液压支架电液控制及工作面自动化技术综述

介绍了支架液压技术、液压支架电液控制系统及工作面自动化技术发展历程,分析了各阶段技术发展特点,展望了未来技术发展趋势.     

基于虚拟样机技术的液压支架模型干涉检查

本文应用虚拟样机技术就液压支架干涉检查的原则和内容进行了研究,并利用三维建模软件进行静态干涉检查,利用动态仿真软件进行动态干涉检查,从而为该类问题的解决提供了技术基础。     

基于分布式控制的液压支架电液控制系统的实现

介绍了基于分布式控制的液压支架电液控制系统构成、单元控制器硬件电路的设计 及控制软件的功能,讨论了电源与负载的匹配关系对系统抗干扰能力的影响,提出了浮动编组、差 时启动的多架推溜控制方法以及在电磁铁驱动电路、液压控制回路上的常闭性安全防护措施。     

Extreme reaches and maximal reachable workspace for rotary tools mounted on a Stewart platform manipulator

Abstract

A new type of problem associated with the extreme reaches of the Stewart platform manipulator is dealt with in this paper. Given a specified orientation of the tool axis, the problem involves finding the extreme distance that the tool bit mounted on the mobile platform can reach from its home position along any specified direction. During the motion, the mobile platform is allowed to be rotated about the tool axis to adjust the configuration of the driving mechanism to prevent premature activation of the kinematic constraints. A numerical optimization algorithm based on the concept of the cyclic coordinate descent method is developed for solving this problem, in which all three types of kinematic constraints, namely the actuator stroke constraint, the passive joint limitations, and the link interference conditions, have been taken into account. In addition, a numerical example is presented to demonstrate the ability of the proposed method to find the optimal reachable workspace of the robot.     

自适应模糊系统在车削工件直径误差预测中的应用研究

根据车削过程中工件直径误差的特点,提出了用自适应模糊系统预测由弹性变形等因素引起的工件直径误差的思路,通过梯度下降算法训练M amdan i型模糊系统,以确定合理的系统参数。根据工件直径误差与切削深度、进给量等的关系,进行车削实验,得到训练数据和测试数据,用训练数据训练模糊系统,进而用测试数据进行测试,得到结果合理,从而验证了利用自适应模糊系统进行工件直径误差预测的可行性。和回归分析的预测值进行比较,比较结果显示了自适应模糊系统在车削工件直径误差预测方面的应用具有优势。     

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.     

残采工作面滑移顶梁支架的应用

为降低滑移顶梁支架工作面的事故率,提高滑移顶梁支架的安全性,采取增强滑移顶梁支架易损部件的强度、在支架上焊接柱销、安装挡矸板并穿设钢丝绳、加设推移千斤顶方形栏等方法对滑移顶梁支架的支护方式及设计进行改进.结果表明:技改后采场顶底板移近量减小,最大顶板下沉量不超过100 mm,易损部件使用平均寿命增加到35 d以上,解决了滑移顶梁支架失稳及平衡力减小、采空区窜矸等问题,避免了落煤爆破造成顶梁变形断裂,保证了支架推移时千斤顶不上翘,大幅降低了开采成本,效果显著,整体提高了滑移顶梁支架的安全性.     

特厚煤层综放液压支架主要支护参数的研究和探讨

根据庞庞塔煤矿10号煤层地质条件、工作面开采及布置方式等情况,介绍了特厚煤层综放液压支架高度、工作阻力以及支架初撑力等主要支护参数的确定原则与方法。试验结果表明:支架的主要支护参数设计合理,安全性、可靠性高;提高了特厚煤层回收率,为工作人员和综采设备提供一个安全可靠的作业空间。     

A variable neighborhood descent heuristic for arc routing problems with time-dependent service costs

This paper proposes a variable neighborhood descent heuristic for solving a capacitated arc routing problem with time-dependent service costs. The problem is motivated by winter gritting applications where the timing of each intervention is crucial. The variable neighborhood descent is based on neighborhood structures that manipulate arcs or sequences of arcs. Computational results are reported on problems derived from classical capacitated arc routing problem instances. A comparison is also provided with an alternative approach where the arc routing problem is solved after being transformed into an equivalent node routing problem.     

液压支架顶梁的迭代差分分析

本文按薄板小挠度理论,用迭代差分法分析了液压支架顶梁在若干加载条件下的挠度、内力和应力,给出了相应的最大应力值及其位置,并与实测结果及有限元法分析结果进行了比较。