Siga este link para ver outros tipos de publicações sobre o tema: Satcom.
Teses / dissertações sobre o tema "Satcom"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 50 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Satcom".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja as teses / dissertações das mais diversas áreas científicas e compile uma bibliografia correta.
1
Bushnell, Christopher J. "U.S. Navy SHF SATCOM : past, present and future". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283704.
Texto completo da fonteResumo:
Thesis (M.S. in Systems Technology (Command, Control, and Communications)) Naval Postgraduate School, June 1994.Thesis advisor(s): Dan C. Boger, Carl R. Jones. "June 1994." Bibliography: p. 137-141. Also available online.
2
Rodrigues, Tiago Giglio, Luis Carlos Sandoval Góes, Nelson Paiva Oliveira Leite e Carlos Nazareth Motta Marins. "FLIGHT TESTS OPTIMIZATION BY SATCOM BASED TELEMETRY LINK". International Foundation for Telemetering, 2005. http://hdl.handle.net/10150/604803.
Texto completo da fonteResumo:
ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, NevadaThe terrestrial microwave telemetry links show limitation due their inherent features concerning bandwidth availability, frequency allocation and range. Also it supports only one aircraft per test and the data acquisition capacity can be enhanced. Following the flight tests trends, it proposes a telemetry link based on satellite communications deployed by off the shelf equipments allowing advantages as bandwidth availability, multiple aircrafts telemetry and almost global range into the reliability standards. By simple equations and typical flight tests data it demonstrates the feasibility of the telemetry system proposed for time and costs reduction to optimize flight tests programs.
3
Hellberg, Joakim, e Axel Sundkvist. "Comparing Control Strategies fora Satcom on the Move Antenna". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279331.
Texto completo da fonteResumo:
Satellite communication is a widely known method for communicating with remote or disaster-strickenplaces. Sometimes, thecommunication can be a matter of life and death,and it is thus vital that it works well. For two-way communication (such as internet) it is necessary for the antenna on Earth to point towards the satellite with a pointing error not larger than a few tenths of a degree. For example, regulations decided by the authorities in the U.S. forbid pointing errors larger than 0.5°. In some cases the antenna on Earth has to be moving while satellite communication is maintained. Such cases can be when the antenna is mounted to a vehicle, and the antenna thus has to compensate for the vehicle’s movement in order to point at the satellite. This application of satellite communication is called Satcom on the Move (SOTM). By constructing a Simulink model of an entire SOTM-system, including vehicle dynamics, satellite position, signal behavior, sensors, and actuators, different control strategies can be compared. This thesis compares the performance of an H2- and an LQG-controller for a static initial acquisition case, and a dynamic inertial stabilization case. The static initial acquisition case is performed with a search algorithm (SpiralSearch) aiming to find the satellite signalin the shortest possible time for a given initial pointing error. The dynamic inertial stabilization case is performed by allowing the simulated vehicle to drive in a slalom pattern and over uneven grounds. The controllers are designed based on modern control theory.The conclusion of this thesis is that the H2-controller performs slightly better in the static testcase,whereastheLQG-controller performs slightly better in the dynamic test cases. However, the results are greatly influenced by the tuning of the controllers, meaning that the comparison is not necessarily true for the controllers rather than the tuning parameters.Satellitkommunikation är en allmänt känd metod för att kommunicera med avlägsna eller katastrofdrabbade platser. Ibland kan kommunikationen vara en fråga om liv och död, och det är därför viktigt att den fungerar bra. För tvåvägskommunikation (som internet) är det nödvändigt att antennen på jorden pekar mot satelliten med ett pekfel som inte är större än några tiondels grader. Exempelvis finns det lagar i USA som förbjuder pekfel större än 0,5°. I vissa fall måste antennen på jorden röra sig medan satellitkommunikation upprätthålls. Sådana fall kan vara när antennen är monterad på ett fordon och antennen således måste kompensera för fordonets rörelse för att peka mot satelliten. Denna applikation av satellitkommunikation kallas Satcom on the Move(SOTM). Genom att konstruera en simulinkmodell av ett fullständigt SOTM-system, inklusive fordonsdynamik, satellitposition, signalbeteende, sensorer och ställdon, kan olika reglerstrategier jämföras. Denna avhandling jämför en H2 - och en LQG-regulator för ett statiskt fall, samt ett dynamiskt fall. Det statiska fallet utförs med en sökalgoritm (spiralsökning) som syftar till att hitta en specifik satellitsignal på kortast möjliga tid för ett givet initialt pekfel. Det dynamiska fallet utförs genom att låta det simulerade fordonet köra i slalommönster och på ojämnt underlag. Regulatorerna är designade baserade på modern kontrollteori. Slutsatsen av denna avhandling är att H2-regulatorn presterar något bättre i det statiska testfallet, medan LQG-regulatorn presterar något bättre i de dynamiska testfallen. Resultaten påverkas emellertid kraftigt av de designade reglerparametrarna, vilket innebär att jämförelsen inte nödvändigtvis är sann för kontrollerna, utan snarare förde specifika reglerparametrarna.
4
Powers, Darin L. "Required performance parameters for Naval use of commercial wideband SATCOM". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA354467.
Texto completo da fonteResumo:
Thesis (M.S. in Space Systems Operations) Naval Postgraduate School, September. 1998."September 1998." Thesis advisor(s): R. Jones, Dan C. Boger. Includes bibliographical references (p. 179-181). Also available online.
5
Hayhurst, Kyle. "DOA Estimation of Ground Based Signals Using Airborne SATCOM Antennas". The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1284566671.
Texto completo da fonte
6
Tauran, Bastien. "On the interaction between transport protocols and link-layer reliability schemes for satellite mobile services". Thesis, Toulouse, ISAE, 2018. http://www.theses.fr/2018ESAE0035/document.
Texto completo da fonteResumo:
L'accès à Internet par satellite permet de connecter des régions isolées de la terre ou des utilisateurs en mouvement, pour lesquels une solution terrestre peut s’avérer couteuse voire impossible. L’utilisation de constellations de satellite en orbite basse permet de transmettre avec des délais similaires à ceux des transmissions terrestres, permettant l’utilisation des protocoles de transport classiques comme TCP. L’utilisation d’un tel environnement engendre cependant des contraintes spécifiques à ce type de réseau, comme des délais de transmission variables et un important taux d’erreur, principalement lors de la traversée de l’atmosphère. Pour compenser ces forts taux de pertes, des mécanismes de fiabilisation doivent être introduit au niveau des couche basse. Ces mécanismes ont toutefois un impact négatif sur les performances des protocoles de transport, notamment TCP, limitant grandement le débit. Le but de cette thèse est de comprendre dans un premier temps les interactions entre les mécanismes de fiabilisation et les protocoles de transport, pour ensuite proposer des solutions permettant d’améliorer la qualité des transmissionsLEO satellite constellations allow to connect isolated or mobile users to the Internet, when terrestrial solutions are too expensive or impossible to deploy. Using such constellations allow to connect these areas with transmission delays close to terrestrial delays, and then to use the classic transport protocols such as TCP. However, this environment brings new impairments such as variable delays and important error rate between the satellite and the ground receiver. To counteract this high error rate, reliability schemes are introduced on the link between the satellite and the ground user. However, these schemes have a negative impact on the transport protocol (TCP), mitigating the throughput, and which has not been deeply studied yet. In this thesis, we first understand the impact of the reliability schemes on the transport layer, and then propose solutions to improve the efficiency of the transmissions
7
Fox, Michael Ethan. "The viability of shaped BPSK modulation techniques with 5kHz UHF SATCOM channels". Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/144644.
Texto completo da fonteResumo:
A method of generating constant envelope BPSK compatible modulation formats is described in which spectral containment is achieved via controlled phase rotations. These Shaped BPSK modulations can be considered BPSK/CPM hybrids. The instantaneous phase transitions of BPSK are tempered to become the continuous phase rotations of CPM. The SBPSK modulations described above are compared with classical BPSK as well as a Shaped BPSK modulation specified by the Joint Chiefs of Staff for use with Department of Defense 5kHz UHF SATCOM channels. It is shown that the use of SBPSK modulations can allow significant increases in the data transmission rate without exceeding the spectral "envelope" of a lower rate BPSK signal. Analysis also includes fractional out of band power curves for the modulated signals before and after transmission through a bandpass hard-limited channel. Equivalent SNR's are generated to quantify the simultaneous effects of decreased adjacent channel interference at the expense of I channel energy. Finally, probability of error curves vs SNR are presented for BPSK and SBPSK modulations transmitted through a band-limited and hard-limited channel.
8
McLaughlin, Robert D. "Leveraging an SNMP agent in terminal equipment for network monitoring of U. S. Navy SATCOM". Thesis, Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/5563.
Texto completo da fonteResumo:
Approved for public release; distribution is unlimited.This research describes and analyzes a United States Navy Satellite Communications (SATCOM) performance monitoring model in providing status information to a network monitoring console to support naval operations. The environment is characterized by potentially adverse conditions that affect satellite performance. Current SATCOM systems are unable to provide performance information to the network's performance monitor because they are not Simple Network Management Protocol (SNMP) enabled and not integrated into the routable network. A network monitoring model defined by sense, decide, and act is central to this study. It represents enhanced monitoring by the subscriber station's monitor console for naval shipboard operations. This model delivers operational and RF environmental information to the SNMP MIB environment so that commonly used SNMP agents can request and send information for sending proper messages to the network's performance monitoring system. The proposed solution is explored through analysis of existing monitoring models together with observations of a tactical networking field experiment, in which equipment at the edge of the network and subscriber's SATCOM terminal is monitored for gathering critical performance details.
9
De, Montera Louis. "Etude de la variabilité micro-échelle des précipitations : Application à la propagation des ondes millimétriques en SATCOM". Phd thesis, Université de Versailles-Saint Quentin en Yvelines, 2008. http://tel.archives-ouvertes.fr/tel-00384050.
Texto completo da fonteResumo:
Aux fréquences de la bande EHF (20-50 GHz), les gaz, les nuages et surtout la pluie provoquent un affaiblissement du signal entre les stations de télécommunication terrestres et les satellites. Les séries temporelles d'affaiblissement présentent des caractéristiques particulières, tel que des périodes de grande variabilité (hétéroscédasticité) et des queues de distributions épaisses. Leur comportement statistique est similaire à certains cours de bourse ou taux de change, ce qui suggère que des modèles de prédiction originellement développés pour des applications financières pourraient être appropriés. L'analyse statistique des séries temporelles d'affaiblissement conduit à un modèle non-linéaire de type ARIMA-GARCH. Ce modèle permet d'obtenir de meilleures performances de prédiction que les modèles existants, notamment grâce à l'estimation de la variance conditionnelle de l'erreur de prédiction.Afin de prédire l'affaiblissement sur la liaison montante à partir de celui sur la liaison descendante qui opère à une fréquence différente, un modèle de similitude en fréquence a été ajouté au modèle de prédiction. La séparation des effets (gaz, nuage, pluie) est réalisée par un réseau de neurones, puis chaque composante est transposée à la fréquence voulue grâce à des coefficients de similitude spécifiques. L'incertitude sur ces coefficients de similitude implique une gestion combinée des erreurs de prédiction et des erreurs dues à la similitude.
Le modèle de prédiction avec similitude en fréquence a été développé avec des mesures de l'affaiblissement des balises 20/30 GHz du satellite OLYMPUS et est ensuite testé avec des données récentes de l'expérience SYRACUSE3 20/44 GHz. Les premiers résultats de cette expérience concernant les statistiques à long terme de l'affaiblissement sont ensuite présentés et comparés aux modèles standard de l'ITU.
Afin de mieux comprendre le lien entre l'affaiblissement et ses causes physiques, une approche basée sur les propriétés multifractales de la pluie est ensuite présentée. En effet, l'analogie entre la pluie et la finance peut être étendue, car ces deux phénomènes sont liés à des processus turbulents et possèdent des propriétés d'invariance d'échelle intéressantes. Malheureusement, l'analyse multifractale directe des séries temporelles d'affaiblissement ne donne pas de résultats satisfaisants. L'analyse multifractale est donc appliquée dans un premier temps à des séries temporelles de taux de pluie. Une évaluation de l'effet de l'intermittence pluie-non pluie sur l'analyse multifractale montre qu'elle provoque une cassure des relations d'invariance d'échelle et peut biaiser considérablement l'estimation des paramètres. L'analyse multifractale est alors réalisée évènement par évènement, c'est-à-dire avec des séries temporelles ininterrompues. Les résultats montrent que la pluie peut être modélisée par un FIF (Fractionally Integrated Flux) auquel on applique un seuil afin de reproduire l'intermittence pluie-non pluie.
La modélisation multifractale de la pluie est ensuite utilisée afin de simuler une liaison Terre-Satellite et de générer des séries synthétiques d'affaiblissement par la pluie. L'analyse de ces séries simulées permet de mieux comprendre pourquoi l'affaiblissement est difficile à modéliser. En particulier, bien que le champ pluie soit multifractal, les séries temporelles d'affaiblissement ne présentent pas de propriétés d'invariance d'échelle stables et peuvent même présenter un redressement du spectre de puissance aux hautes fréquences. Ces résultats montrent que le redressement du spectre observé empiriquement n'est pas dû uniquement au bruit de scintillation.
10
Marsh, Eric Allen. "Inertially stabilized platforms for SATCOM on-the-move applications : a hybrid open/closed-loop antenna pointing strategy". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45259.
Texto completo da fonteResumo:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008.Includes bibliographical references (p. 213-216).
The increasing need for timely information in any environment has led to the development of mobile SATCOM terminals. SATCOM terminals seeking to achieve high data-rate communications require inertial antenna pointing to within fractions of a degree. The base motion of the antenna platform complicates the pointing problem and must be accounted for in mobile SATCOM applications. Antenna Positioner Systems (APSs) provide Inertially Stabilized Platforms (ISPs) for accurate antenna pointing and may operate in either an open or closed-loop fashion. Closed-loop antenna pointing strategies provide greater inertial pointing accuracies but typically come at the expense of more complex and costly systems. This thesis defines a nominal two-axis APS used on an EHF SATCOM terminal on a 707 aircraft. The nominal APS seeks to accomplish mobile SATCOM using the simplest possible system; therefore, the system incorporates no hardware specific to closed-loop pointing. This thesis demonstrates that the nominal APS may achieve accurate antenna pointing for an airborne SATCOM application using a hybrid open/closed-loop pointing strategy. The nominal APS implements the hybrid pointing strategy by employing an open-loop pedestal feedback controller in conjunction with a step-tracking procedure. The open-loop feedback controller is developed using optimal control techniques, and the pointing performance of the controller with the nominal APS is determined through simulation. This thesis develops closed-loop step-tracking algorithms to compensate for open-loop pointing errors.
(cont.) The pointing performance of several step-tracking algorithms is examined in both spatial pull-in and tracking simulations in order to determine the feasibility of employing hybrid pointing strategies on mobile SATCOM terminals. Keywords: Mobile SATCOM, Antenna Pointing, Inertially Stabilized Platform, Two-axis Positioner, Linear Quadratic Gaussian Control, Nonlinear Optimization.
by Eric Allen Marsh.
S.M.
11
de, Montera Louis. "Etude de la variabilité micro-échelle des précipitations : application à la propagation des ondes millimétriques en SATCOM". Versailles-St Quentin en Yvelines, 2008. http://www.theses.fr/2008VERS0021.
Texto completo da fonteResumo:
Les séries d’affaiblissement sur les liaisons Terre-satellite présentent un comportement similaire à certains cours de bourse, ce qui suggère que des modèles de prédiction développés en finance pourraient être appropriés. L'analyse statistique des séries temporelles d'affaiblissement conduit à un modèle ARIMA-GARCH. De plus, un modèle de similitude en fréquence est ajouté au modèle de prédiction. Une approche basée sur les propriétés multifractales de la pluie est ensuite présentée. Une évaluation de l'effet de l'intermittence pluie-non pluie montre qu’elle provoque une cassure des relations d'invariance d'échelle et peut biaiser considérablement les paramètres. L'analyse multifractale est alors réalisée évènement par évènement. Les résultats montrent que la pluie peut être modélisée par un FIF (Fractionally Integrated Flux) auquel on applique un seuil afin de reproduire l'intermittence pluie-non pluieAttenuation time series at EHF band exhibit characteristics similar to some stock exchange rates, which suggests that prediction models originally developed in the finance field might be appropriate. The analysis leads to a non linear ARIMA/GARCH model. In order to predict the uplink attenuation from the downlink attenuation that operates at a different frequency, a frequency scaling model has been added to the prediction model. In order to better understand the link between attenuation and its physical causes, an approach based on rain fractal properties is then presented. An assessment of the effect of rain-no rain intermittency on the multifractal analysis shows that it provokes a break in the scaling and may lead to biased parameters. The multifractal analysis is then performed event by event, i. E. With uninterrupted rain periods. The results show that rain can be modeled by a FIF (Fractionally Integrated Flux) which is threholded in order to simulate rain-no rain intermittency
12
Pham, Trung-Kien. "Étude et conception de réseaux transmetteurs reconfigurables en bande Ka". Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S065.
Texto completo da fonteResumo:
Dans les systèmes de communication et de détection sans fil, l'antenne est un élément indispensable pour transformer l'énergie électrique en ondes électromagnétiques rayonnée dans l'espace, et vice versa. Les antennes sont utilisées dans de nombreux dispositifs militaires et civils, tels que les radars (SAR, secteur automobile, détection de débris, etc.), les instruments biomédicaux, les systèmes de télécommunication (téléphones mobiles, stations de base) pour les communications point à multi-point ou point à point par exemple. Les antennes jouent aussi un rôle essentiel pour le développement de futurs réseaux connectés reliant plusieurs appareils à des utilisateurs en temps réel, par exemple pour l'Internet des objets (IoT). Les réseaux transmetteurs sont une solution attrayante pour de nombreuses applications telles que les communications par satellite (Satcom) ou les futurs réseaux 5G. L'architecture des antennes à réseau transmetteur les rend extrêmement compétitifs comparés aux réseaux phasés par exemple grâce à leur alimentation par onde d’espace et car ils ne souffrent pas du blocage induit par la source primaire, comme c’est le cas pour les réseaux réflecteurs ou les antennes à réflecteur. Grâce à leur fonctionnement en mode transmission, les réseaux transmetteurs peuvent être également facilement montés sur des plates-formes mobiles.Les applications Satcom en bande Ka constituent le secteur applicatif majeur de cette thèse. Cette bande fournit un débit de données élevé à la fois pour les liaisons descendantes et les liaisons montantes, en remplacement des systèmes actuels en bande Ku. Dans ce contexte, il convient aussi de prêter une attention particulière aux communications avec des plates-formes mobiles, par exemple les trains à grande vitesse, les avions, etc., ce qui nécessite de mettre au point des antennes à balayage de faisceau. De nombreuses propriétés avancées sont exploitées depuis ces dernières années pour accroître les débits et la flexibilité des systèmes de communication sans fil, par exemple la polarisation circulaire, la double polarisation, le fonctionnement multi-fréquence ou large bande, le dépointage électronique de faisceau. Pour réduire les coûts, des preuves de concept de réseaux transmetteurs non diélectriques sont également proposées. Cette thèse s’est déroulée dans le cadre du projet ANR TRANSMIL (Reconfigurable TRANSmitarrays for beam steering and beam forming at MILlimetre wave). Les objectifs de cette thèse sont de proposer de nouvelles architectures de réseaux transmetteurs fonctionnant en bande Ka en liaison descendante (de 17,7 GHz à 21,2 GHz) et en liaison montante (de 27,5 GHz à 31 GHz). Différents prototypes ont été conçus et fabriqués afin de valider les concepts proposés en bande X et en bande Ka. Un bon accord entre les résultats numériques et mesurés a été obtenu systématiquement. En particulier, les réseaux transmetteurs à double polarisation que nous avons conçus en bande X présentent un gain de 25 dBi et une bande passante à 3 dB de 20% à 10 GHz. Ces propriétés sont indépendantes de la polarisation du champ rayonné, ce qui signifie que des faisceaux de polarisation linéaire orthogonale peuvent être rayonnés indépendamment dans des directions différentes. Un réseau transmetteur bi-bande fonctionnant en bande Ka a également été mis au point. Sa bande passante à 3 dB est de 10% autour des fréquences centrales (19,5 GHz et 29 GHz) et son efficacité de rayonnement atteint 60%. D’autres concepts ont également été étudiés (réseaux transmetteurs sans diélectrique, réseau transmetteur reconfigurable)Transmitarray is an attractive solution for front-end devices in the next generation of communications (5G). The spatial-fed architecture of transmitarray antennas can compete with phase-arrays due to the absence of feeding network and with reflectarrays since they do not suffer from feed blockage. Thanks to their operation in transmission mode, transmitarrays can be easily mounted on platforms for outdoor environment applications. With mature printed-circuit board technology, there are unstoppable experiments in various frequency bands from cm-wave to mm-wave and up to terahertz in upcoming years for potential applications. Many advanced properties are exploited in transmitarrays in recent years to meet high demands of communications facilities, for example, circular-polarization, dual-/multi-polarization or frequencies through many techniques. Some experiments are consid-ered to validate eligibility of this antenna type in commercial services or military missions, namely electronically steering beam, broad bandwidth, etc. In terms of cost reduction and rigidity, non-dielectric prototypes are also proposed. The Ka-band Satcom applications are the main objective of this thesis through trans-mitarray solution. This band provides high data rate for both down-link and up-link in replacement of the current Ku-band systems with miniaturized module in next dec-ades. Hence, it is worth to pay attention to communications for moving platforms, for example, high-speed trains, planes, etc
13
François, Mathieu. "Conception pour la fabrication additive, par fusion laser sur lit de poudre, de composants hyperfrequences". Thesis, Paris, HESAM, 2020. http://www.theses.fr/2020HESAE008.
Texto completo da fonteResumo:
Pendant de nombreuses années, les composants passifs hyperfréquences ont été utilisés dans des systèmes de communication notamment pour des chaînes d'alimentation d'antenne. Ce type d'équipement radiofréquence est déjà largement opérationnel dans différents domaines tels que les communications satellite, les radars, les observations spatiales etc. en raison de leurs avantages de faibles pertes ainsi que de leur capacité élevée de gestion d'énergie. Seulement, avec l'émergence de nouvelles technologies et une concurrence considérable sur le marché de la défense, les clients sont de plus en plus demandeurs de produits de moins en moins coûteux avec des délais d’obtention toujours plus courts, avec des exigences liées aux performances toutes aussi élevées.Ces dernières années, plusieurs institutions et industries se sont intéressées de plus en plus aux procédés de fabrication additive pour les composants à propagation guidée. Ne nécessitant pas de brut de matière ni d'outillage dédié, les technologies additives apportent de nouvelles perspectives de conception. En particulier, l'ajout de matière couche par couche autorise la fabrication de pièces monolithiques, qui permettraient d'alléger les équipements et de réaliser des économies de temps et de coûts. D'autre part, l'une des plus grandes promesses de la fabrication additive réside dans les degrés de liberté supplémentaires qu'elle offre en conception, permettant de concevoir des architectures complexes et innovantes aux performances accrues, qui seraient irréalisables par des techniques conventionnelles. A ce titre, la fabrication additive a été identifiée comme pouvant jouer un rôle crucial dans le développement de ce type de pièce.Cependant, comme tout procédé de fabrication, les procédés additifs possèdent leurs propres spécificités et contraintes liées aux phénomènes physiques mis en jeu au cours de la fabrication et dont il est nécessaire de tenir compte au cours de la phase de conception pour tirer pleinement profit des avantages qu'ils offrent. Ajoutées aux exigences hyperfréquences, le concepteur doit alors être en capacité d'identifier les liens qui existent entre les domaines de la conception, du procédé et électromagnétique pour garantir une pièce de qualité conforme au cahier des charges.L'objectif de ces travaux de thèse est double. Le premier consiste à identifier les spécificités du procédé de fusion laser sur lit de poudre qui influent majoritairement sur les performances électromagnétiques, de manière à y apporter une attention particulière en phase de conception. Le second porte sur l'élaboration d'une méthode qui intègre les contraintes et opportunités de la fabrication additive tout en répondant aux objectifs, globaux et locaux, issus du cahier des charges hyperfréquences de manière à fabriquer des composants opérationnelsFor many years, passive microwave waveguide components have been used in communication systems, particularly for antenna feed chains. This kind of radiofrequency equipment is already widely operational in various fields such as satellite communications, radars, space observations, etc. Because of their low loss as well as their high energy management capacity. However, the emergence of new technologies and the significant degree of competition that occurs within the defense market, customers are increasingly calling for lower-cost products, shorter lead times, with requirements equally high.Over the past years, several institutions and industries have become more and more interested in additive manufacturing processes for passive waveguide components. Without any need for raw material or dedicated tools, additive technologies bring some new design perspectives. In particular, the addition of material layer by layer promotes the manufacture of monolithic parts, which would contribute to lighten the weight of antennas and save time and costs. On the other hand, it offers additional degrees of freedom during the design stage, encouraging the development of complex and innovative architectures, resulting in increased performance, which would be unachievable by conventional techniques. As such, additive manufacturing has been identified as being able to play a crucial role in the development of this type of part.However, like any other manufacturing process, additive processes involve several physical phenomena and so have their own manufacturing specificities and constraints to consider during the design phase to benefit fully from all the potential of additive manufacturing. Combined with the microwave requirements, the designer must then be able to identify the correlation between design, process and electromagnetic to guarantee a quality part conforming to the specifications.The objective of this study is twofold. The first one consists of identifying the specificities of the laser beam melting process with a major influence on electromagnetic properties, in order to be able to pay special attention during the design phase. The second concerns the development of a method that incorporates the constraints and opportunities of additive manufacturing while meeting the objectives arising from the microwave specifications
14
Meyers, Tom. "UTILIZATION OF FIELD PROGRAMMABLE GATE ARRAYS AND DIGITAL SIGNAL PROCESSING MICROPROCESSORS IN AN ADVANCED PC TT&C SATCOM SYSTEM". International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/606819.
Texto completo da fonteResumo:
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, NevadaL-3 Communications Telemetry & Instrumentation (L-3 T&I) has developed an advanced IBM PC-AT Telemetry, Tracking, and Commanding (TT&C) SATCOM system based on the utilization of Field Programmable Gate Array / Digital Signal Processing (FPGA/DSP) microprocessors. This system includes up-link, down-link, and range processing sections. Physically, the system consists of one IF Transceiver and two or more FPGA/DSP microprocessor boards called Advanced Processing Microprocessors (APMs). The form factor of these PWBs is compliant with full length, full height IBM PC PCI bus cards. This paper describes the features and functionality of an advanced Telemetry, Tracking, and Commanding Processing System (TT&CPS) based on the implementation of FPGA and DSP microprocessors. The high-level functional attributes of the TT&CPS are depicted in Figure 1. There are four main functional blocks: the IF Transceiver, the Down-Link Processing Section, the Up-Link Processing Section, and the Range Processor. The analog/IF circuitry in the IF Transceiver card interfaces between the 68–72 MHz (70 MHz, nominal) IF I/O signals and the Up-Link and Down-Link Processing Section's DSP equipment. The down-link portion of the IF Transceiver card has two user-selected input ports. From the selected input, the signal is processed through selectable bandwidth limiting, gain control, Doppler correction (optional), quadrature down-conversion to zero hertz (baseband), selectable baseband filtering, and precision Analog-to-Digital (A/D) conversion. The up-link portion of the IF Transceiver card takes I/Q digital data from the APM performing the up-link processing functions. This baseband I/Q digital data is Digital-to-Analog (D/A) converted, filtered, quadrature up-converted to 68–72 MHz, up-link Doppler corrected (optional), output level detected and level controlled, and sent to a two-position output selector switch. The down-link portion of the TT&CPS provides main carrier linear PM or BPSK or QPSK demodulation and can also, in composite linear PM demodulation mode, receive and demodulate FSK and/or BPSK subcarriers and ranging signals. The demodulators use symbol timing loops and bit decision circuits (matched filters) to perform the bit synchronization function. Several decoding algorithms, including differential, de-interleaving, Viterbi, and Reed-Solomon, are available for the down-link telemetry. Command format checking and CRC status is also available on FSK-demodulated data. Direct carrier BPSK/QPSK demodulation has decoding and frame synchronization capabilities. Because of the modular construction of the firmware and the use of FPGAs and DSPs, the system can be loaded with only the functions in use, lowering initial setup time while increasing overall system capability. To support a particular function, the card is downloaded with an “image,” which programs the FPGAs and DSPs at initialization. The user can change configurations by simply downloading a new set of instructions to the FPGA/DSP on the fly to keep the ground station running with minimal downtime. The flexibility of the design minimizes spare board costs, while achieving greater programmability at the end-user location.
15
Lomotey, Charles. "Strategies to Recover from Satellite Communication Failures". ScholarWorks, 2019. https://scholarworks.waldenu.edu/dissertations/7032.
Texto completo da fonteResumo:
In natural and manmade disasters, inadequate strategies to recover from satellite communication (SATCOM) failures can affect the ability of humanitarian organizations to provide timely assistance to the affected populations. This single case study explored strategies used by network administrators (NAs) to recover from SATCOM failures in humanitarian operations. The study population were NAs in Asia, the Middle East, Central Africa, East Africa, and West Africa. Data were collected from semistructured interviews with 9 NAs and an analysis of network statistics for their locations. The resource-based view was used as the conceptual framework for the study. Using inductive analysis, 3 themes emerged from coding and triangulation: redundancy of equipment, knowledge transfer, and the use of spare parts to service the SATCOM infrastructure. The findings showed that the organization's use of knowledge, and collaboration among NAs and nontechnical staff improved the organization's ability to recover from SATCOM failures. The implication of this study for social change was the reduced cost of satellite services due to the efficient use of the bandwidth. These savings can be channeled into the purchase of vaccines, shelter, and the improvement in the quality of water and sanitation for displaced persons in humanitarian disasters, which improve the organization's delivery of humanitarian services to the affected populations in the disaster.
16
Hoferek, Jakub. "Modelování a simulace příjímače komunikačního systému pro bezpilotní letadla". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377116.
Texto completo da fonte
17
Diaby, Fatimata. "Réseaux transmetteurs reconfigurables pour le dépointage et la formation de faisceau en bande millimétrique". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT125/document.
Texto completo da fonteResumo:
De nos jours, les antennes à réseaux transmetteurs attirent un grand intérêt pour de nombreuses applications civiles et militaires aux bandes de fréquence comprises entre 10 et 110 GHz (réseaux de communication 5G, liens point à point, radars, etc.).Le travail de thèse vise à faire des innovations dans la modélisation et la conception d'antennes à réseaux transmetteurs pour des applications en bande Ka (28-40 GHz). Il porte plus précisément sur le développement d'outils numériques pour l’analyse théorique des réseaux transmetteurs, la conception et la démonstration de plusieurs prototypes avec des fonctionnalités avancées, telles que des réseaux transmetteurs passifs (larges bandes ou à multifaisceaux) et actifs (à reconfiguration électronique).La première partie des travaux consiste en une analyse théorique des réseaux transmetteurs. Dans un premier temps, l’impact de la méthode de compensation de phase sur les performances des réseaux transmetteurs est étudié. La loi de compensation de phase de l’onde quasi-sphérique incidente sur l’ouverture du réseau transmetteur est calculée en utilisant deux méthodes nommées compensation à phase constante et compensation par ligne à retard, et nous montrons que cette dernière permet d’augmenter la bande passante du réseau transmetteur et de corriger les erreurs de dépointage du faisceau. Dans un second temps, le principe de fonctionnement des réseaux transmetteurs facettés est décrit en détail. La simulation numérique du réseau transmetteur à trois facettes est validée au travers de simulations électromagnétiques 3-D. Pour un certain angle d’inclinaison, nous montrons que la bande passante et la capacité de dépointage du réseau transmetteur sont améliorées au détriment du gain.La suite des travaux porte sur la conception et le prototypage de deux réseaux transmetteurs passifs, dont l’un à faisceau collimaté et très large bande et l’autre à quatre faisceaux fixes. Les deux réseaux transmetteurs sont basés sur une cellule élémentaire à 3bits qui assure une double fonction à savoir la compensation de phase et la conversion de la polarisation linéaire en circulaire. Le réseau passif à faisceau collimaté présente un gain mesuré de 33,8 dBi (correspondant à une efficacité d'ouverture de 51,2%) et une bande passante à -3 dB supérieure à 15,9%. La distribution de phase du réseau transmetteur à quatre faisceaux a été optimisée par un algorithme génétique afin d’avoir des faisceaux dépointés à ± 25° dans le plan horizontal et le plan vertical à la fréquence d’optimisation.La dernière partie des travaux vise la conception d’un réseau transmetteur reconfigurable à 27-31 GHz. Dans un premier temps, une cellule élémentaire active à quatre états de phase (2 bits) en polarisation linéaire a été conçue et validée expérimentalement. Elle est composée de six couches métalliques imprimées sur trois substrats. Les éléments rayonnants sont des antennes patch rectangulaires comprenant chacun deux diodes PIN pour contrôler la phase de transmission. Le principe de fonctionnement de la cellule élémentaire a été validé expérimentalement avec des pertes d’insertion minimales de 1.6-2,1 dB et une bande passante en transmission (à 3 dB) de 10-12,1% pour les quatre états de phase 0 °, 90°, 180° et 270°. Cette cellule a ensuite été utilisée pour la conception d’un réseau transmetteur reconfigurable comprenant 14 × 14 cellules unitaires et 784 diodes PIN. Un prototype a été réalisé et caractérisé, il présente un gain maximum mesuré de 19,8 dBi, correspondant à une efficacité d'ouverture de 23,5%, et une bande passante à 3 dB de 4,7 GHz (26,2-30,9 GHz). Malgré quelques éléments défaillants, ce prototype valide le principe de fonctionnement et la faisabilité de réseaux transmetteurs en bande Ka avec une quantification de phase de 2 bits et constitue une des premières réalisations de ce type dans l’état de l’art actuelNowadays, transmitarray antennas are of great interest for many civil and military applications in frequency bands between 10 and 110 GHz (5G mobile networks, point-to-point communication systems, radars, etc.).This thesis aims to make major innovations in modeling and design of transmitarray antennas for Ka-band applications (28-40 GHz). It focuses on the development of numerical tools, and the design and demonstration of several prototypes with advanced functionalities, such as passive (broadband or multibeam) and active (at electronic reconfiguration) transmitarrays.The first part of the work consists of a theoretical analysis of the transmitarray antenna. In a first step, the impact of the phase compensation method on the performance of the transmitarray is studied. The phase compensation law of the quasi-spherical wave incident on the array aperture is calculated using two methods called constant phase compensation and true-time delay (TTD) compensation. The numerical results show that TTD compensation allows an increase of the transmitarrays bandwidth and a reduction of the beam squint as compared to constant phase-shift compensation. In a second step, the operating principle of facetted transmitarrays is described in detail. The numerical simulation of a 3-facet transmitarray is validated through 3-D electromagnetic simulations. For a certain facet angle, the bandwidth and the beam scanning capability of the TA are improved at the expense of the gain.The next step of the work concerns the design and prototyping of two passive transmitarray antennas, one with a collimated and a large bandwidth, and the other with four fixed beams. The two transmitarrays are based on a 3-bit unit-cell providing two functions, namely the phase compensation and the polarization conversion from linear to circular. The passive beam-collimated transmitarray exhibits a measured gain of 33.8 dBi (corresponding to an aperture efficiency of 51.2%) and a 3-dB gain-bandwidth larger than 15.9%. The quad-beam transmitarray phase distribution has been optimized by a genetic algorithm code coupled with an analytical tool. The array is designed to radiate four beams at ±25° in the horizontal and vertical planes at the optimization frequency.The last part of the work aims to the design of a 27-31 GHz reconfigurable transmitarray antenna. Initially, an active unit-cell with four phase states (2 bits) in linear polarization was designed and validated experimentally. It consists of six metal layers printed on three substrates. The radiating elements are rectangular patch antennas, each of them including two PIN diodes to control the transmission phase. The operating principle of the unit-cell has been experimentally validated with a minimum insertion loss of 1.6-2.1 dB and a 3-dB transmission bandwidth of 10-12.1% for the four phase states. 0°, 90°, 180° and 270°.Then, this unit-cell was used for the design of a reconfigurable transmitarray antenna comprising 14 × 14 unit cells and 784 PIN diodes. A prototype was realized and characterized, it presents a measured maximum gain of 19.8 dBi, corresponding to an aperture efficiency of 23.5%, and a 3-dB bandwidth of 4.7 GHz (26.2% at 30.9 GHz). Despite some faulty elements, this prototype validates the operating principle and the feasibility of Ka-band transmitarray antennas with a 2-bit phase quantization. It is one of the first demonstration of such an antenna in the current state of the art
18
Zhang, Tao. "Mise en œuvre de structure FSS pour la conception de filtre et de duplexeur en ondes millimétriques (80GHz) et pour le découplage du réseau d’antennes SATCOM". Paris 10, 2014. http://www.theses.fr/2014PA100021.
Texto completo da fonteResumo:
Un des challenges dans la conception des circuits électroniques et des structures en hyperfréquence est la miniaturisation. Afin d'avoir une meilleure intégration dans les systèmes de communications et d’avoir une meilleure performance, des circuits ou des structures à très bas profil sont nécessaires. Le coût de fabrication est aussi un facteur important. Depuis les années récentes, les matériaux composites (métamatériaux) sont largement étudiés dans la conception des circuits électroniques et les structures en hyperfréquence pour l’objet de réduire leurs dimensions et de diminuer leurs coûts de fabrication. Par exemple, les fabricants des avions ont intérêt d’améliorer leurs systèmes de communication avionique en intégrant les métamatériaux. Les fournisseurs de télécommunications ont l’intention de révolutionner leurs produits en utilisant mes métamatériaux. Depuis les années 1960s, les surfaces sélectives en fréquence (FSS) ont été étudiées pour la conception des filtres et des radômes dans le domaine de RF et micro-ondes. Actuellement, elles sont aussi utilisées pour constituer les surfaces à haute impédance (HIS) et les structures à bande interdite (EEG) etc. Dans le domaine de télécommunication, la communication de point à point à très haut débit (Gigabit rate) s’étend en bande E (ondes millimétriques). Le développement des dispositifs dans cette gamme de fréquence a besoin d’une précision spécifique et d’une compacité importante. Dans cette étude, nous proposons une méthode de conception de filtre et de duplexeur utilisant les FSS. Des filtres FSS et un FSS duplexeur WRl2 (bande E) ont été conçus. Ces filtres et ce duplexeur peut servir à concevoir un système performant et ultra-compact pour le système de communication de point à point de la prochaine génération (Gigabit rate radio link). Une isolation de 80 dB a été réalisée entre les deux canaux du duplexeur. Un autre enjeu est la miniaturisation du système de communication avion/satellite. Les réseaux d'antenne SATCOM actuelles présentent toute une protubérance importante par rapport à la paroi de l’avion. Un réseau d'antenne plate et compacte est idéal pour intégrer sur le fuselage de |‘avion. Due à la surface limitée du fuselage, l’interférence entre l'antenne d’émission et l’antenne de réception devient importante. Le découplage entre les réseaux d’antennes SATCOM est donc devenu un sujet considérable dans la conception de réseaux d‘antenne. Dans cette étude, nous proposons d'utiliser les FSS pour élaborer un réseau d’antenne SATCOM compact, et ainsi que pour le découpage entre les réseaux d’antennes SATCOM (bande Ku). Un réseau d’antenne ultra-thin a été conçu utilisant les FSS comme plan de masse afin d’intégrer sur le fuselage de l'avion. Une étude de découplage entre réseaux d’antennes a été aussi effectuée, a donné un résultat remarquableOne of the challenges in the design of electronic circuits and microwave structures is miniaturization. In order to have a better integration in communication systems and to have a better performance, very low profile circuits and microwave structures are needed. The manufacturing cost is also an important factor. Since recent years, composite materials (Metamaterial) are widely studied for the design electronic circuits and microwave structures for the purpose of reducing their size and their manufacturing costs. For example, aircraft manufacturers are interested in improving their avionic communication systems by integrating metamaterials. Telecommunication equipment providers have intentions to revolutionize their products using Metamaterials. Since the l960s, the frequency selective surfaces (FSS) were studied for the design of the filters and radomes etc. In the field of RF and microwave. Currently, they are also used to design the high impedance surfaces (HIS) and electromagnetic Bandgap structures (ESG) etc. Ln the field of telecommunications, ultra high speed point to point communication system (Gigabit rate) extends to E-band frequency range (millimeter wave). The development of devices in this frequency range needs a specific precision and very high compactness. Ln this study, we propose a FSS filter and duplexer design method. The FSS filters and FSS duplexer WR12 (band E) were designed and measured. These filters and duplexer can be used to develop an efficient and ultra compact communication system for the next generation point to point communication system (Gigabit rate radio link). An isolation of 80 dB was achieved between the two channels of the diplexer. Another issue is the miniaturization of aircraft / satellite communication system. The current SATCOM antenna arrays exhibit substantial protrusion on the aircraft. A flat, compact antenna system is ideal for the integration on the aircraft fuselage. Due to the limited surface of aircraft body, the interference between the transmitting antenna and the receiving antenna becomes larger. The decoupling between the SATCOM antenna arrays has become a major issue in the design of antenna arrays. In this study, we propose the use of FSS structure to design a compact SATCOM antenna array, as well as the decoupling between SATCOM antenna arrays (Ku band). An ultra -thin antenna array was designed using the FSS ground plane for integrating on the aircraft fuselage. A study of decoupling of antenna arrays has been carried out, and gave a remarkable result
19
Harrell, Steven B. "Design of a Super High Frequency (SHF) Extremely High Frequency (EHF) Satellite Communications (SATCOM) Terminal (SEST) for New Construction Naval Surface Ships using the systems engineering process". Master's thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-02162010-020314/.
Texto completo da fonte
20
Ferrando, Rocher Miguel. "Gap Waveguide Array Antennas and Corporate-Feed Networks for mm-Wave band Applications". Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/115933.
Texto completo da fonteResumo:
[ES] Esta tesis aborda temas de especial interés en el diseño de antenas en la banda de milimétricas. Hui en dia, implementar components passius per a operar en la banda de mil·limètriques i assegurar el contacte i l'alineament metàl·lic apropiat entre peces, resulta un desafiament complex. Habitualment les línies de transmissió i les guies d'ones metàl·liques són les solucions adoptades, però en el primer cas es presenten pèrdues al ser solucions impreses i en el segon cas un mal contacte metàl·lic comporta fugues de camp. Per tant, s'estan explorant nous conceptes que solucionen estos problemes.
La tecnología Gap Waveguide (GW) resulta adecuada ya que no requiere de contactos metálicos. En los últimos años han surgido las agrupaciones de antenas basadas en la tecnología Gap Waveguide y son un candidato prometedor para satisfacer algunas de las necesidades mencionadas. La tecnología GW ha demostrado ser atractiva para dispositivos de milimétricas porque permite redes de distribución completamente metálicas de una manera más simple que las guías de onda convencionales. Por tanto, estas redes tienen muy bajas pérdidas pero además son simples de fabricar. Esto es posible gracias a la capacidad de las GW de confinar de forma segura la propagación de ondas electromagnéticas por medio de una estructura que no requiere de contacto.
Durante la última década, se han hecho avances importantes en la tecnología GW y en la literatura se pueden encontrar un buen número de antenas basadas en GW. Esta tesis va un paso más allá en la contribución de este tipo de antenas. Aquí, no solo se presentan antenas con polarización lineal, como suelen ser las desarrolladas hasta ahora, sino también con polarización dual, circular y duales en banda. Estas aportaciones son especialmente atractivas dentro del campo de las comunicaciones por satélite en movimiento (SATCOM on-the-move). Además, se han explorado nuevas redes de distribución que permiten antenas planas más compactas, más ligeras.[CAT] Esta tesi aborda temes d'especial interés en el disseny d'antenes en la banda de mil.limètriques. Hui en dia, implementar components passius per a operar en longituds d'onda tan xicotetes (de l'orde de mil.límetres) i assegurar el contacte i l'alineament metàl-lic apropiat entre peces, resulta un desafiament complex. Habitualment les línies de transmissió i les guia d'ones metàl.liques són les solucions adoptades, però en el primer cas es presenten pèrdues al ser solucions impreses i en el segon cas un mal contacte metàl.lic comporta fugues de camp. Per tant, s'estan explorant nous conceptes que solucionen estos problemes. La tecnologia Gap Waveguide (GW) resulta adequada ja que no requerix de contactes metàl.lics. En els últims anys han sorgit les agrupacions d'antena basades en la tecnologia Gap Waveguide i són un candidat prometedor per a satisfer algunes de les necessitats mencionades. La tecnologia GW ha demostrat ser atractiva per a dispositius de banda d'ones mil-limètriques perquè permet xarxes de distribució completament metàl-liques d'una manera més simple que les guies d'onda convencionals. Per tant estes xarxes tenen baixes pèrdues peró, a més, són simples de fabricar. Açò és possible gràcies a la capacitat de les GW de confinar de forma segura la propagació d'ones electromagnètiques per mitjà d'una estructura que no requerix de contacte. Durant l'última dècada, s'han fet avanços importants en la tecnologia GW i en la literatura es poden trobar un bon nombre d'antenes basades en GW. Esta tesi va un pas més enllà en la contribució d'este tipus d'antenes. Ací, no sols es presenten antenes amb polarització lineal com solen ser les desenrotllades fins ara, sinó també antenes amb polarització dual, circular i inclús antenes duals en banda. Estes aportacions són especialment atractives dins del camp de les comunicacions per satèl.lit en moviment (SATCOM on-the-move). A més també s'han explorat noves xarxes de distribució que permeten obtindre antenes planes més compactes, més lleugeres.
[EN] This thesis deals with topics of special interest regarding the design of antennas at the mm-wave band. Today, implementing passive components that operate in the mm-wave band and to ensure the appropriate metallic contact is challenging. Commonly, conventional planar transmission lines and hollow metallic waveguides are the usual solutions but they present high losses or they do not ensure a good metallic contact. So, new concepts must be explored. Gap Waveguides (GWs), result suitably since they do not require metallic contact for shielding. Antenna arrays in Gap Waveguide Technology (GW) emerges as one promising candidate to naturally meet some of the mentioned needs. GW technology has demonstrated to be effective for mm-wave band devices because it enables full-metal distribution networks in a much simpler way than conventional waveguides. Very low distribution losses can be achieved preserving at the same time the assembly simplicity of multilayer microstrip feeding networks. This unique feature is a consequence of gap waveguides ability to safely confine the electromagnetic wave propagation through a contactless structure. During the last decade, there have been important advances in GW technology and a good number of gap waveguide-based arrays can be found in the literature. This thesis goes a step further in the contribution to mm-wave gap waveguide antennas. Here, antennas with linear polarization as well as circular or dual polarization are proposed. Dual band antennas has also been explored. These contributions have been carried out with a focus on satellite communications on-the-move. In addition, new distribution networks have also been explored to obtain more compact, low-profile and lighter antennas.
Ferrando Rocher, M. (2018). Gap Waveguide Array Antennas and Corporate-Feed Networks for mm-Wave band Applications [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/115933
TESIS
21
Broussard, Elliot. "Commande innovante d’une nouvelle génération d’antenne satellite mobile". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI090.
Texto completo da fonteResumo:
Les systèmes de communication prennent de nos jours une importance de plus en plus prépondérante dans tous les aspects de la vie courante et les exigences de connectivité se retrouvent dorénavant dans de très nombreux projets. Ces besoins de connexion exigent des débits de communication ainsi que des taux de couverture de plus en plus importants, poussant de ce fait vers l’utilisation de systèmes de communication par satellite (SATCOM). Les applications envisagées n’étant pas limitées à des installations fixes, celles-ci demandent de pouvoir assurer une communication par satellite depuis un porteur en mouvement. Il est donc nécessaire d’utiliser des servomécanismes de positionnement de l’antenne de façon à assurer un pointage correct de l’antenne vers le satellite. Ces positionneurs sont donc asservis de façon à orienter la ligne de visée de l’antenne vers le satellite, avec une erreur angulaire de l’ordre du dixième de degré. Cette précision a pour conséquences certaines exigences fortes sur la conception. Ces contraintes imposent l’utilisation de composants de qualité supérieure, des études mécaniques poussées ainsi que des réglages propres à chaque positionneur après assemblage. Dans le cadre de ces travaux de thèse, une stratégie de pointage différente de l’état de l’art a été conçue. Cette stratégie, nommée Helios (Hybrid Estimator of Line Of Sight), permet de lever certains verrous scientifiques spécifiques. Notamment, elle permet une diminution des performances requises de l’asservissement en position de l’antenne en fournissant une trajectoire plus facile à suivre. Cela permet une diminution des contraintes de conception, notamment mécaniques (frottements, raideurs …). Cela est rendu possible par une meilleure estimation de la direction à pointer, utilisant un plus grand nombre de mesures, sans introduire de retard dans l’estimation. Les moyens d’essais de Thales ont permis d’effectuer des essais expérimentaux sur des prototypes industriels. Ainsi, la stratégie est testée en simulation et en expérimentation sur un hexapode simulant un porteur, permettant un recalage du modèle de simulation à partir de données expérimentales. C’est ainsi que la stratégie est validée en conditions opérationnelles. Afin de réaliser ces tests expérimentaux, une étape de mise en place du moyen d’essais a été réalisée. Notamment, les outils de communication ont été mis au point (bus de terrains, liaisons série …). L’asservissement en position de la station a été réalisé à partir d’une identification non-paramétrique en boucle fermée du mécanisme. L’intégration de la station complète a été réalisée, permettant ainsi les tests en extérieur, sur un hexapodeIn military and civil application, satellite communications (SACTOM) are often needed on moving vehicles (drones, planes, land vehicles, vessels…) in order to transfer all kind of data (pictures, videos, internet …). These types of stations are called SATCOM On The Move (SOTM). In order insure high data rates, the antenna must be directional, which means that they direct electro-magnetic waves in a particular direction of space, called line of sight. The line of sight must be steered in order to be aligned with the satellite to insure a strong communication link with the highest data rate possible. Stabilized platforms, called Antenna Positioning System, aim to steer the antenna’s line of sight in the satellite direction. The pointing requirements are the source of conception constraints that reduce the cost efficiency of the overall station. This PhD report focus on the development and the study of a new pointing strategy called Helios (“Hybrid Estimator of LIne Of Sight”). This algorithm uses least squares to found the antenna pattern in real time, using an observation window. Among others, it allows to reduce the bandwidth of the control loops by generating a trajectory easier to follow. Therefore, it decreases the conception constraints (friction, backlash, field bus data rate …). Helios is tested through experimentation, using Thales industrial prototypes. The vehicle is emulated by a hexapod. Simulation is carried out in order to fit the measured experimental behavior. To do so, parametrical and non-parametrical identification has been done on the SOTM prototype. This way, Helios is validated and studied in operational conditions
22
Bäckström, Hampus. "Design and Evaluation of V/UHF Satellite Communication Antennas for Naval Applications". Thesis, KTH, Elektroteknisk teori och konstruktion, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231844.
Texto completo da fonteResumo:
In this master thesis, compact antenna design aimed towards naval applicationshave been designed, analyzed and evaluated. There is a recentinterest in the development of compact antennas to be used for smallersubmarine models, and with a smaller hull on a submarine, communicationand antenna systems must be adapted and minimized, which limitsantenna design. With two limiting cylindrical volumes with maximumallowed dimensions r = 10 cm, h = 50 cm and r = 5 cm, h = 90 cm,the antennas would operate on the upper to lower V/UHF band, radiatehemispherically and have a high RHCP purity. It was found that the mostappropriate antenna structure for both volumes was QHA design. Afterthe design and analysis process was completed, it was concluded that theshorter antenna design could meet all requirements set while the longerantenna design did not meet all requirements but could still establish agood communication link on the higher frequencies. Antenna prototypesbased on the produced design were constructed and measured and, despiteminor deviations, veried that the results obtained from this thesis werereliable.I denna mastersuppsatsen har kompakta antenner riktade mot marinaapplikationer designats, analyserats och utvarderats. Det nns ett intressefor utvecklingen av kompakta antenner som ska anvandas for mindreubatsmodeller och med ett mindre skrov pa en ubat maste kommunikationsochantennsystemen anpassas och minimeras darefter, vilket begransarantenndesignen. Med tva begransande cylindriska volymer med maximalttillatna dimensioner r = 10 cm, h = 50 cm samt r = 5 cm,h = 90 cm, skulle antennerna verka pa det ovre till lagre V/UHF-bandet,strala hemisfariskt och ha en hog RHCP-renhet. Det konstaterades attden lampligaste antennstrukturen for bada volymen var QHA-design. Efteratt design- och analysprocessen slutforts drogs slutsatsen att den kortareantenndesignen kunde uppfylla alla krav som stalldes medan den langreantenndesignen inte uppfyllde alla krav men fortfarande kunde upprattaen bra kommunikationslank pa de hogre frekvenserna. Antennprototyperbaserade pa de framtagna designerna konstruerades och mattes och, trotsmindre avvikelser, verierade att de erhallna resultaten fran denna avhandlingvar tillforlitliga.
23
Ogilvie, Timothy Bryan. "A Novel Unit Cell Antenna For Highly Integrated Phased Arrays in the SHF Band". DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1051.
Texto completo da fonteResumo:
Phased arrays are electromagnetic antenna systems comprised of many radiating elements and processing electronics. Radiating elements are typically positioned in an orderly grid within the antenna aperture. In the receive mode of operation, radiating elements capture some of the signal energy from incoming radiation and guide these signals to processing electronics. Signals are filtered and amplified to maintain the desired sensitivity and complexly weighted using circuits with reconfigurable amplification gain and phase delay. Finally, all signals are combined. The summation of these complexly weighted spatial samples forms a spatial filter in the same way complexly weighted temporal samples establish a temporal filter in a finite impulse response discrete-time filter. Therefore, a phased array behaves like a spatial filter that strongly favors signals arriving from a specific direction. This favored direction represents the look angle of its beam, and the shape of the beam directly relates to the complex weights applied to the signals in the array. Analogous to the flexibility offered by digital filters, phased arrays enable agile beam steering, sidelobe control, and multiple independent beams. These capabilities have revolutionized radar, radioastronomy, and communication systems.
Phased arrays have increasingly employed printed circuit board (PCB) fabrication techniques and processes to maximize array channel density, achieve lower profile, and minimize component integration cost. A few applications which leverage these qualities include low-cost radar, mobile satellite communication (SATCOM), and intelligence, surveillance, and reconnaissance (ISR). Further, PCB-based arrays readily accommodate advancements in highly integrated beamforming radio frequency integrated circuits (RFICs), multi-chip modules, and RF micro-electro-mechanical system (MEMS) device technologies.
On a prior effort, an integrated unit cell design was developed for a PCB-based SATCOM array application. However, the design failed to meet the requirements. The primary objective of this work is to demonstrate an improved design using systematic microwave design techniques and modern analysis tools to meet the requirements for the same application. The proposed design must improve gain, bandwidth, size, and manufacturability over the prior design. Additionally, the design must be generally extensible to phased array implementations across the SHF band (3-30 GHz).
This work discusses the advantages of phased arrays over continuous apertures (e.g. reflectors), reviews phased array theory, and proposes an improved unit cell design. The proposed design is 35% smaller than a dime and consists of an orthogonally-fed, slot-coupled stacked patch antenna and dual-stage branchline coupler implemented in a multilayer PCB. Within the operating band from 10.7 to 14.5 GHz, the design achieves an average return loss of 15 dB, a uniform radiation pattern with peak realized gain of 4.8 to 7.0 dBic, cross-polarization level below -17 dB, and stable performance in a closely-spaced array. When configured in an array, the design supports X/Ku-band SATCOM in full-duplex operation, electronically rotatable polarization, and a 47.5˚ grating lobe free conical scan range. Further, a Monte Carlo analysis proves the design accommodates tolerances of material properties and manufacturing processes, overcoming a major challenge in PCB-based high frequency antenna design.
24
Joseforsky, David C., e Gilbert O. Garcia. "Transformational communications architecture for the Unit Operations Center (UOC), Common Aviation Command and Control System (CAC2S), and Command and Control On-the-Move Network, Digital Over-the-Horizon Relay (CoNDOR)". Thesis, Monterey California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1586.
Texto completo da fonteResumo:
Approved for public release, distribution is unlimitedThe purpose of this research was to introduce a Transformational Communications Architecture for the Unit Operations Center (UOC); Common Aviation Command and Control System (CAC2S); and Command and Control On-the- Move Network, Digital Over-the-Horizon Relay (CoNDOR). The methodology used was to conduct Field Tests with government contractors and private vendors in order to demonstrate the capabilities of each wireless technology researched. These wireless technologies, Free Space Optics (FSO), Microwave, 802.16, 802.11b over SecNet-11, Orthogonal Frequency Division Multiplexing (OFDM), Broadband Satellite, INMARSAT, and Iridium, all have the potential of being implemented in the transformational communications architecture for intra-nodal and inter-nodal links for UOC and CAC2S, as well as the CoNDOR communications architecture. The ultimate goal of this research was to introduce different technologies that offer more flexibility, mobility, and capability at the tactical level giving the Marine Corps the tactical wireless edge. Throughout this research, the focus revolved around testing equipment and network configurations in an IP network. Special consideration was given to wireless issues for the UOC, CAC2S, and CoNDOR, which could improve line-of-sight, beyond line-of-sight, and over-the-horizon communications for each program. These new technologies will transform communications in the United States Marine Corps for the 21st century.
Captain, United States Marine Corps
25
Solano, Callie M. "Satchmo". ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/td/1578.
Texto completo da fonte
26
Battikh, Arij. "Développement d’une tête de réception numérique innovante pour réception de télécommunications par satellite en Bande X". Thesis, Limoges, 2020. http://www.theses.fr/2020LIMO0012.
Texto completo da fonteResumo:
Cette thèse réexamine l’architecture des récepteurs de station sol de télécommunications par satellites (SATCOM) en mettant en oeuvre des briques technologiques innovantes de sous-échantillonnage / numérisation RF et de duplexeur de polarisation numérique (DOMT). Un démonstrateur fonctionnant en Bande X a été étudié et conçu à partir de ces briques technologiques. Le sous-échantillonnage des signaux RF est réalisé grâce à la technologie Track and Hold Amplifier (THA) qui permet d’échantillonner des signaux dont la bande passante couvre plusieurs GHz (DC-13 GHz dans le cadre de ce travail). Une étude expérimentale a été menée pour comparer les performances en termes de dynamiques, de taux de distorsion harmonique et de facteur de bruit d’un THA avec celles d’un mélangeur équivalent. La numérisation du signal FI image basse fréquence du signal RF sous-échantillonné est ensuite assurée par un Convertisseur Analogique Numérique (CAN) haute vitesse. Le DOMT réalisé comporte une jonction tourniquet purement analogique qui permet de canaliser les signaux polarisés reçus. L’unité de traitement numérique du signal du DOMT permet de recombiner les signaux polarisés orthogonalement à partir d’un calibrage numérique. Le fonctionnement en bande X de ce concept innovant de tête de réception numérique est démontré, d’une part, théoriquement à partir d’un modèle mathématique et expérimentalement d’autre part, à travers les caractérisations du démonstrateur conçu. Les résultats obtenus en simulation comme en mesure permettent de valider le concept et d’obtenir un couplage de polarisation croisée de l’ordre de 40dB en bande XThis thesis reconsiders the architecture of ground station receivers of satellite communications (SATCOM) thanks to the implementation of innovative technological components: theRF sub-sampling/digitization and the digital polarization duplexer (DOMT). A demonstrator operating at X-Band has been studied and designed from these technologies. The sub-sampling of the RF signals is performed using Track and Hold Amplifier (THA) technology which allows sampling signals whose bandwidth covers several GHz (DC-13 GHz in the context of this work). An experimental study has been conducted to compare the performances of a THA with those of an equivalent mixer in terms of dynamics, harmonic distortions and noise factor. The digitization of the IF signals, low frequency image of the sub-sampled RF signal, is then ensured by a high-speed Digital Analog Converter (ADC). The realized DOMT is based on the use of a purely analog turnstile junction which separates the polarized received signals. The DOMT digital signal processing unit allows recombination of orthogonally polarized signals from a digital calibration. The proper functioning of this innovative digital RF front-end concept is demonstrated at X band, theoretically from a mathematical model on the one hand and experimentally on the other hand, thanks to the characterizations of the designed demonstrator. The obtained results in both simulation and measurement validate the concept and allows obtaining a cross-polarization coupling around 40dB at X band
27
Giesa, Aaron. "SATOR / AREPO / TENET / OPERA / ROTAS". PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3035.
Texto completo da fonteResumo:
This collection represents work produced between September of 2014 and April of 2016. These are poems about structure. Or about difference. Or about love. Or they are an attempt to decipher what it can feel like in 2016, in the lonelinesses and in the solidarities that emerge in the apparent collapse of utopian possibility, in the efforts at its reconstruction, and in the search for the next rupture.
28
Nunes, Pancho. "Les opérations de PMI-sation : pratique ou stratégie ?" Grenoble 2, 1991. http://www.theses.fr/1991GRE21023.
Texto completo da fonteResumo:
Partant de la constatation que, dans le contexte actuel de bouleversements organisationnels, la mobilisation de lza forme pme joue un role fortement accru, la recherche explore l'utilite et la validite du concept de pmisation pour la gestion strategique. Adoptant une perspective strategique, la these propose un panorama complet et coherent de l'ensemble des formes de pmisation selon 3 logiques : (1) la repulsion : la filialisation, l'extrapreneuriat, la faire faire, la reconversion et l'elatement, (2) la captation: croissance interne externe, grapees, sous-traitance et reseaux federes, (3) les reseaux centres mis en place par une firme qui s'erige en noyau central d'un ensemble de pme satellites. A partir d'un cadre theorique original qui assimile les mouvements de pmisation a des structures de gestion des transactions; l'auteur analyse le role strategique de la pmisation, ie de la forme pme dans la mise en oeuvre de ces structures. Globalement, la pmisation ne joue un role strategique que dans le cas des reseaux xentres. Dans toutes les autres situations, ne possedant pas d'enjeu strategique, elle ne constitue qu'une pratique contigente. Enfin, la recherche presente les 6 facteurs favorables a la pmisation a partir de 4 niveaux d'analyse: le macroenvironnement technologique, l'industrie, la firme (metier, strategie, culture), et les transactions pmisees. Au total, la these constitue une premiere tentative de theorisation des processus de pmisation et apporte un nouvel eclairage sur les strategies organisationnelles qui combinent efficacite, efficience et flexibiliteStarting from the observation that,in the current context of organizational changes, the mobilization of the pme*form plays an increasingly important role, this research explores the utility and validity of the concept of "pmization" for strategic management. Defining "pmization" as the use of the pme*form and adopting a strategic perspective, this dissertation shows a complete and coherent array of the forms of pmization grouped into 3 categories: (1) the logic of repulsion: filialization, spin-offs, impartition, reconversion, break-ups, (2) the logic of attraction: internal external growth clusters, subcontracting and federations, (3) the logic of centered metworks where a firm transforms itself into the central core of a group pf pme*satellites. Using an original framework which assimilates the movements of pmization to governance structures, the author analyses the strategic role of pmization, ie of the pme*form for the implementation of these structures. Globally, pmization plays a strategic role only in the case of centered networks. In all other situations, it has no strategic value and therefore constitutes only a contingent practice. Finally, the research presents the 6 factors in favor of pmization which are on 4 levels: the technological environment, the industry, the firm (business, strategy, culture), and the transaction characteristics. In summary, this work constitutes a first trial for developing a theory of pmization and suggests an original approach concerning the new organizational strategies which combine effectiveness, effic
29
Satlow, Christian [Verfasser]. "Rückgewinnung von Kunststoffen aus Elektro- und Elektronikschrott am Beispiel von Telekommunikationsendgeräten / Christian Satlow". Aachen : Shaker, 2004. http://d-nb.info/118160320X/34.
Texto completo da fonte
30
Sousa, Bárbara Raquel Pereira Leite de. "As rochas metamórficas da região de Satão (Zona Centro-Ibérica)". Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11985.
Texto completo da fonteResumo:
Mestrado em Engenharia GeológicaA região de Sátão localiza-se no centro de Portugal Continental e está inserida na Zona Centro-Ibérica (ZCI). A área em estudo é composta maioritariamente por metassedimentos de idade proterozóica superior a câmbrica inferior do Super Grupo Dúrico-Beirão, dobrados e metamorfizados durante a orogenia varisca. Estas rochas foram intruídas por granitóides variscos sin- e tardi-pós-tectónicos, representados na área pelos maciços de Sátão, Cota e Aguiar da Beira. Os principais objetivos da investigação realizada no âmbito desta dissertação consistiram em caracterizar estruturalmente o Super Grupo Dúrico-Beirão; caracterizar o metamorfismo regional que afetou as formações do Super Grupo Dúrico-Beirão; cartografar as isógradas de metamorfismo regional e definir a zonalidade metamórfica e, por fim, analisar as principais modificações mineralógicas e texturais resultantes do metamorfismo de contacto nos metassedimentos. Com base nos dados de campo e no estudo petrográfico foi possível retirar as seguintes conclusões: 1) Na área estudada, o caráter polifásico da deformação varisca manifesta-se através da sobreposição de três gerações de estruturas. De acordo com o contexto geológico regional, pode-se inferir que estas se correlacionam com a 1ª, 2ª e 3ª fases de deformação. As 1ª e 2ª fases geram xistosidades nos metassedimentos (S1 e S2, respetivamente), enquanto a 3ª fase produz dobras, a diferentes escalas, que estão bem representadas em toda a região 2) Na zona de Sátão, foi possível cartografar as isógradas da estaurolite e da silimanite + feldspato potássico que também foram dobradas pela D3. 3) De acordo com os dados obtidos verifica-se que o grau do metamorfismo regional aumenta de norte, onde se situam as rochas de menor grau, para sul, onde afloram as rochas migmatíticas. 4) Os efeitos do metamorfismo de contacto associado às intrusões graníticas tardi-pós-tectónicas da região originaram modificações texturais e mineralógicas nas rochas, mascarando muitas vezes o metamorfismo regional prévio. 5) Com base nos dados de metamorfismo, foi possível cartografar uma falha com orientação N-S, que parece estar relacionada com a terceira fase de deformação varisca.
The Sátão region is located on the central zone of continental Portugal and belongs to the Central Iberian Zone. The area of study is mainly constituted by metasediments since superior proteozoic to inferior cambrian age of the “Super Grupo Dúrico-Beirão”, folded and metamorphosed during the variscan orogeny. These rocks were intruded by syn- and tardi-post-tectonic variscan granites, represented in that area by massifs of Sátão, Cota and Aguiar da Beira. The research work in this essay aims the structural characterization of the “Super Grupo Dúrico-Beirão”, the regional metamorphism that affects it, make the cartography of the isogrades of the local metamorphism, define the metamorphic zonality and finally analyze the main mineralogical and textural changes that results on the contact metamorphism of the metasediments. Based on field data and on the petrographic study it was possible to conclude: 1) In the area of study, the polyphase character of the variscan deformation is manifested by the superimposition of three generations of structures. According the regional geological context it can be inferred that are correlated with the first, second and third deformation phases. The first and second phases generate schistosities on the metasediments (S1 and S2, respectively), whereas the third phase produces folds, at different scales, present in all the region. 2) In Sátão zone, staurolite and sillimanite + potassium feldspar isogrades were mapped, which were also folded by D3. 3) According the attained data the regional metamorphism degree increase from north, where the minor metamorphism grade rocks are located, to south where occur migmatites. 4) The contact metamorphism effects associated to the tardi-post-tectonic granitic intrusions of studied zone originated textural and mineralogical modifications on the rocks, masking many often the previous regional metamorphism. 5) Based on the metamorphism data, it was possible to make the cartography of a fault with N-S orientation that seems to be related to the third phase of the variscan deformation.
31
Michel, Philippe. "Autour des conjectures de sato-tate". Paris 11, 1995. http://www.theses.fr/1995PA112016.
Texto completo da fonteResumo:
Dans ce travail, on s'interesse a diverses applications des lois d'equidistribution de sato-tate (qui decrivent la repartition de quantites arithmetico-geometriques interpretees comme des frobenius). La premiere partie traite des sommes d'exponentielles et plus particulierement des sommes de kloosterman kl(l,m ;n). Combinant des techniques de crible avec celles de la cohomologie l-adique, nous montrons que la minoration |kl(1,1,pq)|/2(pq)#1#/#2 0. 16 est verifiee pour une proportion positive de couples de nombres premiers (p,q). Ce resultat est etendu a d'autres familles de sommes d'exponentielles. On etudie egalement le comportement en moyenne des quantites kl(1,m ;p) et kl(1,m ;n)#k, en employant des methodes modulaires (formule de kuznetzov) ou l-adiques. Nous prouvons egalement deux nouveaux theoremes de type bombiei-vinogradov uniformes. La deuxieme partie est consacree a l'etude du rang en moyenne dans diverses familles de varietes abeliennes definies sur q. On montre, en admettant des conjectures standard (qui permettent l'application les formules explicites de weil), que quand la monodromie de la famille est irreductible, le rang de ses varietes est borne en moyenne. Dans le cas d'une famille de courbes elliptiques non isotriviale, ou d'une famille de jacobiennes issues d'un pinceau de lefschetz sur une surface, les lois de sato-tate s'appliquent et permettent d'ameliorer substantiellement la majoration generale
32
Magnano, Guido. "Poisson-Nijenhuis Structures and Sato Hierarchy". Doctoral thesis, SISSA, 1991. http://hdl.handle.net/20.500.11767/4437.
Texto completo da fonteResumo:
The thesis is organized in three distinct parts. The first part ( § 1 and §2) is purely
expository. After a brief introduction to the basic ideas of the bi-Hamiltonian approach
to integrable systems in §1, in §2 the bi-Hamiltonian factorization of Sato's equations is
described as explicitly as possible. This section collects the "experimental facts" which
we aim to explain in the following part of the thesis. In §2 we also introduce and discuss
different representations of the Sato hierarchy, as families of integro-differential equations
in two space variables and in a finite number of fields, which we call Sato-Gel'fand-Dikii
hierarchies. The simplest representation of this type coincides with the well-known KP
hierarchy, while the other representations do not appear, to oμr knowledge, in the previous
literature. The second part of the thesis includes §3, §4 and §5 and represents the theoretical core
of this work. The main result (§4) is the construction of the Poisson-Nijenhuis structures
already mentioned; in §5 we introduce the Kac-Moody algebra of Hamiltonian vector fields,
and we show that these vector fields admit a Lax representation. The only arbitrary point
in the construction is the choice of a Lie-algebra cocycle corresponding to the affine part
of the Lie-Poisson brackets: both the Kac-Moody algebra of bi-Hamiltonian vector fields
and its Lax representation are completely determined by that cocycle.
The third and final part is devoted to the formal application of the abstract framework
to algebras of pseudodifferential operators. In §6 the Gel'fand-Dikii and the Sato-Gel'fandDikii
hierarchies are obtained as reductions (on different affine subspaces) of the dynamical
systems previously obtained, for finite n, while the Sato hierarchy is recovered in §7 as a
generalization of the same construction to the case n = oo.
33
Parviainen, T. (Timo). "Ruokohelpiviljelyn optimointi suopohjilla:turvetuotantoalueiden geologisen ympäristön, pohjaturpeen sekä kierrätyslannoitteiden käytön vaikutus ruokohelpin käyttämiin alkuaineisiin ja satoon". Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514284588.
Texto completo da fonteResumo:
Abstract There are various after-use options on the cut-away peatlands, depending on the characteristics of the soil. If the soil is devoid of rock, cultivation of reed canary grass is a profitable after-use option. The aim of this study was to determine how characteristics of peat, peatland surroundings and fertilizers influence the element uptake of reed canary grass. In the present investigation the peat production areas of Luesuo, Piipsanneva and Jouttenisenneva were selected as study areas. A comprehensive sampling programme was carried out in each of the study areas. In addition, two experimental areas for cultivation of reed canary grass were established in Luesuo and Hankilanneva between 2004 and 2005. The results obtained indicate that all study areas were suitable for cultivating reed canary grass, but fertilizers must be added to make up nutrient deficiencies. The study areas were very clean from heavy metals. The results also suggest that the characteristics of peat or surroundings of peatland do not influence the nutrient level of peat significantly, considering the cultivation of reed canary grass. The large geochemical provinces have a smaller impact on nutrient and heavy metal levels in the peat on the peat cut-away areas compared to smaller geochemical units. Heavy metal content in the peat and in the mineral soil under the peat seems to correlate. Reed canary grass does not uptake heavy metals from the cultivation media effectively. Liming slag was better for liming in cultivation of reed canary grass than ash. Although ash has large amounts usable nutrients, especially potassium, it did not raise the heavy metal content in peat to harmful levels, it can therefore be used in the cultivation of reed canary grass. Stock fertilized fur animal manure compost produced almost as much biomass as optimized artificial fertilizers. After the correction of nutrient deficiencies, compost is suitable for the cultivation of reed canary grass in peatlands. Because the total nutrient levels are high in compost, its fertilizer effect lasts longer than in artificial fertilizers, where nutrients are all in a dissolved form. Already in the first growing season the cultivation of reed canary grass changed the cut-away peatland from a carbon source to a carbon sink. In this respect, the reed canary grass cultivation can be used to produce bioenergy to replace fossil fuels in accordance with the goals of Kyoto ProtocolTiivistelmä Turvetuotannosta vapautuneella suopohjalla toteutetaan erilaisia jälkikäyttötapoja riippuen suopohjan ominaisuuksista. Jos suopohja on kohtuullisen kivetöntä, ruokohelpiviljely on kannattavaa. Viljelty ruokohelpi poltetaan turpeen tai hakkeen seassa. Tämän tutkimuksen tarkoitus oli selvittää miten pohjaturpeen ja suopohjan ympäristöalueiden ominaisuudet sekä viljelyyn käytetyt lannoite- ja kalkitusaineet vaikuttavat ruokohelpin käyttämiin ravinteisiin. Ruokohelpiviljelyn lannoituskustannukset ovat suuret, joten suopohjan luontainen ravinnetila kannattaa huomioida lannoitusta suunniteltaessa. Suopohjan ravinnetila saadaan selville laatimalla alueelle viljavuusanalyysi. Kyseisen analyysin yhteydessä on hyödyllistä tehdä myös raskasmetallianalyysit, jotta viljelykäyttöön tulevan suopohjan puhtaudesta voidaan varmistua. Tutkimuksen kohdealueiksi valittiin Luesuon, Piipsannevan ja Jouttenisennevan turvetuotantoalueet. Lisäksi tutkimusta varten perustettiin ruokohelpin viljelykoealueet Luesuolle ja Hankilannevalle vuosina 2004 ja 2005. Tutkimusalueilla suoritettiin kattava näytteenotto. Näytteistä analysoitiin tärkeimmät kasviravinteet sekä joukko raskasmetalleja. Tulosten perusteella tutkimusalueille laadittiin viljavuusluokittelu. Tutkimusalueet soveltuvat hyvin ruokohelpiviljelyyn, mutta ravinnepuutokset tulee korjata lannoituksella käytettäen suopohjille suositeltua lannoitusta. Tutkimusalueet osoittautuivat puhtaiksi raskasmetalleista. Tutkimuksen kohteina olleiden suopohjien liukoisen kaliumin ja fosforin pitoisuudet olivat hyvin alhaisia, eivätkä turpeen tai ympäristön ominaisuudet vaikuttaneet niiden pitoisuuksiin ruokohelpiviljelyn kannalta merkittävästi. Liukoisen magnesiumin ja kalsiumin pitoisuudet sen sijaan vaihtelivat tutkituilla suopohjilla kohtuullisen paljon riippuen turpeen ominaisuuksista. Geokemiallisella provinssilla ei todettu olevan niin suurta merkitystä suopohjien lopputurpeiden alkuainepitoisuuksiin kuin pienemmillä geokemiallisilla yksiköillä. Tutkittujen suopohjien turpeen ja sen alla olevan kivennäismaan raskasmetallipitoisuudet korreloivat keskenään. Tutkimustulosten mukaan kasvualustan raskasmetallit eivät siirry tehokkaasti ruokohelpiin. Poikkeuksena olivat sinkin ja molybdeenin pitoisuudet, joita ruokohelpissä esiintyi korkeampina pitoisuuksina kuin kasvualustassa. Haitallisten raskasmetallien pitoisuudet olivat huomattavasti alhaisempia ruokohelpissä kuin kasvualustassa. Ruokohelpi sisälsi raskasmetalleja erittäin pieninä pitoisuuksina, joten viimeisen kasvukuukauden muutokset olivat vaikeasti tulkittavissa. Näyttää kuitenkin siltä, että ruokohelpi siirtää ainakin osan kuparista, sinkistä ja molybdeenistä juuristoonsa talven ajaksi. Suoritettujen lannoituskokeiden perusteella teräskuona soveltuu voimalaitostuhkaa paremmin turvekentän kalkitukseen ruokohelpiviljelyssä. Voimalaitostuhka sisältää kuitenkin huomattavia määriä hyödynnettäviä ravinteita, etenkin kaliumia. Tutkimuksessa havaittiin, ettei voimalaitostuhka lisännyt edes ylisuurina annoksina kasvualustan raskasmetallipitoisuuksia haitallisesti, joten sitä voidaan käyttää ruokohelpiviljelyssä. Varastolannoitetulla kompostilla saavutettiin lähes yhtä hyvä ruokohelpisato kuin optimoidulla mineraalilannoitteella. Näin ollen turkislantakompostia voidaan ravinnekorjausten jälkeen käyttää mainiosti ruokohelpiviljelyyn. Kompostin ravinnevaikutus on myös suurten kokonaisravinnepitoisuuksien vuoksi pidempi kuin mineraalilannoitteilla. Fosforin varastolannoitus turkislantakompostilla onnistui ensimmäisen kasvukauden perusteella hyvin. Tutkimuksessa todettiin, että jo ensimmäisenä kasvukautena ruokohelpiviljelyllä saadaan muutettua hiililähteenä toimiva entinen turvetuotantoalue hiilinieluksi. Ruokohelpiviljelyllä tuotetulla bioenergialla voidaan lisäksi korvata fossiilisia polttoaineita Kioton ympäristösopimuksen tavoitteiden mukaisesti
34
Chaga, Marco Antonio Maschio Cardozo. "A viagem do haicai de Nempuku Sato". reponame:Repositório Institucional da UFSC, 1995. http://repositorio.ufsc.br/xmlui/handle/123456789/76368.
Texto completo da fonteResumo:
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e ExpressãoMade available in DSpace on 2012-10-16T09:42:12Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T19:42:42Z : No. of bitstreams: 1 100587.pdf: 2743708 bytes, checksum: 91298c2184c4396b438a622e17faea9d (MD5)
35
Skalický, Ivan. "Auditorská etika a případy jejího porušení". Master's thesis, Vysoká škola ekonomická v Praze, 2010. http://www.nusl.cz/ntk/nusl-71984.
Texto completo da fonteResumo:
This thesis deals with relation between audit and ethics. First part describes the role of ethics in society and demonstrates specifics of audit profession. Second part deals with ethical codes in audit. The output of this section is comparison of ethical rules in the Czech Republic and in the USA. The last part shows on the Satyam case consequences of auditors ethics violation.
36
Sator, Christian [Verfasser]. "Asymptotische Nahfeldanalysen ebener Multi-Materialverbindungsstellen mit der Methode komplexer Potentiale / vorgelegt von Christian Sator". Darmstadt : Techn. Univ., Studienbereich Mechanik, 2010. http://d-nb.info/1006966684/34.
Texto completo da fonte
37
Blanco, Fernández Guillem. "Bernstein-Sato polynomial of plane curves and Yano's conjecture". Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669107.
Texto completo da fonteResumo:
The main aim of this thesis is the study of the Bernstein-Sato polynomial of plane curve singularities. In this context, we prove a conjecture posed by Yano about the generic b-exponents of a plane irreducible curve.
In a part of the thesis, we study the Bernstein-Sato polynomial through the analytic continuation of the complex zeta function of a singularity. We obtain several results on the vanishing and non-vanishing of the residues of the complex zeta function. Using these results we obtain a proof of Yano's conjecture under the hypothesis that the eigenvalues of the monodromy are pair-wise different. In another part of the thesis, we study the periods of integrals in the Milnor fiber and their asymptotic expansion. These periods of integrals can be related to the b-exponents and can be constructed in terms of resolution of singularities. Using these techniques, we can present a proof for the general case of Yano's conjecture.
In addition to the Bernstein-Sato polynomial, we also study the minimal Tjurina number of a plane irreducible curve and we answer in the positive a question raised by Dimca and Greuel on the quotient between the Milnor and Tjurina numbers. More precisely, we prove a formula for the minimal Tjurina number of a plane irreducible curve in terms of the multiplicities of the strict transform along its minimal resolution. From this formula, we obtain the positive answer to Dimca and Greuel question.
This thesis also contains computational results for the theory of singularities on smooth complex surfaces. First, we describe an algorithm to compute log-resolutions of ideals on a smooth complex surface. Secondly, we provide an algorithm to compute generators for complete ideals on a smooth complex surface. These algorithms have several applications, for instance, in the computation of the multiplier ideals associated to an ideal on a smooth complex surface.El principal objectiu d'aquesta tesi és l'estudi del polinomi de Bernstein-Sato de singularitats de corbes planes. En aquest context, es demostra una conjectura proposada per Yano el 1982 sobre els \( b \)-exponents genèrics d'una corba plana irreductible. En una part d'aquesta tesi, s'estudia el polinomi de Bernstein-Sato utilitzant la continuació analítica de la funció zeta complexa d'una singularitat. S'obtenen diversos resultat sobre l'anul·lació i no anul·lació del residu de la funció zeta complexa d'una corba plana. Utilitzant aquests resultats, s'obté una demostració de la conjectura de Yano sota la hipòtesi de que els valors propis de la monodromia siguin diferents dos a dos. En un altre part de la tesi, s'estudien els períodes d'integrals en la fibra de Milnor i la seva expansió asimptòtica. Aquesta expansió asimptòtica dels períodes pot ser relacionada amb els b-exponents i pot ser construïda en termes de la resolució de singularitats. Utilitzant aquestes tècniques, es presenta una prova del cas general de la conjectura de Yano. A més a més del polinomi de Bernstein-Sato, també s'estudia el nombre de Tjurina mínim d'una corba plana irreductible i responem positivament a una pregunta formulada per Dimca i Greuel sobre el quocient entre els nombres de Milnor i Tjurina. Concretament, es demostra una fórmula pel nombre de Tjurina mínim en un classe d'equisingularitat de corbes planes irreductibles en termes de la seqüència de multiplicitats de la transformada estricta al llarg de la resolució minimal. A partir d'aquesta fórmula, s'obté la resposta positiva a la pregunta de Dimca i Greuel. Aquesta tesi també conté resultats computacionals per la teoria de singularitats en superfícies complexes llises. Primer, es descriu un algorisme que calcula la log-resolució d'ideals en un superfície complexa llisa. En segon lloc, es dona un algorisme per calcular generadors per ideals complets en una superfície complexa llisa. Aquests algorismes tenen diverses aplicacions, com per exemple, en el càlcul d'ideals multiplicadors associats a un ideal en una superfície complexa llisa.
38
Bohner, Georg [Verfasser], K. [Gutachter] Sator, R. [Gutachter] Kachel e R. [Gutachter] Lehmann. "Schlaganfall-Bildgebung mittels Mehrschicht-Spiral-CT / Georg Bohner ; Gutachter: K. Sator, R. Kachel, R. Lehmann". Berlin : Humboldt-Universität zu Berlin, 2005. http://d-nb.info/1206190329/34.
Texto completo da fonte
39
Oliveira, Marcia Satomi Suzuki de. "Aspectos jurídicos da poluição genética no direito Brasileiro / Marcia Satomi Suzuki de Oliveira ; orientador, Jussara Maria Leal de Meirelles". reponame:Biblioteca Digital de Teses e Dissertações da PUC_PR, 2007. http://www.biblioteca.pucpr.br/tede/tde_busca/arquivo.php?codArquivo=840.
Texto completo da fonteResumo:
Dissertação (mestrado) - Pontifícia Universidade Católica do Paraná, Curitiba, 2007Bibliografia: f. 144-155
O nascimento da Engenharia Genética constitui um marco para as Ciências, pois a partir do desenvolvimento desta técnica, também conhecida como técnica do DNA recombinante, tornou-se possível produzir os Organismos Geneticamente Modificados (OGM). Em 1996,
40
Guimarães, Andréa Gomes. "Polinômio de Bernstein-Sato de uma hipersuperfície com singularidade isolada". Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/55/55135/tde-26112014-144207/.
Texto completo da fonteResumo:
Neste trabalho estudamos algumas raízes do polinômio de Bernstein bf associado a um germe f(X) ∈ ℂ{X1,. . . , Xn} com ponto crítico isolado na origem. Sabe-se que, para cada raiz de bf, existe um número espectral tal que a soma desses dois números é um inteiro. Em geral, não se sabe exibir explicitamente esses números inteiros, embora existam cotas para eles. M. Saito [Sai93] exibe um subconjunto do conjunto das raízes de bf tal que para esses elementos a soma vale -1. Hertling e Stahlkc [IIS99] conseguiram aumentar esse subconjunto de raízes, supondo f(X) em duas variáveis, com ponto crítico isolado e monodromia finita (hipóteses essas bem restritivas). Conseguimos estender esse último resultado, sem restrições sobre o número de variáveis de, f{X) e apenas com a hipótese de ponto crítico isolado. Além disso, no caso de germes f(X1, X2) irredutíveis e com um único par de Puiseux, mostramos como descrever um subconjunto maior de raízes de bf, quando f pertence a uma dada classe de equidiferenciabilidade.In this work we studv some roots of the Bernstein polynomial bf associated to a germ f(X) in the maximal ideal of ℂ{X1,. . . , Xn} with an isolated criticai point at the origin. It is known that for each root of bf there exists a spectral number such that the sum of these two nurnber is an integer. In general, one doesn\'t. know how to compute explicitly these integers, although there are bounds on them. M. Sai to, in [Sai93], exhibits a subset of the set of roots of bf, such that, for these elements the sum is -1. Heríling and Stahlke, in [HS99], succeeded to increase this subset of roots, assuming f(X) in two variables, with isolated criticai point and finito monodrorny (such hypotheses are very restrictive). We succeeded to extend this last result without any restriction on the number of variables of f(X) and only with the assumption of isolated criticai point. Moreover, in the case of irreducible germs f(X1, X2) with only one Puiseux pair, we show how to describe a. larger subset of roots of bf, when f belongs to a given equidiferentiability class.
41
Hivert, Laurent. "Modeles econometriques et systeme a base de connaissances satchmo, une application a la modelisation du choix du mode de transport". Paris 6, 1989. http://www.theses.fr/1989PA066604.
Texto completo da fonteResumo:
Pour planifier les transports, il est necessaire de simuler et de prevoir les comportements des individus en situation de choix, en modelisant la repartition de leurs deplacements entre differents moyens de transport. Jusqu'a present, les approches les plus sophistiquees en econometrie utilisaient de lourdes series d'hypotheses afin de constituer des modeles desagreges (type logit) fondes sur la micro-economie du consommateur. A l'inverse, les travaux recents d'analyse de la mobilite, moins quantitatifs, cherchent a comprendre les phenomenes en profondeur en mettant en cause la validite theorique des modeles. Depasser le clivage entre approche econometrique et phenomenologique, telle est l'ambition du systeme satchmo presente dans ce travail: il s'agit d'un systeme a base de connaissances formalisant l'ensemble des contraintes pesant sur les individus pour cerner au plus pres leur univers de choix. La premiere partie de la these est consacree a une analyse critique d'un cas d'utilisation des modeles desagreges. La seconde partie decrit la constitution de ce nouveau systeme dont est donne ensuite un exemple d'application sur un echantillon national d'enquete
42
Kebede, Sebsibew. "On Bernstein-Sato ideals and Decomposition of D-modules over Hyperplane Arrangements". Licentiate thesis, Stockholms universitet, Matematiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-129493.
Texto completo da fonte
43
Adachi-Bähr, Satomi [Verfasser]. "Kontrastive Analyse von Gliederungsprinzipien in argumentativen schriftlichen Texten im Deutschen und Japanischen : am Beispiel der Textsorte Leitartikel / Kommentare / Satomi Adachi-Bähr". Mannheim : Institut für Deutsche Sprache, Bibliothek, 2006. http://d-nb.info/1136661530/34.
Texto completo da fonte
44
Sakakibara, Tsuyoshi. "The collapse of Tokugawa Japan and the role of Sir Ernest Satow in the Meiji Restoration, 1853-1869". Thesis, King's College London (University of London), 2015. https://kclpure.kcl.ac.uk/portal/en/theses/the-collapse-of-tokugawa-japan-and-the-role-of-sir-ernest-satow-in-the-meiji-restoration-18531869(c496240a-c767-42b0-927a-edec81c43418).html.
Texto completo da fonteResumo:
The main argument relates to an analysis of the essays written by Ernest Mason Satow in 1866, known as Eikoku Sakuron in Japanese, and also to an analysis of British diplomacy at the time of the civil war and during the Meiji Restoration in 1868-69. The major reason why these two areas should be examined is that the common understanding of them, which Japanese historiography has traditionally defined as historical truth, turns out not to be true. The main idea, which it was planned to argue in this thesis, was to emphasise the efforts of Satow during the Meiji Restoration, because Japanese historiography has consistently defined Eikoku Sakuron as the milestone for Japanese political modernization. In other words without Satow, nineteenth-century Japanese could never have promoted their remarkable national transformation. This modernization was connected with British diplomacy. Japanese historiography asserts that thanks to the British, who had supported the anti-feudal forces, the Japanese could found their modern state in such a short period. These two historical assumptions are viewed as common sense even in present Japanese society. However, through this research, it must now be recognised that the tenets defined by orthodox Japanese historiography cannot be accepted in wider academic argument, because what the Japanese have always believed is largely refuted by British and other sources. Regarding Eikoku Sakuron, although it was read by some Japanese, it did not create a huge psychological impact in nineteenth-century Japan. Satow’s argument was revolutionary, but it can hardly be defined as the guideline for eventual modernization. So why has Japanese historiography clung to its ideas and definition? When this question was asked, the direction for this thesis became established. The Japanese interpretation of the Meiji Restoration was established not to pursue historical truth but to justify political actions. In Japanese historiography, there is a tendency that when historians discuss the Meiji Restoration, they revere it unconditionally, whereas when discussing feudalism, they do not analyse it fairly. The Meiji Restoration will be argued more objectively in this thesis. It will become the opportunity to challenge traditional Japanese historiography.
45
Simmons-Carroll, Kathryn B. "French Quarter Festivals, Inc.: A Year of Festivals (Internship Report)". ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/aa_rpts/169.
Texto completo da fonteResumo:
This report accounts my time spent as an intern with French Quarter Festivals, Inc. from March 2013 through August 2014. FQFI, a nonprofit 501(c)(3) organization in New Orleans, Louisiana, began with French Quarter Festival in 1984 and now produces three festivals each year. This paper seeks to discuss how the organization has changed over time, examine the structure of FQFI in its current state, and make recommendations for FQFI as they continue to “promote the Vieux Carré and the City of New Orleans through high quality special events and activities that showcase the culture and heritage of this unique city, contribute to the economic well being of the community, and instill increased pride in the people of New Orleans.”
46
Cavalini, Flavia Cristina. "Fisiologia do amadurecimento, senescência e comportamento respiratório de goiabas \'Kumagai\' e \'Pedro Sato\'". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/11/11144/tde-10032009-093840/.
Texto completo da fonteResumo:
O amadurecimento e a senescência tem sido diretamente relacionados ao climatério do CO2 e do etileno. No entanto, estudos recentes têm demonstrado que algumas transformações pós-colheita ocorrem independentemente desses eventos e que muitos frutos não se enquadram nas definições clássicas de padrão de atividade respiratória, indicando a necessidade de maiores estudos a respeito da fisiologia do amadurecimento e senescência de frutos. O comportamento respiratório de goiabas é contraditório, servindo como modelo para estes estudos. O uso de reguladores do amadurecimento pode auxiliar na definição do comportamento respiratório de goiabas Kumagai e Pedro Sato. Tendo-se em vista o estabelecido, conduziu-se a etapa 1, com o intuito de determinar índices que indiquem o início da senescência. A etapa 2 visou determinar o comportamento respiratório de goiabas das variedades Kumagai e Pedro Sato submetidas à aplicação de acelerador (etileno) e retardadores (1-MCP e AVG) do amadurecimento. Na etapa 1, as goiabas recém colhidas foram tratadas com fungicida e mantidas em câmara a 23 ± 1oC e 85% UR até a completa senescência. Na etapa 2, os frutos foram submetidos à aplicação de AVG, 1- MCP e etileno e então armazenados em câmara a 23 ± 1oC e 85% UR até a completa senescência. Frutos sem reguladores vegetais foram utilizados como controle. Os frutos foram avaliados a cada dois dias em ambas as etapas. O delineamento estatístico utilizado foi o inteiramente casualizado e os resultados foram submetidos à análise de dados longitudinais, devido ao caráter quantitativo imposto pelo fator tempo de armazenamento. As curvas também foram submetidas à análise do erro padrão da média. As diferenças entre dois tratamentos maiores que as somas de dois erros padrões foram consideradas significativas. Os teores de acetaldeído, etanol e o extravasamento de eletrólitos foram os índices que mais contribuíram para distinguir o amadurecimento da senescência. O aumento brusco apresentado nos teores de acetaldeído e etanol indica início do metabolismo fermentativo, comportamento característico de senescência, além do aumento no extravasamento de eletrólitos, sugerir descompartimentação celular. Os frutos da variedade Pedro Sato não podem ser classificados como climatéricos, nem tão pouco como não climatéricos, pois apesar de amadurecerem, apresentaram pico de produção de etileno após o amadurecimento dos mesmos, além de não responderem à aplicação de etileno exógeno. Apesar das goiabas Kumagai responderem à aplicação de etileno, não se observou comportamento climatério na produção de CO2 e de C2H4, desta forma, esta variedade não pode ser enquadrada nas classificações de padrão de atividade respiratória em uso.Ripening and senescence have been directly related to CO2 and ethylene climacteric behavior. However, recent studies have shown that some postharvest processes occurs independently of those events and that many fruits are not frame in the definitions of respiratory activity traditional pattern, indicating the need for more studies on fruit ripening and senescence physiology. Guavas fruit respiratory behavior is contradictory and serves as a model for these studies. The use of ripening regulators can help in defining the respiratory behavior of Kumagai and Pedro Sato guavas. Consequently, the step 1 has been conducted, with the intention of determining indicators that indicate the beginning of the senescence. The step 2 aimed to determine the respiratory behavior of guava fruits of Kumagai and Pedro Sato cultivars subjected to the application of accelerator (ethylene) and retardants (1-MCP and AVG) of the ripening. In step 1, the newly harvested guavas were treated with fungicide and kept at 23 ± 1oC and 85% RH to complete senescence. In step 2, the fruits were submitted to AVG, 1-MCP and ethylene application and then stored at 23 ± 1oC and 85% RH to complete senescence. Fruit without ripening regulators were used as controls. The fruits were evaluated every two days in both steps. The experimental design was completely randomized and the results were submitted to longitudinal data analysis, due to the quantity of samples imposed by the storage time factor. The curves have been subjected to average standard error analysis. Differences between two treatments larger than the sum of two errors patterns were considered significant. The levels of acetaldehyde, ethanol and ion leakage were indices that contributed most to distinguish ripening from senescence. The increase made in levels of acetaldehyde and ethanol suggests fermentative metabolism, characteristic senescence behavior, beyond the increase in ion leakage, suggests cell decompartmentalization. The fruits of Pedro Sato cultivar can not be classified as climacteric, nor as non-climacteric, because despite they ripen, they show an ethylene production peak after their ripening, and besides do not respond to exogenous ethylene. Even though Kumagai guava fruits reply to ethylene application, there was no climacteric behavior observed during CO2 and C2H4 production thus this variety can not be framed in the respiratory climacteric pattern rankings in use.
47
Azzolini, Marisa. "Fisiologia pós-colheita de goiabas 'Pedro Sato': estádios de maturação e padrão respiratório". Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/11/11144/tde-25022003-140356/.
Texto completo da fonteResumo:
A goiaba apresenta elevado grau de perecibilidade necessitando de um manejo pós-colheita eficiente capaz de reduzir os processos de senescência. Para tanto, o conhecimento do padrão respiratório e dos processos envolvidos no amadurecimento é fundamental. O presente trabalho foi realizado com os objetivos de determinar os índices de maturação, a influência dos estádios de maturação na qualidade pós-colheita e o padrão respiratório de goiabas 'Pedro Sato' e avaliar as respostas dos frutos à aplicação do etileno exógeno e ao bloqueador da ação de etileno 1-MCP (1-metilciclopropeno). Na primeira fase determinaram-se os índices de maturação e a influência de três estádios de maturação na qualidade pós-colheita dos frutos. Os frutos foram selecionados em três estádios de maturação segundo a cor da casca: Estádio 1: cor da casca verde-escura; Estádio 2: cor da casca verde-clara; Estádio 3: cor da casca verde-amarela. Os frutos foram armazenados em câmara com temperatura controlada de 23 + 1 o C e 85 + 5 %UR e analisados quanto às mudanças físico-químicas e qualidade sensorial. Na segunda fase do trabalho foi determinado o padrão respiratório dos frutos analisando-se a atividade respiratória, a produção de etileno e as mudanças físico-químicas após a colheita. Analisou-se também a resposta dos frutos à aplicação de etileno (1000ml.l -1 ) e de 1- metilciclopropeno (300nl.l -1 ) também foi avaliada. A cor da casca e a firmeza da polpa foram considerados os melhores índices de maturação. As variáveis físico-químicas apresentaram pouca variação entre os estádios de maturação durante o amadurecimento Porém, foram observadas diferenças significativas em relação à análise sensorial, sendo as melhores notas atribuídas ao estádio 3. Na segunda fase observou-se aumento da atividade respiratória e da produção de etileno independente do estádio de maturação, determinando o padrão climatérico de amadurecimento. Verificou-se que a máxima atividade respiratória e a produção de etileno ocorrem após o completo amadurecimento. Os frutos não responderam a aplicação de etileno exógeno, não apresentando diferenças no amadurecimento em relação aos frutos do tratamento controle. Entretanto, o 1-MCP retardou sensivelmente o processo de amadurecimento dos frutos.The guava presents high perecibilidade degree needing a handling efficient postharvest capable to reduce the senescence processes. Therefore, it is essential to the knowledge of the respiratory pattern and of the processes involved in the ripening. The present work was accomplished with the objectives of determining the maturation indexes, the influence of the maturation stage in the quality postharvest and the respiratoy pattern of guavas 'Pedro Sato' as well as evaluating the fruit response to the application of the exogenous ethylene and to blocking the action of ethylene 1-MCP (1-metylcyclopropene). In the first phase it was determined the maturation indexes and the influence of three maturation stage in the quality postharvet of fruit. The guavas were selected in three maturation stages according to the color of the peel: Stage 1: dark green peel; Stage 2: light green peel; Stage 3: yellowish green peel. The fruit was stored in a chamber with controlled temperature of 23 + 1 o C and 85 + 5 % RH and analyzed for physicochemical changes and sensorial quality. In the second phase of the work the respiratory pattern of the fruit through the respiratory activity, the ethylene production, and the changes physicochemichal after harvesting. The fruit response to the aplication of exogenous ethylene (1000ml.l -1 ) and of 1-methylcyclopropene (300nl. l -1 ) was also evaluated. The color of the peel and the firmness of the pulp were considered the best maturation indexes. The physicochemical variables presented little variation among the maturation stages during the ripening. However, significantive differences were observed concerning the sensorial analysis, being the best grades granted to stage 3 fruit. In the second phase the fruit presented increse in respiratory activity in production of ethylene independent at the maturation stage, determining the climacteric standard. The maximum respiratory activity and the ethylene production were verified after complete ripening. The guavas did not to responses the application of exogenous ethylene, showing no ripening difference respond in the ripening in relation to the guavas in the control treatment. However, the 1-MCP has sensibly retarded the ripening process in guavas.
48
Bahloul, Rouchdi. "Contributions à l'étude des idéaux de Bernstein-Sato d'un point de vue constructif". Angers, 2003. http://www.theses.fr/2003ANGE0026.
Texto completo da fonteResumo:
Le sujet de cette thèse est l'étude des polynômes de Bernstein-Sato associés à plusieurs fonctions analytiques ou polynomiales. En 1987, C. Sabbah démontra l'existence d'un polynôme de Bernstein-Sato non nul dans le cas analytique. Dans la première partie nous redémontrons ce résultat d'une manière plus élémentaire et plus constructive en utilisant la notion d'éventail de Gröbner. Dans le cas algébrique et pour n'importe quel corps de caractéristique nulle, nous montrons d'une manière effective qu'il existe un polynôme de Bernstein-Sato non nul à coefficients rationnels. Dans la seconde partie, nous nous intéressons au comportement de l'idéal de Bernstein--Sato associé à plusieurs polynômes dépendant de paramètres lorsque les paramètres bougent. Nous montrons que l'espace des paramètres est stratifié de telle sorte que sur chaque strate l'idéal de Bernstein-Sato bouge "continûment". Dans le cas al-gébrique, nous montrons, par des arguments similaires, l'existence d'un polynôme de Bernsteirn-Sato générique rationnel sur une variété affine irréductible améliorant et généralisant les résultats de H. Biosca sur ce sujet. Enfin nous montrons un ré-sultat de constructibilité de l'éventail de Gröbner associé à un idéal dépendant de paramètres. Tous ces résultats s'appuient sur un résultat général : le lemme de spécialisation. Il consiste en l'étude du comportement d'une base de Gröbner d'un idéal dépendant de paramètres lorsqu'on la spécialise le long d'une sous-variété affine ir-réductible de l'espace des paramètres. Dans la troisième et dernière partie, nous nous focalisons sur des aspects plus calculatoires. Nous incluons dans un dernier chapitre un article dans lequel nous donnons un algorithme de calcul de certains idéaux de Bernstein-Sato et nous terminons par une annexe dans laquelle nous implémentons les différents algorithmes rencontrés dans cette thèse à l'aide du programme kan / sm 1 développé par N. TakayamaThe subject of this thesis is the study of the Bernstein-Sato polynomials associated with several analytic or polynomial functions. In 1987, C. Sabbah proved the existence of a non zero Bernstein-Sato polynomial in the analytic case. In the first part, we prove this result in a more elementary and constructive way by using the notion of Gröbner fan. In the algebraic case, this enable us to construct algorithmically a non zero rational Bernstein-Sato polynomial. In the second part, we focus on the Bernstein-Sato ideal associated with polynomials depending on parameters. We prove that the space of the parameters is stratified in such a way that on each stratum, the Bernstein-Sato ideal moves "continuously". In the algebraic case, we prove the existence of a non zero generic Bernstein-Sato polynomial on an irreducible affine variety. This improves and generalizes the results of H. Biosca on this subject. Finally, we prove a constructibility result about the Gröbner fan associated with an ideal depending on parameters. All these results are based on a general result which consists in studying the behaviour of a Gröbner basis associated with an ideal depending on parameters when we specialize it on an irreducible affine sub-variety of the space of the parameters. In the third and last part, we focus on more computational aspects. We include in a last chapter an article where we give an algorithm for computing some Bernstein-Sato ideals. Finally, in the annex, we implement the different algorithms that we can find in this thesis
49
Ukubiala, Julyette Uruakanwa. "The South Atlantic as a zone of peace and cooperation : problems". Thesis, King's College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266177.
Texto completo da fonte
50
Schramm, Satyam Antonio [Verfasser], Friedrich Akademischer Betreuer] Linderkamap e Clemens [Akademischer Betreuer] [Hillenbrand. "Intervention bei ADHS im Jugendalter: Konzeption und empirische Evaluation des Lerntrainings für Jugendliche mit ADHS (LeJA) / Satyam Antonio Schramm. Betreuer: Friedrich Linderkamap ; Clemens Hillenbrand". Oldenburg : BIS der Universität Oldenburg, 2013. http://d-nb.info/104865124X/34.
Texto completo da fonte