Electrical disintegration and micro-focus X-ray CT observations of cement paste samples with dispersed mineral particles

Electrical disintegration is an effective liberation technique in mineral processing where the liberation ratio depends on the mineralogical properties of the mineral grains. However elucidation of the liberation behavior is difficult since the fragments after the electrical disintegration are fine and complex. This study applies electrical disintegration to cement paste samples with various dispersed mineral particles (calcite, quartz, albite, and pyrite) and the disintegrated products are observed with a micro-focus X-ray CT scanner. Current channels and crack extension behavior from the channels are identified by cross sectional CT and three dimensional reconstructed images. A classification of the crack patterns was carried out and compared with the results of liberation ratio measurements of the products.     

A framework for identifying differences and similarities in the managerial competencies associated with different modes of product life extension

It has been noted in the past that economically sound, environmentally preferable life extension modes such as remanufacturing and recycling have special characteristics that complicate the management of their production, logistics and associated operations. This paper considers these complicating characteristics from the perspective of the nine different modes of product life extension. In doing so, a framework and guide is provided to what issues, resource requirements and management capabilities are required for specific life extension modes. This framework provides guidance to practitioners and academics on commonalities between different product life extension modes, thereby assisting practitioners in leveraging current internal skills and capabilities and researchers in determining the generalizability of research.     

Acoustic emission characterization of steel in H2S solution subjected to tensile load

Abstract

This paper investigates the characteristics of acoustic emission (AE) signals generated from hydrogen induced cracking (HIC) and sulfide stress corrosion cracking (SSCC) for a medium strength steel in hydrogen sulfide (H₂S) solution. The experiments performed in this study include the constant load test (CLT) and the constant extension rate test (CERT).

From the results of the CLT, the AE count rate caused by SSCC was found to be much higher than that resulted from the HIC; and the increase of the AE count rate was observed to be approximately proportional to the increase of the applied loading. In addition, the AE frequency distribution diagrams obtained from these tests were found to contain potential information for distinguishing the mechanisms of HIC and SSCC. From the results of CERT, the AE signals detected from the specimens tested in the H₂S solution were compared with those obtained from the specimens tested in the air. In addition, the AE count rate detected from the tensile specimens was studied according to the different deformation stages of the specimens. From this study, the variation of the AE count rate in each deformation stage was described.     

Lifetime extension of in‐core self‐powered neutron detector using new emitter materials

In this paper, new in‐core self‐powered neutron detector emitter candidate materials, ie, vanadium, cobalt, and silver, have been examined in their lifetimes compared with the commonly used rhodium emitter. Using a new quantitative lifetime evaluation model, the lifetimes of vanadium and cobalt were determined to be longer than that of rhodium, but these materials were also shown to have the disadvantage of low signal intensities. Under normal operating conditions, we showed that rhodium emitter can be used for 2 cycles of pressurized water reactors (PWRs) with lifetime of 4.35 years, whereas silver can be used for 5 cycles of PWRs with lifetime of 8.04 years. Three sensitivity tests were performed for rhodium and silver about (1) the emitter size, (2) the fuel assembly burnup, and (3) the emitter temperature variations. From the test results, we observed that the lifetimes of rhodium and silver emitters remained 2 and 5 cycles long, respectively. We concluded that silver can significantly extend the in‐core detector's lifetime in PWR operation.     

A novel method to investigate tensile properties of woven fabrics in all-direction

In this research, we propose a new method and instrument to measure load-extension curve of the fabric samples under all-directional extension. Using this method, fabric sample is loaded under extension in the warp, weft, and all other directions in between. Using this new method, we introduced a comprehensive tensile modulus which is affected by the fabric structures and densities. For this purpose different structures i.e. plain, Twill 2/2, Twill 1/3, and Twill 1/7 were produced with different densities. Then these samples were tested under the new method. Our results are then compared to those one would obtain under uniaxial tests, by performing independent uniaxial tests. It is shown that under all-directional test lowering the weft density decreases the tensile comprehensive modulus. Furthermore, a reduction in the floating yarns in the fabric structure decreases the tensile comprehensive modulus. It was found that among the samples tested here, plain fabric and Twill 1/7, respectively, possess the maximum and minimum comprehensive modulus. A similar trend was also observed through independent uniaxial extension, in warp or weft direction, test.     

基于Pro/E的支撑架多工位级进模设计

在分析了支撑架零件的结构特点和冲压成形工艺的基础上,介绍了冲裁、多次弯曲、切断级进模的排样设计、模具总体结构设计和主要零部件设计,确定了级进模设计方案。并采用Pro/E软件及其外挂PDX实现了支撑架级进模的零件及组件的3D参数化设计,提高了设计效率,缩短了级进模开发周期。     

基于可拓理论的数控代码转换系统的研究

为了解决ISO6983标准的数控(NC)代码共享问题,研究了一种基于可拓理论的数控代码转换系统.系统的信息定制模块根据机床基本性质、程序格式、代码功能复合元模型,完成对应信息的存储;系统的核问题求解模块负责代码功能参数的转换、代码功能的分解和程序格式的转换;系统的源系统代码输入模块通过运动变换矩阵完成机床类型的选择、代码的输入和代码的词法语法分析;系统的中间文件生成模块根据STEP标准的生成中间文件;系统的目标系统代码生成模块对代码进行最优选择和转换.系统的性能取决于三个复合元和核问题解的的完备性.     

新型机械加长杆立柱的设计

为了更加科学地发挥液压支架中加长杆立柱的使用性能,通过对传统液压支架加长杆立柱的结构及受力优缺点进行分析研究,结合实际及其他领域设计经验,设计出一种新型的液压支架用机械加长杆立柱(已申请专利)。通过对2种结构的加长杆立柱进行结构及受力比较试验,试验结果表明该新型结构的机械加长杆立柱要优于传统结构加长杆立柱,有很好的应用前景。     

内蒙古大千博选矿厂改扩建实践

介绍了高压辊磨试验结果、干选试验结果和选矿厂生产现状,对破碎系统、磨选系统的流程及改扩建内容进行了详细论述.改扩建后达到了设计要求的规模.     

基于灰色物元分析的工程施工方案综合评价

针对施工方案综合评价中各指标的不相容性和信息不完全性,提出基于灰色物元分析的施工方案综合评价方法。该方法将待评价方案、评价指标及其特征值作为灰色物元,通过计算综合关联度得到最优的施工方案。用实例与模糊优化理论模型进行了对比,得到一致的结果。