The use of energy and co-energy for the evaluation of forces in non-linear, anisotropic dielectric solids

In this paper, in spite of the wide diffusion of the method that makes use of suitable variations of the electric energy (or co-energy) for computing forces in non-linear, anisotropic dielectric solids, it is shown that the arguments generally developed to justify this approach are, in reality, unsound. A rigorous proof of the correctness of the method is provided. It is shown also that the method is frequently used in cases where it fails; to this end, the limitations of the method itself are pointed out. Received 13 December 1999     

Application of CW local correction approach to SLW modeling of radiative transfer in non-isothermal gaseous media

The solution of the RTE equation in non-isothermal media by the SLW method is handled with the help of the local correction factor instead of the traditionally used so-called reference approach. Two methods of calculation of the correction factor are shown: one is based on the cumulative wavenumber (CW) distribution function developed with the HITEMP spectroscopic data; the other method uses the relationship between the reordered wavenumber and cumulative wavenumber. It is shown how this method is applied to different forms of the partition of absorption cross-section into gray gases. Further, it is shown theoretically that this method approaches the exact solution for non-isothermal media in the limit as the number of gray gases tends to infinity.     

Quantitative estimation of ultrasonic attenuation in a solid in the immersion case with correction of diffraction effects

This paper presents a method of diffraction correction for the log-spectral difference method to estimate quantitatively attenuation of a solid in the immersion case. The correction method is established based on the angular spectrum approach that is used to calculate the echoes from the front and back surfaces of the immersed solid. An example is given of a copper plate submerged in water and inspected by a linear array with a cylindrically curved surface. The correction method is first applied to a theoretical estimation of attenuation which is linearly dependent on frequency. The results have shown that the evaluated attenuation coefficient is in excellent agreement with the exact value. Then the method is applied to a real situation, in which the results have shown that the method yields reasonable evaluated attenuation values. This work has demonstrated that the method is able to correct effectively the diffraction effect so as to achieve a quantitative estimation of attenuation.     

AN ANALYTICAL INVESTIGATION OF THE DIRECT MEASUREMENT METHOD OF ESTIMATING THE ACOUSTIC IMPEDANCE OF A TIME-VARYING SOURCE

This paper presents an analytical investigation of the direct method of measurement of the source impedance of a linear time-variant source. The direct method yields a frequency-dependent effective source impedance which is routinely used in a time-invariant analysis to determine the insertion loss of two different acoustic loads applied to the same source. In such an analysis the strength of the source is assumed to be invariant with load. It is shown here that there is generally no precise correspondence between the effective source impedance as given by the direct method and the characteristics of the actual source. Furthermore, it is shown that the effective source impedance values given by the direct method are functions of the acoustic load and the location of the injected signal as used in the measurement. However, the effective source resistance is always found to be positive, in accordance with experimental measurements. In this regard the direct method is an improvement on the indirect method, where physically implausible negative resistance values are often found. Finally, it is shown that the effective impedance values as given by the direct method when used with a time-invariant analysis give rise to very accurate predictions of insertion loss, even when the strength of the actual time-variant source is allowed to vary with the acoustic load.     

Conventionality in distant simultaneity

The paper defends the thesis of conventionality in distant simultaneity within the special theory of relativity. The thesis can be expressed in the following way: There is no method independent of standard synchronization by which the one-way velocity of light can be measured if all empirical consequences of the special theory of relativity are to be accepted. Three methods which have recently been suggested are investigated. It is shown that they all depend on the method of standard synchronization. It is finally claimed that nobody has suggested a method which cannot be shown to depend on the method of standard synchronization.     

A refined method for estimating fiber and interfacial shear strength by using a single-fiber composite

In estimating interfacial shear strength from the fragmentation process of fibers in single-fiber composites, a problem arises as to the value of the fiber strength if the fiber strengths distribute widely and strongly depend on the fiber length. To overcome this problem, a refined analysis method for simultaneously estimating the fiber and the interfacial shear strength from the fragmentation process has been shown. Agreements between the values estimated with the proposed method and the results of the single-fiber tensile and the direct shear tests have been obtained. It has been shown that the estimation of the interfacial shear strength using the proposed method is insensitive to the matrix properties if the interfacial shear strength is unaltered by the matrix properties, and that the variations of the distribution parameters of the fiber strength is significantly smaller for the proposed method as compared with the single-fiber tensile tests. The results obtained by applying the proposed method to various carbon fibers have been shown.     

IMPACT DAMPING WITH GRANULAR MATERIALS IN A HORIZONTALLY VIBRATING SYSTEM

The damping efficiency of an impact damper with granular materials in a horizontally vibrating system is investigated by means of the discrete element method. This method makes it possible to consider effects of granularity such as the particle size, number of particles and friction between two particles. The validity of this numerical method is examined by a comparison of the experimental results. It is shown that the mass ratio, particle size and cavity dimensions influence the damping performance. It is also shown that the cavity dimensions and the particle radius affect the behavior of the granular materials.     

Reception plate method for characterisation of structure-borne sound sources in buildings: Installed power and sound pressure from laboratory data

In a companion paper, a laboratory method is described to obtain the structure-borne sound power of machines before they are installed in heavy-weight buildings. The laboratory method is based on the concept of the reception plate. In this paper, the method is shown to provide appropriate input data for the prediction of the installed structure-borne power, and thence the resultant sound pressure level in rooms removed from the room containing the machine. Case studies of two common sources are described: a whirlpool bath and a water cistern. It is shown that the method can be incorporated into recently proposed standard prediction models and that sound pressure levels in buildings can be predicted.     

Suprathermal electrons in a laser-heated plasma: A theoretical temperature relationship

It is shown that the detection of 511 keV photons provides a simple and direct method for relating the total number of suprathermal electrons in a laser-heated plasma to the temperature of the suprathermal electrons. Furthermore, it is shown that this method clearly differentiates between the thermal and suprathermal electron populations in contrast to X-ray methods. An explicit relationship between the number of suprathermal electrons, the suprathermal temperature, and the number of 511 keV photons is derived.     

Resonance Fluorescence in Two—Photon JC Models Analyzed by Supersymmetric Transformation

Resonance fluorescences of two-photon two-level and two-photon three-level atoms driven by laser are investigated with supersymmetric transformation.It is shown that the spectrum of fluorescent light obtained from the supersymmetric transformation is more accurate and the physical process shown by this method is clearer than that from dress transformation.     

Free vibration analysis of cantilever plates by the method of superposition

The method of superposition is employed to analyze the first five symmetric and antisymmetric free vibration modes of a cantilever plate for a wide range of aspect ratios. It is shown that this method provides a simple, straightforward and highly accurate means of solution for this family of problems. Convergence to exact values is shown to be remarkably rapid. The first two symmetric and antisymmetric modal shapes for a square plate are accurately described by means of contour line drawings. The numerous advantages of this method over previously used methods are discussed. It is shown that it lends itself readily to the entire family of rectangular plates with classical edge conditions: i.e., clamped, simply supported, and free. Its applicability to a wide family of rectangular plates with boundary conditions other than the classical type is also discussed.     

基于CT切片特征匹配的三维体重建

详细描述了医学解剖学切片图数据读取,特征提取和特征匹配.引入了解剖数据读取方法,叙述了切片匹配的两个过程:特征提取和特征匹配.提出了一种新的有效的特征匹配方法.所有切片图象在匹配之前首先进行了预处理(如滤波、二值化、细化等过程),特征是分区域进行提取的.匹配方法分两步,首先按照对应特征点之间距离的方法匹配特征点,然后用矩的方法进行切片之间匹配.体重建过程中还使用了三维等值面和插值方法.实验结果证实这种特征匹配方法不仅快速而且准确.     

On the Hamilton-Jacobi Treatment of Constrained Systems

Systems with singular-higher order Lagrangians are investigated by two methods: Dirac method and Hamilton-Jacobi method. An example is studied and it is shown that the Hamilton-Jacobi method gives the correct canonical generalized equations of motion, contrary to Dirac method, where Dirac conjecture is invalid.     

Unitary representations of the Virasoro and super-Virasoro algebras

It is shown that a method previously given for constructing representations of the Virasoro algebra out of representations of affine Kac-Moody algebras yields the full discrete series of highest weight irreducible representations of the Virasoro algebra. The corresponding method for the super-Virasoro algebras (i.e. the Neveu-Schwarz and Ramond algebras) is described in detail and shown to yield the full discrete series of irreducible highest weight representations.     

Convergence criteria for the Hartree iterative solution of the general self-consistent field equations

The traditional Hartree method of solving the Hartree-Fock equations, by repeated diagonalization and recalculation of the single-particle Hamiltonian, is expressed in terms of repeated unitary transformations and shown to be applicable to the general SCF (self-consistent field) equations. The necessary and sufficient conditions for convergence to a unique local SCF solution are derived and it is shown that only a small class of solutions are obtainable by this method.     

The HN method for half-space Albedo and constant source problems for isotropic and anisotropic scattering kernels

The H_N method, which is developed recently, is used to solve the half-space albedo and the half-space constant source problems for both isotropic and extremely anisotropic scattering kernels. It has been shown that the method solves the problems in a concise manner and leads to fast converging numerical results as shown in tables.     

Abel Chern-Simons项与复标量场耦合系统的正则量子化

应用Faddeev-Jackiw方法对Abel Chern-Simons项与复标量场耦合系统进行正则量子化,它表明用这种方法进行量子化更加直接和优美.     

非晶态物质衍射数据标准化的一种新方法

对干涉函数i(s)进行稍微不同的衰减而得到的两条RDF/r曲线的交点,在径向距离r较小的区域内,应在-4πrρ₀直线。以此为判据检验其他方法得到的标准化因子K,精度可达1％。 关键词：     

射频驱动具有平方阻尼项的Josephson结混沌起始阈值的研究

本文将运用Melnikov方法求得的射频驱动、具有平方阻尼项的Josephson结参数空间中混沌起始阈值与数值计算结果进行对照。研究表明,Melnikov方法所预测的混沌区域仅占据很窄的射频幅值范围,且是位相锁定的混沌态,而实验观测的混沌位于较大的射频幅值,为非位相锁定的混沌。