双变径摆轮抽油机运动学计算的一种有效方法

双变径摆轮抽油机是一种摆轮采用变径技术的无游梁式抽油机。进行运动学计算时，由于大小两个摆轮采用变径技术，而且相位不同，悬点位移、速度、加速度与曲柄转角之间的关系很难用数学式直接表达出来。针对这一问题，给出了双变径摆轮抽油机运动学计算的一种简单有效的方法：假设柔性件的长度不变，利用数值计算的方法进行求解。第一步，求出小摆轮转角与曲柄转角之间的数值对应关系；第二步，求出悬点位移与大摆轮转角之间的数值对应关系。由于大小两摆轮为同一个构件，悬点位移与曲柄转角之间的数值对应关系可由以上两步联立求出，进而利用差分法可求出悬点速度和加速度与曲柄转角的关系。     

环氧乙烷水合反应器的简易设计方法

介绍一种在特定条件下的简便的环氧乙烷水合反应器设计方法。     

高水头平板闸门水力特性研究

结合三峡水电站排沙底孔工作平板闸门进行了高水头闸门水力特性试验研究 .内容包括在开启过程中 ,闸门底缘后漩涡水流剪切空化引起的闸门空蚀、振动及通气减蚀措施 ;闸门总体布置及最佳体型 ;闸门位置及底缘合理形式 ;加折流器及闸室区水流脉动特性 .提出了防止闸门空蚀及振动的具体措施 ,为高水头闸门结构设计提供科学依据     

RETRIEVING RIVER ATTRIBUTES FROM REMOTELY SENSED DATA: AN EXPERIMENTAL EVALUATION BASED ON FIELD SPECTROSCOPY AT THE OUTDOOR STREAM LAB

This paper summarizes experiments conducted at the Outdoor Stream Lab to gain insight on the relationships between a channel's spectral characteristics and the river attributes of interest to scientists and managers. Improved understanding of these connections would advance the application of remote sensing to fluvial systems. Motivated by this objective, we examined the following: (i) interactions among local hydraulics, water surface roughness and surface reflectance; and (ii) the influence of periphyton development and streambed disturbance on bottom reflectance. These experiments could thus lead to novel methods for inferring flow velocity and substrate type, respectively, from passive optical image data. Our initial results indicate the following: (i) water surface reflectance can compromise spectrally based depth retrieval by reducing the range of useful wavelengths and weakening correlations between band ratios and depth, implying that removing the surface‐reflected component of the total radiance could facilitate bathymetric mapping; (ii) water surface roughness was influenced by local hydraulics and was positively correlated with water surface reflectance, suggesting that observations of surface reflectance could be used to infer flow velocities; (iii) substrate spectral characteristics were influenced by the degree of periphyton development, implying that algal biomass might be estimated from remotely sensed data; and (iv) similarly, bottom reflectance differed significantly for intact versus disturbed substrates, suggesting that areas of streambed disturbance might be identified via remote sensing. Future work will focus on further elucidating connections between surface reflectance, water surface texture and flow velocity, and developing quantitative relationships between bottom reflectance, periphyton abundance and the degree of streambed disturbance. Copyright © 2013 John Wiley & Sons, Ltd.     

Ultrasonic velocity measurements for characterizing the annealing behaviour of cold worked austenitic stainless steel

Precise measurements of shear wave velocities have been made in 20% cold worked and annealed samples of alloy D9 (Ti-modified austenitic stainless steel) to characterize the microstructural changes during annealing. The variation in wave velocity with annealing time exhibited a three stage behaviour. In the first stage, a slight increase in the velocity during recovery regime has been observed. This is followed by a significant increase in the velocity in the recrystallization regime (second stage) and reaching saturation on completion of recrystallization (third stage). Microstructural observations using optical metallography confirmed these three stages. The maximum variation in velocity is observed only when the polarization or the propagation direction of the shear wave is alingned with the cold working direction. Variation in shear wave velocity during annealing process, in general, is just opposite to that of the variation in longitudinal wave velocity. A number of velocity measurements were made by changing the propagation and polarization directions of the shear waves with respect to the cold working direction. Based on these measurements, a suitable velocity ratio parameter is suggested for determining the degree of recrystallization during annealing of cold worked alloy D9.     

颗粒被凝固前沿排斥的临界速度模型

通过对颗粒增强金属基复合材料凝固过程中温度场，、质量分数场变化以及凝固前沿形状改变的数值模拟，建立了颗粒被凝固前沿排斥或捕获的临界速度模型，当凝固前沿的推进速度小于颗粒被凝固前沿所排斥／捕获的临界速度时，颗粒被凝固前沿所捕获的现象不会发生，并且在临界速度模型中保持其它参数为旧，而只考虑合金质量分数的影响时，发现随着合金质量分数的逐渐增加，颗粒被凝固前所排斥／捕获的临界速度逐渐减小。     

按行程速比系数设计平面曲柄滑块机构的解析法

利用平面曲柄滑块机构中各有关点的坐标之间的关系，提出了一种按行程速比系数设计平面曲柄滑块机构的解析法。与现有解析法相比，该方法解题原理简单明了，计算简便，易于被工程设计人员所接受，具有较好的实用价值。     

常用风冷式热泵机组和冷水机组的噪声测量和分析

介绍了对上海近年来公共建筑空调工程中常用的１０余种品牌的风冷式热泵机组、风冷式冷水机组噪声的测定结果及其分析，并将其与各品牌的有关技术数据作了对比，提出了设计选用时应注意的事项。     

时间相关计程仪测速精度的仿真研究

基于回波信号的波形不变性原理，利用维纳一辛钦定理推导出了回波信号的相关函数在峰值的61％处的宽度与船速成简单的反比关系。仿真结果证明：船速越高，相关峰越尖锐，测速误差越小。     

风洞边壁对挟沙气流流速分布的影响

鉴于现有挟沙气流流速分布研究中对风洞边壁影响的认识不足，本文通过改变风洞宽度的方法对风洞边壁的影响进行了探索性实验研究。在五种宽高比条件下，对风洞断面挟沙气流流速分布进行了测量。发现风洞边壁对挟沙气流流速分布有较为明显的影响。在风洞宽度比相同的条件下，断面内中垂线上的有效粗糙度系数大于其它垂线上对应的系数。从靠近边壁的垂线到断面中垂线，各垂线对应的跃移层内区及外区流速分布的上界高度、气流摩阻速度均逐渐增大。随着风洞宽高比的减小，断面内中垂直线上的气流摩阻速度与自由流速的比值以及受风洞边壁影响的气流厚度均增大。