共查询到20条相似文献,搜索用时 26 毫秒
1.
概率路由算法是机会网络中一种常用的路由算法,其TTL的设置将直接影响路由的性能.本文首先利用马尔可夫链对概率路由的转发过程进行建模,并从消息的传输成功率和传输延时方面进行性能评估,不仅可以计算出一个消息从源节点到目的节点所需的传输延时,还可以预测出在给定传输成功率下所需要的最短消息生存周期TTL,这对于TTL的设置具有理论上的指导作用.其次,本文建立的预测模型还可以使一些无法到达目的节点的消息及时被删除,从而减少不必要的转发,达到节约网络资源的目的.最后,在两个真实数据集中的实验结果表明,本文提出的模型能够为概率路由中TTL值的准确设置提供有效参考. 相似文献
2.
An equivalent circuit model of millimeter wave second harmonic oscillator stabilized with a transmission cavity has been proposed for constructing analytical formulations between performance parameters of the oscillator and parameters of the circuit. The model consists of an equivalent circuit of fundamental wave and that of second harmonic wave. Each of the circuits comprises circuit models of main cavity, transmission waveguide, and transmission cavity. Absorbing material placed between the transmission waveguide and the transmission cavity can suppress additional resonances originated from transmission cavity. The behavior of the second harmonic oscillator can be effectively described by the circuit model. Furthermore, based on this model, mechanical tuning characteristics have been studied at first, and then analytical formulas for quality factor and efficiency depending on circuit parameters have been derived. The circuit parameters can be conveniently extracted by electromagnetic field simulation. Hence the formulas exhibit both compact form and enough accuracy. Thereafter, general rules of performance parameters varying with circuit parameters have been deduced for the harmonic oscillators. Then some design considerations have been derived according to the corresponding analysis. The equivalent circuit model is useful for designing and adjusting millimeter wave second harmonic stabilizing oscillator with a transmission cavity. 相似文献
3.
改进SIR模型在社交网络信息传播中的应用 总被引:1,自引:0,他引:1
通过对社交网络结构的分析,将热传播结点引入网络,提出基于改进SIR的信息传播模型,并利用Tumblr中的实际数据进行仿真分析。结果表明,随着免疫概率的降低以及网络推手或普通传播者与易感者接触率的增加,信息在网络中的传播范围和传播速度都将得到一定的提升,在不加控制的情况下,信息会传播给特定网络中的大多数用户。改进的SIR模型可以较准确地揭示信息在社交网络中传播的内在规律。 相似文献
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采用基于蒙特卡罗的多次散射模型,研究无 公共散射体传输模型下紫外光(UV)传输特性,对该模型下 UV在大气中传输的平均散射次数随距离的变化情况、路径损耗随传输距离的变化情况 、脉冲响应时间 延迟随传输距离的变化情况以及脉冲响应曲线随能见度的变化情况进行仿真分析。结果显示 ,无公共散射体 传输模型下的UV至少需要两次的大气散射才能够到达接收端,相同传输距离无公共散 射体传输模型的 路径损耗和脉冲响应时间延迟也远高于有公共散射体传输模型的路径损耗和脉冲响应时间 延迟。通过归 一化得到的随能见度变化的脉冲响应曲线发现,无公共散射体传输模型在大气中传输的 脉冲响应时间 延迟不随能见度的变化而变化,但脉冲响应峰值高度随能见度的增大而增高。 相似文献
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以高性能警戒-引导雷达为模型,研究了适合雷达信号宽带远程传输的协议体系,重点对应用层协议进行了设计,并用Visual C++开发实现了专用通信软件。而后基于专门构建的宽带网络平台对软件进行了测试仿真。仿真结果表明其传输性能良好,可满足雷达信号宽带远程传输的要求。 相似文献
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This paper presents a performance analysis of a PLC-1 private line voice concentrator which uses speech interpolation to increase the capacity of transmission facilities. The PLC-1 employs speech storage. As a result it can be applied to relatively small trunk groups where statistics of loading patterns are particularly unfavorable. Speech impairments can be categorized as delay, gap modulation, and clipping. A mathematical model based on queueing theory is presented for the evaluation of the statistics of these impairments. The model can be used to determine obtainable TASI advantage for various system configurations and loading conditions. It is shown that a TASI advantage of two is achievable with 24 transmission facilities. The veracity of the queueing model is established using simulation techniques. 相似文献
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虚拟主机云存储系统整数规划模型及最优化分配算法 总被引:1,自引:1,他引:0
随着网络存储技术的发展,如何提高广域网网络存储系统的传输性能和存储容量是亟待解决的问题。本文提出一个基于虚拟主机集群的云存储系统(VCloud Storage),具有良好的负载均衡能力,提高了文件传输性能,同时解决了存储容量无限扩展的问题。本文提出的云存储系统首先抽象虚拟主机运行状态数学模型,然后在虚拟主机运行状态数学模型的基础上建立整数规划模型,利用隐枚举算法,最优化分配虚拟主机给客户端模块的存储请求,最终客户端模块与虚拟主机接口协作完成文件传输。实验结果表明:采用本文提出的模型及算法具有明显的优化效果,VCloudStorage总吞吐量和平均传输率均优于微软SkyDrive存储、腾讯QQ邮箱存储和单虚拟主机存储。本文提出的模型及算法增强了文件传输性能和稳定性,是提高广域网网络存储系统性能的一条有效思路。 相似文献
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本文结合付里叶变换和拉氏变换技术,得出了具有任意非零初始电压、电流分布的多导体传输线的等效时域线性网络模型,传输线可以为有耗丰均匀性,该模型可与常用电路分析软件接口,因而可处理非线性终端负载,给出了一个应用本文模型进行瞬态分析的例子。 相似文献
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如何设计最优的频谱感知与传输框架是认知无线电技术的重要环节。考虑频谱接入过程中数据传输中断对认知网络性能影响的问题,提出了一种新的基于传输中断概率的频谱感知与传输模型,联合优化频谱感知和数据传输两个阶段,将问题建模为对主用户的干扰量约束条件下的非凸优问题,以最大化认知网络吞吐量为目标联合优化感知时间、传输速率,并通过数值计算方法对其进行求解与仿真。数值分析表明,引入传输中断概率后,在满足上述约束条件的同时,在保护主用户和认知网络吞吐量、传输时延之间有了更好的权衡。 相似文献
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因为太赫兹技术可以克服传统无损检测技术的局限性,具有穿透普通非金属材料等优点,可被用于分析层状材料的内部结构和内层厚度。本文首先介绍了太赫兹时域光谱系统(THz-TDS)在透射模式下的工作原理,然后使用Rouard等效界面理论来描述多层结构中波的传播,推导得到透射模式下太赫兹波在三层介质中的理论传输模型。通过太赫兹时域光谱系统对制备的样品进行了透射成像。结果证明样品内部聚氯乙烯(PVC)薄片的位置和形状等信息可以被探测到,从而为探测多层材料内部结构提供理论和实验依据。 相似文献
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G.K. Reeves 《Solid-state electronics》1980,23(5):487-490
The measurement of the specific contact resistance of ohmic contacts to semiconductors can be made in a number of ways. One of the methods uses a transmission line model of an ohmic contact on a semiconductor and this paper describes the application of the transmission line model to a contact test pattern of circular symmetry. By using a circular test pattern, the mesa etch step necessary for the standard rectangular test pattern may be omitted, thus simplifying test pattern fabrication. 相似文献
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A simple statistical model is proposed which simulates errors on digital transmission channels and accommodates the tendency for errors to occur in bursts. The model only needs three parameters to be simulated, all of which can be measured from live channels of interest 相似文献
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Hopman W.C.L. van der Werf K.O. Hollink A.J.F. Bogaerts W. Subramaniam V. de Ridder R.M. 《Photonics Technology Letters, IEEE》2008,20(1):57-59
We present a transmission model for estimating the effect of the atomic-force microscopy tapping tip height on a photonic crystal microcavity (MC). This model uses a fit of the measured tip-height-dependent transmission above a ldquohot spotrdquo in the MC. The predicted transmission versus average tapping height is in good agreement with the values obtained from tapping mode experiments. Furthermore, we show that for the existing, nonoptimized structure, the transmission coefficient can be tuned between 0.32 and 0.8 by varying the average tapping height from 26 to 265 nm. A transmission larger than that of the undisturbed cavity at resonance was observed at specific tip locations just outside the cavity-terminating holes. 相似文献
18.
《Electron Device Letters, IEEE》1982,3(5):111-113
In characterizing ohmic contacts using the transmission line model, it is necessary to make a measurement referred to as the contact end resistance, as a result of modification to the sheet resistance under the contact. In this article we show that this contact end resistance and the consequent specific contact resistance can be deduced from simple resistance measurements carried out between contacts on a standard, transmission line model test pattern. 相似文献
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