半气体爆破试验钢管裂纹扩展研究

为研究钢管爆破后的整体变形和最终形态,在低温条件下对直径等于1422 mm、壁厚为21.4 mm、长度为11 m的X80钢管在12 MPa压力下进行两次半气体爆破试验(其中,第一次试验:冷却液为85%、气化的氮气为15%,第二次试验:冷却液为90%、气化的氮气为10%)。利用聚能切割器在管道几何中心上侧沿轴线方向爆炸引入500 mm长的贯穿型裂纹(缺陷),使管道在高压作用下发生爆破,通过实测观察管道爆破的相关参数。研究得到了钢管在低温条件下裂纹扩展的速度、方向、长度及分布情况,为天气管线在低温条件下管线防护的工程设计和施工提供参考和借鉴 。

超声速化学氧碘激光(SCOIL)性能计算的半气体动理学(SGK)模型

对超声速COIL的分析和计算,提出了氧碘反应气流取连续介质近似,同时计算碘激光能级粒子速度分布函数,并用双参数摄动法求解粒子速度分布函数方程组的半气体动理学(SGK)模型,得到与常用Voigt线型及低压极限饱和模型不同的增益饱和模型.对预混合情况,分析计算了不同化学反应系统、不同增益饱和模型以及诸可调参数(包括气流参数、激发态氧的产率、水含量、阈值增益、频移等)对功效的影响.分析计算说明多个反应(包括21个)与选用单一共振反应的功效计算结果接近,而增益饱和模型不同和可调参数的差别对功效、最佳阈值增益范围、功率提取长度均有显著的影响.

静压气体径向与半球轴承混合支撑轴系设计及静特性研究

针对精密机床主轴结构采用前后2个静压气体径向轴承时存在的安装精度难以保证,且不能自动调心的问题,设计一种新型气浮主轴结构,该气浮主轴前端支撑采用静压气体半球轴承,后端支撑采用静压气体径向轴承。基于最大承载和刚度原则对静压气体径向和半球轴承进行结构设计与优化;利用Fluent软件对径向轴承与半球轴承分别进行气膜流场特性分析,得到径向轴承和半球轴承在不同偏心率以及不同转速情况下的承载特性。结果表明:径向轴承与球轴承的承载力均随着偏心率以及供气压力的增大而逐渐增大,刚度随着供气压力的增大而增大,随着偏心率的增大逐渐减小。设计的主轴在供气压力为0.5 MPa、偏心率为0.5时,承载力和静刚度均可以满足精密加工的要求。

高压气体长管半挂车车架高强度钢板强度等代设计

高压气体长管半挂车是输送高压气体的专用车辆,减小车架自重是提高单车运输效率的有效途径。对车架强度等代设计进行了研究,在车架结构优化的基础上用高强度钢板A610L代替原钢板16MnL,使车架重量减轻了455kg。强度等代设计后,车架强度余量增加,在实现轻量化的同时提高了车辆的安全性。

大型液化气体运输半挂车的分析设计

阐述了大型液化气体运输半挂车的性能参数和结构概况,运用有限元软件对强度计算中遇到的问题进行了分析。

大型变径液化气体运输半挂车的设计

介绍了开平机械厂目前研制的25t大型变径液化气体运输半挂车的结构特点及设计方案,通过与原结构的对比,证明该车结构更具安全、可靠性。

液化气体运输半挂车的有限元分析

本文以运输丙烷介质的半挂车为例,介绍了液化气体运输半挂车的整体有限元分析过程。以实体单元为对象建立有限元分析模型,考虑液化气体运输半挂车在常温环境下满载静强度及运行过程中受动态惯性力影响后结构的应力水平,对半挂车进行了有限元分析计算。

经纬机械（集团）有限公司：NBC-XXX型CO2半自动气体保护系列焊机

NBC-XXX型系列焊机晶闸管模块控制的半自动熔化极气体保护焊机，其关键部件均采用原装进口器件，结构合理，稳定，可靠，广泛应用于造船、车辆、工程机械以及锅炉、农机、防盗门等金属加工行业。

液化气体运输半挂车罐体的改进及其制作要点

改大型等径罐体为锥形罐体结构 ,可降低液化气体运输半挂车的质心高度 ,提高行驶安全性。

荆门变电站1000kV气体绝缘半封闭式组合电器的布置方案

荆门特高压变电站扩建工程新增3台1000kV断路器,采用气体绝缘半封闭式组合电器(hybrid gas insulated switchgear,HGIS),1000kV主接线由双断路器过渡接线完善为1个半断路器接线。结合该扩建工程的建设特点,分析了1000kV HGIS的"2+1"和"3+0"布置方式,研究了"3+0"方式面临的前期与本期HGIS基础不均匀沉降问题,计算了前、后2期基础的不均匀沉降量,提出了增加防沉降的伸缩波纹管补偿单元的方法以保障设备的安全运行。

应用裂纹检出率优化焊接工艺规范的研究

裂纹类缺陷是焊接过程中经常出现的最严重缺陷之一。无损检测方法是检测和评价焊接方法是否有效的重要手段。以裂纹检出率作为技术指标,对斜T型全熔透焊缝采用FCAW-CO_2焊接方法的焊接过程质量进行了综合评价,通过优化焊接参数消除了危险性缺陷,最终确保了完工焊缝的焊接质量和提高了产品的整体安全性。

Ag-coated Long-period Fiber Grating

Based on coupled-mode theo ry , the eigenvalue equation of five-layered long-period fiber grating(LPFG) sens or with Ag film and gas-sensitive film overlays are firstly studied. The probl em of resolving complex eigenvalue equation on five-layered LPFG is analyzed, a nd the method of resolution is also given. Then the eigenvalue equation of three -layered metal cladding LPFG is analyzed, and the complex transcendental equati on is also discussed. The computing result shows that the coupling between the l ow-order EH modes and the core mode is much stronger than that between the low -order HE modes and the core mode.

Comparison of Ge_xSi_(1- x) Grown by UHV/CVD from Si_2H_6/GeH_4 and SiH_4/GeH_4

Using double crystal X-rays diffraction (DCXRD) and atomic force microscopy (AFM), the results of Ge x Si 1- x grown by UHV/CVD from Si 2H 6 and SiH 4 are analyzed and compared. Adsorbates can migrate to the energy-favoring position due to the slow growth rate from SiH 4. In this case, a Si buffer that isolates the effect of substrate on epilayer could not be grown, which results in a pit penetrating into epilayer and buffer. The FWHM is 0.055° in DCXRD from SiH 4. The presence of diffraction fringes is an indication of an excellent crystalline quality. The roughness of the surface is improved if grown by Si 2H 6; however, the crystal quality of the Ge x Si 1- x material became worse than that from SiH 4 due to much larger growth rate from Si 2H 6. The content of Ge is obtained from DCXRD, which indicates the growth rate from Si 2H 6 is largest, then GeH 4, and that from SiH 4 is least.

Gas concentration monitoring system for small and medium-sized coal mines based on gas-sensing detection and single-chip control

This paper is aimed at the actual conditions of disaster caused by gas in small and medium-sized coal mines. A new gas concentration monitoring system for coal mines is developed on the basis of gas-sensing detection and single-chip control. The monitoring system uses the tin oxide as the main material of N-type semiconductor gas sensors, be- cause it has good sensitive characteristics for the flammable and explosive gas （ such as methane, carbon monoxide）. The QM-N5-semiconductor gas sensor is adopted to detect the output values of the resistance under the different gas con- centrations. The system, designedly, takes the AT89C51 digital chip as the core of the circuit processing hardware structure to analyze and judge the input values of the resistance, and then achieve the control and alarm for going beyond the limit of gas concentration. The gas concentration monitoring system has man）, advantages including simple in struc- ture, fast response time, stable performance and low cost. Thus, it can be widely used to monitor gas concentration and provide early wamings in small and medium-sized coal mines.

Impact strength and structural refinement of A380 aluminum alloy produced through gas-induced semi-solid process and Sr addition

Semi-solid processing of A380 aluminum alloy was performed by gas induced semi-solid(GISS)process.The effects of argon inert gas flow rate,starting temperature and duration of gas purging as key GISS parameters and also modification with Sr on the structural refinements,hardness and impact strength of GISS alloys were investigated.Microstructural evolution shows that there is an important effect of the pouring temperature and Sr addition on the morphology and size of primaryα(A1)in the alloy to change from coarse dendritic to fine globular structure.The best sample which has fine grains of 51.18μm in average size and a high level of globularity of 0.89 is achieved from a GISS processing of Sr modified alloy in which the gas purging started at 610℃.The impact strength of the GISS optimized samples((4.67±0.18)J/cm^(2))shows an increase of about 40%with respect to the as-cast sample due to the globular structure and fibrous Si morphology.Moreover,the hardness of the optimized GISS sample((89.34±2.85)HB)increases to(93.84±3.14)HB by modification with the Sr and GISS process.The fracture surface of Sr modified alloy is also dominated by complex topography showing typical ductile fracture features.

船用铸钢件的焊接修补施工工艺探讨

在船舶改装及修理过程中,发现有大量的铸钢件在长期使用后出现裂纹,其中一些大型的铸钢件,若是进行换新将会增加成本,同时修理周期较长。这就要求船厂使用合理的焊接方法对裂纹进行修补并保证其实用性。文章从船用铸钢(ZG230-450)的焊接工艺、裂纹的修补、施工控制、试验结果比较等方面阐述了铸钢修补焊接的工艺要素及施工要点。

焊机使用维护技术(二)

CO2气体保护半自动焊机控制电路的动作程序应怎样试验检查?

Analysis and design of resistance-wire heater in MOCVD reactor

Metal organic chemical vapor deposition(MOCVD) is a key equipment in the manufacturing of semiconductor optoelectronic devices and microwave devices in industry. Heating system is a vital part of MOCVD. Specific heating device and thermal control technology are needed for each new reactor design. By using resistance-wire heating MOCVD reaction chamber model, thermal analysis and structure optimization of the reactor were developed from the vertical position and the distance between coils of the resistance-wire heater. It is indicated that, within a certain range, the average temperature of the graphite susceptor varies linearly with the vertical distance of heater to susceptor, and with the changed distances between the coils; furthermore, single resistance-wire heater should be placed loosely in the internal and tightly in the external. The modulate accuracy of the temperature field approximately equals the change of the average temperature corresponding to the change of the coil position.

Electrochemical C-V Characteristics and Photoluminescence of a-C∶N Films

Amorphous carbon (a-C) films and amorphous carbon films incorporating with the nitrogen (a-C∶N) were deposited on silicon substrates in a radio-frequency driven plasma enhanced chemical vapour deposition system, while the surface electrical properties of films were investigated by electrochemical capacitance-voltage measurements. It was examined the effect of the interface defects on the properties and deduced that the conducting type of a-C∶N films was n-type. Subsequently, a comparative studies of a-C and a-C∶N films were performed by photoluminescence spectra depending on the temperature. With the decrease of the temperature, the main band with peak energy of 2.48 eV in the a-C∶N films was more intense compared with the other three bands caused by amorphous C in the a-C films.