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  • 1.
    Aaro, Fredrik
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    En intuitiv & lättillgänglig flyktmask för gruvmiljö2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    I have always lived around mines and around people work­ing with mines. They are a natural part of my life and, inev­itably, a great interest of mine. When time came to make a decision for a degree project, focusing on the mine context felt as natural as breathing.

    In LKABs underground mines, safety in fire accidents is a great priority. Of outmost importance for the escape is to have a personal gas filter for filtration of smoke and/or gas. My design project resulted in a concept which is aimed at shortening the user journey from the start of the accident until the user has applied the personal safety solution and is ready to escape.

    Throughout the project I’ve been working with a context which is heavily regulated, and all problems are serious, important ones. I have been striving towards keeping a high level of innovation during the process, whatever the result in the end might be. I’ve been heavily relying on scenarios/workflows, product testing, observation, and I’ve had the great joy to be able to take part of LKABs accident reports.

    The concept can be divided into three parts, but it is the way these collaborate that makes out the main part of the concept.

    1: An escape station, providing a standardized placement of escape hoods.

    2: A container for the vacuum sealed escape hood.

    3: An escape hood which enables a personalized fit for the user.

    Interactive surfaces are color coded with the goal to provide an intuitive workflow. When the container is opened, the vacuum seal is immediately broken and the user gains access to two handles, one white and one red. The handles are used to lift and apply the escape hood, and the red handle is then used, by pulling, to tighten the throat fit.

    Combined, these solutions help the user applying her escape hood in shorter time, and a large head size, glasses, beard and a thick neck are no longer problematic for the applica­tion

     

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  • 2.
    Aavik, Ida
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Onboarding New Users for Initial Creation of Photo Book in Mobile Application2024Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Photography holds great significance by capturing memories and sharing stories. Today, the average user has around 2,000 photos on their smartphone, many of which go unnoticed. Once Upon is a mobile application launched in 2017, where users can create photo books to collect their memories in a physical book. Observations and previous data from Once Upon show that new users encounter certain challenges when creating their first photo book with the application. This has sparked interest in exploring how onboarding can be used to help new users. Onboarding is a broad term that includes introducing users to a new product or service.

    This study followed the Design Thinking process to create a prototype of an onboarding process that facilitates understanding for new users how to get started with creating their first photo book using the Once Upon mobile application. In the first phase, Empathize, research methods were conducted to identify how users interact with the Once Upon mobile application. The data was further analyzed in order to narrow down the topic and define the problems in the Define phase, employing methods such as personas, user flow diagrams and mind mapping. Subsequently, ideas began to be generated in the next phase, Ideate, where How Might We statements were formulated. These were utilized in two workshops for brainstorming, and then contributed to the initial sketching of different design proposals. The last two phases, Prototype and Test, were performed iteratively to produce prototypes and test them with usability testing.

    It was observed that new users experienced some challenges when creating a photo book for the first time in the application. Among other things, they lacked inspiration, looked in the wrong place for certain functions or did not know how to start from scratch. With this, the focus was placed on the onboarding flow being about introducing users to creating their first photo book with the Once Upon mobile application. Different strategies and types of onboarding had been analyzed, and then some that were deemed suitable for the application were chosen to proceed with. During the tests of the prototypes, a flow was finally chosen that the participants appreciated the most. The result contributed to helping new users get started and get inspired to create their first photo book with the Once Upon mobile application, through the creation of a design proposal of an onboarding process.

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  • 3.
    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.

  • 4.
    Abduljalel, Viyan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Improving post-productionfeedback process2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The process of producing entertaining video and films is complicated and time consuming. One of the complicated parts of post-production of entertaining content is getting feedback and reviewing the draft edit. After the filming process of a series or a film completed, the editors start working on the cut materials. This is a stage in the process where the editor will get their cut reviewed and receive feedback from different teams on the rough-cut or editor cuts. Today the review and the feedback between the editor and reviewer is done online directly through email.

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  • 5.
    Abdulkader, Ammar
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Förseningar i byggprojektering och hur de kan förebyggas2023Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Idag är förseningar inom byggbranschen vanliga och orsakar problem och konsekvenser i byggprojekt. När ett projekt blir försenat uppstår extra kostnader för projektägaren, entreprenören eller båda parter. Med andra ord innebär förseningar ekonomiska förluster och skapar en stressig arbetsmiljö för alla inblandade aktörer och projektmedlemmar. I detta examensarbete identifieras betydande risker som kan orsaka förseningar i projekteringsfasen av byggprocessen, samt presenteras lösningar för att förebygga dem.

    Byggprocessen består av fyra faser: förstudie, projektering, produktion och överlämning. Projekteringsfasen är ett av de viktigaste stegen i byggprocessen och har stor betydelse för att förebygga förseningar. I denna fas utformas och ritas byggnader, och bygghandlingar tas fram med konstruktionsritningar, tekniska lösningar och beskrivningar upprättas för att styra hela byggprocessen.

    Detta arbete fokuserar på förseningar i själva projekteringsfasen och dess påverkan på hela projektet, samt hur de kan förebyggas. Arbetet består av en teoretisk och en praktisk del. Syftet med arbetet är att undersöka orsakerna till förseningar inom projekteringsfasen och att hantera dem på bästa sätt genom att utveckla riskhanteringen. Orsakerna kan vara ofullständig information, förändringar i projektspecifikationer och tekniska problem. Teorin bygger på litteratur om projektering i byggprocessen för att ge en bred kunskapsbas om projektering innan den praktiska delen genomförs. Den praktiska delen baseras på intervjuer med erfarna projektledare inom projektering som har varit involverade i olika försenade projekteringsprocesser. Resultatet presenterar projektledarens svar angående orsakerna till förseningarna i de två projekten. I diskussionen jämförs och analyseras resultaten med teorin, vilket visar att sjukdomar och bristande kommunikation, tillsammans med andra risker, kan vara orsaker till förseningar i projekteringsfasen. Förbättringsförslag inkluderar att skapa en trygg och hälsosam arbetsmiljö som en viktig faktor för projektets framgång, genom att anlita ytterligare konsulter från andra företag vid arbetsbelastning och erbjuda avkopplande aktiviteter som exempelvis spa-besök när det behövs. Andra förslag innefattar att lägga extra tid på riskanalys för att identifiera potentiella problem samt att etablera en kommunikationsmetod för grupper, såsom en grupp på Messenger eller en annan applikation, där all information om projektet regelbundet delas.

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  • 6.
    Abed, Ahmed Ghafel
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energieffektivisering vid renovering av Lamellhus på Mariehemsvägen2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In Sweden more houses than ever before are being built, and the house production is moving forward. At the same time, awareness of the energy use of buildings and its accompanying impacts on climate and sustainability are increasing. Therefore, Boverket constantly raises the demands for the energy performance of newly built and refurbished buildings.

    According to current requirements from Boverket (BBR, 2017), the primary energy value for apartment buildings may not be more than 85 kWh per square meter of tempered floor space and year. This also applies according to future requirements in 2021, but with the difference that the average U-value will decrease from 0.4 to 0.35 W/m2 K which means that apartment buildings must be built in an efficient way to reduce energy use. A large part of new construction and newly refurbished apartment buildings must then implement energy efficiency measures on their buildings to meet future requirements.

    This degree project has been carried out in collaboration with Rikshem AB who wants to investigate the impact of various energy efficiency measures on their apartment building ”Lamellhus”. The aim is to theoretically reduce apartment buildings ”Lamellhusets” specific energy use from 187,4 to 70 kWh/m2 Atemp, year and thus reduce the primary energy enough to meet future requirements according to BBR near-zero energy building.

    To theoretically reduce specific energy use and thus primary energy value, the project through manual calculations and with the help of computer tools examined various energy efficiency measures on the building's construction and installation system.

    The results show that the measures on the property climate shell are sufficient to meet the requirements. If all the measures according to package 1 or 2 on the design are combined, specific energy use according to BBR 16 (2010) will be at 83-94 kWh/m2 Atemp, year and the primary energy value according to BBR 25 (2017) will be at 68-77 kWh/m2 Atemp, year.

    The results also show how much of a building's energy use is ventilated. Replacing the ventilation system from F-systems to FTX-systems on the reference house in the base case, is the measure that gives one of the greatest impacts with a heat saving of (25.5-26.7%). In combination FTX-system with district heating, specific energy consumption can be reduced as low as possible. If the operation with the FTX-system is applied together with the existing district heating and all measures on the construction according to package 1 or 2, this gives a reduction of approximately (70-75 %) compared to the base case corresponding to 42-51 kWh/m2 Atemp, year according to BBR 16 and according to BBR 25, the figures are even lower. If the calculation considers thermal bridges and air leakage in the house, the result will increase.

    The results also show that the investment repays itself after 15-16 years with a simplified payback. With a calculation rate of 5 %, it is profitable over 30-31 years or more, but with a calculation rate of 8 % it is not profitable.

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    Energieffektivisering vid renovering av Lamellhus på Mariehemsvägen
  • 7.
    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.

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  • 8.
    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.

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  • 9.
    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.
    Smart Baggage in Aviation2011In: 2011 IEEE International Conferences on Internet of Things, and Cyber, Physical and Social Computing / [ed] Feng Xia, Zhikui Chen, Gang Pan, Laurence T. Yang, and Jianhua Ma, Los Alamitos: IEEE Computer Society, 2011, p. 620-623Conference paper (Refereed)
    Abstract [en]

    Nowadays, the Internet has dramatically changed the way people take the normal course of actions. By the recent growth of the Internet, connecting different objects to users through mobile phones and computers is no longer a dream. Aviation industry is one of the areas which have a strong potential to benefit from the Internet of Things. Among many problems related to air travel, delayed and lost luggage are the most common and irritating. Therefore, this paper suggests anew baggage control system, where users can simply track their baggage at the airport to avoid losing them. Attaching a particular pattern on the bag, which can be detected and localized from long distance by an ordinary camera, users are able to track their baggage. The proposed system is much cheaper than previous implementations and does not require sophisticated equipment.

  • 10.
    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.

  • 11.
    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.

  • 12.
    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.
    Gesture Tracking for 3D Interaction in Augmented Environments2011Conference paper (Other academic)
  • 13.
    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.
    Real 3D Interaction Behind Mobile Phones for Augmented Environments2011In: 2011 IEEE International Conference on Multimedia and Expo (ICME), IEEE conference proceedings, 2011, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Number of mobile devices such as mobile phones or PDAs has been dramatically increased over the recent years. New mobile devices are equipped with integrated cameras and large displays which make the interaction with device easier and more efficient. Although most of the previous works on interaction between humans and mobile devices are based on 2D touch-screen displays, camera-based interaction opens a new way to manipulate in 3D space behind the device in the camera's field of view. This paper suggests the use of particular patterns from local orientation of the image called Rotational Symmetries to detect and localize human gesture. Relative rotation and translation of human gesture between consecutive frames are estimated by means of extracting stable features. Consequently, this information can be used to facilitate the 3D manipulation of virtual objects in various applications in mobile devices.

  • 14.
    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.
    Sonning, Samuel
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sonning, Sabina
    3D Head Pose Estimation Using the Kinect2011Conference paper (Refereed)
    Abstract [en]

    Head pose estimation plays an essential role for bridging the information gap between humans and computers. Conventional head pose estimation methods are mostly done in images captured by cameras. However accurate and robust pose estimation is often problematic. In this paper we present an algorithm for recovering the six degrees of freedom (DOF) of motion of a head from a sequence of range images taken by the Microsoft Kinectfor Xbox 360. The proposed algorithm utilizes a least-squares minimization of the difference between themeasured rate of change of depth at a point and the rate predicted by the depth rate constraint equation. We segment the human head from its surroundings and background, and then we estimate the head motion. Our system has the capability to recover the six DOF of the head motion of multiple people in one image. Theproposed system is evaluated in our lab and presents superior results.

  • 15.
    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.
    Liu, Li
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Active human gesture capture for diagnosing and treating movement disorders2013Conference paper (Other academic)
    Abstract [en]

    Movement disorders prevent many people fromenjoying their daily lives. As with other diseases, diagnosisand analysis are key issues in treating such disorders.Computer vision-based motion capture systems are helpfultools for accomplishing this task. However Classical motiontracking systems suffer from several limitations. First theyare not cost effective. Second these systems cannot detectminute motions accurately. Finally they are spatially limitedto the lab environment where the system is installed. In thisproject, we propose an innovative solution to solve the abovementionedissues. Mounting the camera on human body, webuild a convenient, low cost motion capture system that canbe used by the patient in daily-life activities. We refer tothis system as active motion capture, which is not confinedto the lab environment. Real-time experiments in our labrevealed the robustness and accuracy of the system.

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    Active Human Gesture Capture for Diagnosing and Treating Movement Disorders
  • 16.
    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.

  • 17.
    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.

  • 18.
    Abedin, Reaz Ashraful
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Autonomous Object Category Learning for Service Robots Using Internet Resources2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the developments in the field of Artificial Intelligence (AI), robots are becoming smarter, more efficient and capable of doing more dififcult tasks than before. Recent progress in Machine Learning has revolutionized the field of AI. Rather than performing pre-programmed tasks, nowadays robots are learning things, and becoming more autonomous along the way. However, in most of the cases, robots need a certain level of human assistance to learn something. To recognize or classify daily objects is a very important skill that a service robot should possess. In this research work, we have implemented a fully autonomous object category learning system for service robots, where the robot uses internet resources to learn object categories. It gets the name of an unknown object by performing reverse image search in the internet search engines, and applying a verification strategy afterwards. Then the robot retrieves a number of images of that object from internet and use those to generate training data for learning classifiers. The implemented system is tested in actual domestic environment. The classification performance is examined against some object categories from a benchmark dataset. The system performed decently with 78:40% average accuracy on ve object categories taken from the benchmark dataset and showed promising results in real domestic scenarios. There are existing research works that deal with object category learning for robots using internet images. But those works use Human-in-the-loop models, where humans assist the robot to get the object name for using it as a search cue to retrieve training images from internet. Our implemented system eliminates the necessity of human assistance by making the task of object name determination automatic. This facilitates the whole process of learning object categories with full autonomy, which is the main contribution of this research.

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  • 19. 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.

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  • 20.
    Abidakun, Olatunde
    et al.
    Department of Mechanical and Aerospace Engineering, West Virginia University Morgantown, West Virginia, 26506, USA.
    Adebiyi, Abdulafeez
    Department of Mechanical and Aerospace Engineering, West Virginia University Morgantown, West Virginia, 26506, USA.
    Valiev, Damir
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education of China, Department of Energy and Power Engineering, Tsinghua University, Beijing, China.
    Akkerman, V’yacheslav
    Department of Mechanical and Aerospace Engineering, West Virginia University Morgantown, West Virginia, USA.
    Impacts of fuel nonequidiffusivity on premixed flame propagation in channels with open ends2021In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 33, article id 013604Article in journal (Refereed)
    Abstract [en]

    The present study scrutinizes premixed flame dynamics in micro-channels, thereby shedding light on advanced miniature micro-combustion technologies. While equidiffusive burning (when the Lewis number Le = 1) is a conventional approach adopted in numerous theoretical studies, real premixed flames are typically non-equidiffusive (Le ≠ 1), which leads to intriguing effects, such as diffusional-thermal instability. An equidiffusive computational study [V. Akkerman et al., Combust. Flame 145, 675–687 (2006)] reported regular oscillations of premixed flames spreading in channels having nonslip walls and open extremes. Here, this investigation is extended to nonequidiffusive combustion in order to systematically study the impact of the Lewis number on the flame in this geometry. The analysis is performed by means of computational simulations of the reacting flow equations with fully-compressible hydrodynamics and onestep Arrhenius chemical kinetics in channels with adiabatic and isothermal walls. In the adiabatic channels, which are the main case of study, it is found that the flames oscillate at low Lewis numbers, with the oscillation frequency decreasing with Le, while for the Le > 1 flames, a tendency to steady flame propagation is observed. The oscillation parameters also depend on the thermal expansion ratio and the channel width, although the impacts are rather quantitative than qualitative. The analysis is subsequently extended to the isothermal channels. It is shown that the role of heat losses to the walls is important and may potentially dominate over that of the Lewis number. At the same time, the impact of Le on burning in the isothermal channels is qualitatively weaker than that in the adiabatic channels.

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  • 21.
    Abor, Joshua Yindenaba
    et al.
    Centre for Global Finance, SOAS University of London, United Kingdom; University of Stellenbosch Business School, South Africa.
    Karimu, AminUmeå University, Faculty of Social Sciences, Centre for Environmental and Resource Economics (CERE). Environmental Policy Research Unit (EPRU), University of Cape Town, South Africa.
    Sustainability management in the oil and gas industry: emerging and developing country perspectives2023Collection (editor) (Refereed)
    Abstract [en]

    The oil and gas industry is a complex sector with significant reach in terms of providing the energy needs of the global economy and the security, environmental and development consequences thereof. In particular, the sector is extremely important for the economic growth of emerging markets and developing countries. Furthermore, the life span of oil and gas resources is finite, with high health and safety risks and substantial environmental costs that require careful management and sustainability practices to ensure optimal extraction and utilisation of these resources. This book examines the challenges and opportunities in the oil and gas industry, in the context of emerging markets and developing economies. It provides comprehensive coverage of the management and sustainability practices of the sector, the environmental impact and sustainability of resources as well as the businesses that operate in the sector across the entire value chain. It addresses the current discourse on topics such as the Sustainable Development Goals, the Green Economy, the Paris Agreement and Glasgow Climate Pact and concludes with a chapter on the future of the oil and gas industry. The discussions around energy and energy transitions in particular continue to gain momentum and the book provides a wide-reaching and up-to-date overview of the industry. The book introduces readers to the concepts and formal models of analysis in the oil and gas sector and will serve as a useful resource for students, scholars and researchers in operations, marketing, procurement and supply chain management, project management, health and safety management, environmental economics, natural resource economics, development finance, and development studies. Researchers and practitioners working in these areas will also find the book a useful reference material.

  • 22.
    Abouhachem, Khalil
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Implementering av Lean Production på Hedson Technologies AB2014Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is the conclusion of my bachelor degree in mechanical engineering at Umeå University. The report is the result of the work that has been done at Hedson Technologies AB in Malmö. Hedson is the number one on the market for producing wheel washers, dry equipment and car lifts. They have two constructions in Sweden and one in Germany. This work is limited to the building in Malmö, Sweden.

    To continue being the market leading company Hedson have realized that they need to improve the production line. To obtain a more efficient flow companies usually use Lean Production. Lean is a philosophy that permeates the whole company, from supply delivery until the product has reached the customer. The purpose of this thesis is to begin a work within Lean at Hedson. The work is supposed to act as groundwork for a Lean initiative that the company later can build on to get the production as efficient as possible.

    I have through an analysis of the production line and interviews with the market and the product manager shaped an overall picture of how the company operates. I have then done a pilot study and manipulated the information I have gathered to find the optimal course of action for Hedson to begin their work within Lean.

    It was thanks to a great cooperation with the staff of the company that a successful result was possible. Since the production was much unorganized and disordered the implementation of the 5S method was a perfect start for a long and successful journey through Lean Production. At last an introduction to Lean and 5S was done through a presentation to create an understanding at the company.

  • 23.
    Abrahamsson, Eric
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Samuel, Palm
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Optimering av täthetsprovning av ventiler2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nordhydraulic is a company in Kramfors that manufactures hydraulic valves. Hydraulic valves are used in a variety of areas to control hydraulic machines. For hydraulic valves to function properly, they must be tight. At Nordhydraulic, a leak tester called Nolek S9 N is used to determine if valves are tight. The leak tester fills the valves with a predetermined pressure and then measures the flow of air into the valve required to maintain the pressure.

    Today, this method has major problems with false negative results in the assembly line, which means that tight valves may give a result that indicates leakage and thus can lead to a bottleneck in the assembly. This is because there are many spaces in the valve that are difficult to reach by the air. The purpose of this work was to develop a better program for the Nolek S9 N to be used in the leak test to reduce assembly stops. The development of this program is done by making measurements with different time settings as well as connection methods to find the most important parameters of the program. Then, measurements are made on valves assembly errors and casting errors to see what flow the leakage has at these errors.

    The work resulted in three different programs for the RS210 valve, which in tests in the assembly achieved approved results faster than the previous program and with fewer false negative results. The conclusion is that the developed program could provide an improvement of the leak test and that the current limit for approved leakage can be increased to 50 mm^3/s  without missing the assembly errors that may occur.

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    Optimering av täthetsprovning av ventiler
  • 24.
    Abrahamsson, Erik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Värmeöverföring från smälta till vattenkyld tapputrustning2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work is done on behalf of Boliden Mineral AB at Rönnskärsverken.

    Kopparhyttan is an electric copper furnace for melting of copper concentrates and secondary materials in the form of ashes, metal scrap, crushed matte, slag and sludge.

    Depending on how the input material varies, the chemical composition of the melt will vary as well. Variations in the chemical composition of the melt also imply that the physical properties of the melt vary and the heat transfer between melt and tap block.

    A high heat load on the tap block during tapping of matte, results in increased wear and severe erosion of the tap channel and therefore the need of an understanding of the underlying causes to prevent and if possible avoid the high heat load.

    The completed analysis shows that a high heat load on the tap equipment mainly is associated with the copper content. A lower copper content leads to the melting point is lowered and also reduces the viscosity, leading to an increased mass flow. The increased heat load thus indicate an increased mass flow in combination with a reduced melting point, which means that the freezing of an erosion protective coating of matte on the inside of tapping channel walls becomes more difficult and thus increases the erosion on the tap equipment. Sulphur deficit, which is calculated from a chemical analysis of matte, showed no correlation to a high heat load and no connection between the sulfur deficit and the erosion of the tap equipment were successfully concluded.

    Measures proposed to reduce the wear on the tap equipment are increasing the flow of cooling water and a possible reduction of the tap channel diameter.

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  • 25.
    Abrahamsson, Linus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kvalitetssäkring av Quick Change™-produkter vid Rototilt Group2021Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Rototilt Group AB is a company located in Vindeln that produces and sells tiltrotators, machine couplers and other different excavator accessories. Since Rototilt recently launched a new series of products, and is expanding their factory, they have not been able to assign any workforce on the quality assurance of their new products. Therefore, this project aims at ensuring that quality is maintained, and that the verifications process is streamlined.

    The work is based on measuring the time spent on each segment in the verifying process, and to identify the segments that have the largest influence on quality. Thereafter, every type of deviation Rototilt has experienced since launching the Quick Change™ product series was analysed.

    It was found that the verification process takes 17 minutes on average, which is a process time Rototilt is aiming to reduce. A compilation of the deviations since the launching of Quick Change™, indicates that the main problems are product quality and lack of documentation. Based on the analysis of process time and type of deviation, a chart with conceptual solutions forms a solid foundation for implementation, which will result in a winwin situation for the operator as well as the company. One solution that stands out is to invest in quick hydraulic couplers. Another solution is to implement In-Process Verification to ensure the quality instead of the current End of Line Testing method. The analysis indicated which parts were crucial for maintaining the quality, and which were crucial for the efficiency. Recommended concepts are based on minimizing investment costs and efforts for implementation and maximizing improvement of the work environment for the operator.

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  • 26.
    Abrahamsson, Matilda
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Metoder för utredning av inomhusmiljö: En studie inom hälsoskyddet med delsyfte att utföra dammätningar i skolor2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Methods for inspection of the indoor environment – a study within health protection where a part of the aim is to perform measurements of dust in schools

    In Sweden the communities are responsible for the health protection in many agencies. The control of the indoor environment can be done in different ways and with different means. The aim of this report was to study in which way the inspectors made this kind of inspections and if there was anything in their approach that could be developed. A part of the aim of the report was to study how fast a clean surface in a school become dusty. Interviewes with healthinspectors in Uppsala, Håbo and Tierp was made. Together with them also some inspections were performed. To get a larger view of methods to investigate the indoor environment some inspections of schools and dwellings were done with an employee at the unit of Arbets- och miljömedicin at the University Hospital in Uppsala. The dust study was performed at two schools in Knivsta. The results were that the inspectors had well developed methods for assessings of the indoor environment. The approach differed in some matters between the larger and the smaller communities. Regardless of the size of the communities the inspectors rarely used instruments as a tool for the inspections. The communication and agreement between the inspectors was also shown as an important part in their work. In general the inspectors felt secure in their role and to make decisions. It appeared some shortcomings in the general advice and guidelines from the national board of health and welfare, which is the national supervisory authority that shall guide inspection of health protection. For example there was shown a lack in the guidelines regarding cleaning in schools and kindergardens. The study of dust in schools showed that there was more dust after five days than after one day.

  • 27.
    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.

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  • 28.
    Abrahamsson, Max
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Elbussar i Örnsköldsvik: En analys över vad som krävs för att elektrifiera bussarna i tätortstrafiken i Örnsköldsvik.2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    For Sweden to achieve its environmental goals by 2045, municipalities need to reducegreenhouse gas emissions, especially from from the transport sector. Recentmeasurements in Örnsköldsvik have shown poor quality air in the built-up environment.Buses are the vehicle classes that emit, proportionally the most carbon dioxide equivalentgases. The intention is to replace the current city buses with electric vehicles to take asignificant step on the road to zero emissions.When electric buses are planned for a city traffic implementation, you must first establishwhat kind of electric buses you want to use. In Örnsköldsvik, the most relevant alternativestoday are either depot-charged or additional-charged buses.Which of the bus types that the municipality chooses to implement will affect themdifferently. If they choose depot-charged buses, the vehicles will be more expensive, but itwill not be necessary to add as much infrastructure and the circulation plan will not be asaffected as in the other case. In addition, some of the lines are too long to run all day, atsome point during the day a depot-charged bus must be run empty back to the depot to bereplaced by a charged bus. If additional-charging is chosen, the infrastructure will be moreexpensive (though fixed infrastructure has a low total cost compared to the cost of thevehicles as these have a longer depreciation period) and the circulation plan will need somechanges so that the buses have time to charge for a few minutes at the end stops.With current electric bus technology, electric buses should work in Örnsköldsvik’s urbanarea. Most with depot charging, some lines may need additional charging. Minimumrecommendations are made for the depot size, location and electric effect needed. Also,recommendation of piloting with 6 busses rather than taking a “Big bang” approach toimplementation to gain experience.

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  • 29.
    Abrahamsson, Simon
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ny lösning för uppvärmning av Nordanås provbana2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    BAE Systems Hägglunds testbana är belägen i Nordanås nordväst om Örnsköldsvik. Detta projekt hade till avsikt att på BAE Systems förfrågan inventera testanläggningens nuvarande oljebaserade värmesystem för att finna ett mer ekonomiskt och miljövänligt alternativ. Utifrån en omfattande litteraturstudie samt kontakt med flera olika leverantörer, undersöktes vilka eventuella värmesystem som skulle kunna vara intressanta utifrån de krav som fanns i Nordanås.

    De alternativa värmesystemen som ansågs vara tekniskt hållbara var följande; bergvärme med lätt biooljepanna, tung biooljepanna eller pelletspanna; pelletspanna, lätt biooljepanna och tung biooljepanna. Dessa alternativ är de som undersökts noggrant i studien och därefter jämförts med det nuvarande värmesystemet i form av ekonomi och miljöpåverkan.

    I en ekonomisk kalkyl jämfördes de olika alternativens kapitalvärde och återbetalningstid. För att jämföra deras miljöpåverkan skapades en kalkyl som utifrån framtagna värden på olika bränslens utsläpp beräknade varje alternativs förväntade årliga utsläpp i form av koldioxidekvivalenter.

    Slutligen konstaterades att om BAE Systems Hägglunds ska byta ut nuvarande systemet bör man antingen investera i ett bergvärmesystem med en lätt biooljepanna som spetspanna eller en konvertering till lätt biooljepanna. Med priser från den tid då rapporten skrevs skulle alternativet med bergvärme ha en beräknad återbetalningstid på ca 6,4 år och kapitalvärdet 1,0 Mkr. Motsvarande värden för alternativet med enbart en lätt biooljepanna uppgick till 1,0 års återbetalningstid samt 0,8 Mkr i kapitalvärde. Den stora skillnaden i återbetalningstid berodde på bergvärmesystemets höga investeringskostnad. Att investera i ett bergvärmesystem ansågs trots detta som ett bra alternativ på grund av den förväntade prisökningen av eldningsolja.

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    Ny lösning för uppvärmning av Nordanås provbana
  • 30.
    Abugabbara, Marwan
    et al.
    Department of Building and Environmental Technology, Division of Building Services, Lund University, Lund, Sweden.
    Gehlin, Signhild
    The Swedish Geoenergy Center, Lund, Sweden.
    Lindhe, Jonas
    Department of Building and Environmental Technology, Division of Building Services, Lund University, Lund, Sweden; Alfa Laval Corporate AB, Lund, Sweden.
    Axell, Monica
    RISE Research Institute of Sweden, Gothenburg, Sweden.
    Holm, Daniel
    Vasakronan AB, Stockholm, Sweden.
    Johansson, Hans
    Umeå ProjektEnergi AB, Umeå, Sweden.
    Larsson, Martin
    RISE Research Institute of Sweden, Gothenburg, Sweden.
    Mattsson, Annika
    Granitor Properties, Malmö, Sweden.
    Näslund, Ulf
    Vasakronan AB, Stockholm, Sweden.
    Puttige, Anjan Rao
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Berglöf, Klas
    ClimaCheck Sweden AB, Nacka, Sweden.
    Claesson, Johan
    Department of Building and Environmental Technology, Division of Building Physics, Lund University, Lund, Sweden.
    Hofmeister, Morten
    Research Center for Built Environment, Energy, Water and Climate, VIA University College, Horsens, Denmark.
    Janson, Ulla
    Department of Building and Environmental Technology, Division of Building Services, Lund University, Lund, Sweden.
    Jensen, Aksel Wedel Bang
    Region Midtjylland, Aarhus, Denmark; Department of Planning, Aalborg University, Aalborg, Denmark.
    Termén, Jens
    Energy Machines, Gävle, Sweden.
    Javed, Saqib
    Department of Building and Environmental Technology, Division of Building Services, Lund University, Lund, Sweden.
    How to develop fifth-generation district heating and cooling in Sweden?: Application review and best practices proposed by middle agents2023In: Energy Reports, E-ISSN 2352-4847, Vol. 9, p. 4971-4983Article in journal (Refereed)
    Abstract [en]

    Sweden has an ambitious plan to fully decarbonise district heating by 2030 and to contribute with negative emissions of greenhouse gases in 2050. The vagaries of the energy market associated with climate, political, and social changes entail cross-sectoral integration that can fulfill these national targets. Fifth-generation district heating and cooling (5GDHC) is a relatively new concept of district energy systems that features a simultaneous supply of heating and cooling using power-to-heat technologies. This paper presents best practices for developing 5GDHC systems in Sweden to reach a consensus view on these systems among all stakeholders. A mixed-method combining best practice and roadmapping workshops has been used to disseminate mixed knowledge and experience from middle agents representing industry professionals and practitioners. Four successful implementations of 5GDHC systems are demonstrated and the important learned lessons are shared. The best practices are outlined for system planning, system modeling and simulation, prevailing business models for energy communities, and system monitoring. A roadmap from the middle agents’ point of view is composed and can be utilised to establish industry standards and common regulatory frameworks.

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  • 31.
    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.

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    FULLTEXT01
  • 32.
    Acef, Lylia
    et al.
    University Of Science And Technology Houari Boumediene, Algiers, Algeria.
    Bouzergui, Fatene
    University Of Science And Technology Houari Boumediene, Algiers, Algeria.
    Benouar, Sara
    University Of Science And Technology Houari Boumediene, Algiers, Algeria.
    Hafid, Abdelakram
    University Of Science And Technology Houari Boumediene, Algiers, Algeria.
    Ferroukhi, Merzak
    University Of Science And Technology Houari Boumediene, Algiers, Algeria.
    Low cost electronic instrumentation solutions for cardiovascular parameters measurement2019In: 2019 International Conference on Advanced Electrical Engineering (ICAEE), IEEE, 2019, p. 1-5Conference paper (Refereed)
    Abstract [en]

    Cardiovascular activity is one of the primordial physiological phenomena of human life. However, it is subject to many pathologies due to various factors such as: lifestyle, age, diabetes, cholesterol or heredity. As a consequence, there are different kinds of examination and methods used to enable the diagnostic. In this paper cardiovascular parameters are calculated due to the acquisition of simultaneous electrocardiography (ECG) and photoplethysmography (PPG) signals and the high limb peripheral arterial stiffness is evaluated by the calculation of the Pulse Wave Velocity (PWV) parameter. Those measurements are performed by two different low-cost systems based on Arduino board. The acquired waveforms form each device prototype present a satisfactory result, and the cardiovascular parameters are in the range of the value found in the literature. The developed prototype devices could easily be used for engineering educational purposes, hobby or first steps research.

  • 33.
    Ackermann, Wilhelm
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    The Impact of Spatial User Interface Integration within Strategy Games: An evaluation of a strategy game’s approachability within diegesis and spatial theory2021Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Diegesis and Spatiality are fundamental to visualization techniques in games. The impact of integrating user interfaces into the game world is a contentious issue between minimizing the heads-up display or maximizing functionality above realism. Previous studies have shown conflicting results determining what approach is better, but these studies have focused on conventional genres like the First Person Shooter. Strategy games, or more specifically, the grand strategy genre, is different in perspective and role of the player, as the genre places a heavier emphasis on panel elements than other genres. In this paper, we created two similar prototypes that differed in their focus on integration or superimposition. We then evaluated their impact on performance and the user experiences. The results showed that strictly spatial integration attributed to negative results, but diegetic integration was better received. Additionally, we identified several areas where implementing diegetic interfacing in grand strategy games is different from other genres of games. Finally, we gave recommendations to enhance the strengths and overcome the limitations of diegetic interfacing in grand strategy games.

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  • 34.
    Adam, Nyström
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energideklarationsanalys: En inblick i energiläget i Umeå kommun2021Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the year 2018 the housing and service-sector accounted for 40% of the total use of energy in Sweden. Great adjustments and energy-technical actions are necessary to reduce the emissions from this sector. By analyzing the energy-use in buildings on a local scale through compilation of energy-declaration-data an overall look of the energy consumption is achieved. With this insight the work becomes easier to plan how the emissions from the housing and service-sector is supposed to be reduced with energy-efficient measures.

    The aim of this report is to investigate the energy-use in apartment buildings in Umeå kommun through analysis of energy-declaration-data. The goal is to present an overall look at the energy-use in the municipality and to present the measures that is needed to reduce the use of energy in apartment buildings.

    The work initiated by submitting a research certificate to Boverket to gain access to energy-declaration-data of buildings in the municipality. Five models were created by calculating the average value for different parameters in the data. The first model is based on the mean values for every apartment building in the data. The remaining four models were created with the average value for different parameters for apartment buildings with an energy-classification of D, E, F and G. Parameters such as heating system, ventilation system and the proposed energy-efficient measures were analyzed for each model. The models were simulated in an energy-program called BV2. The most frequent occurring energy-efficient measures in the data were applied to the models to calculate the potential reduction of energy consumption in the buildings. The energy use, carbon dioxide emissions and the primary-energy-value were calculated for each model after the energy-efficient measures were simulated.

    The distribution of energy-classification of the analyzed apartment buildings in Umeå kommun differs from the Swedish national compilation (Created by Boverket) according to the data. The number of buildings with an energy-classification of F and G is percental lower in Umeå compared to the national compilation. An average apartment building in Umeå has an energy-classification of E and uses 87.3 kWh/m2, year for heating purposes. The use of real estate electricity was calculated to an average of 16,7 kWh/m2, year. The most frequent occurring heating system in the data was district heating and the most frequent ventilation system was FTX. An apartment building in Umeå emits 6,43 kg CO2-e/m2, year on average. By analyzing the data and through calculations the result showed that by adjusting the heating system a yearly saving corresponding to 2 – 4% could be achieved. By installing water saving equipment in the apartments a potential saving corresponding to 3 – 8% could be achieved.

    Existing buildings should be renovated with application of energy-efficient engineering techniques in the same pace as new buildings are built. To reach carbon neutrality to the year 2040 a lot must be done to the existing building stock. Through compilation of energy-declaration-data and analysis an insight of the energy related problems could be located and improved.

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  • 35.
    Adebiyi, Abdulafeez
    et al.
    Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia 26506, USA.
    Alkandari, Rawan
    Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia 26506, USA.
    Valiev, Damir
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education of China, Department of Energy and Power Engineering, Tsinghua University, Beijing, China.
    Akkerman, V’yacheslav
    Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia, USA.
    Effect of surface friction on ultrafast flame acceleration in obstructed cylindrical pipes2019In: AIP Advances, E-ISSN 2158-3226, Vol. 9, no 3, article id 035249Article in journal (Refereed)
    Abstract [en]

    The Bychkov model of ultrafast flame acceleration in obstructed tubes [Valiev et al., "Flame Acceleration in Channels with Obstacles in the Deflagration-to-Detonation Transition," Combust. Flame 157, 1012 (2010)] employed a number of simplifying assumptions, including those of free-slip and adiabatic surfaces of the obstacles and of the tube wall. In the present work, the influence of free-slip/non-slip surface conditions on the flame dynamics in a cylindrical tube of radius R, involving an array of parallel, tightly-spaced obstacles of size αR, is scrutinized by means of the computational simulations of the axisymmetric fully-compressible gasdynamics and combustion equations with an Arrhenius chemical kinetics. Specifically, non-slip and free-slip surfaces are compared for the blockage ratio, α, and the spacing between the obstacles, ΔZ, in the ranges 1/3 ≤ α ≤ 2/3 and 0.25 ≤ ΔZ/R ≤ 2.0, respectively. 

    For these parameters, an impact of surface friction on flameacceleration is shown to be minor, only 1-4%, slightly facilitating acceleration in a tube with ΔZ/R = 0.5 and moderating acceleration in thecase of ΔZ/R = 0.25. Given the fact that the physical boundary conditions are non-slip as far as the continuum assumption is valid, the presentwork thereby justifies the Bychkov model, employing the free-slip conditions, and makes its wider applicable to the practical reality. Whilethis result can be anticipated and explained by a fact that flame propagation is mainly driven by its spreading in the unobstructed portion ofan obstructed tube (i.e. far from the tube wall), the situation is, however, qualitatively different from that in the unobstructed tubes, wheresurface friction modifies the flame dynamics conceptually.

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  • 36.
    Adebiyi, Abdulafeez
    et al.
    Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, United States.
    Idowu, Gbolahan
    Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, United States.
    Valiev, Damir
    Center for Combustion Energy, Tsinghua University, Beijing 100084, China.
    Akkerman, V'yacheslav
    Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, United States.
    Computational simulations of nonequidiffusive premixed flames in obstructed pipes2018Conference paper (Refereed)
    Abstract [en]

    The impact of the Lewis number, Le, on the dynamics and morphology of a premixed flame front, spreading through a toothbrush-like array of obstacles in a semi-open channel, is studied by means of the computational simulations of the reacting flow equations with fully-compressible hydrodynamics and Arrhenius chemical kinetics. The computational approach employs a cell-centered, finite-volume numerical scheme, which is of the 2nd-order accuracy in time, 4th-order in space for the convective terms, and of the 2nd-order in space for the diffusive terms. The channels of blockage ratios 0.33∼0.67 are considered, with the Lewis numbers in the range 0.2≤Le≤2.0 employed. It is shown that the Lewis number influences the flame evolution substantially. Specifically, flame acceleration weakens for Le>1 (inherent to fuel-lean hydrogen or fuel-rich hydrocarbon burning), presumably, due to a thickening of the flame front. In contrast, Le<1 flames (such as that of rich hydrogen or lean hydrocarbon) acquire an extra strong folding of the front and thereby accelerate even much faster. The later effect can be devoted to the onset of the diffusional-Thermal combustion instability. © 2018 Eastern States Section of the Combustion Institute. All rights reserved.

  • 37.
    Adelblad, Hany
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Framtagning av ett koncept för motordrivna sjukhussängar.: Affärsförslag2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The project was concerned with developing a concept to integrating a battery-powered motor with a wheel in the hospital beds that are used for internal patient transfers between departments at the Norrland University Hospital (NUS). The department for patient transport at NUS is responsible for the daily internal patient transfers, which takes place approximately 10–40 times per day with varied distances up to 500 m. The weight of the bed including mattress, healthcare equipment and the patient can be up to 450 kg. The purpose of the project was to create a business case for a concept that will facilitate work during patient transfers. Ultimately, this should lead to a more ergonomic way of working. The goal was to come up with a suggestions and design variants that will facilitate patient movements for staff working at the patient transport department, as well as to propose the most optimal components, for example which motor, battery, wheels and bracket that can be used in the concept. The project was carried out by collecting facts, opinions and limitations from the product user via meetings and telephone calls. Market research was also performed via the suppliers' websites and phone calls to them. Design variants have been created using CAD-Solid Works. The result shows that the concept's requirements are met at a maximum load of 450 kg if a battery-powered DC motor of 1654 Watt is used. The conclusion is that, although there are similar concepts on the market that meet the same goals, the proposed solution can easily and cost-efficiently be integrated in the existing hospital beds at NUS.

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  • 38.
    Adewole, Kayode S.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science. Department of Computer Science, University of Ilorin, Ilorin, Nigeria.
    Torra, Vicenç
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    DFTMicroagg: a dual-level anonymization algorithm for smart grid data2022In: International Journal of Information Security, ISSN 1615-5262, E-ISSN 1615-5270, Vol. 21, p. 1299-1321Article in journal (Refereed)
    Abstract [en]

    The introduction of advanced metering infrastructure (AMI) smart meters has given rise to fine-grained electricity usage data at different levels of time granularity. AMI collects high-frequency daily energy consumption data that enables utility companies and data aggregators to perform a rich set of grid operations such as demand response, grid monitoring, load forecasting and many more. However, the privacy concerns associated with daily energy consumption data has been raised. Existing studies on data anonymization for smart grid data focused on the direct application of perturbation algorithms, such as microaggregation, to protect the privacy of consumers. In this paper, we empirically show that reliance on microaggregation alone is not sufficient to protect smart grid data. Therefore, we propose DFTMicroagg algorithm that provides a dual level of perturbation to improve privacy. The algorithm leverages the benefits of discrete Fourier transform (DFT) and microaggregation to provide additional layer of protection. We evaluated our algorithm on two publicly available smart grid datasets with millions of smart meters readings. Experimental results based on clustering analysis using k-Means, classification via k-nearest neighbor (kNN) algorithm and mean hourly energy consumption forecast using Seasonal Auto-Regressive Integrated Moving Average with eXogenous (SARIMAX) factors model further proved the applicability of the proposed method. Our approach provides utility companies with more flexibility to control the level of protection for their published energy data.

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  • 39.
    Adewole, Kayode Sakariyah
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science. Department of Computer Science and Media Technology, Malmö University, Malmö, Sweden; Department of Computer Science, University of Ilorin, Ilorin, Nigeria.
    Torra, Vicenç
    Umeå University, Faculty of Science and Technology, Department of Computing Science. Department of Computer Science and Media Technology, Malmö University, Malmö, Sweden.
    Privacy protection of synthetic smart grid data simulated via generative adversarial networks2023In: Proceedings of the 20th international conference on security and cryptography, SECRYPT 2023 / [ed] DiVimercati, SD; Samarati, P, SciTePress, 2023, p. 279-286Conference paper (Refereed)
    Abstract [en]

    The development in smart meter technology has made grid operations more efficient based on fine-grained electricity usage data generated at different levels of time granularity. Consequently, machine learning algorithms have benefited from these data to produce useful models for important grid operations. Although machine learning algorithms need historical data to improve predictive performance, these data are not readily available for public utilization due to privacy issues. The existing smart grid data simulation frameworks generate grid data with implicit privacy concerns since the data are simulated from a few real energy consumptions that are publicly available. This paper addresses two issues in smart grid. First, it assesses the level of privacy violation with the individual household appliances based on synthetic household aggregate loads consumption. Second, based on the findings, it proposes two privacy-preserving mechanisms to reduce this risk. Three inference attacks are simulated and the results obtained confirm the efficacy of the proposed privacy-preserving mechanisms.

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  • 40.
    Adjeiwaah, Mary
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Quality assurance for magnetic resonance imaging (MRI) in radiotherapy2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Magnetic resonance imaging (MRI) utilizes the magnetic properties of tissues to generate image-forming signals. MRI has exquisite soft-tissue contrast and since tumors are mainly soft-tissues, it offers improved delineation of the target volume and nearby organs at risk. The proposed Magnetic Resonance-only Radiotherapy (MR-only RT) work flow allows for the use of MRI as the sole imaging modality in the radiotherapy (RT) treatment planning of cancer. There are, however, issues with geometric distortions inherent with MR image acquisition processes. These distortions result from imperfections in the main magnetic field, nonlinear gradients, as well as field disturbances introduced by the imaged object. In this thesis, we quantified the effect of system related and patient-induced susceptibility geometric distortions on dose distributions for prostate as well as head and neck cancers. Methods to mitigate these distortions were also studied.

    In Study I, mean worst system related residual distortions of 3.19, 2.52 and 2.08 mm at bandwidths (BW) of 122, 244 and 488 Hz/pixel up to a radial distance of 25 cm from a 3T PET/MR scanner was measured with a large field of view (FoV) phantom. Subsequently, we estimated maximum shifts of 5.8, 2.9 and 1.5 mm due to patient-induced susceptibility distortions. VMAT-optimized treatment plans initially performed on distorted CT (dCT) images and recalculated on real CT datasets resulted in a dose difference of less than 0.5%.

     The magnetic susceptibility differences at tissue-metallic,-air and -bone interfaces result in local B0 magnetic field inhomogeneities. The distortion shifts caused by these field inhomogeneities can be reduced by shimming.  Study II aimed to investigate the use of shimming to improve the homogeneity of local  B0 magnetic field which will be beneficial for radiotherapy applications. A shimming simulation based on spherical harmonics modeling was developed. The spinal cord, an organ at risk is surrounded by bone and in close proximity to the lungs may have high susceptibility differences. In this region, mean pixel shifts caused by local B0 field inhomogeneities were reduced from 3.47±1.22 mm to 1.35±0.44 mm and 0.99±0.30 mm using first and second order shimming respectively. This was for a bandwidth of 122 Hz/pixel and an in-plane voxel size of 1×1 mm2.  Also examined in Study II as in Study I was the dosimetric effect of geometric distortions on 21 Head and Neck cancer treatment plans. The dose difference in D50 at the PTV between distorted CT and real CT plans was less than 1.0%.

    In conclusion, the effect of MR geometric distortions on dose plans was small. Generally, we found patient-induced susceptibility distortions were larger compared with residual system distortions at all delineated structures except the external contour. This information will be relevant when setting margins for treatment volumes and organs at risk.  

    The current practice of characterizing MR geometric distortions utilizing spatial accuracy phantoms alone may not be enough for an MR-only radiotherapy workflow. Therefore, measures to mitigate patient-induced susceptibility effects in clinical practice such as patient-specific correction algorithms are needed to complement existing distortion reduction methods such as high acquisition bandwidth and shimming.

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  • 41.
    Adolfsson, Daniel
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lastfördelning: En jämförelse mellan handberäkningar och FEM-design2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The stability of the structure must be ensured when designing a building. To ensure the stability, the forces which a building can be exposed for must be known. In case of wind loads it means forces in the horizontal stabilizing system.

    The purpose with this project was to examine if FEM-design distribute wind loads like traditional hand calculations. This by comparing the results of load distribution for both calculation methods on a reference building. The reference building is designed in four different versions where the stiffness in the walls and the floor is what separate them. That to observe different design situations. The load distribution has been clarified by calculating reaction forces in the ground and shear forces in the walls.

    The stiffness ratio between the walls and the floor has been calculated to examine the load distribution on the walls. Calculations showed that the floor was weak in relation to the walls for two of the building’s versions. A ratio which the literature suggests that the load distributes like a continuous beam on fixed support. When hand calculations where compared to FEM-design the results did not agree very well. FEM-design gave a more uniform distribution of the loads, which reminds of a design the literature suggests for a structure with the same stiffness in the walls as in the floor. Further research indicates that it probably due to the different methods way of calculating stiffness for CLT.

    Based on the research done in this project it can be stated that load distribution for buildings with stiff floors and walls with the same stiffness correspond for the different calculation methods. For buildings with stiff floors and different stiffness in the walls the results do not agree. Probably due to the different methods of calculating stiffness for CLT.

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    Lastfördelning - En jämförelse mellan handberäkningar och FEM-design
  • 42.
    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.

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    Lastområdesutvidgning med aktiv flödeskontroll i Francisturbiner
  • 43.
    af Geijerstam, Klas
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    CONGESTION-CONTROLLED AUTOTUNING OF OPENMP PROGRAMS2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Parallelisation is becoming more and more important as the single core performance increase is stagnating while the amount of cores is increasing with every new generation of hardware. ŒThe traditional approach of manual parallelisation has an alternative in parallel frameworks, such as OpenMP, which can simplify the creation of parallel code. Optimising this code can, however, be cumbersome and difficult. Automating the optimisation or tuning of parallel code and computations is a very interesting alternative to manually optimising algorithms and programs. Previous work has shown that intricate systems can eff‚ectively autotune parallel programs with potentially the same eff‚ectiveness as human experts. ThŒis study suggests using an approach with the main algorithm used inspired from the congestion control algorithms from computer networks, namely AIMD. By applying the algorithm on top of an OpenMP program the parallel parameters such as grain size can be controlled. TheŒe simpli€ed algorithm is shown to be able to achieve a 19% speedup compared to a naive static parallel implementation

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  • 44.
    Afzaal, Qasim
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Ahmad, Usman
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Audio Video Streaming Solution for Bambuser2012Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Audio/Video streaming has widely been used in different applications but the social communication applications have especially raised its usage. The aim of this thesis is to design and develop an improved Audio/Video streaming solution for a Swedish company Bambuser and can easily be extended with new features where necessary. Currently Bambuser is using the Flash Media Server (FMS) for streaming the media, but it is license based and adds the extra cost to the company's budget. It does not support a wide range of platforms (e.g. OpenBSD and various Linux distributions) and also has limited options for the streaming. There is no real time monitoring and controlling functionality, which can show the status of essential services to the user, needed for the streaming (for example if the camera is working, microphone is turned on, battery power status. etc.).

    In order to solve these issues the GStreamer is used, which is an Open source multimedia streaming framework. The GStreamer environment was tested on different Linux distributions. The research and implementation includes the creation of the streaming pipeline and analyzing which options (i.e. GStreamer elements and plugins) are required to stream the media. It also includes the testing of different pipeline parameters (for example video rate, audio rate etc.) and noting their effects in a real working environment. Python binding with GStreamer is used to have better control over the pipeline. Another requirement of this project was to add the functionality of monitoring and control that shows the status of essential services to the user. Implementation of this part is done by using server and client side coding. Further improvements and suggestions are also proposed in this report.

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  • 45.
    Agardh, Ella
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Jämförelse av kostnad och klimatpåverkan för olika typer av bjälklag och bärande innerväggar2023Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Byggnadsdelar av hållbara material är viktigt för att uppnå de miljömål som satts upp för Agenda 2030 samt för att skapa ett mer hållbart samhälle. För att bidra till detta analyserades och jämfördes olika uppbyggnader av bjälklag och innerväggar tillverkade av trä. Byggnadsdelarna ska uppnå de tekniska kraven som ställs och hur de olika skiljer sig i kostnad och CO2e-utsläpp vid olika spännvidder och laster. Bjälklagen och innerväggarnas olika materialskikt kontrollerades för att undersöka vilket skikt som bidrar med det högsta utsläppet, för att göra det möjligt att utveckla materialet i framtiden. En jämförelse utfördes för bjälklagen tillverkade av korslamminerat trä och betonghåldäckets kostnad och undersöka om användningen av träbjälklaget blir mer lönsamt. 

    Arbetet utgick ifrån fyra alternativa typer av bjälklag och två typer av bärande innerväggar till en skolbyggnad som Sweco ansåg intressanta att utvärdera. Utformningen på dessa bjälklag och väggar bestämdes i detalj genom val av materialskikt för att uppfylla de tekniska kraven och dimensionering av de bärande delarna i konstruktionerna. För bjälklagen dimensionerades stommen utifrån spännvidder mellan 4–12 meter och väggarna dimensionerades utifrån antagandet att skolbyggnaden bestod av fyra våningsplan. Efter att detaljutformningen bestämts beräknades materialvolymerna som sedan låg till grund för kostnadsberäkning och klimatpåverkan. Det fyra bjälklagstyperna var baserade på KL-trä, limträ, lättbalk och betonghåldäck som bärande konstruktion för skolbyggnaden medan de två väggtyperna konstruerades av KL-trä och reglar.

    Resultatet bidrar till att undersöka vilken stomme som är mest effektiv utifrån ett kostnads och klimatperspektiv samt ge ökad kunskap om trästommars egenskaper. Jämförelsen visar att bjälklagen tillverkade i trä är mer gynnsamt ur ett klimatperspektiv för alla träbjälklag medan kostnaden varierar beroende på vilket träbjälklag som kontrollerades. Genom att undersöka kostnaden utifrån ett framtidsperspektiv kan trästommar vara mer lönsamt. För bjälklagen var limträbalken fördelaktigast för kostnaden för alla spännvidder. KL-trät var dock mest gynnsam utifrån utsläppet för spännvidderna 4–8 meter medan lättbalken hade det högsta utsläppet. För innerväggarna var kostnaden högst för KL-trät men hade det lägsta utsläppet upp till tre våningar därefter hade regelstommen ett lägre utsläpp. 

    De slutsatser som kan dras utifrån arbetet är att trästommar är mer lönsamt ur ett hållbarhetsperspektiv dock har trä en relativt hög kostnad i dagsläget. Limträbjälklaget och regelväggen har en relativ låg kostnad i jämförelse med de andra och ett lågt utsläpp som skulle kunna användas för att bidra till de uppsatta klimatmålen. En minskad kostnad av trä skulle göra att respektive träbjälklag är mer lönsamma utifrån både kostnaden och klimatet i jämförelse med betong. 

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  • 46.
    Agarwal, Ayush
    et al.
    Department of Information Technology, Delhi Technological University, Delhi, India.
    Chivukula, Aneesh Sreevallabh
    School of Computer Science, FEIT, University of Technology Sydney, Sydney, Australia.
    Bhuyan, Monowar H.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Jan, Tony
    School of Computer Science, FEIT, University of Technology Sydney, Sydney, Australia.
    Narayan, Bhuva
    School of Communication, FASS, University of Technology Sydney, Sydney, Australia.
    Prasad, Mukesh
    School of Communication, FASS, University of Technology Sydney, Sydney, Australia.
    Identification and Classification of Cyberbullying Posts: A Recurrent Neural Network Approach Using Under-Sampling and Class Weighting2020In: ICONIP 2020: Neural Information Processing: 27th International Conference, ICONIP 2020, Bangkok, Thailand, November 18–22, 2020, Proceedings, Part V, Thailand: Springer Berlin/Heidelberg, 2020, p. 113-120Conference paper (Refereed)
    Abstract [en]

    With the number of users of social media and web platforms increasing day-by-day in recent years, cyberbullying has become a ubiquitous problem on the internet. Controlling and moderating these social media platforms manually for online abuse and cyberbullying has become a very challenging task. This paper proposes a Recurrent Neural Network (RNN) based approach for the identification and classification of cyberbullying posts. In highly imbalanced input data, a Tomek Links approach does under-sampling to reduce the data imbalance and remove ambiguities in class labelling. Further, the proposed classification model uses Max-Pooling in combination with Bi-directional Long Short-Term Memory (LSTM) network and attention layers. The proposed model is evaluated using Wikipedia datasets to establish the effectiveness of identifying and classifying cyberbullying posts. The extensive experimental results show that our approach performs well in comparison to competing approaches in terms of precision, recall, with F1 score as 0.89, 0.86 and 0.88, respectively.

  • 47. Agogo, George O.
    et al.
    van der Voet, Hilko
    van 't Veer, Pieter
    Ferrari, Pietro
    Muller, David C.
    Sanchez-Cantalejo, Emilio
    Bamia, Christina
    Braaten, Tonje
    Knuppel, Sven
    Johansson, Ingegerd
    Umeå University, Faculty of Medicine, Department of Odontology.
    van Eeuwijk, Fred A.
    Boshuizen, Hendriek C.
    A method for sensitivity analysis to assess the effects of measurement error in multiple exposure variables using external validation data2016In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 16, article id 139Article in journal (Refereed)
    Abstract [en]

    Background: Measurement error in self-reported dietary intakes is known to bias the association between dietary intake and a health outcome of interest such as risk of a disease. The association can be distorted further by mismeasured confounders, leading to invalid results and conclusions. It is, however, difficult to adjust for the bias in the association when there is no internal validation data. Methods: We proposed a method to adjust for the bias in the diet-disease association (hereafter, association), due to measurement error in dietary intake and a mismeasured confounder, when there is no internal validation data. The method combines prior information on the validity of the self-report instrument with the observed data to adjust for the bias in the association. We compared the proposed method with the method that ignores the confounder effect, and with the method that ignores measurement errors completely. We assessed the sensitivity of the estimates to various magnitudes of measurement error, error correlations and uncertainty in the literature-reported validation data. We applied the methods to fruits and vegetables (FV) intakes, cigarette smoking (confounder) and all-cause mortality data from the European Prospective Investigation into Cancer and Nutrition study. Results: Using the proposed method resulted in about four times increase in the strength of association between FV intake and mortality. For weakly correlated errors, measurement error in the confounder minimally affected the hazard ratio estimate for FV intake. The effect was more pronounced for strong error correlations. Conclusions: The proposed method permits sensitivity analysis on measurement error structures and accounts for uncertainties in the reported validity coefficients. The method is useful in assessing the direction and quantifying the magnitude of bias in the association due to measurement errors in the confounders.

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  • 48.
    Agrell, Daniel
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Optimerad design och tillverkningsmetod av koncentrerande solfångare2015Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    The sun is our most important source of energy for us to be able to cope with the evermore pressuring climate threats. This has always been very clear for Absolicon Solar Collector AB in Härnösand, developers of concentrating solar collectors. The company has so far produced solar collectors which can produce both thermal and electrical power for mid-sized installations such as hotels and hospital. Now however, they are changing direction. Absolicon wants to address the many bigger industries with a demand for steam, in countries rich with solar radiation. Absolicon also wants to develop a production line for production of their solar collector, for deployment in the countries where the demand is the biggest.

     

    In a project partially financed by the Swedish energy department, a demonstrational production line will be built in Härnösand. The production line will be used to build a demonstrational field at HEMAB (Härnösands Energi och Miljö AB) with a new generation of solar collectors, optimized for steam production. The solar collectors built today has a problem with the reflector not getting an optimized shape throughout the whole collector. This has to be rectified since the demand on the shape of the reflector is higher on the new generation of solar collectors. This Is due to the use of a smaller receiver. Furthermore a mounting carriage using a new production method is to be developed for the production line. The mounting carriage should, by using vacuum, form and fixate the reflector of the collector while it also optimizes its shape.

     

    Tests was performed to examine how to optimize the shape of the reflector. A test rig was used to examine how a thin sheet of metal can be formed and fixated using vacuum while developing an optimized production method. A prototype carriage for production of 2 m long collectors using the new method was designed and constructed for evaluation.

     

    The results of the evaluation showed that the developed method is working well and that a receiver diameter of 19 mm can be used. The method is based on letting the edges of the reflector sheet hang free, which eliminates unwanted tensions in the reflector.

     

    The prototype which was built is ready for upscaling to a 6 m mounting carriage which will be able to produce the new generation of solar collectors for the demonstration field. A mounting process for production of solar collectors in a production line has been proposed which can shorten the mounting time and work load to less than 45 minutes and 1-2 persons per collector.

    The full text will be freely available from 2025-09-01 20:46
  • 49.
    Agrell, Elias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Analys av massapumps- och mixerarbete vid Metsä Board Sverige AB, Husums Fabriker: Energibesparingsåtgärder vid blekeri 4 & 5 med jämförelse mot ny utrustning2014Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    Husums plant has a selection of different pulp pumps at bleaching plant 4 and 5. The displacement- (HC-pump, Sund Defibrator PTD-60) and centrifugalpumps (MC-pump, MCA 42-200, MCP 30/20) are of interest in this report. The centrifugal pumps are controlled by throttle valves, which result in an energy loss. Chemical mixers are used to mix ClO2 into the pulp before proceeding into a holding tower where the bleaching process occurs.

    The energy demand of the different positions has been measured or calculated to be used in comparisons against new equipment. Quotations were requested and delivered from Valmet and Sulzer. The quotations were made with a production increase of 10 ADMt/h and plant compared to current equipment. Therefore energy need of the equipment in the quotation had to be recalculated to the same production output as when measurements were conducted to be comparable. Quotation of the pumps assumes the use of frequency inverters.

    A deeper investigation was made for 441PU255 which is located at bleaching plant 4. The drop leg level of the pump is controlled via a throttle valve. A frequency inverter is installed but not utilized to maintain constant pulp level in the drop leg. This was due to physical changes in the process not being compensated for in the control system. This caused the drop leg level to oscillate when automatic control was used. As a workaround the drive had been set at a constant speed. To investigate the potential savings, an attempt was made in which the speed was lowered from 1520 rpm to 1100 rpm, resulting in a power reduction of 82 kW or 342,081 Sek per year at a production of 36 ADMT/h. The experiment was done with slightly lower production output than desirable; because of this, savings will decrease slightly at higher outputs.

    Comparisons showed that considerable amounts of energy could be saved at all positions. However the investment cost is high and therefore favorable payback times can only be seen for some of the positions. The MC-pumps are oversized and in need of constant throttling therefore the majority of the energy savings is made through the installation of frequency inverters and not the pump upgrade.

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    Analys av massapumps- och mixerarbete vid Metsä Board Sverige AB, Husums Fabriker
  • 50. 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.

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