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  • 1.
    Bejhed, Johan
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Eriksson, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Stenmark, L
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    The Development of a Micro Machined Xenon Feed System2004In: AIAA-2004-3976, 40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit: Fort Lauderdale, Florida, USA, 11-14 July 2004, 2004, p. pp 1-8Conference paper (Other scientific)
  • 2.
    Bejhed, Johan
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Wallbank, J
    Lindegren, Robert
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Thorslund, Robert
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Baker, A M
    Stenmark, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Köhler, Johan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Catalyst microsystem design and manufacture for a monopropellant microrocket engine2004In: PowerMEMS 2004, Kyoto, Japan.: 28-30 November, 2004., 2004Conference paper (Other scientific)
  • 3.
    Bengtsson Bernander, Karl
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction.
    A Method for Detecting Resident Space Objects and Orbit Determination Based on Star Trackers and Image Analysis2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Satellites commonly use onboard digital cameras, called star trackers. A star tracker determines the satellite's attitude, i.e. its orientation in space, by comparing star positions with databases of star patterns. In this thesis, I investigate the possibility of extending the functionality of star trackers to also detect the presence of resident space objects (RSO) orbiting the earth. RSO consist of both active satellites and orbital debris, such as inactive satellites, spent rocket stages and particles of different sizes.

    I implement and compare nine detection algorithms based on image analysis. The input is two hundred synthetic images, consisting of a portion of the night sky with added random Gaussian and banding noise. RSO, visible as faint lines in random positions, are added to half of the images. The algorithms are evaluated with respect to sensitivity (the true positive rate) and specificity (the true negative rate). Also, a difficulty metric encompassing execution times and computational complexity is used.

    The Laplacian of Gaussian algorithm outperforms the rest, with a sensitivity of 0.99, a specificity of 1 and a low difficulty. It is further tested to determine how its performance changes when varying parameters such as line length and noise strength. For high sensitivity, there is a lower limit in how faint the line can appear.

    Finally, I show that it is possible to use the extracted information to roughly estimate the orbit of the RSO. This can be accomplished using the Gaussian angles-only method. Three angular measurements of the RSO positions are needed, in addition to the times and the positions of the observer satellite. A computer architecture capable of image processing is needed for an onboard implementation of the method.

  • 4.
    Brown, P.
    et al.
    Imperial Coll London, Blackett Lab, London, England.
    Auster, U.
    TU Braunschweig, Braunschweig, Germany.
    Bergman, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fredriksson, Jesper
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Kasaba, Y.
    Tohoku Univ, Sendai, Miyagi, Japan.
    Mansour, M.
    Ecole Polytech, Lab Phys Plasmas, Palaiseau, France.
    Pollinger, A.
    Austrian Acad Sci, Space Res Inst, Vienna, Austria.
    Baughen, R.
    Imperial Coll London, Blackett Lab, London, England.
    Berglund, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Hercik, D.
    TU Braunschweig, Braunschweig, Germany.
    Misawa, H.
    Tohoku Univ, Sendai, Miyagi, Japan.
    Retino, A.
    Ecole Polytech, Lab Phys Plasmas, Palaiseau, France.
    Bendyk, M.
    Imperial Coll London, Blackett Lab, London, England.
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Vienna, Austria.
    Cecconi, B.
    Observ Paris, LESIA, Meudon, France.
    Dougherty, M. K.
    Imperial Coll London, Blackett Lab, London, England.
    Fischer, G.
    Austrian Acad Sci, Space Res Inst, Vienna, Austria.
    Meeting the Magnetic Emc Challenges for the In-Situ Field Measurements on the Juice Mission2019In: Proceedings of 2019 ESA Workshop on Aerospace EMC (Aerospace EMC), IEEE, 2019Conference paper (Refereed)
    Abstract [en]

    The JUICE (JUpiter ICy moon Explorer) mission features instrument designs tailored to meet the specific challenges of the respective measuring environment, including EMC constraints. We describe the magnetic field science requirements for this mission and show how they drive the EMC requirements on the spacecraft and selected in-situ instrument configurations. We describe the results of two mutual interference campaigns and discuss the design mitigations employed in order to realise in-situ magnetic and electric field data in-flight with the accuracy required to meet very challenging mission science goals.

  • 5.
    Bruhn, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Miniaturized Multifunctional System Architecture for Satellites and Robotics2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes and evaluates the design of nanospacecraft based on advanced multifunctional microsystems building blocks. These systems bring substantial improvements of the performance of nanosatellites and enable new space exploration, e.g. interplanetary science missions using minute space probes. Microsystems, or microelectromechanical systems, allows for extreme miniaturization using heritage from IC industry. Reducing mass and volume of spacecraft gives large savings in terms of launch costs.

    Definition and categorization of system and module level features in multifunctional microsystems are used to derive a spacecraft optimization algorithm which is compatible with commonly used concurrent engineering methods.

    The miniaturization of modules enables modular spacecraft architectures comprising powerful multifunctional microsystems, which are applicable to satellites between 10 and 1000’s of kg.

    This kind of complete spacecraft architecture has been developed for the NanoSpace-1 technology demonstrator satellite. The spacecraft bus uses multifunctional design to enable distributed intelligence and autonomy, graceful degradation, functional surfaces, and distributed power systems. The increase in performance of the new spacecraft architecture as compared with conventional nanosatellites is orders of magnitudes in terms of power storage, scientific payload mass ratio, pointing stabilization, and long time space operation.

    This high-performance system-of-microsystems architecture has been successfully employed on two space robotic concepts: a miniaturized submersible vehicle for Jupiter’s Moon Europa and a miniaturized spherical robot. The submersible is enabled by miniaturization of electronics into 3-dimensional, vertically integrated multi-chip-modules together with new interconnection methods. These technologies enabled the submersible vehicle tube-shaped design within 20 cm length and 5 cm diameter. The spherical rover was developed for long range and networked science investigations of interplanetary bodies. The rover weighs 3.5 kg and is shown to endure direct reentry on Mars, which increases the ratio between the landed mobile payload mass and the initial mass in Mars orbit by a factor of 18.

    List of papers
    1. Nanospace-1: The Impacts of the First Swedish Nanosatellite on Spacecraft Architecture and Design
    Open this publication in new window or tab >>Nanospace-1: The Impacts of the First Swedish Nanosatellite on Spacecraft Architecture and Design
    2003 In: Acta Astronautica, Vol. 53, p. 633-643Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-93730 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
    2. Nanospace-1: Spacecraft Design using Advanced Modular Architecture (AMA)
    Open this publication in new window or tab >>Nanospace-1: Spacecraft Design using Advanced Modular Architecture (AMA)
    In: AIAA Journal of Spacecraft and RocketsArticle in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-93731 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
    3. Spacecraft Design Optimization - A multifunctional Microsystem Module Implementation Method
    Open this publication in new window or tab >>Spacecraft Design Optimization - A multifunctional Microsystem Module Implementation Method
    Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-93732 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
    4. Distributed Communication Architecture in Spacecraft System-of-Microsystems - A preliminary Analysis
    Open this publication in new window or tab >>Distributed Communication Architecture in Spacecraft System-of-Microsystems - A preliminary Analysis
    Show others...
    Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-93733 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
    5. MEMS Enablement and Analysis of the Miniature Autonomous Submersible Explorer
    Open this publication in new window or tab >>MEMS Enablement and Analysis of the Miniature Autonomous Submersible Explorer
    Show others...
    2005 In: IEEE Journal of Oceanic Engineering, Vol. 30, no 1, p. 165-178Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-93734 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
    6. A Preliminary Design for a Spherical Inflatable Microrover for Planetary Exploration
    Open this publication in new window or tab >>A Preliminary Design for a Spherical Inflatable Microrover for Planetary Exploration
    Show others...
    2008 (English)In: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030, Vol. 63, no 5-6, p. 618-631Article in journal (Refereed) Published
    Abstract [en]

    The Spherical Mobile Investigator for Planetary Surface (SMIPS) concept aims at making use of the latest developments within extreme miniaturization of space systems. The introduction of Microelectromechanical Systems (MEMSs) and higher level Multifunctional Microsystems (MMSs) design solutions gives the robot high performance per weight unit. The untraditional spherical shape makes it easily maneuverable and thus provides a platform for scientific investigations of interplanetary bodies. Preliminary investigations of the SMIPS concept show several advantages over conventional robots and rovers in maneuverability, coverage, size, and mass. A locomotion proof-of-concept has been Studied together with a new distributed on-board data system configuration. This paper discusses theoretical robot analysis, an overall concept, possible science, enabling technologies, and how to perform scientific investigations. A preliminary design of an inflatable multifunctional shell is proposed.

    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:uu:diva-93967 (URN)10.1016/j.actaastro.2008.01.044 (DOI)000258632900009 ()
    Available from: 2006-01-19 Created: 2006-01-19 Last updated: 2017-12-14Bibliographically approved
    7. Extremely Low Mass Spherical Rovers for Extreme Environments and Planetary Exploration with MEMS
    Open this publication in new window or tab >>Extremely Low Mass Spherical Rovers for Extreme Environments and Planetary Exploration with MEMS
    2005 In: Proc. of Int. Symp. on Artificial Intelligence, Robotics and Automation in SpaceArticle in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-93736 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
  • 6.
    Bruhn, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    Kratz, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    Warell, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Lagerkvist, Claes-Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Kaznov, Viktor
    Jones, Jack A
    Stenmark, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    A Preliminary Design for a Spherical Inflatable Microrover for Planetary Exploration2008In: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030, Vol. 63, no 5-6, p. 618-631Article in journal (Refereed)
    Abstract [en]

    The Spherical Mobile Investigator for Planetary Surface (SMIPS) concept aims at making use of the latest developments within extreme miniaturization of space systems. The introduction of Microelectromechanical Systems (MEMSs) and higher level Multifunctional Microsystems (MMSs) design solutions gives the robot high performance per weight unit. The untraditional spherical shape makes it easily maneuverable and thus provides a platform for scientific investigations of interplanetary bodies. Preliminary investigations of the SMIPS concept show several advantages over conventional robots and rovers in maneuverability, coverage, size, and mass. A locomotion proof-of-concept has been Studied together with a new distributed on-board data system configuration. This paper discusses theoretical robot analysis, an overall concept, possible science, enabling technologies, and how to perform scientific investigations. A preliminary design of an inflatable multifunctional shell is proposed.

  • 7.
    Bull, Jonathan
    et al.
    Stanford University.
    Jameson, Antony
    High-Order Flux Reconstruction Schemes for LES on Tetrahedral Meshes2014In: Progress in Hybrid RANS-LES Modelling: Volume 130 of the series Notes on Numerical Fluid Mechanics and Multidisciplinary Design / [ed] Sharath Girimaji, Werner Haase, Shia-Hui Peng, Dieter Schwamborn, 2014Conference paper (Refereed)
    Abstract [en]

    The use of the high-order Flux Reconstruction (FR) spatial discretization scheme for LES on unstructured meshes is investigated. Simulations of the compressible Taylor-Green vortex at Re=1,600 demonstrate that the FR scheme has low numerical dissipation and accurately reproduces the turbulent energy cascade at low resolution, making it ideal for high-order LES. To permit the use of subgrid-scale models incorporating explicit filtering on tetrahedral meshes, a high-order filter acting on the modal form of the solution (i.e. the Dubiner basis functions) is developed. The WALE-Similarity mixed (WSM) model using this filter is employed for LES of the flow over a square cylinder at Re=21,400, obtaining reasonable agreement with experiments. Future research will be directed at improved SGS models and filters and at developing high-order hybrid RANS/LES methods.

  • 8.
    Bull, Jonathan
    et al.
    Department of Aeronautics and Astronautics, Stanford University.
    Jameson, Antony
    Lopez-Morales, Manuel
    Crabill, Jacob
    Economon, Thomas
    Manosalvas, David
    Romero, Joshua
    Sheshadri, Abhishek
    Watkins, Jerry
    Williams, David
    Palacios, Francisco
    Verification and Validation of HiFiLES: a High-­Order LES Unstructured Solver on Multi­GPU Platform2014Conference paper (Refereed)
    Abstract [en]

    The goal of this paper is to present a verification and validation study of HiFiLES: a high-order LES solver developed in the Aerospace Computing Laboratory (ACL) at Stanford University. HiFiLES has been built on top of SD++ (Castonguay et al.) and achieves high-order spatial discretizations with the Energy-Stable Flux Reconstruction (ESFR) scheme on unstructured grids in two and three dimensions. The high parallelizability of this scheme motivates the solver’s ability to run in a multi-GPU (Graphical Processing Unit) environment. We intend for this paper to be the main reference for HiFiLES and serve (with the previous SD++ papers) as a reference for researchers that would like to develop or implement high-order numerical schemes based on an Energy-Stable Flux Reconstruction (ESFR) approach.

  • 9.
    Bull, Jonathan R.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis. Stanford University, Department of Aeronautics and Astronautics.
    Jameson, Antony
    Simulation of the Taylor–Green vortex using high­-order flux reconstruction schemes2015In: AIAA Journal, ISSN 0001-1452, E-ISSN 1533-385X, Vol. 53, no 9, p. 2750-2761Article in journal (Refereed)
  • 10. Burke, J D
    et al.
    Alkalai, L
    Bruhn, Fredrik
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Micro/Nano spacecraft as program driver2004In: ISU 9th International Symposium: 29-30 December, 2004, Strasbourg, France, 2004Conference paper (Other (popular scientific, debate etc.))
  • 11.
    Deiana, Federico
    et al.
    Univ Cagliari, Dept Elect & Elect Engn, I-09123 Cagliari, Italy..
    Serpi, Alessandro
    Univ Cagliari, Dept Elect & Elect Engn, I-09123 Cagliari, Italy..
    Abrahamsson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Marongiu, Ignazio
    Univ Cagliari, Dept Elect & Elect Engn, I-09123 Cagliari, Italy..
    Gatto, Gianluca
    Univ Cagliari, Dept Elect & Elect Engn, I-09123 Cagliari, Italy..
    Extensive Losses Estimation of a Novel High-Speed Permanent Magnet Synchronous Machine for Flywheel Energy Storage Systems2016In: 2016 XXII International Conference On Electrical Machines (ICEM), 2016, p. 1728-1734Conference paper (Refereed)
    Abstract [en]

    In this paper, the design criteria and an extensive losses analysis of a novel High-Speed Permanent Magnet Synchronous Machine (HS-PMSM) is presented. The proposed machine topology has been designed for a Flywheel Energy Storage System (FESS) with the aim of optimizing the integration between the flywheel and the HS-PMSM rotor, minimizing the overall losses at the same time. Thus, the conceptual design and sizing criteria of the FESS are introduced at first. Furthermore, a double HS-PMSM is designed, whose main specifications are presented and discussed. Subsequently, HS-PMSM standby and load losses arc determined by an extensive Finite Element Analysis (FEA) through the JMAG software package. Numerical simulations allow the identification of HS-PMSM losses over different operating conditions, confirming the effectiveness of the proposed design approach.

  • 12.
    Enculescu, I
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. Materialvetenskap.
    Siwy, Z
    Dobrev, D
    Trautmann, C
    Toimil, Molares M E
    Neumann, R
    Hjort, Klas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science.
    Westerberg, L
    Spohr, R
    Copper nanowires electrodeposited in etched single-ion track templates2003In: Appl. Phys. A, Vol. 77, p. 751-755Article in journal (Refereed)
  • 13.
    Espadas Escalante, Juan José
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics. Uppsala University.
    On numerical analyses of woven composite laminates: Homogenization, damage and fracture2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation analyzes various mechanical properties of textile reinforced composite laminates.

    The dissertation is based on a total of six published works, which are essentially numerical, although experimental elements are available. The numerical methods used are based on high-resolution finite element models in combination with sophisticated phase-field theories for brittle fracture. A key result is that important mechanical properties in engineering applications, such as fracture or damage resistance, can be substantially affected by the arrangement of the constituent materials at the meso level.

    List of papers
    1. A phase-field model for strength and fracture analyses of fiber-reinforced composites
    Open this publication in new window or tab >>A phase-field model for strength and fracture analyses of fiber-reinforced composites
    2019 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 174, p. 58-67Article in journal (Refereed) Published
    Abstract [en]

    A phase-field model for brittle fracture is proposed and evaluated for strength and fracture analyses of composites. In addition to the elastic properties, this approach makes use of only the fracture toughness and the strength of the material. The capability of the method is shown in analyses of composites at two scales. In laminates, strengths of notched laminates are estimated, including hole size effects. In a lamina, cracks developed in both transverse tension and compression are analyzed and compared to other numerical methods in the literature. The effects of a spectral and a hydrostatic-deviatoric decomposition of the strain energy density, two variants often used in phase-field formulations, are studied. It is shown that the choice of the decomposition affects the fracture development. Results are compared to experiments and simulations in the literature showing the capabilities of the phase-field approach.

    Place, publisher, year, edition, pages
    Elsevier, 2019
    Keywords
    Computational mechanics, Strength, Fracture, Finite element analysis (FEA)
    National Category
    Composite Science and Engineering
    Identifiers
    urn:nbn:se:uu:diva-368254 (URN)10.1016/j.compscitech.2018.10.031 (DOI)000469407500008 ()
    Available from: 2018-12-03 Created: 2018-12-03 Last updated: 2019-07-05Bibliographically approved
    2. A study on the influence of boundary conditions in computational homogenization of periodic structures with application to woven composites
    Open this publication in new window or tab >>A study on the influence of boundary conditions in computational homogenization of periodic structures with application to woven composites
    2017 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 160, p. 529-537Article in journal (Refereed) Published
    Abstract [en]

    The influence of boundary conditions (BCs) in the estimation of elastic properties of periodic structures is investigated using computational homogenization with special focus on planar structures. Uniform displacement, uniform traction, periodic, in-plane periodic and a proposed mix of periodic and traction BCs are used. First, the effect of the BCs is demonstrated in structures with one-, two- and three-dimensional periodicity. Mixed BCs are shown to most accurately represent the behavior of layered structures with a small number of repeating unit cells. Then, BCs are imposed on a twill woven composite architecture. Special attention is devoted to investigate the sensitivity of the estimated properties with respect to the BCs and to show differences when considering a single lamina or a laminate. High sensitivity of the in-plane extensional modulus and Poisson's ratio with respect to the type of BCs is found. Moreover, it is shown that the mix of BCs and in-plane periodic BCs are capable to represent an experimental strain field.

    Keywords
    Computational homogenization, Mixed boundary conditions, Heterogeneous structures, Elastic properties, Woven composites, Finite element method
    National Category
    Composite Science and Engineering
    Identifiers
    urn:nbn:se:uu:diva-359307 (URN)10.1016/j.compstruct.2016.10.082 (DOI)000390470300044 ()
    Available from: 2018-08-31 Created: 2018-08-31 Last updated: 2019-07-05Bibliographically approved
    3. The effect of free-edges and layer shifting on intralaminar and interlaminar stresses in woven composites
    Open this publication in new window or tab >>The effect of free-edges and layer shifting on intralaminar and interlaminar stresses in woven composites
    2018 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 185, p. 212-220Article in journal (Refereed) Published
    Abstract [en]

    The free-edge effects and relative layer shifting in the interlaminar and intralaminar stresses of plain woven composite laminates under uniaxial extension is investigated numerically using a finite element approach. A computational framework of the free-edge problem for periodic structures with finite width is applied to woven laminates. First, two-layered laminates with three different shifting configurations are studied considering repeating unit cells simulating finite and infinite width. For each configuration, two different widths are considered by trimming the model at different locations in order to investigate different free-edge effects. Then, two four-layered laminates with no shifting and a maximum shifting configuration are analyzed to illustrate the effect of neighboring layers in the stresses. For each shifting configuration, different delamination mechanisms are expected. When considering more layers, it is found that the stacking configuration affects the state of stress and the free-edge effects depending on the shifting. In general, a different behavior than that of unidirectional tape laminates is found, since the interlaminar and intralaminar stresses can be higher than those generated at the free-edges. Particularly, for the maximum shifting configuration results are in agreement with experimental results in the literature where no debonding between yarns was observed at the free-edges.

    Keywords
    Woven composites, Finite element method, Intralaminar stresses, Interlaminar stresses, Free-edge effects, Multiscale modeling
    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-341485 (URN)10.1016/j.compstruct.2017.11.014 (DOI)000418961000018 ()
    Available from: 2018-02-28 Created: 2018-02-28 Last updated: 2019-07-05Bibliographically approved
    4. A study of induced delamination and failure in woven composite laminates subject to short-beam shear testing
    Open this publication in new window or tab >>A study of induced delamination and failure in woven composite laminates subject to short-beam shear testing
    2019 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 205, p. 359-369Article in journal (Refereed) Published
    Abstract [en]

    Failure in woven composite laminates subject to global shear load is studied. Laminates are manufactured, tested and analyzed using X-ray computed tomography, scanning electron microscopy and finite element models. It is found that the stress distribution along the thickness direction is dependent on the layer shifting that alters different yarn interactions, which in turn, affects delamination and failure onset A suggested failure mechanism is in agreement with experimental observations.

    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-368250 (URN)10.1016/j.engfracmech.2018.10.015 (DOI)000453766000026 ()
    Available from: 2018-12-03 Created: 2018-12-03 Last updated: 2019-07-05Bibliographically approved
    5. Analysis of the Influence of Layer Shifting on the Elastic Response and Damage Nucleation and Growth in Woven Composite Laminates
    Open this publication in new window or tab >>Analysis of the Influence of Layer Shifting on the Elastic Response and Damage Nucleation and Growth in Woven Composite Laminates
    2018 (English)In: NASA Technical MemorandumsArticle in journal (Refereed) Published
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-368253 (URN)
    Available from: 2018-12-03 Created: 2018-12-03 Last updated: 2019-07-05
    6. Mesoscale analysis of the transverse cracking kinetics in woven composite laminates using a phase-field fracture theory
    Open this publication in new window or tab >>Mesoscale analysis of the transverse cracking kinetics in woven composite laminates using a phase-field fracture theory
    2019 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 216, article id 106523Article in journal (Refereed) Published
    Abstract [en]

    A phase-field approach to fracture is used to simulate transverse cracking kinetics in composite laminates. First, a typical unidirectional tape laminate is modeled and the transverse cracking evolution with the consequent reduction in the in-plane modulus of elasticity is estimated. Then, a four-layered plain weave composite is modeled using different layer shifting configurations. Predictions in the transverse cracking evolution become improved as the shifting configuration of the laminate model become closer to experimental observations. Simulations predict that some cracks do not form perpendicularly to the loading direction, as it has been observed experimentally in similar locations. Only the fracture toughness and the in situ transverse strength of the ply are required without prior knowledge of the position of the cracks or an ad hoc criterion for crack evolution. All the simulations are compared qualitatively and quantitatively to experiments published elsewhere.

    Keywords
    Composites, Fibre reinforced materials, Fracture mechanics, Damage mechanics, Crack growth
    National Category
    Applied Mechanics
    Research subject
    Engineering science with specialization in Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-388533 (URN)10.1016/j.engfracmech.2019.106523 (DOI)000477573000028 ()
    Available from: 2019-07-01 Created: 2019-07-01 Last updated: 2019-09-20Bibliographically approved
  • 14. Gurgurewicz, Joanna
    et al.
    Mège, Daniel
    Grygorczuk, Jerzy
    Wiśniewski, Łukasz
    Berglund, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Carrère, Véronique
    Gritsevich, Maria
    Kalarus, Maciej
    Peltoniemi, Jouni
    Persson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Rataj, Mirosław
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wawer, Piotr
    Zubko, Nataliya
    Studying the composition of Phobos' surface using HOPTER (Highland Terrain Hopper)2016Conference paper (Refereed)
  • 15.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Microsystems for the good life2018In: Int. Summit Forum on Micro and Nano Manipul. and Manufact.: MNMM 2018, 2018, p. 5-5Conference paper (Other academic)
    Abstract [en]

    The Microsystems Technology Division of Uppsala University is committed to make microsystems for the good life. I will present our research on novel materials and technologies for miniaturized systems that are for the good of society and can provide fundamental answers in science.

  • 16.
    Köhler, Johan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Bringing Silicon Microsystems to Space: Manufacture, Performance, and Reliability2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The incorporation of extremely compact multifunctional microsystems is a highly profitable long-term approach in spacecraft design. These systems bring substantial launch-cost reductions, and enable exciting space exploration and science missions.

    Silicon microsystems technology is an adequate choice for the multifunctional microsystem development. However, the development of basic microsystems technology cannot be financed within application-specific space missions. Rather, the microsystems technology should be matured through fundamental research.

    Silicon microsystems technology was used to develop a cold gas microthruster system suitable for minute movements of spacecraft (low Δv). In a hybrid integration, the system unit contains three silicon microsystem parts with four individual thrusters in total, together with external control electronics. The total mass is 0.35 kg.

    Further integration will result in a mass of 0.08 kg. Complete system integration means that all package and interconnection levels are integrated into the silicon microsystem units. Several vital issues must be addressed, e.g. the reliable bonding of silicon wafers, the microfabrication process compatibility, and the manufacture process sequence. A graphical tool is introduced for process sequence evaluation.

    Wafer bonding is used as fabrication process, assembly tool, and packaging technique. The quality and reliability of the bonded interfaces must be assessed in order to secure the operation of the microsystems in space. Therefore, statistical methods for burst test evaluation have been developed.

    Weibull fracture probability functions have been derived in order to interpret the bond quality. In addition, rank-sum tests on spot series and analysis of variance are performed for bond quality diagnostics. The dependence on annealing temperature and surface-activation are presented, together with diagnosed degradation of insufficiently annealed bonds due to different spaceflight environments (thermal cycling, vibration, γ-irradiation).

  • 17.
    Köhler, Johan
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Moerel, J L
    Halswijk, W
    Baker, A M
    Hebden, R
    Stenmark, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Detailed design of a monopropellant microrocket engine using MEMS Technology2004In: PowerMEMS 2004, Kyoto, Japan.: 28-30 November, 2004., 2004Conference paper (Other scientific)
  • 18. Mege, Daniel
    et al.
    Grygorczuk, Jerzy
    Gurgurewicz, Joanna
    Wisniewski, Lukasz
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    The Planetary Highland Terrain Hopper (HOPTER): the right way to jump into conclusions2015Conference paper (Refereed)
    Abstract [en]

    Comprehensive understanding of the principles governing the geological activity of the Earth was obtained in continental and oceanic mountains. It is not expected that the principles governing the overall geologic activity and evolution of other planetary bodies such as Mars will be understood if exploration is limited to nearly flat terrains, either imposed by the used exploration platform capabilities, the risk of getting stuck, or by the time required to cross the border of a landing ellipse. Surface exploration of mountains is additionally to be coupled to two-or three-dimensional geophysical surveys to correlate the surface observations with deeper processes. On the small bodies where ultra-low gravity prevails, the weight of wheel-driven platforms is not sufficient to generate the friction at the contact with the ground that is required to trigger motion of the rover relative to the ground. Under such circumstances, hopping is one of the mobility solutions. We present a new locomotion system, the hopter platform, which is adapted to these challenges on Solar System bodies having a gravity field lower than on Earth. The hopter is a robust, versatile and highly manoeuvrable platform based on simple mechanical concepts that accurately jumps to distances of meters to tens of meters and more, depending on the gravity field of the studied body. Its low mass of 10kg (including up to 5 kg of miniaturized payload), makes it possible to simultaneously launch several hopters to work as a fractionated explorer at a very competitive cost. After reviewing the payload that may be placed onboard hopters, we illustrate the scientific capabilities of hopters and hopter networks in performing basic geologic observations at distinct study sites in a variety of geological environments, obtaining data along steep geological cross sections, surveying geophysical anomalies in the subsurface, prospecting resources, monitoring micro-environments, meteorological events, and geodetic deformation, or characterizing dust activity on Mars, the Moon, and Phobos.

  • 19. Mege, Daniel
    et al.
    Gurgurewicz, Joanna
    Grygorczuk, Jerzy
    Wisniewski, Lukasz
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    The Highland Terrain Hopper (HOPTER): Concept and usecases of a new locomotion system for the exploration of lowgravity Solar System bodies2016In: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030, Vol. 121, p. 200-220Article in journal (Refereed)
    Abstract [en]

    Comprehensive understanding of the principles governing the geological activity of theEarth was obtained in continental and oceanic mountains. It is not expected that theprinciples governing the overall geologic activity and evolution of other planetary bodiessuch as Mars will be understood if exploration is limited to nearlyflat terrains, eitherimposed by the used exploration platform capabilities, the risk of getting stuck, or by thetime required to cross the border of a landing ellipse. Surface exploration of mountains isadditionally to be coupled to two- or three-dimensional geophysical surveys to correlatethe surface observations with deeper processes. On the small bodies where ultra-lowgravity prevails, the weight of wheel-driven platforms is not sufficient to generate thefriction at the contact with the ground that is required to trigger motion of the roverrelative to the ground. Under such circumstances, hopping is one of the mobility solutions.We present a new locomotion system, the hopter platform, which is adapted to thesechallenges on Solar System bodies having a gravityfield lower than on Earth. The hopter isa robust, versatile and highly manoeuvrable platform based on simple mechanical con-cepts that accurately jumps to distances of metres to tens of metres and more, dependingon the gravityfield of the studied body. Its low mass of 10 kg (including up to 3 kg ofminiaturised payload), makes it possible to simultaneously launch several hopters to workas a fractionated explorer at a very competitive cost. After reviewing the payload that maybe placed onboard hopters, we illustrate the scientific capabilities of hopters and hopternetworks in performing basic geologic observations at distinct study sites in a variety ofgeological environments, obtaining data along steep geological cross sections, surveyinggeophysical anomalies in the subsurface, prospecting resources, monitoring micro-environments, meteorological events, and geodetic deformation, or characterizing dustactivity on Mars, the Moon, and Phobos.

  • 20. Mege, Daniel
    et al.
    Gurgurewicz, Joanna
    Grygorczuk, Jerzy
    Wiśniewski, Lukasz
    Beucler, Eric
    Carrère, Véronique
    Dyment, Jérome
    Gritsevich, Maria
    Langlais, Benoit
    Peltoniemi, Jouni
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zubko, Nataliya
    Principles and examples of scientific applications of the HOPTER jumping robot on Phobos2016Conference paper (Refereed)
  • 21.
    Nguyen, Hugo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    Jonsson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    Edqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    Sundqvist, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    Kratz, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    A heavily miniaturized submersible: a terrestrial kickoff2008In: Proceedings of ASTRA 2008, 2008, p. 1-9Conference paper (Refereed)
    Abstract [en]

    The vision of exploring extraterrestrial water findings employing a remotely operated submersible, as proposed by JPL/NASA for the investigation of the possible ocean underneath the frozen crust of Jupiter’s moon Europa, is now taking a step further into fulfilment. The Ångström Space Technology Centre has developed a sophisticated vehicle concept based on microtechnology for most of the navigational systems and payload systems. This enables a high function density, and a compact vehicle with a diameter of 50 mm and length of 200 mm, i.e. an overall size allowing the vehicle to be deployed through a borehole like that typical for arctic drilling.

    Here, the system architecture of the vehicle complying with the requirements on manoeuvrability, operational functions, and mission objectives is presented. In short, the vehicle in the first version will operate in deep and narrow waters, and will be equipped with a camera, sonar imaging system, an electronic tongue for chemical sampling, and a Conductivity-Temperature-Depth (CTD) sensor. Although the vehicle will be given certain autonomy in later versions, the first edition will rely on remote manual guidance. Commands for this, as well as power download, and data upload will be communicated through an optic fibre.

    The objective of this contribution is to present, for the first time, the status of the project including, briefly, the first results from miniaturized sonar, the vehicle bus design, and the design, realization and testing of the propulsion and attitude control systems differing in manoeuvrability, weight/volume, redundancy and efficiency.

  • 22.
    Persson, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Berglund, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Khaji, Zahra
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Sturesson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Söderberg, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Optogalvanic spectroscopy with microplasma sources – Current status and development towards Lab-On-A-Chip2015Conference paper (Refereed)
    Abstract [en]

    Miniaturized optogalvanic spectros-copy shows excellent prospects of becoming a highly sensitive method for gas analysis in micro total analysis systems. Here, a status report on the current development of microplasma sources for optogalvan-ic spectroscopy is presented, together with the first comparison of the sensitivity of the method to con-ventional single-pass absorption spectroscopy. The stability and reproducibility of the microplasma source when used as a detector for optogalvanic spectroscopy is also investigated, and a roadmap of future developments is presented, with the particular focus of integrating sensors for measuring the pres-sure, temperature and flow of the sample gas through the detector, and combining the detector with a miniaturized combustor to allow for studies of solid samples.

  • 23.
    Persson, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Nguyen, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Riddar, Frida
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Micro- and nanostructured magnetic field sensor for space applications2009In: 15th International Conference on Solid-State SensorsTransducers 2009: Actuators and Microsystems, 2009, p. 1190-1193Conference paper (Refereed)
    Abstract [en]

    Magnetometers are popular payloads on scientific space missions. Here, the design and fabrication process of a miniaturized magnetometer based on tunneling magnetoresistance is presented. The process is capable of making magnetic tunnel junctions in a wide size range, by employing both UV lithography and focused ion beam milling and deposition. Ga implantation in the ferromagnetic electrodes of the junction is studied in more detail. It was shown that Ga implantation may harm the magnetometer if the irradiation dose exceeds 1014 Ga+ cm-2.

  • 24.
    Persson, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Passenger Flight Experience of Urban Air Mobility2019Student paper other, 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The first part of a study of passenger flight experience of Urban Air Mobility was completed. This first part included the design of different Urban Air Mobility vehicle models, in which the passenger flight experience would be quantitatively measured. A first version of a simulator setup, in which the measurements were performed, was also developed. Three concept vehicle models, a single main rotor, a side-by-side rotor and a quadrotor, were designed in the conceptual design software NDARC. The vehicles were electrically propelled with battery technology based on future technology predictions and were designed for autonomous flight with one passenger. The emissions of the vehicles were analyzed and compared with an existing turboshaft helicopter. The interface between NDARC and the flight dynamics analysis and control system software FlightCODE, which was used to create control systems to the NDARC models,  was developed to fit the vehicle configurations considered. The simulator setup was created with a VR headset, the flight simulation software X-Plane, an external autopilot software and stress sensors. Trial runs with the simulator setup were performed and gave important data for the continued development. Planned upgrades of the simulation station were presented and the continuation of the study was discussed.

  • 25.
    Sarmast, Sasan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Shen, W. Z.
    Tech Univ Denmark, Wind Energy Dept, DK-2800 Lyngby, Denmark.
    Zhu, W. J.
    Tech Univ Denmark, Wind Energy Dept, DK-2800 Lyngby, Denmark.
    Mikkelsen, R. F.
    Tech Univ Denmark, Wind Energy Dept, DK-2800 Lyngby, Denmark.
    Breton, Simon-Philippe
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Ivanell, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. KTH Mech, S-10044 Stockholm, Sweden.
    Validation of the actuator line and disc techniques using the New MEXICO measurements2016In: SCIENCE OF MAKING TORQUE FROM WIND (TORQUE 2016), 2016, article id 032026Conference paper (Refereed)
    Abstract [en]

    Actuator line and disc techniques are employed to analyse the wake obtained in the New MEXICO wind turbine experiment. The New MEXICO measurement campaign done in 2014 is a follow-up to the MEXICO campaign, which was completed in 2006. Three flow configurations in axial flow condition are simulated and both computed loads and velocity fields around the rotor are compared with detailed PIV measurements. The comparisons show that the computed loadings are generally in agreement with the measurements under the rotor's design condition. Both actuator approaches under-predicted the loading in the inboard part of blade in stall condition as only 2D airfoil data were used in the simulations. The predicted wake velocities generally agree well with the PIV measurements. In the experiment, PIV measurements are also provided close to the hub and nacelle. To study the effect of hub and nacelle, numerical simulations are performed both in the presence and absence of the hub geometry. This study shows that the large hub used in the experiment has only small effects on overall wake behaviour.

  • 26.
    Seton, Ragnar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Sturesson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Dept. of Military Sciences, Swedish Defence University, Stockholm, Sweden.
    Persson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Investigating the plasma properties of a Xe-microplasma thruster2018In: 29th Micromechanics and Microsystems Europe workshop, Bratislava, Slovakia, August 26-29, 2018, Bratislava, Slovenia, 2018Conference paper (Other academic)
    Abstract [en]

    By combining optical emission spectroscopy (OES) and Langumuir probes, the plasma properties of a Xenon-microplasma thruster have been investigated. Using IV-curve analysis the properties of the plasma have been determined and correlated to the power fed into it. Satisfactory agreement has been obtained with the results of OES measurements (line-ratio technique) and shock-cell distance calculations. While the fuel consumption of the thruster decreased very linearly with the power fed to the plasma, the plasma properties was found to have behave in a more complex way. In the studied power range, the density ratio between at least two ions, with upper configurations 5p5(2P◦3/2)7p and 5p5(2P◦3/2)6p, strongly indicated that the ionization processes of the former was favorable in terms of thrust for the geometry of the nozzle. This was supported electron temperature measurements from IV-curves. 

  • 27.
    Skarpsvärd, Joakim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Industrial Engineering & Management.
    Helleblad Nymo, Carl-Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Industrial Engineering & Management.
    Modulär Mekanikstruktur för Nanosatelliter2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The objective of this thesis was to present a design proposal on a modular mechanicalstructure for a nanosatellite. The size of the structure should follow the CubeSatstandards. This standard divides satellites in units (U), where 1U is equivalent to acube where sides measure 100 mm. 2U corresponds to the same volume and size as2 assembled 1U structures, and so on. The focus was to develop a structure in theorder of 3U and 6U.

    At the integration in the satellite launch rocket, there are a couple of differentinterfaces, where the structure is adapted to common ones; P-POD and CSD. Toadapt the structure between both of them was part of the challenge.

    Most of the work consisted of concept generation and computer aided design. Aliterature study with focus on earlier work, modularity, materials and robustconstruction was also carried out. The finished structure was tested with digital toolsagainst some of the strains that satellites are exposed to, with good results. Thestructure´s modularity consists of relatively free mounting of the payload, and that thetransition between the different interfaces and sizes takes place in a smooth manner.

    According to the requirement specification all applicable objectives where achieved,except the weight criteria on the 3U-structure for CSD that exceeded it by 45 grams.A brief competitive analysis was carried out which showed positive results. A coupleof the recommendations for further work was to perform a proper cost analysis andthe manufacturing of a prototype for further assessments.

  • 28.
    Stenmark, Lars
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    Köhler, Johan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science. ÅSTC.
    NanoSpace-1, The MNT-Based Nanosatellite, Small Satellites and Space Systems2004In: La Rochelle, France, 2004, p. pp 1-8Conference paper (Other scientific)
  • 29.
    Sturesson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC). Försvarshögskolan/Swedish National Defence College.
    Sense, Actuate and Survive: Ceramic Microsystems for High-Temperature Aerospace Applications2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In aerospace applications, but also in manufacturing, mining, energy industry and natural hazards, high temperature, corrosion, erosion and radiation, challenge the performance and being of hardware.

    In this work, high-temperature co-fired ceramic (HTCC) alumina and platinum have been used for a range of devices intended for aerospace applications at up to 1000°C.

    The thermomechanics of a pressure sensor was investigated, and the interfacing was attained by wireless powering and reading. However, read range was limited and sensitivity decreased with temperature. Silver, electroplated after sintering, was found to remedy this until it eventually alloyed with platinum.

    Copper was electroplated and oxidized for oxygen storage in a microcombustor, intended for sample preparation for optogalvanic spectroscopy (OGS) to indicate extraterrestrial life. Despite delamination, caused by residual stresses, the device operated successfully.

    Conversely, pre-firing metallization by integration of platinum wires was studied. Freely suspended, and despite heat-induced shape irregularities, these were found advantageous over screen printed elements for gas heating, and temperature and pressure sensing. By fusing off the wires, spherical tips, allowing for impedance monitoring of microplasma sources in, e.g., OGS, were formed.

    Microplasma sources can also be used for gas heating. This, together with screen printed and suspended resistive heaters, was evaluated in a microthruster, showing that plasma heating is the most effective, implying fuel consumption reduction in satellite propulsion.

    In conclusion, HTCC alumina microdevices are thermally stable and could benefit several aerospace applications, especially with the complementary metallization schemes devised here.

    Future developments are expected to include both processing and design, all with the intention of sensing, actuating and surviving in high-temperature environments.

    List of papers
    1. Thermomechanical properties and performance of ceramic resonators for wireless pressure reading in high temperatures
    Open this publication in new window or tab >>Thermomechanical properties and performance of ceramic resonators for wireless pressure reading in high temperatures
    Show others...
    2015 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, no 9, article id 095016Article in journal (Refereed) Published
    Abstract [en]

    This paper reports on the design, fabrication and thermomechanical study of ceramic LC resonators for wireless pressure reading, verified at room temperature, at 500 °C and at 1000 °C for pressures up to 2.5 bar. Five different devices were fabricated of high-temperature co-fired ceramics (HTCC) and characterized. Alumina green tape sheets were screen printed with platinum paste, micromachined, laminated and fired. The resulting samples were 21 x 19 mm2 with different thicknesses. An embedded communicator part was integrated with either a passive backing part or with a pressure-sensing element, including an 80 μm thick and 6 mm diameter diaphragm. The study includes measuring thermally and mechanically induced resonance frequency shifts, and thermally induced deformations. For the pressure sensor device, contributions from changes in the relative permittivity and from expanding air, trapped in the cavity, were extracted. The devices exhibited thermomechanical robustness during heating, regardless of the thickness of the backing. The pressure sensitivity decreased with increasing temperature from 15 050 ppm/bar at room temperature to 2400 ppm/bar at 1000°C, due to the decreasing pressure difference between the external pressure and the air pressure inside the cavity. 

    Keywords
    Wireless Reading, HTCC, Pressure sensing, Harsh Environments, Thermomechanical properties
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-253555 (URN)10.1088/0960-1317/25/9/095016 (DOI)000365167700023 ()
    Funder
    Knut and Alice Wallenberg Foundation
    Available from: 2015-05-29 Created: 2015-05-29 Last updated: 2018-08-03Bibliographically approved
    2. Ceramic Pressure Sensor for High Temperatures – Investigation of the Effect of Metallizationon on Read Range
    Open this publication in new window or tab >>Ceramic Pressure Sensor for High Temperatures – Investigation of the Effect of Metallizationon on Read Range
    2017 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 17, no 8, p. 2411-2421Article in journal (Refereed) Published
    Abstract [en]

    A study on the relationship between circuit metallization, made by double-layer screen printing of platinum and electroplating of silver on top of platinum, and its impact on practical read range of ceramic LC resonators for high-temperature pressure measurements is presented. Also included is the first realization of membranes by draping a graphite insert with ceramic green body sheets. As a quality factor circuit reference, two-port microstrip meander devices were positively evaluated and to study interdiffusion between silver and platinum, test samples were annealed at 500 degrees C, 700 degrees C, and 900 degrees C for 4, 36, 72, and 96 h. The LC resonators were fabricated with both metallization methods, and the practical read range at room temperature was evaluated. Pressure-sensitive membranes were characterized for pressures up to 2.5 bar at room temperature, 500 degrees C and up to 900 degrees C. Samples electroplated with silver exhibited performance equal to or better than double-layer platinum samples for up to 60 h at 500 degrees C, 20 h at 700 degrees C, and for 1 h at 900 degrees C, which was correlated with the degree of interdiffusion as determined from cross-sectional analysis. The LC resonator samples with double-layer platinum exhibited a read range of 61 mm, and the samples with platinum and silver exhibited a read range of 59 mm. The lowest sheet resistance, and, thereby, the highest read range of 86 mm, was obtained with a silver electroplated LC resonator sample after 36 h of annealing at 500 degrees C.

    Keywords
    Alternative metallization, ceramic membrane, harsh environment sensor, high temperature co-fired ceramics (HTCC), HTCC processing, LC resonator, pressure sensor, wireless reading
    National Category
    Accelerator Physics and Instrumentation Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-302852 (URN)10.1109/JSEN.2017.2671418 (DOI)000398890800016 ()
    Available from: 2016-09-11 Created: 2016-09-11 Last updated: 2018-08-03Bibliographically approved
    3. Manufacturing and characterization of a ceramic microcombustor with integrated oxygen storage and release element
    Open this publication in new window or tab >>Manufacturing and characterization of a ceramic microcombustor with integrated oxygen storage and release element
    Show others...
    2015 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, no 10, article id 104006Article in journal (Refereed) Published
    Abstract [en]

    A microscale ceramic high-temperature combustor with a built-in temperature sensor and source of oxygen has been designed, manufactured and characterized. The successful in situ electroplating and oxidation of copper, and the use of copper oxide as the source of oxygen were demonstrated. It was shown that residual stresses from electroplating, copper oxidation and oxide decomposition did not cause much deformation of the substrate but influenced mainly the integrity and adhesion of the metal films. The process had influence on the electrical resistances, however. Calibration of the temperature sensor and correlation with IR thermography up to 1000°C revealed a nearly linear sensor behavior. Demonstration of combustion in a vacuum chamber proved that no combustion had occurred before release of oxygen from the metal oxide resource.

    Place, publisher, year, edition, pages
    Institute of Physics (IOP), 2015
    Keywords
    isotopic analysis, HTCC, combustor, EDS, TGA, RGA, oxygen release
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-264147 (URN)10.1088/0960-1317/25/10/104006 (DOI)000366827400007 ()
    Funder
    Swedish National Space Board
    Available from: 2015-10-06 Created: 2015-10-06 Last updated: 2018-08-03Bibliographically approved
    4. Pirani Microgauge Fabricated of High-Temperature Co-fired Ceramics with Integrated Platinum Wires
    Open this publication in new window or tab >>Pirani Microgauge Fabricated of High-Temperature Co-fired Ceramics with Integrated Platinum Wires
    2019 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 285, p. 8-16Article in journal (Refereed) Published
    Abstract [en]

    This paper presents the integration and pressure sensor operation of platinum bond wires in High-Temperature Co-fired alumina (HTCC). Devices were fabricated with a 50 μm diameter wire suspended across a 500 μm wide cavity in green-body state HTCC, electrically connected to screen printed alumina conductors. The substrate shrinkage during sintering to a cavity width of 400 μm causes the wire element to elevate from the cavity´s bottom surface. Resulting devices were compared with reference devices, containing screen-printed sensor elements, as Pirani gauges operated at 100 °C in constant-resistance mode, and in dynamic mode with a feeding current of 1 A in a pressure range from 10−4 Torr to atmospheric pressure. Also, devices with wire lengths between 500 and 3500 μm were operated and studied in constant-resistance and dynamic mode. Lastly, a device is demonstrated in operation at a mean temperature of 830 °C. The results include wire elements with a consistent elevation from their substrate surfaces, with irregularities along the wires. The wire devices exhibit a faster pressure response in dynamic mode than the reference devices do but operate similarly in constant-resistance mode. Increasing the wire element length shows an increasing dynamic pressure range but a decreasing maximum sensitivity. The sensitivity is retained in high temperature mode, but the dynamic range is extended from about 10 Torr to about 700 Torr.

    Keywords
    HTCC, Pirani gauge, High temperature, Bond wires
    National Category
    Ceramics Other Electrical Engineering, Electronic Engineering, Information Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-356481 (URN)10.1016/j.sna.2018.10.008 (DOI)000456902600002 ()
    Available from: 2018-07-30 Created: 2018-07-30 Last updated: 2019-02-19Bibliographically approved
    5. Manufacturing Miniature Langmuir probes by Fusing Platinum Bond Wires
    Open this publication in new window or tab >>Manufacturing Miniature Langmuir probes by Fusing Platinum Bond Wires
    2015 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, no 10, article id 105012Article in journal (Refereed) Published
    Abstract [en]

    This paper reports on a novel method for manufacturing microscopic Langmuir probes with spherical tips from platinum bond wires for plasma characterization in microplasma sources by fusing. Here, the resulting endpoints, formed by droplets of a fused wire, are intended to act as a spherical Langmuir probe. For studying the fusing behavior, bond wires were wedge-bonded over a 2 mm wide slit, to emulate the final application, and fused at different currents and voltages. For electrical isolation, a set of wires were coated with a 4 µm thick layer of Parylene before they were fused. After fusing, the gap size, as well as the shape and area of the ends of the remaining stubs were measured. The yield of the process was also investigated, and the fusing event was studied using a high-speed camera for analyzing the dynamics of fusing. Four characteristic tip shapes were observed: spherical, semi-spherical, serpentine shaped and folded. The stub length leveled out at ~420µm. The fusing of the coated wires required a higher power for attaining a spherical shape. Finally, a Parylene coated bond wire was integrated into a stripline split-ring resonator (SSRR) microplasma source, and fused to form two Langmuir probes with spherical endpoints. These probes were used for measuring the I-V characteristics of a plasma generated by the SSRR. In a voltage range between -60 V and 60 V, the fused stubs exhibited the expected behavior of spherical Langmuir probes and will be considered for future integration.

    Keywords
    Langmuir probe; bond wire; fusing; microplasma source
    National Category
    Physical Sciences Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-251306 (URN)10.1088/0960-1317/25/10/105012 (DOI)000366827400028 ()
    Funder
    Swedish National Space BoardKnut and Alice Wallenberg Foundation
    Available from: 2015-04-15 Created: 2015-04-15 Last updated: 2018-08-03Bibliographically approved
    6. Effect of Resistive and Plasma Heating on the Specific Impulse of a Ceramic Cold Gas Thruster
    Open this publication in new window or tab >>Effect of Resistive and Plasma Heating on the Specific Impulse of a Ceramic Cold Gas Thruster
    Show others...
    2019 (English)In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 28, no 2, p. 235-244Article in journal (Refereed) Published
    Abstract [en]

    The research and development of small satellites has continued to expand over the last decades. However, the propulsion systems with adequate performance have persisted to be a great challenge. In this paper, the effects of three different heaters on the specific impulse and overall thrust efficiency of a cold gas microthruster are presented. They consisted of a conventional, printed resistive thick-film element, a freely suspended wire, and a stripline split-ring resonator microplasma source, and were integrated in a single device made from the high-temperature co-fired ceramics. The devices were evaluated in two setups, where the first measured thrust and the other measured shock cell geometry. In addition, the resistive elements were evaluated as gas temperature sensors. The microplasma source was found to provide the greatest improvement in both specific impulse and thrust efficiency, increasing the former from an un-heated level of 44–56 s when heating with a power of 1.1 W. This corresponded to a thrust efficiency of 55%, which could be compared with the results from the wire and printed heaters which were 51s and 18%, and 45s and 14%, respectively. The combined results also showed that imaging the shock cells of a plasma heated thruster was a simple and effective way to determine its performance, when compared to the traditional thrust balance method.

    Keywords
    Microthruster, HTCC, Resistive Heating, Plasma Heating, Specific Impulse, Shock Cells
    National Category
    Aerospace Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-356675 (URN)10.1109/JMEMS.2019.2893359 (DOI)000463623600008 ()
    Available from: 2018-08-02 Created: 2018-08-02 Last updated: 2019-04-25Bibliographically approved
    7. On the Applicability and Military Utility of Microsystems in Military Jet Engines
    Open this publication in new window or tab >>On the Applicability and Military Utility of Microsystems in Military Jet Engines
    (English)Manuscript (preprint) (Other academic)
    Keywords
    HTCC, jet engine control, applicability, military utility
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:uu:diva-356691 (URN)
    Available from: 2018-08-03 Created: 2018-08-03 Last updated: 2018-08-03
  • 30.
    Sturesson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC). Försvarshögskolan/Swedish National Defence College.
    Bull, Peter
    Försvarshögskolan/Swedish National Defence College.
    On the Applicability and Military Utility of Microsystems in Military Jet EnginesManuscript (preprint) (Other academic)
  • 31.
    Sturesson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC). Försvarshögskolan/Swedish National Defence College.
    Seton, Ragnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Persson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Effect of Resistive and Plasma Heating on the Specific Impulse of a Ceramic Cold Gas Thruster2019In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 28, no 2, p. 235-244Article in journal (Refereed)
    Abstract [en]

    The research and development of small satellites has continued to expand over the last decades. However, the propulsion systems with adequate performance have persisted to be a great challenge. In this paper, the effects of three different heaters on the specific impulse and overall thrust efficiency of a cold gas microthruster are presented. They consisted of a conventional, printed resistive thick-film element, a freely suspended wire, and a stripline split-ring resonator microplasma source, and were integrated in a single device made from the high-temperature co-fired ceramics. The devices were evaluated in two setups, where the first measured thrust and the other measured shock cell geometry. In addition, the resistive elements were evaluated as gas temperature sensors. The microplasma source was found to provide the greatest improvement in both specific impulse and thrust efficiency, increasing the former from an un-heated level of 44–56 s when heating with a power of 1.1 W. This corresponded to a thrust efficiency of 55%, which could be compared with the results from the wire and printed heaters which were 51s and 18%, and 45s and 14%, respectively. The combined results also showed that imaging the shock cells of a plasma heated thruster was a simple and effective way to determine its performance, when compared to the traditional thrust balance method.

  • 32.
    Vu Trong, Thu
    et al.
    FPT university, Hanoi, Vietnam.
    Dinh Quoc, Tri
    FPT university, Hanoi, Vietnam.
    Dao Van, Thang
    FPT university, Hanoi, Vietnam.
    Pham Quang, Hung
    FPT university, Hanoi, Vietnam.
    Nguyen, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Constellation of small quick-launch and self-deorbiting nano-satellites with AIS receivers for global ship traffic monitoring2011In: 2nd Nano-Satellite Symposium, Tokyo, Japan, Mars 2011, 2011Conference paper (Refereed)
    Abstract [en]

    Since December 2004 the International Maritime Organization's International Convention for the Safety of Life at Sea requires that Automatic Identification System (AIS) has to be implemented on all international voyaging ships with gross tonnage of 300 or more tons, and on all passenger ships regardless of size. This stems from the need of collision avoidance, search-and-rescue operations and other maritime purposes. Ground-based AIS receiving station usually cannot cover ships over the horizon, but with space-based AIS signal receivers, the global ship monitoring became possible, providing data service for maritime administrations, cargo liners, and even navies. Since 2007, a number micro-satellites and nano-satellites have been launched for technical demonstration in this respect. However, at present the space-based global AIS data service is not fully operational and international cooperation is limited. In this paper, a constellation of 3 self-deorbiting nano-satellites, with a mass equivalent to 3U cubesats, carrying AIS receivers is proposed to complement the existing systems. The feasible study presented here showed that this mission can be realized at very low cost, and quick-launched. Three other important features of the mission are: international cooperation, making a practical use of smaller nano-satellites and taking the responsibility for deorbiting the satellites at the end of mission. It is also the hope that this mission will become a milestone that marks the maturity of smaller nanosats, and give the "student satellite" projects around the world a new dimension for real application and sustainable business application.

  • 33.
    Vu Trong, Thu
    et al.
    FPT university, Hanoi, Vietnam.
    Pham Quang, Hung
    FPT university, Hanoi, Vietnam.
    Nguyen Hoang, Giang
    FPT university, Hanoi, Vietnam.
    Nguyen, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Tiềm năng lớn của vệ tinh siêu nhỏ đáp ứng nhu cầuquản lý hàng hải của Việt Nam2011In: REV/ComNaVi-11, Workshop on Communications and Navigations for the Development of Vietnam's Marine Economy, Da Nang city Vietnam, August 2-4, 2011,, 2011Conference paper (Refereed)
    Abstract [un]

    Trong 10 năm gần đây, loại vệ tinh siêu nhỏ có kích thước 10x10x10 cm và trọng lượng 1 kg với tên gọi CubeSat từ công cụ thực hành của sinh viên đại học đang dần trở thành nền tảng cho những vệ tinh có khả năng ứng dụng trong thực tiễn. Ngày nay, người sử dụng có thể tự thiết kế hoặc mua sẵn linh kiện điện tử và cơ khí lắp thành vệ tinh cỡ 1, 2, 3... kg với các tính năng mong muốn. Ưu điểm của loại vệ tinh siêu nhỏ này là thời gian chế tạo ngắn, chi phí thấp và càng phát huy năng lực khi sử dụng cả một chùm vệ tinh. Nhờ có thể thích hợp hóa dễ dàng với từng nhu cầu thực tiễn và nhờ những tiến bộ nhanh chóng trong lĩnh vực điện tử và công nghệ thu nhỏ các hệ thống cảm ứng, nhiều nhu cầu quản lý hàng hải của Việt Nam được đánh giá là khả thi ngay trong thời điểm hiện tại.

     Nhiều trường đại học trên thế giới đã sử dụng thành công vệ tinh siêu nhỏ trong các chương trình viễn thám và khoa học vũ trụ. Gần đây, Trường đại học FPT cộng tác với Đại học Uppsala Thụy Điển đã đưa ra ý tưởng sử dụng loại vệ tinh này trong công tác quản lý hàng hải Việt Nam và đã được Trường đại học Tokyo, Nhật Bản tuyển chọn, mời sang trình bày đề án tại hội thảo “2nd Nano-satellite symposium” ngày 13-15/3/2011. Nói tóm tắt, đây là đề án dùng chùm vệ tinh siêu nhỏ loại 3kg có trang bị máy thu tín hiệu định vị (AIS) của tàu thuyền lưu thông trên biển, nhằm hỗ trợ công tác quản lý hàng hải và tìm kiếm, cứu nạn.

     Bài viết này đề cập đến loại vệ tinh siêu nhỏ CubeSat có thể áp dụng cho các nhu cầu thiết thực của Việt Nam, đồng thời cũng trình bày về đề án theo dõi sự di chuyển của tàu biển từ vệ tinh làm ví dụ điển hình cho thấy tiềm năng lớn của vệ tinh siêu nhỏ đáp ứng nhu cầu quản lý hàng hải hiện nay của đất nước.

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