THE IMPACTS OF INTERACTION OF A TYPHOON WITH THE MIDLATITUDE TROUGH ON ITS TRACK AFTER THE RECURVATURE

Three typhoon cases are selected to conduct a series of simulations that are initialized from sequential analyses. The results show that the forecast error in crucial area where a tropical cyclone (TC) interactes with the upstream trough is highly correlated to the track forecast error after the TC recurvature. Furthermore, sensitivity experiments confirm that the developments of the midlatitude downstream circulations and then the TC track after its recurvature are highly sensitive to the TC intensity and its location relative to the upstream trough, which can give an example or one way of sensitivity of the TC track to the TC-trough interaction. If the TC interacts with the upstream trough more strongly (e.g., the TC being intensified or getting closer to the upstream trough), the downstream circulations will be more meridional, thus the TC track will be more northerly and westerly; otherwise, the downstream circulations will be more zonal, and the TC track will be more southerly and easterly.     

莒南发现恐龙足印化石群

近来，在山东省莒南县岭泉镇后左山村金牛墩岭上发现了远古时代留下的恐龙足印群。此处恐龙足印分布地点之多、足印类型之多、赋存层位之多皆为省内外所罕见。     

贵州涟江惠水段河流阶地特征与地貌演化研究

贵州涟江惠水段级次清晰的四级阶地是流域地貌阶段性演化的直观记录。笔者等利用差分GPS测量法精确厘定了涟江阶地的级序和高程,结合剖面观测发现从上游到下游,涟江惠水段阶地标高和级差逐渐降低,地貌面整体呈“收拢”趋势;阶地沉积物呈现砾石层厚度变小,砾石含量降低、砾径减小,砂质沉积占比增大趋势;阶地类型从基座阶地为主向堆积阶地为主演变。光释光(OSL)测年显示,T1阶地埋藏年龄31.2±2.0 ka BP到14.7±1.3 ka BP,T2阶地122.4±8.5 ka BP到66.9±3.8 ka BP,阶地年龄与贵州高原其他流域十分相近,具有同步演化特征。结合阶地时代和发育特征,认为贵州高原河流阶地是构造运动的产物。涟江四级阶地记录了在更新世以来四次构造抬升背景下,流域经过多期自北向南“削高补低”的地貌改造,逐步由构造洼地演变为山间盆地的地貌过程。     

全球海量地形数据组织管理方法的研究

本文通过研究全球多分辨率地形数据的特点和渲染需要,研究了现有的全球地形数据组织方法并提出改进措施。然后利用多分辨率LOD(MRLOD)技术,设计并实现了一种面向全球的分层分块方案,详细阐述了其构建规则,并分析了方案的可行性,然后详细地说明了分层分块的数据结构组织,最后利用上述提出的技术,做了一些关于某一大规模三维地形实时漫游方面的实验,文中详细列出了这些实验结果。实验结果表明,采用该文提出的方法,可以在普通PC机上实现大规模三维地形场景的实时漫游。     

A theoretical extraction scheme of transport information based on exclusion models

In order to explore how to extract more transport information from current fluctuation, a theoretical extraction scheme is presented in a single barrier structure based on exclusion models, which include counter-flows model and tunnel model. The first four cumulants of these two exclusion models are computed in a single barrier structure, and their characteristics are obtained. A scheme with the help of the first three cumulants is devised to check a transport process to follow the counter-flows model, the tunnel model or neither of them. Time series generated by Monte Carlo techniques is adopted to validate the abstraction procedure, and the result is reasonable.     

Underway Measurement of Sea Surface Temperature and Salinity in the Taiwan Straits in August,1999

The distributional features of sea surface temperature and salinity(SST and SSS) in the Taiwan Straits have been analyzed using the SST and SSS underway measurements in August,1999.The characteristics of SST and SSS are summarized as foloows:There are several upwellings and diluted water in the Taiwan Straits.The upwellings are divided into two kinds:those along the western coast of the Taiwan Straits and those around the Taiwan Shoal.There are three sources of diluted water:diluted water of the Jiulongjiang River,diluted water of the Zhujiang River and diluted water of the Minjiang River.     

弯型截止阀流场的PIV显示和数值模拟

为了解弯型进口截止阀的流场特性,用粒子成像流速仪(PIV)对弯型截止阀对称面模型进行了流场显示;此外,采用了RNGk ε紊流模型和贴体坐标对弯型进口和斜进口截止阀对称面流场进行了模拟。通过用粒子成像流速仪流场显示技术和数值计算,揭示了弯型进口和斜进口截止阀流场特性,数值计算的流态与实验结果也较为吻合。计算结果显示斜进口截止阀流态好于弯型进口截止阀的流态。     

用热温度给恒星论资排辈

用热温度给恒星论资排辈○陈华在国家自然科学基金委员会和母校北京大学地球物理系天体物理专业的支持下,我于年初回国短期工作,在此期间深深感到祖国的天文事业与其他事业一样蒸蒸日上,不仅专业工作者,而且公众对天文的热情也很高,我特意将我的学术报告中的一个,写...     

一种面向对象的全球多分辨率纹理数据的预处理方法的研究

建立具有多分辨率、海量数据的大规模虚拟地形场景越来越受到人们的关注,海量纹理数据的管理与生成算法是三维地景仿真的关键技术之一。本文在金字塔塔模型的基础上,运用面向对象思想,设计了多分辨率纹理数据的生成方案,对其流程进行了具体实现,对一些相关技术进行了讨论。通过试验表明,采用本文提出的方法,可以灵活地对全球影像数据进行管理和使用,对全球三维可视化具有一定作用。     

二维地理信息表达在三维空间中的应用分析研究

地理信息表达从二维纸质地图到电子地图再到三维可视化地理环境的飞跃,是地图学史上的一次革命。三维空间认知理论,三维符号体系设计及三维符号变量理论的逐渐完善和发展对三维环境下地理空间信息的表达起到了积极的作用,本文论述了二维地图符号与三维空间信息表达的关系,描述了二维地理信息在三维空间中叠加表示的意义,并分析了二维地图符号表达的优劣性。