Minimally modified balanced codes

We present and analyze a new construction of bipolar balanced codes where each codeword contains equally many -1's and +1's. The new code is minimally modified as the number of symbol changes made to the source word for translating it into a balanced codeword is as small as possible. The balanced codes feature low redundancy and time...

Data-driven hazardous gas dispersion modeling using the integration of particle filtering and error propagation detection

The accurate prediction of hazardous gas dispersion process is essential to air quality monitoring and the emergency management of contaminant gas leakage incidents in a chemical cluster. Conventional Gaussian-based dispersion models can seldom give accurate predictions due to inaccurate input parameters and the computational errors. In order...

Level of detail in 3D city models

The concept of level of detail (LOD) describes the content of 3D city models and it plays an essential role during their life cycle. On one hand it comes akin to the concepts of scale in cartography and LOD in computer graphics, on the other hand it is a standalone concept that requires attention. LOD has an influence on tendering and...

PIV uncertainty propagation

This paper discusses the propagation of the instantaneous uncertainty of PIV measurements to statistical and instantaneous quantities of interest derived from the velocity field. The expression of the uncertainty of vorticity, velocity divergence, mean value and Reynolds stresses is derived. It is shown that the uncertainty of vorticity and...

High-precision positioning of radar scatterers

Remote sensing radar satellites cover wide areas and provide spatially dense measurements, with millions of scatterers. Knowledge of the precise position of each radar scatterer is essential to identify the corresponding object and interpret the estimated deformation. The absolute position accuracy of synthetic aperture radar (SAR) scatterers in...

Extending the BEM for Elastic Contact Problems Beyond the Half-Space Approach

The boundary element method (BEM) is widely used in fast numerical solvers for concentrated elastic contact problems arising from the wheel-rail contact in the railway industry. In this paper we extend the range of applicability of BEM by computing the influence coefficients (ICs) numerically. These ICs represent the Green's function of the...

Extending the BEM for elastic contact problems beyond the half-space approach

In this paper we extend the range of applicability of the boundary element method (BEM) for concentrated elastic contact problems by computing the influence coefficients (ICs) numerically. These ICs represent the Green's function of the problem, i.e. the surface deformation due to unit loads. For the half-space they are analytically available....

Extending the BEM for elastic contact problems beyond the half-space approach

In this paper we extend the range of applicability of the boundary element method (BEM) for concentrated elastic contact problems by computing the influence coefficients (ICs) numerically. These ICs represent the Green's function of the problem, i.e. the surface deformation due to unit loads. For the half-space they are analytically available....

Error propagation in the computation of volumes in 3D city models with the Monte Carlo method

This paper describes the analysis of the propagation of positional uncertainty in 3D city models to the uncertainty in the computation of their volumes. Current work related to error propagation in GIS is limited to 2D data and 2D GIS operations, especially of rasters. In this research we have (1) developed two engines, one that generates random...

Computing the vertical density and seismic velocity profiles from multi-angle reflection data: Error analysis

Numerical models were used to recursively compute the density profile and the seismic velocity profile of three different artificial models of the underground from primary reflection images obtained from multi-angle incident plane wave reflection data. The aim is to investigate the effect of errors in the obtained primary reflection amplitudes...

Accuracy assessment of airborne laser scanning strips using planar features

Airborne Laser Scanning (ALS) is widely used in many applications for its high measurement accuracy, fast acquisition capability, and large spatial coverage. Accuracy assessment of the ALS data usually relies on comparing corresponding tie elements, often points or lines, in the overlapping strips. This paper proposes a new approach to strip...