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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Clustering biological data using a hybrid approach : Composition of clusterings from different features

Keller, Jens January 2008 (has links)
<p>Clustering of data is a well-researched topic in computer sciences. Many approaches have been designed for different tasks. In biology many of these approaches are hierarchical and the result is usually represented in dendrograms, e.g. phylogenetic trees. However, many non-hierarchical clustering algorithms are also well-established in biology. The approach in this thesis is based on such common algorithms. The algorithm which was implemented as part of this thesis uses a non-hierarchical graph clustering algorithm to compute a hierarchical clustering in a top-down fashion. It performs the graph clustering iteratively, with a previously computed cluster as input set. The innovation is that it focuses on another feature of the data in each step and clusters the data according to this feature. Common hierarchical approaches cluster e.g. in biology, a set of genes according to the similarity of their sequences. The clustering then reflects a partitioning of the genes according to their sequence similarity. The approach introduced in this thesis uses many features of the same objects. These features can be various, in biology for instance similarities of the sequences, of gene expression or of motif occurences in the promoter region. As part of this thesis not only the algorithm itself was implemented and evaluated, but a whole software also providing a graphical user interface. The software was implemented as a framework providing the basic functionality with the algorithm as a plug-in extending the framework. The software is meant to be extended in the future, integrating a set of algorithms and analysis tools related to the process of clustering and analysing data not necessarily related to biology.</p><p>The thesis deals with topics in biology, data mining and software engineering and is divided into six chapters. The first chapter gives an introduction to the task and the biological background. It gives an overview of common clustering approaches and explains the differences between them. Chapter two shows the idea behind the new clustering approach and points out differences and similarities between it and common clustering approaches. The third chapter discusses the aspects concerning the software, including the algorithm. It illustrates the architecture and analyses the clustering algorithm. After the implementation the software was evaluated, which is described in the fourth chapter, pointing out observations made due to the use of the new algorithm. Furthermore this chapter discusses differences and similarities to related clustering algorithms and software. The thesis ends with the last two chapters, namely conclusions and suggestions for future work. Readers who are interested in repeating the experiments which were made as part of this thesis can contact the author via e-mail, to get the relevant data for the evaluation, scripts or source code.</p>
192

Improving the energy density of hydraulic hybridvehicle (HHVs) and evaluating plug-in HHVs /

Zeng, Xianwu. January 2009 (has links)
Thesis (M.S.)--University of Toledo, 2009. / Typescript. "Submitted as partial fulfillment of the requirements for The Master of Science in Mechanical Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 75-78.
193

Bias analysis in mode-based Kalman filters for stochastic hybrid systems

Zhang, Wenji January 1900 (has links)
Doctor of Philosophy / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / Stochastic hybrid system (SHS) is a class of dynamical systems that experience interaction of both discrete mode and continuous dynamics with uncertainty. State estimation for SHS has attracted research interests for decades with Kalman filter based solutions dominating the area. Mode-based Kalman filter is an extended version of the traditional Kalman filter for SHS. In general, as Kalman filter is unbiased for non-hybrid system estimation, prior research efforts primarily focus on the behavior of error covariance. In SHS state estimate, mode mismatch errors could result in a bias in the mode-based Kalman filter and have impacts on the continuous state estimation quality. The relationship between mode mismatch errors and estimation stability is an open problem that this dissertation attempts to address. Specifically, the probabilistic model of mode mismatch errors can be independent and identically distributed (i.i.d.), correlated across different modes and correlated across time. The proposed approach builds on the idea of modeling the bias evolution as a transformed system. The statistical convergence of the bias dynamics is then mapped to the stability of the transformed system. For each specific model of the mode mismatch error, the system matrix of the transformed system varies which results in challenges for the stability analysis. For the first time, the dissertation derives convergence conditions that provide tolerance regions for the mode mismatch error for three mode mismatch situations. The convergence conditions are derived based on generalized spectral radius theorem, Lyapunov theorem, Schur stability of a matrix polytope and interval matrix method. This research is fundamental in nature and its application is widespread. For example, the spatially and timely correlated mode mismatch errors can effectively capture cyber-attacks and communication link impairments in a cyber-physical system. Therefore, the theory and techniques developed in this dissertation can be used to analyze topology errors in any networked system such as smart grid, smart home, transportation, flight management system etc. The main results provide new insights on the fidelity in discrete state knowledge needed to maintain the performance of a mode-based Kalman filter and provide guidance on design of estimation strategies for SHS.
194

Anslutning av hybridfordon somreservkraft till elnätet / Connecting hybridengine to the electric grid

Eriksson, Peter January 2018 (has links)
Detta examensarbete är en konceptstudie som har genomförts tillsammans med BAE System. Huvudmålet är att ta fram gällande lagkrav samt ett förslag på en teknisk lösning.Den tekniska lösningen ska utvecklas för att kunna använda ett hybridfordon för att kunna verka som reservkraftanläggning. Det som framkommer i rapporten är att lagkraven är möjligt att efterleva och därför finns en utvecklingspotential i den tekniska lösningen.Tekniskt sett är det möjligt att ansluta hybridfordonet till elnätet. Detta kan genomföras genom att likrikta spänningen från generatorn i hybridfordonet för att sen ansluta till en omriktare som kan skapa en önskvärd amplitud på sinusspänningen. Efter omriktaren kommer det behövas ett LCL-filter för att på så sätt få en renare AC-spänning. Spänningen kommer sen att behöva kopplas in på en transformator för att kunna skapa ett TN-S system.För att kunna skapa ett TN-S system kommer transformatorn behöva vara av typen D/Yo så man på Y0 kan ansluta en jordpunkt för att kunna uppnå ett direktjordat system vilket underlättar för att kunna bygga upp ett nät med selektivitet. För att få dom olika delarna att samverka behövs kommunikation mellan hybridfordonet och omriktaren om vilket effektbehov som finns.
195

Porovnání výnosových a kvalitativních parametrů vybraných hybridů silážní kukuřice

Seryn, Jaroslav January 2014 (has links)
This thesis presents a comparison of quality and yield parameters of corn silage hybrids. The basis for the work was a pilot experiment, which was set in 2013 on the land of the agriculture company ÚSOVSKO. During the growing period differences among hybrids were recorded at different growth stages. At harvest, yield of biomass was assessed and then the samples were taken for laboratory analyses. The following characteristics of particular hybrids were evaluated: dry matter content, starch content, the content of N-substances, content of ADF and NDF, cellulose content, ash and fat content. Based on obtained data the methane production and milk production from one ton of silage and per one hectare of crop was calculated as well as estimation of digestibility.
196

Ověřování SSR markerů vhodných pro rozlišování odrůd vybraných zelenin z čeledi Brassicaceae

Sochorová, Jana January 2014 (has links)
In available literature there is no recommended set of microsatellite markers in the improvement of cabbage cultivars (Brassica oleracea conv. capitata) to distinguish F1 hybrids and self-pollinated plants with a parental genotype. That is why microsatellite markers used to other Brassicas had been searched in this work. Tested microsatellite markers were studied for their ability of distinguishing F1 hybrids in seven cabbage cultivars. Two of 23 microsatellite markers were able to distinguish F1 hybrids in six cabbage cultivars. No microsatellite marker was able to distinguish F1 hybrid and parental genotypes of one cultivar, 'A'.
197

Vliv vegetačních fází na chemické složení a výživnou hodnotu vícesečných hybridů čiroku

Hrabětová, Dana January 2012 (has links)
No description available.
198

Synthèse par polymérisation en émulsion d’objets hybrides dans le système silice/latex : Application à la granulation par voie colloïdale de l’alumine / Emulsion polymerization of hybrids particles in the silica/latex system : Application to processing alumina spheres by colloidal route

Monegier du Sorbier, Quitterie 21 March 2016 (has links)
La synthèse d’objets hybrides silice/latex constitue le coeur de ce travail de doctorat ; il s’agit de recouvrir partiellement des particules de polystyrène par de la silice nanométrique. Pour cela la polymérisation en émulsion de la phase organique in-situ en présence de nanoparticules de silice a été sélectionnée, en présence d’auxiliaires organiques pour rendre les surfaces amphiphiles. Les premières formulations mises en oeuvre avec des tensioactifs n’ont pas conduit à la décoration des latex parce que la présence de ces molécules aux interfaces favorise plutôt la dispersion des latex, empêchant l’adsorption de la silice. Par la suite, l’étude de deux systèmes composés respectivement d’une silice chargée négativement et du PEGMA, et d’une silice chargée positivement et du PSS, ont permis d’obtenir des latex « décorés » caractérisés par ATG et MET. Les mécanismes proposés s’appuient, selon les conditions, sur des mécanismes de nucléation homogène ou de nucléation en gouttelettes. Il apparait que la maîtrise des interactions pouvant être produites à la surface du latex est très importante pour permettre à la silice de se placer à sa surface. Ainsi, le choix de l’amorceur ou de l’auxiliaire organique est un paramètre clé pour obtenir des particules hybrides.Dans la dernière partie de cette étude, la silice a été introduite sous la forme d’objets hybrides silice/latex dans une suspension d’alumine pour procéder à l’hétérocoagulation des deux matériaux et à la granulation de l’alumine. La combinaison des propriétés des matériaux organique et inorganique constituant les particules hybrides a permis de conduire à l’amélioration de l’organisation microstructurale interne du granule lors de l’étape de séchage, en diminuant de manière significative les fissurations au sein des granules. / This work is centered on the silica/latex hybrid particles synthesis: the aim of the study is to partially cover the polystyrene beads with silica nanoparticles. For this purpose, in-situ emulsion polymerization of the organic phase with silica has been selected with organic auxiliaries to make the surfaces amphiphilic. The first compositions processed with surfactants did not lead to latex decoration because the presence of the molecules at the interface favors the dispersion of the latex impeding silica adsorption. Then, the study of two systems with, in one hand negatively charged silica and PEGMA, and in the other hand positively charged silica and PSS, allowed to get “decorated” latex characterized by TGA and TEM. The proposed mechanisms are based on the homogeneous nucleation or the droplet nucleation mechanisms depending on the conditions. It appears that the control of the interactions that could be produced at the surface of the latex is very important to allow the silica to go at the surface. Thus, the initiator or organic auxiliary choice is a key parameter to get hybrid particles.In the last part of this study, silica has been introduced via hybrid particles in an alumina suspension to proceed to heterocoagulation of both materials leading to alumina granulation. The combination of the properties of the organic and inorganic material that constitute the hybrid particles leads to the improvement of the microstructural organization inside the spheres during the drying step by reducing significantly the cracks in the spheres.
199

Functionalization of Organic-Inorganic Nano-Hybrids Utilizing Inorganic Nanoparticles / 無機ナノ粒子を利用した有機無機ナノハイブリッドの機能化

Otsuka, Takeshi 24 September 2010 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15674号 / 工博第3332号 / 新制||工||1503(附属図書館) / 28211 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 中條 善樹, 教授 澤本 光男, 教授 赤木 和夫 / 学位規則第4条第1項該当
200

Polyimide-silica hybrids based on polyamic acid and an acetylene-terminated isoimide as matrices for carbon fibre composites

Xenopoulos, Constantinos January 1999 (has links)
A study was carried out on formulations of organic-inorganic hybrids and their subsequent use as matrices for unidirectional carbon fibre-reinforced composites. The hybrids consist of low molecular weight polyimide precursors and silica which is generated in-situ via the sol-gel route. A special feature of these systems is the use of organofunctional trialkoxysilanes as coupling agents for the two phases and for controlling the resultant morphology. Enhancements are obtained in physicochemical, thermal and mechanical properties of hybrids through morphological modifications achieved in the parent polyimide and silicate materials. Small variations to the composition of the precursors display a substantial effect both on the kinetics of the associated reactions and the final properties of hybrids, often as a result of a change in miscibility of the organic and the inorganic components of the system. The processability of the matrix was evaluated with respect to the fabrication of composites, which in this case is strongly influenced by the gelation behaviour of both the organic pre-polymer and also the inorganic sol-gel component. The kinetics of gelation reactions were examined by dynamic viscometry and by practical tests based on visual observation of the cessation of flow. Differential scanning calorimetry, infrared spectroscopy, thermogravimetric analysis and electron microscopy formed part of the evaluation of the matrix materials. Composites were produced by application of the matrix solution from a variety of formulations on pre-tensioned fibres, followed by vacuum drying and curing under pressure at high temperatures. The properties of these composites were determined by such methods as dynamic mechanical thermal analysis, flexural testing and thermomechanical analysis. From the results obtained in this study, it is concluded that the inclusion of silicate phase in a polyimide matrix in the form of fine co-continuous networks improves the thermal and mechanical properties of the base material, although these are dependent on the overall silicate content and the amount of the coupling agent. High loadings of the coupling agent can cause degradation by chain scission and a reduction of the crosslinking density of the organic pre-polymer.

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