• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 730
  • 217
  • 202
  • 160
  • 119
  • 85
  • 73
  • 66
  • 47
  • 44
  • 33
  • 25
  • 23
  • 11
  • 8
  • Tagged with
  • 1955
  • 311
  • 248
  • 220
  • 175
  • 169
  • 163
  • 158
  • 158
  • 156
  • 148
  • 148
  • 144
  • 131
  • 130
  • 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.
831

Estratégias de controle não-convencional para uma plataforma de Stewart acionada hidraulicamente / Non-conventional control strategies for a hydraulically driven Stewart platform

Alexandre Simião Caporali 05 December 2003 (has links)
Este trabalho apresenta técnicas de projeto de controle neural e controle difuso para uma plataforma de Stewart acionada hidraulicamente. O modelo dinâmico não linear da plataforma de Stewart com seis graus de liberdade foi desenvolvido no ambiente de sistemas multicorpos ADAMS. Este pacote comercial foi usado para economizar tempo e esforço na modelagem de um sistema mecânico complexo e na programação para obter a resposta no tempo do sistema. A plataforma de Stewart é um manipulador paralelo com alta relação força-peso e acuracidade de posicionamento comparada a manipuladores seriais convencionais. As desvantagens dos mecanismos seriais é que cada articulação suporta o peso da articulação seguinte e mais o objeto a ser manipulado. A plataforma de Stewart tem recebido recentemente considerável interesse de pesquisadores dado o sucesso de suas aplicações e potencial vantagens sobre os manipuladores convencionais. Uma aplicação bastante popular da plataforma de Stewart é o simulador de vôo onde a plataforma executa movimento com acelerações similares àquelas de uma aeronave. Embora muitas pesquisas na literatura tenham dedicado amplo esforço para cinemática, dinâmica e projeto mecânico de manipuladores baseados em plataforma de Stewart, pouca atenção tem sido dada ao problema de controle deste tipo de manipulador. Um esquema de controle difuso e de redes neurais foi adotado para lidar com as não linearidades, distúrbios e incertezas dos parâmetros, e precisão necessária no posicionamento e orientação da plataforma. Redes neurais artificiais e lógica difusa fornecem um paradigma computacional característico e tem demonstrado resultado para uma faixa de problemas práticos onde a técnica computacional convencional não tem sucesso. Em particular, a habilidade do controle neural e do controle difuso para representar mapeamento não linear encoraja o estudo de controle neural e difuso para representar problemas de controle não linear. Resultados de simulação são apresentados, mostrando que as técnicas propostas podem ser usadas na plataforma de Stewart. / This work presents a neural and fuzzy control design technique for a hydraulically driven Stewart platform. The non-linear dynamic model of a Stewart platform with six degrees of freedom was developed in the multibody systems environment ADAMS. This commercial package was used to save time and effort in modelling the complex mechanical system and in the programming to get the time response of the system. The Stewart platform is a parallel manipulator with high force-to-weight ratio and position accuracy compared to conventional serial manipulators. The disadvantage of serial mechanisms is that each link has to support the weigth of all the following links in addition to the object to be supported. The Stewart platform has recently received considerable research interest due to its successful applications and potential advantages over the conventional manipulators. A quite popular application of the Stewart platform is the flight simulator where the platform performs motion with accelerations similar to those of an airplane. Although much of the research in the literature has devoted extensive effort to the kinematics, dynamics and mechanisms design of the Stewart platform-based manipulators, little attention has been paid to the control problem of this type of manipulators. A fuzzy and neural network control scheme was adopted to deal with the nonlinealities, disturbances and uncertainties of the parameters, and required precision in position and orientation the platform. Artificial neural networks and fuzzy logic provide a distinctive computational paradigm and have proven to be effective for a range of practical problems where conventional computation techniques have not succeeded. In particular, the ability of neural and fuzzy control techniques to represent non-linear mappings encourages the study of these techniques to be used for controling complex non-linear control problems. Simulations results are presented, showing that the proposed technique can be used in a Stewart platform.
832

Modelos tecnológicos para planejamento e gestão operacional em terminais especializados em apoio logístico para operações offshore. / Technological models for planning and operational management in terminais specialized in offshore logistical support.

Fabio Del Papa 10 June 2013 (has links)
O presente trabalho tem como objetivo apresentar uma descrição dos modelos tecnológicos aplicáveis em terminais \"OffShore\", especializados em apoio logístico às unidades marítimas de extração de petróleo. Com a expansão do setor petrolífero brasileiro, o apoio logístico ganhou uma importância considerável, tendo em vista o aumento no número de unidades marítimas e a distâncias, superiores a 200 km da costa brasileira. Os terminais \"OffShore\" desempenham um papel importante no elo de transição entre as unidades marítimas e o transporte terrestre e precisam buscar eficiência e rapidez nos seus serviços para atingir índices de produtividade compatíveis com expectativa de aumento na movimentação de carga. A inserção da inteligência computacional permite a otimização dos tempos de espera dos caminhões, a diminuição do tempo de operação das embarcações e do tempo de atendimento dos caminhões, das taxas de ocupação dos equipamentos e otimiza o arranjo da carga no estoque. Um terminal \"OffShore\" é um sistema com vários componentes interligados entre si, consequentemente a ineficiência de um componente interfere em toda cadeia logística do terminal. / The current work aims to show a description of the technological models applicable to OffShore terminals, specialized in logistic support to the maritime units of oil extraction. With the expansion of the Brazilian oil industry, logistics has gained considerable importance in view of the increase in the number of marine units and distances greater than 200 km from the Brazilian coast. The Offshore terminals play an important role in link units transition between sea and land transport, and must seek efficiency and speed in its services to achieve productivity levels consistent with expected increase in cargo handling. The integration of computational intelligence enables optimization of waiting times of trucks, reducing the operating time of vessels and the service time of the trucks, the occupancy rates of the equipment and the arrangement optimizes the load on the stock. A Offshore terminal is a system with several components interconnected, hence the inefficiency of one component affects the entire logistics chain in the terminal.
833

Análise dos caminhos de execução de programas para a paralelização automática de códigos binários para a plataforma Intel x86 / Analysis of the execution paths of programs to perform automatic parallelization of binary codes on the platform Intel x86

André Mantini Eberle 06 October 2015 (has links)
Aplicações têm tradicionalmente utilizado o paradigma de programação sequencial. Com a recente expansão da computação paralela, em particular os processadores multinúcleo e ambientes distribuídos, esse paradigma tornou-se um obstáculo para a utilização dos recursos disponíveis nesses sistemas, uma vez que a maior parte das aplicações tornam-se restrita à execução sobre um único núcleo de processamento. Nesse sentido, este trabalho de mestrado introduz uma abordagem para paralelizar programas sequenciais de forma automática e transparente, diretamente sobre o código-binário, de forma a melhor utilizar os recursos disponíveis em computadores multinúcleo. A abordagem consiste na desmontagem (disassembly) de aplicações Intel x86 e sua posterior tradução para uma linguagem intermediária. Em seguida, são produzidos grafos de fluxo e dependências, os quais são utilizados como base para o particionamento das aplicações em unidades paralelas. Por fim, a aplicação é remontada (assembly) e traduzida novamente para a arquitetura original. Essa abordagem permite a paralelização de aplicações sem a necessidade de esforço suplementar por parte de desenvolvedores e usuários. / Traditionally, computer programs have been developed using the sequential programming paradigm. With the advent of parallel computing systems, such as multi-core processors and distributed environments, the sequential paradigm became a barrier to the utilization of the available resources, since the program is restricted to a single processing unit. To address this issue, we introduce a transparent automatic parallelization methodology using a binary rewriter. The steps involved in our approach are: the disassembly of an Intel x86 application, transforming it into an intermediary language; analysis of this intermediary code to obtain flow and dependency graphs; partitioning of the application into parallel units, using the obtained graphs and posterior reassembly of the application, writing it back to the original Intel x86 architecture. By transforming the compiled application software, we aim at obtaining a program which can explore the parallel resources, with no extra effort required either from users or developers.
834

Mise en œuvre des nouvelles technologies pour l'évaluation du contrôle postural et de l’analyse de la marche / IMPLEMENTATION OF NEW TECHNOLOGIES FOR THE EVALUATION OF POSTURAL CONTROL AND WALK ANALYSIS

Cuarelli, Gilberto 20 December 2018 (has links)
Certains besoins de santé spécifiques ont contribué au développement du travail présenté ici, en particulier dans le domaine de la kinésithérapie dans lequel l’étude de l’équilibre postural est étudiée. Les solutions qui existent aujourd'hui sur le marché sont coûteuses, disponibles uniquement dans les grands hôpitaux ou dans des salles dédiées, avec un faible taux de fréquentation de la population, principalement dans des endroits plus éloignés des grands centres urbains. Ce travail a été développé en collaboration avec une équipe constituée de kinésithérapeutes, de chercheurs en génie électrique et en génie mécanique du laboratoire G-SCOP, Grenoble INP, Institut d’Ingénierie, Univ. Grenoble Alpes, France. Cette équipe cherche des solutions à faible coût qui répondent aux besoins de la société en général, en mettant l'accent sur la santé, mais également sur la vulgarisation scientifique, en diffusant ses travaux lors de manifestations de type fête de la Sciences dans la région et pour la communauté. Les travaux ont débuté avec une plateforme de force développée en 2016, conjointement par des chercheurs de l'UNESP (une Université de l'état Sao Paulo au Brésil) et du laboratoire G-SCOP. A cette solution a été ajoutée une nouvelle interface électronique, développée dans le but de fournir des informations sur le déplacement du centre de pression du patient. Un mécanisme a également été mis en place pour assurer la synchronisation entre les informations capturées par les capteurs installés sur la plate-forme et un capteur Microsoft Kinect. De nouveaux outils logiciels ont été proposés pour capturer et analyser les résultats. Le traitement des données permet de créer un modèle tridimensionnel détaillé contenant la cinématique de plusieurs articulations du corps humain et leur comportement respectif en fonction du temps. La mise en œuvre du capteur Kinect synchronisé avec la plate-forme de force permet de comparer le Centre de Pression avec le Centre de masse en vue de proposer un outil plus léger et moins cher à la communauté des praticiens hospitaliers. / Some specific health needs contributed to the development of the work presented here, especially in Physical Therapy in which the Postural Equilibrium is studied. The solutions that exist today in the market are of expensive, available only in large hospitals or in dedicated rooms, with low index of attendance to the population, mainly in places more distant of the great urban centers. This work was developed in cooperation with a team constituted of Phisiotherpists, Electrical Engineering and Mechanical Engineering from of the G-SCOP Laboratory, Grenoble INP, Institute of Engineering Univ. Grenoble Alpes, France. This team seeks low cost solutions that meet the needs of society in general, with a focus on health, but also with a focus on the popularization of science, disseminating its work in basic schools in the region and also in the community. The work began with a strength platform developed in 2016, jointly by researchers from UNESP, Sao Paulo, Brasil, and the G-SCOP Laboratory. To this solution was added a new electronic interface, developed with the purpose of providing information on the displacement of the patient pressure center. A mechanism was also implemented to ensure synchronization between information captured by sensors installed on the platform and a Microsoft Kinect sensor. New software tools were developed to capture and analyze the results. The data treatment allows the creation of a detailed three-dimensional model, containing the kinematics of several joints of the human body and their respective positional behavior, as a function of time. With the implementation of the Kinect sensor, synchronised with the force platform, it is also possible to evaluate the kinematic and positional biomechanical parameters.
835

Translational assessment of cognitive impairments in depression models

Martis, Lena-Sophie January 2018 (has links)
Major depressive disorder (MDD) affects 300 million people worldwide and is a major contributor to the global burden of disease. The aetiology of depression, emerging through a gene x environment interaction, is still incompletely understood which prevents tailoring of treatment approaches. In addition to MDD core symptoms, such as anhedonia (a diminished anticipation or experience of pleasure), depressed patients suffer from a plethora of manifestations including cognitive impairments, which occur primarily in the domains of executive function, attention and memory. Patients remitted from affective symptoms of MDD often continue to display cognitive impairments. These cognitive deficits are the longest present residual symptom, predict treatment response and increase risk of relapse. Consequently, cognitive impairments need to be targeted more effectively by antidepressants for complete remission from MDD. Clinically relevant animal models are essential for developing, tailoring and testing such novel, pro-cognitive antidepressants. This PhD project aimed to establish a preclinical screening platform for the testing of pro-cognitive antidepressants, to improve understanding of MDD risk factors and consequent symptom development, and finally, to focus on clinical relevance of the applied techniques. The chronic mild stress (CMS) rodent model of depression was used, known for displaying the core symptom anhedonia, but also for a high construct, face and predictive validity. The environmental MDD risk factor 'stress' induces an anhedonic-like phenotype in a subgroup of exposed rats, whereas another subgroup of rats is resilient, as determined by the sucrose consumption test. The cognitive performance of different rat strains, including CMS anhedonic-like and resilient rats, was assessed employing the touchscreen operant platform, which was developed based on the Cambridge neuropsychological test automated battery (CANTAB) for assessing cognition in humans. Furthermore, a group of anhedonic-like rats was treated with the antidepressant vortioxetine, which acts as both a pro-cognitive and antidepressant treatment. Our results showed that stress exposure induced anhedonia in albino and pigmented rat strains, although stress did not affect cognitive performance of pigmented rats in a simple pairwise discrimination touchscreen task. Applying a more complex pairedassociates learning touchscreen task revealed impaired cognitive performance in the CMS anhedonic-like but not in the resilient phenotype. Furthermore, vortioxetine treatment reversed anhedonia in the CMS model and altered executive functions in treated rats. The expression of genes involved in the stress response, affective disorders and neuronal plasticity was altered in the prefrontal cortex and hippocampus owned to treatment and hedonic state. Thus, we have demonstrated that the CMS model exhibits both stress-induced cognitive alterations and depression-associated cognitive impairments in touchscreen tasks. Furthermore, touchscreen testing was sufficiently sensitive to detect alterations in cognitive performance due to pharmacological intervention. Overall, we established a potential platform for pro-cognitive antidepressant drug screening. Furthermore, brain derived neurotrophic factor (BDNF), involved in learning and memory, was examined in the context of depression. BDNF is reduced in MDD patients as well as in preclinical models in response to stress. Although this suggests that BDNF contributes to the aetiology of depression, studies including mice heterozygous for BDNF (BDNF+/-) have generated conflicting results. BDNF+/- rats may provide a more suitable model as (1) rats have a greater behavioural repertoire than mice, (2) classical behaviour tests are designed for rats, and (3) rats, like humans, produce peripheral BDNF. We found anhedonia and mild signs of anxiety in BDNF+/- rats, accompanied by prefrontal and hippocampal changes in expression of genes relevant in psychiatric disorders and underpinning learning. Thus, behavioural and molecular findings in BDNF+/- rats complement existing literature and suggest that rats are a more suitable model in BDNF research than mice. Overall, the project uncovered environmental and genetic manifestations of risk factors in translational models and established a novel tool for translational pro-cognitive antidepressant drug screening.
836

Estratégias de controle não-convencional para uma plataforma de Stewart acionada hidraulicamente / Non-conventional control strategies for a hydraulically driven Stewart platform

Caporali, Alexandre Simião 05 December 2003 (has links)
Este trabalho apresenta técnicas de projeto de controle neural e controle difuso para uma plataforma de Stewart acionada hidraulicamente. O modelo dinâmico não linear da plataforma de Stewart com seis graus de liberdade foi desenvolvido no ambiente de sistemas multicorpos ADAMS. Este pacote comercial foi usado para economizar tempo e esforço na modelagem de um sistema mecânico complexo e na programação para obter a resposta no tempo do sistema. A plataforma de Stewart é um manipulador paralelo com alta relação força-peso e acuracidade de posicionamento comparada a manipuladores seriais convencionais. As desvantagens dos mecanismos seriais é que cada articulação suporta o peso da articulação seguinte e mais o objeto a ser manipulado. A plataforma de Stewart tem recebido recentemente considerável interesse de pesquisadores dado o sucesso de suas aplicações e potencial vantagens sobre os manipuladores convencionais. Uma aplicação bastante popular da plataforma de Stewart é o simulador de vôo onde a plataforma executa movimento com acelerações similares àquelas de uma aeronave. Embora muitas pesquisas na literatura tenham dedicado amplo esforço para cinemática, dinâmica e projeto mecânico de manipuladores baseados em plataforma de Stewart, pouca atenção tem sido dada ao problema de controle deste tipo de manipulador. Um esquema de controle difuso e de redes neurais foi adotado para lidar com as não linearidades, distúrbios e incertezas dos parâmetros, e precisão necessária no posicionamento e orientação da plataforma. Redes neurais artificiais e lógica difusa fornecem um paradigma computacional característico e tem demonstrado resultado para uma faixa de problemas práticos onde a técnica computacional convencional não tem sucesso. Em particular, a habilidade do controle neural e do controle difuso para representar mapeamento não linear encoraja o estudo de controle neural e difuso para representar problemas de controle não linear. Resultados de simulação são apresentados, mostrando que as técnicas propostas podem ser usadas na plataforma de Stewart. / This work presents a neural and fuzzy control design technique for a hydraulically driven Stewart platform. The non-linear dynamic model of a Stewart platform with six degrees of freedom was developed in the multibody systems environment ADAMS. This commercial package was used to save time and effort in modelling the complex mechanical system and in the programming to get the time response of the system. The Stewart platform is a parallel manipulator with high force-to-weight ratio and position accuracy compared to conventional serial manipulators. The disadvantage of serial mechanisms is that each link has to support the weigth of all the following links in addition to the object to be supported. The Stewart platform has recently received considerable research interest due to its successful applications and potential advantages over the conventional manipulators. A quite popular application of the Stewart platform is the flight simulator where the platform performs motion with accelerations similar to those of an airplane. Although much of the research in the literature has devoted extensive effort to the kinematics, dynamics and mechanisms design of the Stewart platform-based manipulators, little attention has been paid to the control problem of this type of manipulators. A fuzzy and neural network control scheme was adopted to deal with the nonlinealities, disturbances and uncertainties of the parameters, and required precision in position and orientation the platform. Artificial neural networks and fuzzy logic provide a distinctive computational paradigm and have proven to be effective for a range of practical problems where conventional computation techniques have not succeeded. In particular, the ability of neural and fuzzy control techniques to represent non-linear mappings encourages the study of these techniques to be used for controling complex non-linear control problems. Simulations results are presented, showing that the proposed technique can be used in a Stewart platform.
837

A evolução das plataformas no setor de software: uma análise na perspectiva das capacitações das organizações. / The evolution of the platforms in the software industry: an analysis in the capabilities perspective of organizations.

Facin, Ana Lucia Figueiredo 29 August 2017 (has links)
O conceito \"plataforma\" tem sido explorado em pesquisas sobre desenvolvimento de produtos, estratégia tecnológica e economia industrial. O uso de plataformas dentro das empresas e, mais recentemente, para mediar atividades de aglomerados ou ecossistemas de empresas têm sido reconhecidos como de grande importância na gestão de novos negócios, no desenvolvimento de novos produtos e na inovação. Google, Facebook, SAP, Microsoft e Apple são exemplos de empresas do setor de software cujas plataformas têm inspirado muitas outras empresas a desenvolverem produtos e serviços complementares. Ao analisar sistematicamente a literatura sobre plataformas, combinando análises bibliométricas e de conteúdo, foi possível verificar a existência de lacunas a serem estudadas no que se refere à teoria da evolução das plataformas e às adaptações organizacionais das empresas que se baseiam em plataformas para o desenvolvimento de seus produtos. Visando estender essa teoria, o objetivo desta tese foi investigar capacitações vinculadas ao relacionamento entre proprietárias de plataformas e desenvolvedores que complementam estas plataformas, como meio para compreender como elas evoluem de internas para externas. A abordagem metodológica escolhida foi a pesquisa qualitativa realizada mediante estudo de casos múltiplos em empresas nacionais e internacionais que atuam no setor brasileiro de software. Foram analisadas seis plataformas em organizações que são proprietárias de plataformas de software, e dezesseis empresas desenvolvedoras que contribuem com produtos ou serviços complementares a estas plataformas. Os resultados trouxeram algumas contribuições; a revisão sistemática da literatura, por exemplo, permitiu uma melhor compreensão e clareza sobre a evolução do conceito plataforma com identificação de tendências e temas emergentes para pesquisa. O estudo de casos realizado contribuiu com a identificação e a classificação de um conjunto de capacitações por tipo de plataforma, considerando a perspectiva do proprietário da plataforma e dos desenvolvedores. E como principal contribuição deste trabalho, tanto para teoria como para prática, fica a proposição de um quadro teórico estendido, que indica que para evoluir de uma plataforma interna para uma plataforma externa, as proprietárias de plataformas desenvolvem determinadas capacitações vinculadas ao relacionamento com desenvolvedores de software, de acordo com o tipo de plataforma. Em relação aos desenvolvedores, esse quadro aponta para o desenvolvimento de capacitações adaptadas ao tipo de plataforma. Espera-se que este trabalho contribua para o debate sobre plataformas e capacitações. / The concept of \"platform\" has been explored in many studies on product development, technology strategy, and industrial economy. The use of platforms within companies and, more recently, in mediating the activities within clusters or ecosystems of businesses, has been recognized as highly significant for the management of new businesses, for the development of new products, and for innovation. Google, Facebook, SAP, Microsoft and Apple are examples of companies in the software industry whose platforms have inspired many other businesses to develop complementary products and services. By systematically analyzing the literature on platforms, combining bibliometric analyses with content analyses, it was possible to observe the existence of gaps to be filled concerning the theory of the evolution of platforms, and the processes of organizational adaptation that platform-based companies undergo in the development of their products. Aiming at extending the theory, the objective of this work has been that of investigating capabilities associated to the relationships between platform owners and developers as a means to understand how platforms evolve from internal platforms to external platforms. The methodology chosen for this work was a qualitative study conducted via case study of multiple cases with national and international companies present in the Brazilian software industry. Six examples of software platform owners were examined, along with sixteen developers that contribute with products and services that extend those platforms. The results of the study make a few contributions to this topic; the systematic review of the literature, for example, allows a better, clearer understanding of the evolution of the concept of platform, identifying trends and emerging themes for research. The case studies contribute to identify and classify a set of capabilities by type of platform, considering the perspective of the owner and that of the developers. And as the main contribution of this work, both for theory and for practice, we have the proposition of an extended theoretical framework that indicates that, in order to evolve from an internal platform to an external one, the platform owners develop certain capabilities associated to their relationship with software developers, according to the type of platform. Regarding developers, this framework points to the development of capabilities adapted to the type of platform. We hope that this work will contribute to the ongoing debate about platforms and capabilities.
838

Data-driven framework for forecasting sedimentation at culverts

Xu, Haowen 01 May 2019 (has links)
The increasing intensity and frequency of precipitation in recent decades, combined with the human interventions in watersheds, has drastically altered the natural regimes of water and sediment transport in watersheds over the whole contiguous United States. Sediment-transport related concerns include the sustainability of aquatic biology, the stability of the river morphology, and the security and vulnerability of various riverine structures. For the present context, the concerns are related to the acceleration of upland erosion (sediment production) and in-stream sediment-transport processes that eventually lead to sediment accumulation at culverts (structures that pass streams under roadways). This nuisance has become widespread in many transportation agencies in the United States, as it has a direct bearing on maintaining normal culvert operations during extreme flows when these waterway crossings are essential for the communities they serve. Despite the prevalence of culvert sedimentation, current specifications for culvert design do not typically consider aspects of sediment transport and deposition. The overall study objective is to systematically identify the likelihood of culvert sedimentation as a function of stream and culvert geometry, along with landscape characteristics (process drivers of culvert sedimentation) in the culvert drainage area. The ideal approach for predicting sedimentation is to track sediment sources dislocated from the watershed, their overland movement, and their delivery into the streams using physical-based modeling. However, there are considerable knowledge gaps in addressing the sedimentation at culverts as an end-to-end process, especially in connecting the upland with in-stream processes and simulating the sediment deposition at culverts in non-uniform, unsteady flows, while also taking into account the vegetation growth in culverts’ vicinity. It is, therefore, no surprise that existing research, textbooks, and guidelines do not typically provide adequate information on sediment control at culverts. This dissertation presents a generalizable data-driven framework that integrates various machine-learning and visual analytics techniques with GIS in a web-based geospatial platform to explore the complex environmental processes of culvert sedimentation. The framework offers systematic procedures for (1) classifying the culvert sedimentation degree using a time-series of aerial images; (2) identifying key process-drivers from a variety of environmental and culvert structural characteristics through feature selections and interactive visual interfaces; (3) supporting human interactions to perceive empirical relationships between drivers and the culvert sedimentation degree through multivariate Geovisualization and Self-Organizing Map (SOM); and (4) forecasting culvert sedimentation potential across Iowa using machine learning algorithms. Developed using modular design and atop national datasets, the framework is generalizable and extendable, and therefore can be applied to address similar river management issues, such as habitat deterioration and water pollution, at the Contiguous US scale. The platform developed through this Ph.D. study offers a web-based problem-solving environment for a) managing inventory and retrieving culvert structural information; b) integrating diverse culvert-related datasets (e.g., culvert inventory, hydrological and land use data, and observations on the degree of sedimentation in the vicinity of culverts) in a digital repository; c) supporting culvert field inspections and real-time data collection through mobile devices; and d) hosting the data-driven framework for exploring culvert sedimentation drivers and forecasting culvert sedimentation potential across Iowa. Insights provided through the data-driven framework can be applied to support decisions for culvert management and sedimentation mitigation, as well as to provide suggestions on parameter selections for the design of these structures.
839

Discrete Linear Constrained Multivariate Optimization for Power Sources of Mobile Systems

Ioannou, Stelios G 03 November 2008 (has links)
Unmanned ground and aerial vehicles (UGVs and UAVs) have strict payload limitations, limited free space affecting on board power availability resulting in limited endurance and operational range. This limitation is exacerbated by the addition of sensors, actuators and other related equipment needed to accomplish mission objectives in diverse applications. Two energy sources are mainly available for mobile applications; batteries and fuel cells. Batteries are a relatively cheap, tested technology with good performance under varying loads. On the other hand, fuel cells offer fast and easy refueling solutions. Furthermore, preliminary studies have shown that a hybrid system can combine the advantages of both technologies offering a superior system. It is true that for most outdoors applications, payload needs, sensor suite utilization and energy requirements are apriori unpredictable. This makes proper sizing of energy storage devices and the prediction of remaining available energy rather difficult tasks. This research proposes an indirect way of improving the operational range for UAVs of Vertical Take Off and Landing (VTOLs), since the VTOL vehicle is transported to the mission site without the need to fly. The proposed gimballed platform, which will be a power source itself, rotates around two axes perpendicular to each other, allowing the VTOL to take-off and land, regardless of the position of the UGV, while securing it during transportation. The UGV can also serve as a charging station for the VTOL. Furthermore, this research proposes a Matlab Simulation tool that can simulate the energy and power demand of small to mid-sized robotic vehicles. This model will simulate the power consumption in the motors based on Skid steering, road gradient, linear and angular velocity. With the energy and power requirements estimated, a Matlab optimization tool is proposed to be used to determine the optimal configuration of a power system for mobile applications under constraints relating to capacity/runtime, weight, volume, cost, and system complexity. The configuration will be based on commercially available batteries, and fuel cells to significantly reduce cost and delivery time. The optimization tool can be used for any mobile application. Finally, a new model is proposed for the accurate prediction of battery runtime and remaining energy for single battery discharge. This model reformulates Peukert's equation and achieves higher accuracy by introducing a new concept of variable exponent which is a function of battery capacity and discharge current.
840

Development of Simulation Platform for Oropharyngeal Airway Placement and Design Evaluation of the Bardo Airway

Lee, Lewis On Hang 01 December 2012 (has links)
Off-label use of traditional Oropharyngeal Airway (OPA) as a bite-block, and the subsequential procedure of force exertion of the device by physician has caused many cases of patient’s teeth damage and monetary loss, as the patient’s incisors were damaged while clenching on the OPA during an adverse scenario called “Emergency Clenching”. To remedy this harmful situation, Bardo OPA was developed by Dr. Theodore Burdumy. The Bardo airway has unique design to transfer the clenching force from incisor to the molar. However, the Bardo OPA is one-sized, and cannot fit most of the patients like the commonly-used OPAs, such as the Berman and Gudel OPA, which have a spectrum of sizes to ensure fit. In this project, a Computer Assisted Design (CAD) simulation platform was developed to simulate the scenario where OPA is placed in a patient’s oral cavity. CAD – related technique and tools, such as 3D scanner (ScanStudio HD), RapidWorks, SolidWorks and Mimics were utilized to create the models used to construct the platform. The purpose of this platform is to generate data to support the development of additional sizes and other modification to improve the current design of the Bardo OPA. MRI sets of nine (9) patients were obtained and converted into STL mesh models. Berman and Guedel OPA were used as the standard for comparison against the Bardo OPA. It was found that the Bardo OPA was able to fit into all sample patients’ models, while these models were fitted with Berman and Guedel OPA of 70-90mm (Small to medium adult) sizes. It can only be concluded that the Bardo is compatible with these OPA sizes and there was not enough evidence to show the need for additional sizes. Nevertheless, some functional features of the Bardo OPA were found potentially harmful to the patients or ineffective. Three approaches were suggested to improve the design of the Bardo to achieve better safety and efficacy.

Page generated in 0.0438 seconds