12Cr17Ni7不锈钢中大型夹杂物的分析

对12Cr17Ni7(ASTM/301)不锈钢连铸坯中大型夹杂物的形貌和化学成分进行分析。结果表明:该夹杂物是由Fe、Cr、Ni、Mn等金属组成,且有一定的韧性。分析认为该夹杂物是在连铸过程中,在结晶器上较长时间凝结的钢液滴在表面受到氧化后被钢水冲入钢液,这种没有上浮的半凝固态的钢液滴,在连铸后进入铸坯中形成外来的金属夹杂物;对此提出具体的控制措施。     

一种林间自装卸粉碎机底盘设计与分析

针对目前移动式林间粉碎设备存在的问题,提出了一种林间自装卸粉碎机底盘.介绍了其行走系统、车架、支撑系统、液压系统、制动系统、转向系统等.通过CATIA软件对该底盘进行了主要部件的三维建模和装配,并对底盘进行了强度分析.     

地铁明挖区间废水泵房破除改造方案研究

已投入运营的武汉地铁4号线明挖区间右线废水泵房侵入拟建5号线盾构区间限界,需对其进行破除改造。通过对1 m、3 m及5 m破除进尺长度时各施工工况进行数值模拟分析,获得不同破除进尺长度时各施工工况下明挖区间结构及土体变形情况。分析结果表明:采用5 m进尺长度的破除施工方案是可靠的、合理的;破除所引起的结构变形主要集中在4号线区间右线结构顶、底板,破除结构前应于紧邻破除区5.0 m范围内设置水平、垂直向临时钢管支撑。数值分析所得数据和结论不仅为破除改造时的支护体系设计提供依据,也可为类似工程提供有益的借鉴。     

基于CREAM的航天发射场人因可靠性定量分析方法研究

以我国航天发射场安全评估为背景,基于认知可靠性和失误分析方法(CREAM),开展航天发射场人因可靠性(HRA)定量分析方法研究。首先结合航天发射场特点对共同绩效条件(CPC)进行改进,之后采用模糊方法处理CPC到控制模式之间的映射关系,提出了环境影响因子值的概念,提出了航天发射场HRA定量分析流程,最后针对火箭吊装过程进行了实例分析。     

基于空间分析的城市火灾风险评估与应用——以西安为例

城市消防是城市中重要的安全保障体系之一,本文从消防重点地区、人口密度、高层建筑分布、大型人流密集的地下空间等风险要素的空间分析入手,探索城市火灾风险评估的方法及其应用,旨在为编制城市消防专项规划、城市消防设施建设和城市消防安全管理提供扎实、科学的依据。     

火电厂ZYGL-Ⅲ型专用在线工业离子色谱分析测量装置的研制及应用

针对传统的水质分析仪器在大机组火电厂应用过程中存在阻抗不匹配、测量信号衰减,静电、电磁场干扰,以及传统高效离子色谱分析法代表性不强,测量数据传输不及时,受环境温湿度影响大等问题,研制了电极常数为0.001 cm^-1、测量范围0~0.001的专用在线工业离子色谱分析测量装置,并在内蒙古京隆发电有限责任公司投入使用。实际使用情况表明,该装置可以准确测量出各种离子的质量分数,应用效果良好。     

横泉水库帷幕灌浆试验点分析

横泉水库工程地质条件复杂,采用帷幕灌浆的方法对风化岩层进行处理以满足水库对防渗要求.风化岩层上为厚度16～30m的覆盖层,覆盖层由土层和砂卵石层组成.主要介绍了深覆盖层下风化基岩帷幕灌浆试验的钻孔、灌浆施工方法及其灌浆效果分析.为风化基岩帷幕灌浆积累了经验,可供同类大型工程帷幕灌浆时参考.     

氧输送管路动态水试仿真分析

利用AMESim软件针对某型运载火箭氧输送管水试试验进行仿真分析,建立无蓄压器和带蓄压器试验系统仿真模型,模拟试验过程中的主要压力变化,并利用软件自带的FFT变换(快速傅立叶变换)获取管路在与水介质耦合作用下的一阶频率和二阶频率。通过对比分析发现,仿真结果与试验结果比较吻合,验证了仿真模型的有效性。     

A modified solution of radial subgrade modulus for a circular tunnel in elastic ground

In models based on Winkler springs for tunnel lining design, designers always face the difficulty of selecting appropriate values for the radial subgrade modulus (k_r). The widely used solution k_r for a circular tunnel in elastic ground proposed by Wood (1975) was found to be applicable only when the tunnel radial deformation is oval-shaped. On the basis of the Wood׳s solution, this note presents a general solution for k_r when the radial deformation of the tunnel is described by a Fourier series. This modified Wood׳s solution of k_r using compatible stress functions is validated by a numerical example. The modified solution for the example shows good consistency with the original Wood׳s solution when the tunnel becomes an oval shape with deformations. The example indicates that the magnitude of k_r is significantly affected by the distribution shape of the tunnel radial deformation. The value of k_r is no longer a constant value around the tunnel when the tunnel deforms into a general shape described by a Fourier series. It is quite different from the value of k_r for a distribution shape described by a single Fourier term, i.e. one involving a single frequency. The application of a general solution for k_r is illustrated by a design case using a bedded beam model.     

A new design equation for drained stability of conical slopes in cohesive-frictional soils

New plasticity solutions to the drained stability of conical slopes in homogeneous cohesive-frictional soils were investigated by axisymmetric finite element limit analysis. Three parameters were studied, i.e. excavated height ratios, slope inclination angles, and soil friction angles. The influences of these parameters on the stability factor and predicted failure mechanism of conical slopes were discussed. A new design equation developed from a nonlinear regression of the lower bound solution was proposed for drained stability analyses of a conical slope in practice. Numerical examples were given to demonstrate a practical application of the proposed equation to stability evaluations of conical slopes with both associated and non-associated flow rules.