An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.     

A case study of WebGIS technology for distance learning between Korea and Japan

Recently，some case study of distance learning by internet line are widely carried out. Until now，the cultural or friendship exchange was a main purpose using distance learning program. In our research group， a distance learning which connected 3 sites (Nagasaki and Omura and Kagoshima in Japan) was tried as a domestic example [1]. In this case，internet exclusive line and portable telephone were utilized for DVTS technical support of distance learning. Nowadays，the international distance learning for education is also beginning. Our research group also tried international distance learning between Kwangju city of Korea and Nagasaki city of Japan using DVTS techniques with the tools of WebGIS education materials.     

Indexing large moving objects from past to future with PCFI

In moving object database, the moving objects' current position must be kept in memory, also to the trajectory, in some case, as same as the future. But the current existing indexes such as SEB tree, SETI tree, 2+3R tree, 2 3RT tree and etc. can only provide the capability for past and current query, and the TPR Tree, TPR * Tree and etc. can only provide the capability for current and future query. None of them can provide a strategy for indexing the past, current and also the future information of moving objects. In this paper, we propose the past current future Index (PCFI Index) to index the past, current & future information of the moving objects. It is the combination of SETI tree and TPR * tree, the SETI liking index is used for indexing the historical trajectory segments except the front line structure, and the moving objects' current positions, velocities are indexed via the in memory frontline structure which mainly implemented with TPR * tree. Considering the large update operations on TPR tree of large population, a hash table considering cache sensitivity is also introduced. It works with the frontline part, leading a bottom up update of the tree. The performance analysis proves that the PCFI index can handle most of the query efficiently and provides a uniform solution for the trajectory query, time slice query, internal query and moving query.     

射频负偏压等离子体鞘层流体动力学模拟

采用流体动力学方法建立了一种自洽的无碰撞射频直流偏压等离子体鞘层动力学模型.模型中考虑了极板直流负偏压对离子运动的影响,模拟了在不同偏压条件下射频等离子体鞘层内各参量的时空演化特性.在该模型中,认为鞘层厚度是与时间有关的函数,并采用等效电路模型建立了鞘层瞬时厚度与鞘层电位降的关系.模拟结果表明,极板上电势呈非正弦周期性变化;鞘层厚度变化与极板电势变化周期相同,趋势相反,且略滞后于射频周期.     

大规模围垦对香港维多利亚港水动力环流的影响

运用一个已校正的珠江口三维水动力数学模型,研究现存的大规模围垦和进一步最大可能的中环围垦对香港维多利亚港(维港)水动力环流的影响.数值计算显示,与1975年(大规模围垦前)海岸线相比,现存的大规模围垦使维港的水动力有几点关键性变化:①流量峰值降低了8%～17%,平均降低约11.5%;②维港东部流速峰值由于流量的减少而减少,维港西部,尽管流量减少,但由于横断面剧减,流速峰值反而增加;③雨季由于珠江径流的作用,盐度垂向分布呈明显的二层结构,而在枯季则比较均匀;④枯、雨季的潮流冲洗时间分别增加约30%和50%.在现存的海岸线下,维港枯、雨季的潮流冲洗时间分别为5～7 d和1.5～2.5 d.进一步的中环围垦不会对维港潮流冲洗率和流量产生明显影响.     

圆弧形沉积谷地对Rayleigh波三维散射解析解

采用假定的大圆弧面来模拟半空间,利用波函数展开法和有限项Fourier级数展开技术,在频域内给出圆弧形沉积谷地对Rayleigh波三维散射的一个解析解．以此解答为基础,进一步分析入射波的频率和入射角度以及谷地深度对圆弧形沉积谷地场地反应的影响．数值结果表明,入射频率和入射角度以及沉积谷地深度对沉积谷地地表位移有重要影响．     

一种考虑修复非新的多设备串行系统机会维护动态决策模型

以由不同设备组成的无中间缓冲站的串行生产系统为研究对象,通过引入整合役龄递减因子和故障率递增因子的单设备预防性修复非新模型,建立了一种基于设备可靠性的多设备串行系统机会维护动态决策优化模型.该模型满足设备只有短期信息可用的实际操作特点,可为多设备串行系统的维护决策提供有力的支持.     

非接触嵌入式信息电子Agent预测技术及设备商务平台

研究了用于非接触式(Tether-free)设备性能衰退预测的嵌入式信息电子Agent(Embedded Infotronics Agent,EIA)技术.分析了如何强化小脑模型节点控制器网络(Cerebella Model Articulation Controller,CMAC)算法,并将其运用到EIA实现的关键——看门狗(Watchdog Agent)预测技术中去;在详细分析设备商务(Device-to-Business,D2B)系统的基础上,提出定制维护(Customized Maintenance,CM)概念和理论,给出了D2B技术理论在齿轮箱衰退性能研究上的架构实例,并初步验证了相关技术的可行性.随着相关研究和应用的深入推广,传统的维护领域势必会产生革命性的变化.     

平面P波在饱和半空间中凹陷地形周围的散射规律

对平面P波在饱和半空间中凹陷地形周围的散射规律进行了研究,分析了入射波频率、边界渗透条件、孔隙率、泊松比等对散射的影响.研究表明,饱和情况(透水或不透水)与干土情况凹陷地形附近地表位移的差别很大,饱和情况与干土情况的地表位移出现相位漂移,饱和情况地表位移波长相对较大.当孔隙率较低时,边界渗透条件对地表位移幅值的影响很小,而当孔隙率较大时,边界渗透条件的影响则不可忽视:在不透水情况下,水平和竖向地表位移幅值的峰值均相对较大.随着入射频率的升高,孔隙率的影响逐渐增大,而且不透水情况下孔隙率的影响相对较大.随着泊松比的增大,水平位移幅值逐渐减小,竖向位移幅值则逐渐增大.泊松比较小时,边界渗透条件对位移幅值的影响较大;泊松比较大时,边界渗透条件对位移幅值的影响则较小.随着入射频率的升高,泊松比的影响逐渐增大.当孔隙率较小时,孔隙水压幅值较小但空间变化比较剧烈;随着孔隙率的增大,孔隙水压逐渐增大但空间变化逐渐平缓.当孔隙率达到临界状态时,孔隙水压显著增大;这与SV波入射情况完全不同.当入射频率较高时,孔隙水压幅值较大,且孔隙水压的空间变化比较复杂.