基于负载的IEEE 802.11 AP切换研究

IEEE802．11规范包括MAC子层和物理层（PHY）两个协议层,支持结点的移动通信。很多切换机制的改进算法都以减少切换时间为目的,而随着无线传输的QoS要求和网络通信的速率不断提高,负载对AP切换的影响也日益显著。详细讨论了现有的基于负载的AP切换机制,并对各自的性能进行了分析比较,认为在高负载环境下,采用中心结构的切换机制会比基础结构的切换机制更具优势。     

利用蛋白质组学技术筛选与BIV基质蛋白MA相互作用蛋白

牛免疫缺陷病毒BIV的基质蛋白MA是由gag基因编码病毒结构蛋白之一,参与病毒运输包装等多种过程.通过蛋白质组学方法,寻找与MA有相互作用的宿主蛋白.通过原核表达MA-CBP融合蛋白,将其结合在几丁质上,并与细胞裂解物混合,纯化特异结合的细胞蛋白.利用双向电泳以及MALDI-TOF质谱分析,筛选到8个与MA具有相互作用的候选蛋白,功能涉及运输、氧化还原、热激反应等.进而克隆所鉴定蛋白之一的PRDX4,利用体外结合实验进一步证实其与BIV MA蛋白存在相互作用.初步建立利用蛋白质组学技术研究病毒与宿主相互作用实验方法,所得结果为了解慢病毒结构蛋白在病毒生活周期中功能提供了线索,有助于探索过氧化物酶家族蛋白在病毒感染过程中的作用及其分子机制.     

Attentional negativity bias moderated by positive mood arousal

Automatically allocation of more attention to negative stimuli is called emotional negativity bias. An event-related potentials (ERPs) experiment investigated whether or not this bias was altered by positive mood arousal. The results suggested that the attention bias towards negative stimuli was attenuated when positive information was accessible.     

水库调度PSO优化模型及求解方法

水库优化调度是水资源系统工程的一个典型,其实质是一个非线性的不等式约束优化问题,然而现行的求解方法中针对离散精度和复杂约束处理两个问题一直考虑不足,相关方面的研究也较少。将连续域寻优的粒子群算法引入到水资源系统工程中,建立水库调度的PSO优化模型,避免因离散而引起的寻优瓶颈,并针对传统粒子群算法的趋同性问题和复杂约束问题,提出退火罚函数法和混沌变异因子法,使改进后的粒子群能更有效地解决水库调度问题。通过实例分析,验证该方法的可靠性,为水库调度提供了一种新的求解途径。     

Non-fragile decentralized H∞ controller design for uncertain linear systems

Considering the design problem of non-fragile decentralized H∞ controller with gain variations, the dynamic feedback controller by measurement feedback for uncertain linear systems is constructed and studied. The parameter uncertainties are considered to be unknown but norm bounded. The design procedures are investigated in terms of positive definite solutions to modify algebraic Riccati inequalities. Using information exchange among local controllers, the designed non-fragile decentralized H∞ controllers guarantee that the uncertain closed-loop linear systems are stable and with H∞ -norm bound on disturbance attenuation. A sufficient condition that there are such non-fragile H∞ controllers is obtained by algebraic Riccati inequalities. The approaches to solve modified algebraic Riccati inequalities are carried out preliminarily. Finally, a numerical example to show the validity of the proposed approach is given.     

Research on secure buyer-seller watermarking protocol

A new buyer-seller watermarking protocol is proposed by applying a double encryption method and a novel mechanism of embedding a buyer＇s watermark. The protocol can effectively prevent against collusion attacks and the man in the middle attack if the third party is not trusted. Also, based on the proposed scheme for the first-hand transaction, a new buyer-reseller watermarking protocol and a formal multi-party watermarking protocol are also proposed. The proposed buyer-resell watermarking protocol only needs the original seller to provide transfer certificate and encryption-decryption service to support the second-hand transaction, and the multi-party watermarking protocol with distributed certificate authorities can overcome the difficulty in the combination of multicast mechanism with multiple unique watermarks and allow a seller to multicast the watermarked digital contents and key transaction information to n buyers. Furthermore, the idea of zero knowledge proof is also applied into the proposed scheme to allow the seller to take an effective control on the task performed by the third party.     

Cluster Synchronization in a Complex Dynamical Network with Two Nonidentical Clusters

This paper further investigates cluster synchronization in a complex dynamical network with two-cluster. Each cluster contains a number of identical dynamical systems, however, the subsystems composing the two clusters can be different, i.e., the individual dynamical system in one cluster can differ from that in the other cluster. Complete synchronization within each cluster is possible only if each node from one cluster receives the same input from nodes in other cluster. In this case, the stability condition of one-cluster synchronization is known to contain two terms： the first accounts for the contribution of the inner-cluster coupling structure while the second is simply an extra linear term, which can be deduced by the ＂same-input＂ condition. Applying the connection graph stability method, the authors obtain an upper bound of input strength for one cluster if the first account is known, by which the synchronizability of cluster can be scaled. For different clusters, there are different upper bound of input strength by virtue of different dynamics and the corresponding cluster structure. Moreover, two illustrative examples are presented and the numerical simulations coincide with the theoretical analysis.     

船舶破舱横摇数学模型及理论分析

船舶在航行过程中有可能发生船体破损以至船体进水的情况。因此,应该考虑船舶的抗沉性和应对措施,使船舶在一定程度损伤后仍具有足够的航行能力。在对船舶对称破舱的情况进行分析的基础上,采用槽型水舱理论建立了船舶破舱后横摇的数学模型,并对不同破舱水位和流动阻尼情况下的船舶横摇特性作了仿真和分析。最后根据船舶破舱数学模型,讨论并给出了船舶破舱情况下系统的绝对稳定条件。     

船舶航向与柴油主机联合LPV鲁棒控制及仿真

船舶航向与柴油机推进装置是紧密耦合的,但长期以来对它们的控制是完全独立的.根据线性变参数(LPV)系统设计原理,提出了基于LPV的船舶航向与主机联合控制.建立了以船速等为变参数的船舶航向与主机联合控制的LPV模型,采用LPV多胞设计方法,通过状态反馈对闭环极点进行配置,分别设计具有H∞鲁棒性能的航向与主机LPV控制器,实现二者的联合控制.以5446箱班轮为被控制对象,仿真验证了航向与主机LPV控制器在风浪干扰下联合控制的有效性.     

Investigation on full distribution CNC system based on SERCOS bus

A full distribution CNC system based on SERCOS bus is studied in accordance with the limitations of traditional PC-based motion card. The conventional PC-based motion control card is dispersed into several autonomous intelligent servo-control units with the function of servo driver. The autonomous intelligent servocontrol units realize the loop control of position, velocity and current. Interpolation computation is completed in PC and the computational results are transferred to every autonomous intelligent servo-control unit by high speed SERCOS bus. Software or hardware synchronization technology is used to ensure all servomotors are successive and synchronously running. The communication and synchronization technology of SERCOS are also researched and the autonomous intelligent servo-control card is developed byself. Finally, the experiment of circle contour process on a prototype system proves the feasibility.