The dissertation thesis deals with a study of an influence of a simultaneous incidence of an additive thermal noise and a multiplicative phase noise on the useful signal transmission in narrowband satellite communication systems. While the additive thermal noise affects the useful signal only on the receiver side of the communication system, the multiplicative phase noise is produced in all system oscillators. One investigates how the receiver filter bandwidth reduction takes effect on the influence of individual noise types. The thesis is divided into four units. The first one (chapters 4 and 5) solves the ways of modeling of both noise types. In the second part (chapter 6), on the simple example, the primary analysis of the phase noise influence is made. Basic modulation schemes used in the satellite communication are also discussed (chapter 7). Third part (chapter 8) is devoted to the modeling of a general digital system with a M PSK modulation made directly on the main carrier wave. The last part (chapter 9) describes the modeling of a digital system with a BPSK modulation on the auxiliary subcarrier wave followed by an SSB modulation on the main carrier wave. General conclusions are deduced from obtained simulation results.

[ES] La presente tesis doctoral tiene como objetivo fundamental desarrollar nuevas estructuras capacitivas de filtrado en guía de ondas rectangular que sean capaces de proporcionar mayores ancho de banda en la banda de paso y, al mismo tiempo, mejorar la respuesta fuera de banda. Estas nuevas estructuras guiadas han sido pensadas para ofrecer nuevas soluciones tecnológicas para los filtros de microondas de alta frecuencia, con una variedad de diferentes funciones de transferencia, abordando específicamente las necesidades de los futuros sistemas de telecomunicaciones para aplicaciones terrestres y espaciales. En este contexto, por lo tanto, discutimos en este documento el estudio, diseño y fabricación de varios tipos de filtros de microondas en guía de ondas rectangular que muestran una mejora significativa con respecto al estado del arte. Las soluciones que discutimos se obtienen introduciendo modificaciones simples en la estructura de los filtros de microondas clásicos. Varias técnicas que emplean iris híbridos, resonadores con salto de impedancia, configuración en escalera y uniones T en plano E con conexiones en cortocircuito o manifold, se utilizan con éxito para cumplir con las exigentes especificaciones de los futuros sistemas para aplicaciones terrestres y espaciales. Además, un desafío actual adicional al que se enfrentan todos los diseñadores de equipos y componentes de microondas es la necesidad de reducir tanto su tamaño físico como su masa (o peso). Para abordar este problema, discutimos en este documento el uso de aperturas resonantes en guías de ondas rectangulares, presentando una nueva familia de filtros que se pueden usar para implementar funciones complejas de transferencia de banda única y banda doble con una reducción significativa de tamaño y masa. En los siguientes capítulos de esta tesis doctoral, cada tema se analiza en detalle, incluyendo las formulaciones teóricas básicas, los procedimientos de diseño, los resultados de las simulaciones electromagnéticas de onda completa, las consideraciones de fabricación y el rendimiento medido de una serie de prototipos. En todos los casos se ha encontrado una excelente concordancia entre las mediciones y las simulaciones realizadas, validando así completamente tanto las estructuras novedosas propuestas como sus procedimientos de diseño. / [CA] La present tesi doctoral té com a objectiu fonamental el desenvolupament de noves estructures capacitives de filtrat en guia d'ones rectangular que siguen capaços de proporcionar major ample de banda en la banda de pas i millorar, al mateix temps, la resposta fora de banda. Aquestes noves estructures guiades han sigut pensades per a oferir noves solucions tecnològiques per a filtres de microones d'alta freqüència, amb una varietat de diferents funcions de transferència, abordant específicament les necessitats dels futurs sistemes de telecomunicacions per a aplicacions terrestres i espacials. En aquest context, per tant, discutim en aquest document l'estudi, disseny i fabricació de diversos tipus de filtres de microones en guia d'ones rectangular que mostren una millora significativa respecte a l'estat de l'art. Les solucions que discutim s'obtenen introduint modificacions simples en l'estructura dels filtres de microones clàssics. Diverses tècniques que fan ús d'iris híbrids, ressonadors amb salt d'impedància, configuració en escala i unions T en plànol E amb connexions en curtcircuit o col·lector, s'utilitzen amb èxit per a complir amb les exigents especificacions dels sistemes futurs per a aplicacions terrestres i espacials. A més, un desafiament actual addicional al qual s'enfronten tots els dissenyadors d'equips i components de microones és la necessitat de reduir tant la seua grandària física com la seua massa (o pes). Per a abordar aquest problema, discutim en aquest document l'ús d'obertures ressonants en guies d'ones rectangulars, presentant una nova família de filtres que es poden usar per a implementar funcions complexes de transferència de banda única i doble banda amb una reducció significativa de grandària i massa. En els següents capítols d'aquesta tesi doctoral, cada tema s'analitza detalladament, incloent les formulacions teòriques bàsiques, els procediments de disseny, els resultats de les simulacions electromagnètiques d'ona completa, les consideracions de fabricació i el rendiment mesurat d'una sèrie de prototips. En tots els casos s'ha trobat una excel·lent concordança entre el mesurament i les simulacions realitzades, validant així completament tant les estructures noves propostes com els seus procediments de disseny. / [EN] The main objective of this doctoral thesis is the development of new capacitive filtering structures in rectangular waveguide that are able to provide wide bandwidths in the pass-band and improve, at the same time, the out-of-band response. These new guided structures have been developed in order to offer new technological solutions for high-frequency microwave filters, with a variety of different transfer functions, addressing specifically the needs of future telecommunication systems for both ground and space applications. In this context, therefore, we discuss in this document the study, design and manufacture of several types of microwave filter in rectangular waveguide that show a significant improvement with respect to the state-of-the-art. The new solutions that we propose are obtained by introducing simple modifications in the structure of classic microwave filters. Several techniques based on hybrid irises, stepped impedance resonators, staircase configuration and E-plane T-junctions with shorted stubs or manifold connections, are successfully used in order to meet the very demanding specifications of future systems for both ground and space applications. Furthermore, an additional current challenge faced by all designers of microwave components is the need to reduce both their physical size and mass (or weight). To address this issue, we discuss in this document the use of resonant apertures in rectangular waveguide, introducing a new family of filters which can be used to implement complex single and dual-band transfer functions with significant size and mass reduction. In the following chapters of this doctoral thesis, each subject is discussed in detail including the basic theoretical formulations, design procedures, the results of full-wave electromagnetic simulations, manufacturing considerations, and the measured performance of a number of prototypes. Excellent agreement is found in all cases between measurement and simulations, thereby fully validating both the novel structures discussed and their design procedures. / Valencia Sullca, JF. (2021). New Wide-Band Capacitive Filter Structures in Rectangular Waveguide Technology With Enhanced Out-of-Band Response [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/180198 / TESIS

This thesis deals with the synthesis and optimization of frequency analogue filters with modern active elements usable for higher frequencies. The thesis is divided into three parts, the first part deals with the problematic concerning Leap-Frog combined ARC structure. Due to a difficult design, this method is not described in a detail and used in practice, although it shows e.g. low sensitivity. Firstly, a complete analysis of individual filters was made (for and T endings) and consequently these findings were used during implementation of this method to NAF program. Finally, samples of real filters were realized (for verification of functioning and correct design). Another very interesting topic concerning filters is usage of coupled band-pass for small bandwidth, where it is necessary to solve the problems concerning ratio of building elements values, but also price, quality, size of coils, sensitivity, Q factors, coefficients etc. That is why in practice a coil is very often substituted with other equivalent lossy and lossless blocks which create ARC filters structure. The design and the possibility of usage of lossy grounded elements were described here (such as synthetic inductors, frequency dependent negative resistor). Some parts of the design are individual computer sensitivity analysis, setting of usage and quality comparison of individual lossy grounded blocks. Besides, a program for these elements was created, it is useful for a quick design and depiction of transfer characteristics. The third part deals with the usage of tuning universal filters consisting three or more operational amplifiers, which secures its universality and possibility to create different kinds of transfer characteristic. In practice, Akerberg - Mossberg and Kerwin - Huelsman - Newcomb are the most used types of filters. These were also compared with less common universal filters. In the end, the possibility of digital tuning of universal filter with the help of digital potentiometers for filters of 10th order and frequency around 1 MHz was shown.

Summaries in English and Afrikkans / The aim of this thesis is to investigate the labour law position of South African farm workers. For three and a half centuries farm workers constituted the most neglected group in the South African labour force. Consequently, an understanding of their present position can only be obtained by investigating their labour history. As in other parts of the world, farm workers in South Africa held a subordinate position to agricultural employers. Discrimination against black persons added to the inferior socio-economic and political position of South African farm workers. White farmers occupied a strong political position during most of the time under investigation, which enabled them to institute and apply discriminatory legislation and informal methods to overcome labour shortages. The freedom of movement of black people and their access to land were restricted to create a cheap immobile labour force. During the 20th century farmers prevented the inclusion of farm workers in labour legislation by exercising their political influence. Pressure by industrial trade unions and encouragement by the International Labour Organisation (ILO) resulted in the adoption of the Agricultural Labour Act which made labour legislation applicable to farm workers, but precluded them from striking and made allowance for longer working hours than for industrial workers. The new political dispensation facilitated the inclusion of farm workers in general labour legislation without any discriminatory exceptions and land reform legislation now protects farm workers against arbitrary evictions. A bill of rights furthermore guarantees the rights of farm workers which were previously violated. It would superficially seem that farm workers' problems are something of the past. Farm workers, however, remain handicapped in exercising their new rights by historical factors and circumstances peculiar to the agricultural sector. Legal comparison with Ontario and California confirms that legislation alone is insufficient to empower farm workers. It is recommended that the government amend existing legislation to accommodate the special needs of farm workers and that relevant ILO conventions, especially Convention 141 of 1975, be ratified to aid the development of unions for farm workers. This will contribute to the empowerment of and social justice for farm workers. / Die doel van hierdie tesis is om die arbeidsregtelike posisie van Suid-Afrikaanse plaaswerkers te ondersoek. Plaaswerkers was vir drie en 'n half eeue die mees afgeskeepte groep in die Suid-Afrikaanse werksmag. Om die huidige posisie van plaaswerkers te begryp is dus slegs moontlik deur 'n bestudering van die regsgeskiedenis van plaaswerkers. Soos in ander werelddele beklee plaaswerkers in Suid-Afrika 'n minderwaardige posisie teenoor landbouwerkgewers. Diskriminasie teenoor swartpersonehet bygedra tot die sosio-ekonomiese en polities minderwaardige posisie van Suid-Afrikaanse plaaswerkers. Blanke boere het gedurende die grootste deel van die tydperk onder bespreking 'n sterk politiese posisie beklee wat hulle in staat gestel het om diskriminerende wetgewing en informele metodes aan te wend om arbeidstekorte te bowe te kom. Swart persone se bewegingsvryheid en toegang tot grond is beperk om 'n goedkoop immobiele werksmag te vorm. Gedurende die 20ste eeu het boere se sterk politiese posisie hulle in staat gestel om te verhoed dat plaaswerkers by arbeidswetgewing ingesluit word. Druk deur industriele vakbonde en aanmoediging deur die Intemasionale Arbeidsorganisasie (IAO) het gelei tot die Wet op Landbou-arbeid waardeur arbeidswetgewing op plaaswerkers van toepassing gemaak is, maar wat plaaswerkers verbied het om te staak en wat voorsiening gemaak het vir langer werkure as vir industriele werkers. 'n Nuwe politieke bedeling het gelei tot die insluiting van plaaswerkers in algemene arbeidswetgewing sonder enige diskriminerende uitsonderings en grondhervormingswetgewing beskerm plaaswerkers nou teen arbitrere uitsettings. 'n Handves van menseregte waarborg verder die regte van plaaswerkers wat voorheen misken is. Oenskynlik is die probleme van plaaswerkers nou iets van die verlede. Plaaswerkers word egter steeds in die uitoefening van hulle nuwe regte gestrem deur historiese faktore en die eiesoortige omstandighede van die landbousektor. Regsvergelyking met Kalifomie en Ontario het aangetoon <lat wetgewing alleen nie voldoende is om plaaswerkers te bemagtig nie. Daar word aanbeveel dat die regering bestaande wetgewing wysig om voorsiening te maak vir die spesiale behoeftes van plaaswerkers en dat relevante IA0 konvensies, veral Konvensie 141 van 197 5 geratifiseer word om die ontwikkeling van vakbonde vir plaaswerkers te bevorder. Dit sal bydra tot die bemagtiging van en tot sosiale geregtigheid vir plaaswerkers / Law / LL.D.

The State of Texas implemented the No Pass-No Play Rule within House Bill 72 in the spring semester of 1985. The addition of this section to the state education code was a part of the state's efforts toward educational reform. The perceived rationale implied in House Bill 72 is that extracurricular activities can inspire student motivation and increase student achievement. The No Pass-No Play Rule seems to imply that there is a relationship between student achievement and extracurricular activities, and further implies that a student can be motivated to achieve by the desire to continue to participate in extracurricular activities. The problem of this study was a comparison of academic achievement for high school pupils involved in extracurricular activities and those who did not participate in extracurricular activities under the Texas No Pass-No Play Rule. The purpose of this study was to determine the impact of extracurricular activities on the academic achievement of high school students, specifically looking at the years 1983 through 1986, when the No Pass-No Play Rule was implemented. This study was an ex post facto study with data obtained from a cooperating Texas school district. Students were matched on critical variables, and their scores on a measure of achievement were analyzed to determine if there was any relationship between extracurricular activities and achievement. Repeated measures of achievement were also analyzed to determine if students involved in extracurricular activities scored differently from those not involved in extracurricular activities over this time period in which the No Pass-No Play Rule was implemented. Results indicated that for those students involved in this study, there was no significant difference on a measure of achievement for students involved in extracurricular activities and those who did not participate. Results also indicated that in the years 1983 through 1986 all students involved in the study declined slightly in their achievement scores, regardless of involvement with extracurricular activities.

The problem of the study was to ascertain the perceptions of high school personnel and students regarding the effectiveness and implementation of the educational reforms and the No-Pass, No-Play section in Texas House Bill 72 and compare them to changes in reported student academic performances. Questionnaires were mailed to a stratified random sample of fifteen high schools in Texas. Six persons were asked to respond at each school. The sample consisted of ninety participants. In addition, each school provided forty student grade profiles, twenty from 1984 and twenty from 1986. The instrument, "Questionnaire on Texas Educational Reform Legislation, Extracurricular Activities and No-Pass, No-Play," had eighteen questions. Questions one and two provided demographic data for the study. Questions three through eighteen assessed the perceptions of high school personnel and students regarding educational reforms and the "No-Pass, No-Play" rules. Hypotheses one through four used chi-square Tests of Independence to determine the significance among variables. Hypothesis five used a t value to measure the comparison of the grade-point averages from 1984 and 1986. Hypothesis six compared the result of hypothesis five and a z value generated from a comparison of a percentage of participant responses and the neutral value. The findings were that of 120 chi-square calculations only ten showed significance for 8.3 percent of the total. There were no significant differences found among the variables regarding the questions asked. There was a significant difference in what study participants thought about students' achievement and the actual differences in the student grade-point averages. A major conclusion was that the participants believed that students were achieving more academically since Texas House Bill 72 and "No-Pass, No-Play." In summary there were six findings, eleven conclusions, seven general recommendations, eight specific recommendations and six recommendations for further study reported as a result of this research.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

The political economy of the exchange rate explains different approaches within the integration process of the European monetary union. The changing character of exchange rate pass-through into the foreign trade prices changes not only the international economy paradigm, but also the attitude to the exchange rate political economy. The study solves the incentives to the different exchange rate arrangement choice during the transformation and integration period in the Central and East European countries. It follows with the analysis of the industry structure in these economies. It discusses the existence of its direct and indirect channel of influencing the exchange rate politics. Article solves the hypothesis of interest group formation in regard to the exchange rate policy (the euro adoption) and the intergovernmental bargaining as well as the bargaining within the economy. The industry analysis results confirm the set hypothesis, in which the heterogenity of industry structure explains the heterogeneous approach to the exchange rate politics during the transformation process in monitored economies. The redistributive change of Hungarian exchange rate policy is discussed in connection with the change of subsidies flow within the political cycle. We discuss the impact of current account adjustment on the tradable and nontradable sector in member countries of currency union -- Euro zone. The current account adjustment associated with the adjustment of the net export's deficit caused by the drop in the domestic absorption evokes the increase in the relative price of the nontradable sector. The paper discusses this hypothesis within framework of the Portuguese current account adjustment, which is the result of European financial integration in catching-up countries. The common monetary policy and common currency cannot offset the negative impact of nontradable price increase within the internal expenditure switching effect and also can not support exporters within the external expenditure effect.. The Portuguese current account adjustment was not followed by the currency depreciation and the tradable price increase. The cost of the currency asymmetric response were born by the tradable mark-up decrease, the falling decrease in nontradable wages and employment and finally by the nontradable mark-up and employment decrease.

In vielen Kommunikationssytemen wird Information durch die zeitliche Struktur von Signalen kodiert. Ein neuronales System, welches rhythmische Signale verarbeitet, sollte davon profitieren, seine inhärenten Filtereigenschaften den Frequenzcharakteristika dieser Signale anzupassen. Die Grille Gryllus bimaculatus stellt ein einfaches biologisches System dar, für welches nur wenige, spezifische Modulationsfrequenzen verhaltensrelevant sind. Ich habe einzelne Neuronen im peripheren und höheren auditorischen System der Grille hinsichtlich einer möglichen Anpassung auf diese Frequenzen untersucht. Hierfür habe ich extrazelluläre Elektrophysiologie mit verschiedenen Stimulationsparadigmen kombiniert, welche auf amplitudenmodulierten Tönen basierten. Die Analyse der experimentellen Daten ergab, dass bereits in der auditorischen Peripherie einige der untersuchten Neurone Bandpasseigenschaften aufwiesen, da sie verhaltensrelevante Modulationsfrequenzen mit den höchsten Feuerraten beantworteten. Anhand einfacher mathematischer Modelle demonstriere ich, wie weitverbreitete, zellintrinsische und netzwerkbasierte Mechanismen die beobachteten Feuerratenresonanzen erklären könnten. Diese Mechanismen umfassen unterschwellige Resonanz von Membranströmen, aktivitätsabhängige Adaptation, sowie das Zusammenwirken von Exzitation und Inhibition. Ich zeige, wie eine serielle Kombination solcher elementarer Filter die deutliche Selektivität im Verhalten der Grille erklären könnte, ohne dabei auf ein dediziertes Filterelement zurückzugreifen. Allgegenwärtige neuronale Mechanismen könnten demnach eine dezentralisierte Filterkaskade in einem hochspezialisierten und größenbeschränkten neuronalen System begründen. / In many communication systems, information is encoded in the temporal pattern of signals. For rhythmic signals that carry information in specific frequency bands, a neuronal system may profit from tuning its inherent filtering properties towards a peak sensitivity in the respective frequency range. The cricket Gryllus bimaculatus is a simple biological system for which only a narrow range of modulation frequencies is behaviorally relevant. I examined individual neurons in the peripheral and higher auditory system for tuning towards specific temporal parameters and modulation frequencies. To this end, I combined extracellular electrophysiology with different stimulation paradigms involving amplitude-modulated sounds. Analysis of the experimental data revealed that—even in the auditory periphery—some of the examined neurons acted as tuned band-pass filters, yielding highest firing-rates for behaviorally relevant modulation frequencies. Using simple computational models, I demonstrate how common, cell-intrinsic or network-based mechanisms could account for the experimentally observed firing-rate resonances. These mechanisms include subthreshold resonances, spike-triggered adaptation, as well as the interplay of excitation and inhibition. I present how a serial combination of such elementary filters could explain the strong selectivity evident in the cricket’s behavior—without the need for a dedicated filter element. Pervasive neuronal mechanisms could therefore constitute an efficient, distributed frequency filter in a highly specialized, size-constrained neuronal system.

Les taux élevés de mortalité et de morbidité associés aux maladies vasculaires en font des pathologies dont les conséquences physiopathologiques, chirurgicales et socio-économiques sont d’une importance majeure pour le système de santé. Malgré leurs avantages, la disponibilité limitée des vaisseaux autologues a conduit au développement de prothèses synthétiques. Cependant, leur surface hautement thrombogène limite leur utilisation dans la substitution des vaisseaux de petit calibre (< 6 mm). De ce fait, à cause de leur obstruction précoce, la reconstitution d’une surface luminale proche de l’endothélium natif est incontournable. Pourtant, les revêtements de surface actuellement disponibles possèdent de médiocres qualités de rétention des néo-endothélium lorsqu’ils sont soumis à des contraintes de cisaillement physiologiques. Dans ce travail, nous proposons un substitut vasculaire de petit calibre endothélialisé réalisé à partir de trois éléments : 1) une matrice préparée à partir d’une artère ombilicale désendothélialisée, 2) un recouvrement de surface innovant constitué du film multicouche de polyélectrolytes (MPE) (PAH-PSS)3-PAH, et 3) un néo-endothélium constitué de cellules endothéliales matures ou progénitrices. Les études in vitro menées sur ces substituts ont montré que la formation, la rétention sous contraintes de cisaillement et la fonctionnalité du néoendothélium élaboré sur la surface luminale étaient améliorées par le film MPE. L’implantation du substitut par pontage termino-latéral sur le lapin a montré que le cahier des charges imputé aux substituts de petit calibre était rempli, principalement en termes de perméabilité et de diamètre, mais aussi de résistance à la suture et aux infections. En conclusion, le film MPE favorise le développement d’un substitut vasculaire de petit diamètre perméable à « long » terme et qui pourrait répondre aux exigences des chirurgiens / Vascular diseases with their high rate of mortality and morbidity belong to the pathologies involving important socio-economic factors for health system. Despite the advantages of autografts, the limited availability of autologous vessels has led to the development of synthetic prostheses. However, their high thrombogenic surface limits their use as small calibre vascular substitutes (< 6 mm). To prevent narrowing of small diameter vascular grafts, the reconstruction of a luminal surface close to the native endothelium is essential. However, the retention of the neo-endothelium subjected to shear stress is poor on the coatings currently available. In this work, we developed a small calibre endothelialized vascular substitute thanks to three elements: 1) a natural matrix prepared from umbilical artery, 2) an innovative coating based on the polyelectrolytes multilayer film (PEM) (PAH-PSS)3-PAH, and 3) used for cell culture of mature or progenitor endothelial cells. In vitro studies have shown that the formation, the retention under shear stress and the endothelial function of the neoendothelium on the luminal surface were improved by PEM film. The anastomosis of this substitute on rabbits has shown that the specifications essential to small calibre vascular grafts were reached, mainly in terms of permeability and diameter but also of resistance to suture and infections. In conclusion, PEM films helped us to develop a small diameter vascular substitute with long term patency