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  • 151.
    Eriksson, Oskar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Björnemo, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Ahlén, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Gidlund, Mikael
    On Hybrid ARQ Adaptive Forward Error Correction in Wireless Sensor Networks2011Inngår i: IECON 2011: 37TH ANNUAL CONFERENCE ON IEEE INDUSTRIAL ELECTRONICS SOCIETY, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The use of wireless technology in the process industry is becoming increasingly important to obtain fast deployment at low cost. However, poor channel quality often leads to retransmissions, which are governed by Automatic Repeat Request (ARQ) schemes. While ARQ is a simple and useful tool to alleviate packet errors, it has considerable disadvantages: retransmissions lead to an increase in energy expenditure and latency. The use of Forward Error Correction (FEC) however offers several advantages. We consider a Hybrid-ARQ-Adaptive-FEC scheme (HAF) based on BCH codes and Channel State Information. This scheme is evaluated on AWGN and fading channels. It is shown that HAF offers significantly improved performance both in terms of energy efficiency and latency, as compared to ARQ.

  • 152.
    Ersvik, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Analysis of reliability and energy consumption in industrial wireless sensor networks2012Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Wireless sensor networks have attracted the interest of the process industry. A process plant typically contains thousands of devices, monitoring or controlling the process. Today, all these devices are usually connected with wires. Using wireless technology simplifies deployment of new devices in a network and eliminates the need for extensive wiring. But wireless communication is also more sensitive than its wired counterpart. Therefore work is needed to make wireless sensor networks a viable option in many applications. Important issues are, for example, robustness, energy efficiency, and latency. One of the leading communication protocols for industrial wireless sensor networks is the WirelessHART protocol. This thesis investigates three ways of improving performance of the protocol, in terms of reliability and energy requirements. First, the structure of a WirelessHART packet is studied and the removal of certain fields is suggested to make the communication overhead smaller. Second, forward error correcting codes are evaluated using simulations in MATLAB. Third, measurement experiments in actual industrial environments are conducted where radio signals are transmitted and received. The variability of the received signal strength is measured and the effect that polarization diversity has on the signal variability is analyzed. The findings indicate that substantial improvements can be attained by employing polarization diversity, which can reduce channel variability and increase the expected signal strength significantly. The improvements in channel gain can be on the order of several tens of dB. The evaluations of forward error correcting codes show that the reliability is improved, with a channel gain of 3 dB. The study of the WirelessHART packet structure indicate that the packet sizes can be reduced by 15%. In turn, this also reduces energy requirements and packet error rates by 15%. This is equivalent to a gain in SNR on the order of a tenth of a dB.

  • 153.
    Ferguson, Joel
    et al.
    Univ Newcastle, Sch Elect Engn & Comp, Callaghan, NSW 2308, Australia.;Univ Newcastle, PRC CDSC, Callaghan, NSW 2308, Australia..
    Donaire, Alejandro
    Univ Naples Federico II, Prisma Lab, Naples, Italy.;Univ Newcastle, Callaghan, NSW, Australia..
    Knorn, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Middleton, Richard H.
    Univ Newcastle, Sch Elect Engn & Comp, Callaghan, NSW 2308, Australia.;Univ Newcastle, PRC CDSC, Callaghan, NSW 2308, Australia..
    Decentralized control for l(2) weak string stability of vehicle platoon2017Inngår i: 20th IFAC World Congress, Elsevier, 2017, Vol. 50, nr 1, s. 15012-15017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we present a method of bidirectional control of a vehicle string that achieves l(2) weak string stability. Previous work required short-range communications between vehicles within the string. Here, we utilise some recent results on integral action to remove the requirement of communications altogether. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 154.
    Ferrari, Arnaud
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Ekelöf, Tord
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Ziemann, Volker
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Gourie, Gabriel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Cheng, Shi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Öjefors, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Johnson, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Results of the EUROTeV Confocal Beam Position Monitor (CPBM) Task2008Rapport (Annet vitenskapelig)
    Abstract [en]

    This paper is the deliverable of the EUROTeV Confocal Beam Position Monitor(CPBM) task and gives an overview of the published results.

  • 155. Ferrari, Riccardo M.G.
    et al.
    Teixeira, André
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Detection and isolation of routing attacks through sensor watermarking2017Inngår i: 2017 Am. Control Conf., IEEE , 2017, s. 5436-5442Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In networked control systems, leveraging the peculiarities of the cyber-physical domains and their interactions may lead to novel detection and defense mechanisms against malicious cyber-attacks. In this paper, we propose a multiplicative sensor watermarking scheme, where each sensor's output is separately watermarked by a Single Input Single Output (SISO) filter. Hence, such scheme does not require communication between multiple sensors, but can still lead to detection and isolation of malicious cyber-attacks. In particular, we analyze the benefits of the proposed watermarking scheme for two attack scenarios: the physical sensor re-routing attack and the cyber measurement re-routing one. For each attack scenario, detectability and isolability properties are analyzed with and without the proposed watermarking scheme and we show how the watermarking scheme can be leveraged to detect cyber sensor routing attacks. In order to detect compromised sensors, we design an observer-based detector with a robust adaptive threshold. Additionally, we identify the sensors involved in the re-routing attacks by means of a tailored Recursive Least Squares parameter estimation algorithm. The results are illustrated through a numerical example.

  • 156.
    Fjällstrom, Eva
    et al.
    Lulea Univ Technol, Dept Arts Commun & Educ, Lulea, Sweden.
    Forsberg, Christoffer
    Lulea Univ Technol, Dept Comp Sci Elect & Space Engn, Lulea, Sweden.
    Trulsson, Felix
    Lulea Univ Technol, Dept Comp Sci Elect & Space Engn, Lulea, Sweden.
    Knorn, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Staffas, Kjell
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Varagnolo, Damiano
    Norwegian Univ Sci & Technol, Dept Engn Cybernet, Trondheim, Norway.
    Wrigstad, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Courses-Concepts-Graphs as a Tool to Measure the Importance of Concepts in University Programmes2019Inngår i: 2019 18th European Control Conference (ECC), IEEE, 2019, s. 3076-3083Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper investigates methods for quantitatively assessing the importance and relative importance of concepts taught in a university program. This assessment has many uses, e.g., to aid program design and inventory, and for communicating what concepts a course may rely on at a given point in the program. We propose to perform this quantitative assessment in two steps: first, representing the university program as an opportune graph with courses and concepts as nodes and connections between courses and concepts as edges; second, by quantitatively defining each concept's importance as its centrality as a node within the network. We thus perform two investigations, both leveraging a practical case - data collected from two engineering programs at two Swedish university: a) how to represent university programs in terms of graphs (here called Courses-Concepts Graph (CCG)), and b) how to reinterpret the most classical graph-theoretical node centrality indexes in the pedagogical term of concept centrality index.

  • 157. Fjällström, E
    et al.
    Knorn, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Staffas, Kjell
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Varagnolo, D
    Developing concept inventory tests for electrical engineering (CITE): extractable information, early results and learned lessons2018Konferansepaper (Fagfellevurdert)
  • 158. Fjällström, Eva
    et al.
    Atta, Khalid
    Knorn, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sandin, Fredrik
    Sas, Gabriel
    Staffas, Kjell
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Teixeira, André
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Varagnolo, Damiano
    Creating a quantitative basis for course and program development in higher education - a report from field tests2019Konferansepaper (Fagfellevurdert)
  • 159.
    Fjällström, Eva
    et al.
    Lulea Univ Technol, Lulea, Sweden.
    Knorn, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Staffas, Kjell
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Varagnolo, Damiano
    Lulea Univ Technol, Lulea, Sweden.
    Developing Concept Inventory Tests for Electrical Engineering: extractable information, early results, and learned lessons2018Inngår i: 2018 UKACC 12th International Conference on Control (CONTROL), IEEE, 2018, s. 436-441Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper suggests a method for developing, implementing and assessing a concept inventory test for electrical engineering students (CITE). The aim of this test is to help students better understand and learn core concepts, plus increase their awareness about links between the different courses and other themes of the program. Our and other experiences show that students often struggle to understand and use fundamental concepts, and how these relate to the various courses. This issue is probably due to the fact that traditional exams mainly focus on assessing procedural tasks (e.g., directly solving specific problems following step-by-step approaches). The investigated programs at Uppsala University (UU) and Lulea University of Technology (LTU), nonetheless, have no tool for collecting quantitative data on how students develop conceptual knowledge throughout the programs, and thus no means to obtain an holistic view about their learning process. The here proposed methodology thus describes how to develop tests that would not only provide students with valuable feedback on their progression, but also equip teachers and program boards with high-end data for pedagogical and course development purposes. Besides illustrating the developmental methodology, the paper includes reactions and remarks from students on what the tests would provide and what would motivate them to take it.

  • 160.
    Flink, Oskar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Wireless electrocardiogram transmission based on ultra wideband radio2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Ultra wideband (UWB) communications has been a subject of much discussion over the last decade. The method of UWB has had a hard time to establish itself among other methods such as Bluetooth and WiFi but as internet of things (IoT) gains a foothold in our daily lives, UWB has presented some new application areas. These application areas are, among other things, self driving cars, energy efficient data transfer, health care applications, sensor networks and real time location systems. This project aims to use UWB communications to real-world applications, specifically, electrocardiography (ECG) - an application in health care in this project, and develop a prototype for the application. The prototype consists of two Android smart phones and two UWB modules (EVK1000 evaluation kits from DecaWave, Inc). Each smartphone connects a UWB module so that the two smart phones, one as sender and the other as receiver, can communicate directly through UWB radios. This is intended to serve as a proof-of-concept that UWB devices are well suited for short range data transfer applications. The result achieved by the project is an android application along with sending and receiving programs for the development boards by Decawave and additional information regarding UWB and its uses. The results also include a comparison of UWB, Bluetooth and WiFi as of todays standard. The goal of the project is to learn how android applications are programmed, how UWB is used in todays technology and how to program and use development boards presented by companies. The prototype has been built and shown that 12-lead simulated ECGsignals from the sender can be transfered to the receiver through the UWB communications. The work includes programming (in C) the two UWB modules for UWB communications, and Java for the android applications (programs) on the smart phones. The Android application is handling transmission of ECG signals to the sending UWB module and then receiving them from the receiving UWB module as well as displaying them on the receiver. The future work to continue the present project is to replace the sending smart phone by an ECG device that sends real ECG signals.

  • 161.
    Flodén, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Prototyping a wireless ECG system with an automatically tunable notch filter.2019Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    In this thesis an electrocardiography (ECG) prototype is developed that wireless transfer the ECG measurements to an Android smartphone. The prototype consist of two printed circuit boards (PCBs), an Android smartphone and an automatically tunable notch filter.

    The first PCB is intended for performing ECG measurements using three electrodes placed on a body and transferring the ECG data to thesecond PCB wireless via ultra-wideband (UWB). The second PCB is used to receive the ECG data via UWB communications and then transfer it to the Android smartphone through a USB cable. An automatically tunable notch filter is implemented to remove the 50 Hz power lineinterference in the ECG measurement data. And finally, an Android application is developed to display the ECG data to the user in realtime.

    The finished prototype is tested and shown to be successful. The ECG measurements can be transmitted from the transmitting to the receiving PCB over UWB and then displayed graphically in real-time on an Android smartphone. The automatically tunable notch filter is simulated and shown to able to remove power line interference.

  • 162.
    Forsslund, Ola
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Automatic trimming of ultrasonic pulse in fiber-optical power spectrometer2009Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this master's thesis is to develop a method that fully automates a trimming step in the production of a fiber-optical power spectrometer, based on a unique Acusto-Optical Scanning Filter.

    The filter is created by letting an ultrasonic mechanical pulse pass through a chirped Fiber Bragg Grating. The pulse introduces a disturbance in the grating, creating a thin optical transmission window in the otherwise reflective bandwidth. The high demands on the window requires a precise, unit dependent pulse form with unknown properties. Thus each unit needs to be trimmed to reach required performance.

    The manual trimming is largely a trial and error process, that contains two performance tests. We redefine one, eliminating the need to reroute the optical path and reducing the number of fiber weldings. The tests are then quantified, allowing a figure of merit to be based on weighted performance values.

    A brute force method, testing a large set of pulses, is implemented. The set is defined by the parameter space spanned by previously produced units. Due to the large space, the method is too time consuming. Instead it is used to measure the performance spaces of three units. An attempt to largely reduce the parameter space using PCA failed.

    An alternating variables method that finds local performance optima in the parameter space is developed. By using a set of several starting points, the method tends to find several qualified pulses. The method is implemented and successfully verified by trimming new units.

    Finally we propose where to focus improvements of the method in a production ramp up.

  • 163. Freyhult, EK
    et al.
    Andersson, K
    Gustafsson, Mats G
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Structural modeling extends QSAR analysis of antibody-lysozome interactions to 3D-QSAR2003Inngår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 84, nr 4, s. 2265-2272Artikkel i tidsskrift (Fagfellevurdert)
  • 164.
    Fällman, Oscar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Jönsson, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Testsystem av kontrollsystem för klystronmodulatorer2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    The company, ScandiNova Systems, has had a need for a test system that can automate and optimize fault detection of the digitizer circuit in the control system of their klystron modulators. This thesis work is intended for this need with the aim of constructing a test system built in LabVIEW, and a pulse generator to generate stimulation for the digitizer circuit board. The test system has been tested and the results have shown that it works well for the given circumstances. The analysis of how the digitizer circuit reads an analog signal works almost perfectly, given an 5%-tolerance interval from the reference value of how the pulse should be. However, not all of the digital outputs of the digitizer can be checked for faults with the current configuration of the circuit board. If the FPGA-code on the digitizer circuit is revised with the pulses of the pulse generator the Boolean error outputs of the FPGA can be correctly checked.

     

    If a test system is to be created for other circuits in the control system based on the work done in this thesis project, the parts specified for the present circuit shall be removed from the LabVIEW-program. For example, almost all parts of the GUI that are specified for the digitizer circuit, the stepping of the DIP-switches etc,, shall be removed. Stimuli for the circuits shall also be created according to their specifications.

  • 165.
    Gerami, Majid
    et al.
    Royal Inst Technol, KTH, Sch Elect Engn, Stockholm, Sweden.
    Xiao, Ming
    Royal Inst Technol, KTH, Sch Elect Engn, Stockholm, Sweden.
    Salimi, Somayeh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Skoglund, Mikael
    Royal Inst Technol, KTH, Sch Elect Engn, Stockholm, Sweden.
    Papadimitratos, Panos
    Royal Inst Technol, KTH, Sch Elect Engn, Stockholm, Sweden.
    Optimal Secure Partial-Repair in Distributed Storage Systems2017Inngår i: 2017 51st Annual Conference on Information Sciences and Systems (CISS), IEEE, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Consider a distributed storage system where parts of the source file fragments in storage nodes are lost. We denote a storage node that lost a part of its fragments as a faulty storage node and a storage node that lost non of its fragment as a complete storage node. In a process, termed as partial repair, a set of storage nodes (among faulty and complete storage nodes) transmit repairing fragments to other faulty storage nodes to recover the lost fragments. We first investigate the optimal partial repair in which the required bandwidth for recovering the lost fragments is minimal. Next, we assume that an eavesdropper wiretaps a subset of links connecting storage nodes, and overhears a number of repairing fragments. We then study optimal secure partial-repair in which the partial-repair bandwidth is minimal and the eavesdropper obtains no information about the source file by overhearing the repairing fragments. We propose optimal secure codes for exact partial-repair in a special scenario.

  • 166.
    Gollbo, Simon
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Development of a platform for evaluating a GNSS positioning system2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The project aims to develop a platform for the demonstration and evaluation of Global Navigation Satellite Systems (GNSSs). The GNSS receivers used in the project are two uBlox NEO-M8P modules, one of which is used as a reference receiver in a differential GNSS setup.

    The entire platform has been implemented and consists of a network-controlled car (NetCar) which has a GNSS receiver and a 4G module on it, a separate reference GNSS receiver, a computer hosting a control interface for controlling the NetCar and a relay server for relaying data between the control interface and the NetCar.

    The platform has been tested for evaluating the GNSS. The performance was evaluated in terms of the time to first fix (TTFF), stationary positioning accuracy and tracking accuracy which includes qualitative evaluation of accuracy, statistical evaluation of accuracy and evaluation of absolute accuracy after moving. The test results show that the platform performed well for the demonstration and evaluation of the GNSS. The evaluation results show that the TTFF for the uBlox NEO-M8P used in the project averaged 24.2 s with a worst case of 33 s. The stationary positioning accuracy was found to drift in the order of tens of centimeters when using differential GNSS in RTK float mode and in the order of centimeters in RTK fixed mode. The relative trackingaccuracy between points during either RTK mode was found to be on the order of centimeters while the absolute accuracy was found to be drifting, probably due to the reference receiver position being acquired through self-survey. The current project can be extended further by including automatic navigation, sensor fusion, pathfinding and the like.

  • 167.
    Gollbo, Simon
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sköld, Adam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Base stations for communication in obstructed environments2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The purpose of this project was to produce signal relay stations that could receive information via 2.4 GHz radio and relay the information to a designated target station. If a relay station was located outside of signal range for the target station it was supposed to utilize other relay stations to transfer the information to the target station, so called multi-hop.

    The would-be application of the relay stations was orienteering. When an orienteer punches a checkpoint the signal stations would relay information of who punched the control, when it was punched and the checkpoint that was punched to the speaker tower in the goal area.

    The work resulted in prototypes which fulfilled the statement of purpose and was tested at an orienteering competition with satisfactory results. The performance of the prototypes was tested and found adequate for the would-be application.

  • 168.
    Gotthold, Oscar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Larsson, Victor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Utveckling av ett digitalt reglersystem för styrning och kontroll av en seismisk vibratorkälla2017Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    The report describes how a control system has been developed to dampen known resonance frequency and optimize excitation at other frequencies of a seismic vibrator source. This vibrator source is used to excite energy at the surface of reflection seismic surveys.The resonance frequency dominates the excited signal, which results in limitations of the systems performance. The vibrator source is excited with a power amplifier that receives a control signal from a chirp signal generator. During the project, a chirp generator, as well as a control system, was programmed in Labview, and tested boththrough simulations and in the laboratory. Initially, it was investigated whether it was possible to regulate the system, partly for resonance attenuation and also for optimization of excitation at other frequencies, using a PID controller. However, this proved to be overly advanced and time consuming to perform in a ten-week project. Therefore, the system was regulated by envelope compensation, which both dampened resonance and optimized excitation at other frequencies.

  • 169.
    Goude, Kim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Development of an FPGA-based digital filter platform2017Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    This project has the aim of developing a digital filter platform based on an FPGA IC (field-programmable gate array integrated circuit). The platform can be used to design and realize digital filters of various types, such as lowpass (LP), highpass (HP), bandpass (BP) and band stop (BS) filters, in the category of either finte impulse response (FIR) or infinite impulse response (IIR). Its hardware consists of a Terasic DE1-SoC development board (having an Altera Cyclone V FPGA IC, and 10 switches plus 4 buttons on it) and a QC2004A LCD display. The LCD display together with the switches and buttons constitute the human machine interface with which the filter category (FIR or IIR) can be selected and the desired filter can be specified with cutoff frequencies, bandwidth, filter’s order, and so on. The FPGA is programmed using VHDL (VHSIC Hardware Description Language). The present project is continued from an earlier project that had already developed a platform that can create FIR filters of LP and HP with a fixed order (32th) and IIR filters of LP, HP and BS with the first and second orders. It has extended the FIR filters with selectable filter order up to 64th order and the IIR filters with up to the 6th order.

    The FIR filters are shown to fully function as expected. But the IIR filters work partly. In particular, the calculated coefficients for the IIR filters are sometimes correct, and the Altera Cyclone V FPGA IC is not powerful enough for higher filter order, e.g., 6th order.

  • 170.
    Granbom, Markus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Förenklad felinformation på trafikinformationsutrustning2013Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    This thesis lays the foundation of the future routines of effective error repotring fortraffic devices in the raiway sector.If a device, for example a timetable display, stops working it is vital that the device isfixed as fast as possible so that the travelers dont miss any important information.The methods that are used today are old and not very effective. It can take time forthe repairmen to find the right device or locating the broken component. At the sametime he is supposed to maintain telephone contact with central control throughoutthe whole session.The need for a new, more effective, system is vital to make the whole repair pfocessmore effective and let the repairmen work without having to contact the centralcontrol by phone.I started this work by examining the possibilities of assigning every object with aunique identifier (ID tag) that could be accessed by a manual scan device. The ideawas that the ID tag could holw information about the object and be obtained byscanning the ID and get the information presented on a mobile device.The work also included building a internet application that enabled the reader to seeand change the information on the ID tag.The result was a database that stored information of different objects which could beobtained by scanning the ID tag and presented by a internet application.

  • 171.
    Grudén, Mathias
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrovågs- och terahertzteknik.
    Westman, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Platbardis, Janis
    TNT-Elektronik AB, Säter.
    Hallbjörner, Paul
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrovågs- och terahertzteknik.
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrovågs- och terahertzteknik.
    Reliability Experiments for Wireless Sensor Networks in Train Environment2009Inngår i: European Microwave Week (EuMWeek), Second European Wireless Technology Conference, EuWIT, 2009, s. 37-40Konferansepaper (Fagfellevurdert)
  • 172. Guo, X
    et al.
    He, Y
    Atapattu, S
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Evans, J
    Power allocation for distributed detection systems in wireless sensor networks with limited fusion centre feedback2018Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 66, nr 10, s. 4753-4766Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider a distributed detection system for a wireless sensor network over slow-fading channels. Each sensor only has knowledge of quantized channel state information (CSI) which is received from the fusion center via a limited feedback channel. We then consider transmit power allocation at each sensor in order to maximize a J-divergence based detection metric subject to a total and individual transmit power constraints. Our aim is to jointly design the quantization regions of all sensors CSI and the corresponding power allocations. A locally optimum solution is obtained by applying the generalized Lloyd algorithm (GLA). To overcome the high computational complexity of the GLA, we then propose a low-complexity near-optimal scheme which performs very close to its GLA based counterpart. This enables us to explicitly formulate the problem and to find the unique solution despite the non-convexity of the optimization problem. An asymptotic analysis is also provided when the number of feedback bits becomes large. Numerical results illustrate that only a small amount of feedback is needed to achieve a detection performance close to the full CSI case.

  • 173.
    Guo, Xiaoxi
    et al.
    Univ Melbourne, Dept Elect & Elect Engn, Parkville, Vic 3010, Australia.
    Leong, Alex S
    Univ Paderborn, Dept Elect Engn, D-33098 Paderborn, Germany.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Distortion outage minimization in distributed estimation with estimation secrecy outage constraints2017Inngår i: IEEE Transactions on Signal and Information Processing over Networks, E-ISSN 2373-776X, Vol. 3, nr 1, s. 12-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we investigate a class of distortion outage minimization problems for a wireless sensor network in the presence of an eavesdropper. The observation signals transmitted from the sensors to the fusion center (FC) are overheard by the eavesdropper. Both the FC and the eavesdropper reconstruct minimum mean squared error estimates of the physical quantity observed. We address the problem of transmit power allocation to minimize the distortion outage at the FC, subject to an expected total transmit power constraint across the sensor(s) and a secrecy outage constraint at the eavesdropper. Applying a rigorous probabilistic power allocation technique, we derive power policies for the full channel state information (CSI) case. Suboptimal power control policies are studied for the partial CSI case in order to reduce the high computational cost associated with large numbers of sensors or receive antennas. Numerical results show that significantly improved performance can be achieved by adding multiple receive antennas at the FC. In the case of multiple transmit antennas, the distortion outage at the FC can be dramatically reduced and in some cases completely eliminated, by transmitting the observations on the null space of the eavesdropper's channel or deploying an artificial noise technique, in the full CSI and partial CSI cases, respectively.

  • 174.
    Guo, Xiaoxi
    et al.
    Univ Melbourne, Dept Elect & Elect Engn, Melbourne, Vic 3010, Australia..
    Leong, Alex S.
    Paderborn Univ, Dept Elect Engn EIM E, D-33098 Paderborn, Germany..
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Estimation in Wireless Sensor Networks With Security Constraints2017Inngår i: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 53, nr 2, s. 544-561Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we investigate the performance of distributed estimation schemes in a wireless sensor network in the presence of an eavesdropper. The sensors transmit observations to the fusion center (FC), which at the same time are overheard by the eavesdropper. Both the FC and the eavesdropper reconstruct a minimum mean-squared error estimate of the physical quantity observed. We address the problem of transmit power allocation for system performance optimization subject to a total average power constraint on the sensor(s), and a security/secrecy constraint on the eavesdropper. We mainly focus on two scenarios: 1) a single sensor with multiple transmit antennas and 2) multiple sensors with each sensor having a single transmit antenna. For each scenario, given perfect channel state information (CSI) of the FC and full or partial CSI of the eavesdropper, we derive the transmission policies for short-term and long-term cases. For the long-term power allocation case, when the sensor is equipped with multiple antennas, we can achieve zero information leakage in the full CSI case, and dramatically enhance the system performance by deploying the artificial noise technique for the partial CSI case. Asymptotic expressions are derived for the long-term distortion at the FC as the number of sensors or the number of antennas becomes large. In addition, we also consider multiple-sensor multiple-antenna scenario, and simulations show that given the same total number of transmitting antennas the multiple-antenna sensor network is superior to the performance of the multiple-sensor single-antenna network.

  • 175.
    Guo, Xiaoxi
    et al.
    Department of Electrical and Electronic Engineering, The University of Melbourne, VIC 3010, Australien.
    Leong, Alex S
    Department of Electrical and Electronic Engineering, The University of Melbourne, VIC 3010, Australien.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Power allocation for distortion minimization in distributed estimation with security constraints2014Inngår i: 2014 IEEE 15th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), 2014, s. 299-303Konferansepaper (Fagfellevurdert)
  • 176.
    Guo, Xiaoxi
    et al.
    Univ Melbourne, Dept Elect & Elect Engn, Melbourne, Vic 3010, Australia..
    Leong, Alex S.
    Univ Melbourne, Dept Elect & Elect Engn, Melbourne, Vic 3010, Australia..
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Power Allocation for Estimation Outage Minimization with Secrecy Outage Constraints2016Inngår i: 2016 Australian Communications Theory Workshop (AusCTW), New York: IEEE, 2016, s. 71-76Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we investigate the distortion outage minimization problem for a wireless sensor network (WSN) in the presence of an eavesdropper. The observation signals transmitted from the sensors to the fusion center (FC) are overheard by the eavesdropper. Both the FC and the eavesdropper reconstruct minimum mean squared error (MMSE) estimates of the physical quantity observed. We address the problem of transmit power allocation to minimize the distortion outage at the FC, subject to a long-term transmit power constraint among the sensors and a secrecy outage constraint at the eavesdropper. Applying a rigorous probabilistic power allocation technique we derive power policies for the full channel state information (CSI) case. Additional suboptimal power control policies are studied for the partial CSI case in order to reduce the high computational cost as the number of sensors or receive antennas grows. Numerical results show better performance can be achieved by adding multiple receive antennas at the FC.

  • 177.
    Gustafsson, Leif
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sternad, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    A guide to population modelling for simulation2016Inngår i: Open Journal of Modelling and Simulation, nr 4, s. 55-92Artikkel i tidsskrift (Fagfellevurdert)
  • 178.
    Gustafsson, Leif
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sternad, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Consistent micro, macro and state-based population modelling2010Inngår i: Mathematical Biosciences, ISSN 0025-5564, E-ISSN 1879-3134, Vol. 225, nr 2, s. 94-107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A population system can be modelled using a micro model focusing on the individual entities, a macro model where the entities are aggregated into compartments, or a state-based model where each possible discrete state in which the system can exist is represented. However, the concepts, building blocks, procedural mechanisms and the time handling for these approaches are very different. For the results and conclusions from studies based on micro, macro and state-based models to be consistent (contradiction-free), a number of modelling issues must be understood and appropriate modelling procedures be applied. This paper presents a uniform approach to micro, macro and state-based population modelling so that these different types of models produce consistent results and conclusions. In particular, we demonstrate the procedures (distribution, attribute and combinatorial expansions) necessary to keep these three types of models consistent. We also show that the different time handling methods usually used in micro, macro and state-based models can be regarded as different integration methods that can be applied to any of these modelling categories. The result is free choice in selecting the modelling approach and the time handling method most appropriate for the study without distorting the results and conclusions.

  • 179.
    Gustafsson, Leif
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sternad, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    When can a deterministic model of a population system reveal what will happen on average?2013Inngår i: Mathematical Biosciences, ISSN 0025-5564, E-ISSN 1879-3134, Vol. 243, nr 1, s. 28-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dynamic population system is often modelled by a deterministic difference equation model to obtain average estimates. However, there is a risk of the results being distorted because unexplained (random) variations are left out and because entities in the population are described by continuous quantities of an infinitely divisible population so that irregularly occurring events are described by smooth flows. These distortions have many aspects that cannot be understood by only regarding a deterministic approach. However, the reasons why a deterministic model may behave differently and produce biased results become visible when the deterministic model is compared with a stochastic model of the same structure. This paper focuses first on demographic stochasticity, i.e. stochasticity that refers to random variations in the occurrence of events affecting the state of an individual, and investigates the consequences of omitting this by deterministic modelling. These investigations reveal that bias may be strongly influenced by the type of question to be answered and by the stopping criterion ending the analysis or simulation run. Two cases are identified where deterministic models produce unbiased state variables: (1) Dynamic systems with stable local linear dynamics produce unbiased state variables asymptotically, in the limit of large flows; and (2) linear dynamic systems produce unbiased state variables as long as all state variables remain non-negative in both the deterministic and the stochastic models. Both cases also require the question under study to be compatible with a solution over a fixed time interval. Stochastic variability of initial values between simulation runs because of uncertainty or lack of information about the initial situation is denoted initial value stochasticity. Elimination of initial value stochasticity causes bias unless the model is linear. It may also considerably enlarge bias from other sources. Unknown or unexplained variations from the environment (i.e. from outside the borders of the studied system) enter the model in the form of stochastic parameters. The omission of this environmental stochasticity almost always creates biased state variables. Finally, even when a deterministic model produces unbiased state variables, the results will be biased if the output functions are not linear functions of the state variables.

  • 180.
    Gustafsson, Leif
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sternad, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Gustafsson, E
    The full potential of continuous system simulation modelling2017Inngår i: Open Journal of Modelling and SimulationArtikkel i tidsskrift (Fagfellevurdert)
  • 181.
    Gustafsson, MG
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System. SIGNALS AND SYSTEMS.
    A probabilistic derivation of the partial least-squares algorithm2001Inngår i: JOURNAL OF CHEMICAL INFORMATION AND COMPUTER SCIENCES, ISSN 0095-2338, Vol. 41, nr 2, s. 288-294Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Traditionally the partial least-squares (PLS) algorithm, commonly used in chemistry for ill-conditioned multivariate linear regression, has been derived (motivated) and presented in terms of data matrices. In this work the PLS algorithm is derived probabi

  • 182.
    Gustavsson, Anna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Reliable Network Communication2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The Target Positioning Sensor (TPS) is used by cranes to locate containers in ports and on cargo ships. The reliability of the communication network between the TPS and the Programmable Logic Controller (PLC) is important to optimise the productivity of the container terminal. Lost data messages between the network devices will lead to delays and production loss for the terminal.

    The main goal of this thesis project is to make the Ethernet-based network between the TPS and the PLC more reliable. The current sensor network protocol uses the User Datagram Protocol (UDP), and the project aims to replace that with the Transport Control Protocol (TCP). This includes designing a new message handling application and performing case studies on how to best handle compatibility issues between the TPS and the PLC, to improve the longevity of the application. The case studies led to considering an adaptable behaviour toward future software updates in different parts of the network.

    An application which used TCP to communicate between a PC and a PLC was developed, intended to be used as a reference during future integration into the actual sensor network. The TCP application works but needs to be improved before being implemented in a real system.

    In addition, the project also looked into Time-Sensitive Networking, which is a method of increasing link capacity and reliability in time-sensitive network implementations. This was done through a literature study on the IEEE Time-Sensitive Networking Standard, which showed that the application of the standard could be beneficial if more sensors are added to the network of if the sampling frequency of the TPS is increased.

  • 183.
    Hallbjörner, Paul
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Cheng, Shi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Karlsson, K
    Modified planar inverted code antenna for mobile communication handsets2007Inngår i: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 6, s. 472-475Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The planar inverted cone antenna (PICA) is an antenna type that shows remarkably wideband performance. In its basic configuration, it is mounted on an infinite ground plane, and protrudes lambda/4 above it. This letter presents a study of the possibilities of integrating a PICA in a mobile terminal handset by modifying the ground plane and the radiating element. Port impedance and radiation performance are studied in both simulations and measurement.

  • 184.
    Hallbjörner, Paul
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Skarin, Ingvar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    From, Kajsa
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Circularly polarized traveling-wave array antenna with novel microstrip patch element2007Inngår i: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 6, s. 572-574Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A traveling-wave microstrip array antenna with circular polarization in presented. It uses a novel circularly polarized dual-feed radiating element. The element is a square microstrip patch with a chamfered corner. It is fed by microstrip lines, so radiating element and feed lines can be realized in a single layer. A five-element array is designed and built. Measured performance is presented.

  • 185.
    Hallvig, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Fuel Consumption Tuning for Electric All Wheel Drive System2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This report investigates methods to reduce fuel consumption in SAAB's prototype hybrid car. It is primarily concerned with changes in the final drive ratio (FDR) of the gearbox. Reducing the FDR lowers the engine speed, allowing the engine to run at a more efficient operating point. However, this has a negative impact on engine power and vehicle performance. It was thought that the hybrid's eXWD (electric cross wheel drive) system could make up for this loss of performance.

    Computer simulations showed significant improvements in fuel economy when the FDR was reduced. This was confirmed by real world tests on a chassis dynamometer, although the number of tests were too low to establish the precise fuel consumption reduction. The effects on performance were evaluated by creating a quasi static model of the drivetrain and calculating which combinations of speed and acceleration corresponded to the engine's torque limits. The loss of acceleration was found to be lower than the increase in acceleration made possible by eXWD for most choices of FDR. It is therefore possible to reduce the FDR in the hybrid version of the car and still maintain a performance advantage compared to the front wheel drive version. No other major disadvantageous effects were found. The conclusion was therefore that a reduction of the final drive ratio is a feasible method to improve the fuel economy of the prototype car, given that maximizing performance is deemed less important than increasing fuel economy. 

  • 186.
    Hammarberg, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    A Signal Processing Approach to Practical Neurophysiology: A Search for Improved Methods in Clinical Routine and Research2002Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Signal processing within the neurophysiological field is challenging and requires short processing time and reliable results. In this thesis, three main problems are considered.

    First, a modified line source model for simulation of muscle action potentials (APs) is presented. It is formulated in continuous-time as a convolution of a muscle-fiber dependent transmembrane current and an electrode dependent weighting (impedance) function. In the discretization of the model, the Nyquist criterion is addressed. By applying anti-aliasing filtering, it is possible to decrease the discretization frequency while retaining the accuracy. Finite length muscle fibers are incorporated in the model through a simple transformation of the weighting function. The presented model is suitable for modeling large motor units.

    Second, the possibility of discerning the individual AP components of the concentric needle electromyogram (EMG) is explored. Simulated motor unit APs (MUAPs) are prefiltered using Wiener filtering. The mean fiber concentration (MFC) and jitter are estimated from the prefiltered MUAPs. The results indicate that the assessment of the MFC may well benefit from the presented approach and that the jitter may be estimated from the concentric needle EMG with an accuracy comparable with traditional single fiber EMG.

    Third, automatic, rather than manual, detection and discrimination of recorded C-fiber APs is addressed. The algorithm, detects the Aps reliably using a matched filter. Then, the detected APs are discriminated using multiple hypothesis tracking combined with Kalman filtering which identifies the APs originating from the same C-fiber. To improve the performance, an amplitude estimate is incorporated into the tracking algorithm. Several years of use show that the performance of the algorithm is excellent with minimal need for audit.

  • 187.
    Hammarberg, Björn
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Forster, C
    Torebjörk, E
    Parameter estimation of human nerve C-fibers using matched filtering and multiple hypothesis tracking2002Inngår i: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 49, nr 4Artikkel i tidsskrift (Fagfellevurdert)
  • 188.
    Hammarstedt, Ola
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Fall detection bracelet with an accelerometer and cellular connectivity2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis aims at developing a prototype for a fall detection bracelet that can connect to the cellular network. The bracelet consists of a processing unit, three sensors, a LTE USB modem and a powerbank.

    The prototype is aimed at elderly people since up to one out of three over the age of 65-years-old fall each year. Besides elderly people this system can be used in activities which involves substantial height, e.g. climbing and roofing. Statistics has shown that most serious consequences are not a direct result of falling, but from the lack of fast assistance and treatment. If a fall is detected a distress signal, in the form of an SMS message, is sent to a predefined emergency contact. The contents of the SMS messages includes time and date of fall, ambient temperature, fall location coordinates as well as an URL that redirects to the location as seen in Google Maps.

    The fall detection algorithm is threshold based and was created by first analyzing falls in different direction. It can successfully identify 74,4% of all falls, but as good as up to 91% of falls that are either backwards, forwards or to the left given that the bracelet is attached to the left wrist. The algorithm can further filter out 100% of studied activities that are not falls. Such activities include walking, running and sitting down. This gives an overall Accuracy of 93% for the system. The Accuracy takes into account how well a fall is detected and how well other activities are filtered out. Furthermore, the bracelet was worn for 40 hours, spread out over 11 days, in order to capture data during this persons every day life. During this time no false distress signal was sent to the emergency contact.

    Limitations of the system has been found to be the GPS module and the fact that the algorithm is threshold based. The location tracking can be improved by utilizing AGPS, which is the same technique that cellphones use. The threshold based system can't be circumvent in a wearable device solution.

    From this thesis it is indicated that a wearable bracelet can be a reliable fall detection unit. With more extensive falls and field testing even better results can be achieved and it can eventually be pushed as a real product.

  • 189.
    Hasnain, Bakhtiyar Asef
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Algoz, Ali
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    A Control System For A 3-Axis Camera Stabilizer2018Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    The purpose of the project is to implement a control system for a 3- axis camera stabilizer. The stabilization is done by controlling three blushless DC motors driving the yaw, pitch and roll movements of the camera stabilizer's frame, respectively. The stabilizer's frame (equipped with three motors) is used in this project, and it is directly taken from a commercial product, Feiyu Tech G4S. The control system concerned in this project consists of a Teensy 3.6 microcontroller unit (MCU) implemented with three PID controllers, the motor drivers to drive the three motors, and an inertial measurement unit (IMU) of 9 degrees of freedom.The MCU is also used to process the IMU angle measurements of the camera position in 3- axis motion, in particular, it converts the IMU raw data to an angle for each of the axis, it then processes the angle data using a Kalman filter to reduce the noise. In the end of the project a prototype has been built and tested, it uses the control system to run the stabilizing process. It is shown to work quite successfully. In particular, it can run smoothly in the roll and pitch axes and compensate for unwanted movement, however the yaw axis does not function as intended due to a misplacement as well as poor calibration process of the magnetometer sensor in the IMU, which is left for future work.

  • 190. Hasse, L
    et al.
    Kiwilszo, M
    Smulko, J
    Stepinski, Tadeusz
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Quality assessment of varistor ZnO structures by resonant ultrasound spectroscopy2009Inngår i: Insight (Northampton), ISSN 1354-2575, E-ISSN 1754-4904, Vol. 51, nr 5, s. 262-265Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Varistors are produced from ZnO cylindrically-shaped structures whose quality depends on varying technological conditions at stages of their shape forming and firing. Therefore, the varistors art, tested at the final phase of production and faulty elements are excluded. We propose to test the quality of ZnO structures at an earlier stage of production to eliminate defective structures from further and expensive processing. The recommended method applies resonant ultrasound spectroscopy that meets the demand for limiting the costs introduced by an additional measurement procedure. This paper presents the prepared   economical measurement system. that can be used for this purpose The proposed method measures one of the lowest resonant frequencies and dimensions of the tested specimen. The measured quantities enable the estimation of a parameter that is proportional to the sound velocity,  in the tested ZnO sample and gives information about the quality of the   ZnO structure. Detailed experimental data obtained for two batches of  ZnO structures, oil purpose prepared in different ways, are analysed to confirm the usefulness of the applied procedure in industrial applications.

  • 191.
    He, Yuan Yuan
    et al.
    Department of Electrical and Electronic Engineering, The University of Melbourne, Australien.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Power allocation for secondary outage minimization in spectrum sharing networks with limited feedback2013Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 61, nr 7, s. 2648-2663Artikkel i tidsskrift (Fagfellevurdert)
  • 192. He, Yuan Yuan
    et al.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sum Rate Maximization for Cognitive MISO Broadcast Channels: Beamforming Design and Large Systems Analysis2014Inngår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 13, nr 5, s. 2383-2401Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper considers the ergodic weighted sum rate maximization (WSRMax) problem for an underlay cognitive radio multiple input single output (MISO) broadcast channel. In this setting, a secondary network, consisting of a base-station with M transmit antennas and K single-antenna secondary users (SUs), is allowed to share the same spectrum with a primary user (PU), under an average total transmit power (ATTP) constraint and an average interference power (AIP) constraint at the PU receiver. We show that the ATTP constraint always remains active, and as the maximum ATTP P-av -> infinity, the ergodic WSR approaches infinity similar to conventional non-CR networks. We propose a novel low-complexity suboptimal beamforming scheme termed "Partially-Projected & Regularized Zero-Forcing Beamforming" (PP-RZFBF) with a close-form beamformer, by combining the regularized zero-forcing (RZF) with the channel projection idea, to achieve a tradeoff between maximizing secondary throughput and suppressing secondary multiuser interference as well as the interference on PU. In order to analyze and optimize the performance of this scheme, we employ the large system analysis technique, in the limit as M and K approach infinity with a fixed ratio r = K/M. This allows us to derive deterministic limiting approximations for the PP-RZFBF problem which enables us to determine asymptotically optimal beamformers for PP-RZFBF. In the large system limit, for the PP-RZFBF scheme, we also find that as P-av -> infinity, the interference on PU caused by the secondary transmission is asymptotically removed. A special suboptimal beamforming scheme called "CZFBF" is also considered, which involves zero forcing all the interference, including the secondary multiuser interference as well as the interference imposed on PU. Various interesting comparisons between PP-RZFBF and CZFBF are provided. Numerical simulations illustrate that the asymptotically optimal beamformers for the PP-RZFBF scheme provide an excellent performance even for finite-sized systems.

  • 193.
    He, Yuan Yuan
    et al.
    Department of Electrical and Electronic Engineering, The University of Melbourne, Australien.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Throughput maximization in poisson fading channels with limited feedback2013Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 61, nr 10, s. 4343-4356Artikkel i tidsskrift (Fagfellevurdert)
  • 194.
    He, Yuan Yuan
    et al.
    Department of Electrical and Electronic Engineering, University of Melbourne, Australien.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Weighted sum rate maximization for cognitive MISO broadcast channel: Large system analysis2013Konferansepaper (Fagfellevurdert)
  • 195.
    He, Yuan Yuan
    et al.
    Electrical and Computer Engineering, Monash University, Melbourne, Australien.
    Evans, Jamie S
    Electrical and Computer Engineering, Monash University, Melbourne, Australien.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Secrecy rate maximization for cooperative overlay cognitive radio networks with artificial noise2014Konferansepaper (Fagfellevurdert)
  • 196.
    Hedlund, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Design of a UAV-based radio receiver for avalanche beacon detection using software defined radio and signal processing2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    A fully functional proof of concept radio receiver for detecting avalanche beacons atthe frequency 457 kHz was constructed in the work of this master thesis. The radioreceiver is intended to be mounted on an unmanned aerial vehicle (UAV or drone)and used to aid the mountain rescue teams by reducing the rescue time in findingavalanche victims carrying a transmitting beacon. The main parts of this master thesisinvolved hardware requirement analysis, software development, digital signalprocessing and wireless communications.

    The radio receiver was customized to receive low power signal levels becausemagnetic antennas are used and the avalanche beacon will operate in the reactive nearfield of the radio receiver. Noise from external sources has a significant impact on theperformance of the radio receiver.

    This master thesis allows for straightforward further development and refining of theradio receiver due to the flexibility of the used open-source software development kitGNU Radio where the digital signal processing was performed.

  • 197.
    Hellkvist, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Performance Evaluation Of Self-Backhaul For Small-Cell 5G Solutions2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis evaluates the possibility of using millimeter waves of frequency 28GHz for the use of wireless backhaul in small cell solutions in the coming fifth generation mobile networks. This frequency band has not been used in preceding mobile networks but is undergoing a lot of research. In this thesis simulations are performed to evaluate how the high frequency waves behave inside a three dimensional grid of buildings. The simulations use highly directive antenna arrays with antenna gains of 26dBi.

    A main results of the investigation was that a high bandwidth of 800MHz was not enough to provide 12Gbps in non line-of-sight propagation within the simulations. Furthermore, without interference limiting techniques, the interference is probable to dominate the noise, even though the high diffraction losses of millimeter waves propose that interference should be very limited in urban areas.

  • 198.
    Henriksson, Manne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Estimation of heading using magnetometer and GPS.2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    One important part of inertial navigation is the estimation of the direction relative to the Earth’s geographic North Pole, the so called heading. In this project, a gyroscope and an accelerometer were used together in an Extended Kalman Filter with a quaternion as the state space variable, representing the attitude. Given the attitude of the system, measurements from a magnetometer were rotated to a horizontal coordinate frame in order to calculate the direction toward Earth’s magnetic North Pole. Comparing this direction with the angle toward the Geographic North Pole given by a GPS, the local magnetic declination was estimated with the purpose of correcting the heading in the future. Different methods for detecting disturbances on the magnetometer in order to automatically decide when it is to be trusted was discussed and evaluated. Routines for easily performing sensor calibration was created. The outcome of the project was a well working attitude estimation, simply performed calibration routines and a set of methods working together to detect magnetometer disturbances. 

  • 199.
    Herman, Ivo
    et al.
    Czech Tech Univ, Dept Control Engn, Prague, Czech Republic..
    Knorn, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Ahlén, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Disturbance scaling in bidirectional vehicle platoons with different asymmetry in position and velocity coupling2017Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 82, s. 13-20Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper considers a string of vehicles where the local control law uses the states of the vehicle's immediate predecessor and follower. The coupling towards the preceding vehicle can be chosen different to the coupling with the following vehicle, which is referred to as an asymmetric bidirectional string. Further, the asymmetry for the velocity coupling can be chosen differently to the asymmetry in the position coupling. It is investigated how the effect of the disturbance on the control errors in the string depends on the string length. It is shown, that in case of symmetric position coupling and asymmetric velocity coupling, linear scaling can be achieved. For symmetric interactions, the errors scale quadratically in the number of vehicles. When the coupling in position is asymmetric, exponential scaling may occur or the system might even become unstable. The paper thus gives a comprehensive overview of the achievable performance in linear, asymmetric, bidirectional platoons. The results reveal that symmetry in the position coupling and asymmetry in velocity coupling qualitatively improve the performance of the string. Extensive numerical results illustrate the theoretical findings.

  • 200.
    Holmberg, Max
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Development and Evaluation of a Robocentric SLAM Algorithm2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this master thesis the front end of a Simultaneous Localization And Mapping(SLAM) system is developed in the programming language C++ and themeta-operating system ROS (Robot Operating System). The algorithms are based onprevious work done at the Swedish defense research agency (FOI) and are a part of aGPS free positioning system developed for military use. The parts that have beenimplemented during the project includes: feature extraction from LIDAR data, featureassociation and a Robocentric Extended Kalman Filter. The sensors used in the SLAMsystem are a Velodyne LIDAR (LIght Detection And Ranging) unit and an IMU (InertialMeasurement Unit). During the master thesis, data collection has been done indifferent types of outdoor environments. The resulting front end SLAM with a Kalmanfilter is evaluated in the different types of environments and compared with bothaccurate RTK (Real Time Kinetic) GPS and a version of the filter that uses datafiltered with a GPS. The GPS free SLAM algorithm in urban and forest environmentsgives position estimates that drifts less than 2% compared with the SLAM algorithmthat has help from a GPS. In open field terrain the GPS free SLAM algorithm hastrouble estimating its position due to a lack of features, which results in significantdrift over time. When the SLAM algorithm with GPS filtered data is compared with anaccurate Real Time Kinetic GPS in an urban environment the average drift is less than1%.

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