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991.
讨论了以地理信息系统作为建模与仿真过程的空间信息支持 ,在高层体系结构 (HLA)提供的RTI服务基础上 ,运用多线程技术实现地理信息系统作为仿真成员的HLA接口的设计与实现。实验表明 ,能够满足仿真的需求 相似文献
992.
Deriving rules from activity diary data: A learning algorithm and results of computer experiments 总被引:1,自引:0,他引:1
Theo A. Arentze Frank Hofman Harry J.P. Timmermans 《Journal of Geographical Systems》2001,3(4):325-346
Activity-based models consider travel as a derived demand from the activities households need to conduct in space and time.
Over the last 15 years, computational or rule-based models of activity scheduling have gained increasing interest in time-geography
and transportation research. This paper argues that a lack of techniques for deriving rules from empirical data hinders the
further development of rule-based systems in this area. To overcome this problem, this paper develops and tests an algorithm
for inductively deriving rules from activity-diary data. The decision table formalism is used to exhaustively represent the
theoretically possible decision rules that individuals may use in sequencing a given set of activities. Actual activity patterns
of individuals are supplied to the system as examples. In an incremental learning process, the system progressively improves
on the selection of rules used for reproducing the examples. Computer experiments based on simulated data are performed to
fine-tune rule selection and rule value update functions. The results suggest that the system is effective and fairly robust
for parameter settings. It is concluded, therefore, that the proposed approach opens up possibilities to derive empirically
tested rule-based models of activity scheduling. Follow-up research will be concerned with testing the system on empirical
data.
Received: 31 January 2001 / Accepted: 13 September 2001 相似文献
993.
Developing a bivariate spatial association measure: An integration of Pearson's r and Moran's I 总被引:1,自引:0,他引:1
Sang-Il Lee 《Journal of Geographical Systems》2001,3(4):369-385
This research is concerned with developing a bivariate spatial association measure or spatial correlation coefficient, which
is intended to capture spatial association among observations in terms of their point-to-point relationships across two spatial
patterns. The need for parameterization of the bivariate spatial dependence is precipitated by the realization that aspatial bivariate association measures, such as Pearson's correlation coefficient,
do not recognize spatial distributional aspects of data sets. This study devises an L statistic by integrating Pearson's r as an aspatial bivariate association measure and Moran's I as a univariate spatial association measure. The concept of a spatial smoothing scalar (SSS) plays a pivotal role in this task.
Received: 07 November 2000 / Accepted: 02 August 2001 相似文献
994.
Kieran P. Donaghy 《Journal of Geographical Systems》2001,3(3):257-270
This paper presents and demonstrates a general approach to solving spatial dynamic models in continuous space and continuous
time that characterize the behaviour of intertemporally and interspatially optimizing agents and estimating from discrete
data the parameters of such models. The approach involves the use of a projection method to solve the models and a quasi-Newton
algorithm to update quasi-FIML parameter estimates.
Received: 26 July 2000 / Accepted: 31 January 2001 相似文献
995.
Computer networks like the Internet are gaining importance in social and economic life. The accelerating pace of the adoption
of network technologies for business purposes is a rather recent phenomenon. Many applications are still in the early, sometimes
even experimental, phase. Nevertheless, it seems to be certain that networks will change the socioeconomic structures we know
today. This is the background for our special interest in the development of networks, in the role of spatial factors influencing
the formation of networks, and consequences of networks on spatial structures, and in the role of externalities. This paper
discusses a simple economic model – based on a microeconomic calculus – that incorporates the main factors that generate the
growth of computer networks. The paper provides analytic results about the generation of computer networks. The paper discusses
(1) under what conditions economic factors will initiate the process of network formation, (2) the relationship between individual
and social evaluation, and (3) the efficiency of a network that is generated based on economic mechanisms.
Received: 5 July 2000 / Accepted: 28 November 2000 相似文献
996.
997.
珠穆朗玛峰地区大气气溶胶元素成分的监测及分析 总被引:9,自引:8,他引:9
对珠穆朗玛峰地区大气气溶胶化学民分进行了观测和分析。初步分析结果表明,珠峰地区大气气溶胶以Al,Ca,Si,K,Fe等地壳元素为主,地壳元素占总元素浓度的82%以上。S,Pb等与人类活动影响有关的污染元素含量很低。元素S浓度为91.64ng.m^-3,元素Pb浓度仅为2.93ng.m^-3,接近于格陵兰地区的浓度,从气富集因子来看,来自地壳成分元素的富集因子要小于北京地区。而As,Pb等与人类活动有关的气溶胶元素的富集因子也比北京地区低得多。研究表明,人类活动对珠峰地区的影响很小。 相似文献
998.
999.
利用2993个浅源地震的地震矩张量解、404个P波初动方向震源机制解和47个深井孔的孔壁崩落资料,编制了东亚地区现今地壳构造应力场主应力方向和应力类型分布图.按200km的等距格点,算出有资料地区各格点半径为200km范围内的平均应力方向,绘制了平均主应力方向分布图,并绘制了东亚地区的震源机制解分布图.主应力方向分布特征表明,东亚地区的现今构造应力场除受印度 欧亚板块碰撞的强烈影响外,俯冲带的弧后扩张亦有重要影响.喜马拉雅山弧处的大陆碰撞和缅甸山弧处的弧后扩张之联合作用可能形成了青藏高原东南部主应力方向的显著转动.菲律宾海板块与欧亚板块在台湾的碰撞与琉球岛弧弧后扩张的联合作用影响了中国东部的应力场.爪哇海沟俯冲带的弧后大片地区现今没有强震活动,这里的弧后扩张可能是造成东南亚地区物质容易向南运动的因素.青藏高原内部大致以昆仑山为界,北部和东北部是大陆内部的宽阔挤压带,南部和西南部地壳上部主要处于正断层型应力状态中. 相似文献
1000.
IntroductionFor the need of a nuclear test ban treaty, international society must make great efforts to find effective methods for discrimination between earthquake and nuclear explosion. Thereupon, many methods of discrimination of nuclear explosion appeared. But, at present, there is some uncertainty to discriminate middle or small nuclear explosion (Peppin, McEvilly, 1974; Richards, Zarales, 1990). When we study tectonic ambient shear stress field of Southern California, we find that str… 相似文献