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1.
提出了一种下行采用10 Gbit/s广播,上行采用1 Gbit/s波分多址的万兆以太无源光网络体系结构,该结构实际上下行为点对多点,上行为点对点.为解决该体系结构下的MAC(媒体接入控制)层协议控制问题,提出了一种协议模型.有别于IEEE标准802.3ah-2004的MPMC(多点MAC控制)子层,该模型提出了MWMC(多波长MAC控制)子层.给出了该结构下P2PE(点对点仿真)的实现方法,包括MWMC子层和调和层的扩展与修改以及10GBASE-R和1000BASE-X的物理层的扩展.通过点对点仿真可以使基于波分多址的万兆以太无源光网络在协议层面看起来就像上下行均采用点对点技术一样.  相似文献   

2.
无线资源控制(RRC)子层位于空中接口协议栈的第3层,它主要完成无线资源的控制和管理功能.文章的研究对象是RRC子层连接建立过程,即信令连接建立过程,详细分析了该过程的具体流程和可能出现的异常情况,并对资源的分配做了简要描述.  相似文献   

3.
针对用户呼叫层和分组层的不同运行机制,建立了认知无线电网络呼叫层和分组层相互关系的跨层马尔可夫模型,推导了次用户的呼叫阻塞概率和分组时延的表达式,提出了一种基于跨层建模的随机频谱接入新机制,并对认知无线电网络进行了系统级仿真.结果表明,文中模型能够准确地评估认知无线电网络的性能,随机频谱接入新机制可同时保证次用户呼叫层和分组层的性能要求.  相似文献   

4.
为提高电梯控制系统程序代码的通用性,适用不同层数电梯的控制要求,提出了一种新颖的控制策略,建立了以层为基础的电梯运行的动态二进制数学模型,动态识别出电梯的各种呼叫状态,利用这些呼叫状态作为电梯定向和升降的状态转移条件,成功地将动态过程简化为静态处理,简化了电梯控制系统控制的复杂性.该控制方法实现容易,提高了通用性,可推广应用.  相似文献   

5.
第三代移动通信系统TD-SCDMA是一种自干扰的系统.随着未来用户的增加,在无线资源相对有限的情况下,有效控制干扰的要求越来越高,而呼叫接纳控制技术(CAC)就是解决这一问题的关键技术之一.该文提出了基于功率控制的呼叫接纳控制算法,以小区负荷因子为分析参数,分析新用户满足接纳请求的条件,进而对新的呼叫请求作出判断.该算法充分考虑了系统中各种干扰,更加符合实际的网络环境,同时满足了无线用户日益提高的QoS要求.  相似文献   

6.
支持PSTN向NGN演进的协议-BICC   总被引:2,自引:0,他引:2  
在传统电信网向下一代网络(NGN)的演进过程中7为了既能实现与现有网络的兼容,又可以实现对任何分组网络的承载,ITU-T提出的承载无关呼叫控制--BICC成为目前的一个研究热点.首先介绍了BICC的体系架构与功能模型,接着分析了BICC的呼叫流程,最后给出了如何实现BICC对IP网络的承载控制.  相似文献   

7.
无线资源控制(RRC)子层位于空中接口协议栈的第3层,它主要完成无线资源的控制和管理功能。文章的研究对象是RRC子层连接建立过程,即信令连接建立过程,详细分析了该过程的具体流程和可能出现的异常情况,并对资源的分配做了简要描述。  相似文献   

8.
利用等离子增强化学气相淀积(PECVD)技术制备a-SiH/SiO2多层膜,并采用脉冲激光诱导限制结晶的方法,对a-SiH/SiO2多层膜进行晶化.喇曼(Raman)散射谱的结果表明经过激光辐照后纳米硅颗粒在原始的a-SiH子层形成,且尺寸可以精确控制.  相似文献   

9.
呼叫接纳控制是通讯网络设计与运营中的一个重要优化问题. 环网络中,这一问题的目标是对于给定的具有边容量的环网络和任意利润的呼叫的集合,确定最大利润的呼叫子集并为其中每一个呼叫安排路径,使得任一边容量不被违反. 对于无向和有向环网络呼叫接纳控制问题, 均给出了多项式时间近似方案.  相似文献   

10.
分布式智能型呼叫接纳控制(DICAC)方法即模糊估计新呼叫用户等效干扰,利用神经网络估计系统内已连接用户下一时刻总干扰水平,综合考虑本小区及相邻小区用户QoS反馈信息,由模糊接纳判决处理器输出接纳判决结果.该方法将分布式思想引入智能呼叫接纳控制,提出加权和等效相邻小区掉线概率概念,同时考虑本小区及相邻小区的负载状况和QoS要求.仿真结果表明,对于新用户的接纳,能够在保证本小区用户QoS要求的同时,周围相邻小区用户的通话质量也不受影响,能够满足用户掉线率及呼叫阻塞率的要求.  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.
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   

13.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  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.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  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.
19.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

20.
Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with  相似文献   

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