• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1389
  • 305
  • 71
  • 51
  • 48
  • 22
  • 22
  • 22
  • 21
  • 17
  • 14
  • 14
  • 8
  • 8
  • 8
  • Tagged with
  • 2013
  • 807
  • 542
  • 368
  • 291
  • 208
  • 200
  • 165
  • 151
  • 142
  • 137
  • 135
  • 129
  • 122
  • 120
  • 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.
161

Modelagem matematica e aproximação numerica do estudo de poluentes no ar

Castro, Sonia Elena Palomino 21 December 1993 (has links)
Orientador: João F. D. C. Azevedo Meyer / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Científica / Made available in DSpace on 2018-07-19T14:15:06Z (GMT). No. of bitstreams: 1 Castro_SoniaElenaPalomino_M.pdf: 1708138 bytes, checksum: b09153b3c090a6fa62b37e9d22497a25 (MD5) Previous issue date: 1993 / Resumo: Não informado. / Abstract: In this work the mathematical modelling, and the numerical simulation of the concentration of pollutants in the air is presented. An advective-diffusive evolution partial differencial equation is used, where poluttants transpot is caused by the predominant air movement. Finite Elements of first and second order are used for space variables, and Crank-Nicolson techniques for Finite Differencies for the time variable. / Mestrado / Mestre em Matemática Aplicada
162

The Neoproterozoic tectonic evolution of the western Jiagenen Orogenic Belt and its Early Paleozoic-Mesozoic tectonic reworking / Evolution tectonique Néoproterozoïque de la chaîne de Jiangnan Occidental et sa réactivation au Paléozoïque inférieur Mésozoïque

Yan, Chaolei 29 October 2018 (has links)
La chaîne de collision d'âge néoprotérozoïque de Jiangnan, orientée NE-SW, marque la limite entre les blocs duYangtze et de Cathaysia. Son évolution tectonique reste encore débattue. Une des questions les plus controversées est l'âge de la collision entre les deux blocs. Afin d'acquérir une meilleure compréhension de ce problème, nous avons collecté des échantillons dans les couches sédimentaires situées au-dessus et au-dessous de la discordance dans le but de comparer les spectres d'âge des zircons détritiques et aussi de les confronter à ceux décrits dans les séries néoprotérozoïques des régions du Yangtze, Jiangnan et Cathaysia. En outre, nous nous sommes intéressés aux plutons granitiques d'âge néoproterozoïque de Sanfang et Yuanbaoshan, de type-S, situés dans la partie occidentale de la chaîne de Jiangnan afin de tracer l'évolution tectonique de la région depuis 830 Ma par la mise en œuvre de méthodes pluridisciplinaires : géologie structurale, géochronologie U-Pb, AMS, modélisation gravimétrique et thermochronologie Argon.Notre étude montre les résultats suivants : (i) La chaîne de Jiangnan s'est formée par la collision des blocs de Yangtze et Cathaysia entre ca. 865 and 830 Ma ; (ii) Les intrusions granitiques de 830 Ma se sont mises en place dans des formations encaissantes du groupe Sibao plissées et faillées. Les plutons ont été construits par accumulation latérale E-W de filons N-S, avec un écoulement horizontal du magma du sud vers le nord ; (iii). Un cisaillement ductile du haut vers l'Ouest a été reconnu dans la partie supérieure des plutons. Des âges Ar/Ar vers 420 Ma obtenus sur plusieurs grains de muscovite et biotite déformés impliquent que le cisaillement ductile peut être : a) formé pendant l'orogenèse du Paléozoïque inférieur de Chine du Sud, ou b) pendant la mise en place des plutons au Néoprotérozoïque dans une croûte chaude, sous la température de fermeture du chronomètre argon, puis lors de l'orogenèse du Paléozoïque inférieur, ce domaine crustal de Chine du Sud est passé au-dessous de 350°C; (iv) Durant la période 420-240 Ma, la région de Sanfang-Yuanbaoshana connu un refroidissement lent qui pourrait correspondre au ré-équilibrage isostatique de la croûte. / The Jiangnan Orogenic Belt is a NE-SW trending Neoproterozoic collisional suture, marking the boundary between the Yangtze Block and the Cathaysia Block. Its tectonic evolution is still debated. One of the most controversial questions is the timing of the collision between the Yangtze and Cathaysia blocks. In order to have a better understanding of this problem, we have collected the sedimentary rocks from the strata both overlying and underlying the Neoproterozoic unconformities to compare the detrital zircon age spectra between them, as well as to compare the detrital zircon spectra of Neoproterozoic sequences among the Yangtze, Jiangnan and Cathaysia regions. Moreover, we paid attention to the Neoproterozoic S-type granite plutons located in the western Jiangnan region in order to trace the crustal evolution in the Sanfang-Yuanbaoshan area since 830 Ma by multidisciplinary methods, including structural geology, geochronology, AMS, gravity modelling and Argon isotopic dating.Our study shows that : (i) The Jiangnan Orogenic Belt was built up due to the assembly of the Yangtze and Cathaysia blocks between ca. 865 and 830 Ma ; (ii) The 830 Ma granitic magma intruded into the pre-existing folds and faults in the Sibao group, the tongue-and/orsill-shaped plutonswere constructed by anE-W lateral accumulation of N-S oriented dykeswith adominantly northward horizontal magma flow from south to north ; (iii)A top-to-the-W ductile shearband has been identified on the top of plutons, (iv) the coherent mica Ar-Ar age of ca. 420 Ma, obtained from the deformed muscovite, implies that this shearing may be formed either a)during the Early Paleozoicorogeny, or b) during the Neoproterozoic plutons emplacement, then the plutons were exhumed by the Paleozoic orogeny ; (iv) During the 420-240 Ma period, the Sanfang-Yuanbaoshan area has experienced a slow cool ingrate, which may correspond to the isostatic re-equilibration of the crust.
163

Convexity in the Design of Bounded Surfaces and Unconventional Solids Using GeoGebra AR

Flores-Osorio, Alejandro Isaías, Lobo-da-Costa, Nielce Meneguelo, Espejo-Peña, Dennis Alberto, Cabracancha-Montesinos, Lenin Rolando 01 January 2022 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The present investigation focuses on the mathematical concept of convexity, as the main tool for the graphic construction of bounded surfaces explicitly and implicitly described, as well as the construction of unconventional solids using GeoGebra. Two cases are presented in which the importance of the concept of convexity is highlighted, in the first situation the convexity is used in the argument of the surface command together with the curves that delimit it to graph a bounded surface, while in the second situation the convexity is evidenced by expressing the coordinates of the surface in parametric form. On the other hand, the 3D graphic view combined with the GeoGebra AR tool allows one to visualize, manipulate, understand and improve the abstraction of mathematical objects that are built in three-dimensional space in a dynamic and friendly environment. These constructions in three-dimensional space that are complex when sketching them with pencil and paper are easier when linking the mathematical definitions with free software such as GeoGebra. / Revisón por pares
164

mHealth Tracker to Track Postural Stability and Pain History

Chen, Jia 23 May 2019 (has links)
No description available.
165

[pt] ESTUDO DO ESCOAMENTO DE UM FLUIDO REAL COM DENSIDADE ESTRATIFICADA PASSANDO POR UM OBSTÁCULO / [en] STUDY OF REAL FLUID FLOW WITH DENSITY STRATIFIED THROUGH AN OBSTACLE

LUCIANO MAGNO COSTALONGA VAREJAO 13 August 2012 (has links)
[pt] O objetivo deste trabalho é estudar o comportamento de um fluido real com densidade estratificada quando passa por um obstáculo. A partir das equações gerais da Mecânica dos Fluidos desenvolvida para vorticidade e função de corrente, obtém-se duas equações diferenciais parciais ambas elípticas, constituindo o modelo matemático do escoamento. O método numérico TUBE AND TANK, desenvolvido por Gosman et al. (1), análogo ao das diferenças finitas, é utilizado para transformar as equações diferenciais em equações algébricas. As condições de contorno necessárias ao problema foram tais que o escoamento estudado se tornou idêntico àquele analisado por Forchtgott(3). Com o auxílio de um computador IBM/370 foi possível obter os resultados que estão de acordo com as observações de Forchtgott(3). / [en] The main purpose of this work is to study the behavior of the real density stratified fluid flowing over an obstacle. From the general equations of fluid mechanics developed in terms of vorticity and stream functions two elliptical partial differential equations which constitute the mathematical flow model were obtained. The numerical method TUBE AND TANK, developed by Gosman et al. (1), analogous to the finite differences method, was used to transform the partial differential equations into algebraic equations. The boundary conditions used in the problem were such that the flow was indentical to that analyzed by Forchtgott(3). Using an IBM/370 computer it was possible to obtain the resultswhich are in agreement with those observed by Forchtgott(3).
166

The Dilemma of Aspirin Resistance in Obese Patients

Ardeshna, Devarshi, Khare, Sarthak, Jagadish, Pooja S., Bhattad, Venugopal, Cave, Brandon, Khouzam, Rami N. 01 September 2019 (has links)
Aspirin resistance (AR) commonly refers to the concept of reduced aspirin efficacy in preventing cardiovascular disease and platelet inhibition. Obesity increases the risk of heart disease three- to four-fold and has been associated with AR. Aspirin is used as a tool for both primary and secondary prevention, but recent studies suggest that its lack of efficacy for primary prevention is partly attributable to obesity. Several mechanisms have been described that contribute to AR in obese patients using pharmacokinetics and pharmacodynamics. AR may be attenuated through weight loss, alternative dosing regimens, and different drug formulations. With the global rise of obesity, it is imperative to find preventive therapies that adequately address atherosclerotic cardiovascular disease (ASCVD) risk in this population.
167

Enhancing mobile advertising through 3D and AR

Linnarson, Erik January 2023 (has links)
Augmented Reality (AR) is making its way into many industries, with advertising being no exception. Existing literature within the field have focused on investigating the benefits of AR advertising from the perspective of businesses, for instance by measuring purchase intention and effect on attitude towards the brand. The present study investigated how AR advertising may be beneficial for the customer. This was done by carrying out a quantitative survey investigating how 2D, 3D and AR advertising differ in terms of knowledge of product dimensions, confidence in assessment of product, as well as expectations on products. The results showed that both 3D and AR are rich mediums, and can be effectively used by advertisers to promote a better understanding of products, instill confidence, and set realistic expectations with consumers.  The results indicate that this is more true for products, or product properties, that can be accurately understood based on vision alone. The results also showed that this is true to some degree for material properties, however not to the same extent.
168

Cascade RLS with Subsection Adaptation

Zakaria, Gaguk 26 February 2000 (has links)
Speech coding or speech compression is one of the important aspects of speech communications nowadays. By coding the speech, the speed needed to transmit the digitized speech, called the bit rate, can be reduced. This means that for a certain speech communications channel, the lower the bit rate of the speech coding, the more communicating parties can be carried on that channel. This research has as its main application the extraction of the parameters of human speech for speech coding purposes. We propose an RLS-based cascade adaptive filter structure that can significantly reduce the computational effort required by the RLS algorithm for inverse filtering types of applications. We named it the Cascade RLS with Subsection Adaptation (CRLS-SA) algorithm. The reduction in computational effort comes from the fact that, for inverse filtering applications, the gradients of each section in the cascade are almost uncorrelated with the gradients in other sections. Hence, the gradient autocorrelation matrix is assumed to be block diagonal. Since we use a second order filter for each section, the computation of the adaptation involves only the 2x2- gradient autocorrelation matrix for that section, while still being based on a global minimization criterion. The gradient signal of a section itself is defined as the derivative of the overall output error with respect to the coefficients of the particular section, which can be computed efficiently by passing the overall output of the cascade to a filter with coefficients that are derived from the coefficients of that section. The computational effort of the CRLS-SA algorithm is approximately 20*L*N/2, where L is the data record length and N is the order of the filter. We analyze the convergence rate of the CRLS-SA algorithm based on the convergence time constant concept, which is the ratio of the condition number and the sensitivity. The CRLS- SA structure is shown to satisfy the DeBrunner-Beex conjecture which says that a structure with a smaller convergence time constant converges faster than a structure with a larger convergence time constant. We show that CRLS-SA converges faster than the Direct Form RLS (DFRLS) algorithm and that its convergence time constant is lower than that of the direct form. The convergence behavior is verified by looking at how fast the estimated system approaches the true system. Here we use the Itakura distance as the measure of closeness between the estimated and the true system. We show that the Itakura distance associated with the CRLS-SA algorithm approaches zero faster than that associated with the direct form RLS algorithm. The CRLS-SA algorithm is applied in this dissertation to general linear prediction, to the direct adaptive computation of the LSF and their representation in quantized form using a split vector quantization (VQ) approach, and to the detection and tracking of the frequencies in signals consisting of multiple sinusoids in noise. / Ph. D.
169

Subjective Evaluation of Marker-Based and Marker-Less AR for an Exhibition of a Digitally Recreated Swedish Warship

Stridbar, Lucas, Henriksson, Emma January 2019 (has links)
Background: In recent years, research in the field of Augmented Reality (AR) in cultural heritage has been rapidly expanding, due to the advancement of technology and availability of cheaper “off the shelf” hardware. It is, amongst other things, being used as a means to increase availability and regain the public’s interest in cultural heritage.Objectives: This study compares marker-based and marker-less AR in perceived usability and perceived performance through a user study. Methods: With the use of the software Unity3D and Vuforia, two AR applications were implemented. Both applications display a model of an 18th-century Swedish warship, based on a wooden ship model, each using one of the two AR methods. The digital model was remade in Autodesk Maya, to suit the needs of an AR application used on mobile devices. The applications were evaluated in a user study with 14 participants. Each participant was asked to perform a simple task of walking around the displayed ship and then answering a questionnaire on usability. This process was done for both applications, followed by a post-experiment questionnaire on perceived performance where the two methods were compared. Results: The result of the study showed that both applications were perceived as usable and well performing. The result of the usability questionnaire showed that the applications were considered usable, with an average of 90.5 points for marker-based AR and 86.8 points for marker-less AR on a 0-100 point scale. Regarding performance, the marker-based method was perceived as better performing. Conclusions: The participants felt that with just a few instructions, the applications were easy to use, even though 50% of them had no previous experience in using AR, that it could enhance a museum exhibition. Possible further development of the app would be to complete the ship-model by adding more details that are currently missing.
170

Medição, predição e análise de partículas aéreas em salas cirúrgicas. / Measurement, prediction and analysis of airborne particles in surgical rooms.

Pereira, Marcelo Luiz 10 October 2008 (has links)
Os sistemas de condicionamento de ar exercem função importante em uma sala cirúrgica, que é proteger a ferida cirúrgica e os equipamentos estéreis dos microrganismos carreados pelo ar. Essa proteção é feita pelo controle simultâneo da movimentação e distribuição do ar, da temperatura, da umidade, da filtragem, das infiltrações de ar de outros setores, entre outros. Esses são fatores que afetam diretamente a quantidade de partículas aéreas presentes em uma sala cirúrgica. Dentro deste contexto, no presente trabalho foi desenvolvido um modelo matemático para predição da concentração de partículas em salas cirúrgicas e para determinação da importância relativa dos fatores que interferem na geração e remoção dessas partículas. O modelo proposto baseia-se no balanço de massa para o cálculo da concentração de partículas, que foi aplicado e validado com os dados obtidos em salas cirúrgicas com diferentes tipos de sistemas de condicionamento de ar. Nessas salas cirúrgicas foram realizadas medições de variáveis ambientais considerando diferentes situações que normalmente ocorrem na rotina de salas cirúrgicas. Para cada uma das condições analisadas, é proposto um determinado conjunto de parâmetros relativos ao ambiente, ao sistema de condicionamento de ar e às concentrações de partículas provenientes das diversas fontes, que são utilizados como dados de entrada no modelo. O modelo que está sendo proposto também pode ser utilizado como uma importante ferramenta para auxiliar na análise específica dos fatores que afetam tanto a geração como a remoção de partículas. / Air conditioning systems exert an important function in surgical rooms, to protect the surgical wound and the sterile equipments from airborne infected particles. This protection is achieved by means of a simultaneous control of the movement and distribution of the air, of the temperature, of the humidity, of the filtering, of air infiltrations from other sections etc. Those factors directly affect the amount of airborne particles present in a surgical room. Within this context, the present work aimed to develop a mathematical model for the prediction of particle concentrations in surgical rooms and for the determination of the relative importance of the factors that interfere in the generation and removal of those particles. The proposed model, based on mass balance for the calculation of the particle concentrations, has been applied and validated with the data obtained from different types of air conditioning systems in which the measurements were carried out, as well as with different conditions that commonly occur in the routine of surgical rooms. For each one of these conditions, a certain group of relative parameters is proposed to the environment, to the air conditioning system, and to the concentrations of particles originated from the different sources, which are used as input data to the model. The proposed model can also be used as an important tool to aid in the specific analysis of the factors that affect both particle generation and removal.

Page generated in 0.0608 seconds