• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 34
  • 8
  • 8
  • 5
  • 4
  • 4
  • 4
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 80
  • 14
  • 13
  • 12
  • 8
  • 8
  • 7
  • 7
  • 7
  • 7
  • 7
  • 7
  • 7
  • 7
  • 6
  • 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.
41

Design of an Emulator of Contactless Card from a Discontinued Product

Lochet, Florian January 2013 (has links)
Contactless cards are everywhere nowadays due to their ease to use and low price to produce. In addition, their reliability is excellent. That is why they are used in systems where security is essential within a low price. To develop the associated systems (cards, readers, terminals), efficient tools are needed. These tools can be a spy analyzing any communication or an emulator that can act and answer exactly as a real contactless card. The objective of this thesis was to develop a contactless card emulator on a product that is currently only spying, the NomadLAB of KEOLABS. The emulator feature is based on a discontinued product, the ProxiCARD, and it has for main objective to be compliant with the ISO 14443 standard. Through the analysis of its architecture and its current performance, I have developed a complete system that can be integrated into the ecosystem of the KEOLABS products. The features I developed take place into the source code of the NomadLAB, at the level of its ARM microcontroller in language C, and in its FPGA in language VHDL. The ARM is here to handle all the smart part of the transmission, while the FPGA to handle the coding and decoding process. In addition, I developed an antenna able to on one hand receive the signal from a reader and on the other hand to reply to it by modulating the magnetic field. I also developed and added my controls to the current computer software. Finally, I have written a lot of testing to make sure that this new system is reliable. The NomadLAB is now able to emulate a contactless card complying with ISO14443 standard, while keeping its spy features, and its control through a computer.
42

Peripheral Nervous Network Simulator : A Computer Networks approach

Hmidi, Baha Eddine January 2022 (has links)
The peripheral nervous system can be seen as a huge network of neurons that prop-agates signals across the human body. In fact, as seen in [1] , "All the information streaming in the peripheral nervous system (PNS) is transmitted along axons byelectro-chemical signals called action potentials". The ordinary conduction of such nervous signals, or action potentials, can be prevented however due to nerve damage. In this context, the accurate passage of information to an intended destination or partwithin the organism is obstructed. Admittedly, it is understood that physiotherapy can be quite helpful in regaining correct functionality over a damaged part of the peripheral nervous system. Yet, it is still hard to visualize the nervous activity as it is achieved inside the human body. Simulating the nervous system would providea platform to visualize how the system works and how a damaged nerve can affect the PNS. Indeed, the purpose of this study is to simulate a virtual network that im-itates a general topology of the human peripheral nervous system e.g(simulate the nervous structure and behaviour of the human arm) that shows how the signals canbe routed to their correct destination and showcase how can the simulator created simulate biological nerve damage in its system.
43

Exceptional points and adiabatic evolution in optical coupled mode systems

Yang, Guang 30 August 2023 (has links)
Quantum and classical frameworks form two perspectives for describing physical systems. Their formulation also presents interesting isomorphism: for example, the Schrodinger equation can find its classical correspondence in the paraxial Helmholtz equation, and coherent atomic population transfers is analogous to coupling dynamics in waveguides. In classical coupled mode systems, quantum notion can be manifested in the following ways: (1) adiabatic (i.e., sufficiently slow) evolution of the Hamiltonian enables robust mode conversion and light transfer, where the dynamics is carried out in predominantly one eigenmode; (2) non-Hermitian Hamiltonians give rise to peculiar singularities known as exceptional points (EPs), associated with not only degenerate eigenvalues but coalescent eigenvectors. In this dissertation, we explore the above principles in light manipulation, sensing, and photonic emulation. First, we numerically demonstrate two examples of photonic devices based on adiabatic evolution engineering. We present a coupled waveguide system analogous to the atomic physics process of stimulated Raman adiabatic passage, where the principle of adiabaticity not only allows high-extinction polarization mode splitting, but also counterintuitively mitigates the losses from the plasmonic structure involved. We show a modal hybridization effect in rib waveguide geometry that allows the mode to adiabatically evolve from one polarization to its orthogonal state upon electro-optic modulation in thin film lithium niobate, enabling an actively switchable polarization converter. We propose a generic EP emulator based on programmable photonics to tackle the challenging implementation of EP. Our approach combines on-chip operations of coupling, loss and detuning based on generic photonic modules (Mach-Zehnder interferometers), and a discrete scheme for mapping Hamiltonians to common mesh architecture. We demonstrate multiple exemplary EP functionalities, including loss-induced transparency, encircling second-order EPs in the PT and anti-PT symmetry picture, and a third-order EP. The proposed EP emulator marks a new paradigm for discrete, \textit{in situ} programming of EPs and multi-functional, repurposable EP devices. We also present our preliminary work on NV center-induced EPs. In contrast to conventional fluorescence-based schemes for addressing NV centers, we leverage NV centers' absorption to bring a coupled ring resonator system to an EP and numerically demonstrate the emerging dynamics. Our primary numerical results promise proof-of-concept magnetometry, combining NV centers' response to magnetic and microwave fields with the sensitivity enhancing nature of EP. This dissertation sheds light on unconventional photonics inspired by quantum-like principles. / 2025-08-29T00:00:00Z
44

Hardened Registration Process for Participatory Sensing

Borsub, Jatesada January 2018 (has links)
Participatory sensing systems need to gather information from a largenumber of participants. However, the openness of the system is a doubleedgedsword: by allowing practically any user to join, the system can beabused by an attacker who introduces a large number of virtual devices.This work proposes a hardened registration process for participatory sensingto raise the bar: registrations are screened through a number of defensivemeasures, towards rejecting spurious registrations that do not correspondto actual devices. This deprives an adversary from a relatively easytake-over and, at the same time, allows a flexible and open registrationprocess. The defensive measures are incorporated in the participatorysensing application. / Deltagande avkännings system behöver samlas från ett stort antal aktörer.Systems öppenhet är dock en dubbelsidigt värd: Genom att låta alla praktiskaanvändare deltagit, kan system utnyttja en av angripare som introducera ett stortantal virtuella enheter. I det här arbetet föreslå en härda registreringsprocess fördeltagare att identifiera höjning av ribban: registrering screenas genom ett antaldefensiva åtgärders, för att avvisa falska registreringar som inte motsvara aktuellaenheter. Detta berövar en motståndare från en relativt lätt övertagande och gersamtidigt en flexibel och öppen registreringsprocess. De defensiva åtgärdernainförlivas i deltagande avkännings applikation.
45

ANÁLISE DE UM PROCESSO DE PRODUÇÃO DE UM FRIGORÍFICO DE CARNE BOVINA UTILIZANDO A TECNOLOGIA RFID. / PRODUCTION PROCESS ANALYSIS IN A SLAUGHTER CATTLE HOUSE USING RFID TECHNOLOGY.

Grande, Eliana Tiba Gomes 09 April 2012 (has links)
Made available in DSpace on 2016-08-10T10:40:24Z (GMT). No. of bitstreams: 1 ELIANA TIBA GOMES GRANDE.pdf: 20259156 bytes, checksum: e966b56d59dd707573bd0634c9b2a73e (MD5) Previous issue date: 2012-04-09 / Since 2008, Brazil has been the largest beef exporter worldwide and also has had. The largest commercial beef herd in the world, which is around 205.3 million animals (IBGE, 2009). Remaining on the top of the ranking depends on technology implementations in the industry and a greater knowledge of the entire production process of beef cattle, mainly the identification of bottlenecks. The RFID technology, which is based on automatic transmission of data, has become a useful tool in various aspects of any productive sector. Throughout this technology one is able not only to track their products throughout the production process, but also do inventory control, logistics, quality control, with constant monitoring of temperature and moisture, which are essential for health y food, all done automatically in real time . The objective of this work was to analyze a solution for the control of traceability in the production process of a slaughter house using RFID technology. This monitoring can be accompanied from anywhere, and anytime because the RFID system uses the middleware that processes data read by the physical layer and provides them to various environments such as the Web. As a result to analyze has the confirmation of the feasibility of using RFID technology in such an unusual environment as the example of the production process in a slaughter house. / O Brasil, desde 2008, é o maior exportador de carne bovina no contexto mundial. Nele se concentra o maior rebanho comercial do mundo: cerca de 205,3 milhões de animais (IBGE, 2009). A permanência no topo do ranking depende das implementações tecnológicas no setor e de um maior conhecimento do processo produtivo de toda a cadeia da carne bovina, principalmente no que se refere à identificação dos pontos de gargalos. A tecnologia RFID, baseada na transmissão automática dos dados, vem se tornando uma aliada em vários aspectos em qualquer setor produtivo. Através desta tecnologia, pode ser possível não somente rastrear seus produtos durante todo o processo produtivo, mas também fazer controle de estoque, de logística, controle de qualidade com o monitoramento constante da temperatura e umidade, essencial à sanidade do alimento, tudo feito automaticamente em tempo real. Objetivou-se nesta dissertação analisar uma solução para a continuidade da rastreabilidade iniciada pelo SISBOV no contexto do processo produtivo de um frigorífico utilizando a tecnologia RFID. Este monitoramento pode ser acompanhado de qualquer lugar, a qualquer hora, pois a solução analisada possui um midlleware que processa dos dados lidos pela camada física e disponibiliza-os para vários ambientes, tais como a Web. Como resultados da análise têm-se a confirmação da viabilidade da utilização da tecnologia RFID em um ambiente tão incomum como é o caso do processo produtivo de um frigorífico.
46

PPS5000 Thruster Emulator Architecture Development & Hardware Design

Persson, Robert January 2019 (has links)
This Master's Thesis handles prestudy work and early hardware development that resulted in architectural definitions and prototype hardware of electronic ground support equipment. This equipment is destined to emulate the electric power consumption of the PPS5000 Hall Effect Thruster (HET), for use in satellite end-to-end tests of the all-electric Geostationary Satellite Electra, developed at OHB Sweden AB. The Thruster Emulator (TEM) was defined through a resulting compilation of intricate interdependent components that interface the satellite power system and the thruster, which yielded an architecture development to support some basic predefined emulator requirements. This architecture was then analyzed to form a base-line conceptual function of the emulator system, which incorporates the entire HET functionality. Six primary HET impedances were defined, of which the three most complex impedances were investigated fully. For the primary thruster discharge, research is shown of the complexity of implementing advanced electronic load hardware directly to the satellite's 5kW power system with respect to the transient primary plasma discharge during thruster start up, and with limitations on the electronic load reducing emulator-thruster similarities. Additionally, a fully functional plasma ignition emulator prototype circuit board was built to be used in the final hardware of the TEM to emulate the external HET cathode start-up functionality. Finally, a feasibility study for designing a possible solution for the large PPS5000 electromagnet impedance was performed, resulting in the manufacture of two prototype inductors with unsatisfying performance results according to the design requirements.
47

Parameter, State and Uncertainty Estimation for 3-dimensional Biological Ocean Models

Mattern, Jann Paul 15 August 2012 (has links)
Realistic physical-biological ocean models pose challenges to statistical techniques due to their complexity, nonlinearity and high dimensionality. In this thesis, statistical data assimilation techniques for parameter and state estimation are adapted and applied to biological models. These methods rely on quantitative measures of agreement between models and observations. Eight such measures are compared and a suitable multiscale measure is selected for data assimilation. Build on this, two data assimilation approaches, a particle filter and a computationally efficient emulator approach are tested and contrasted. It is shown that both are suitable for state and parameter estimation. The emulator is also used to analyze sensitivity and uncertainty of a realistic biological model. Application of the statistical procedures yields insights into the model; e.g. time-dependent parameter estimates are obtained which are consistent with biological seasonal cycles and improves model predictions as evidenced by cross-validation experiments. Estimates of model sensitivity are high with respect to physical model inputs, e.g river runoff.
48

Um sistema eletrônico de 2kW para emulação/simulação experimental da característica estática de saída, tensão (versus) corrente, de sistemas de geração com células combustível tipo PEM /

Melo, Guilherme de Azevedo e. January 2007 (has links)
Orientador: Carlos Alberto Canesin / Banca: Fabio Toshiaki Wakabayashi / Banca: Luiz Carlos de Freitas / Resumo: Este trabalho apresenta o desenvolvimento e implementação de um emulador para a característica estática de saída (Tensão versus Corrente) equivalente àquela de fontes de energia com células combustível. O emulador apresenta como vantagens, em relação à aquisição de uma FC, o baixo custo, o reduzido espaço físico e a flexibilidade via software para a implementação de diversas características baseadas em diferentes tipos de células combustível. Neste sentido, o emulador proposto permite a realização de ensaios preliminares durante a fase de projeto e os testes dinâmicos dos subsistemas de condicionamento de energia, sem a necessidade do acoplamento com o sistema de geração à células combustível, reduzindo-se os custos associados a estes testes laboratoriais. O emulador proposto consiste em um conversor Buck isolado "Full-Bridge", com potência de saída de 2kW e alimentação via barramento de 400VCC, permitindo a emulação da característica nominal de saída de um conjunto de células tipo PEM ("Proton Exchange Membrane" - Membrana de Troca Protônica), em uma faixa de tensão de saída variando entre 32VCC e 72VCC, dependendo da corrente drenada pela carga. O circuito principal de controle é realizado através... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work presents a design and implementation of an emulator to the static output characteristic (Voltage versus Current) that is similar to Fuel Cell generators. There are many advantages on using the Fuel Cell emulator. The emulator is cheaper, smaller and more flexible than the real Fuel Cell systems, because it is possible to emulate different characteristics through the use of a computer. In this context, a Fuel Cell emulator is proposed in this work in order to allow laboratory testes in the power conditioning system during its design and development stage. The proposed emulator is an insulated "Full-Bridge" converter with "Buck" operation, 2kW output power and 400VCC input voltage. This emulator achieves the output characteristic of a PEM (Proton Exchange Membrane) Fuel Cell stack with output voltage range of 32VCC to 72VCC, depending on the output current. The main control circuit is based on FPGA (Field Programmable Gate Array) and VHDL (Very High Speed Integrated Circuit Hardware Description Language) language. The experimental results demonstrate that the proposed emulator achieves the output static characteristic of the PEMFC Fuel Cell System and this output characteristic can be easily modified in order to obtain another desirable static... (Complete abstract click electronic access below) / Mestre
49

Time controlled network traffic shaper / Time controlled network traffic shaper

Yousuf, Kamran January 2010 (has links)
Network performance metrics such as delay variations and packet loss influence the performance of the network. As a consequence, the performance of applications on the network is also affected as most of the networked applications existing today are very much sensitive to the network performance. Therefore it is of utmost importance to test the intensity of such network level disturbances on the performance of applications. A network traffic shaper/emulator shapes the network traffic in terms of these performance metrics to test such applications in a controlled environment. Most of the traffic shapers existing today give the instantaneous step transition in delay and packet loss on network. In this work, we present time-controlled network traffic shaper, a tool that facilitates testing and experimentation of network traffic through emulation. It focuses on time variant behavior of the traffic shaper. A linear transition of delay and packet loss that is varying with respect to time may fits much better to the real network scenarios instead of an instantaneous step transition in delay and packet loss. This work illustrates the emulation capabilities of time-controlled network traffic shaper and presents its design architecture. Several approaches are analyzed to do the task and one of them is followed to develop the desired architecture of the shaper. The shaper is implemented in a small scenario and is tested to see whether the desired output is achieved or not. The shortfalls in the design of the shaper are also discussed. Results are presented that show the output from the shaper in graphical form. Although the current implementation of the shaper does not provide linear or exponential output but this can be achieved by implementing a configuration setting that is comprised of small transition values that are varying with respect to very small step sizes of time e.g. transitions on milli seconds or micro seconds. The current implementation of the shaper configuration provides the output with a transition of one milli second on every next second. / kami1219@gmail.com
50

The Impact of Waiting Time Distributions on QoE of Task-Based Web Browsing Sessions / Påverkan av väntetiden distributioner på QoE av Task-Based Web webbläsning

Islam, Nazrul, Elepe, Vijaya John David January 2014 (has links)
There has been an enormous growth in the Internet usage in recent years, fueled by the increasing number of multimedia applications and widespread availability of World Wide Web (WWW). The end-user generally accesses these applications through web browsing activities. These time-critical services often suffer from the delays ranging from small chunks to long peaks which can have severe implications on the Quality of Experience (QoE). Hence, it is worthwhile to identify the impact of different variations of delay on the end-user QoE. This research focused on the end-user QoE for three different distributions of delays occurring during an e-commerce shopping experiment. By keeping the overall waiting time of every sessions same, the study shows that the end-user QoE is different for different variety of delays. And the research also concludes that, the users prefer small frequently occurring delays as compared to the long rarely occurring delays within a task-driven web browsing session.

Page generated in 0.0651 seconds