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  • 1.
    Abdalmoaty, Mohamed
    KTH, Reglerteknik.
    Learning Stochastic Nonlinear Dynamical Systems Using Non-stationary Linear Predictors2017Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The estimation problem of stochastic nonlinear parametric models is recognized to be very challenging due to the intractability of the likelihood function. Recently, several methods have been developed to approximate the maximum likelihood estimator and the optimal mean-square error predictor using Monte Carlo methods. Albeit asymptotically optimal, these methods come with several computational challenges and fundamental limitations.

    The contributions of this thesis can be divided into two main parts. In the first part, approximate solutions to the maximum likelihood problem are explored. Both analytical and numerical approaches, based on the expectation-maximization algorithm and the quasi-Newton algorithm, are considered. While analytic approximations are difficult to analyze, asymptotic guarantees can be established for methods based on Monte Carlo approximations. Yet, Monte Carlo methods come with their own computational difficulties; sampling in high-dimensional spaces requires an efficient proposal distribution to reduce the number of required samples to a reasonable value.

    In the second part, relatively simple prediction error method estimators are proposed. They are based on non-stationary one-step ahead predictors which are linear in the observed outputs, but are nonlinear in the (assumed known) input. These predictors rely only on the first two moments of the model and the computation of the likelihood function is not required. Consequently, the resulting estimators are defined via analytically tractable objective functions in several relevant cases. It is shown that, under mild assumptions, the estimators are consistent and asymptotically normal. In cases where the first two moments are analytically intractable due to the complexity of the model, it is possible to resort to vanilla Monte Carlo approximations. Several numerical examples demonstrate a good performance of the suggested estimators in several cases that are usually considered challenging.

  • 2.
    Abdel-Hafiez, Mahmoud
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. Univ Sharjah, Res Inst Sci & Engn, Ctr Adv Mat Res, Sharjah, U Arab Emirates.;Univ Sharjah, Dept Appl Phys & Astron, Sharjah, U Arab Emirates..
    Shi, Li Fen
    Chinese Acad Sci, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China.;Chinese Acad Sci, Inst Phys, Beijing 100190, Peoples R China.;Univ Chinese Acad Sci, Sch Phys Sci, Beijing 100190, Peoples R China..
    Cheng, Jinguang
    Chinese Acad Sci, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China.;Chinese Acad Sci, Inst Phys, Beijing 100190, Peoples R China.;Univ Chinese Acad Sci, Sch Phys Sci, Beijing 100190, Peoples R China..
    Gorlova, Irina G.
    RAS, Kotelnikov Inst Radioengn & Elect, Moscow 125009, Russia..
    Zybtsev, Sergey G.
    RAS, Kotelnikov Inst Radioengn & Elect, Moscow 125009, Russia..
    Pokrovskii, Vadim Ya.
    RAS, Kotelnikov Inst Radioengn & Elect, Moscow 125009, Russia..
    Ao, Lingyi
    Nanjing Univ, Coll Engn & Appl Sci, Natl Lab Solid State Microstruct, Nanjing 210000, Peoples R China.;Nanjing Univ, Jiangsu Key Lab Artificial Funct Mat, Nanjing 210000, Peoples R China..
    Huang, Junwei
    Nanjing Univ, Coll Engn & Appl Sci, Natl Lab Solid State Microstruct, Nanjing 210000, Peoples R China.;Nanjing Univ, Jiangsu Key Lab Artificial Funct Mat, Nanjing 210000, Peoples R China..
    Yuan, Hongtao
    Nanjing Univ, Coll Engn & Appl Sci, Natl Lab Solid State Microstruct, Nanjing 210000, Peoples R China.;Nanjing Univ, Jiangsu Key Lab Artificial Funct Mat, Nanjing 210000, Peoples R China..
    Titov, Alexsandr N.
    Russian Acad Sci, MN Miheev Inst Met Phys, Ural Branch, Ekaterinburg 620990, Russia..
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala Univ, WISE Wallenberg Initiat Mat Sci, SE-75120 Uppsala, Sweden..
    Ong, Chin Shen
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    From Insulator to Superconductor: A Series of Pressure-Driven Transitions in Quasi-One-Dimensional TiS3 Nanoribbons2024In: Nano Letters, ISSN 1530-6984, E-ISSN 1530-6992, Vol. 24, no 18, p. 5562-5569Article in journal (Refereed)
    Abstract [en]

    Transition metal trichalcogenides (TMTCs) offer remarkable opportunities for tuning electronic states through modifications in chemical composition, temperature, and pressure. Despite considerable interest in TMTCs, there remain significant knowledge gaps concerning the evolution of their electronic properties under compression. In this study, we employ experimental and theoretical approaches to comprehensively explore the high-pressure behavior of the electronic properties of TiS3, a quasi-one-dimensional (Q1D) semiconductor, across various temperature ranges. Through high-pressure electrical resistance and magnetic measurements at elevated pressures, we uncover a distinctive sequence of phase transitions within TiS3, encompassing a transformation from an insulating state at ambient pressure to the emergence of an incipient superconducting state above 70 GPa. Our findings provide compelling evidence that superconductivity at low temperatures of ∼2.9 K is a fundamental characteristic of TiS3, shedding new light on the intriguing high-pressure electronic properties of TiS3 and underscoring the broader implications of our discoveries for TMTCs in general.

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  • 3.
    Abewardhana, Ruwan
    et al.
    Univ Colombo, Dept Phys, Colombo, Sri Lanka.
    Abegunawardana, Sidath
    Univ Colombo, Dept Phys, Colombo, Sri Lanka.
    Fernando, Mahendra
    Univ Colombo, Dept Phys, Colombo, Sri Lanka.
    Sonnadara, Upul
    Univ Colombo, Dept Phys, Colombo, Sri Lanka.
    Cooray, Vernon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Lightning Localization Based on VHF Broadband Interferometer Developed in Sri Lanka2018In: 2018 34th international conference on lightning protection (ICLP 2018), New York: IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    A basic broadband digital interferometer was developed, which is capable of locating Very High Frequency (VHF) radiation sources in two spatial dimensions and time. Three antennas sensed the time series of broadband electromagnetic (EM) signals and digitized with 4 ns sampling interval for a duration of several milliseconds. A technique based on cross-correlations has been implemented for mapping lightning source locations. A map of the first return stroke (RS) and the preceding stepped leader was mapped successfully, using the system with a time resolution of few milliseconds. The result was compared with the visible events of the ground flash to validate the system.

  • 4.
    Abrahamsson, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Hedlund, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Kamf, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bernhoff, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    High-Speed Kinetic Energy Buffer: Optimization of Composite Shell and Magnetic Bearings2014In: IEEE Transactions on Industrial Electronics, ISSN 0278-0046, E-ISSN 1557-9948, Vol. 61, no 6, p. 3012-3021Article in journal (Refereed)
    Abstract [en]

    This paper presents the design and optimization of a high-speed (30 000 r/min) kinetic energy storage system. The purpose of the device is to function as an energy buffer storing up to 867 Wh, primarily for utility vehicles in urban traffic. The rotor comprises a solid composite shell of carbon and glass fibers in an epoxy matrix, constructed in one curing. The shell is optimized using a combined analytical and numerical approach. The radial stress in the shell is kept compressive by integrating the electric machine, thereby avoiding delamination. Radial centering is achieved through eight active electromagnetic actuators. The actuator geometry is optimized using a direct coupling between SolidWorks, Comsol, and Matlab for maximum force over resistive loss for a given current density. The optimization results in a system with 300% higher current stiffness than the reference geometry with constant flux area, at the expense of 33% higher power loss. The actuators are driven by semipassive H bridges and controlled by an FPGA. Current control at 20 kHz with a noise of less than 5 mA (95% CI) is achieved, allowing position control at 4 kHz to be implemented.

  • 5.
    Abro, Mehwish
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Modelling the exfoliation of graphite for production of graphene2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of my thesis is to make a theoretical model of data obtained from liquid-phase exfoliation of graphene. The production of graphene in the liquid phase exfoliation is a cost efficient method One part of this work is devotedto learn the method of production of graphene by the shear mixing technique from the graphite and to estimate some important parameters which are crucial for the process. Other part of my work is based on studying the liquid-phase exfoliation mechanism of graphene through ultrasonication technique. This method is time consuming as compared to shearmixing.

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  • 6.
    Adeleye, Damilola
    et al.
    Univ Luxembourg, Esch Sur Alzette, Luxembourg.
    Sood, Mohit
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology. University of Luxembourg, Esch-sur-Alzette, Luxembourg.
    Hultqvist, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology. University of Luxembourg, Esch-sur-Alzette, Luxembourg.
    Vanderhaegen, Aline
    Melchiorre, Michele
    Siebentritt, Susanne
    Mitigation of Phase Separation in High Ga Cu(In,Ga)S2 Absorbers to Achieve ∼ 1 Volt 15.6% Power Conversion Efficiency2023In: 2023 IEEE 50th Photovoltaic Specialists Conference (PVSC), Institute of Electrical and Electronics Engineers (IEEE), 2023Conference paper (Refereed)
    Abstract [en]

    The use of Cu(In,Ga)S2 as a top cell in tandem solar cell, despite having suitable properties for such an application, is hampered by a high open-circuit voltage (VOC) deficit. The deficit arises from a poor optoelectronic quality of the absorbers - engendered by phase separation - and the inadequate translation of the optoelectronic quality of the absorber into device VOC. In this work, we report the role of first stage substrate temperature in the mitigation of phase separation and optimized Cu-excess during growth in Cu(In,Ga)S2, which leads to reduced VOC deficit, resulting in a device with 15.6 % PCE with a VOC of ∼ 981 mV when completed with atomic layer deposited (Zn,Sn)O and Al:ZnMgO transparent conductive oxide.

  • 7.
    Adolfsson, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Developing a Graphical Application to Control Stepper Motors with Sensorless Load Detection2021Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    For positioning of linear stages in absolute coordinates, there is a general need to find a reference position since the initial one is unknown. This is commonly called homing. To reduce costs and facilitate assembly, homing can be performed without additional sensors, known as sensorless homing. This thesis delves into sensorless homing, specifically with respect to stepper motors, and develops a graphical application for control of them. The commercial technology StallGuard is applied inconjunction with exploration into how it – and sensorless load detectionin general – functions. The resulting graphical application can be used to configure the stepper motors, perform homing using StallGuard, and automatically tune StallGuard to work despite varying conditions. In addition, rudimentary sensorless load detection independent from StallGuard is developed, demonstrating how it could work in practice. Testing shows homing with StallGuard resulting in a position within a ±5μm window in 94% of cases, less than 1/7 the width of an average strand of human hair. Additionally, homing is easily performed with a single button press from the graphical interface, with optional additional configuration available.

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  • 8.
    Adrian, Ehrnebo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Single Crystalline CVD Diamond Based Devices for Power Electronics Applications2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Chemical vapor deposited single-crystalline diamond has rare material properties such as thermal conductivity five times as high as copper, a wide band gap, a high breakdown field and high carrier mobilities. This makes it a very interesting material for high power, high frequency and high temperature applications.

    In this thesis work, metal oxide semiconductor (MOS) capacitors of diamond substrate were fabricated and analyzed. The MOS capacitor is a building block of the metal oxide semiconductor field effect transistor (MOSFET). Capacitance-voltage (C-V) measurements can provide useful information of the operation of a MOS. Electrical characterization by C-V and current-voltage (I-V) measurements at temperatures ranging from 20 to 150 degrees Celsius were performed on the MOS capacitors to examine flatband and threshold voltages, oxide charge, and oxide thickness.

    At elevated temperatures, low frequency C-V curves with threshold voltages of approximately 5 V were obtained for MOS capacitors consisting of aluminum gates, a 30 nm layer of aluminum oxide, and boron doped diamond with acceptor concentration 3.1 x 1017 cm-3. The C-V measurements also showed large variations in flatband voltage for different contacts of the MOS capacitor, indicating the presence of oxide charge. Oxide thickness was also extracted from the C-V measurements, typically showing thicknesses around 15-19 nm.

    Also in this  thesis, an alternative method for reducing the electric field strength around the edges of the contact of a Schottky diode has been examined. This method consists of alternating the geometry by etching the semiconductor where the contact is to be placed. Simulations performed in Comsol Multiphysics showed that a reduction of the field strength of approximately 30 % at the contacts could be achieved by etching the substrate.

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  • 9.
    Ahlberg, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Graphene Implementation Study in Semiconductor Processing2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Graphene, with its two-dimensional nature and unique properties, has for over a decade captured enormous interests in both industry and academia. This work tries to answer the question of what would happen to graphene when it is subjected to various processing conditions and how this would affect the graphene functionality. The focus is placed on its ability to withstand different thin-film deposition environments with regard to the implementation of graphene in two application areas: as a diffusion barrier and in electronic devices.

    With single-layer graphene films grown in-house by means of chemical vapor deposition (CVD), four techniques among the well-established thin-film deposition methods are studied in detail: atomic layer deposition (ALD), evaporation, sputter-deposition and spray-deposition. And in this order, these methods span a large range of kinetic impact energies from low to high. Graphene is known to have a threshold displacement energy of 22 eV above which carbon atoms are ejected from the lattice. Thus, ALD and evaporation work with energies below this threshold, while sputtering and spraying may involve energies above. The quality of the graphene films undergone the various depositions is mainly evaluated using Raman spectroscopy.

    Spray deposition of liquid alloy Ga-In-Sn is shown to require a stack of at least 4 layers of graphene in order to act as an effective barrier to the Ga diffusion after the harsh spray-processing. Sputter-deposition is found to benefit from low substrate temperature and high chamber pressure (thereby low kinetic impact energy) so as to avoid damaging the graphene. Reactive sputtering should be avoided. Evaporation is non-invasiveness with low kinetic impact energy and graphene can be subjected to repeated evaporation and removal steps without losing its integrity. With ALD, the effects on graphene are of different nature and they are investigated in the field-effect-transistor (FET) configuration. The ALD process for deposition of Al2O3 films is found to remove undesired dopants from the prior processing and the Al2O3 films are shown to protect the graphene channel from doping by oxygen. When the substrate is turned hydrophobic by chemical treatment prior to graphene transfer-deposition, a unipolar transistor behavior is obtained.

    List of papers
    1. A two-in-one process for reliable graphene transistors processed with photolithography
    Open this publication in new window or tab >>A two-in-one process for reliable graphene transistors processed with photolithography
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    2015 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 107, no 20, article id 203104Article in journal (Refereed) Published
    Abstract [en]

    Research on graphene field-effect transistors (GFETs) has mainly relied on devices fabricated using electron-beam lithography for pattern generation, a method that has known problems with polymer contaminants. GFETs fabricated via photo-lithography suffer even worse from other chemical contaminations, which may lead to strong unintentional doping of the graphene. In this letter, we report on a scalable fabrication process for reliable GFETs based on ordinary photo-lithography by eliminating the aforementioned issues. The key to making this GFET processing compatible with silicon technology lies in a two-in-one process where a gate dielectric is deposited by means of atomic layer deposition. During this deposition step, contaminants, likely unintentionally introduced during the graphene transfer and patterning, are effectively removed. The resulting GFETs exhibit current-voltage characteristics representative to that of intrinsic non-doped graphene. Fundamental aspects pertaining to the surface engineering employed in this work are investigated in the light of chemical analysis in combination with electrical characterization.

    National Category
    Physical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-269191 (URN)10.1063/1.4935985 (DOI)000365688700049 ()
    Funder
    Knut and Alice Wallenberg Foundation, 2011.0113, 2011.0082Swedish Foundation for Strategic Research , SE13-0061Swedish Research Council, 621-2014-5591
    Available from: 2015-12-14 Created: 2015-12-14 Last updated: 2017-12-01Bibliographically approved
    2. Interface Dependent Effective Mobility in Graphene Field Effect Transistors
    Open this publication in new window or tab >>Interface Dependent Effective Mobility in Graphene Field Effect Transistors
    2018 (English)In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 47, no 3, p. 1757-1761Article in journal (Refereed) Published
    Abstract [en]

    By pretreating the substrate of a graphene field-effect transistor (G-FET), a stable unipolar transfer characteristic, instead of the typical V-shape ambipolar behavior, has been demonstrated. This behavior is achieved through functionalization of the SiO2/Si substrate that changes the SiO2 surface from hydrophilic to hydrophobic, in combination with postdeposition of an Al2O3 film by atomic layer deposition (ALD). Consequently, the back-gated G-FET is found to have increased apparent hole mobility and suppressed apparent electron mobility. Furthermore, with addition of a top-gate electrode, the G-FET is in a double-gate configuration with independent top- or back-gate control. The observed difference in mobility is shown to also be dependent on the top-gate bias, with more pronounced effect at higher electric field. Thus, the combination of top and bottom gates allows control of the G-FET's electron and hole mobilities, i.e., of the transfer behavior. Based on these observations, it is proposed that polar ligands are introduced during the ALD step and, depending on their polarization, result in an apparent increase of the effective hole mobility and an apparent suppressed effective electron mobility.

    National Category
    Engineering and Technology Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-284924 (URN)10.1007/s11664-017-6023-6 (DOI)000424341700002 ()
    Funder
    Knut and Alice Wallenberg Foundation, 2011.0082Swedish Research Council, 2014-5591
    Available from: 2016-04-19 Created: 2016-04-19 Last updated: 2018-04-11Bibliographically approved
    3. Defect formation in graphene during low-energy ion bombardment
    Open this publication in new window or tab >>Defect formation in graphene during low-energy ion bombardment
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    2016 (English)In: APL Materials, E-ISSN 2166-532X, Vol. 4, no 4, article id 046104Article in journal, Letter (Refereed) Published
    Abstract [en]

    This letter reports on a systematic investigation of sputter induced damage in graphene caused by low energy Ar+ ion bombardment. The integral numbers of ions per area (dose) as well as their energies are varied in the range of a few eV's up to 200 eV. The defects in the graphene are correlated to the dose/energy and different mechanisms for the defect formation are presented. The energetic bombardment associated with the conventional sputter deposition process is typically in the investigated energy range. However, during sputter deposition on graphene, the energetic particle bombardment potentially disrupts the crystallinity and consequently deteriorates its properties. One purpose with the present study is therefore to demonstrate the limits and possibilities with sputter deposition of thin films on graphene and to identify energy levels necessary to obtain defect free graphene during the sputter deposition process. Another purpose is to disclose the fundamental mechanisms responsible for defect formation in graphene for the studied energy range.

    National Category
    Materials Chemistry Nano Technology
    Identifiers
    urn:nbn:se:uu:diva-284702 (URN)10.1063/1.4945587 (DOI)000375846100007 ()
    Funder
    Knut and Alice Wallenberg Foundation, 2011.0082Swedish Research Council, 2014-5591 2014-6463
    Available from: 2016-04-19 Created: 2016-04-19 Last updated: 2023-10-17Bibliographically approved
    4. Toward synthesis of oxide films on graphene with sputtering based processes
    Open this publication in new window or tab >>Toward synthesis of oxide films on graphene with sputtering based processes
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    2016 (English)In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 34, no 4, article id 040605Article in journal (Refereed) Published
    Abstract [en]

    The impact of energetic particles associated with a sputter deposition process may introduce damage to single layer graphene films, making it challenging to apply this method when processing graphene. The challenge is even greater when oxygen is incorporated into the sputtering process as graphene can be readily oxidized. This work demonstrates a method of synthesizing ZnSn oxide on graphene without introducing an appreciable amount of defects into the underlying graphene. Moreover, the method is general and applicable to other oxides. The formation of ZnSn oxide is realized by sputter deposition of ZnSn followed by a postoxidation step. In order to prevent the underlying graphene from damage during the initial sputter deposition process, the substrate temperature is kept close to room temperature, and the processing pressure is kept high enough to effectively suppress energetic bombardment. Further, in the subsequent postannealing step, it is important not to exceed temperatures resulting in oxidation of the graphene. The authors conclude that postoxidation of ZnSn is satisfactorily performed at 300 degrees C in pure oxygen at reduced pressure. This process results in an oxidized ZnSn film while retaining the initial quality of the graphene film.

    National Category
    Engineering and Technology Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-303391 (URN)10.1116/1.4949565 (DOI)000382207700005 ()
    Funder
    Knut and Alice Wallenberg Foundation, 2011.0082Swedish Research Council, 2014-5591
    Available from: 2016-09-19 Created: 2016-09-19 Last updated: 2023-11-21Bibliographically approved
    5. Graphene as a Diffusion Barrier in Galinstan-Solid Metal Contacts
    Open this publication in new window or tab >>Graphene as a Diffusion Barrier in Galinstan-Solid Metal Contacts
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    2014 (English)In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 61, no 8, p. 2996-3000Article in journal (Refereed) Published
    Abstract [en]

    This paper presents the use of graphene as a diffusion barrier to a eutectic Ga-In-Sn alloy, i.e., galinstan, for electrical contacts in electronics. Galinstan is known to be incompatible with many conventional metals used for electrical contacts. When galinstan is in direct contact with Al thin films, Al is readily dissolved leading to the formation of Al oxides present on the surface of the galinstan droplets. This reaction is monitored ex situ using several material analysis methods as well as in situ using a simple circuit to follow the time-dependent resistance variation. In the presence of a multilayer graphene diffusion barrier, the Al-galinstan reaction is effectively prevented for galinstan deposited by means of drop casting. When deposited by spray coating, the high-impact momentum of the galinstan droplets causes damage to the multilayer graphene and the Al-galinstan reaction is observed at some defective spots. Nonetheless, the graphene barrier is likely to block the formation of Al oxides at the Al/galinstan interface leading to a stable electrical current in the test circuit.

    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering Nano Technology
    Research subject
    Engineering Science with specialization in Electronics; Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-229503 (URN)10.1109/TED.2014.2331893 (DOI)000342906200056 ()
    Available from: 2014-08-10 Created: 2014-08-10 Last updated: 2017-12-05Bibliographically approved
    6. Scalable residue-free graphene for surface-enhanced Raman scattering
    Open this publication in new window or tab >>Scalable residue-free graphene for surface-enhanced Raman scattering
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    2016 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 98, p. 567-571Article in journal (Refereed) Published
    Abstract [en]

    A room-temperature polymer-assisted transfer process is developed for large-area, single-layer graphene grown by means of chemical vapor deposition (CVD). This process leads to transferred graphene layers free of polymer contamination. The absence of polymer residues boosts the surface-enhanced Raman scattering (SERS) of the CVD graphene with gold nanoparticles (Au NPs) deposited atop by evaporation. The SERS enhancement of the CVD graphene reaches similar to 120 for the characteristic 2D peak of graphene, the highest enhancement factor achieved to date, when the Au NPs are at the threshold of percolation. Our simulation supported by experiment suggests that the polymer residues persistently present on the graphene transferred by the conventional polymer-assisted method are equivalent to an ultrathin film of less than 1 nm thickness. The presence of polymer residues drastically reduces SERS due to the separation of the Au NPs from the underlying graphene. The scalability of CVD graphene opens up for the possibility of graphene-based SERS sensors.

    National Category
    Physical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-269192 (URN)10.1016/j.carbon.2015.11.043 (DOI)000367233000070 ()
    Funder
    Knut and Alice Wallenberg Foundation, 2011.0113Knut and Alice Wallenberg Foundation, 2011.0082Swedish Foundation for Strategic Research , SE13-0061Swedish Research Council, 621-2014-5591
    Available from: 2015-12-14 Created: 2015-12-14 Last updated: 2017-12-01Bibliographically approved
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  • 10.
    Ahlberg, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Seung, Hee Jeong
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jiao, Mingzhi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Graphene as a Diffusion Barrier in Galinstan-Solid Metal Contacts2014In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 61, no 8, p. 2996-3000Article in journal (Refereed)
    Abstract [en]

    This paper presents the use of graphene as a diffusion barrier to a eutectic Ga-In-Sn alloy, i.e., galinstan, for electrical contacts in electronics. Galinstan is known to be incompatible with many conventional metals used for electrical contacts. When galinstan is in direct contact with Al thin films, Al is readily dissolved leading to the formation of Al oxides present on the surface of the galinstan droplets. This reaction is monitored ex situ using several material analysis methods as well as in situ using a simple circuit to follow the time-dependent resistance variation. In the presence of a multilayer graphene diffusion barrier, the Al-galinstan reaction is effectively prevented for galinstan deposited by means of drop casting. When deposited by spray coating, the high-impact momentum of the galinstan droplets causes damage to the multilayer graphene and the Al-galinstan reaction is observed at some defective spots. Nonetheless, the graphene barrier is likely to block the formation of Al oxides at the Al/galinstan interface leading to a stable electrical current in the test circuit.

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  • 11. Ahlgren Peters, Adam
    et al.
    Söderholm, Robin
    Wahlmark, Rickard
    Analog gitarrförstärkare: med rörliknande egenskaper2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
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  • 12.
    Ahlström, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Åsktransienter och överspänningar: En spänningsfylld simulering av elkraftsystemet vid Forsmark 32014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A power system will inevitably be subjected to transient overvoltages, most often produced by switching operations and lightning strikes. These transient overvoltages may harm sensitive equipment without sufficient protection, but it is not an easy task to predict what transients may occur or how they affect the system. A fault occurred in a low voltage system at Forsmark 2012 and overvoltages from lightning were concluded as the probable cause. The three aims with this thesis are to develop and test a model of the power system at Forsmark 3, analyse the transient behaviour of the system when subjected to lightning surges and identify critical parameters, and lastly to provide a tool for investigating the protection of the system. The modelling and simulations were performed in the freely available simulation program LT Spice. Challenges and difficulties have been to obtain parameter values for components that are relevant for the high frequencies produced by the short rise time in lightning surges. The main conclusions are: the maximum current in the lightning discharge has the largest impact on the system voltages and surges in the external grid can produce standing waves in the system, causing significant overvoltages even in low voltage systems. The simulations produced larger overvoltages than would occur in a real system, which also would dampen the high frequency signals to a larger extent. Further work to obtain models better suited for high frequency simulation is suggested.

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    EXAMENSARBETE ERIK AHLSTRÖM
  • 13.
    Ahmad, Mohd Riduan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Universiti Teknikal Malaysia Melaka.
    Interaction of Lightning Flashes with Wireless Communication Networks: Special Attention to Narrow Bipolar Pulses2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, the features of electric field signatures of narrow bipolar pulses (NBPs) generated by cloud flashes are investigated and their effects on wireless communication systems are studied. A handful amount of NBPs (14.5%) have been observed to occur as part of cloud-to-ground flashes in South Malaysia. Occurrence of NBPs in Sweden has been reported for the first time in this thesis. The electric field waveform characteristics of NBPs as part of cloud-to-ground flashes were similar to isolated NBPs found in Sweden and South Malaysia and also to those isolated NBPs reported by previous studies from various geographical areas. This is a strong indication that their breakdown mechanisms are similar at any latitudes regardless of geographical areas.

    A comparative study on the occurrence of NBPs and other forms of lightning flashes across various geographical areas ranging from northern regions to the tropics is presented. As the latitude decreased from Uppsala, Sweden (59.8°N) to South Malaysia (1.5°N), the percentage of NBP emissions relative to the total number of lightning flashes increased significantly from 0.13% to 12%. Occurrences of positive NBPs were more common than negative NBPs at all observed latitudes. However, as latitudes decreased, the negative NBP emissions increased significantly from 20% (Sweden) to 45% (South Malaysia). Factors involving mixed-phase region elevations and vertical extents of thundercloud tops are invoked to explain the observed results. These factors are fundamentally latitude dependent.

    In this thesis, the interaction between microwave radiations emitted by cloud-to-ground and cloud flashes events and bits transmission in wireless communication networks are also presented. To the best of our knowledge, this is the first time such effects are investigated in the literature. Narrow bipolar pulses were found to be the strongest source of interference that interfered with the bits transmission.

    List of papers
    1. Signatures of Narrow Bipolar Pulses as Part of Cloud-to-Ground Flashes in Tropical Thunderstorms
    Open this publication in new window or tab >>Signatures of Narrow Bipolar Pulses as Part of Cloud-to-Ground Flashes in Tropical Thunderstorms
    2014 (English)In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824Article in journal (Refereed) Submitted
    Keywords
    Narrow bipolar pulse; Return stroke; Tropical thunderstorm.
    National Category
    Meteorology and Atmospheric Sciences Engineering and Technology
    Research subject
    Engineering Science with specialization in Atmospheric Discharges
    Identifiers
    urn:nbn:se:uu:diva-233624 (URN)
    Available from: 2014-10-07 Created: 2014-10-07 Last updated: 2017-12-05
    2. Narrow bipolar pulses and associated microwave radiation
    Open this publication in new window or tab >>Narrow bipolar pulses and associated microwave radiation
    2013 (English)Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Stockholm: , 2013
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Science of Electricity
    Identifiers
    urn:nbn:se:uu:diva-212898 (URN)
    Conference
    Progress in Electromagnetics Research Symposium
    Available from: 2013-12-16 Created: 2013-12-16 Last updated: 2015-01-23
    3. Electric Field Signature of Narrow Bipolar Pulse Observed in Sweden
    Open this publication in new window or tab >>Electric Field Signature of Narrow Bipolar Pulse Observed in Sweden
    Show others...
    2014 (English)Manuscript (preprint) (Other academic)
    Keywords
    Electric field; Narrow bipolar pulse; Sweden.
    National Category
    Meteorology and Atmospheric Sciences Engineering and Technology
    Research subject
    Engineering Science with specialization in Atmospheric Discharges
    Identifiers
    urn:nbn:se:uu:diva-233636 (URN)
    Available from: 2014-10-07 Created: 2014-10-07 Last updated: 2024-04-03
    4. Latitude Dependence of Narrow Bipolar Pulse Emissions
    Open this publication in new window or tab >>Latitude Dependence of Narrow Bipolar Pulse Emissions
    Show others...
    2015 (English)In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 128, p. 40-45Article in journal (Refereed) Published
    Keywords
    Latitude; Narrow bipolar pulse; Thunderstorm.
    National Category
    Meteorology and Atmospheric Sciences Engineering and Technology
    Research subject
    Engineering Science with specialization in Atmospheric Discharges
    Identifiers
    urn:nbn:se:uu:diva-233638 (URN)10.1016/j.jastp.2015.03.005 (DOI)000355717500005 ()
    Available from: 2014-10-07 Created: 2014-10-07 Last updated: 2017-12-05Bibliographically approved
    5. Similarity between the Initial Breakdown Pulses of Negative Ground Flash and Narrow Bipolar Pulses
    Open this publication in new window or tab >>Similarity between the Initial Breakdown Pulses of Negative Ground Flash and Narrow Bipolar Pulses
    2014 (English)In: 2014 INTERNATIONAL CONFERENCE ON LIGHTNING PROTECTION (ICLP), IEEE conference proceedings, 2014, p. 810-813Conference paper, Published paper (Refereed)
    Abstract [en]

    In this paper, temporal characteristics of several initial electric field pulses of preliminary breakdown process (PBP) from very close negative cloud-to-ground (CG) flashes are compared to close narrow bipolar pulses (NBPs) to observe any similarity that may exists. Interestingly, we found that the initial PBP pulses are similar to close NBP with zero crossing time less than 5 mu s, do not preceded by any slow field change and followed by pronounce static component. As NBPs are believed to be a result of relativistic runaway electron avalanches discharge, this finding is an indication that the initial electric field pulses of PBP are perhaps the result of the same discharge mechanism.

    Place, publisher, year, edition, pages
    IEEE conference proceedings, 2014
    Keywords
    Narrow bipolar pulse; Preliminary breakdown pulse; Relativistic runaway electron avalanches.
    National Category
    Meteorology and Atmospheric Sciences Engineering and Technology
    Research subject
    Engineering Science with specialization in Atmospheric Discharges
    Identifiers
    urn:nbn:se:uu:diva-233639 (URN)000358572100153 ()978-1-4799-3544-4 (ISBN)
    Conference
    International Conference on Lightning Protection (ICLP), OCT 11-18, 2014, Tsinghua Univ, Shanghai, PEOPLES R CHINA
    Available from: 2014-10-07 Created: 2014-10-07 Last updated: 2015-09-03Bibliographically approved
    6. Lightning interference in multiple antennas wireless communication systems
    Open this publication in new window or tab >>Lightning interference in multiple antennas wireless communication systems
    Show others...
    2012 (English)In: Journal of Lightning Research, ISSN 1652-8034, Vol. 4, p. 155-165Article in journal (Refereed) Published
    Abstract [en]

    This paper analyzes the interference of lightning flashes with multiple antennas wireless communicationsystems operating in the microwave band at 2.4 GHz and 5.2 GHz. A bit error rate (BER) measurement method was usedto evaluate BER and packet error rate (PER) during 5 heavy thunderstorms on January 25 and March 17 to 20, 2011,respectively. In addition, BER measurements also were done on January 21 and March 30, 2011 under fair weather (FW)conditions providing a baseline for comparison. The Transmitter-Receiver separation was fixed at 10 meter with line-ofsight(LOS) consideration. We infer that lightning interfered with the transmitted digital pulses which resulted in a higherrecorded BER. The maximum recorded BER was 9.9·10-1 and the average recorded BER and PER were 2.07·10-2 and2.44·10-2 respectively during the thunderstorms with the average fair weather BER and PER values under the influence ofadjacent channel interference (ACI) and co-channel interference (CCI) being 1.75·10-5 and 7.35·10-6 respectively. Weconclude that multiple antennas wireless communication systems operating at the microwave frequency can besignificantly interfered by lightning.

    Place, publisher, year, edition, pages
    Bentham open, 2012
    National Category
    Meteorology and Atmospheric Sciences Engineering and Technology
    Research subject
    Engineering Science with specialization in Atmospheric Discharges
    Identifiers
    urn:nbn:se:uu:diva-190902 (URN)
    Available from: 2013-01-09 Created: 2013-01-09 Last updated: 2016-02-03
    7. Interference from cloud-to-ground and cloud flashes in wireless communication system
    Open this publication in new window or tab >>Interference from cloud-to-ground and cloud flashes in wireless communication system
    2014 (English)In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 113, p. 237-246Article in journal (Refereed) Published
    Abstract [en]

    In this study, cloud-to-ground (CG) flash and intra-cloud (IC) flash events that interfere with the transmission of bits in wireless communication system operating at 2.4 GHz were analyzed. Bit error rate (BER) and consecutive lost datagram (CLD) measurement methods were used to evaluate BER and burst error from 3 tropical thunderstorms on November 27, 28, and 29 during 2012 northeastern monsoon in Malaysia. A total of 850 waveforms from the electric field change recording system were recorded and examined. Out of these, 94 waveforms of very fine structure were selected which matched perfectly with the timing information of the recorded BER. We found that both CG and IC flashes interfered significantly with the transmission of bits in wireless communication system. The severity of the interference depends mainly on two factors namely the number of pulses and the amplitude intensity of the flash. The interference level becomes worst when the number of pulses in a flash increases and the amplitude intensity of pulses in a flash intensifies. During thunderstorms, wireless communication system has experienced mostly intermittent interference due to burst error. Occasionally, in the presence of very intense NBP event, wireless communication system could experience total communication lost. In CG flash, it can be concluded that PBP is the major. source of interference that interfered with the bits transmission and caused the largest burst error. In IC flash, we found that the typical IC pulses interfered the bits transmission in the same way as PBP and mixed events in CG flash and produced comparable and in some cases higher amount of burst error. NBP has been observed to interfere the bits transmission more severely than typical IC and CG flashes and caused the most severe burst error to wireless communication system.

    Keywords
    Bit error rate, Cloud flash, Cloud-to-ground flash, Interference, Microwave radiation, Wireless system
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-228679 (URN)10.1016/j.epsr.2014.03.022 (DOI)000337554200032 ()
    Available from: 2014-07-22 Created: 2014-07-21 Last updated: 2017-12-05Bibliographically approved
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  • 14.
    Ahmed, Ubaid
    et al.
    Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur, Pakistan..
    Muhammad, Rasheed
    Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur, Pakistan..
    Abbas, Syed Sami
    Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur, Pakistan..
    Aziz, Imran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur, Pakistan..
    Mahmood, Anzar
    Mirpur Univ Sci & Technol, Dept Elect Engn, Mirpur, Pakistan..
    Short-term wind power forecasting using integrated boosting approach2024In: Frontiers in Energy Research, E-ISSN 2296-598X, Vol. 12, article id 1401978Article in journal (Refereed)
    Abstract [en]

    Rapidly increasing global energy demand and environmental concerns have shifted the attention of policymakers toward the large-scale integration of renewable energy resources (RERs). Wind energy is a type of RERs with vast energy potential and no environmental pollution is associated with it. The sustainable development goals: affordable and clean energy, climate action, and industry, innovation and infrastructure, can be achieved by integrating wind energy into the existing power systems. However, the integration of wind energy will bring instability challenges due to its intermittent nature. Mitigating these challenges necessitates the implementation of effective wind power forecasting models. Therefore, we have proposed a novel integrated approach, Boost-LR, for hour-ahead wind power forecasting. The Boost-LR is a multilevel technique consisting of non-parametric models, extreme gradient boosting (XgBoost), categorical boosting (CatBoost), and random forest (RF), and parametric approach, linear regression (LR). The first layer of the Boost-LR uses the boosting algorithms that process the data according to their tree development architectures and pass their intermediary forecast to LR which is deployed in layer two and processes the intermediary forecasts of layer one models to provide the final predicted wind power. To demonstrate the generalizability and robustness of the proposed study, the performance of Boost-LR is compared with the individual models of CatBoost, XgBoost, RF, deep learning networks: long short-term memory (LSTM) and gated recurrent unit (GRU), Transformer and Informer models using root mean square error (RMSE), mean square error (MSE), mean absolute error (MAE) and normalized root mean square error (NRMSE). Findings demonstrate the effectiveness of the Boost-LR as its forecasting performance is superior to the compared models. The improvement in MAE of Boost-LR is recorded as to be 31.42%, 32.14%, and 27.55% for the datasets of Bruska, Jelinak, and Inland wind farm, respectively as compared to the MAE of CatBoost which is revealed as the second-best performing model. Moreover, the proposed study also reports a literature comparison that further validates the effectiveness of Boost-LR performance for short-term wind power forecasting.

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    FULLTEXT01
  • 15.
    Al Kzair, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    SiC MOSFET function in DC-DC converter2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis evaluate the state of art ROHM SCT3080KR silicon carbide mosfet in a synchronous buck converter. The converter was using the ROHM P02SCT3040KR-EVK-001 evaluation board for driving the mosfets in a half bridge configuration. Evaluation of efficiency, waveforms, temperature and a theoretical comparison between a silicon mosfet (STW12N120K5) is done. For the efficiency test the converter operate at 200 V input voltage and 100 V output voltage at output currents of 7 A to 12 A, this operation was tested at switching frequencies of 50 kHz, 80 kHz and 100 kHz. The result of the efficiency test showed an efficiency of 98-97 % for 50 kHz, 97.7-96.4 % for 80 kHz and 97-96.2 % for the 100 kHz test. The temperature test shows a small difference in comparison of the best case scenario and the worst case scenario, temperature ranges from 25.5 to 33.5 °C for the high side mosfet while the low side mosfet temperature ranges from 29.8 to 35 °C. The waveform test was conducted at 50 kHz and 100 kHz for output currents of 4 A and 12 A (at 200 V input and 100 V output). The result of the waveform test shows a rise and fall time of the voltages in range of 10-12 ns while the current rise and fall time was 16 ns for the 4 A test and 20 ns for the 12 A test. Overall SiC mosfet show a clear advantage over silicon mosfet in terms of efficiency and high power capabilities.

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  • 16.
    Alahmad, Bashar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering.
    The role of location of low inertia in power systems2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The plans to reduce the energy-related greenhouse gas emissions stimulate the deployment of electronically interfaced renewable resources. The increased penetration of such intermittent sources together with phasing conventional power plants out and the installation of High Voltage Direct Current (HVDC) links for long-distance more efficient transmission, reduces the stored inertia in any electrical grid. This leads to a more vulnerable power system and increases the significance of studying the corresponding stability aspects. Decreasing the inertial response of a power system deteriorates the quality of both frequency and rotor-angle stability which are the dynamics of interest in this study.

    The thesis explores the role of the location of low inertia on varying the power system’s dynamics. This is to be conducted in isolation of all other factors that could affect the study outcomes, such as dealing with the same system’s inertia value upon lowering the inertia in different locations. To accomplish this objective, it is essential to analyze the inertia distribution of the examined power system following the alterations of inertia reduction location. Accordingly, an inherently previous work methodology, that estimates the relative distance of the system’s components to Center Of Inertia (COI), is utilized throughout this study. Both frequency response and small-signal stability are analyzed in light of the inertia distribution results.

    The thesis examines two different power systems, a small two-area model and a bigger more realistic power system. The former model, known as Kundur model, helps in building a conceptual process to apply the methodology and to benchmark the dynamics of interest. While the latter is a reduced model of the Swedish transmission grid, known as Nordic 32 model. Different scenarios of low inertia are considered to capture the current trend of integrating more Renewable Energy Sources (RES) and phasing out more conventional plants. DIgSILENT Powerfactory is the weapon of choice in this study. It is utilized to assess both the frequency stability by performing electromechanical transients’ simulations, and small-signal stability following modal analysis simulations. 

    Results show that the alterations of low inertia location are associated with variations in Instantaneous Frequency Deviation (IFD), Rate Of Change Of Frequency (ROCOF) and the damping ratio of the most critical inter-area oscillation mode. These variations have different levels of significance. Variations of the latter two metrics have the most considerable effects from the stability’s perspective. They can be utilized to prioritize the phasing out process of the conventional power plants, and to choose one of the scenarios of a specific low inertia location over the others. This helps in fulfilling proper long-term planning and short-term operation from the system operator’s perspective.

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  • 17.
    Alfredsson, Hampus
    et al.
    RISE Research Institutes of Sweden.
    Ollas, Patrik
    RISE Research Institutes of Sweden.
    Ghaem Sigarchian, Sara
    RISE Research Institutes of Sweden.
    Aalhuizen, Christoffer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Leijon, Jennifer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Thomas, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Transportation Goes Electric – Exploring the Potential of Smart Charging Strategies for Airports2023Conference paper (Refereed)
    Abstract [en]

    Transport electrification continuously increases globally and propagates to new, even-larger vehicle applications due to decreased costs, battery technology improvements, and charging infrastructure rollout. This work highlights the importance of strategic planning for large electric vehicle charging nodes, like depots, terminals, airports and ports. Specifically from the perspective of predicting future power requirements and how to satisfy energy demand using a combination of smart charging algorithms, local photovoltaic electricity production and battery energy storage systems. A case study is presented where developed tools and models are applied to an airport for high-power charging of future electric aircraft.

  • 18.
    Al-hadi, Mahmood
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering.
    Smart shading regulated by the time at specific voltage2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
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  • 19.
    Alhoush, George
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Measuring bacterial metabolism and antibioticsusceptibility: using silicon nanowire field-effect transistor.2024Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Antimicrobial resistance is considered by many prominent researcher and scientist as a profound global health crisis that us humans must face in the next decade. It is threatening the effectiveness of these once-reliable weapons against bacterial infections and leaving us susceptible to pathogenic agents. The indiscriminate overprescription of antibiotic in healthcare and animal husbandry, has led to an increased emergence of “super bugs”— a resistant strain of bacteria that were once susceptible to antibiotic—. The escalating creation of those resistant bacteria has been coupled with a proliferation of research papers that seek to explain the working mechanism of antibiotics and their efficacy on the bacterial pathogens, however these efforts often fall short of explaining the impact that antibiotics has on the bacterial metabolism.

    This project utilizes an established technology, specifically silicone nano-wire ion-selective field-effect transistor in an innovative approach to discern alteration in the metabolic pathways induced by various antibiotics. The methodology involves measuring extracellular acidity of the tested culture and converting it to an electrical signal to extract valuable information about the metabolic process of the bacteria, and how is altered in the presence of antibiotics.

    Empirical observations pertaining bacteriostatic antibiotics suggests comprehensive suppression of metabolic pathways, encompassing the efflux transition from acetyl-CoA to acetate, resulting an elevated pH level in cultures treated with bacteriostatic agents relative to their wild-type counterparts.

    Our experimental data also indicates a shift in bacterial metabolic and physiological responses to bactericidal antibiotic-induced stress which include an increased respiration rate, and a heightened activity of the TCA cycle in the test group with bactericidal antibiotics, causing acetate uptake from the medium and decelerating the acidification of the treated culture compared to the wild-type.

    The results clearly demonstrate a successful utilization of the chip to further study the effects that antibiotics have on bacteria and the interplay between bacterial metabolism and antibiotic efficacy.

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    Measuring bacterial metabolism and antibiotic susceptibility using silicon nanowire field-effect transistors.
  • 20.
    Al-Sallami, Omer
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    CABLES DECOMMISSIONING IN OFFSHORE WIND FARMS: ENVIRONMENTAL AND ECONOMICAL PERSPECTIVE2021Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Addressing the decommissioning issues is vital to ensure a sustainable and effective process of such an essential part of the project life cycle. While there is a set of good practices and regulations that govern most of the decommissioning activities, the cable decommissioning issue is still in a big debate and often left abandoned at the seabed due to environmental concerns, as justified by most developers. This paper is aiming to understand the environmental and economic consequences of cable decommissioning.

    The available research papers and reports that are dealing with cable decommissioning issues have been reviewed. The cables are often decommissioned using similar methods to installation. However, there are no regulatory obligations to removing the cables in most countries. Cable installation will be associated with environmental impacts, but they are considered to be negligible. Additionally, Recycling cables’ copper is beneficial in both aspects environmentally and economically as copper prices are on the rise.

    A comparison between the ESs and decommissioning programs in a number of OWFSs have been conducted to understand the justification used for abandoning the cables. Most of the decommissioning reports have considered cable decommissioning to cause “considerable damage to seabed ecology”. However, that contradicts what was found in the ESs, where the impact level was considered negligible and anticipated to be similar to installation. It was unclear whether the abandonment of cables was driven by environmental considerations or not.

    A case study has been selected to compare cable and monopile decommissioning costs and the contribution of each component to the total decommissioning cost, including possible revenue generated from recycling. It was found that the cost-benefit of cable decommissioning is incomparable to monopile decommissioning as the latter is very costly, and the possible residual value is insignificant when compared to cables. Moreover, it is possible that the total cable decommissioning cost to be largely offset by the revenue generated from copper resell. Additionally, the cable decommissioning total cost can be almost paid by recycling cables if copper prices increase in the near future.

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    Offshore wind energy
  • 21. Alvarez Urrutia, Leonardo
    et al.
    Kollberg, August
    Automated test rig for electronic products2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Testing to ensure the function of PCB:s is a key process that ismandatory for factory constructed boards. Given a large number oftest object shows that manual processing is inefficient. Byautomating the process companies will have the possibility to dothis process more efficient, but how can the process be automatedfor a flexible flow and different PCB designs?This report describes the work done when designing a prototype unit that is part of an automated PCB-test line. The prototype has the task to sort PCB-cards, approved or non-approved, after thetest has been completed.

    The system consist of an elevated slider with a trolley whose position is controlled by a stepper motor and timing belt. On thetrolley a construction with a linear actuator and robot gripper is placed. The trolley moves to a position were the PCB is picked up,the signal from a terminal informs the system whether the test isok or not. The card is then placed in a rack. The status of the rack is controlled by a distance measurement, which gives the distance to nearest empty slot. Two Arduinos are used as controllers.

    The system was tested in two parts, first each component andprogram by itself and later the assemble. The result was a prototype that worked but had room for improvement with some parts in need of replacement. Future work would include error signal management, stabilizing the construction and increasing theflexibility.

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  • 22.
    Amft, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Skorodumova, Natalia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Does H2O improve the catalytic activity of Au1−4/MgO towards CO oxidation?2010Manuscript (preprint) (Other academic)
    Abstract [en]

    The present density functional theory study addresses the question whether the presence of H2O influences the catalytic activity of small gold clusters, Au1-4/MgO(100), towards the oxidation of carbon monoxide. To this end, we studied the (co-)adsorption of H2O and CO/O2 on these gold clusters. The ground state structures in the presence of all three molecular species, that we found, are Au1O2/MgO and Au2-4CO/MgO with H2O adsorbed on the surface in the proximity of the clusters-molecule complex. In this configuration the catalytic activity of Au1-4/MgO is indifferent to the presence of H2O. We also found that a stable, highly activated hydroperoxyl-hydroxyl complex, O2H ·· OH, can be formed on Au1,3/MgO. For the catalytic active system Au8/MgO, it has been predicted that this complex opens an alternative catalytic reaction pathway towards CO oxidation. Our results suggest that this water mediated catalytic cycle is unlikely to occur on Au1,3/MgO. In the case of Au1/MgO the cycle is interrupted by the dissociation of the remaining (OH)2 complex after forming the first CO2 molecule. On Au3 /MgO the O2H ·· OH complex is likely to decompose upon the impact of a CO molecule, since three of its bond dissociation energies are comparable to the reaction barrier of the CO to CO2 oxidation. 

  • 23.
    An, Hongbin
    et al.
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Hubei, Peoples R China.
    Chen, Liangzhou
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Hubei, Peoples R China.
    Liu, Xiaojun
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Hubei, Peoples R China.
    Zhao, Bin
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Hubei, Peoples R China.
    Ma, Donglin
    Huazhong Univ Sci & Technol, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Hubei, Peoples R China.
    A method of manufacturing microfluidic contact lenses by using irreversible bonding and thermoforming2018In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 28, no 10, article id 105008Article in journal (Refereed)
    Abstract [en]

    In this paper, we present the development of microfluidic contact lenses, which is based on the advantages of wearable microfluidics and can have great potential in the ophthalmology healthcare field. The development consists of two parts; the manufacturing process and the usability tests of the devices. In the manufacturing process, we firstly extended silane coupling and surface modification to irreversibly bond plastic membranes with microchannel-molded silicone rubber, to form the plastic-PDMS plane assemblies, and then molded the plane into a contact lens by thermoforming. We systematically investigated the effects of thermoforming factors, heating temperatures and the terrace die's sphere radius on channels by using the factorial experiment design. In addition, various tests were conducted to verify the usability of the devices. Through blockage and leakage tests, the devices were proved to be feasible, with no channel-blockages and could stand high pressures. Through a wearing test, the contact lenses were confirmed to be harmless on the living body. Furthermore, by performing the manipulating test, the device was proved to be liquid-controllable. These works provide a foundation for the applications of microfluidic contact lenses in ophthalmology.

  • 24.
    Andersson, Axel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division Vi3.
    Koriakina, Nadezhda
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division Vi3.
    Sladoje, Nataša
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division Vi3.
    Lindblad, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division Vi3.
    End-to-end Multiple Instance Learning with Gradient Accumulation2022In: 2022 IEEE International Conference on Big Data (Big Data), Institute of Electrical and Electronics Engineers (IEEE), 2022, p. 2742-2746Conference paper (Refereed)
    Abstract [en]

    Being able to learn on weakly labeled data and provide interpretability are two of the main reasons why attention-based deep multiple instance learning (ABMIL) methods have become particularly popular for classification of histopathological images. Such image data usually come in the form of gigapixel-sized whole-slide-images (WSI) that are cropped into smaller patches (instances). However, the sheer volume of the data poses a practical big data challenge: All the instances from one WSI cannot fit the GPU memory of conventional deep-learning models. Existing solutions compromise training by relying on pre-trained models, strategic selection of instances, sub-sampling, or self-supervised pre-training. We propose a training strategy based on gradient accumulation that enables direct end-to-end training of ABMIL models without being limited by GPU memory. We conduct experiments on both QMNIST and Imagenette to investigate the performance and training time and compare with the conventional memory-expensive baseline as well as a recent sampled-based approach. This memory-efficient approach, although slower, reaches performance indistinguishable from the memory-expensive baseline.

  • 25. Andersson, Hjalmar
    et al.
    Zdansky Cottle, Leo
    Claesson, Melker
    Karlsson, Nils
    Stenhammar, Oscar
    Insamling av drift- och produktionsdata från energiteknik vid Ihus anläggning på Vaksala-Eke2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    För att minska den globala uppvärmningen bär utbyggnaden av förnybar energiproduktion en stor vikt i dagens samhälle. Av den anledningen är det av stor betydelse som nya tekniker för energiproduktion testas. För att undersöka huruvida dessa tekniker är effektiva och lönsamma är det viktigt att deras produktionsdata publiceras och görs tillgänglig för allmänheten. Det är anledningen till att det här projektet beställts från Ihus via STUNS energi.

    Projektidén var att samla in högfrekvent uppmätt produktionsdata från en soltracker, ett vindkraftverk och ett batterilager. Dessutom skulle väderdata samlas från en väderstation och solinstrålningsmätare för att sedan offentliggöra datan via STUNS Energiportal.

    För genomförandet av projektet användes en enklare dator för att ta emot information från olika sensorer. För att kommunicera med enheterna användes olika standardiserade kommunikationsprotokoll. Enheterna konfigurerades och kopplades in i datorn. Den insamlade datan bearbetades med en programmerad kod. Programmet sände iväg datan till en molnlagringsplattform för att sedan publicera den.

    Uppkoppling mot soltrackerns växelriktare samt pyranometern lyckades. Den insamlade informationen från de två enheterna publicerades sedan på Energiportalen. Väderstationen producerade data men kommunikation med det ursprungligt tänkta protokollet lyckades inte att upprättas. Genom ett annat protokoll erhölls värden, men inte genom den implementerade koden. Dessutom uppstod problem med batterilagret och vindkraftverket. Ingen information lyckades hämtas från någon av dem.

    I projektets gång har det samlats in mätpunkter var femte sekund för respektive enhet. Utifrån det erhållna resultatet kan de konstateras att vid högfrekvent insamling av väder- och produktionsdata, blir viktig information tydligare för vardera energiproduktionsenhet. Denna information kan gå förlorad vid lågfrekvent datainsamling. Det beror på vädrets hastiga fluktuation. En lågfrekventare datainsamling ger således en sämre uppfattning av hur värdena egentligen ändras med tiden.

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  • 26.
    Andersson, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wilson, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    A microfluidic relative permittivity sensor for feedback control of carbon dioxide expanded liquid flows2019In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 285, p. 165-172Article in journal (Refereed)
    Abstract [en]

    Binary CO2-alcohol mixtures, such as CO2-expanded liquids (CXLs), are promising green solvents for reaching higher performance in flow chemistry and separation processing. However, their compressibility and high working pressure makes handling challenging. These mixtures allow for a tuneable polarity but, to do so, requires precise flow control. Here, a high-pressure tolerant microfluidic system containing a relative permittivity sensor and a mixing chip is used to actively regulate the relative permittivity of these fluids and indirectly—composition. The sensor is a fluid-filled plate capacitor created using embedded 3D-structured thin films and has a linearity of 0.9999, a sensitivity of 4.88 pF per unit of relative permittivity, and a precision within 0.6% for a sampling volume of 0.3 μL. Composition and relative permittivity of CO2-ethanol mixtures were measured at 82 bar and 21 °C during flow. By flow and dielectric models, this relationship was found to be described by the pure components and a quadratic mixing rule with an interaction parameter, kij, of -0.63 ± 0.02. Microflows with a relative permittivity of 1.7–21.4 were generated, and using the models, this was found to correspond to compositions of 6–90 mol % ethanol in CO2. With the sensor, a closed loop control system was realised and CO2-ethanol flows were tuned to setpoints of the relative permittivity in 30 s.

  • 27. Andersson, Oskar
    Savonius wind turbine innovation integrated in a constructed nano grid system2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A nanogrid system for supplying neutrino detectors on Antarctica with electricity is

    designed and built. The nanogrid system could later on be implemented in various

    configurations where suppling electricity to neutrino detectors is one area of use.

    The energy system that is acting on site in Antarctica is based around solar panels

    to provide power to the measuring equipment. However, providing electricity in

    such a way is not optimal due to its failure in delivering electricity at times. A

    nanogrid that can stand the demands of constant energy supply to the

    measurement station are therefore constructed. The energy sources that are

    integrated into the nanogrid are an innovation in vertical axis wind turbine and

    photovoltaics. The wind turbine innovation is tested under real conditions for the

    first time. In the constructed nanogrid, there are also integrated energy storage

    consisting of battery cells that are coupled together to a coherent unit.

    Measurement equipment is also implemented for analyzation of acting wind turbine

    as well as different types of safety equipment for redundancy in the system. In the

    nanogrid, a rectifier for AC to DC transformation is constructed. An inverter for DC

    to AC transformation is also implemented for supplying electricity to the

    equipment that are acting on the grid.

    The system is tested under real conditions. The whole system could observe

    partially function and configurated well to the various parts of the whole system.

    Further optimisation of some parts of the system from the prototype is needed.

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  • 28.
    Andersson, Tim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Akram, Muhammad Arsal
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Carlnäs, Carl-Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Salisbury, Tiffany
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Evaluation of potential marine current turbine sites in North American waters2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Suitable locations for marine current power generation were scouted. The specific turbines considered in this project are vertical axis turbines and require an water velocity of 0.8 m/s to start and has a system efficiency of 20%. In the beginning of the project focus was directed towards areas along Florida's coastal line with high water velocities tapping into the Gulf Stream. Data found the velocities did not meet the water speed requirements. Following this observation, it was decided to discontinue further research in the Florida region and divert the attention towards waters in Alaska. There current velocities were found to be significantly higher. Because velocities vary over time marine current power is not relevant in Alaska, but rather the closely related technology tidal power. Two areas in Alaska distinguished themselves, Cook Inlet and Aleutian Islands.Potential power and annual energy extraction were estimated for turbine stations at each site. A battery energy storage system was implemented to counteract varying water velocities. The most promising site could steadily deliver 269 kW and an annual energy production of 2.44 GWh per turbine.

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  • 29.
    Anderås, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Advanced MEMS Pressure Sensors Operating in Fluids2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Today’s MEMS technology allows manufacturing of miniaturized, low power sensors that sometimes exceeds the performance of conventional sensors. The pressure sensor market today is dominated by MEMS pressure sensors.

    In this thesis two different pressure sensor techniques are studied. The first concerns ways to improve the sensitivity in the most commonly occurring pressure sensor, namely such based on the piezoresistive technique. Since the giant piezoresistive effect was observed in silicon nanowires, it was assumed that a similar effect could be expected in nano-thin silicon films. However, it turned out that the conductivity was extremely sensitive to substrate bias and could therefore be controlled by varying the backside potential. Another important parameter was the resistivity time drift. Long time measurements showed a drastic variation in the resistance. Not even after several hours of measurement was steady state reached. The drift is explained by hole injection into the buried oxide as well as existence of mobile charges. The piezoresistive effect was studied and shown to be of the same magnitude as in bulk silicon. Later research has shown the existence of such an effect where the film thickness has to be less than around 20 nm. 

    The second area that has been studied is the pressure sensitivity of in acoustic resonators. Aluminium nitride thin film plate acoustic resonators (FPAR) operating at the lowest-order symmetric (S0), the first-order asymmetric (A1) as well as the first-order symmetric (S1) Lamb modes have been theoretically and experimentally studied in a comparative manner. The S0 Lamb mode is identified as the most pressure sensitive FPAR mode. The theoretical predictions were found to be in good agreement with the experiments. Additionally, the Lamb modes have been tested for their sensitivities to mass loading and their ability to operate in liquids, where the S0 mode showed good results.

    Finally, the pressure sensitivity in aluminium nitride thin film bulk wave resonators employing c- and tilted c-axis texture has been studied. The c-axis tilted FBAR demonstrates a substantially higher pressure sensitivity compared to its c-axis oriented counterpart. 

    List of papers
    1. Resistance Electric Field Dependence and Time Drift of Piezoresistive Single Crystalline Silicon Nanofilms
    Open this publication in new window or tab >>Resistance Electric Field Dependence and Time Drift of Piezoresistive Single Crystalline Silicon Nanofilms
    2009 (English)In: Proceedings of Eurosensors May 2009, Procedia Chemistry vol 1 (1), 2009, p. 80-83Conference paper, Published paper (Refereed)
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-122014 (URN)
    Conference
    Eurosensors May 2009, Proceedings of Eurosensors May 2009, Procedia Chemistry vol 1 (1)
    Projects
    WISENETVR-621-2006-5881
    Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2016-04-14Bibliographically approved
    2. Drift in thin film SOI piezoresistors
    Open this publication in new window or tab >>Drift in thin film SOI piezoresistors
    Show others...
    2010 (English)In: Proc. of EUROSOI Workshop, 2010 Jan 25-27, Grenoble, France, 2010, p. 71-72Conference paper, Oral presentation only (Refereed)
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-136179 (URN)
    Conference
    EUROSOI 2010 Jan 25-27, Grenoble, France
    Available from: 2010-12-10 Created: 2010-12-10 Last updated: 2016-04-18Bibliographically approved
    3. Sensitivity Features of Thin Film Plate Acoustic Wave Resonators
    Open this publication in new window or tab >>Sensitivity Features of Thin Film Plate Acoustic Wave Resonators
    2011 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 11, no 12, p. 3330-3331Article in journal (Refereed) Published
    Abstract [en]

    Thin film plate acoustic resonators devices operating in the lowest order symmetric Lamb wave mode (S0) in coriented aluminum nitride (AlN) membranes on Si were fabricated and tested for their sensitivities to pressure and mass as well as for their ability to work in liquid environment.

    Place, publisher, year, edition, pages
    IEEE Sensors Council, 2011
    Keywords
    Film bulk acoustic resonators, Resonant frequency, Sensitivity, Sensors, Surface acoustic waves
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-157877 (URN)10.1109/JSEN.2011.2158094 (DOI)000301878500019 ()
    Projects
    VR "Thin Film Guided Microacoustic Waves in Periodical Systems: Theory and Applications"
    Funder
    Swedish Research Council, 2009-5056
    Available from: 2011-08-24 Created: 2011-08-24 Last updated: 2017-12-08Bibliographically approved
    4. Lamb wave resonant pressure micro-sensor utilizing a thin-film aluminium nitride membrane
    Open this publication in new window or tab >>Lamb wave resonant pressure micro-sensor utilizing a thin-film aluminium nitride membrane
    2011 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 21, no 8, p. 085010-Article in journal (Refereed) Published
    Abstract [en]

    In this work, pressure sensitivities of aluminium nitride (AlN) thin film plate acoustic resonators (FPAR) operating at the lowest-order symmetric (S0), the first-order asymmetric (A1) as well as the first-order symmetric (S1) Lamb modes are theoretically and experimentally studied in a comparative manner. The finite element method analysis has also been performed to get a further insight into the FPAR pressure sensitivity. The theoretical predictions are found to be in good agreement with the experiment. The S0 Lamb mode is identified as the most pressure-sensitive FPAR mode, while the A1 and S1 modes are found to be much less sensitive. Further, the S0 and the A1 modes exhibit almost equal temperature sensitivities, which can be exploited to eliminate the temperature drift by comparing the resonance frequencies of the latter two modes.

    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-157028 (URN)10.1088/0960-1317/21/8/085010 (DOI)000293163700010 ()
    Funder
    Swedish Research Council, 2009-5056
    Available from: 2011-08-16 Created: 2011-08-15 Last updated: 2017-12-08
    5. Thin Film Plate Wave Resonant Sensor for Pressure and Gravimetric Measurements
    Open this publication in new window or tab >>Thin Film Plate Wave Resonant Sensor for Pressure and Gravimetric Measurements
    2011 (English)In: Procedia Engineering 25, Eurosensors XXV: Proc. Eurosensors XXV, September 4-7, 2011, Athens, Greece, Elsevier, 2011, p. 571-574Conference paper, Published paper (Refereed)
    Abstract [en]

    Thin film plate acoustic resonators (FPAR) devices operating in the lowest order symmetric Lamb wave mode (S0),the first order asymmetric Lamb wave mode (A1) and the first order symmetric Lamb wave mode (S1), propagatingin c-oriented aluminum nitride (AlN) membranes on Si were fabricated and tested for their sensitivities to pressureand mass. Systematic data on frequency shifts versus rigid mass (layer) thickness and ambient pressure variations arepresented for the different Lamb wave resonances. Further the ability to work in liquid environment of the S0, A1 andS1 modes, respectively, has been tested in view of Bio-sensor applications.

    Place, publisher, year, edition, pages
    Elsevier, 2011
    Series
    Procedia Engineering, ISSN 1877-7058 ; 25
    Keywords
    Micro, prssure, sensor, radio frequency
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-167002 (URN)10.1016/j.proeng.2011.12.142 (DOI)000300512400139 ()
    Conference
    25th Eurosensors Conference, SEP 04-07, 2011, Athens, GREECE
    Projects
    VR Granted
    Funder
    Swedish Research Council, 2009-5056
    Available from: 2012-01-18 Created: 2012-01-18 Last updated: 2013-03-13
    6. Tilted c-Axis Thin-Film Bulk Wave Resonant Pressure Sensors With Improved Sensitivity
    Open this publication in new window or tab >>Tilted c-Axis Thin-Film Bulk Wave Resonant Pressure Sensors With Improved Sensitivity
    2012 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 12, no 8, p. 2653-2654Article in journal (Refereed) Published
    Abstract [en]

    Aluminum nitride thin film bulk wave resonant pressure sensors employing c- and tilted c-axis texture, have been fabricated and tested for their pressure sensitivities. The c-axis tilted FBAR pressure sensors demonstrate substantially higher pressure sensitivity compared to its c-axis oriented counterpart. More specifically the thickness plate quasi-shear resonance has demonstrated the highest pressure sensitivity while further being able to preserve its performance in liquid environment.

    Keywords
    AlN, FBAR, pressure sensor, sensitivity, micro-acoustic
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-173179 (URN)10.1109/JSEN.2012.2199482 (DOI)000305584300003 ()
    Available from: 2012-04-20 Created: 2012-04-20 Last updated: 2017-12-07Bibliographically approved
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  • 30.
    Anderås, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Arapan, Lilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Yantchev, Ventsislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thin Film Plate Wave Resonant Sensor for Pressure and Gravimetric Measurements2011In: Procedia Engineering 25, Eurosensors XXV: Proc. Eurosensors XXV, September 4-7, 2011, Athens, Greece, Elsevier, 2011, p. 571-574Conference paper (Refereed)
    Abstract [en]

    Thin film plate acoustic resonators (FPAR) devices operating in the lowest order symmetric Lamb wave mode (S0),the first order asymmetric Lamb wave mode (A1) and the first order symmetric Lamb wave mode (S1), propagatingin c-oriented aluminum nitride (AlN) membranes on Si were fabricated and tested for their sensitivities to pressureand mass. Systematic data on frequency shifts versus rigid mass (layer) thickness and ambient pressure variations arepresented for the different Lamb wave resonances. Further the ability to work in liquid environment of the S0, A1 andS1 modes, respectively, has been tested in view of Bio-sensor applications.

  • 31.
    Anderås, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Yantchev, Ventsislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Tilted c-Axis Thin-Film Bulk Wave Resonant Pressure Sensors With Improved Sensitivity2012In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 12, no 8, p. 2653-2654Article in journal (Refereed)
    Abstract [en]

    Aluminum nitride thin film bulk wave resonant pressure sensors employing c- and tilted c-axis texture, have been fabricated and tested for their pressure sensitivities. The c-axis tilted FBAR pressure sensors demonstrate substantially higher pressure sensitivity compared to its c-axis oriented counterpart. More specifically the thickness plate quasi-shear resonance has demonstrated the highest pressure sensitivity while further being able to preserve its performance in liquid environment.

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  • 32.
    Andreasson, Joel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Design och konstruktion av distorsionseffekt för gitarrer2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This project has been done as a part of a bachelors degree in engineering at Uppsala university. The project was supervised by Jörgen Olsson at the division of solid state electronics.

    The goal of this project was to develop a distortion effect that can be used with an guitar and a amplifier. The effect was to have controllable distorsion, volume and tone control including bass and treble. The circuit is also supposed to be run using a 9V battery as power supply, which means that the in circuit currents shold be low. When the circuit was finished it was also analyzed through different measurements and simulations.

    The distortion of the circuit was achieved using diodes to get a nonlinear amplification. The goals of the circuit controls was achieved, and although a low circuit current was achieved, it only satisfied the goal of 1 mA when high distorsion was set for the circuit.

    When measuring and simulating the system, some major differences was found. The simulated frequency response characteristics was found to be very different from the measured. This is likely due to the simulation program not being

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  • 33.
    Andreou, Charalambos M.
    et al.
    Univ Cyprus, Dept Elect & Comp Engn, CY-1678 Nicosia, Cyprus.
    Miguel Gonzalez-Castano, Diego
    Univ Santiago de Compostela, Radiat Phys Lab, E-15705 Santiago De Compostela, Spain.
    Gerardin, Simone
    Univ Padua, Dept Informat Engn, I-35122 Padua, Italy.
    Bagatin, Marta
    Univ Padua, Dept Informat Engn, I-35122 Padua, Italy.
    Gomez Rodriguez, Faustino
    Univ Santiago de Compostela, Radiat Phys Lab, E-15705 Santiago De Compostela, Spain.
    Paccagnella, Alessandro
    Univ Padua, Dept Informat Engn, I-35122 Padua, Italy.
    Prokofiev, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Javanainen, Arto
    Univ Jyvaskyla, Dept Phys, FI-40014 Jyvaskyla, Finland;Vanderbilt Univ, Dept Elect Engn & Comp Sci, Nashville, TN 37235 USA.
    Virtanen, Ari
    Univ Jyvaskyla, Dept Phys, FI-40014 Jyvaskyla, Finland.
    Liberali, Valentino
    Univ Milan, Dept Phys, I-20133 Milan, Italy.
    Calligaro, Cristiano
    RedCat Devices, I-20142 Milan, Italy.
    Nahmad, Daniel
    R&D Dept, Tower Semicond, IL-2310502 Migdal Haemeq, Israel.
    Georgiou, Julius
    Univ Cyprus, Dept Elect & Comp Engn, CY-1678 Nicosia, Cyprus.
    Low-Power, Subthreshold Reference Circuits for the Space Environment: Evaluated with -rays, X-rays, Protons and Heavy Ions2019In: Electronics, E-ISSN 2079-9292, Vol. 8, no 5, article id 562Article in journal (Refereed)
    Abstract [en]

    The radiation tolerance of subthreshold reference circuits for space microelectronics is presented. The assessment is supported by measured results of total ionization dose and single event transient radiation-induced effects under -rays, X-rays, protons and heavy ions (silicon, krypton and xenon). A high total irradiation dose with different radiation sources was used to evaluate the proposed topologies for a wide range of applications operating in harsh environments similar to the space environment. The proposed custom designed integrated circuits (IC) circuits utilize only CMOS transistors, operating in the subthreshold regime, and poly-silicon resistors without using any external components such as compensation capacitors. The circuits are radiation hardened by design (RHBD) and they were fabricated using TowerJazz Semiconductor's 0.18 m standard CMOS technology. The proposed voltage references are shown to be suitable for high-precision and low-power space applications. It is demonstrated that radiation hardened microelectronics operating in subthreshold regime are promising candidates for significantly reducing the size and cost of space missions due to reduced energy requirements.

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  • 34.
    Ankarcrona, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    High Frequency Analysis of Silicon RF MOS Transistors2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Today, the silicon technology is well established for RF-applications (f~1-100 GHz), with emphasis on the lower frequencies (f < 5 GHz). The field of RF power devices is extensive concerning materials and devices. One of the important RF-devices is the silicon LDMOS transistor. A large extent of the research presented in the thesis concerns studies of this device, which have resulted in increased understanding of the device behavior and improved performance. The thesis starts with a brief survey of the RF-field, including the LDMOS transistor, followed by a description of the methods used in the investigations; simulations, modeling and measurements. Specific results presented in the appended papers are also briefly summarized.

    A new concept for LDMOS transistors, which allows for both high frequency and high voltage operation, has been developed and characterized. World-record performance in terms of output power density was obtained: over 1 W/mm at 50 V and 3.2 GHz. Further understanding and improvements of the device are achieved using simulations and modeling. For determination of model parameters a new general parameter extraction technique was developed. The method has been successfully used for a large variety of high-frequency devices, and has been frequently used in the modeling work in this thesis.

    Important properties of RF-power devices are the device linearity and power efficiency. Extensive studies regarding the efficiency were conducted using numerical simulations and modeling of the off-state output resistance, which is correlated to the efficiency. The results show that significant improvements can be obtained for devices on both bulk- and SOI-substrates, using thin high-resistivity substrates and very low-resistivity SOI-substrates, respectively.

    Finally a new approach to drastically reduce substrate crosstalk by using very low-resistivity SOI substrate is proposed. Experimentally, a reduction of 20-40 dB was demonstrated in the GHz range compared to high-resistivity SOI substrate.

    List of papers
    1. Sub-Circuit Based SPICE Model for High Voltage LDMOS Transistors
    Open this publication in new window or tab >>Sub-Circuit Based SPICE Model for High Voltage LDMOS Transistors
    2002 (English)In: Physica Scripta, no T101, p. 7-9Article in journal (Refereed) Published
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-93398 (URN)
    Available from: 2005-09-02 Created: 2005-09-02 Last updated: 2012-09-26
    2. A General Small-Signal Series Impedance Extraction Technique
    Open this publication in new window or tab >>A General Small-Signal Series Impedance Extraction Technique
    2002 (English)In: IEEE Microwave and Wireless Components Letters, ISSN 1531-1309, E-ISSN 1558-1764, Vol. 12, no 7, p. 249-251Article in journal (Refereed) Published
    Abstract [en]

    A new technique for extracting the series inductances and resistances in a small-signal equivalent circuit is presented. The technique does not rely on approximation and should therefore be as accurate as the measured data. The technique can also be used to extract the intrinsic parameters if they are not easily achieved using other methods. The method is exemplified with a microwave LDMOS transistor

    Keywords
    S-parameters, microwave LDMOS transistor, parameter estimation, series inductances, series resistances, small-signal equivalent circuit, small-signal series impedance extraction technique
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-93400 (URN)10.1109/LMWC.2002.801134 (DOI)
    Available from: 2005-09-02 Created: 2005-09-02 Last updated: 2017-12-14Bibliographically approved
    3. Analysis and Design of a Low-Voltage High-Frequency LDMOS Transistor
    Open this publication in new window or tab >>Analysis and Design of a Low-Voltage High-Frequency LDMOS Transistor
    2002 (English)In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 49, no 6, p. 976-980Article in journal (Refereed) Published
    Abstract [en]

    For a low voltage lateral double-diffused MOS (LDMOS) transistor, the output performance has been improved in terms of fMAX. This is done by decreasing the output capacitance and thus decreasing the total output conductance. Extraction of the model parameters has been made and the most efficient parameter to improve was identified and linked to a specific part of the transistor structure. Layout changes in the n-well/p-base region were done as the result of the model analyses and finally, the modified devices were processed. Measurements on the improved devices showed results that closely, matched the expected, and fMAX was increased with 30% and only a slight decrease in f T. Finally, the capacitance reduction in the n-well/p-base junction was measured by direct. measurements

    Keywords
    LV HF LDMOS transistor, S-parameter, current-voltage characteristics, equivalent circuits, layout changes, microwave FET, model parameters, n-well/p-base junction, output capacitance, output performance, small-signal parameters, total output conductance
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-93401 (URN)10.1109/TED.2002.1003715 (DOI)
    Available from: 2005-09-02 Created: 2005-09-02 Last updated: 2017-12-14
    4. Simulation and modeling of the substrate contribution to the output resistance for RF-LDMOS power transistors
    Open this publication in new window or tab >>Simulation and modeling of the substrate contribution to the output resistance for RF-LDMOS power transistors
    2004 (English)In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 48, no 5, p. 789-797Article in journal (Refereed) Published
    Abstract [en]

    High frequency substrate losses for RF MOSFETs are analyzed using numerical device simulation. The results show that losses in devices made on low resistivity substrate occur through the substrate while losses in devices made on high resistivity substrate in the high frequency region occur along the surface through the device (source–drain). An equivalent circuit model is developed which accurately describes the off-state losses. Based on the model significant improvements in terms of output resistance are demonstrated, using an improved device on high resistivity substrate.

    Keywords
    Substrate losses, Modeling, RF MOSFET, LDMOS
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-93402 (URN)10.1016/j.sse.2003.12.005 (DOI)
    Available from: 2005-09-02 Created: 2005-09-02 Last updated: 2017-12-14
    5. Improved Output Resistance in RF-power MOSFETs using Low Resistivity SOI Substrate
    Open this publication in new window or tab >>Improved Output Resistance in RF-power MOSFETs using Low Resistivity SOI Substrate
    Show others...
    (English)Manuscript (Other academic)
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-93403 (URN)
    Available from: 2005-09-02 Created: 2005-09-02 Last updated: 2015-07-21Bibliographically approved
    6. Low Resistivity SOI for Substrate Crosstalk Reduction
    Open this publication in new window or tab >>Low Resistivity SOI for Substrate Crosstalk Reduction
    2005 (English)In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, IEEE Trans on Electronic Devices, Vol. 52, no 8, p. 1920-1922Article in journal (Refereed) Published
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-93404 (URN)
    Available from: 2005-09-02 Created: 2005-09-02 Last updated: 2017-12-14Bibliographically approved
    7. 1 W/mm RF Power Denisty at 3.2 GHz for a Dual-Layer RESURF LDMOS Transistor
    Open this publication in new window or tab >>1 W/mm RF Power Denisty at 3.2 GHz for a Dual-Layer RESURF LDMOS Transistor
    Show others...
    2002 (English)In: IEEE Electron Device Letters, ISSN 0741-3106, Vol. 23, no 4, p. 206-208Article in journal (Refereed) Published
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-41678 (URN)10.1109/55.992840 (DOI)
    Available from: 2007-02-23 Created: 2007-02-23 Last updated: 2010-07-09Bibliographically approved
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    COVER01
  • 35.
    Ankarcrona, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Eklund, Klas-Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Vestling, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Olsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Analysis and improvments of high frequency substrate losses for RF MOSFETs2003In: Proceedings of IEEE SISPAD, 2003, p. 319-322Conference paper (Refereed)
  • 36.
    Ankarcrona, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Eklund, Klas-Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Vestling, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Olsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Simulation and modeling of the substrate influence on the high frequency performance for RF LDMOS2003In: GHz2003 Symposium, Nov. 4-5, 2003Conference paper (Refereed)
  • 37.
    Ankarcrona, Johan
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Materials Science. Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Olsson, Jörgen
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Materials Science. Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    SPICE Modeling of High Voltage LDMOS Transistors2001In: The 19th Nordic Semiconductor Meeting, Copenhagen, Denmark, May, 2001Conference paper (Refereed)
  • 38.
    Ankarcrona, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Olsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Sub-Circuit Based SPICE Model for High Voltage LDMOS Transistors2002In: Physica Scripta, no T101, p. 7-9Article in journal (Refereed)
  • 39.
    Anker, A.
    et al.
    Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA..
    Barwick, S. W.
    Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA..
    Bernhoff, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Besson, D. Z.
    Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA.;Natl Res Nucl Univ MEPhI, Moscow Engn Phys Inst, Moscow 115409, Russia..
    Bingefors, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Garcia-Fernandez, D.
    DESY, D-15738 Zeuthen, Germany.;Friedrich Alexander Univ Erlangen Nurnberg, ECAP, D-91058 Erlangen, Germany..
    Gaswint, G.
    Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA..
    Glaser, C.
    Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA..
    Hallgren, Allan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Hanson, J. C.
    Whittier Coll, Dept Phys, Whittier, CA 90602 USA..
    Klein, S. R.
    Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA..
    Kleinfelder, S. A.
    Univ Calif Irvine, Dept Elect Engn & Comp Sci, Irvine, CA 92697 USA..
    Lahmann, R.
    Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA.;Friedrich Alexander Univ Erlangen Nurnberg, ECAP, D-91058 Erlangen, Germany..
    Latif, U.
    Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA..
    Nam, J.
    Natl Taiwan Univ, Dept Phys, Taipei 10617, Taiwan.;Natl Taiwan Univ, Leung Ctr Cosmol & Particle Astrophys, Taipei 10617, Taiwan..
    Novikov, A.
    Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA.;Natl Res Nucl Univ MEPhI, Moscow Engn Phys Inst, Moscow 115409, Russia..
    Nelles, A.
    DESY, D-15738 Zeuthen, Germany.;Friedrich Alexander Univ Erlangen Nurnberg, ECAP, D-91058 Erlangen, Germany..
    Paul, M. P.
    Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA..
    Persichilli, C.
    Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA..
    Plaisier, I
    DESY, D-15738 Zeuthen, Germany.;Friedrich Alexander Univ Erlangen Nurnberg, ECAP, D-91058 Erlangen, Germany..
    Prakash, T.
    Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA..
    Shively, S. R.
    Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA..
    Tatar, J.
    Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA.;Univ Calif Irvine, Res Cyberinfrastruct Ctr, Irvine, CA 92697 USA..
    Unger, Elisabeth
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Wang, S-H
    Natl Taiwan Univ, Dept Phys, Taipei 10617, Taiwan.;Natl Taiwan Univ, Leung Ctr Cosmol & Particle Astrophys, Taipei 10617, Taiwan..
    Welling, C.
    DESY, D-15738 Zeuthen, Germany.;Friedrich Alexander Univ Erlangen Nurnberg, ECAP, D-91058 Erlangen, Germany..
    A search for cosmogenic neutrinos with the ARIANNA test bed using 4.5 years of data2020In: Journal of Cosmology and Astroparticle Physics, E-ISSN 1475-7516, no 3, article id 053Article in journal (Refereed)
    Abstract [en]

    The primary mission of the ARIANNA ultra-high energy neutrino telescope is to uncover astrophysical sources of neutrinos with energies greater than 10(16) eV. A pilot array, consisting of seven ARIANNA stations located on the surface of the Ross Ice Shelf in Antarctica, was commissioned in November 2014. We report on the search for astrophysical neutrinos using data collected between November 2014 and February 2019. A straight-forward template matching analysis yielded no neutrino candidates, with a signal efficiency of 79%. We find a 90% confidence upper limit on the diffuse neutrino flux of E-2 Phi = 1.7 x 10(-6) GeV cm(-2) s(-1) sr(-1) for a decade wide logarithmic bin centered at a neutrino energy of 10(18),eV, which is an order of magnitude improvement compared to the previous limit reported by the ARIANNA collaboration. The ARIANNA stations, including purpose built cosmic-ray stations at the Moore's Bay site and demonstrator stations at the South Pole, have operated reliably. Sustained operation at two distinct sites confirms that the flexible and adaptable architecture can be deployed in any deep ice, radio quiet environment. We show that the scientific capabilities, technical innovations, and logistical requirements of ARIANNA are sufficiently well understood to serve as the basis for large area radio-based neutrino telescope with a wide field-of-view.

  • 40. Anthon, Jonsson
    et al.
    Vincent, Ricknell
    Project in Electrical Engineering: Electric Skateboard2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Download full text (pdf)
    fulltext
  • 41.
    Anttila, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering.
    Power control strategies for renewable energy systems: The inverter's role in future power systems2020Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Connecting more non-dispatchable renewable energy sources (RESs) will result in a higher power variability and a lower system inertia when the synchronous generators are replaced by inverter-connected RES. Inverter control can be divided in three categories: grid-following, grid-forming (GFM) and grid-supporting. A literature review of inverter control strategies identifies the GFM control as having an important role in maintaining system stability assuming near 100 % inverter-connected RES. Critical aspects of the inverter control are also identified; the control need to function autonomously, be able to remain connected during transient events and be insensitive to grid topology.

    Combining various RES is also shown to improve system stability. The combination of RES that has been investigated in most studies is wind, solar and wave power. Wave power is still a young technology compared to solar and wind power. It generates higher power fluctuations over short time periods with a significant difference between average and maximum power. Additionally, wave power parks (WPPs) are often connected via long cables which contribute reactive power to the grid. These challenges has to be considered to maintain system stability and power quality when connecting a WPP to the grid.

    In a Power Hardware-In-the-Loop study of how a WPP affects the power quality at the point of common coupling (PCC), it is found that the impact is highest for WPPs with fewer generators as the variability is reduced when several generators are excited at different times. Energy storage is also shown to have a significant impact on the power quality at the PCC with reduced flicker, total harmonic distortion and power and voltage variability. A simulation study also shows the positive impact of energy storage on power variability and the role of inverter control in reactive power compensation.

    List of papers
    1. Power Control Strategies for a Smoother Power Output from a Wave Power Plant
    Open this publication in new window or tab >>Power Control Strategies for a Smoother Power Output from a Wave Power Plant
    Show others...
    2019 (English)In: European Wave and Tidal Energy Conference (EWTEC), Napoli, Italy: European Wave and Tidal Energy Conference , 2019Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Napoli, Italy: European Wave and Tidal Energy Conference, 2019
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:uu:diva-390134 (URN)
    Conference
    13th European Wave and Tidal Energy Conference (EWTEC), Napoli, Italy, September 1-6, 2019
    Available from: 2019-08-05 Created: 2019-08-05 Last updated: 2020-10-05Bibliographically approved
    2. Power Hardware-in-the-loop simulations of Grid-Integration of a Wave Power Park
    Open this publication in new window or tab >>Power Hardware-in-the-loop simulations of Grid-Integration of a Wave Power Park
    Show others...
    2019 (English)In: 13th European Wave and Tidal Energy Conference (EWTEC), Napoli, Italy, September 1-6, 2019, Napoli, Italy, 2019Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Napoli, Italy: , 2019
    Keywords
    energy storage system, grid integration, hardware-in-the-loop, microgrid, power fluctuations, wave energy converter
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-390104 (URN)
    Conference
    13th European Wave and Tidal Energy Conference (EWTEC), Napoli, Italy, September 1-6, 2019
    Available from: 2019-08-05 Created: 2019-08-05 Last updated: 2023-10-02Bibliographically approved
    3. Marine Renewable Energy Sources for Desalination, Generating Freshwater and Lithium
    Open this publication in new window or tab >>Marine Renewable Energy Sources for Desalination, Generating Freshwater and Lithium
    Show others...
    2019 (English)Conference paper, Published paper (Refereed)
    National Category
    Condensed Matter Physics Energy Systems
    Identifiers
    urn:nbn:se:uu:diva-400118 (URN)
    Conference
    29th International Ocean and Polar Engineering Conference ISOPE, 16-21 June, 2019, Honolulu, USA
    Available from: 2019-12-18 Created: 2019-12-18 Last updated: 2021-10-17Bibliographically approved
    4. Freshwater and Lithium from Desalination Powered by Marine Energy Sources
    Open this publication in new window or tab >>Freshwater and Lithium from Desalination Powered by Marine Energy Sources
    Show others...
    2020 (English)In: International Journal of Offshore and Polar Engineering, ISSN 1053-5381, Vol. 30, no 3, p. 283-285Article in journal (Refereed) Published
    Abstract [en]

    To our knowledge, this paper represents an initial study of a novel concept in freshwater and lithium extraction from desalination powered off-grid by marine renewable energy sources. The project's background is interest in the local supply of lithium for the growing numbers of electric vehicles. The desalination technologies investigated are reverse osmosis and electrodialysis. The collocation of the marine resources, possibly available and future technical solutions, and demands for freshwater and lithium suggest that the proposed system could be interesting to study further.

    Keywords
    Wave power, marine current energy, desalination, lithiumion battery, electric vehicles, aqueous mining, brine management.
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Science of Electricity
    Identifiers
    urn:nbn:se:uu:diva-417958 (URN)10.17736/ijope.2020.jc789 (DOI)000592954900004 ()
    Available from: 2020-08-27 Created: 2020-08-27 Last updated: 2021-10-17Bibliographically approved
    5. Grid Impact and Power quality Assessment in wave Energy Parks: Different layouts and Power Penetrations using Energy Storage
    Open this publication in new window or tab >>Grid Impact and Power quality Assessment in wave Energy Parks: Different layouts and Power Penetrations using Energy Storage
    Show others...
    2021 (English)In: The Journal of Engineering, E-ISSN 2051-3305, Vol. 2021, no 8, p. 415-428Article in journal (Refereed) Published
    Abstract [en]

    Power fluctuations induced by wave energy converters (WECs) may reflect negative impact on the power quality of the power grid. Assessing their impact is an important step to ensure the grid compliance level of the energy park. The IEC 61000-4-15 standard classifies the allowable disturbances in the grid. This study analysed and assessed the grid impact in terms of flicker, harmonic distortion and voltage variations. The assessments were performed without energy storage and compared when using the energy storage. A single WEC is emulated as an irregular power output of a real WEC using a combined model of power take-off in the Simulink model. Time series based on data obtained in earlier offshore experiments, conducted at the Lysekil research site in Sweden, is used to emulate a wave energy park (WEP) power in a land-based test rig in real-time power hardware-in-the-loop simulations. A total of three and ten WECs are emulated by introducing a time delay in the time series to investigate the grid impact in each layout. Flicker emissions, voltage variations, individual and total harmonics of the voltage at the connection point in each layout are studied and compared with the limits to be grid compliant for layouts of the WEP. In addition, voltage and current harmonics for the single WEC and individual harmonics in each phase of the voltage are measured and analysed to assess the compliance level of the WEP.

    Place, publisher, year, edition, pages
    Institution of Engineering and Technology, 2021
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-390136 (URN)10.1049/tje2.12006 (DOI)000670344800001 ()
    Funder
    Swedish Research Council, 2015-03126StandUp
    Available from: 2019-08-05 Created: 2019-08-05 Last updated: 2024-04-05Bibliographically approved
    6. Grid Forming inverters: A review of the state of the art of key elements for microgrid operation
    Open this publication in new window or tab >>Grid Forming inverters: A review of the state of the art of key elements for microgrid operation
    2022 (English)In: Energies, E-ISSN 1996-1073, Vol. 15, no 15, article id 5517Article, review/survey (Refereed) Published
    Abstract [en]

    In the past decade, inverter-integrated energy sources have experienced rapid growth, which leads to operating challenges associated with reduced system inertia and intermittent power generation, which can cause instability and performance issues of the power system. Improved control schemes for inverters are necessary to ensure the stability and resilience of the power system. Grid-forming inverters dampen frequency fluctuations in the power system, while grid-following inverters can aggravate frequency problems with increased penetration. This paper aims at reviewing the role of grid-forming inverters in the power system, including their topology, control strategies, challenges, sizing, and location. In order to facilitate continued research in this field, a comprehensive literature review and classification of the studies are conducted, followed by research gaps and suggestions for future studies.

    Place, publisher, year, edition, pages
    MDPI, 2022
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:uu:diva-421008 (URN)10.3390/en15155517 (DOI)000839717400001 ()
    Funder
    SweGRIDS - Swedish Centre for Smart Grids and Energy StorageVattenfall ABSwedish Energy Agency
    Available from: 2020-10-03 Created: 2020-10-03 Last updated: 2023-12-05Bibliographically approved
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  • 42.
    Anubhab, Ghosh
    et al.
    KTH Royal Institute of Technology.
    Abdalmoaty, Mohamed
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Chatterjee, Saikat
    KTH Royal Institute of Technology.
    Hjalmarsson, Håkan
    KTH Royal Institute of Technology.
    DeepBayes -- an estimator for parameter estimation in stochastic nonlinear dynamical modelsManuscript (preprint) (Other academic)
    Abstract [en]

    Stochastic nonlinear dynamical systems are ubiquitous in modern, real-world applications. Yet, estimating the unknown parameters of stochastic, nonlinear dynamical models remains a challenging problem. The majority of existing methods employ maximum likelihood or Bayesian estimation. However, these methods suffer from some limitations, most notably the substantial computational time for inference coupled with limited flexibility in application. In this work, we propose DeepBayes estimators that leverage the power of deep recurrent neural networks in learning an estimator. The method consists of first training a recurrent neural network to minimize the mean-squared estimation error over a set of synthetically generated data using models drawn from the model set of interest. The a priori trained estimator can then be used directly for inference by evaluating the network with the estimation data. The deep recurrent neural network architectures can be trained offline and ensure significant time savings during inference. We experiment with two popular recurrent neural networks -- long short term memory network (LSTM) and gated recurrent unit (GRU). We demonstrate the applicability of our proposed method on different example models and perform detailed comparisons with state-of-the-art approaches. We also provide a study on a real-world nonlinear benchmark problem. The experimental evaluations show that the proposed approach is asymptotically as good as the Bayes estimator. 

  • 43.
    Apelfröjd, Senad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bülow, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Kjellin, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Eriksson, Sandra
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Laboratory verification of system for grid connection of a 12 kW variable speed wind turbine with a permanent magnet synchronous generator2012In: EWEA 2012 Annual Event, Copenhagen, Denmark, 2012, 2012Conference paper (Refereed)
    Abstract [en]

    In this paper the first laboratory tests of the gridconnection system, connected to a resistiveload, for a vertical axis wind turbine (VAWT)with a permanent magnet generator arepresented. The system is based on a taptransformertopology with a voltage sourceinverter and an LCL-filter. The use of a taptransformer topology eliminates the need for aDC-DC converter to handle the variations inDC voltage. The harmonic content of thecurrents from experiments and simulationsperformed in Simulink using different taps onthe transformer are presented. The simulatedcurrents, fed to the resistive load, have a totalharmonic distortion (THD) of 0.5% to 0.9% forthe different taps. The experimental systemhas a current THD ranging from 1.8% to 2.8%.The difference is expected to be due tounbalances, delays and dead times in theexperimental set-up as the major THDcontribution is from harmonic orders below 11.The results show that an LCL filter can bedesigned to meet the demands on powerquality for grid connection of the system withall the taps of the tap transformer inaccordance with IEEE 519-1992.

  • 44.
    Arapan, Lilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thin Film Plate Acoustic Resonators for Frequency Control and Sensing Applications2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The recent development of the commercially viable thin film electro-acoustic technology has triggered a growing interest in the research of plate guided wave or Lamb wave components owing to their unique characteristics. In the present thesis i) an experimental study of the thin film plate resonators (FPAR) performance operating on the lowest symmetrical Lamb wave (S0) propagating in highly textured AlN membranes versus a variety of design parameters has been performed. The S0 mode is excited through an Interdigital Transducer and confined within the structure by means of reflection from metal strip gratings. Devices operating in the vicinity of the stop-band center exhibiting a Q-value of up to 3000 at a frequency around 900MHz have been demonstrated. Temperature compensation of this type of devices has been studied theoretically and successfully realized experimentally for the first time. Further, integrated circuit-compatible S0 Lamb based two-port FPAR stabilized oscillators exhibiting phase noise of -92 dBc/Hz at 1 kHz frequency offset with feasible thermal noise floor below -180 dBc/Hz have been tested under high power for a couple of weeks. More specifically, the FPARs under test have been running without any performance degradation at up to 27 dBm loop power. Further, the S0 mode was experimentally demonstrated to be highly mass and pressure sensitive as well as suitable for in-liquid operation, which together with low phase noise and high Q makes it very suitable for sensor applications; ii) research in view of FPARs operating on other types of Lamb waves as well as novel operation principles has been initiated. In this work, first results on the design, fabrication and characterization of two novel type resonators: The Zero Group Velocity Resonators (ZGVR) and The Intermode-Coupled Thin Film Plate Acoustic Resonators (IC-FPAR), exploiting new principles of operation have been successfully demonstrated. The former exploits the intrinsic zero group velocity feature of the S1 Lamb mode for certain combination of design parameters while the latter takes advantage of the intermode interaction (involving scattering) between S0 and A1 Lamb modes through specially designed metal strip gratings (couplers). Thus both type of resonators operate on principles of confining energy under IDT other than reflection.

    List of papers
    1. Micromachined Thin Film Plate Acoustic Wave Resonators (FPAR) Part II
    Open this publication in new window or tab >>Micromachined Thin Film Plate Acoustic Wave Resonators (FPAR) Part II
    2009 (English)In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 56, no 12, p. 2701-2710Article in journal (Refereed) Published
    Abstract [en]

    Improved performance thin-film plate acousticwave resonators (FPAR) using the lowest order symmetricLamb wave (S0) propagating in highly textured AlN membraneshave been previously demonstrated for the first time.In this work, an experimental study of the resonators’ performancevs. a variety of design parameters is performed. Devicesoperating in the vicinity of the stopband center exhibiting aQ-value of up to 3000 at a frequency of around 875 MHz aredemonstrated. Further, low-loss high-Q micromachined 2-portlongitudinally coupled thin-film resonators using the S0 modeare demonstrated for the first time. For the analysis of theproposed structures, the coupling-of-modes (COM) approachis successfully employed. Initially, the COM model is used forthe extraction of physical parameters from one-port FPARmeasurements. Subsequently, using the COM model, a satisfactoryagreement with the proposed experimental frequencycharacteristics of S0 2-port FPARs has been achieved, andpossibilities for further improvements in the performance discussed.Finally, the frequency spectrum of the one-port deviceshas been studied and the excited plate modes at differentfrequencies identified and presented with their Q-factors andtemperature coefficients of frequency (TCF).

    Keywords
    Thin films, Resonator, Micromachining, MEMS, NEMS
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-111379 (URN)10.1109/TUFFC.2009.1361 (DOI)000272593100011 ()
    Projects
    VR Funded "Thin Film Guided Microacoustic Waves in Periodical Structures: Theory and Applications"
    Funder
    Swedish Research Council, 2009-5056
    Available from: 2009-12-12 Created: 2009-12-12 Last updated: 2017-12-12
    2. Micromachined thermally compensated thin film Lamb wave resonator for frequency control and sensing applications
    Open this publication in new window or tab >>Micromachined thermally compensated thin film Lamb wave resonator for frequency control and sensing applications
    2009 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 19, no 3, p. 035018-Article in journal (Refereed) Published
    Abstract [en]

    Micromachined thin film plate acoustic wave resonators (FPAR) utilizing the lowest order symmetric Lamb wave (S0) propagating in highly textured 2μm thick Aluminum Nitride (AlN) membranes have been successfully demonstrated [1]. The proposed devices have a SAW-based design and exhibit Q factors of up to 3000 at a frequency around 900MHz as well as design flexibility with respect to the required motional resistance. However, a notable drawback of the proposed devices is non-zero temperature coefficient of frequency (TCF) which lies in the range -20 ppm/K to –25 ppm/K. Thus, despite the promising features demonstrated, further device optimization is required. In this work temperature compensation of thin AlN film Lamb wave resonators is studied and experimentally demonstrated. Temperature compensation while retaining at the same time the device electromechanical coupling is experimentally demonstrated. The zero TCF Lamb wave resonators are fabricated onto composite AlN/SiO2 membranes. Q factors of around 1400 have been measured at a frequency of around 755 MHz. Finally, the impact of technological issues on the device performance is discussed in view of improving the device performance.

    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Electronics
    Identifiers
    urn:nbn:se:uu:diva-89404 (URN)10.1088/0960-1317/19/3/035018 (DOI)000263678200019 ()
    Projects
    WISENET
    Funder
    Swedish Research Council, 2009-5056
    Available from: 2009-02-12 Created: 2009-02-12 Last updated: 2018-06-26Bibliographically approved
    3. Thin film plate acoustic resonators for integrated microwave power oscillator applications
    Open this publication in new window or tab >>Thin film plate acoustic resonators for integrated microwave power oscillator applications
    2011 (English)In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 47, no 7, p. 452-453Article in journal (Refereed) Published
    Abstract [en]

    Two-port film plate acoustic resonators (FPAR) devices operating on the lowest order symmetric Lamb wave mode (S0) in C-oriented AlN membranes on Si were fabricated and tested for their power handling capabilities in a feedback-loop power oscillator circuit. The FPAR was operated at an incident power level of 24 dBm for several weeks without performance degradation. Its flicker noise constant was calculated from close-in phase noise data as αR=2.1×10^−36/Hz. The results indicate that IC-compatible S0 FPARs are well suited for integrated microwave oscillators with thermal noise floor (TNF) levels below −175 dBc/Hz.

    Keywords
    Powe oscillator, low noise, MEMS, piezo
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-150468 (URN)10.1049/el.2011.0381 (DOI)000288893100023 ()
    Projects
    VR "Thin Film Guided Microacoustic Waves in Periodical Systems: Theory and Applications"
    Funder
    Swedish Research Council, 2009-5056
    Available from: 2011-03-30 Created: 2011-03-30 Last updated: 2017-12-11Bibliographically approved
    4. Sensitivity Features of Thin Film Plate Acoustic Wave Resonators
    Open this publication in new window or tab >>Sensitivity Features of Thin Film Plate Acoustic Wave Resonators
    2011 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 11, no 12, p. 3330-3331Article in journal (Refereed) Published
    Abstract [en]

    Thin film plate acoustic resonators devices operating in the lowest order symmetric Lamb wave mode (S0) in coriented aluminum nitride (AlN) membranes on Si were fabricated and tested for their sensitivities to pressure and mass as well as for their ability to work in liquid environment.

    Place, publisher, year, edition, pages
    IEEE Sensors Council, 2011
    Keywords
    Film bulk acoustic resonators, Resonant frequency, Sensitivity, Sensors, Surface acoustic waves
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-157877 (URN)10.1109/JSEN.2011.2158094 (DOI)000301878500019 ()
    Projects
    VR "Thin Film Guided Microacoustic Waves in Periodical Systems: Theory and Applications"
    Funder
    Swedish Research Council, 2009-5056
    Available from: 2011-08-24 Created: 2011-08-24 Last updated: 2017-12-08Bibliographically approved
    5. Highly Mass-Sensitive Thin Film Plate Acoustic Resonators (FPAR)
    Open this publication in new window or tab >>Highly Mass-Sensitive Thin Film Plate Acoustic Resonators (FPAR)
    Show others...
    2011 (English)In: Sensors, E-ISSN 1424-8220, Vol. 11, no 7, p. 6942-6953Article in journal (Refereed) Published
    Abstract [en]

    The mass sensitivity of thin aluminum nitride (AlN) film S0 Lamb wave resonators is theoretically and experimentally studied. Theoretical predictions based on modal and finite elements method analysis are experimentally verified. Here, two-port 888 MHz synchronous FPARs are micromachined and subsequently coated with hexamethyl-disiloxane(HMDSO)-plasma-polymerized thin films of various thicknesses. Systematic data on frequency shift and insertion loss versus film thickness are presented. FPARs demonstrate high mass-loading sensitivity as well as good tolerance towards the HMDSO viscous losses. Initial measurements in gas phase environment are further presented.

    Keywords
    resonator, aluminum nitride, membrane, HMDSO, gravimetric, sensitivity
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-157836 (URN)10.3390/s110706942 (DOI)000293069200027 ()
    Projects
    VR "Thin Film Guided Microacoustic Waves in Periodical Systems: Theory and Applications"
    Available from: 2011-08-24 Created: 2011-08-23 Last updated: 2022-02-10Bibliographically approved
    6. Thin-film zero-group-velocity Lamb wave resonator
    Open this publication in new window or tab >>Thin-film zero-group-velocity Lamb wave resonator
    2011 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, no 3, article id 033505Article in journal (Refereed) Published
    Abstract [en]

    A concept for the development of thin film micro-acoustic resonators is demonstrated. The basicprinciples for the design and fabrication of zero-group-velocity Lamb acoustic wave resonators onc-textured thin aluminum nitride films are presented. The experimental results demonstrate that thezero-group-velocity waves can be employed in high frequency resonators with small form factors.

    Keywords
    acoustic resonators, aluminium compounds, micromechanical resonators, surface acoustic waves
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-157833 (URN)10.1063/1.3614559 (DOI)000293679000069 ()
    Projects
    VR, "Thin Film Guided Microacoustic Waves in Periodical Systems: Theory and Applications"
    Funder
    Swedish Research Council, 2009-5056
    Available from: 2011-08-23 Created: 2011-08-23 Last updated: 2017-12-08Bibliographically approved
    7. An intermode-coupled thin-film micro-acoustic resonator
    Open this publication in new window or tab >>An intermode-coupled thin-film micro-acoustic resonator
    2012 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 8, p. 085004-Article in journal (Refereed) Published
    Abstract [en]

    A novel concept for the development of thin-film micro-acoustic resonators based on the coupling between different plate acoustic modes was demonstrated. The basic principles for the design and fabrication of intermode-coupled plate acoustic wave resonators on c-textured thin AlN films were presented and first experimental proof of coupling between laterally propagating waves and BAW was demonstrated. The experimental results demonstrate that the grating-assisted intermode coupling can be employed in high-frequency resonators inheriting the low dispersive nature of the S0 mode in combination with the energy localization in the plate bulk typical for the fundamental thickness shear resonance.

    Keywords
    acoustic resonator, aluminium nitride, Lamb wave, mode conversion
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Electronics; Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-178590 (URN)10.1088/0960-1317/22/8/085004 (DOI)000306649000004 ()
    Funder
    Swedish Research Council, 2009-5056
    Available from: 2012-08-01 Created: 2012-08-01 Last updated: 2017-12-07Bibliographically approved
    Download full text (pdf)
    fulltext
  • 45.
    Arapan, Lilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Anderås, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Yantchev, Ventsislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Sensitivity Features of Thin Film Plate Acoustic Wave Resonators2011In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 11, no 12, p. 3330-3331Article in journal (Refereed)
    Abstract [en]

    Thin film plate acoustic resonators devices operating in the lowest order symmetric Lamb wave mode (S0) in coriented aluminum nitride (AlN) membranes on Si were fabricated and tested for their sensitivities to pressure and mass as well as for their ability to work in liquid environment.

  • 46.
    Arapan, Lilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Avramov, Ivan
    Inst Solid State Physics, Bulgarian Academy of Sciences.
    Yantchev, Ventsislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thin film plate acoustic resonators for integrated microwave power oscillator applications2011In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 47, no 7, p. 452-453Article in journal (Refereed)
    Abstract [en]

    Two-port film plate acoustic resonators (FPAR) devices operating on the lowest order symmetric Lamb wave mode (S0) in C-oriented AlN membranes on Si were fabricated and tested for their power handling capabilities in a feedback-loop power oscillator circuit. The FPAR was operated at an incident power level of 24 dBm for several weeks without performance degradation. Its flicker noise constant was calculated from close-in phase noise data as αR=2.1×10^−36/Hz. The results indicate that IC-compatible S0 FPARs are well suited for integrated microwave oscillators with thermal noise floor (TNF) levels below −175 dBc/Hz.

  • 47.
    Arapan, Lilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Yantchev, Ventsislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    An intermode-coupled thin-film micro-acoustic resonator2012In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 8, p. 085004-Article in journal (Refereed)
    Abstract [en]

    A novel concept for the development of thin-film micro-acoustic resonators based on the coupling between different plate acoustic modes was demonstrated. The basic principles for the design and fabrication of intermode-coupled plate acoustic wave resonators on c-textured thin AlN films were presented and first experimental proof of coupling between laterally propagating waves and BAW was demonstrated. The experimental results demonstrate that the grating-assisted intermode coupling can be employed in high-frequency resonators inheriting the low dispersive nature of the S0 mode in combination with the energy localization in the plate bulk typical for the fundamental thickness shear resonance.

  • 48.
    Arapan, Lilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Yantchev, Ventsislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Alexieva, Gergana
    Dept of Solid State Physics and Microelectronics, University of Sofia.
    Strashilov, Vesseline
    Dept of Solid State Physics and Microelectronics, University of Sofia.
    Avramov, Ivan
    Georgy Nadjakov Institute of Solid State Physics, Sofia, Bulgarian Academy of Sciences.
    Radeva, Ekaterina
    Georgy Nadjakov Institute of Solid State Physics, Sofia, Bulgarian Academy of Sciences.
    Polymer coated thin film plate acoustic resonators (FPAR) for gas sensing applications2011In: 2011 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum Proceedings, San Fransisco, CA, USA, 2011Conference paper (Refereed)
    Abstract [en]

    Mass sensitivity of thin aluminum nitride (AlN) film S0 plate wave resonators is theoretically and experimentally studied. Here, two-port 888MHz synchronous thin film plate acoustic resonators (FPAR) are micromachined and subsequently coated with plasma-polymerized hexamethyldisiloxane (pp-HMDSO) thin films of various thicknesses. Systematic data on frequency shift and insertion loss versus film thickness are presented in a comparative manner. Measurements in gas phase environment are further presented in a comparative manner.

  • 49.
    Arayeshnia, Amir
    et al.
    Imam Khomeini Int Univ IKIU, Fac Tech & Engn, Qazvin, Iran.
    Madannejad, Alireza
    Univ Tehran, Sch Elect & Comp Engn, Tehran, Iran.
    Ebrahimizadeh, Javad
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Ravanbakhsh, Fatemeh
    Islamic Azad Univ, Sch Med Sci & Technol, Tehran, Iran.
    Perez, Mauricio D.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Augustine, Robin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Miniaturized CPW-fed bowtie slot antenna for wearable biomedical applications2020In: 2020 14th European Conference on Antennas and Propagation (EuCAP), 2020Conference paper (Refereed)
    Abstract [en]

    A miniaturized, low -profile, flexible, and wearable ultra-wideband antenna for biomedical applications is proposed. The antenna is designed to operate in wearable conditions with the presence of multilayer biological tissues. A meandering technique is employed to reduce the electrical size of the antenna. The operational band of the proposed antenna is 0.5-4.5 GHz, while its dimensions are as small as 21x19.25x0.025 mm3. The antenna is simulated using a commercial full-wave simulator (CST Microwave Studio), fabricated on Polyethylene terephthalate (PET), and tested in realistic scenarios. The simulation and measurement results are in good compliance with each other.

  • 50.
    Archetti, Joao A. G.
    et al.
    Univ Fed Juiz de Fora, Multiplatform Simulat Lab, Elect Engn Program, BR-36036900 Juiz De Fora, MG, Brazil..
    de Oliveira, Leonardo W.
    Univ Fed Juiz de Fora, Multiplatform Simulat Lab, Elect Engn Program, BR-36036900 Juiz De Fora, MG, Brazil..
    Oliveira, Janaína Goncalves de
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity. Univ Fed Juiz de Fora, Multiplatform Simulat Lab, Elect Engn Program, BR-36036900 Juiz De Fora, MG, Brazil..
    Hardware-in-the-Loop Volt-Watt and Volt-VAr Control for Distribution Systems with High Penetration of Renewables2023In: Journal of Control Automation and Electrical Systems, ISSN 2195-3880, Vol. 34, no 1, p. 177-188Article in journal (Refereed)
    Abstract [en]

    This work aims to validate in control hardware in the loop (CHIL) simulations new voltage profile control strategies in distribution systems with different levels of photovoltaic penetration. The proposed control is implemented through intelligent inverters with control functions that act through voltage sensitivity. The Volt-VAr (V-V) and Volt-Watt (V-W) functions act in the local voltage control being implemented in a complementary way. The simulations are performed in real time, using the real-time digital simulator. Residential load profiles, solar irradiance and temperature curves are discretized hourly over a daily period, with the intention of making the emulation more realistic. Voltage source converters were implemented in RSCAD software. The contribution of this article points to the performance of the Volt-Watt (V-W) control function in single-stage inverters, which allows the maximum generation of instantaneous active power, acting directly on the maximum power point tracking algorithm, this strategy being validated by the CHIL simulation. The results show that the Volt-VAr and Volt-Watt control functions, acting at different levels of photovoltaic penetration, were effective in preventing the voltage profiles from violating the critical level imposed by the regulatory standard. Leading to the conclusion that its implementation directly in photovoltaic inverters entails a low cost and a complementary solution for the new challenges of electrical systems.

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