Analysis on the optimum dynamic quality of wireless mesh network

In order to procure the optimum quality of control for full-controlled wireless mesh network, the primary influencing factor network time delay is analyzed. In order to get the optimum quality of control,the minimum network time delay should be acquired,and the algorithm of branch and bound is given to solve this problem. According to the numerical simulation, the quality of control for the whole network system with decreasing the delay time can be optimized by adjusting the number of nodes, the average transmission hop counts, and the probability of successful channel access and transmission for random nodes.     

A borrowed address based on efficient distributed address assignment algorithm in ZigBee networks

The borrowed address algorithm can solve the orphan problem made by the restriction of threshold of children when DAAM(distributed address assignment mechanism) assigns the addresses for the nodes in ZigBee networks. The exited borrowed algorithms only can increase the success ratio of address assignment, but their overhead and times spend on founding net cost much. To address the problem, we propose an efficient borrowed address assignment algorithm EDAA BA (efficient distributed address assignment algorithm based on borrowed address). To control the overhead and time spend on founding net, it borrows addresses firstly from the descent nodes in same branch for the orphan router nodes, adds the mechanism of immediate reply of borrowed message, and assigns the remainder addresses unused by DAAM in the 16 bits addresses for the orphan end devices. Theoretical and simulation analyses show that our algorithm outperforms DAAM and two of its present improvement algorithms in terms of the overhead and time spent on forming network, under the premise of better success rate of address assignment.     

无线网络接入点TCP流时间公平性

对无线网络接入点上下行TCP流存在的时间不公平性现象进行了研究,报告了无线网络接入有线网络存在的拥塞控制问题现状,提出了一种的无线网络TCP流公平调度算法。采用快速的TCP流优先发送方法,既保证了各流吞吐率公平性,又解决了慢速的TCP占用信道时间过多的问题,实现了各流占用信道的时间公平性。通过网络仿真实验证明,新的公平调度算法比传统的算法在性能上有较大的改进,达到了提高网络整体效率的目的。     

THE SUFFICIENT AND NECESSARY CONDITION FOR A PLANAR TO BE HAMILTONIAN

This paper presents a sufficient and necessary condition for any planarembedding G(namely plane graph)of a planar graph to be Hamiltonian.If Gis Hamiltonian,a method that an adjacent edge subgraph method for finddingits Hamilton cycles are given.     

An asymmetric fault ride-through control strategy for PMSG wind turbine

In order to improve the asymmetric fault ride-through capability of PMSG wind turbine, a novel control method is proposed. This method can reduce the negative sequence current component in the grid side converter and eliminate the 2 nd order voltage fluctuation in the DC link capacitor voltage of the AC-DC-AC converter. The proposed control method employs the grid voltage feed forward to reduce the grid side negative sequence current component, while a novel power control concept, output power of generator tracking the grid side power, is applied to control the electro-magnetic power of the PMSG to eliminate the 2 nd order voltage ripple in the DC link. Simulation results for a 1 MW case study show that the control method can eliminate the grid side negative sequence current component and the 2 nd order voltage ripple in the DC link at the same time.     

关于Mapmaker/Exp遗传作图中标记分群和排序操作技术的讨论

Mapmaker/Exp (3.0)是国内外广泛使用的遗传连锁数据分析软件, 在分子标记数量大时(多于500个)往往出现所绘制连锁图谱图距偏大的现象。本文从标记分群和标记排序两个遗传作图环节分析原因并概括出以下两个实施要点：(1)标记分群不应强求同一LOD值, 对特殊的连锁群可试用不同LOD值; (2)在标记排序时, 一次order命令后用ripple命令反复梳理有时并不能获得最佳排列顺序, 而应多次使用order, 每次order后用ripple反复梳理, 经反复比较才能得出最佳排列顺序, 必要时还须结合人工调整。通过大豆遗传作图实例比较了软件推荐思路2的通常用法和作者建议的新用法所构建的遗传图谱及相应QTL定位的差异, 认为新用法具有更好的效果。     

An asymmetric fault ride-through control method forPMSG wind turbine based onsuper-capacitors

With the rapid increasing interaction between wind turbines and power systems, wind turbines have to have the fault ride-through (FRT) capability to ensure the safe operation of power grid. In order to improve the asymmetric FRT capability of permanent magnet synchronous generator (PMSG) wind turbine, a novel control FRT method based on super-capacitors is proposed. In this method, super-capacitors are connected to the DC bus of AC-DC-AC converter via a bi-directional DC-DC converter, and the power processed by the super-capacitors is controlled to limit the increasing of the DC bus voltage of the AC-DC-AC converter in grid failure condition, and to reduce the 2nd order voltage ripple in the DC bus. Meanwhile, the proposed control method employs the grid voltage feed-forward approach to reduce the negative sequence current component in the grid side converter. According to the low voltage ride through (LVRT) standard, the selection of the super-capacitor capacity is also discussed, and then a mathematical model of the super-capacitor with the bi-directional DC-DC converter is established for designing the controller. Simulation results for a 1MW PMSG wind turbine by MATLAB show that the proposed control method reduces both the negative sequence current component in grid side converter and the 2nd order voltage ripple in DC link at the same time. The results also demonstrate that the asymmetric FRT capability of PMSG wind turbine is improved, which verifies the effectiveness of the proposed control method in this paper.     

On-demand routing algorithm based on load balancing and mobility prediction in wireless mobile Ad hoc network

The traditional routing protocol for wireless mobile ad hoc networks is unable to achieve balanced energy consumption and could not adapt to the dynamic topology changes well.A novel on-demand rooting algorithm is proposed based on load balancing and mobility prediction.The proposed rooting algorithm excludes the unstable links in routing discovery,and allows the node with more energy forward the routing request packet preferentially.In addition,it adopts the active local routing recovery strategy by predicting the link connection time,and finishes the repair work before the link being actually failure.The simulation experiments demonstrate that,comparing with the traditional AODV protocol,with slight increase of the rooting control overhead,the proposed algorithm increases the average packet delivery ratio,decreases the average end-to-end delay of the data packets,and achieves load balancing in the network and prolong the life-span of the network,which shows the proposed algorithm is highly practical.     

Restoration algorithm with wavelength reservation collision avoidance in ASON

Aiming at the problem of link fault restoration in ASON, an improved equalizing routing algorithm (ERA) is introduced to proportion the load at the routing phase. In order to solve the easy blocking problem for the network without wavelength converter because of the wavelength continuity constraint, the algorithm WRCA is proposed at the wavelength assignment phase. This algorithm is realized by adding collision detection object (CDO) in the path message of the resource reservation protocol with traffic engineering extension (RSVP TE). Depending on the value of the CD flag, different wavelength selection strategies are applied at the destination node, and the blocks resulting from wavelength reservation collision are reduced. The simulation experiments compare four wavelength assignment algorithms with the same routing algorithm ERA. The results show that compared with the traditional first fit algorithm (FF) and random fit algorithm (RD), the FF and RD employing CD scheme can effectively reduce the blocking ratio of the whole network, and enhance the practical applicability of the restoration algorithms.     

Petri网逆网在主轴故障诊断中的应用

比较了成熟期27个梨品种的果胶含量、半乳糖醛酸含量、果肉硬度和可溶性固形物含量,并分析果胶含量与果实品质特性的相关性。结果表明,不同梨品种间的果肉硬度、可溶性固形物、果胶、半乳糖醛酸含量4个指标的差异性都达到极显著水平(P0.01),果肉硬度均值为2.76 kg·cm-2,F值为47.03;半乳糖醛酸含量为0.64%~1.73%,F值为89.24,品种间差异最大;可溶性固形物含量为9.41%~15.19%,F值为17.66,品种间差异最小;果胶含量为0.23%~1.02%,与可溶性固形物和半乳糖醛酸含量呈极显著正相关(P0.01),Pearson相关系数分别为0.618和0.680。     

Analysis of Effect on Performance of Network Compensating Technique by Processing of Signals in Time Domain

The effect on performance of network compensating technique by identifying and processing of signals is studied.And the error function caused by processing signals in time domain is derived,the method that can reduce errors is also proposed.     

The Development of Intelligent Fault Diagnosis System Based KBE Graph

Aimed at solving the insufficiency problem in the current intelligent fault diagnosis system, such as lack of development tools, inference oversimplification, and developed a kind of diagnosis system based on network and KBE graph. The system is simple and easy to establish, modify, expand and maintain and does not need further coding. In addition, it can significantly save time and reduce the chance of failure. The integration of expert rules, fuzzy logic and nerve network enables the system to adapt to those complicated systems which involve in multi-variable, multi-parameter, multi-object and multi-process. As an example, an on-line detection system for simulate-on rotor test bench has been established and typical faults were successfully diagnosed through it, which proved the validity and reliability of the system. Furthermore, the system has been declared national invention patent.     

Novel channel estimation algorithm for OFDM/TDM over fast fading channels

For the shortage of tracking ability against fast fading channel of the existing pilot structures and channel estimation algorithms in OFDM combined with time division multiplexing (OFDM/TDM) system, an improved channel estimation algorithm is proposed. The channel transfer functions are obtained by estimating the channel properties with two adjacent time domain multiplexing (TDM) pilot sequences, while the channel state information of the OFDM/TDM symbols is obtained with interpolation Combined with frequency domain equalization based on minimum mean square error (MMSE-FDE), the proposed algorithm can significantly compensate the path loss over fast fading channels. Simulation results show that, compared with the existing channel estimation algorithms, the proposed algorithm can achieve better performance, which is not only capable of dealing with slow fading channels, but also has a better tracking ability against fast fading channels with the same data transmission efficiency.     

谱聚类在给水管网分区优化中的应用

利用图划分技术和图论算法实现给水管网分区。根据给水管网分析,确定分区数量,建立权重邻接矩阵并计算图拉普拉斯矩阵及其特征向量,通过多路图划分对隐藏在特征向量中的聚类信息进行数据挖掘,采用遗传算法和K均值方法实现最佳节点聚类。利用PageRank和最短路径算法确定水表和阀门位置,最终实现给水管网优化分区。实际给水管网模型分区实例表明所提方法在给水管网分区的有效性。     

一种基于距离和角度的无线传感器网络GPSR协议

传感器节点能量是影响无线传感器网络的生存周期的关键因素,基本的GPSR协议所使用的贪婪算法忽略了角度因素对下一跳选择的影响,在转发失败遇到空洞问题时只能进行周边边界转发算法,以损耗节点能量为代价。为了节约节点能量,延长网络生存周期,从改进GPSR协议出发,综合考虑距离和角度这两个因素解决路由过程中的空洞问题。仿真实验表明,改进后的协议是网络节点消耗大大减少,网络生存时间为300 s,长于基本GPSR协议下的200 s。该协议缩短了路径长度,节约节点能量,减少能量的消耗,延长了网络生存时间。     

Upstream Transmission Way in a HFC Network

In the HFC network, the funnelling effect of noise is the main restrict matter of raising the rate in the up stream channel. The requirements for the wide band services in a up stream channel are fist studied, and used as the criteria to compare the transfer ways each other used in up stream channel. Then, the ways in DOCSIS are analyzed, which were used to resist the noise, and the effect is showed by an example. The raised ability of resisting noise in the CDMA is obtained by reducing the transfer rate. Although it has a little better performance in resisting noise, but the rate is low and can not meet the requirements of wide band services. A kind of network structure is given, in which the users are connected in serial way, the noise funnelling is eliminated and have a high rate in the up stream channel. It is suitable for the wide band services, but the technology realizing the network structure needs perfecting.     

Pathway Analysis of the Mountainous Characteristic Road Network for Emergency Evacuation

According to conditions of landform in mountain area and features of mountainous road network, a concept of mountainous characteristic I Shaped road network was presented. By adopting time cost analysis method, finite impact ranges of key pathway and its adjoining pathway surrounding road networks were defined. Using graph theory and fluid network theory, the analysis of pathways to mountainous characteristic I Shaped road network was carried out. With the ways of virtual node and virtual branch, pathway algorithm of mountainous characteristic I Shaped road network was provided. The calculated process of the analysis of pathways to mountainous characteristic I Shaped road network was illustrated through numerical example, which shows that it provides guidance for determining an optimal route to evacuation and evacuation management in the calamity events.     

Application of improved genetic algorithm to locating and sizing of distributed generation

A Prüfer-coded genetic algorithm based on the decimal number of nodes is proposed and it is used to solve collaborative optimization planning of access solution of distributed generation(DG)and structure of distribution network.Using graph theory to generate theoretically feasible topology structureand the access nodes and the installed capacity of distributed generation are coded by the Prüfer number.The coding method makes the distribution network operation structure and the access solution of DG combine into the evolution problem of the same chromosomal gene.The length of the chromosome coding of this method is shorter than binary encoding.This solution takes full advantage of the Prüfer-coded to improve computational efficiency and convergence rateand makes some restrictions and improvements in some key parts of the algorithm to solve the problem illegal solution.Finallyfeasibility and superiority of the algorithm is validated by a case study.