A study of the Galactic plane towards l= 305°

We present optical  ( UBVI _C )  observations of a rich and complex field in the Galactic plane towards   l ∼ 305°  and   b ∼ 0°  . Our analysis reveals a significantly high interstellar absorption  ( A _V ∼ 10)  and an abnormal extinction law in this line of sight. Availing a considerable number of colour combinations, the photometric diagrams allow us to derive new estimates of the fundamental parameters of the two open clusters Danks 1 and Danks 2. Due to the derived abnormal reddening law in this line of sight, both clusters appear much closer (to the Sun) than previously thought. Additionally, we present the optical colours and magnitudes of the WR 48a star, and its main parameters were estimated. The properties of the two embedded clusters, DBS2003 130 and 131, are also addressed. We identify a number of young stellar objects which are probable members of these clusters. This new material is then used to revisit the spiral structure in this sector of the Galaxy showing evidence of populations associated with the inner Galaxy Scutum-Crux arm.     

Are pre-main-sequence stars older than we thought?

We fit the colour–magnitude diagrams of stars between the zero-age main-sequence and terminal-age main sequence in young clusters and associations. The ages we derive are a factor of 1.5–2 longer than the commonly used ages for these regions, which are derived from the positions of pre-main-sequence stars in colour–magnitude diagrams. From an examination of the uncertainties in the main-sequence and pre-main-sequence models, we conclude that the longer age scale is probably the correct one, which implies that we must revise upwards the commonly used ages for young clusters and associations. Such a revision would explain the discrepancy between the observational lifetimes of protoplanetary discs and theoretical calculations of the time to form planets. It would also explain the absence of clusters with ages between 5 and 30 Myr.
We use the  τ²  statistic to fit the main-sequence data, but find that we must make significant modifications if we are to fit sequences which have vertical segments in the colour–magnitude diagram. We present this modification along with improvements to the methods of calculating the goodness-of-fit statistic and parameter uncertainties.
Software implementing the methods described in this paper is available from http://www.astro.ex.ac.uk/people/timn/tau-squared/ .     

Variable stars in the field of open cluster NGC 2126

We report the results of a time-series CCD photometric survey of variable stars in the field of open cluster NGC 2126. In about a one square degree field covering the cluster, a total of 21 variable candidates are detected during this survey, of which 16 are newly found. The periods, classifications and spectral types of 14 newly discovered variables are discussed, which consist of six eclipsing binary systems, three pulsating variable stars, three long period variables, one RS CVn star, and one W UMa or δ Scuti star. In addition, there are two variable candidates, the properties of which cannot be determined. By a method based on fitting observed spectral energy distributions of stars with theoretical ones, the membership probabilities and the fundamental parameters of this cluster are determined. As a result, five variables are probably members of NGC 2126. The fundamental parameters of this cluster are determined as: metallicity to be 0.008 Z , age log(t)=8.95, distance modulus (m - M)0 = 10.34 and reddening value E(B -V) = 0.55 mag.     

基于元数据的地理空间信息Web服务及其开发研究

地理空间信息Web服务的基础是元数据,通过元数据接口可以有效地发现和提供地理空间信息服务。基于CSDGM标准,分析和扩展地理空间信息服务模块,包括1个复合元素和11个数据元素。提出2种基于元数据的地理空间信息Web发布模式,并从服务角度对二者进行了比较。结合第2种模式分析了地理空间信息服务的关键技术,并进行了应用实例验证。     

发展我国地理空间信息网格技术的探讨

网格技术发展迅速,从网格技术的发展轨迹和我国社会经济发展的需求来看,构建地理空间信息网格势在必行.本文介绍了网格的技术背景与发展进程,提出地理空间信息网格的结构层次应该是开放的、可扩展的、面向对象的,基于此设计了地理空间信息网格的结构层次,并针对我国构建地理空间信息网格提出了从局部到整体、政府支持与协调、完善规划和法规的建设性意见.     

基于知识标注的地理信息语义服务框架研究

基于空间语义学基础理论,将传统的地理信息服务技术与新兴的语义服务技术相结合,建立地理信息语义服务框架及知识标注方法体系,并应用于地理空间信息服务处理中,提供智能化、自动化的地理信息服务发现、组合与触发策略;设计基于文本挖掘算法的半自动知识标注引擎,提高服务处理自动化程度,实现包含丰富语义信息的地理空间语义服务的发布;建立基于规则和推理引擎的地理信息服务匹配与发现机制,提高服务发现效率;建立地理信息服务语义标注与服务匹配评价方法,采用基于空间关联规则的标注正确性评估策略,验证知识标注价值。     

石油污染土壤生物修复的强化技术

为探索石油污染土壤的高效修复方法,从实验室保存的优势菌中筛选得到4株降油效果最佳菌,采用摇床和恒温培养箱培养,对含油量为5％的石油污染土壤进行微生物菌剂强化处理和环境强化实验。微生物菌剂强化结果表明：4种菌和除油效果最好的A、C、D混合菌3d可将石油烃依次降解24％、19．81％、22．55％、26．46％、39．67％;并对该菌群的最佳投加配比进行确定,A、C、D菌群数量的最佳配比为Nn：Nc：No=1：2：0．5,3d内菌群A、C、D在最佳接种配比情况下可将石油烃降解44．2％。环境强化实验结果表明：A、C、D菌群在最佳修复条件营养物质C：N：P为75：8：3、表面活性剂为0．5％、通气条件为6层纱布、电子受体H2O2的加入量为1．5％下,3d内石油烃降解61．46％,比自然条件下修复的除油率4．7％提高了56．76％,较只进行菌种强化时最高除油率44．2％提高了约17％。     

关中城市建设中的地质工作

随着经济社会快速发展,城市建设进程中,地质环境问题显得越来越重要。从已取得的研究成果看,1976年到2006年的30年间,仅仅因地裂缝与地面沉降灾害,给西安城区（200 km2）造成的经济损失高达120亿元。地裂缝与地面沉降主要造成住宅、厂房、车间的破坏;天然气管道、煤气管道、自来水管道、污水管道等的爆裂、破损;公路、铁路、地铁、桥梁的破坏;还有城市水灾、安全高程损失、