A QUASI-NEWTON METHOD IN INFINITE-DIMENSIONAL SPACES AND ITS APPLICATION FOR SOLVING A PARABOLIC INVERSE PROBLEM

1.IntroductionQuasi-Newtonmethodsplayanimportantroleinnumericallysolvingnon--linearsystemsofequationsontheEuclideanspaces.Blltitseemsthatthequasi-Newtonmethodshavenotbeenapplieddirectlytosolvinginverseproblemsinpartialdifferentialequations(PDE)uptonowifwe…     

Molecular orientation dependence of ortho-para H2 conversion on Fe(OH)3 cluster induced by hyperfine contact interaction

We investigate the molecular orientation dependence of the (o)rtho-(p)ara H₂ conversion on Fe(OH)₃ cluster. Taking Fermi's contact interaction as perturbation, we find that the o-p H₂ conversion yield for the molecular orientation angle θ= 10^○ with respect to the surface normal is larger than that for θ= 70^○.     

悬丝耦合音频共振法的原理与检验

提出了悬丝耦合音频共振的实验方法,用来测定材料的杨氏模量、剪切模量和泊松比,并分析了测量误差来源,进而运用此方法测定了25号碳钢(退火)的杨氏模量和剪切模量.     

Modification of spontaneous emission rate in planar dielectric microcavities – seen as superradiance and subradiance

The modification of the spontaneous emission rate of an atom in a cavity can be seen as superradiance/subradiance induced by virtual image dipoles. This result is used to gain physical insight why the spontaneous emission is enhanced or suppressed in various cavity geometries. A general model for spontaneous emission engineering, which simultaneously handles dispersive and lossy cavities, is derived.     

Velocity and concentration profiles in uniform sediment-laden flow

This paper presents a theoretical model for computing the velocity and sediment concentration profiles in a uniform sediment-laden flow carrying all fine, medium and coarse sediments. The proposed model essentially includes the effect of sediment concentration in total turbulent shear stress and eddy diffusivity in addition to the modified mixing length derived by Umeyama and Gerritsen [J. Hydr. Engng., ASCE, 118 (2) (1992) 229–245] applied to Hunt’s diffusion equation. Numerical solution of coupled differential equations for velocity and sediment concentration is carried out. The theoretical results show quite good agreement with the experimental data.     

火炬松木材剪切弹性模量的测试研究

研究采用变跨距的三点弯曲方法测试10年生火炬松木材17号家系和50号家系的剪切弹性模量GLT,GLR值;用45°偏轴压缩法测量GRT值.测试结果表明,速生材火炬松的剪切弹性模量GLT,GLR,GRT都不高,在70-180 MPa之间,其中GRT最小;另外,整体上火炬松17家系的抗剪切性能优于50号家系.     

Conductivity effect in electrorheological fluids

Based on conduction model and cubic particle model, the relationship between current density and shear yield stress of electrorheological (ER) fluids was calculated and compared with some reported experimental results. The conductivity of the insulating oils is found to have been changed by the mixed particles. Several ways to decrease insulating liquid conductivity and increase the conductivity ratio of ER fluids have been proposed to prepare ER fluids with high shear yield stresses but low current densities.     

Preliminary Investigation of Impurity and Radiation Behaviors in the Startup Phase of HL-2A Tokamak

As the startup phase of HL-2A operation and the first divertor tokamak device in China, it is important to identify the species of impurity, estimate the concentration of impurities and compare the different behaviors of radiation in limiter and divertor configurationt. In startup phase of HL-2A, glowing discharge cleaning （GDC） is used as a conventional wall conditioning technology and titanium gettering is used occasionally in closed divertor chamber during SN configuration discharges phase.     

A Unifying Explanation for the Damping of Turbulence by Additives or External Forces

Recent calculations for the turbulent flow of a suspension of solid spheres in a gas were carried out by solving a Navier Stokes equation for the fluid that recognizes the presence of particles as external point forces. These show that a strong damping of the fluid turbulence can be realized at remarkably small volume fractions. The suggestion is made that the presence of point forces, pseudo-point forces, or added point shear stresses could provide a general explanation for turbulence suppression caused by additives or by the acceleration of a turbulent boundary-layer.     

Cyclic shear of saturated soil: the evolution of stress inhomogeneity

Received July 30, 2001 / Published online February 28, 2002