Siga este enlace para ver otros tipos de publicaciones sobre el tema: Hybrid collectif.
Tesis sobre el tema "Hybrid collectif"
Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros
Consulte los 50 mejores tesis para su investigación sobre el tema "Hybrid collectif".
Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.
También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.
Explore tesis sobre una amplia variedad de disciplinas y organice su bibliografía correctamente.
1
Fosseprez, Charles. "Étude des comportements collectifs dans les écosystèmes microbiens par l'utilisation d'une interaction machine-ecosystème originale". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLET050.
Texto completoResumen
Peu importe l’échelle d’observation, les systèmes biologiques allant des molécules aux cellules et les organismes multicellulaires aux communautés, manifeste des comportements collectifs. De nombreuses idées explicatives ont été avancées basé sur la perception locale. Dans chacun de ces cas, des progrès ont été possible parce que le phénotype au niveau collectif est évident et observable à l’oeil nu, mais aussi en raison de la fonction d’objectif visée dans la compréhension de ces comportements. Ici, j’ai construit un hybride machine-écosystème qui implique un dispositif d’observation, couplé à un générateur de paysage lumineux dans une boucle qui contient un processus d’apprentissage à chaque étape en fonction des données capturées de l’écosystème observé. Afin de combler la difficulté expérimentale entre modélisation et réalité, compte tenu de la complexité profonde du système étudié car la modélisation peut alors ´évoluer avec le la matière observée, qui est réactive envers le paysage adaptatif qui va interagir avec lui, cela permettant d’atteindre des horizons inexplorés et non expérimentalement implémentables pour le moment. Mon projet comporte plusieurs étapes. Construction de l’hybride. Développement et mise en pratique d’algorithmes d’interaction. Mise en place de populations microbiennes simples qui peuvent être maintenu et dont le comportement peut être manipulé via la machine. Expériences pour démontrer le principeNo matter the scale of observation, biological systems ranging from molecules to cells, and multicellular organisms to communities, manifest collective behaviours. Many explanatory ideas have been put forward based on local perception. In each of these cases progress has been possible because the collective-level phenotype is obvious and observable to the naked eye, but also because of the objective function targeted in the understanding of these behaviours. Here I constructed a machine-ecosystem hybrid that involve an observation device, coupled to a light landscape generator in an automated loop that contain a learning process at every step based on data captured from the ecosystem being observed. In order to break the reality gap between modelisation and reality, taking into account the deep complexity of the studied system as the modelisation can then co evolve with the observed matter, that is reactive toward the adaptive landscape that interact with it, and then reach unexplored and not experimentally implementable fields of heuristic. My project involves several stages. Construction of the hybrid. Application and development interaction algorithms. Establishment of simple microbial populations that can be sustained and whose behaviour can be manipulated via the machine. Experiments to demonstrate proof of principle
2
Du, Plessis Jacques J. P. "Performance evaluation of water collecting systems with a hybrid dephlegmator". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95920.
Texto completoResumen
Thesis (MEng) -- Stellenbosch University, 2014.ENGLISH ABSTRACT: Water collection systems are used in wet-cooling towers (WCTs) with fill over which water to be cooled flows and in evaporative air-cooled heat exchangers (EACHEs) having deluged tube bundles over which water flows to transfer heat from the tubes. They collect and remove water falling from the bottom of the fill or heat exchanger tube bundle while allowing air to pass with limited flow resistance. There are basically two types of collection systems, categorized as trough and basin systems. Trough systems comprise of multiple, evenly spaced parallel troughs extended in one direction with inclined capture plates to direct water into the troughs. The water collects in the troughs and drains under gravity to a collecting tank or manifold from where it is pumped to the sprayers. In basin systems water falls directly into an open basin under gravity where it is collected and can be pumped to the sprayers. The hybrid (dry/wet) dephlegmator (HDWD) for air-cooled steam condensers, which is being developed at Stellenbosch University as discussed by Heyns (2008), Owen (2013) and Anderson (2014), requires a more effective water collection system with a lower pressure drop than what current designs have to offer. In this thesis, an existing trough system is systematically evaluated by means of various high speed camera and flow experiments to determine its performance characteristics and to find ways to improve its catchment effectiveness. A modification is proposed which increases the effectiveness from approximately 92% to 100 % with a relatively small increase in pressure drop, by adding a small deflector plate and reducing the spacing between adjacent troughs. Experimental data and CFD models are used to determine the performance characteristics of the modified trough system for design purposes. For comparison, various basin system designs are proposed and investigated using CFD, where the baseline model is validated by means of experimental data of rectangular cooling tower inlets by Kröger (2004). Rectangular cooling tower inlets are relevant as they have a similar re-circulating flow pattern to what is seen with the water basin inlets at the vicinity of the inlet wall. The numerical data is correlated to determine empirical relations for the flow performance characteristics. The comparison between the modified trough and the different basin systems yields that the trough system requires significantly less fan and pumping power than basin systems and the costs are also expected to be less.
AFRIKAANSE OPSOMMING: Wateropvangstelsels word gebruik in nat koeltorings en verdamping verkoelers, waar waterdruppels in teen-vloei is met n lugstroom. Die stelsel vang die water wat val op en verwyder dit uit die lugstroom met 'n minimale lugweerstand. Daar is twee wateropvangstelsels wat as volg gekategoriseer word: trog stelsel en wateropvangbak stelsel. 'n Trog stelsel bestaan uit eweredige gespasieerde trôe parallel aan mekaar met 'n skuinsvlak om water in die kanaal op te vang. Water dreineer as gevolg van swaartekrag na 'n opvangs tenk waarvan dit terug gepomp word na die sproeiers. In 'n wateropvangbak stelsel val water direk in die bak en word terug gepomp na die sproeiers. 'n Lugverkoelde kondenserstelsels met 'n hibriede (droog/nat) deflegmator wat huidiglik by die Stellenbosch Universiteit ontwikkel word benodig 'n meer effektiewe wateropvangstelsel met 'n lae drukval. In hierdie tesis word bestaande trog stelsels sistematies geëvalueer deur middel van verskeie toetse met 'n hoë spoed kamera en lugvloei eksperimente om die werkverrigtingskarakteristieke te bepaal en om die opvangsvermoë te verbeter. 'n Verbetering word voorgestel wat die opvangsvermoë verbeter van ongeveer 92 % na 100 % met 'n relatiewe klein verhoging in die drukval deur 'n klein leilem by te voeg en die spasiëring tussen trôe te verminder. Eksperimentele data en BVD (berekeningsvloeidinamika) modelle word gebruik om die werkverrigtingskarakteristieke te bepaal van die nuwe trog stelsel vir ontwerps doeleindes. Die modelle is bekragtig deur gebruik te maak van literatuur van inlaatverlies korrelasies vir reghoekige koeltorings, soos gedoen deur Kröger (2004). Die inlaat van reghoekige koeltorings het soortgelyke vloeipatrone en vloeiwegbreking soos wat by die inlaat van die wateropvangbak stelsel gesien word. Die numeriese data word gebruik om 'n vergelyking vir die vloei karakteristieke te bepaal. 'n Vergelykende studie tussen die nuwe trog stelsel en die wateropvangbak stelsel het bewys dat die trog stelsel noemenswaardig minder waaier drywing en pomp drywing benodig.
3
Ghauri, Farzan Naseer. "Hybrid Photonic Signal Processing". Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3233.
Texto completoResumen
This thesis proposes research of novel hybrid photonic signal processing systems in the areas of optical communications, test and measurement, RF signal processing and extreme environment optical sensors. It will be shown that use of innovative hybrid techniques allows design of photonic signal processing systems with superior performance parameters and enhanced capabilities. These applications can be divided into domains of analog-digital hybrid signal processing applications and free-space--fiber-coupled hybrid optical sensors. The analog-digital hybrid signal processing applications include a high-performance analog-digital hybrid MEMS variable optical attenuator that can simultaneously provide high dynamic range as well as high resolution attenuation controls; an analog-digital hybrid MEMS beam profiler that allows high-power watt-level laser beam profiling and also provides both submicron-level high resolution and wide area profiling coverage; and all optical transversal RF filters that operate on the principle of broadband optical spectral control using MEMS and/or Acousto-Optic tunable Filters (AOTF) devices which can provide continuous, digital or hybrid signal time delay and weight selection. The hybrid optical sensors presented in the thesis are extreme environment pressure sensors and dual temperature-pressure sensors. The sensors employ hybrid free-space and fiber-coupled techniques for remotely monitoring a system under simultaneous extremely high temperatures and pressures.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
4
Moreno, Puerto Jose. "Performance Evaluation of the Solarus AB Asymmetric Concentrating Hybrid PV/T Collector". Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17096.
Texto completoResumen
The energy sector is currently in a state of change as conventional energy sources are questioned by the need of new clean and sustainable energy sources to satisfy the global energy demand in the long term. Renewable energies respond to this increasing demand and solar energy is an advanced example of them. Photovoltaic modules are experiencing a steady reduction in their production costs. It is needed that this trend continues and, along with it, their propagation and expansion in the market continues. One way of reducing production costs is by using inexpensive light concentrators to increase the output of the costly photovoltaic cell. In this respect, the Solarus AB hybrid PV/T collector has been designed based on this principle. This collector is a CPC (Compound Parabolic Collector) and belongs to the MaReCo (Maximum Reflector Collector) family. The aim of this thesis is to deeply investigate this technology in two main areas. Firstly, the collector will be tested both electrically and thermally in order to evaluate its performance. To do so, a solar test rig has been built and connected at the building Hall 45 of Högskolan i Gävle, Gävle, Sweden. The second main area of investigation of this thesis is to determine the optimal price for the Solarus AB hybrid PV/T collector in order to be competitive in the solar energy market. This study will be based in the current market prices of photovoltaic and thermal collectors. Regarding the electrical performance of the collector, the results obtained show that the front side of the receiver produces more electricity throughout the day than the reflector side. This has guided Solarus AB to decide to change the design of its receiver to improve its performance. With the current design, it has been obtained a peak power at STC of 220W. In relation with the thermal part, the heat losses of the collector have been estimated obtaining a U value of 6,8W/(m2*K), a thermal optical beam efficiency of 63,5% and a total optical beam efficiency of 74,5%. The price market study of photovoltaic and thermal collector has shown that 2m2 of the Solarus AB hybrid PV/T collector produces approximately the same annual electricity and heat as 1,1m2 of a photovoltaic module with an efficiency of 15,5% and a flat plate collector of 0,85m2 of aperture area. According to the market study, its cost is equivalent to 190€ for the PV module and 220€ for the flat plate collector. This means that the price of the Solarus AB hybrid PV/T collector should be lower than 410€.
5
Dupeyrat, Patrick. "Experimental development and simulation investigation of a photovoltaic-thermal hybrid solar collector". Thesis, Lyon, INSA, 2011. http://www.theses.fr/2011ISAL0049.
Texto completoResumen
L´intérêt grandissant pour les bâtiments à haute efficacité énergétique nécessite le développement de nouveaux types d´enveloppe active et multifonctionnelle pouvant couvrir une partie des besoins énergétiques du bâtiment. Les travaux présentés dans cette thèse concernent le développement de capteurs hybrides solaires photovoltaïques thermique pour la production simultanée d´eau chaude sanitaire et d´électricité au sein d´un unique capteur. L’objectif de cette thèse a été dans un premier temps d´analyser la faisabilité et la complexité du concept de capteur hybrides PV-T. Puis, à partir d’un modèle numérique développé spécifiquement pour appuyer la phase de conception du capteur PV-T les raisons expliquant la limitation des performances de tels capteurs ont été analysées, pour enfin proposer différentes solutions innovantes, tant au niveau des cellules solaires que des matériaux du modules PV et du design du capteur final afin d´en augmenter les performances. L´approche développée est par conséquent multi-échelle allant de la prise en compte des phénomènes physiques pris isolément, des propriétés locales des matériaux jusqu’à la mise en œuvre d’un composant et à l´analyse énergétique et exergétique de ses performances dans un environnement numérique dédié au bâtimentIn the context of greenhouse gas emissions and fossil and fissile resources depletion, solar energy is one of the most promising sources of power. The building sector is one of the biggest energy consumers after the transport and industrial sectors. Therefore, making use of a building’s envelope (façades and roofs) as solar collecting surfaces is a big challenge facing local building needs, specifically in regard to heat, electricity and cooling. However, available surfaces of a building with suitable orientation are always limited, and in many cases a conflict occurs between their use for either heat or electricity production. This is one of the reasons why the concept of a hybrid photovoltaic-thermal (PV-T) collector seems promising. PV-T collectors are multi-energy components that convert solar energy into both electricity and heat. In fact, PV-T collectors make possible the use of the large amount of solar radiation wasted in PV modules as usable heat in a conventional thermal system. Therefore, PV-T collectors represent in principle one of the most efficient ways to use solar energy (co-generation effect). However, such a concept still faces various barriers due to the multidisciplinary knowledge requirements (material, semi-conductors, thermal) and to the complexity of the multiple physical phenomena implied in such concepts.The objective of this PhD work is to carry out a study based on a multi-scale approach that combines both numerical and experimental investigations regarding the feasibility of the concept of hybrid solar collector. The performance of such components is estimated through an appropriate design analysis, and innovative solutions to design an efficient PV-T collector are presented. Based on improved processing methods and improved material properties, an efficient covered PV-T collector has been designed and tested. This collector was made of PV cells connected to the surface of an optimized flat heat exchanger by an improved lamination process and covered on the front side by a static air layer and AR-coated glass pane and on the back side by thermal insulation material. The results showed a significant improvement of both thermal and electrical efficiency in comparison to all previous works on PV-T concepts found in the literature. System simulations were carried out for a hot water system with the software TRNSYS in order to get a clearer statement on the performance of PV-T collectors. The results show that the integration of PV-T collectors can be more advantageous than standard solar components in regard to thermodynamic considerations (energy and exergy) and environmental considerations (CO2 and primary energy saving)
6
Williams, Kristen. "Solar integration : applying hybrid photovoltaic/thermal systems". Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3744.
Texto completo
7
Gkatzioura, Anna. "A hybrid approach for item collection recommendations : an application to automatic playlist continuation". Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/664040.
Texto completoResumen
Current recommender systems aim mainly to generate accurate item recommendations, without properly evaluating the multiple dimensions of the recommendation problem. However, in many domains, like in music, where items are rarely consumed in isolation, users would rather need a set of items, designed to work well together, while having some cognitive properties as a whole, related to their perception of quality and satisfaction.
In this thesis, a hybrid case-based recommendation approach for item collections is proposed. In particular, an application to automatic playlist continuation, addressing similar cognitive concepts, rather than similar users, is presented. Playlists, that are sets of music items designed to be consumed as a sequence, with a specific purpose and within a specific context, are treated as cases. The proposed recommender system is based on a meta-level hybridization. First, Latent Dirichlet Allocation is applied to the set of past playlists, described as distributions over music styles, to identify their underlying concepts. Then, for a started playlist, its semantic characteristics, like its latent concept and the styles of the included items, are inferred, and Case-Based Reasoning is applied to the set of past playlists addressing the same concept, to construct and recommend a relevant playlist continuation. A graph-based item model is used to overcome the semantic gap between songs’ signal-based descriptions and users’ high-level preferences, efficiently capture the playlists’ structures and the similarity of the music items in those. As the proposed method bases its reasoning on previous playlists, it does not require the construction of complex user profiles to generate accurate recommendations. Furthermore, apart from relevance, support to parameters beyond accuracy, like increased coherence or support to diverse items is provided to deliver a more complete user experience.
Experiments on real music datasets have revealed improved results, compared to other state of the art techniques, while achieving a “good trade-off” between recommendations’ relevance, diversity and coherence. Finally, although actually focusing on playlist continuations, the designed approach could be easily adapted to serve other recommendation domains with similar characteristics.Los sistemas de recomendación actuales tienen como objetivo principal generar recomendaciones precisas de artículos, sin evaluar propiamente las múltiples dimensiones del problema de recomendación. Sin embargo, en dominios como la música, donde los artículos rara vez se consumen en forma aislada, los usuarios más bien necesitarían recibir recomendaciones de conjuntos de elementos, diseñados para que se complementaran bien juntos, mientras se cubran algunas propiedades cognitivas, relacionadas con su percepción de calidad y satisfacción. En esta tesis, se propone un sistema híbrido de recomendación meta-nivel, que genera recomendaciones de colecciones de artículos. En particular, el sistema se centra en la generación automática de continuaciones de listas de música, tratando conceptos cognitivos similares, en lugar de usuarios similares. Las listas de reproducción son conjuntos de elementos musicales diseñados para ser consumidos en secuencia, con un propósito específico y dentro de un contexto específico. El sistema propuesto primero aplica el método de Latent Dirichlet Allocation a las listas de reproducción, que se describen como distribuciones sobre estilos musicales, para identificar sus conceptos. Cuando se ha iniciado una nueva lista, se deducen sus características semánticas, como su concepto y los estilos de los elementos incluidos en ella. A continuación, el sistema aplica razonamiento basado en casos, utilizando las listas del mismo concepto, para construir y recomendar una continuación relevante. Se utiliza un grafo que modeliza las relaciones de los elementos, para superar el ?salto semántico? existente entre las descripciones de las canciones, normalmente basadas en características sonoras, y las preferencias de los usuarios, expresadas en características de alto nivel. También se utiliza para calcular la similitud de los elementos musicales y para capturar la estructura de las listas de dichos elementos. Como el método propuesto basa su razonamiento en las listas de reproducción y no en usuarios que las construyeron, no se requiere la construcción de perfiles de usuarios complejos para poder generar recomendaciones precisas. Aparte de la relevancia de las recomendaciones, el sistema tiene en cuenta parámetros más allá de la precisión, como mayor coherencia o soporte a la diversidad de los elementos para enriquecer la experiencia del usuario. Los experimentos realizados en bases de datos reales, han revelado mejores resultados, en comparación con las técnicas utilizadas normalmente. Al mismo tiempo, el algoritmo propuesto logra un "buen equilibrio" entre la relevancia, la diversidad y la coherencia de las recomendaciones generadas. Finalmente, aunque la metodología presentada se centra en la recomendación de continuaciones de listas de reproducción musical, el sistema se puede adaptar fácilmente a otros dominios con características similares.
8
Tyler, Laurence Gethyn. "A hybrid methodology for the experimental study of collective behaviour in robot groups". Thesis, De Montfort University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420853.
Texto completo
9
Dayananda, Karanam Ravichandran. "Zone Based Hybrid Approach for Clustering and Data Collection in Wireless Sensor Networks". Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/28738.
Texto completoResumen
A wireless sensor network (WSN) is a collection of spatially distributed autonomous sensor nodes that can be used to monitor, among other things, environmental conditions. WSN nodes are constrained by their limited energy supply, communication range and local computational capabilities. Data routing is an area that can be optimized to allow nodes to conserve energy, improving the network?s overall lifetime. Though many routing protocols can be used, using a clustering protocol can play an important role in conserving WSN energy. A new hybrid algorithm is proposed which incorporates both distributed and centralized algorithms for selection of the cluster head (CH). In most networks, sensor nodes have limited energy, so a mobile data collector (MDC) is used to collect information, reducing energy requirements. The performance of proposed algorithm is evaluated using NS-2 simulations. The results show that proposed algorithm has better performance, throughput, network lifetime compared to existing routing protocols.
10
Senthil, Kumar Nithin. "Designing optimized MPI+NCCL hybrid collective communication routines for dense many-GPU clusters". The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619132252608831.
Texto completo
11
Xu, Dongjiang. "HYBRID AND HIERARCHICAL IMAGE REGISTRATION TECHNIQUES". Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3232.
Texto completoResumen
A large number of image registration techniques have been developed for various types of sensors and applications, with the aim to improve the accuracy, computational complexity, generality, and robustness. They can be broadly classified into two categories: intensity-based and feature-based methods. The primary drawback of the intensity-based approaches is that it may fail unless the two images are misaligned by a moderate difference in scale, rotation, and translation. In addition, intensity-based methods lack the robustness in the presence of non-spatial distortions due to different imaging conditions between images. In this dissertation, the image registration is formulated as a two-stage hybrid approach combining both an initial matching and a final matching in a coarse-to-fine manner. In the proposed hybrid framework, the initial matching algorithm is applied at the coarsest scale of images, where the approximate transformation parameters could be first estimated. Subsequently, the robust gradient-based estimation algorithm is incorporated into the proposed hybrid approach using a multi-resolution scheme. Several novel and effective initial matching algorithms have been proposed for the first stage. The variations of the intensity characteristics between images may be large and non-uniform because of non-spatial distortions. Therefore, in order to effectively incorporate the gradient-based robust estimation into our proposed framework, one of the fundamental questions should be addressed: what is a good image representation to work with using gradient-based robust estimation under non-spatial distortions. With the initial matching algorithms applied at the highest level of decomposition, the proposed hybrid approach exhibits superior range of convergence. The gradient-based algorithms in the second stage yield a robust solution that precisely registers images with sub-pixel accuracy. A hierarchical iterative searching further enhances the convergence range and rate. The simulation results demonstrated that the proposed techniques provide significant benefits to the performance of image registration.Ph.D.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering
12
Drira, Wassim. "Secure collection and data management system for WSNs". Phd thesis, Institut National des Télécommunications, 2012. http://tel.archives-ouvertes.fr/tel-00814664.
Texto completoResumen
Nowadays, each user or organization is already connected to a large number of sensor nodes which generate a substantial amount of data, making their management not an obvious issue. In addition, these data can be confidential. For these reasons, developing a secure system managing the data from heterogeneous sensor nodes is a real need. In the first part, we developed a composite-based middleware for wireless sensor networks to communicate with the physical sensors for storing, processing, indexing, analyzing and generating alerts on those sensors data. Each composite is connected to a physical node or used to aggregate data from different composites. Each physical node communicating with the middleware is setup as a composite. The middleware has been used in the context of the European project Mobesens in order to manage data from a sensor network for monitoring water quality. In the second part of the thesis, we proposed a new hybrid authentication and key establishment scheme between senor nodes (SN), gateways (MN) and the middleware (SS). It is based on two protocols. The first protocol intent is the mutual authentication between SS and MN, on providing an asymmetric pair of keys for MN, and on establishing a pairwise key between them. The second protocol aims at authenticating them, and establishing a group key and pairwise keys between SN and the two others. The middleware has been generalized in the third part in order to provide a private space for multi-organization or -user to manage his sensors data using cloud computing. Next, we expanded the composite with gadgets to share securely sensor data in order to provide a secure social sensor network
13
Dresel, Eva. "Development and Characterization of a Light Diffuser for a Concentrating PV Collector". Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-9873.
Texto completoResumen
Hybrid solar systems as well as concentrating solar collectors are promising solar technologies. To run them efficiently in northern countries is a task Solarus AB is working on.The objective of this MSc project is to investigate and experimentally evaluate the option of implementing a light diffusing sheet in acompound parabolic concentrator (CPC) solar collector, called the “Scania Model”. This component should improve the non-uniform illumination of the photovoltaic cells in concentrating solar collectors.Therefore, scientific publications on this kind of solar collectors were read up on, e.g.Adsten, M. Brogren, M., Roos, A., Karlsson, B. Nilsson, J. and Leutz, R.After researching and procuring possible diffuser materials, experimental tests were carried out and the different materials were reviewed. Implemented in a solar simulator the IV curves of the collector with the different diffusers were generated. Furthermore, the influence of the materials on light was reviewed using daylight, laser light and an artificial light source. In the following, the light intensity distribution on the absorber of the Scania Model was defined and evaluated.The results of this project show that the main problem regarding diffuser material is to provide sufficient diffusion without much transmission losses.
14
Sung, Jin Won. "A NEW HYBRID DIFFRACTIVE PHOTO-MASK TECHNOLOGY". Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2391.
Texto completoResumen
In the field of photolithography for micro-chip manufacturing, the photo-mask is used to print desired patterns on a proper photo-resist on wafer. The most common type of photo-mask is binary amplitude mask made an opaque layer of chrome. The principle and potential application of hybrid photo-mask with diffractive phase element and binary amplitude is presented in this dissertation paper from both numerical modeling and experimental research. The first important application is the characterization of aberration in the stepper system using hybrid diffractive photo-mask. By utilizing multiple diffractive illumination conditions, it is possible to characterize Zernike wave front aberration coefficients up to any desired order. And, the second application is the use of binary phase grating mask for analog micro-optics fabrication. This approach of using binary phase grating mask for fabricating analog micro-optics turned out to be a very effective alternative for gray-scale mask technology. Since this is a pure phase only mask, it doesn't cause any scattered noise light like half-tone mask and it results in smooth desired resist profile. The benefits and limitations of hybrid diffractive photo-mask approach for both applications are discussed.Ph.D.
Other
Optics and Photonics
Optics
15
Futch, Linda. "A STUDY OF BLENDED LEARNING AT A METROPOLITAN RESEARCH UNIVERSITY". Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2456.
Texto completoResumen
The goal of this research was to better understand blended learning at the University of Central Florida (UCF). The investigator examined blended learning from the institutional, faculty, and student perspectives in an attempt to capture the complexities of this learning environment. For the institutional perspective, models emerged that were critical to the development of UCF's initiative and ongoing support of both fully online and blended courses. The individual faculty perspective outlined unique characteristics of one blended course, HFT4932 - Exploring Wines of the World. The professor explained his/her choices and reasons for an instructional model as well as why the blended format was selected. The student perspective indexed student attitudes toward blended classes at UCF. Students continued to report high overall satisfaction with blended courses as well as high levels of quality interaction among students and with faculty. However, there continued to be a downward trend in satisfaction levels with younger generations of students. Students still reported convenience and flexibility as their primary reasons for taking blended courses. Many students viewed the blended format as a way to become active participants in their learning thereby developing new learning skills. Infrequently, technology difficulties were reported. Challenges for students were time management and poor course organization. Web-based instructional delivery is still relatively new with a growing need for models that provide guidelines and strategies for instructors. The investigator suggests the possibility that this study serve as a model for a blended learning assessment for other institutions.Ed.D.
Department of Educational Research, Technology and Leadership
Education
Curriculum and Instruction
16
Barz, Hanns-Werner y Bernd Heide. "Collective Effects and Multifragmentation in Heavy Ion Collisions at Intermediate Energies within a Hybrid Model". Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-32176.
Texto completo
17
Barz, Hanns-Werner y Bernd Heide. "Collective Effects and Multifragmentation in Heavy Ion Collisions at Intermediate Energies within a Hybrid Model". Forschungszentrum Rossendorf, 1995. https://hzdr.qucosa.de/id/qucosa%3A22045.
Texto completo
18
Szy, Paula. "Back to the Roots : How Traditional Justice Processes Heal Collective Trauma after Conflict". Thesis, Uppsala universitet, Institutionen för freds- och konfliktforskning, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-354644.
Texto completoResumen
In recent times traditional justice processes have become increasingly adapted to serve as transitional justice tools in post-conflict societies. The healing potential of traditional justice is becoming more recognized, nevertheless there is still little known about its impact on collective trauma and especially about the causal mechanisms behind it. To contribute to this research field, this study is guided by the following research question: Why do some traditional justice processes generate the healing of collective trauma after conflict more than others?The developed theoretical framework argues that bottom-up, locally-led traditional justice processes foster voluntary community engagement which enhances collective trauma healing. Top-down, institutionalized processes, on the other hand, are theorized to produce involuntary contact which leads to lower levels of collective healing. It is thus hypothesized that locally-led traditional justice processes are more likely to generate healing of collective trauma than institutionalized traditional justice processes. An in-depth comparative case study which uses Structured Focused Comparison, analyzes the Rwandan Gacaca trials and the traditional justice processes in Acholiland. The empirical findings lend support to the hypothesis and provide modest support to the proposed causal mechanism.
19
Saizar, Zubeldia Xabier y Montagut Gerard Vila. "Analysis of the Solarus C-PVT solar collector and design of a new prototype : Market review and Production process guideline". Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-21679.
Texto completoResumen
Finding cleaner and sustainable energy resources is one of the most important concerns for the development of humanity. Solar energy is taking an essential role in this matter as the production cost of solar collectors is decreasing and more solar installations are being set up every year throughout the world. One way of reducing the cost of solar panels is by using concentrators that are cheaper than the costly photovoltaic cells and can increase their output. Solarus AB designed a Photovoltaic Thermal (PVT) hybrid collector that uses this principle and which is a variation of the Maximum Reflector Collector (MaReCo) design and is a Compound Parabolic Collector (CPC). This thesis has two main objectives. The first one is to design variations of the actual Solarus’ design and some alternative MaReCo designs and pure parabola designs. These designs include new solar cell cuts which are based on 4 busbar solar cells. In this way a future in-depth analysis may be carried out by comparing different receiver designs and collector boxes. The second goal is to investigate the current electrical and thermal performance of the collectors from Solarus AB which are installed in the Hus 45 of HiG. The appropriate data of the installation has been obtained using simulations and specific software, and it has been analysed with Microsoft Excel®. Concerning the new designs of the receivers and boxes, everything has been prepared for the future construction of the prototypes. All the measurements and their adjustments have been taken into account to define the size of the components and the process of building has been set up. Moreover, some future work has been planned in order to move forward the project. Regarding the analysis of the HiG installation, both electrical and thermal performance have resulted to be significantly lower compared with their estimated simulation, being their real output around 60 % of the estimated one. In the thermal part, the losses in the pipeline result to be more than a third part of the produced heat. In the electrical part, the production varies a lot between different collectors due to some of them do not work properly, consequence of poor condition of the solar panels (broken cells, dirt, shading, etc.).
20
Soriano, Alfonso Francisco. "A study of hybrid powertrains and predictive algorithms applied to energy management in refuse-collecting vehicles". Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/308140.
Texto completoResumen
There is an increasing demand for vehicles with lower environmental impact and higher fuel efficiency. To meet these requirements, powertrain hybridization has been introduced in both academia and industry during recent years.
In this work we have carried out an in-depth analysis of the potential reduction in fuel consumption of refuse-collecting vehicles (RCV), based on different hybridization technologies. This study has been structured in four work packages: RCV energy model development, predictive algorithms aimed at energy management for RCV drive cycles, analysis of hybrid hydraulic powertrains for RCV and analysis of hybrid electric powertrains for RCV.
RCV energy model development: the process of simulation starts with the RCV energy model development, which is based on the improvement of the classic approach (breaking down the energy consumption into aerodynamics, rolling resistance, road profile and inertias), and adding the RCV ancillaries¿ (lifter, compactor and unloading devices) consumption. The adjustments and validation methodology applied to the models is based on the use of low-cost hardware and post-processing data by use of GPS and cartography. Working with this method it has been empirically demonstrated that high accuracy energy consumption estimations are possible through the use of these models.
Predictive algorithms aimed at energy management for RCV drive cycles: based on the principle that RCV drive cycles are repetitive, the typical RCV drive cycle has been modeled and its main characteristics parameterized. The model is separated into different drive cycles which are related to different power consumption modes. Based on this analysis two algorithms are presented, which can identify in which drive mode the vehicle is operating; these algorithms are based on deterministic principles and on artificial intelligence respectively. Also, an algorithm which can estimate the energy needed to finish the current trip is presented; this algorithm is based on information inferred from previous trips, statistics and infinitesimal calculus.
Once the drive cycle of an RCV is analyzed and modeled, the working modes of a standard internal combustion engine on real drive cycles are presented and contrasted with fuel consumption maps. This study concludes that, because of the typical drive cycles of RCV, an ICE is oversized most of the time and tends to work in low efficiency points. Based on this information a basic alternative powertrain architecture is proposed
Analysis of hybrid hydraulic powertrain for RCV: hybrid hydraulic powertrains are often used in heavy duty vehicles in which big power flows can be found. As RCV represent an application with big power flows, the performance of this technology applied to RCV has been analyzed. This study is based on the development of models for each of the components of the powertrain, and the simulation of the whole powertrain model on real routes. All the component models are based on information provided by the manufacturers, and the routes have been logged in real RCV drive cycles. The conclusion is that an important fuel saving can be achieved by the hydraulic hybridization of the powertrain.
Analysis of hybrid electric powertrain for RCV: hybrid electric powertrains are often used in cars and light duty vehicles. As RCV represents a light to medium duty application the performance of this technology applied to RCV has been analyzed. As in the hybrid hydraulic case, this study is based on the development of models for each of the powertrain components, and the simulation of the whole powertrain model on real routes.
Finally a comparison between the hybrid electric and the hybrid hydraulic is established, identifying the more efficient technology and the advantages and inconveniences of each. And establishing what would be, according to the author, the most interesting technological powertrain evolution in the mid and long term for this kind of vehicle.Existe una creciente demanda de vehículos con menor impacto ambiental y mayor eficiencia energética. Para alcanzar esos objetivos, la hibridación del powertrain se ha introducido a nivel industrial y académico durante los últimos años. En el presente trabajo se ha realizado un análisis de la potencial reducción de consumo de carburante en vehículos recolectores de residuos (RCV), basado en diferentes tecnologías de hibridación. El trabajo se ha estructurado en cuatro paquetes de trabajo: modelos energéticos de RCV, algoritmos predictivos aplicados a la gestión energética de RCV, análisis de powertrains híbridos hidráulicos y análisis de powertrains híbridos eléctricos. Desarrollo de modelos de RCV: el proceso de simulación empieza con el desarrollo de los modelos, que están basados en la descomposición clásica (aerodinámica, rodadura, perfil de carretera e inercias) añadiendo los elementos auxiliares (prensa de residuos y elevador de contenedores). El ajuste y la validación de los modelos se basan en el uso de hardware de bajo coste y el post-procesado de datos mediante GPS y cartografía. Trabajando con este método se ha demostrado empíricamente que se pueden hacer estimaciones precisas del consumo energético, mediante el uso de los modelos desarrollados. Algoritmos predictivos para la gestión energética de RCV: basándose en el principio de que los ciclos de conducción de los camiones de basura son repetitivos, el ciclo de conducción de los RCV ha sido modelizado y sus principales características parametrizadas. El ciclo se ha separado en diferentes sub-ciclos que corresponden con diferentes modos de consumo de potencia. Basándose en este análisis se desarrollan dos algoritmos que pueden identificar el modo de consumo de potencia; estos algoritmos están basados en principios deterministas y en inteligencia artificial. Se presenta también un algoritmo que permite estimar en tiempo real el consumo de energía restante hasta llegar al final de la ruta. Una vez el ciclo de conducción de un RCV es analizado y modelado, los puntos de trabajo de un motor de combustión interna se presentan y comparan con un mapa de iso-consumos del motor. Este estudio concluye, que debido a los ciclos de conducción de un RCV, el motor está sobredimensionado durante la mayor parte del ciclo y tiende a trabajar sobre zonas de baja eficiencia. Basándose en esta información se plantea una arquitectura de powertrain alternativo. Análisis de powertrain híbrido hidráulico: estos powertrains se usan habitualmente en maquinaria pesada en las cuales se dan grandes flujos de potencia. Dado que los RCV presentan grandes flujos de potencia, las prestaciones de esta tecnología aplicada a RCV se han evaluado. Éste estudio se basa en el desarrollo de modelos para cada uno de los componentes del powertrain, y la simulación del sistema completo sobre rutas reales. Cada uno de los modelos de los componentes se basan en información suministrada por los fabricantes, y las rutas empleadas para la simulación son rutas reales. La conclusión final es que este powertrain presenta un importante ahorro de carburante. Análisis de powertrain híbrido eléctrico: estos powertrains se usan habitualmente en turismos y vehículos de gama "light duty". Dado que el RCV representa una aplicación de "medium duty" a "light duty", las prestaciones de esta tecnología aplicada a RCV se han evaluado. Como en el caso hidráulico los modelos se basan en información suministrada por fabricantes de componentes. Finalmente se establece una comparación de los powertrains hidráulico y eléctrico, identificando la tecnología más eficiente y las ventajas e inconvenientes de cada una. Y se establece cual es, según el autor, la evolución tecnológica más interesante para estas tecnologías.
21
Moursli, Omar. "Scheduling the hybrid flowshop : branch and bounnd algorithms". Université catholique de Louvain, 1999. http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-11262003-101952/.
Texto completoResumen
This thesis studies Production Scheduling in a multistage hybrid flowshop facility. It first states the general Production Planning and Scheduling problem and highlights some drawbacks of classical solutions. A theoretical decomposition-based approach is introduced whose main issue is to overcome non-efficient capacity utilization. By using Branch and Bound methods, an in-depth analysis of the scheduling part of the system is then carried out throughout the study and development of upper and lower bounds as well as branching schemes. Already-existing and new heuristics are presented and compared on different shop floor configurations. Five different heuristic approaches are studied. By scheduling the HFS one stage at a time the first approach uses different stage sequencing orders. The second and third approaches are mainly list heuristics. The second approach uses ideas derived from the multistage classical flowshop with a single machine per stage, while the third approach uses classical dispatching priority rules. The fourth and fifth approaches, respectively, use random scheduling and local search techniques. Statistical analysis is carried out in order to compare the heuristics and to select the best of them for each shop configuration. Already-existing and new lower bounds on the single stage subproblem are also presented and compared. Three new lower bounds are developed: a dual heuristic based bound, a partially preemptive bound and a heuristic for the so-called subset bound. Some of these lower bounds use a network flow algorithm. A new version of the “Preflow Push” algorithm which runs faster than the original one is presented. The best lower bounds are selected based on numerical tests. Two branch and bound algorithms are presented, an improved version of the sequence enumeration method and a generalization of the so-called interval branching method, along with several bounding strategies. Based on the upper and lower bound studies, several branch and bound algorithms are presented and compared using numerical tests on different shop floor configurations. Eventually, an Object Model for Scheduling Algorithm Implementations (OMSAI), that has been used for the computer implementation of the developed algorithms, is presented.
22
Hassan, Mohamed. "INELASTIC DYNAMIC BEHAVIOR AND DESIGN OF HYBRID COUPLED WALL SYSTEMS". Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4437.
Texto completoResumen
A key consideration in seismic design of buildings is to ensure that the lateral load resisting system has an appropriate combination of strength, stiffness and energy dissipation capacity. Hybrid coupled wall systems, in which steel beams are used to couple two or more reinforced concrete shear walls in series, can be designed to have these attributes and therefore have the potential to deliver good performance under severe seismic loading. This research presents an investigation of the seismic behavior of this type of structural system. System response of 12- and 18-story high prototypes is studied using transient finite element analyses that accounts for the most important aspects of material nonlinear behavior including concrete cracking, tension stiffening, and compressive behavior for both confined and unconfined concrete as well as steel yielding. The developed finite element models are calibrated using more detailed models developed in previous research and are validated through numerous comparisons with test results of reinforced concrete walls and wall-beam subassemblages. Suites of transient inelastic analyses are conducted to investigate pertinent parameters including hazard level, earthquake record scaling, dynamic base shear magnification, interstory drift, shear distortion, coupling beam plastic rotation, and wall rotation. Different performance measures are proposed to judge and compare the behavior of the various systems. The analyses show that, in general, hybrid coupled walls are particularly well suited for use in regions of high seismic risk. The results of the dynamic analyses are used to judge the validity of and to refine a previously proposed design method based on the capacity design concept and the assumption of behavior dominated by the first vibration mode. The adequacy of design based on the pushover analysis procedure as promoted in FEMA-356 (2000) is also investigated using the dynamic analysis results. Substantial discrepancies between both methods are observed, especially in the case of the 18-story system. A critical assessment of dynamic base shear magnification is also conducted, and a new method for estimating its effects is suggested. The method is based on a modal combination procedure that accounts for presence of a plastic hinge at the wall base. Finally, the validity of limitations in FEMA-368 (2000) on building height, particularly for hybrid coupled wall systems, is discussed.Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil and Environmental Engineering
23
Platt, Kyle. "DESIGN AND FABRICATION OF A FULL-FEATURED LABSCALE HYBRID ROCKET ENGINE". Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2815.
Texto completoResumen
The design, development, integration and testing of a full-featured, Lab-Scale Hybrid Rocket Engine was not only envisioned to be the chosen method of putting student payloads into space, but to be an invaluable teaching resource. The subject of the present thesis is the analysis, design, development, integration and demonstration of a lab-scale hybrid rocket motor. The overarching goal of this project was to establish a working developmental lab model from which further research can be accomplished. The lab model was specifically designed to use a fuel source that could be studied in normal laboratory conditions. As such, the rocket engine was designed to use Hydroxyl Terminated Polybutadiene as the fuel and Liquid Nitrous Oxide as the oxidizer. Developing the rocket engine required the usage of several electronics modules and a software package. The custom-designed electronics modules were a Signal Conditioning & Data Amplification Interface and a Data Acquisition Network. The software package was coded in Visual Basic (VB). A MathCAD regression rate computer model was designed and written to geometrically constrain the engine design. Further, the computer model allowed for the "what-if" situations to be evaluated. Using ProPep, solutions to the Equilibrium Thermodynamics Equations for the fuel and oxidizer mixture were obtained. The resultants were used as initial input to the computer model for predicting the lab-scale rocket's Chamber Pressure, Chamber Temperature, Ratio of Specific Heats and Molecular Weight. Details on the model, the rocket hardware, and the successful test firing are provided.M.S.A.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Aerospace Engineering
24
Ibrahim, Idowu David. "Development of Smart Parabolic Trough Solar Collector for Water Heating and Hybrid Polymeric Composite Water Storage Tank". Electronic Thesis or Diss., université Paris-Saclay, 2020. http://www.theses.fr/2020UPASG049.
Texto completoResumen
Les sources d’énergies utilisées pour le chauffage de l’eau dans les bâtiments commerciaux et résidentielles sont multiples. Ces ressources sont essentiellement électriques dans les milieux urbains et utilisent le bois dans les milieux ruraux. Le pourcentage de l’énergie solaire utilisé reste assez faible. Les méthodes les utilisées pour produire l’eau chaude sont pour basés pour l’essentielle sur l’utilisation des résistances électrique ou des capteurs solaire plat. Le travail présenté dans cette thèse est basé sur l’utilisation des concentrateurs solaires pour chauffer des collecteurs d’énergie. Le rendement est augmenté par le développement de nouveau matériaux pour le stockage.La structure pour le support du collecteur a été conçue et analysée utilisant le logiciel Solidworks®. Les forces agissant sur les éléments de la structure sont simulées pour assurer la fiabilité du support lors des différentes conditions de fonctionnement. L’analyse par la méthode des éléments finis a permis la vérification de la structure utilisée pour le réflecteur et son support.Les performances énergétiques ont été simulées pour cinq ans d’opération utilisant le logiciel Matlab Simulink®. Cette simulation a été basée sur l’utilisation de trois données différentes. La première est une base de données météorologique de cinq ans en Afrique du Sud dans la Ville de Tshwane. La deuxième est un profil d’utilisation pour un foyer type. La troisième est le coût de complément de chauffage en électricité dépendant de l’heure de l’utilisation. Cette simulation a permis la validation des choix de dimensions de différents éléments du système de chauffage.Cette étude a permis le développement d’une approche pour la conception d’un système de chauffage solaire en optimisant les dimensions des différents éléments pour un foyer type et une région spécifique.De plus, nous avons conçu un autre réservoir d’eau chaude. Nous avons démontré que l'utilisation de matériaux polymères et d'autres matériaux comme le polyuréthane, le sel et l'aluminium est possible pour le développement d'un réservoir de stockage d'eau chaude en fonction de leurs propriétés inhérentes.L'extension des résultats de cette thèse améliorera encore les conceptions des technologies de concentrateurs solaires et des systèmes de chauffage solaire de l'eau. Par conséquent, certaines recommandations et suggestions sont mises en évidence afin d'améliorer la conception, l'analyse et les performances globales du systèmeIn recent years, various energy sources and methods have been used to heat water in domestic and commercial buildings. The known sources for water heating include electrical energy and solar radiation energy in the urban regions or burning of firewood in the rural areas. Several water heating methods may be used such as electrical heating elements, solar concentrators, flat plate collectors and evacuated tube collectors. This thesis focuses on ways to further improve the system’s performance for water heating through the combined use of solar energy and solar concentrator technique. Furthermore, the study proposed an alternative design method for the hot water storage tank.The solar collector-supporting frame was designed and analysed using Solidworks®. The forces acting on the structural members were simulated to determine the capacity of the frame to sustain the load, and the possible regions on the supporting frame, which could potentially fail while in operation.Energy performance was simulated for five years of operation using Matlab Simulink® software. This simulation was based on the use of three different data. The first is a five-year weather database of the City of Tshwane in South Africa. The second is a hot water consumption profile for a typical household. The third is the cost of additional heating with electricity depending on the time of use. This simulation allowed the validation of the choices of the different elements of the heating system.This study allowed the development of an approach for the design of a solar heating system by optimising the dimensions of the different elements for a typical household and a specific region.In addition, the use of polymeric materials and other materials like polyurethane, salt and aluminium is possible for the development of a hot water storage tank based on their inherent properties.Extending the findings in this thesis will further improve the designs for solar concentrator technologies and solar water heating systems. Therefore, some recommendations and suggestions are highlighted in order to improve the overall system design, analysis and performance
25
Pepper, Michael. "BI-DIRECTIONAL DCM DC-TO-DC CONVERTER FOR HYBRID ELECTRIC VEHICLES". Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2672.
Texto completoResumen
With the recent revival of the hybrid vehicle much advancement in power management has been made. The most popular hybrid vehicle, the hybrid electric vehicle, has many topologies developed to realize this hybrid vehicle. From these topologies, as sub set was created to define a particular group of vehicles where the converter discussed in this thesis has the most advantage. This sub set is defined by two electric sources of power coupled together at a common bus. This set up presents many unique operating conditions which can be handled seamlessly by the DC-to-DC converter when designed properly. The DC-to-DC converter discussed in this thesis is operated in Discontinuous Conduction Mode (DCM) of operation because of its unique advantages over the Continuous Conduction Mode (CCM) operated converter. The most relevant being the reduction of size of the magnetic components such as inductor, capacitor and transformers. However, the DC-to-DC converter operated in DCM does not have the inherent capability of bi-directional power flow. This problem can be overcome with a unique digital control technique developed here. The control is developed in a hierarchical fashion to separate the functions required for this sub set of hybrid electric vehicle topologies. This layered approach for the controller allows for the seamless integration of this converter into the vehicle. The first and lowest level of control includes a group of voltage and controller regulators. The average and small signal model of these controllers were developed here to be stable and have a relatively fast recovery time to handle the transient dynamics of the vehicle system. The second level of control commands and organizes the regulators from the first level of control to perform high level task that is more specific to the operation of the vehicle. This level of control is divided into three modes called hybrid boost, hybrid buck and electric vehicle mode. These modes are developed to handle the specific operating conditions found when the vehicle is operated in the specific mode. The third level of control is used to command the second level of control and is left opened via a communication area network (CAN) bus controller. This level of control is intended to come from the vehicle s system controller. Because the DC-to-DC converter is operated in DCM, this introduces added voltage ripple on the output voltage as well as higher current ripple demand from the input voltage. Since this is generally undesirable, the converter is split into three phases and properly interleaved. The interleaving operation is used to counteract the effects of the added voltage and current ripple. Finally, a level of protection is added to protect the converter and surrounding components from harm. All protection is designed and implemented digitally in DSP.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
26
Stewart, Calvin. "A Hybrid Constitutive Model For Creep, Fatigue, And Creep-Fatigue Damage". Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6023.
Texto completoResumen
In the combustion zone of industrial- and aero- gas turbines, thermomechanical fatigue (TMF) is the dominant damage mechanism. Thermomechanical fatigue is a coupling of independent creep, fatigue, and oxidation damage mechanisms that interact and accelerate microstructural degradation. A mixture of intergranular cracking due to creep, transgranular cracking due to fatigue, and surface embrittlement due to oxidation is often observed in gas turbine components removed from service. The current maintenance scheme for gas turbines is to remove components from service when any criteria (elongation, stress-rupture, crack length, etc.) exceed the designed maximum allowable. Experimental, theoretical, and numerical analyses are performed to determine the state of the component as it relates to each criterion (a time consuming process). While calculating these metrics individually has been successful in the past, a better approach would be to develop a unified mechanical modeling that incorporates the constitutive response, microstructural degradation, and rupture of the subject material via a damage variable used to predict the cumulative “damage state” within a component. This would allow for a priori predictions of microstructural degradation, crack propagation/arrest, and component-level lifing. In this study, a unified mechanical model for creep-fatigue (deformation, cracking, and rupture) is proposed. It is hypothesized that damage quantification techniques can be used to develop accurate creep, fatigue, and plastic/ductile cumulative- nonlinear- damage laws within the continuum damage mechanics principle. These damage laws when coupled with appropriate constitutive equations and a degrading stiffness tensor can be used to predict the mechanical state of a component. A series of monotonic, creep, fatigue, and tensile-hold creep-fatigue tests are obtained from literature for 304 stainless steel at 600°C (1112°F) in an air. Cumulative- nonlinear- creep, fatigue, and a coupled creep-fatigue damage laws are developed. The individual damage variables are incorporated as an internal state variable within a novel unified viscoplasticity constitutive model (zero yield surface) and degrading stiffness tensor. These equations are implemented as a custom material model within a custom FORTRAN one-dimensional finite element code. The radial return mapping technique is used with the updated stress vector solved by Newton-Raphson iteration. A consistent tangent stiffness matrix is derived based on the inelastic strain increment. All available experimental data is compared to finite element results to determine the ability of the unified mechanical model to predict deformation, damage evolution, crack growth, and rupture under a creep-fatigue environment.Ph.D.
Doctorate
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering
27
Pastrana, John. "Model-Based Systems Engineering Approach to Distributed and Hybrid Simulation Systems". Doctoral diss., University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6336.
Texto completoResumen
INCOSE defines Model-Based Systems Engineering (MBSE) as "the formalized application of modeling to support system requirements, design, analysis, verification, and validation activities beginning in the conceptual design phase and continuing throughout development and later life cycle phases." One very important development is the utilization of MBSE to develop distributed and hybrid (discrete-continuous) simulation modeling systems. MBSE can help to describe the systems to be modeled and help make the right decisions and partitions to tame complexity.
The ability to embrace conceptual modeling and interoperability techniques during systems specification and design presents a great advantage in distributed and hybrid simulation systems development efforts. Our research is aimed at the definition of a methodological framework that uses MBSE languages, methods and tools for the development of these simulation systems. A model-based composition approach is defined at the initial steps to identify distributed systems interoperability requirements and hybrid simulation systems characteristics. Guidelines are developed to adopt simulation interoperability standards and conceptual modeling techniques using MBSE methods and tools. Domain specific system complexity and behavior can be captured with model-based approaches during the system architecture and functional design requirements definition. MBSE can allow simulation engineers to formally model different aspects of a problem ranging from architectures to corresponding behavioral analysis, to functional decompositions and user requirements (Jobe, 2008).Ph.D.
Doctorate
Industrial Engineering and Management Systems
Engineering and Computer Science
Industrial Engineering
28
Schön, Gustav. "NUMERICAL MODELLING OF A NOVEL PVT COLLECTOR AT CELL RESOLUTION". Thesis, KTH, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-212731.
Texto completoResumen
Solar photovoltaic-thermal (PVT) modules produce heat and power via a heat exchanger attached to the rear of the PV cells. The novel PVT collector in this study is previously untested and therefore its behaviour and thermo-electric performance due to fluid channel configuration and in various climate and operating conditions are unknown. Moreover, the working fluid flowing through the heat exchanger cause a temperature gradient across the module such that a cell near the inlet and a cell near the outlet may have significant temperature differences. PV cells are sensitive to temperature; however the most common way to simulate power output from a PVT is to use the average temperature and ignore the gradient. In this study, a single diode PV model is incorporated into a commercial thermal solver to co-simulate the thermal and electrical output of a novel PVT module design with cell level resolution. The PVT system is modelled in steady state under various wind speeds, inlet temperatures, ambient temperatures, flow rates, irradiation, convection coefficients from coolant and back of the module and two different fluid channel configurations. The results show that of the controllable variables, the inlet temperature has the highest influence of the total power output and that a parallel flow of the fluid channel configuration is preferable. The difference between the cell resolution and the module resolution simulations do not motivate the use of a higher resolution numerical simulation.En kombinerad solcellspanel och solvärmefångare (PVT) producerar värme och elenergi på samma yta genom att en värmeväxlare upptar värmen från baksidan av solcellspanelen. Den PVT som berörs i denna studien är nyutvecklad och har aldrig tidigare testats, vilket medför att data för hur den beter sig samt dess termo-elektiska prestanda saknas för olika driftförhållanden samt flödeskonfigurationer. Vidare ger mediet som flödar genom värmeväxlaren upphov till en temperaturgradient, vilken kan innebära en påtaglig skillnad i temperatur mellan solcellerna i solcellspanelen vid mediets in- respektive utlopp. Trots solcellers temperaturkänslighet, så sker simulering i allmänhet med avseende på panelens medeltemperatur istället för att hänsyn tas till denna temperaturgradient. I den här studien implementeras en så kallad ”single diode”-modell i en kommersiell numerisk mjukvara termiska beräkningar för att samsimulera termiskt och elektriskt effektuttag ur den nyutvecklade PVT-designen. Designen modelleras statiskt under givna variationer av vindhastighet, inloppstemperatur, omgivande temperatur, flödeshastighet, solinstrålning och konvektionskoefficienter för mediet samt baksidan av modulen. Resultaten visar att kontrollerbara variabler som inloppstemperatur har högst inverkan på den totala effekten samt att en parallell flödeskonfiguration lämpar sig bäst. Studien visar också att skillnaden mellan simulering på cellnivå och modulnivå inte motiverar en numerisk beräkningsmetod med upplösning satt till solcellsnivå.
29
Kang, Bei. "STATISTICAL CONTROL USING NEURAL NETWORK METHODS WITH HIERARCHICAL HYBRID SYSTEMS". Diss., Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/122303.
Texto completoResumen
Electrical EngineeringPh.D.
The goal of an optimal control algorithm is to improve the performance of a system. For a stochastic system, a typical optimal control method minimizes the mean (first cumulant) of the cost function. However, there are other statistical properties of the cost function, such as variance (second cumulant) and skewness (third cumulant), which will affect the system performance. In this dissertation, the work on the statistical optimal control are presented, which extends the traditional optimal control method using cost cumulants to shape the system performance. Statistical optimal control will allow more design freedom to achieve better performance. The solutions of statistical control involve solving partial differential equations known as Hamilton-Jacobi-Bellman equation. A numerical method based on neural networks is employed to find the solutions of the Hamilton-Jacobi-Bellman partial differential equation. Furthermore, a complex problem such as multiple satellite control, has both continuous and discrete dynamics. Thus, a hierarchical hybrid architecture is developed in this dissertation where the discrete event system is applied to discrete dynamics, and the statistical control is applied to continuous dynamics. Then, the application of a multiple satellite navigation system is analyzed using the hierarchical hybrid architecture. Through this dissertation, it is shown that statistical control theory is a flexible optimal control method which improves the performance; and hierarchical hybrid architecture allows control and navigation of a complex system which contains continuous and discrete dynamics.
Temple University--Theses
30
Andrianarison, Maherizo. "New Methods and Architectures for High Sensitivity Hybrid GNSS Receivers in Challenging Environments". Thesis, Toulouse, ISAE, 2018. http://www.theses.fr/2018ESAE0016/document.
Texto completoResumen
Les systèmes de navigation par satellites GNSS ne cessent d’évoluer et ils sont déjà utilisés dans de nombreuses applications. Avec la venue des nouveaux systèmes Galileo et BeiDou ainsi que la modernisation des systèmes GPS et GLONASS, de nouveaux satellites ainsi que de nombreuses nouvelles fréquences et de nouveaux signaux feront leur apparition dans les prochaines années et qui vont encore ouvrir la porte à d’innombrables nouvelles applications. L’évolution rapide de la téléphonie mobile nécessite une meilleure exploitation des systèmes de navigation et de positionnement dans les environnements urbains.Jusqu'à maintenant, les signaux de navigation GPS ne peuvent pas être bien captés dans les environnements urbains. Les niveaux des signaux y sont très faibles et il est presque impossible d’acquérir et de poursuivre les signaux de façon autonome à cause de l'importance des obstacles. De plus, le positionnement à l’intérieur et dans les environnements urbains sont aussi soumis aux problèmes de multi-trajets, de masquage, d’interférences et de brouillages. Dans ces conditions, il faut pouvoir traiter des signaux très dégradés ou très courts qui ne permettent pas au récepteur d’effectuer le processus de poursuite. Ainsi, cela nous conduit à la nécessité de repenser l'architecture du récepteur GNSS pour les applications modernes.Ce projet de thèse consiste à développer de nouvelles méthodes et architectures de récepteur GNSS de haute sensibilité et robuste aux dégradations des signaux tout en concevant de nouveaux algorithmes intégrés dans un récepteur GNSS hybride capable de fonctionner dans les environnements urbains profonds ou « intérieurs ».La méthodologie prévoit l’utilisation de la nouvelle approche de « détection collective (CD) » ou « acquisition collaborative ». L'approche collaborative qui traite tous les signaux multi-satellites ouvre une solution intéressante. De nombreuses techniques existent dans la littérature pour résoudre les problèmes de positionnement dans les environnements urbains, mais nous proposons la nouvelle approche de détection collective en raison de sa performance en tant que méthode de positionnement direct et méthode d'acquisition de haute sensibilité, par l'application de la détection vectorielle de tous les satellites visibles. En effet, la bonne combinaison des valeurs de corrélation de plusieurs satellites peut réduire le niveau de C/N0 requis des signaux satellites par les algorithmes standards de traitement (acquisition et poursuite) qui ne peuvent pas être acquis individuellement mais permettent de contribuer de manière constructive à une solution collective de positionnement pour chaque utilisateur. L’objectif est de détecter collaborativement les satellites. La combinaison de différents signaux GNSS peut considérablement augmenter la sensibilité d'acquisition du récepteur. Malgré les avantages de cette approche, elle présente également des inconvénients tels que la charge de calcul élevée en raison du grand nombre de points candidats dans le domaine position/biais d’horloge. Ainsi, le travail proposé dans cette thèse consiste à réduire la complexité du CD en optimisant la recherche de points candidats dans le domaine position/biais d’horloge. Enfin, l'objectif est d'appliquer l'approche de détection collective au positionnement GNSS coopératif pour la navigation moderne dans des environnements difficiles. Pour cela, des algorithmes d'exploitation optimale des ressources du récepteur en sélectionnant les meilleurs satellites ou la station de référence seront développés selon certains critères tels que le niveau du rapport signal sur bruit (C/N_0), l’angle d’élévation des satellites ainsi que la configuration géométrique des satellites visibles. L’objectif final est de proposer une nouvelle architecture de récepteur cognitif de haute sensibilité permettant de recevoir de façon optimale les nouveaux signaux GNSSGNSS satellite navigation systems are constantly evolving and have been already used in many applications. With the advent of the new systems Galileo and BeiDou as well as the modernization of GPS and GLONASS systems, new satellites and numerous new frequencies and signals will appear in the coming years and will open door to countless new applications that are currently impossible. The rapid evolution of mobile telephony and personal navigation devices (PND) requires better use of navigation systems in non-ideal environments, especially the need for positioning in deep urban area. On the one hand, users are waiting for a high positioning accuracy, because of the proximity to various points of interest. On the other hand, urban environment brings specific difficulties in receiving GNSS signals.GNSS navigation signals cannot be properly captured in urban and "indoor" environments. Signal levels are very low and it is almost impossible to acquire and track signals autonomously because of the strong attenuation of signals due to obstacles. In addition, indoor and urban positioning are also subject to multipath problems, masking, interference and jamming. Under these conditions, we must be able to process highly degraded or very short signals that do not allow the receiver to go through the tracking process. Thus, this leads us to the need to rethink the architecture of GNSS receiver for modern applications.This thesis project consists of developing new GNSS methods and architectures of high sensitivity and robustness to signal degradations and designing new algorithms integrated into a hybrid GNSS receiver capable of operating in deep urban environments.The methodology involves the use of the new concept of “Collective Detection (CD)”, also called “collaborative acquisition”. The collaborative approach that treats multi-satellite signals all together opens an interesting solution. Many techniques exist in the literature to solve the problems of positioning in urban environments, but we propose the new Collective Detection approach because of its performance as both a Direct Positioning method, providing a coarse position/clock-bias solution directly from acquisition, and High-Sensitivity acquisition method, by application of vector detection of all satellites in view. Indeed, the correct combination of the correlation values of several satellites can reduce the required Carrier-to-Noise Ratio (C/N_0) level of the satellite signals which cannot be acquired individually by standard signal processing (acquisition and tracking) but make it possible to use them constructively to a positioning solution. The combination of different GNSS signals can considerably increase the acquisition sensitivity of the receiver. Despite the advantages of this approach, it also has drawbacks such as the high computational burden because of the large number of candidate points in the position/clock-bias domain. Thus, the work proposed in this thesis consists of reducing the complexity of the CD by optimizing the search for candidate points in position/clock-bias domain. Finally, the goal is to apply the CD approach to Cooperative GNSS Positioning for modern navigation in harsh environments. For that, algorithms for optimally exploiting receiver resources by selecting the best satellites or the reference station will be developed according to certain criteria such as the C/N_0 level, the elevation angle, and the geometric configuration of the visible satellites. The ultimate goal is to propose a design of a new smart receiver “High Sensitivity Cognitive GNSS Receiver (HS-CGR)” to optimally receive and process GNSS signals
31
Quijada, Sergio. "A HYBRID SIMULATION METHODOLOGY TO EVALUATE NETWORK CENTRICDECISION MAKING UNDER EXTREME EVENTS". Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2348.
Texto completoResumen
Currently the network centric operation and network centric warfare have generated a new area of research focused on determining how hierarchical organizations composed by human beings and machines make decisions over collaborative environments. One of the most stressful scenarios for these kinds of organizations is the so-called extreme events. This dissertation provides a hybrid simulation methodology based on classical simulation paradigms combined with social network analysis for evaluating and improving the organizational structures and procedures, mainly the incident command systems and plans for facing those extreme events. According to this, we provide a methodology for generating hypotheses and afterwards testing organizational procedures either in real training systems or simulation models with validated data. As long as the organization changes their dyadic relationships dynamically over time, we propose to capture the longitudinal digraph in time and analyze it by means of its adjacency matrix. Thus, by using an object oriented approach, three domains are proposed for better understanding the performance and the surrounding environment of an emergency management organization. System dynamics is used for modeling the critical infrastructure linked to the warning alerts of a given organization at federal, state and local levels. Discrete simulations based on the defined concept of "community of state" enables us to control the complete model. Discrete event simulation allows us to create entities that represent the data and resource flows within the organization. We propose that cognitive models might well be suited in our methodology. For instance, we show how the team performance decays in time, according to the Yerkes-Dodson curve, affecting the measures of performance of the whole organizational system. Accordingly we suggest that the hybrid model could be applied to other types of organizations, such as military peacekeeping operations and joint task forces. Along with providing insight about organizations, the methodology supports the analysis of the "after action review" (AAR), based on collection of data obtained from the command and control systems or the so-called training scenarios. Furthermore, a rich set of mathematical measures arises from the hybrid models such as triad census, dyad census, eigenvalues, utilization, feedback loops, etc., which provides a strong foundation for studying an emergency management organization. Future research will be necessary for analyzing real data and validating the proposed methodology.Ph.D.
Other
Engineering and Computer Science
Modeling and Simulation
32
Helal, Magdy. "A HYBRID SYSTEM DYNAMICS-DISCRETE EVENT SIMULATIONAPPROACH TO SIMULATING THE MANUFACTURING ENTERPRISE". Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2349.
Texto completoResumen
With the advances in the information and computing technologies, the ways the manufacturing enterprise systems are being managed are changing. More integration and adoption of the system perspective push further towards a more flattened enterprise. This, in addition to the varying levels of aggregation and details and the presence of the continuous and discrete types of behavior, created serious challenges for the use of the existing simulation tools for simulating the modern manufacturing enterprise system. The commonly used discrete event simulation (DES) techniques face difficulties in modeling such integrated systems due to increased model complexity, the lack of data at the aggregate management levels, and the unsuitability of DES to model the financial sectors of the enterprise. System dynamics (SD) has been effective in providing the needs of top management levels but unsuccessful in offering the needed granularity at the detailed operational levels of the manufacturing system. On the other hand the existing hybrid continuous-discrete tools are based on certain assumptions that do not fit the requirements of the common decision making situations in the business systems. This research has identified a need for new simulation modeling approaches that responds to the changing business environments towards more integration and flattened enterprise systems. These tools should be able to develop comprehensive models that are inexpensive, scalable, and able to accommodate the continuous and discrete modes of behavior, the stochastic and deterministic natures of the various business units, and the detail complexity and dynamic complexity perspectives in decision making. The research proposes and develops a framework to combine and synchronize the SD and DES simulation paradigms to simulate the manufacturing enterprise system. The new approach can respond to the identified requirements in simulating the modern manufacturing enterprise systems. It is directed toward building comprehensive simulation models that can accommodate all management levels while explicitly recognizing the differences between them in terms of scope and frequency of decision making as well as the levels of details preferred and used at each level. This SDDES framework maintains the integrity of the two simulation paradigms and can use existing/legacy simulation models without requiring learning new simulation or computer programming skills. The new framework uses a modular structure by which the SD and DES models are treated as members of a comprehensive simulation. A new synchronization mechanism that that maintains the integrity of the two simulation paradigms and is not event-driven is utilized to coordinate the interactions between the simulation modules. It avoids having one simulation paradigm dominating the other. For communication and model management purposes the SDDES formalism provides a generic format to describe, specify, and document the simulation modules and the information sharing processes. The SDDES controller which is the communication manager, implements the synchronization mechanism and manages the simulation run ensuring correct exchange of data in terms of timeliness and format, between the modules. It also offers the user interface through which users interact with the simulation modules.Ph.D.
Department of Industrial Engineering and Management Systems
Engineering and Computer Science
Industrial Engineering PhD
33
pande, anurag. "ESTIMATION OF HYBRID MODELS FOR REAL-TIME CRASH RISK ASSESSMENT ON FREEWAYS". Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3016.
Texto completoResumen
Relevance of reactive traffic management strategies such as freeway incident detection has been diminishing with advancements in mobile phone usage and video surveillance technology. On the other hand, capacity to collect, store, and analyze traffic data from underground loop detectors has witnessed enormous growth in the recent past. These two facts together provide us with motivation as well as the means to shift the focus of freeway traffic management toward proactive strategies that would involve anticipating incidents such as crashes. The primary element of proactive traffic management strategy would be model(s) that can separate 'crash prone' conditions from 'normal' traffic conditions in real-time. The aim in this research is to establish relationship(s) between historical crashes of specific types and corresponding loop detector data, which may be used as the basis for classifying real-time traffic conditions into 'normal' or 'crash prone' in the future. In this regard traffic data in this study were also collected for cases which did not lead to crashes (non-crash cases) so that the problem may be set up as a binary classification. A thorough review of the literature suggested that existing real-time crash 'prediction' models (classification or otherwise) are generic in nature, i.e., a single model has been used to identify all crashes (such as rear-end, sideswipe, or angle), even though traffic conditions preceding crashes are known to differ by type of crash. Moreover, a generic model would yield no information about the collision most likely to occur. To be able to analyze different groups of crashes independently, a large database of crashes reported during the 5-year period from 1999 through 2003 on Interstate-4 corridor in Orlando were collected. The 36.25-mile instrumented corridor is equipped with 69 dual loop detector stations in each direction (eastbound and westbound) located approximately every ½ mile. These stations report speed, volume, and occupancy data every 30-seconds from the three through lanes of the corridor. Geometric design parameters for the freeway were also collected and collated with historical crash and corresponding loop detector data. The first group of crashes to be analyzed were the rear-end crashes, which account to about 51% of the total crashes. Based on preliminary explorations of average traffic speeds; rear-end crashes were grouped into two mutually exclusive groups. First, those occurring under extended congestion (referred to as regime 1 traffic conditions) and the other which occurred with relatively free-flow conditions (referred to as regime 2 traffic conditions) prevailing 5-10 minutes before the crash. Simple rules to separate these two groups of rear-end crashes were formulated based on the classification tree methodology. It was found that the first group of rear-end crashes can be attributed to parameters measurable through loop detectors such as the coefficient of variation in speed and average occupancy at stations in the vicinity of crash location. For the second group of rear-end crashes (referred to as regime 2) traffic parameters such as average speed and occupancy at stations downstream of the crash location were significant along with off-line factors such as the time of day and presence of an on-ramp in the downstream direction. It was found that regime 1 traffic conditions make up only about 6% of the traffic conditions on the freeway. Almost half of rear-end crashes occurred under regime 1 traffic regime even with such little exposure. This observation led to the conclusion that freeway locations operating under regime 1 traffic may be flagged for (rear-end) crashes without any further investigation. MLP (multilayer perceptron) and NRBF (normalized radial basis function) neural network architecture were explored to identify regime 2 rear-end crashes. The performance of individual neural network models was improved by hybridizing their outputs. Individual and hybrid PNN (probabilistic neural network) models were also explored along with matched case control logistic regression. The stepwise selection procedure yielded the matched logistic regression model indicating the difference between average speeds upstream and downstream as significant. Even though the model provided good interpretation, its classification accuracy over the validation dataset was far inferior to the hybrid MLP/NRBF and PNN models. Hybrid neural network models along with classification tree model (developed to identify the traffic regimes) were able to identify about 60% of the regime 2 rear-end crashes in addition to all regime 1 rear-end crashes with a reasonable number of positive decisions (warnings). It translates into identification of more than ¾ (77%) of all rear-end crashes. Classification models were then developed for the next most frequent type, i.e., lane change related crashes. Based on preliminary analysis, it was concluded that the location specific characteristics, such as presence of ramps, mile-post location, etc. were not significantly associated with these crashes. Average difference between occupancies of adjacent lanes and average speeds upstream and downstream of the crash location were found significant. The significant variables were then subjected as inputs to MLP and NRBF based classifiers. The best models in each category were hybridized by averaging their respective outputs. The hybrid model significantly improved on the crash identification achieved through individual models and 57% of the crashes in the validation dataset could be identified with 30% warnings. Although the hybrid models in this research were developed with corresponding data for rear-end and lane-change related crashes only, it was observed that about 60% of the historical single vehicle crashes (other than rollovers) could also be identified using these models. The majority of the identified single vehicle crashes, according to the crash reports, were caused due to evasive actions by the drivers in order to avoid another vehicle in front or in the other lane. Vehicle rollover crashes were found to be associated with speeding and curvature of the freeway section; the established relationship, however, was not sufficient to identify occurrence of these crashes in real-time. Based on the results from modeling procedure, a framework for parallel real-time application of these two sets of models (rear-end and lane-change) in the form of a system was proposed. To identify rear-end crashes, the data are first subjected to classification tree based rules to identify traffic regimes. If traffic patterns belong to regime 1, a rear-end crash warning is issued for the location. If the patterns are identified to be regime 2, then they are subjected to hybrid MLP/NRBF model employing traffic data from five surrounding traffic stations. If the model identifies the patterns as crash prone then the location may be flagged for rear-end crash, otherwise final check for a regime 2 rear-end crash is applied on the data through the hybrid PNN model. If data from five stations are not available due to intermittent loop failures, the system is provided with the flexibility to switch to models with more tolerant data requirements (i.e., model using traffic data from only one station or three stations). To assess the risk of a lane-change related crash, if all three lanes at the immediate upstream station are functioning, the hybrid of the two of the best individual neural network models (NRBF with three hidden neurons and MLP with four hidden neurons) is applied to the input data. A warning for a lane-change related crash may be issued based on its output. The proposed strategy is demonstrated over a complete day of loop data in a virtual real-time application. It was shown that the system of models may be used to continuously assess and update the risk for rear-end and lane-change related crashes. The system developed in this research should be perceived as the primary component of proactive traffic management strategy. Output of the system along with the knowledge of variables critically associated with specific types of crashes identified in this research can be used to formulate ways for avoiding impending crashes. However, specific crash prevention strategies e.g., variable speed limit and warnings to the commuters demand separate attention and should be addressed through thorough future research.Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering
34
Secretan, James. "A Hybrid of Neural Networks and Genetic Algorithms for Controlling Mobile Robots". Honors in the Major Thesis, University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/725.
Texto completoResumen
This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucfBachelors
Engineering and Computer Science
Computer Engineering
35
Ceballos, Andres. "A multiscale model of the neonatal circulatory system following Hybrid Norwood palliation". Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4866.
Texto completoResumen
A system of 32 first-order differential equations is formulated and solved for the LP model using a fourth-order adaptive Runge-Kutta solver. The output pressure and flow waveforms obtained from the LP model are imposed as boundary conditions on the CFD model. Coupling of the two models is done through an iterative process where the parameters in the LP model are adjusted to match the CFD solution. The CFD model domain is a representative HLHS anatomy of an infant after undergoing the Hybrid Norwood procedure and is comprised of the neo-aorta, pulmonary roots, aortic arch with branching arteries, and pulmonary arteries. The flow field is solved over several cardiac cycles using an implicit-unsteady RANS equation solver with the k-epsilon turbulence model.; Hypoplastic left heart syndrome (HLHS) is a complex cardiac malformation in neonates suffering from congenital heart disease and occurs in nearly 1 per 5000 births. HLHS is uniformly fatal within the first hours or days after birth as the severely malformed anatomies of the left ventricle, mitral and aortic valves, and ascending aorta are not compatible with life. The regularly implemented treatment, the Norwood operation, is a complex open heart procedure that attempts to establish univentricular circulation by removing the atrial septum (communicating the right and left ventricle), reconstructing the malformed aortic arch, and connecting the main pulmonary artery into the reconstructed arch to allow direct perfusion from the right ventricle into the systemic circulation. A relatively new treatment being utilized, the Hybrid Norwood procedure, involves a less invasive strategy to establish univentricular circulation that avoids a cardiopulmonary bypass (heart-lung machine), deliberate cardiac arrest, and circulatory arrest of the patient during the procedure. The resulting systemic-pulmonary circulation is unconventional; blood is pumped simultaneously and in parallel to the systemic and pulmonary arteries after the procedure. Cardiac surgeons are deeply interested in understanding the global and local hemodynamics of this anatomical configuration. To this end, a multiscale model of the entire circulatory system was developed utilizing an electrical lumped parameter model for the peripheral or distal circulation coupled with a 3D Computational Fluid Dynamics (CFD) model to understand the local hemodynamics. The lumped parameter (LP) model is mainly a closed loop circuit comprised of RLC compartments that model cardiac function as well as the viscous drag, flow inertia, and compliance of the different arterial and venous beds in the body.ID: 030423155; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references (p. 59-61).
M.S.
Masters
Mechanical, Materials, and Aerospace Engineering
Engineering and Computer Science
36
Kerley, Ross. "Small-scale hybrid alternative energy maximizer for wind turbines and photovoltaic panels". Honors in the Major Thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/457.
Texto completoResumen
This thesis describes the creation of a small-scale Hybrid Power System (HPS) that maximizes energy from a wind turbine and photovoltaic array. Small-scale HPS are becoming an increasingly viable energy solution as fossil fuel prices rise and more electricity is needed in remote areas. Modern HPS typically employ wind speed sensors and three power stages to extract maximum power. Modern systems also use passive rectifiers to convert AC from the wind turbine to DC that is usable by power electronics. This passive system inefficiently wastes power and introduces damaging harmonic noise to the wind turbine. The HPS described in this thesis does not require external wind speed sensors, and has independent wind and solar Maximum Power Point Tracking (MPPT). It converts AC from the wind turbine to DC with a Vienna rectifier that can be controlled to improve efficiency, allow MPPT, and allow Power Factor Correction (PFC). PFC all but eliminates the harmonic noise that can damage the wind turbine. A prototype HPS was built and evaluated that combines the two renewable sources in such a way that only two power stages are necessary, the Vienna rectifier and a step-down converter. This thesis describes the prototype and reports the results obtained.B.S.
Bachelors
Engineering and Computer Science
37
Hurson, Megan. "Social Capital in a Hybrid Online and Offline Social Networking Community". Master's thesis, Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/166367.
Texto completoResumen
Mass Media and CommunicationM.A.
Contemporary social networking sites (SNSs) are becoming common places where individuals and their respective networks congregate to exchange information. These places online are often thought as community and as Chua, Madej,and Wellman (2011) suggest "communities can consist of a person's network of relationships, wherever such communities are located" (p. 101). However, traditional social networking sites like Facebook and MySpace typically comprise networks that users are already familiar with, often brought into online spaces from their offline worlds (Baym, 2011). In order to gain social capital, an important element toward civic participation, users must engage in actions of exchanges with members of their network (Bourdieu, 1986). Different types of social capital afford different types of support, yet traditional social networks typically only afford bridging capital, a social tie that is most commonly found to only provide new information rather than trust and emotional support. Due to the fragmented nature of our contemporary media landscape, as outlined through networked individualism (Wellman, 1998), individuals navigate multiple networks instead of remaining in one locale. This study seeks to analyze these types of networks found within a hybrid online and offline community, Fark.com, in order to understand how media multiplexity (Haythorthwaithe, 2005) allows for different forms of social capital to accrue.
Temple University--Theses
38
TUNC, GOKHAN. "RC/COMPOSITE WALL-STEEL FRAME HYBRID BUILDINGS WITH CONNECTIONS AND SYSTEM BEHAVIOR". University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1020441384.
Texto completo
39
Middlebrook, Rebecca. "PEDAGOGICAL RE-MEDIATION IN HYBRID COURSES: A CASE STUDY OF FIVE FIRST-YEAR COMPOSITION INSTRUCTORS". Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4177.
Texto completoResumen
As the move to increase availability of composition courses in the online environment continues, it is important to understand the ways in which composition instructors have taken on the challenges associated with moving their teaching online and how they modify, or re-mediate, their pedagogy for the this new teaching and learning environment. This study takes on the task of examining re-mediation as it occurs in the pedagogical practices used by instructors to facilitate peer review activities in hybrid, first-year composition courses. At the same time, it is important to understand the varying factors that may influence the degree to which instructors re-mediate their pedagogy for this hybrid environment. This study also uncovers four factors that appeared to influence the degree to which the instructors re-mediated their pedagogical practices over the course of the semester in which this study was conducted. Results from this study will contribute to the field by serving as a guide to instructors and administrators who will teach and design hybrid composition courses or curricula in the future.Ph.D.
Department of English
Arts and Humanities
Texts and Technology PhD
40
Saleheen, Firdous. "BIMODAL DYNAMIC IMAGING SYSTEM FOR TUMOR CHARACTERIZATION USING HYBRID HIERARCHICAL STATISTICAL CONTROL". Diss., Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/465968.
Texto completoResumen
Electrical and Computer EngineeringPh.D.
Conventional medical imaging technologies for cancer diagnosis utilize fixed geometric configuration of the source and the detector to image the target. In this dissertation, we hypothesize that dynamic utilization of source and detector geometry will lead to better performance of medical imaging devices. Interrogating a target in a three dimensional space requires cooperation and coordination between the source and detector positions. The goal of this dissertation is to develop a dynamic imaging method, which will improve the tumor characterization performance, and provide a control scheme appropriate for the dynamic interrogation. This dissertation proposes a bimodal dynamic imaging (BDI) method for improving tumor characterization and a hybrid hierarchical statistical control scheme for the autonomous control of the sources and detectors. The tactile imaging sensor has high specificity but low sensitivity in tumor characterization. The spectral sensor has high sensitivity but low specificity. The BDI system integrates the tactile sensing and the spectral sensing modalities with the capability of dynamic positioning of the source and detector to determine the mechanical and spectral properties of a tumor. The tactile sensing can estimate the mechanical properties of the tumor, such as size, depth, and elastic modulus, while the spectral sensing can determine the absorption coefficient of the tumor through diffuse optical imaging. These properties help us characterize the tumor, and differentiate cancerous tissues from healthy tissues. We designed and experimentally evaluated the BDI system for estimating the size, depth, elastic modulus, and absorption coefficient of embedded inclusions. The system performance in characterizing mechanical properties was then compared to that of the tactile imaging sensor. The proposed BDI method was experimentally validated using fabricated bimodal phantom. The experimental results showed that the tactile imaging system (TIS) estimated the tumor phantom size with 7.23% error; BDI measured the size with 0.8% error. The TIS depth estimation error was 41.83%; BDI reduced the depth measurement error to 20.00%. The TIS elastic modulus estimation error was 96.80%; the BDI method showed 74.79% error. Additionally, BDI estimated the absorption coefficient with 14%-25% estimation error. For further improvement the system performance, this bimodal imaging system is implemented on a dual-arm robot, Baxter, where the laser source and the tactile imaging sensors were mounted on the end-effectors. Each arm of Baxter robot has seven Degree-of- Freedom. This provides more flexibility in terms of interrogating the target compared to the fixed geometric configuration. We devised a hybrid statistical controller for maneuvering the source and the detector of the system. In this control architecture, a high-level supervisory controller was used for the functions at a higher level for coordinating two arms. At lower level, a full-state feedback statistical controller was used to facilitate the minimum position variation. A linear model for the dual-arm Baxter robot was derived for testing the proposed architecture. We performed the simulations of hybrid hierarchical statistical controller on the Baxter model for trajectory tracking. The simulation studies demonstrated accurate sequential task execution for the bimodal dynamic imaging system using a hybrid hierarchical statistical control.
Temple University--Theses
41
Popat, Paiyal V. "Use of the yeast two-hybrid system to define the function of THAP5 protein". Honors in the Major Thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1310.
Texto completoResumen
This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Medicine
Microbiology and Molecular Biology
42
Linde, Daniel. "Evaluation of a Flat-Plate Photovoltaic Thermal (PVT) Collector prototype". Thesis, Högskolan Dalarna, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:du-24061.
Texto completoResumen
This Master thesis, in collaboration with Morgonsol Väst AB, was completed as a part of the Solar Energy engineering program at Dalarna University. It analyses the electrical and thermal performance of a prototype PVT collector developed by Morgonsol Väst AB. By following the standards EN 12975 and EN ISO 9806 as guides, the thermal tests of the collector were completed at the facility in Borlänge. The electrical performance of the PVT collector was evaluated by comparing it to a reference PV panel fitted next to it. The result from the tests shows an improved electrical performance of the PVT collector caused by the cooling and a thermal performance described by the linear efficiency curve ηth=0.53-21.6(Tm-Ta/G). The experimental work in this thesis is an initial study of the prototype PVT collector that will supply Morgonsol Väst with important data for future development and research of the product.
43
Bolden, Christian. "Evolution of the Folk Devil: A Social Network Perspective of the Hybrid Gang Label". Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3063.
Texto completoResumen
In keeping abreast of current gang phenomena, this study seeks to comparatively examine structural processes and characteristics of gangs in chronic gang city, San Antonio, and an emerging gang city that would be more likely to have "hybrid" gangs, Orlando. Hybrid gangs have been identified as having organizational processes that differ from traditional gangs; thus, this work will examine these processes that consist of a range of non-traditional phenomena, including cooperation between gangs, members switching gang affiliations, as well as gang initiations, and members leaving gangs. Additional characteristics uniquely associated with hybrid gangs consist of the notable presence of white, middle-class, and female gang members. Evidence suggests that the hybrid gang is more of a socially constructed moral panic than a reality. A limited number of recent studies have indicated that some gangs may better fit into a social network framework rather than a solid organizational analysis. WhePh.D.
Department of Sociology
Sciences
Sociology PhD
44
Andrasik, Stephen James. "NEW ORGANIC/INORGANIC HYBRID SOL-GEL NANOCOMPOSITE MATERIALS FOR RAMAN GAIN IN FIBER OPTICS". Master's thesis, University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4457.
Texto completoResumen
The recent increased availability of additional wavelengths in the telecommunications window of about 1300-1600 nm has generated an interest in new optical materials and devices that can operate outside the normally used regions of 840 nm, 1310 nm, and 1550 nm. Specifically, methods to amplify fiber optical data transmission in the regions where there is limited or no existing methods to achieve amplification is of interest in the chemistry and photonic communities. Raman gain is one method that has been proposed to passively amplify optical data transmission through a distributed process. Amplification is obtained through a nonlinear light scattering process where an optical wave is amplified at the expense of a higher frequency pump wave. Multiple wavelengths can be evenly amplified simultaneously in a desired region by specific selection of one or more pump wavelengths. Herein, the synthesis and characterization of new hybrid inorganic/organic sol-gels and monomers capable of producing broad wavelength Raman scattering over a spectral range of 1200-1670 nm are presented. The synthetic methodology developed facilitates the systematic approach to produce sol-gel derivatives with functional groups known to be strongly Raman scattering. Additionally, a method to synthesize and characterize a large number of different compounds using a combinatorial approach was demonstrated. Thio based derivatives of sulfonyldiphenol, isopropylidenediphenol, and triallyloxy triazine were synthesized in addition to thio derivatives of poly(hydroxystyrene). Micro-Raman spectra of the hybrid sol-gels, thio-based derivatives, and IR spectra of select sol-gel monomers were obtained.M.S.
Department of Chemistry
Arts and Sciences
Chemistry
45
JÃnior, Francisco Holanda. "Comparative study of capture hÃbrida-hpv-dna for domiciliary autocoleta and it collects doctor". Universidade Federal do CearÃ, 2005. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=353.
Texto completoResumen
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoCoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
A infecÃÃo pelo Papilomavirus humano à a principal causa do carcinoma de colo uterino. No Cearà o cÃncer cervical à o segundo mais freqÃente entre as mulheres, quando se excetua o cÃncer de pele. à uma doenÃa de fÃcil prevenÃÃo, haja vista que quando se dispÃe de um serviÃo bem estruturado a mortalidade à reduzida em atà 80% dos casos. O problema à que muitas mulheres nÃo tÃm acesso a testes de varredura, cujos motivos estÃo relacionados a diversas barreiras culturais e geogrÃficas, bem como a baixa oferta e/ou inexistÃncia de serviÃos. O Cearà conta com cerca de 10.000 agentes comunitÃrios de saÃde, o que representa uma possibilidade de se levar um teste de autocoleta atà estas mulheres, considerando, todavia, que este teste tivesse uma sensibilidade e especificidade aceitÃvel e, assim, atendendo rapidamente um quantitativo significativo de mulheres que nunca fizeram o exame de prevenÃÃo ou estÃo em intervalo recomendado para repeti-lo. Em face ao exposto, este estudo tem por objetivo comparar a sensibilidade e especificidade da Captura HÃbrida de espÃcime cÃrvico-vaginal para HPV-DNA por autocoleta domiciliar em condiÃÃes reais, com a Captura HÃbrida para HPV-DNA coletado por mÃdico ginecologista em consultÃrio e nas condiÃÃes ideais. Os dados foram coletados no perÃodo de agosto a dezembro de 2002, junto a 878 mulheres de cinco cidades cearenses. Estas foram submetidas, na mesma semana, aos testes de Captura HÃbrida por autocoleta, citologia, Captura HÃbrida coletada pelo mÃdico ginecologista, colposcopia e histopatolÃgico, quando necessÃrio. Das 878 mulheres participantes 815 foram consideradas negativas pelo padrÃo ouro, 54 foram consideradas positivas - baixo grau e 9 foram consideradas alto grau - carcinoma. Nos resultados das amostras para Captura HÃbrida HPV-DNA da autocoleta e da coleta mÃdica, obtiveram-se que em 546 casos, ambos os testes concordaram como negativos, em 216 casos concordaram como positivos, em 35 casos houve discordÃncia com a coleta mÃdica positiva e em 81 casos houve discordÃncia com a autocoleta positiva. Os percentuais de sensibilidade encontrados da citologia, Captura HÃbrida por coleta mÃdica e Captura HÃbrida autocoleta foram, respectivamente, 18,3%, 63,3% e 66,7%. Os percentuais de especificidade verificados da citologia Captura HÃbrida coleta mÃdica e Captura HÃbrida autocoleta foram, respectivamente, 98,0%, 73,0% e 68,7%. Comparando-se a concordÃncia entre ambas as coletas de Captura HÃbrida, obteve-se o coeficiente de Kappa (K=0,693) com um erro padrÃo de 0,026 embora existe diferenÃa significativa da prevalÃncia detectada por ambos os testes, teste de McNemar (p<0,001). Avaliando-se as Ãreas da curva ROC para ambos os testes, mostrou-se coleta mÃdica Ãrea=0,738 com coeficiente de 95% de certeza - o intervalo de confianÃa IC=[0,673;0,802] e autocoleta Ãrea= 0,670 com 95% de certeza - o intervalo de confianÃa IC=[0,597;0,742] para detecÃÃo do Papilomavirus. Concluiu-se haver boa concordÃncia entre os resultados obtidos pela autocoleta de espÃcime para realizaÃÃo da Captura HÃbrida HPV-DNA com a coleta mÃdica.
Human Papillomavirus infection is the mean cause of the most of cervical cancers. In Cearà this type of cancer is the second in frequency among the women, when the skin cancers are excluded. Cervical cancer is one the most preventable. Where well structured programs exist the mortality has declined, and in some cases in about 80% .The mean problem is that cervical cancer screening is not fully utilized among groups of women, especially those without access or because there are no services offered or when services exist there are many other barriers, since cultural aspects to geographic barriers. In Cearà exist well structured Health communitarian agents program, which we estimate in about 10.000 agents that cover fully the necessities of population in their areas and the all Cearà territory. With this program we can carry on one screening program by self-sampling if this test were acceptable and had a good sensitivity and specificity. By these communitarian agents we could insert in screening program all women who never underwent to pap smear or other type of screening test. The mean objective of this work is to determine whether testing of self-collected vaginal specimen for Human Papillomavirus has the same accuracy of sampling collected by physicians . In order to evaluate this one Cross-sectional observational study was done between August and December of 2002, 878 women from five municipalities were enrolled and the tests were done in the same week, the women started by doing self-sampling at home and after that they were undergone in physicianâs clinics to the others examination in following sequence cytology, hybrid capture HPV-DNA, colposcopy and when were necessary biopsy. OF 878 women that participated in this study , 815 were considered negative by the gold standard ,54 were considered positive low grade and 9 were high grade/ carcinoma . Of 878 samples to HPV-DNA , there was negative concordance to both test in 546 samples, there was positive concordance in 216 samples, there was discordance in 35 samples where the physician collect were positive and finally there was discordance in 81 samples where the self-collect were positive. The results of sensitivity to cytology, Hybrid Capture by physicians, Hybrid Capture by self-sampling were, respectively 18%, 63,3% and 66,7%. The prevalence estimated by the gold standard were 7,2% in this sample. The results of specificity to cytology, hybrid capture by physicians, hybrid capture by self-sampling were, respectively 98%, 73% and 68,7%. There was significant difference between the results of HPV-DNA self-collected and collected by the physicians, McNemar test p<0,001. When we compare the concordance through the Kappa index we have obtained k=0,693 with stand error of 0,026. Compared the areas obtained by the ROC curve as follows area=0,738 that represent the achievement of physician collected with IC=[0,673;0,802] with 95% confidence interval to detect HPV in sample, area=0,670 that represent the achievement of self-collected sample to HPV with the 95% of confidence interval IC=[0,597;0,742].We concluded that Hybrid Capture by self-collected vaginal sample is as good as Hybrid Capture collected by the physicians, and there was good concordance between these tests.
46
Lavin, Amy A. "Assessing Student Characteristics for Success in Online Versus Face-to-Face Environments". Diss., Temple University Libraries, 2019. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/598584.
Texto completoResumen
Educational LeadershipEd.D.
Online education is pervasive in higher education today. More students are taking courses online than ever before. Institutions are encouraged to adopt virtual classrooms as the market demands access. This study examined the characteristics of students who choose to enroll in online or face-to-face courses and their eventual academic outcomes in their selected course. The purpose was to determine whether online and face-to-face students possess the same skillsets or if there are characteristics that a student should possess when choosing to enroll in an online class or program. Additionally, this study examined students’ perception of online courses versus face-to-face courses to determine if there were any differences in students’ feedback based on the type of course in which they were enrolled. The course Management Information Systems 101 (MS107) served as the focus of this study; it is a required undergraduate business course in an urban university. Typically, undergraduate sophomores or juniors take this course and are declared business majors at the university. The units for analysis consisted of students enrolled in MS107 in the fall of 2017 and spring of 2018 semesters. The online courses were conducted via WebEx, synchronously with live interaction from the professor. The face-to-face classes were conducted in the traditional environment on the university’s main campus. Data were collected from the university’s student system, student feedback forms, and the university’s New Student Questionnaire (NSQ) and concatenated to present a full picture of each student’s course outcome, demographics, and responses to the NSQ. The purpose in analyzing this information was to determine if there are behavioral, demographic, or other characteristics that might lend to better or worse performance in an online classroom. Finally, student feedback was analyzed to determine whether students have different opinions of MS107 depending on course delivery method. Results of this study indicate that from a course delivery perspective, engagement between students and faculty is a critical asset that should be developed in the online classroom environment. In the analysis of the student self-reported characteristics, many of the characteristics for success for the entire sample hold true for the characteristics of successful students in the face-to-face sections. For the online sections, however, the key predictors of success are simply previous grade point average and expectation of high averages in college, eliminating variables like self-confidence and hard working. The results of this study support prior research that states students perform better in face-to-face classrooms than online; however, this research begins to showcase what opportunities might be available for improvement in the online classroom
Temple University--Theses
47
Palaniappan, Ravishankar. "A SELF-ORGANIZING HYBRID SENSOR SYSTEM WITH DISTRIBUTED DATA FUSION FOR INTRUDER TRACKING AND SURVEILLANCE". Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2407.
Texto completoResumen
A wireless sensor network is a network of distributed nodes each equipped with its own sensors, computational resources and transceivers. These sensors are designed to be able to sense specific phenomenon over a large geographic area and communicate this information to the user. Most sensor networks are designed to be stand-alone systems that can operate without user intervention for long periods of time. While the use of wireless sensor networks have been demonstrated in various military and commercial applications, their full potential has not been realized primarily due to the lack of efficient methods to self organize and cover the entire area of interest. Techniques currently available focus solely on homogeneous wireless sensor networks either in terms of static networks or mobile networks and suffers from device specific inadequacies such as lack of coverage, power and fault tolerance. Failing nodes result in coverage loss and breakage in communication connectivity and hence there is a pressing need for a fault tolerant system to allow replacing of the failed nodes. In this dissertation, a unique hybrid sensor network is demonstrated that includes a host of mobile sensor platforms. It is shown that the coverage area of the static sensor network can be improved by self-organizing the mobile sensor platforms to allow interaction with the static sensor nodes and thereby increase the coverage area. The performance of the hybrid sensor network is analyzed for a set of N mobile sensors to determine and optimize parameters such as the position of the mobile nodes for maximum coverage of the sensing area without loss of signal between the mobile sensors, static nodes and the central control station. A novel approach to tracking dynamic targets is also presented. Unlike other tracking methods that are based on computationally complex methods, the strategy adopted in this work is based on a computationally simple but effective technique of received signal strength indicator measurements. The algorithms developed in this dissertation are based on a number of reasonable assumptions that are easily verified in a densely distributed sensor network and require simple computations that efficiently tracks the target in the sensor field. False alarm rate, probability of detection and latency are computed and compared with other published techniques. The performance analysis of the tracking system is done on an experimental testbed and also through simulation and the improvement in accuracy over other methods is demonstrated.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Modeling and Simulation PhD
48
PEPPAS, NIKOLAOS. "A HYBRID ROUTING PROTOCOL FOR COMMUNICATIONS AMONG NODES WITHHIGH RELATIVE SPEED IN WIRELESS MESH NETWORKS". Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2345.
Texto completoResumen
Wireless mesh networks (WMN) is a new promising wireless technology which uses already available hardware and software components. This thesis proposes a routing algorithm for military applications. More specifically, a specialized scenario consisting of a network of flying Unmanned Aerial Vehicles (UAVs) executing reconnaissance missions is investigated. The proposed routing algorithm is hybrid in nature and uses both reactive and proactive routing characteristics to transmit information. Through simulations run on a specially built stand alone simulator, based on Java, packet overhead, delivery ratio and latency metrics were monitored with respect to varying number of nodes, node density and mobility. The results showed that the high overhead leads to high delivery ratio while latency tends to increase as the network grows larger. All the metrics revealed sensitivity in high mobility conditions.M.S.Cp.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Computer Engineering MSCpE
49
Zhuge, Jinfeng. "PROCESSING, OPTIMIZATION AND CHARACTERIZATION OF FIRE RETARDANT POLYMER NANOCOMPOSITES". Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4246.
Texto completoResumen
Fiber reinforced polymeric composites (FRPC) have superior physical and mechanical properties, such as high specific strength, light weight, and good fatigue and corrosion resistance. They have become competitive engineering materials to replace conventional metallic materials in many important sectors of industry such as aircraft, naval constructions, ships, buildings, transportation, electrical and electronics components, and offshore structures. However, since FRPC contain polymer matrix, the polymer composites and their structures are combustible. FRPC will degrade, decompose, and sometimes yield toxic gases at high temperature or subject to fire conditions. The objective of this study is to design and optimize fire retardant nanopaper by utilizing the synergistic effects of different nanoparticles. A paper-making technique that combined carbon nanofiber, nanoclay, polyhedral oligomeric silsesquioxanes, graphite nanoplatelet, and ammonium polyphosphate into self-standing nanopaper was developed. The fire retardant nanopaper was further incorporated into the polymer matrix, in conjunction with continuous fiber mats, through resin transfer molding process to improve fire retardant performance of structural composites. The morphology, thermal stability, and flammability of polymer composites coated with hybrid nanopaper were studied. The cone calorimeter test results indicated that the peak heat release rate of the composites coated with a CNF-clay nanopaper was reduced by 60.5%. The compact char material formed on the surface of the residues of the CNF-clay nanopaper was analyzed to understand the fire retardant mechanism of the nanopaper. The financial support from Office of Naval Research is acklowdged.M.S.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering MSME
50
Alla, Nageswara Rao. "Studies on human ribonuclease H1 and its action on 2'-fluoroarabinose oligonucleotide hybrid substrates". Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/182925.
Texto completoResumen
ChemistryPh.D.
Ribonuclease H1 is a conserved enzyme that is localized in the nuclear and mitochondrial compartments of eukaryotic cells, and functions in DNA replication, repair, recombination and transcription. (Arunachandran et al., 2000; Cerritelli et al., 2003) Oligonucleotide binding to a complementary RNA sequence can provide a substrate for RNase H1, and provides the mechanistic basis for antisense oligonucleotide (AON)-directed gene silencing in cells (Opalinska et al., 2002). Effective evaluation of the therapeutic efficacy of next-generation AONs with novel structures requires an in vitro system involving, purified, highly active RNase H1 of human cells, and a full understanding of the catalytic mechanism of the enzyme. The goal of project 1 described in chapter 3, was to determine the involvement of a conserved Histidine (H264) in the catalytic mechanism of human RNase H1. Based on this analysis I was able to conclude that H264 has a dual role in phosphodiester hydrolysis and in product release. The goal of project 2 (Chapter 4) was to examine the reactivities towards human RNase H1 of model hybrid substrates containing specific types of 2'-FANA substitutions (abbreviated as `F', with 2'-deoxyribose abbreviated as `D'), either at the "wings" of the molecule ("7-gapmer"; each wing=7 nt: FFFFFFF-DDDDDDD-FFFFFFF), or with 3 nt alternations ("3-altimer": FFF-DDD-FFF-DDD-FFF-DDD-FFF). The results of this study strongly support the continued examination of the potential therapeutic utility of the 2'-FANA modification in AONs. The highly efficient and selective inhibition of protein expression is a primary basis of action of most antisense therapeutic strategies. These data suggest that the 2'-FANA modification supports sustained silencing after a single administration, either by mRNA cleavage or by a translational block, and at substantially lower concentrations compared to the unmodified AON. The results of this project underscore the proposal that 2'-FANA-modified AONs will be important additions to the repertoire of rational antisense strategies for the effective treatment of disease.
Temple University--Theses