简述改进屋顶水箱附件设置及安装的技术措施

本文介绍了屋顶水箱附件设置、安装的基本要求,总结出一些改善水箱有效运行、方便维护检修、防止水质污染、防止噪音的技术措施。     

Tube joining by asymmetric plastic instability

This paper explores inclined, out-of-plane, plastic instability waves in thin-walled tubes subjected to axial compression and the factors affecting its development and propagation. Explanations are given for the experimental observations and finite element predictions of plastic flow and compression load in a wide range of process parameters. Basic design guidelines are provided, making use of plastic instability waves to produce tube attachments in situations where the axis of the branch tube is inclined to the axis of the main body tube.The overall content of the paper widens and enhances previous work published by the authors in perpendicular tube attachments by providing a complete characterization of the process feasibility window for inclined tube attachments. The new developments in asymmetric plastic instability are a step forward in tube joining because their offer an effective and environmentally friendly solution for producing complex tube attachments in situations where there are little or no-alternatives of utilizing conventional processes involving welding and brazing.     

Status of ITER blanket attachment design and related R&D

Main function of the ITER blanket system [1], [2], [3] is to shield the vacuum vessel (VV) from nuclear radiation and thermal energy coming from the plasma. Blanket system consists of discrete blanket modules (BM). Each BM is composed of a first wall panel and a shield block (SB). The shield block is attached to the VV by means of four flexible supports and three or four shear keys, through key pads. All listed supports do have parts with ceramic electro-insulating coatings necessary to exclude the largest loops of eddy currents and restrict EM loads. Electrical connection of each SB to the VV is through two elastic electrical straps. Cooling water is supplied to each BM by one coaxial water connector. This paper summarizes the recent evolution of the blanket attachment system toward design solutions compatible with design loads and numbers of load cycles, and providing sufficient reliability and durability. This evolution was done in a frame of pre-defined external interfaces. The ongoing supporting R&D is also briefly described.     

固定式端面弧齿联轴节的加工方法

为了在国产数控螺旋锥齿轮加工机床上实现端面弧齿联轴节的加工,对固定式端面弧齿联轴节的加工方法进行了研究。分析了端面弧齿联轴节的切齿原理和切齿方法,根据固定式端面弧齿联轴节的调整计算卡,建立了刀盘半径、刀齿顶宽、切削刃压力角、刀尖圆角半径的计算方法。基于端面弧齿联轴节的切齿原理以及国产数控螺旋锥齿轮加工机床的结构,建立了弧齿联轴节切齿加工机床调整参数的计算方法,给出了相关的计算公式并开发了端面弧齿联轴节设计、加工参数计算软件。在国产H350G型数控螺旋锥齿轮磨齿机上,基于软件计算得到的机床调整参数进行了实际的磨齿加工,通过实际的接触区检测和几何参数检测,验证了切齿加工参数计算方法的正确性。     

最小曲率法的再认识及其应用

在使用最小曲率法推导有关公式的过程中,涉及了大量的三角函数变换,过程有时很复杂,极易出现错误。为了解决这个问题,分析了井眼轨迹切线与井斜角和方位角之间的数学关系,利用井眼方向矢量给出了最小曲率法的矢量形式。这种矢量形式深刻地揭示了圆弧井段弯曲角、井眼曲率、坐标增量、井斜角和方位角之间的关系的数学实质,具有形式简洁和几何直观性。使用矢量形式的最小曲率法对井眼轨迹内插、完钻井段设计等问题进行了研究。结果表明,有关公式的推导过程非常简单,完全避免了复杂的三角函数变换,而且最终得到了计算公式更加简单。同时,还用实际算例进行了验算,证实了本文新公式的正确性。本文提出的矢量形式的最小曲率法新公式可以应用于与圆弧井段有关的井眼轨迹设计和计算问题中。     

改进的BA 网络演化模型的研究及应用

利用主方程和连续域理论分析了BA无标度网络的度分布以及初始吸引因子对网络节点度分布的演化过程。对BA模型进行了改进和推广,提出了随机吸引因子网络演化模型。此网络演化模型通过理论分析和数值模拟验证是吻合的,该模型是无标度网络演化模型。实验结果表明,改进的模型能够很好地反映现实系统中的一些重要性质,具有实际应用价值。     

水布垭面板堆石坝面板附着物成分及成因分析

为了确保水布垭面板堆石坝工程的长效安全运行,对库水水质、面板附着物的成分和成因以及面板混凝土的强度状况进行研究,在此基础上开展库水和附着物对面板混凝土的腐蚀性评价。研究结果表明:库水对面板混凝土和钢筋均无腐蚀;面板混凝土上的附着物主要成分为方解石和石英,其对面板混凝土基本没有腐蚀性;面板混凝土的强度损失较小,面板运行状况良好。从工程美观和长效安全角度考虑,建议对面板上的附着物进行定期铲除清理。     

Degradation phenomena of magnetic attachments used clinically in the oral environment

The purpose of this study was to investigate the mechanisms involved in the failure of magnetic attachments used to retain dental prostheses. Dyna magnets were retrieved from dentures that had failed after 34 months of clinical use. These magnetic attachments were prepared and sectioned so as to observe the corrosion surface and layer in order to analyze the corrosion behaviors of the attachments. The corroded surface was observed under a field emission scanning electron microscope (FE-SEM) (JSM 840A, JEOL, Japan). An X-ray diffractometer (XRD) was used to analyze the corrosion product formed due to corrosion in the oral environment. Erosion-corrosion started in the uneven portion of the stainless steel cover in the magnetic attachments composed with Nd−Fe−B alloy. Corrosion was initiated on the worn stainless steel surface, followed by spalling of magnetic material due to corrosive solution. The corrosion rate increased drastically after the corrosion product caused spalling in Nd−Fe−B alloy. Corrosion initiated in the uneven stainless steel surface as well as in the welded zone. In conclusion, the failure of magnetic attachments may occur by either welding failure or breakdown of the encapsulating material. Thus, we believe that treating the surface of magnetic attachments would resolve the corrosion problem seen in magnetic attachments to some extent.     

基于Spring上传大附件应用系统的研究

上传附件是大部分应用系统必备的功能,现在已经有很多种实现方法,但是一般存在上传附件小,上传速度慢等问题,不能很好的满足用户的需求,上传附件成了开发过程当中较为重要也较困难的一个环节。通过J2EE开发环境的搭建及使用Spring组件进行开发出的上传附件功能,解决了当前附件上传的问题,而且开发方便快捷,为程序员提供了一种可选择的开发方案,通过详细的开发过程描述,方便掌握该开发方法,有利于程序开发的顺利进行。     

端面齿啮合段的弯曲刚度特性研究

针对端面齿的存在会引起燃气轮机转子结构轴向不连续的现象,应用端面齿啮合段的弯曲刚度分析方法和三维有限元法建立非线性接触分析模型,计算了不同预紧力作用下端面齿啮合段的弯曲刚度,提出了整体转子结构的弯曲刚度修正系数,并分析了关键几何结构参数对端面齿啮合段弯曲刚度修正系数的影响.结果表明:预紧力大于由弯矩引起的脱开力是保持端面齿啮合段弯曲刚度稳定的条件;端面齿内直径和外直径对弯曲刚度修正系数的影响甚微,而齿数的增加会减小弯曲刚度修正系数.