Deviation of light path in Born-Infeld type gravitational field

The discovery of ＂twin quasi-stellar objects＂ arose interests among astronomers and astrophysicists to study gravitational leasing problem. Deviation of light from straight path is caused by the presence of massive objects, i.e., the presence of gravitational field according to the general theory of relativity. It is shown that the low energy effective field theory on D-branes is of the Born-Infeld type. In this work a Born-Infeld type gravitational field is pasttflated. An explicit representation of the angular deviation of light path is derived based on the space time metric in the Born-Infeld theory.

Methane concentration detection system based on differential infrared absorption

The infrared absorption method for methane concentration detection is an ideal way to detect methane at present. However, it is difficult to spread this method due to its high cost. In this paper, by using a wideband infrared light emitting di- ode （LED） accompanied with a PIN photo electric diode, a low-cost methane detection system was designed. To overcome the shortcomings caused by the wide working band, a differential light path was designed. By means of a differential ratio algo- rithm, the stability and the accuracy of the system were guaranteed. Finally, the validity of the system with the proposed algo- rithm was verified by the experiment results.

The Mathematical Thoughts and Physics Interpretations of Rainbow from Ancient to Modern Times

With the aim of building a more precise mathematical model of better predictability for the formation of the supernumerary rainbow and fogbow and seeking a clearer and more elaborate physical interpretation, this paper examines the relationship between different rainbow patterns and droplet sizes through both analytical derivation and numerical simulation and develops a much more detailed model beyond previous explanations. From Newton’s geometric model of optics to Young’s wave model, the paper first establishes a solid foundation for the understanding of the formation of the rainbow in nature and through human vision, and then goes on examining the interferences of light, finally applying the model in reality for a better understanding of complex rainbow phenomena, with additional analysis on an unexpected finding about the correspondence of maximum view angle and shortest light path through hypothetical explanation based on the principle of least time and simulation of an elliptical droplet.

Variance Analysis and Adaptive Sampling for Indirect Light Path Reuse

In this paper, we study the estimation variance of a set of global illumination algorithms based on indirect light path reuse. These algorithms usually contain two passes -- in the first pass, a small number of indirect light samples are generated and evaluated, and they are then reused by a large number of reconstruction samples in the second pass. Our analysis shows that the covariance of the reconstruction samples dominates the estimation variance under high reconstruction rates and increasing the reconstruction rate cannot effectively reduce the covariance. We also find that the covariance represents to what degree the indirect light samples are reused during reconstruction. This analysis motivates us to design a heuristic approximating the covariance as well as an adaptive sampling scheme based on this heuristic to reduce the rendering variance. We validate our analysis and adaptive sampling scheme in the indirect light field reconstruction algorithm and the axis-aligned filtering algorithm for indirect lighting. Experiments are in accordance with our analysis and show that rendering artifacts can be greatly reduced at a similar computational cost.