Global ETD Search

91	Simulação de fenômenos óticos e fisiológicos do sistema de visão humana / Simulation of optical and physiological phenomena of the human vision Leandro Henrique Oliveira Fernandes 07 March 2008 (has links) O ganho crescen te de desempenho nos computadores modernos tem impulsionado os trabalhos científicos nas áreas de simulação computacional. Muitos autores utilizam em suas pesquisas ferramentas comerciais que limitam seus trabalhos ao esconder os algoritmos internos destas ferramentas e dificultam a adição de dados in-vivo nestes trabalhos. Este trabalho explora esta lacuna deixada por aqueles autores. Elaboramos um arcabouço computacional capaz de reproduzir os fenômenos óticos e fisiológicos do sistema visual. Construímos com superfícies quádricas os modelos esquemáticos do olho humano e propomos um algoritmo de traçado de raio realístico. Então realizamos um estudo nos modelos esquemáticos e a partir deles mais a adição de dados in-vivo obtidos de um topógrafo de córnea extraímos informações óticas destes modelos. Calculamos os coeficientes e Zernike dos modelos para tamanhos diversos de pupila e obtivemos medidas de aberração do olho humano. Os resultados encontrados estão de acordo com os trabalhos relacionados e as simulações com dados in-vivo estão consoantes com as produzidas por um aparelho de frente de onda comerciais. Este trabalho é um esforço em aproveitar as informações adquiridas pelos equipamentos modernos de oftalmologia, além de auxiliar o entendimento de sistemas visuais biológicos acabam também em auxiliar a elaboração de sistemas de visão artificial e os projetistas de sistemas óticos / The increase in performance of the modern computers has driven scientific work in the areas of computer simulation. Many authors use in their research commercial tools that use embedding algorithms, which sources are not provided, and it makes harder and sometimes impossible, the development of novel theories or experiments. This work explores this gap left for those authors. We present a computational framework capable to reproduce the optical and physiological phenomena of the human visual system. We construct schematical models of the human eye from quadrics surfaces and consider an algorithm of realistic ray tracing. Afterward, we performed a study on schematics models and in addition we introduce, in these models, in-vivo data obtained from corneal topography machine and extract optical information. We calculate the Zernike coefficients in the models for different sizes of pupil and measures of aberration of the human eye. The results are in agreement with related work and simulations with in-vivo data are according with the produced by a commercial wave-front device. This work is an effort in using to advantage the information acquired for the modern equipment of ophthalmology, besides assisting the understanding of biological visual systems, it also helps the development of artificial vision systems and the designing of optical systems Aberração Acomodação Diagrama de pontos Dioptria Frente de onda Modelos esquemátizados do olho humano MTF Polinômio de Zernike PSF Razão de Strehl Aberration Accommodation Dioptry Esquematics model eye Spherical aberration Spot diagram Strehl ratio Wave-front Zernike polynomials
92	L'éducation, fondement et avenir des politiques de ressources humaines et de développement du leadership dans les sociétés de services professionnels / Fostering education-based innovative HR and leadership development strategies in professional service firms Choain, Laurent 05 March 2014 (has links) Cette thèse, au travers d’une étude croisée d’un secteur – les firmes de services professionnels – et d’un champ fonctionnel global – l’éducation au management – traite en réalité d’une question principale: comment vont diriger les leaders issus de la génération Y ? Les systèmes actuels d’éducation au management sont-ils en état d’aider à préparer l’émergence d’une génération dont les codes ne pourront plus être ceux – stables – de ces soixante dernières années ? De nouveaux acteurs sont déjà en émergence, prêts à accompagner le développement exponentiel de la classe moyenne mondiale ; mais les entreprises ne pourraient-elles pas, au travers de vingt ans d’expériences innovantes dans leurs universités internes, autant que d’une emprise réelle sur des terrains de recherche opérationnelle, baliser la voie de nouveaux modes d’apprentissage, voire d’organisation, pour peu qu’elles réalisent un effort d’ouverture ? De structures de production à forte concentration capitalistique, n’ont-elles pas vocation à devenir ces lieux de management et de développement de savoir que recherchent les membres les plus talentueux et convoités de cette génération Y ? Les sociétés de services professionnels, confrontées avant toutes autres à ces phénomènes de transformation, sont une avant-garde originale de ces questions, jusque dans leur gouvernance associative et la place centrale des ressources humaines dans leur modèle économique. / This work sits at the crossroads of an industry – professional services – and a global functional field – management education, and seeks to answer one question: how are millenials going to lead? Are current management education systems, which proved robust and effective for the past sixty years, capable of adapting to this new generation, helping them create their own leadership codes? New players in the field of education are emerging to take advantage of the rise of a massive middle class around the world. With their vast bodies of empirical research and their innovative practices in the design and delivery of management education through their corporate universities, can companies, provided they open up, pioneer new formats of executive education? Can these corporations shift from capital-intensive organisations to knowledge-intensive campuses, the latter seemingly favoured by the most talented and sought-after Millenials? If a shift is underway, Professional Service Firms are at the forefront of the transformation: based on a purely people-intensive business model, selling only knowledge, and governed through partnerships, PSFs have long had management education at the heart of their operations. Moreover, a large majority of their staff belong to the Y generation. This work therefore examines how to foster education-based innovative HR and leadership development strategies in Professional Service Firms, and draws lessons for the larger corporate world. Education Partnership professionnel Ressources humaines Talent Université d'entreprise Génération Y Leadership partagé MBA Education Professional service firms Partnership Human resources Talent Corporate universities Resource based view theory Generation Y Shared leadership MBA
93	Zlepšení rozlišení pro vícečetné snímky stejné scény / Superresolution Mezera, Lukáš January 2010 (has links) Úkolem této diplomové práce je navrhnout vlastní metodu pro zvýšení rozlišení v obraze scény, pokud je k dispozici více snímků dané scény. V teoretické části diplomové práce jsou jako nejlepší metody pro zvýšení rozlišení v obraze vybrány ty, které jsou založeny na principech zpracování signálu. Dále jsou popsány základní požadavky metod pro zvýšení rozlišení v obraze při přítomnosti více snímků stejné scény a jejich typická struktura. Následuje stručný přehled těchto metod a jejich vzájemné porovnání podle optimálních kritérií. Praktická část diplomové práce se zabývá samotným návrhem metody pro zvýšení rozlišení v obraze, pokud je k dispozici více snímků této scény. První navržená metoda je naimplementována a otestována. Při testování této metody je však zjištěna její špatná funkčnost pro snímky scény s nízkým rozlišením, které vznikly vzájemnou rotací. Z toho důvodu je navržena vylepšená metoda pro zvýšení rozlišení v obraze. Tato metoda využívá při svém výpočtu robustních technik. Díky tomu je již vylepšená metoda nezávislá na rotaci mezi snímky scény s nízkým rozlišením. I tato metoda je řádně otestována a její výsledky jsou porovnány s výsledky první navržené metody pro zvýšení rozlišení v obraze. V porovnání výpočetních časů je lepší první navrhovaná metoda, avšak její výsledky pro obrazy obsahující rotace nejsou kvalitní. Oproti tomu pro obrazy, které vznikly pouze posunem při snímání scény, jsou tyto výsledky velice dobré. Vylepšená metoda je tedy využitelná zejména pro obrazy obsahující rotace. V závěru této práce je ještě navrženo jedno vylepšení, které by mohlo zlepšit výsledky druhé navrhnuté metody pro zvýšení rozlišení v obraze scény.
94	Electromagnetic Physical Security: Addressing Exploitation Risks and Building Trust Md Faizul Bari (20373786) 10 December 2024 (has links) <p dir="ltr">Unintentional electromagnetic emission (called emanation) from electronic devices and cables contains a significant correlation with the source signal and can be used to recover otherwise confidential data. In our work, EM emanation has been exploited to recover keystrokes from USB keyboards. Also, such emission has been utilized to form a covert channel for data exfiltration from air-gapped devices without being detected by IDS. To protect sensitive information, an automated emanation detection system has been proposed by developing two emanation detection algorithms (CNN-based and harmonic-based) through the characterization of emanation signals from a wide range of devices. Apart from emanation, data theft can happen due to the failure of access control methods. Traditional wireless devices are susceptible to various spoofing attacks as they only use digital signature-based authentication systems, ignoring the physical signatures completely. To circumvent that, RF-PUF was proposed to use device-specific signatures to be used for trust augmentation in traditional methods. By forming an extensive experimental dataset, we established RF-PUF as a strong PUF with a low-power overhead that outperformed the state-of-the-art methods and is robust against typical attacks. For real-time authentication, we proposed DIRAC, which forms dynamic device clusters and incrementally learns as more device data becomes available. Since our root of trust is in the physical signature of the ICs, they also need to be secured. However, counterfeited ICs may jeopardize that goal. We have proposed RF-PSF, which uses device-specific physical properties to authenticate its process technology which is a big part of the cloned IC detection.</p> Circuits and systems Engineering electromagnetics Hardware security System and network security EM Emanation RF-PUF RF-PSF Side Channel Analysis Covert Channel Data exfiltration PWM Keystroke Recovery authentication security Incremental learning Dynamic Clusters Counterfeit IC Computational Harmonic Detector Emanation Compromising Emanation TEMPEST investigators
95	Channel Probing for an Indoor Wireless Communications Channel Hunter, Brandon 13 March 2003 (has links) (PDF) The statistics of the amplitude, time and angle of arrival of multipaths in an indoor environment are all necessary components of multipath models used to simulate the performance of spatial diversity in receive antenna configurations. The model presented by Saleh and Valenzuela, was added to by Spencer et. al., and included all three of these parameters for a 7 GHz channel. A system was built to measure these multipath parameters at 2.4 GHz for multiple locations in an indoor environment. Another system was built to measure the angle of transmission for a 6 GHz channel. The addition of this parameter allows spatial diversity at the transmitter along with the receiver to be simulated. The process of going from raw measurement data to discrete arrivals and then to clustered arrivals is analyzed. Many possible errors associated with discrete arrival processing are discussed along with possible solutions. Four clustering methods are compared and their relative strengths and weaknesses are pointed out. The effects that errors in the clustering process have on parameter estimation and model performance are also simulated. multipath multipath propagation propagation environment indoor propagation indoor multipath indoor multipath propagation channel probing channel probing indoor wireless communications channel indoor wireless communications indoor wireless communications wireless communications wireless communications channel MIMO SISO multiple input multiple output single input single output antenna diversity antenna diversity antenna array channel modeling modeling model wireless propagation clustering methods clustering algorithms clustering parameter estimation parameter channel matrix h matrix ray tracing point spread function psf deconvolution clean algorithm clean algorithm antenna pattern network analyzer temporal pattern 2.4 ghz system 6 ghz system channel capacity capacity estimate channel capacity estimate propagation environment scattering transfer matrix matrix water filling solution water filling method water filling Saleh Valenzuela Saleh and Valenzuela Model arrival time of arrival angle of arrival direction of arrival arrival amplitude arrivals antenna positioner data simulations measurements angle of departure direction of departure correlation convolution errors error CFA CFAD constant false alarm constant false alarm detection signal signal dependent clutter clutter returns transmitter transmit receive receiver transmit antenna receive antenna spatial correlation system PSF system point spread function mapping fuzzy c-means clustering fuzzy clustering c-means clustering c-means fuzzy k-means euclidean distance time amplitude delay performance prediction performance prediction errors fuzzy weighted distance method rectangular method weighted rectangular method statistics statistical statistical model Electrical and Computer Engineering

Page generated in 0.0392 seconds