混凝土骨料二维分布的模拟和应用

通过在一个矩形截面上模拟混凝土骨料的实际分布，获得了该截面上任一点的骨料分布密度和骨料分布的统计特性。模拟结果表明，当模拟次数趋向于无穷大时，截面上任一点的骨料分布密度趋向于定值，对于不同的骨料面积百分数，骨料分布密度曲线的形状十分相似，均由上升段和水平段两部分组成。基于这些模拟结果，利用数学拟合获得了骨料分布密度的解析表达式，并被混凝土实验所初步证实。作为一个应用，本文计算了混凝土截面上各点的氯离子扩散系数。     

结构-波浪-海床耦合系统中大圆筒结构的波压力响应

以沉入式大圆筒结构为对象，通过设计随机波浪水槽实验，测取了在单筒和连续筒两种结构型式、两种沉入深度和两种波谱输入下结构表面的动波压力分布。波面高度以及波压力历程均在领域进行分析。通过计算结构表面沿高程和沿环向的波压力谱及波压力传递函数，将单筒实测结果与基于线性绕射理论的解析解进行了比较，同时也详细对比了两种结构型式下的实测结果。文中汇报了在研究中获得的新发现及进行的相应分析，特别是在结构——波浪——海床动力相互作用下对波压力响应机理以及针对连续筒的研究，可为工程应用提供有价值的参考。     

固定式宽带无线接入技术--LMDS

本地多点分配业务(LMDS)是近年来在国际上兴起的固定式宽带无线接入技术,具有传输容量大、起始费用低的优点,受到了国内外电信业务经营者的普遍关注.文章介绍了LMDS提供的业务类型、工作频率、系统结构和标准化情况,并将LMDS与有线电视网络、ADSL、MMDS等现有的接入技术进行了比较.文章认为LMDS的商业推广尚需解决信号质量、服务区尺寸、费用等制约因素.     

A New Method for Target Recognition

1　Introduction　SinceZadeh[1] establishedfuzzysettheoryin 196 5 ,fuzzysetmakesgreatachievementintheoryandapplica tion[2～ 5] .Becausethereexistintrinsicfuzzinessinpat ternrecognition ,usingfuzzysettopatternrecognitionacquiregreatsuccess.Toexplainthedifferentandrela tionbetweenfuzzysetandprobabilitytheory ,Zadeh[6 ]introducedpossibilitytheoryin 1978.Possibilitytheoryhadbeenusedinfuzzyreason ,fuzzycontrolandexpertsystem[7～ 9] .Applingpossibilitytheoryto patternrecognitionisattemptedbyHalland…     

Tensile fracture and failure behavior of technical flax fibers

The apparent tensile strength of technical flax fibers was determined in single‐fiber tests at various clamping lengths (20, 40, and 80 mm) and the outcome was compared with literature data. It was demonstrated that the strength of flax at each clamping length obeyed the two‐parameter Weibull model. The failure mode and sequence were studied in situ (i.e., during loading) by SEM and acoustic emission (AE). The failure sequence (axial splitting of the technical fiber along its elementary constituents, radial cracking of the elementary fibers, multiple fracture of the elementary fibers) concluded reflected the hierarchical build‐up of the flax bast fibers. To the above failure events AE amplitude ranges were assigned. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3638–3645, 2003     

Dynamic stiffness vibration analysis using a high‐order beam model

This work presents the derivation of the exact dynamic stiffness matrix for a high‐order beam element. The terms are found directly from the solutions of the differential equations that describe the deformations of the cross‐section according to the high‐order theory, which include cubic variation of the axial displacements over the cross‐section of the beam. The model has six degrees of freedom at the two ends, one transverse displacement and two rotations, and the end forces are a shear force and two end moments. Using the dynamic stiffness matrix exact vibration frequencies for beams with various combinations of boundary conditions are tabulated and compared with results from the Bernoulli–Euler and Timoshenko beam models. Copyright © 2003 John Wiley & Sons, Ltd.     

Wake and aerodynamics loads in multiple bodies—application to turbomachinery blade rows

Two-dimensional, unsteady flow around bodies of complex geometry (or multiple bodies) at high Reynolds number is simulated using the vortex method. This method is modified to take into account the sub-grid scale phenomena through a second order velocity structure function model adapted to the Lagrangian scheme. The dynamics of the body wake is computed using the convection-diffusion splitting algorithm; the convection process is carried out with a Lagrangian Adams-Bashforth time-marching scheme and the diffusion process is simulated using the random walk method. The pressure distribution is obtained using an integral equation derived from the pressure Poisson equation, which was first developed for a single body. Results for the numerical simulation around a linear cascade of airfoils are presented. As the flow is periodic in the y direction, the discrete vortex shedding need only be considered for a reference airfoil. The flow characteristics around the NACA 65-410 series airfoils are calculated and comparisons are made with results available in the literature.     

变频调速技术在济钢焦化厂高压氨水泵上的应用

济钢焦化厂高压氨水泵变频调速系统采用变频器和PLC相结合的方式 ,具有调速精度高、节能等多种功能 ,保证氨水泵正常工作。全年可增加经济效益 77.3万元。     

Ф16mm、Ф18mm钼棒的研制

采用等静压制法，压制钼圆棒坯，经中频高温烧结，制得尺寸适合、用户满意的钼电极棒。     

推进石化销售企业质量管理创新发展

对照IS0 9001质量管理体系标推的要求，结合石化销售企业质量管理工作中存在的主要问题，提出质量管理工作创新的建议。