Least Squares Adjustment of Satellite Observations for Simultaneous Directions or Ranges. Part 1 - Formulation of Equations

Least squares adjustment of satellite observations for simultaneous directions or range

Least Squares Adjustment of Satellite Observations for Simultaneous Directions or Ranges. Part 3 - Subroutines

Subroutines used in computer programs for least squares adjustment of satellite observations for simultaneous directions or range

Unsupervised labelling of sequential data for location identification in indoor environments

In this paper we present indoor positioning within unknown environments as an unsupervised labelling task on sequential data. We explore a probabilistic framework relying on wireless network radio signals and contextual information, which is increasingly available in large environments. Thus, we form an informative spatial classifier without resorting to a pre-determined map, and show the potential of the approach using both simulated and real data sets. Results demonstrate the ability of the procedure to segregate structures of radio signal observations and form clustered regions in association to areas of interest to the user; thus, we show it is possible to differentiate location between closely spaced zones of variable size and shape

Robustness analysis of geodetic networks in the case of correlated observations

GPS (or GNSS) networks are invaluable tools for monitoring natural hazards such as earthquakes. However, blunders in GPS observations may be mistakenly interpreted as deformation. Therefore, robust networks are needed in deformation monitoring using GPS networks. Robustness analysis is a natural merger of reliability and strain and defined as the ability to resist deformations caused by the maximum undetecle errors as determined from internal reliability analysis. However, to obtain rigorously correct results; the correlations among the observations must be considered while computing maximum undetectable errors. Therefore, we propose to use the normalized reliability numbers instead of redundancy numbers (Baarda's approach) in robustness analysis of a GPS network. A simple mathematical relation showing the ratio between uncorrelated and correlated cases for maximum undetectable error is derived. The same ratio is also valid for the displacements. Numerical results show that if correlations among observations are ignored, dramatically different displacements can be obtained depending on the size of multiple correlation coefficients. Furthermore, when normalized reliability numbers are small, displacements get large, i.e., observations with low reliability numbers cause bigger displacements compared to observations with high reliability numbers

Acceleration of finite-difference time-domain electromagnetic simulations using graphics processor units

Bibliography: p. 65-66The Finite-Difference Time-Domain (FDTD) method is used extensively in microwave engineering and optics for Electromagnetic (EM) simulations. However, FDTD runs too slowly for some simulations to be practical, especially when run on standard desktop computers, but even when run on clusters of computers or supercomputers. The suitability of Graphics Processor Units (GPUs) for the acceleration of FDTD has been investigated. It is demonstrated that consumer GPUs can be used to accelerate two-dimensional FDTD simulations by a factor of roughly seven, relative to compiler-optimized code running on an Intel CPU of similar technology generation. In order to demonstrate this acceleration, an off-the-shelf GPU has been programmed to solve three 2-dimensional electromagnetic problems: (i) a cavity resonator; (ii) a band­gap structure with periodic boundaries; and (iii) a waveguide with ceramic fingers and Perfectly Matched Layer (PML) boundaries. OpenGL is the Application Programming Interface (API) used to program the GPU

Geodesy: the concepts

Geodes