Autorotation dynamics of a low aspect-ratio rectangular prism

This paper presents two previously unreported aspects of the autorotation dynamics of low aspect ratio rectangular prisms, observed during an experimental study of the dynamics of helicopter underslung loads. Low-speed wind tunnel tests of a simplified container model free to rotate on a fixed axis demonstrated (a) that autorotation rate can lock-in to a structural mode and (b) that static hysteresis in autorotation rate can occur at low speeds. Autorotation lock-in behaves in a similar manner to vortex-shedding lock-in, suggesting that a similar feedback flow process between vortex wake dynamics and body motion is operating, and may provide a partial explanation for the complex changes in behaviour of rotating slung loads at high airspeeds. Static hysteresis at low speeds results in a bifurcation diagram for autorotation which is similar to that for cross-wind galloping of a square prism, including the effects of friction and inertia. The similarity in bifurcation behaviour seems likely to indicate similar dynamics rather than flow physics, suggesting that it may be possible to apply techniques developed to model the effect of non-linear damping characteristics in galloping to the modelling of autorotation.     

ITER ���±��ⲿ�����Ľṹ�����Ӧ������

ITER低温泵需要定期再生循环以去除吸附的气体，处于安全考虑氢的累计体积摩尔浓度不能超过1.5mol?m?3，从而使得再生的容积必须不小于15m3，需要额外设计容器结构以提供足够的再生容积，同时兼顾支撑和密封的作用。介绍了ITER低温泵外部容器的结构与功能，并运用有限元分析方法对其不同载荷状况进行了数值计算，为其结构设计与优化提供了理论依据。     

A new multiobjective procedure for solving nonconvex environmental/economic power dispatch

In this article, an improved multiobjective chaotic interactive honey bee mating optimization (CIHBMO) is proposed to find the feasible optimal solution of the environmental/economic power dispatch problem with considering operational constraints of the generators. The three conflicting and noncommensurable: fuel cost, pollutant emissions, and system loss, should be minimized simultaneously while satisfying certain system constraints. To achieve a good design with different solutions in a multiobjective optimization problem, Pareto dominance concept is used to generate and sort the dominated and nondominated solutions. Also, fuzzy set theory is used to extract the best compromise solution. The propose method has been individually examined and applied to the standard Institute of Electrical and Electronics Engineers (IEEE) 30‐bus six generator, IEEE 180‐bus 14 generator and 40 generating unit (with valve point effect) test systems. The computational results reveal that the multiobjective CIHBMO algorithm has excellent convergence characteristics and is superior to other multiobjective optimization algorithms. Also, the result shows its great potential in handling the multiobjective problems in power systems. © 2014 Wiley Periodicals, Inc. Complexity 20: 47–62, 2014     

显微红外光谱在摩擦学中的应用

用显微红外光谱测定了羟基植物油脂肪酸在摩擦过程中生成聚酯的特征吸收峰υc^as-o-c的波数，由聚酯的折合质量分析了特征吸收峰υc^as-o-c的波数位移，据此导出了羟基植物油脂肪酸的抗磨性顺序规律与振动吸收峰位置的内在联系，合理解释了υc^as-o-c从小到大的顺序（13，14－二羟基廿二酸＜13（14）－羟基廿二酸＝9，10－二羟基十八酸＜9，10，12－三羟基十八酯＜9（10）－羟基十八酸）与羟基酸的抗磨性从好到差的顺序（13，14－二羟基廿二酸＞13（14）－羟基廿二酸＝9，10－二羟基十八酸＞9，10，12－羟基十八酸＞9（10）－羟基十八酸）的一致性。13，14－二羟基廿二酸形成网状取酯膜，9（10）－羟基十八酸形成线状聚酯膜。     

Bloch方程的解析解及其在水峰抑制和特形脉冲设计中的应用

用Laplace变换方法求出了Bloch方程在各种不同物理条件下的解析解,这些解析解物理图象清楚,便于分析,克服了数值解中的困难.解析解和相应的结论已用于水峰抑制和特形脉冲的设计.对于水峰抑制,本文指出抑制效果是有极限的,并给出了抑制效果的极限以及最佳抑制时间的近似计算公式.在特形脉冲的模拟过程中,我们发现只有同时考虑全部四类解析解,才能得到正确的模拟结果,另外,模拟还表明,要在保持激励频谱形状不变的条件下,得到不同倾倒角的脉冲必须改变激励脉冲的形状,相应实验的结果与我们给出的上述结论完全吻合。     

从单个混合时间的2D NOESY峰强度矩阵求取核间距

提出了从单个混合时间的2D NOESY峰强度或混合系数矩阵直接求取核间距的新方法。该方法分成二步进行。第一步采用规范化2D NOESY峰强度或对称化混合系数矩阵来计算对称化核交叉弛豫速率矩阵。其优点是计算过程简单且普适。第二步直接用对称化核交叉弛豫速率来求取核间距。该过程考虑到分子内部运动的贡献。本文方法是自治的,只要能测出单个混合时间的2D NOESY峰强度或混合系数矩阵即可直接求出自旋系统的核间距了。     

硅酸锶掺Er3+的高压合成及发光特性

 首次采用高压高温方法合成了Sr₂SiO₄:Er³⁺Bi³⁺和SrSiO₃:Er³⁺Bi³⁺发光材料，研究了合成压力、合成温度对发光特性的影响。与常压合成产物相比较，发光谱发生了红移；谱线半宽度显著增大；发光强度和量子发光效率下降。X射线衍射分析得出，SrSiO₃:Er³⁺Bi³⁺发生了结构相变，Sr₂SiO₄:Er³⁺Bi³⁺结构未变但晶格参数发生了变化，且主衍射峰强度发生了反转。分析表明，发光特性的变化是压致晶场、库仑及自旋-轨道相互作用的变化引起的。     

Control of Gear Vibrations at Their Source

Results are presented of study into the origin of spur gear vibrations and methods of reducing them at their source     

A New Method to Resolve Overlapped Voltammetric Peaks

A new method called spline convolution (SC) for resolving overlapped peaks was proposed in this paper. The differential pulse voltammetric overlapped peaks of mixtures of Pb(Ⅱ） and T1(I) were investigated by this method, and satisfactory results were obtained. The results show excellent correlation between peak areas of the processed signals and the concentrations.     

中细柔性圆环壳整体弯曲的一般解及在波纹管计算中的应用（I）—基本方程和一般解

讨论了圆环壳在横向载荷作用下的整体弯曲问题，提出了中细柔性圆环壳的概念、基本方程和一般解。本文称粗细比（子午线曲率半径与子午线曲率中心到回转轴的距离之比）小于1／3的圆环壳为中细圆环壳；方程的推导基于E.L.Axelrad的柔性壳理论；所得的解含有处理边界问题所必须的积分常数并且在全域内处处收敛；本解能方便地用于有关波纹管的计算。全文共分4个部分：（I）基本方程和一般妥；（Ⅱ）Ω型波纹管的计算；（Ⅲ）C型波纹管的计算；（Ⅳ）U型波纹管的计算。