换热器传热特性的试验方法研究

本文提出了一种新的研究换热器传热特性的试验方法.按着传热的基本原理,应用最优化方法,得出可以同时准确的确定换热面两侧冷、热流体的对流换热规律.这种方法进一步发展和改进了 Wilson 方法.它可以进行多个末知参数的计算,有较高的计算精度.文中依据理论分析和应用实例测试,验证了该方法的数学可行性.     

Raman studies of semiconducting oxide nanobelts

Crystalline nanobelts of ZnO and SnO2 were prepared from a thermal evaporation of oxide powders inside an alumina tube in the absence of catalysts. Typical dimensions of the nanobelt samples ranged from approximately 10 to 100 microns in length, 30 to 300 nm in width, and 6 to 30 nm in thickness. Room temperature Raman spectra were obtained on pressed mats of nanobelt samples and compared with the corresponding spectra of the starting oxide powders and bulk materials. Collectively, our Raman data indicated that the as-prepared nanobelt samples used in this study were oxygen deficient. Upon annealing at 900 degrees C in flowing oxygen for 1 h, the nanobelt samples exhibited Raman features that corresponded to those expected in respective bulk semiconducting oxides. The dimensions of the nanobelts were a bit too large to expect significant quantum size effects on the phonon structure similar to those observed in carbon nanotubes and short-period semiconductor superlattices.     

全球宽带接入市场发展趋势

从用户数持续快速增长、宽带用户数最多的国家和地区、宽带用户增量、宽带用户增长率以及宽带业务普及率等5个方面阐明了全球宽带接入市场的总体情况。分析指出宽带接入技术发展趋势．DSL在近两年内仍将占据主流地位。介招了宽带增值业务发展情况。     

选频放大器的特殊应用与多频率峰值现象的分析

本文分析了一种特殊应用的选频放大器,分析它的多频率峰值、幅值干扰、谐波干扰等电子学现象。向读者提供一个有实用价值的设计方案和一组参考数据。     

安钢3#高炉大喷煤量探索

安钢3^#高炉采用全烟煤喷吹。提高煤粉燃烧率、维持适宜的理论燃烧温度、保证煤气流的合理分布是提高喷煤比的关键。本文介绍安钢就如何提高3^#高炉喷煤量及大喷煤量下的高炉操作进行探索并取得了良好技术指标（煤比提高24kg／t，焦比降低了43kg／t）的生产实践。     

Application of K008 camera in diagnostics of shock and detonation waves

Results of tests of the K008 camera to determine its resistance to the action of factors that accompany gaseodynamic experiments, such as powerful electromagnetic, acoustic, and optical interference, and its application as a component of laser Doppler velocity meters of objects thrown by an explosion are presented. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 46–49, May, 2007.     

Analysis of Heat Transference in Regenerative Exchanger of a Thermal Power Plant

The process of electricity generation in a power plant involves several phases for heat exchange generally between hot fluid (water, fumes of steam) and one of the input fluids (cool water, cook oven gas, fuel, blast furnace gas, etc) The process of exchange evolves in time at the same time as installation itself. This improvement is another step in a deep study of the time-changing conditions of the heat transmission due to ageing, but it will also make possible the introduction of new parameters in the physical formulation whose relation is unknown. Modelling is done using feedforward neural networks after a very extensive pre-processing step.