Observation of a Straight-Line Wind Case Caused by a Gust Front and Its Associated Fine-Scale Structures

A straight-line wind case was observed in Tianjin on 13 June 2005, which was caused by a gust front from a squall line. Mesoscale analyses based on observations from in-situ surface stations, sounding, and in-situ radar as well as fine-scale analyses based on observation tower data were performed. The mesoscale characteristics of the gust front determined its shape and fine-scale internal structures. Based on the scale and wavelet analyses, the fine-scale structures within the gust front were distinguished from the classical mesoscale structures, and such fine-scale structures were associated with the distribution of straight-line wind zones. A series of cross-frontal fine-scale circulations at the lowest levels of the gust front was discovered, which caused a relatively weak wind zone within the frontal strong wind zone. The downdraft at the rear of the head region of the gust front was more intense than in the classical model, and similar to the microburst, a series of vertical vortices propagated from the rear region to the frontal region. In addition, strong tangential fine-scale instability was detected in the frontal region. Finally, a fine-scale gust front model with straight-line wind zones is presented.     

基于开源方式的多源网络地名数据库整合

目前我国地名数据库的建设主要靠传统测绘手段完成,存在周期长、成本高、效率低的缺点。随着地理数据服务的发展,出现了一些在格式、尺度、范围、内容、现势性等方面具有差异性的免费地名数据库。本文提出了一种整合多开源网络地名数据库形成统一格式、多尺度、内容完备、现势性强的矢量地名库的方法。首先通过OGR和数据访问API构建不同文件格式的网络地名库的矢量格式转换模型,然后对多网络地名库进行矢量转换,最后对其进行数据预处理、数据处理、数据分类映射等处理过程建立矢量地名数据库。本文以香港地区的Geonames,GNS,OSM地名数据库整合为例,验证了方法的可行性。     

房产全生命周期测绘管理系统开发

房产作为社会最重要的财富,要经历规划、预售、竣工、拆迁等阶段,在每一阶段均要进行房产面积的测算。现在房产测绘在各阶段的测绘方法与计算规范不尽相同,成果的比较核对与共享大部分还处在手工阶段,这给房产测绘管理带来了很大的不确定性,也大大增加了测绘成本和可能带来的纠分。为此,开发一套针对房产全生命周期的测绘管理办法与系统,提高房产调查与测绘的效率,降低成本,保证成果的质量与权威性,实现各管理部门的信息共享,为城市建设提供决策支持。     

新沂地震台地电阻率反向年变分析

结合新沂地震台电测深曲线、 测区地质剖面资料, 建立了三维非均匀层状介质有限元模型. 以第一层介质电阻率变化模拟表层介质电阻率随季节性降雨的变化, 在模型中计算了3个测道的地电阻率年变化形态. 计算结果表明, EW和N45°E测道地电阻率随表层介质电阻率的增减同向增减, 而NS测道地电阻率则与表层介质电阻率变化相反. 该结果符合新沂台3个测道实际观测的年变形态．      

低kV管电流调制技术在正常体重指数者CT冠状动脉成像中的可行性研究

目的:探讨80 kV管电流调制技术冠状动脉CT成像在正常BMI受检者中应用的可行性。方法:收集140例行冠状动脉CTA检查的患者。所有受检者BMI均小于25 kg/m2。随机分为2组,即80 kV组和120 kV组,在这2组内部分受检者又联合采用管电流调制技术扫描。由2位医师行双盲、随机方法对各组图像评分。客观测量信噪比、对比噪声比及辐射剂量。结果:80 kV组客观图像质量均低于120 kV组(P值均<0.05),而2组图像质量主观评分并未见明显差异(P>0.05)。采用80 kV组其辐射剂量较120 kV组减少约12 mSv,而联合应用管电流调制技术可减少剂量高达82%(P<0.05)。结论:对于BMI指数小于25 kg/m2受检者,采用80 kV管电压联合管电流调制技术可有效降低辐射剂量且不损害主观图像质量。     

基于STC89C52单片机的地震台站远程监控系统

针对无人地震监测点日益增加和台网运行维护存在不足的现状,提出一种基于STC89C52单片机的远程监控系统。对该系统的单片机微控制器、通信模块、温湿度检测模块等硬件组成进行描述,并介绍其控制程序。实践证明,该系统可以对无人值守台站的设备进行断电和重启等远程操作并对工作环境进行实时监测,为地震监测设备的实时维护和稳定运行提供依据与保障。     

准噶尔荒漠小山蒜的形态与生物量特征及其相互关系

小山蒜(Allium pallasii)是中国新疆特有的类短命植物。调查了准噶尔荒漠16个20 m×20 m样地内小山蒜种群的分布概况,研究了小山蒜盛花期的生物学特征、器官生物量分配及其相互关系。结果表明:①小山蒜多生于沙丘中下部,密度为0.187株·m–2;平均株高为(22.93±5.15)cm,多为3片叶;花序近球形,平均半径(2.44±0.37)cm,纵断面角度211.39°±60.4°,表面积和体积分别为(50.95±34.19)cm2和(43.37±29.45)cm3。②其形态指标(平均叶长、4个花球指标及鳞茎直径)间、生物量指标(根生物量除外)间,及二者之间多为显著(P<0.05)或极显著(P<0.01)正相关,协同生长关系较强。③小山蒜生物量分配呈鳞茎>花葶>花球>叶片>根的格局,根冠比为0.873,生殖分配占49.66%。④形态指标与生物量间均呈α<1的异速生长关系,而生物量指标间多为等速关系,其中地上、地下生物量间符合α=3/4的异速关系。⑤生物量估测表明,小山蒜单株地上生物量平均为0.312 g,单株地下生物量平均为0.264 g,种群总生物量密度仅为0.106 g·m-2,其生物量在整个荒漠生态系统中可忽略不计,但它作为准噶尔荒漠重要而独特的种质资源,应从多个方面深入研究,同时进行适当保护。     

多层螺旋CT血管造影对肠扭转的诊断价值

目的：探讨多层螺旋CT血管造影对肠扭转的诊断价值。方法：回顾性分析14例行腹部CT血管造影诊断肠扭转,并经手术证实病例资料。采用多平面重建MPR,容积再现VR,最大密度投影MIP等多种重建方式显示肠系膜血管。结果：14例均正确诊断,主要征象肠系膜血管的漩涡征（14例）,肠管的漩涡征（14例）,鸟喙征（10例）,肠壁水肿...     

Habitat values for artificial oyster (Crassostrea ariakensis) reefs compared with natural shallow-water habitats in Changjiang River estuary

studies have compared oyster reefs with adjacent natural shallow-water habitats.Here the resident benthic macroinvertebrate communities in an artificial oyster(Crassostrea ariakensis) reef and in adjacent natural estuarine shallow-water habitats(salt marsh,intertidal mudflat,and subtidal soft bottom) in the Changjiang(Yangtze) River estuary were described.The mean total densities and biomass,Margalef’s species richness,Pielou’s evenness and Shannon-Weaver biodiversity indices of the resident benthic macroinvertebrate communities differed significantly among the habitats.Significantly higher densities and biomass of benthic macroinvertebrates occurred in the oyster reef compared with the other three habitats.Ordination plots showed a clear separation in benthic macroinvertebrate communities among the four habitat types.The results demonstrated that the artificial oyster reef supported distinct and unique benthic communities,playing an important role in the complex estuarine habitat by supplying prey resources and contributing to biodiversity.In addition,the results suggested that the oyster reef had been restored successfully.     

湿地旅游环境承载力研究——以宁夏银川市阅海湿地公园为例

湿地是一类特殊的旅游资源,应以保护为主,开发为辅,在开发过程中必须要进行旅游环境承载力的计算。本文对阅海湿地公司的旅游环境承载力做出了系统测算,并提出了旅游调控策略。最后还对旅游承载力这一概念进行了讨论。