遭雷击后线路绝缘子的绝缘性能与输电线路的安全运行

介绍了遭雷击后输电线路绝缘子的绝缘性能及其对输电线路安全运行的影响,在昆明1970m海 拔高度的试验室内,对遭雷击的、运行中的及新的500kV线路悬式绝缘子进行了工频和雷电冲击比对 试验。有限数量的试验结果表明,不同绝缘状况下的绝缘子的电气特性不尽相同;同一杆塔上遭雷击的 同一绝缘子串中各绝缘子的绝缘特性并不一样;遭雷击的绝缘子与运行中的及新的绝缘子相比,其表面 绝缘特性也不完全劣化。     

夏邑县火店南煤勘查区二2煤层煤质评价

夏邑县火店南煤勘查区位于夏邑县城东南25 km。通过对主要可采煤层二₂煤各指标的定量分析表明，勘查区二₂煤属半亮型煤，低灰、低挥发分、特低硫、较高软化温度灰和较高流动温度灰、特高热值的无烟煤三号和贫煤。贫煤可作气化、动力和民用煤；无烟煤除可作动力和民用外，块煤可作化工原料，经过一定加工，粉状煤可供高炉喷吹燃料。     

高层建筑施工安全问题及管控措施研究

近些年来建筑业获得了飞速的发展,其中一个较为突出的现状就是高层建筑变得越来越多。由于高层建筑自身构造的特点,导致了高层建筑施工技术具有较高的要求。因此,高层建筑施工安全问题就成为了人们关注的焦点所在。本文将围绕高层建筑施工安全问题展开进一步的讨论,并根据高层建筑构造复杂化和功能实用化的特点,提出了我们必须强化对于高层建筑施工安全的管控措施,遏制住高层建筑施工安全隐患发生的源头,促进施工过程中的安全生产,从而保障高层建筑施工工程的质量,进一步保护好社会经济利益和个人人身安全。     

Phase structure and vibrational spectra of rare-earth-oxide ceramics of Dy<Subscript>2(1−<Emphasis Type="Italic">x</Emphasis>)</Subscript>Tm<Subscript>2<Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>3</Subscript>

Rare-earth-sesquioxide ceramics have been found to possess potential applications in solid-state lasers due to their excellent physical and chemical properties as well as low cost. In this paper, composite powders with the composition of Dy_2(1−x)Tm_2x O₃ were prepared by ball milling method and corresponding ceramics were obtained using the pressureless sintering technique. Phase structure and vibrational spectra were investigated using X-ray diffraction, Raman spectrometer, and FT-IR spectrometer. It is shown that the mixture of Dy₂O₃ and Tm₂O₃ converts to an ordered solid solution of body-centered cubic structure after heat treatment at 1,100 °C for 4 h. It is also found that the cell constants of ceramics decrease linearly with the increase of Tm₂O₃ content. Raman spectra analysis demonstrates that bond length plays a major role in determining the frequencies of Raman bands at high-frequency range and that peak positions exhibit a blue shift with the increase of Tm₂O₃ content due to decreasing cell constant. Similar phenomenon is also observed in infrared spectra, which shows linearly increasing infrared band frequency with decreasing cell volume. The ball milling method used for preparing composite powders and vibrational spectra analysis in this work provide some important references for the study of laser ceramics containing Dy₂O₃ and Tm₂O₃.     

Response sensitivity analysis of the dynamic milling process based on the numerical integration method

As one of the bases of gradient-based optimization algorithms, sensitivity analysis is usually required to calculate the derivatives of the system response with respect to the machining parameters. The most widely used approaches for sensitivity analysis are based on time-consuming numerical methods, such as finite difference methods. This paper presents a semi-analytical method for calculation of the sensitivity of the stability boundary in milling. After transforming the delay-differential equation with time-periodic coefficients governing the dynamic milling process into the integral form, the Floquet transition matrix is constructed by using the numerical integration method. Then, the analytical expressions of derivatives of the Floquet transition matrix with respect to the machining parameters are obtained. Thereafter, the classical analytical expression of the sensitivity of matrix eigenvalues is employed to calculate the sensitivity of the stability lobe diagram. The two-degree-of-freedom milling example illustrates the accuracy and efficiency of the proposed method. Compared with the existing methods, the unique merit of the proposed method is that it can be used for analytically computing the sensitivity of the stability boundary in milling, without employing any finite difference methods. Therefore, the high accuracy and high efficiency are both achieved. The proposed method can serve as an effective tool for machining parameter optimization and uncertainty analysis in high-speed milling.     

LNG储罐区防液堤的设计探讨

结合工程实例,探讨了LNG储罐区防液堤设计中有效容积和形状的确定、混凝土材料的选择和配置.针对提高防液堤的抗低温和耐高温性能,提出了建议.     

水泥窑协同处置油基钻屑经验

水泥窑系统因具有高温、强碱性环境、热容量大等优势,在处置油基钻屑类危险废物方面有着无可比拟的优势,在国外相关案例的启发下,A厂和B厂两条2500 t/d水泥生产线分别在2018年建设了油基钻屑焚烧系统,经过近一年的调试,解决了接收、卸车、输送、与水泥窑结合等诸多问题,最终实现了安全稳定运行,均实现了日处理100 t以上的实际处置量.     

木质素基活性炭的制备和吸附特性

用磷酸活化法制备木质素基活性炭,研究了浸渍比、磷酸浓度、活化温度、活化时间对其吸附性能和得率的影响。结果表明,随着浸渍比、磷酸浓度、活化温度、活化时间的增加,活性炭的碘吸附值和亚甲基蓝吸附值均先升后降。适当提高这4个数值有助于木质素形成较多的微孔,提高活性炭的吸附性能;但超过一定程度时,活性炭内部的部分微孔之间的孔壁变薄甚至被烧穿,造成微孔扩大至中孔甚至大孔。同时,磷酸与已生成的微孔结构的孔壁碳原子发生反应,引起炭材料过度烧蚀,使孔径变大,导致活性炭的吸附性能降低。这种活性炭对苯酚的吸附符合Freundlich等温吸附方程,吸附动力学符合Lagergren拟二级速率方程。     

非接触式电压传感器电极仿真分析

传统电压互感器在体积、微弱信号测量精度以及电绝缘程度方面仍然存在不足,为满足铁路道岔转辙机内部狭窄空间内线路电压非接触测量的需求,根据电容耦合原理,提出一种非接触式电压传感器制作方法,并采用仿真软件COMSOL Multiphysics中的AC/DC模块对不同结构的感应极板进行建模仿真并进行计算及分析对比,选用适用于当前测量状况的电容极板,在保证对原转辙机内部电路系统影响较低的基础上,实现对线路电压的准确稳定测量.为非接触式电压传感器前端电极的选择提供理论依据.