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  • 1.
    Abbasi, Jasim Aftab
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Test of Rapid Control System Development using TargetLink2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis is to employ and evaluate an evaluation board with the standard microprocessor freescale MPC5554EVB board for implementation of control algorithms which are created in Matlab/Simulink instead of using dSPACE prototyping hardware. The Simulink real-time model shall be compiled to the MPC5554EVB board. TargetLink is a powerful software tool which allows an automatic generation of efficient C code from Simulink and facilitates model-based control design. The goal of this thesis is to learn how to use TargetLink in a control design workflow from model to real code and what are the limitations of a microprocessor platform and to evaluate the capabilities of TargetLink to generate a working code for a generic microprocessor.

  • 2.
    Abedan Kondori, Farid
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Bring Your Body into Action: Body Gesture Detection, Tracking, and Analysis for Natural Interaction2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Due to the large influx of computers in our daily lives, human-computer interaction has become crucially important. For a long time, focusing on what users need has been critical for designing interaction methods. However, new perspective tends to extend this attitude to encompass how human desires, interests, and ambitions can be met and supported. This implies that the way we interact with computers should be revisited. Centralizing human values rather than user needs is of the utmost importance for providing new interaction techniques. These values drive our decisions and actions, and are essential to what makes us human. This motivated us to introduce new interaction methods that will support human values, particularly human well-being.

    The aim of this thesis is to design new interaction methods that will empower human to have a healthy, intuitive, and pleasurable interaction with tomorrow’s digital world. In order to achieve this aim, this research is concerned with developing theories and techniques for exploring interaction methods beyond keyboard and mouse, utilizing human body. Therefore, this thesis addresses a very fundamental problem, human motion analysis.

    Technical contributions of this thesis introduce computer vision-based, marker-less systems to estimate and analyze body motion. The main focus of this research work is on head and hand motion analysis due to the fact that they are the most frequently used body parts for interacting with computers. This thesis gives an insight into the technical challenges and provides new perspectives and robust techniques for solving the problem.

  • 3.
    Abedan Kondori, Farid
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Human Motion Analysis for Creating Immersive Experiences2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    From an early age, people display the ability to quickly and effortlessly interpret the orientation and movement of human body parts, thereby allowing one to infer the intentions of others who are nearby and to comprehend an important nonverbal form of communication. The ease with which one accomplishes this task belies the difficulty of a problem that has challenged computational systems for decades, human motion analysis.

    Technological developments over years have resulted into many systems for measuring body segment positions and angles between segments. In these systems human body is typically considered as a system of rigid links connected by joints. The motion is estimated by the use of measurements from mechanical, optical, magnetic, or inertial trackers. Among all kinds of sensors, optical sensing encompasses a large and varying collection of technologies.

    In a computer vision context, human motion analysis is a topic that studies methods and applications in which two or more consecutive images from an image sequences, e.g. captured by a video camera, are processed to produce information based on the apparent human body motion in the images.

    Many different disciplines employ motion analysis systems to capture movement and posture of human body for applications such as medical diagnostics, virtual reality, human-computer interaction etc.

    This thesis gives an insight into the state of the art human motion analysissystems, and provides new methods for capturing human motion.

  • 4.
    Abedan Kondori, Farid
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Yousefi, Shahrouz
    KTH Royal Institute of Technology, Department of Media Technology and Interaction Design.
    Kouma, Jean-Paul
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Liu, Li
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Li, Haibo
    KTH Royal Institute of Technology, Department of Media Technology and Interaction Design.
    Direct hand pose estimation for immersive gestural interaction2015In: Pattern Recognition Letters, ISSN 0167-8655, E-ISSN 1872-7344, Vol. 66, p. 91-99Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel approach for performing intuitive gesture based interaction using depth data acquired by Kinect. The main challenge to enable immersive gestural interaction is dynamic gesture recognition. This problem can be formulated as a combination of two tasks; gesture recognition and gesture pose estimation. Incorporation of fast and robust pose estimation method would lessen the burden to a great extent. In this paper we propose a direct method for real-time hand pose estimation. Based on the range images, a new version of optical flow constraint equation is derived, which can be utilized to directly estimate 3D hand motion without any need of imposing other constraints. Extensive experiments illustrate that the proposed approach performs properly in real-time with high accuracy. As a proof of concept, we demonstrate the system performance in 3D object manipulation On two different setups; desktop computing, and mobile platform. This reveals the system capability to accommodate different interaction procedures. In addition, a user study is conducted to evaluate learnability, user experience and interaction quality in 3D gestural interaction in comparison to 2D touchscreen interaction.

  • 5.
    Abedan Kondori, Farid
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Yousefi, Shahrouz
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Li, Haibo
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Direct three-dimensional head pose estimation from Kinect-type sensors2014In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 50, no 4, p. 268-270Article in journal (Refereed)
    Abstract [en]

    A direct method for recovering three-dimensional (3D) head motion parameters from a sequence of range images acquired by Kinect sensors is presented. Based on the range images, a new version of the optical flow constraint equation is derived, which can be used to directly estimate 3D motion parameters without any need of imposing other constraints. Since all calculations with the new constraint equation are based on the range images, Z(xyt), the existing techniques and experiences developed and accumulated on the topic of motion from optical flow can be directly applied simply by treating the range images as normal intensity images I(xyt). In this reported work, it is demonstrated how to employ the new optical flow constraint equation to recover the 3D motion of a moving head from the sequences of range images, and furthermore, how to use an old trick to handle the case when the optical flow is large. It is shown, in the end, that the performance of the proposed approach is comparable with that of some of the state-of-the-art approaches that use range data to recover 3D motion parameters.

  • 6.
    Abedan Kondori, Farid
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Yousefi, Shahrouz
    KTH Royal Institute of Technology, Department of Media Technology and Interaction Design.
    Liu, Li
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Li, Haibo
    KTH Royal Institute of Technology, Department of Media Technology and Interaction Design.
    Head operated electric wheelchair2014In: IEEE Southwest Symposium on Image Analysis and Interpretation (SSIAI 2014), IEEE , 2014, p. 53-56Conference paper (Refereed)
    Abstract [en]

    Currently, the most common way to control an electric wheelchair is to use joystick. However, there are some individuals unable to operate joystick-driven electric wheelchairs due to sever physical disabilities, like quadriplegia patients. This paper proposes a novel head pose estimation method to assist such patients. Head motion parameters are employed to control and drive an electric wheelchair. We introduce a direct method for estimating user head motion, based on a sequence of range images captured by Kinect. In this work, we derive new version of the optical flow constraint equation for range images. We show how the new equation can be used to estimate head motion directly. Experimental results reveal that the proposed system works with high accuracy in real-time. We also show simulation results for navigating the electric wheelchair by recovering user head motion.

  • 7.
    Abedan Kondori, Farid
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Yousefi, Shahrouz
    Ostovar, Ahmad
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Liu, Li
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Li, Haibo
    A Direct Method for 3D Hand Pose Recovery2014In: 22nd International Conference on Pattern Recognition, 2014, p. 345-350Conference paper (Refereed)
    Abstract [en]

    This paper presents a novel approach for performing intuitive 3D gesture-based interaction using depth data acquired by Kinect. Unlike current depth-based systems that focus only on classical gesture recognition problem, we also consider 3D gesture pose estimation for creating immersive gestural interaction. In this paper, we formulate gesture-based interaction system as a combination of two separate problems, gesture recognition and gesture pose estimation. We focus on the second problem and propose a direct method for recovering hand motion parameters. Based on the range images, a new version of optical flow constraint equation is derived, which can be utilized to directly estimate 3D hand motion without any need of imposing other constraints. Our experiments illustrate that the proposed approach performs properly in real-time with high accuracy. As a proof of concept, we demonstrate the system performance in 3D object manipulation. This application is intended to explore the system capabilities in real-time biomedical applications. Eventually, system usability test is conducted to evaluate the learnability, user experience and interaction quality in 3D interaction in comparison to 2D touch-screen interaction.

  • 8. Abel, Olubunmi
    et al.
    Shatunov, Aleksey
    Jones, Ashley R.
    Andersen, Peter M.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology.
    Powell, John F.
    Al-Chalabi, Ammar
    Development of a Smartphone App for a Genetics Website: The Amyotrophic Lateral Sclerosis Online Genetics Database (ALSoD)2013In: JMIR mhealth and uhealth, E-ISSN 2291-5222, Vol. 1, no 2, article id e18Article in journal (Refereed)
    Abstract [en]

    Background: The ALS Online Genetics Database (ALSoD) website holds mutation, geographical, and phenotype data on genes implicated in amyotrophic lateral sclerosis (ALS) and links to bioinformatics resources, publications, and tools for analysis. On average, there are 300 unique visits per day, suggesting a high demand from the research community. To enable wider access, we developed a mobile-friendly version of the website and a smartphone app. Objective: We sought to compare data traffic before and after implementation of a mobile version of the website to assess utility. Methods: We identified the most frequently viewed pages using Google Analytics and our in-house analytic monitoring. For these, we optimized the content layout of the screen, reduced image sizes, and summarized available information. We used the Microsoft. NET framework mobile detection property (HttpRequest. IsMobileDevice in the Request. Browser object in conjunction with HttpRequest. UserAgent), which returns a true value if the browser is a recognized mobile device. For app development, we used the Eclipse integrated development environment with Android plug-ins. We wrapped the mobile website version with the WebView object in Android. Simulators were downloaded to test and debug the applications. Results: The website automatically detects access from a mobile phone and redirects pages to fit the smaller screen. Because the amount of data stored on ALSoD is very large, the available information for display using smartphone access is deliberately restricted to improve usability. Visits to the website increased from 2231 to 2820, yielding a 26% increase from the pre-mobile to post-mobile period and an increase from 103 to 340 visits (230%) using mobile devices (including tablets). The smartphone app is currently available on BlackBerry and Android devices and will be available shortly on iOS as well. Conclusions: Further development of the ALSoD website has allowed access through smartphones and tablets, either through the website or directly through a mobile app, making genetic data stored on the database readily accessible to researchers and patients across multiple devices.

  • 9.
    Abrahamsson, Mattias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Elkvalitet på ett industrinät2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    En tung industri har oftast utrustning installerad som kan bidra till övertoner på ett elnät. Samtidigt är oftast elnäten starka inom dessa industrier vilket ska bidra till att reducera spänningsövertonerna som går att finna på respektive fas.Studien har arbetat med de villkor och föreskrifter som gäller både för en ansluten elanläggning till Vattenfalls elnät, men även hur en elkvalitetsmätning ska genomföras och vilka krav som behöver uppfyllas.Åkers Sweden AB, där studien har ägt rum, har induktionsugnar för smältning av metaller. Det förekommer olika tekniska lösningar samt 3 olika fabrikat. Mätningar har genomförts på samtliga dessa fabrikat för att kontrollera om någon av dessa urskiljer sig gentemot de övriga.Genomförda mätningar indikerar att spänningsövertoner förekommer men inte i sådan utsträckning att man inte uppfyller gällande regelverk. Det finns dock anledning till att fortsätta arbetet och utöka mätningarna till övriga objekt inom företaget som inte har ingått i denna studie.Företaget har ett effektabonnemang och en kontroll av detta med avseende på nu gällande effekt och förbrukning under 2015 har genomförts för att kunna ge förslag på eventuella förändringar. Eftersom företaget har ungefär samma produktionsvolym 2016 som 2015 finns anledning till att se över nu gällande avtal för att kunna erhålla en kostnadsreducering.En enkät har skickats ut till samtliga anställda inom företaget med syfte att både upplysa de anställda om vilka kvalitetsproblem som kan förekomma inom ett elnät, men även få en återkoppling på hur de anställda upplever nuvarande situation. Enkäten fick låg svarsfrekvens men svaren som inkom indikerade att de anställda upplever att företaget har en god elkvalitet.

  • 10.
    Abu-Hamam, Anas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Li, Haibo
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Georgakis, Apostolos
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Understanding Web Users Behaviour From A Web Video Camera2003Report (Other academic)
    Abstract [en]

    To develop a Real-Time system, which can capture and track the web user’s head motion. Based on the head motion information, the system should be able to identify whether the user is interested in the current homepage or not. A future system property would be to find out in which area of the homepage the user’s interest is moving.

  • 11.
    Adolfsson, Sebastian
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Expanding operation ranges using active flow control in Francis turbines2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report contains an investigation of fluid injection techniques used in the purpose of reducing deleterious flow effects occurring in the draft tube of Francis turbines when operating outside nominal load. There is a focus on implement ability at Jämtkrafts hydroelectric power plants and two power plants were investigated, located in series with each other named Lövhöjden and Ålviken. The only profitable scenario found with some degree of certainty was an increase in the operating range upwards to allow overload operation.

    Findings show that both air and water can be introduced in various locations to improve hydraulic efficiency around the turbine parts as well as reduce pressure pulsations in harmful operating regions. Investments in such systems have proven useful and profitable at several facilities with poorly adapted operating conditions. But due to losses in efficiency when operating injection systems, it turns out unprofitable in situations where it does not improve the operating range in a way that is resulting in increased annual or peak production.

  • 12. Aguilar, Luis T.
    et al.
    Boiko, Igor M.
    Fridman, Leonid M.
    Freidovich, Leonid B.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Generating oscillations in inertia wheel pendulum via two-relay controller2012In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 22, no 3, p. 318-330Article in journal (Refereed)
    Abstract [en]

    The problem of generating oscillations of the inertia wheel pendulum is considered. We combine exact feedback linearization with two-relay controller, tuned using frequency-domain tools, such as computing the locus of a perturbed relay system. Explicit expressions for the parameters of the controller in terms of the desired frequency and amplitude are derived. Sufficient conditions for orbital asymptotic stability of the closed-loop system are obtained with the help of the Poincare map. Performance is validated via experiments. The approach can be easily applied for a minimum phase system, provided the behavior of the states of the zero dynamics is of no concern. Copyright (C) 2011 John Wiley & Sons, Ltd.

  • 13.
    Aguilar, Luis T.
    et al.
    CITEDI, National Polytechnic Institute, Tijuana, BC, Mexico.
    Freidovich, Leonid
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Orlov, Yury
    CICESE Research Center, Ensenada, Baja California, Mexico.
    Merida, Jovan
    CITEDI, National Polytechnic Institute, Tijuana, BC, Mexico.
    Performance Analysis of Relay Feedback Position Regulators for Manipulators with Coulomb Friction2013In: Proc. 12th European Control Conference, NEW YORK, NY 10017 USA: IEEE , 2013, p. 3754-3759Conference paper (Refereed)
    Abstract [en]

    The purpose of the paper is to analyze the performance of several global position regulators for robot manipulators with Coulomb friction. All the controllers include a proportional-differential part and a switched part whereas the difference between the controllers is in the way of compensation of the gravitational forces. Stability analysis is also revisited within the nonsmooth Lyapunov function framework for the controllers with and without gravity pre-compensation. Performance issues of the proposed controllers are evaluated in an experimental study of a five degrees-of-freedom robot manipulator. In the experiments, we choose two criteria for performance analysis. In the first set of experiments, we set the same gains to all the controllers. In the second set of experiments, the gains of the controller were chosen such that the work done by the manipulator is similar.

  • 14.
    Al-Alosi, Muhammed
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Framtidsmöjligheter med 5G mobilnät2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report introduces various mobile network technologies, 1G to 5G. Focus is on the future 5G mobile networks, how it works and what opportunities will come with it. The report also covers the base stations that will be used in the future mobile network, with a brief description of the terminal in 5G network and the services that will be available with it. The protocol stack in 5G network is also covered. Moreover the report presents the Wi-Fi 802.11u standard that will be a part of the future mobile network. We can also read about how the 5G network will solve certain problems that are related to today's networks technologies. Finally, the report describes different access technologies that are used in the telecommunications systems.

  • 15.
    Algers, Björn
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stereo Camera Calibration Accuracy in Real-time Car Angles Estimation for Vision Driver Assistance and Autonomous Driving2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The automotive safety company Veoneer are producers of high end driver visual assistance systems, but the knowledge about the absolute accuracy of their dynamic calibration algorithms that estimate the vehicle’s orientation is limited.

    In this thesis, a novel measurement system is proposed to be used in gathering reference data of a vehicle’s orientation as it is in motion, more specifically the pitch and roll angle of the vehicle. Focus has been to estimate how the uncertainty of the measurement system is affected by errors introduced during its construction, and to evaluate its potential in being a viable tool in gathering reference data for algorithm performance evaluation.

    The system consisted of three laser distance sensors mounted on the body of the vehicle, and a range of data acquisition sequences with different perturbations were performed by driving along a stretch of road in Linköping with weights loaded in the vehicle. The reference data were compared to camera system data where the bias of the calculated angles were estimated, along with the dynamic behaviour of the camera system algorithms. The experimental results showed that the accuracy of the system exceeded 0.1 degrees for both pitch and roll, but no conclusions about the bias of the algorithms could be drawn as there were systematic errors present in the measurements.

  • 16.
    Ali-Eldin, Ahmed
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Capacity Scaling for Elastic Compute Clouds2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    AbstractCloud computing is a computing model that allows better management, higher utiliza-tion and reduced operating costs for datacenters while providing on demand resourceprovisioning for different customers. Data centers are often enormous in size andcomplexity. In order to fully realize the cloud computing model, efficient cloud man-agement software systems that can deal with the datacenter size and complexity needto be designed and built.This thesis studies automated cloud elasticity management, one of the main andcrucial datacenter management capabilities. Elasticity can be defined as the abilityof cloud infrastructures to rapidly change the amount of resources allocated to anapplication in the cloud according to its demand. This work introduces algorithms,techniques and tools that a cloud provider can use to automate dynamic resource pro-visioning allowing the provider to better manage the datacenter resources. We designtwo automated elasticity algorithms for cloud infrastructures that predict the futureload for an application running on the cloud. It is assumed that a request is either ser-viced or dropped after one time unit, that all requests are homogeneous and that it takesone time unit to add or remove resources. We discuss the different design approachesfor elasticity controllers and evaluate our algorithms using real workload traces. Wecompare the performance of our algorithms with a state-of-the-art controller. We ex-tend on the design of the best performing controller out of our two controllers anddrop the assumptions made during the first design. The controller is evaluated with aset of different real workloads.All controllers are designed using certain assumptions on the underlying systemmodel and operating conditions. This limits a controller’s performance if the modelor operating conditions change. With this as a starting point, we design a workloadanalysis and classification tool that assigns a workload to its most suitable elasticitycontroller out of a set of implemented controllers. The tool has two main components,an analyzer and a classifier. The analyzer analyzes a workload and feeds the analysisresults to the classifier. The classifier assigns a workload to the most suitable elasticitycontroller based on the workload characteristics and a set of predefined business levelobjectives. The tool is evaluated with a set of collected real workloads and a set ofgenerated synthetic workloads. Our evaluation results shows that the tool can help acloud provider to improve the QoS provided to the customers.

  • 17.
    Ali-Eldin, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    El-Ansary, Sameh
    Nile University.
    Optimizing Replica Placement in Peer-Assisted Cloud Stores2011Conference paper (Refereed)
    Abstract [en]

    Peer-assisted cloud storage systems use the unutilizedresources of the clients subscribed to a storage cloudto offload the servers of the cloud. The provider distributesdata replicas on the clients instead of replicating on the localinfrastructure. These replicas allow the provider to providea highly available, reliable and cheap service at a reducedcost. In this work we introduce NileStore, a protocol forreplication management in peer-assisted cloud storage. Theprotocol converts the replica placement problem into a lineartask assignment problem. We design five utility functionsto optimize placement taking into account the bandwidth,free storage and the size of data in need of replication oneach peer. The problem is solved using a suboptimal greedyoptimization algorithm. We show our simulation results usingthe different utilities under realistic network conditions. Ourresults show that using our approach offloads the cloud serversby about 90% compared to a random placement algorithmwhile consuming 98.5% less resources compared to a normalstorage cloud.

  • 18.
    Ali-Eldin, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    El-Ansary, Sameh
    Nile University.
    Replica Placement in Peer-Assisted Clouds: An Economic Approach2011In: Lecture Notes in Computer Science / [ed] Pascal Felber, Romain Rouvoy, Springer, 2011, p. 208-213Conference paper (Refereed)
    Abstract [en]

    We introduce NileStore, a replica placement algorithm based on an economical model for use in Peer-assisted cloud storage. The algorithm uses storage and bandwidth resources of peers to offload the cloud provider’s resources. We formulate the placement problem as a linear task assignment problem where the aim is to minimize time needed for file replicas to reach a certain desired threshold. Using simulation, We reduce the probability of a file being served from the provider’s servers by more than 97.5% under realistic network conditions.

  • 19.
    Ali-Eldin, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Ilyushkin, Alexey
    Ghit, Bogdan
    Herbst, Nikolas Roman
    Papadopoulos, Alessandro
    Losup, Alexandru
    Which Cloud Auto-Scaler Should I Use for my Application?: Benchmarking Auto-Scaling Algorithms2016In: PROCEEDINGS OF THE 2016 ACM/SPEC INTERNATIONAL CONFERENCE ON PERFORMANCE ENGINEERING (ICPE'16), Association for Computing Machinery (ACM), 2016, p. 131-132Conference paper (Refereed)
  • 20.
    Ali-Eldin, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Kihl, Maria
    Lund University.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Elmroth, Erik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Analysis and characterization of a Video-on-Demand service workload2015In: Proceedings of the 6th ACM Multimedia Systems Conference, MMSys 2015, ACM Digital Library, 2015, p. 189-200Conference paper (Refereed)
    Abstract [en]

    Video-on-Demand (VoD) and video sharing services accountfor a large percentage of the total downstream Internet traf-fic. In order to provide a better understanding of the loadon these services, we analyze and model a workload tracefrom a VoD service provided by a major Swedish TV broad-caster. The trace contains over half a million requests gener-ated by more than 20000 unique users. Among other things,we study the request arrival rate, the inter-arrival time, thespikes in the workload, the video popularity distribution, thestreaming bit-rate distribution and the video duration distri-bution. Our results show that the user and the session ar-rival rates for the TV4 workload does not follow a Poissonprocess. The arrival rate distribution is modeled using a log-normal distribution while the inter-arrival time distributionis modeled using a stretched exponential distribution. Weobserve the “impatient user” behavior where users abandonstreaming sessions after minutes or even seconds of startingthem. Both very popular videos and non-popular videos areparticularly affected by impatient users. We investigate ifthis behavior is an invariant for VoD workloads.

  • 21.
    Ali-Eldin, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Rezaie, Ali
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Mehta, Amardeep
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Razroev, Stanislav
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Sjöstedt-de Luna, Sara
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Seleznjev, Oleg
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Elmroth, Erik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    How will your workload look like in 6 years?: Analyzing Wikimedia's workload2014In: Proceedings of the 2014 IEEE International Conference on Cloud Engineering (IC2E 2014) / [ed] Lisa O’Conner, IEEE Computer Society, 2014, p. 349-354Conference paper (Refereed)
    Abstract [en]

    Accurate understanding of workloads is key to efficient cloud resource management as well as to the design of large-scale applications. We analyze and model the workload of Wikipedia, one of the world's largest web sites. With descriptive statistics, time-series analysis, and polynomial splines, we study the trend and seasonality of the workload, its evolution over the years, and also investigate patterns in page popularity. Our results indicate that the workload is highly predictable with a strong seasonality. Our short term prediction algorithm is able to predict the workload with a Mean Absolute Percentage Error of around 2%.

  • 22.
    Ali-Eldin, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Seleznjev, Oleg
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Sjöstedt-de Luna, Sara
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Elmroth, Erik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Measuring cloud workload burstiness2014In: 2014 IEEE/ACM 7th International Conference on Utility and Cloud Computing (UCC), IEEE conference proceedings, 2014, p. 566-572Conference paper (Refereed)
    Abstract [en]

    Workload burstiness and spikes are among the main reasons for service disruptions and decrease in the Quality-of-Service (QoS) of online services. They are hurdles that complicate autonomic resource management of datacenters. In this paper, we review the state-of-the-art in online identification of workload spikes and quantifying burstiness. The applicability of some of the proposed techniques is examined for Cloud systems where various workloads are co-hosted on the same platform. We discuss Sample Entropy (SampEn), a measure used in biomedical signal analysis, as a potential measure for burstiness. A modification to the original measure is introduced to make it more suitable for Cloud workloads.

  • 23.
    Ali-Eldin, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Elmroth, Erik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Kihl, Maria
    Lund University.
    WAC: A Workload analysis and classification tool for automatic selection of cloud auto-scaling methodsManuscript (preprint) (Other academic)
    Abstract [en]

    Autoscaling algorithms for elastic cloud infrastructures dynami-cally change the amount of resources allocated to a service ac-cording to the current and predicted future load. Since there areno perfect predictors, no single elasticity algorithm is suitable foraccurate predictions of all workloads. To improve the quality ofworkload predictions and increase the Quality-of-Service (QoS)guarantees of a cloud service, multiple autoscalers suitable for dif-ferent workload classes need to be used. In this work, we intro-duce WAC, a Workload Analysis and Classification tool that as-signs workloads to the most suitable elasticity autoscaler out of aset of pre-deployed autoscalers. The workload assignment is basedon the workload characteristics and a set of user-defined Business-Level-Objectives (BLO). We describe the tool design and its maincomponents. We implement WAC and evaluate its precision us-ing various workloads, BLO combinations and state-of-the-art au-toscalers. Our experiments show that, when the classifier is tunedcarefully, WAC assigns between 87% and 98.3% of the workloadsto the most suitable elasticity autoscaler.

  • 24.
    Ali-Eldin, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Elmroth, Erik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Kihl, Maria
    Department of Electrical and Information Technology, Lund University, Lund, Sweden.
    Workload Classification for Efficient Auto-Scaling of Cloud Resources2013Manuscript (preprint) (Other academic)
    Abstract [en]

    Elasticity algorithms for cloud infrastructures dynamically change the amount of resources allocated to a running service according to the current and predicted future load. Since there is no perfect predictor, and since different applications’ workloads have different characteristics, no single elasticity algorithm is suitable for future predictions for all workloads. In this work, we introduceWAC, aWorkload Analysis and Classification tool that analyzes workloads and assigns them to the most suitable elasticity controllers based on the workloads’ characteristics and a set of business level objectives.

    WAC has two main components, the analyzer and the classifier. The analyzer analyzes workloads to extract some of the features used by the classifier, namely, workloads’ autocorrelations and sample entropies which measure the periodicity and the burstiness of the workloads respectively. These two features are used with the business level objectives by the clas-sifier as the features used to assign workloads to elasticity controllers. We start by analyzing 14 real workloads available from different applications. In addition, a set of 55 workloads is generated to test WAC on more workload configurations. We implement four state of the art elasticity algorithms. The controllers are the classes to which the classifier assigns workloads. We use a K nearest neighbors classifier and experiment with different workload combinations as training and test sets. Our experi-ments show that, when the classifier is tuned carefully, WAC correctly classifies between 92% and 98.3% of the workloads to the most suitable elasticity controller.

  • 25.
    Ali-Eldin Hassan, Ahmed
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Workload characterization, controller design and performance evaluation for cloud capacity autoscaling2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis studies cloud capacity auto-scaling, or how to provision and release re-sources to a service running in the cloud based on its actual demand using an auto-matic controller. As the performance of server systems depends on the system design,the system implementation, and the workloads the system is subjected to, we focuson these aspects with respect to designing auto-scaling algorithms. Towards this goal,we design and implement two auto-scaling algorithms for cloud infrastructures. Thealgorithms predict the future load for an application running in the cloud. We discussthe different approaches to designing an auto-scaler combining reactive and proactivecontrol methods, and to be able to handle long running requests, e.g., tasks runningfor longer than the actuation interval, in a cloud. We compare the performance ofour algorithms with state-of-the-art auto-scalers and evaluate the controllers’ perfor-mance with a set of workloads. As any controller is designed with an assumptionon the operating conditions and system dynamics, the performance of an auto-scalervaries with different workloads.In order to better understand the workload dynamics and evolution, we analyze a6-years long workload trace of the sixth most popular Internet website. In addition,we analyze a workload from one of the largest Video-on-Demand streaming servicesin Sweden. We discuss the popularity of objects served by the two services, the spikesin the two workloads, and the invariants in the workloads. We also introduce, a mea-sure for the disorder in a workload, i.e., the amount of burstiness. The measure isbased on Sample Entropy, an empirical statistic used in biomedical signal processingto characterize biomedical signals. The introduced measure can be used to charac-terize the workloads based on their burstiness profiles. We compare our introducedmeasure with the literature on quantifying burstiness in a server workload, and showthe advantages of our introduced measure.To better understand the tradeoffs between using different auto-scalers with differ-ent workloads, we design a framework to compare auto-scalers and give probabilisticguarantees on the performance in worst-case scenarios. Using different evaluation cri-teria and more than 700 workload traces, we compare six state-of-the-art auto-scalersthat we believe represent the development of the field in the past 8 years. Knowingthat the auto-scalers’ performance depends on the workloads, we design a workloadanalysis and classification tool that assigns a workload to its most suitable elasticitycontroller out of a set of implemented controllers. The tool has two main components;an analyzer, and a classifier. The analyzer analyzes a workload and feeds the analysisresults to the classifier. The classifier assigns a workload to the most suitable elasticitycontroller based on the workload characteristics and a set of predefined business levelobjectives. The tool is evaluated with a set of collected real workloads, and a set ofgenerated synthetic workloads. Our evaluation results shows that the tool can help acloud provider to improve the QoS provided to the customers.

  • 26.
    Alstergren, Manne
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Development of a spectral and goniophotometric imagingmeasurement system for optical characterization of materials2014Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    In this thesis, a novel color measurement system has been developed and its performance evaluated.It is a modular spectral imaging goniophotometer that measures angle resolved spectralreflectance and transmittance of materials, e.g. textiles, papers, coated materials and flexibleelectronics. It is a highly flexible system that can, unlike most commercial systems, capturereflectance images of both high spectral and spatial resolution over a wide range of measurementgeometries.

    It is important that the system can produce geometrically correct images of the samples, as well ascapture spectral information with high accuracy, i.e. the system needs to be both geometricallyand photometrically calibrated. A line-scan spectral camera and a high accuracy translationstage provide 2D-scans of the sample, where imaged area, sample position and measurementgeometry is controlled by a high precision robotic arm. Assessment of spectral and spatialresolution, characterization of the light source and spectral accuracy of the camera are someof the evaluations carried out. Spectral accuracy, and thus color measurement accuracy, isevaluated with the color difference formula CIE ∆Eab. During these evaluations the system isable to measure colors at ∆Eab < 14 and ∆Eab < 30 for a matte and glossy sample respectively,both of which are standard color calibration samples. These results show large color differencesthat are most likely caused by the low signal-to-noise ratio for short wavelengths due to thelight source. Finally, the system’s angle resolved measurement capability is demonstrated bymeasurements of goniochromatic samples whose color shifts with the viewing angle. The changein color is successfully captured for viewing angles in the range of 0 to 45 degrees from the surfacenormal.

  • 27.
    Anani, Adi
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    M-learning in review: Technology, standard and evaluation2008In: Journal of Communication and Computer, ISSN 1548-7709, Vol. 5, no 11, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Nowadays E-learning as a form of learning depending on networks and computer devices has been expanding by leaps and bounds. As a special kind of E-learning, M-learning (mobile learning) aims at the use of mobile devices anywhere at anytime by anybody. In this paper, the technologies to develop a M-learning system is deeply analyzed according to the layer model at first. Secondly, from the view of application, the standardization in M-learning is researched in order to accelerate the development and popularization of M-learning. Finally, quality estimation of M-learning system is discussed from the view of QoE (quality of experiences). The experience form end-user is the sole effective norm to judge the result of M-learning technology. It is no doubt that technologies, standardization and evaluation will play very important parts in the course of M-learning development.

  • 28.
    Anani, Adi
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Zhang, Deng-yin
    Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, China.
    Li, Haibo
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    QoS-guaranteed packet scheduling in wireless networks2009In: The Journal of China Universities of Posts and Telecommunications, ISSN 1005-8885, Vol. 16, no 2, p. 63-67Article in journal (Refereed)
    Abstract [en]

    To guarantee the quality of service (QoS) of a wireless network, a new packet scheduling algorithm using cross-layer design technique is proposed in this article. First, the demand of packet scheduling for multimedia transmission in wireless networks and the deficiency of the existing packet scheduling algorithms are analyzed. Then the model of the QoS-guaranteed packet scheduling (QPS) algorithm of high speed downlink packet access (HSDPA) and the cost function of packet transmission are designed. The calculation method of packet delay time for wireless channels is expounded in detail, and complete steps to realize the QPS algorithm are also given. The simulation results show that the QPS algorithm that provides the scheduling sequence of packets with calculated values can effectively improve the performance of delay and throughput.

  • 29.
    Anani, Sani
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Hand Reader – A hand Geometry Based Personal Verification System2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report presents my bachelor thesis performed at the Department of Applied Physics and Electronics at UmeåUniversity. The Digital Media Lab was the assigner, supervising and assisting me during the project.

     

    A simple and smart system to verify a person’s identity using hand geometry as a biometrical identity is developed. The system should tolerate some deviation in hand placement and will not use pins or pegs. A complete system, hardware and software, is delivered. A webcam based hand-scanner is constructed and designed to operate on a PC utilizing Matlab for image processing.

  • 30. Andersson, Alina
    et al.
    Robertsson, Anders
    Shiriaev, Anton S.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Norwegian Univ Sci & Technol, Dept Engn Cybernet, Trondheim, Norway.
    Freidovich, Leonid B.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Johansson, Rolf
    Robustness of the Moore-Greitzer Compressor Model's Surge Subsystem with New Dynamic Output Feedback Controllers2014In: IFAC PAPERSONLINE, Elsevier, 2014, Vol. 47, no 3, p. 3690-3695Conference paper (Refereed)
    Abstract [en]

    This work presents an extension of a design procedure for dynamic output feedback design for systems with nonlinearities satisfying quadratic constraints. In this work we used an axial gas compressor model described by the 3-state Moore-Greitzer compressor model (MG) that has some challenges for output feedback control design (Planovsky and Nikolaev 1990), (Rubanova 2013). The more general constraints for the investigation of the robustness with respect to parametric uncertainties and measurement noise are shown.

  • 31.
    Andersson, Martin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Isolerad DC/DC-omvandlare2011Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Cross Control is a company that produces embedded computer solutions. A computer’ s normal input voltage is 18-30 VDC and consumes at the most 50W. The computers are sold to several different customers, who use them in anything from forwarders to trains. In separate vehicles the supply dc current varies from one vehicle to another. This creates needs to convert the voltage to a level that the computers can handle. Such a device is called a DC/DC-converter. Voltage conversion can be performed in different ways, either through linear regulation, or by using switching technology. The goal of our work is to design a DC/DC-converter that meets the requirements raised in cooperation with CrossControl. To achieve sufficient efficiency, and since galvanic isolation between input and output voltage is a requirement, the converter is based on a switched flyback solution. The transformer is the most important component for the converter function. Therefore, a large part of the project was focused on selecting a suitable one. The result is a prototype that is capable of regulating the output voltage to 24VDC for the entire input range, and can handle a load of 50W. The effectiveness ended at 80% which is 5% below target. To improve the prototype it is necessary to protect it from voltage outside input range. To achieve 85% efficiency one could redesign the snubber network.

  • 32.
    Andersson, Sebastian
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Centralised Distribution Grid Energy Storage Systems: Placement and Utilisation for Grid Expansion Deferment2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Following an ongoing change towards an increasingly renewable power generation system Swedish grid operators are facing several challenges in coming years. As authorities plan for the decommissioning of nuclear power an increased reliance on de-centralised energy sources such as photo-voltaic distributed generation (PVDG) is expected. A technology observed in some cases to accompany local power quality issues severe enough to impose grid expansion measures from distribution system operators (DSOs). Considering a combination of an indicative utilisation inefficiency of classical grid expansion measures and a recent year maturing of various energy storage technologies, this report sets out to evaluate the possibility of utilising centralised energy storage systems (ESSs) for deferment of classical grid expansion measures.

    For the purpose of identifying the most prominent problem scenarios of modern production- and consumption behaviours as well as the possible solutions offered by centralised ESSs, a literature review of journal articles and technical reports was conducted in combination with a case-study of an existing urban grid operated by Umeå Energi Elnät AB (UEEN). The work regarding ESSs is directed with specific focus towards evaluating which ESS services can potentially facilitate grid expansion deferment and what ESS placement is advisable for efficient utilisation. Assessing possible grid safety implications, potential for peak load shaving and the presently most suitable energy storage technology was also within the scope of the study.

    The literature review reveals PVDG induced feeder line over-voltage and transformer overload the most likely and previously observed implications imposing grid expansion measures. The former more prominent in elongated, typically rural, grids and the latter in more densely populated urban grids. For deferment of over-voltage related grid expansion measures a centralised ESS can be utilised for voltage support provided placement is made close to the affected grid section, presumably far out the affected feeder line. This result is coherent throughout the reviewed literature and is supported by the results of the case-study. Distribution transformer overload and its imposed grid expansion measures can be deferred through load re-allocation and peak load shaving, two services proven achievable by centralised ESSs and the capacity for which increases if ESS placement is made closer the distribution transformer.

    Provided present regulatory and standards are adhered to upon installation, significant negative impact of centralised ESSs on distribution grid safety can be avoided. Most energy storage technologies, including battery based energy storage technologies indicated from the literature review providing the most suitable characteristics for use in centralised distribution grid ESSs, utilise well established systems for grid connection hence no presently unsolvable grid safety implications are identified. Technical reports of real applications of centralised ESSs reinforce this argument as successful implementation without ESS caused grid safety implications have been achieved in the Swedish distribution grid in the past.

  • 33.
    Andreasson, Simon
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Datainsamling röntgen2011Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 34.
    Appelblad, André
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Development of a Temperature Controlled Cell for Surface Enhanced Raman Spectroscopy for in situ Detection of Gases2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This work describes a master’s thesis in engineering physics at Umeå University carried out during the spring semester of 2014. In the thesis the student has constructed and tested a temperature controlled cell for cooling/heating of surface-enhanced-Raman-spectroscopy (SERS) substrates for rapid detection of volatile substances. The thesis was carried out at the Swedish Defence Research Agency (FOI) in Umeå, Sweden. A Linkam Scientific Instruments TS1500 cell was equipped with a Peltier element for cooling/heating and a thermistor temperature sensor. A control system was constructed, based on an Arduino Uno microcontroller board and a pulse-width-modulated (PWM) H-bridge motor driver to control the Peltier element using a proportional-integral (PI) control algorithm. The temperature controlled cell was able to regulate the temperature of a SERS substrate within -15 to +110 °C and maintain the temperature over prolonged periods at ±0.22 °C of the set point temperature. Gas phase of 2-chloro-2-(difluoromethoxy)-1,1,1-trifluoro-ethane (isoflurane) was flowed through the cell and SERS spectra were collected at different temperatures and concentrations. This test showed that the signal is increased when the substrate is cooled and reversibly decreased when the substrate was heated.

    Keywords: temperature control, Raman scattering, surface enhanced Raman spectroscopy SERS, SERS substrate, volatile substances, Peltier module, thermistor, PWM, H-bridge, PI(D) control.

  • 35.
    Aranovskiy, Stanislav
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. The Department of Control Systems and Informatics, National Research University of Information Technologies, Mechanics and Optics, Saint-Petersburg, Russia.
    Freidovich, Leonid
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Adaptive compensation of disturbances formed as sums of sinusoidal signals with application to an active vibration control benchmark2013In: European Journal of Control, ISSN 0947-3580, E-ISSN 1435-5671, Vol. 19, no 4, p. 253-265Article in journal (Refereed)
    Abstract [en]

    An intuitive solution for the problem of adaptive attenuation of a disturbance formed as a finite sum of unknown sinusoidal signals is proposed for an internally stable discrete-time plant. The compensator is formed as a weighted sum of stable filters. An identification-based procedure for adaptive tuning of the coefficients is proposed for the case of unknown disturbance. We also propose a time-invariant compensator that provides perfect attenuation of a disturbance for the case when a model identification error is sufficiently small and disturbance frequencies are known. The technique is applied to a case study on a challenging benchmark example in the field of active vibration control. Attenuation of a disturbance formed as a sum of up to three sinusoidal signals with unknown/time-varying frequencies is demonstrated via simulation and experimental studies. (C) 2013 European Control Association. Published by Elsevier Ltd. All rights reserved.

  • 36.
    Aranovskiy, Stanislav
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Department of Control Systems and Informatics, ITMO University.
    Freidovich, Leonid
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nikiforova, LV
    Department of Control Systems and Informatics, ITMO University.
    Losenkov, AA
    Department of Control Systems and Informatics, ITMO University.
    МОДЕЛИРОВАНИЕ И ИДЕНТИФИКАЦИЯДИНАМИКИ ЗОЛОТНИКОВОГО ГИДРОРАСПРЕДЕЛИТЕЛЯ: ЧАСТЬ I. МОДЕЛИРОВАНИЕ / ЧАСТЬ II. ИДЕНТИФИКАЦИЯ2013In: Scientific and Technical Journal «Priborostroenie», ISSN 0021-3454, Vol. 56, no 4, p. 253-265Article in journal (Refereed)
    Abstract [en]

    MODELING AND IDENTIFICATION OF DYNAMICS OF A HYDRAULIC ACTUATOR WITH A SPOOL VALVE. PART I. MODELING

    Approaches to the problem of modeling of hydraulic actuator are considered. A model for the spool dynamics consisting of a linear block and two static nonlinear subsystems is presented.

    MODELING AND IDENTIFICATION OF DYNAMICS OF A HYDRAULIC ACTUATOR WITH A SPOOL VALVE. PART II: IDENTIFICATION

    A method for identification of dynamic model parameters is suggested for the case when only pressures in the hydraulic cylinders but not the valve displacements are measured. The approach is verified by presented results of experiments.

  • 37.
    Aranovskiy, Stanislav
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Department of Control Systems and Informatics, ITMO University, Saint-Petersburg, Russia.
    Losenkov, Andrei
    Department of Control Systems and Informatics, ITMO University, Saint-Petersburg, Russia.
    Vazquez, Carlos
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Position control of an industrial hydraulic system with a pressure compensator2014In: Proceedings of the 2014 22nd Mediterranean Conference of Control and Automation (MED 2014), Institute of Electrical and Electronics Engineers (IEEE), 2014, p. 1329-1334Conference paper (Refereed)
    Abstract [en]

    A problem of position control of a forestry crane is studied. Several features of industrial hydraulic systems are pointed out, namely a nonlinearity of a valve and a pressure compensator. A novel model of a hydraulic system with the pressure compensator is presented and analyzed, a static nonlinearity inversion and a velocity feedforward control term are introduced. Real-time experiments with controllers which use only position measurements illustrate utility of these terms.

  • 38. Aranovskiy, Stanislav
    et al.
    Vazquez, Carlos
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Control of a single-link mobile hydraulic actuator with a pressure compensator2014In: 2014 IEEE Conference on Control Applications (CCA), 2014, p. 216-221Conference paper (Refereed)
    Abstract [en]

    A problem of position control of a single-link hydraulic drive, including model uncertainties and disturbances, is studied. Main properties of mobile hydraulic systems are taking into account, namely a nonlinearity of a valve and a pressure compensator. A discontinuous control law coupled with a static nonlinearity inversion and a feed-forward term of velocity is proposed. Besides, a novel model with pressure compensator is presented and the closed-loop stability analysis is provided. Results of experiments carried out on a forestry crane confirm the efficacy of the proposed approach.

  • 39.
    Aronsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    NEXT-analys av kablage för Ethernetkommunikation i påfrestande miljöer2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 40.
    Asaro, Peter M.
    Umeå University, Faculty of Arts, Humlab.
    A Body to Kick, but Still No Soul to Damn: Legal Perspectives on Robotics2012In: Robot Ethics: The Ethical and Social Implications of Robotics / [ed] Patrick Lin, Keith Abney and George A. Bekey, CAMBRIDGE: MIT Press, 2012, p. 169-186Chapter in book (Other academic)
  • 41.
    Aspholm, Mattias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Utredning av frekvensomriktaresinverkan på sin närmiljö2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Fokus läggs mer och mer på hur olinjära laster påverkar spänningsgodheten pånätet. Ledorden är att ”du skall icke sabotera din grannes spänningskvalitet!”.Detta gillar nätbolagen och allmänheten men i vissa delar av nätet är det inte lika nödvändigt att hålla så hårt på elkvaliteten. Industrier har ofta anläggningar som är avskilda öar från det elektriska fastlandet. Därför gjordes mätningar på befintlig anläggning med stor del frekvensomriktardrift för att kunna jämföra med simuleringar från dimensioneringsprogram och slutligen utifrån resultatet dra slutsatser om hur man ska utveckla tankesättet vid dimensionering av frekvensomriktare för att göra den mer kostnadseffektiv.

  • 42.
    Ataniyazov, Ataniyaz
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Transformatorers tekniska och ekonomiska livslängd2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is performed at WSP in Skellefteå, specializing in Rönnskär Education in Skelleftehamn.

    Rönnskär’s construction began by Boliden AB in 1928 and it was ready for production in 1930. It produces copper, lead, zinc clinker, gold and silver. In 2010 Rönnskär produced 190000 tons of copper and in 2013 it produced 206 000 tons. Current number of employees is 866.

    The electricity supply of the industrial area of Rönnskär is in very high priority and transformer failures leading to lengthy downtime and expensive repairs. Power transformers must have high operational availability transformers which purchases for production must be robust.

    This is a comparative study between dry type and oil insulated transformers which summarized in form of recommendation for the future purchases.

    The work will highlight the parameters of operational availability and operational safety make calculations for rated short time currents and losses in transformers based on manufacturers data.

    The aim of this thesis is to compare various parameters of dry and oil immersed transformers from different manufacturers summarized in a comparison table according to the apparent power and voltage which shows the difference between various types of transformers.

    This work is primarily based on the theory of transformers and at the same time on continuous dialogue with the client and the transformer manufacturer.

    The recommendations should be viewed as a preliminary study, a deeper analysis and further investigation is required when purchasing transformers, depending on the circumstances and the conditions.

    An economic analysis has not been performed because of the limited information.

    Keyword for this study is AOS: Availability and Operational Safety.

  • 43.
    Ataniyazov, Ataniyaz
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Transformatorers tekniska och ekonomiska livslängd: En jämförande studie mellan torrisolerade och oljeisolerade transformatorer som resulterar i en rekommendation för framtida inköp2014Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [en]

    This thesis is performed at WSP in Skellefteå, specializing in Rönnskär Education in Skelleftehamn.

    Rönnskär’s construction began by Boliden AB in 1928 and it was ready for production in 1930. It produces copper, lead, zinc clinker, gold and silver. In 2010 Rönnskär produced 190000 tons of copper and in 2013 it produced 206 000 tons. Current number of employees is 866.

    The electricity supply of the industrial area of Rönnskär is in very high priority and transformer failures leading to lengthy downtime and expensive repairs. Power transformers must have high operational availability transformers which purchases for production must be robust.

    This is a comparative study between dry type and oil insulated transformers which summarized in form of recommendation for the future purchases.

    The work will highlight the parameters of operational availability and operational safety make calculations for rated short time currents and losses in transformers based on manufacturers data.

    The aim of this thesis is to compare various parameters of dry and oil immersed transformers from different manufacturers summarized in a comparison table according to the apparent power and voltage which shows the difference between various types of transformers.

    This work is primarily based on the theory of transformers and at the same time on continuous dialogue with the client and the transformer manufacturer.

    The recommendations should be viewed as a preliminary study, a deeper analysis and further investigation is required when purchasing transformers, depending on the circumstances and the conditions.

    An economic analysis has not been performed because of the limited information.

    Keyword for this study is AOS: Availability and Operational Safety

  • 44.
    Augustian, Midhumol
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    ur Réhman, Shafiq
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sandvig, Axel
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience. Norwegian University of Science and Technology (NTNU), Norway.
    Kotikawatte, Thivra
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
    Yongcui, Mi
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Evensmoen, Hallvard Røe
    Norwegian University of Science and Technology (NTNU), Norway.
    EEG Analysis from Motor Imagery to Control a Forestry Crane2018In: Intelligent Human Systems Integration (IHSI 2018) / [ed] Karwowski, Waldemar, Ahram, Tareq, 2018, Vol. 722, p. 281-286Conference paper (Refereed)
    Abstract [en]

    Brain-computer interface (BCI) systems can provide people with ability to communicate and control real world systems using neural activities. Therefore, it makes sense to develop an assistive framework for command and control of a future robotic system which can assist the human robot collaboration. In this paper, we have employed electroencephalographic (EEG) signals recorded by electrodes placed over the scalp. The human-hand movement based motor imagery mentalization is used to collect brain signals over the motor cortex area. The collected µ-wave (8–13 Hz) EEG signals were analyzed with event-related desynchronization/synchronization (ERD/ERS) quantification to extract a threshold between hand grip and release movement and this information can be used to control forestry crane grasping and release functionality. The experiment was performed with four healthy persons to demonstrate the proof-of concept BCI system. From this study, it is demonstrated that the proposed method has potential to assist the manual operation of crane operators performing advanced task with heavy cognitive work load.

  • 45.
    Bagheri, Shahriar
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Modeling, Simulation and Control System Design for Civil Unmanned Aerial Vehicle (UAV)2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Unmanned aerial systems have been widely used for variety of civilian applications over the past few years. Some of these applications require accurate guidance and control. Consequently, Unmanned Aerial Vehicle (UAV) guidance and control attracted many researchers in both control theory and aerospace engineering. Flying wings, as a particular type of UAV, are considered to have one of the most efficient aerodynamic structures. It is however difficult to design robust controller for such systems. This is due to the fact that flying wings are highly sensitive to control inputs.

    The focus of this thesis is on modeling and control design for a UAV system. The platform understudy is a flying wing developed by SmartPlanes Co. located in Skellefteå, Sweden. This UAV is particularly used for topological mapping and aerial photography.

    The novel approach suggested in this thesis is to use two controllers in sequence. More precisely, Linear Quadratic Regulator (LQR) is suggested to provide robust stability, and Proportional, Integral, Derivative (PID) controller is suggested to provide reference signal regulation. The idea behind this approach is that with LQR in the loop, the system becomes more stable and less sensitive to control signals. Thus, PID controller has an easier task to do, and is only used to provide the required transient response.

    The closed-loop system containing the developed controller and a UAV non-linear dynamic model was simulated in Simulink. Simulated controller was then tested for stability and robustness with respect to some parametric uncertainty. Obtained results revealed that the LQR successfully managed to provide robust stability, and PID provided reference signal regulation.

  • 46. Bagheri, Shahriar
    et al.
    Jafarov, Tural
    Freidovich, Leonid
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sepehri, Nariman
    Beneficially Combining LQR and PID to Control Longitudinal Dynamics of a SmartFly UAV2016In: 7TH IEEE ANNUAL INFORMATION TECHNOLOGY, ELECTRONICS & MOBILE COMMUNICATION CONFERENCE IEEE IEMCON-2016 / [ed] Chakrabarti S, Saha HN, 2016Conference paper (Refereed)
    Abstract [en]

    The problem of control system design for longitudinal axis of a small-size flying wing is studied. The new controller proposed is comprised of two controllers working together to provide robust stability and step reference tracking for the nonlinear dynamics of SmartFly UAV. More precisely, Linear Quadratic Regulator (LQR) is used together with Proportional, Integral, Derivative (PID) controller. The inspiration comes from the fact that each of the mentioned controllers have advantages and disadvantages that cannot be neglected. LQR, as an optimal in terms of energy-like regulator, provides robust stability with a minimized energy-like performance index. It is also very computationally efficient. But, when it comes to the transient of particular output, LQR is not the best solution. On the other hand, PID has the advantage of a possibility to tune the gains for optimized transient behavior, especially for well-behaving plants. Furthermore, PID controller is particularly useful for tracking problems. However, PID is often not robust (in terms of parameter uncertainties) and it is also difficult to tune PID parameters for unstable systems. By differentiating between system stability and performance in the controller design process, it is possible to benefit from both controllers, using them along side together in one system. Functionality of this method was verified through computer simulation in MATLAB/SIMULINK for a nonlinear model of SmartFly UAV. Closed-loop system performance was evaluated in terms of robustness and step reference tracking.

  • 47.
    Barth, Ruud
    et al.
    Greenhouse Horticulture, Wageningen University & Research Center.
    Baur, Jörg
    Institute of Applied Mechanics, Technische Universität München.
    Buschmann, Thomas
    Institute of Applied Mechanics, Technische Universität München.
    Edan, Yael
    Department of Industrial Engineering and Management, Ben-Gurion University of the Negev.
    Hellström, Thomas
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Nguyen, Thanh
    KU Leuven, Department of Biosystems.
    Ringdahl, Ola
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Saeys, Wouter
    KU Leuven, Department of Biosystems.
    Salinas, Carlota
    Centre for Automation and Robotics UPM-CSIC.
    Vitzrabin, Efi
    Department of Industrial Engineering and Management, Ben-Gurion University of the Negev.
    Using ROS for agricultural robotics: design considerations and experiences2014In: RHEA-2014 / [ed] Pablo Gonzalez-de-Santos and Angela Ribeiro, 2014, p. 509-518Conference paper (Refereed)
    Abstract [en]

    We report on experiences of using the ROS middleware for developmentof agricultural robots. We describe software related design considerations for all maincomponents in developed subsystems as well as drawbacks and advantages with thechosen approaches. This work was partly funded by the European Commission(CROPS GA no 246252).

  • 48. Basavoju, Srinivas
    et al.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Velaga, Sitaram P
    Pharmaceutical salts of fluoroquinolone antibacterial drugs with acesulfame sweetener2012In: Molecular Crystals and Liquid Crystals, ISSN 1542-1406, Vol. 562, no 1, p. 254-264Article in journal (Refereed)
    Abstract [en]

    Novel organic salts of norfloxacin and ciprofloxacin with artificial sweeteners such as saccharin and acesulfame were prepared. The two salts 1 and 2 were characterized by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). Finally, the crystal structures were solved by single crystal X-ray diffraction data and the structures were analyzed in terms of supramolecular synthons. In norfloxacin acesulfamate 1, two norfloxacin cations and two acesulfame anions form an eight membered cyclic tetramer supramolecular synthon. The salt, ciprofloxacin acesulfamate 2, has a similar structure as salt 1. This study contributes the importance of crystal engineering and supramolecular chemistry to the pharmaceutical applications in terms of interactions and structural correlations in the design of new solid phases. Supplemental materials are available for this article. Go to the publisher's online edition of Molecular Crystals and Liquid Crystals to view the free supplemental file.

  • 49.
    Baskar, Jayalakshmi
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Lindgren, Helena
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Human-Agent Dialogues on Health Topics - An Evaluation Study2015In: Highlights of practical applications of agents, multi-agent systems, and sustainability: The PAAMS Collection, PAAMS 2015, 2015, p. 28-39Conference paper (Refereed)
    Abstract [en]

    A common conversation between an older adult and a nurse about health-related issues includes topics such as troubles with sleep, reasons for walking around nighttime, pain conditions, etc. This dialogue emerges from the participating human's lines of thinking, their roles, needs and motives, while switching between topics as the dialogue unfolds. This paper presents a dialogue system that enables a human to engage in a dialogue with a software agent to reason about health-related issues in a home environment. The purpose of this work is to conduct a pilot evaluation study of a prototype system for human-agent dialogues, which is built upon a set of semantic models and integrated in a web application designed for older adults. Focus of the study was to receive qualitative results regarding purpose and content of the agent-based dialogue system, and to evaluate a method for the agent to evaluate its behavior based on the human agent's perception of appropriateness of moves. The participants include five therapists and 11 older adults. The results show users' feedback on the purpose of dialogues and the appropriateness of dialogues presented to them during the interaction with the software agent.

  • 50.
    Behring, Sven
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kontaktpressningssystem: En studie av elsäkerhet2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    This work covers a broad analysis of the risks that could impact the achievement of electrical safety of electrical installations. The work includes both electrical equipment such as the installation of electrical equipment.The report illustrates the main technical characteristics of electrical connections greater than 10 mm2 and provides an introduction to the crimping systems for copper and aluminum conductors. In addition to that analyzes the factors that are important to assure the quality of an electrical connection throughout the value stream in terms of both materials such informations. Furthermore analyzed deeper the need for skills development of technicians and other staff.The different parts of this work are analyzed and presented, in theory to studies carried out both at Elpress AB and partly with the help of other scientific reports dealing with similar subjects. In addition, presents a survey that will help understanding the current perception of the electrical connections and cable crimping systems among end users. Various risks are analyzed in an FMEA analysis with respect to the different stages in the value stream.The project has shown that there is a need for changes in the regulations that deals with, among other things, permission for electrical staff.

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