Assessment of spray quality from an external mix nozzle and its impact on SQL grinding performance

Spray quality is the critical factor which decides the efficacy of Small Quantity Lubrication (SQL) technology in a high specific energy involved machining process like grinding. Yet, the understanding about spray quality, the actual process mechanics and its effect on machining performance is inadequate. The present work is an attempt to establish a correlation between the spray input variables, quality of the spray and machining performance of SQL grinding through modelling and experiments. Using computational fluid dynamic techniques, the variation of droplet size, droplet velocity, number of droplets and heat transfer coefficient have been analysed at different input parameters and the computed trends have been verified and validated. CFD modelling of spray indicates that it is possible to produce aerosol medium with high heat dissipation ability at moderately high air pressure and low flow rate. It also shows that any increase in atomising air pressure favourably leads to notable increase in wetting area and also results in substantial enhancement in heat dissipation ability. Reduction of residual stress is thus remarkably good. On the other hand, grinding fluid flow rate, if increased, offers significantly better lubricity and reduces the grinding force which also reduces tensile residual stress. Short spell grinding test results are found to be in good agreement with CFD results.     

Nature of heterophase inclusions in high-purity optical fiber materials as studied with 3D laser ultramicroscopy

3D laser ultramicroscopy (3D LUM) is intended specially for determining the concentration and size distribution of submicron inclusions in the bulk samples of high-purity materials for visible and IR fiber optics. In this work the 3D LUM technique is shown to be able to identify the nature of individual inclusions detected. The measurement of the light scattered by an inclusion at a varied probe beam wavelength and polarization and at a varied scattered light collection angle makes it possible to determine the inclusion refractive index. The 3D LUM possibilities are illustrated by the example of studying the inclusion nature in the As₂S₃ glass samples prepared by the direct synthesis from elements in a quartz container at elevated temperatures.     

差分跳频通信系统的特点及性能

文章介绍了一种新型的短波跳频通信技术——差分跳频,分析了差分跳频技术区别于常规跳频技术的主要特点。针对按序列检测的信号接收方法,对差分跳频通信系统在AWGN信道下的性能进行了理论分析,同时做出相应的计算机仿真,证实了差分跳频通信技术和按序列检测方法的结合,使通信系统在AWGN信道下的性能得到了比较显著的提升。     

连续波雷达测距中的解模糊技术

研究连续波雷达测距中的距离模糊问题，分析几种常用解模糊方法的性能，并讨论参差比的选取对测距范围的影响。     

淤泥软基爆炸固结试验研究

对爆炸效应在淤泥软基工程中的应用问题进行了探讨，并首次提出了爆炸在淤泥软基中的分界应力特征以及排水固结及破坏分区的基本模式。为采用动力加速对淤泥软基工程的处理，提供了试验依据，具有实用价值和指导意义。     

Fe3O4/PSt/TiO2多层包覆电磁响应微球的制备

首先采用分散聚合法将自制的Fe3O4磁流体和苯乙烯反应合成有磁核的Fe3O4/PSt磁性聚合物微球，然后，用非均匀成核水解反应在Fe3O4/PSt微球外包覆无定形二氧化钛，获得Fe3O4/PSt/TiO2复合微粒。用红外光谱、扫描电镜和热分析对粒子的形貌和结构进行了表征。并测试了微粒的介电性能和磁性，结果表明，所制得复合微粒有良好的电、磁响应性。     

600 A IGBT开关电路及其散热系统设计

采用IGBT开关电路，对大功率电阻带进行直流脉宽调制控制，实现了内燃机车大功率直流发电机负载实验中的负载大小的连续调节。为了避免在实验过程中IGBT器件的温度过高，采用独特的双管IGBT结构和双向强迫风冷的散热系统。实验表明该电路运行稳定、可靠。     

威海市污水处理深海排放工程的设计

威海市污水处理深海排放工程是为改善其水域环境而建设的一英包括市区排水系统，污水预处理厂，输水管道和海洋放流管系统在内的完整而典型的工程，因此其工程设计扣的经验将会对同类项目的设计与工程建设有所借鉴。