Energy basis via decoherence

The question of the emergence of a preferred basis which is generally understood as that basis in which the reduced density matrix is driven to a diagonal (classically interpretable) form via environment induced decoherence is addressed. The exact solutions of the Caldeira-Leggett Master Equation are analyzed for a free particle and a harmonic oscillator system. In both cases, we see that the reduced density matrix is driven diagonal in the energy basis, which is momentum for the free particle and the number states for the harmonic oscillator. This seems to single out the energy basis as the preferred basis which is contrary to the general notion that it is the position basis which is selected since the coupling to the environment is via the position coordinates     

Solitary wave solutions for nonlinear Schrödinger equation with non-polynomial nonlinearity

A new kind of non-polynomial nonlinearity is introduced in the nonlinear Schrödinger equation (NLSE) and the conditions are determined for which it admits solitary wave solutions. The study is done for two cases: one in which the nonlinear interaction is of the non-polynomial form and second in which cubic nonlinearity is also included along with the radical nonlinearity. Dark and bright solitary waves solutions are obtained in the respective cases. Further, later case is extended to conditions for which corresponding equation reduces to driven quadratic-cubic NLSE possessing cnoidal solutions with plane wave phase, which reduces to bright soliton for a certain parameter.     

SHER-HIAF ring lattice design

The Super Heavy Experimental Ring （SHER）, which is one of the rings of the next accelerator complex High Intensity Heavy Ion Accelerator Facility （HIAF） at IMP, has to be optimized for e-cooling. Its lattice is designed for two modes： the first is the isochronous mode, which is a time-of-flight mass spectrometer for short-lived secondary nuclei, the second is the storage ring mode, which is used for collecting and cooling the secondary rare isotope beams from the transport line. In order to fulfil its purpose, the ion optics can be set to different ion optical modes.     

A General Theory of Non-Abelian Electrodynamics

The general theory of gauge fields is used to develop a theory of electrodynamics in which the fundamental structure is non-Abelian and in which the internal gauge field symmetry is O(3), based on the existence of circular polarization and the third Stokes parameter. The theory is used to provide an explanation for the Sagnac effect with platform at rest and in motion. The Sagnac formula is obtained by considering the platform in motion to be a gauge transformation. The topological phases can be described straightforwardly with non Abelian electrodynamics, which produces a novel magnetic field component for all types of radiation, a component which is proportional to the third Stokes parameter. The theory provides a natural explanation for the inverse Faraday effect without phenomenology.     

SHER-HIAF ring lattice design

The Super Heavy Experimental Ring (SHER), which is one of the rings of the next accelerator complex High Intensity Heavy Ion Accelerator Facility (HIAF) at IMP, has to be optimized for e-cooling. Its lattice is designed for two modes: the first is the isochronous mode, which is a time-of-flight mass spectrometer for short-lived secondary nuclei, the second is the storage ring mode, which is used for collecting and cooling the secondary rare isotope beams from the transport line. In order to fulfil its purpose, the ion optics can be set to different ion optical modes.     

A Complex Network Model for Analyzing Railway Accidents Based on the Maximal Information Coefficient

It is an important issue to identify important influencing factors in railway accident analysis. In this paper, employing the good measure of dependence for two-variable relationships, the maximal information coefficient (MIC), which can capture a wide range of associations, a complex network model for railway accident analysis is designed in which nodes denote factors of railway accidents and edges are generated between two factors of which MIC values are larger than or equal to the dependent criterion. The variety of network structure is studied. As the increasing of the dependent criterion, the network becomes to an approximate scale-free network. Moreover, employing the proposed network, important influencing factors are identified. And we find that the annual track density-gross tonnage factor is an important factor which is a cut vertex when the dependent criterion is equal to 0.3. From the network, it is found that the railway development is unbalanced for different states which is consistent with the fact.     

Quark-gluon amplitudes in the dual expansion

The dual representation, which gives a simple analytical form for purely gluonic amplitudes, is extended to amplitudes which include a quark-antiquark pair. To minimize the calculations, supersymmetry is used to relate the purely gluonic amplitudes to those including a gluino pair from which the quark-antiquark amplitudes are easily deduced. We explicitly give simple analytical forms for the full amplitudes for those multi-parton processes which involve a quark-antiquark pair plus two, three and four gluons.     

硅基发光材料研究进展

微电子技术是高技术中的关键技术，硅是微电子技术的基础材料，但是硅是一种非发光材料，为了发展光电集成技术，必须大力发展硅基发光材料，多孔硅是一种有希望的硅基发光材料，它表明纳米晶粒中的量子限制效应对光发射是极有效的，随之涌现出一系列量子限制硅基发光材料，为发展光电子集成提供了新的途径。     

Deriving Internal Energy by Virtue of Generalized Feynman-Hellmann Theorem for Mixed States

We show how to directly use the generalized Feynman-Hellmann theorem, which is suitable for mixed state ensemble average, to derive the internal energy of Hamiltonian systems. A concrete example, which is a two coupled harminic oscillators, is used for elucidating our approach.     

Cartesian Dynamics of Simple Molecules I Diatomics and Centrosymmetric Triatomics

A simple spring model for molecular vibrations is described in which Cartesian co-ordinates are used for both longitudinal and transverse displacements. The transverse restoring forces are shown to be electrostatic in origin and much weaker than the elastic longitudinal forces. The technique is applied to diatomic and centrosymmetric triatomic molecules. In the latter case, an analytical expression for the bending mode frequency is obtained which is equivalent to that derived by conventional methods using bending constants and internal co-ordinates. The model offers certain advantages when applied to the dynamics of crystals, for which Cartesian co-ordinates, aligned with the unit cell axes, are the natural choice. Reference is made to recent work on molecular and ionic crystals using extensions of this model.     

Improvement of the average action

We propose an improvement for the average action which helps to decouple particles with heavy masses. Comparison is made with various other formulations for effective actions for which the short distance degrees of freedom are integrated out. In particular, the improved average action is closely related to a scale-dependent effective action for which an exact evolution equation was found recently.     

The influence of the stoichiometry on the Eu nuclear spin-spin relaxation in EuO single crystals

The ¹⁵³Eu spin-spin relaxation for two spherical EuO single crystals of different composition has been measured for two saturating field values of 2 and 6 T. The relaxation can be described by two time constants, a short one increasing with the magnetic field, arising from the Suhl-Nakamura coupling and a long one, due to the dipolar coupling, which is field independent. It is shown that the number of nuclei which are relaxed due to the dipolar coupling increases at increasing magnetic fields, in agreement with the Suhl-Nakamura theory. For the sample which is nearly stoichiometric the relative number of nuclei which is relaxed due to the SN coupling is much larger than for the sample which contains an excess of Eu atoms.     

Melting curves of FCC-metals by cell-theory

The cell model is developed to account for many body interaction effects, as occurring in the embedded atom method (EAM) potentials, and crystal lattice features to determine the free energy of FCC metals. The well known smearing approximation, which is generally used in conjunction with pair potentials, is also developed for EAM potentials. The free energy so obtained is used to determine melting curves of FCC metals. For this purpose, the liquid phase free energy is calculated using the corrected rigid spheres model. The advantage of our scheme, which is verified with data on Lennard-Jones solids, is that both free energies are based on the same interaction potential. Results match well with the available experimental/theoretical data for Al and Cu. A good agreement is also found for the transition metals, Ni and Pt, for which molecular dynamics as well as theories like Lindemann's law do not give accurate results. It is also found that smearing approximation, which neglects interactions beyond nearest neighbors, also provides good estimates for free energy if many body effects are accounted with EAM potential.     

Multiple scattering in the high-frequency limit with second-order shadowing function from 2D anisotropic rough dielectric surfaces: I. Theoretical study

In this paper the first- and second-order Kirchhoff approximation is applied to study the backscattering enhancement phenomenon, which appears when the surface rms slope is greater than 0.5. The formulation is reduced to the geometric optics approximation in which the second-order illumination function is taken into account. This study is developed for a two-dimensional (2D) anisotropic stationary rough dielectric surface and for any surface slope and height distributions assumed to be statistically even. Using the Weyl representation of the Green function (which introduces an absolute value over the surface elevation in the phase term), the incoherent scattering coefficient under the stationary phase assumption is expressed as the sum of three terms. The incoherent scattering coefficient then requires the numerical computation of a ten- dimensional integral. To reduce the number of numerical integrations, the geometric optics approximation is applied, which assumes that the correlation between two adjacent points is very strong. The model is then proportional to two surface slope probabilities, for which the slopes would specularly reflect the beams in the double scattering process. In addition, the slope distributions are related with each other by a propagating function, which accounts for the second-order illumination function. The companion paper is devoted to the simulation of this model and comparisons with an 'exact' numerical method.     

Application of the steiner street problem to a more economical data bus

A data bus consists of the interconnection of N terminals, each of which is connected to every other terminal. There are three fundamental approaches to the topology of the network: (1) the tee network, for which the connecting nodes coincide with the communicating nodes; (2) the star network, for which there is only one connection node, which may not coincide with a communication node; and (3) the Steiner minimal tree network, for which there can be many nodes, each of which is difficult to locate in the x-y plane. The tee and star approaches are receiving most attention but the third is the only one that economizes on the use of cable (glass fiber waveguide). After a discussion of the tee and star networks, we turn to the Steiner minimal tree network and a method of locating the connecting nodes so that the total amount of cable is minimized.     

Sound radiation from perforated plates

A practical engineering noise control measure that can often be used for plate-like structures is to construct them from perforates. This can dramatically reduce the sound radiation from such structures. Here, a prediction model is developed to quantify this effect. It is an extension of Laulagnet's model for the radiation from an unbaffled plate, which expresses the surface pressure difference as well as the plate velocity as a sum over plate modes. The perforation is included in terms of a continuously distributed surface impedance, which for moderately sized holes is predominantly inertial. Results show that the radiation efficiency reduces, not only as the perforation ratio increases but also as the hole size reduces for a given perforation ratio. Experimental validation is given which shows a good agreement with the predictions. An approximate formula is also proposed for the effect of perforation which corresponds well with the analytical calculations up to half the critical frequency and could be used for an engineering application to predict the noise reduction due to perforation. A model for the case of a perforated plate embedded in an equally perforated baffle is also discussed for comparison.     

1700 线/mm镀金光栅的拼接理论和实验研究

提出了一个能够实时地监控拼接光栅状态的方案；理论上论证了氦氖光不能用来实时监控1740线衍射光栅的光栅拼接实验；提出了一种选择监控光波长的方法，使得拼接光栅的各种误差对于主光束和监控光的影响是一致的，并且通过实验进行了验证. 关键词： 拼接光栅 刻线密度误差 实时监控 光栅对压缩池     

Multiple scattering in the high-frequency limit with second-order shadowing function from 2D anisotropic rough dielectric surfaces: I. Theoretical study

Abstract

In this paper the first- and second-order Kirchhoff approximation is applied to study the backscattering enhancement phenomenon, which appears when the surface rms slope is greater than 0.5. The formulation is reduced to the geometric optics approximation in which the second-order illumination function is taken into account. This study is developed for a two-dimensional (2D) anisotropic stationary rough dielectric surface and for any surface slope and height distributions assumed to be statistically even. Using the Weyl representation of the Green function (which introduces an absolute value over the surface elevation in the phase term), the incoherent scattering coefficient under the stationary phase assumption is expressed as the sum of three terms. The incoherent scattering coefficient then requires the numerical computation of a ten- dimensional integral. To reduce the number of numerical integrations, the geometric optics approximation is applied, which assumes that the correlation between two adjacent points is very strong. The model is then proportional to two surface slope probabilities, for which the slopes would specularly reflect the beams in the double scattering process. In addition, the slope distributions are related with each other by a propagating function, which accounts for the second-order illumination function. The companion paper is devoted to the simulation of this model and comparisons with an ‘exact’ numerical method.     

Telescope illumination and beam measurements for submillimeter astronomy

Submillimeter receivers which operate in the highest frequency atmospheric windows must still be mounted on large infrared and optical telescopes. Finding the optimum submillimeter wave illumination for these large telescopes is simplified by their effectively perfect optical surfaces and long focal lengths, but is complicated by telescope optics which have been optimized for non-tapered beams. In order to determine the effects of changing illumination edge taper, we calculated idealized aperture and beam efficiencies for telescopes which are used for submillimeter astronomical observations. The optimum illumination edge taper for the large infrared telescopes is near 10 dB, somewhat less than for classical radio telescopes, and is not very critical as long as it is between 10 and 13 dB.We also present an accurate method for measuring the sizes of, and deviations from, Gaussian beam pattern distributions by using astronomical sources which have sizes comparable with the beam.