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  • 1.
    Avelin, Anders
    et al.
    Mälardalen University, School of Business, Society and Engineering.
    Widarsson, Björn
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Lilja, Reijo
    VTT, Espoo, Finland.
    Time based data reconciliation and decision support for a CFB boiler2009In: IFAC Proceedings Volumes (IFAC-PapersOnline), 2009 / [ed] Yrjö Majanne, Tampere: Tampere University Press , 2009, p. 338-343Conference paper (Refereed)
    Abstract [en]

    This paper covers a method for operator decision support, where physical simulation models are used to connect different physical variables to each other. By comparing energy and material balances for a larger process area inconsistencies in single process parts and sensor measurements can be detected, by following the development between single measurements and values predicted from the simulations. This information then can be used as input to e.g. a BN, Bayesian Network, for decision support. The application has been for a CFB boiler at Mälarenergi AB. The simulators have been made in Modelica respectively a more advanced model in APROS.

  • 2. Blanco, Angeles
    et al.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Kappen, Johannes
    Manninen, Jussi
    Negro, Carlos
    Rittala, Risto
    Chapter 12: Modelling and simulation in the Pulp and Paper Industry: Current state and future perspectives2006In: Handbook of Control Room Design and Ergonomics: A Perspective for the Future / [ed] Toni Ivergård and Brian Hunt, Taylor & Francis Group, 2006, 2nd, p. 311-326Chapter in book (Other academic)
  • 3.
    Dahlquist, Erik
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Hunt, Brian
    Ivergård, Toni
    Chapter 8: Industrial Applications and Case Studies2009In: Handbook of Control Room Design and Ergonomics: A Perspective for the Future / [ed] Toni Ivergård and Brian Hunt, Taylor & Francis Group, 2009, 2nd, p. 203-226Chapter in book (Other academic)
  • 4.
    Dahlquist, Erik
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Tomas-Aparicio, Elena
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Jansson, Johan
    SAPPI South Africa.
    On-line simulations for diagnostics and control2010In: International Control Systems 2010 Proceedings / [ed] Alf Isaksson, Stockholm: SPCI , 2010Conference paper (Refereed)
    Abstract [en]

    The main objective of this project is to develop an application where physical models of fibre lines are run in parallel to the real processes. This application can be useful as a diagnostic tool to detect faults and improve process operations. By running the simulation models continuously, feeding input data from the process data base at a pre-determined time interval, the simulation will show results from the “normal operations”. These simulation results are compared to the measured data and hence faults can be detected e.g. hang-ups in the digester and channelling. NIR-spectra lab measurements of the wood chips fed into the digester can as well be considered. This feature give us the possibility of correlating the quality of the obtained pulp to the raw material used, which can be of help when tuning the process parameters.

    In this paper results from the use of the application described above in several mills in South Africa and results from some preliminary tests in a mill in Sweden are presented. Moreover, the system structure for the interaction between the physical models designed in Modellica language and the real process data is described.

  • 5.
    Gerdtman, Christer
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Bäcklund, Ylva
    Office for Science and Technology, Uppsala University, Uppsala, Sweden.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    A gyro sensor based computer mouse with a USB interface: A technical aid for motor-disabled people2012In: Technology and disability, ISSN 1055-4181, Vol. 24, no 2, p. 117-127Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to develop an alternative computer mouse for disabled persons. The mouse developed is a flexible input device with a multi-click function, which can be attached to a selectable body part (eg head, arm, foot). The mouse has a MEMS-gyroscope as the motion sensor, which is both small and sensitive. A USB-interface with a HID-profile is used to make the installation easy, "plug & play", and to make it compatible for use on any modern computer, independent of the operating system (Windows, Linux, Mac etc.). The structure is modular to achieve a flexible functionality. The mouse has individually adapted click-functions with selectable click devices, in addition to which, it is possible to define individual settings of the mouse parameters. The functionality can be extended by adding further personal settings, thereby programming the mouse for individual optimal performance. The result is a reliable and useful computer mouse for people with disabilities. In the development process, 23 users have been interviewed, three of whom participated in a 6 month long-term test. The study shows that a computer mouse incorporating a MEMS-gyroscope is a good, flexible solution, providing a high performance technical aid with extremely good sensitivity at a modest cost.

  • 6.
    Gerdtman, Christer
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Bäcklund, Ylva
    Uppsala University.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Development of a Test Rig for MEMS-based Gyroscopic Motion Sensors in Human Applications2011In: IFMBE Proceedings,  Volume 34 IFMBE, 2011, 2011, p. 203-206Conference paper (Refereed)
    Abstract [en]

    This paper describes the development of a test rig for MEMS gyroscopes. The purpose of the test rig is testing and verification of various gyroscopes that are intended for human motion analysis. The test rig will be a tool to test functionality and help in the selection process of appropriate MEMS-gyroscopes. Human movement pattern differs from mechanical motion and thus puts specific demands on the test equipment and verification procedures. The main function of the test rig is to rotate the gyroscope and measure the precision in the sensor signal response in different situations. This includes detection of different movement patterns and performances in different environment conditions (e.g. temperature, vibrations, etc). Several components can be tested at the same time in the test rig. Among the things that can be evaluated is the performance of the components, comparisons between different individual components or batches, aging processes of components and verification of the component performance for comparison of the specifications from the manufacturer. There are several different pre-programmed test-programs available but the test rig can also be manually operated. The data from the tests are stored and can be analyzed and processed afterwards.

  • 7.
    Gerdtman, Christer
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Folke, Mia
    Mälardalen University, School of Innovation, Design and Engineering.
    Bexander, Catharina
    Hälsans hus.
    Brodd, Anita
    Mälardoktorerna HB.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Portable sensor system for rehabilitation of WAD patients2009In: Proceedings of the 6th International Workshop on Wearable, Micro, and Nano Technologies for Personalized Health: "Facing Future Healthcare Needs", IEEE , 2009, p. 65-68Conference paper (Refereed)
    Abstract [en]

    Whiplash Associated Disorders (WAD) are several remaining symptoms after an acceleration-/deceleration injury of the neck, often due to a road accident. Common symptoms are neck pain, headache, stiffness, loss of sensation, memory impairment and concentration difficulties. The whiplash-related injuries were estimated to cost Sweden more than SEK 4 billion 2005, the main part of these costs takes the form of compensation for loss of income, as a result of incapacity for work. The aim of this project has been to develop a training and rehabilitation system for patients suffering from WAD. The portable system is based on a 2-axis gyroscopic sensor with a computer interface. The sensor system is placed on the head of the patient and movements of the head are mirrored on the computer screen. The patient is supposed to follow a visible track on the screen. This enables interactive training facilities for patients, who can use the system unsupervised in their home environment.

  • 8.
    Gerdtman, Christer
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Lindén, Maria
    Mälardalen University, Department of Computer Science and Electronics.
    Development of a gyro sensor based computer mouse with USB interface interface as technical aid for disabled persons2005In: 3rd European Medical & Biological Engineering Conference (EMBEC’05), Vienna (Austria): Society for the Organization of the European Medical and Biological Engineering Conference EMBEC , 2005Conference paper (Refereed)
    Abstract [en]

    This paper describes the development of an alternative computer mouse for disabled persons. The mouse is an advanced technical aid for a large group of disabled (handicapped) persons, and can be placed on variuos suitable body parts. The mouse is module based and have many functions that enable a disabled persons to control a computer. It also allows the person to work efficent on the computer. The functions have been developed togehter with disabled persons and are based on their wishes and needs. Therfor it is not only a «head-mouse», it is an alternative mouse! The device is a gyro sensor based computer mouse and it operates by sensing the rotation of a body part. The disabled users appreciated the high sensitivity of the mouse and that it is easy to install and use, thanks the USB «plug&play» functionality. The mouse is a small and comfortable computer mouse that suits a various groups of disabled persons with different types of movement handicaps.

  • 9.
    Gärtner, Johan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Johansson, Philip
    Mälardalen University, School of Innovation, Design and Engineering.
    AN ADAPTIVE CONTROL SYSTEM BASED ON PID, I2PD AND RLS, A SIMULATED DESIGN FOR UAVS2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During this master thesis an adaptive control system for angular velocity was developed. The approach focuses on radio controlled quadrotors and thereby targets a computational efficient solution. The adaptation is divided into two steps. First, an Integral Squared Plus Time Delay (I2PD) model estimation is done through the Recursive Least Squares (RLS) algorithm. Second, control parameters for the quadrotors Proportional Integral Derivative (PID) controller are found by using empirically modified Tuning Rules (TRs) which are based on the I2PD model. Simulation results show the benefits of an adaptive tuning algorithm in regards of the time consuming process of manually tuning a PID controller as well as robustness against both predictable and unpredictable system changes. This includes actuator degradation, battery consumption, changes in weight or inertia etc. However, it is apparent that the tuning algorithm demands an arbitrary initial approximation to be stable at initialization.

  • 10.
    Hernández González, Francisco
    Mälardalen University, School of Innovation, Design and Engineering.
    Planar Robot Arm Modelling and Control2012Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis objective is to model a one link robotic arm mounted on a sliding mobile platform and to investigate different control strategies under the effect of gravity and external force disturbance. For simplicity the robotic set up can be modelled and controlled as an inverted pendulum moving on a non constant sloping surface.

    Firstly the control is done on level ground. This lower mathematical complexity will be taken as an advantage to approach the analysis on aspects more related with control theory: several control techniques and observers, steady state error study, etcetera.

    Afterwards the control is generalized for sloping grounds. This chapter will seek situations closer to reality, the purpose is to design something with practical interests, like model a Segway.

  • 11.
    Kujan, Dzana
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Radisavljevic, Nikola
    Mälardalen University, School of Innovation, Design and Engineering.
    Migrating process automation applications to mobile2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 12.
    Lindberg, Carl-Fredrik
    et al.
    ABB Corporate Research, Sweden.
    Isaksson, Alf
    ABB Corporate Research, Sweden.
    Comparison of different sampling schemes for wireless control subject to packet losses2015In: First International Conference on Event-Based Control, Communication, and Signal Processing, 2015Conference paper (Refereed)
    Abstract [en]

    Three different approaches to reduce the amount of communication in wireless control subject to packet losses have been evaluated in an extensive simulation study. The sampling approaches are: slow periodic, event-based and self-triggered sampling. They are ranked based on their integrated absolute error (IAE) control performance and also compared with fast periodic sampling. The three approaches have surprisingly equal control performance in the nominal case (without packet losses) for a wide range of test scenarios (process models, controller tunings etc.). With packet losses the importance of re-transmissions becomes evident.

  • 13.
    Lindberg, Carl-Fredrik
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zahedian, Kourosh
    ABB AB, Västerås, Sweden.
    Solgi, Maryam
    ABB AB, Västerås, Sweden.
    Lindkvist, Rickard
    ABB AB, Västerås, Sweden.
    Potential and limitations for industrial demand side management2014In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 61, p. 415-418Article in journal (Refereed)
    Abstract [en]

    The growing share of variable renewable power such as wind and solar photovoltaic (PV) emphasize the importance of demand side management. In a couple of years consumers have to adapt their consumption more to available generated power in order to maintain grid stability and to reduce their electricity costs. In this study the potential and limitations for demand side management in about 15 different companies in Sweden has been investigated. A brief description of some of the company’s production process is given, with focus on electrical consumption. Suggestions on different demand side management possibilities are presented as well as limitations. The suggestions are given for different time horizons, from load shifting between hours, to weeks and years. Potential savings achieved with demand side management have also been evaluated based on historical electricity prices from different countries.

  • 14.
    Mostafa Orand, Seyed
    et al.
    Islamic Azad University, Science and Research Branch, Saveh, Iran .
    Mirzazadeh, Abolfazl
    Kharazmi University, Tehran, Iran.
    Ahmadzadeh, Farzaneh
    Islamic Azad University, Karaj Branch, Iran.
    Talebloo, Farid
    Sufi Razi, Zanjan, Iran.
    Optimisation of the Inflationary Inventory Control Model under Stochastic Conditions with Simpson Approximation: Particle Swarm Optimisation Approach2015In: Iranian Journal of Management Studies, ISSN 2008-7055, Vol. 8, no 2, p. 203-220Article in journal (Refereed)
  • 15.
    Nylander, Michelle
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Aparicio Tomas, Elena
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    ANALYSIS AND OPTIMIZATION OF ENERGY FLOWS IN A PULP MILL2008In: Proceedings of Control Systems,  2008 / [ed] Andrea Borrelli, Vancouver: TAPPI Press , 2008Conference paper (Refereed)
    Abstract [en]

    In this paper the digester house process variables

    are first studied to identify the process variations in

    different time perspectives. The focus is on the

    perspective of controlling the process on-line for

    the next 24 hours. With a mathematical model first

    the cook and the flows associated with the digester

    house are modelled. From this different scenarios

    with different “faults” are implemented in the

    model and compared to the process data. From this

    the performance can be predicted for different

    conditions. Key numbers are determined from this

    and these are used together with suitable objective

    functions to make optimal production planning for

    model based control. The set points are sent to the

    control system. By determining the reactivity of

    different qualities of wood chips by measuring NIR

    and measuring final kappa, a tool for feed forward

    control is developed.

  • 16.
    Packalén, Sture
    et al.
    Uppsala universitet.
    Daniels, Mats
    Uppsala universitet.
    Hansson, Hans
    Uppsala universitet.
    MÄTNING OCH STYRNING1985 (ed. 1)Book (Other (popular science, discussion, etc.))
  • 17.
    Papadopoulos, Alessandro
    et al.
    Lund University, Sweden.
    Maggio, Martina
    Lund University, Sweden.
    Terraneo, Federico
    Politecnico di Milano, Italy.
    Leva, Alberto
    Politecnico di Milano, Italy.
    A Dynamic Modelling Framework for Control-based Computing System Design2015In: Mathematical and Computer Modelling of Dynamical Systems, ISSN 1387-3954, E-ISSN 1744-5051, Vol. 21, no 3, p. 251-271Article in journal (Refereed)
    Abstract [en]

    This manuscript proposes a novel viewpoint on computing systems’ modelling. The classical approach is to consider fully functional systems and model them, aiming at closing some external loops to optimize their behaviour. On the contrary, we only model strictly physical phenomena, and realize the rest of the system as a set of controllers. Such an approach permits rigorous assessment of the obtained behaviour in mathematical terms, which is hardly possible with the heuristic design techniques, that were mainly adopted to date. The proposed approach is shown at work with three relevant case studies, so that a significant generality can be inferred from it.

  • 18.
    Papadopoulos, Alessandro
    et al.
    Politecnico di Milano, Italy.
    Prandini, Maria
    Politecnico di Milano, Italy.
    Model reduction of switched affine systems2016In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 70, p. 57-65Article in journal (Refereed)
    Abstract [en]

    This paper addresses model reduction and extends balanced truncation to the class of switched affine systems with endogenous switching. The switched affine system is rewritten as a switched linear one with state resets that account for the affine terms. Balanced truncation can then be applied to each mode dynamics, independently. As a result, different reduced state vectors are associated with the different modes, and reset maps are here appropriately redefined so as to account and compensate for this mismatch, possibly preserving the continuity of the output. The overall behavior of the reduced switched system is determined by both the selected reduction per mode and the adopted reset maps. In this paper, we consider a stochastic setting and propose a randomized method for the selection of the reduced order. The performance of the proposed approach is illustrated through a multi-room temperature control example.

  • 19.
    Paulsson, Christian
    Mälardalen University, School of Innovation, Design and Engineering.
    Dasher the running robot2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 20.
    Rahman, Hamidur
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Non-Contact Physiological Parameters Extraction Using Facial Video Considering Illumination, Motion, Movement and Vibration2020In: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 67, no 1, p. 88-98, article id 8715455Article in journal (Refereed)
    Abstract [en]

    Objective: In this paper, four physiological parameters, i.e., heart rate (HR), inter-beat-interval (IBI), heart rate variability (HRV), and oxygen saturation (SpO2), are extracted from facial video recordings. Methods: Facial videos were recorded for 10 min each in 30 test subjects while driving a simulator. Four regions of interest (ROIs) are automatically selected in each facial image frame based on 66 facial landmarks. Red-green-blue color signals are extracted from the ROIs and four physiological parameters are extracted from the color signals. For the evaluation, physiological parameters are also recorded simultaneously using a traditional sensor 'cStress,' which is attached to hands and fingers of test subjects. Results: The Bland Altman plots show 95% agreement between the camera system and 'cStress' with the highest correlation coefficient R = 0.96 for both HR and SpO2. The quality index is estimated for IBI considering 100 ms R-peak error; the accumulated percentage achieved is 97.5%. HRV features in both time and frequency domains are compared and the highest correlation coefficient achieved is 0.93. One-way analysis of variance test shows that there are no statistically significant differences between the measurements by camera and reference sensors. Conclusion: These results present high degrees of accuracy of HR, IBI, HRV, and SpO2 extraction from facial image sequences. Significance: The proposed non-contact approach could broaden the dimensionality of physiological parameters extraction using cameras. This proposed method could be applied for driver monitoring application under realistic conditions, i.e., illumination, motion, movement, and vibration.

  • 21.
    Rezaei, Amin
    et al.
    University of Louisiana at Lafayette, Lafayette, United States .
    Daneshtalab, Masoud
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Zhao, Dan
    Old Dominion University, Norfolk, United States .
    Modarressi, Mehdi
    University of Tehran, Tehran, Iran .
    SAMi: Self-aware migration approach for congestion reduction in NoC-based MCSoC2016In: International System on Chip Conference, IEEE Computer Society, 2016, p. 145-150Conference paper (Refereed)
    Abstract [en]

    Many-Core System-on-Chips (MCSoCs) require efficient task migration approach in order to reach system performance objectives such as load balancing, communication optimization, fault tolerance, and temperature control. In this paper an efficient self-aware migration approach is introduced for NoC-based MCSoCs using a centralized feedback controller in order to control the congestion over the system. The proposed approach is divided into four main steps: predicting behavior of the application, defining reliable triggers to initiate task migration, introducing cost comparison functions, and presenting a streamlined controlling mechanism to migrate tasks. The experimental results affirm that the proposed self-aware migration approach can help achieving significant throughput and system utilization while efficiently controlling system congestion.

  • 22.
    Salido Monzú, David
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Roldán Sánchez, Oliver
    Mälardalen University, School of Innovation, Design and Engineering.
    Robot Positioning System: Underwater Ultrasonic Measurement2009Independent thesis Advanced level (degree of Master (One Year)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    This document provides a description about how the problem of the detection of thecenter of a defined geometry object was solved.This named object has been placed in an experimental environment surrounded bywater to be explored using microwaves under the water, to try to find a possibletumor. The receiver antenna is fixed in the tip of the tool of an ABB robot.Due to this working method, it was necessary to locate the center of this object tomake correctly the microwave scanning turning always around the actual center. Thiswork not only consist in give a hypothetic solution to the people who gave us theresponsibility of solve their problem, it is also to actually develop a system whichcarries out the function explained before.For the task of measuring the distance between the tip of the tool where themicrowave antenna is, ultrasonic sensors has been used, as a complement of acomplete system of communication between the sensor and finally the robot handler,using Matlab as the main controller of the whole system.One of these sensors will work out of water, measuring the zone of the object which isout of the water. In the other hand, as the researching side of the thesis, a completeultrasonic sensor will be developed to work under water, and the results obtained willbe shown as the conclusion of our investigation.The document provides a description about how the hardware and software necessaryto implement the system mentioned and some equipment more which were essentialto the final implementation was developed step by step.

  • 23.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Andersson, A.
    Chalmers University, Gothenburg, Sweden.
    Funk, Peter
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Mixed-Effect Models for the Analysis and Optimization of Sheet-Metal Assembly Processes2017In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 13, no 5, p. 2194-2202, article id 7857795Article in journal (Refereed)
    Abstract [en]

    Assembly processes can be affected by various parameters, which is revealed by the measured geometrical characteristics (GCs) of the assembled parts deviating from the nominal values. Here, we propose a mixed-effect model (MEM) application for the purposes of analyzing variations in assembly cells, as well as for screening the input variables and characterization. MEMs make it possible to take into account statistical dependencies that originate from repeated measurements on the same assembly. The desirability functions approach was used to describe how to find corrective or control actions based on the fitted MEM. Objectives: To examine the usefulness of the MEM between the positions of the in-going parts as the input controllable variables and the measured GCs as the outputs. Methods: The data from 34 car frontal cross members (each measured three times) were experimentally collected in a laboratory environment by intentionally changing the positions of the in-going parts, assembling the parts, and subsequently measuring their GCs. A single MEM that completely describes the assembly process was fitted between the GCs and the positions of the in-going parts. Results: We present a modeling technique that can be used to establish which measured GCs are influenced by which controllable variables, and how this occurs. The fitted MEM shows evidence that the variability of some GCs changes over time. The natural variation in the system (i.e., unmodeled variations) is about two times larger than the variation between the assembled cross members. We also present two cases that demonstrate how to use the fitted MEM desirability functions to find corrective or control actions. Conclusion: MEMs are very useful tools for analyzing the assembly processes for car-body parts, which are nonlinear processes with multiple inputs and multiple correlated outputs. MEMs can potentially be applied in numerous industrial processes, since modern manufacturing plants measure all important process variables, which is the sole prerequisite for MEMs applications. 

  • 24.
    Trosten, Torbjörn
    et al.
    Mälardalen University, School of Innovation, Design and Engineering. Bombardier Transportation, Västerås, Sweden.
    Moskull, Henrik
    Bombardier Transportation, Västerås, Sweden.
    Lindahl, Martin
    Bombardier Transportation, Västerås, Sweden.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Maher, Azaza
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Energy Optimal Switching Frequency for a 750V Metro Traction Drive Using Silicon Carbide MOSFET Inverter2018In: Energy Optimal Switching Frequency for a 750V Metro Traction Drive Using Silicon Carbide MOSFET Inverter, 2018Conference paper (Refereed)
    Abstract [en]

    The introduction of Silicon Carbide (SiC) MOSFET based inverters into the traction drive makes it possible to increase the inverter switching frequency and reduce energy consumption. This paper describes how to model switching frequency dependent losses in the traction drive and compares the calculated losses to measurements done on a newly developed SiC MOSFET based traction drive. The results from the developed loss models of motor and inverter agrees well with the results from energy measurements. This paper concludes that the energy use of the traction motor and inverter can be simulated well using simple models where skin-effect losses in the motor are modelled in detailed. This paper also concludes that in terms of energy efficiency, the optimal switching frequency using a SiC MOSFET based inverter, is in the range of 3-6 kHz.

  • 25.
    Wang, W.
    et al.
    Computer Science Department, University of Pittsburgh, Pittsburgh, PA, United States.
    Mosse, D.
    Computer Science Department, University of Pittsburgh, Pittsburgh, PA, United States.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Packet priority assignment for wireless control systems of multiple physical systems2019In: Proceedings - 2019 IEEE 22nd International Symposium on Real-Time Distributed Computing, ISORC 2019, Institute of Electrical and Electronics Engineers Inc. , 2019, Vol. 107, p. 143-150Conference paper (Refereed)
    Abstract [en]

    Wireless control systems (WCSs) have gained much attention lately, due to their easy deployment and flexibility compared to wired control systems. However, this comes at the cost of possibly increased network delay and packet losses, that can significantly impact the control system performance, and possibly its stability. Such problems become even more relevant if the network is shared among different control systems, and thus becomes a scarce resource, like in Industrial Internet of Things applications. In this paper, we describe how to assign packet priorities dynamically when there are many physical systems sharing a given network, aiming at minimizing the performance degradation of the WCS. Towards that, we present a network model including both delay and packet losses, both of which are very important for the control system performance. Our solution is evaluated over two different use cases to show the generality of the approach: the WCS for a set of inverted pendula, and the WCS for small modular reactors in a nuclear power plant. The results show that the proposed approach allows for a more stable performance even in presence of highly nonlinear systems, sensitive to time-varying delays, as well as in presence of high network interference.

  • 26.
    Weidl, Galia
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology. University of Stuttgart.
    Madsen, Anders
    HUGIN Expert A/S, Denmark.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Decision support on complex industrial process operation2008In: Bayesian networks: Apractical guide to applications / [ed] Olivier Pourret, Patrik Naim and Bruce Marcot, Chichester, UK: John Wiley & sons , 2008, 1st, p. 311-328Chapter in book (Other (popular science, discussion, etc.))
    Abstract [en]

    A practical guide to applications of Bayesian Networks. Theoretical aspects of BNs together with a number of applications in different areas like sensor validation, process industry applications, forensic science, terrorism risk management, robotics risk management, classification of wines, pavement and bridge management, and enhancing human cognition.

  • 27.
    Xiong, Ning
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Funk, Peter
    Mälardalen University, Department of Computer Science and Electronics.
    Building similarity metrics reflecting utility in case-based reasoning2006In: Journal of Intelligent & Fuzzy Systems, ISSN 1064-1246, E-ISSN 1875-8967, Vol. 17, no 4, p. 407-416Article in journal (Refereed)
    Abstract [en]

    Fundamental to case-based reasoning is the idea that similar problems have similar solutions. The meaning of the concept of "similarity" can vary in different situations and remains an issue. Since we want to identify and retrieve truly useful or relevant cases for problem solving, the metrics of similarity must be defined suitably to reflect the utility of cases for solving a particular target problem. A framework for utility-oriented similarity modeling is developed in this paper. The main idea is to exploit a case library to obtain adequate samples of utility from pairs of cases. The task of similarity modeling then becomes the customization of the parameters in a similarity metric to minimize the discrepancy between the assessed similarity values and the utility scores desired. A new structure for similarity metrics is introduced which enables the encoding of single feature impacts and more competent approximation of case utility. Preliminary experimental results have shown that the proposed approach can be used for learning with a surprisingly small case base without the risk of over-fitting and that it yields stable system performance with variations in the threshold selected for case retrieval.

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