95 resultados para GNSS Positioning


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Currently, the need of reliable coordinates has been one of the main objectives of the scientific and practice community. Thus, the robustness analysis of a geodetic network, aims, at analyzing if the network is robust or not, based on the maximum undetectable errors. The network will be robust if the influence of these errors is small, otherwise it is weak, or not robust. This analysis is performed with the merger of two techniques, one which deals with the statistical analysis of reliability and the other one with the geometric strength analysis. The reliability analysis will provide the maximum error that cannot be detected by tests, after the adjustment. After finding these errors, the geometric strength analysis will determine the potential strain that the network will have, based on these errors. It is emphasized that the robustness analysis doesn't depend of the datum, reflecting only the geometry of the network and the accuracy of the observations (VANÌCEK et al., 2001). Therefore, this work aims at contributing to the scientific research on geodetic networks, checking the same, based on their geometry and observations.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Background: This study analyzed the positioning of the head, trunk, and upper extremities during gait in children with visual impairment. Methods: A total of 11 children participated in this study: 6 with blindness and 5 with low vision. The kinematics of the positioning of the head, trunk, shoulders, and elbows in each participant was analyzed during the four phases of the gait cycle: foot strike, support, toe-off, and swing. Results: There were significant differences between children with blindness and low vision in the positioning of the trunk in the sagittal plane during the foot strike, support, and swing phases. Conclusions: The analysis identified postural alterations of the head, trunk, shoulder, and elbow during the children’s gait, highlighting the relevance of appropriate stimulation at an early age in orientation and mobility programs, as well as the essential presence of professionals who work with movement.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The use of the Global Positioning System technology has brought a real revolution in the surveying and georeferencing techniques, which are the basis for many others relevant studies to the many fields of Geography. In this sense, it was seen a massive growth of the use of GNSS receivers in Brazil from the early 2000s, due the duty of Georreferencing Rural Properties to comply with the 10.267/2001 law. For Georreferencing, it is needed high accuracy receivers, and most of time, it is used two receivers: one static base and one rover. To do the adjustment of the base (in order to correct errors), two ways are utilized: post-processing via the brazilian GNSS network - Rede Brasileira de Monitoramento Contínuo dos Sistemas GNSS (RBMC) or via Precise Point Positioning - Posicionamento por Ponto Preciso, both managed by IBGE. Given the wide range of applications as well as discussions on the accuracy of both methods, this monograph aims to conduct a comparative analysis and prove the effectiveness of both methods considering the INCRA’s Standard for Rural Properties Georreferencing. From the processing of GNSS data collected in Piracicaba, Ituverava, Iperó and São Pedro, it could be seen that the research reached the objectives and shows that both methods are accurate and feasible

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Estimation of tropospheric gradients in GNSS data processing is a well-known technique to improve positioning (e.g. Bar-Sever et al., 1998; Chen and Herring, 1997). More recently, several authors also focused on the estimation of such parameters for meteorological studies and demonstrated their potential benefits (e.g. Champollion et al., 2004). Today, they are routinely estimated by several global and regional GNSS analysis centres but they are still not yet used for operational meteorology.This paper discusses the physical meaning of tropospheric gradients estimated from GPS observations recorded in 2011 by 13 permanent stations located in Corsica Island (a French Island in the western part of Italy). Corsica Island is a particularly interesting location for such study as it presents a significant environmental contrast between the continent and the sea, as well as a steep topography.Therefore, we estimated Zenith Total Delay (ZTD) and tropospheric gradients using two software: GAMIT/GLOBK (GAMIT version 10.5) and GIPSY-OASIS II version 6.1. Our results are then compared to radiosonde observations and to the IGS final troposphere products. For all stations we found a good agreement between the ZWD estimated by the two software (the mean of the ZWD differences is 1 mm with a standard deviation of 6 mm) but the tropospheric gradients are in less good agreement (the mean of the gradient differences is 0.1 mm with a standard deviation of 0.7 mm), despite the differences in the processing strategy (double-differences for GAMIT/GLOBK versus zero-difference for GIPSY-OASIS).We also observe that gradient amplitudes are correlated with the seasonal behaviour of the humidity. Like ZWD estimates, they are larger in summer than in winter. Their directions are stable over the time but not correlated with the IWV anomaly observed by ERA-Interim. Tropospheric gradients observed at many sites always point to inland throughout the year. These preferred directions are almost opposite to the largest slope of the local topography as derived from the world Digital Elevation Model ASTER GDEM v2. These first results give a physical meaning to gradients but the origin of such directions need further investigations.

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Aim: The aim of this report is to describe a quick and simple method of positioning retention magnets when deformed patients are rehabilitated with an oculopalpebral prostheses attached to a maxillary denture/obturator. Background: In patients with deformities requiring complex rehabilitations, the use of magnets is the most efficient means of providing combined prostheses with retention quality and stability. Usually prostheses with magnets are in sections and have a magnet in each section. When the sections are put together properly, the magnets are attracted to each other and retain the sections. Report: An edentulous patient presented for a post-surgical evaluation of a maxillofacial prosthesis used to repair a partial maxillectomy and left orbital exoneration which removed all adjacent tissues leaving an open communication between the oral, nasal, and orbital cavities. The proposed treatment plan included construction of a maxillary complete denture with a palatal obturator and a mandibular complete denture. Magnets were used to attach the oculopalpebral prosthesis to the maxillary denture/obturator. Summary: Use of retention magnets simplify the clinical and laboratorial phase, retains the denture, and makes it stable and comfortable for the patient. This treatment is one successful approach to the restoration of oral function and increases the patient’s quality of life.

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To compare peri-implant soft- and hard-tissue integration at implants installed juxta- or sub-crestally. Furthermore, differences in the hard and soft peri-implant tissue dimensions at sites prepared with drills or sonic instruments were to be evaluated. Three months after tooth extraction in six dogs, recipient sites were prepared in both sides of the mandible using conventional drills or a sonic device (Sonosurgery(®) ). Two implants with a 1.7-mm high-polished neck were installed, one with the rough/smooth surface interface placed at the level of the buccal bony crest (control) and the second placed 1.3 mm deeper (test). After 8 weeks of non-submerged healing, biopsies were harvested and ground sections prepared for histological evaluation. The buccal distances between the abutment/fixture junction (AF) and the most coronal level of osseointegration (B) were 1.6 ± 0.6 and 2.4 ± 0.4 mm; between AF and the top of the bony crest (C), they were 1.4 ± 0.4 and 2.2 ± 0.2 mm at the test and control sites, respectively. The top of the peri-implant mucosa (PM) was located more coronally at the test (1.2 ± 0.6 mm) compared to the control sites (0.6 ± 0.5 mm). However, when the original position of the bony crest was taken into account, a higher bone loss and a more apical position of the peri-implant mucosa resulted at the test sites. The placement of implants into a sub-crestal location resulted in a higher vertical buccal bone resorption and a more apical position of the peri-implant mucosa in relation to the level of the bony crest at implant installation. Moreover, peri-implant hard-tissue dimensions were similar at sites prepared with either drills or Sonosurgery(®) .