Quantum dissipative master equations: Some exact results

The results for two quantum dissipative master equations were derived with the help of quantum characterstics functions. These equations included disspative Liouvillian operators of the Lindblad type corresponding to two forms of dissipation mechanisms. The evoluton of level populations for an oscillator in a coherent state with certain displacement in undamped regime was also studied. The analysis suggested that the Hamiltonian represented the excited manifold with one primary oscillator in the Brownian oscillator model. The study also revealed that if the bath temperature was sufficiently high, the vibrational manifold could reach a Boltzmann-type distribution before it came ito full thermal equilibrium with the surrounding bath.published_or_final_versio

Trilogy on Computing Maximal Eigenpair

The eigenpair here means the twins consist of eigenvalue and its eigenvector. This paper introduces the three steps of our study on computing the maximal eigenpair. In the first two steps, we construct efficient initials for a known but dangerous algorithm, first for tridiagonal matrices and then for irreducible matrices, having nonnegative off-diagonal elements. In the third step, we present two global algorithms which are still efficient and work well for a quite large class of matrices, even complex for instance.Comment: Updated versio

An Efficient Approximate kNN Graph Method for Diffusion on Image Retrieval

The application of the diffusion in many computer vision and artificial intelligence projects has been shown to give excellent improvements in performance. One of the main bottlenecks of this technique is the quadratic growth of the kNN graph size due to the high-quantity of new connections between nodes in the graph, resulting in long computation times. Several strategies have been proposed to address this, but none are effective and efficient. Our novel technique, based on LSH projections, obtains the same performance as the exact kNN graph after diffusion, but in less time (approximately 18 times faster on a dataset of a hundred thousand images). The proposed method was validated and compared with other state-of-the-art on several public image datasets, including Oxford5k, Paris6k, and Oxford105k

汉诺坝玄武岩中麻粒岩和辉石岩捕虏体Sr-Nd-Pb同位素五维空间特征及其地质意义

研究了汉诺坝玄武岩中麻粒岩和辉石岩捕虏体在Sr-Nd-Pb同位素五维空间中的特征 .结合捕虏体的空间分布相对位置, 认为层离作用可较好地解释不同类型捕虏体同位素之间的相互关系。published_or_final_versio

Lattice and spin polarons in two dimensions

A general method applicable to two-dimensional particle-boson systems with arbitrary forms of linear particle-boson interactions and boson dispersion relations is presented. Applications to model superradiance in PIC J-aggregates, and to study single-pole motion in a two-dimensional antiferromagnet are discussed.published_or_final_versio

Fourier domain optical coherence tomography system with balance detection

A Fourier domain optical coherence tomography system with two spectrometers in balance detection is assembled using each an InGaAs linear camera. Conditions and adjustments of spectrometer parameters are presented to ensure anti-phase channeled spectrum modulation across the two cameras for a majority of wavelengths within the optical source spectrum. By blocking the signal to one of the spectrometers, the setup was used to compare the conditions of operation of a single camera with that of a balanced configuration. Using multiple layer samples, balanced detection technique is compared with techniques applied to conventional single camera setups, based on sequential deduction of averaged spectra collected with different on/off settings for the sample or reference beams. In terms of reducing the autocorrelation terms and fixed pattern noise, it is concluded that balance detection performs better than single camera techniques, is more tolerant to movement, exhibits longer term stability and can operate dynamically in real time. The cameras used exhibit larger saturation power than the power threshold where excess photon noise exceeds shot noise. Therefore, conditions to adjust the two cameras to reduce the noise when used in a balanced configuration are presented. It is shown that balance detection can reduce the noise in real time operation, in comparison with single camera configurations. However, simple deduction of an average spectrum in single camera configurations delivers less noise than the balance detection

A novel polyphase multipole square-wave permanent magnet motor drive for electric vehicles

A novel high-power-density permanent magnet (PM) motor drive for electric vehicles (EVs) is proposed. The motor is a polyphase multipole square-wave PM motor, which can be classified as a kind of PM brushless DC motor. The distinct features of the proposed motor as compared to those of the conventional PM brushless DC motor are as follows. First, the multipole magnetic circuit arrangement enables the minimization of the magnetic yoke, resulting in the reduction of motor volume and weight. Second, the coil span is purposely designed to be equal to one slot pitch, thus saving the amount of copper used. Third, by using a fractional number of slots per pole per phase, the arrangement of the numbers of poles and slots is so unique that the magnetic force between the stator and the rotor at any rotating position is uniform, hence eliminating the cogging torque that usually occurs in PM motors. Finally, the motor can be controlled to operate at a constant torque region and a constant power region with field weakening, thus both high starting torque and high cruising speed can be achieved. Therefore, as the proposed motor drive possesses the distinct advantages of high power density, high efficiency, and superior dynamic performance, it is very suitable for EV applications. A prototype of a five-phase 22-pole 5 kW motor drive has been designed for an experimental EV.published_or_final_versio

Sr, Nd Pb isotopic characteristics of granulite and pyroxenite xenoliths in Hannuoba basalts, Hebei Province, and their implications for geologic processes

Rb-Sr, Sm-Nd and Pb isotopic systematics are reported for granulite and pyroxenite xenoliths in Hannuoba basalts, Hebei Province. The isotopic characteristics of xenoliths suggest t hat they might have formed recently , although there is no strict constraint on the precise age. The decoupling of low Rb/Sr and high [87]Sr/[86]Sr ratios implies the multi-stage evolution history and strong mixing processes. There are close ties between granulite and pyroxenites with different mineral assemblages on the Sr-Nd, Pb-Sr and Pb-Nd correlation figures. The granulite is the common end-member o f the three kinds o f pyroxenite. Combined with the distribution of the xenoliths in space and their isotopic relationships, It is proposed that delamination can be well used to explain the ties.系统研究了河北汉诺坝玄武岩中二辉麻粒岩和辉石岩捕虏体的Sr、Nd、Pb 同位素特征。虽然未确定捕虏体的形成时代, 但同位素特征显示它们可能为较近期( 中生代以来) 形成。低的Rb/Sr 与高 的[87]Sr/[86]Sr 比值的解耦表明捕虏体的形成经历了较强的混合作用。在二元同位素相关图上, 三类具不同矿物组成的辉石岩与二辉麻粒岩有密切关系, 即二辉麻粒岩投点位置是三类辉石岩的共同端点。综合考虑捕虏体的空间分布及其在Sr 、Nd、Pb 同位素协变图上的关系, 可以认为层离作用可较好地解释这些现象。published_or_final_versio

Localized-density-matrix, segment-molecular-orbitals and poly(p-phenylenevinylene) aggregates

The segment-molecular-orbital representation is developed and incorporated into the recently developed linear-scaling localized-density-matrix method. The entire system is divided into many segments, and the molecular orbitals of all segments form the basis functions of the segment-molecular-orbital representation. Introduction of different cutoff lengths for different segment-molecular-orbitals leads to a drastic reduction of the computational cost. As a result, the modified localized-density-matrix method is employed to investigate the optical responses of large Poly(p-phenylenevinylene) aggregates. In particular, the interchain excitations are studied. The complete neglect of differential overlap in spectroscopy hamiltonian is employed in the calculation. © 1999 American Institute of Physics.published_or_final_versio