Temperature dependence of the elastic constants of copper,gold and silver

From an inverse power type interatomic potential energy function and the Boltzmann distribution function for interatomic distances, the second-order elastic constants of copper, gold and silver are calculated as a function of temperature without involving any undetermined parameters. The results are found to be in fair to good agreement with the experimental observations in the temperature range of-196 to 25°C.     

Nonreciprocal effects in a plasma waveguide

The nonreciprocal effects in a waveguide completely filled with plasma are investigated. The basic assumptions and equations concerning the reason for the occurrence of such effects are presented. The results of the numerical calculations for different values of parameters are given. The main features of the nonreciprocal effects involving the electromagnetic waves in a plasma waveguide are summarized. It is shown that such effects exist only for nonsymmetrical waves of the HE type. Two frequency regions are found in which only one nonsymmetrical HE-mode can propagate along the field, while against the field no one mode of any type can     

A study of a 1-3-2 type piezoelectric composite

A novel 1-3-2 type piezoelectric composite is developed. There are piezoelectric ceramic framework supports at transverse and longitudinal directions in its structure, so it is free from the influence of any outside mechanic impact and environmental temperature change. The sample characteristic is good coherence. It has many advantages, such as a high piezoelectricity, lower density and acoustic impedance matching with water and tissue easily. Based on Newnham's series and parallel theory of composites, the calculation formulae of dielectric and piezoelectric constants of a 1-3-2 type piezoelectric composite are deduced. The sample's characteristics indicate that a 1-3-2 type piezoelectric composite's theoretic calculation values are in good agreement with the measurement results. Element samples have been designed, manufactured and measured. The results indicate that the resonant frequency, resonant impedance, piezoelectricity and static capacity of these samples are stable. It is easy to design sensor array elements using this material.     

Crosstalks of two-waveguide and three-waveguide directional couplers

Crosstalks of two-waveguide and three-waveguide directional couplers are analyzed mathematically based on the relationship between the coupled mode and the normal mode. Numerical techniques such as the finite-difference method and the beam propagation method are employed to confirm the validity of the derived expressions. The calculation results show that two-waveguide directional coupler is superior to any type of three-waveguide couplers from the practical viewpoint of the crosstalk and the coupling length.     

Analysis of Godunov type schemes applied to the compressible Euler system at low Mach number

We propose a theoretical framework to clearly explain the inaccuracy of Godunov type schemes applied to the compressible Euler system at low Mach number on a Cartesian mesh. In particular, we clearly explain why this inaccuracy problem concerns the 2D or 3D geometry and does not concern the 1D geometry. The theoretical arguments are based on the Hodge decomposition, on the fact that an appropriate well-prepared subspace is invariant for the linear wave equation and on the notion of first-order modified equation. This theoretical approach allows to propose a simple modification that can be applied to any colocated scheme of Godunov type or not in order to define a large class of colocated schemes accurate at low Mach number on any mesh. It also allows to justify colocated schemes that are accurate at low Mach number as, for example, the Roe–Turkel and the AUSM⁺-up schemes, and to find a link with a colocated incompressible scheme stabilized with a Brezzi–Pitkäranta type stabilization. Numerical results justify the theoretical arguments proposed in this paper.     

Induced dipole contributions to the potential in the surface region of an ionic solid

The theory of the electric potential near the surface of an ionic solid is extended to include induced dipolar effects. Numerical results are given for the {100} and {110} faces of several solids having the NaCl structure. General matrices are given which allow the determination of the dipolar contribution for any ionic solid of the NaCl type. It is shown that the contribution is small for the two surface planes considered.     

Free vibration analysis of circular cylindrical shells

A general analytical method is presented for evaluating the free vibration characteristics of a circular cylindrical shell with classical boundary conditions of any type. The solution is obtained through a direct solution procedure in which Sanders' shell equations are used with the axial modal displacements represented as simple Fourier series expressions. Stokes' transformation is exploited to obtain correct series expressions for the derivatives of the Fourier series. An explicit expression of the exact frequency equation can be obtained for any kind of boundary conditions. The accuracy of the method is checked against available data. The method is used to find the modal characteristics of the thermal liner model of the U.S. Fast Test Reactor (FTP). The numerical results obtained are compared with finite element method solutions.     

Small-amplitude solitons in nonlinear-saturation glass fibers

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Calculation of parameters of diffraction polarizers

The results of calculations of two types of reflective polarizers made up of thin-film diffraction grating formed by birefringent plane-parallel elements are presented. One of the two orthogonal linear polarizations can be separated almost without any losses because of a strong zero-order reflection. A polarizer of the first type represents a grating formed by asperities of a dielectric coating with a columnar structure produced upon oblique deposition of the dielectric. The second polarizer represents a thin mica plate grating. In this case, comparison with previous experiments can be performed.     

单次瞬态过程频谱分析仪

本文叙述了一个适用于各种单次瞬态过程的频谱分析仪的工作原理和实验结果。本仪器利用实验室现有设备(通用示波器和声频频谱仪等),经过适当组装和附加少量专用电路,可以较快地建成。利用时间扩展(或压缩)技术,可以将欲测的频谱波段移到声频波段。用光电函数发生器产生待测的瞬态过程的重复波形。这样,就可以用一般的声频频谱仪(或波分析仪)来模拟测量单次瞬态过程的频谱。实验结果证明上述方案是可行的。对主要频谱成份,测量可准确到2—3％。对较弱的频谱成份,准确度要差些。     

A quasi-free scattering model for reactions involving clusters

A master equation is used to predict spectra of the type (α, α') under the assumption that the mechanism is a quasi-free intranuclear alpha-nucleon scattering process. The treatment applied to α-clusters is general for any cluster. The parameters of the model are described, and comparisons are presented between experimental angle integrated (α, α') spectra and results of the assumed quasi-free scattering mechanism.     

Prospects for development of wind turbines with orthogonal rotor

The experimental data obtained previously on the investigation of power characteristics and the possibility of the self-start of the Darrieus rotor are anlysed. These results are used at the design of new two-tier wind turbines with straight blades. The full-scale tests of two design variants showed the prospects for the development of wind turbines with the Darrieus rotor. At a reasonable design, they do not need any devices for the rotor orientation and start-up, are little sensitive to wind gusts and can have a high level of power characteristics, which is not inferior to the best samples of the units of propeller type.     

Investigation of a method to calculate spontaneous radiation spectra from relativistic electrons in undulators

Undulators are key devices to produce brilliant synchrotron radiation at the synchrotron radiation facilities.In this paper we present a numerical computing method,including the computing program that has been developed to calculate the spontaneous radiation emitted from relativistic electrons in undulators by simulating the electrons' trajectory.The effects of electron beam emittance and energy spread have also been taken into account.Comparing with other computing methods available at present,this method has a few advantages with respect to several aspects.It can adopt any measured or arbitrarily simulated 3D magnetic field and arbitrary electron beam pattern for the calculation and it's able to analyze undulators of any type of magnetic structure.It's expected to predict precisely the practical radiation spectrum.The calculation results of a short period in-vacuum undulator and an EllipticaUy Polarized Undulator (EPU) at Shanghai Synchrotron Radiation Facility (SSRF) are presented as examples.     

Study of a Quantum Framework for Search Based Software Engineering

The Search Based Software Engineering (SBSE) is widely used in the software engineering to identify optimal solutions. The traditional methods and algorithms used in SBSE are criticized due to their high costs. In this paper, we propose a rapid modified-Grover quantum searching method for SBSE, and theoretically this method can be applied to any search-space structure and any type of searching problems.     

Bosonic colored group field theory

Bosonic colored group field theory is considered. Focusing first on dimension four, namely the colored Ooguri group field model, the main properties of Feynman graphs are studied. This leads to a theorem on optimal perturbative bounds of Feynman amplitudes in the “ultraspin” (large spin) limit. The results are generalized in any dimension. Finally, integrating out two colors we write a new representation, which could be useful for the constructive analysis of this type of models.     

A mobile test facility based on a magnetic cumulative generator to study the stability of the power plants under impact of lightning currents

The report presents the results of the development and field testing of a mobile test facility based on a helical magnetic cumulative generator (MCGTF). The system is designed for full-scale modeling of lightning currents to study the safety of power plants of any type, including nuclear power plants. Advanced technologies of high-energy physics for solving both engineering and applied problems underlie this pilot project. The energy from the magnetic cumulative generator (MCG) is transferred to a high-impedance load with high efficiency of more than 50% using pulse transformer coupling. Modeling of the dynamics of the MEG that operates in a circuit with lumped parameters allows one to apply the law of inductance output during operation of the MCG, thus providing the required front of the current pulse in the load without using any switches. The results of field testing of the MCGTF are presented for both the ground loop and the model load. The ground loop generates a load resistance of 2–4 Ω. In the tests, the ohmic resistance of the model load is 10 Ω. It is shown that the current pulse parameters recorded in the resistive-inductive load are close to the calculated values.     

Angular structure of QCD jets

We derive the angular correlation functions between an arbitary number of partons inside a quark or gluon jet emerging from a high energy hard collision. As an application results for the correlation in the relative angle between two partons as well as the multiplicity moments of any order for partons in a sidewise angular region are calculated. At asymptotic energies the distributions of rescaled angular variables approach a scaling limit of a new type with two redundant quantities. All observables reveal the power behaviour characteristic to the fully developed selfsimilar cascade in appropriate regions of phase space. We present analytical results from the double logarithmic approximation as well as Monte Carlo results.     

统一的对流扩散型可压缩流体力学方程与解法

流体力学的动量方程、能量方程、湍动能方程和耗散方程都具有对流扩散方程的形式,但连续方程却不是对流扩散型的。对于可压缩问题,本文通过合理的数学推导,不作任何近似、假定与简化,得到一个全新的连续方程形式．该连续方程以压力为未知变量,并具有对流扩散型形式,使得所有的流体动力学方程组都具有完全统一的方程形式,给出了这种三维对流扩散方程组的有限精确差分计算格式。对流体力学的进一步发展具有一定意义．     

SCF theory for excited states

Equations of Hartree-Fock type are formulated for a many-electron system described by a wave function containing any number of open and closed shells. The solutions define ‘optimal orbitals’ which minimize the average energy of the states of a configuration in which each shell contains a specified number of electrons. Analogues of the Koopmans theorem are constructed.

The results obtained are of special interest in discussing highly excited states (e.g. in ESCA and Auger spectroscopy) where ‘holes’ may be present in both inner and outer shells.     

Inhomogeneous strains in small particles

This paper considers the evidence for strains in small particles. Firstly, the dynamical electron diffraction theory for dark field imaging of small particles is briefly reviewed, considering primarily the effects of strain on wedge crystals and identifying the fingerprint of strain contrast effects under strong beam conditions. Evidence included herein and from published papers by other authors clearly shows inhomogeneous strain effects in both multiply twinned particles and single crystals. Considering these results and earlier reports of lattice parameter changes, there are problems with the uniqueness of these analyses, and the strains in the small single crystals are thought more likely to be due to interfacial stresses or contaminants than any intrinsic particle effect; there are so many different origins of this type of strain that we cannot with confidence isolate a unique source. It is emphasised that the uniqueness of any interpretation of experimental results from small particles must be very carefully considered.