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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Inertial and radio positioning in challenging environments / Géolocalisation en environnements contraints par systèmes inertiel et radio

Patarot, Alexandre 29 June 2015 (has links)
Les systèmes de navigation par satellites permettent les applications de positionnement en extérieur, dont la navigation routière. Dans les environnements contraints, comme l'intérieur des bâtiments où ces signaux satellitaires sont dégradés, la continuité du service de positionnement est nécessaire. Les applications adaptées aux citoyens modernes avec leurs appareils nomades posent des contraintes fortes de mobilité, de coûts et de limitations des infrastructures existantes. Les larges possibilités de déplacements dans des environnements hétérogènes accroissent les difficultés. Un état de l'art alimenté par une décennie de travaux académiques et industriels présente un ensemble de technologies qui visent disponibilité et performance. L'accent porte ensuite sur les systèmes inertiels pédestres à bas coût, avec une première contribution permettant d'abandonner la détection de pas au profit d'une mobilité facilitée, mais reste limitée par la connaissance de la distance parcourue pendant une phase de calibration. Cette approche nouvelle est confrontée à celle classique au pied, puis éprouvée pour différents capteurs et piétons au travers d'expérimentations répétées en conditions réalistes. Une seconde contribution décline une constellation radio locale pour estimer la distance avec une infrastructure allégée à deux émetteurs. Elle s’inspire d’une conception satellitaire sur radio programmable pour faciliter sa compatibilité avec l’existant et explorer ses performances. Une surveillance du rapport signal à bruit inter-canal améliore la précision du positionnement. Le couplage de ces systèmes asynchrones et distribués est évalué en intérieur sur une plateforme automatisée / The global navigation satellite systems allow outdoor positioning applications, including car navigation. In challenging environments, such as the buildings where satellite signals are mitigated, georeferenced points of interest or navigation applications require a continuity of the positioning service. The applications adapted to modern citizens and their mobile devices raise strong constraints on mobility, costs and limitations of the existing infrastructure. The wide variety of displacements in heterogeneous environments increases the challenge. A state of the art fed by a decade of academic and industrial works presents a set of technologies that target availability and performance. The emphasis follows on the low cost pedestrian inertial systems, with a first contribution allowing to give up the step detection for the benefit of an easier mobility, but remains limited to the knowledge of the distance traveled during a calibration phase. This new approach is compared with the classical foot-mounted approach, and then benchmarked with several sensors and pedestrians through repeated experiments in real conditions. A second contribution operates a local radio constellation to estimate the distance with a minimal infrastructure with two emitters. The signals and the algorithm are based on a reproduction of satellite systems to ease the compatibility but are implemented on a programmable radio to explore the performances. A monitoring of the difference of carrier to noise ratio between the radio channels improves the distance estimation. The hybridization of these distributed, asynchronous and multi-rates inertial and radio systems is evaluated indoor on a motorized platform
52

Analysis of Positional Precision when Using Ground Control Points with Supported INS in GNSS-Free Environments / Undersökning av positionsprecision vid utnyttjande av kända punkter tillsammans med INS i områden utan GNSS

Bäckström, Linus, Grenert, Patrik January 2021 (has links)
Railway traffic is one of the most used transportation methods in today's society both for freight transports and transportation of people. A necessity for this to function is that the tracks upon which the trains travel are functional. This includes both that the tracks have been constructed correctly and that the tracks have not experienced wear and tear to the level that their functionality is in jeopardy. This requires that the tracks are thoroughly maintained and thus a continuous knowledge about the state of the tracks is required. One way to obtain knowledge about the current track geometry is to measure the tracks using laser scanners to establish the tracks geographical position. This in turn leads to the possibility to notice changes in the tracks. These laser scanners can be mounted on trains or modified vehicles where they scan the tracks while the vehicle is moving along the tracks. However, the scanned points also have to be precisely located in a coordinate system so that they can be compared to the scanned geometry of the initial tracks. The precise locations can be acquired by using Global Navigation Satellite Systems (GNSS) along with Inertial Measurement Systems (INS) and odometers, which are then used as input in a Kalman filter. The GNSS and INS complement each other in a good way since INS have very high positional accuracy and a large temporal error while GNSS has an acceptable positional accuracy and no temporal error. In locations where there is sufficient GNSS availability, this method reaches positional accuracies around the low cm level. The aforementioned method does however struggle when there is subpar GNSS availability, for example in tunnels or in dense forests. This necessitates the use of additional data, and in this work the use of ground control points (GCP) have been examined. The GCPs have been implemented in simulated GNSS-free areas where a temporal distance of 2, 5, 10, 20 and 40 seconds between GCPs has been used. Based on these experiments, an estimated positional accuracy from 0.5 cm to 30 cm in GNSS-free environments has been acquired depending on the distance between points. The authors recommend an implementation of GCPs in a tightly coupled approach every 5-10 seconds to achieve a reliable positional precision on the mm-cm level. The disadvantages of GCPs are quite large since they have to be established and maintained, which costs a fair amount of money and time. It is therefore of utmost importance to minimize the need for GCPs. This can be accomplished either by using alternative solutions such as implementations of track alignment in the Kalman filter, but also by increasing the efficiency of the GCPs. The way that this thesis recommends this to be researched is to use the same GCPs multiple times by either using more advanced sensors for locating the GCPs or by increasing the number of sensors as well as spreading them out across the vehicle. / Tågtrafik är ett av de mest använda transportsätten idag vare sig det gäller godstransporter eller persontransporter. En nödvändighet för att detta ska fungera är att rälsen som tågen färdas på är funktionella. Detta inkluderar att rälsen är korrekt konstruerad, men även att rälsen inte har blivit skadade av bland annat kontinuerlig användning. Därmed behöver rälsen underhållas, och för att kunna göra det krävs kunskap om i vilket skick rälsen är. Ett sätt att införskaffa kunskap om rälsens skick är att mäta rälsen med hjälp av laserskanners. Dessa laserskanners kan monteras på tåg eller rälsanpassade fordon så att de kan mäta in rälsen samtidigt som fordonet färdas längs med rälsen. De inmätta punkterna måste emellertid även vara kända i ett koordinatsystem så att de kan jämföras med punkterna som mättes in när rälsen initialt skannades. Den precisa platsinformationen som krävs för detta kan införskaffas genom att använda Global Navigation Satellite Systems (GNSS) samt Inertial Measurement Systems (INS) och odometer, som sedan används som input i ett Kalmanfilter. GNSS och INS kompletterar varandra på ett bra vis eftersom INS har en väldigt hög platsnoggrannhet samt ett högt tidsberoende fel medan GNSS har relativt hög platsnoggrannhet och inget tidsberoende fel. Denna metod kan därmed nå noggrannheter runt cm-nivån när det är bra GNSS-förutsättningar. Metoden som beskrevs ovan fungerar emellertid inte bra när det är dåliga GNSS-förutsättningar, till exempel i tunnlar eller i täta skogar. Då behövs det annan data, och i detta arbete har användningen av kända punkter analyserats. De kända punkterna har implementerats under en sträcka med simulerad avsaknad av GNSS där ett tidsbaserat avstånd på 2, 5, 10, 20 och 40 sekunder mellan kända punkter har använts. Baserat på dessa experiment har en precision på 0,5 cm till 30 cm uppnåtts beroende på avståndet mellan de kända punkterna. Författarna rekommenderar att kända punkter ska implementeras i en tightly coupled beräkningsmetod var 5-10 sekund för att nå en noggrannhet på mm-cm nivå. Nackdelarna med kända punkter är däremot flertaliga eftersom de måste etableras och underhållas, vilket kräver både tid och pengar. Det är därför viktigt att minimera behovet av kända punkter. Det kan åstadkommas genom att till exempel implementera rälsdata i Kalmanfiltret, men även genom att öka effektiviteten i användandet av de kända punkterna. I det här arbetet rekommenderas det att undersöka hur det går att använda samma kända punkt flertalet gånger. Detta genom att antingen använda mer avancerade sensorer för att lokalisera de kända punkterna eller genom att öka antalet sensorer samt att sprida ut dem över fordonet.
53

OVERVIEW OF THE NASA WALLOPS FLIGHT FACILITY MOBILE RANGE CONTROL SYSTEM

Davis, Rodney A., Semancik, Susan K., Smith, Donna C., Stancil, Robert K. Jr 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The NASA GSFC’s Wallops Flight Facility’s (WFF) Mobile Range Control System (MRCS) is based on the functionality of the WFF Range Control Center at Wallops Island, Virginia. The MRCS provides real time instantaneous impact predictions, real time flight performance data, and other critical information needed by mission and range safety personnel in support of range operations at remote launch sites. The MRCS integrates a PC telemetry processing system (TELPro), a PC radar processing system (PCDQS), multiple Silicon Graphics display workstations (IRIS), and communication links within a mobile van for worldwide support of orbital, suborbital, and aircraft missions. This paper describes the MRCS configuration; the TELPro’s capability to provide single/dual telemetry tracking and vehicle state data processing; the PCDQS’ capability to provide real time positional data and instantaneous impact prediction for up to 8 data sources; and the IRIS’ user interface for setup/display options. With portability, PC-based data processing, high resolution graphics, and flexible multiple source support, the MRCS system is proving to be responsive to the ever-changing needs of a variety of increasingly complex missions.
54

MODULAR AFFORDABLE GPS/INS (MAGI)

Singh, Mahendra, McNamee, Stuart, Khosrowabadi, Allen 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The GPS/INS equipment is used at the Air Force Flight Test Center (AFFTC) to collect time space position information (TSPI) during testing. The GPS-based test instrumentation is lagging behind available commercial technologies. Advancing technologies for test use requires investigation of affordable commercial equipment. To enable technology insertion for state of the art testing, there is a need for more robust, flexible, reliable, modular, affordable low cost TSPI systems capable of operating in all flight environments. Modular (plug-and-play) hardware and software, quick and easy to re-configure, are required for supporting various test platforms from fighter aircraft to cargo size aircraft. Flight testing dynamics are such that, GPS-only systems tend to lose data during critical maneuvers. To minimize this data loss, inertial measurement systems coupled with GPS sensors are used in most sophisticated range instrumentation packages. However, these packages have required fairly expensive inertial units, are usually very large and not very flexible in terms of quick and easy reconfiguration to meet the unique needs of AFFTC’s test customers. WADDAN SYSTEMS has begun to address this problem with a modular design concept, which incorporates their high-performance navigation quality inertial measurement unit, but with costs comparative to that of lower-end performance inertial units. This paper describes WADDAN’s concept and the components that make up MAGI; and addresses some of the preliminary testing and near-term proposed activities. In general, the system will provide GPS, inertial and discrete MIL-STD 1553, RS-232/422 and video data from the participant. The MAGI will be structured around the Compact personal computer interface (PCI) backplane bus with on-board recording and processing and will include real-time command and control through a UHF data link.
55

Unfamiliar Streets: The Chattanooga Sit-ins, the Local Press, and the Concern for Civilities

Harris, Jessie 06 May 2011 (has links)
Gene Roberts and Hank Klibanoff in their breakthrough work, The Race Beat, contended that mainstream newspapers—white newspapers—largely ignored the black community until the 1950s and 1960s when editors gradually began opening their pages to reports of racial discrimination and the emerging protest against segregation. This coverage significantly shaped the civil rights movement, Roberts and Klibanoff argued. “Unfamiliar Streets” offers nuance to their narrative. Examining the local coverage of the 1960 Chattanooga sit-in movement as a case study, Jessie Harris contends that reporters and editors, although they should be credited for extensively covering the sit-ins, ultimately cared more for civilities than civil rights. Their coverage detailed the protests, fights, and mobs downtown, but only rarely provided perspectives of student demonstrators and rarely called attention to the injustices of segregation.
56

Etude du rôle du gène PROX1 dans le diabète de type 2 / Study of the role of PROX1 gene in type 2 diabetes

Lecompte, Sophie 04 December 2012 (has links)
PROX1 étant un facteur de susceptibilité au diabète de type 2 (DT2), nousavons réalisé des études génétiques et moléculaires afin de comprendre son rôledans l’étiologie du DT2.Nous avons analysé l’impact de 80 SNPs de PROX1 sur des phénotypescliniques associés au DT2 dans l’étude HELENA (n=1155 adolescents) et montréque trois SNPs (rs340838, rs340837 et rs340836) sont associés à l’insulinémie àjeun. Nous avons évalué la fonctionnalité de 9 SNPs (les 3 SNPs associés et 6 SNPsen déséquilibre de liaison) en utilisant un gène rapporteur Luciférase dans descellules HepG2 et MIN6. Les allèles associés à la diminution de l’insulinémie desSNPs rs340874, rs340873 et rs340835 sont associés à une diminution del’expression du gène rapporteur Luciférase, suggérant que l’expression de PROX1est diminuée chez les individus porteurs des allèles à risque.Nous avons aussi montré que l’inhibition de l’expression de Prox1 par siRNAsdans les cellules INS-1E engendrait une diminution de 1,7 fois de la sécrétiond’insuline en réponse au glucose et qu’une concentration élevée en glucose modulaitpositivement l’expression de la protéine Prox1.Des analyses transcriptomiques réalisées dans les cellules INS-1E ont permisde montrer que certains des gènes cibles de PROX1 dans les cellules bêta sont desgènes impliqués dans des voies de sécrétion d’insuline.Enfin, nous avons également observé que l’agoniste de PPARgamma, latroglitazone, diminuait l’expression de Prox1 dans les cellules INS-1E.Ces résultats suggèrent qu’une altération de l’expression de Prox1 par desvariants cis-régulateurs pourrait conduire à une sécrétion d’insuline en réponse auglucose altérée des cellules bêta, conférant ainsi une susceptibilité au DT2. / As PROX1 is a susceptibility factor for type 2 diabetes (T2D), we conductedgenetic and molecular studies to better understand the role of PROX1 in the etiology of T2D. We assessed the impact of 80 PROX1 SNPs on T2D-related biochemical traits in the HELENA study (n=1155 adolescents) and showed that 3 SNPs (rs340838, rs340837 and rs340836) were significantly associated with fasting plasma insulin levels. We evaluated the functional impact of 9 SNPs (the 3 insulin-associated SNPs plus 6 SNPs in linkage disequilibrium) using a Luciferase reporter gene expression in HepG2 and MIN6 cells. The insulin-lowering alleles of the rs340874, rs340873 and rs340835 SNPs were associated with lower Luciferase gene expression, suggesting that PROX1 expression may be lower in individuals carrying the insulin-lowering alleles. We also showed that the knock-down of Prox1 expression by siRNA in INS-1E cells resulted in a 1.7 fold reduced glucose-stimulated insulin secretion and that high concentrations of glucose positively modulated Prox1 protein expression. Then, microarray analyses performed in INS-1E cells showed that some PROX1 target genes in the _cells are implicated in insulin secretion pathways. Finally, we observed that the PPARgamma agonist, the troglitazone, decreased Prox1 expression in INS-1E cells. Altogether, these results suggest that an altered expression of Prox1 bys cisregulators variants results in an altered -cell glucose-stimulated insulin secretion andthereby confers susceptibility to T2D.
57

Effect of aryl-hydrocarbon receptor activity on lipid accumulation, insulin content and secretion from clonal pancreatic beta-cells

Baghdasarian, Siyouneh 03 July 2018 (has links)
OBJECTIVE: The aryl hydrocarbon receptor (AhR) translocates to the nucleus and binds to the aryl hydrocarbon receptor nuclear translocator (ARNT) to regulate biological responses upon ligand activation. The aim of this study was to measure the effects of activation or inhibition of AhR activity on basal and glucose-stimulated insulin secretion (GSIS) from clonal pancreatic β-cells (INS-1) cultured under normal and glucolipotoxic (GLT) conditions (high glucose and fatty acid). METHODS: Insulin content and secretion were measured utilizing homogenous time-resolved fluorescence (HTRF) insulin assay kit (cisbio). Cells cultured in RPMI media containing 5 mM and 11 mM glucose were pre-incubated with the receptor agonist FICZ or antagonist CH223191 for 96 hours. Insulin secretion over 2 hours was reported as ng/million cells. Intracellular lipid was measured by fluorescence after Nile red staining. RESULTS: Incubation of INS-1 cells with 11 mM glucose and fatty acid increased lipid droplets, basal insulin secretion and inhibited GSIS compared to cells cultured in 4 mM glucose, characteristic of GLT. Incubation of INS-1 cells with 11 mM glucose alone also exhibited GLT characteristics. INS-1 cells cultured at 11 mM glucose and treated with antagonist (1.25 - 10 μM) had decreased lipid content and improved insulin secretion compared to cells cultured in 11 mM glucose alone. INS-1 cells cultured in 5 mM glucose and treated with the AhR agonist (1.25 - 10 μM) exhibited increased intracellular lipid and impaired insulin secretion. CONCLUSION: The AhR may play a mediatory role in the development of GLT in pancreatic β-cells cultured in excess nutrients and β-cell specific activator or inhibitor ligands of this receptor could potentially be a targeted therapeutic treatment of diabetes.
58

Baltic German Exodus, 1939-1945: Settlement, Adaption and Disappearance

Bresinsky, Aiko N 01 May 2017 (has links)
The resettlement of Baltic Germans from Estonia and Latvia to the Polish territories initiated the dissolution of the Baltic German community and its unique identity, largely causing hardship and suffering throughout the occupation in Poland. The subsequent escape from the Red Army and deportations by the Poles at the end of World War II completed the disbanding. It brought innocent families, as well as Baltic German soldiers, to and beyond the limits of their ability to endure pain and suffering. Yet, throughout the process, Baltic Germans’ reaction to the opportunities and crisis varied greatly. The following study will uncover the diverse fates Baltic Germans endured and reveal the range of Baltic German’s culpability and victimhood throughout the resettlement process and the subsequent migration west.
59

Language extension via dynamically extensible compilers.

Seefried, Sean, Computer Science & Engineering, Faculty of Engineering, UNSW January 2006 (has links)
This dissertation provides the motivation for and evidence in favour of an approach to language extension via dynamic loading of plug-ins. There is a growing realisation that language features are often a superior choice to software libraries for implementing applications. Among the benefits are increased usability, safety and efficiency. Unfortunately, designing and implementing new languages is difficult and time consuming. Thus, reuse of language infrastructure is an attractive implementation avenue. The central question then becomes, what is the best method to extend languages? Much research has focussed on methods of extension based on using features of the language itself such as macros or reflection. This dissertation focuses on a complementary solution: plug-in compilers. In this approach languages are extended at run-time via dynamic extensions to compilers, called plug-ins. Plug-ins can be used to extend the expressiveness, safety and efficiency of languages. However, a plug-in compiler provides other benefits. Plug-in compilers encourage modularity, lower the barrier of entry to development, and facilitate the distribution and use of experimental language extensions. This dissertation describes how plug-in support is added, to both the front and back-end of a compiler, and demonstrates their application through a pair of case studies.
60

Bearbetning av GPS-data vid Flyg- och Systemprov / Processing GPS data at Flight and Systems test

Persson, Joakim January 2002 (has links)
At Flight and Systems test Saab AB, a post-processing software is used to process GPS data. A new software by the name GrafNav has been purchased and the purpose of this master thesis therefore became, partly to make a judgment regarding GrafNav’s ability to estimate position, velocity and accuracy, partly to if needed improve the estimate and finally find one or several methods to estimate the position and velocity accuracy. The judgment of GrafNav was performed partly by a comparison to the former post-processing software (PNAV) and partly by a comparison to the airplane’s inertial navigation system (INS). The experiments showed that GrafNav’s ability to estimate the position is comparable with PNAV:s, but its capacity to estimate the velocity is considerably worse. The velocity estimate even showed a more noisy behavior than the original velocity from the receiver. More effort is needed to judge GrafNav’s ability to estimate the accuracy thru its quality signals. A few trials were made to improve the velocity estimate thru Kalman filtering (Rauch-Tung-Striebel smoothing). The filtering was first made using only the position data from GrafNav as measurements and afterwards both position and velocity data from GrafNav was used. The outcome of the Kalman filtering showed that the best result is obtained when solely position data is used and that the estimate in general is comparable with PNAV:s estimate, but considerable big deviations is obtained in conjunction to interruptions in position data. More over, is more effort needed using both position and velocity data when performing the smoothing and also replacing the stationary Kalman filter with an adaptive filter. Finally a method was brought out to estimate the position precision and a method to estimate the velocity accuracy. Both methods use the INS velocity to perform an estimation.

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