• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 600
  • 250
  • 180
  • 175
  • 130
  • 123
  • 64
  • 24
  • 20
  • 16
  • 16
  • 12
  • 11
  • 8
  • 7
  • Tagged with
  • 1884
  • 251
  • 240
  • 232
  • 230
  • 175
  • 138
  • 137
  • 132
  • 128
  • 115
  • 107
  • 101
  • 97
  • 97
  • 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.
411

Lokomotyvo maršruto duomenų surinkimo įtaisas / Locomotive Route Data Logger

Valančius, Valdas 04 August 2011 (has links)
Šiame darbe suprojektuotas įtaisas yra skirtas duomenų kaupimui ir yra paremtas GPS technologija. Įtasisas nuskaito ALS kodų būsenos duomenis nuo lokomotyvo ALS indikatoriaus ir apjungtus su GPS duomenimis įrašo į SD atmintinę. / This work is designed and build in the data accumulation device is a device based on GPS technology. He is a ALS codes status of locomotive capture and the conjoin with GPS data to record to SD memory. The device reads the status codes for an ALS from the ALS indicator of photo sensor. The device is designed using the company's GlobalSat GPS module ET-212 and the "Microchip" PIC18F4520 microcontroller, which communicate with each other through the UART interface NMEA0183 protocol. Equipped with a standard SD memory port, the device is suitable for any manufacturer of SD memory. Printed circuit boards designed with Cadsoft "'s EAGLE 5.11.0 software, and the microcontroller software is written MikroC pro 3.8v compiler. This device is designed for locomotives ALS status code and data storage can be used in the locomotives equipped with the ALS (KLUB) system.
412

Onboard Orbit Determination Using GPS Measurements for Low Earth Orbit Satellites

Zhou, Ning January 2005 (has links)
Recent advances in spaceborne GPS technology have shown significant advantages in many aspects over conventional technologies. For instance, spaceborne GPS can realize autonomous orbit determination with significant savings in spacecraft life cycle, in power, and in mass. At present, the onboard orbit determination in real time or near-real time can typically achieve 3D orbital accuracy of metres to tens metres with Kalman filtering process, but 21st century space engineering requires onboard orbit accuracy of better than 5 metres, and even sub-metre for some space applications. The research focuses on the development of GPS-based autonomous orbit determination techniques for spacecraft. Contributions are made to the field of GPS-based orbit determination in the following five areas: Techniques to simplify the orbital dynamical models for onboard processing have been developed in order to reduce the computional burden while retaining full model accuracy. The Earth gravity acceleration approximation method was established to replace the traditional recursive acceleration computations. Results have demonstrated that with the computation burden for a 55× spherical harmonic gravity model, we achieve the accuracy of a 7070× model. Efforts were made for the simplification of solar & lunar ephemerides, atmosphere density model and orbit integration. All these techniques together enable a more accurate orbit integrator to operate onboard. Efficient algorithms for onboard GPS measurement outlier detection and measurement improvement have been developed. In addition, a closed-form single point position method was implemented to provide an initial orbit solution without any a priori information. The third important contribution was made to the development of sliding-window short-arc orbit filtering techniques for onboard processing. With respect to the existing Kalman recursive filtering, the short-arc method is more stable because more measurements are used. On the other hand, the short-arc method requires less accurate orbit dynamical model information compared to the long-arc method, thus it is suitable for onboard processing. Our results have demonstrated that by using the 1 ~ 2 revolutions of LEO code GPS data we can achieve an orbit accuracy of 1 ~ 2 metres. Sliding-window techniques provide sub-metre level orbit determination solutions with 5~20 minutes delay. A software platform for the GPS orbit determination studies has been established. Methods of orbit determination in near-real time have been developed and tested. The software system includes orbit dynamical modelling, GPS data processing, orbit filtering and result analysis modules, providing an effective technical basis for further studies. Furthermore a ground-based near-real time orbit determination system has been established for FedSat, Australia's first satellite in 30 years. The system generates 10-metre level orbit solution with half-day latency on an operational basis. This system has supported the scientific missions of FedSat such as Ka-band tracking and GPS atmosphere studies within the Cooperative Research Centre for Satellite System (CRCSS) community. Though it is different from the onboard orbit determination, it provides important test-bed for the techniques described in previous section. This thesis focuses on the onboard orbit determination techniques that were discussed in Chapter 2 through Chapter 6. The proposed onboard orbit determination algorithms were successfully validated using real onboard GPS data collected from Topex/Poseidon, CHAMP and SAC-C satellites.
413

GPS L1 Carrier Phase Navigation Processing

Bruggemann, Troy S. January 2005 (has links)
In early 2002, Queensland University of Technology (QUT) commenced to develop its own low-cost Global Positioning System (GPS) receiver with the capability for space applications such as satellites in Low Earth Orbits, and sounding rockets. This is named the SPace Applications Receiver (SPARx). This receiver development is based on the Zarlink (formerly known as Mitel) GP2000 Chip set and is a modification of the Mitel Orion 12 channel receiver design. Commercially available GPS receivers for space applications are few and expensive. The QUT SPARx based on the Mitel Orion GPS receiver design is cost effective for space applications. At QUT its use is being maximized for space applications and carrier phase processing in a cost-effective and specific way. To build upon previous SPARx software developments made from 2002 to 2003, the receiver is required to be modified to have L1 carrier phase navigation capability. Such an improvement is necessary for the receiver to be used in 3-axis attitude determination and relative navigation using carrier phase. The focus of this research is on the implementation of the L1 carrier phase measurement capability with SPARx. This is to enable the use of improved navigation algorithms. Specific emphasis is given to the areas of time synchronization, the carrier phase implementation and carrier phase differential GPS with SPARx. Test results conducted in the area of time synchronization and comparisons with other carrier phase capable GPS receivers are given, as well as an investigation of the use of SPARx in carrier phase differential GPS. Following these, conclusions and recommendations are given for further improvements to SPARx.
414

Großräumige GPS/INS Vermessung mittels virtueller Referenzstationen

Kipka, Adrian Unknown Date (has links)
Techn. Univ., Diss., 2005--Darmstadt
415

Estimativa do vapor d'água atmosférico e avaliação da modelagem do atraso zenital troposférico utilizando GPS /

Sapucci, Luiz Fernando. January 2001 (has links)
Orientador: João Francisco Galera Monico / Resumo: O posicionamento com GPS (Global Positioning System), consiste basicamente na determinação de distâncias entre satélites e receptores, obtidas por meio de observações de sinais de rádio-freqüência. Entre os vários erros que estão presentes nessas observações, encontra-se o atraso dos sinais causado pela influência do vapor d'água atmosférico. Depois de minimizados os demais erros, o atraso troposférico pode ser estimado a partir das observações GPS. Estas estimativas, além de serem utilizadas para avaliar os modelos que tratam os efeitos da troposfera, podem ser convertidas em estimativas do vapor d'água integrado na atmosfera (IWV-Integrated Water Vapor). Para essa conversão, utiliza-se uma relação entre essas quantidades baseada na temperatura média da coluna vertical troposférica. Este trabalho tem por objetivo apresentar a aplicação do GPS na quantificação do vapor d'água atmosférico e uma metodologia para avaliar a modelagem do atraso zenital troposférico. Para isso, campanhas de radiossondagens e coletas simultâneas de observações GPS foram realizadas. Os resultados, na estimativa do vapor d'água atmosférico, apresentaram boa compatibilidade com os valores fornecidos pelas radiossondas (EMQ de 2 kg/m2), e são similares aos valores encontrados na literatura. Quanto à avaliação da modelagem troposférica, os resultados indicam que a metodologia proposta apresentou-se adequada. / Abstract: The GPS (Global Positioning System) positioning basically consists on determining the distances between satellites and receivers that are obtained by observing radio-frequency signals. There are several errors present in these observations. Among them we can find the delay of those signals caused by atmospheric water vapor. The tropospheric delay can be estimated by GPS observations processing after minimizing other errors. These estimates can be used to evaluate the models that attempt to reduce the tropospheric effects and may also be transformed into estimates of integrated water vapor (IWV). In this transformation is used a relationship between the delay and IWV values based on the tropospheric mean temperature. The main aims of this work are to present the GPS application related to atmospheric water vapor quantification and to propose a methodology to evaluate the zenithal tropospheric delay modeling. Launching radiosonde campaigns with simultaneous collections of GPS observations were accomplished. The results obtained by comparison the IWV values derived by GPS and radiosondes presented good compatibility (EMQ 2 kg/m2), which are similar to those found in the literature. The results supplied in the evaluation of tropospheric models indicated that the proposed methodology is adequate. / Mestre
416

Potencialidades de serviços on-line de Posicionamento por Ponto Preciso em aplicações geodésicas: uma análise envolvendo longo período de dados das estações da RBMC

Azambuja, José Luiz Fay de January 2015 (has links)
Um método de posicionamento por GNSS (Global Navigation Satellite System) que vem se popularizando nos últimos anos é o Posicionamento por Ponto Preciso (PPP). Este método de posicionamento se utiliza de dados de apenas um receptor e requer, fundamentalmente, o uso de efemérides e correções dos relógios dos satélites precisos. O PPP nos últimos anos ganhou um impulso significativo em sua popularidade devido, principalmente, ao surgimento de serviços gratuitos de processamento on-line. Entre estes serviços on-line de processamento de PPP, destaca-se o fornecido pelo NRCan (Natural Resource Canada), denominado CSRS-PPP (Canadian Spatial Reference System – Precise Point Positioning). Nesta Tese utilizou-se o serviço canadense CSRS-PPP no processamento de um longo período de dados superior a onze anos coletados em noventa e cinco das estações da RBMC. A análise das velocidades obtidas a partir das respectivas séries temporais referentes às coordenadas diárias estimadas pelo CSRS-PPP bem como a determinação de suas coordenadas – através do PPP – referidas à época 2000.4, mostraram resultados com pequenas discrepâncias quando comparadas com os valores oficiais adotados para as estações analisadas. O problema detectado, refere-se à impossibilidade da adoção de velocidades lineares de translação no sistema cartesiano X, Y e Z, tendo em vista que na grande maioria das estações constatou-se um comportamento sazonal referente à altura elipsoidal, variação esta que afeta as translações em X, Y e Z ao longo do ano. Como solução, propõe-se a adoção das velocidades de deslocamento calculadas para coordenadas planas, particularmente as coordenadas UTM, sendo a altura elipsoidal corrigida através de modelos estabelecidos em função da variação sazonal registrada em cada uma das estações da RBMC. / A positioning method for GNSS (Global Navigation Satellite System) that has become more popular in recent years is the Precise Point Positioning (PPP). The PPP refers to the positioning method that utilizes data to only one receiver and requires fundamentally the use of ephemeris and corrections to the precise satellite clock. The PPP in recent years gained a significant boost in its popularity, mainly due to the emergence of free services online processing. Among these PPP processing on-line services, there is the one provided by NRCan (Natural Resource Canada) called CSRS-PPP (Canadian Spatial Reference System - Precise Point Positioning). In this Thesis used if the Canadian service CSRS-PPP to process data for a long period upper through eleven collected at ninety-five of RBMC stations. The analysis of the rates obtained from the respective time series relating to the daily coordinates estimated by the CSRS-PPP and the determination of its coordinates - through PPP - said at the time 2000.4, showed results with minor discrepancies compared with the official values adopted for the analyzed stations. The problem detected, refers to the impossibility of adopting linear translation speeds in the Cartesian system X, Y, and Z, considering that in most of the stations found a seasonal pattern related to the ellipsoidal height, this variation that affects translations in X, Y and Z throughout the year. As a solution, it is proposed the adoption of the forward speeds calculated for planar coordinates, particularly UTM coordinates, and the ellipsoid height corrected by established models depending on seasonal variations recorded in each of the stations RBMC.
417

To drink or not to drink? The influence of resource availability on elephant foraging and habitat selection in a semi-arid savanna. / Boire ou ne pas boire? L'influence de la disponibilité en resource sur l'approvisionenement et la sélection de l'habitat d'éléphants dans une savanne semi aride.

Valls Fox, Hugo 14 December 2015 (has links)
L’eau et le fourrage sont deux ressources non substituables pour les herbivores dans les écosystèmes arides et semi-arides. La distribution spatiale de l’eau de surface détermine la distribution et l’abondance des espèces dépendantes de l’eau. Cependant les processus impliqués à l’échelle individuelle demeurent méconnus. Treize groupes familiaux d’éléphants d’Afrique (Loxodonta africana) et dix mâles ont été équipé de colliers GPS dans le parc National de Hwange, au Zimbabwe, et à sa périphérie. Les éléphants fourragent autour de multiples points centraux : ils visitent un point d’eau périodiquement toutes les 5h, 24h, 48h ou 72h et s’éloignent plus de l’eau lorsque ils font des trajets de plus longue durée. Pendant la saison sèche, la température augmente et les ressources fourragères s’épuisent à proximité de l’eau. Les groupes familiaux d’éléphants visitent les points d’eau plus souvent en augmentant la fréquence des trajets courts et en abandonnant les trajets de 72h. Cependant, ils parviennent à se rendre plus loin de l’eau pendant les trajets de 24h en augmentant la vitesse de déplacement. Ainsi les patrons de déplacement révèlent que les capacités de locomotion et de navigation des éléphants sont au cœur de leur stratégie d’adaptation à la saison sèche. Malgré cela, ces capacités sont rarement incluses dans les modèles d’approvisionnement dans des environnements hétérogènes. Pendant ces trajets, les groupes familiaux sélectionnent les zones de faible densité de points d’eau à des échelles multiples. La force de la sélection pour ces zones de faible densité augmente avec la longueur du trajet et au cours de la saison. Malgré le fait que l’importance des échelles spatiales soit bien établie dans la littérature, les contraintes associées à l’utilisation de multiples points centraux distribués de manière hétérogène dans le paysage ont été négligé alors que cette distribution détermine le degré d’épuisement des ressources fourragères et les rétroactions sur la sélection de l’habitat. J’ai aussi montré que la faune sauvage évite fortement le bétail et les humains qui les conduisent en périphérie d’une zone protégée pendant la saison des pluies. Cependant cet évitement décline au cours de la saison sèche en raison de l’assèchement des points d’eau et de la raréfaction des ressources fourragères. Les éléphants sont de plus en plus contraints par la distribution de l’eau de surface en saison sèche en raison de l’augmentation de leur besoins en eau tandis qu’ils tentent de maintenir leur approvisionnement en fourrage. Cette étude donne une évaluation quantitative de la contrainte en eau à l’échelle individuelle ainsi que les effets de la distribution en eau dans le paysage sur un grand herbivore. Ces résultats peuvent guider les politiques de gestion de l’eau dans un contexte d’aridification dû au changement climatique. / Water and forage are key non-substitutable resources for herbivores in arid and semi-arid ecosystems. The distribution of surface water determines the distribution and abundance of water dependent animal species yet little is known about the processes involved at the individual level. Thirteen African savanna elephant family groups and ten bulls (Loxodonta Africana) were tracked with GPS collars within and on the outskirts of Hwange National Park, Zimbabwe. Elephants behave as multiple central place foragers: They visit waterholes periodically every 5h, 24h, 48h or 72h and travel further from water during longer trips. During the dry season, temperatures increase and forage becomes depleted closer to water. Elephant family groups visit waterholes more often by increasing the proportion of briefer trips and abandoning 72h trips. However, they forage further during 24h trips by increasing travelling speed. Elephant movement patterns revealed locomotional and navigational abilities are at the core of their coping strategies although they are seldom allowed to vary in most foraging models of animal's use of heterogeneously distributed resources. During these foraging trips, family herds select for areas with low waterhole density at multiple scales. Selection strength for low density areas increases with both distance to water and the advancement of the dry season. Although scaling effects are widely recognized, the effects of the spatial distribution of multiple central places constraining foraging have been ignored yet they determine depletion effects and their feedbacks on habitat selection. I also showed that wildlife strongly avoid livestock and people that herd them at the boundary of a protected area during the rainy season yet avoidance decreases during the dry season when foraging and drinking resources become scares. Elephants are increasingly constrained by surface water availability during the dry season as their drinking requirements increase while they strive to main their forage intake. This study provides quantitative assessment of individual water dependence and of landscape effects of surface water distribution on a large herbivore. These findings can inform surface water management in contexts of aridification resulting from climate change.
418

Mesure de la variabilité des déplacements 3D de glaciers alpins par GNSS et imagerie radar / 3D displacement variability measurements of alpine glaciers by GNSS and radar imagery

Ponton, Fanny 22 November 2013 (has links)
Les travaux menés dans le cadre de cette thèse portent sur la mesure de la variabilité de déplacement de surface de glaciers alpins, par GNSS et imagerie radar. Le glacier tempéré d'Argentière, situé dans le massif du Mont-Blanc et équipé de stations GPS et de coins réflecteurs, est plus particulièrement choisi comme site d'étude. A l'aide de la méthode de corrélation d'amplitude, 44 images TerraSAR-X acquises en 2009 et 2011 sont traitées, permettant d'obtenir 38 champs de déplacement 2D, ainsi que 6 champs de déplacement 3D. En parallèle, l'analyse de 5 années de données GPS continues issues de 2 stations implantées sur le glacier, permet de connaître la vérité terrain. Une stratégie d'analyse GPS, qui optimise la précision de la mesure de position sur un objet en mouvement, a été choisie. Les résultats GPS révèlent plusieurs régimes dynamiques du glacier d'Argentière. La variabilité journalière indique un déplacement de surface en stick-slip et la variabilité intra-annuelle permet de mettre en évidence un amincissement constant du glacier d'Argentière. Au printemps 2011, les résultats GPS permettent de suivre la mise en place d'un système de drainage sous-glaciaire. Les résultats radar permettent une visualisation des variations du déplacement de surface d'une grande résolution spatiale. Au niveau temporel, des accélérations du déplacement sont mises en évidence pendant les périodes de fonte importante. Si une bonne corrélation entre les variations générales du déplacement du glacier d'Argentière issues des deux sources de données est obtenue, les travaux de cette thèse révèlent une importante complémentarité entre le GPS et l'imagerie radar. / The aim of this PhD thesis is to measure the surface displacement variability of alpine glaciers with GNSS and radar imagery. The temperate Argentière glacier, located in the Mont Blanc massif and equiped with GPS station and corners reflectors is prticularly considered. 44 TerraSAR_X images, acquired in 2009 and 2011, are processed by offset power tracking,allowing to obtain 38 2D displacement field and 6 3D displacement fields. At the same time, 5 years of continuous GPS data from 2 stations et up on the glacier are processed, allowing to have a ground truth. GPS processing has been carefully chosen to mximise the positionning accuracy on a moving object. GPS results highlight the existence of several dynamic regimes of the Argentière surface displacement. The daily variability shows a stick slip behaviour of the displacement and the annual variability reveals a constant thinning of hte ice. Moreover, in spring 2011 the particular signal of the installation of the subglacial drainage system is identified. Synthetic Aperture Radar (SAR) results allow the monitoring of thesurface displacement with a high spatial resolution. Temporally, a seasonnal variability is found, with large accelerations over relatively short times in melting periods. While a good correlation is obtained between the mean displacement variability of the Argentière glacier from both data sources, the thesis results highlight a significant complementarity between GPS and SAR imagery.
419

Contraintes GPS sur la tectonique actuelle du sud-ouest de la Bulgarie, de la Grèce du nord et de l'Albanie / Gps constrains on current tectonics of soutwest bulgaria, northern greece, and albania

Matev, Krasimir 08 March 2011 (has links)
Dans cette thèse, nous présentons une quantification de la déformation en cours du sud des Balkans et de la Méditerrnée centrale et orientale par GPS. Le champs de vitesses a été déduit de l'analyse de données issues de 225 stations GPS permanentes ou épisodiques pour la période 1996-2009. Ce champs de vitesse est analysé et discuté pour essayer de déterminer si le champ de vitesse est continu ou si, au contraire, des blocs stables peuvent être individualisés. La déformation actuelle du sud-ouest de la Bulgarie et du nord de la Grèce ont été particulièrement étudiés à partir de mesures réalisées de 1996 à 2008. Cette région est particulièrement active comme le montre la sismicité historique et en particulier le séisme de Krupnik en 1904 (sud-ouest de la Bulgarie) qui fut un séisme parmi les plus destructeur en Europe continentale au cours des deux derniers siècles. Le nord de la Grèce est quant à lui caractérisé par des séismes destructeurs de M > 6. Les résultats obtenus montrent l'existence de déplacements vers le sud par rapport à l'Eurasie stable s'accroissant du Nord (2mm/an) vers le sud de la région étudiée (10 mm/an). Les tenseurs de taux de déformation sont présentés et discutés à la lumière de la déformation exprimée lors des séismes. Ces deux types d'information montrent tous deux une prédominance d'une extension Nord-sud en accord avec les données géologiques (présence de grabens Est-Ouest) et les modèle proposés pour la Méditerranée centrale et orientale. A l'ouest des Balkans, la déformation actuelle de l'Albanie s'exprime par des nombreux indices néotectoniques et une sismicité importante présentant de nombreux séismes historiques destructeurs. Données géologiques et sismotectoniques montrent d'une part l'existence d'un raccourcissement dans les Albanides externes et d'autre part une extension Est-Ouest et Nord –Sud dans les Albanides externes. Les vitesses de déplacements ont été quantifiées par GPS continu et épisodiques à partir de 2003. Ces vitesses ainsi que les mécanismes au foyer montrent un raccourcissement en cours à travers l'Adriatique (déplacements des Albanides externes vers l'ouest par rapport à la plaque Apulie), et un déplacement vers le sud des Albanides internes à la fois par rapport à la plaque Apulie et à la plaque Eurasie. La zone de failles Skutar-Pesh entre Albanides et Dinarides semble former la limite nord de la zone affectée par un déplacement vers le sud par rapport à l'Eurasie comprenant l'est de l'Albanie, la Macédoine, la Bulgarie et la Grèce. Les Albanides externes semblent être segmentées par des failles transverses actives (faille de Lezhë et de l'ile d'Othoni et du col de Dhërmi) associées à une importante sismicité historiques. Les Albanides internes sont affectées à la fois par une extension Nord-sud le long de la faille d'Elbasani-Diber, du graben de Korca et par une extension est-ouest de part et d'autre du graben d'Ohrid. Le domaine affecté par un déplacement vers le sud est donc limité à l'ouest par la transition antre les Albanides externes et les Albanides Internes et au nordouest par la faille de Skutar-Pesh qui se poursuit en Macédoine. Sur l'ensemble du domaine étudié, notre analyse du champ de vitesse nous conduit à privilégié l'hypothèse d'une déformation continue au détriment d'une déformation localisée aux frontières de blocs stables. / The investigation in the present thesis is focused on the South Balkan extensional region using Global Positioning System (GPS) technique. The GPS-derived velocity field from 225 episodic and continuous GPS stations covering the territory of Central and East Mediterranean for the period 1996-2009 has been analysed and discussed in the context of present-day tectonics block models. The geodynamic processes in the region of Southwest Bulgaria (SWB) and Northern Greece (NG) are investigated by GPS measurements acquired during a 12-year (1996-2008) period. SWB and NG are recent active tectonic and seismotectonic regions. The SWB is the most active seismic region of the Bulgarian territory - in the Krupnik – Kresna region one of the most catastrophic earthquakes in continental Europe during the last two centuries occurred in 1904. NG is an area with widespread seismic activity ranging from low to high with destructive earthquakes of M≥6.0 from historical to recent times. The obtained velocity field of the Earth's crust is represented by 34 points in SWB and 21 points in NG encompassing the region. The results show southward displacements between 2-10 mm/yr. The strain rates for the region obtained by GPS measurement for the region are presented and discussed together with seismological events. By comparision to the geological and seismotectonic data, the results obtained from the GPS observations confirm the present-day activity of the fault structures and the dominating extension to the north-south. This extension is in agreement with the regional tectonic model of the East Mediterranean. The current tectonics of Albania is documented by neotectonics indices and by a large number of medium size earthquakes. The focal mechanisms suggest the existence of current shortening across the external Albanides whereas the internal Albanides are affected by E-W to N-S extension. To investigate the kinematics of the Albanides, we integrate continuous and episodic GPS measurements with focal mechanisms from the Regional Centroid Moment Tensor catalogue. This study has allowed distinguishing a western Albania affected by westward motions relative to the Apulia microplate, illustrating the ongoing collision of external Albanides, whereas inner Albanides present southward motion relative to both Apulia and stable Eurasia. The Skutar-Pesh Fault Zone, between Dinarides and Albanides, is identified as the possible northern limit of an area including Albania and western Greece, affected by a clockwise rotation relative to Apulia and also the northern limit of the Balkans (inner Albanides, Macedonia, Bulgaria) affected by southward motion relative to Apulia and stable Eurasia. The other transverse fault zone of the Albanides, the Diber-Elbasani fault, appears to be affected mainly by a moderate extension. Compilation of the published GPS data with our data set allows to identify the external-inner Albanides limit as the western border of the domain (inner Albania, northern Greece, Macedonia, Bulgaria) affected by southward displacements relative to stable Eurasia, whereas Skutar-Pesh fault probably forms also its northern limit. The analysis of the velocity field for the whole studied area leads to the hypothesis of a continuous deformation to the detriment of local deformation at the borders of stable blocks.
420

Potencialidades de serviços on-line de Posicionamento por Ponto Preciso em aplicações geodésicas: uma análise envolvendo longo período de dados das estações da RBMC

Azambuja, José Luiz Fay de January 2015 (has links)
Um método de posicionamento por GNSS (Global Navigation Satellite System) que vem se popularizando nos últimos anos é o Posicionamento por Ponto Preciso (PPP). Este método de posicionamento se utiliza de dados de apenas um receptor e requer, fundamentalmente, o uso de efemérides e correções dos relógios dos satélites precisos. O PPP nos últimos anos ganhou um impulso significativo em sua popularidade devido, principalmente, ao surgimento de serviços gratuitos de processamento on-line. Entre estes serviços on-line de processamento de PPP, destaca-se o fornecido pelo NRCan (Natural Resource Canada), denominado CSRS-PPP (Canadian Spatial Reference System – Precise Point Positioning). Nesta Tese utilizou-se o serviço canadense CSRS-PPP no processamento de um longo período de dados superior a onze anos coletados em noventa e cinco das estações da RBMC. A análise das velocidades obtidas a partir das respectivas séries temporais referentes às coordenadas diárias estimadas pelo CSRS-PPP bem como a determinação de suas coordenadas – através do PPP – referidas à época 2000.4, mostraram resultados com pequenas discrepâncias quando comparadas com os valores oficiais adotados para as estações analisadas. O problema detectado, refere-se à impossibilidade da adoção de velocidades lineares de translação no sistema cartesiano X, Y e Z, tendo em vista que na grande maioria das estações constatou-se um comportamento sazonal referente à altura elipsoidal, variação esta que afeta as translações em X, Y e Z ao longo do ano. Como solução, propõe-se a adoção das velocidades de deslocamento calculadas para coordenadas planas, particularmente as coordenadas UTM, sendo a altura elipsoidal corrigida através de modelos estabelecidos em função da variação sazonal registrada em cada uma das estações da RBMC. / A positioning method for GNSS (Global Navigation Satellite System) that has become more popular in recent years is the Precise Point Positioning (PPP). The PPP refers to the positioning method that utilizes data to only one receiver and requires fundamentally the use of ephemeris and corrections to the precise satellite clock. The PPP in recent years gained a significant boost in its popularity, mainly due to the emergence of free services online processing. Among these PPP processing on-line services, there is the one provided by NRCan (Natural Resource Canada) called CSRS-PPP (Canadian Spatial Reference System - Precise Point Positioning). In this Thesis used if the Canadian service CSRS-PPP to process data for a long period upper through eleven collected at ninety-five of RBMC stations. The analysis of the rates obtained from the respective time series relating to the daily coordinates estimated by the CSRS-PPP and the determination of its coordinates - through PPP - said at the time 2000.4, showed results with minor discrepancies compared with the official values adopted for the analyzed stations. The problem detected, refers to the impossibility of adopting linear translation speeds in the Cartesian system X, Y, and Z, considering that in most of the stations found a seasonal pattern related to the ellipsoidal height, this variation that affects translations in X, Y and Z throughout the year. As a solution, it is proposed the adoption of the forward speeds calculated for planar coordinates, particularly UTM coordinates, and the ellipsoid height corrected by established models depending on seasonal variations recorded in each of the stations RBMC.

Page generated in 0.0655 seconds