变导程螺杆挤压脱水机的运动分析和整体设计的研究

变导程螺杆是变导程螺杆挤压脱水机的核心部分,它的设计的好坏直接影响着变导程螺杆挤压脱水机的工作效果和效率。而用于牛粪固液分离的变导程挤压脱水机的螺杆除了在以上的一些要求以外,还要求螺杆能够承受较低的温度以及较大的温度变化。     

挤压脱水机螺杆轴断裂故障分析与改进

文章针对挤压脱水机螺杆主轴多次发生断裂故障,通过分析该轴受力情况,校核轴的疲劳强度,得出该轴是由于强度不够造成疲劳断裂的结论,并制定出具体改造的措施。     

沉降过滤式离心脱水机的操作与维护

沉降式离心脱水机是运用离心力使煤水混合物进行固液分离，它分为沉降式离心脱水机和沉降过滤式离心脱水机，我国选煤厂中应用较多的是沉降过滤式离心脱水机。本文以WLG1100×2600为例，分析沉降过滤式离心脱水机的结构、操作、维护等技术问题。     

含油污泥真空带式压榨脱水机理论及结构研究

本文首先介绍了含油污泥的来源,在此基础之上提出了真空带式压榨脱水机的过滤机理以及过滤分离原理,然后对真空带式压榨脱水机总体结构进行了分析,介绍了真空带式脱水机的工作原理和结构形式的选择,最后简要阐述了真空带式压榨脱水机的跑偏问题,提出跑偏的解决措施和直接原因分析。     

基于盲源分离理论的电能质量闪变的仿真研究

本文研究了利用单只电压互感器输出的信号序列构造延迟矩阵,以代替多个传感器输出信号阵列,满足盲源分离的要求并进行了盲源分离,对闪变的时域和频域进行分析,验证盲源分离理论的准确性和优越性,实现了从含有多个频率分量的闪变信号中分离出闪变包络及各谐波、间谐波频率分量的波形。     

基于PLC的先导式减压阀水压控制系统设计与研制

先导式减压阀是一种通过机械方式在水压小范围波动内自动稳定出水管道的水压阀，它的水压依靠其导阀来标定，传统的标定方法是通过人工岛现场对导阀的调节螺杆调整来实现的；现将减速电动机安装在导阀螺杆上，采用可编程控制器（PLC）控制远程控制减速电机旋转调节导阀螺杆，以标定阀门的出水压力。该方案为先导式减压阀远程调压控制提供了新的解决方案，并在实际应用中取得了很好的控制效果。     

浅谈煤泥离心脱水机在太西洗煤厂的应用

本文对LLL1200×650B型煤泥离心脱水机投用前后产品指标进行对比分析,介绍了该型号煤泥离心脱水机的使用效果,降低了生产成本,保证产品的水分合格,提高我厂的经济效益。     

螺杆制冷压缩机耗油量大的原因及改进措施

本文通过对螺杆式制冷压缩机油分滤芯的分离机理进行分析,找出螺杆冰带油量较大问题的症结所在,并提出了改进措施,加以实施,初步取得了一定的效果。     

卧式离心脱水机在潘-选煤厂的应用

水分是外销煤的一项重要考核指标，也是考核选煤厂是否完成洗选任务的指标之一。为了能够更好的降低外销煤水分，潘-选煤厂引进了WZ1400-A型卧式离心脱水机。本文主要介绍了WZ1400-A型卧式离心脱水机工作原理和结构，故障处理及离心脱水机的单机测试实验。     

VM1300脱水机在选煤厂的应用实践

介绍新脱水机的优点及新旧脱水机的对比，以及新脱水机的维护注意事项。     

螺杆空气压缩机变频控制系统改造

本文介绍了螺杆空气压缩机变频控制系统的改造,以及其社会效益和经济效益。     

螺旋机构运动精度可靠性设计

将螺旋机构的诸原始误差视为随机变量,对螺旋机构具有螺距累积误差、中径锥度和椭圆度误差、牙型半角误差等各项随机变量分别进行了分析;运用微小位移的线性迭加原理,综合出各项误差导致的机构运动输出总误差,建立了机构运动精度可靠性分析模型;利用计算机数字仿真技术,考察了机构各项误差导致的机构运动输出总误差对机构输出运动精度可靠性的影响,从中获得了一些有意义的结论。     

基于Pro/E的双螺杆挤出机挤压系统三维参数化设计

将参数化设计技术应用于双螺杆挤出机挤压系统的设计。文章介绍了以Pro/Engineer为平台,利用Visual C++6.0和Pro/Engineer应用程序接口Pro/Toolkit,开发了双螺杆挤出机挤压系统的三维参数化设计软件。     

信息不完全条件下提前期可变的供应链生产库存联合优化

研究了信息不完全条件下提前期可变的单制造商-单销售商供应链生产库存联合优化,假设销售商的需求是未知分布的随机变量,提前期是订货批量的线性函数,将销售商每次的订货量、销售商的库存安全系数、制造商的每个生产周期中销售商的订货次数作为决策变量,对制造商和销售商的期望库存总成本进行联合优化,设计了优化算法,并给出了相应的算例。     

螺杆泵的选择、使用中的问题研究

伴随着螺杆泵举升方式应用规模的日益扩大,常规地面驱动螺杆泵装置存在合理选用的问题:螺杆泵的合理选用、带泵电机的合理选用等。如果选用不当,会造成电机和螺杆泵的效率下降、能耗过大;存在安全隐患等问题。     

联立方程模型的工具变量方法质疑与商榷

本文质疑联立方程模型前定变量的工具变量性质：前定变量并不保证与当期行为解释变量的相关性,由其构建的工作回归元所完成的分阶段最小二乘估计因而并非两阶段最小二乘估计。建议按照简约式方程构建工作回归元,其具有模型数理逻辑支持下的可替代意义。工作回归元的不同导致结构式方程分阶段最小二乘估计的不同结果,之于恰好识别方程则揭示了业内关于间接最小二乘估计方法的一个误区。     

单螺杆泵的合理选择研究

为合理选择单螺杆泵,将螺杆泵抽油井作为一个大的生产系统,把油层、套管、油管、井下螺杆泵机组和井口作为5个子系统,利用系统节点分析法,确定出泵的工作载荷,并根据油井的实际工作参数,对泵特性曲线进行换算。由油井工作参数和单螺杆泵输油特性曲线对比可知,单螺杆泵的特性曲线和油井工作参数配合最好的情况是:油井的工作点应位于泵特性曲线Q0-H0的下面,而且在高效区的开始处。实践证明,采用这种方法选泵,既能保证油井的产量,又能明显地提高单螺杆泵整套装置的效率,还能延长泵的使用寿命。     

Extend (r, Q) Inventory Model Under Lead Time and Ordering Cost Reductions When the Receiving Quantity is Different from the Ordered Quantity

This paper investigates the continuous review inventory model involving variable lead time with partial backorders, where the amount received is uncertain. The options of investing in ordering cost reduction is included, and lead time can be shortened at an extra crashing cost. The objective of this article is to simultaneously optimize the order quantity, reorder point, ordering cost and lead time. We first assume that the lead time demand follows a normal distribution and develop an algorithm to find the optimal solution. Then, we relax the assumption of normality to consider a distribution free case where only the mean and standard deviation of lead time demand are known. We apply the minimax distribution free procedure to solve this problem. For both cases, we also show that the objective cost function to be minimized is jointly convex in the decision variables. Furthermore, two numerical examples are given to illustrate the results.     

The cost of inflated planned lead times in MRP systems

Much of the current literature in the field of production and inventory control systems stresses the need to revise traditional forms of thinking regarding production processes, the role of inventories for work in process, and the need for reduced lead times or flow times. Group technology, manufacturing cells, and other means of incorporating repetitive manufacturing techniques into traditional job-shop settings constitute the leading edge in system development.Still, there is resistance to these dramatic changes, and traditional “business as usual” methods still predominate. This study attempts to illustrate graphically the cost justification associated with reduction in lead times which generally results from these new concepts. In most job shops today, lead times are much longer than they need to be due to inflation of lead time estimates. Actual lead times for the manufacture of fabricated and assembled products have been shown to be a direct consequence of the planning lead times used in the MRP planning process—a form of self-fulfilling prophesy.The research employs a simulation model of a factory using MRP as a planning tool in a multiproduct, multilevel production environment. Manufacturing costs constitute the dependent variable in the experiments, defined as the sum of material costs (including expedite premiums), direct labor costs (including overtime premiums), inventory carrying costs, and overhead costs. The independent variable being manipulated is the planned lead time offset used in the MRP planning process. Twenty values of planned lead time are evaluated ranging from a value that includes no slack time at all (pure assembly line) up to a value that allows 95% slack (queue) time which, unfortunately, is not uncommon in many job shops today. Stochastic variables in the model include customer demand and actual processing times—the sum of set-up and run times.The result of the study is a cost curve formed over the range of independent lead time variables that is constructed using nonlinear regression techniques. The conclusions from the resultant graph clearly indicate the cost consequences of long lead times, with exponential cost increases beyond the 80–90% queue time level. Total costs are 41% higher at the maximum lead time allowance compared to the minimum. Clearly, this study demonstrates the need for lead time reduction, either through downward adjustment of MRP planned lead times or by introducing new manufacturing concepts.