Impact on short length bars

A finite element method for the solution of an axisymmetric wave propagation problem of a bar of finite length is proposed. The results are obtained for a uniform bar with (i) a displacement input and (ii) a stress input. Also results are obtained for a discontinuous bar with stress input. They are compared with the existing finite difference solutions and experimental results. It is observed that the results are in close agreement. The study is then extended to the case of bars with an hemispherical end. The advantage of using the finite element method for such problems is indicated. Finally the results for a composite bar comprising a hallow cylinder and hemisphere are obtained by using the finite element method. Experiments are conducted to verify these results.     

Energy Spectrum of the Relativistic Duffin-Kemmer-Petiau Equation

The bound state energy eigenvalues for the relativistic DKP oscillator and DKP Coulomb potentials are determined by using an exact quantization rule. The corresponding eigenfunctions are also obtained. The results are consistent with those obtained by others methods.     

High-dimensional Kuramoto model limited on smooth curved surfaces

In this Letter, a high-dimensional Kuramoto model limited on smooth curved surfaces is established. Some synchronization phenomena of this new model are displayed by simulations. A necessary and sufficient condition of equilibria is obtained and the linearized system around an equilibrium is derived. As the considered smooth curved surface is an ellipsoid, some dynamical properties including limit behavior and instability are obtained. Based on those results, almost global synchronization is achieved for the high-dimensional Kuramoto model limited on ellipsoids with complete or tree graphs. Moreover, numerical simulations are given to validate the obtained theoretical results.     

Radiation transfer with synthetic scattering phase function

Equations connecting the relation between the reflection and transmission functions for a finite slab and those of an infinite one are obtained in terms of an operator which satisfies a semigroup. In trying to calculate the infinite medium reflection function, we use a synthetic scattering function to approximate the Henyey-Greenstein scattering law. Numerical calculations are done and compared with the results obtained from different scattering functions used by other authors. Good results are obtained, especially for |c?1| ?i1 and for τ>1. The deviation in some results is due to the effect of back-scattering.     

Acoustical source characterization studies on a multi-cylinder engine exhaust system

It is well known that the characterization of the acoustic source in an exhaust muffler system is of utmost importance in the proper evaluation of the acoustic performance of the muffler. However, in the literature, there are very few experimental studies on source characterization of a multi-cylinder internal combustion engine. This paper describes the use of a transfer function method (with a random excitation source) for measurement of the internal source impedance of an eight-cylinder engine under running conditions. The results obtained agree well with those obtained by the standing wave method by earlier investigators. The studies include the effect on the measured internal source impedance caused by variation of engine speed and load. The source impedance results obtained for the engine in operation are compared with those for the engine not in operation. The use of these results in the overall modeling of the exhaust system is described in an accompanying paper.     

Ordered HGMS filters in the transverse configuration

A numerical solution for the Navier-Stokes equation is obtained for the flow conditions in an ordered high-gradient magnetic filter. Hence, capture efficiencies are calculated for this filter operated in the transverse configuration, with field, flow, and collector-wire axis mutually perpendicular. Good agreement with experiment is obtained over a wide range of filter parameters. Comparisons are made with results obtained by other models.     

A rotating arc gas pump for circuit breaking and other applications

A rotating arc circuit breaker is described which uses an auxiliary current source to generate the magnetic field for driving the arc. Test results obtained using optical fiber measurement systems have shown that there are three main arcing phases. Initially the arc rotates at an essentially constant but low velocity, subsequently its velocity oscillates between this and much higher values, and finally the are plasma may become diffuse in nature. Test results obtained with dielectric strength probes have indicated that a unidirectional flow of arc heated gas is generated. The flow is away from the moving contact of the interrupter so promoting good dielectric strength in this critical contact region. The combination of the optical fiber and dielectric probe results indicates two possible modes of gas pumping represented, respectively, by a fan and a piston-type action of the arc. Simplified analytical models for both modes are developed with predictions obtained showing good agreement with the experimental results. Discussion of experimental results suggests that the transition from oscillatory velocity changes to diffuse arcing represents an important parameter for scaling the geometries of future interrupters and arc heaters     

Gauge theories on a simplicial lattice

We present various results obtained for pure gauge theories built on a simplicial lattice, an alternative to the almost always used hypercubical lattice. The main interest is to lead to shorter calculations, with more rapid thermalization of the Monte Carlo simulations. Our results are quite similar to those obtained with hypercubical lattices.     

X-rays from accreting neutron stars

The paper gives an overall picture of accreting neutron stars as obtained from X-ray observations. Theories of X-ray binaries, accreting processes, and X-ray emission mechanisms are reviewed to give qualitative understanding of physics relevant to X-rays from accreting neutron stars. Some quantitative results under simplified conditions are given for the application to the interpretation of observational results. Recent results obtained by Japanese X-ray astronomy satellites HAKUCHO and TENMA are presented in comparison with theoretical models.     

611.8 nm single-mode He-Ne laser

The conditions for optimum 611.8 nm laser operation are obtained and a convenient method for indicating 3.39 µm suppression is proposed. Single longitudinal mode 611.8 nm generation is obtained using higher gas-mixture pressure and application of an axial magnetic field. Several milliwatt monomode output power and 0.75 multimode-to-monomode power conversion coefficients are obtained without an internal iodine cell. A comparison of the experimental results with a single-mode laser theory is given.     

A simulation model for ultrasonic pulse-echo systems

Echo patterns obtained by using an ultrasonic pulse-echo system are mainly determined by the structure of an object, but are influenced by many other factors such as the directivity and damping characteristics of the ultrasonic transducer, the dynamic range of the display unit and so on. A simulation model has been developed in which if these factors are specified numerically and fed to the simulator, then an A- or B-mode display pattern is obtained as its output. In this paper the principles of the simulator are presented first and some results of the simulation are given and they are compared with echo patterns obtained experimentally.     

The Baikal Neutrino Telescope

We review the present status of the Baikal Neutrino Experiment and present results of a search for upward-going atmospheric neutrinos and magnetic monopoles obtained with the detector NT200. The results of a search for very high energy neutrinos are presented and an upper limit on the extraterrestrial diffuse neutrino flux is obtained. We describe the strategy of upgrading the NT200 to NT200+ and creating a detector on the Gigaton scale at Lake Baikal. The first results obtained with the new NT200+ detector as a basic cell of a future Gigaton detector are presented. The text was submitted by the authors in English.     

Approximate analytical solutions of the effective mass Dirac equation for the generalized Hulthén potential with any <Emphasis Type="Italic">κ</Emphasis>-value

The Dirac equation, with position-dependent mass, is solved approximately for the generalized Hulthén potential with any spin-orbit quantum number κ. Solutions are obtained by using an appropriate coordinate transformation, reducing the effective mass Dirac equation to a Schrödinger-like differential equation. The Nikiforov-Uvarov method is used in the calculations to obtain energy eigenvalues and the corresponding wave functions. Numerical results are compared with those given in the literature. Analytical results are also obtained for the case of constant mass and the results are in good agreement with the literature.     

Dependence of negative photoconductivity in organic liquids on the illumination intensity and potential difference

Results of an experimental study on negative photoconductivity in organic liquid semiconductors are described. It was found that the volt-ampere characteristics are linear, but the illumination-ampere characteristics increase in a complicated manner, approaching a hyperbola for sufficiently large light intensities. The experimental results are considered on the basis of previously developed models according to which light absorption (ascertained spectroscopically) results in an electron freed from a fixed metastable site, which then recombines with a hole, resulting in a decreased conductivity in the specimen. Graphs, obtained experimentally, are successfully interpreted by equations obtained on the basis of these models.     

SPH方法气-液界面边界条件研究

针对界面附近粒子光滑函数截断和非物理穿透问题,提出一种气-液界面边界条件的处理方法.当界面附近支持域出现不同材料粒子,每步计算可在支持域设置虚粒子,按照密度分配方法给虚粒子物理量赋值,并对界面附近粒子引入气-液两相阻力.采用SPH方法和Level-Set方法,计算运动激波对气-液界面作用问题,两者计算结果一致,初步验证了气-液界面边界条件处理的适用性.用SPH方法分别计算超声速气流中的圆截面液柱绕流和下落问题,界面两侧粒子压力和法向速度连续,给出弓形激波、回流区和下游回流区等定性合理结果.表明本文方法可适度避免界面附近流体粒子光滑截断和粒子非物理穿透现象、界面附近流场数值振荡.     

Enhancement of harmonic generation by Fresnel-lensing effects

We present experimental results of enhanced second- and third-harmonic generation efficiency from Fresnel-lensing effects. We obtained enhancement by a factor of 6 in the third-harmonic yield by simply limiting the laser beam with an iris. Higher enhancement factors (up to 16) were obtained with a Fresnel zone plate. The experimental findings are in good agreement with the results of a simple theoretical analysis.     

Exact analytic solutions for an elliptic hole with asymmetric collinear cracks in a one-dimensional hexagonal quasi-crystal

Using the complex variable function method and the technique of conformal mapping, the anti-plane shear problem of an elliptic hole with asymmetric colfinear cracks in a one-dimensional hexagonal quasi-crystal is solved, and the exact analytic solutions of the stress intensity factors （SIFs） for mode Ⅲ problem are obtained. Under the limiting conditions, the present results reduce to the Griffith crack and many new results obtained as well, such as the circular hole with asymmetric collinear cracks, the elliptic hole with a straight crack, the mode T crack, the cross crack and so on. As far as the phonon field is concerned, these results, which play an important role in many practical and theoretical applications, are shown to be in good agreement with the classical results.     

Shock compression of solid deuterium

Experimental data on the compression of solid deuterium at a pressure of ～60 GPa are presented. The data were obtained on a generator of powerful converging spherical shock waves. The results are compared with the data of shock experiments obtained on a Nova laser facility and an electrodynamic EPBF-Z plant.     

Comparisons of Performances of a Flat Tube Bank Fin Model Mounted Vortex Generators and the Real Heat Exchanger

Abstract

In this article, we compared the model results obtained by the naphthalene sublimation method with the results obtained by experiments with the real heat exchanger based on the model used in the naphthalene sublimation experiment. The results reveal that in the Reynolds number region studied in the present article, the experimental results obtained by naphthalene sublimation agree with the experimental data of the real heat exchanger under the working conditions within a 10% deviation. The heat/mass transfer coefficient obtained with an isothermal condition using naphthalene sublimation can be applied to the mixed thermal boundary condition. The effects of mounted and punched vortex generators on thermal-hydraulic performances are limited to the configuration studied in this article.     

Update of Prior Probabilities by Minimal Divergence

The present paper investigates the update of an empirical probability distribution with the results of a new set of observations. The update reproduces the new observations and interpolates using prior information. The optimal update is obtained by minimizing either the Hellinger distance or the quadratic Bregman divergence. The results obtained by the two methods differ. Updates with information about conditional probabilities are considered as well.