Transfer of quantum correlations in nonunitary evolution

A generalized Lindblad equation has been derived for describing the evolution of two dynamical systems interacting with a bath formed by two broadband modes of squeezed light in an entangled state. The transfer of quantum correlations, in particular, entanglement between the bath and dynamic systems, which are taken in the form of two electromagnetic field modes separated by two high-Q cavities, two atoms, and an atom and a mode, has been analyzed. It has been found that the entanglement of the bath is transferred both to two modes and to two atoms, which can form an almost perfect Einstein-Podolsky-Rosen pair. It has been shown that the interaction of the bath with the system consisting of an atom and a mode for which collective boson operators are introduced leads to the appearance of coherent and squeezed states.     

判别两个或两个以上深能级是否属于同一中心的方法

本文分别研究了两个或两个以上深能级之间的耦合和非耦合两种情况所对应的光电容瞬态,根据这两种瞬态的本质差别,提出一个判别两个或两个以上深能级是否属于同一深中心的方法。它具有适用于两个以上的多个深能级的样品以及方法简单和测量时间短等优点。作为例子,将它应用于判别硅中和金有关的施主和受主两能级,结果证实它们确实是属于和金有关的同一中心,而不是分属于两个中心。 关键词：     

Metric and Ricci tensors for a certain class of space-times ofD type

The class of space-times has been determined at the connection level, assuming the existence of some symmetrical relations between the Ricci rotation coefficients. It has been assumed, for instance, that at least two shear-free congruences of null geodesics exist. We have shown that onlyD type or conformally flat space-times can belong to this class. The theorem has been proved that a system of coordinates exists in which the metric tensor can depend on two coordinates, only. The metric tensor has been determined with an accuracy to two functions, each of which is a function of only one coordinate. Linear, second-order differential expressions have been found for these two functions. They determine the Ricci tensor. Several solutions of the Einstein-Maxwell equations with a cosmological constant are given.On leave from the Institute of Theoretical Physics, Warsaw University, Warsaw, Poland.     

Two-colour operation of a Free-Electron Laser and applications in the mid-infrared

The two-colour operation of a Free-Electron Laser (FEL) has been demonstrated with the “CLIO” infrared facility. A two section undulator allows the production of picosecond laser pulses at two different wavelengths and simultaneously, in a wavelength range from to , and with a wavelength separation of two colours of up to . The time overlap, between both colours, has been measured on a picosecond time scale and on a microsecond time scale. An initial pump-probe application experiment has been performed with the two colours: stimulated emission has been measured in a 3-level Quantum-Well system. This is the best demonstration of the stability and reliability of the two-colour laser operation. Received: 4 November 1997 / Revised in final form: 31 March 1998 / Accepted: 10 April 1998     

Topotaxy in the oxidation of valentinite,Sb2O3, to cervantite,Sb2O4

The oxidation of orthorhombic Sb₂O₃, valentinite, to orthorhombic Sb₂O₄, cervantite, has been shown by single crystal x-ray diffraction techniques to be a topotactic reaction. The orientation relationships between the two lattices have been determined by making use of a hybrid crystal. It has been found that the individual axes in the two oxides are parallel. The two crystal structures have been compared in the appropriate orientation and their close similarity has been established. The shifts of the individual atoms in valentinite during the process of oxidation have been calculated to be not more than 0·6 Å. It has been established that the reduction of cervantite to valentinite also takes place topotactically.     

Flow structure investigation around two square cross-section beams under interference conditions

The dependence of the flow patterns around two prism bodies with square cross sections on the distance between them has been studied. The specific structures arising around two bluff bodies have been obtained and divided into four main types. The thermoanemometer probing in aerodynamic wake of the same two bodies has been performed and resulted in the presented dependence of Strouhal numbers on the relative distance between the investigated prisms.     

Polaronic excitations in the doped polyacene

The polyacene as two coupled chains of transpolyacetylene has been studied based on an extended SSHHubbard model. The dimerized displacement u ₀ is found to be similar to the case of trans-polyacetylene, and equals to 0.04 Å. The energy-band gap is 0.38 eV, in agreement with other authors. In particular, we have considered some cases where polyacene is doped with one and two donor electrons. In the case of doping with one electron, a polaron spreading over two chains has been found; in the case of doping with two electrons having different spins, a stable bipolaron has been obtained, which is different from the one of transpolyacetylene; in the case of doping with two electrons having the same spins, two stable polarons which spread over two chains have been found. The bound electronic states corresponding to these cases are obtained.     

High-power Raman conversion of a discharge XeCl-laser

Raman conversion of high-power discharge XeCl-laser radiation in hydrogen has been carried out. Simultaneous generation of four Stokes and two anti-Stokes outputs has been observed, every radiation line consisting of two close components, which correspond to the double structure of the pumping line.     

A comprehensive analysis of the electric field distribution in an electrodynamic screen

The electrodynamic screen, or EDS, has shown promising results in mitigation of dust accumulation losses in solar energy harvesting systems. In this paper, the electric field distributions in two EDS configurations have been thoroughly investigated. The analytical solutions for the electric potential and electric field distribution in the first EDS configuration have been provided and corroborated numerically using finite element analysis (FEA) software. The electrostatic model of second EDS configuration has been developed in the FEA software and its electric field distribution has been analyzed numerically. A comparison has been made between the two configurations regarding dust removal efficiency.     

垂直上升管中油水两相流流型辨识

基于运动波理论本文建立了垂直上升管中油水两相流运动波传播方程,计算得到了管内无仪器插入体情况下油水两相流运动波传播速度特性曲线,根据曲线特征确定了油水两相流过渡流型存在于持水率大于0.25并小于0.5区间,应用该流型辨识准则对Govier等实验观察到的油水两相流流型试验点进行了辨识,取得了较好对比效果。此外还使用Flores等击碎聚合机理性模型验证了本文的辨识流型图,并与之结合产生了更加细化的合成流型图。     

Surface potentials of interacting metallic films

An exact analytic relation between the surface potentials of two interacting metallic films has been derived in terms of their bulk properties. The relation is valid at arbitrary separation between the two films and has been compared with other available analytical and numerical results.     

Collapse mechanism of the condensate wavefunction in the Bose-Fermi mixture with attraction between the components

The ground state of the mixture of degenerate Bose and Fermi atoms in a trap has been analyzed on the basis of the effective Hamiltonian. The two types of the solutions of the modified Gross-Pitaevskii equation that correspond to the stationary and unstable states of the Bose gas have been found numerically. The chemical potential and energy are found as functions of the number of bosons for these two types of the solutions. The manyvalued character of these functions has been analyzed and the critical number of bosons at which the system collapse occurs has been determined.     

Use of heat transfer enhancement in process integration

To date, heat transfer enhancement and process integration have been two separate techniques for improving energy efficiency. It has never been assumed that the two are mutually exclusive, but no concerted effort has been made to combine them systematically. As a consequence, whilst there are many working examples showing the successful use of both techniques, there are few, if any, of the use of the two in combination. In this paper we present the means of rectifying this situation. We show how heat transfer enhancement can be effectively used in both a stand-alone and an integrated context. A systematic method for the combined use of enhancement and integration has now been developed.     

Role of surface plasmon polaritons in anomalous transmission of an electromagnetic wave through two arrays with subwavelength slits

The anomalously large transmission of an electromagnetic wave through structures consisting of two periodic arrays of subwavelength slits in films has been investigated. The conditions ensuring zero transmittance of this system have been determined. The role of surface plasmon polaritons in transmission anomalies has been analyzed. An analysis of the systems consisting of three arrays of slits has revealed specific features of the transmittance that are independent of the number of slits. It has been demonstrated that, at a wavelength corresponding to the excitation of a surface plasmon polariton in the gap between two periodic arrays of subwavelength slits, the transmittance is zero (i.e., transmission is suppressed). The investigation has been carried out using numerical simulations with the Fourier modal method.     

机械泵驱动两相回路的储液器控温策略研究

本文阐述了一种机械泵驱动两相回路的储液器的控温原理,并对待选的两种控温策略进行了解释:一种是基于电压的PI控制,另一种是基于功率的PI控制。文中将它们作了近似等效转换,并用SINDA/FLUINT软件进行模拟。结果显示:当控温点上升时,两种不同控制策略的控温效果大体一致;但当控温点下降时,由于基于功率的PI控制策略包含有Peltier的制冷功能,可以比基于电压的PI控制策略更快到达控温点。另外,基于功率的PI控制策略在死区内的跳跃更少,其应当为优先选择的控制策略。     

近红外钢轨磨耗检测中的图像处理

对近红外钢轨磨耗检测中实时图像处理方法进行了研究.在断面磨耗检测中,要获取较高精度的磨耗数值,起始点(或称坐标基准)的定位必须准确且误差小.考虑到标准钢轨轨形和实际钢轨磨耗情况,得出了起始点两种可行的定位方式,并就其中的一种用编程实现,仿真处理效果良好,所获取的两关键点的磨耗数值与实测值吻合较好.为了进行实采钢轨轨形与标准轨形的模板比较,讨论了钢轨断面图像的细化问题.这里并没有采用通常的细化算法,而是先利用Roberts算子进行图像的边缘检测,再抽取出光带中心线,大大减少了运算量,提高了运算速度,同时也满足了对轨形细化的要求.断面图像的起始点定位与轨形细化兼顾了处理精度和速度的要求,满足了本系统实时检测的要求.     

Dynamic strain measurement using two wavelength-matched fiber Bragg grating sensors interrogated by a cascaded long-period fiber grating

In this work, we describe a fiber Bragg grating (FBG) sensing system using two wavelength-matched FBG sensors for static and dynamic strain measurement. A cascaded long-period fiber grating (CLPG)-based demodulation technique has been used to interrogate the two wavelength-matched FBG sensors. Experimental results of static strain measurement show that the proposed system has a strain resolution of 1 με. This system has also been used for dynamic strain measurement. An eddy current displacement meter-based system has been used as a comparison measurement. Experimental results of dynamic strain measurement have proved that the FBG sensing system has a good performance in the measurement of dynamic strain. The results of static and dynamic strain measurement indicate that the sensing system using two wavelength-matched FBG sensors is superior to the single FBG sensor system.     

两类喇曼光纤放大器的研究

以Photonic Transmission Design Suite(PTDS)仿真试验平台为基础，对单信道40Gb／s光纤传输系统中的两类RFA进行了研究和比较，并对各自系统进行了优化．最后指出，现有的依赖DCF进行色散补偿的方法在40Gb／s光纤传输系统中不再适用．     

Heteronuclear energy pooling collisions: The Na(3P) + K(4P) reaction

An experiment has been performed in which two different atomic species - sodium and potassium - have been simultaneously excited in a cell by two resonant cw dye lasers and the fluorescence spectrum has been analysed by using an intermodulation technique to isolate the contributions due to the heteronuclear processes. The energy pooling collisions between Na(3P) and K(4P) have been observed for the first time and the relative collision cross sections have been measured.     

Enhancement of the relative visibility of the central fringe in the output of a white light interferometric system with a synthetic source

A study of the enhancement of the relative visibility of the central fringe in the output of a white light interferometric system with a synthetic source has been carried out. A theoretical analysis and an experimental investigation of the relative intensities of the central fringe in the output has been given and a comparison with the system discussed in this paper. A conventional two wavelength system has also been included. The results show that the relative intensity of the central fringe of the multiplied output is independent of the intensity ratio of the two wavelength components.