液晶磁致旋光的研究

利用矩阵方法分析了液晶的旋光效应，导出了液晶旋光的矩阵表示. 利用JG-3型连续可调谐磁场仪搭建实验装置，红外1350 nm激光器做光源，测量了偏振光通过磁场作用下BL-009型向列相液晶的旋光角，详细分析了磁场对液晶旋光性能的影响. 通过实验测试，对液晶的阈值磁场强度进行了讨论，同时对实验结果进行了理论上的分析，得出了液晶旋光角随磁场与液晶盒表面夹角而变化的结论，验证了液晶分子轴的旋转方向与磁场的方向无关，这为更好的研究液晶的特性以及液晶器件的设计具有重要的参考价值. 关键词： 液晶 矩阵 磁致旋光     

Attainable superheating of solutions of cryogenic liquids

The kinetics of spontaneous boiling-up of superheated binary solutions of cryogenic liquids is studied. Within the framework of the Kramers-Zeldovich method, an expression is obtained for the steady state rate of homogeneous nucleation in a solution that takes into account free-molecular and diffusion regimes of the substance supply to a growing bubble. Viscous and inertial forces are also taken into account in the study of the nucleus growth dynamics. The work of critical nucleus formation is determined within the framework of the Gibbs and van der Waals capillarity theories. The dependence of the surface tension of critical bubbles in the solution on their size is investigated. The temperature of attainable superheating and nucleation rates in superheated solutions of cryogenic liquids with complete or partial solubility of the components are determined by a method of lifetime measurement. The experiments were conducted in a wide range of pressures and solution concentrations. The measurement results are compared with the theory of homogeneous nucleation taking or not taking into account the size effect in nucleation. It has been found that, by taking into account the size dependence of the surface tension of a nucleus, better agreement between the theory and experiment is obtained. The boundary of essential instability of the solution, that is, the diffusion spinodal, is computed.     

1/4波片延迟量的相位调制椭偏测量法

利用椭偏测量术中的相位调制椭偏测量原理测量了1/4波片的延迟量。该方法预先对测量光束的偏振态进行调制,以生成随时间变化的光强信号,通过对信号中的谐变成分进行分析而获得待测波片的延迟量。测量了四个波片,其中三个波片的延迟量已经用电光调制法精确测量过,经对比测量的结果符合较好。观察到了和理论相符的云母波片延迟量的振荡现象。实验结果说明这种方法是一种有实际意义的方法。     

Influence of the opening angle of a conical supersonic nozzle on the structure of initial interval of non-isobaric jet

The ideal gas exhaustion from an infinite volume into a gas at rest through a supersonic conical Laval nozzle is considered. The problem was solved numerically by steadying in time in a unified formulation for the regions inside the nozzle and in the ambient environment. In such a statement, the nozzle outlet section is no internal boundary of the region under consideration, and there is no need of specifying the boundary conditions here. Local subsonic zones arising in the flow lie inside the region under consideration, which eliminates the possibility of using a marching technique along one of the coordinates. The numerical solution is constructed by a unified algorithm for the entire flow region, which gives a possibility of obtaining a higher accuracy. The computations are carried out in the jet initial interval, where, according to monograph [1], the wave phenomena predominate over the viscous effects. The exhaustion process is described by the system of gas dynamics equations. Their solution is constructed with the aid of a finite difference Harten’s TVD (Total Variation Diminishing) scheme [2], which has the second approximation order in space. The second approximation order in time is achieved with the aid of a five-stage Runge-Kutta method. The solution algorithm has been parallelized in space and implemented on the multi-processor computer systems of the ITAM SB RAS and the MVS-128 of the Siberian Supercomputer Center of SB RAS. The influence of the semi-apex angle of the nozzle supersonic part and the pressure jump between the nozzle outlet section and the ambient environment on the flow in the initial interval of a non-isobaric jet is investigated in the work. A comparison with experimental data is presented. The computations are carried out for the semi-apex angles of the nozzle supersonic part from 0 (parallel flow) to 20 degrees. For all considered nozzles, the Mach number in the nozzle outlet section, which was computed from the one-dimensional theory, equaled three. Computations showed that in the case of flow acceleration in a conical supersonic nozzle, its geometry is one of the main factors determining the formation of the jet initial interval in ambient environment.     

Gravitational interaction of a vector field with account of the nonmetricity of space-time

The gravitational interaction of a vector field is investigated in a space with the nonmetricity described by the Weyl vector. The analogue of the Coulomb law for the electrostatic field of a point charge is found in such a space. It is shown that taking account of the nonmetricity of space-time leads to the appearance of a nonlinearity in a massive vector field, resulting in the sine-Gordon and shine-Gordon equations. The screening of the vector-field mass as a consequence of its interaction with the nonmetricity is clarified. The solution for the Reissner-Nordström problem in a Weyl space is obtained, which asymptotically coincides with the solution of the same problem in general relativity, but nowhere does it possess singularities apart from at the origin. The obtained results show that it is reasonable to take account of the nonmetricity when describing the gravitational interaction of a vector field.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 50–54, August, 1984.     

混沌的乘法规律

从理论上分析了几个混沌映射相乘的规律，提出了混沌相乘的思想.数值仿真与理论计算结果表明，几个混沌映射相乘仍然具有非线性动力学特性和分岔序列.并且具有混沌吸引子和对初值敏感性.混沌的乘法概念具有重要的理论意义和应用价值. 关键词： 相乘混沌 吸引子 分岔序列     

Theory of switching of multiaxial ferroelectrics (Initial stage)

The classical theory of nucleation and growth is used to study the thermodynamics and kinetics of switching of multiaxial ferroelectrics. The initial stage of 180°-and 90°-domain switching is studied in the tetragonal, orthorhombic, and trigonal phases. The multidimensional kinetic theory of first-order phase transitions is applied to describe the initial stage of switching of ferroelectric crystals in the general case where three-dimensional growth (along the radius and height) of repolarized domains occurs. The energy of nucleus formation is calculated in the vicinity of the saddle point of an activation barrier in the space of sizes and shapes, and the dependence of the critical domain size on the switching field is found. The two-dimensional Fokker-Planck kinetic equation is reduced to a one-dimensional Zel’dovich equation, and a stationary solution to the Zel’dovich equation is obtained. The diffusion coefficients are derived in the size space for the normal and layer-by-layer mechanisms of domain growth. The main characteristic of the initial switching stage, namely, the steadystate flux of repolarized domains, is found as a function of the applied field.

     

High temperature equation of state of metallic hydrogen

The equation of state of liquid metallic hydrogen is solved numerically. Investigations are carried out at temperatures from 3000 to 20 000 K and densities from 0.2 to 3 mol/cm³, which correspond both to the experimental conditions under which metallic hydrogen is produced on earth and the conditions in the cores of giant planets of the solar system such as Jupiter and Saturn. It is assumed that hydrogen is in an atomic state and all its electrons are collectivized. Perturbation theory in the electron-proton interaction is applied to determine the thermodynamic potentials of metallic hydrogen. The electron subsystem is considered in the randomphase approximation with regard to the exchange interaction and the correlation of electrons in the local-field approximation. The proton-proton interaction is taken into account in the hard-spheres approximation. The thermodynamic characteristics of metallic hydrogen are calculated with regard to the zero-, second-, and third-order perturbation theory terms. The third-order term proves to be rather essential at moderately high temperatures and densities, although it is much smaller than the second-order term. The thermodynamic potentials of metallic hydrogen are monotonically increasing functions of density and temperature. The values of pressure for the temperatures and pressures that are characteristic of the conditions under which metallic hydrogen is produced on earth coincide with the corresponding values reported by the discoverers of metallic hydrogen to a high degree of accuracy. The temperature and density ranges are found in which there exists a liquid phase of metallic hydrogen.     

太湖梅梁湾水下光场扰动的特征分析

在水体表面波的扰动作用下,水下光场随深度呈现较为明显的波动现象,且水中光合作用会对水下光场波动作出响应,因而此现象引起了广泛的关注。基于太湖梅梁湾观测的水下光场数据,计算了水下光场随深度的变化,并分析了其波动特征。结果表明:表面波引起了水下光场较为明显的波动现象,波动振幅最大的深度基本小于20 cm,远小于海洋中对应的深度;水下光场波动的振幅随深度呈e的负指数衰减,漫射消光系数越大,水下光场的波动衰减得也越快;当深度大于30 cm时,水下光场的扰动现象基本消失。还计算了船舶对水下光场观测的影响,发现直射光未被遮挡的情况下,漫射比例越高,其相对误差越大。     

小尾寒羊胴体不同部位矿物元素的比较研究

采用火焰原子吸收法对小尾寒羊胴体不同部位的Ca,Fe,K,Cu,Zn和Mg等矿物元素的含量进行了分析测定。该法的加标回收率为96.9%—104.2%,RSD值小于2.0%,具有良好的准确度和精密度。研究结果表明：小尾寒羊肉中Ca,Fe,K,Zn和Mg含量丰富,颈肉中Ca的含量最高,肋肉和腰肉中Mg的含量较高,心和肝中Fe的含量较高,心和颈肉中Zn的含量较高。此测定结果可为探讨羊肉中矿物元素的含量与其代谢调节功效的相关性提供科学依据。     

SU-8光刻胶应变分布光学全场检测方法

由于SU-8光刻胶的内应力将会影响高深宽比结构的全金属光栅的制作质量,本文针对近年来SU-8光刻胶应力测量困难的情况,提出了一种基于激光剪切散斑干涉技术的SU-8光刻胶应变分布测量的新方法。该方法通过对被测胶体加载前后两幅干涉图像的处理,直接得到被测胶体结构的全场应变分布情况,由胶体的应变变形数据即可反映出内应力的变化和分布趋势。同时使用ANSYS有限元分析软件对同一被测胶体进行应变仿真模拟研究,获得胶体结构的变形场仿真数据。组建了实验系统,进行了实验验证,结果表明:实际测量变形量约为1.189μm,仿真的最大变形量为1.088μm,测量误差在允许范围内,且测量的形变趋势与仿真模拟结果相一致,表明激光剪切散斑干涉技术可应用于SU-8光刻胶的应变分布全场无损检测。     

Study of influences of laser power fluctuation on thermogram of the material

The effects of the laser beam instability on the temperature of the material are studied in this paper. The fluctuation of the temperature not only relates to the laser beam instability, but also correlates with the thermal conductivity, the thermal diffusivity, the emissivity, the laser–solid interaction time, and the laser spot diameter. The temperature fluctuation of the aluminum, the polymethylmethacrylate, the epoxylite, and the low carbon steel is measured by the infrared thermal imagers (HWRX··) to determine validity of the theory prediction. It is found that the theoretical prediction is in good agreement with the experimental results. Besides, the maximum amplitude of the temperature fluctuation is calculated and how to control the temperature fluctuation is discussed. The results show that the temperature fluctuation in the laser–solid interaction is of importance in practice.     

The stability of the simple cubic phase of phosphorus

The transition from the rhombohedral phase to the simple cubic phase of phosphorus under pressure is studied within the local density-functional formalism with use of the norm-conserving pseudopotential. The calculated transition pressure is 15.8GPa, which is in good agreement with the measured value, 10GPa. The bonding in the simple cubic phase is shown to be predominantly covalent. It is found that the instability of the simple cubic structure under low pressures is understood by a Peierls' instability, which is just the same as the case of arsenic. It is also shown that the mixing of atomic 3d-orbitals in the occupied states is important for stabilizing the simple cubic structure under high pressures.     

Analysis of the Evolution of a Supersonically Expanding Plasma

A supersonically expanding arc plasma in argon is analyzed both experimentally and theoretically. The plasma is created in a cascaded arc and extracted through a hole in the anode. It emanates in a large vacuum system, where it expands supersonically. This expansion is limited by a shock wave. After the shock wave a subsonic plasma beam is created. A quasi one-dimensional model, based on the conservation of mass, momentum and energy is presented. The shock wave is treated as a discontinuity. The electron density, the gas velocity and the gas temperature are measured as a function of the position in the expansion by means of Stark broadening and Doppler spectroscopy. The model calculations agree well with the measurements, especially in the first part of the supersonic flow.     

一种新型光纤压力传感器的设计

设计了一种工作波长为800 nm的光纤压力传感器,提出了一种用补偿光纤对温度和双折射进行补偿的方法,并从理论上进行了解释.在不同温度和压力条件下对该传感器进行了实验,相对误差小于1.5％.实验结果表明,该补偿方法是有效的.在0℃~50℃的温度下,对传感器在0～40 MPa的压力范围内进行了测试,其标准偏差在1%以内.     

Nature of instability of block media and distribution law of unstable states

The paper studies the properties of a structured continuum. The result of finite structure size is that difference relations fail to automatically pass into differential ones. Consideration of an infinitely small volume of the medium with laws of conservation is found impossible. The representative volume is only that volume of finite dimensions which contains a certain minimum set of elementary mesostructures. The impossibility to merely replace difference relations by differential relations lead to equilibrium equations and equations of motion of infinite order due to an infinite number of degrees of freedom in block media. golutions of these equations contain, in addition to ordinary elastic waves, a set of waves with widely different velocities, including extremely low velocities unbounded below. As shown earlier, small vibration in these media can be both decreasing and unlimitedly increasing. Hence, small vibrations are not always harmless. A dual role belongs to structure size dispersion. The latter weakens unstable vibrational phenomena, but extends the range of vibration frequencies involved in a catastrophic process such that catastrophic events may arise at quite low frequencies. The equilibrium equation can not hold in each infinitesimal volume of the medium because it is not representative for the medium as a whole. The equilibrium equation is valid only on average for sufficiently representative volumes. Hence, individual dynamic events are possible in the medium even if it is at equilibrium as a unit. This phenomenon is termed acoustic emission. The paper describes conditions under which acoustic emission initiates wave processes in their ordinary sense, i.e., initiation of waves under quasistatic stresses. The set of complex roots of the dispersion equation which are possible to interpret as the number of unstable solutions depends on the specific crack surface. At the logarithmic scale, this relation is almost linear and fits the Gutenberg-Richter earthquake repeatability law well-known in seismology.     

Calculation of Electronic Structure of Zinc-Blende CdS

The linear-muffin-tin orbital method is used to study the electronic-energy-band structure of zinc-blende CdS. Incorporating the 4d states of Cd into the valence band gives substantially the main-valenceband width, and yields valenceband features in agreement with the experiment. The calculated equilibrium lattice constant is in accord with the measured result. The fundamental band gap is found to be direct at T point and the value is about 1.21 eV. The band structure calculation shows that the present results are in good agreement with experiments and other calculations.     

Acoustical estimation of parameters of porous road pavement

In the simplest case, porous road pavement of a known thickness is described by such parameters as porosity, tortuosity, and flow resistance. The problem of estimating these parameters is investigated in this paper. An acoustic signal reflected by the pavement is used for this. It is shown that this problem can be solved by an experiment conducted in the time domain (i.e., the pulse response of the media is recorded). The incident sound wave is thrown at a grazing angle to the surface between the pavement and the air to improve penetration into the porous medium. The procedure of computing of the pulse response using the Morse-Ingard model is described in detail.     

Influence of the periodic motion of a monochromatic light source on the spectrum of its radiation

The influence of the periodic motion of a monochromatic light source on the observed spectrum of its radiation in the far-field and near-field zones is considered. The appearance of components shifted in frequency (harmonics of the oscillation frequency of the source) is demonstrated. The spatial structure of harmonics is investigated, and the presence of optical vortices in these harmonics is shown.     

Determination of the of rate cross slip of screw dislocations

The rate for cross slip of screw dislocations during annihilation of screw dipoles in copper is determined by molecular dynamics simulations. The temperature dependence of the rate is seen to obey an Arrhenius behavior in the investigated temperature range: 225-375 K. The activation energy and the effective attempt frequency can therefore be extracted from the simulations. The transition state energy for the annihilation process is calculated by identifying the transition state using the nudged elastic band path technique. The two activation energies agree very well, indicating that transition state theory is applicable for this type of process.