NS2网络仿真器功能扩展方法及实现

NS2作为开源软件缺少对最新研究算法的模拟能力 .在现有软件基础上对其进行功能扩展极其必要 ,是模拟研究新理论新算法的基础 .本文着重探讨网络仿真软件 NS2的功能扩展原理及设计实现 ,展示运用 NS2仿真器对网络行为进行研究的过程 .最后对该算法进行模拟实验 ,并与已有 RED和 PI算法进行性能对比分析 .

基于改进网络模型的大时滞网络拥塞控制算法

　随着对网络拥塞控制的深入研究,出现了许多有关网络流量的控制理论及网络模型.Misra等人于2000年基于流体流(fluidflow)理论提出的模型被研究人员广为采用.但模型在推导过程中的一些近似却使得模型对网络行为描述不精确.本文对此从理论和实验结果两方面进行了详细分析,并对原模型进行了改进.基于改进的模型,把一种PID(ProportionalIntegralDifferential)及类PID设计方法用于AQM(ActiveQueueManagement)控制器的设计.对比仿真结果表明,该算法具有更好的性能.

一种开放源代码的网络仿真器的原理与实现

随着互联网的飞速发展,网络拥塞已经成为一个十分重要的问题,网络仿真是一种检测拥塞控制算法有效性的常用方法.该文给出了一种开放源代码的网络仿真器NS2(Network Simulator V2)的原理与实现.首先比较了四种不同仿真器的优缺点,然后详细描述了NS2的模块组成、工作环境、主代码结构以及扩展方法等,最后用RED(Random EarlyDetection)队列调度和移动IP数据传输两个典型实例说明了NS2的应用价值.

基于D稳定域和ITAE准则的主动队列管理算法

主动队列管理（active queue management，简称AQM）是网络拥塞控制的研究热点之一，其中的关键问题是如何设计反馈控制策略．提出一种新的基于D稳定域和时间乘以误差绝对值乘积积分（integral of time-weighted absolute error,简称ITAE）性能准则的比例-积分-微分（proportional-integral-differential，简称PID）优化设计方法（简称DITAE-PID），并用于AQM控制器的设计，控制闭环系统的理想动态性能．首先在复平面上设定一组理想的D稳定域，然后以ITAE为目标函数，通过数值优化算法求出控制器的参数，使得闭环系统的所有特征根都在D稳定域内，以降低排队延时，提高有效吞吐量．对比仿真实验结果表明孩算法能够预先探测和控制拥塞，有较好的鲁棒性，链路利用率更高，丢包率更小，平均队列长度更趋于期望值，同时，趋于期望队列长度的时间更短，其综合性能明显优于典型的随机早期探测（random early detection，简称RED）和比例-积分（proportional-integral，简称PI）算法．

星球探测系统的多机器人组内协作研究

建立了子机器人的控制模型,提出了分散式控制与集中式控制相结合的复合控制体系。采用动态分配ID号和由ID号确定机器人组中领导者的机制,建立了有领导者的机器人组的协作方法。其中,领导者与监控平台之间采用无线通讯,机器人组内采用CAN(control area network)总线传递控制信号。同时采用组内基于状态表匹配的控制方式。两个机器人组合利用以上机制,通过相互协调完成差速转弯的实验验证了该控制方法的可行性。

水下机器人的神经网络自适应控制

研究了水下机器人神经网络直接自适应控制方法,采用Lyapunov稳定性理论,证明了存在有界外界干扰和有界神经网络逼近误差条件下,水下机器人控制系统的跟踪误差一致稳定有界.为了进一步验证该水控制方法的正确性和稳定性,利用水下机器人实验平台进行了动力定位实验、单自由度跟踪实验和水平面跟踪实验等验证实验.

Optical two-dimensional SW-banyan network: Optical implementation, routing control, and determination of permissible permutations

A 2-D SW-banyan network is introduced by properly folding the 1-D SW-banyan network, and its corresponding optical setup is proposed by means of polarizing beamsplitters and 2-D phase spatial light modulators. Then, based on the characteristics and the proposed optical setup, the control for the routing path between any source-destination pair is given, and the method to determine whether a given permutation is permissible or not is discussed. Because the proposed optical setup consists of only optical polarization elements, it is compact in structure, its corresponding energy loss and crosstalk are low, and its corresponding available number of channels is high. (C) 1996 Society of Photo-Optical Instrumentation Engineers.

Construction and control of plasmid DNA network

The influences of different cations on plasmid DNA network structures on a mica substrate were investigated by atomic force microscopy (AFM). Interactions between the DNA strands and mica substrate, and between the DNA strands themselves were more strongly influenced by the complex cations (Fe(phen)(3)(2+), Ni(phen)(3)(2+), and Co(phen)(3)(3+)) than by the simple cations (Mg2+, Mn2+, Ni2+, Ca2+, Co3+). The mesh height of the plasmid DNA network was higher when the complex cations were added to DNA samples. The mesh size decreased with increasing DNA concentration and increased with decreasing DNA concentration in the same cation solution sample. Hence, plasmid DNA network height can be controlled by selecting different cations, and the mesh size can be controlled by adjusting plasmid DNA concentration.

Origin of rabbit (Oryctolagus cuniculus) in China: evidence from mitochondrial DNA control region sequence analysis

A fragment of mitochondrial DNA (mtDNA) control region (similar to700 bp) was sequenced in 104 individuals from 20 breeds (three Chinese domestic breeds, five recently derived breeds and 12 introduced breeds) of domestic rabbits, Oryctolagus cuniculus . Nineteen sites were polymorphic, with 18 transitions and one insertion/deletion, and eight haplotypes (A1, A2, A3, A4, A5, A6, A7 and A8) were identified. Haplotype A1 was the most common and occurred in 89 individuals. In the 25 Chinese rabbits, only haplotype A1 was observed, while four haplotypes (A1, A3, A5 and A6) were found in 26 recently derived individuals. Haplotype A2 was shared by seven individuals among three introduced strains. The other six haplotypes accounted for 0. 96-1. 92% of the animals. Combined with the published sequences of European rabbits, a reduced median-joining network was constructed. The Chinese rabbit mtDNAs were scattered into two clusters of European rabbits. These results suggest that the (so-called) Chinese rabbits were introduced from Europe. Genetic diversity in Chinese rabbits was very low.

Compact Reconfigurable Binary-Decision-Diagram Logic Circuit on a GaAs Nanowire Network

We describe a reconfigurable binary-decision-diagram logic circuit based on Shannon's expansion of Boolean logic function and its graphical representation on a semiconductor nanowire network. The circuit is reconfigured by using programmable switches that electrically connect and disconnect a small number of branches. This circuit has a compact structure with a small number of devices compared with the conventional look-up table architecture. A variable Boolean logic circuit was fabricated on an etched GaAs nanowire network having hexagonal topology with Schottky wrap gates and SiN-based programmable switches, and its correct logic operation together with dynamic reconfiguration was demonstrated.

Determining of the delay time for a heating ventilating and air-conditioning plant using two weighted neural network approach

This paper presents an two weighted neural network approach to determine the delay time for a heating, ventilating and air-conditioning (HVAC) plan to respond to control actions. The two weighted neural network is a fully connected four-layer network. An acceleration technique was used to improve the General Delta Rule for the learning process. Experimental data for heating and cooling modes were used with both the two weighted neural network and a traditional mathematical method to determine the delay time. The results show that two weighted neural networks can be used effectively determining the delay time for AVAC systems.