A Two-Layer Model for Superposed Electrified Maxwell Fluids in Presence of Heat Transfer

Based on a modified-Darcy-Maxwell model, two-dimensional, incompressible and heat transfer flow of two bounded layers, through electrified Maxwell fluids in porous media is performed. The driving force for the instability under an electric field, is an electrostatic force exerted on the free charges accumulated at the dividing interface. Normal mode analysis is considered to study the linear stability of the disturbances layers. The solutions of thelinearized equations of motion with the boundary conditions lead to an implicit dispersion relation between the growth rate and wave number. These equations are parameterized by Weber number, Reynolds number, Marangoni number, dimensionless conductivities, and dimensionless electric potentials. The case of long waves interfacial stability has been studied. The stability criteria are performed theoretically in which stability diagrams are obtained. Inthe limiting cases, some previously published results can be considered as particular cases of our results. It is found that the Reynolds number plays a destabilizing role in the stability criteria, while the damping influence is observed for the increasing of Marangoni number and Maxwell relaxation time.     

A New Car Following Model： Comprehensive Optimal Velocity Model

In this paper, we present a new car-following model, i.e. comprehensive optimal velocity model (COVM), whose optimal velocity function not only depends on the following distance of the preceding vehicle, but also depends on the velocity difference with preceding vehicle. Simulation results show that COVM is an improvement over the previous ones theoretically. Then, the stability condition of the model is obtained by the linear stability analysis, which has shown that the model could obtain a bigger stable region thanprevious models in the phase diagram. Through the nonlinear analysis, the Burgers, Korteweg-de Vries (KdV) and modified KdV (mKdV) equations are derived for the triangular shock wave, the soliton wave, and the kink-antikink soliton wave. At the same time, numerical simulations are also carried out to show that the model could simulate these density waves.     

A New Solution with Torsion in Model of dS Gauge Theory of Gravity

A new static de Sitter solution with torsion in the model of de Sitter gauge theory of gravity is obtained. The torsion only contains O(3)-symmetric tensor part according to irreducible decomposition. Some properties of the new solution are discussed.     

向量自回归模型与向量误差修正模型预测功能的比较——基于我国国内生产总值和居民消费支出变量的实证研究

建立国内生产总值与居民消费支出有关形式变量的向量自回归模型和误差修正模型,依据国内生产总值和居民消费支出的历史数据分别对模型进行估计,并利用估计好的2个模型对近2年的相应变量进行预测,将预测结果与实际数据相比较,从而得出2个模型的预测效果.通过比较显示：误差修正模型预测效果优于向量自回归模型.     

高放废物地质处置中的模型

我国将采用深地质处置的方法处理核能发展所产生的大量高水平放射性废物。为了准确地预测核素的迁移行为,评估处置库的安全性,除了实验之外,还必须使用模型。本文对高放废物地质处置中所涉及的模型,以及与模型相关的软件、数据库做了综述,重点叙述了用于化学种态分析的地球化学模型,扼要介绍了多场耦合模型。此外还简要报告了本实验室核素迁移实验数据的处理方法和程序。     

一种多源空间数据统一访问模型的实现

空间数据通常以栅格与矢量两种数据模型进行表达,但由于各自的不同特性,一般采用不同的访问方式.如何采用一致的方式进行多源空间数据访问是当前空间数据共享和互操作的难点之一.基于OGC SFS规范,从实现层次上考虑提出按几何与属性要素组织为几何-属性矢量数据模型（GAFeature model）,同时融入了扩展栅格数据模型,通过借鉴设计模式中的提供者模式和桥接模式,提供了一个较为完整的矢量栅格一体化访问管理模型,并进行了实现,使其能支持本地文件类型数据以及WCS、WFS空间信息服务.实验结果表明具备多源空间数据统一访问的能力.     

Kerr效应对非线性J-C模型辐射谱的影响

研究了Kerr介质腔中非线性J-C模型的辐射谱.导出了双模初始光场处于任意量子态时辐射谱的计算公式,给出了光场处于数态、相干态和压缩真空态时的数值结果,讨论了Kerr效应和初始场强对辐射谱的影响.发现在光子数态的情况下,Kerr效应使低频峰增强、高频峰减弱,并使各峰向右移动.在初始腔场为较强的相干态时,原子辐射谱明显地分成两个拱形的梳状峰群,Kerr效应的增强使左侧峰群增高,右侧的边峰受到抑制.在压缩真空态情况下,边带峰只出现在中心频率双峰的左侧,随Kerr效应和初始场的增强,边峰个数也随之增多.无论哪种情况都破坏谱结构的对称性,在强场条件下Kerr效应的影响更加显著.     

APPROXIMATE SOLUTIONS FOR TRANSIENT RESPONSE OF CONSTRAINED DAMPING LAMINATED CANTILEVER PLATE

The series composed by beam mode function is used to approximate the displacement function of constrained damping of laminated cantilever plates, and the transverse deformation of the plate on which a concentrated force is acted is calculated using the principle of virtual work.By solving Lagrange＇s equation, the frequencies and model loss factors of free vibration of the plate are obtained, then the transient response of constrained damping of laminated cantilever plate is obtained, when the concentrated force is withdrawn suddenly.The theoretical calculations are compared with the experimental data, the results show：both the frequencies and the response time of theoretical calculation and its variational law with the parameters of the damping layer are identical with experimental results.Also, the response time of steel cantilever plate, unconstrained damping cantilever plate and constrained damping cantilever plate are brought into comparison, which shows that the constrained damping structure can effectively suppress the vibration.     

ACOUSTICAL TRANSMISSION LINE MODEL FOR ULTRASONIC TRANSDUCERS FOR WIDE-BANDWIDTH APPLICATION

An improved model for ultrasonic transducers is proposed.By considering only the first symmetric mode,each layer is represented as an acoustical transmission line in modeling of bulk wave transducers.In imaging applications,wide bandwidth and short time duration are required.The approach we have used consists of impedance matching the front face of the piezoelectric transducer to the propagating medium with a quarter wavelength impedance matching layer and inserting an unmatching quarter wavelength acoustical layer between the rear face and backing material.A heavy backing would degrade the wide-band phenomena,but show a time duration shorter than 0.5 μs for imaging applications.PSPICE code of the controlled source model is implemented to precisely predict the performance of the matched transducers such as impedance,insertion loss,bandwidth and duration of the impulse response.Good agreement between the simulation and experimental results has been achieved.     

非饱和土渗流和变形强度特性的温度效应

高放核废料地下处置、高压电缆埋设和地热开发等工程的发展,使得温度对非饱和土基本力学性质影响的研究逐渐成为当前岩土工程的热点.从渗流特性和变形强度特性两方面出发,分析了温度对非饱和土基本力学性质的影响. 对于渗流特性,研究了温度对液相水和水蒸气运动的影响,并进一步综述了水热迁移模型的发展. 对于变形强度特性受温度的影响,从试验研究和理论模型入手,研究了非饱和土的变形和强度等随温度的变化规律,并在此基础上对温度的影响进行了总结.文中还指出了现阶段研究中存在的问题及今后的研究方向.