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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.
561

AplicaÃÃo da teoria fuzzy em um modelo de transporte de massa, para avaliar o risco da dispersÃo dos poluentes atmosfÃricos / Application of fuzzy theory in a mass transport model to study the risk of dispersion of air pollutants

Heloisa Beatriz Cordeiro Moreira 14 February 2014 (has links)
nÃo hà / Os problemas de poluiÃÃo do ar se tornam cada vez mais crÃticos, necessitando de controles e monitoramentos contÃnuos, a fim de assegurar um ambiente adequado à comunidade em geral. O impacto das fontes de poluiÃÃo do ar existente ou de novas fontes pode ser avaliado, atravÃs de modelos matemÃticos ou modelos de qualidade do ar. Esta ferramenta permite avaliar os riscos (efeitos) dos poluentes atmosfÃricos ao meio ambiente sob diversas variÃveis, como condiÃÃes de estabilidade atmosfÃricas e pontos de lanÃamento. Neste contexto, a teoria Fuzzy desponta como uma soluÃÃo viÃvel para estudar o risco de falha de um sistema de controle de poluiÃÃo do ar a diferentes lanÃamentos, como a carga de poluente entre 200 a 300 kgd-1. Esta teoria, combinada com o princÃpio de transporte de massa tem permitido que campos de risco sejam determinados, podendo avaliar se os controles adotados sÃo confiÃveis. Este trabalho propÃe uma metodologia, baseado em uma modelagem matemÃtica dos processos de dispersÃo dos poluentes atmosfÃricos, onde os parÃmetros sÃo funÃÃes de pertinÃncia, definidas segundo a teoria Fuzzy. A pesquisa utiliza esses conceitos na soluÃÃo da equaÃÃo gaussiana âfuzzificadaâ, para determinar o risco de falha e a confiabilidade de minimizaÃÃo do lanÃamento de poluentes atmosfÃricos a diferentes concentraÃÃes para emissÃes contÃnuas e instantÃneas. Os resultados mostraram que a melhor condiÃÃo de estabilidade para dispersÃo dos poluentes à a instÃvel e o risco de falha do sistema nesta condiÃÃo à baixo, apresentam valores de concentraÃÃo dentro dos parÃmetros da legislaÃÃo pertinente, o qual nÃo causa impactos para o meio ambiente e nem para a comunidade no entorno. / Air pollution problems increasingly become more critical, requiring continuous monitoring and controls in order to ensure an appropriate environment for the community in general. The impact sources of air pollution from existing or new sources can be evaluated using mathematical models or models of air quality. This tool allows for evaluate the effects (risks) of air pollutants to the environment in several variables. In this context, the Fuzzy theory emerged as a viable solution to study the risk of failure of a system of air pollution different releases. This theory combined with the principle of mass transportation has allowed fields of risk are determined and can assess whether the controls adopted are reliable. This paper proposes a methodology based on a mathematical modeling of air dispersion process pollutants, where their parameters are membership functions, defined according for Fuzzy theory. The research uses these concepts in the solution of the equation Gaussian Fuzzy to determine the risk of failure and ensuring sustainability of the release of pollutants at different concentrations for continuous and instantaneous emissions. The results showed that the best conditions of stability for the dispersion of pollutants is unstable and the risk of system failure in this condition is zero, with concentration values within the parameters of the relevant legislation, without causing impacts on the environment the environment or to the community around.
562

Leis de reciprocidade / Reciprocity laws

Lopes, Rodrigo Francisco 23 February 2006 (has links)
Orientador: Paulo Roberto Brumatti / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-06T01:03:00Z (GMT). No. of bitstreams: 1 Lopes_RodrigoFrancisco_M.pdf: 640692 bytes, checksum: 75ad1ee35d8a529904fe79cc7c944a7b (MD5) Previous issue date: 2006 / Mestrado / Algebra / Mestre em Matemática
563

Desenvolvimento de uma metodologia de analise da qualidade cristalina de monocristais

METAIRON, SABRINA 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:43:13Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:35Z (GMT). No. of bitstreams: 1 06444.pdf: 11587450 bytes, checksum: c6dc7c542bc99d2c882eb508cb25673a (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
564

Mitteilungen des URZ 3/1996

Fischer, Günther, Köbe, Rolf, Müller, Thomas, Schier, Thomas, Schumann, Merten, Ziegler, Christoph, Fiedler, Gerald, Riedel, Wolfgang, Porezag, Dirk 17 December 1996 (has links)
PC-Integration via Cache-Server Archiv- und Recherchesystem der TU TeleNET-Projekt Softwarelizenzen Das Programmpaket GAUSSIAN Software-News
565

Analytic Long Term Forecasting with Periodic Gaussian Processes / Analytic Long Term Forecasting with Periodic Gaussian Processes

Ghassemi, Nooshin Haji January 2014 (has links)
In many application domains such as weather forecasting, robotics and machine learning we need to model, predict and analyze the evolution of periodic systems. For instance, time series applications that follow periodic patterns appear in climatology where the CO2 emissions and temperature changes follow periodic or quasi-periodic patterns. Another example can be in robotics where the joint angle of a rotating robotic arm follows a periodic pattern. It is often very important to make long term prediction of the evolution of such systems. For modeling and prediction purposes, Gaussian processes are powerful methods, which can be adjusted based on the properties of the problem at hand. Gaussian processes belong to the class of probabilistic kernel methods, where the kernels encode the characteristics of the problems into the models. In case of the systems with periodic evolution, taking the periodicity into account can simplifies the problem considerably. The Gaussian process models can account for the periodicity by using a periodic kernel. Long term predictions need to deal with uncertain points, which can be expressed by a distribution rather than a deterministic point. Unlike the deterministic points, prediction at uncertain points is analytically intractable for the Gaussian processes. However, there are approximation methods that allow for dealing with uncertainty in an analytic closed form, such as moment matching. However, only some particular kernels allow for analytic moment matching. The standard periodic kernel does not allow for analytic moment matching when performing long term predictions. This work presents an analytic approximation method for long term forecasting in periodic systems. We present a different parametrization of the standard periodic kernel, which allows us to approximate moment matching in an analytic closed form. We evaluate our approximate method on different periodic systems. The results indicate that the proposed method is valuable for the long term forecasting of periodic processes.
566

Decoding Book Barcode Images

Tao, Yizhou 01 January 2018 (has links)
This thesis investigated a method of barcode reconstruction to address the recovery of a blurred and convoluted one-dimensional barcode. There are a lot of types of barcodes used today, such as Code 39, Code 93, Code 128, etc. Our algorithm applies to the universal barcode, EAN 13. We extend the methodologies proposed by Iwen et al. (2013) in the journal article "A Symbol-Based Algorithm for Decoding barcodes." The algorithm proposed in the paper requires a signal measured by a laser scanner as an input. The observed signal is modeled as a true signal corrupted by a Gaussian convolution, additional noises, and an unknown multiplier. The known barcode dictionaries were incorporated into the forward map between the true barcode and the observed barcode. Unlike the one proposed by Iwen et al., we take dictionaries of different patterns into account, specifically for decoding book barcodes from images which are captured with smartphones. We also presented numerical experiments that examined the performance of the proposed algorithm and illustrated that the unique determination of barcode digits is possible even in the presence of noise.
567

Generating Generalized Inverse Gaussian Random Variates by Fast Inversion

Leydold, Josef, Hörmann, Wolfgang January 2009 (has links) (PDF)
We demonstrate that for the fast numerical inversion of the (generalized) inverse Gaussian distribution two algorithms based on polynomial interpolation are well-suited. Their precision is close to machine precision and they are much faster than the bisection method recently proposed by Y. Lai. / Series: Research Report Series / Department of Statistics and Mathematics
568

Non-coherent energy detection transceivers for Ultra Wideband Impulse radio systems

Stoica, L. (Lucian) 29 January 2008 (has links)
Abstract The focus of this thesis is Ultra Wideband (UWB) Impulse Radio (UWB-IR) transmitters and non-coherent receivers. The aim of the thesis is to investigate, analyze and design UWB-IR transmitter and receiver structures both from a theoretical and circuit design viewpoint. An UWB-IR transmitter structure is proposed and is the subject of a detailed investigation. The transmitter generates a Gaussian monocycle and can be modified to generate a family of Gaussian waveforms. The Gaussian monocycle is easy to generate while providing good bit-error-rate (BER) performance. The Gaussian monocycle has a wide -10 dB bandwidth and a zero-DC component which does not decrease antenna efficiency. The transmitter design includes a delay locked loop (DLL) based frequency synthesis approach. The advantage of using a frequency synthesis approach based on a DLL is based on the fact that a DLL generates less noise than a phase locked loop (PLL) and is inherently stable. The generated pulse has a width of less than 350 ps and a -10 dB bandwidth of 4.7 GHz. The power consumption of the designed UWBIR transmitter is 20 mW at a voltage supply of 3.3 V. Compared with other integrated UWB-IR transmitters, the transmitter presented in this thesis has the lowest pulse width for comparable integrated processes, one of the lower power consumptions and a low die area. The BER performance of several UWB-IR non-coherent receiver structures is presented. The energy detection (ED) receiver offers the same BER performance as the transmitted reference scheme with binary pulse amplitude modulation (BPAM) but has a lower implementation complexity since it does not require an analogue delay line in its structure. Circuit performance of several blocks of the ED receiver is presented. The radio frequency (RF) front-end and analogue baseband sections of the receiver have been designed as an integrated circuit (IC) in a 0.35 μm bipolar complementary metal oxide semiconductor (BiCMOS) process. The RF front-end section includes a low noise amplifier (LNA), a variable gain amplifier (VGA) and a Gilbert cell. The LNA has a noise figure (NF) of less than 3 dB, a gain of 18 dB in the interest bandwidth and less than 20 mW of power consumption. The NF of the LNA can be reduced even further at the expense of a higher power consumption or by using input pads with lower capacitance values. The noise figure can be also lowered by using a process which provides transistors with higher transit frequency (fT). Trading-off power consumption for noise is still a key design issue in the design of integrated UWB-IR receivers. The analogue baseband section includes a bank of integrators and a 4-bit analogue to digital converter (ADC). The ADC is running at a sampling rate equal to the symbol rate and takes only 2 mW of power at 3.3 V supply. The power consumption of the designed integrated front-end and analogue baseband receiver sections is 117 mW at a power supply of 3.3 V. The digital baseband of the receiver have been implemented on a field programmable gate array (FPGA) technology. The power consumption of the baseband is 450 mW with a power supply of 1.2 V and a maximum supply of 3.3 V for input-output pins. The total power consumption of the designed transceiver is 587 mW. When compared with other UWB receiver architectures, the energy detection receiver has the lowest power consumption due to the low power consumption of the LNA, simple synchronization architecture and low sampling rate of the ADC.
569

Stochastic volatility modeling of the Ornstein Uhlenbeck type : pricing and calibration

Marshall, Jean-Pierre 23 February 2010 (has links)
M.Sc.
570

Modeling of the dispersion of radionuclides around a nuclear power station

Dinoko, Tshepo Samuel January 2009 (has links)
Magister Scientiae - MSc / Nuclear reactors release small amounts of radioactivity during their normal operations. The most common method of calculating the dose to the public that results from such releases uses Gaussian Plume models. We are investigating these methods using CAP88-PC, a computer code developed for the Environmental Protection Agency (EPA) in the USA that calculates the concentration of radionuclides released from a stack using Pasquill stability classification. A buoyant or momentum driven part is also included. The uptake of the released radionuclide by plants, animals and humans, directly and indirectly, is then calculated to obtain the doses to the public. This method is well established but is known to suffer from many approximations and does not give answers that are accurate to be better than 50% in many cases. More accurate, though much more computer-intensive methods have been developed to calculate the movement of gases using fluid dynamic models. Such a model, using the code FLUENT can model complex terrains and will also be investigated in this work. This work is a preliminary study to compare the results of the traditional Gaussian plume model and a fluid dynamic model for a simplified case. The results indicate that Computational Fluid Dynamics calculations give qualitatively similar results with the possibility of including much more effects than the simple Gaussian plume model. / South Africa

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