Harmonics
Mostrando 37-48 de 106 artigos, teses e dissertações.
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37. Substitution of Electrotherm by Combustible Gases in the Industrial Sector / Substituição da eletrotermia por gases combustíveis no setor industrial
This work analyzes the technical, economical and financial viability to substitute the resistive electrotherm for the direct combustion of fuel gases, such as natural gas (NG) and liquefied gas of petroleum (LGP). In order to do so, a study of the electrotherm presence in the productive process of some industries located in The Great São Paulo has been done
Publicado em: 2008
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38. MODIFICAÇÕES VOCAIS DECORRENTES DA TÉCNICA FONOTERAPÊUTICA DE SONS HIPERAGUDOS
describe the acoustic vocal modifications occurred after the vocal technique of the high-pitched sound in young adult women without voice complaints and with normal larynx, it was done through Multi-Dimensional Voice Program. Method: 23 subjects participated in the study who signed the Statement of Free and Informed Consent, completed a questionnaire, the ea
Publicado em: 2008
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39. Estimação de estados de distorções harmônicas em sistemas elétricos de potência utilizando estratégias evolutivas. / Power systems harmonic distortion state estimation using evolutionary strategy.
The aim of the present thesis is to develop a Harmonic Distortion State Estimation algorithm for Power Systems. Although the cost of Power Quality Meters has decreased for a while now, it is still not practicable the use of one meter for each real system bus. This demands a Harmonic Distortion State Estimation (HDSE) algorithm to find the harmonic components
Publicado em: 2008
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40. Simulation software development for multibody systems / Desenvolvimento de uma ferramenta computacional para simulação de sistemas mecânicos multicorpos
The mathematical simulation is a very important tool to reduce production costs in new projects of agricultural machines. This work consists of a simulation software development for multibody systems (MBS), called FSSM (tool for simulation of mechanical systems), with appropriate functionalities for manufacturers of agricultural machines, using the AutoCAD g
Publicado em: 2008
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41. Investigation of a rotor- bearing system with bearing clearances and hertz contact by using a harmonic balance method
This work is about the steady state vibration of a rotor bearing system. The rolling bearings are modeled as two degrees of freedom elements where the kinematics of the rolling elements is considered, so are the internal clearance and the Hertz contact nonlinearity. The steady state solution of the system is achieved by the harmonic balance method, validated
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2007-03
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42. Low-cost PWM speed controller for an electric mini-baja type vehicle
This paperwork presents a Pulse Width Modulation (PWM) speed controller for an electric mini-baja-type car. A battery-fed 1-kW three-phase induction motor provides the electric vehicle traction. The open-loop speed control is implemented with an equal voltage/frequency ratio, in order to maintain a constant amount of torque on all velocities. The PWM is impl
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2007-03
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43. Real time methods for positive, negative sequence and/or harmonics extraction. / Método de extração em tempo real de seqüência positiva, negativa e/ou harmônicos.
Harmonics and unbalances cause several problems to equipments connected to AC mains. This work proposes a real time method to obtain the positive and negative sequence components and/or harmonics that requires no coordinate transformation neither signal filtering. Numerical simulation and experimental results are shown to validate the proposed method. As exa
Publicado em: 2007
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44. Aproximação na esfera por uma soma com pesos de harmônicos esféricos / Approximation on the sphere by weighted sums of spherical harmonics
The subject of this work is to study approximation on the sphere by weighted sums of spherical harmonics. We present necessary and sufficient conditions on the weights for convergence in both, the continuous and the Lp cases. We analyse the convergence rates of the approximation processes using a modulus of smoothness related to the strong Laplace- Beltrami
Publicado em: 2007
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45. Determinação do conteúdo harmônico de corrente baseada em redes neurais artificiais para cargas não-lineares monofásicas / Determination of the current harmonic content based on artificial neural networks for single-phase non-linear loads
In this thesis artificial neural networks are employed in a novel approach to identifying harmonic components of the single-phase nonlinear load current, whose amplitudes and phase angles are subject to unpredictable changes in steady-state. An identified harmonics number is previously selected. These harmonics are present in the non-linear loads current of
Publicado em: 2007
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46. Diferentes noções de diferenciabilidade para funções definidas na esfera / Different notions of differentiability for functions defined on the sphere
In this work we study different notions of differentiability for functions defined on the unit sphere S^n-1 of R^n, n>=2. With respect to the usual derivative, we find necessary and/or sufficient conditions in order that a function be differentiable up to a fixed order. As for the other two, the strong Laplace-Beltrami derivative and the weak derivative, we
Publicado em: 2007
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47. CaracterizaÃÃo Ãptica de materiais nanoestruturados por tÃcnicas de geraÃÃo de segundo e terceiro harmÃnico
This work is dedicated to the optical characterization of nanostructured materials that are of interest for non-linear optics, optoelectronics and nanophotonics. The hyper- Rayleigh scattering (HRS) technique and the third harmonic generation (THG) technique were used. The materials investigated were a glass-ceramics containing sodium niobate (NaNbO3) nanocr
Publicado em: 2007
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48. Avaliação de filtros eletromagnéticos e sintonizados LC para minimização de correntes de seqüência zero em sistemas de distribuição a quatro fios
A qualidade da energia elétrica se apresenta como uma área de grande interesse para os consumidores e concessionárias de energia elétrica. O aumento deste interesse é explicado pelo aprimoramento da legislação pertinente a esta área e ao nível de esclarecimento dos consumidores, cada vez mais conscientes de seus direitos. Em se tratando do tema qual
Publicado em: 2007