908 resultados para global positioning systems


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In this paper, we propose an original method to geoposition an audio/video stream with multiple emitters that are at the same time receivers of the mixed signal. The obtained method is suitable when a list of positions within a known area is encoded with precision tailored to the visualization capabilities of the target device. Nevertheless, it is easily adaptable to new precision requirements, as well as parameterized data precision. This method extends a previously proposed protocol, without incurring in any performance penalty.

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Mode of access: Internet.

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Bill Chappell, Jr., chairman, Subcommittee on Defense, Committee on Appropriations, House of Representatives. -- p. [1].

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Advances in communication, navigation and imaging technologies are expected to fundamentally change methods currently used to collect data. Electronic data interchange strategies will also minimize data handling and automatically update files at the point of capture. This report summarizes the outcome of using a multi-camera platform as a method to collect roadway inventory data. It defines basic system requirements as expressed by users, who applied these techniques and examines how the application of the technology met those needs. A sign inventory case study was used to determine the advantages of creating and maintaining the database and provides the capability to monitor performance criteria for a Safety Management System. The project identified at least 75 percent of the data elements needed for a sign inventory can be gathered by viewing a high resolution image.

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Since turning professional in 1995 there have been considerable advances in the research on the demands of rugby union, largely using Global Positioning System (GPS) analysis over the last 10 years. A systematic review on the use of GPS, particularly the setting of absolute (ABS) and individual (IND) velocity bands in field based, intermittent, high-intensity (HI) team sports was undertaken. From 3669 records identified, 38 studies were included for qualitative analysis. Little agreement on the definition of movement intensities within team sports was found, only three papers, all on rugby union, had used IND bands, with only one comparing ABS and IND methods. Thus, the aim of this study was to determine if there is a difference in the demands within positions when comparing ABS and IND methods for GPS analysis and if these differences are significantly different between the forward and back positional groups. A total of 214 data files were recorded from 26 players in 17 matches of the 2015/2016 Scottish BT Premiership. ABS velocity zones 1-7 were set at 1) 0-6, 2) 6.1-11, 3) 11.1-15, 4) 15.1-18, 5) 18.1-21, 6) 21.1-15 and 7) 25.1-40km.h-1 while IND zones 1-7 were 1) <20, 2) 20-40, 3) 40-50, 4) 50-70, 5) 70-80, 6) 80-95 and 7) 95-100% of player’s individually determined maximum velocity (Vmax). A 40m sprint test measured Vmax using OptaPro S4 10 Hz (catapult, Australia) GPS units to derive IND bands. The same GPS units were worn during matches. GPS outputs analysed were % distance, % time, high intensity efforts (HIEs) over 18.1 km.h-1 / 70% max velocity and repeated high intensity efforts (RHIEs) which consists of three HIEs in 21secs. General linear model (GLM) analysis identified a significant difference in the measurement of % total distance covered, between the ABS and IND methods in all zones for forwards (p<0.05) and backs (p<0.05). This difference was also significant between forwards and backs in zones 1, shown as mean difference ± standard deviation (3.7±0.7%), 6 (1.2±0.4%) and 7 (1.0±0.0%) respectively (p<0.05). Percentage time estimations were significantly different between ABS and IND analysis within forwards in zones 1 (1.7±1.7%), 2 (-2.9±1.3%), 3 (1.9±0.8%), 4 (-1.4±0.8%) and 5 (0.2±0.4%), and within backs in zones 1 (-10±1.5%), 2 (-1.2±1.1%), 3 (1.8±0.9%) and 5 (0.6±0.5%) (p<0.05). The difference between groups was significant in zones 1, 2, 4 and 5 (p<0.05). The number of HIEs was significantly different between forwards and backs in zones 6 (6±2) and 7 (3±2). RHIEs were significantly different between ABS and IND for forwards (1±2, p<0.05) although not between groups. Until more research on the differences in ABS and IND methods is carried out, then neither can be deemed a criterion method. In conclusion, there are significant differences between the ABS and IND methods of GPS analysis of the physical demands of rugby union, which must be considered when used to inform training load and recovery to improve performance and reduce injuries.

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Desde hace algunos años los sistemas de Posicionamiento Global (SPG) se están imponiendo como una herramienta interesante e, incluso, imprescindible para el posicionamiento y la navegación – marítima, aérea y terrestre – y con importantes aplicaciones en los campos de la cartografía, la teledetección, los sistemas de información Geográfica, la Topografía, etc. En este artículo realizamos una introducción a los SPG, haciendo un repaso de los componentes, de la forma de calcular la distancia, de la precisión y de la metodología de trabajo con ellos.ABSTRACT For some years now, Global Positioning Systems (GPS) have become interesting and indispensable tools for determining geographical positioning for air, land and marine navigation, as well as having important applications in the area on Cartography, Remote Sensing, Geographical Information Systems, Surveying, etc. In this article, we present an introduction to GPS and summarize the necessary components, ways to calculate distance and precision, and methodologies for working with them.

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Este articulo tal como reza en su titulo, reúne la aplicación de tres tecnologías diferentes en la geografía actual: Sistemas de Posicionamiento Global (SPG), Sistemas de Información Geográfica (SIG) y Teledetección, lo cual es importante para los investigadores de estos temas y para el lector común científico o no. Pero la principal finalidad del trabajo es que sus contenidos rigurosos, metodológica y teóricamente tratan de análisis histórico del uso de los recursos naturales y la evolución ecológica en uno de los países mas devastados por todo tipo de calamidad: los desastres naturales, los desastres sociales-guerra- y las enfermedades. Lo anterior lo califica como uno de los países más pobres de Centroamérica y del mundo. El sudeste de Nicaragua es la <<muestra>> de nuestros países expoliados, exportadores de materia prima, endeudados con los entes financieros y con todo tipo de debilidad interna: desempleo, bajos salarios, desigualdad en la repartición de la tierra, dominio empresarial de una <<oligarquía>>, agricultura de subsistencia, factores ambientales negativos. Como se señalará más adelante, <<a los habitantes les gusta decir que llueve trece meses al año>>. Este último factor, constituye una dificultad metodológica porque la cantidad de nubosidad impide realizar trabajos <<óptimos>>. No obstante, el trabajo deja ver las consecuencias de la deforestación para el pastoreo y algunos cultivos (monocultivos y productos para el mercado externo). En conclusión, el estudio lleva a la consecución de la distribución del uso del suelo, la delimitación de la frontera agrícola y la elaboración del mapa respectivo para 1992, elementos que permiten comparar el gran avance de la frontera agrícola observando un mapa del instituto Nicaragüense de Estudios Territoriales (INETER) de 1983.  ABSTRACT This article focuses on the application of Global Positioning Systems (GPS), Geographical Information Systems (GIS), and Remote Sensing to the study of the agricultural frontier of Southeastern Nicaragua in the elaboration of a land use map of this area. The methodology of map elaboration, bases on LANDSAT satellite imagines, is explained. A report on deforestation processes and the agrarian frontier in Nicaragua within the context of Central America is also included.

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This paper firstly presents an extended ambiguity resolution model that deals with an ill-posed problem and constraints among the estimated parameters. In the extended model, the regularization criterion is used instead of the traditional least squares in order to estimate the float ambiguities better. The existing models can be derived from the general model. Secondly, the paper examines the existing ambiguity searching methods from four aspects: exclusion of nuisance integer candidates based on the available integer constraints; integer rounding; integer bootstrapping and integer least squares estimations. Finally, this paper systematically addresses the similarities and differences between the generalized TCAR and decorrelation methods from both theoretical and practical aspects.

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In this paper, the problems of three carrier phase ambiguity resolution (TCAR) and position estimation (PE) are generalized as real time GNSS data processing problems for a continuously observing network on large scale. In order to describe these problems, a general linear equation system is presented to uniform various geometry-free, geometry-based and geometry-constrained TCAR models, along with state transition questions between observation times. With this general formulation, generalized TCAR solutions are given to cover different real time GNSS data processing scenarios, and various simplified integer solutions, such as geometry-free rounding and geometry-based LAMBDA solutions with single and multiple-epoch measurements. In fact, various ambiguity resolution (AR) solutions differ in the floating ambiguity estimation and integer ambiguity search processes, but their theoretical equivalence remains under the same observational systems models and statistical assumptions. TCAR performance benefits as outlined from the data analyses in some recent literatures are reviewed, showing profound implications for the future GNSS development from both technology and application perspectives.

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This dissertation develops the model of a prototype system for the digital lodgement of spatial data sets with statutory bodies responsible for the registration and approval of land related actions under the Torrens Title system. Spatial data pertain to the location of geographical entities together with their spatial dimensions and are classified as point, line, area or surface. This dissertation deals with a sub-set of spatial data, land boundary data that result from the activities performed by surveying and mapping organisations for the development of land parcels. The prototype system has been developed, utilising an event-driven paradigm for the user-interface, to exploit the potential of digital spatial data being generated from the utilisation of electronic techniques. The system provides for the creation of a digital model of the cadastral network and dependent data sets for an area of interest from hard copy records. This initial model is calibrated on registered control and updated by field survey to produce an amended model. The field-calibrated model then is electronically validated to ensure it complies with standards of format and content. The prototype system was designed specifically to create a database of land boundary data for subsequent retrieval by land professionals for surveying, mapping and related activities. Data extracted from this database are utilised for subsequent field survey operations without the need to create an initial digital model of an area of interest. Statistical reporting of differences resulting when subsequent initial and calibrated models are compared, replaces the traditional checking operations of spatial data performed by a land registry office. Digital lodgement of survey data is fundamental to the creation of the database of accurate land boundary data. This creation of the database is fundamental also to the efficient integration of accurate spatial data about land being generated by modem technology such as global positioning systems, and remote sensing and imaging, with land boundary information and other information held in Government databases. The prototype system developed provides for the delivery of accurate, digital land boundary data for the land registration process to ensure the continued maintenance of the integrity of the cadastre. Such data should meet also the more general and encompassing requirements of, and prove to be of tangible, longer term benefit to the developing, electronic land information industry.