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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.
311

Lokal kompensering i Mellanspänningsnät

Bassam, Diraoui January 2017 (has links)
Vid byte av luftledningar mot jordkabel kommer kapacitiva felström-mar att genereras. De kapacitiva felströmmarna ökar med större kabel-area. Rapporten behandlar problematiken med för stora bidrag av kapacitiva jordfelströmmar och dess inverkan på hela elnätet. Arbetetsfrågeställningar kommer att behandla utlokaliserad kompen-sation, oselektiv reläskyddsfunktion och skillnaden mellan långa led-ningar och stora nät. Syftet med uppsatsen är att belysa behovet av att utlokalisera kompensationen, bestämma antal och täthet av spolar som minskar kapacitiva strömmar på Alnön, samt titta på skillnaderna mellan långa och många ledningar både på tätortens och också lands-bygdens nät. I teoridelen tas teorier om olika typer av jordfelsskydds funktioner upp, lokal kompensering och skillnader mellan korta och långa markkabelns nät. Projektet är utfört genom utforskning av de metoder som används för att begränsa dem genererade kapacitiva felströmmen vid användning av markkablar. I slutsatsen kommer jag fram till att för förbättring av ledningsskydds-funktion på landsbygden måste kapacitiva strömmar transporteras genom kabeln i kortare sträckor. Detta kommer att minska spänningsfal-let över kabelns resistans och reaktans, eller att fördela nätet till små fack.
312

Optimization of Vehicle Powertrain Model Complexity for Different Driving Tasks

Zetterlund, Olof January 2015 (has links)
This master thesis has examined how the understanding of different driving tasks can be used to develop a suitable powertrain model to be used in the Sim III simulator at VTI. Studies performed in the simulator have been statistically analyzed using parameters commonly used to describe driving patterns in drive cycles. It has been shown that the studies can be divided into three driving tasks: "High constant velocity", "High velocity with evasive maneuver", and "Mixed driving". Furthermore, a powertrain model from a former master thesis has been further developed. The new model utilizes a 3D torque map that takes engine speed, accelerator pedal position and gear as input. Using measurements, from the chassis dynamometers laboratory at LiU, that resembles the derived driving tasks, it has been shown that the performance of the new model has significantly increased for high velocity driving and during maximum acceleration. However, when using the clutch at low speeds and gears the model still performs poorly and needs further development.
313

Life Time BoM : BoM-effektivisering ur ett Lean-perspektiv. / Life Time BoM : Streamlining BoM-handling from a Lean perspective.

Holmberg, Marc January 2019 (has links)
Beskrivning och analys av ett effektiviseringsprojekt på Sanminas fabrik i Örnsköldsvik. Projektet ska effektivisera BoM-hanteringsprocessen primärt genom tre förändringar. 1: Införa en BoM istället för flera. 2: Datorstöd istället för manuell hante-ring. 3: En konform hantering för alla projekt. Analysen av projektet grundas påLean-principer. Centrala begrepp som Lean och BoM beskrivs. En kvalitativ studiegenomförs med en fokusgrupp bestående av komponentingenjörer. Resultatet fråndenna ligger till grund för analysen. Ny metodik tolkas som effektivare än gammalmetodik på alla tre relevanta punkter. Ny metodik löser dock inte alla de bristersom finns i den gamla processen. Detta då de verktyg avsedda för interna processerinte har större inverkan på externa problem. Förändringarna tolkas som ett steg moten mer Lean BoM-hanteringsprocess. Fullständig analys kommer kunna genomförasnär ny metodik är implementerad. Diskussion kring tolkning av data och osäkerhet i analys av densamma. Detta då datan är kvalitativ.
314

Dataöverföring mellan PLC och trådlös enhet

Michailidis, Konstantinos January 2019 (has links)
Syftet med studien har varit att analysera produktionsrelaterad teknik för att utveckla en kostnadseffektiv lösning för dataöverföring mellan maskinens styrsystem och trådlösa enheter. Anledningen till att trådlösa metoder valdes för arbetet var att kunna reparera de olika givarnas fel och att ingripa i sensorerna i realtid. Vid användning av en bärbar enhet måste felet repareras och testas på maskinen. Undersökningen innefattar även att utveckla en lämplig metod för att trådlöst överföra uppsamlade mätdata till serverns miljö där mätdata ska lagras för att kunna presentera senare diagram, tabeller och använda mätdata för statistiska beräkningar. De rekommenderade metoderna som ska undersökas bör sedan appliceras i en produktionsmiljö med högkvalitativa säkerhetskrav. Anledningen till detta är att minimera produktionsstopp i samband med kvalificerad reparation. Många små och medelstora företag har inte råd att investera i dyr teknik, som i sin tur måste uppdateras regelbundet för att rymma ny utrustning, plattformar och utbilda underhållspersonal För dem kan det vara bra att installera ett billigt system som enkelt kan installeras och implementeras i sitt befintliga ekonomiskt styrsystem med minimikostnader med hjälp av oberoende varumärkesvaror. Resultaten av en systemundersökning har visat att dataöverföring med vissa metoder som kräver mindre säkerhetskrav och hög energiförbrukning blir mer instabila och mer mottagliga i framtiden. / The purpose of the study has been to analyze production-related tech-nology to develop a cost-effective solution for data transmission be-tween the machine's control systems and wireless devices. The reason why wireless methods were chosen for the work was to be able to repair the various donors' faults and to intervene in the sensors in real time. When using a portable device, the fault must be repaired and tested on the machine. The survey also involves developing a suitable method for wirelessly transmitting collected measurement data to the server's environment where measurement data is to be stored in order to present later charts, tables and use measurement data for statistical calculations. The recommended methods to be examined should then be applied in a production environment with high quality safety requirements. The reason for this is to minimize production stoppages in connection with qualified repair. Many SMEs cannot afford to invest in expensive technology, which in turn needs to be regularly updated to accommodate new equipment, platforms and training maintenance staff For them, it may be good to install a cheap system that can be easily installed and implemented in its existing financial control system with minimum costs using independent branded goods. The results of a system survey have shown that data transmission with certain methods that require less security requirements and high energy consumption becomes more unstable and more susceptible in the future.
315

An Analysis of Cloud-Based Machine Learning Models for Traffic-Sign Classification

Lindeman, Victor January 2019 (has links)
The machine learning method deep neural networks are commonly used for artificial intelligence applications such as speech recognition, robotics, and computer vision. Deep neural networks often have very good accuracy, the downside is the complexity of the computations. To be able to use deep neural network models on devices with less computing power, such as smart-phones e.g., can the model run on the cloud and send the results to the device. This thesis will evaluate the possibility to use a smart-phone as a camera unit with Google’s open source neural network called Inception, to identify traffic signs. The thesis analyzes the possibility to move the computation to the cloud and still use the system for real-time applications, and compare it to running the image model on the edge (the device itself). The accuracy of the model, as well as how estimations of future 5G mobile networks will affect the quality of service for the system is also analyzed. The result shows that the model achieved an accuracy of 88.0 % on the "German traffic sign benchmark" data set and 97.6 % on a newly created data set (data sets of images to test the neural network model on). The total time when using this system, from sending the image to receiving the result, is > 2 s. Because of this can it not be used for any application affecting traffic safety. Estimated improvements from future 5G mobile networks could include reduced communication delay, ultra-reliable communication, and with the higher bandwidth available could the system achieve a higher capacity if that would be required e.g. sending higher quality images.
316

Modular SoC-design : Minimizing area and power consumption

Larsson, Mattias January 2018 (has links)
This is the main report for Mattias Larsson’s degree project for the Master’s programin System-on-Chip. The main part of this project has been to design a modularMPSoC-unit (Multi Processor System on Chip) for reuse in different typesof projects. A SoC includes and interconnects a processor and FPGA in one chip.MPSoC is an extension of SoC including more than one processor. Zynq Ultra-Scale MPSoC has been used in this design which comes in three different versionsCG, EG and EV. In this project the EG version has been used, this versionhas a quad-core ARM Cortex-A53 platform, two Cortex-R5 real-time processorand Mali-400 MP2 graphics processing unit.The modular MPSoC-unit is designed to be used in a project as the main computingunit. A modular unit has to be general enough to fit almost all demandsbut as small as possible. The area usage is always an important question butsince the modular MPSoC-unit will be designed once and have a certain size andshape its overall area coverage determines how usable it will be. It is thereforhighly important to keep the area as small as possible.This project has been focused on the design of a modular SoC-unit with focuson a schematic-level. This report raises and answers question as too which extentsit is worth using certain types of DC/DC regulators, on-chip functionalityetc. A big part of the design work has been dedicated towards the DC/DC regulationand generation of voltages to supply the circuits. The MPSoC requires anumber of voltage levels of which some supplies can be tied together while othersare analog and sensitive to digital switching noise on the supply. This reportinvestigates the possibilities to use a simple ferrite bead filter for sensitive loadssharing the same supply. Extra work has gone into trying to reduce the numberof regulators. In order to design a safe and general power supply an estimation ofthe power consumption has to be done. This report shows how to find, use and estimatethe power consumption for the main power consumer in the system. Withthis information a generic modular SoC-design approach can be found.
317

En ljusbåges energi och konsekvenser : Att öka säkerheten och belysa konsekvenserna vid en ljusbåge på Mörrums Bruk

Dahlskog, Robert, Arnell, Martin January 2019 (has links)
Syftet med den här rapporten är att uppmärksamma elriskerna med ljusbågar som i många fall glömts bort, vilka risker man utsätter sig för när man oskyddad rör sig i närheten av transformatorer och ställverk. Rapporten ger också en överblick av vad som behöver förbättras på Södra Cell Mörrum för att öka elsäkerheten och undvika elskador. Ett mål är även att med hjälp av beräkningar kunna välja rätt skyddskläder och ha möjlighet att avgöra när en anläggning ska göras spänningslös vid elunderhållsarbete. Ett beräkningsblad har skapats i Excel för att enklare räkna ut energierna på olika transformatorer.
318

Wireless charger

Dyi, Barry, Dondogori, Bruce, Hägerbrand, Jonathan January 2018 (has links)
This project focuses on wireless power transmission (WPT). More specifically, the use of inductive coupling with resonance. The resonance phenomenon makes the transfer of power more efficient, through matching the inductive and capacitive reactances thus eliminating the reactive losses. A wireless smartphone charger has been built with this method for demonstration, and some tests were performed. The charger consisted of a primary “transmitting circuit” and a secondary “receiving circuit”. The built charger did not achieve full resonance, but it achieved longer wireless transmission distance compared to that of a commercial wireless phone charger. The first experiment confirmed the DC/AC characteristics of the transmitting circuit, and the ability for the voltage to oscillate at a higher level than the input voltage. The voltage oscillated at 45kHz. The second experiment confirmed the AC/DC characteristics of the receiving circuit, and the ability to regulate the voltage to a constant 5V. The minimum required input voltage for the receiving circuit, to achieve a constant 5V output, was approximately 6V. Frequencies from 100Hz to 350kHz were tested and it had no severe impact on stability of the output voltage. The third and last test used both circuits, and showed the relationship between input voltage and transmission distance. The maximum distance achieved for the complete device was ~4.3cm at an input voltage of ~20V. When having the coils touch (Transmission distance ~0cm), the minimum required voltage was 6.6V, whereas a commercial wireless charger needs 5V.
319

Design and construction of electronic control unit

Hansson, Johan, Bothén, Christian January 2018 (has links)
The main objective of this project was to create a new, future-proofed, electroniccontrol unit for a test station at GE Healthcare in Uppsala. The control unit was tobe created in cooperation with the technical consultant firm Rejlers. The project consisted of two parts, one investigation part and one design part. The investigation part consisted of examining the previous control unit and its connection between the quality control station and the host computer. This examination resulted in a specification of requirements which was used as a basis in the design of the new control unit. The design part consisted of finding durable and reliable components that met the specification of requirements. During the design process the work was documented and compiled in a technical documentation for the control unit. The project resulted in a new control unit that was improved by using a programmable logic controller that was directly compatible with LabVIEW, moving external power supplies inside the control unit to limit the number of cables and adding cartridge fuses for safety. It also resulted in a full technical documentationof the unit, facilitating future maintenance. The new control unit was considered to be future-proofed, but in order to consider the entire test station future-proofed the quality control station would have needed to be replaced as well. At the time this report was written, the new electronic control unit had been designed and was under construction.
320

Realize Smart City Applications with LoRaWAN Network

Wang, Bin January 2019 (has links)
Internet of Things is an important part of realizing smart cities, this article introduces a proposal to build an Internet of Things system with LoRaWAN to achieve diverse smart city applications. There are three problems proposed and resolved in this research, how to maximize wireless devices’ lifetime with LoRa protocol characters, how to choose the gateways’ location for improving the efficiency and reduce costs, and about a good way to set up network servers to balance performance and consumption to implement in smart city applications. The IoT platform is built completely and running three applications on it in this research, Smart Parking, Smart Building Monitoring and Smart Sewage Monitoring. The methods of build platform and set applications are also explained in this article.

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