Statefinder description of a cosmological model based on a mixture of five fluids

In this paper, we have considered a model of our universe containing five components as its constituents. Then, we have done here the statefinder diagnostics for this model. This model can successfully explain the accelerated expansion of the universe given that it satisfies a certain condition. Here we have considered the modified Chaplygin gas as the dynamically changing part of the dark energy component of our universe. Chaplygin gas provides early deceleration and late time acceleration of the universe. The graphical representation of statefinder parameters shows that the total evolution of the universe starts from radiation era to phantom model.     

利用TRMM卫星资料对人工增雨云系模式云微观场预报能力的检验

文中利用TRMM卫星测雨雷达探测反演的云水、雨水、云冰和降冰4种云参数产品及实况降水资料,对比检验该人工增雨云系业务模式对云微观场和地面降水场的预报能力.结果表明,人工增雨云系模式系统对降水的预报能力要略优于现行业务运行的GRAPES模式;人工增雨云系模式系统能较好地预报云系系统云物理微观量的垂直结构特征,模式预报的微观场与卫星监测吻合较好;在播撒窗区的水平分布上,模式预报的各水凝物分布形势和强中心位置与卫星监测一致,其大小也接近监测值;人工增雨云系模式能较好地预报云的微观场和天气形势场,可作为云系人工增雨条件决策的重要参考依据.     

基于FPGA的高速FIR数字滤波器设计的改进方法

在高速有限冲击响应(Finite Impulse Response,FIR)数字滤波器的设计中,随着滤波器阶数的增加,保持数据流速率和有效使用硬件资源成为设计的一个重点和难点。基于高速并行有限冲击响应数字滤波器的基本原理,提出了一种将位平面法、正则有符号系数(Canonical-Signed Digit,CSD)编码算法和抽取算法应用于并行有限冲击响应数字滤波器的改进方法。设计通过Matlab仿真,在Quartus II中编译、仿真、综合后下载到现场可编程门阵列(Field Programmable Gate Array,FPGA)中进行测试,结果显示,这种改进方法较好地解决了滤波器阶数和数据流速率与硬件资源之间的关系。     

SVOM数据档案库软件原型系统的设计与实现

作为中法天文卫星(Space multi-band Variable Object Monitor,SVOM)中方科学中心的重要组成部分,中法天文卫星数据档案库承担了中方科学数据产品本地存储和管理的任务,提供统一的数据产品管理平台,实现中法天文卫星科学数据产品的归档、检索、检出、维护与管理等功能。作为中法天文卫星科学中心预研的一部分,对中法天文卫星数据档案库原型系统进行了需求分析、系统设计,实现能够运行的原型系统,以演示中法天文卫星数据档案库的基本功能和工作流程,验证设计方案的可行性。档案库原型系统具有开放性和低耦合的特点,能够适应中法天文卫星中方数据产品结构的不断变化,在项目早期即可投入试用并不断完善,满足中法天文卫星的任务需求。     

Optical observations of the broad-lined type Ic supernova SN 2012ap

The optical observations of the type Ic supernova(SN Ic) SN 2012 ap in NGC 1729 are presented. A comparison with other SNe Ic indicates that SN 2012 ap is highly reddened(with E(B- V)host～0.8 mag) and may represent one of the most luminous SNe Ic ever observed, with an absolute V-band peak magnitude of ～-19.3±0.5 mag after extinction correction. The near-maximum-light spectrum shows wide spectral features that are typical of broad-lined SNe Ic. One interesting feature in the spectrum is the appearance of some narrow absorption features that can be attributed to the diffuse interstellar bands, consistent with the large reddening inferred from the photometric method. Based on the light curves and the spectral data, we estimate that SN 2012 ap produced a56 Ni mass of ～ 0.3 ± 0.1M in the explosion, with an ejecta mass of 2.4+0.7-0.7M and a kinetic energy of E5K= 1.1+0.4-0.4× 102 erg. The properties of its progenitor are also briefly discussed.     

黑子活动区流场精细结构

本文通过太阳活动区光球和色球速度场和磁场观测资料,讨论了黑子活动区附近流场的精细结构,论述了太阳大气中物质的流动呈纤维结构,以及速度场纤维与磁场,色球纤维和网络结构之间的关系。     

Exact solution of anisotropic compact stars via mass function

Studying relativistic compact objects is important in modern astrophysics to understand several astrophysical issues. It is therefore natural to ask for an internal structure and physical properties of specific classes of compact stars from astrophysical observations. We obtain a class of new relativistic solutions with anisotropic distribution of matter for compact stars. More specifically, stellar models, described by an anisotropic fluid, establishing a relation between metric potentials and generating a specific form of mass function, are explicitly constructed within the framework of General Relativity. New solutions can be used to model compact objects, which adequately describe compact strange star candidates like SMC X-1, Her X-1 and 4U 1538-52, with observational data taken from Gangopadhyay et al. (Mon. Not. R. Astron. Soc. 431:3216, 2013). As a possible astrophysical application the obtained solutions could explain the physics of selfgravitating objects, and might be useful for strong-field regimes where data are currently inadequate.     

Analytical study of the swing-by maneuver in an elliptical system

The objective of the present paper is to derive a set of analytical equations that describe a swing-by maneuver realized in a system of primaries that are in elliptical orbits. The goal is to calculate the variations of energy, velocity and angular momentum as a function of the usual basic parameters that describe the swing-by maneuver, as done before for the case of circular orbits. In elliptical orbits the velocity of the secondary body is no longer constant, as in the circular case, but it varies with the position of the secondary body in its orbit. As a consequence, the variations of energy, velocity and angular momentum become functions of the magnitude and the angle between the velocity vector of the secondary body and the line connecting the primaries. The “patched-conics” approach is used to obtain these equations. The configurations that result in maximum gains and losses of energy for the spacecraft are shown next, and a comparison between the results obtained using the analytical equations and numerical simulations are made to validate the method developed here.     

Integration of the full two-body problem by using generalized inertia integrals

A new algorithm to integrate the full two-body problem based on generalized inertia integrals is given. The computation speed is comparable to the fastest algorithm available till now which is based on spherical harmonics.     

Measuring supermassive black holes via reverberation mapping in the UV

Over the past three decades the reverberation mapping technique was used to measure the central regions of Active Galactic Nuclei (AGN), their size, velocity field, and the mass of the black hole in the center. This technique was used mainly in the optical with several studies in the UV. Reverberation mapping in the UV adds essential information to the AGN studies. This paper reviews these recent studies done in the UV, presents results from the recent HST campaign toward NGC?5548, and discuss two projects of reverberation mapping of UV emission lines in high-luminosity quasars. The advantages of reverberation mapping in the UV will be discussed as well as the needs from new UV missions in order to be able to advance UV reverberation mapping campaigns.