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Research and development on crystal growth technologies for production of crystalline silicon ribbon have been under way now for three decades. I review here their progress toward establishment of manufacturing capabilities for silicon wafers for photovoltaic applications. I examine technology improvements which are currently being explored for a future generation of low cost solar products based on ribbon wafers, and discuss potential limits of the technology. 相似文献
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介绍了单端正向变换器基本电路,重点叙述带三路调节DC电压的100KHZ180W离线电源。它采用具有低导电阻RDS和低栅极电荷Qg的新型场效应管(QFET)作为变换电路的主开关器件,降低了电源开关损耗并提高了效率3%-5%。 相似文献
76.
In the oxidation of TiAl alloys, the role of scale-growth stresses formed during oxidation has, thus far, been unknown. In the present paper the oxide-growth stresses were investigated by the deflection-test method in monofacial oxidation (DTMO) accompanied by acoustic-emission measurements. On unmodified surfaces the growth stresses are compressive and reach levels of around –100 MPa. At the same time, significant acoustic emission occurs indicating that even under isothermal conditions, stresses are relieved by a scale-cracking mechanism. For oxide scales on TiAl surfaces, which had been ion implanted with chlorine before oxidation, a very thin protective alumina layer is formed which, however, develops growth stresses in the range of several GPa, accompanied by intensive acoustic emission. In all stress–time curves, a dynamic situation is observed. This consists of phases of stress relief by scale microcracking and phases of stresses increase due to crack healing and further oxide growth. As a result, the level of stress as a function of oxidation time, is characterized by an oscillating course. 相似文献
77.
On the basis of the experimental data, we show that the difference between the macroscopic and microscopic fatigue crack growth rates in the second section of the kinetic diagram of fatigue fracture is caused by the effect of crack closure within the limits of its existence. We establish the relationships between the macroscopic and microscopic fatigue crack growth rates and the structure of the material in the second section of the diagram for various values of the load ratio with regard for the effect of crack closure and propose a procedure of examination of the fracture processes in structural materials based on the analysis of microscopic and macroscopic fatigue crack growth rates. 相似文献
78.
位于蒙古国中部的尼尔金盆地是一个中生代裂谷盆地,目前仍处于勘探早期。盆地内下白垩统湖相泥岩和纸状页岩具有很强的生油能力,下白垩统的煤系地层及上二叠统-下侏罗统中富含有机质的泥岩和煤层是可能的气源岩;盆地内广泛分布着3套储集层;上侏罗统、下白垩统、上白垩统的泥岩是潜在的盖层;存在多种生储盖组合及远景圈闭类型。通过对石油地质条件的分析,认为尼尔金盆地很可能形成多套含油气层系和多种油气藏类型,推测在盆地中部和南部会有大的油气藏存在。 相似文献
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The effect of ductile crack growth on the near tip stress field in two different specimen geometries has been investigated. For homogeneous specimens it is observed that the peak stress level increases with ductile crack growth. The effect is most pronounced up to about 1 mm of crack growth. For low and intermediate hardening there is a significant effect of specimen size on the stress level. In case of mismatch in yield stress, the simulations show that the increase in stress level in the material with the lower yield stress is of a similar magnitude as is the case for stationary cracks. In case of ductile crack growth deviation from the original crack plane occurs, the highest stresses are still found close to the interface, and not in front of the current crack tip. 相似文献