制动时间对起重机制动器温升的影响研究

根据起重机盘式制动器的工作特点以及制动盘与摩擦片的实际几何尺寸,运用ABAQUS软件建立了三维摩擦生热有限元模型。有限元模拟过程中通过设定不同的制动时间,获得了不同的摩擦片温度场分布情况,并根据仿真结果,提出了控制制动器温升的对策。     

空压机ZR750低压机头LP转子驱动齿轮断裂分析

通过对空压机ZR750低压机头LP转子驱动齿轮断裂部位进行理化检测和分析,推断其失效原因为在机器发生故障后仍反复强行运转,致使承受很大的冲击和弯曲应力,导致在应力集中的齿轮齿根部位产生了断裂。     

镀锌层三价铬钝化工艺

概述了镀锌层三价铬钝化膜形成机理及特性,及国内外三价铬钝化工艺应用情况,三价铬钝化液的使用寿命长,镀液成分较稳定,并可得到不同色泽的钝化膜,采用封闭剂处理显著提高了膜层耐蚀性;三价铬钝化能减少对环境的污染,是我国电镀清洁生产推荐的工艺,具有实用参考价值。     

基于深度学习的目标检测技术综述

目标检测是计算机视觉领域中的研究热点.近年来,目标检测的深度学习算法有突飞猛进的发展.基于深度学习的目标检测算法大致可分为基于候选区域和基于回归两大类.基于候选区域的目标检测算法精度高,但是结构复杂,检测速度较慢.而基于回归的目标检测算法结构简单、检测速度快,在实时目标检测领域有较高的应用价值,然而检测精度相对略低.本文总结了基于深度学习的目标检测主流算法,并分析了相关算法的优缺点和应用场景.最后根据深度学习的目标检测算法中存在的困难和挑战,对未来的发展趋势做了思考和展望.     

A parameter for quantitative analysis of plasticity induced crack closure

Numerical models have been successfully developed to predict plasticity induced crack closure (PICC). However, despite the large research effort a full understanding of the links between physical parameters, residual plastic wake and PICC has not been achieved yet. The plastic extension of material behind crack tip, Δy_p, obtained by the integration of vertical plastic deformation perpendicularly to crack flank, is proposed here to quantify the residual plastic field. The values of Δy_p and PICC were obtained numerically in a M(T) specimen using the finite element method. An excellent correlation was found between PICC and Δy_p which indicates that this parameter controls the phenomenon, and can be used to quantify the effect of physical parameters. An empirical model was developed to predict PICC assuming that the residual plastic field is a set of vertical plastic wedges, that the linear superposition principle applies and that the influence of a particular wedge exponentially decreases with distance to crack tip. The model was applied successfully to predict PICC for different residual plastic fields which provided an additional validation of Δy_p as the parameter controlling PICC.     

Physical properties of Sn58Bi–xNi lead-free solder and its interfacial reaction with copper substrate

The aims of this research are to investigate the effects of Ni on the physical properties of Sn58Bi–xNi lead-free solder, and to examine its interfacial reaction with the copper substrate. In the experiments, four concentrations of Ni (i.e. 0.05, 0.1, 0.5 and 1.0 wt.%) were individually added into Sn58Bi and their respective microstructure, tensile strength, elongation, melting temperature, wettability and electrical resistivity of Sn58Bi–xNi were subsequently measured. The results indicated that Ni refined the microstructure of the solder matrix and induced the formation of Ni₃Sn₄ intermetallic phase, and that the size and volume fraction of Ni₃Sn₄ were positively correlated to the Ni content. The optimal concentration of Ni to enhance the tensile strength of the alloy was 0.1 wt.%, but the elongation of the alloy was inversely correlated to the Ni content. The addition of Ni contributed positively to the melting temperature and wetting behavior of the alloy, whereas no significant change in the electrical resistivity of Sn58Bi–xNi was detected. In addition, Ni increased the thickness of the intermetallic layer at the interface, and only monoclinic η′-Cu₆Sn₅ phase was present at the intermetallic layer. Nevertheless, the intermetallic phase of this research was dissimilar from the findings of existing literature.     

Yigo管理软件CAD的探索及应用

在激烈的管理软件市场竞争中，管理软件产品的与时俱进以及客户服务质量已成为管理软件厂商的生命线。因此，进一步实现管理软件按时成功交付，缩短实施周期，降低开发成本，提升经济效益是处于全球竞争之中管理软件厂商的战略目标，而现有的基于Yigo无码开发技术的图表化的管理软件CAD已将客户自主设计、自主维护、自主扩展的自主信息化管理提供了可能。     

基于GPIB和VB的自动测试系统设计

文章首先介绍基于GPIB技术和VB所设计的自动测试系统,然后介绍GPIB技术的特点和工作原理,最后介绍自动测试系统的软硬件组成,并给出了系统的控制程序流程图。     

片式电容及其应用（2）

片式电容由于有许多突出的优点,例如在比较小的体积里面可以获得比较高的电容量,以及非常好的高频特性等,成为最有用的电子元件之一。在这篇文章里,我们要分两期来讨论片式电容的结构,分类以及应用,这里是文章的第二部分。     

Characterization and acid-induced gelation of butter oil emulsions produced from heated whey protein dispersions

Whey protein isolate was dispersed at 4% or 8% (w/v) and heated at neutral pH to produce protein polymers. Butter oil, up to 20%, was homogenized in heated whey protein dispersions at pressure ranging from 10 to 120 MPa. Emulsion gelation was induced by acidification with glucono-δ-lactone. Whey protein polymers produced finely dispersed emulsions with fat droplet diameter ranging from 340 to 900 nm. Homogenization pressure was the main factor influencing droplet size. At low fat volume fraction, the emulsions exhibited Newtonian behaviour. As fat content increased, shear thinning behaviour developed as a result of depletion flocculation. Emulsion consistency index increased with protein and fat concentrations. Increasing homogenization pressure had no effect on Newtonian emulsions but promoted flocculation and significantly increased the consistency of high fat emulsions. Protein concentration was the main factor explaining emulsion gel hardness and syneresis. Syneresis decreased with increasing fat content in the gel.