The peeling property of Bondi-Sachs metrics for nonzero cosmological constants

In this paper, we show that the peeling property still holds for Bondi-Sachs metrics with nonzero cosmological constants under the boundary condition given by Sommerfeld's radiation condition together with three nontrivial Λ-independent functions B, a and b. This should indicate that the new boundary condition is natural. Moreover, we construct some nonstationary vacuum Bondi-Sachs metrics without Bondi news, whose Newman-Penrose quantities fall faster than usual. This provides a new feature of gravitational waves for nonzero cosmological constants.     

Compensated split-step balanced methods for nonlinear stiff SDEs with jump-diffusion and piecewise continuous arguments

This paper deals with numerical solutions of nonlinear stiff stochastic differential equations with jump-diffusion and piecewise continuous arguments. By combining compensated split-step methods and balanced methods, a class of compensated split-step balanced (CSSB) methods are suggested for solving the equations. Based on the one-sided Lipschitz condition and local Lipschitz condition, a strong convergence criterion of CSSB methods is derived. It is proved under some suitable conditions that the numerical solutions produced by CSSB methods can preserve the mean-square exponential stability of the corresponding analytical solutions. Several numerical examples are presented to illustrate the obtained theoretical results and the effectiveness of CSSB methods. Moreover, in order to show the computational advantage of CSSB methods, we also give a numerical comparison with the adapted split-step backward Euler methods with or without compensation and tamed explicit methods.

     

Generalized KKM type theorems in FC-spaces with applications (II)

This paper is a continuum of the preceding paper of author. By applying a coincidence theorem in noncompact FC-space without any convexity structure due to author, a new KKM type theorem is first proved under noncompact setting of FC-spaces. The equivalent relation between the coincidence theorem and the KKM type theorem is also established. As applications of the KKM type theorem, we establish some new existence theorems of solutions for three classes of generalized vector equilibrium problems under noncompact setting of FC-spaces. These theorems improve and generalize many known results in literature.     

Public key encryption with filtered equality test revisited

Designs, Codes and Cryptography - Without revealing data in the plain, public key encryption with equality test can achieve the basic cryptographic functionalities required. However, the extended...     

Delannoy数与Schröder数的一些和式公式

研究了Delannoy数与Schr?der数.利用分析方法和组合技巧,建立了任意多个Delannoy数乘积的一些和式公式,并对Schroder数的和式公式进行了类似的研究.     

Study on size-dependent optical property of 4,4′-dibromobiphenyl nanocrystals

4,4^′-dibromobiphenyl nanocrystals with different sizes in the range from 20 nm to 300 nm were prepared by the reprecipitation method. It was found that their absorption peaks experienced a red shift while the size of the nanocrystals increased. Through analyzing these spectra of the nanocrystals with different sizes, it is suggested that this size-dependent optical property is contributed by two factors, the size effect and the J-aggregate formation. Received: 28 August 2000 / Accepted: 2 March 2001 / Published online: 23 May 2001     

Effect of film thickness manganite-based on interfacial barrier of heterojunctions

Interracial barrier is a key factor that determines the performances of heterojunctions. In this work, we study the effect of manganite film thickness on the effective interracial barrier for La0.67Sr0.33MnO3/Nb：SrTiO3 junctions, The barrier is extracted from the forward current-voltage characteristics. Our results demonstrate that the barrier decreases gradually from -0.85 eV to -0.60 eV when the film thickness decreases from 150 nm to 2 nm. The overall value of the barrier is only about 50% of the corresponding one determined from the photovoltaic effect.     

Temporal and spectral analysis of capillary-discharge-pumped Ar<Superscript>8+</Superscript> lasers

We measure temporal and spectral characteristics of soft X-ray lasers based on capillary discharge, employing flat-field and Rowland spectrographs for analyzing the spectrum of a Ne-like Ar soft Xray laser and a monochromator for analyzing its temporal behavior on the 46.9 nm laser line. The monochromator provides the time resolution for a single wavelength; therefore, the pulse width and the onset time of the laser pulse can be reliably measured. In spite of the fact that the flat field spectrograph is relatively difficult to adjust (due to the long distance between the entrance slit and the grating), we obtained a fine spectrum with a fairly high precision. In contrast, the Rowland spectrograph is widely used, easily adjusted, and provides instantaneously visible results, but its detection precision is just between that of the monochromator and the flat-field spectrograph. Each of these three types of devices is characterized by its own strong point for the accurate detection and study of the spectrum of a Ne-like Ar laser at J = 0− 1 and wavelength 46.9 nm.     

基于视频推荐技术的无线网络视频服务器设计

无线网络视频服务器中视频推荐技术已成为重要技术之一,视频推荐技术是为了用户在使用无线网络是视频务器时,更快的找到感兴趣的视频。采用当前方法对用户进行视频推荐时,未考虑用户的兴趣偏好是否随着时间有所变化,使视频推荐出现偏差。为此,提出一种基于视频推荐技术的无线网络视频服务器设计方法。该方法首先使用无线网络视频服务器硬件部分的MPEG-4进行视频数据采集,并对MPEG-4采集的视频数据进行整理。在由软件部分把采集到的视频数据储存到缓冲区,进行视频缓冲,并建立视频数据队列进行视频数据输送。以计算无线网络视频的相似度来搜索相近视频,将搜索到的视频与目标用户观看过的视频进行对比,对比相似度越接近1,则说明用户对推荐视频感兴趣的几率大,反之越接近-1用户对推荐视频越不感兴趣。此计算方法能有效的从海量视频数据中快速的搜索出目标用户感兴趣视频。实验结果表明,将视频推荐技术应用到无线网络视频中可以迅速准确的搜索出目标用户感兴趣视频。     

The dispersive properties of a dielectric-rod loaded waveguide immersed in a magnetized annular plasma

Propagation properties of electromagnetic waves in a dielectric-rod waveguide immersed in a magnetized annular plasma are presented in this paper. The dispersion relations are derived and calculated. The results show that the dielectric-rod loading can make the structure less dispersive and the transmission frequency-band broadened.