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1.
基于LBS应用的分布式移动GIS技术实现   总被引:6,自引:0,他引:6  
分布式移动地理信息系统是传统GIS在21世纪移动互联网时代发展的新方向。笔者分析了应用于空间定位服务(LBS)的分布式移动地理信息系统(DM-GIS)的原理、特点和有关关键技术,提出了应用DM-GIS技术的解决方案。  相似文献   

2.
针对目前入侵检测系统的不足,将新型分布式处理技术移动Agent与入侵检测融为一体,提出了一种基于移动代理的分布式入侵检测系统(DIDS)的模型;实现了基于该模型的分布式入侵检测系统;采取了保证分布式入侵检测系统自身安全的防范措施.通过移动代理,各Agent相互独立,同时能在网络中自由移动,并具有良好的灵活性,降低了网络通信量和系统负载,有效保证系统的安全.  相似文献   

3.
利用地理信息系统(GIS)这种先进的技术系统,在高校已有校园网上构架分布式网络校园地理信息系统(CCGIS),将高校校园中大量与空间位置有关或具有空间内涵的地理数据有效管理起来,不仅极大地丰富了校园网上的资源,并提供了一种全新的信息查询与检索手段,可以全面提高高校管理水平。  相似文献   

4.
采用分布式监测机制来实现多媒体网络业务QoS(服务质量)保证是一个重要的研究方向。首先分析当前多媒体网络QoS分布式监测方法的相关研究;然后将移动代理技术引入QoS分布式监测方法,提出一种基于移动代理的QoS分布式关联监测框架;并以该框架为基础提出一种基于移动代理的QoS劣化网段定位方法。仿真表明了该方法的实时性和有效性,也表明提高了网络接口利用率和减少了网络时延。  相似文献   

5.
介绍了几种常见的分布式入侵检测系统,针对目前入侵检测系统的不足,将新型分布式处理技术移动 Agent与入侵检测融为一体,提出了一种基于移动代理的分布式入侵检测系统(DIDS)的模型.系统采用层次 结构的探测和响应机制,各Agent相互独立,同时能在网络中自由移动、相互协作,以检测分布式攻击,并具 有良好的灵活性、健壮性和可扩展性.  相似文献   

6.
传统的分布式移动管理方案虽然能解决集中式移动管理方案的不足,但在移动结点发生切换时,仍然需要建立隧道,从而增加了网络开销.为了解决这一问题,利用软件定义网络(SDN)中控制平面与转发平面相分离的特点,在SDN架构下提出一种新的基于网络的分布式移动管理方案(NNDMM),该方案能充分发挥SDN的优点,同时不会给控制器造成额外的压力.建模分析表明:相对于传统的分布式移动管理方案,无论在信令费用上,还是包递送费用上,NNDMM方案都有明显的优势.  相似文献   

7.
移动源已成为城市大气污染的主要贡献源.基于MOVES模型和地理信息系统(ArcGIS)技术,建立了宜宾市2018年分辨率为2 km×2 km的移动源网格化排放清单.研究结果表明:宜宾市2018年移动源污染物碳氢化合物(THC)、CO、NOX、PM2.5、PM10、NH3、SO2和挥发性有机化合物(VOC)的年排放量依次...  相似文献   

8.
组件式交通地理信息系统设计与开发   总被引:3,自引:1,他引:3  
地理信息技术在交通领域有着广泛的应用。分析了交通地理信息系统设计和开发中的几个关键问题,提出了基于Java-CORBAR的分布式交通地理信息系统设计模型,并对交通地理信息系统的发展趋势进行了展望。  相似文献   

9.
李锋 《海峡科学》2000,22(4):74-75
近年来,随着因特网技术和通讯技术的快速发展,地理信息系统在各行各业的应用也得到迅速发展.本文探讨了使用EJB组件模型进行网络地理信息系统数据集成的原理,提出了一种在Web环境下,对于日益复杂的分布式地理数据,相应采取分布式组件的处理方法.  相似文献   

10.
张彦敏 《科技信息》2011,(12):I0218-I0219,I0221
空间数据库是地理信息系统研究的重点也是一个难点。分布式空间数据库系统的提出不但符合地理信息系统发展的趋势,同时也是数据共享的要求。研究高效的分布式实时空间数据传输方法不但是分布式空间数据库系统的重要研究内容,也是当前地理信息服务的重点。本文根据面向对象的思想设计了一种把空间数据和属性数据组成一个整体,利用oracle数据库触发器机制和SQL/PLUS编程语言,把整体数据传输到分布式节点。为了降低网络负担,本文根据所传输的数据里有无空间数据而进行了优化。实验结果表明,本文提出的方法在配电网地理信息系统中得到很好的应用,其速度完全满足电力系统方面的应用。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

14.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

15.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

16.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

17.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

18.
For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the  相似文献   

19.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

20.
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