电力线路张力放线自制牵引机液压系统没计方案

阐述了电力线路张力放线自制牵引机设计中与进口设备完全不同的一种新型液压驱动设计方案,该方案使电力线路张力放线液压系统元件国产化得以实现.     

基于CMAC的恒张力控制系统研究

针对张力控制系统的时变性和耦合性,通过卷辊和带材的动力学分析,建立了张力系统动力学模型,分析了影响张力的主要因素.为解决常规PID控制在张力控制过程中难以实现参数整定的问题,提出CMAC与常规PID并行控制方案,利用CMAC的非线性映射能力适应时变系统的要求.建立了控制系统模型,并进行了仿真.结果表明,该方法的控制效果优于常规PID,抑制扰动能力强、稳定性较好.     

复合材料非连续带材缠绕控制技术研究

为实现复合材料带缠绕大拉伸比的工艺要求,提出了非连续带材缠绕.在分析成型工艺过程和可能存在技术难点的基础上,对影响缠绕制品质量的张力、布带拉伸比、布带自动续接及自动纠偏等因素的控制方法及相互作用机理进行了研究.根据缠绕工艺要求,设计出机械装置和控制方案.为验证方案的合理性,在非连续带材缠绕机上做了工艺试验,并对缠绕样件的性能指标进行了对比分析.经应用验证,变张力控制使布带缠绕、布带续接过程具有不同张力,保证整个缠绕过程的恒拉伸比,同时不会使布带在搭接处重新断开,实现了非连续带材的自动化缠绕.     

航空电动绞车缠绕机构变张力控制系统

航空电动绞车主要用于极端条件下人员救援或物资运送,为保证安全工作,需加装钢缆缠绕机构张力控制系统.文中提出了一种基于绞车滚筒和张力轮速度差实现的实时变张力控制方案,主要介绍了单片机信号采集处理和电机驱动控制模块,重点解决了单片机PWM控制信号产生以及电机低速平稳性问题.实验证明,该系统可根据实时信号灵活控制张力有无及方向,具有结构简单、重量轻等特点,特别是对于高性能轻型起吊机有普遍意义.     

电力线路张力放线自制牵引机液压系统设计方案

阐述了电力线路张力放线自制牵引机设计中与进口设备完全不同的一种新型液压驱动设计方案，该方案使电力线路张力放线液压系统元件国产化得以实现。     

卷筒纸印刷机张力控制研究

针对卷筒纸印刷生产的特点,阐述了张力控制的目的和影响张力的主要因素,分析和研究了纸带张力控制机理.通过对罗兰卷筒纸印刷机纸带张力控制系统实例,详细剖析了张力控制系统的控制规律和控制回路.说明了张力控制系统中采用的PID控制规律的优点,并得出纸带张力控制系统的影响因素和控制中需要解决的相应问题.     

动态闭环绕线张力精确控制方法建模与仿真

绕线过程中的张力控制是影响产品质量的重要因素,为此提出了一种较为精确的绕线闭环张力控制方法,该方法通过线性弹性元件和张力传感器共同实现对绕线张力的高精度控制.通过分析绕线过程中的受力情况,建立了理想力学模型,推导了模型的键合图,并在此基础上对整个张力控制系统进行了仿真分析.验证了该张力控制方法具有频响快,张力控制稳定性高,预设张力在线跟踪能力强等特点.     

通过控制丝网印版张力提高印刷质量

介绍了丝网印版张力控制的重要性,及印版张力与网距之间的关系.随后具体论述了因印版张力不足所导致的各种印刷质量问题.最后总结了如何从印前准备到印刷等各个阶段调控印版张力,使之得到最好的印品.     

卷筒纸印刷机张力系统的检测

阐述卷筒纸印刷机纸带张力控制的重要性和张力不当产生的印刷问题;针对张力的重要作用阐明了张力控制中的张力检测问题,着重论述目前卷筒纸印刷机中采用的几种典型张力检测装置的原理和检测方法.     

连轧张力公式的实验验证和分析

连轧张力公式是连轧理论和实践的核心问题,该问题国内外都有大量的研究,20世纪60年代笔者推导了连轧张力微分方程、多机架动态张力公式、稳态张力公式,理论上已作过深入、广泛的分析讨论.日本在20世纪70年代对连轧张力公式进行了理论上的推导和实验验证,特别是浅川基男等人的连轧实验结果更为重要.为此引用了浅川基男的实验数据和宝钢2050 mm热连轧机上的实测数据,验证了连轧张力公式.     

A study of JIT implementation and operating problems

This paper reports the results of a survey of early implementators of the just-in-time (JIT) philosophy in the United States with particular emphasis on the identification of implementation problems and operating problems. There were 39 respondents to the survey who were in the process of implementing JIT. Five classes of implementation problems and eight classes of operating problems were identified.     

电商包装存在问题及对策

目的研究电商包装存在的问题,并提出解决对策。方法采用查阅文献、网络调研等分析电商包装的特点,并基于电商包装的现状剖析其当前存在的突出问题,针对性地提出解决对策。结果通过对电商包装现阶段存在问题的深入研究,提出要从根本上解决电商包装包装不足、过度包装、环保问题突出、包装规格过多、用户体验不佳等问题,需要政府、包装企业、快递企业、电商企业等多方配合,共同提升电商包装回收利用率,要从产品包装设计、包装材料选择、包装操作规范和包装标准制定等多方面规范电商包装全流程,不断提升用户体验。结论电商包装现阶段仍然存在诸多问题,只有参与各方共同努力,协同改进电商包装中的问题,才能使电商包装回归本质、绿色环保、方便快捷。     

A Heuristic for a Class of Production Planning and Scheduling Problems

This paper describes a solution technique for a general class of problems referred to as aggregate planning and master scheduling problems. The technique is also applicable to multi-item single level capacitated lot sizing problems. The solution technique presented here is a heuristic that is practical for large problems e.g. 9 products and 36 periods. We have tested it for problems with varying number of time periods, number of products, setup costs, holding costs, overtime costs and capacity levels. For those problems that we could solve exactly using a branch and bound algorithm, the solutions produced by the heuristic were all within 1 % of optimality. For problems that we could not solve exactly, we are able to compute a lower bound on the optimal cost. Using the bound we are able to show that our heuristic solutions were within 2.93% of optimality on the average. Except for those problems having very high setup cost or problems with extreme seasonality, the algorithm produced solutions that were within 1 % of optimality on average.     

Cutting Plane and Branch and Bound for Solving a Class of Scheduling Problems

Two general purpose integer programming algorithms, one a fractional cutting-plane algorithm and the other a branch-and-bound algorithm, were investigated. The cutting-plane algorithm easily solves an important class of integer problems, a class of scheduling problems for the assigning of personnel to work shifts over a fixed period of time. Scheduling problems were constructed with 14 to 189 integer variables and with 14 to 21 constraints. The general branch-and-bound search was not effective on this class of scheduling problems, but it was effective on the classical test problems found in the literature of integer programming, many of which were not handled by the cutting-plane algorithm.     

卷筒卫生纸包装结构设计改进研究

通过市场调研及对消费者问卷的分析总结,发现了目前市场上的卷筒卫生纸包装存在的主要问题:销售包装较长,不便携带;提手强度及舒适度不佳;包装袋侧裂且包装规格较少等。通过对大量的设计实例进行归纳总结,建立了内包装、系列化销售包装的设计模型,有助于解决卷筒卫生纸包装现有的问题,同时方便生产企业进行快速包装结构设计。     

基于TRIZ理论的榨汁机创新设计研究

目的 基于TRIZ理论探索榨汁机存在的潜在问题,并依次解决电机温度升高、刀具存在的安全隐患和杯体内壁清洁困难问题。方法 在问题识别阶段,运用系统组件和功能分析对榨汁机进行问题描述,并通过因果分析流程探索问题发生的根本原因;结合分析结果,利用矛盾分析、技术系统进化、科学效应与效应知识库、发明问题解决算法、物场分析等方法获得问题的最终理想解,得出可行性方案。结果 通过TRIZ理论相关工具的运用获得问题的原理解,解决了产品的安全隐患、工作散热和清洁问题,设计出一款既保证了使用寿命和使用安全性,又强化了使用便捷性的榨汁机产品。结论 TRIZ理论为设计中多个方案的探索提供了依据,使榨汁机产品存在的诸多问题得到解决和优化;同时,为该理论在家电类产品的结构优化设计上提供一定的参考与借鉴。     

战储车辆器材包装的现状调查及对策研究

对战储车辆器材包装的现状进行了实地调查,详细分析了战储车辆器材包装存在的一些主要问题及其原因,并着重就战储车辆器材包装现状的改善、存在问题的改进提出了具体的对策.     

瓦楞纸板搓板状现象及粘合不良的原因及对策

从理论上深入研究了瓦楞纸板搓板状现象及粘合不良问题的原因及对策.     

Pre‐college Electrical Engineering Instruction: The Impact of Abstract vs. Contextualized Representation and Practice on Learning

Background While engineering instructional materials and practice problems for pre‐college students are often presented in the context of real‐life situations, college‐level texts are typically written in abstract form. Purpose (Hypothesis ) The goal of this study was to jointly examine the impact of contextualizing engineering instruction and varying the number of practice opportunities on pre‐college students' learning and learning perceptions. Design/ Method Using a 3 × 2 factorial design, students were randomly assigned to learn about electrical circuit analysis with an instructional program that represented problems in abstract, contextualized, or both forms, either with two practice problems or four practice problems. The abstract problems were devoid of any real‐life context and represented with standard abstract electrical circuit diagrams. The contextualized problems were anchored around real‐life scenarios and represented with life‐like images. The combined contextualized‐abstract condition added abstract circuit diagrams to the contextualized representation. To measure learning, students were given a problem‐solving near‐transfer post‐test. Learning perceptions were measured using a program‐rating survey where students had to rate the instructional program's diagrams, helpfulness, and difficulty. Results Students in the combined contextualized‐abstract condition scored higher on the post‐test, produced better problem representations, and rated the program's diagrams and helpfulness higher than their counterparts. Students who were given two practice problems gave higher program diagram and helpfulness ratings than those given four practice problems. Conclusions These findings suggest that pre‐college engineering instruction should consider anchoring learning in real‐life contexts and providing students with abstract problem representations that can be transferred to a variety of problems.     

用工业工程思想发现、解决和预防问题

在工厂现场问题研究的基础上,联系生活实际,对问题科学进行了研究.定义了什么叫问题;探讨了问题的本质;对工作生活中问题进行了分类;阐明了问题和风险以及问题和矛盾之间的关系.利用工业工程(IE)的思想,分析了普遍的如何发现问题及解决问题的思维过程;阐明了在工作和生活中如何利用问题的实质去发现问题,并最终解决和预防问题.报告了解决问题的三个原则、注意事项和步骤.