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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.
401

Hashing algorithms : A comparison for blockchains in Internet of things

Dahlin, Karl January 2018 (has links)
In today’s society blockchains and the Internet of things are two very discussed subjects this has led to thoughts about combining them by using a blockchain in Internet of things. This objective of this study has been to solve the problem which hashing algorithms is the best for a blockchain used in an Internet of things network. This have been done by first selecting a few hashing algorithms and setting up a scenario where a blockchain can be used in an Internet of things network. After that I specified what to compare, speed, input length and output length. The study has been conducted with the aid of literary studies about the hashing algorithms and a program that implements the algorithms and tests their speed. The study has shown that out of the selected hashing algorithms MD5, SHA-256, SHA3-256 with the conditions specified for the study that the hashing algorithm SHA3-256 is the best option if speed is not of the utmost importance in the scenario since it is from a newer standard and do not have a max input length. If speed is the very important in other words if SHA3-256 is to slow then SHA-256 would be best for the Internet of things network.
402

Development of Fluidity Measurement Technique and Automation of Measurement Station : Developing the existing Fluidity Measurement Station by automating the operation and measuring the fluidity digitally with MATLAB Image Processing Tools. / Utveckling av Fluiditsmätningsteknik och Automatisering av Mätstation

Ullal, Pratheek January 2019 (has links)
Bryne AB has invented a device called Loop for measuring the fluidity of molten metal. Loop is made up of refractory fiber material and has a dimension of 196 sq.mm within which there is an engraved spiral shaped runway for the molten metal to flow. The distance traveled by the molten metal in the spiral determines its fluidity and is measured visually by the operator with the help of the spiral scale printed on the Loop. A workstation is used to support the Loop for an easier and better working environment. At present, the entire operation of fluidity measurement is done manually. The aim of the thesis is to develop an automatic workstation for the fluidity measurement and find a technique to measure the fluidity without human visual aid. Further, an attempt has been made to find a way to store and retrieve the measured values for future use.   The automation of the workstation is done with the help of Arduino Uno circuit board for electrical connections and Arduino IDE for programming the circuit. MATLAB image processing tool is used for measuring the fluidity digitally.   The prototype of the automated workstation is built and showcases the ability to reduce the time and operational errors. The automation of the unplugging operation saves up to 7 seconds.  The digital measuring of the fluidity with FLIR thermal camera and MATLAB image processing tool does not show significant improvement in accuracy in measurement, but it reduces the dependency on the expertise of the operator. There is an error of 12.7% from the actual fluidity value.
403

Model Based Catalyst Control

Irman, Svraka, Linus, Österdahl Wetterhag January 2019 (has links)
A one dimensional discretized model of a two brick three way catalyst (TWC) system was developed and implemented in MATLAB, Simulink and TargetLink in collaboration with Volvo Cars and Linköpings Universitet - ISY. The purpose of this thesis was to increase system understanding and create a model based TWC control for further development at Volvo Cars. A total of 50 states were modelled, including emission concentrations (O2, CO, C3H6, C3H8, H2, NOx, CO2, H2O), temperature and oxygen buffer level (OBL). A model based control structure was implemented in the form of five separate PID-controllers enabling possibilities to control the OBL of each separate slice of each brick individually and through simple reference handling. The control structures includes anti-windup, feedforward control and feedback safety for model reset during sensor indication of leakage. Specific equipment and software used included MATLAB, Simulink, TargetLink, Volvo SULEV30 TWC and testing rigs. Overall increase in system understanding was achieved in comparison with contemporary TWC modelling and control, as well as sufficient system performance in regard to estimate emissions, simulation duration and pedagogical value. Concluding thoughts of the thesis revolve the complexity of the actual TWC modelling, parameter estimation as well as control. The model presented in this thesis has great potential of describing TWC systems but with great effort during parameter estimation. With ECU performance available in temporary vehicle production year 2019, a complex model may be combined with a simple control strategy whilst a simple model may be combined with a complex control strategy.
404

Controle ativo de vibrações em vigas utilizando controle feedforward e elementos espectrais /

Menão, Mauro Cesar. January 2014 (has links)
Orientador: Paulo José Paupitz Gonçalves / Banca: Vicente Lopes Junior / Banca: Bento Rodrigues de Pontes Junior / Resumo: Esse trabalho demonstra diferentes estratégias de controle de vibrações aplicadas à uma viga tipo Euler-Bernoulli com a restrição engastada-livre, envolvendo a técnica de controle de alimentação direta ou antecipado (Feedforward). O sistema dinâmica da viga é representado pelo método de matriz de impedância e a solução das equações do movimento utiliza elementos espectrais, cuja solução no domínio da freqüência não são aproximações como no usual método de lementos finitos, o que permite uma resposta precisa do sistema utilizando poucos elementos no modelo dinâmico. A posição da força e dos momentos de controle é estudada em termos em função de controle ótimo, visando maximizar o desempenho e evitar a instabilidade na estrutura, que é uma possibilidade nos controles ativos. As simulações são desenvolvidas para demonstrar o impacto da posição da força de controle ao longo da vida e a melhor distribuição dos pontos de sensores para o controle das vibrações. As simulações numéricas são realizadas com auxílio do software Matlab. A validação do modelo é realizada através de ensaio experimental de bancada e comparativo com o método de elementos finitos através do software CREO, da empresa PTC / Abstract: This document shows different strategies for vibration control applied to a cantilever Euler-Bernoulli beam involving the technique of Feedforward control. The dynamic system is represented by the impedance matrix method and the solution of the equations of motions is obtained using spectral elements, which have solutions in frequency domain that are not approximations as in the usual finite element method, allowing accurate systems response calculation using few elements. The position of control force and control moments is studied in terms of optimal control function, to maximize performance and avoid instability in the structure. The simulations are performed to demonstrate the impact of the control force position along the beam length and the best distribution of the sensors position. The numerical sumulations are performed with Matlab. Model validation is performed using experimental tests and commercial finite element software Creo / Mestre
405

Modeling and analysis of aluminum/air fuel cell

Unknown Date (has links)
The technical and scientific challenges to provide reliable sources energy for US and global economy are enormous tasks, and especially so when combined with strategic and recent economic concerns of the last five years. It is clear that as part of the mix of energy sources necessary to deal with these challenges, fuel cells technology will play critical or even a central role. The US Department of Energy, as well as a number of the national laboratories and academic institutions have been aware of the importance such technology for some time. Recently, car manufacturers, transportation experts, and even utilities are paying attention to this vital source of energy for the future. In this thesis, a review of the main fuel cell technologies is presented with the focus on the modeling, and control of one particular and promising fuel cell technology, aluminum air fuel cells. The basic principles of this fuel cell technology are presented. A major part of the study consists of a description of the electrochemistry of the process, modeling, and simulations of aluminum air FC using Matlab Simulink™. The controller design of the proposed model is also presented. In sequel, a power management unit is designed and analyzed as an alternative source of power. Thus, the system commutes between the fuel cell output and the alternative power source in order to fulfill a changing power load demand. Finally, a cost analysis and assessment of this technology for portable devices, conclusions and future recommendations are presented. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.
406

Elektrifiering av utskovsluckor : En fallstudie vid Lilla Ursen

Thune, Felicia January 2019 (has links)
Stand-alone or micro off-grid systems can be used to electrify remote areas when it is not economically justifiable to connect to the power grid. In Sweden there are several flood gates that are used to regulate the water level in hydropower dams, these dams are not always easily accessible. Furthermore, some flood gates are not electrified making the adjustment of the water level complicated and time consuming. An off-grid solution could be used to electrify the water level adjustment and this report aims to identify one remote dam, owned by the company VB Kraft, that could be electrified by implementing an off-grid solution. The report will also investigate which off-grid solution that is most applicable concerning maintenance demand, technical and economic aspects. Sensors for monitoring the status of the dam will also be identified which are required to preserve dam security. The chosen off-grid solution will be simulated on a yearly basis and the most appropriate size of the components will be specified. The report has been conducted by collecting material from the company, a literature study and by interviews and email conversations. Calculations have been performed by using MATLAB and Excel. The data is based on measurements from the Swedish Meteorological and Hydrological Institute. The result revealed that Lilla Ursen, a remote dam in Dalarnas county, is maneuvered often and therefore this study will investigate electrification of this dam. Out of the four alternatives (small wind, hydro and hydrokinetic power and PV), PV was considered the most suitable in an off-grid system combined with a lead-acid battery. Sensors considered important for dam security are water level and flow monitoring, position indicator for the flood gate, camera monitoring and a temperature sensor. It also important with a logger and transmitter. The battery is protected with a charge controller. A series of sensitivity analysis have been conducted and the result showed a large variation concerning the battery capacity and the modules area and peak power. For Lilla Ursen it is recommended with a PV module of 30 Wp and a lead-acid battery with a capacity of 280 Ah.
407

Ferramenta para modelagem de sistemas de comunicação. / Tool for modeling communication systems.

Zapata, Catalina 06 August 2007 (has links)
Este trabalho apresenta uma ferramenta para a simulação de sistemas de comunicação utilizando modelos em alto nível para cada um dos blocos empregados. A ferramenta é baseada em modelos comportamentais de blocos de Radio Freqüência (RF), o que reduz custos, tempo de simulação e permite um rápido diagnóstico de problemas precoces no projeto de um sistema de comunicação sem fio. O desenvolvimento de blocos, como o LNA (Low Noise Amplifier), o MIXER, o LO (Oscillator Local) e o PA (Power Amplifier), facilita a implementação de qualquer arquitetura de Transmissão e de Recepção. Para isso foram levados em consideração efeitos de ruído, não linearidade e ganho no modelo dos blocos. Com isto se espera que a ferramenta ajude no projeto de circuitos integrados de um sistema de blocos em cascata, onde o usuário possa selecionar, configurar e simular o sistema. Na utilização da ferramenta é indispensável um conhecimento prévio das características e especificações em nível de sistema. Assim, se poderão fazer mudanças nos parâmetros de blocos, que permitirá então analisar compromissos existentes entre ruído, ganho e distorção do sinal através de todo o caminho, antes mesmo de se ter uma resposta definitiva. A ferramenta de simulação é implementada em Simulink, que é um pacote (toolbox) de Matlab, amplamente utilizado no desenvolvimento de algoritmos e blocos de comunicação. A interação e ambiente gráfico da ferramenta facilitam o uso pelas pessoas envolvidas direta e indiretamente com o projeto de circuitos. Finalmente, para verificar a ferramenta desenvolvida foi feito um estudo de caso, onde se modelou e simulou o padrão Bluetooth. / This work presents a tool for the simulation of Communication Systems using macromodels for each block used. The tool is based on behavioral models of Radio Frequency (RF) blocks, which minimize cost, simulation time and allows a fast determination of problems in the early phases of the design of a Wireless Communication System. The development of blocks like the LNA (Low Noise Amplifier), the MIXER, the LO (Local Oscillator) and the PA (Power Amplifier), helps to implement any architecture for transmission and reception. For that, the effects of noise, non-linearity and gain in the behavioral model of the blocks were considered. With this, it is expected that the tool will help the design of integrated circuits of a system with cascade blocks, where the user can select, set up and simulate the system. In order to use the tool, previous knowledge of the characteristics and specifications of the system is necessary. In this way, it will be possible to change the parameters of blocks, allowing the analysis of tradeoffs between noise, gain and distortion of the signal through the system, before having a definite answer. The tool is implemented in Simulink, which is a toolbox of Matlab, normally used in the development of communication blocks and algorithms. The graphic environment of the tool allows a straightforward use for people involved directly or indirectly with the Circuit Design. Finally, in order to verify the developed tool, a case study was performed where the Bluetooth standard was modeled and simulated.
408

Modelamiento no lineal geométrico de vigas utilizando la teoría mejorada de primer orden mediante el método de elementos finitos / A geometrically nonlinear finite element model for Improved FSDT beams

Jorge Ponce, Xamir, Soncco Sinchi, Kurt Walter 04 1900 (has links)
El modelamiento de elementos estructurales se puede realizar actualmente en diferentes programas computacionales, las cuales se basan en conceptos y teorías de la mecánica estructural, las cuales se encuentran inmersas en su programación. Sin embargo, no siempre los conceptos en los programas comerciales cumplen con describir con mayor precisión el comportamiento de los elementos estructurales especialmente en el campo de la no linealidad. Por ello, se propone un modelo computacional del comportamiento no lineal geométrico de vigas, en base a un programa diseñado en MATLAB©, utilizando la formulación del Método de Elemento Finitos (FEM). Para la formulación del código del programa, se ha planteado el uso de la teoría de vigas de Timoshenko, considerándose esfuerzos cortantes en las vigas y una formulación Lagrangiana no lineal para deformaciones finitas. Se ha realizado la comparación entre el campo de desplazamientos propuesto por Timoshenko y la teoría clásica de vigas con la finalidad de poder comprobar la convergencia de teorías más robustas y explícitas en diferentes casos de vigas. El presente programa es capaz de calcular las deformaciones, esfuerzos y fuerzas internas de diferentes casos de vigas, los cuales han sido comparados con problemas benchmark de la bibliografía consultada para confirmar su convergencia. / The computational modeling of structural elements can be done in many different computational programs in the market today, that are based in concepts and theories of structural mechanics that are inside the code of the program. However, the concepts used in these programs do not always achieve an exact description of the structural behavior of structural elements, especially when it has no linear strain-displacement behavior. Therefore, this research describes a computational model of nonlinear strain-displacement relation of beams, based in a program designed in MATLAB©, using a finite element formulation. For the development of the code, it has presented the Timoshenko beam theory, where it has considerations shear deformations in beams, and a Lagrangian formulation for the strain-displacement relation for finite deformation. It has done comparison between the displacement of Timoshenko theory and the classic theory (Euler formulation), to verify the convergence of more robust and explicit theories in different cases of beams. This program is capable of calculate of displacements, stresses and internal forces of different beam problems, which has been compared with benchmark problems of the consulted bibliography for convergence check. / Tesis
409

Mathematical Analysis of Intensity Based Segmentation Algorithms with Implementations on Finger Images in an Uncontrolled Environment

Svens, Lisa January 2019 (has links)
The main task of this thesis is to perform image segmentation on images of fingers to partition the image into two parts, one with the fingers and one with all that is not fingers. First, we present the theory behind several well-used image segmentation methods, such as SNIC superpixels, the k-means algorithm, and the normalised cut algorithm. These have then been implemented and tested on images of fingers and the results are shown. The implementations are unfortunately not stable and give segmentations of varying results.
410

Formación de imágenes para detección de cáncer de mama empleando tecnología microondas

Villavicencio Paz, Arantxa 21 February 2019 (has links)
El presente trabajo consiste en la formación de imágenes que permitan detectar tempranamente los tumores mamarios. Para ello, se hará uso de un sistema de recolección de datos físico, haciendo uso de la tecnología microondas por medio de antenas y un equipo Analizador de Redes Vectoriales (VNA). Estos datos serán procesados con algoritmos computacionales para lo obtención de las imágenes. El primer capítulo presenta una descripción del marco problemático actual, donde se considera tanto la incidencia como la mortalidad por cáncer de mama en relación con la importancia de la detección temprana. Luego, se hace una mención breve sobre alguna de las tecnologías actuales que se encuentran destinadas a la imagenología de la mama, lo cual brinda una visión de en qué campos puede desenvolverse la presente investigación y los parámetros a evaluar que se contemplan para una útil formación de imágenes. Por último, con todo lo anterior se plantea la justificación y los objetivos de estas tesis. En el segundo capítulo se expone qué son las propiedades dieléctricas y cómo es que las propiedades de los componentes de una mama brindan información suficiente para la formación de imágenes en base a tecnología microondas. Además, se mencionan las distintas técnicas microondas para formación de imágenes y se logra enfatizar en las basadas en radar, ya que estas competen a la aplicación en este trabajo. Finalmente, se explica brevemente lo que son los parámetros de dispersión, datos base de información para el procesamiento que son brindados por el equipo VNA. El tercer capítulo consiste en el planteamiento de distintos puntos requeridos para el sistema final. Por un lado, se plantea el desarrollo del fantoma de pruebas que simula las propiedades eléctricas de una mama, para lo cual se emplea una técnica basada en cavidades resonantes que permite medir la permitividad de los materiales a usar. Esta medición de permitividad permite comprobar si los valores de los materiales corresponden a los esperados. Por otro lado, se describen dos sistemas para formación de imágenes basados en radar: Confocal y Holográfico. Para ello, se considera el mecanismo de sus algoritmos, los requerimientos para la recolección de pruebas experimentales y, finalmente, las pruebas de factibilidad de estos en la detección de objetos. Las imágenes obtenidas permiten comparar ambos métodos. Además, se realiza una prueba adicional de distribución espacial de antenas para el sistema holográfico, buscando distinguir la distribución con mejores resultados. / Tesis

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