基于聚合点的网络多媒体业务拥塞控制

当前广泛开展的网络多媒体业务都存在不同程度的服务不稳定情况,其原因是架构于网络上的多媒体业务缺乏整体有效的网络控制机制.基于研究提出了一种基于聚合点的拥塞控制方法,能对网络多媒体业务进行有效的拥塞控制.与现有业务实施机制相比,该方案实现简单,能更有效保证业务的开展.     

星爆后星系NGC4736核区的环状结构

在１９９２年３月３１日至４月２日期间，我们利用云南天文台１ｍ望远镜２号ＣＣＤ和缩焦装置，对环星系ＮＧＣ４７３６进行了Ⅴ和Ⅰ波段深曝光观测。在经过Ｒｉｃｈａｒｄｓｏｎ－Ｌｕｃｙ图象复原以及自适应滤波两种方法处理后，发现仅仅在Ⅴ波段图象上，其核区存在一个直径约为１０″的环状结构。     

Numerical simulations of the Hyades dynamics and the nature of the moving Hyades cluster

We present our numerical simulations of the dynamical evolution of the Hyades open cluster. The simulations were performed usinga modified NBODY6 algorithm that included tidal forces and a realistic orbit of the cluster in a gravitational field described by the Miyamoto-Nagai potential. Our goal was to study the nature of movingclu sters. We show that the stars that were earlier cluster members could be later identified within a sphere of 50 pc in diameter around the Sun. The number of such stars for the chosen initial mass and virial radius of the cluster does not exceed ten. The maximum space velocity of these stars relative to the core of the current cluster does not exceed 3 km s^?1. Our numerical simulations confirm the assumption that some of the moving clusters near the Sun could consist of stars that have escaped from open clusters in the course of their dynamical evolution.     

NGC 1624 (OCl 403, Cr 53) – A very young open cluster

We present the first CCD photometric UBVRI observations of the not-so-well-studied open cluster NGC 1624 (OCl 403, Cr 53; α₂₀₀₀ = 04 h 40 m 36 s; δ₂₀₀₀ = + 50^˚ 27^′ 42″ Trumpler class = I 2 p N). This cluster was observed on 01 February 2004 with the 2 m Himalayan Chandra Telescope at Hanle using a LN2 cooled 2k × 2k CCD. The cluster presents differential reddening with E(B-V) values ranging from 0.70 to 0.90 mag, which could be attributed to the presence of the HII region wherein the cluster is embedded. It is found to be at a distance of 6.025 ± 0.5 kpc and the age of this cluster is estimated to be ∼3.98 × 10⁶ years. In view of these parameters, it can be considered as a young enough cluster located in the direction of the Perseus constellation with the galactic coordinates of l = 155^˚.35 and b = + 02 ^˚.58. Thus it could also be used as a suitable candidate for tracing the Outer Perseus spiral arm of our Galaxy. The initial mass function slope is derived as 1.65 ± 0.25 by applying the corrections for field star contamination and data incompleteness. This is in good agreement with the Salpeter value within the limits of errors.     

星系的恒星速度弥散度的归算方法

星系的恒星视向速度分布是星系动力学模型的重要观测约束,其特征参数包括速度弥散度、分布轮廓以及红移。这些参数对研究星系的动力学、结构和演化以及中央黑洞的质量等都具有重要的价值。该文全面总结了从星系光谱归算星系的恒星视向速度分布及其弥散度的各种方法,以及对观测和处理的一些要求。这些方法都假设星系谱线可看作是模板星光谱经多普勒位移并加宽后的线性叠加。提取尽可能多的星系内部恒星运动信息、减少模板星失配的影响、简化误差分析,是这些方法追求的目标。     

疏散星团NGC2244天区恒星的绝对自行研究

利用上海天文台相隔35年的两期照相底片资料,测定了疏散星团NGC2244所在天区55’×55’范围内495颗恒星基于Tycho-2星表的位置和绝对自行,并对自行精度作了初步分析。     

A new red variable star in the globularcluster M4

G302 = L3107 is a red star located at the lowest end of the red giant branch of the globular cluster M4. According to its location on the C-M diagram, G302 may be a cluster member. No proper motion or radial velocity determinations are available up to date.

We discovered that C302 is a new variable star with a main period of 1.24719 day and a peak to peak amplitude of about 0.3 mag in V. It may have a second period of 2.38249 day with an amplitude of about 0.05 mag. If it is a cluster member, then there will be interesting implications for the the theory of stellar evolution.     

移动Agent 在集群系统中的应用研究

从任务级的角度，在基于主／从模式的集群系统中引入了移动Agent技术，建立了基于移动Agent的并行计算模型。基于该模型，对移动Agent之间的通信接口、容错机制和负载平衡策略等问题进行了研究。     

恒星形成区GGD12-15的近红外观测

给出恒星形成区GGD12-15的宽波段JHK和窄波段H2v=1-0S(1)近红外成像观测．观测图像揭示了致密的年轻红外星团和与红外源成协的红外星云，并发现了以H2发射结表征的星团外流活动．大多数红外点源在光学波段不可见；对76颗红外点源的JHK′测光结果显示，有32颗具有红外超，其中5颗表现原恒星特征，表明分子云中的恒星形成活动很活跃．以B8光谱型作为大质量星分界，由色星等图估计出大质量星所占星团比例为-10％～26％．GGD12—15星团的K′星等分布的峰值位于15.0mag，并在13．0mag-16．0mag平坦分布；[H—K′]色分布的峰值出现在-0．7mag，在此以上更红的星团成分占70％．在GGD12-15区新发现的氢分子发射结集中在星团中心领域，其空间分布明显与剧烈的恒星形成活动相关；有5个发射结位于分子外流的中心区域，暗示其激发可能与分子外流同源．