公路隧道喷射混凝土套拱加固结构力学特性

为研究喷射混凝土套拱加固前后二次衬砌与混凝土套拱的受力状况,依托陕西汉中至留坝段八里关隧道,运用有限元软件建立隧道混凝土结构套拱加固分析模型,并通过现场监测获取二次衬砌与套拱间的接触压力、套拱格栅拱架钢筋应力、套拱混凝土应力,将数值模拟结果与现场测试结果相结合,得出套拱结构的一般受力变化规律。结果表明:套拱加固前衬砌结构的最不利荷载位置位于施工缝附近的拱顶、拱肩与拱脚处; 由于衬砌局部变形与温度应力的影响,套拱混凝土应力变化呈现反复“上升-下降-上升”最后趋于稳定的特点; 套拱的作用是控制二次衬砌的进一步变形,套拱施作后所承受荷载较小,套拱反作用力远小于围岩作用于衬砌的应力,在应力计算中不应将衬砌与套拱作为整体计算; 套拱结构数值模拟所得的结果与现场测试套拱结构内力(轴力、弯矩)的大小及分布相似度高,但在衬砌裂损严重部位,数值模拟所得结果误差较大,应以现场测试结果为准。     

长期护理保险政策对养老护理员队伍的影响及优化对策研究

通过对养老护理员队伍稳定性的调查研究,了解长护险制度对于养老机构护理员队伍离职意愿的影响,为提高护理员队伍稳定性、促进队伍良性发展提供长护险政策优化对策和建议。采用定性和定量相结合的调查研究办法,对上海养老机构和居家养老护理员进行问卷调查和个别访谈,采用SPSS23.0软件统计分析调查资料。结果显示,在长护险制度背景下养老机构护理员压力趋多、负担趋重、薪酬公平感降低,队伍稳定性受到极大影响,建议通过缩小养老机构和居家养老护理员之间的薪酬差距,建立居家养老护理员实地培训基地,注重护理员队伍的培育和素质提升问题,优化护理员考核评价标准等一系列措施,优化长期护理保险政策。     

Finite element optimization of sample geometry for measuring the torsional shear strength of glass/metal joints

Assessment of mechanical properties of glass/metal joints is a challenging process, especially when the application relevant conditions of the joints have to be considered in the test design. In this study, a finite element method (FEM) is implemented to analyze a torsional shear strength test designed for glass-ceramic/steel joints aiming towards solid oxide fuel/electrolysis cells application. Deviations from axial symmetry of the square flanges (ends) of respective hourglass-shaped specimens and also supporting and loading sockets of the test set-up are included in the model to simulate conditions close to reality. Undesirable tensile stress and also shear stress concentration appear at the outer edge of glass-ceramic layers, which are less for the hollow-full specimen. The simulation results show that for a specimen with either 9 mm thick square- or 6 mm thick triangular-flanges, locally enhanced tensile stresses almost disappear, resulting in a symmetric shear stress distribution. The difference between the analytically derived nominal shear strength and the real critical shear stress derived via simulation reduces with decreasing the fracture torque.     

基于压缩机-支架系统的异常噪声研究

针对某乘用车发动机转速在1 573 r/min，压缩机开启时车内噪声异常的问题，对样车进行试验分析与诊断，对压缩机-支架系统进行仿真分析，提出改进方案并验证改进效果。利用LMS声振信号采集系统采集振动噪声数据，采用频谱分析、阶次追踪等方法，并结合压缩机-支架系统模态仿真结果，确定车内异常噪声是压缩机轴频21阶与压缩机-支架系统3阶模态频率接近发生共振造成的。通过优化支架结构来提高压缩机-支架系统3阶模态频率以此来避免共振，并换装橡胶驱动盘缓和压缩机输入扭矩波动。将改进结构进行整车试验，结果表明：匀速工况空调开启时问题转速下，车内噪声降低了2.5 dB(A)；匀加速工况空调开启时发动机转速1 500~1 650 r/min区间，车内噪声无峰值，其余转速空调开启时改进前/后车内噪声基本不变，噪声波动趋势平缓。     

抽水蓄能发电机定子线棒绝缘击穿故障分析

通过对抽水蓄能机组定子绝缘击穿故障线棒进行解剖分析和理化性能测试，研究线棒受损的外力来源，结合机组安装期线棒下线情况及端部成型工艺，应用有限元结构分析程序ANSYS仿真计算线棒端部校形受力情况，提出线棒校形会对出槽口处的绝缘产生受力集中点，击穿面绝缘内部产生裂纹并逐渐由内向外劣化，最终导致线棒绝缘击穿事件的发生。     

Investigation of fracture behavior of cement-bonded corundum castables using wedge splitting test and digital image correlation method

To investigate the fracture behavior of cement-bonded corundum castables, various cement contents and pre-treating temperatures have been comparatively studied using the wedge splitting method and the digital image correlation technique. The results show that the microstructure enhances the mechanical properties, so the fracture energy and the maximum load as well as the fracture modes are affected correspondingly. The castables demonstrate the highest fracture energy and maximum load at 1600 °C with cement content of 10 wt% due to an appropriate amount of CA6. At the temperatures of 110 and 1100 °C, the crack propagation within the matrix and along the interface are dominated whereas within the aggregates significantly increased at 1600 °C, leading to the brittleness of materials. However, increasing the cement content can reduce their brittleness, caused by the maximum strain in thex-direction, largest length of the main crack, and high ratio of crack propagation in the matrix.     

无线电综合测试仪校准装置的研究及其不确定度分析

This calibration device of radio comprehensive tester is studied and established in this paper. It solves the verification and calibration of a large number of general-purpose radio comprehensive testers. The calibration device consists of four calibration sub- systems and calibration software system, including RF generator, audio generator, audio analyzer and RF analyzer. It also researches on the configuration of standard equipment and analyzes the uncertainty of the calibration devices, ensuring accurate and reliable val- ue transfer.     

浅谈枪支(弹药)库室电子技防测试

一个完整枪支(弹药)库室的安全防范由管理要求、物防要求、技防要求及人防要求完美的结合而成,其中技防要求是需要根据枪支(弹药)库室现场实体情况采取的一项电子技术手段,是起到安全预报警的最佳方式。本文就枪支(弹药)库室安全防范在技防要求方面按现行GA 1016-2012标准在检测中存在的问题做一些探讨、建议,以期为需要枪支(弹药)库室的建设单位、施工单位提供参考。     

An Innovative Non-Pillar Coal-Mining Technology with Automatically Formed Entry: A Case Study

A non-pillar coal-mining technology with an automatically formed entry is proposed, which reduces the waste of coal resources and the underground entry drivage workload. Three key techniques in this technology cooperate to achieve automatic formation and retaining of the gob-side entry, and to realize non-pillar mining. Constant-resistance large deformation (CRLD) support ensures the stability of the entry roof; directional presplitting blasting (DPB) separates the entry roof and the gob roof; and a blocking-gangue support system (BGSS) integrates the caved rock material as an effective entry rib. An industrial test was conducted to verify the engineering effects of these key techniques. The field application results showed that the retained entry was under the pressure-relief zone due to the broken-expansion nature of the caved rock mass within the DPB height. After going through a provisional dynamic pressure-bearing zone, the retained entry entered the stability zone. The final stable entry meets the requirements of safety and production. The research results demonstrate the good engineering applicability of this technology. By taking the framework of the technology design principles into consideration and adjusting the measures according to different site conditions, it is expected that the proposed non-pillar coal-mining technology can be popularized on a large scale.     

Test sample allocation method for testability verification test

An extended failure mode effect and criticality analysis (FMECA)-based sample allocation method for testability verification is presented in this study to deal with the poor representativeness of test sample sets and the randomness of the testability evaluation results caused by unreasonable selection of failure samples. First, the fault propagation intensity is introduced as part of the extended information of FMECA, and the sample allocation impact factors of component units and failure modes are determined under this framework. Then, the failure mode similarity and impact factor support are defined, and the game decision method for weighing the relationship between similarity and support is proposed to obtain the weight of failure mode impact factor. Finally, a two-step allocation framework of test samples is formulated to realize the sample allocation of component units and failure modes. This method is applied to the testability verification test of a launch control system. Results show that this method can obtain more representative test samples compared with the traditional sample allocation method while effectively reducing randomness of single testability evaluation result.