表面活性剂对碳钢的缓蚀作用及与缓蚀剂的协同效应

采用动电势扫描法测定了碳钢在饱和（NH4）2CO3溶液中的阳极极化曲线，研究了几种表面活性剂与缓蚀剂复配后的协同缓蚀作用。结果表明：几种表面活性剂均具有较好的缓蚀性能，体系中添加0．1％的量，缓蚀效率都接近90％：当0．05％壬基酚聚氧乙烯醚（TX－10）与0．05％四丁基碘化铵复配时，协同缓蚀效率可达93．3％；应用动电势扫描法能够快速、简便地测定腐蚀速率和评选缓蚀剂。     

"教育评估中介机构"概念质疑

本文从语词含义和造词宗旨入手,剖析了中介机构与评估机构、中间机构、缓冲组织的区别,以论证“教育评估中介机构”概念不当而应予废弃。     

Influence of process parameters on the deposition footprint in plasma-spray coating

This paper presents an investigation of the influence of plasma spray process conditions on the in-flight particle behavior and their cumulative deposition to form a coating on the substrate. Three-dimensional computational fluid dynamics (CFD) analyses were performed to model the in-flight particle behavior in the plasma-spray process and their deposition on the substrate. The plasma spray was modeled as a jet issuing from the torch nozzle through the electrical heating of the arc gas. In the model, particles were injected into the plasma jet where they acquired heat and momentum from the plasma, some got melted and droplets were formed. By means of a droplet splatting model, the particle in-flight data generated by the CFD analyses were further processed to build up an imaginary three-dimensional deposition profile on a flat stationary substrate. It is found that the powder carrier gas flow rate influences the particle distribution on the substrate by imparting an injection momentum to the particles that were directed radially into the plasma jet in a direction perpendicular to the plasma jet. The larger sized particles will acquire higher injection momentum compared with the smaller sized particles. This causes particle distribution at the substrate surface that is elliptical in shape with the major axis of ellipse parallel to the particle injection port axis as illustrated in Fig. 1. Larger particles tend to congregate at the lower part of the ellipse, due to their greater momentum. The distribution of particle size, temperature, velocity, and count distribution at the substrate was analyzed. Further, based on the size and the computed particle temperature, velocity histories, and the impact sites on the substrate, the data were processed to build up a deposition profile with the Pasandideh-Fard model. The shapes of deposition profiles were found to be strongly driven by the segregation effect.     

基于BP神经网络的清扫机器人的环境建模

针对未知环境清扫机器人的环境识别和建模,提出了一种基于BP神经网络的环境建模算法.首先提出了一种利于计算机识别和处理的室内环境拓扑结构,再利用3个超声波传感器获得周围物体的距离信息,对这些距离数据进行归一化处理之后利用BP神经网络来识别出物体的形状,完成环境的建模.给出了系统的组成结构、室内环境拓扑结构、BP神经网络原理及学习步骤.并对实验获得的一组数据进行了仿真,结果表明这种算法对于环境识别和建模是一种有效的方法.     

Simplified and efficient calibration of a mechanistic cutting force model for ball-end milling

Accurate evaluation of the empirical coefficients of a mechanistic cutting force model is critical to the reliability of the predicted cutting forces. This paper presents a simplified and efficient method to determine the cutting force coefficients of a ball-end milling model. The unique feature of this new method is that only a single half-slot cut is to be performed to calibrate the empirical force coefficients that are valid over a wide range of cutting conditions. The instantaneous cutting forces are used with the established helical cutting edge profile on the ball-end mill. The half-slot calibration cut enables successive determination of the lumped discrete values of the varying cutting mechanics parameters along the cutter axis whereas the size effect parameters are determined from the known variation of undeformed chip thickness with cutter rotation. The effectiveness of the present method in determining the cutting force coefficients has been demonstrated experimentally with a series of verification test cuts.     

虚拟装配技术及应用

虚拟制造是一种新兴的先进制造概念和理论，虚拟装配是虚拟制造研究领域重要的研究分支。虚拟装配可帮助产品摆脱对于试制物理样机并装配物理样机的过度依赖，可以有效地提高产品装配建模的质量与速度，有助于降低产品开发成本，缩短产品开发周期。介绍了虚拟装配的国内外现状，分析了虚拟装配的特征和关键，探讨了虚拟装配的实施方案和步骤。     

国内外不锈钢精炼剂研究发展现状

分析了精炼剂组元元素的作用能力，讨论并总结了精炼剂组元的复合作用，介绍了几种国内、国外精炼剂产品，提出发展高效复合精炼剂的想法。     

Casting/mold thermal contact heat transfer during solidification of Al-Cu-Si alloy (LM 21) plates in thick and thin molds

Heat flow at the casting/mold interface was assessed and studied during solidification of Al-Cu-Si (LM 21) alloy in preheated cast iron molds of two different thicknesses, coated with graphite and alumina based dressings. The casting and the mold were instrumented with thermocouples connected to a computer controlled temperature data acquisition system. The thermal history at nodal locations in the mold and casting obtained during experimentation was used to estimate the heat flux by solving the one-dimensional inverse heat conduction problem. The cooling rate and solidification time were measured using the computer-aided cooling curve analysis data. The estimated heat flux transients showed a peak due to the formation of a stable solid shell, which has a higher thermal conductivity compared with the liquid metal in contact with the mold wall prior to the occurrence of the peak. The high values of heat flux transients obtained with thin molds were attributed to mold distortion due to thermal stresses. For thin molds, assumption of Newtonian heating yielded reliable interfacial heat transfer coefficients as compared with one-dimensional inverse modeling. The time of occurrence of peak heat flux increased with a decrease in the mold wall thickness and increase in the casting thickness.     

基于参数化特征建模的汽车转向器CAD系统的研制

通过对汽车转向器结构特点进行分析，得出了汽车转向器CAD策略，利用UG软件平台并结合UG／OpenGRIP语言来创建参数直接驱动的转向器三维参数化CAD建模程序，开发了一种基于参数化特征建模的汽车转向器CAD系统。经实际应用表明，该系统设计效率高，实用性强，大大缩短了产品开发周期。     

有机膦系预膜剂在碳钢表面的成膜机理

用旋转挂片法、极化曲线法、X射线光电子能谱法、原子力显微镜法等分析测试手段对以有机膦酸和Zn盐为主要成分的预膜剂在碳钢表面形成的缓蚀保护膜进行了综合表征.结果表明,有机膦酸和Zn盐成膜剂能够在碳钢表面形成致密的保护膜,对腐蚀的阴极和阳极过程都具有抑制作用;膜结构为磷酸盐螯合物颗粒的致密沉积,主要成分(mol%)为55%O、16?、14%P、5%Zn、7%C和2?.