制氢转化炉管局部红管的原因分析及措施

针对制氢装置原料波动后出现转化炉管局部红管现象,分析产生红管的各种因素,结果表明由于积碳和轻微硫氯中毒而引起红管,采用缓和的烧碳方法,降低负荷,增大水碳比,最终达到预期效果。     

A shear deformable theory for the analysis of steel beams reinforced with GFRP plates

A shear deformable thin-walled beam theory is developed for the analysis of steel beams reinforced with a GFRP plate to one of the flanges. Starting with the principle of stationary potential energy, the governing equilibrium equations and boundary conditions are formulated for the problem. The theory results in two sets of fully coupled systems of equilibrium equations. The first system describes the longitudinal-flexural response of the system and involves four generalized displacement fields and the second system governs the lateral-torsional response and involves six generalized displacement fields. The resulting coupled systems are then solved numerically for practical problems. Detailed comparisons with three dimensional and shell solutions under ABAQUS show that the present theory provides reliable predictions for displacements and stresses. A comparison with results from a non-shear deformable theory illustrates the necessity of incorporating shear deformation effects in cases involving predominantly twisting responses.     

谈供热直埋热水管道摩擦力的计算

通过对新旧规程中供热直埋热水管道摩擦力的计算分析,得出同条件下新规程单长摩擦力减小了很多,且考虑了地下水位对管道摩擦力的影响,指出摩擦力的变化直接影响到管道过渡段长度、自由端热伸长以及补偿器的选择等,其计算数据关系到管网的安全运行,具有重要的实用价值。     

多峰函数优化的黄金分割斐波那契树优化算法

针对多峰函数优化问题，基于斐波那契树优化算法，结合黄金分割思想，提出一种黄金分割斐波那契树优化算法.该算法利用斐波那契树优化算法全局局部交替寻优特性，通过在寻优过程中对优化问题解空间进行黄金分割比例压缩，从而提高算法局部搜索能力与小峰值搜索能力.多峰函数优化的仿真结果表明，该算法多峰优化能力强、速度快、精度高.     

现代有轨电车横穿高速公路纵断面方案比较

对现代有轨电车线路沿道路横穿高速公路节点进行了分析,根据设计规范提出了包括地面线方案、普通高架线方案和坡度优化高架线方案在内的三种纵断面方案,解决了公路与高架道路交叉节点线路设计问题。     

Failure analysis on abnormal wall thinning of heat-transfer titanium tubes of condensers in nuclear power plant Part I: Corrosion and wear

Titanium tubes used in condensers in a nuclear power plant in China encountered abnormal wall thinning, and was thus forced to temporarily stop operation or it could bring about catastrophic safety problems. Most of the wall thinning happened at quite regular positions on the tubes and these failure tubes were located similarly in the condensers, indicating some common problems. To find out the root cause and mechanism of the thinning failure, we conducted surface deposit analysis, appearance inspection, microstructure analysis and composition analysis of the samples by means of X-ray diffraction (XRD), stereo microscope, scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS). The results revealed that the wall thinning was primarily caused by eccentric contact wear and three-body contact wear rooted in processing defect of internal borings, corrosion products deposit and sagging, and foreign particles. Finally, countermeasures were proposed for repair and prevention.     

Star graph automorphisms and disjoint Hamilton cycles

The search for edge-disjoint Hamilton cycles in star graphs is important for the design of interconnection network topologies. We define automorphisms for star graphs St _n of degree n?1, for every positive odd integer n, which yield permutations of labels for the edges of St _n taken from the set of integers between 1 and ? n/2 ?. By decomposing these permutations into permutation cycles, we are able to identify edge-disjoint Hamilton cycles that are automorphic images of a known Hamilton cycle in St _n . Our method produces a better than two-fold improvement from ? ? (n)/10 ? to ? 2? (n)/9 ?, where ? is the Euler function, for the known number of edge-disjoint Hamilton cycles in St _n for all odd integers n. For prime n, the improvement is from ? n/8 ? to ? n/5 ?, and we can extend this result to the case when n is the power of a prime greater than 7.     

烟管与管板连接结构的焊接残余应力数值模拟

为了研究烟管与管板连接处环向裂纹产生的原因,文章基于ANSYS软件中的APDL语言、单元生死技术以及热-结构间接耦合法对烟管与管板焊接结构的焊接温度场、应力场进行了三维数值模拟,获得了焊接残余应力的大小与分布规律,并对模拟结果进行了详细讨论.模拟结果表明：在焊缝区环向应力较大,容易造成焊缝环向开裂而失效;相邻焊缝的焊接对环向焊接残余应力大小与分布规律影响显著.     

Blade sections for wind turbine and tidal current turbine applications–current status and future challenges

The designers of horizontal axis wind turbines and tidal current turbines are increasingly focusing their attention on the design of blade sections appropriate for specific applications. In modern large wind turbines, the blade tip is designed using a thin airfoil for high lift : drag ratio, and the root region is designed using a thick version of the same airfoil for structural support. A high lift to drag ratio is a generally accepted requirement; however, although a reduction in the drag coefficient directly contributes to a higher aerodynamic efficiency, an increase in the lift coefficient does not have a significant contribution to the torque, as it is only a small component of lift that increases the tangential force while the larger component increases the thrust, necessitating an optimization. An airfoil with a curvature close to the leading edge that contributes more to the rotation will be a good choice; however, it is still a challenge to design such an airfoil. The design of special purpose airfoils started with LS and SERI airfoils, which are followed by many series of airfoils, including the new CAS airfoils. After nearly two decades of extensive research, a number of airfoils are available; however, majority of them are thick airfoils as the strength is still a major concern. Many of these still show deterioration in performance with leading edge contamination. Similarly, a change in the freestream turbulence level affects the performance of the blade. A number of active and passive flow control devices have been proposed and tested to improve the performance of blades/turbines. The structural requirements for tidal current turbines tend to lead to thicker sections, particularly near the root, which will cause a higher drag coefficient. A bigger challenge in the design of blades for these turbines is to avoid cavitation (which also leads to thicker sections) and still obtain an acceptably high lift coefficient. Another challenge for the designers is to design blades that give consistent output at varying flow conditions with a simple control system. The performance of a rotating blade may be significantly different from a non‐rotating blade, which requires that the design process should continue till the blade is tested under different operating conditions. Copyright © 2012 John Wiley & Sons, Ltd.