Papers by Author: Yun Du

Abstract: The sci-tech novelty search institutes have accumulated a large number of novelty search commissioned data, processed scientific and technical information, professional novelty search reports and other valuable information. The statistical analysis of the information mentioned above can reflect the characteristics of one regions sci-tech innovation activities from one perspective. In this paper, based on the information of novelty search projects accomplished by Beijing Municipal Institute of Science and Technology Information in 2007-2011, we make statistical analysis on the subjects of the novelty search projects, and obtain four hotspot research fields of Beijing municipal sci-tech innovation in nearly five years: electronic information, new energy and energy efficient, optical mechanical and electronic integration, resource and environment. Then the important research branches in each hotspot research field are figured out. And one typical sci-tech innovation case is given in each hotspot research field. At last, based on the analysis of novelty search projects, the hotspots in four research fields mentioned above are put forward for the researchers to reference and make new breakthrough.

Abstract: The rock is assumed to be assembled by a great number of HMUs. The number of HMUs responding to external force is uncertain, which leads to the instability of hysteretic loops. Transition probability of HMUs to the external force and temperature varies with external loading frequency and temperature. The self-adaptive adjustment effects for rocks in frequency field are obtained by uniaxial and triaxial cyclic loading: when frequency increases, transition probability of the response of mesoscopic structure to applied loads reduces, the adjustment time of self-adaptive process becomes shorter, residual strain become smaller, and hysteretic loops tend to be easy to be stable. The self-adaptive adjustment effects in temperature field can also be obtained.

Abstract: Some preliminary experiments are conducted to investigate the responses of granite， marble and red stone in the states of natural，water-saturation and oil-saturated under the shock of short pulse laser. The 3D contour of ablation pit and the preliminary relations of the ablation contour to the number of laser pulses are obtained. The results show that some cracks generate at local places for the shock of laser，and the degree of ablation of the oil-saturated rocks is more severe than that of the natural and water saturated rocks. However，further work should be conducted to control the direction，sizes and number of cracks generated under the shock of laser.