Effect of vibration condition and inter-particle frictions on the packing of uniform spheres

We present a numerical study of the packing of uniform spheres under three-dimensional vibration using the discrete element method (DEM), focusing on the effects of vibration condition (amplitude and frequency) and inter-particle frictions (sliding and rolling frictions). The results are analysed in terms of packing density, coordination number (CN), radial distribution function (RDF) and pore structure. It is shown that increasing either the vibration amplitude or frequency causes packing density to increase initially to a maximum and then decrease. Both vibration frequency and amplitude should be considered to characterize the effect of vibration process on packing structure. The sliding and rolling frictions between particles can decrease packing density since they dissipate energy, although the effect of rolling friction is less significant. In line with the change of packing density, microstructural properties such as CN, RDF and pore distribution also change: a looser packing often corresponds to smaller CN, less peaked RDF and larger but more widely distributed pores.     

Lean philosophy: implementation in a forging company

This research addresses the implementation of lean philosophy in a forging company with a focus on radial forging production flow lines. Here, the prime motive is to evolve and test several strategies to eliminate waste on the shop floor. In this research, a systematic approach is suggested for the implementation of lean principles. This paper describes an application of value stream mapping (VSM). Consequently, the present and future states of value stream maps are constructed to improve the production process by identifying waste and its sources. Furthermore, Taguchi’s method of design of experiments is pursued here to minimize the forging defects produced due to imperfect operating conditions. A noticeable reduction in set-up time and work-in-process (WIP) inventory level is substantiated. Finally, we conclude with a discussion of managerial implications and the future scope of research.     

制冷系统的节能优化运行

本文通过对制冷系统耗电诸多因素的初步分析 ,采用正交试验、回归计算等手段 ,得出系统耗电与主要因素的函数关系 ,以便通过优化计算迅速找出最佳运行参数 ,指导操作 ,从而达到节能是目的。     

Computing distance transformations in convex and non-convex domains

It is shown that the well known two-pass sequential local transformation algorithm for computing a distance transformation in rectangular domains may fail in some convex integer domains, but that a four-pass algorithm is sufficient in all two-dimensional convex domains. For non-convex domains the number of passes necessary is shown to be generally greater. Two propagation algorithms for computing the distance transformation are described and shown theoretically and experimentally to be computationally more efficient than the sequential local transformation algorithm in non-convex domains of complex shape. The relationship of the distance transformation in non-convex domains to some more general transformations is explored.     

大把捆远程维护仪的研究

采用单片机开发大把捆远程维护仪，通过电话线，维护仪远程拨叫维护中心，远程采集机器运行状态，远程调整参数，使机器处于最佳状态运行；维修中心专家远程判断故障点，远程维护或远程指导维护，节省维护成本和人力资源。     

POLARIZATION BEHAVIOR OF PACKED-BED ELECTRODES: A COMPARATIVE STUDY OF EXPERIMENTAL AND MODELING RESULTS

The current distribution and overall polarization behavior of electrodeposition at a flow-through (packed bed or fluidized bed) electrode are modeled by means of a one-dimensional model involving a primary reacting species and a simultaneous side reaction. The model equations are solved by orthogonal collocation; the time and storage requirements compare favorably to those of finite-difference methods. Experimental data obtained using a packed-bed electrode are compared with the model predictions and various methods of fitting the data are compared.     

电火花铣削钛合金加工工艺研究

在全面试验的基础上，对电火花铣削钛合金进行了初步研究，给出了电火花铣削钛合金的影响因素及其指标的关系曲线。并对其进行了数据分析。试验表明，冲油电火花铣削是加工钛合金的有效方法。     

包装机中塑料薄膜常热式热封参数的实验研究

文中通过对包装机中常热式热封过程的分析及有效的实验，获得较为可靠的热封实验数据，并利用专业统计软件spss对实验数据进行处理，得到包装机中塑料薄膜的封口强度与操作参数之间的关系，为设计人员提供了一种获得最优操作参数的有效方法。     

Near-wall porosity characteristics of fixed beds packed with wood chips

Packed beds of fuel wood chips are commonly found in thermal conversion processes such as combustion or gasification. Wood chips in particular are mostly used as fuel for small-scale domestic heating boilers but also for commercial-scale combustion units. The characterization of spatial voidage distribution inside the wood chip beds is of great importance for flow and reactor modelling. This study focuses on the radial porosity variations of cylindrical beds of three different types of commercially available wood chips including chips classified as G30 size class. The conventional technique of consolidating packed beds with a resin was chosen as the experimental procedure. The radial voidage distribution in different cylindrical beds is determined by image analysis of sections of the solidified packings. Additionally, a packing of monosized spheres was investigated in order to assess the selected procedure in comparison with widely available literature data for spheres. The results are discussed and summarized in a mathematical expression correlating the radial voidage distribution depending on average wood chip size, packing core porosity and dimensionless distance from the tube wall.     

Chrestenson函数序列的生成方法及其数学分析

本文提出了适于三种序号的Ｃｈｒｅｓｔｅｎｓｏｎ函数序列的复制方法，对其复制过程进行了数学分析，并指出当Ｃｈｒｅｓｔｅｎｓｏｎ函数退化为Ｗａｌｓｈ函数时，此方法即为复制理论中的平移复制方法。