94 resultados para 482
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
The stiffness behaviour of injection moulded short glass fibre/impact modifier/polypropylene hybrid composites has been investigated in this work by theoretical predictions and experiments. Predictions from the self-consistent method were found to be in good agreement with test results for the impact modifier/polypropylene blends. By taking into account of the fibre orientation distributions in the skin and core layers, the values of Young's modulus for the skin and core layers were predicted by employing Eshelby's equivalent inclusion method and the average induced strain approach. The prediction of the values of Young's modulus for the whole sample was obtained by applying the simple mixture theory of laminated composites to the predicted results for the skin and core layers. Good correlation between predicted and experimental Young's modulus values were found.
Resumo:
A remarkably increased coagulation rate for 2-mu m PS spheres was previously reported for a perikinetic coagulation experiment performed under microgravity conditions (1998, R. Folkersma, A. J. G. van Diemen, and H. N. Stein, J. Colloid Interface Sci. 206, 482); from this experiment, it was assumed that the leading factor slowing the coagulation process under normal gravitation was free convection due to gravity (1998, R. Folkersma, and H. N. Stein, J. Colloid Interface Sci. 206, 494). To test the influence of free convection as a single-effect factor on the coagulation process, a ground-based experiment was constructed. The coagulation rate of 2-mu m PS spheres dispersed in water was determined by measuring the turbidity of the dispersion solution while convection-driven flows in the solution were checked with a visual magnification system. We found that it was possible to cease free convection-driven particle flows on the ground, as long as the experiments were carefully operated. The strength of convection was controlled by changing the temperature gradient applied to the sample cell. By monitoring both the coagulation rate and convection-driven flows simultaneously, our experiments showed that weak free convection (maximum speed <150 mu m/s) actually has negligible effects on the coagulation rate.
Resumo:
介绍水蚀性岩层中的渗流及金属和无机污染物迁移问题。用高渗透率多孔介质中的流动基本方程近似描述,而对流、水动力学扩散、稀释等影响可作为物理过程来阐述。总之,控制裂隙岩体中地下水流动与研究污染物输运的物理和化学机理,是建立水蚀性岩层中无机污染物输运近似方法的基础。
Resumo:
本文用 Split-Hopkinson 压力杆装置研究了应力波通过破裂岩石试件的衰减现象。给出了灰砂岩、石灰岩两种岩石动态的破裂强度与应力应变关系.结合受应力作用的岩样切片的微观观察,对应力裂纹、裂纹的动态分叉现象进行了分析讨论.
Resumo:
今年12月11日是国际著名力学家,我国近代力学的奠基人,我国航天技术的开创者和系统工程科学家,中国力学学会和中国空气动力学学会的创始人,钱学森先生的90华诞.中国力学学会和中国空气动力学学会等21个单位举办“新世纪力学研讨会──钱学森技术科学思想的回顾与展望”会议,重温他发展力学的丰富思想,共同探讨我国新世纪力学的前进道路.本期刊出《钱学森先生简介》、郑哲敏院士的《祝贺钱学森院士90寿辰》以及研讨会的3篇大会报告,以表示对钱学森先生90华诞的祝贺。
Resumo:
The influence of focus spot and target thickness on multi-keV x-ray sources generated by 2 ns duration laser heated solid targets are investigated on the Shenguang II laser facility. In the case of thick-foil targets, the experimental data and theoretical analysis show that the emission volume of the x-ray sources is sensitive to the laser focus spot and proportional to the 3 power of the focus spot size. The steady x-ray flux is proportional to the 5/3 power of the focus spot size of the given laser beam in our experimental condition. In the case of thin-foil targets, experimental data show that there is an optimal foil thickness corresponding to the given laser parameters. With the given laser beam, the optimal thin-foil thickness is proportional to the -2/3 power of the focus spot size, and the optimal x-ray energy of thin foil is independent of focus spot size. (C) 2008 American Institute of Physics.
Resumo:
An optoelectronic implementation based on optical neighborhood operations and electronic nonlinear feedback is proposed to perform morphological image processing such as erosion, dilation, opening, closing and edge detection. Results of a numerical simulation are given and experimentally verified.