城市隧道给排水设计问题探讨

针对城市隧道给排水设计中经常会遇到的争议,结合相关规范和国内现状,对城市隧道分类、隧道消火栓、泵站设置类型、横截沟细部设计等问题,提出相应的设计思路。     

剪力墙体插座横向配管在工程中的应用

介绍了采用剪力墙体横向配管施工的特点和工艺原理，指出使用剪力墙体横向配管，避免了因管路堵塞造成的墙体的开槽及因管路堵塞后的整改，从而保证了工程质量，降低了劳动强度，提高了经济效益。     

连铸矫直过程板坯角部横向裂纹数值分析

 连铸过程中板坯角部可能出现横向裂纹，这些裂纹严重影响着连铸坯的质量和产量。本文采用显式动力学有限元方法对连铸矫直阶段连铸板坯表层金属应力变化规律进行了模拟，分析了角部应力的变化规律，并对矫直过程中连铸板坯应力分布对角部横向裂纹的影响进行了讨论。研究结果对指导连铸生产具有重要的实际意义和理论意义。     

J55套管钢铸坯角部横裂纹成因与防止措施

对马钢板坯铸机生产的 J55套管钢铸坯角部横裂纹成因与防止措施进行了探讨,并简述了相关试验情况。     

A semi‐analytical locally transversal linearization method for non‐linear dynamical systems

An numeric‐analytical, implicit and local linearization methodology, called the locally transversal linearization (LTL), is developed in the present paper for analyses and simulations of non‐linear oscillators. The LTL principle is based on deriving the locally linearized equations in such a way that the tangent space of the linearized equations transversally intersects that of the given non‐linear dynamical system at that particular point in the state space where the solution vector is sought. For purposes of numerical implementation, two different numerical schemes, namely LTL‐1 and LTL‐2 schemes, based on the LTL methodology are presented. Both LTL‐1 and LTL‐2 procedures finally reduce the given set of non‐linear ordinary differential equations (ODEs) to a set of transcendental algebraic equations valid over a short interval of time or over a short segment of the evolving trajectories as projected on the phase space. While in the LTL‐1 scheme the desired solution vector at a forward time point enters the linearized differential equations as an unknown parameter, in the LTL‐2 scheme a set of unknown residues enters the linearized system as parameters. A limited set of examples involving a few well‐known single‐degree‐of‐freedom (SDOF) non‐linear oscillators indicate that the LTL methodology is capable of accurately predicting many complicated non‐linear response patterns, including limit cycles, quasi‐periodic orbits and even strange attractors. Copyright © 2001 John Wiley & Sons, Ltd.     

Transversal thermal patterns in packed‐bed reactors with simple kinetics: Bifurcation criterion and simulations

We derive a new criterion for transversal instability of planar fronts based on the bifurcation condition dV_f/dK|_K=0 = 0, where V_f and K are the front velocity and its curvature, respectively. This refines our previously obtained condition, which was formulated as α = (ΔT_adPe_T)/(ΔT_mPe_C) > 1 to α > 1 + |δ|, where ΔT_ad and ΔT_m are the adiabatic and maximal temperature rise, respectively, Pe_C and Pe_T are the axial mass and the heat Pe numbers, respectively, and δ is a small parameter. The criterion is based on approximate relations for ΔT_m and V_f, which account for the local curvature of a propagating front in a packed bed reactor with a first‐order activated kinetics. The obtained relations are verified by linear stability analysis of planar fronts. Simulations of a simplified 2D model in the form of a thin cylindrical shell are in good agreement with the critical parameters predicted by dispersion relations. Three types of patterns were detected in simulations: “frozen” multiwave patterns, spinning waves, and complex rotating–oscillating patterns. We map bifurcation diagrams showing domains of different modes using the shell radius as the bifurcation parameter. The possible translation of the 2D cylindrical shell model results to the 3D case is discussed. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

外辐射源雷达多径杂波抑制的快速横向滤波算法

外辐射源雷达面临严重的多径杂波问题,传统的递归最小二乘(Recursive LeastSquare,RLS)算法能有效地抑制多径杂波,相对最小均方(Least Mean Square,LMS)算法而言,该算法收敛速率快,且不随输入相关矩阵特征值的扩散而改变,能获得更好的杂波抑制效果,但该算法复杂度高,不利于实时处理.针对此问题,提出了一种外辐射源雷达多径杂波抑制的快速横向滤波算法,该算法的计算量与LMS相当,同时具有RLS的优越性,对多径杂波抑制的实时处理更具有吸引力.仿真和实测数据处理结果验证了该算法的有效性.     

双曲率兜孔静音轴承保持架设计

传统深沟球轴承浪形保持架兜孔一般采用球形或椭球形结构,轴承在高速运转时滚动体不能充分润滑,存在噪声大、滚动体可能被划伤、使用寿命短等问题。文中在总结对比国内外保持架设计研究方法的基础上,以改善滚动体和保持架的润滑为目标,设计了一种具有双曲率兜孔结构的浪形保持架,分析了所设计保持架的减振降噪机理,最后通过测试验证了该结构能够有效地减振降噪,达到了静音轴承的标准。