基于DHT的P2P网络资源定位模型研究

目的分析和讨论目前流行的P2P网络模型,探讨基于DHT(Distributed Hash Table)的资源定位方法,提出一种改进的kademlia模型。方法将虚拟节点引入结构化P2P系统,对P2P网络节点进行筛选以提高网络运行效率,使之能自适应地进行网络规模调整,在拓扑形成时充分利用网络访问的区域性和物理网络中节点的邻近特性降低访问延迟和路由长度。结果模拟测试表明模型在路由选择和访问延迟方面的表现均优于原Kademlia算法。结论改进后的模型继承了DHT和Kademlia的优点,有助于改善P2P网络的可扩展性和可管理性,优化路由,减少网络开销,从而提高网络资源的利用率,适合面向Internet规模的文件共享、协同工作等P2P应用。     

Reversal current observed in micro-and submicro-channel flow under non-continuous DC electric field

In practical applications of biochips and bio-sensors, electrokinetic mechanisms are commonly employed to manipulate and analyze the characteristics of single bio-molecules. To accurately and flexibly control the movement of single molecule within micro-/submicro-fluidic channels, the characteristics of current signals at the initial stage of the flow are systematically studied based on a three-electrode system. The current response of micro-/submicro-fluidic channels filled with different electrolyte solutions in non-continuous external electric field are investigated. It is found, there always exists a current reversal phenomenon, which is an inherent property of the current signals in micro/submicro-fluidics Each solution has an individual critical voltage under which the steady current value is equal to zero The interaction between the steady current and external applied voltage follows an exponential function. All these results can be attributed to the overpotentials of the electric double layer on the electrodes. These results are helpful for the design and fabrication of functional micro/nano-scale fluidic sensors and biochips.     

PCI EXPRESS的发展和应用趋势

本文分析了PCI总线标准的特点,介绍新的发展方向PCI Express总线的产生背景,并对PCI Express总线的拓扑构架进行分析,提出其应用趋势。     

现代科技革命与水文地质学发展

近半个世纪以来,现代科学技术取得了突飞猛进的发展。水文地质学作为科学技术领域中一个不可或缺的重要组成部分,也经过长期的发展逐渐变得成熟起来。本文以水文地质学发展的历史为主线,以自然辩证的观点论述其对马克思主义哲学的证实与发展。探讨了现代科技革命对水文地质学发展的影响,初步探讨了当代水文地质学发展方向。