Effects of Hall Currents and Gyroviscosity on the Stability of a Finitely Conducting Rotating Viscous Plasma of Variable Density

The Rayleigh-Taylor instability of an incompressible viscous, finitely conducting, rotating plasma of variable density has been investigated in the presence of the effects of Hall currents and finite ion Larmor radius. The proper solution for a semi-infinité plasma layer having exponentially varying density in the vertical direction has been obtained by making use of a variational principle which is shown to characterize the problem. The dispersion relation has been solved numerically. It is found that gyroviscosity, viscosity and coriolis forces have stabilizing influence whereas Hall currents and resistivity have a destabilizing influence.     

Hall Currents and the Rayleigh-Taylor Instability of a Finitely Conducting Plasma in the Presence of Coriolis Forces

We have studied the effect of rotation on the development of Rayleigh-Taylor instability of an incompressible, viscous, Hall, finitely conducting plasma of variable density. The solution is developed, through variational methods, for a semi-infinite plasma in which the density varies exponentially along the vertical. It is found that the system is unstable for all wave numbers when the effects of magnetic resistivity are included. The effects of coriolis forces and viscosity on the growth rate of the unstable system are found to be stabilizing while that of Hall currents is destabilizing. Finite conductivity affects the growth rate of the unstable mode differently for the smaller and larger values of the wave numbers, destabilizing for the waves of large wave length and stabilizing for waves of small wave length.     

The statistical correlation of intermolecular coriolis and centrifugal forces

Correlation functions are computed in the laboratory frame for the molecular coriolis and centrifugal forces with respect to a frame of reference static in the laboratory. The molecular Coriolis and centrifugal forces in this laboratory frame result from a combination of the molecule's rotational and translational motion, and correlate statistically these two types of motion. They are not usually considered in the theory of decoupled rotational or translational diffusion. Correlation functions are computed for the enantiomers and racemic mixture of liquid bromochlorofluoromethane, and for dichloromethane liquid subjected to a strong, uniaxial, electric field of force in the z axis of the laboratory frame.     

柯里拉京与DNA相互作用的光谱研究

在p H 7.4的生理条件下,以溴化乙锭(EB)作为荧光探针,利用荧光光谱、紫外-可见吸收光谱、共振散射光谱法结合盐效应和DNA熔点(T_m)实验研究了柯里拉京(Cor)与小牛胸腺DNA分子之间的相互作用机制。实验结果表明,Cor静态猝灭DNA-EB体系的荧光。Cor与DNA作用后,其特征吸收峰强度发生减色效应;与DNA作用导致Cor在480.5 nm处的共振散射峰增强,并在330.2 nm处出现新共振散射峰。盐效应对Cor与DNA分子相互作用的影响较小。与Cor作用引起DNA的T_m值升高5.5℃。由此推断,Cor与DNA相互作用的主要方式为嵌插,两者间形成了超分子体系。通过计算获得Cor与DNA间结合常数(K_A)为5.82×10~3L/mol(298 K)、2.47×10~4L/mol(310 K),它们之间的作用为熵驱动的自发、吸热过程,疏水作用力是主要的非共价作用方式。     

反射后激光(光子)螺旋性改变的量子论解释和信息论意义

基于近年来王顺金提出的处理螺旋光纤中激光(光子)传播时的螺旋性变化的理论方法和所得结果,分析了激光(光子)在反射后螺旋性(左旋与右旋)互换这一实验事实,发现激光(光子)反射的瞬息过程会产生一个极高的激光束回转频率,它与激光园偏振(光子自旋)发生科式惯性力耦合,进而改变激光(光子)的螺旋性.还发现当激光束回转频率达到极大时,将发生激光(光子)螺旋性(左旋与右旋)互换.讨论了激光反射后螺旋性互换的信息论含义及其应用.     

Normal co-ordinates through coriolis coupling constants

Normal co-ordinates, force fields and isotopic frequencies have been calculated for someXY ₃ andXY ₄-type molecules using coriolis coupling constants.     

三轴形变对102Rh旋称反转的影响

将两准粒子加轴对称转子模型扩展到三轴形变, 对奇奇核102Rh的旋称反转进行了研究和分析, 结果表明, 可能的旋称反转机制 (即低K 空间n p相互作用和科氏力的相互竞争), 对于A=100质量区奇奇核也是适用的, 三轴形变可以明显地改进能谱的振荡特性. The model of an axially symmetric rotor plus two quasi particles for the Signature Inversion (SI) in odd odd nuclei is generalized to the triaxial deformation. The calculation of the odd odd nucleus 102Rh shows that the possible SI mechanism (i. e., the competition between the n p interaction and the coriolis force in low K space) is also appropriate for odd odd nuclei in the A=100 region. A triaxial shape can improve the vibration property of the rotational spectra remarkably.     

Rupture energy of a pendular liquid bridge

We propose a simple expression for the rupture energy of a pendular liquid bridge between two spheres, taking into account capillary and viscous (lubrication) forces. In the case of capillary forces only, the results are in accordance with curve fitting expressions proposed by Simons et al. [2] and Willett et al. [5]. We performed accurate measurements of the force exerted by liquid bridges between two spheres. Experimental results are found to be close to theoretical values. A reasonable agreement is also found in the presence of viscous forces. Finally, for small bridge volumes, the rupture criterion given by Lian et al. [10] is modified, taking into account additional viscous effects. Received 18 September 2000 and Received in final form 10 June 2001     

The meson propagator in nuclear matter

We present a formal device for calculation of a meson propagator in infinite nuclear matter, through the calculation of the ground state energy of the system in the presence of external, static meson fields, using a pseudo-Hamiltonian simply related to the actual Hamiltonian. This approach is particularly well adapted for dealing with some effects that are not taken into account at all in multiple scattering approaches, for example, the effects of nuclear forces on the intermediate states which are involved in the meson-single-nucleon scattering. A theorem is proved about limiting conditions under which the charged pion propagator is independent of the nuclear forces. These conditions are nearly enough realized in π-nucleus scattering (sufficiently below the energy of the first resonance) so that we can evaluate the corrections perturbatively. The (virtually unknown) two-body force between the 3-3 resonance and nucleons is shown to be of considerable importance in determining the π-meson propagator.     

Kinetic Constants Method for the Vibrational Analysis of Thallous Halide Dimers

The kinetic constants method is applied to the case of thallous halide dimers to evaluate the molecular constants such as, potential constants, compliance constants, mean amplitudes of vibration, coriolis coupling constants and centrifugal distortion constants, using the recent vibrational frequencies¹. The values of mean amplitude of vibration obtained by this method are in good agreement with the experimental values². The thermodynamic functions of thallous flouride for eleven temperatures ranging from 100K to 1000K are calculated on the basis of rigid-rotor, harmonic-oscillator approximation and are reported.     

Crossover between complete wetting and critical adsorption

The effects of bulk critical fluctuations on the adsorption of a fluid on a planar attractive substrate are studied as a function of the temperature and chemical potential in the presence of long-ranged forces. The latter are explicitly included in a phenomenological free energy functional constructed to give non-classical critical exponents. The crossover between the complete wetting and the critical adsorption regime is studied along different paths in thermodynamic space and a comparison is made with the results of recent experiments.     

VIBRATION SUPPRESSION OF A BEAM STRUCTURE BY INTERMEDIATE MASSES AND SPRINGS

A method based on the dynamic Green function has been proposed to determine the optimum values of masses and/or springs and their locations on a beam structure in order to confine the vibration at an arbitrary location. In the analysis, the beam is driven by a harmonic external excitation. The added masses on the beam and the springs attached are modelled as simple reactions that provide transverse forces to the beam. These forces act as secondary forces that reduce the response caused by the external force. Numerical simulation shows that the vibration of the beam can be confined in a certain region by the presence of masses and springs in best arrangement. This method is demonstrated for both a simply supported and a cantilever beam. An experimental set-up was designed in which a simply supported beam is excited by an electrodynamic shaker and the response of the beam is measured using an He-Ne laser system. This assures very accurate measurements and avoids any additional loading effects as in the case of accelerometers. Comparisons of the theoretical and the experimental results show good agreement.     

Energy flow of moving dissipative topological solitons

We study the energy flow due to the motion of topological solitons in nonlinear extended systems in the presence of damping and driving. The total field momentum contribution to the energy flux, which reduces the soliton motion to that of a point particle, is insufficient. We identify an additional exchange energy flux channel mediated by the spatial and temporal inhomogeneity of the system state. In the well-known case of a dc external force the corresponding exchange current is shown to be small but nonzero. For the case of ac driving forces, which lead to a soliton ratchet, the exchange energy flux mediates the complete energy flow of the system. We also consider the case of combination of ac and dc external forces, as well as spatial discretization effects.     

Study of a misaligned flexibly coupled shaft system having nonlinear bearings and cyclic coupling stiffness—Theoretical model and analysis

A model which enables dynamic analysis of flexibly coupled misaligned shafts is presented. The model is setup to account for both angular and parallel misalignment in the presence of mass unbalance and incorporates a coupling having angular, torsional and axial flexibility. Among the important features is the ability to simulate both nonlinear bearing stiffness and coupling angular-stiffness anisotropy. The equations of motion are derived for the linear system, extended to include nonlinear bearing effects and subsequently transformed into non-dimensional form for general application. A series of numerical analyses are performed and the influence of important system parameters assessed thereby providing insight to the resulting static and dynamic forces and motions. Angular and parallel misalignments are shown to produce fundamentally different system response. It is found that the static preload induced by both types of misalignment can play a key role in producing complex vibration resulting from it's interaction with rotating-element anisotropy and bearing nonlinear properties. Bearing static forces are altered and rotating elements are subjected to alternating forces which could affect fatigue life. Bearing forces can be further modified by the application of transmitted torque. The potential for great variability in system response is shown to exist due to the participation of numerous influential variables.     

The anharmonic force field of phosphorus trifluoride from the millimeter wave spectra of vibrationally excited states

The millimeter rotational spectra of PF₃ have been recorded for all four excited fundamental vibrational states. A coriolis resonance between ν₁ and ν₃ results in anomalous distortion constants for these states and can be analyzed to yield $\text{|ζ}{}_{13}{}^{\mathrm{y}}\text{| = 0.392}$. The value of $\text{ζ}{}_{33}{}^{\mathrm{c}}$ is found to be 0.4194 which does not fit the coriolis sum rule due to anharmonic resonance. Equilibrium values for the centrifugal distortion constants are determined and have been used to find the harmonic force field. All available data is used to determine some of the anharmonic force constants.     

旋转状态半受限冲射流流动和换热特性研究

利用数值模拟的方法,通过改变冲击雷诺数Rej(20000-35000)、旋转数Ro(0-0．0117)等参数,分析旋转条件下半受限单孔冲击射流的流动和换热特性,讨论了旋转对冲击射流的流场结构和换热特性的影响．研究结果表明:冲击射流在离心力和哥氏力的共同作用下发生弯曲,造成冲击靶面上的冲击斑随着旋转数Ro的增加而不断偏移,显著影响了冲击的冷却效果．冲击靶面的平均Nu数随着冲击雷诺数Rej的增加而增加;当旋转数Ro增加时,冲击靶面的平均Nu数先增加,后减小,然后再增加．计算结果和试验结论基本一致．     

The effective interactions between colloidal hard spheres in microporous media: Hypernetted chain approximation for replica Ornstein-Zernike equations

In this work, the effective interaction between hard sphere colloidal particles in the presence of a hard sphere solvent, both dispersed either in a disordered quenched matrix of hard spheres or in the random matrix of freely overlapping obstacles is analyzed, using the replica Ornstein-Zernike (ROZ) integral equations. The ROZ equations are supplemented by the hypernetted chain closure. The presence of either disordered or random matrix is manifested in the attractive minima of the colloid-colloid potential of mean force (PMF), in addition to a set of minima due to the presence of solvent species. The effects of matrix microporosity and solvent density on the PMF and the intercolloidal forces are investigated. This project has been supported in part by the National Council for Science and Technology of Mexico (CONACyT) under Grant 25301-E.     

Magnetic field effects on low dimensional electron systems: Luttinger liquid behaviour in a quantum wire

We discuss the effects of a strong magnetic field in quantum wires. We show how the presence of a magnetic field modifies the role played by electron electron interaction producing a strong reduction of the backward scattering corresponding to the Coulomb repulsion. We discuss the consequences of this and other effects of magnetic field on the Tomonaga-Luttinger liquids and especially on their power-law behaviour in all correlation functions. The focal point is the rescaling of all the repulsive terms of the interaction between electrons with opposite momenta, due to the edge localization of the electrons and to the reduction of the length scale. Because of the same two reasons there are some interesting effects of the magnetic field concerning the backward scattering due to the presence of one impurity and the corresponding conductance. As an effect of the magnetic field we find also a spin polarization induced by a combination of electrostatic forces and the Pauli principle, quite similar to the one observed in large Quntum Dots.     

Infrared energy levels and intensities of carbon dioxide—II

Energy levels and rotational constants are provided for all carbon dioxide infrared absorption transitions of significance for terrestrial atmospheric transmission. Constants have been recalculated using new FTS measurements in the 4.3 μm region at elevated temperature, new FTS measurements in the 15, 5, and 2 μm regions, precise laser measurements around 10 μm, and high resolution grating spectrometer measurements of isotopically enriched samples. Band centers, band strengths, and coriolis coupling constants are given for some 560 bands.     

A=100区奇奇核旋称反转

利用两准粒子加轴对称转子模型,对A=100质量区两个奇奇核¹⁰²Rh和^{9 8}Rh的旋称反转进行了研究.结果表明,在A=160,130,80三个质量区奇奇核的计算中 已得到证实的、可能的旋称反转机制(即低K空间n-p相互作用和科氏力的相互竞争),对 于A=100质量区奇奇核也是适用的.这暗示在不同质量区奇奇核可能存在一种普遍的旋称 反转机制. 关键词： 奇奇核 旋称反转 两准粒子加轴对称转子模型