Dissertations / Theses on the topic 'UTDF'

Workshop "Netz- und Service-Infrastrukturen" Unicode bietet erstmals die Möglichkeit, jedes in der Welt vorkommende Zeichen eindeutig im Rechner abzubilden. Im Vortrag wird auf mögliche Probleme bei der Umstellung, wie z.B. die Verarbeitung von bereits vorhanden Daten, die Parallelarbeit mit unterschiedlichen Kodierungssystemen und den remote Aufruf von Rechnern mit einer anderen Kodierung, eingegangen.

Large phased array antennas are widely used in many military and commercial applications. The analysis of large arrays containing many antenna or frequency-selective (FSS) surface elements is inefficient or intractable when brute force numerical methods are used. For the efficient analysis of such structures hybrid methods (analytic and numerical, numerical and numerical) can be used. In this thesis, a hybrid method combining the uniform geometrical theory of diffraction (UTD) and the moment method (MoM) used for the analysis of large, finite arrays is modified for the efficient yet accurate analysis of large printed dipole arrays. In the present hybrid UTD-MoM approach, the number of unknowns to be solved is drastically reduced as compared to the conventional MoM approach, which provides a great efficiency on the computational cost. This extreme reduction in the number of MoM unknowns is carried out by introducing a few UTD-ray type global basis functions for the unknown array element currents. In this study, this hybrid UTD-MoM method is applied to the analysis of a finite, planar periodic array of printed dipoles on a grounded dielectric substrate. The efficiency and accuracy of this hybrid method are demonstrated with some numerical results.

This paper presents a two-stage model of optimization as a quick method to choose the best potential links for implementing urban travel demand management (UTDM) strategy like road pricing. The model is optimized by minimizing the hidden cost of congestion based on user equilibrium (MHCCUE). It forecasts the exact amount of flows and tolls for links in user equilibrium condition to determine the hidden cost for each link to optimize the link selection based on the network congestion priority. The results show that not only the amount of total cost is decreased, but also the number of selected links for pricing is reduced as compared with the previous toll minimization methods. Moreover, as this model just uses the traffic assignment data for calculation, it could be considered as a quick and optimum solution for choosing the potential links.

Hybridation d'une méthode intégrale (MoM) avec une méthode de rayon (UTD), en particulier en présence de corps imbriqués. C'est le point de départ d'une réflexion synthétique plus générale sur les méthodes de raccordement utilisées en électromagnétisme qui conduit à une présentation unifiée de ces raccordements au travers d'une classification en deux types dont les conditions de non singularité sont démontrées. Cette présentation est applicable à tous les types de formulation des champs : différentielle, intégrale, asymptotique, spectrale… Outre l'hybridation, deux autres applications de cette approche sont proposées : une nouvelle formulation intégrale bien posée sur corps impédant prolongeable aux objets parfaitement conducteurs et la formulation CFIE sur corps mince ou ouvert<br>Implementation of a hybrid Integral Equation Method (MOM)/ Uniform Theory of Diffraction (UTD) formulation for small dielectric (or PEC) protrusions embedded into a large conducting body. Carrying out hybrid techniques leads to more general considering about connection of electromagnetic problems. Resulting from that, a reliable interpretation and a unified classification of usual connection techniques into two types is proposed. For both type, well posedness conditions are pointed out. This classification applies to all types of fields formulations (differential, integral, ray, spectral…). In addition to Hybrid MoM/UTD, two more applications of this lateral thinking are proposed: a new well posed integral formulation for scattering by impedant (IBC) 3D bodies that can be extended to PEC and the formulation of CFIE on an open or thin PEC object

L’Abjad en tant que système d’écriture du monde arabe, qui s’étend de l’océan atlantique à l’océan pacifique. L’Abjad n’est pas un alphabet au sens européen du terme. Issue de calligraphies et rencontres culturelles variées, comment ce système d’écriture est-il devenu celui des arabes ? il n’est pas l’œuvre de Mahomet, il est plus ancien que le prophète. Mais le Coran demeure le livre sacré des arabes et l’Abjad, une écriture sacrée, intouchable, inviolable. La langue arabe a une morphologie particulière fondée sur des racines et des schèmes. Aussi, un mot peut être écrit sous un grand nombre de formes, sans compter les différentes orthographes dépendant de la prononciation car il existe de nombreux dialectes et un état de diglossie qui complique les règles d’usage dans le monde musulman, malgré un arabe classique, système présent dans le coran, et que tout homme éduqué doit savoir écrire et lire. L’Abjad n’est pas seulement un problème culturel, mais aussi un problème informatique. Unicode fut une révolution dans ce domaine, en permettant de traiter la totalité de l’Abjad avec ses 943 caractères environ, sur son unique page de code. Mais Unicode demande un encodage. Trois solutions alors sont proposées : utf-8, utf-16, utf-32. Nous avons retenu utf-32 malgré des inconvénients indiscutables. En somme, l’Abjad empêche, les arabes de développer à grande échelle la diffusion de texte dans leur langue. Il devrait donc, être possible de normaliser l’Abjad, mais pour des raisons religieuses, on ne peut retenir cette solution. Car, le monde arabe ne supporterait pas qu’en quelconque façon il soit porté atteinte à l’Abjad dans lequel le Coran est écrit. Mais cela même condamne l’Abjad à rester une écriture religieuse et non un outil de communication moderne pour les affaires, la banque et le commerce<br>In this thesis, we sought to show the difficulties due to the religious dimension of the Abjad, the scripting of the Arabs, when implementing on computers the scripting systems of all the people in the world, following the Unicode project, and the consequences waited in NLP. First of all the Abjad is not an alphabet in the European meaning of the word, its holy scripting. This scripting is also the one of a Semitic language, endowed with a particular morphology based upon roots and schemes and many diacritics which depends upon the pronunciation of different dialects, event if the classical Arabic scripting present in the Koran is accessible to all man who can read and write. This scripting is not disappearing in the modern world, Arabic and the Abjad have succeeded in finding words to describe the concepts of the European political thought and all the ways and means to spread Islam throughout the world. The rare words borrowed from the Occident have to be accustomed into Arabic, because of its morphology with roots ands schemes with which European words cannot match. . . The Abjad is essential to translations, or high quality information research. Abjad is not only a cultural problem but also a technical, computer one : the only solution to install Arabic on Microsoft’s systems was the manual or external choice of the language. It was evident that the whole Abjad was not taken into account. Unicode was a revolution, allowing taking into account the whole Abjad with its 943 characters, but Unicode required an encoding scheme. To implement theses caracters on the machine, we made up our mind on the utf-8, in spite of its drawbacks, in particular when doing natural language processing. All attempts to normalise Abjad is to rule out for religious reasons : Abjad is the holy scripting of the Koran and that prevents to become a modern communication tool for business or trade and the cultural and religious dimension of the Abjad and the Koran are at the centre of the Arabian life and more than any other preoccupation, be it the economical development of their countries, their cultural presence on modern communication media or the implementation of automatic tools to process written information

Thesis (MEng)--Stellenbosch University, 2000.<br>ENGLISH ABSTRACT: Fouling is readily acknowledged as one of the most critical problems limiting the wider application of membranes in liquid separation processes. A better understanding of fouling layer formation and its monitoring is needed in order to improve on existing cleaning techniques. Plant operation can be optimised if fouling can be monitored by noninvasion means either on the plant itself or on an attached monitoring device. The overall scope of this research was to develop a non-destructive, real-time, in situ visualisation technique or device for concentration polarisation and fouling layer monitoring. Ultrasonic-time-domain-reflectometry (UTDR) was employed as a visualisation technique to provide real-time characterisation of the fouling layer. A 24 cm-long rectangular flat sheet aluminium cell was designed and used as separation device for a desalination system. The experimental results obtained using this module confirmed that there are an excellent correspondence between the flux decline behaviour and the UTDR response from the membrane. The ultrasonic technique could effectively detect fouling layer initiation and growth on the membrane in real-time. In addition to the measurement of fouling, the ultrasonic technique was also successfully employed for monitoring membrane cleaning. Since no real-time permeation data is available during cleaning operations in industrial applications, a UTDR monitoring device may prove to be a very valuable technique in optimising cleaning strategies. The technique was further tested on an 8-inch diameter spiral wrap industrial module and good results were obtained. Stagnant zones, as well as flux flow behaviour inside the module could be determined. However, more research IS needed to fully understand the complex phenomena inside a spiral wrap module. Overall, the UTDR technique and its use in monitoring devices have a major impact in the membrane industry due to its extremely powerful capabilities.<br>AFRIKAANSE OPSOMMING: Membraan-bevuiling of -verstopping is die grootste struikelblok wat die algemene aanwending van membrane vir verskillende watersuiweringsprosesse negatief beinvloed. 'n Beter begrip van membraan-bevuiling, asook beter metingsmetodes daarvan is nodig om op bestaande skoonmaaktegnieke te verbeter. Die hoofdoel van hierdie studie was die ontwikkeling van 'n nie-destruktiewe-in-lyn visuele tegniek vir die meting van konsentrasie polarisasie en membraan-bevuiling. Deur gebruik te maak van ultrasoniese klank golwe, is 'n tegniek ontwikkel wat 'n direkte visuele aanduiding kon gee van die toestand van membraan-bevuiling binnein die module. 'n Reghoekige aluminium-module, 24 cm lank, is ontwerp en gebou waarbinne die membraan geplaas is vir die skeidingsproses. Resultate dui daarop dat daar 'n uitstekende verband bestaan tussen die afname in permeaatvloei en die ultrasoniese eggo vanaf die membraan. Die ultrasoniese tegniek kon die vorming van en toename in membraan-bevuiling doeltreffend karakteriseer. In teenstelling hiermee, is die tegniek ook suksesvol aangewend om die skoonmaak-proses van membrane te ondersoek. Met min of geen data beskikbaar vir die skoonmaak-proses van membrane in die industriële sektor, het die tegniek enorme potensiaal in die optimisering van bestaande skoonmaak-tegnieke. Die tegniek is verder aangewend op 'n industriële 8-duim deursnee spiraal-module en goeie resultate is verkry. Stagnante sones asook vloed-vloei-patrone binne-in die module kon suksesvol bepaal word. Baie navorsing is egter nog nodig om die ingewikkelde data wat gegenereer word tydens die ondersoek van 'n spiraal-module ten volle te verstaan. Die enorme potensiaal en moontlikhede van die ultrasoniese tegniek kan die begin wees van 'n revolusie in die membraan-industrie.

This work deals with the implementation of support for network identifiers containing national characters in the SProbe software project, which is designed to monitor network flows. It was necessary to test and evaluate the status of selected network applications working over SMTP, POP3, IMAP, FTP or SIP protocols. On the basis of the information obtained, an extension of the current software project SProbe was proposed - a module to support network traffic monitoring with national alphabet characters. The proposed solution was then implemented and the functionality of the entire resulting system was tested. In addition, this work proposes and implements a modification of the test environment for faster and more efficient testing of the system focusing on tests containing diacritics.

The rapid growth of text based information on the World Wide Web and various applications making use of this data motivates the need for efficient and effective methods to identify and separate the “main content” from the additional content items, such as navigation menus, advertisements, design elements or legal disclaimers. Firstly, in this thesis, we study, develop, and evaluate R2L, DANA, DANAg, and AdDANAg, a family of novel algorithms for extracting the main content of web documents. The main concept behind R2L, which also provided the initial idea and motivation for the other three algorithms, is to use well particularities of Right-to-Left languages for obtaining the main content of web pages. As the English character set and the Right-to-Left character set are encoded in different intervals of the Unicode character set, we can efficiently distinguish the Right-to-Left characters from the English ones in an HTML file. This enables the R2L approach to recognize areas of the HTML file with a high density of Right-to-Left characters and a low density of characters from the English character set. Having recognized these areas, R2L can successfully separate only the Right-to-Left characters. The first extension of the R2L, DANA, improves effectiveness of the baseline algorithm by employing an HTML parser in a post processing phase of R2L for extracting the main content from areas with a high density of Right-to-Left characters. DANAg is the second extension of the R2L and generalizes the idea of R2L to render it language independent. AdDANAg, the third extension of R2L, integrates a new preprocessing step to normalize the hyperlink tags. The presented approaches are analyzed under the aspects of efficiency and effectiveness. We compare them to several established main content extraction algorithms and show that we extend the state-of-the-art in terms of both, efficiency and effectiveness. Secondly, automatically extracting the headline of web articles has many applications. We develop and evaluate a content-based and language-independent approach, TitleFinder, for unsupervised extraction of the headline of web articles. The proposed method achieves high performance in terms of effectiveness and efficiency and outperforms approaches operating on structural and visual features<br>Das rasante Wachstum von textbasierten Informationen im World Wide Web und die Vielfalt der Anwendungen, die diese Daten nutzen, macht es notwendig, effiziente und effektive Methoden zu entwickeln, die den Hauptinhalt identifizieren und von den zusätzlichen Inhaltsobjekten wie z.B. Navigations-Menüs, Anzeigen, Design-Elementen oder Haftungsausschlüssen trennen. Zunächst untersuchen, entwickeln und evaluieren wir in dieser Arbeit R2L, DANA, DANAg und AdDANAg, eine Familie von neuartigen Algorithmen zum Extrahieren des Inhalts von Web-Dokumenten. Das grundlegende Konzept hinter R2L, das auch zur Entwicklung der drei weiteren Algorithmen führte, nutzt die Besonderheiten der Rechts-nach-links-Sprachen aus, um den Hauptinhalt von Webseiten zu extrahieren. Da der lateinische Zeichensatz und die Rechts-nach-links-Zeichensätze durch verschiedene Abschnitte des Unicode-Zeichensatzes kodiert werden, lassen sich die Rechts-nach-links-Zeichen leicht von den lateinischen Zeichen in einer HTML-Datei unterscheiden. Das erlaubt dem R2L-Ansatz, Bereiche mit einer hohen Dichte von Rechts-nach-links-Zeichen und wenigen lateinischen Zeichen aus einer HTML-Datei zu erkennen. Aus diesen Bereichen kann dann R2L die Rechts-nach-links-Zeichen extrahieren. Die erste Erweiterung, DANA, verbessert die Wirksamkeit des Baseline-Algorithmus durch die Verwendung eines HTML-Parsers in der Nachbearbeitungsphase des R2L-Algorithmus, um den Inhalt aus Bereichen mit einer hohen Dichte von Rechts-nach-links-Zeichen zu extrahieren. DANAg erweitert den Ansatz des R2L-Algorithmus, so dass eine Sprachunabhängigkeit erreicht wird. Die dritte Erweiterung, AdDANAg, integriert eine neue Vorverarbeitungsschritte, um u.a. die Weblinks zu normalisieren. Die vorgestellten Ansätze werden in Bezug auf Effizienz und Effektivität analysiert. Im Vergleich mit mehreren etablierten Hauptinhalt-Extraktions-Algorithmen zeigen wir, dass sie in diesen Punkten überlegen sind. Darüber hinaus findet die Extraktion der Überschriften aus Web-Artikeln vielfältige Anwendungen. Hierzu entwickeln wir mit TitleFinder einen sich nur auf den Textinhalt beziehenden und sprachabhängigen Ansatz. Das vorgestellte Verfahren ist in Bezug auf Effektivität und Effizienz besser als bekannte Ansätze, die auf strukturellen und visuellen Eigenschaften der HTML-Datei beruhen

Today there is a great need for communication between people and even between things, using systems onboard e.g. aircraft, cars, ships and satellites. As a consequence, these communications needs require antennas mounted on or integrated in the surfaces of different vehicles or platforms, i.e. conformal antennas. In order to ensure proper operation of the communication systems it is important to be able to determine the characteristics of these antennas. This thesis is about the analysis and design of conformal antennas using high frequency asymptotic methods. Commonly used eigenfunction solutions or numerical methods such as FDTD, FEM or MoM are difficult to use for arbitrarily shaped electrically large surfaces. However, the high frequency approximation approach together with an accurate ray tracing procedure offers a convenient solution for these surfaces. The geodesics (ray paths) on the surfaces are key parameters in the analysis and they are discussed in detail. In the first part of the thesis singly and doubly curved perfectly electrical conducting (PEC) surfaces are studied, with respect to the mutual coupling among aperture type elements. A synthesis problem is also considered where the effect of the mutual coupling is taken into account. As expected, the mutual coupling must be included in the synthesis procedure to be able to realize the prescribed pattern, especially in the shaped main lobe. Furthermore, the polarization of the antenna elements is very important when considering antennas on generally shaped surfaces. For such antennas the polarization must most likely be controlled in some way for a proper function. For verification of the results two experimental antennas were built at Ericsson Microwave Systems AB, Mölndal, Sweden. The first antenna is a circular cylinder with an array of rectangular waveguide fed apertures and the second antenna is a doubly curved surface (paraboloid) with circular waveguide fed apertures. It is found that it is possible to obtain very accurate results with the asymptotic method when it is combined with the Method of Moments, i.e. a hybrid method is used. The agreement compared to measurements is good at levels as low as –80 dB in many cases. The second part of the thesis is about the development of a high frequency approximation for surface field calculations on a dielectric covered PEC circular cylinder. When using conformal antennas in practice they have to be covered with a radome for protection and with the method developed here this cover can be included in the analysis. The method is a combination of two different solutions, one valid in the non-paraxial region of the cylinder and the other is valid in the paraxial region. The method is verified against measurements and reference results obtained from a spectral domain moment method code.<br>QC 20100616

[EN] This thesis is focused on the synthesis of new zeolitic structures using phosphorus containing compounds as structure directing agents, and the study of the influence of the presence of phosphorus in the adsorption capacity and acid properties of the zeolites. The phosphazene bases and aminophosphonium cations used in this work have yielded to zeolites with new crystalline structures (ITQ-45, ITQ-52, ITQ-58), as well as have developed new routes of synthesis of already known zeolites, but broadening their range of compositions (DON, RTH, ITE, STF), and these have allowed obtaining the synthetic analogue (ITQ-47) of the natural zeolite boggsite (BOG) by first time.<br>[ES] La presente tesis doctoral se centra en la síntesis de nuevas estructuras zeolíticas empleando como agentes directores de estructura compuestos que contienen fósforo y el estudio de la influencia de la presencia de fósforo en la capacidad de adsorción y en las propiedades ácidas de las zeolitas. Las bases de fosfaceno y cationes aminofosfonio empleados en este trabajo han permitido obtener zeolitas con nuevas estructuras cristalinas (ITQ-45, ITQ-52 e ITQ-58), así como desarrollar nuevas rutas de síntesis de zeolitas conocidas ampliando el rango de composiciones (DON, RTH, ITE, STF) y obtener por primera vez el análogo sintético (ITQ-47) de la zeolita natural boggsita (BOG).<br>[CAT] La present tesi doctoral es centra en la síntesi de noves estructures zeolítiques emprant com agents directors d'estructura compostos que continguen fòsfor, i la influència de la presència de fòsfor en la capacitat d'adsorció i en la fortalesa àcida de les zeolites. Les bases de fosfazè i cations aminofosfoni emprats en aquest treball han permès obtindre zeolites amb noves estructures cristal¿lines (ITQ-45, ITQ-52 e ITQ-58), així com desenvolupar noves rutes de síntesi de zeolites conegudes ampliant el rang de composicions (DON, RTH, ITE, STF) i obtindre per primera vegada l'anàleg sintètic (ITQ-47) de la zeolita natural boggsita (BOG).<br>Simancas Coloma, R. (2015). Síntesis de nuevos materiales zeolíticos empleando agentes directores de estructura fosforados [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/52025<br>TESIS

La clairance des cellules apoptotiques par les macrophages est à l’origine d’un microenvironnement pro-résolutif composé de différents facteurs solubles, permettant de stopper la réaction inflammatoire et d’engager la réparation tissulaire. La résolution de l’inflammation est parfois défaillante et concourt au développement de pathologies inflammatoires chroniques, comme les maladies inflammatoires chroniques de l’intestin (MICI), qui regroupent la maladie de Crohn (MC) et la rectocolite hémorragique (RCH). Dans ce contexte, nous proposons d’évaluer l’efficacité thérapeutique de l’injection de ces facteurs pro-résolutifs dans le traitement des MICI. Ce produit issu de la culture de macrophages avec des cellules apoptotiques, appelé SuperMApo (Supernatant issued from Macrophage Apoptotic cell culture) (Brevet # WO2014106666-A1, 2013) contient des facteurs pro-résolutifs semblables à ce qu’on retrouve dans le processus physiologique de résolution de l’inflammation, et qui peuvent être absents ou inefficaces chez ces patients.Lors de ce travail, nous avons mise en évidence une efficacité thérapeutique de SuperMApo à l’aide de deux modèles expérimentaux de colite. Pour évaluer la pertinence de ces modèles par rapport à la pratique clinique, nous avons mise en place la vidéo-endoscopie souple. On a montré que l’efficacité de SuperMApo se traduit par diminution du score clinique, endoscopique et histologique des souris colitiques, accompagnée d’une amélioration de la perméabilité intestinale, et de la cicatrisation muqueuse. Cette efficacité thérapeutique est liée en partie à une reprogrammation des cellules présentatrices d’antigènes (APC) notamment de cDC et de macrophages qui présentent moins de réponse aux ligands de TLR, favorisent l’induction de Treg et inhibent la production de Th1. Par ailleurs, SuperMApo induit une cicatrisation nette de la muqueuse intestinale associée à la fois à une activation des myofibroblastes (la forme active des fibroblastes) et des cellules intestinales épithéliales (IEC). Concrètement, SuperMApo augmente les propriétés de migration, de prolifération et de cicatrisation de ces deux types cellulaire. Cet effet dépend en partie des facteurs de croissance au sein de SuperMApo comme le TGF-β, l’IGF-I et le VEGF. Finalement des résultats préliminaires montrent que SuperMApo induit un profil réparateur sur des fibroblastes issus de patients atteints de MICI. L’ensemble de ces résultats montrent, que l’injection de ces facteurs pro-résolutifs permet de mettre en œuvre des mécanismes capables de mettre en place un processus de résolution de l’inflammation et ouvre vers une utilisation clinique de cette approche dans le traitement de MICI<br>Inflammation is a natural body defence reaction in response to injuries. The clearance of apoptotic cells by macrophages is at the origin of a pro-resolving microenvironment composed of various soluble factors, allow the arrest of the inflammatory response and to initiate tissue repair. The resolution of inflammation is sometimes defective and contributes to the development of chronic inflammatory diseases, such as chronic inflammatory bowel disease (IBD), which include Crohn's disease (CD) and ulcerative colitis (UC). In this context, we propose to evaluate the therapeutic effect of these pro-resolving factors in the treatment of IBD. This factors derived from the culture of macrophages with apoptotic cells, and called SuperMApo (Supernatant issued from Macrophage Apoptotic cell culture) (Patent # WO2014106666-A1, 2013) contains pro-resolving factors similar to those found in the physiological process of inflammatory resolution, and which may be absent or ineffective in these patients.In this work, we have demonstrated the therapeutic effect of SuperMApo using two experimental models of colitis. To assess the relevance of these models to clinical practice, we have implemented flexible video endoscopy. The therapeutic effect of SuperMApo has been shown to decrease the clinical, endoscopic and histological score of colitis mice, accompanied by improved intestinal permeability and mucosal healing in vivo. This therapeutic effect is related in part to reprogramming of antigen presenting cells (APC), in particular cDC and macrophages, which exhibit less response to TLR ligands, promote induction of Treg and inhibit Th1 production. In addition, SuperMApo induces a marked tissue repair of the intestinal mucosa associated with activation of myofibroblasts, the active form of fibroblasts, and the epithelial intestinal cells (IEC). In particular, SuperMApo increases the migration, proliferation and wound healing properties of these two cell types. This effect depends in part on the growth factors contained in SuperMApo such as TGF-β, IGF-I and VEGF. Finally, preliminary results show that SuperMApo induces a repairing state on fibroblasts from patients with IBD. This opens widely the use of SuperMApo as a clinically approach to propose this new therapeutic option to refractory patients suffering from IBD

En esta tesis se presenta un método para analizar antenas montadas sobre estructuras arbitrarias. La Optica Geométrica (GO) y la Teoría Uniforme de la difraccion (UTD), han sidoempleadas para analizar los efectos que la estructura produce sobre el diagrama de radiación de la antena emisora. Para la descripción geométrica de la estructura, han sido utilizados parches NURBS (Non Uniform Rational B-Spline), por lo que el método presentado, es compatible con la mayoría de los programas gráficos disponibles en el mercado.EL tratamiento de geometrías arbitrarias requiere un código eficiente en el análisis de tres dimensiones.Por otro lado, para obtener resultados satisfactorios, la descripción de la superficie de la estructura, debe ser muy próxima al modelo real, sin embargo, esto complica el tratamiento computacional. Aquí la estructura es modelada mediante un conjunto de parches NURBS, que unidos entre sí, describen el modelo completo. Esta descripción permite manipular superficies arbitrarias con un bajo numero de parches, lo que significa un volumen de información reducido.La descripción inicial por NURBS del modelo, es acompañada con información complemetaria como por ejemplo: la tipología de las superficies, las curvas frontera, el tipo de material, etc. Esto es imprescindible para la aplicación de criterios de selección dedicados a la aceleración del proceso.El método tras leer la descripción del modelo, descompone los parches NURBS en superficies racionales de Bezier. Un parche de Bezier es también una superficie paramétrica definida en términos de una combinación lineal de los polinomios de Bernstein.Las antenas son modeladas usando modelos numéricos simples basados en agrupaciones de dipolos infinitesimales eléctricos y magnéticos. Esta caracterización de la antena es muyventajosa ya que con un numero reducido de datos de entrada, la fuente queda definida para cualquier dirección del espacio y el valor del campo radiado puede ser calculado fácilmente.El análisis electromagnético de los efectos que contribuyen al campo dispersado por la geometría comienza con una selección rigurosa de la geometría iluminada desde la fuente.Unicamente los parches de Bezier iluminados serán almacenados por el ordenador durante el análisis. La filosofía de este proceso es descartar aquella parte de la geometría que no contribuye a los efectos de dispersión.El campo total calculado es la superposición de los siguientes efectos pertenecientes a la GO y a la UTD: campo directo procedente de la fuente, campo reflejado por los parches de Bezier, campo difractado por las aristas del modelo definidas como curvas de Bezier, ondas de superficie, dobles reflexiones, reflexione-difraccion y difraccion-reflexión. El método ha sido diseñado para analizar campo cercano y lejano. El mayor gasto computacional se debe a la búsqueda de los puntos de dispersión, por lo que antes de emplear los algoritmos de intersección es necesario aplicar un conjunto de criterios rápidos dependientes de la dirección de observación.El principio de Fermat en combinación con el Gradiente Conjugado (CGM) es usado para obtener de manera eficiente los puntos de dispersión sobre la estructura. Para cada efecto, laposible ocultación de la trayectoria completa del rayo es examinada, por ello, si el rayo corta alguno de los parches de Bezier su contribución será descartada. Los dobles efectos son tratados como una generalización de los simples efectos.El método desarrollado es eficiente ya que precisa de un numero reducido de superficies para modelar objetos complejos lo que se traduce en bajos requerimientos de memoria y reducidos tiempos de calculo.<br>In this thesis a method to analyze antennas on board of complex bodies is presented. The Geometrical Optics (GO) and Uniform Theory of Diffraction (UTD) have been used to analyze the effect of the structure in the radiation pattern of the antennas. The bodies are geometrically modelled by using NURBS (Non Uniform Rational B-Spline) surfaces. In addition to be accurate and efficient, the method is compatible with most of the modern CAGD (Computer Aided Geometric Design) available programs.The treatment of arbitrary geometries requires a code which can carry out an efficient 3D analysis. To obtain accurate results the description of the surface must be close to the real model, however this complicates the computational procedure. Here the structure is modeled by a collection of individual N.U.R.B.S. surface patches joined to form a complete description of the surface model. The NURBS description is able to manipulate free form surfaces with a low number of patches, and therefore, with a low amount of information. The initial description of the model by NURBS surfaces is accompanied with other complementary data for example : the topology of the surfaces, the boundary curves, the types of material and other inputs. It is very interesting to apply criteria to make the complete analysis faster.The method reads the NURBS description of the model and transforms the NURBS into the rational BEZIER surfaces. A rational BEZIER patch is also a parametric surface defined in terms of a linear combination of Bernstein polynomials.The antennas are modelled using simple numerical models based on arrays of electric and magnetic infinitesimal dipoles. This antenna modelization is very advantageous because with a little input data, the source is defined in any direction and the field value is readily accessible.The electromagnetic analysis of the contributive effects to the scattering field by the geometry, starts with the rigorous selection of the geometry illuminated from the source. Only the Bezier patches illuminated will be in memory of the computer during the analysis. The philosophy of this previous process is to discard in the process the part of the geometry which does not contribute to the scattering effects.The total field is the superposition of the following GO and UTD field components: direct field from the source, reflected fields from the Bezier patches of the model, diffracted fields from the arbitrary edges defined as a Bezier curves, creeping waves, double reflected field and diffracted-reflected and reflected-diffracted fields. The search of specular and diffraction points are the most CPU time consuming, thus before using the intersection algorithms it is necessary to apply a set of fast selection criteria which depend on the observation direction.The Fermat principle in conjunction with the Conjugate Gradient Method (CGM) is used for obtaining efficiently the reflection points and diffraction points on the structure. For each effect the complete ray path is examined to see whether or not it is interrupted by any Bezier patch of the model, in this case the field component is not computed. The double effects are treated using a generalization of the single effects algorithms. The method has been developed to analyze the near and far field cases for different frequencies.The developed method is quite efficient because it makes use of a small number of surfaces to model complex bodies, so it requires few memory and low computing time.

碩士<br>中原大學<br>化學工程研究所<br>101<br>Membrane fouling is unavoidable in a membrane filtration process; fouling caused by recalcitrant gel and cake layers on the membrane always results in a decrease of permeate flux. In recent years, on-line, non-destructive ultrasonic time-domain reflectometry（UTDR）has been applied to membrane fouling, but the analysis is limited to single-point measurement from UTDR to describe the fouling degree for the whole membrane. In this research, the UTDR signals from the block-scanning mode （so called C-mode）are used to investigate membrane fouling in various conditions. Through Hilbert transform on UTDR signals, direct visualization of the membrane fouling distribution is developed. To examine the effectiveness of the operating conditions on membrane fouling, an in-site or UTDR based monitoring technique of membrane fouling is developed. Even if the existing collected data of the measured UTDR signals are rich source of information on the variations affecting the membrane performance, the data are seldom systematically studied to enhance the understanding of the correlation of the measured UTDR signals with the operating conditions. In this research, the texture analysis applied to UTDR images is developed to extract the spatial statistic features of fouling distribution. Because the arrival time and the local magnitude of a UTDR signal are of great importance for proper interaction of ultrasonic signals from non-homogeneous fouling layers, the fouling development is quantified by 2D wavelets from the ultrasonic data. It can obtain information in different scales for the whole membrane. Subsequently, the gray level co-occurrence matrix is used to enrich spatial information; the pixel intensity and the relative position in the texture analysis are used to extract the statistic features of spatial distribution. To build up the automatic fouling monitoring system, the PCA technique of multivariate statistics is applied to statistic features. Obviously, it is more convenient to detect faults using the proposed method than the commonly used visualized approaches. In membrane filtration, fouling and its performance can be affected by different operation conditions. It is difficult for an untrained person to detect the fault source from sensor reading only. In this research, an on-line UTDR based fault diagnosis is also proposed. This diagnosis technique is the combinational method of the clustering method and the decision tree. Clustering is first done by the subtractive clustering method to classify the data. Subsequently, C4.5 decision tree is used to build the diagnosis rules. To verify the effectiveness of the proposed method, the on-line fouling data are measured from the real separation experiments of phospholipids from the canola oil. The results show that the proposed method is capable of detecting the fault and making appropriate adjustment to correct the operating condition.

碩士<br>國立臺灣科技大學<br>電機工程技術研究所<br>85<br>In this thesis, a simulation program is developed to analyze the properties of wave propagations in buildings. Also, a vector network analyzer is used to measure the transmission properties of the building structures so that the constitutive parameters of the building structures can be obtained for doing wave propagation simulations. For the measurements of the constitutive parameters, a free space transmission approach is applied by using different frequencies (0.5-3.0Ghz), incident angles, distances from the wall, locations and polarizations to extract the equivalent complex dielectric constants of the brick wall and reinforced concrete structures. Those walls are modeled as slabs with uniform thickness and homogeneous dielectric properties. On the other hand, the wave propagation simulation program is developed by employing the ray tracing method , heuristic uniform theory of diffraction, and periodic moment method. This program, together with the measured equivalent complex dielectric constants, can be applied to evaluate the characteristics of wave propagations for indoor wireless communications.

abstract: Two commercial blade antennas for aircraft applications are investigated. The computed results are compared with measurements performed in the ASU ElectroMagnetic Anechoic Chamber (EMAC). The antennas are modeled as mounted on a 13-inch diameter circular ground plane, which corresponds to that of the measurements. Two electromagnetic modeling codes are used in this project to model the antennas and predict their radiation and impedance characteristics: FEKO and WIPL-D Pro. A useful tool of WIPL-D Pro, referred to as WIPL-D Pro CAD, has proven to be convenient for modeling complex geometries. The classical wire monopole was also modeled using high-frequency methods, GO and GTD/UTD, mounted on both a rectangular and a circular ground plane. A good agreement between the patterns of this model and FEKO has been obtained. The final versions of the solvers used in this work are FEKO (Suit 6.2), WIPL-D Pro v11 and WIPL-D Pro CAD 2013. Features of the simulation solvers are presented and compared. Simulation results of FEKO and WIPL-D Pro have good agreements with the measurements for radiation and impedance characteristics. WIPL-D Pro has a much higher computational efficiency than FEKO.<br>Dissertation/Thesis<br>M.S. Electrical Engineering 2014