Membrane Computing and Brane Calculi (Some Personal Notes)

This is a very short discussion of similarities and dissimilarities between membrane computing and brane calculi, insisting mainly on some recent ideas of bridging the two areas of research (from this last point of view, the bibliography tries to be as complete as possible) and proving that, in fact, there is no real dissimilarity...     

Tissue P systems with cell separation: attacking the partition problem

Tissue P systems are distributed parallel and non-deterministic computing models in the framework of membrane computing, which are inspired by intercellular communication and cooperation between neurons. Recently, cell separation is introduced into tissue P systems, which enables systems to generate an exponential workspace in a polynomial time. In this work, the computational power of tissue P systems with cell separation is investigated. Specifically, a uniform family of tissue P systems with ce...     

基于对等模型的分布式协同设计系统

为了解决分布式协同设计系统中的信息快速检索以及多副本同步等问题,引入了对等模型,给出了该系统的功能模型、信息检索模型等。提出了DHT的对等信息检索方法,保证了用户能够在分布式协同设计系统中快速共享资源。采用基于DHT的分布式互斥等算法作为协同数据的一致性维护方法,给出了系统的具体实现方法和实例。     

基于JXTA技术的P2P应用系统的研究与开发

本文首先简单的介绍了新一代分布计算模型——P2P的流行以及P2P系统的主要应用类型,然后重点阐述了JXTA技术的体系结构、核心协议以及在开发P2P应用系统时的优势所在,最后利用JXTA的Java实现版本设计和开发了一个简单的P2P远程学习系统。     

P2P文件共享系统行为特性模型分析

由于P2P文件共享系统具有自组织的特点,其行为特性很大程度上影响了系统可靠性和性能。为了解这种性质,利用统计方法研究了Maze系统用户行为特性分布模型及特点。结论表明,用户上传流量和下载流量、上传带宽和下载带宽可以使用对数正态混合分布来描述,活跃时间和传输时间可以使用对数正态分布来拟合,而请求次数和被请求次数可以使用指数分布和Pareto分布的混合分布来表达。     

基于P2P的即时通信系统的设计与实现

该文基于对等网络(P2P)设计了一种即时通信系统,该系统采用基于中心服务器的中心化拓扑结构,利用SOCKET编程实现。与传统的C/S模式相比,该模式大大弱化了服务器的作用,服务器只是为维护用户列表,用户之间的通信完全是点对点的,不需要经过服务器中转,从而能够承载更多的用户,大大提高了网络效率。     

对等网络Chord分布式查找服务的研究

在大规模Internet网络的应用中,查找服务是对等网络系统所面临的核心问题。Chord提供了一种高效和稳定的查找服务,Chord的可扩展性特点适用于大规模对等网络系统。在节点退出或加入时,Chord提供了高效稳定的机制。基于Chord的文件共享系统(SFS)是一个用于对等网络的只读存贮系统,它可以提供高效率的、鲁棒的和负载平衡的文件存取功能。SFS采用了完全分布式体系结构(没有服务器),很容易地扩展到大规模网络。SFS核心分为二层：DHT层和Chord层,使用Chord算法来定位查找服务。     

基于幂律分布和小世界特性的无结构P2P网络中搜索方法研究

目前无结构P2P系统得到了大量的应用,但其常用的基于简单flooding机制的信息资源搜索方法造成了严重的通信消耗.基于P2P网络的幂律分布和小世界特性,通过对复杂网络幂律特性产生机制的分析并借鉴人际传播中谣言传播机制,提出了一种结合择优连接机制和谣言传播中兴趣衰减机制的信息资源搜索方法.其中择优连接是导致复杂网络幂律特性产生的机制之一,而谣言传播中的兴趣衰减机制适合于聚合网络中的信息传播.分析和仿真结果表明,提出的搜索方法可以有效地减少无结构P2P网络中信息搜索的通信开销.     

基于P2P网络的匿名通讯技术的研究与实现

P2P网络的应用给匿名通讯系统带来了可扩展性等优点,但同时P2P网络中节点的动态上下线又使得匿名通道缺乏稳定性.设计并实现了一种基于非结构化P2P网络的匿名通讯系统,称之为LeafageMix.与传统基于Mix网络的匿名通讯系统不同,该系统采用中继组的方式来建立匿名通道,使得匿名通道具有较强的抵抗节点失效能力,并提高了匿名通讯系统的实用性.     

基于交易特征和反馈评价的P2P信任模型

提出了一种新的在P2P系统中基于交易特征和反馈评价的信任评估机制。为确定反馈评价的真实性,模型引入了时间衰减函数和事务影响参数,给出了反馈评价的可信度计算方法。实验仿真结果表明,该评估机制能够提高局部声誉和全局声誉的计算准确性,有效地抑制恶意节点。与信任模型PeerTrust和EigenTrust相比,该模型的性能优于其他两者,能够更好地应用于P2P电子商务系统中。     

基于JXTA的P2P网络答疑系统的设计与实现

JXTA技术主要用于提供P2P程序所需的基础服务.它致力于为P2P应用创建一个通用的平台,其中包括一系列独立于语言、平台和网络传输技术之外的协议.本文以Internet上基于P2P计算模式的网络答疑系统为研究对象,以JXTA平台为基础,讨论分析了其设计、实现的相关问题与技术.并对利用P2P计算模式来构建网络答疑系统的关键技术进行了研究.     

An efficient time-free solution to SAT problem by P systems with proteins on membranes

P systems with proteins on membranes are a class of bio-inspired computing models, where the execution of each rule completes in exactly one time unit. However, in living cells, the execution time of biochemical reactions is difficult to know precisely because of various uncontrollable factors. In this work, we present a time-free uniform solution to SAT problem by P systems with proteins on membranes in the sense that the correctness of the solution is irrelevant to the times associated with the involved rules, and the P systems are constructed from the sizes of instances.     

Secure seamless peer-to-peer (P2P) UDP communication using IPv4 LSRR option and IPv4+4 addresses

The current structure of the Internet, with hosts behind network address translation (NAT) boxes, causes well-known problems for P2P applications. There are several proposals, e.g., STUN, UPnP, MIDCOM, TURN among others, to enable P2P UDP communication for nodes behind NAT boxes, but each technique offers a partial solution that works in special limited cases and fails in others. In this paper, we present a framework based on the use of IPv4+4 addresses and the standard IPv4 Loose Source Record Route (LSRR) option that offers a complete solution to the secure seamless P2P UDP communication problem. Our proposal requires no changes whatsoever to end-host protocol stacks and Internet routers. The only requirement is a simple upgrade of border routers with a new LSRR-based packet forwarding algorithm for the P2P UDP traffic. We detail our implementation of a Linux-based border router that runs the proposed forwarding algorithm, and describe how applications requiring P2P UDP communication such as Voice over IP (VoIP) using SIP can benefit from our framework.     

Spiking neural P systems with neuron division and budding

Spiking neural P systems are a class of distributed and parallel computing models inspired by spiking neurons.In this work,the features of neuron division and neuron budding are introduced into the framework of spiking neural P systems,which are processes inspired by neural stem cell division. With neuron division and neuron budding,a spiking neural P system can generate exponential work space in polynomial time as the case for P systems with active membranes.In this way,spiking neural P systems can efficie...     

基于IPv6的P2P组播应用的研究与实现

介绍IPv6组播和P2P多播技术,分析FreePastry的路由算法,重点改进对象EpochInetSocketAddress对源路由节点地址的管理方法,在FedoraCore6系统环境下双栈技术的运用,以及在IPv6环境下设计并实现了基于P2P的组播应用。MTAP6由P2P重叠网和接入网两个部分组成,其中重叠网部分采用基于P2P的应用层组播技术,接入网部分采用基于IPv6的组播技术。最终实现了以视频会议、视频点播、远程教育为特色的新型多媒体组播应用     

Preparation of PCLT/P(VDF-TrFE) pyroelectric sensor based on plastic film substrate

Nanosized lead titanate doped with calcium and lanthanum (PCLT) powder obtained by the sol–gel method was homogeneously mixed with vinylidene fluoride-trifluoroethylene [P(VDF-TrFE)]. The nanocomposite PCLT/P(VDF-TrFE) film was used as the sensing film for pyroelectric sensors, whose detective merit was about 22.4% higher than that of sensors using pure P(VDF-TrFE). A 35 nm ITO film was deposited as the bottom electrode on PET plastic film substrate, on which PCLT/P(VDF-TrFE) was prepared by spin-coating, and Ni–Cr film was chosen as the upper electrode. The PET plastic film substrate could effectively decrease the thermal conductivity of the element and the ITO bottom electrode could reflect the infrared irradiation. The voltage responsivity was increased and the thermal fluctuation noise of the pyroelectric element was decreased significantly. The experimental results indicated that the specific detectivity of PCLT/P(VDF-TrFE) pyroelectric sensors based on PET film substrate reached 3.4E7 cm Hz^1/2 W⁻¹, more than two orders of magnitude higher than that of the sensors on bulk silicon substrate formed under the same conditions.     

一类分数阶(超)混沌系统异结构同步及仿真

针对一类分数阶(超)混沌系统的异结构同步问题,根据分数阶动力系统稳定性理论,结合反馈控制和主动控制方法提出了一种新的分数阶(超)混沌系统异结构同步方法。方法不仅不需要计算复杂的条件Lyapunov指数,而且保留了响应系统的非线性项。在数值研究过程中,可直接用时域进行数值计算,而不必进行时域与复频域转换。仿真结果表明:所设计的控制策略简单、易于实现,而且没有强加在系统上的限制条件,因此应用范围较宽。理论分析及仿真结果证明该方法的有效性。     

基于IMPULSE C的GF(P)域椭圆加密算法的硬件加速

研究了大素数域上的椭圆曲线加密算法,基于IMPULSE C语言,对该算法进行编程实现;在标准射影坐标系下,对点加和倍加算法进行并行化改进,并且在编程时利用编译器特性做了进一步的并行化。通过对加密算法合理的软硬件分割,将计算量大而且复杂的点乘运算作为硬件部分,通过现场可编程门陈列(FPGA)进行硬件加速;将加密协议的其他部分作为软件部分,在传统CPU上执行,并将硬件部分生成VHDL代码。分别进行加密算法的CoDeveloper的桌面仿真和生成的硬件VHDL代码的ISE综合仿真。最后将该加速设计在Xilinx Virtex-5 xc5vfx70t FPGA开发板上作了实现,基于FPGA的实验结果表明,P-192上点乘运算处理在133MHz时钟下用时2.9 ms,硬件资源分配合理,与现有的手工编写的HDL代码相比,具有并行加速优势。     

基于ANN的动态系统状态方程辨识建模仿真

对系统辨识原理、基于神经网络（ANN）的动态系统辨识进行了分析,针对动态系统辨识模型描述的复杂性,为简化ANN辨识建模的输入／输出关系的表达,提高算法的简洁性,采用了状态方程辨识模型,并给出了基于ANN的动态系统状态方程辨识模型。为比较分析不同网络结构的辨识建模效果及网络模型泛化能力,针对三种不同网络结构方案进行了辨识建模仿真研究。仿真结果最示,基于ANN的动态系统状态方程模型的辨识建模是有效的,并且简单合理的网络结构方案,可提高网络辨识模型的泛化能力。     

Spectral (Finite) Volume Method for Conservation Laws on Unstructured Grids III: One Dimensional Systems and Partition Optimization

In this paper, the third in a series, the Spectral Volume (SV) method is extended to one-dimensional systems—the quasi-1D Euler equations. In addition, several new partitions are identified which optimize a certain form of the Lebesgue constant, and the performance of these partitions is assessed with the linear wave equation. A major focus of this paper is to verify that the SV method is capable of achieving high-order accuracy for hyperbolic systems of conservation laws. Both steady state and time accurate problems are used to demonstrate the overall capability of the SV method.