Ray tracing algorithms rely on two dimensional or three dimensional database. They use ray optical techniques referred to as the uniform theory of diffraction (UTD) using building database given as polygons. Building geometries can also be modelled as having non-planar geometries, and this would be important in modeling of shadowing loss due to curved structures in urban radio propagation. To d...

The low-resolution structure of α-crustacyanin has been determined to 30 Å resolution using negative-stain electron microscopy (EM) with single-particle averaging. The protein, which is an assembly of eight β-crustacyanin dimers, appears asymmetrical and rather open in layout. A model was built to the EM map using the X-ray crystallographic structure of β-crustacyanin guided by PISA interface a...

Appropriate channel models are needed in order to determine the performance of new emerging space time processing techniques. This paper investigates several properties of the mobile space-time channel, which can be modeled by stochastic parameters of the time-variant azimuth-delay-power-spectrum (ADPS). The raw characteristics of the ADPS are determined from ray tracing methods using the Radio...

  Introduction: Monte Carlo (MC) is the most common method for simulating virtual SPECT projections. It is useful for optimizing procedures, evaluating correction algorithms and more recently image reconstruction as a forward projector in iterative algorithms; however, the main drawback of MC is its long run time. We introduced a model based method considering the eff...

Orbiting x-ray and gamma ray instruments are subject to large background count rates due to local particle fluxes in the space environment. The ability of an instrument to make calibrated measurements of the flux from a source of interest is highly dependent on accurately determining the background level. We present here a method of calculating the energy dependent background flux for any point...

We present a survey design that generalizes static conjoint experiments to elicit inter-temporal adoption decisions for durable goods. We show that consumers’ utility and discount functions in a dynamic discrete choice model are jointly identified using data generated by this specific design. In contrast, based on revealed preference data, the utility and discount functions are generally not jo...

Rational B-spline surfaces make it possible to merge the concepts of freeform surfaces and that of surfaces described by rational polynomials espe­ cially conic sections. For ray tracing it is crucial to determine the intersection between ray and object. Therefore an algorithm is developed that is suitable for a VLSI implementation. Some alternatives for the implementation of this algorithm are...

The biased choice model (BCM) of Lute (1963) and general recognition theory (CRT) of Ashby and Townsend (1986) are compared with respect to their ability to account for data from identification experiments. Specifically, by using CRT we investigate the ability of the BCM to account for data characterized by violations of perceptual independence and perceptual and decisional separability, and by...

PURPOSE This work aimed at quantifying the gains in spatial resolution and noise that could be achieved when using resolution modelling based on a multi-ray approach and additionally the Statistical and Heuristic Noise Extraction (SHINE) method in human pinhole single photon emission tomography (PH-SPECT). METHODS PH-SPECT of two line phantoms and one homogeneous cylinder were recorded using ...

This paper reviews the double directional channel models mainly for MIMO applications. First, the double directional channel measurements and data analysis are presented, to extract the antenna-independent propagation channel model from the MIMO channel measurement via the parametric modeling and estimation. Next, stochastic modeling approaches are introduced for the link-level simulation for t...