scholarly journals Aspectos da Otimização e Processamento de Redes GPS

2003 ◽  
Vol 30 (2) ◽  
pp. 51 ◽  
Author(s):  
MÁRCIA CRISTINA MARINI ◽  
JOÃO FRANCISCO GALERA MONICO
Keyword(s):  
Network Optimization ◽  
High Reliability ◽  
Geodetic Network ◽  
First Order ◽  
Gps Network ◽  
Gps Networks ◽  
Network Application ◽  
Low Costs ◽  
Fixed Solution ◽  
Gps Observations

This paper deals with some aspects which should be taken into account for the densification of geodetic network using GPS technology, specially in the concern of Earth body tide modes, ambiguity resolution and the variance propagation of the network constrains. Based on trials accomplished for a GPS network, some aspects of GPS network optimization and processing are presented. In network optimization, applied to GPS networks, are presented the Zero Order, First Order and Second Order Problems, showing the needs of planning the GPS observations and processing in such a way that one can reach the required accuracy with high reliability and low costs. In the tests to evaluate the need for applying Earth body tide model, it was verified that it is necessary for baselines longer than 200 km for the majority of network application. It was noticed that the ambiguity solution should always be analyzed before accepting a fixed solution as the best, since the presented results demonstrated that some fixed ambiguities are inconsistent. In the processing trials with fixed constrains (without taken into account the precision) or fiducial constrains (with associated precision), it was noticed that the former provided better dispersion values for the new points, however, the last one provided more reliable values, since the new points have associated with themselves the uncertainty of the datum points.

scholarly journals Ionospheric Modelling using GPS to Calibrate the MWA. I: Comparison of First Order Ionospheric Effects between GPS Models and MWA Observations

2015 ◽  
Vol 32 ◽  
Author(s):  
B. S. Arora ◽  
J. Morgan ◽  
S. M. Ord ◽  
S. J. Tingay ◽  
N. Hurley-Walker ◽  
...  
Keyword(s):  
Gps Receiver ◽  
Radio Observatory ◽  
Ionospheric Effects ◽  
First Order ◽  
Ionospheric Gradients ◽  
Gps Networks ◽  
Position Shift ◽  
Ionospheric Modelling ◽  
Gps Station ◽  
Gps Observations

AbstractWe compare first-order (refractive) ionospheric effects seen by the MWA with the ionosphere as inferred from GPS data. The first-order ionosphere manifests itself as a bulk position shift of the observed sources across an MWA field of view. These effects can be computed from global ionosphere maps provided by GPS analysis centres, namely the CODE. However, for precision radio astronomy applications, data from local GPS networks needs to be incorporated into ionospheric modelling. For GPS observations, the ionospheric parameters are biased by GPS receiver instrument delays, among other effects, also known as receiver DCBs. The receiver DCBs need to be estimated for any non-CODE GPS station used for ionosphere modelling. In this work, single GPS station-based ionospheric modelling is performed at a time resolution of 10 min. Also the receiver DCBs are estimated for selected Geoscience Australia GPS receivers, located at Murchison Radio Observatory, Yarragadee, Mount Magnet and Wiluna. The ionospheric gradients estimated from GPS are compared with that inferred from MWA. The ionospheric gradients at all the GPS stations show a correlation with the gradients observed with the MWA. The ionosphere estimates obtained using GPS measurements show promise in terms of providing calibration information for the MWA.

Analysis of the geodetic network points displacements due to the Brawley Swarm Earthquake M5.3, 2012.08.26 according to GPS observations

2017 ◽  
Vol 929 (11) ◽  
pp. 22-28
Author(s):  
A.Y. Melnikov ◽  
V.D. Golikov
Keyword(s):  
Geodetic Network ◽  
Gps Network ◽  
Before And After ◽  
Gps Observations

The results of observations at permanent GPS network points located in the Brawley Swarm (M5.3) earthquake region, which occurred on August 26, 2012 in California, USA are analyzed in this work. The results of determining the annual displacements of GPS network points before and after the earthquake in the period from 2006 to 2016 are analyzed. Values characteristics of the displacements are calculated by two methods

scholarly journals A priori sensitivity analysis for densification GPS networks and their capacities of crustal deformation monitoring: a real GPS network application

2014 ◽  
Vol 14 (5) ◽  
pp. 1299-1308 ◽  
Author(s):  
P. Küreç ◽  
H. Konak
Keyword(s):  
Sensitivity Analysis ◽  
Crustal Deformation ◽  
A Priori ◽  
Deformation Monitoring ◽  
Crustal Movement ◽  
Gps Network ◽  
Minimum Displacement ◽  
Gps Networks ◽  
Network Application ◽  
New Criteria

Abstract. The main purpose of this study is to investigate the possibilities of monitoring crustal movement, during collective evaluation of first- and second-order GPS densification networks. The new criteria, which are independent from the network datum, are widely used for the evaluation and quality processing of geodetic networks. In this study, the values of detectable minimum displacement for a real GPS network are investigated as well as how sensitivity levels are affected by additional datum conditions, which are added to the adjustment model.

scholarly journals Adaptive Least-Squares Collocation Algorithm Considering Distance Scale Factor for GPS Crustal Velocity Field Fitting and Estimation

2019 ◽  
Vol 11 (22) ◽  
pp. 2692 ◽  
Author(s):  
Wei Qu ◽  
Hailu Chen ◽  
Shichuan Liang ◽  
Qin Zhang ◽  
Lihua Zhao ◽  
...  
Keyword(s):  
Least Squares ◽  
Covariance Function ◽  
High Reliability ◽  
Scale Factor ◽  
Distance Scale ◽  
Crustal Movement ◽  
Least Squares Collocation ◽  
Crustal Velocity ◽  
Regional Tectonic ◽  
Gps Observations

High-precision, high-reliability, and high-density GPS crustal velocity are extremely important requirements for geodynamic analysis. The least-squares collocation algorithm (LSC) has unique advantages over crustal movement models to overcome observation errors in GPS data and the sparseness and poor geometric distribution in GPS observations. However, traditional LSC algorithms often encounter negative covariance statistics, and thus, calculating statistical Gaussian covariance function based on the selected distance interval leads to inaccurate estimation of the correlation between the random signals. An unreliable Gaussian statistical covariance function also leads to inconsistency in observation noise and signal variance. In this study, we present an improved LSC algorithm that takes into account the combination of distance scale factor and adaptive adjustment to overcome these problems. The rationality and practicability of the new algorithm was verified by using GPS observations. Results show that the new algorithm introduces the distance scale factor, which effectively weakens the influence of systematic errors by improving the function model. The new algorithm can better reflect the characteristics of GPS crustal movement, which can provide valuable basic data for use in the analysis of regional tectonic dynamics using GPS observations.

scholarly journals Design of electromechanical height adjustable suspension

2017 ◽  
Vol 232 (9) ◽  
pp. 1253-1269 ◽  
Author(s):  
Nicola Amati ◽  
Andrea Tonoli ◽  
Luca Castellazzi ◽  
Sanjarbek Ruzimov
Keyword(s):  
Aerodynamic Drag ◽  
High Reliability ◽  
Environmental Issues ◽  
Emissions Reduction ◽  
General Context ◽  
Passenger Vehicles ◽  
Potential Benefits ◽  
Vehicle Motion ◽  
Low Costs ◽  
Fuel Consumption And Emissions

In the general context of vehicles’ fuel consumption and emissions reduction, the minimization of the aerodynamic drag can offer not negligible benefits regarding the environmental issues. The adjustment of the vehicle height is one of the possible ways to provide a reduction of the resistances to vehicle motion, in addition to consequent aspects regarding the increased versatility of the vehicle. The aim of this paper is to present in a systematic way the state of the art of height adjustment systems for passenger vehicles, summarizing the main modes of operations, working principles, and architectures. Particular attention is then given to electromechanical systems, which represent the next trends for future vehicles due to their high reliability and relatively low costs. A design methodology for electromechanical height adjustment systems with the purpose of optimizing their performance is presented. Such procedure is able to reach the most efficient working point even in presence of constraints of different nature. Prototypes have been designed, produced and tested to demonstrate the potentialities of electromechanical height adjustment systems. Furthermore, potential benefits and drawbacks of using such systems are highlighted.

Analysis of Mechanism Reliability in Anti-Dislocation Locking of Space Cable-Strut Deployable Articulated Mast

2013 ◽  
Vol 753-755 ◽  
pp. 1145-1150
Author(s):  
Zhong Qiang Tan ◽  
Ming Yan Zhao ◽  
Shi Jiao Wang
Keyword(s):  
Room Temperature ◽  
High Reliability ◽  
Space Environment ◽  
First Order ◽  
Locking Mechanism ◽  
First Order Second Moment ◽  
Space Limit ◽  
Working Principle ◽  
Assembly Error ◽  
Actual Size

The study is limit-locking mechanism of space cable-strut deployable articulated mast. On the base of structure and working principle, the mechanism’s failure in ant-dislocation locking is analyzed and a new analytical model of reliability has been constructed. In the process of calculating reliability index, the factors such as size, assembly error, and space environment influence have been taken into consideration, and the method of MFOSM (Mean First Order Second Moment) has been applied. Based on the actual size of the mechanism, reliabilities of mechanism ant-dislocation locking have been calculated at both room temperature and space limit temperature. The main influencing factors have been analyzed and the improvement has been put forward. Calculations show that the new model has a high reliability in ant-dislocation locking.

Second-Order Decisions

2017 ◽  
Author(s):  
Edna Ullmann-Margalit
Keyword(s):  
Second Order ◽  
Costs And Benefits ◽  
First Order ◽  
Low Costs

People are often reluctant to make decisions by calculating the costs and benefits of alternative courses of action in particular cases. Knowing, in addition, that they may err, people and institutions often resort to second order strategies for reducing the burdens of, and risk of error in, first order decisions. They make a second order decision when they choose one from among such possible strategies. They adopt rules or presumptions; they create standards; they delegate authority to others; they take small steps; they pick rather than choose. Some of these strategies impose high costs before decision but low costs at the time of ultimate decision; others impose low costs both before and at the time of ultimate decision; still others impose low costs before decision while exporting to others the high costs at the time of decision.

ENHANCEMENT THE QUALITY OF THE EGYPTL4N FIRST ORDER GEODETIC NETWORK USING GPS DATA.

2009 ◽  
Vol 32 (1) ◽  
pp. 89-94
Author(s):  
A. M Rahil ◽  
A. M El Gohary ◽  
M. I Doma ◽  
A. F El Shony
Keyword(s):  
Geodetic Network ◽  
Gps Data ◽  
First Order
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