交通地理信息系统中的时空动态分段模型研究

动态分段技术是交通地理信息系统(GIS-T)中一项重要的线性要素动态显示与分析技术,该文提出了一种时空动态分段模型,使动态分段系统的组成成分融入时态因素,并将属性的时态信息作为属性信息表的字段存储,通过时态地理信息系统技术完成物理段的时态变化。利用统一建模语言(UML)的类图设计方式开发了物理模型,描述了时空动态分段模型中对象之间的关系,并定义了必要的属性和操作;同时基于线性参照系统(LRS)表达空间实体的方法,概括了模型中所涉及到的主要拓扑关系。实验表明,时空动态分段模型弥补其他模型将时空参考分为时间参考和空间参考所产生的不足,而且更明确地将多重属性和物理实体有机结合起来。     

岩溶多重介质地下水模拟技术及应用进展

由于岩溶发育的极不均匀性和岩溶含水介质的多重介质性等特征,使得岩溶水系统的地下水运动规律呈现出复杂多变的特点,在孔隙或微小裂隙含水介质中岩溶水满足达西流,而在岩溶管道中可能出现非达西运动,这给岩溶区地下水模拟带来了极大挑战。系统地梳理了岩溶水流和溶质运移模拟的主要方法,总结了复杂岩溶多重介质系统地下水模拟技术的现状,并结合我国南方岩溶和北方岩溶各自的特点,提出岩溶水模型在实际应用中需要关注的要点。主要包括：需加强野外调查和观测,提高模型中对岩溶含水介质结构非均质性表征的精度;进一步深化对岩溶水运动机理的研究,刻画岩溶多重介质的水流特征以及水交换机理;针对北方岩溶水系统模拟,可选择等效连续多孔介质模型,重在耦合区域分布的岩溶溶孔-裂隙介质中慢速渗流与脉状分布的强径流带快速流;对于南方岩溶区,建议考虑建立分布式流域水文模型与能刻画集中管道流多流态变化的多重介质模型的岩溶地下水耦合模型。     

Windows钩子技术的研究与应用

综述了Windows平台下钩子函数的特点及应用.在Windows消息机制下,深入讨论了利用Windows钩子函数,进行嵌入式程序设计的原理及方法,并给予相应的简略实现过程.由目前嵌入式硬件迅速发展的前景,利用钩子,作了用软件来模拟硬件的有益尝试.     

Deriving Changjiang coastal zone wind from C-band SAR and its application to salinity simulation

Wind plays an important role in hydrodynamic processes such as the expansion of Changjiang （Yangtze） River Diluted Water （CDW）, and shelf circulation in the Changjiang estuary. Thus, it is essential to include wind in the numerical simulation of these phenomena. Synthetic aperture radar （SAR） with high resolution and wide spatial coverage is valuable for measuring spatially inhomogeneous ocean surface wind fields. We have collected 87 ERS-2 SAR images with wind-induced streaks that cover the Cbangjiang coastal area, to verify and improve the validity of wind direction retrieval using the 2D fast Fourier transform method. We then used these wind directions as inputs to derive SAR wind speeds using the C-band model. To demonstrate the applicability of the algorithms, we validated the SAR-retrieved wind fields using QuikSCAT measurements and the atmospheric Weather Research Forecasting model. In general, we found good agreement between the datasets, indicating the reliability and applicability of SAR- retrieved algorithms under different atmospheric conditions. We investigated the main error sources of this process, and conducted sensitivity analyses to estimate the wind speed errors caused by the effect of speckle, uncertainties in wind direction, and inaccuracies in the normalized radar cross section. Finally, we used the SAR-retrieved wind fields to simulate the salinity distribution off the Changjiang estuary. The findings of this study will be valuable for wind resource assessment and the development of future numerical ocean models based on SAR images.     

虚拟局域网技术分析及其在校园网中的应用

探讨虚拟局域网技术.基于端口的VLAN(虚拟局域网)技术在保证了VLAN本身灵活性的同时,又为网络的安全管理提供了有效的技术手段.利用Cisoo交换机,按端口组网的方法建设校园网.     

信息技术应用与提升企业竞争优势关系的实证研究

探究了信息技术的应用与企业竞争优势提高的关系,以某制造企业在北美,欧洲,亚洲的3家企业实施ERP数据为例进行了实证分析.通过交货期衡量企业绩效,建立了多元回归分析模型.研究结果显示信息技术本身并不存在生产率悖论问题.3家企业在实施ERP之后订单交货期均缩短了,但这并不能够给企业带来长期的竞争优势,并从基于能力的竞争理论的角度分析了其中原因.     

Approach to modeling and virtual-reality-based simulation for plant canopy lighting

Over the past 20 years, significant progress has been made in virtual plant modeling corresponding to the rapid advances in information technology. Virtual plant research has broad applications in agronomy, forestry, ecology and remote sensing. As many biological processes are driven by light, it is the key for virtual plant to estimate the light absorbed by each organ. This paper presents the radiance equation suitable for calculating sun and sky light intercepted by plant organs based on the principles of the interaction between light and plant canopy firstly; analyzes the process principles of plant canopy primary lighting based on ray casting and projection secondly; describes the multiple scattering of plant lighting based on Monte Carlo ray tracing method and on the radiosity method thirdly; and confirms the research with 3D visualization based on Virtual Reality Modeling Language （VRML） finally. The research is the primary work of digital agriculture, and important for monitoring and estimating corn growth in Northeast China.     

Utilization pattern of Olympic parks and its application in Beijing

With great promotion of mega-events in both quantities and qualities in China, the research of Mega-events has been increased. As a global hallmark event, the Olympics, with their enormous scale, universal at- traction for the media and tremendous political significance, have increasingly drawn attention from the researchers. It is obvious that Beijing has been greatly impacted by the 2008 Olympic Games as the host. The event aroused close attention of researchers, especially the problem how the Olympic stadiums and facilities can be utilized after Olympic Games. The paper employed 3 methods to conduct a survey, that is, sending questionnaires to tourists, in- terviewing with government officers, and collecting information about former Olympic Parks from Internet and literatures. The utilization of former Olympic Parks after Games was summarized and some experiences were refined. Besides, 3 main bodies including government, business operators and visitors which formed basic driving forces to influence the park′s use were analyzed. At the same time, the paper believes that 3 topics affect the park′s utilization involving ′prepare to use′, ′how to use it′ and ′how to manage it′, and Beijing Olympic Park can also follow that thinking and reference in the further practices. Based on it, suggestions are given that Beijing Olympic Park can be planned spatially from 3 layers, the point, line and area, based on their function and infrastructure in the Games, and the area would be shaped as a new urban center with multi-functions while Mega-events and sport events are still the main content of the park.     

模型和模型方法

根据模型与原型的关系 ,把模型分为物质模型和观念模型两大类 ,并从科学研究的目的出发 ,分别探讨了建立两大类模型的典型方法——模拟方法和理想化方法     

MATLAB在运用系统建模处理南海气象数据过程中应用

介绍了MATLAB语言特点和系统建模方法的基本理论.根据南海气象数据的实际建模处理过程,给出了建模的详细步骤及其MATLAB实现过程以及MATLABTM的主要实现程序.试验讨论和结果表明利用MATLAB语言可以方便地对南海气象数据用系统建模方法进行建模和处理,MATLAB在运用系统建模法处理南海气象数据方面具有明显的优越性.