东风水库左岸补强帷幕灌浆施工关键技术研究

水利工程施工过程中,帷幕灌浆方法因其能够形成阻水帷幕以减少库水渗透量,对坝基渗漏问题能够起到较好的防渗效果,在实际工程中得到广泛应用。本文以东风水库左岸补强防渗工程为例,结合工程区工程地质条件及补强防渗设计方案,就帷幕灌浆补强防渗施工过程中的灌浆关键技术进行探讨。     

等离子喷涂热障陶瓷涂层冷却累计残余应力的有限元模拟与验证

Plasma sprayed ZrO2 ceramic coating has been widely used in many industrial fields due to its simple manufacturing process, low cost, and good heat insulation effect. However, the structure and service conditions of thermal barrier coatings are complex, and residual stresses will inevitably occur during the preparation process as well as application. Residual stress has the most obvious influence on the life of thermal barrier coatings, seriously reducing the bonding strength between the coating and the substrate, and ultimately showing the cracking and spalling of the coating, greatly reducing the service time and stability of the coating during service. To realize the prediction and detection of the residual stress, it is necessary to seek a reliable detection method for thermal barrier coating to effectively predict the accumulated residual stress in the cooling process of coating and reduce the influence of residual stress on the stability of the coating. In this paper, the finite element model of plasma-sprayed ZrO2 coating was established by using the birth and death element method. Gauss heat source was used to simulate the heat source condition of plasma spraying, and the residual stress and its distribution of the coating cooling to room temperature were studied. The residual stress of ZrO2 coating prepared by plasma spraying was detected by X-ray diffraction and Raman spectroscopy to explore the accurate detection method of residual stress in ceramic coating. Through the analysis of the finite element results, it is found that the number of elements is reasonable and the calculation time is short when the mesh unit size of the model is 1.75 mm. The maximum temperature of the coating temperature field obtained by simulation is consistent with the test temperature in the experiment, and the simulation results are accurate. It can be concluded that the residual stresses in the central region of the plasma spraying coating after cooling to room temperature are larger than those in the edge region, which are mainly concentrated in the central region of heat flow. There is large stress at the bonding interface of each layer, which causes the stress to change significantly along the thickness direction of the coating. The equivalent stress of the coating is 160-220 MPa. The X-ray method was used to detect the residual stress of plasma sprayed coating. To obtain an isolated, complete, high peak position and high peak intensity with enough diffraction peaks to avoid the influence of texture, (331) crystal plane with a high multiplicity factor was selected as the characteristic peak. The test results show that the residual stress in the coating will make the position of the characteristic diffraction peak shift to a high angle at 2θ=153°. The residual stresses of 180-185 MPa were detected by X-ray diffraction. The I6 peak in the Raman spectrum of the coating was used as the characteristic peak of the spectrum to represent the frequency shift of the Raman spectrum band. Compared with the original spraying powder, the position of the Raman characteristic peak of the ceramic coating shifted to the low-frequency direction, indicating that there was residual tensile stress after the coating was cooled. The Raman-stress factor of the ZrO2 coating was calibrated to be 8.33 (cm·GPa)-1, and the residual stress of the coating was calculated to be 174-180 MPa. In this paper, the finite element method can effectively simulate the residual stress inside the coating when the plasma spraying reaches room temperature. It has good matching with the XRD and Raman spectrum detection results. There is about 180 MPa residual stress inside the coating when the coating is cooled to room temperature, seriously affecting the stability of the coating. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.     

设计中受变动回水顶托影响的水位流量关系线拟定

通过对水利水电工程设计中水文测站控制断面的水位流量关系受下游变动回水顶托影响的几种不同情况的叙述，介绍了其影响下的常规水文资料整编方法，及以下游水位为参数拟定水位流量关系的方法。     

低压电力线载波通讯信道的分析与载波信号注入耦合电路的设计

本对低压电力线载波通讯信道的参数特性和影响通讯质量的因素进行了定性分析；为了提高通信通讯质量提出了载波通讯中心频率的选择方法；给出了中心频率注入耦合和检出通讯中心频率的原理框图及实际电路，并对此进行了原理性说明。     

浅析检察行为的宪政内涵和宪政意义

检察行为的宪政内涵体现在我国的检察权是一种独立的法律监督权,检察行为是一种独立的法律监督行为,检察行为的行使内在统一于检察机关的法律监督属性.检察行为的宪政意义应该体现在检察行为对实现宪政目标的推动和保障方面的重要作用.     

冷藏车热性能的老化

本文论述了冷藏车的隔热性能、气密性能和降温性能随着使用年限老化的理论根据和实测数据,介绍了国外在这方面的研究水平和我国铁路四方车辆研究所8年来所作的工作。文章指出,研究热性能老化对改善冷藏车结构设计、材料选择和运用热计算有着重大的意义,这项工作应扩大测试车种并坚持进行到车辆的寿命期方能有效。     

国产机冷车制冷设备的现代化

一、前言 我国第一代五节式机械冷藏车组(B19型)使用了以国产4FS7B制冷压缩机为主机的制冷机组,这种制冷机组虽经多次改进,但低温制冷性能总不理想,机组的制造及组装工艺也不先进,“脏、堵、漏”的现象不时发生。由于制冷机组不过关,也是导致第一代机冷车组停产的原因之一。 我国单独制冷式机械冷藏车大部分是从原民德德骚工厂进口的。文革初期进口的B18型车,货物车安装314.005型制冷加热设备两套。七十年代中期进口的B20型车,货物车安装     

基于恒定开关频率的12区段DTC系统的研究

传统的直接转矩控制方法将磁链控制为六边形或是6区间圆形,转矩的控制使用一个滞环比较器,这种方法会造成开关频率变化、转矩脉动过大。为解决这些问题,在传统直接转矩控制的基础上介绍一种改进方法,将传统6区间圆形磁链细分为12区间,并使用一种恒定开关频率控制器以取代转矩滞环比较器,来解决传统6区间磁链以及转矩滞环比较器存在的缺陷。仿真结果表明,该方法能保持开关频率恒定,并能有效地减小转矩脉动。     

建筑工程中造价超预算的原因及控制对策

在建筑工程施工中,造价是整个工程所消耗的费用的总和,直接关系到建筑企业的经济效益。造价预算是在工程开始之前,对工程的费用消耗做出的预算,为工程的经济效益提供一定的借鉴。但是,在实际施工中,由于市场因素的变化,各项费用支出都会发生变化,所以会导致造价预算无法实现,超出工程预算的范围,致使工程的经济效益大大的降低。文章对于建筑工程中造价超预算的原因进行了分析,然后提出了合理的控制措施,为工程造价的合理控制提供了借鉴。     

蚕室升温补湿靠壁灶

湖州市农村能源办从八四年开始研制蚕桑靠壁灶,为重点蚕区饲养小蚕提供了一种能达到升温、补湿、符合小蚕生理要求的良好加温形式。推动了科学养蚕技术的应用,提高了暗火饲育率,防止了人、蚕中毒,蚕茧产量大幅度增产。