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1
Charbonnieras, Christophe. "Mesure d’intégrité par l’exploitation des signaux de navigation par satellites." Thesis, Toulouse, ISAE, 2017. http://www.theses.fr/2017ESAE0036/document.
Testo completoAbstract (sommario):
Dans le cadre des systèmes de positionnement par satellite GNSS (« Global Navigation Satellite Systems »), l’intégritéde la navigation d’un utilisateur est gérée en réception par la détection, l’identification voire l’exclusion de mesures depseudo-distance jugées erronées. Généralement basés sur le concept a posteriori RAIM (« Receiver Autonomous IntegrityMonitoring »), les algorithmes de contrôle autonome d’intégrité fournissent de hautes performances pour l’aviation civile,dont le contexte de navigation est caractérisé par une forte visibilité des satellites et peu de signaux parasites captéspar l’antenne réceptrice. L’algorithme WLSR RAIM est communément utilisé dans ce cadre. Néanmoins, les techniquesRAIM ne sont pas compatibles avec la navigation terrestre en milieu contraint. En effet, le contexte urbain est notammentcaractérisé par un masquage récurrent des signaux satellitaires directs ainsi que la réception de multi-trajets générés parl’environnement proche du récepteur. RAIM ne prend pas en compte l’ensemble des données disponibles en réception,dégradant ainsi fortement ses performances. Il est donc nécessaire de développer des méthodes de contrôle d’intégritécompatibles avec un tel contexte de navigation. Pour cela, la thèse propose d’étudier l’apport d’informations GNSS a priorinon utilisées par les techniques RAIM. Deux paramètres principaux ont été exploités : le signal GNSS brut reçu et lesestimations de directions d’arrivée des signaux satellitaires DOA (« Direction Of Arrival »). La première étape a consisté à implémenter une méthode a priori qui évalue la cohérence du positionnement estimé par rapport au signal brut directement reçu. Cette méthode a été nommée Direct-RAIM (D-RAIM) et a démontré une forte sensibilité de détection, permettant d’anticiper d’éventuels risques sur la navigation et de caractériser plus finement la qualité de l’environnement proche du récepteur. Toutefois, le caractère a priori de l’approche engendre de potentielles non détection d’erreurs en cas de modèle de signal défectueux. Afin de contourner cette limitation, un couplage WLSRRAIM – D-RAIM a été développé, nommé Hybrid-RAIM (H-RAIM). Une telle approche permet de combiner robustesse etsensibilité apportées par ces techniques respectives. Le second axe de recherche a mis en évidence la contribution de l’information des DOA dans un contrôle autonome d’intégrité. L’intégration d’un réseau d’antennes en réception permet d’obtenir l’estimation des DOA pour l’ensemble dela constellation visible. Théoriquement, l’évolution jointe des DOA est directement liée à l’attitude du réseau. Cet aspectpermet donc de détecter toute incohérence sur une ou plusieurs voies en cas d’estimation(s) de DOA biaisée(s), par rapportà l’ensemble de la constellation. L’algorithme RANSAC (« RANdom SAmple Consensus») a été utilisé afin de détecter toutcomportement aberrant dans l’estimation des DOA, et ainsi mesurer la confiance que l’utilisateur peut placer dans chaquevoie. L’algorithme WLSR RAIM RANSAC a ainsi été implémenté. L’intégration de la composante DOA permet d’ajouterun degré de liberté dans le contrôle autonome d’intégrité côté récepteur et ainsi d’affiner la détection voire l’exclusiond’erreurs. Au cours de cette thèse, un récepteur logiciel a été implémenté, permettant de traiter des signaux Galileo, de lagénération du signal jusqu’au positionnement puis au contrôle d’intégrité. Ce récepteur a pu être évalué à partir de donnéessimulées en environnement urbain<br>In Global Navigation Satellite Systems (GNSS) applications, integrity is managed at the reception side by detection,identification and exclusion of faulty pseudorange measurements. Usually based on the a posteriori Receiver AutonomousIntegrity Monitoring (RAIM) concept, integrity techniques provide high performances for civil aviation, with a navigationcontext defined by a clear-sky environment. WLSR RAIM is commonly used. Nevertheless, RAIM techniques are notcompatible with a terrestrial navigation in harsh environments. For instance, urban areas are characterized by a poorvisibility and the reception of many multipaths derived from the receiver closed-environment. RAIM does not consider allthe available data in the reception chain, which dramatically deteriorates the detection performances. Hence, it is necessaryto develop integrity process compatible with such a navigation context. This PhD work studies the contribution of GNSSa priori information, disused by conventional RAIM techniques. Two main parameters have been exploited : the receivedraw GNSS signal and the Directions Of Arrival (DOA) estimations.This first step was devoted to the development of an a priori method which evaluates the consistence of the estimatedPosition Velocity Time (PVT) vector of the receiver with respect to the raw GNSS signal. This method has been calledDirect-RAIM (D-RAIM) and has shown high detection sensitivity, allowing the user to anticipate navigation risks and todefine precisely the quality of the receiver closed-environment. However, the a priori aspect of this approach may lead tonavigation error missed detections if the signal model is getting flawed. In order to circumvent this limitation, a WLSRRAIM – D-RAIM coupling has been developed, called Hybrid-RAIM (H-RAIM). Such an approach merges the robustnessand the sensitivity brought by both techniques.The second research step has brought to light the contribution of the DOA information in an autonomous integritymonitoring. Using an antenna array, the user can get the DOA estimations for all satellites in view. Theoretically, the DOAjoint evolution is directly correlated with the array rotation angles. Hence, any mismatch on the DOA estimations withrespect to the global constellation can be detected. RANdom Sample Consensus (RANSAC) algorithm has been used inorder to detect any faulty DOA evolution, derived from inconsistencies in reception linked to potential navigation risks :RANSAC measures the trust that the user can place in each channel. Therefore, a WLSR RAIM RANSAC algorithmhas been developed. The integration of the DOA component adds a degree of freedom in receiver autonomous integritymonitoring, refining the error detection and exclusion.Last but not least, a software receiver has been implemented processing Galileo data, from the signal generation to positioningand integrity monitoring. This software has been evaluated by simulated data characterizing urban environments
2
Rotondo, Giuseppe. "Processing and integrity of DC/DF GBAS for CAT II/III operations." Phd thesis, Toulouse, INPT, 2016. http://oatao.univ-toulouse.fr/17774/1/Rotondo_Giuseppe_1.pdf.
Testo completoAbstract (sommario):
In Civil Aviation domain, to cope with the increasing traffic demand, research activities are pointed toward the optimization of the airspace capacity. Researches are thus ongoing on all Civil Aviation areas: Communication, Navigation, Surveillance (CNS) and Air Traffic Management (ATM). Focusing on the navigation aspect, the goals are expected to be met by improving performances of the existing services through the developments of new NAVigation AIDS (NAVAIDS) and the definition of new procedures based on these new systems. The Global Navigation Satellite System (GNSS) is recognized as a key technology in providing accurate navigation services with a worldwide coverage. The GNSS concept was defined by the International Civil Aviation Organization (ICAO). A symbol of its importance, in civil aviation, can be observed in the avionics of new civil aviation aircraft since a majority of them are now equipped with GNSS receivers. The GNSS concept includes the provision of an integrity monitoring function by an augmentation system in addition to the core constellations. This is needed to meet all the required performance metrics of accuracy, integrity, continuity and availability which cannot be met by the stand-alone constellations such as GPS. Three augmentation systems have been developed within civil aviation: the GBAS (Ground Based Augmentation System), the SBAS (Satellite Based Augmentation System) and the ABAS (Aircraft Based Augmentation System). GBAS, in particular, is currently standardized to provide precision approach navigation services down to Category I (CAT I) using GPS or Glonass constellations and L1 band signals. This service is known as GBAS Approach Service Type-C (GAST-C). In order to extend this concept down to CAT II/III service, research activities is ongoing to define the new service called a GAST-D. Among other challenges, the monitoring of the ionospheric threat is the area where the integrity requirement is not met. Thanks to the deployment of new constellations, Galileo and Beidou, and the modernization process of the existing ones, GPS and Glonass, the future of GNSS is envisaged to be Multi-Constellation (MC) and Multi-frequency (MF). In Europe, research activities have been focused on a Dual-Constellation (DC) GNSS and DC GBAS services based on GPS and Galileo constellations. Moreover, to overcome the problems experienced by Single-Frequency (SF) GBAS due to ionosphere anomalies, the use of two frequencies (Dual Frequency, DF) has been selected as a mean to improve ionosphere anomalies detection and to mitigate ionosphere residual errors. Advantages in using a DC/DF GBAS (GAST-F) system are, however, not only related to the integrity monitoring performance improvement. Benefits, brought by DC and DF, are also related to •the robustness of the entire system against unintentional interference thanks to the use of measurements in two protected frequency bands, •the robustness against a constellation failure, •the accuracy improvement by using new signals with improved performance, and more satellites. However, the use of new signals and a new constellation, does not bring only benefits. It also raises a series of challenges that have to be solved to fully benefit from the new concept. In this thesis, some challenges, related to DC/DF GBAS, have been investigated. One of them, rising from the use of new GNSS signals, is to determine the impact of error sources that are uncorrelated between the ground station and the aircraft and that induce an error on the estimated position. Using two frequencies, there is the possibility to form measurement combinations like Divergence-free (D-free) and Ionosphere-free (I-free) for which the errors impact has to be analyzed. In this thesis, the impact of the uncorrelated errors (noise and multipath as main sources) on ground measurements is analyzed. The aim is to compare the derived performances with the curve proposed in (RTCA,Inc DO-253C, 2008) for the
3
Mink, Michael [Verfasser], and B. [Akademischer Betreuer] Heck. "Performance of Receiver Autonomous Integrity Monitoring (RAIM) for Maritime Operations / Michael Mink ; Betreuer: B. Heck." Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1122461410/34.
Testo completo
4
Salós, Andrés Carlos Daniel. "Integrity monitoring applied to the reception of GNSS signals in urban environments." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0047/document.
Testo completoAbstract (sommario):
L’intégrité des signaux GNSS est définie comme la mesure de la confiance qui peut être placée dans l’exactitude des informations fournies par le système de navigation. Bien que le concept d’intégrité GNSS a été initialement développé dans le cadre de l’aviation civile comme une des exigences standardisées par l’Organisation de l’Aviation Civile Internationale (OACI) pour l’utilisation du GNSS dans les systèmes de Communication, Navigation, et Surveillance / Contrôle du Trafic Aérien (CNS/ATM), un large éventail d’applications non aéronautiques ont également besoin de navigation par satellite fiable avec un niveau d’intégrité garanti. Beaucoup de ces applications se situent en environnement urbain. Le contrôle d’intégrité GNSS est un élément clé des applications de sécurité de la vie (SoL), telle que l’aviation, et des applications exigeant une fiabilité critique comme le télépéage basé sur l’utilisation du GNSS, pour lesquels des erreurs de positionnement peuvent avoir des conséquences juridiques ou économiques. Chacune de ces applications a ses propres exigences et contraintes, de sorte que la technique de contrôle d’intégrité la plus appropriée varie d’une application à l’autre. Cette thèse traite des systèmes de télépéage utilisant GNSS en environnement urbain. Les systèmes de navigation par satellite sont l’une des technologies que l’UE recommande pour le Service Européen de Télépéage Electronique (EETS). Ils sont déjà en cours d’adoption: des systèmes de télépéage pour le transport poids lourd utilisant GPS comme technologie principale sont opérationnels en Allemagne et en Slovaquie, et un système similaire est envisagé en France à partir de 2013. À l’heure actuelle, le contrôle d’intégrité GPS s’appuie sur des systèmes d´augmentation (GBAS, SBAS, ABAS) conçus pour répondre aux exigences de l’OACI pour les opérations aviation civile. C´est la raison pour laquelle cette thèse débute par une présentation du concept d’intégrité en aviation civile afin de comprendre les performances et contraintes des systèmes hérités. La thèse se poursuit par une analyse approfondie des systèmes de télépéage et de navigation GNSS en milieu urbain qui permets de dériver les techniques de contrôle d’intégrité GNSS les plus adaptées. Les algorithmes autonomes de type RAIM ont été choisis en raison de leur souplesse et leur capacité d´adaptabilité aux environnements urbains. Par la suite, le modèle de mesure de pseudodistances est élaboré. Ce modèle traduit les imprécisions des modèles de correction des erreurs d’horloge et d’ephemeride, des retards ionosphériques et troposphériques, ainsi que le bruit thermique récepteur et les erreurs dues aux multitrajets. Les exigences d’intégrité GNSS pour l’application télépéage sont ensuite dérivées à partir de la relation entre les erreurs de positionnement et leur effets dans la facturation finale. Deux algorithmes RAIM sont alors proposés pour l’application péage routier. Le premier est l’algorithme basé sur les résidus de la solution des moindres carrés pondérés (RAIM WLSR), largement utilisé dans l’aviation civile. Seulement, un des principaux défis de l’utilisation des algorithmes RAIM classiques en milieux urbains est un taux élevé d’indisponibilité causé par la mauvaise géométrie entre le récepteur et les satellites. C’est pour cela que un nouvel algorithme RAIM est proposé. Cet algorithme, basé sur le RAIM WLSR, est conçu de sorte à maximiser l’occurrence de fournir un positionnement intègre dans un contexte télépéage. Les performances des deux algorithmes RAIM proposés et des systèmes de télépéage associés sont analysés par simulation dans différents environnements ruraux et urbains. Dans tous les cas, la disponibilité du nouvel RAIM est supérieure à celle du RAIM WLSR<br>Global Navigation Satellite Systems (GNSS) integrity is defined as a measure of the trust that can be placed in the correctness of the information supplied by the navigation system. Although the concept of GNSS integrity has been originally developed in the civil aviation framework as part of the International Civil Aviation Organization (ICAO) requirements for using GNSS in the Communications, Navigation, and Surveillance / Air Traffic Management (CNS/ATM) system, a wide range of non-aviation applications need reliable GNSS navigation with integrity, many of them in urban environments. GNSS integrity monitoring is a key component in Safety of Life (SoL) applications such as aviation, and in the so-called liability critical applications like GNSS-based electronic toll collection, in which positioning errors may have negative legal or economic consequences. At present, GPS integrity monitoring relies on different augmentation systems (GBAS, SBAS, ABAS) that have been conceived to meet the ICAO requirements in civil aviation operations. For this reason, the use of integrity monitoring techniques and systems inherited from civil aviation in non-aviation applications needs to be analyzed, especially in urban environments, which are frequently more challenging than typical aviation environments. Each application has its own requirements and constraints, so the most suitable integrity monitoring technique varies from one application to another. This work focuses on Electronic Toll Collection (ETC) systems based on GNSS in urban environments. Satellite navigation is one of the technologies the directive 2004/52/EC recommends for the European Electronic Toll Service (EETS), and it is already being adopted: toll systems for freight transport that use GPS as primary technology are operational in Germany and Slovakia, and France envisages to establish a similar system from 2013. This dissertation begins presenting first the concept of integrity in civil aviation in order to understand the objectives and constraints of existing GNSS integrity monitoring systems. A thorough analysis of GNSS-based ETC systems and of GNSS navigation in urban environments is done afterwards with the aim of identifying the most suitable road toll schemes, GNSS receiver configurations and integrity monitoring mechanisms. Receiver autonomous integrity monitoring (RAIM) is chosen among other integrity monitoring systems due to its design flexibility and adaptability to urban environments. A nominal pseudorange measurement model suitable for integrity-driven applications in urban environments has been calculated dividing the total pseudorange error into five independent error sources which can be modelled independently: broadcasted satellite clock corrections and ephemeris errors, ionospheric delay, tropospheric delay, receiver thermal noise (plus interferences) and multipath. In this work the fault model that includes all non-nominal errors consists only of major service failures. Afterwards, the GNSS integrity requirements are derived from the relationship between positioning failures and toll charging errors. Two RAIM algorithms are studied. The first of them is the Weighted Least Squares Residual (WLSR) RAIM, widely used in civil aviation and usually set as the reference against which other RAIM techniques are compared. One of the main challenges of RAIM algorithms in urban environments is the high unavailability rate because of the bad user/satellite geometry. For this reason a new RAIM based on the WLSR is proposed, with the objective of providing a trade-off between the false alarm probability and the RAIM availability in order to maximize the probability that the RAIM declares valid a fault-free position. Finally, simulations have been carried out to study the performance of the different RAIM and ETC systems in rural and urban environments. In all cases, the availability obtained with the novel RAIM improve those of the standard WLSR RAIM
5
Hewitson, Steve Surveying & Spatial Information Systems Faculty of Engineering UNSW. "Quality control for integrated GNSS and inertial navigation systems." Awarded by:University of New South Wales. Surveying and Spatial Information Systems, 2006. http://handle.unsw.edu.au/1959.4/25534.
Testo completoAbstract (sommario):
The availability of GPS signals is a major limitation for many existing and potential applications. Fortunately, with the development of Galileo by the European Commission (EC) and European Space Agency (ESA) and new funding for the restoration of the Russian GLONASS announced by the Russian Federation the future for satellite based positioning and navigation applications is extremely promising. This research primarily investigates the benefits of GNSS interoperability and GNSS/INS integration to Receiver Autonomous Integrity Monitoring (RAIM) from a geometrical perspective. In addition to these investigations, issues regarding multiple outlier detection and identification are examined and integrity procedures addressing these issues are proposed. Moreover, it has been shown how the same RAIM algorithms can be effectively applied to the various static and kinematic navigation architectures used in this research.
6
Younes, Abdelrazak. "Théorie séquentielle appliquée au contrôle de l'intégrité du GNSS et à l'hybridation GNSS/INS." Toulouse, INPT, 2000. http://www.theses.fr/2000INPT044H.
Testo completoAbstract (sommario):
Un récepteur GPS (Système de Positionnement Global par satellite) permet à son utilisateur de connaître sa position et sa vitesse à tout moment et à tout endroit du globe. Malheureusement, le GPS ne peut satisfaire à lui seul les exigences de l'OACI (Organisation de l'Aviation Civile Internationale) pour devenir un moyen unique de navigation. Il doit être amélioré pour cela. Une des principales limitations du GPS est son intégrité. Celle-ci peut être améliorée grâce à une augmentation du GPS ou par son hybridation avec un autre système de navigation. Au niveau du récepteur GPS, un module RAIM (Receiver Autonomous Integrity Monitoring) est proposé pour effectuer le contrôle autonome de l'intégrité du système. Ce module se sert de la redondance inhérente aux mesures GPS pour s'assurer qu'aucune panne n'affecte la solution GPS de navigation. En cas de panne, le RAIM doit aussi pouvoir rapidement détecter cette panne et exclure le satellite qui est en cause. Il existe deux sortes de RAIMs : le RAIM Snapshot n'utilise que les mesures GPS instantanées alors que le RAIM Séquentiel se sert de toutes les mesures passées et présentes pour décider de l'intégrité du système. La géométrie des satellites utilisée pour la solution de navigation peut nuire à la détection et/ou l'isolation d'une panne. Dans ces cas de figure, des tests sur mesures réelles et des simulations montrent que le RAIM Séquentiel est beaucoup plus performant que le RAIM Snapshot. De cette capacité à fonctionner sous des conditions adverses, la disponibilité du GPS lorsqu'il est contrôlé par un RAIM Séquentiel est naturellement améliorée. Beaucoup d'avions civils intègrent un Système de Navigation Inertielle (INS). Grâce à leur grande complémentarité, l'hybridation des systèmes GPS et INS peut devenir un moyen unique de navigation pour certaines phases de vol. Dans ce système, il faut s'assurer que la solution GPS utilisée pour recaler la solution INS soit intègre. C'est ce que permet le RAIM Séquentiel grâce à ses qualités théoriques (vérifiées par simulations). Un schéma d'hybridation exploitant ces qualités est présenté.
7
Neri, Pierre. "Use of GNSS signals and their augmentations for Civil Aviation navigation during Approaches with Vertical Guidance and Precision Approaches." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0073/document.
Testo completoAbstract (sommario):
La navigation par satellite, Global Navigation Satellite System, a été reconnue comme une solution prometteuse afin de fournir des services de navigation aux utilisateurs de l'Aviation Civile. Ces dernières années, le GNSS est devenu l'un des moyens de navigation de référence, son principal avantage étant sa couverture mondiale. Cette tendance globale est visible à bord des avions civils puisqu'une majorité d'entre eux est désormais équipée de récepteurs GNSS. Cependant, les exigences de l'Aviation Civile sont suffisamment rigoureuses et contraignantes en termes de précision de continuité, de disponibilité et d'intégrité pour que les récepteurs GPS seuls ne puissent être utilisés comme unique moyen de navigation. Cette réalité a mené à la définition de plusieurs architectures visant à augmenter les constellations GNSS. Nous pouvons distinguer les SBAS (Satellite Based Augmentation Systems), les GBAS (Ground Based Augmentation Systems), et les ABAS (Aircraft Based Augmentation Systems). Cette thèse étudie le comportement de l'erreur de position en sortie d'architectures de récepteur qui ont été identifiées comme étant très prometteuses pour les applications liées à l'Aviation Civile<br>Since many years, civil aviation has identified GNSS as an attractive mean to provide navigation services for every phase of flight due to its wide coverage area. However, to do so, GNSS has to meet relevant requirements in terms of accuracy, integrity, availability and continuity. To achieve this performance, augmentation systems have been developed to correct the GNSS signals and to monitor the quality of the received Signal-In-Space (SIS). We can distinguish GBAS (Ground Based Augmentation Systems), ABAS (Airborne Based Augmentation Systems) SBAS (Satellite Based Augmentation Systems). In this context, the aim of this study is to characterize and evaluate the GNSS position error of various positioning solutions which may fulfil applicable civil aviation requirements for GNSS approaches. In particular, this study focuses on two particular solutions which are: • Combined GPS/GALILEO receivers augmented by RAIM where RAIM is a type of ABAS augmentation. This solution is a candidate to provide a mean to conduct approaches with vertical guidance (APV I, APV II and LPV 200). • GPS L1 C/A receivers augmented by GBAS. This solution should allow to conduct precision approaches down to CAT II/III, thus providing an alternative to classical radio navigation solutions such as ILS. This study deals with the characterization of the statistics of the position error at the output of these GNSS receivers. It is organised as following. First a review of civil aviation requirements is presented. Then, the different GNSS signals structure and the associated signal processing selected are described. We only considered GPS and GALILEO constellations and concentrated on signals suitable for civil aviation receivers. The next section details the GNSS measurement models used to model the measurements made by civil aviation receivers using the previous GNSS signals. The following chapter presents the GPS/GALILEO and RAIM combination model developed as well as our conclusions on the statistics of the resulting position error. The last part depicts the GBAS NSE (Navigation System Error) model proposed in this report as well as the rationales for this model
8
Perea, Diaz Santiago Verfasser], Michael [Akademischer Betreuer] [Meurer, Boris [Akademischer Betreuer] Pervan, and Jens-Rainer [Akademischer Betreuer] Ohm. "Design of an integrity support message for offline advanced RAIM / Santiago Perea Diaz ; Michael Meurer, Boris Pervan, Jens-Rainer Ohm." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1194239242/34.
Testo completo
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Martineau, Anaïs. "Étude de la performance du contrôle autonome d'intégrité pour les approches à guidage vertical." Toulouse, INPT, 2008. http://ethesis.inp-toulouse.fr/archive/00000984/.
Testo completoAbstract (sommario):
Afin de répondre aux exigences opérationnelles de l'aviation civile, les systèmes de navigation par satellite requièrent l'appui de moyens d'augmentation tels que ceux utilisant des stations de surveillance sol ou ceux fonctionnant de manière autonome, tel le RAIM (Receiver Autonomous Integrity Monitoring). Cette méthode engendre des coûts de mise en oeuvre réduits et constitue à l'heure actuelle un moyen simple et efficace d'effectuer des approches de non précision. Or la future mise en place du système de navigation européen Galileo ainsi que la modernisation du système historique américain GPS vont entrainer une nette amélioration, à la fois en terme de nombre et de qualité, des mesures satellitaires disponibles, laissant entrevoir la possible utilisation du RAIM pour des approches à guidage vertical, très intéressantes du point de vue opérationnel. Cette étude porte sur l'évaluation des performances du RAIM qu'il soit basé sur des algorithmes classiques ou innovants<br>To ensure civil aviation requirements different architectures are defined to augment basic Global Navigation Satellite System constellations. Among them, Receiver Autonomous Integrity Monitoring (RAIM) is a simple and efficient solution to check the integrity down to Non Precision Approaches. The future introduction of Galileo and modernized GPS will imply great improvements in the number and in the quality of available measurements. Thus, more demanding phases of flight such as approaches with vertical guidance could be targeted using classical or new RAIM techniques to provide integrity monitoring. The goal of this thesis is to carefully evaluate the RAIM resulting performance, as more available measurements also implies a larger number of potential faulty measurements. Moreover, the targeted phases of flight are also characterized by more stringent requirements resulting in smaller threatening range errors to be detected
10
Norris, Natasha Louise. "Implementation of Multi-Constellation Baseline Fault Detection and Exclusion Algorithm Utilizing GPS and GLONASS Signals." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1535028817622931.
Testo completo
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Silva, Marco Antônio Lima da. "Avaliação arqueo-espeleológica das cavernas da Raiz, Raio, Onça e Batismo do município de Presidente Figueiredo - Amazonas." Universidade Federal do Amazonas, 2007. http://tede.ufam.edu.br/handle/tede/3263.
Testo completoAbstract (sommario):
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Dissertacao_Marco Antonio.pdf: 19449044 bytes, checksum: b24ff32d320c539ad7d1f8b8e6c8a2db (MD5)
Previous issue date: 2007-02-02<br>FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas<br>The pre-colonial human occupations of Amazônia have been outlined (highlighted) in the worldwide literature in the last decades, emphasizing mainly open archeological sites. Detailed studies with this emphasis in caves are restricted to the Monte Alegre region, State of Pará, northern Brazil. The geoarcheology analysis of caves of Uatumã-Abonari Speleologic Province located in the Presidente Figueiredo e Balbina districts, Northeast of Statet of Amazonas, allowed characterized vestiges of pre-colonial human occupations in this part of Amazonia. The caves were developed in Silurian (420 Ma) quartz-arenites of Nhamundá Formation and
include morphologic features as saloon, galleries, quartz speleotems, abandoned conduits (pipes) generally
beheaded in fractures plains. The uplift phenomena, pseudokarstic relief dissection and ground waters
hydrodynamic favored the chemical dissolutions and mechanic dismantling, following a sanding/pipe model,
generating the caves during the Quaternary. The evidences of human occupation in the Raiz, Raio, Onça e
Batismo caves, with probable age of 800 years, are predominantly undecorated fragments ceramics and
rupestrial paintings. The caves were used as temporary shelters probably for hunting activities, and rarely for
ritualistic ceremonials. Nowadays, the caves are in continuous processes of depredation due the uncontrolled
tourism and the ignorance of the local population about the meaning and importance of this cultural patrimony.
This study demonstrated this importance and can be a guide to future works which use the geology and
archaeology in the reconstitution of the history of the human occupation in the Amazônia.<br>mundial nas últimas décadas, enfocando principalmente sítios arqueológicos abertos, mas restritos contudo à região de Monte Alegre, Estado do Pará. Cavernas e abrigos na porção
central da Amazônia, por outro lado, ainda estão longe de estudos mais detalhados. A análise geoarqueológica de cavernas e abrigos da Província espeleológica Uatumã-Abonari,
localizadas no município de Presidente Figueiredo e distrito de Balbina, nordeste do Estado do Amazonas, permitiu caracterizar vestígios de ocupação humana pré-colonial nesta parte da Amazônia. As cavernas foram desenvolvidas em quartzarenitos silurianos (420 Ma) da Formação Nhamundá, que incluem feições morfológicas como salões, galerias, espeleotemas de quartzo, condutos abandonados (pipes) geralmente encaixados em planos de fraturas. Os
fenômenos de soerguimento, dissecação do releva pseudocárstico e hidrodinâmica do lençol freático favoreceram os processos de dissolução e desmantelamento mecânico, seguindo um modelo tipo sanding/pipe gerando as cavernas durante o Quaternário. As evidências de ocupação humana nas cavernas da Raiz, do Raio, da Onça e do Batismo, com idade provável de 800 anos, são fragmentos cerâmicos predominantemente não decorados e pinturas
rupestres. As cavernas serviram como abrigos temporários provavelmente para atividades de caça e, raramente, para fins ritualísticos. Atualmente as cavernas passam por um processo de depredação em função do turismo descontrolado e da falta de conscientização da população
local quanto ao significado e à importância desse patrimônio cultural. Este estudo demonstrou esta importância e pretende guiar futuros trabalhos que envolvam a geologia e
arqueologia na reconstituição da história da ocupação humana da Amazônia.
12
Yüksel, Gökçen. "Raum." Universität Leipzig, 2018. https://ul.qucosa.de/id/qucosa%3A32556.
Testo completoAbstract (sommario):
In den wissenschaftlichen Disziplinen der Mathematik, Physik, Philosophie, Geschichte und der Geografie ist der Raum sowohl als Untersuchungsgegenstand als auch als Analyseinstrument von zentralem Interesse. Er kann als soziales Phänomen und Produkt sozialer Praktiken und Handlungen gelten. Theoretische Annahmen solcher Art qualifizieren Raum als analytische Kategorie und sorgen für seine Anschlussfähigkeit an die Geschlechterdifferenzierungsforschung sowie die Gender und Queer Studies. In den Fokus gerät dabei die Interdependenz von Raum- und Geschlechterordnungen.
13
Sigismund, Markus. "Mehr Raum für den Raum in der Mobilitätsforschung." Rhombos-Verlag, 2017. https://slub.qucosa.de/id/qucosa%3A21297.
Testo completoAbstract (sommario):
Das Bundesministerium für Verkehr und digitale Infrastruktur (BMVI) etabliert im Geschäftsbereich mit Bausteinen wie der Geoinformationsstrategie, der mCLOUD (Rechercheplattform) und dem mFUND (Modernitätsfond) eine neue, offene Datenkultur und leistet mit der Bereitstellung von Verwaltungsdaten und der Erschließung neuer Datenquellen einen wichtigen Beitrag zur Open-Data-Strategie der Bundesregierung. Die hier dargestellten „klassischen“ Mobilitätserhebungen, Forschungsprojekte und amtlichen Daten verlieren in diesem Umfeld jedoch nicht an Wert. Im Gegenteil: Sie sind die wichtigste empirische Grundlage für die Verkehrsplanung und Mobilitätsforschung. Sie sind auch Grundlage zur Eichung der neuen Datenwelten wie z. B. Big Data und Verwaltungsdaten und damit deren Wertschöpfungspotenzial. Zwischen diesen Datenwelten der Mobilitätsforschung und Verkehrsplanung nehmen
siedlungsstrukturelle Raumtypisierungen eine zentrale Scharnierfunktion ein. Um diese Scharnierfunktion zu verbessern, hat das BMVI einen Anforderungskatalog definiert und das Bundesinstitut für Bau-, Stadt- und Raumforschung (BBSR) mit einer Operationalisierung neuer Raumtypen beauftragt. Diese werden vor allem auch benötigt, um die Mobilität erklären zu können: die wichtigsten Veränderungen der Mobilität werden erst erkennbar, wenn unter der bundesweit ruhigen Oberfläche, d. h. mit nahezu unveränderten Mobilitätskennwerten auf Bundesebene, systematisch räumliche Unterschiede identifiziert werden können. Deshalb gibt das BMVI raumbezogenen Daten mehr Raum. Das BMVI wirbt dafür, dass auch die amtliche Statistik eine Raumtypisierung in das Standardveröffentlichungsprogramm übernimmt und empfiehlt die neue Raumtypisierung als Diskussionsgrundlage an.
14
Welsh, Clare. "Tin Rain." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2575.
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Tyfield, David. "Desert rain." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12298.
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Kjellberg, Andreas. "An Exploratory Comparison of B-RAAM and RAAM Architectures." Thesis, University of Skövde, Department of Computer Science, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-816.
Testo completoAbstract (sommario):
<p>Artificial intelligence is a broad research area and there are many different reasons why it is interesting to study artificial intelligence. One of the main reasons is to understand how information might be represented in the human brain. The Recursive Auto Associative Memory (RAAM) is a connectionist architecture that with some success has been used for that purpose since it develops compact distributed representations for compositional structures.</p><p>A lot of extensions to the RAAM architecture have been developed through the years in order to improve the performance of RAAM; Bi coded RAAM (B-RAAM) is one of those extensions. In this work a modified B-RAAM architecture is tested and compared to RAAM regarding: Training speed, ability to learn with smaller internal representations and generalization ability. The internal representations of the two network models are also analyzed and compared. This dissertation also includes a discussion of some theoretical aspects of B-RAAM.</p><p>It is found here that the training speed for B-RAAM is considerably lower than RAAM, on the other hand, RAAM learns better with smaller internal representations and is better at generalize than B-RAAM. It is also shown that the extracted internal representation of RAAM reveals more structural information than it does for B-RAAM. This has been shown by hieratically cluster the internal representation and analyse the tree structure. In addition to this a discussion is added about the justifiability to label B-RAAM as an extension to RAAM.</p>
17
Soenneker, Richard (Richard Joseph) 1978. "Design of a bipolar rail-to-rail operational amplifier." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86734.
Testo completoAbstract (sommario):
Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.<br>Includes bibliographical references (leaves 66-67).<br>by Richard Soenneker.<br>M.Eng.and S.B.
18
Hudzik, Martin. "Návrh Rail-to-Rail proudového konvejoru v technologii CMOS." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242143.
Testo completoAbstract (sommario):
Master’s thesis deals with design of rail-to-rail second generation current conveyor in CMOS technology. Describes principles of function of different generations of current conveyors, as well as the basic principle of design of second generation current conveyor based on operational amplifier. Addresses circuit topology of input rail-to-rail stage and class AB output stage. The objective of this thesis is to design, characterize performance and create layout of second generation current conveyor with input common mode voltage rail-to-rail capability in ONSemi I3T25 technology.
19
Holmlund, Gabriel. "RFID in Rail : RFID tracing of rail-borne cargo." Thesis, Mittuniversitetet, Avdelningen för informations- och kommunikationssystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-25824.
Testo completoAbstract (sommario):
SCA transports timber via rail from railway terminals in western Sweden to saw and/or pulp mills located on the east coast. Sometimes timber wagons are lost due to damages inflicted when loading the wagon. Wagons can also be decommissioned for maintenance conducted by the Swedish Transport Administration. Both situations are unpredictable and causes many types of problems. If the wagons could be automatically traced these problems could be predicted and pre-emptive actions could be taken. All wagons used by SCA are equipped with RFID tags and RFID readers are installed at the railway terminals. The purpose of this thesis is to equip the RFID readers with Internet access, collect the data read by the RFID readers and present this data in a single page web application. The actual data collection is done by an already existing system which pushes the train data to the back-end part of the application. The front-end part is made with a JavaScript framework named Ember.js and the back-end part is made with ASP .NET Web API and SQL Server. The application is finished and verified with various tests but is not put in production due to a negotiation delay between SCA with a third-party consultant.
20
Raij, Katariina. "Toward a profession : clinical learning in a hospital environment as described by student nurses." Helsinki : University of Helsinki, 2000. http://ethesis.helsinki.fi/julkaisut/kas/kasva/vk/raij/.
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Muppalaneni, Nitin. "Adaptive Hierarchial RAID." Thesis, Indian Institute of Science, 1998. http://hdl.handle.net/2005/50.
Testo completoAbstract (sommario):
Redundant Arrays of Inexpensive Disks or RAID is a popular method of improving the reliability and performance of disk storage. Of various levels of RAID, mirrored or RAID1 and rotating parity or RAID5 configurations have become moat popular. Mirrored or RAID1 provides best overall performance and is easier to configure, but has 100 percent storage overhead for the redundancy. Rotating parity or RAID5, on the other hand, is quite inexpensive for the redundancy it provides, shorn impressive performance for reads and full-stripe writes in normal mode, but the small write performance is poor due to the read-modify-write cycle involved. The performance drops drastically when one of the disks fails and the system enters degraded mode. Also RAID5 is relatively difficult to configure.
Typical non-scientific system disk access patterns exhibit very high locality of reference. This thesis presents the design and implementation of an Adaptive Hierarchical RAID array to exploit this high locality. Frequently accessed data is migrated towards the top of the hierarchy and not so frequently acee88ed data is moved down the hierarchy, thus adaptively rearranging itself to the access patterns.
Previous work on Adaptive Hierarchical RAID such as HP AutoRAID has explored one part of the design space, namely design of configurable storage at the SGSI level with no interaction with higher level layers like volume manager. This thesis explores a different design point: namely, one that is centered at the volume manager layer. This is important also for the reason that with fibre channel disks and SCSI-3, Storage Area Networks (SAN) no longer need a conventional controller but a modified version of a controller that is more close to a volume manager.
22
Kumagai, Emiko. "Zeit-Spiel-Raum." Diss., lmu, 2004. http://nbn-resolving.de/urn:nbn:de:bvb:19-37087.
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Norris, Patrick B. "Ronald Reagan Rain." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/830.
Testo completoAbstract (sommario):
RONALD REAGAN RAIN is a collection of poems that explore the wildness and terror lurking beneath the surface of contemporary suburban landscapes in a largely imagined America. Images of menacing policemen, bears, fast food restaurants, and dead film stars appear as substantive figures that embody loss and a preoccupation with aging, money woes, and a failed national confidence. Influenced by Russel Edson and Georg Trakl, poets whose work is characterized by Hermeticism and Expressionism, the poems in RONALD REAGAN RAIN suggest a similar dual need for autonomy and compromise in both highly charged poetic fragments and longer prose passages that examine issues of civil and personal estrangement as the outside world calls for constant introspection and reassessments of identity.
24
Orvnäs, Anneli. "Simulation of Rail Wear on the Swedish Light Rail Line Tvärbanan." Thesis, KTH, Spårfordon, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-26310.
Testo completoAbstract (sommario):
Rail wear can result in extensive costs for the track owner if it is not predicted and preventedin an efficient way. To limit these costs, one measure is to predict rail wear through wear simulations. The purpose with this work is to perform simulations of successive rail wear on the Swedish light rail line Tvärbanan in Stockholm, by means of the track-vehicle dynamics software GENSYS in combination with a wear calculation program developed in MATLAB. The simulation procedure is based on a methodology with a simulation set design, where the simulations to be performed are selected through a parametric study. The simulations include track-vehicle simulations, where the wheel-rail contact is modelled according to the Hertzian contact theory together with Kalker’s simplified theory (including the numerical algorithm FASTSIM). The results from the track-vehicle simulations serve as input to the wear calculations. When modelling rail wear Archard’s wear model has been used, including wear coefficients based on laboratory measurements. The measurements have been performed under dry conditions, so the wear coefficients under lubricated conditions (both natural and deliberate lubrication) are reduced by factors estimated by field observations. After the wear depth calculations the wear distribution is smoothed and the rail profile is updated. The simulation procedure continues with a new wear step as long as the desired tonnage is not attained. Four curves of Tvärbanan with different curve radii, ranging from 85 to 410 m, have beenstudied in this work. On three of the curves the high rail is deliberately lubricated, whereas no lubrication has been applied in the widest curve. The vehicle operating the light rail line is an articulated tram with two motor end bogies and one intermediate trailer bogie. The line was opened in August 1999 and extended in one direction one year later. Rail profile measurements have been carried out by SL since March 2002. The traffic tonnage at the selected sites from the opening of the line to the last measurement occasion (September2004) is at most 8.9 mega gross ton per track. The results of the rail wear prediction tool are evaluated by comparing worn-off area of the simulated rail profiles with that of the measured rail profiles. Simulated and measured resultsdo not agree too well, since the simulated rail wear is more extensive than the measured one, especially on the outer rail. However, the shapes of the simulated worn rail profiles are comparable to those of the measured rail profiles.<br>QC 20101123
25
Murty, Anjali. "Highly linear, rail-to-rail ICMR, low voltage CMOS operational amplifer." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/14884.
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Pang, Tao, and tony_pang@hotmail com. "Studies on Wheel/Rail Contact Impact Forces at Insulated Rail Joints." Central Queensland University. Centre for Railway Engineering, 2008. http://library-resources.cqu.edu.au./thesis/adt-QCQU/public/adt-QCQU20080410.154708.
Testo completoAbstract (sommario):
To investigate the wheel/rail contact impact forces at insulated rail joints (IRJs), a three-dimensional finite element model and strain gauged experiments are employed and reported in this thesis. The 3D wheel/rail contact-impact FE model adopts a two-stage analysis strategy in which the wheel-IRJ railhead contact is first established in the static analysis and the results transferred to dynamic analysis for impact simulations. The explicit FE method was employed in the dynamic analysis. The Lagrange Multiplier method and the Penalty method for contact constraint enforcement were adopted for the static and dynamic analyses respectively.
The wheel/rail contact-impact in the vicinity of the end post is exhibited via numerical examples from the FE modelling. The wheel/rail contact impact mechanism is investigated. The strain gauged experiments which consist of a lab test and a field test are reported. The signature of the strain time series from the field test demonstrates a plausible record of the dynamic responses due to the wheel/rail contact impact. By using the experimental data, both the static and the dynamic FE models are validated.
It is found that the stiffness discontinuity of the IRJ structure causes a running surface geometry discontinuity during the wheel passages which then causes the impact in the vicinity of the end post. Through a series of sensitivity studies of several IRJ design parameters, it is shown that the IRJ performance can be effectively improved with optimised design parameters.
27
Morris, John D. (John David) 1978. "Improving toggle rate in a rail-to-rail comparator output stage." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/16854.
Testo completoAbstract (sommario):
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.<br>Includes bibliographical references.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>The demand for high-speed components has driven an increase in the speed of analog comparators, a building block for many analog circuits. This paper describes the modification of one of Linear Technology's low-cost, high-speed comparators to increase the output toggle rate beyond the one hundred megahertz range. The essential modifications to the output stage mainly relate to overcoming quasi-saturation of the output devices by extracting unwanted, stored base charge. Additional features were added into a dual comparator package with a tiny footprint to increase consumer interest and to diversify it from other comparators in Linear Technology's line. A final circuit design and physical silicon layout were designed using computer design tools, and the IC was fabricated and tested. The first silicon was tested extensively and worked successfully with only minor undesired discrepancies that were deemed acceptable. The LT1715 design was successful since the design itself accomplished all the desired specifications and the part is now available for sale.<br>by John D. Morris.<br>M.Eng.
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Cruvinel, Paulo Estevão. "Minitomografo de raio-X e raio-gama computadorizado para aplicações multidisciplinares." [s.n.], 1987. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260480.
Testo completoAbstract (sommario):
Orientadores: Sergio Mascarenhas Oliveira , Maria Adelia Collier Farias<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica<br>Made available in DSpace on 2018-07-16T20:28:29Z (GMT). No. of bitstreams: 1
Cruvinel_PauloEstevao_D.pdf: 22993747 bytes, checksum: 337eb576c9ed432c9c3f27cc8f869914 (MD5)
Previous issue date: 1987<br>Resumo: Esta tese tem como principal resultado o desenvolvimento e a implementação de um minitomógrafo de raio-X e Raio-Y computadorizado com possibilidades de aplicações em campos multidisciplinares e em particular a estudos em Física de Solos. Tal sistema é basicamente constituído por uma mesa mecânica com dois motores de passo para movimentos de rotação e translação, fonte radioativa, colimadores, detector com cristal de NaI(Te), cadeia de detecção nuclear, interface e microcomputador com duas unidades de disco flexível de 5 1/4", video de alta resolução e impressora gráfica. O sistema, após funcionamento e avaliações quantitativas, mostrou-se apropriado às aplicações mencionadas. Utilizando-se do conceito de,função transferência de contraste (CTF) foram obtidas, quantitativamente, informaçoes quanto à resolução espacial e qualidade das imagens. Tal estudo, feito com fonte de raio-y (241Am) mostra que as imagens obtidas com tamanho de pixel de 1mm e largura do feixe de fótons de 1,2mm são de boa qualidade e, os resultados, com contagens da ordem de 10000, mostratam qualitativamente um adequado contraste da imagem. Os programas computacionais, isto é, MTACCON, MTACREC e MTACSEC, desenvolvidos em' linguagem Pascal, são respectivamente utilizados para controle e aquisição de dados, reconstrução da imagem com algoritmo de retroprojeção filtrada e visualização da secção reconstruída com possibilidades de análise quantitativa do coeficiente de atenuação linear ao longo da imagem...Observação: O resumo, na integra, poderá ser visualizado no texto completo da tese digital<br>Abstract: The main result of this thesis is the development, implementation and use of an X-ray and y-ray computerized minitomography scanner with possible applications in multidisciplinary fields particularly in soil physics. The hardware is basically a mechanical table with two step motors, one for rotation and another for translation motions, radioactive,source, collimators, radiation detector with NaI(Te) chrystal, electronic pulse handling system and microcomputer with two floppy disk-units (5 1/4"), video with
high resolution and graphic printer. Using the concept of Contrast Transfer Function (CTF) we obtained quantitative information on the spatial resolution and image quality of the system. This study using a y-ray source (241Am) demostrates that the images obtained with pixel widths of 1mm and photon beam radii of 1,2mm have good quality as evaluated quantitatively by the CTF. On the other hand, results with a total of 10000 photons counts' showed adequate image, contrast The computational programs were all developed
in Pascal language. They are used respectively for control and data collection (MTACCON), image reconstruction with filtered backprojection algorithms (MTACREC) and to show in the video the slice with possibility of quantitative analysis of the linear attenuation coefficient at any chosen region (MTACSEC)...Note: The complete abstract is available with the full electronic digital thesis or dissertations<br>Doutorado<br>Automação<br>Doutor em Engenharia Elétrica
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Naini, Srikar Reddy. "PING-PONG AUTO-ZERO AMPLIFIER WITH RAIL-TO-RAIL OUTPUT BUFFER." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1537224512595497.
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Kumar, Saurabh. "A study of the rail degradation process to predict rail breaks." Licentiate thesis, Luleå tekniska universitet, Drift, underhåll och akustik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18226.
Testo completoAbstract (sommario):
Rail infrastructure is a large and costly investment, and has a long life. To realize the benefits from this investment, effective maintenance is required. Railways are one of the prime modes of transportation in many countries and as they are closely associated with passenger and cargo transportation, they own high risk in terms of potential loss of human life and damage/destruction of assets. New technologies and stringent safety standards are constantly being introduced, but accidents still occur. There will always be some risk associated with derailments and collisions, but it can be reduced by elimination of the root causes by means of an effective maintenance strategy to govern optimization of inspection, lubrication and grinding frequency and/or improvement in skill and efficiency. A detailed study of the defects which emerge both in the rolling stock and the rail infrastructure is essential to identify the correct maintenance strategy. Detection and rectification of rail defects/degradations are major issues for all rail players around the world. Some of the rail degradations include worn out rails, weld problems, internal defects, corrugations and rolling contact fatigue (RCF) initiated problems such as surface cracks, head checks, squats, spalling and shelling. If undetected and/or untreated, these defects can lead to rail breaks and derailments. Efficient maintenance strategies can reduce potential risk of rail breaks and derailments. A potential risk is the risk which accumulates in the form of rail degradation over a period of time. In spite of continuous efforts made by all rail infrastructure operators around the world to reduce costs, a substantial proportion of railway budget is spent on rail maintenance. It is understood that the consequential costs due to derailment reduces with increase in inspection, lubrication, grinding and replacement costs. The challenge is to find a balance between the maintenance costs which consists of inspection, lubrication and grinding costs, and consequential costs due to derailments. The consequences of derailment in terms of loss of human life, damage/destruction of assets and loss of company trust and reputation justify maintaining stringent safety standards, which require massive rail maintenance investments in order to be met. Reduction in maintenance investments may increase the rate of rail degradation, which may increase the risk of derailments. The aim is to develop an approach to predict rail failures, which will help to optimize maintenance activities (inspection, grinding, rectification/replacement and/or welding). Generally, there is a trade-off between maintenance investment and the risk involved in rail degradation in order to develop a rail maintenance procedure. Failure prediction of rail sections undergoing degradation will help to estimate the risk of derailment. Thus, prediction of the rail failure rate is a requirement for the development of an effective rail maintenance procedure. Different types of rail degradation processes leading to various rail defects have been studied. The performed literature studies indicate a need for better prediction of rail failure over a period of time based on the factors influencing rail degradation. The maintenance strategy followed by the Swedish National Rail Administration (Banverket), Sweden's rail infrastructure operator, is described and the issues related to rail degradation and maintenance are outlined for further research in this area. Rail failure data has been extracted from different Banverket's databases, classified according to a classification framework developed and analyzed over a period of time based on Million Gross Tonnes (MGT) of traffic using Weibull distribution. During the process of data evaluation and analysis, a method of extracting useful information from incomplete data has been identified.<br><p>Godkänd; 2006; 20061212 (ysko)</p>
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Hirsch, Vanessa. "Malerei und Installation bei Robert Irwin : vom Bild-Raum zum Raum-Bild /." Berlin : Mann, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016330559&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Kamura, Eri. "Exploring the Methylation Status of RAI1 and the RAI1 Consensus Binding Sequence." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1891.
Testo completoAbstract (sommario):
Smith Magenis Syndrome (SMS) is a multiple congenital anomalies/ mental retardation disorder caused by deletion or mutation of the RAI1 gene on chromosome 17p11.2. The majority of patients with SMS phenotypes have a deletion or mutation of RAI1. However, some patients have been observed with SMS-like phenotypes and yet have no deletions or mutations in the RAI1 gene. One possible explanation could be aberrant methylation of RAI1 since RAI1 is present and yet may be silenced. In order to study this possibility, patient cell lines were treated with 5-Aza-2’-deoxycytidine. RNA was extracted and real-time PCR was used to check the RAI1 expression status on the cells. RAI1 is thought to be a transcription factor, but the DNA binding sequence is still unknown. Sequences from ChIP-chip data were compared to identify a consensus sequence. One gene which contained this consensus sequence was the chemokine-like receptor-1 gene (CMKLR1), which was investigated by luciferase assay. CMKLR1 showed upregulation when co-transfected with RAI1.
33
Ewert, A. Erhardt. "Formularservice im kreisangehörigen Raum." Universität Potsdam, 2003. http://opus.kobv.de/ubp/volltexte/2007/1574/.
Testo completoAbstract (sommario):
Einleitung: Verwaltungsorganisationen stehen vor der Herausforderung, ihre Strukturen, Funktionen und Leistungen auf die Anforderungen der Informationsgesellschaft einzustellen. Für die Gestaltung von eGovernment sieht sich die Kreisverwaltung Potsdam-Mittelmark mit der Gegenwarts- und Zukunftsaufgabe konfrontiert, die knappen finanziellen Ressourcen effizient und wirkungsvoll einzusetzen. Der Kreis und seine angehörigen Gemeinden sollen im Standortwettbewerb bestehen können. Um der Abwanderung aus ländlichen Regionen entgegenzuwirken, sollten Kommunen für den Bürger und die Wirtschaft attraktiv gestaltet sein. Unternehmen beziehen längst in ihre Standortwahl den Faktor Leistungsfähigkeit der Verwaltung mit ein. Der Landkreis Potsdam-Mittelmark versucht mit einem mehrstufigen Entwurf einer integrierten Kommunalverwaltung, Dienstleistungen bürgernah anzubieten. In der ersten Phase sollen gemeindliche Bürgerbüros Kreisleistungen in der Fläche anbieten. Dies erfolgt technikunterstützt auf der Basis eines Virtual Privat Network (VPN), an das die Kreisverwaltung sowie die Stadt-, Amts- und Gemeindeverwaltungen angebunden sind. Auf der Grundlage der im gesicherten VPN gesammelten Erfahrungen werden Online-Dienstleistungen via Internet angeboten. Der Bürger soll die Art der Kontaktaufnahme mit der Verwaltung wählen und während des jeweiligen Verfahrens wechseln können. Der Zugang zu Verwaltungsprozessen wird auch zukünftig in erster Linie über Formulare erfolgen, allerdings in elektronischer Form. Ob der Mitarbeiter des Bürgerbüros oder der Bürger via heimischem PC - über das Internet werden über ein Formularportal Zugriffe auf die notwendigen Formulare und die damit verbundenen Informationen möglich. Das vorliegende Konzept umfasst eine Zusammenstellung organisatorischer und technischer Überlegungen. Es definiert Grundanforderungen, die an ein integriertes Formularportal gestellt werden. Abschließende Aussagen zu einem konkreten Produkt "Formularportal" können noch nicht getroffen werden. Dazu bedarf es u.a. der Analyse der Fachverfahren hinsichtlich einer möglichen Webintegration. Soll ein Formularportal über die reine Downloadfunktionalität hinaus gehen, setzt dies enorme Veränderungen im Bereich der Verfahrensschnittstellen und der Middleware voraus. Die damit verbundenen Aufwendungen übersteigen die Leistungsfähigkeit der einzelnen Gemeinden. Sinnvoll für die Erfüllung dieser Aufgabe wäre eine Verantwortlichkeit des Landkreises, für die Gemeinden aktiv zu werden. Das Konzept "Formularportal" stellt kein fertiges Papier dar. Es ist als Diskussionsgrundlage zu verstehen und soll mithilfe der Anregungen aus Theorie und Praxis, aus der Verwaltung und durch Anbieter technischer Lösungen kritisch diskutiert und fortgeschrieben werden.
34
Leuenberger, Lorenz. "Schwebender Raum - Limmatplatz Zürich." Zürich : ETH, Eidgenössische Technische Hochschule Zürich, Departement Architektur, 2006. http://e-collection.ethbib.ethz.ch/show?type=dipl&nr=273.
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Telliskivi, Tanel. "Wheel-rail Interaction Analysis." Doctoral thesis, KTH, Machine Design, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3532.
Testo completoAbstract (sommario):
<p>A general approach to numerically simulating wear in rollingand sliding contacts is presented in this thesis. A simulationscheme is developed that calculates the wear at a detailedlevel. The removal of material follows Archards wear law,which states that the reduction of volume is linearlyproportional to the sliding distance, the normal load and thewear coefficient. The target application is the wheel-railcontact.</p><p>Careful attention is paid to stress properties in the normaldirection of the contact. A Winkler method is used to calculatethe normal pressure. The model is calibrated either withresults from Finite Element simulations (which can include aplastic material model) or a linear-elastic contact model. Thetangential tractions and the sliding distances are calculatedusing a method that incorporates the effect of rigid bodymotion and tangential deformations in the contact zone.Kalkers Fastsim code is used to validate the tangentialcalculation method. Results of three different sorts ofexperiments (full-scale, pin-on-disc and disc-on-disc) wereused to establish the wear and friction coefficients underdifferent operating conditions.</p><p>The experimental results show that the sliding velocity andcontact pressure in the contact situation strongly influencethe wear coefficient. For the disc-on-disc simulation, therewas good agreement between experimental results and thesimulation in terms of wear and rolling friction underdifferent operating conditions. Good agreement was alsoobtained in regard to form change of the rollers. In thefull-scale simulations, a two-point contact was analysed wherethe differences between the contacts on rail-head to wheeltread and rail edge to wheel flange can be attributed primarilyto the relative velocity differences in regard to bothmagnitude and direction. Good qualitative agreement was foundbetween the simulated wear rate and the full-scale test resultsat different contact conditions.</p><p><b>Keywords:</b>railway rail, disc-on-disc, pin-on-disc,Archard, wear simulation, Winkler, rolling, sliding</p>
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Li, Yan. "Scalability of RAID systems." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/3382.
Testo completoAbstract (sommario):
RAID systems (Redundant Arrays of Inexpensive Disks) have dominated backend storage systems for more than two decades and have grown continuously in size and complexity. Currently they face unprecedented challenges from data intensive applications such as image processing, transaction processing and data warehousing. As the size of RAID systems increases, designers are faced with both performance and reliability challenges. These challenges include limited back-end network bandwidth, physical interconnect failures, correlated disk failures and long disk reconstruction time. This thesis studies the scalability of RAID systems in terms of both performance and reliability through simulation, using a discrete event driven simulator for RAID systems (SIMRAID) developed as part of this project. SIMRAID incorporates two benchmark workload generators, based on the SPC-1 and Iometer benchmark specifications. Each component of SIMRAID is highly parameterised, enabling it to explore a large design space. To improve the simulation speed, SIMRAID develops a set of abstraction techniques to extract the behaviour of the interconnection protocol without losing accuracy. Finally, to meet the technology trend toward heterogeneous storage architectures, SIMRAID develops a framework that allows easy modelling of different types of device and interconnection technique.Simulation experiments were first carried out on performance aspects of scalability. They were designed to answer two questions: (1) given a number of disks, which factors affect back-end network bandwidth requirements; (2) given an interconnection network, how many disks can be connected to the system. The results show that the bandwidth requirement per disk is primarily determined by workload features and stripe unit size (a smaller stripe unit size has better scalability than a larger one), with cache size and RAID algorithm having very little effect on this value. The maximum number of disks is limited, as would be expected, by the back-end network bandwidth. Studies of reliability have led to three proposals to improve the reliability and scalability of RAID systems. Firstly, a novel data layout called PCDSDF is proposed. PCDSDF combines the advantages of orthogonal data layouts and parity declustering data layouts, so that it can not only survivemultiple disk failures caused by physical interconnect failures or correlated disk failures, but also has a good degraded and rebuild performance. The generating process of PCDSDF is deterministic and time-efficient. The number of stripes per rotation (namely the number of stripes to achieve rebuild workload balance) is small. Analysis shows that the PCDSDF data layout can significantly improve the system reliability. Simulations performed on SIMRAID confirm the good performance of PCDSDF, which is comparable to other parity declustering data layouts, such as RELPR. Secondly, a system architecture and rebuilding mechanism have been designed, aimed at fast disk reconstruction. This architecture is based on parity declustering data layouts and a disk-oriented reconstruction algorithm. It uses stripe groups instead of stripes as the basic distribution unit so that it can make use of the sequential nature of the rebuilding workload. The design space of system factors such as parity declustering ratio, chunk size, private buffer size of surviving disks and free buffer size are explored to provide guidelines for storage system design. Thirdly, an efficient distributed hot spare allocation and assignment algorithm for general parity declustering data layouts has been developed. This algorithm avoids conflict problems in the process of assigning distributed spare space for the units on the failed disk. Simulation results show that it effectively solves the write bottleneck problem and, at the same time, there is only a small increase in the average response time to user requests.
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By, Tomas. "Tears in the rain." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247153.
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Mortimer, Torrey. "Acid rain : the effects /." Click here to view, 2009. http://digitalcommons.calpoly.edu/socssp/1/.
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Cheong, Felix. "Broken by the rain /." [St. Lucia, Qld. : s.n.], 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16634.pdf.
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Clavell, Alicia K. "The archeology of rain." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2009m/clavell.pdf.
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Johnson, Don. "More Than Heavy Rain." Digital Commons @ East Tennessee State University, 2014. http://amzn.com/1937875571.
Testo completoAbstract (sommario):
More Than Heavy Rain brings together poems of intense observation culled from a life lived mostly outside. Set mostly around the poet’s home along the Watauga River in northeast Tennessee, the poems also reach out to such distant locations as Montana, Alaska, and post-war Germany. Some of them reconstruct the poet’s childhood in rural West Virginia. Some examine his family history, the events and relatives who helped determine the way he views the world.<br>https://dc.etsu.edu/etsu_books/1044/thumbnail.jpg
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Schantl, Helmut. "Schule als "triadischer Raum"." Doctoral thesis, Humboldt-Universität zu Berlin, Philosophische Fakultät IV, 2011. http://dx.doi.org/10.18452/16407.
Testo completoAbstract (sommario):
Ausgehend von der These, dass das Verhalten „schwieriger“ Kinder eine Folge kulturell-gesellschaftlicher Entwicklungen ist, die sich nachteilig auf den innerpsychischen Prozess der Triangulierung auswirken und auf die eine von zweckrationalen Organisationsstrukturen, von institutionsspezifischen Kommunikations- und Handlungsformen und von einem veränderten professionellen Selbstverständnis einzelner Lehrer dominierte Schule bislang keine befriedigenden Antworten gegeben hat, wird nach dem Potenzial der Psychoanalyse hinsichtlich der Möglichkeit gefragt, Pädagogen und Pädagoginnen bei der Konstituierung von Schule als ‚triadischer Raum’ im Sinne eines dyadisch geprägten und triadisch strukturierten, die kindliche Entwicklung fördernden psychosozialen Erfahrungsraums zu unterstützen. Am psychoanalytischen Theorem der Triangularität orientiert wendet sich die Erörterung zunächst drei von der Psychoanalyse beeinflussten sozialisationstheoretischen Konzepten unterschiedlicher Provenienz zu. Dieses methodische Vorgehen erweist sich jedoch im Kontext der zentralen Zielsetzung, ein umfassendes pädagogisches Konzept zur Stärkung kindlicher triangulärer psychischer Strukturen zu skizzieren, nur bedingt als hilfreich. Die anschließende Diskussion der Problem- und Fragestellung auf der Folie einer ‚kulturtheoretisch orientierten’ Psychoanalyse, die einem eigenständigen wissenschaftstheoretischen Selbstverständnis und Erkenntnisprozess folgend unbewusste individuelle und überindividuelle, kulturspezifische Subjektivitätsmomente wie auch biologische Determinanten seelischen Erlebens und Verhaltens berücksichtigt, führt zur Formulierung dreier Dimensionen des dialektischen Prinzips der Psychoanalyse, die sich im Bemühen um die Gestaltung triangulär organisierter Verständigungsprozesse als hilfreich erweisen können.<br>Based on the theory that the behavior of „difficult“ children is a result of a socio-cultural evolution that has adversely affected the inner-psychological process of triangulation and, based on the school of thought of purposive-rational organizational structures and that of institution-specific forms of communication and action, along with the altered professional self-understanding of individual teachers – noneof which have yet to offer any satisfactory answers – the question arises in accordance with the potential of psychoanalysis concerning the possibilities for educators in the constitution of a school as a ‚triadic space’, dyadically characterized and triadically structured to support the constructive psycho-social realm of experience in childhood development. Oriented on the psychoanalytical theorem of triangularity, the analysis initially adresses the varied provenience of three concepts influencing the socializationtheoretically and psychoanalytically. In the context of a central target, this methodic approach proves to be only slightly helpful when outlining a comprehensive pedagogical concept to reinforce childhood triangular psychological structures. The subsequent discussion of the problems addressed on the slides of ‚cultural-theorist-oriented’ psychoanalysis, following an independent epistemological self-understanding and cognitive process, taking unconscious individual and supraindividualculture-specific moments of subjectivity as well as biological determinants of emotional experience and behavior into consideration, leads to the formulation of tree dimensions of the dialectic principle of psychoanalysis that might prove to be helpful when attempting to configure triangularly organized processes of understanding.
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Jilabi, Abdulsameea. "Welding of rail steels." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/welding-of-rail-steels(b9d907ef-45fc-4649-8c2f-9239a121abe0).html.
Testo completoAbstract (sommario):
The worldwide preferred method for rail joining is welding; flash butt welding (FBW) and thermite welding (TW) are the two main welding methods used for joining continuous welded rail (CWR) tracks. However, the welds still represent a discontinuity in the track structure due to variations in microstructure, mechanical properties and residual stress levels with respect to the parent rail. These variations can play significant roles in increasing the risk of weld failure under service conditions. In order to better understand how FBW parameters affect these variations, the two main parameters; number of preheating cycles and upsetting forces were varied in three 56E1 rail welds, welded by a stationary FBW machine. Besides, these variations were systematically compared with those that occur in a standard thermite 60E2 rail weld. The thermite weld showed a heat affected zone (HAZ) extent much greater than those measured in the flash butt welds. The flash butt rail weld with a greater upsetting force (Standard Crushed) showed a HAZ extent larger than those in the other two welds (Standard Uncrushed and Narrow-HAZ Crushed), while the weld with fewer preheating cycles (Narrow-HAZ Crushed) showed a smaller extent of the HAZ.All welds showed pearlite colonies with proeutectoid ferrite at the prior austenite grain boundaries in the weld centre, and in the thermite weld zone. The rest zones across the welds exhibited almost fully pearlitic microstructures, but the pearlite at nearly the visible HAZ extents was partially spheroidised. The partially spheroidization zone had the minimum hardness across each of the thermite and flash butt welds. The Narrow-HAZ Crushed weld showed hardness in the weld centre, on average, higher than that of the parent metal. Moreover, the averaged hardness levels in this weld were significantly higher than those in the other two welds. However, these levels in the Standard Crushed weld were slightly lower than those in the Standard Uncrushed weld. Although the visible HAZ extent coincided with the point of minimum hardness, the residual stresses arising from the welds seem to extend much further. Contour Method and laboratory X-ray diffraction techniques were used together to measure the residual stress components across the thermite and flash butt rail welds. The longitudinal residual stress distribution showed tension in the web region along with compression in the head and foot regions of the rail welds. The vertical stress distribution across the flash butt welds was generally similar, and the maximum tensile stress values were comparable to those in the longitudinal direction. While the maximum values of the longitudinal tensile stress increased with decreasing the HAZ widths, these values in the vertical direction were significantly unaffected. However, the longitudinal and vertical tensile residual stresses typically promote the vertical straight-break and horizontal split web failure modes respectively.
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Kawasaki, Junji 1968. "Estimations of rail irregularities." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8543.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.<br>Includes bibliographical references (leaves 74-76).<br>Inspection cars that have been used to measure rail irregularities are costly and need operators. This thesis proposes a method to estimate rail irregularities by measuring accelerations of a passenger car instead of direct measurement by using a conventional inspection car. Using a System Identification technique and data obtained by simulations based on a three-dimensional rail vehicle model with actual rail irregularities, the proposed method identifies an inverse system where inputs are accelerations of a vehicle and outputs are rail irregularities. The resulting model is assessed through comparing the estimated irregularity with the actual irregularity. Validation results show that the estimate agree well with the actual irregularity for the Vertical Irregularity. Though the estimation error for the Lateral Irregularity is larger than that for the Vertical Irregularity, the error is acceptable form a practical point of view. The quality of the estimation is evaluated quantitatively by using the Mean Square Error. In addition, resolution of the estimation is presented in order to demonstrate the accuracy of the estimation. Model uncertainties are assessed for a practical implementation. The effects due to two major uncertainties, mass variations and speed variations, are evaluated by using the Singular Value Decomposition in order to present the limitations of the estimation using a nominal model. In addition, this thesis proposes a compensation method for mass variations and speed variations.<br>by Junji Kawasaki.<br>S.M.
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Boucsein, René. "Elitenbildung im transnationalen Raum." St. Gallen, 2008. http://www.biblio.unisg.ch/org/biblio/edoc.nsf/wwwDisplayIdentifier/03605680004/$FILE/03605680004.pdf.
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Ray, Arunim. "Niobium microalloyed rail steels." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/265387.
Testo completoAbstract (sommario):
Rail steels rely primarily on possessing adequate wear and rolling contact fatigue resistance. These properties, together with the toughness, can in principle be optimized by implementing thermomechanical processing assisted by controlled niobium additions. The purpose of the current work is to develop a Nb-microalloying strategy in the context of high-carbon pearlitic and cementite-free bainitic steels. The conventional methods do not leave the critical regions of a rail section in a suitably processed state. An attempt has been made for the first time, to create a pancaked austenite grain structure, with an examination of the consequences on the final product. One of the major difficulties is to ensure that niobium does not segregate during manufacturing, since niobium is a strong carbide former and rail steels traditionally contain large carbon concentrations. Niobium solubility in austenite has been assessed critically and thermodynamic calculations for microsegregation have been taken into account. The aim is to ensure that any primary niobium carbide precipitated from solute-enriched liquid during non-equilibrium solidification, can be taken into solution in austenite during reheating, to mitigate potential effects of coarse precipitates on the final mechanical properties. Rail steels containing 0.01-0.02 wt% Nb have been designed and characterised. In as-cast condition, primary niobium carbides as large as ~10 µm can be observed, which dissolve slowly during reheating. An attempt has been made to develop a model to estimate the dissolution kinetics of the carbides. Dissolved niobium in reheated austenite precipitates during hot deformation as fine niobium carbides (< 50 nm) which inhibit austenite recrystallisation by pinning the austenite grain boundaries. Nb-microalloying increases the ‘no-recrystallisation temperature’ of deformed austenite during multi-pass compression tests. The topology of grain deformation has been analysed in terms of stereological calculations and dilatometric experiments have shown that transformation kinetics tend to accelerate when the austenite is deformed below the no-recrystallisation temperature, however the effect is relatively small. The microstructure and mechanical properties of the as-rolled Nb-microalloyed steels have been characterised along with their rolling-sliding wear performance and compared with their non-microalloyed counterparts. Increased austenite grain boundary area and increased dislocation activity due to pancaking, hinder bainite growth which leads to an increased retained austenite volume fraction. This in turn, leads to slightly improved ductility, improved toughness and improved wear resistance in Nb-microalloyed bainitic alloys. Microstructural refinement in Nbmicroalloyed pearlitic alloys does not have any significant effect on tensile and toughness properties, but wear resistance improves significantly. A Bayesian neural network model has been developed to estimate the wear of rails. Predicted trends have been found consistent with metallurgical experience and the perceived noise levels are consistent with reasonable repeatability of the wear testing method used. The model can be applied widely to estimate wear because of its capacity to indicate uncertainty, including both the perceived level of noise in the output, and an uncertainty associated with fitting the function in the local region of input space.
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Ascher, Diana. "Ortsnamenwechsel im Raum Fulda." Deutsche Gesellschaft für Namenforschung, 2017. https://ul.qucosa.de/id/qucosa%3A31810.
Testo completoAbstract (sommario):
The essay deals with place name changes in the area Fulda. Although place and water names have a high degree of antiquity and continuity, names are changeable as linguistic entities. After an overview of the positions and observations on this phenomenon, represented by Wilhelm Arnold, Adolf Bach and Rudolf Schützeichel, as well as the impulses of the 1986 Bamberger Symposion on the subject of “place name change”, the term “name change” and its definitional blurring become first of all different types treated by “toponymic variation”. Finally, concrete examples from the Fulda area will be discussed and systematized.
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Weng, Darrin Kalung. "Accurate Hardware RAID Simulator." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1005.
Testo completoAbstract (sommario):
Computer data storage is growing at an astonishing rate. With cloud computing and the growth of the Internet enterprise storage has been predicted to grow at rates as high as 300\% per year. To fulfill this need technologies such as Redundant Array of Independent Disks or RAID are being used in industry today. Not only does RAID increase I/O performance but also provides redundancy measures to protect against hardware failure. Even though RAID has existed for some time now and is well understood, proprietary optimizations such as command scheduling and cache strategies that are employed by current RAID controllers are not well known. This thesis presents a model for RAID 5 that incorporates these features and describes the overall function of hardware RAID controllers. Also a python implementation of this model, Accurate Hardware RAID Simulator (AHRS) is presented and validated against a current hardware RAID controller. It is shown that AHRS can reproduce the behavior of a hardware RAID system with an accuracy of 97.92\% on average compared to a LSI hardware RAID controller.
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Vieira, Filipe Costa Beber. "Amplificador de Instrumentação em Modo Corrente com entrada e saída Rail-to-Rail." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/5347.
Testo completoAbstract (sommario):
This dissertation is aimed at the development of a current mode instrumentation amplifier (CMIA) with a high common mode input range. This characteristic is obtained due
to the rail-to-rail operational amplifiers (opamps). These opamps are built with rail-to-rail differential amplifiers as input stages, and with cascode-based output stages, which are able to copy its current by adding identical branches and connecting their gates without the voltage
degradation as the known CMIA topologies. The main contribution of this work is the development of a rail-to-rail current mode instrumentation amplifier, analyzing the pros and cons of this topology. The functionality of the proposed topology is shown through measured results of a manufactured integrated circuit. This first prototype, although it was operated in a large input common mode range, presented insufficient values of CMRR (Common Mode
Rejection Ratio) and VOS (Offset voltage). These two characteristics were studied and modeled, the instrumentation amplifier was re-designed, and simulated results demonstrate important improvements.<br>Esta dissertação tem como objetivo o desenvolvimento de um amplificador de instrumentação em modo corrente com uma ampla faixa de entrada em modo comum. Esta característica é obtida graças ao emprego de estágios de amplificação rail-to-rail na entrada e a geração do sinal de saída através do espelhamento da corrente diretamente dos gates dos
transistores do estágio ao invés da alternativa clássica, onde espelhos são ligados em série e degradam a excursão do sinal de saída. Com esta proposta, é possível a implementação de
ampops com entrada e saída rail-to-rail. A principal contribuição deste trabalho é analisar as vantagens e desvantagens da utilização destas soluções na implementação de um amplificador de instrumentação com entrada rail-to-rail. A funcionalidade da topologia proposta é demonstrada através dos resultados medidos de um circuito integrado fabricado. Este primeiro protótipo, apesar do bom funcionamento em toda a faixa de entrada em modo comum, apresentou valores insatisfatórios de CMRR (Common Mode Rejection Ratio) e de VOS (Tensão de offset), o que levou a um aprofundamento no estudo e modelagem destas características. A partir disto, o circuito foi re-projetado e os resultados de simulação
demonstram melhorias bastante significativas em suas características.
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Sakurai, Satoshi. "Design of rail-to-rail CMOS operational amplifiers for a 3-V supply /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487854314870488.
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