锥形封头压力试验下应力校核问题的探讨

通过对比分析GB/T 150与ASME压力试验时的压力最低取值以及受压元件应力校核的方法,并结合锥形封头承压下不同位置的应力情况,指出了目前主流计算软件在锥壳应力校核上的不足,提出了锥形封头压力试验下应力校核的方法,避免了工程上因漏算带来的风险.     

压力容器新型封头的应力分析

通过对新型封头及标准椭圆形封头所进行的有限元应力计算和应力测试，对两种封头的应力状况进行了分析，进而提出了新型封头适宜的设计公式。     

全拉应力凸形封头

介绍内压作用下,薄膜应力处处为拉应力的凸形封头的设计方法。并给出周向应力与径向应力比值(以下简称应力比)为线性变化时的封头形状。这种封头的曲率半径是连续变化的,没有几何形状与应力的突变。     

反应釜封头部位大开孔接管应力分析与强度校核

采用有限元软件ABAQUS建立某反应釜封头部位大开孔接管有限元模型进行应力分析,并用线性分析法进行强度校核。结果表明:应力最大值发生在接管与封头外壁面相贯处;设计压力条件下应力均满足强度要求。     

基于ANSYS的高压容器简体与封头的连接区的应力分析

由于高压容器筒体与封头的连接区的不连续，往往导致不连续区局部应力集中，而且结构较为复杂，很难用解析法进行精确求解。采用有限元分析软件ANSYS对高压容器筒体与封头的连接区进行了应力分析，从而为压力容器不连续区应力分析提供了一种合理的方法和依据。     

锥形封头的应力分析

本文采用电测法,通过对锥形封头和与封头相连接的部分圆筒体的应力分布进行实验测定,绘出了应力分布曲线图,由于锥形封头和筒体两部分连接处曲率不同,受压后,在连接处会产生边缘力系—边缘力矩和边缘剪力,使得折边区及其两侧一定距离内的筒体和封头中的应力分布比较复杂,某些位置会出现较高的局部应力等重要的结论。     

加氢反应器封头引出管管口载荷引起的局部应力的校核

加氢反应器上封头或下封头引出管的结构,因其结构的特殊性,对此类开口接管的管口载荷所引起的局部应力如何计算,国内外标准均无相应的规定.采用理论公式推导和工程设计相结合的方法,对该管口载荷对引出管各部位产生的应力进行了详细的分析和推导,给出了各部位应力的计算和校核公式,并采用工程设计实例进行了说明.文中所给的计算和校核公式...     

外压锥形封头设计和开孔处的应力强度

本文对外压锥形封头设计以及开孔接管处的应力强度等两个问题进行分析。     

考虑温度影响的平盖加筋封头结构应力强度分析

对某加热器的平盖加筋封头考虑其既受热又受内压的情况,运用有限元分析软件ANSYS对其在两种载荷下分别单独进行应力强度分析,并重点介绍了热应力分析方法。运用ANSYS耦合分析功能,在两种载荷同时作用下对平盖加筋封头结构进行应力强度分析。分析了温度载荷对平盖加筋封头结构应力强度的影响。     

Proof of ether-bridged condensation products in UF resins by 2D NMR spectroscopy

The existence of ether-bridged condensation products in urea-formaldehyde (UF) resins is still disputed in the literature as these products have never been isolated or fully characterized. Using ¹H-¹⁵N gradient heteronuclear single quantum correlation (gHSQC) experiment, ¹H-¹³C gHSQC experiment and ¹H-¹³C gradient heteronuclear multiple bond correlation (gHMBC) experiment a, methylolurea hemiformal compound (urea compound with oligomeric chains $-\rm{CH}_{2}\;{\rm O[CH}_{2}{\rm O]}{\mathrm {n}}{\rm H}$ and $n\geq 1$ ) and a symmetrical compound, most likely an ether-bridged condensation product, in a UF resin sample were characterized. The results were confirmed by 2D NMR ¹³C-¹³C gradient correlated spectroscopy (gCOSY) experiment using ¹³C labeled ureaformaldehyde samples. Spectroscopic chemical shifts of the proposed ether-bridged condensation product in ¹⁵N, ¹³C, ¹H NMR spectroscopy were assigned. Furthermore, individual peak assignments are provided for the methylolurea hemiformal moiety.     

钻孔应力释放法应用于筒体校形后残余应力的测量

通过对产生较大椭圆度筒体的校形,运用钻孔应力释放法测量筒体中残余应力的大小,证明了筒节校形前后残余应力变化不大,附加残余应力只是筒体母材屈服强度的0.45%,从而确定筒体校形后不需要重新进行消应力的热处理。     

Direct Proof of Ingested Food Regurgitation by Spodoptera littoralis Caterpillars during Feeding on Arabidopsis

Oral secretions of herbivorous lepidopteran larvae contain a mixture of saliva and regurgitant from the insect gut. Different compounds from the oral secretions can be recognized by the host plants and, thus, represent elicitors that induce plant defenses against feeding herbivores. Exogenously applied oral secretions can initiate the biosynthesis of jasmonates, phytohormones involved in the regulation of plant defense. However, it is not known (a) whether or not non-manipulated insects indeed release oral secretions including gut-derived compounds into a leaf wound during the natural feeding process, or (b) whether they adjust the release of gut components to the state of plant defense. We addressed these questions by using Arabidopsis thaliana as host plant and larvae of the generalist herbivorous insect Spodoptera littoralis. We investigated the conversion of the plant-derived jasmonate precursor, cis-12-oxophytodienoic acid (cis-OPDA), to iso-OPDA by the larvae. This enzymatic reaction is mediated by a specific glutathione-S-transferase in the insect gut, but not in the plant. Any presence of iso-OPDA in plant tissue, thus, indicated that gut content had been regurgitated into the plant wound. Our study demonstrates that the plant is the only source for the substrate cis-OPDA by using aos (allene oxide synthase) mutants that are unable to synthesize OPDA. The fact that iso-OPDA accumulated over time on feeding-damaged leaves shows that the feeding larvae are constantly regurgitating on leaves. Although the larvae provided the signaling compounds that were recognized by the plant and elicited defense reactions, the larval regurgitation behavior did not depend on whether they fed on a defensive wild type plant or on a non defensive coi1-16 plant. This suggests that S. littoralis larvae do not adjust regurgitation to the state of plant defense.     

Optimum design parameters of a squash head projectile

This note first establishes a correlation between post impact fuze delay and the spread of explosives of a squash head gun-fired projectile when hitting a rigid non-yielding plate. Estimations of optimum strike velocity and fuze delay to maximize spread are derived.     

论手机短信的证据效力

作为一种新兴的信息承载方式,手机短信以新型证据的身份闯进了诉讼程序,司法实践中以手机短信作为证据的案件不断涌现,对于手机短信在证据理论和实务上如何定位,也成为亟待解决的问题。本文拟对手机短信的证据效力问题进行初步的探索,以期引起更多学者的注意。     

防霉抗菌问题概述

该文根据生物科学资料介绍细菌和霉菌的一些基本构造和特性,对常见霉腐微生物的繁殖条件做了概叙,最后对防霉抗菌问题研究的状况做了分析.     

Direct Proof of Volatile and Adsorbed Hydrocarbons on Solid Catalysts by Complementary NMR Methods

In this paper, both volatile and strongly adsorbed products of heavy hydrocarbon conversion on a zeolite were investigated by gas-phase and solid-state NMR. For this purpose, the reactions were carried out in sealed glass tubes under vacuum to collect the volatile reaction products. This procedure is demonstrated for pure 2-ethylphenol conversion on ultra-stabilized zeolite Y leading to both the formation of light alkanes and deoxygenation products. The above-mentioned method is useful to improve the understanding of heavy hydrocarbon conversion under batch conditions.     

基于CFD技术优化乳化头转子结构

应用SolidWorks Flow Simulation对一款乳化头4个不同转子结构进行了CFD分析,通过仿真计算,直观地获得了釜内不同乳化头周围的流体速度分布云图和流线轨迹;通过粒子示踪法,模拟了制胶物料在乳化头作用下的分布状态;最后在乳化头出料口外定距设定一草绘面获取该面上的平均速度,以定量预测对比不同转子结构的乳化效果。通过CFD分析,可从4个方案中选择最佳结构,达到优化转子的目的。