178

S.231-238

S.315-322

Alkaline methanol oxidation is an electrochemical process, perspective for the design of efficient high energy density fuel cells. The process involves a large number of elementary reactions, forming a complex reaction graph, and it is described by a system of non-linear differential equations of high order. The purpose of parameter identification is a reconstruction of reaction constants in this model on the basis of available experimental data. Cyclic voltammetry, a measurement of dynamical current-voltage characteristic of the cell, is especially suitable for analysis of electrochemical kinetics. In this paper we present several approaches for parameter identification in cyclic voltammetry of alkaline methanol oxidation. With the aid of global optimization methods and interactive parameter study we find four islands of solutions in parameter space, corresponding to different chemical mechanisms of the process. The main features of solutions are discussed and the reconstructed reaction constants are presented.

We extend our system for radio astronomical monitoring by a module for numerical modeling of real antennas, based on the laws of wave optics. We use far field approximation, suitable for phased array radio telescopes, searching deep space signals. We have implemented the main computation on GPU, achieving acceleration factor 52 and providing real time performance of the module. Visualization of the resulting wave patterns helps to separate true deep space signals from the near Earth satellite radio interference. In particular, we model in detail a scenario of a satellite signal coming through the side lobe of SETI ATA-42 telescope. Such signals can be responsible for the false alarms in monitoring procedures, used in searching for extraterrestrial intelligence. We also analyze a scenario of searching pulsar signals with BSA/LPI radio telescope and their separation from background radio interference.

We extend our system for radio astronomical monitoring by a cross-validation filter, separating near Earth radio frequency interference (RFI) from deep space signals. The filter searches for similar signals in a nearby frequency band, coming from a different spatial direction than the tested signal. The filter passes the signals which do not have such duplicates. We apply this technique to a database of SETI Institute (setilive.org), containing 1.5 millions of sky observations in a frequency range 0.5-11.2~GHz, where our primary selection identified 28 strong signals possessing extraterrestrial (ET) signature. Cross-validation allows to filter out 24 of those signals as satellite RFI. We present parameters for the remaining 4 signals and discuss statistical significance of these findings.

S.179-186

S.64-70

In this paper we introduce Simulated Reality (SR) as a new concept for the interplay between simulation, optimization and interactive visualization. We see SR as a new metaphor for the interactive visual exploration of simulation and optimization results. The vision of Simulated Reality implies interactive behavior of simulations. Fact is today that simulations might still need hours of computation time, especially in crash worthiness. This paper shows approaches to come closer to the vision of SR. Combining design of experiments methods, metamodeling, new interpolation schemes and innovative graphics methods, we enable to user to interact with simulation parameters, optimization criteria and come to a new interpolated crash result within seconds. The approaches have been successfully applied for solution of real life car design optimization problems.

In this paper a 3D tracking system for Virtual Environments is presented which utilizes infrared (IR) laser technology. Invisible laser patterns are projected from the user(s) to the screen via the input device Sceptre or the appending headtracking device. IR-sensible cameras which are placed near the projectors in a backprojection setup recognize the pattern. That way position and orientation of the input devices is reconstructed. The infrared laser is not seen by human eye and therefore does not disturb the immersion.

We describe a system for real-time simulation of linear elastic deformations of volumetric objects in virtual environments, implemented in Avango VE framework [T. H. Avocado (1999)]. The approach makes use of the methods of finite and boundary elements and precomputed Green's functions, and supports real-time interactive deformations of large elastic models, containing more than 10,000 volumetric nodes, at the graphics update rate 85fps.

We have implemented a scheme for elimination of depolarization artefacts in passive stereo-projection systems. These problems appear due to non-perfectness of stereo-projection equipment: depolarization of the light due to reflection from the screen or due to the passage through the screen; non-ideality of polarizing filters; mixing of left- and right-eye images in a change of relative orientation of the filters. These effects lead to strong violations in stereo-perception (known as "ghosts"). They can be eliminated by software methods, using linear filtering of the image before its projection to the screen, based on the formula L' = L -/spl alpha/R, R' = R -/spl alpha/L , where L, R are images, destined for the left and right eye respectively, /spl alpha/ is constant, defining intensity of the ghosts. This receipt, in theory leading to exact compensation of the ghosts, in practice possesses certain limitations, which allow not complete elimination but only strong suppression of the ghosts, at very careful calibration of the system. We have implemented this algorithm in VE system Avango by means of texture mappings. All necessary operations are performed by the graphics board, thus providing the real-time rendering rate. The described method considerably improves stability of stereo-perception, making high-quality performances of virtual environment possible on affordable equipment.

Differential geometry and topology are the areas of higher mathematics, which particularly require visual representation of studying objects for better understanding of the material. On the other hand, the complex structure of such objects makes their visualization a challenge for modern graphical systems. In this video we demonstrate real-time methods for adequate representation of topologically non-trivial objects in virtual environment systems, particularly the acceleration of standard mechanisms for rendering of transparent surfaces, applicable for complex cases of self-intersecting time-dependent surfaces, not necessarily admitting continuous fields of normal vectors. We also use the technique of image-based rendering, which places stereo-photographs of real environments as static background for 3D virtual scenes. The methods are implemented in educational application, which demonstrates the main properties of elementary topological objects (Möbius band, Klein bottle, projective plane etc) and gives a possibility to explore interactively the complex constructions, arising in higher mathematics.