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1.
论述光纤通信高速信息网技术及最新发展,并讨论这些高速信息网的拓扑结构,协议,原理,特点和应用。  相似文献   

2.
张玉红 《科技信息》2009,(24):I0192-I0192
路局高速信息网实际上是构建一个铁路局内部专用的“互联网”,该网络在物理上和国际互联网隔绝,充分利用互联网技术接口标准、开放、简单、便于扩容、接入成本低廉等特点为铁路信息化建设提供通道承载服务。路局高速信息网组网基于TCP/IP技术,用于实现铁路各站段到各中间站、车间、班组的办公联网系统、视频会议系统、远程监视、监测、控制系统等不同系统的接入。  相似文献   

3.
俞华 《杭州科技》1996,17(4):25-27
中国政府和学术界较早地认识到建设信息高速公路对经济发展的重要作用。中国科学院院士、北京邮电大学名誉校长叶培大教授,中国科学院院士、著名通信专家陈俊亮教授,国家863高科技计划通信专家组组长、北京邮电大学副校长钟义信等教授、学者,1993年初联合向有关方面提出了“中国高速信息网计划”的构想,并把它取了一个更有特色的代号——CHINA。即“中国高速信息网计划”的英文 China High-speed Information NetworkApproach的缩写。  相似文献   

4.
介绍韩国高速信息网的发展现状,叙述了韩国信息基础实施的发展背景,目标和实施计划。  相似文献   

5.
黄翱鹏 《科技信息》2012,(26):282-282,284
在当今信息高速发展的时代,为了适应现代网络的高速发展,公司决定独立架设企业信息网,以更快捷,更安全,更简便的方式实现信息的共享及现代智能化办公。本文对某公司的网络进行了设计。  相似文献   

6.
镇江市政府利用第三期日元贷款构建的全市经济信息网络,目前通过省级技术鉴定。该网络是覆盖全市并与国内外信息网互联的高速、大容量信息传递网和社会应用服务系统.它以光纤连接构成100M高速主干网,采用美国Bay公司网络交换机、Annex通信服务器,建立了Unix、Window、NT等主流操作系统平台,并实现了互联。目前,网络已开辟了“国际经济电讯”、“互联之窗”、“每日动态”、“项目库及产品企业”、“特别专题”、“要闻检索”等栏目。镇江经济信息网通过鉴定  相似文献   

7.
该课题系杭州市科委软科学计划项目(编号95116)。课题组在文献调研和现状调研基础上,经分析研究提供了包括全球信息高速公路的情况和问题,中国高速信息网CHINA计划和实施进展,杭州市的信息网基础和问题,以及杭州市与国家信息高速公路接轨对策等内容丰富长达4万字的研究报告,为我省市信息高速公路的建设提供了发展思路、指导思想、目标框架、对策措施等一系列决策参考意见,于日前通过技术鉴定。  相似文献   

8.
百灵信息网的最大特点是“宽带、高速、无缝、稳定、安全”。在用户的接入方式上,它采用光缆到楼,双绞线入户的方式,取代了传统的电话拨号方式,用户最少可以得到10M的共享速度,有效消除了“通讯瓶颈”,622M主干、155M接入带宽使信息传输真正实现了质的飞跃。极强的兼容性可使各种网络在稳定、安全的前提下,实现高速互连、无缝接入,并使虚拟网服务得以实现,从而为社会节省巨额的网络建设费和大量的维护人  相似文献   

9.
钱秀峰 《科技信息》2010,(20):I0235-I0236
高校财务信息网是财务信息资源、服务与财务信息使用者之间的桥梁,是信息服务的重要工具,是提高财务工作服务水平和管理能力的基本要求.基于计算机网络技术的高校财务信息网,在高校财务管理中发挥着越来越重要的作用.本文就高校如何建设财务信息网进行了研究,探悉了财务信息网建设的内容和实际作用.  相似文献   

10.
沈悦林  俞华 《杭州科技》1996,17(5):19-21
近年来,世界上一些发达国家掀起了建设信息高速公路热潮。我国于1993年由中国科学院院士叶培大教授等专家提出建设“中国高速信息网计划”。与此同时,邮电部门加快了通信网的建设,“八五”期间全国建成了22条国家一级干线光缆(总长达3.2万公里)、20条数字微波干线和20个大中型卫星通信地面站。全国分组交换公用数据网进行了扩容,网络覆盖了包括267个城市,拥有2万端口,通达21个省、市的高速数字数据骨干网(DDN)已投入运行,并与世界20个国家和37个分组  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.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

14.
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   

15.
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   

16.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

17.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
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   

20.
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   

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