NIR FT－Raman研究铝酸钠溶液的碳酸化过程

本文用ＮＩＲＦＴ－Ｒａｍａｎ光谱仪原位跟踪了铅酸钠溶液的碳酸化过程，观察到此过程的Ｒａｍａｎ光谱呈现振荡现象和非重线性，认为在碳酸化过程中，可能产生Ａｌ２（ＯＨ）离子和进一步缩聚形成的离子。     

端面附近缺陷在掺铒光纤中引起的振荡

实验研究了由于掺铒光纤（ＥＤＦ）端面附近存在缺陷引起光反射而导致的振荡，这种振荡发生在掺铒光纤放大的自发辐射（ＡＳＥ）谱的峰值波长处，由于较长掺铒光纤的放大的自发辐射谱近似于其小信号增益谱，因此也可以认为发生在掺铒光纤放大器（ＥＤＦＡ）的最大增益处，对其增益产生不良影响。     

轴对称磁场的数值问题

用现行的一次有限元解轴对称磁场时，在单元中心得到的磁感应强度会随径向格点作非物理的激烈振荡。我们分析了产生这种振荡的原因及其特性，并与网格的不均匀性引起的振荡作了比较。     

含剧烈振荡波函数积分J（n,X）的研究（Ⅱ）

在电子与原子（或离子）碰撞过程中，需要精确计算大量含剧烈振荡涵数的积分。把计算Ｊ（ｎ，Ｘ）的积分路径变到复平面上来研究含剧烈振荡波函数积分，不仅能计算相同波数或波数不同但相关较大的积分Ｊ（ｎ，Ｘ）而且能计算了“近简并”情形下的积分Ｊ（ｎ，Ｘ）。     

HL—1装置等离子体输运与锯齿特性的数值研究

本文利用一维圆柱等离子体输运编码（ＴＲＡＮＰＹ），编制了模拟锯齿振荡的大型编码（ＳＡＷＭＯＤ）。对锯齿振荡的研究，我们选用了两种具有代表性的理论模型：重联模型和湍流模型，后者特别适用于低ｑａ放电的锯齿特性研究。重联模型的锯齿振荡是由于磁力线的完全重联引起的，而湍流模型的锯齿振荡是因为微观湍流或磁力线的随机化而产生的。最后，我们将ＨＬ－１装置的一次典型高密放电的参数代入（ＳＡＷＭＯＤ）编码，运算结果     

变系数拉曼增益对两种特殊形式暗孤子传输特性的影响

在非均匀光纤中,基于带有分布色散,自相位调制和自陡峭的变系数修正非线性薛定谔方程(VcMNLSE)及其两种暗孤子解,详细讨论了不同形式的拉曼增益对暗孤子解传输特性的影响。结果表明:周期的正弦函数拉曼增益会使两种暗孤子解的背景波产生周期性振荡,并且振荡周期和幅度均随正弦函数的参数变化而变化;双曲正弦函数和指数函数的拉曼增益将会使两种暗孤子解的背景波功率升高;正切函数的拉曼增益会使两种暗孤子解的背景波产生阶跃性变化,且周期振荡暗孤子解会在传输过程中发生分裂。     

HL─1装置等离子体输运与锯齿特性的数值研究

本文利用一维圆柱等离子体输运编码（ＴＲＡＮＰＹ），编制了模拟锯齿振荡的大型编码（ＳＡＷＭＯＤ）。对锯齿振荡的研究，我们选用了两种具有代表性的理论模型：重联模型和湍流模型，后者特别适用于低ｑａ放电的锯齿特性研究。重联模型的锯齿振荡是由于磁力线的完全重联引起的，而湍流模型的锯齿振荡是因为微观湍流或磁力线的随机化而产生的。最后，我们将ＨＬ─１装置的一次典型高密放电的参数代入（ＳＡＷＭＯＤ）编码，运算结果表明，重联模型和湍流模型均能解释实验观测的锯齿现象，理论模拟与实验结果符合较好。     

双束旁射虚阴极振荡器的粒子模拟

提出了虚阴极振荡器（Ｖｉｒｃａｔｏｒ）一种新的物理模型，用自己编写的两维半、全电磁、相对论性的粒子模拟程序ＷＧＣＦ模拟了两个对称虚阴极互相耦合振荡产生高功率微波（ＨＰＭ）的物理过程，激发的柱面波横向３６０°引出。通过大量的计算（包括单束情况）表明：（１）极距ｄ不变时，无论双束还是单束，比值Ｊ＿０／Ｊ＿ｃ在１２～２之间效率较高；（２）Ｊ＿０／Ｊ＿ｃ不变时，极距ｄ有一最佳值，大于或小于此值时效率略降低；（３）双束情况输出波型较纯净，无“直流”分量，单束情况却不然；（４）双束时频率增宽；（５）与一维情况不同，Ｊ＿０≈Ｊ＿ｃ时也会发生振荡，但直流成分较大。此外，我们对横向外边界的透射边界条件和辐射功率按模式、频率分布的表达式进行了推导。     

邻氨基苯甲酸BZ反应体系中的振荡与混沌：I.SCTR实验研究和非线…

本文研究了ＣＳＴＲ中邻氨基苯甲酸苯甲酸ＢＺ反应体系的振荡行为，总结了非化条件下各反应物浓度和流速变化以及温度变化对体系振荡反应的影响规律；同时还考察了催化条件下的体系振荡行为，发现了Ｍｎ（Ⅱ）催化出现复杂振荡筢应序列，非线性动力学理论分析的结果表明复杂振荡是由体系动力学本质决定的确定性行为，并发现由周期走向混沌的演变过程中存在倍周期分岔（或慢周期分岔）迹象；同时，还通过计算分维，研究反应条件对体系     

中红外超短脉冲的产生及其研究的最新进展

中红外超短（皮秒至飞秒量级）脉冲是研究固体、表面、等离子体和光化学等领域里各种瞬态过程的有力工具。着重介绍了常用的四种产生中红外超短脉冲的方法，即光学自由感应衰减、半导体开关、光学参量振荡以及差频产生，并比较了它们的优缺点，概述了这方面研究的最新进展及其应用。     

Modeling of heat explosion with convection

The work is devoted to numerical simulations of the interaction of heat explosion with natural convection. The model consists of the heat equation with a nonlinear source term describing heat production due to an exothermic chemical reaction coupled with the Navier-Stokes equations under the Boussinesq approximation. We show how complex regimes appear through successive bifurcations leading from a stable stationary temperature distribution without convection to a stationary symmetric convective solution, stationary asymmetric convection, periodic in time oscillations, and finally aperiodic oscillations. A simplified model problem is suggested. It describes the main features of solutions of the complete problem.     

Estimation of Uncertainty in an Analytical Inverse Heat Conduction Solution

The method of sequential perturbations is applied to find the uncertainty in estimated surface temperature and heat flux from a two-dimensional analytical inverse heat conduction problem related to impinging jet quenching experiments. It is shown that for meaningful uncertainty estimates, the inverse solution itself must be formulated such that it can be interpreted as giving average surface conditions over a small period of time and space. A procedure for estimating the time and space resolution limits of the solution is proposed.     

Resonant interaction of an electromagnetic wave with an inhomogeneous plasma slab

Resonant interaction at oblique incidence of an electromagnetic wave on an inhomogeneous plasma slab is studied. The time evolution of this interaction is solved numerically from two-fluid equations, adiabatic equation for electron pressure and from Maxwell equations. It is shown that the electromagnetic energy of an incident wave is transformed both into the heat energy and into the energy of plasma oscillations in the direction of density gradient. The distribution of the transformed energy between the heat energy and the energy of plasma oscillations is strongly dependent on the plasma temperature. The ratio of heat energy to the energy of plasma oscillations is growing with growing temperature. The plasma oscillations are generated by magnetic induction of the penetrating wave. In a cold plasma they are generated especially in the overdense region and their frequency is equal to local plasma frequency. The electric field in the direction of plasma gradient has a form of a wave packet whose envelope reaches a maximum at resonance. The characteristic wavelength in the wave packet decreases and the amplitude of the packet increases with the time.     

A fast semi-implicit method for anisotropic diffusion

Simple finite differencing of the anisotropic diffusion equation, where diffusion is only along a given direction, does not ensure that the numerically calculated heat fluxes are in the correct direction. This can lead to negative temperatures for the anisotropic thermal diffusion equation. In a previous paper we proposed a monotonicity-preserving explicit method which uses limiters (analogous to those used in the solution of hyperbolic equations) to interpolate the temperature gradients at cell faces. However, being explicit, this method was limited by a restrictive Courant–Friedrichs–Lewy (CFL) stability timestep. Here we propose a fast, conservative, directionally-split, semi-implicit method which is second order accurate in space, is stable for large timesteps, and is easy to implement in parallel. Although not strictly monotonicity-preserving, our method gives only small amplitude temperature oscillations at large temperature gradients, and the oscillations are damped in time. With numerical experiments we show that our semi-implicit method can achieve large speed-ups compared to the explicit method, without seriously violating the monotonicity constraint. This method can also be applied to isotropic diffusion, both on regular and distorted meshes.     

Oscillations of the crystallization front of adsorbed water

Relaxation oscillations of the crystallization front in a gradient temperature field have been observed for water adsorbed on a metal film deposited on a glass substrate. The metal film plays an important role in heat removal from the crystallization front and determines the existence of oscillations. A possible mechanism is proposed for the development of oscillations. It is shown that the oscillations observed are similar to the oscillations of the front of self-propagating high-temperature synthesis.     

New tokamak plasma regime with stationary temperature oscillations

During noninductively driven discharges in the Tore Supra tokamak, steady sinusoidal oscillations of the central electron temperature, lasting as long as 2 min, have been observed for the first time. Having no helical structure, they cannot be ascribed to any known MHD instability. The most plausible explanation of this new phenomenon is that the plasma current density and the electron temperature evolve as a nonlinearly coupled predator-prey system. This interpretation is supported by the numerical solution of coupled resistive current diffusion and heat transport equations.     

Simulation Study of Shock Reaction on Porous Material

Direct modeling of porous materials under shock is a complex issue. We investigate such a system via the newly developed material-point method. The effects of shock strength and porosity size are the main concerns. For the same porosity, the effects of mean-void-size are checked. It is found that local turbulence mixing and volume dissipation are two important mechanisms for transformation of kinetic energy to heat. When the porosity is very small, the shocked portion may arrive at a dynamical steady state; the voids in the downstream portion reflect back rarefactive waves and result in slight oscillations of mean density and pressure; for the same value of porosity, a larger mean-void-size makes a higher mean temperature. When the porosity becomes large, hydrodynamic quantities vary with time during the whole shock-loading procedure： after the initial stage, the mean density and pressure decrease, but the temperature increases with a higher rate. The distributions of local density, pressure, temperature and particle-velocity are generally non-Gaussian and vary with time. The changing rates depend on the porosity value, mean-void-size and shock strength. The stronger the loaded shock, the stronger the porosity effects. This work provides a supplement to experiments for the very quick procedures and reveals more fundamental mechanisms in energy and momentum transportation.     

Transient coupled radiative and conductive heat transfer in a semitransparent layer of ceramic

This work considers transient radiative and conductive heat transfer in a semitransparent layer of ceramic, submitted to several thermal and radiative boundary conditions. Each side of the layer is exposed to hot or cold radiative surroundings, while each boundary is heated or cooled by convection. The solution procedure must provide accurate temperature distribution in the layer, so a nodal analysis based on Hottel's zonal method extended by ray tracing method is carried out. A finite difference method with non-uniform space and time increments is used to solve the transient energy equation, including a radiative heat source, coupled to a equation of radiative transfer. Variable spacing was used to concentrate grid points in regions with large temperature gradients. The influence of refractive index, optical thicknesses and conduction-radiation parameters is investigated.     

Dynamics of Random One-Dimensional ±J Systems

Finite chains of a two-state random Potts spin model with periodic boundary conditions are studied within Glauber dynamics. The spin exchange is assumed random with frustration between ferro and antiferromagnetic values (±J). Time-dependent fluctuations are induced by periodic temperature oscillations. Master type differential equations for spin correlation functions are solved within linear response theory. The spectrum of relaxation times are calculated at different temperatures. The ±J Potts glass chains undergo a zero temperature phase transition. The barriers against inversion of the spin chain take only two values; 0 and 2|J|. The temperature behaviour of specific heat is characterized by rounded peaks. The frequency dependence displays two plateaus for the real part of specific heat and two corresponding peaks for the imaginary part. The dynamic specific heat is not affected by the longest relaxing mode like susceptibility. The time separation of the modes is demonstrated by the Cole-Cole plots.     

Thermal-relaxation dissipation in thermoacoustic systems

Pressure oscillations in a sound wave are accompanied by temperature oscillations. In the presence of a solid boundary, the heat transfer from the oscillating gas to the solid boundary causes dissipation of the acoustic energy. This results in the attenuation of the sound wave. This thermal-relaxation dissipation process has a negative effect on the performance of thermoacoustic heat pumps and engines. A simple analytical model describing the interaction between an acoustic wave and a solid boundary is presented. The effect of the solid material and gas type on thermal-relaxation dissipation is analysed. The main result of this model is that the choice of a solid material with the smallest possible heat capacity per unit area in combination with a gas with the largest possible heat capacity per unit area minimises the thermal-relaxation dissipation. From the different combinations solid-gas used in the calculations, the combination cork-helium leads to the lowest thermal attenuation of the sound wave. In this case, the heat transfer from the gas to the wall less damps the temperature oscillations. However, because of the porosity of cork that may cause some problems, it is suggested that the combination polyester-helium can be used in practice to minimise the thermal-relaxation losses.