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991.
The transient temperature fields and dynamic thermal stress fields in gun barrel are studied in this paper, which are problems of interior ballistics.The high blast temperature and pressure act simultaneously on the inner surface of the barrel behind projectile moving in the barrel during shooting. Under this boundary condition, the governing equations of the thermoelastic problems of hollow cylinder are given, the corresponding functional is studied and the numerical results calculated by the finite element method are obtained. 相似文献
992.
Based upon the effect of land-sea interaction on the paleomonsoon variation and the time series of climatic proxy-indicators, the historical Asian monsoon variation over the last 130,000 and 18,000 years has been reconstructed with an emphasis on the basic characteristics of summer monsoon circulation. The monsoon-climatic cycles and associated model of environmental development over the central and eastern China are proposed and the mechanism of paleomonsoon variation of China preliminarily discussed. The variation of East Asian monsoon circulation should be regarded as a regional result of both solar-radiation changes and the global glacial-interglacial cycles. The episodic uplifting of the Qinghai-Xizang Plateau since the late Miocene has to a large extent controlled the forming and evolution of the paleomonsoon circulation of China. 相似文献
993.
低气压微波感耦氩等离子体空间分布特性光谱诊断 总被引:3,自引:3,他引:0
用二维光学多道分析仪研究了低气压表面波型微波感耦氬等离子体的光谱辐射特性?鼳bel反演后,得到了在各种气压和微波功率下等离子体辐射光强和激发温度的空间分布及其变化规律。讨论了此等离子体的激发机理。 相似文献
994.
A. I. Leont'ev 《Fluid Dynamics》2002,37(4):512-529
The known methods of gas-dynamic temperature stratification are reviewed. Attention is concentrated on an analysis of the possibilities of the gas dynamic stratification method proposed by the author. The method is based on the difference between the equilibrium temperature of a thermally insulated wall in supersonic flow and the adiabatic stagnation temperature of the gas. Certain possible practical applications of the method to various types of energy-converting apparatus are considered. The basic trends of fundamental and applied research in the field of gas-dynamic temperature stratification are formulated. 相似文献
995.
Thermal expansion measurements have been carried out on Fe substituted superconducting compounds Y1Ba2(Cu1−x
Fe
x
)3O
y
(0<x<4%) using a high resolution dilatometer employing the three terminal capacitance technique. The experimental set up is sensitive
enough to detect changes in α of less than 10−8K−1. Results show that the jump Δα in the coefficient of linear thermal expansion at the superconducting transition temperature,T
c, increases almost linearly with Fe concentration. The normal state thermal expansion coefficient α first decreases, attains
a minimum value aroundx=1% and then increases for higher Fe concentrations. The oxygen content per unit formula is almost constant up tox=1% and then increases rapidly withx. It has also been observed that the anomalous behaviour of α around 260 K observed by Meingastet al [22] for Fe concentrationx=5% is due to inadequate annealing of the sample. 相似文献
996.
997.
通过对新疆石英滩金矿石中冰长石的标型特征的研究表明,冰长石是一种典型的低温热液矿物,它不仅是一种研究矿床成因的标型矿物,而且还是一个寻找低温热液型金矿床的标志物,在金矿找矿中具有重要的标志作用。 相似文献
998.
999.
1000.
G. Dajk 《Radiation measurements》1997,28(1-6):133-136
Etching solutions of different compositions were applied at room temperature (22°C) for electrochemical etching. The background developed during electrochemical etching in a CR-39 track detector was investigated. Detectors irradiated with alphas of 5.49 MeV were measured also. It was found that the PEW solutions (potassiumhydroxid, ethylalcohol, water) showed good sensitivity. One of them (PEW20/40 was applied for neutrons from a 252Cf source. The achieved registration sensitivity was about 10−5 spot/n after 3 hours of etching time. 相似文献