非对称碰撞约束下形状记忆合金梁的随机响应与分岔

形状记忆合金(SMA)是二十一世纪具有形状记忆效应的新型智能材料.针对具有非对称约束的SMA梁,本文构造了碰撞振动系统.在无碰撞和有碰撞两种情况下,利用随机平均法给出了近似解析结果.数值模拟作为验证解析结果的工具.结果表明,系统能量的概率响应曲线具有非光滑特性.当约束位置发生变化时,系统会出现随机P分岔和D分岔.     

企业管理创新应与经营机制转换同步

针对企业经营机制转换过程中存在的“以转代管”、轻视管理创新的时弊,通过企业管理与经营机制内在关系的研究,提出了转换经营机制要以强化企业管理为依托、管理创新应与机制转换同步的企业改革思路。结合铁法矿务局管理创新实践,阐述了目前按市场机制要求需在企业管理中改革创新的主要方面。     

睡莲科植物酯酶同功酶的数量分类研究

采用垂直平板聚丙烯酰胺凝胶盘状电泳技术,对国内睡莲科植物（包括６个属的６个代表种及３个品种）的叶片进行了酯酶同功酶的测定,初步结果表明被测植物均有各自稳定的酯酶酶谱．运用数量分类学方法对被测植物进行聚类,其中白睡莲与其派生的红睡莲和黄睡莲２品种聚为一类,南芡与北芡亦聚为一类,而此２类与萍蓬草、莲、莼菜和王莲的亲缘关系较远,且后４种植物之间亲缘关系亦远．该结果与由过氧化物同功酶酶谱的分析结果基本相似．     

Fuzzy复数的Fuzzy运算

复数ａ＋ｂｉ和二无数对（ａ,ｂ）可建立一对应关系,对定义在复数域上的Ｆｕｚｚｙ集的研究可转化为欧氏空间Ｒ２上的Ｆｕｚｚｙ集的研究,假定,本文中研究了Ｆｕｚｚｙ复数的加法和乘法运算,对已有的有关结果进行了改进。     

Shock waves and turbulence in a hypersonic inlet

A numerical investigation for an axisymmetric hypersonic turbulent inlet flow field of a perfect gas is presented for a three-shock configuration consisting of a biconic and a cowl. An upwind parabolized Navier-Stokes solver based on Roe's scheme is used to compute an oncoming flow Mach numberM =8, temperatureT =216 K, and pressureP =5.5293×10³ N/m². In order to assess the flow quantities, the interaction between shock and turbulence, and the inlet efficiency, three different flow calculations — laminar, turbulent with incompressible and compressible two-equationk- turbulence models — have been performed in this work.Computational results show that turbulence is markedly enhanced across an oblique shock with step-like increases in turbulence kinetic energy and dissipation rate. This enhancement is at the expense of the mean kinetic energy of the flow. Therefore, the velocity behind the shock is smaller in turbulent flow and hence the shock becomes stronger. The entropy increase through a shock is caused not only by the amplification of random molecular motion, but also by the enhancement of the chaotic turbulent flow motion. However, only the compressiblek- turbulence model can properly predict a decrease in turbulence length scale across a shock. Our numerical simulation reveals that the incompressiblek- turbulence model exaggerates the interaction between shock and turbulence with turbulence kinetic energy and dissipation rate remaining high and almost undissipated far beyond the shock region. It is shown that proper modeling of turbulence is essential for a realistic prediction of hypersonic inlet flowfield. The performed study shows that the viscous effect is not restricted in the boundary layer but extends into the main flow behind a shock wave. The loss of the available energy in the inlet performance therefore needs to be determined from the shock-turbulence interaction. The present study predicts that the inlet efficiency becomes relatively lower when turbulence is taken into account.     

Independent sets,cliques and hamiltonian graphs

LetG be ak-connected (k 2) graph onn vertices. LetS be an independent set ofG. S is called essential if there exist two distinct vertices inS which have a common neighbor inG. LetV _r, be a clique which is a complete subgraph ofG. In this paper it is proven that if every essential independent setS ofk + 1 vertices satisfiesS V _r , thenG is hamiltonian, orG{u} is hamiltonian for someu V _r, orG is one of three classes of exceptional graphs. Our theorem generalizes several well-known theorems.