Measurement of the Elasticity of Biological Soft Tissue of Finite Thickness

Elasticity is of profound significance to evaluating the function of a biological soft tissue.When the elasticity of a tissue is macroscopically changed,it means that the biological function of the tissue is abnormal and some disease or injury may occur.In the present work,an elastometer is developed to measure the elasticity of biological soft tissues.The measurement is based on the indentation method and the force is measured by the bending of the cantilever.The force-indentation data of the soft tissue is experimentally measured by this elastometer and Young's modulus of the tissue is calculated using the Hertz-Sneddon model.For comparison,a numerical model for the indentation method is established using the finite element method.The difference between the actual modulus and the measured modulus is discussed.The effect of the thickness of the specimen on the measurement is investigated.Young's moduli of beef,porcine liver and porcine kidney are experimentally measured.The results indicate that our elastometer is effective in measuring Young's modulus of a soft tissue quantitatively.     

Measurement of degree of polarization of fluorescence of pure anthracene crystalline film

The polarization ratio (I _b/I_a) of fluorescence of a monocrystalline film of pure anthracene is measured correcting for all probable errors. Comparison with decay-time data brings out that deviation from the value obtained from absorption measurements is due to a loss of intensity in the a-polarized fluorescence as compared to what is expected from absorption data. This is interpreted as an evidence that anthracene crystal fluorescence is emitted from regions of local lattice imperfections. It is confirmed that the first electronic transition takes place along the short axis of the anthracene molecule.     

Model of process of singular estimation of the primary tone of a speech signal

A novel method is proposed to estimate the primary tonal frequency of speech. The method is based on singular spectrum analysis. A singular model of a vocalized segment of a speech signal is presented that considers the direct and inverse problems. A study is conducted of the process of singular estimation of the primary tonal frequency of speech. Experimental research is carried out using a model that yields adequacy and reliability estimates. The concept of singular estimation of the primary tonal frequency of speech is introduced.     

Observation of the condensation of a gas of interacting grains

We consider an ensemble of grains that interact through a dipole-dipole interaction. A granular gas is formed by the vertical motion of a piston at the bottom boundary of the system. The interaction between the grains is controlled by an horizontally applied magnetic field. When the speed of the piston is decreased, we observe a transition from a low density to a high density phase. When the interaction between grains is weak, the transition is continuous. It is discontinuous for stronger interaction. The phase diagram displays strong similarities with the ones observed for usual equilibrium phase transitions.     

Investigation of oscillations of a soliton of a bose condensate of atoms in a trap in the limit of small oscillations of its walls

The motion of the center of a soliton in a trap with oscillating walls is studied analytically and numerically for the case in which the intrinsic frequency of small soliton oscillations in the equilibrium state considerably exceeds the frequency of wall oscillations. this problem can be solved either by applying the gross–pitaevskii equation, which most exactly describes the behavior of the soliton in the trap, or by using the approximate, “mechanical,” equation of motion of the newtonian type for the center of the soliton. an approximate analytical solution of the mechanical equation is obtained and is compared with the numerical solution of the newton equation, while the latter solution is compared with the numerical solution of the gross–pitaevskii equation. good agreement between the first two solutions is revealed. it is also shown that there is a range of parameters in which the numerical solutions of the newton and gross–pitaevskii equations are closest to each other. the frequency-sweeping effect of soliton center oscillations is revealed. an approximate analytical formula for the limiting frequency of these oscillations is obtained and the numerical analysis of this phenomenon is performed.     

Theory of scattering of X-Rays

Scattering by bound electrons is considered in the nonrelativistic approximation. The matrix element for the transition is calculated in the second order of perturbation theory without the use of intermediate states. It is shown that ordinary scattering is accompanied by scattering giving lower -energy quanta and fast electrons.     

Moment of inertia of superconductors

We find that the bulk moment of inertia per unit volume of a metal becoming superconducting increases by the amount $m_e/(\pi r_c)$, with $m_e$ the bare electron mass and $r_c=e^2/m_e{c}^2$ the classical electron radius. This is because superfluid electrons acquire an intrinsic moment of inertia $m_e{(2{\lambda }_L)}^2$, with ${\lambda }_L$ the London penetration depth. As a consequence, we predict that when a rotating long cylinder becomes superconducting its angular velocity does not change, contrary to the prediction of conventional BCS-London theory that it will rotate faster. We explain the dynamics of magnetic field generation when a rotating normal metal becomes superconducting.     

Real-time measurement of retardation of eighth-wave plate independent of fast-axis direction

A real-time measurement method for the retardation of an eighth-wave plate is proposed. The collimated laser beam is split using a Glan Taylor polarizer with two side escape windows. The reflected sub-beam is detected using a detector, whereas the transmitted sub-beam passes through the quarter-wave plate and the eighth-wave plate of interest. Then, it is reflected by the mirror and passes reversely through the eighth-and quarter-wave plates. Finally, it is analyzed using the Glan Taylor polarizer and detected using another detector. With two detection signals, the retardation is resolved and found to be independent of the fast-axis direction, initial intensity, and circuit parameters. In the experiment, a crystal quartz sample is measured at different fast-axis angles. The standard deviation of the retardation is 0.9 o . The usefulness of the method is verified.     

Restriction of a Number of Levels of Dimensional Quantization in Elements of Nanoelectronics

Russian Physics Journal - Realization of a criterion of dimensional quantization in quantum wells of various profiles is considered. It is established that there is the limit number of the discrete...     

Comparative analysis of side-illumination methods of measurement of emission decay of fluorescent polymer fibers

The fluorescence decay constant of a fluorescent polymer optical fiber is measured by two different side illumination methods. Comparative analysis of these methods is performed. It is shown that the difference in the measured parameters is caused by different conditions of energy exchange between the core, cladding, and radiation modes of the fiber waveguide.     

大尺度相干结构的光学特性研究

根据大气近地面层对流湍池的实验结果,提出了一种用于描述大尺度相干结构的立体模型——椭球结构模型。计算并分析了该大尺度相干结构对光传输波前相位结构函数的影响,且和小尺度湍流结构作了比较。对于相同的参数,光线平行于间断面时造成的影响大于垂直于间断面;一般情况下,影响都很小;但当光线平行穿过具有三角波模型结构的间断面时可能产生较大的影响。     

Study of field dependence of magnetoresistance of polycrystalline perovskite manganites

The field dependence of magnetoresistance in polycrystalline perovskite manganites is studied. It is found that there are two kinds of conduction channels. One is insulating channel, in which the spin-polarized tunneling affects the magnetotransport, the other is metallic, where the spin-dependent scattering dominates. The increase of metallic channels in the high external magnetic field, which is due to the reorientation of disorder spins at the interface, is assumed determinant to the continuous decrease of resistance. Within our theoretic model, the magnetoresistance of the systems with different grain size and different intergrain connectivity can be well explained. Our calculations agree with the experimental data well.     

粉末颗粒气力加注特性实验研究

粉末发动机是以粉末颗粒为燃料的新型发动机,具有多次起动和推力调节的功能.粉末加注是粉末发动机实验组织过程中的重要环节.本研究通过搭建粉末供应系统开展粉末气力加注实验,研究对比了集粉箱加注位置、流化气量对粉末气力加注特性的影响.考虑了供粉过程中储箱内粉末堆积密度的动态变化,并建立了相应的计算方法,同时还采用控制系统理论揭示了储箱内粉末堆积密度的变化规律.结果表明:在相同条件下,较大的流化气量有利于加注过程稳定,但集粉箱加注率较低;气力加注方式下集粉箱内的粉末堆积密度大于储箱内初始堆积密度;采用较小的流化气量与集粉箱壁面切向加注方式有利于提高粉末粒径分布均匀性;集粉箱壁面切向加注方式下,流化气量较小时储箱内粉末的堆积密度是先增大后减小,且堆积密度最终值小于初始值,而流化气量较大时,储箱内粉末的堆积密度是先增大后减小再增大后减小,且堆积密度最终值大于初始值;储箱内粉末堆积密度的动态变化过程类似于欠阻尼二阶系统,流化气量较小时系统阻尼系数较小,而流化气量较大时系统阻尼系数较大,且是一个变阻尼过程.     

Dependence of the characteristics of bubbles on types of sonochemical reactors

Computer simulations of bubble oscillations in liquid water irradiated by an ultrasonic wave have revealed that the characteristic of bubbles depends on types of sonochemical reactors: a horn-type reactor and a standing-wave type reactor. When the acoustic amplitude is large at 20 kHz, the bubble content is mostly water vapor even at the end of the bubble collapse and the temperature inside a bubble at the collapse is relatively low. On the other hand, when the acoustic amplitude is relatively low, the bubble content is mostly noncondensable gas at the end of the bubble collapse and the bubble temperature is relatively high. In a horn-type sonochemical reactor, the former type of bubbles are dominant because many bubbles exist near the horn-tip where the acoustic amplitude is large, while in a standing-wave type reactor the latter type of bubbles are dominant because the Bjerknes force gathers bubbles at a region where acoustic amplitude is relatively low.     

类胡萝卜素的分子光谱研究

类胡萝卜素是含有9个CC共轭双键的短链多烯类生物分子. 特殊的分子结构, 使其不仅在光采集, 光防护, 防癌, 抗癌等生物学领域有重要应用, 而且在分子导线, 光开关, 滤光器等光电器件研制中也有重要的非生物学应用. 本文对它的分子光谱进行研究和总结, 结果表明, 类胡萝卜素具有宽带荧光, 将其用于荧光增强受激拉曼散射可以获得宽带受激拉曼散射; 电子能隙随温度降低而收缩, 电子吸收光谱红移, 这特性使它能研制优质半导体元件; 极大的拉曼活性和三阶非线性系数, CC键基频拉曼散射截面可以比普通分子大10个数量级, 和频、倍频拉曼散射强度也很高, 低温下与基频强度比可达0.5. 类胡萝卜素分子的这些光谱特性对多烯类分子结构、性能研究及其在非生物学中的应用有重要参数价值.     

冷却储存环主环磁铁的准直测量

采用激光跟踪仪及配套带软件Insight对兰州重离子加速器冷却储存环主环磁铁进行了安装和准直。首先建立全局坐标系，用来确定从源体到实验环各子系统的理论原点的位置；而各个子系统又分别以各自的理论原点为基础建立局部坐标系，用来安装定位本系统内的各个元件；对各个子系统中的每一个元件还采用了元件坐标系。准直测量时，先在每块磁铁上焊接8个测量基准；然后对磁铁上的基准进行测量，以确定其在元件坐标系中的位置；再架设激光跟踪仪，测量主环控制网点，恢复主环局部坐标系，根据元件在主环局部坐标系中的位置及理论坐标，计算出相关的变换参数；转入元件坐标系，采用激光跟踪仪及Insight 软件显示实时测量坐标及其与理论值之差，其精度达到0.15 mm。     

混合物物态方程的计算

 在采用体积相加原理计算混合物物态方程的基础上,建立了一种物理模型确定混合物温度。根据混合物中各组分温度和压强平衡条件,采用压强-密度迭代方法计算给出混合物物态方程,编制了两种组分的混合物物态方程计算程序。为检验建立的温度模型的合理性及程序的有效性,分析了不同密度、温度状态的氢（H2）和钨（W）组成的混合物状态参量,计算了以下情形及其组合情形的混合物物态方程：H₂和W以不同质量比混合;质量比固定,单组分状态不同;温度区间和密度区间不同。研究表明:实际应用中在建立的混合物温度模型基础上确定的混合物物态方程是合理的。     

Quantative measure of efficiency of Monte Carlo simulations

An easily applied, physically motivated algorithm for determining the efficiency of Monte Carlo simulations is introduced. The theoretical basis for the algorithm is developed. As an illustration we apply the method to the Lennard-Jones liquid near the triple point. We show that an acceptance ratio of 0.2 is twice as efficient for the purpose of generating a satisfactory sample as is an acceptance ratio of 0.5. There is a strong correlation between the efficiency measure and the diffusion rate of liquid particles during the simulation. We argue that the optimal value of the acceptance ratio is calculable from short Monte Carlo simulations. The method is very general and is applicable to Monte Carlo simulations involving arbitrary potentials.     

Analysis of Calculation of the Critical Temperature of Metals

General considerations on the form of the real equation of state make it possible to assume that the ratio of the melting temperature to the critical temperature is constant for each group of elements. This assumption is verified for two groups of elements, the critical temperatures of which are measured. It is shown that, for certain groups of elements, the critical temperatures of which are calculated instead of being measured, this assumption is also valid. The critical temperatures of certain elements are calculated or refined.     

Analysis of distribution of partially polarized light

A new method for characterization of the distribution of the partially polarized light is described. Analysis of distribution is based on three dimensional radial distribution function. The radial distribution function is useful method of determining type of the distribution of partially polarized light. For uniformity analysis of the distribution method which is based on calculation of the correlation coefficient is presented.