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‣ Comparison of friction models applied to a control valve

GARCIA, Claudio
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.6318%
Eight different models to represent the effect of friction in control valves are presented: four models based on physical principles and four empirical ones. The physical models, both static and dynamic, have the same structure. The models are implemented in Simulink/Matlab (R) and compared, using different friction coefficients and input signals. Three of the models were able to reproduce the stick-slip phenomenon and passed all the tests, which were applied following ISA standards. (C) 2008 Elsevier Ltd. All rights reserved.

‣ Monitoração de modelos físicos reduzidos para investigação do comportamento de estruturas em escala real.; Monitoring reduced physical models to investigate the behavior of real structures.

Ticona Melo, Ladislao Roger
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/08/2011 Português
Relevância na Pesquisa
66.84145%
Esta pesquisa apresenta a monitoração de modelos reduzidos para a investigação do comportamento de estruturas. O estudo do comportamento estrutural consistiu basicamente na medição de grandezas físicas de forma experimental, para o qual os modelos físicos reduzidos foram submetidos a múltiplos ensaios em laboratório. Posteriormente, os dados experimentais foram tratados e analisados, para então serem comparados com os resultados dos modelos teóricos, avaliando assim, sua capacidade de simulação. No total foram monitorados três modelos reduzidos, cujas grandezas físicas foram medidas utilizando-se sensores elétricos, tais como: extensômetros, LVDTs e um servoatuador hidráulico, os quais estavam ligados ao sistema de aquisição da National Instrument, controlado por um computador de comando e pelos programas LabView e DynaTester. Um dos modelos construído em alumínio foi utilizado a fim de se estudar o comportamento da ponte do rio Suaçui, assim como calibrar os modelos teóricos em função dos dados experimentais da estrutura real e do modelo reduzido e estabelecer uma relação entre eles. Os outros dois modelos construídos em microconcreto foram utilizados para estudar o comportamento de estruturas na fase não linear e em fratura...

‣ O uso de modelos físicos na indústria cerâmica durante o processo de desenvolvimento de projeto de produto e as possibilidades da inserção de tecnologias digitais nesse processo - estudos de casos; The use of physical models in the ceramic industry during the product development process and the possibilities of integrating digital technologies in this process - case studies

Moreira, Fernanda
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 05/05/2014 Português
Relevância na Pesquisa
66.949033%
O objetivo deste trabalho é apresentar informações sobre o uso de modelos físicos na indústria cerâmica como parte integrante do método de projeto e identificar as possibilidades de utilização de tecnologias digitais nesse processo, verificando possíveis contribuições para o design. Esta é uma pesquisa qualitativa, que se utiliza de procedimentos adotados em estudos de casos múltiplos, a partir da investigação de duas indústrias de cerâmica para cada um dos setores fabris: louça de mesa, louça sanitária, cerâmica decorativa/ ornamental, revestimentos cerâmicos, telhas e blocos estruturais. Foram realizadas pesquisas bibliográficas e de campo, por meio de visitas a indústrias cerâmicas, a representantes de equipamentos de tecnologias digitais, a centros de pesquisa nacional e internacional e a instituições que possuem os equipamentos digitais para obtenção de modelos físicos. Os modelos físicos são muito utilizados em projetos de design durante as fases de desenvolvimento de produto e servem para gerar, analisar e selecionar as alternativas propostas, fornecendo respostas a problemas que surgem através de testes e simulações que devem ser adequados às questões e informações que se pretende coletar. Tradicionalmente...

‣ Testing Physical Models of Passive Membrane Permeation

Leung, Siegfried S. F.; Mijalkovic, Jona; Borrelli, Kenneth; Jacobson, Matthew P.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.56169%
The biophysical basis of passive membrane permeability is well understood, but most methods for predicting membrane permeability in the context of drug design are based on statistical relationships that indirectly capture the key physical aspects. Here, we investigate molecular mechanics-based models of passive membrane permeability and evaluate their performance against different types of experimental data, including parallel artificial membrane permeability assays (PAMPA), cell-based assays, in vivo measurements, and other in silico predictions. The experimental data sets we use in these tests are diverse, including peptidomimetics, congeneric series, and diverse FDA approved drugs. The physical models are not specifically trained for any of these data sets; rather, input parameters are based on standard molecular mechanics force fields, such as partial charges, and an implicit solvent model. A systematic approach is taken to analyze the contribution from each component in the physics-based permeability model. A primary factor in determining rates of passive membrane permeation is the conformation-dependent free energy of desolvating the molecule, and this measure alone provides good agreement with experimental permeability measurements in many cases. Other factors that improve agreement with experimental data include deionization and estimates of entropy losses of the ligand and the membrane...

‣ Back to the Future: Can physical models of passive membrane permeability help reduce drug candidate attrition and move us beyond QSPR?

Swift, Robert V.; Amaro, Rommie E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/2013 Português
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46.70538%
It is widely recognized that ADMET (Adsorption, Distribution, Metabolism, Excretion - Toxicology) liabilities kill the majority of drug candidates that progress to clinical trials. The development of computational models to predict small molecule membrane permeability is therefore of considerable scientific and public health interest. Empirical qualitative structure permeability relationship (QSPR) models of permeability have been a mainstay in industrial applications, but lack a deep understanding of the underlying biological physics. Others and we have shown that implicit solvent models to predict passive permeability for small molecules exhibit mediocre predictive performance when validated across experimental test sets. Given the vast increase in computer power, more efficient parallelization schemes, and extension of current atomistic simulation codes to general use graphical processing units (GPUs), the development and application of physical models based on all-atom simulations may now be feasible. Preliminary results from rigorous free energy calculations using all-atom simulations indicate that performance relative to implicit solvent models may be improved, but many outstanding questions remain. Here we review the current state of the art physical models for passive membrane permeability prediction...

‣ Empirical physical modeling methods for bowed-string and wind instruments

Sterling, Mark (1980 - ); Bocko, Mark Frederick (1956 - )
Fonte: University of Rochester Publicador: University of Rochester
Tipo: Tese de Doutorado Formato: Number of Pages:xi, 135 leaves
Português
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Thesis (Ph. D.)--University of Rochester. Dept. of Electrical and Computer Engineering, 2011.; An empirical approach for the physical modeling synthesis of musical instrument sounds is presented and demonstrated for the Violin, Bassoon, and Clarinet. The physical models incorporate measured acoustic and mechanical impedances in their definition. The control parameter inputs to the physical models correspond to actions performed by human musicians and are therefore highly expressive and, owing to the inherent bandwidth limitations of human actions, compact. Time-histories of the control parameters may be created arbitrarily or inferred from digital audio recordings to match the model output to a given performance or piece of music. Experiments were conducted in a controlled anechoic environment on real instruments. Descriptions of the experimental procedures as well as the physical modeling and sound synthesis algorithms, including computer code examples, are provided.

‣ Models of Time Travel: a comparative study using films

Micklethwait, Guy Roland
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
Português
Relevância na Pesquisa
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This research identifies the way the science of time travel is presented to the public through the medium of feature films, and discovers if this can be used to construct a comprehensive set of models about time travel and its consequences. There is no universally accepted understanding of what constitutes the nature of time. Even though the fundamental laws of physics do not prohibit time travel, scientists and philosophers do not agree about what would happen if backwards time travel ever became a reality. I identified models that scientists and philosophers have produced about the nature of time, time travel and other temporal phenomena. I then determined the model of time used in each of the 100 time travel films that I reviewed. I also used a verbal survey to elicit the personal models of time travel for each participant of three focus groups I conducted with members of the movie-going public. I compared these models of time with the personal models used by members of the movie-going public and synthesised them to develop a comprehensive set of 21 models of time. The "guyline" diagrams that I devised proved to be a very useful tool for analysing how the timelines of the time travellers behaved in each film. My research has shown that an investigation of time travel in films can indeed be used to construct useful models of time based on the evidence of the 21 models that I developed. Furthermore...

‣ From physical models to well-founded control

Dobson, Simon; Coyle, Lorcan; O'Hare, G.M.P.; Hinchey, Mike
Fonte: IEEE Computer Society Publicador: IEEE Computer Society
Tipo: Conference item; all_ul_research; ul_published_reviewed; none
Português
Relevância na Pesquisa
56.68182%
peer-reviewed; Mobile sensors are an attractive proposition for environmental sensing, but pose significant engineering problems. Not least amongst these is the need to match the behaviour of the sensor platform to the physical environment in which it operates. We present initial work on using models of physical processes to generate models for autonomic control, and speculate that these can be used to improve the confidence we can place in sensed data.

‣ Analysis of Vilanova Artigas' unbuilt designs in Sao Paulo

Tagliari, Ana; Perrone, Rafael; Florio, Wilson
Fonte: EDITORA UNISINOS; SAO LEOPOLDO Publicador: EDITORA UNISINOS; SAO LEOPOLDO
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.68182%
The aim of this article is to examine unbuilt residential projects designed by Vilanova Artigas. The formal and spatial conception of these projects is investigated through physical models. The object of this research project consists of the unbuilt residential projects designed by Vilanova Artigas in Sao Paulo that are available in FAUUSP's digital Library. The results indicate that physical models contribute to a better interpretation of unbuilt architectural design, both from the conceptual and aesthetic and from the functional and technical point of view. The original contribution lies in the object, i.e. the unbuilt projects, in the method, using physical models for analysis, and in the objective, viz. to establish a relationship between Artigas' built works and his unbuilt residential projects in order to better understand the design's spatial conception and its architectural approach.

‣ Analysis of Vilanova Artigas' unbuilt designs in Sao Paulo

Tagliari, Ana; Perrone, Rafael; Florio, Wilson
Fonte: Editora Unisinos; Sao Leopoldo Publicador: Editora Unisinos; Sao Leopoldo
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.68182%
The aim of this article is to examine unbuilt residential projects designed by Vilanova Artigas. The formal and spatial conception of these projects is investigated through physical models. The object of this research project consists of the unbuilt residential projects designed by Vilanova Artigas in Sao Paulo that are available in FAUUSP's digital Library. The results indicate that physical models contribute to a better interpretation of unbuilt architectural design, both from the conceptual and aesthetic and from the functional and technical point of view. The original contribution lies in the object, i.e. the unbuilt projects, in the method, using physical models for analysis, and in the objective, viz. to establish a relationship between Artigas' built works and his unbuilt residential projects in order to better understand the design's spatial conception and its architectural approach.

‣ Precise physical models of protein–DNA interaction from high-throughput data

Kinney, Justin B.; Tkačik, Gašper; Callan, Curtis G.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.65671%
A cell's ability to regulate gene transcription depends in large part on the energy with which transcription factors (TFs) bind their DNA regulatory sites. Obtaining accurate models of this binding energy is therefore an important goal for quantitative biology. In this article, we present a principled likelihood-based approach for inferring physical models of TF–DNA binding energy from the data produced by modern high-throughput binding assays. Central to our analysis is the ability to assess the relative likelihood of different model parameters given experimental observations. We take a unique approach to this problem and show how to compute likelihood without any explicit assumptions about the noise that inevitably corrupts such measurements. Sampling possible choices for model parameters according to this likelihood function, we can then make probabilistic predictions for the identities of binding sites and their physical binding energies. Applying this procedure to previously published data on the Saccharomyces cerevisiae TF Abf1p, we find models of TF binding whose parameters are determined with remarkable precision. Evidence for the accuracy of these models is provided by an astonishing level of phylogenetic conservation in the predicted energies of putative binding sites. Results from in vivo and in vitro experiments also provide highly consistent characterizations of Abf1p...

‣ Likelihood method and Fisher information in construction of physical models

Piotrowski, E. W.; Sladkowski, J.; Syska, J.; Zajac, S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/11/2008 Português
Relevância na Pesquisa
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The subjects of the paper are the likelihood method (LM) and the expected Fisher information (FI) considered from the point od view of the construction of the physical models which originate in the statistical description of phenomena. The master equation case and structural information principle are derived. Then, the phenomenological description of the information transfer is presented. The extreme physical information (EPI) method is reviewed. As if marginal, the statistical interpretation of the amplitude of the system is given. The formalism developed in this paper would be also applied in quantum information processing and quantum game theory.

‣ Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution

Hanuš, J.; Ďurech, J.; Brož, M.; Marciniak, A.; Warner, B. D.; Pilcher, F.; Stephens, R.; Behrend, R.; Carry, B.; Čapek, D.; Antonini, P.; Audejean, M.; Augustesen, K.; Barbotin, E.; Baudouin, P.; Bayol, A.; Bernasconi, L.; Borczyk, W.; Bosch, J. -G.;
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/01/2013 Português
Relevância na Pesquisa
46.73496%
The larger number of models of asteroid shapes and their rotational states derived by the lightcurve inversion give us better insight into both the nature of individual objects and the whole asteroid population. With a larger statistical sample we can study the physical properties of asteroid populations, such as main-belt asteroids or individual asteroid families, in more detail. Shape models can also be used in combination with other types of observational data (IR, adaptive optics images, stellar occultations), e.g., to determine sizes and thermal properties. We use all available photometric data of asteroids to derive their physical models by the lightcurve inversion method and compare the observed pole latitude distributions of all asteroids with known convex shape models with the simulated pole latitude distributions. We used classical dense photometric lightcurves from several sources and sparse-in-time photometry from the U.S. Naval Observatory in Flagstaff, Catalina Sky Survey, and La Palma surveys (IAU codes 689, 703, 950) in the lightcurve inversion method to determine asteroid convex models and their rotational states. We also extended a simple dynamical model for the spin evolution of asteroids used in our previous paper. We present 119 new asteroid models derived from combined dense and sparse-in-time photometry. We discuss the reliability of asteroid shape models derived only from Catalina Sky Survey data (IAU code 703) and present 20 such models. By using different values for a scaling parameter cYORP (corresponds to the magnitude of the YORP momentum) in the dynamical model for the spin evolution and by comparing synthetics and observed pole-latitude distributions...

‣ Review of Some Promising Fractional Physical Models

Tarasov, Vasily E.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/02/2015 Português
Relevância na Pesquisa
46.45853%
Fractional dynamics is a field of study in physics and mechanics investigating the behavior of objects and systems that are characterized by power-law non-locality, power-law long-term memory or fractal properties by using integrations and differentiation of non-integer orders, i.e., by methods of the fractional calculus. This paper is a review of physical models that look very promising for future development of fractional dynamics. We suggest a short introduction to fractional calculus as a theory of integration and differentiation of non-integer order. Some applications of integro-differentiations of fractional orders in physics are discussed. Models of discrete systems with memory, lattice with long-range inter-particle interaction, dynamics of fractal media are presented. Quantum analogs of fractional derivatives and model of open nano-system systems with memory are also discussed.; Comment: 38 pages, LaTeX

‣ Are the modern computer simulations a substitute for physical models? The SKA case

Tingay, Steven J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/09/2012 Português
Relevância na Pesquisa
46.724824%
I consider the question posed to me by the scientific organisers of the conference, "Are the modern computer simulations a substitute for physical models? The SKA case." I briefly consider the current knowledge of computer simulations and of physical prototypes in the context of understanding interferometric radio telescopes. My conclusion is that, "no, computer simulations are not a substitute for physical models when it comes to understanding the SKA.....furthermore, physical models are not much help either." This conclusion is intentionally provocative, designed to promote some discussion at the conference, which it did. However, the conclusion reflects my belief that we do not have a deep enough understanding, theoretical or practical, of how interferometry works, to determine if the SKA will meet the stated specifications or not. I conclude that we need to adopt a qualitatively different approach to dealing with interferometric data. I note that some good work is being done on this front, but it is likely a bigger effort is needed in the SKA era. This is exactly the type of innovation that projects such as the SKA should encourage.; Comment: 7 pages, submitted to proceedings of "From Antikythera to the Square Kilometre Array: Lessons from the Ancients"...

‣ The repository of physical models used for the CODATA-2002 FPC (re-)evaluation

Siver, A. S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/09/2005 Português
Relevância na Pesquisa
46.61834%
We present PAREVAL package containing a repository of theoretical physical models used for (re-)evaluation of the fundamental physical constants (FPC). It holds all necessary data for building 105 (so called) observational equations and can be used in high precision calculations. Among repository models there are expressions for energy levels of hydrogen and deuterium (with 16 types of contributions), electron and muon magnetic moment anomalies, muonium ground-state hyperfine splitting, Zeeman energy levels in muonium. Each model is represented as {\sl Mathematica} module with XML meta-data keeping information about the model (including data on dependence from others models). There are also modules for working with the basic FPC.

‣ SAMBA RECEPTION DESK: COMPROMISING AESTHETICS, FABRICATION AND STRUCTURAL PERFORMANCE WITH THE USE OF VIRTUAL AND PHYSICAL MODELS IN THE DESIGN PROCESS

Barbosa Neto, Wilson; Araujo, André; Carvalho, Guilherme; Celani, Gabriela
Fonte: Universidade de São Paulo. Instituto de Arquitetura e Urbanismo Publicador: Universidade de São Paulo. Instituto de Arquitetura e Urbanismo
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Avaliado Por Pares; Pesquisa-Ação Formato: application/pdf
Publicado em 03/12/2014 Português
Relevância na Pesquisa
56.515176%
The present paper describes an integrative design experiment in which different types of models were used in order to achieve a design that compromises aesthetics, lightness, fabrication, assembly and structural performance. It shows how an integrative aproach, through the use of both virtual and physical models, can provide valuable feedback in different phases of the design and fabrication process. It was possible to conclude that the design method used allowed solving many problems and had a significant impact in the resulting object.

‣ Statistical models for physically derived target sub-spaces

Ientilucci, Emmett; Bajorski, Peter
Fonte: Society of Photo-Optical Instrumentation Engineers Publicador: Society of Photo-Optical Instrumentation Engineers
Português
Relevância na Pesquisa
46.45853%
Traditional approaches to hyperspectral target detection involve the application of detection algorithms to atmo- spherically compensated imagery. Rather than compensate the imagery, a more recent approach uses physical models to generate target sub-spaces. These radiance sub-spaces can then be used in an appropriate detection scheme to identify potential targets. The generation of these sub-spaces involves some a priori knowledge of data acquisition parameters, scene and atmospheric conditions, and possible calibration errors. Variation is allowed in the model since some parameters are di±cult to know accurately. Each vector in the subspace is the result of a MODTRAN simulation coupled with a physical model. Generation of large target spaces can be computationally burdensome. This paper explores the use of statistical methods to describe such target spaces. The statistically modeled spaces can then be used to generate arbitrary radiance vectors to form a sub-space. Statistically modeled target sub-spaces, using limited training samples, were found to accurately resemble MODTRAN derived radiance vectors.; RIT community members may access full-text via RIT Libraries licensed databases: http://library.rit.edu/databases/

‣ The principle and physical models of novel jetting dispenser with giant magnetostrictive and a magnifier

Zhou, C.; Li, J.H.; Duan, J.A.; Deng, G.L.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Text
Publicado em 16/12/2015 Português
Relevância na Pesquisa
46.45853%
In order to develop jetting technologies of glue in LED and microelectronics packaging, giant-magnetostrictive-material (GMM) is firstly applied to increase jetting response, and a new magnifying device including a lever and a flexible hinge is designed to improve jetting characteristics. Physical models of the jetting system are derived from the magnifying structure and working principle, which involves circuit model, electro-magneto-displacement model, dynamic model and fluid-solid coupling model. The system model is established by combining mathematical models with Matlab-Simulink. The effectiveness of the GMM-based dispenser is confirmed by simulation and experiments. The jetting frequency significantly increases to 250 Hz, and dynamic behaviors jetting needle are evaluated that the velocity and displacement of the jetting needle reaches to 320 mm•s-1 and 0.11 mm respectively. With the increasing of the filling pressure or the amplitude of the current, the dot size will become larger. The dot size and working frequency can be easily adjusted.

‣ Physical and numerical modelling of a four-strand steelmaking tundish using flow analysis of different configurations

Cloete,J.H.; Akdogan,G.; Bradshaw,S.M.; Chibwe,D.K.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2015 Português
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46.533125%
Modern tundishes have evolved as vessels to serve as the final step in refining of molten steel by removing inclusions and promoting thermo-chemical homogeneity. In this study the flow behaviour in a four-strand tundish was investigated by means of a ½-scale water model as well as numerical modelling. The numerical and physical models were used to characterize residence time distribution and calculate properties pertaining to tundish flow regime. Three different tundish configurations were investigated: a bare tundish with no flow control devices, a tundish with a turbulence inhibitor, and a tundish with both a turbulence inhibitor and a dam. The physical and numerical models showed that a tundish without flow control devices is prone to significant short-circuiting. A tundish with a turbulence inhibitor was shown to be successful in preventing short-circuiting and provided surface-directed flow that might assist the removal of inclusions from the melt. However, it was also observed that the upward-directed flow caused the maximum turbulence kinetic energy near the surface to increase dramatically. The potential for slag entrainment should therefore be considered during the design and operation of tundishes with turbulence inhibitors.