Self-Dual Yang-Mills Theory as a Two-Dimensional Chiral Model and Its Conservation Laws

The self-dual Yang-Mills field theories in two-dimensional representations are formulated. The Biicklund transformation and the conservation law are given in the framework of the prolongation theory. Furthermore, we derive the conserved current algebras which are in essence the Yang-Baxter relations.     

NUMERICAL STUDIES OF TRANSITIONAL TURBULENT PULSATILE FLOW IN PIPES WITH RING–TYPE CONSTRICTIONS

Pulsatile flows in the vicinity of mechanical ring-type constrictions in pipes were studied for transitional turbulent flow with a Reynolds number (Re) of the order of 10⁴. The Womersley number (Nw) is in the range 30–50, with a corresponding Strouhal number (St) range of 0·0143–0·0398. The pulsatile flows considered are a pure sinusoidal flow, a physiological flow and an experimental pulsatile flow profile for mechanical aortic valve flow simulations. Transitional laminar and turbulent flow characteristics in an alternating manner within the pulsatile flow fields were studied numerically. It was observed that fluid accelerations tend to suppress the development of flow disturbances. All the instantaneous maximum values of turbulent kinetic energy, turbulent viscosity and turbulent shear stress are smaller during the acceleration phase than during the deceleration period. Various parametric equations have been formulated through numerical experimentation to better describe the relationships between the instantaneous flow rate (Q), the pressure loss (ΔP), the maximum velocity (V_max), the maximum vorticity (ζ_max), the maximum wall vorticity (ζ_w,max), the maximum shear stress (τ_max) and the maximum wall shear stress (τ_w,max) for turbulent pulsatile flow in the vicinity of constrictions in the vascular tube. An elliptic relationship has been found to exist between the instantaneous flow rate and the instantaneous pressure gradient. Other linear and quadratic relations between various flow parameters were also obtained.     

FINITE ELEMENT SOLUTIONS OF LAMINAR AND TURBULENT MIXED CONVECTION IN A DRIVEN CAVITY

This paper presents laminar and turbulent mixed convection solutions of a driven cavity flow using the finite element method. For the laminar flow, distributions of velocity and temperature with and without the effect of buoyancy force are presented and compared. For the turbulent flow, governing partial differential equations of the thermal turbulence two-equati on model and kinetic turbulence two-equation model are used. Corresponding results such as kinetic eddy diffusivity, kinetic eddy energy, thermal eddy energy and their dissipations are presented.     

Dynamically selective multiwavelength cross-connect based on fibre Bragg gratings and mechanical optical switches

A dynamically selective multiwavelength cross-connect for wavelength division multiplexed (WDM) networks based on fibre Bragg gratings (FBGs) and optical switches is reported. Dynamically single- or multi-channel cross-connect functionality can be realized according to control of the optical switches and the FBGs' arrangement. Bit-error-rate performance with negligible power penalty is achieved in a 2.5Gbs-1x3 WDM channels over 100km conventional single-mode fibre (SMF) network demonstration. The characteristics of low channel crosstalk, uniform channel loss, high scalability and cascadability, and low cost of this device could provide more reconfiguration flexibility and network survivability for WDM networks.     

磁场逐渐增强的摇摆器

研究了用磁场增强摇摆器来提高自由电子激光器效率的机制．采用KMR方程，考虑空间电荷效应，模拟计算发现自由电子激光器的效率有了很大的提高，而且电子束能散度越大，对提高自由电子激光器效率越有帮助．因此采用磁场增强摇摆器能充分利用加速器的能量来莸得更高的自由电子激光器能量 关键词：     

DYNAMIC ANALYSIS OF AN AUTOMATIC WASHING MACHINE WITH A HYDRAULIC BALANCER

A mathematical model of a hydraulic balancer in steady state condition was derived from a whirling model of a vertical axis washing machine, with the aim of implementing a dynamic analysis of an automatic washing machine during spin drying mode. The centrifugal force acting on the hydraulic balancer depends on the centroidal distance of the fluid in the hydraulic balancer, and the centroidal distance is a function of an eccentricity of the geometric center of the hydraulic balancer from the axis of rotation. A mathematical model of the hydraulic balancer in steady state is validated by the experimental result of the centrifugal force. Experiments were performed on a washing machine during spin drying mode, and results were compared with the simulation result. The parameters affecting the vibration of the washing machine were investigated by the parameter study.     

Syntheses of Iso-Condensed Heteroaromatic Pyrroles and the Application to the Total Synthese of Natural Products

A novel method, namely the intramolecular 1,3-dipolar cycloaddition and cycloreversion ofazido-alkylidene malonates, for the preparation of iso-condensed heteroaromatic pyrroles has beendeveloped. The application of this method for the synthesis of 2,4-dihydropyrrolo[3,4-b]indole ringsystem, as well as the application of this ring system for the total syntheses of ellipticine alkaloids arereported.     

单晶硅中硅氢键和氢致缺陷的电子自旋共振研究

本文先后用光致发光、核磁共振和电子自旋共振研究了单晶硅中硅氢键和氢致缺陷的性质。光致发光谱表明硅氢键引起了大量非辐射中心。观测和探讨了电子自旋共振测量与样品平均厚度的关系。本文克服了真空热处理中氢从表面扩散的困难,并避免了样品平均厚度大于1.00mm和小于0.85mm给电子自旋共振带来的困难,测得分别在纯氢气氛和氩气氛生长的单晶硅每立方厘米电子自旋数。对比二者,我们估算出氢的数量为4×10¹⁶/cm³,而硅氢键分离激活能约为0.1eV。前者与文献[6]和[10]符合得很好,后者比文献[11]测定的沉淀激活能低一个数量级。 关键词：     

Optical Image Combination and Logic AND Operation Using Beam Fanning Effect

Using the beam fanning effect in a BaTiO₃ crystal, we propose two simple set-ups to perform the function of an optical image combiner and an optical AND gate respectively. The optical image combiner combines two mutually coherent as well as mutually incoherent patterns transmitted to it separately into a single coherent pattern. This set-up can also be used as an optical OR gate. For the AND gate, the two input signals may also be mutually coherent or incoherent. Experimental results showed the response time of these two devices to range from 0.01 second to 2.5 seconds.     

The forgotten liquid crystals of Daniel Vorlander: A new look at mesogenic 4-pyridones

Three classes of 4-pyridone (1H-pyridin-4-one) terminated liquid crystals were synthesized and their mesogenic properties examined. These liquid crystal classes differ in the composition of the aromatic core group which vary among azobenzene, stilbene or tolane groups. The synthesis of the 4-pyridones was accomplished by aromatic nucleophilic substitution reaction of the appropriate activated aryl fluoride with 4-hydroxypyridine. These pyridone liquid crystals possess broad enantiotropic nematic and smectic A phases and may possess useful properties such as high birefringence and polarity including hydrogen bonding capability. The original report of a 4-pyridone containing liquid crystal due to Vorlander has been substantiated.