谈谈分析天平制动部分的调修

分析天平的调修难度较大的是机械传动部分故障的调修。在大修前，通常先按下列顺序对天平进行预检：外观检查及清洁工作（了解一般零部件缺损情况）、横梁和刀刃的检查（了解要害部件的磨损情况）和机械传动部分工作情况检查（计量性能预检）。通过预检，可大致确定天平失灵的原因及故障所在，然后再逐步进行调修。以下主要只谈谈制动系统中支柱螺丝和吊耳的调修。     

Protel 99 SE使用中的常见问题分析与探讨

指出了使用Protel 99 SE软件时常遇到的几个问题,分析了产生这些问题的原因,并提出了相应的解决方法。     

天平与砝码计量标准考核中需注意的几个问题

笔者多年在天平与砝码计量标准考核工作中,经常遇到对考核规范理解有误造成计量标准延误考核,现列举几种常见现象并提出解决办法,供建标单位参考。     

电光分析天平的正确使用与维护

本文主要叙述电光分析天平的安装、使用与维护.     

变频器在井下使用的干扰问题及其解决方法

根据变频器在煤矿使用过程中对电网的干扰较大,甚至干扰煤矿井下安全生产监测监控系统等问题,对变频器的干扰种类、途径、干扰原因及其解决方法进行了研究。     

使用机械天平应注意的问题

本文主要介绍了机械天平使用前、使用中和使用后一些应注意的事项,以利于同行和使用者借鉴。     

L波段雷达探测系统的使用方法和常见问题处理

L波段高空气象探测系统是我国自主研制的新一代高空探测系统。它具有自动化程度高、精度高、时效快、界面新颖、使用方便等特点。为了保障该系统的正常运行,笔者对其在长春市气象探测中心已正式运行1年的情况进行了总结归纳,摸索出了一套适合本省环境和特点的操作方法。本文介绍了该系统的正确使用方法和常见问题处理,供广大业务、科研、管理人员借鉴。     

分析实验中常用天平和称量方法的选择

解读了分析实验中常用天平的重要参数的含义,比较了超微量、微量、半微量、常量、精密和粗天平6类天平的测量级别、最大载荷、分刻度值\\误差、称量特点、适用范围,举例说明了指定量称量法、减量称量法、差减称量法和增量称量法,列举了常用的称量容器及其适用对象,为分析实验操作和教学过程中正确选择天平类型以及合适的称量方法提供了参考。     

机械天平的使用、保养与修理

机械天平是测量质量的重要仪器之一,在日常生活当中应用十分广泛。为了满足称重要求就必须要保证机械天平的计量性能,我们除了能够正确使用天平以外,还必须高度重视机械天平的维护保养,以及准确的修理。     

棒线材飞剪机设计及使用的若干问题

从棒线材生产线的重要设备之一飞剪机的设计入手,总结了该飞剪机的种类、作用及选型等,对其结构设计及使用过程中出现的典型问题,作了详细分析,并提出了解决的方法。     

Early castability evaluation using analytical hierarchy process

Design for manufacture usually implies applying various guidelines derived from previous experience to improve part design so it is more compatible with the capabilities of the selected process, resulting in better quality and lower cost. The guidelines can be formulated as dimensionless criteria, enabling quantitative evaluation of a particular aspect of part design. There is, however, no good way to compare two or more designs for all aspects, considering that they may not be equally important. In this work, we employ analytical hierarchy process to determine the relative weights of various criteria for castability evaluation. The criteria are categorised in a three-level hierarchy, with the middle level comprising mould, feeding and gating groups. The prioritisation of criteria along with consistency checking of pair-wise comparisons enables a systematic evaluation of alternative product designs for manufacturability. The methodology is illustrated by modifying the product and tooling design of a grey iron bracket casting and estimating the improvement in manufacturability. The results are supported by experiments.     

基于SVM的微生物发酵过程软测量建模研究

微生物发酵过程中支持向量机(SVM)软测量模型的预测精度主要取决于SVM参数和输入变量优化选择.提出了一种新的SVM参数选择与输入变量选取方法,将SVM参数的选择和输入变量的选取看作组合优化问题,构造了基于赤池信息准则(AIC)的组合优化目标函数.为提高优化效率,采用遗传模拟退火算法(GSAA)来搜索最优的目标函数值.通过与网格算法、遗传算法等方法对比仿真研究表明,所提SVM微生物发酵过程软测量建模方法在微生物发酵过程的软测量建模中具有优良的性能.     

影响分析天平准确度的分析

文章分析了影响分析天平准确度的因素，并提出怎么样提高分析天平的准确度。     

Framework to evaluate manufacturing capability using analytical hierarchy process

Manufacturing capability of a firm is given by the level of output generated by the production system employed which in turn decides the competitiveness in the market. The pattern of structural and infrastructural decisions in the manufacturing affects the capability of the production system. Therefore, it is crucial to know the overall manufacturing capability of a firm and the contribution of each decision in it. This paper presents quantification of manufacturing capability based on multi-criteria approach. A total of 33 decisions (criteria) and their corresponding choices have been identified from the literature analysis to quantify the manufacturing capability. These decisions are then classified into six decision areas (group criteria), and the manufacturing capability evaluation problem is modeled by using analytical hierarchy process (AHP) framework. The approach facilitates computation of manufacturing capability index by evaluating the decisions taken in the manufacturing, which is then mapped into four levels, namely, infant, industry average, adult, and world class as proposed by the Miltenburg. The methodology is illustrated with a numerical example for a job shop manufacturing system.     

An analytical solution of the ECAE process of bi-layer strip using a Bezier type streamline

Co-extrusion of strips of different strength and ductility is a process in the production of bimetal rods of desirable physical and mechanical properties. Equal channel angular extrusion (ECAE) is an innovative process for applying severe plastic deformation to materials. The present study is concerned with the ECAE of different bi-layer strips. Developing a kinematically admissible velocity field using a Bezier-type streamline is the aim of present research. In this analysis, using the mentioned velocity field and the upper bound theorem, the extrusion force as well as the strain distribution in the deformation zone of the ECAE process are predicted. The solution takes into account the die profile, friction conditions, strength, arrangement and thickness ratio of the layer materials. Experimental results of ECAE of aluminum/copper and aluminum/mild steel bi-layer strips showed a good agreement with the predicted results.

     

电子分析天平模糊自适应PID平衡调节方法研究

为实现电子分析天平的快速准确称量,提出基于增量式模糊调节和PID调节有机融合的电子天平模糊自适应PID平衡调节方法。在建立电磁力平衡传感器系统传递函数基础上,确定基于FOLPD模型及Z-N整定法的初始PID调节参数,结合电磁力平衡传感器的动态响应特性,设定电子分析天平的模糊调节规则,并通过阈值判断,在系统偏差较大时采用增量式模糊调节,偏差较小时采用PID调节,实现两种调节方法的优势互补,缩短系统调节时间,提高系统的鲁棒性。仿真及测试结果表明,量程220 g、感量0.1 mg的电子分析天平应用模糊自适应PID调节方法,各载荷点示值误差≤±0.3 mg,稳定时间≤3 s,优于国家标准《JJG1036—2008电子天平检定规程》规定的I级天平示值误差指标。     

基于汽车故障诊断机理的故障诊断流程设计

通过对汽车故障诊断机理的分析,根据汽车实际故障现象,综合运用假设推理和故障树分析法,设计故障诊断流程,依据设计的故障诊断流程测试排除故障。研究表明:符合汽车故障诊断逻辑的故障诊断流程,可迅速准确地判断汽车故障产生的原因与故障点,同时为汽车故障诊断的思路提供了参考。     

电子分析天平的非线性影响与补偿方法研究

基于电磁力平衡传感器的电子分析天平非线性影响复杂,现有天平的非线性补偿主要依靠硬件电路实现,调试烦琐,示值误差大,一致性差.分析了电磁力平衡传感器的动圈位置、工作电流、环境温度、永磁体性能等非线性影响机理,提出了电磁力平衡传感器机械平衡优化与空间限位、取样电阻与传感器匹配、传感器多点温度测量等硬件优化方法,建立了电子分析天平非线性影响的牛顿插值补偿算法,实现了电子分析天平的非线性自动补偿.检验结果表明,采用研究的补偿方法对量程210g、分辨力0.1 mg的电子分析天平补偿后,全量程示值误差≤±0.3 mg,优于国家标准《JJG 1036-2008电子天平检定规程》规定的一级天平示值误差指标.