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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Energiuppföljning på två flerbostadshus i centrala Skellefteå. / Energy Auditing of two Multistorey Apartment Buildings in Skellefteå

Burman, Sebastian January 2018 (has links)
One third of Sweden's energy use is used by residential and commercial buildings, of which nearly 60 % go to heating. Opportunities are great for using energy more efficiently and there is a great potential to save energy by improving the construction of the building. The EU places higher demands on energy use and means that monitoring of energy use is becoming increasingly important. From 2021, all new production of buildings in EU Member States will be "close to zero energy houses". The definition of "near zero energy house" has not yet been established in Sweden, but in a throw-out of BBR is the requirement to tighten by 40 % discussed. Efforts to get more energy-efficient buildings are under way and are being carried out in close collaboration with BBR.   This degree project has been carried out on behalf of Skebo, where the goal is to establish the real specific energy use in operation for two properties in Skellefteå, Ringduvan and Odenskrapan. Compare and analyze deviations from projected specific energy use. Ringduvan was ready for occupation in spring 2014 and Odenskrapan in early 2016.Both buildings have electricity and district heating from Skellefteå Kraft. Ringduvan is projected by NCC and Oden of Lindbergs Energi & VVS AB.   Sveby ("Standardize and Verify Energy Performance in Buildings") is a development program run by actors in the construction and real estate industry. Svebys aim is to develop an industry standard that increases the accuracy of the project between projected and real energy use. With increased knowledge of user-related use, a standardized approach, energy monitoring and enhanced cooperation between actors, the goal is to reduce the deviations. Operators in the industry may choose to enter into a Sveby agreement, which includes a common method of procurement, design and verification.   The projected specific energy use for Ringduvan is 76 kWh/m2,year and the real is 101 kWh/m2,year. Odenskrapan projected is 53 kWh/m2,year and the real is 93 kWh/ m2,year. That is, the specific energy use exceeds the estimated energy consumption by 33 % for Ringduvan and 75 % for Odenskrapan. This means that much more district heating and real estate is needed than expected.   In general, potential causes of higher energy use have been identified. But nothing has been confirmed and more work is required against the buildings in order to compare and identify the exact reasons.
142

Centralised Distribution Grid Energy Storage Systems : Placement and Utilisation for Grid Expansion Deferment

Andersson, Sebastian January 2018 (has links)
Following an ongoing change towards an increasingly renewable power generation system Swedish grid operators are facing several challenges in coming years. As authorities plan for the decommissioning of nuclear power an increased reliance on de-centralised energy sources such as photo-voltaic distributed generation (PVDG) is expected. A technology observed in some cases to accompany local power quality issues severe enough to impose grid expansion measures from distribution system operators (DSOs). Considering a combination of an indicative utilisation inefficiency of classical grid expansion measures and a recent year maturing of various energy storage technologies, this report sets out to evaluate the possibility of utilising centralised energy storage systems (ESSs) for deferment of classical grid expansion measures. For the purpose of identifying the most prominent problem scenarios of modern production- and consumption behaviours as well as the possible solutions offered by centralised ESSs, a literature review of journal articles and technical reports was conducted in combination with a case-study of an existing urban grid operated by Umeå Energi Elnät AB (UEEN). The work regarding ESSs is directed with specific focus towards evaluating which ESS services can potentially facilitate grid expansion deferment and what ESS placement is advisable for efficient utilisation. Assessing possible grid safety implications, potential for peak load shaving and the presently most suitable energy storage technology was also within the scope of the study. The literature review reveals PVDG induced feeder line over-voltage and transformer overload the most likely and previously observed implications imposing grid expansion measures. The former more prominent in elongated, typically rural, grids and the latter in more densely populated urban grids. For deferment of over-voltage related grid expansion measures a centralised ESS can be utilised for voltage support provided placement is made close to the affected grid section, presumably far out the affected feeder line. This result is coherent throughout the reviewed literature and is supported by the results of the case-study. Distribution transformer overload and its imposed grid expansion measures can be deferred through load re-allocation and peak load shaving, two services proven achievable by centralised ESSs and the capacity for which increases if ESS placement is made closer the distribution transformer. Provided present regulatory and standards are adhered to upon installation, significant negative impact of centralised ESSs on distribution grid safety can be avoided. Most energy storage technologies, including battery based energy storage technologies indicated from the literature review providing the most suitable characteristics for use in centralised distribution grid ESSs, utilise well established systems for grid connection hence no presently unsolvable grid safety implications are identified. Technical reports of real applications of centralised ESSs reinforce this argument as successful implementation without ESS caused grid safety implications have been achieved in the Swedish distribution grid in the past.
143

Natriumbaserat Flödesbatteri : Experimentell undersökning av natriumbaserat flödesbatteri och analys av möjlig applicering i tunga fordon

Tjäder, Marcus, Ishak, Busuladzic January 2018 (has links)
No description available.
144

SPICE modeling of ultrasound systems : improvements and verifications

Johansson, Jonny January 2001 (has links)
The success of modern electronics is built on the possibility to accurately predict system behavior by the use of simulation tools. This paradigm can be extended to components such as sensors attached to the electronics. The ability to simulate both sensors (mechanical components) and electronics together renders possible effective optimizations at system level, i.e. minimizing size, cost and power consumption. In this thesis the simulation of a combined electronics and ultrasound sensor system is explored. The environment used is compatible with the electronic simulation tool SPICE. Improvements and verifications of existing SPICE models for ultrasound equipment is described, and applied in the design of integrated analog electronics for an ultrasound measurement system. Emphasis is put on the interdependence between acoustic performance and electronics design. The goal is to improve precision in the simulations to a level where real systems can be implemented from simulation results alone. The thesis is divided into introduction and three attached papers. In the introduction, an overview of ultrasound devices, measurement technology and simulation is given. Tools and design flow for analog integrated circuits are discussed. The first paper shows that system simulations can be used to minimize the size of the transistors used to excite an ultrasound transducer, while keeping maximum output ultrasound energy. A design of an ASIC (Application Specific Integrated Circuit) driver stage for piezoelectric crystals is made and performance of the system is predicted using system simulations. Measurements and simulations are compared, showing that the optimum transistor size can be chosen from simulation data with very good precision. The goal with paper number two is to achieve absolute amplitude correctness in PSpice simulations of ultrasonic systems. Previously published models of the ultrasound propagation medium include viscoelastic loss but disregard loss due to diffraction, i.e. beam spreading. This paper presents a method to include diffraction loss in the models. Measurements and simulations have been performed using a pulse echo system in water. Results show that the simulated amplitude of the returned echo differs less than 10% from measured values in both near and far fields. In paper number three, the influence of parasitic electrical components on measurements and simulations is investigated. It is shown that simulation of excitation pulses can be done with very high accuracy if parasitics are taken into account. The coaxial cable which connects the electronics and the transducer represents one of the major parasitic components in the system. As the cable length is varied, pulse echo amplitudes and time delays shift. It is shown that simulations can be used to predict these effects with good accuracy. / Godkänd; 2001; 20070313 (ysko)
145

Human Motion Analysis for Creating Immersive Experiences

Abedan Kondori, Farid January 2012 (has links)
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.
146

Development of a novel test system for the ATLAS-upgrade at CERN

Lycksam, Andreas, Andersson, Martin January 2018 (has links)
The ATLAS-upgrade is a project with the endeavors to enhance the performance of the ATLAS detector located at CERN. The intention of this project is to enable testing of the upgraded components locally at Ångströmlaboratoriet, Uppsala University, in cooperation with CERN. A power supply system  was constructed to provide the correct voltage to the new electronic hybrid circuits. The hybrids need to be tested under the right conditions hence governing the features of the system. A graphical user interface with included software that controls and monitors the hardware in the system was developed. To ease connection of the test system, a backplane power circuit board was designed for the power supply cards. / ATLAS-upgrade experiment
147

Implementing a Probe with Laser Doppler and Heater

Marneson, Karin January 2017 (has links)
With laser Doppler flowmetry, blood flow can be measured in the smallest blood vessels in the body. Perimed AB is a company that develops instruments for microvascular diagnostics and want to develop a 15-mm probe with laser Doppler and heater. By using a new component, a combined VCSEL and photodetector from Kyocera, a prototype for the 15-mm probe is designed to measure blood flow. The results show that the signal is sufficient for optical analysis. Further work is necessary to determine if the 15-mm probe can be realized.
148

Deterministic Analysis of the Accuracy in FFT Hardware Architectures

Guinart Platero, David January 2012 (has links)
This Master Thesis studies the different quantization effects in hardware architecture due to the use of finite word lenght. This master thesis gives a deterministic analysis with relation to the accuracy and presents a relationship between input bits and coefficient bits for minimizing recourses and to obtained the best relation with the accuracy. Furthermore, the objective of this mater thesis is to find a direct relation between the input bits and coefficient bits. This can be used as guide for the design of FFT hardware architectures
149

Likströmsnät i byggnader : En genomförbarhetsstudie för ett potentiellt smartare och energieffektivare elsystem / DC-grids in buildings : A feasibility study of a potentially smarter and more energy efficient electrical system at the Swedish market today

Wennlund, Samuel January 2018 (has links)
Byggnaders interna distributionsnät är idag liksom resten av elnätet sedan länge växelströmsbaserat. Idag använder dock det mesta i en byggnad likström vid slutanvändningen. Dessutom ökar användningen av solceller, batterilager och elbilar snabbt och alla dessa bygger också på likström. Likströmsnät i byggnader är en idé om att minska antalet omvandlingar mellan växelström och likström inom byggnaden, istället kan man ha en effektivare centraliserad likriktning, därmed kan man minska omvandlingsförlusterna. Syftet med detta arbete är att undersöka fenomenet likströmsnät samt den svenska marknaden för det. Detta för att komma fram till görbarheten och möjligheterna för ett likströmsnät i en kontorsbyggnad idag. Genom en marknadsundersökning har dagens lösningar och kunskap i Sverige kartlagts, detta har sedan använts för att ta fram en rekommendation om vilka delar i byggnaden som kan kopplas till och drivas av ett likströmsnät. Enligt undersökningen finns idag möjligheter på den svenska marknaden att bygga ett distribuerande likströmsnät på 350VDC eller +/-380VDC (760VDC) beroende på vilka fördelar som prioriteras i det aktuella projektet. Då inte alla elapparater kan matas med likström idag blir en hybrid mellan växelström och likström det rimliga valet. Delar som kan drivas med likström idag är belysning, ventilation, laptops, mobiler, surfplattor, servrar och mindre kontorsapparater och telefoni. Eventuellt kan även värmepumpar och pumpar kopplas till likströmsnätet. Delarna som idag fortfarande behöver växelströmsmatning är kopiatorrummet, hissen, kökspentryt och garaget med elbilsladdare. / The internal distribution grid in buildings is, just like the rest of the grid, based on alternating current technology, even though today most of the electricity consumers in a building use direct current in their final stage. Furthermore the use of photovoltaics, battery systems and electric vehicles are increasing and they also use direct current. Direct current grids in buildings could be a way to minimize the amount of conversions between AC and DC within the building, instead the idea is to centralize the rectification and thereby lower the conversion losses. The purpose of this thesis is to investigate the phenomenon of DC-grids and the Swedish market for it. This is done with the purpose to explore the feasibility and possibilities of a DC-grid in an office building today. Through a market investigation the solutions and knowledge to this day has been summarized, and is then used to find a recommendation for what parts in an office building that can be supplied with direct current from a DC-grid. According to the investigation there are solutions in the Swedish market for building an internal DC-grid at 350VDC or +/-380VDC (760VDC) depending on the priority of the project in question. Since not all electricity consumers can use DC a hybrid between AC and DC is most relevant today. Electrical units that can use direct current today are lighting, ventilation, laptops, mobile phones, tablets, servers and smaller office appliances and telephony. Possibly heat pumps and other pumps might also be able to be supplied by direct current. Electrical units that still need to be supplied by AC are copier rooms, elevators, kitchen areas and garages with the EV chargers.
150

Performance and Improvement Investigation of Accelerated Temperature Change Test.

Narri, Vandana January 2018 (has links)
This thesis is focused on Accelerated Temperature Change Test (ATCT). This test is performed in order to deteriorate and age a product in a faster than natural way. The ATCTs are primarily controlled with four parameters: the temperature range (∆T), ramp rate (RR), dwell time (DT) and number of cycles in test ( . A comprehensive investigation was carried out to analyze the performance and functionality of the cabinet, used for performing ATCT. This was achieved by performing repeated measurements in the empty cabinet with different combinations of temperature range (∆T) and dwell time (DT). The test parameters are normally adjusted according to values given in the standards common in automotive environmental testing and also according to the thermal properties and size of the tested components. In this investigation, four different standards for accelerated testing were taken into consider. They are TB1900, ISO 16750-4:2010 (International Organization for Standardization), IEC 60068-2-14 (International Electrotechnical Commission) and The GMW3172: User Guide. From each standard, each parameter definitions are illustrated. Practical tests were executed on three different types of components and with different test conditions. A suitable experimental-setup was prepared to record the temperature measurements on/in the DUT (Device Under Test). This experimental-setup was designed using thermocouples (Type - K) and DEWESoft. The results from the test were used to analyze the deviation between the standards and practical testing. This comparison helps in understanding the required improvements in the test parameters values i.e. the cabinet parameter settings or the test conditions. The values assigned for each parameter before the test are called Cabinet Parameter Settings (CPS). The temperature readings from the DUT are recorded and plotted after ATCT. Based on these ATCT measurements, optimal values of the test parameter are estimated. These are called Estimated Parameter Values (EPV). A significant deviation is observed between CPS and EPV. From these EPV, an acceleration factor (AF) for each test is calculated using two different life prediction models i.e. (i) Coffin-Manson and (ii) Norris Landzberg. And using this AF, an evaluation of the “number of cycles in the field (Nf)” with certain “number of cycles in the test (Nt)” is made. This evaluation helps in understanding the effect of parameter values during the test on the acceleration conditions. A simple aluminum box (one of the test component) is replicated into a simple structure, to implement in COMSOL Multiphysics Simulations. When the simulation results show good agreement with practical results, then simulations are recommended to be used to find the proper test conditions and test parameter values. Further, the simulations are used to find the sensitive point in/on the component. These simulations take some reasonable efforts. Index Terms— Acceleration factor, Dwell time, Fatigue failure, Accelerated temperature change test, Stress level, Temperature range, Coefficient of Thermal Expansion.

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