输电线路在线监测WSNs优化部署研究

应用于输电线路在线监测的无线传感器网络(WSNs)通常呈长链型,存在跳数多、时延大的问题。引入具备无线公网通信模块的异构节点能够优化WSNs时延性能。考虑网络中传感器节点分布不均匀引起的数据分布不均匀这一普遍现象及其对时延的影响,建立了异构WSNs的最大时延模型;同时考虑网段划分和异构节点部署对时延的影响,提出了一种基于局部搜索思想的网络优化部署方法来优化网络时延。仿真结果表明:上述方法能有效降低网络最大时延,提高网络实时性。     

基于分布对象的同步回调模型的研究与实现

分布对象技术是分布异构环境下软件开发和系统集成的良好解决方案,然而在高性能分布计算领域,传统调用模型在异步特性方面的不足限制了分布对象技术在该领域的应用。因此,本文介绍一种新的基于分布对象的异步回调模型。测试表明,该模型能够有效改善分布对象系统的性能。     

Dual-Object: 面向对象的并行程序设计

面向对象的并行程序设计提供了类似于共享内存模型对通讯和计算的抽象能力，从而非常适合于大型并行软件系统的开发．但是基于远程对象调用的分布式对象的实现效率一直是面向对象方法在分布式／并行程序设计中得到广泛应用的障碍．本文介绍了并行机ＭＡＮＮＡ上所采用的面向对象的并行程序设计模型——Ｄｕａｌ－Ｏｂｊｅｃｔ模型．该模型通过引入从语义角度出发给出的数据一致特性的描述，在一定程度上解决了实现效率低下的问题．其次，文章通过程序设计实例详细地讨论了基于Ｄｕａｌ－Ｏｂｊｅｃｔ模型的扩展Ｃ＋＋并行程序设计，并给出了部分实际测试结果．     

Solution of parallel computation problem based on “space-time” concept

Construction of distributed systems by way of composition of program objects is considered. It is proposed to define topology of links between the objects by describing a ??neighborhood?? of each object in the form of a list of ??formal neighbors.?? Synchronization of evolution of the object and its neighbors is described in terms of ??local time?? of the object and its neighborhood. Results of solution of real problems on a supercomputer are presented. They demonstrate that it is possible to the reduce labor input required for the creation of distributed software systems to that of local programming.     

DOST: a distributed object segmentation tool

This paper presents a novel distributed object segmentation framework that allows one to extract potentially large coherent objects from digital images. The proposed approach requires minimum user supervision and permits to segment the objects accurately. It works in three steps starting with the user input in form of few mouse clicks on the target object. First, based on user input, the statistical characteristics of the target distributed object are modeled with Gaussian mixture model. This model serves as the primary segmentation of the object. In the second step, the segmentation result is refined by performing connected component analysis to reduce false positives. In the final step the resulting segmentation map is dilated to select the neighboring pixels that are potentially incorrectly classified; this allows us to recast the segmentation as a graph partitioning problem that can be solved using the well-known graph cut technique. Extensive experiments have been carried out on heterogeneous images to test the accuracy of the proposed method for the segmentation of various types of distributed objects. Examples of application of proposed technique in remote sensing to segment roads and rivers from aerial images are also presented. The visual and objective evaluation and comparison with the existing techniques show that the proposed tool can deliver optimal performance when applied to tough object segmentation tasks.

     

Petri net-based analysis on object assignment in distributed object-oriented systems

Object-oriented programming ^[9], which treats objects as processes in execution, has shown significant effectiveness in distributed systems. This effectiveness is greatly influenced by how objects are assigned to nodes. In this paper, we present a colored generalized stochastic Petri net (CGSPN) model to analyze the behavior of object invocations when an assignment strategy is applied. The effectiveness of an object assignment is also analyzed by our CGSPN model. Moreover, this analysis provides guidelines to develop an efficient object assignment strategy. ^[4–8]     

一种面向边缘环境的多实例服务链在线部署算法

边缘设备的资源有限性促使部署边缘服务需要深入理解网络功能的资源消耗情况.通过无线路由器上容器化网络功能部署实验得出,除了处理业务流的计算开销外,网络功能实例间的通信也会消耗大量CPU资源.基于该发现,考虑在近距离和相对低负载的对等边缘设备上分布式地部署网络功能实例,在满足时延约束的条件下均衡流量,从而最小化边缘设备负载...     

一种基于物体的视觉注意计算模型

为解决基于空间的视觉注意计算模型存在的注意目标不完整、容易转移到无意义区域等问题,提出一种结合空间显著性的基于物体的视觉注意计算模型。检测图像的边缘信息,根据空间视觉显著性度量结果,提取显著值高的封闭边缘,得到感知物体的轮廓。根据各感知物体的大小、位置和显著程度计算其注意度。注意焦点按照注意度递减的顺序在各感知物体之间进行转移。在多幅自然图像上进行实验验证,实验结果表明该模型具有和人类视觉特性相符合的注意效果。     

基于模板匹配及区域信息融合提取的快速目标跟踪算法

提出了一种基于融合的快速目标跟踪算法。该方法将目标预测模型、目标模板匹配以及目标空间信息融合到统一框架内。该方法通过预测模型,预测下一帧中目标候选区域,从而降低模板匹配方法的搜索区域。然后在预测模型预测的搜索范围内进行目标的模板匹配,同时,提取目标的区域信息来辅助目标的模板跟踪方法。最终跟踪结果由目标模板跟踪以及目标的空间信息共同决定。本方法由于采用了目标的预测模型,从而能够减少目标的搜索范围,降低因目标的全图搜索造成的时间开销。并且由于减少了搜索区域,剔除了部分相似的匹配窗口,从而提高了跟踪时匹配的精度。本算法结合了目标模板跟踪和目标区域信息的优点,能够增强目标跟踪过程准确度。由于加入了目标的区域信息,对目标跟踪中出现的漂移现象更加鲁棒。实验结果表明,本方法在进行目标跟踪过程中对出现的漂移、遮挡等问题更加鲁棒、稳定。     

A distributed hierarchical genetic algorithm for efficient optimization and pattern matching

In this paper we propose a new approach in genetic algorithm called distributed hierarchical genetic algorithm (DHGA) for optimization and pattern matching. It is eventually a hybrid technique combining the advantages of both distributed and hierarchical processes in exploring the search space. The search is initially distributed over the space and then in each subspace the algorithm works in a hierarchical way. The entire space is essentially partitioned into a number of subspaces depending on the dimensionality of the space. This is done in order to spread the search process more evenly over the whole space. In each subspace the genetic algorithm is employed for searching and the search process advances from one hypercube to a neighboring hypercube hierarchically depending on the convergence status of the population and the solution obtained so far. The dimension of the hypercube and the resolution of the search space are altered with iterations. Thus the search process passes through variable resolution (coarse-to-fine) search space. Both analytical and empirical studies have been carried out to evaluate the performance between DHGA and distributed conventional GA (DCGA) for different function optimization problems. Further, the performance of the algorithms is demonstrated on problems like pattern matching and object matching with edge map.     

A scalable P2P platform for the knowledge grid

The knowledge grid needs to operate with a scalable platform to provide large-scale intelligent services. A key function of such a platform is to efficiently support various complex queries in a dynamic large-scale network environment. This paper proposes a platform to support index-based path queries by incorporating a semantic overlay with an underlying structured P2P network that provides object location and management services. Various distributed indexing structures can be dynamically formed by publishing, semantic objects as indexing nodes. Queries are forwarded along the chains of semantic object pointers to search for objects. We investigate the deployment of a scalable distributed trie index for broadcast queries on key strings, propose a decentralized load balancing method for solving the problem of uneven load distribution incurred by heterogeneity of loads and node capacities and by the distributed trie index, and give an approach for improving the availability of the semantic overlay and its trie index. Experiments demonstrate the scalability of the proposed platform.     

P2P网络中一种基于进化博弈的资源配置模型

合理的资源配置能够有效地改进非结构化P2P网络的查询性能,提高资源副本的可获得性.当前,资源配置研究多集中在各种类型资源副本的定量分析和分布式配置策略上,节点独立地选择资源副本进行配置,并未考虑节点间配置行为的交互作用.P2P网络中节点只维护若干与邻居节点的连接,掌握局部信息,因而在交互过程中可将节点视为有限理性节点.在分析查询性能与节点资源配置行为之间关系的基础上,构造查询性能相关的节点收益函数,将资源配置问题模型化为一种进化博弈,通过对进化过程的描述能够有效分析节点在资源配置过程中的交互关系以及可获得的查询性能.仿真实验结果表明,资源配置进化模型可获得更高的查询成功率和近似最优的平均查询跳数,且保持相对较低的冗余度.     

Distributed model predictive control for plant-wide hot-rolled strip laminar cooling process

Since hot-rolled strip laminar cooling (HSLC) process is a large-scale, nonlinear system, a distributed model predictive control (DMPC) framework is proposed for computational reason and enhancing the precision and flexibility of control system. The overall system is divided into several interconnected subsystems and each subsystem is controlled by local model predictive control (MPC). These local MPCs cooperate with its neighbours through the scheme of neighbourhood optimization for the improvement of global performance. The state space representation of each subsystem’s prediction model is designed by finite volume method firstly, and then is linearized around the current operating point at each step to overcome the computational obstacle of nonlinear model. Moreover, since the strip temperature is measurable only at a few positions in water cooling section due to the difficult ambient conditions, an Extended Kalman Filter (EKF) is used to estimate the transient temperature of strip. Both simulation and experiment results prove the efficiency of the proposed method.     

面向MapReduce计算的大规模集群通信优化

为了优化大规模集群运行MapReduce作业时的通信效率和减少shuffle数据传输量,首先采用存储局部性换取通信局部性的策略建立一个分布式协同数据映射模型;其次通过随机抽样和机器学习方法来提取作业数据的局部性特征,实现map计算数据的有效部署;最后,利用软件定义网络的全局灵活控制能力,优选通信链路好的节点并将计算任务映射到该类节点中。实验表明对于中间数据混洗密集类作业有较好的优化效果,通信延迟降低了4.3%~5.8%。该方案能减少shuffle流量和数据迁移延迟,并且适合各种调度策略和网络拓扑结构。     

网络RAID存储系统边界性能研究

目前针对网络存储系统性能的研究大都集中在定性研究方面,缺乏有效的定量分析方法和模型．在有限容量闭合排队网络理论的基础上,提出了网络RAID存储系统性能的定量分析模型．并提出了一种新的计算有限容量闭合排队网络系统边界性能的分析方法-APBA法,和其他近似分析方法相比,APBA法的计算时间复杂度更低．测试结果表明,通过利用APBA方法,由网络RAID存储系统的性能定量分析模型获得的系统性能值,可以有效反映网络RAID存储系统在轻载区、重载区和过载区的性能边界,以及系统的最大负载量．     

Open Signaling for ATM Networks: A Vexed Question of Performance

Based on a clear separation between switching hardware and control software, the concept of open signaling creates an open programmable networking environment in which network entities can be realized as high level software objects with well-defined interfaces. This underlying architecture facilitates the creation of multiple mechanisms of network control, supporting applications for connection management. The feasibility of a connection management framework however depends mainly on the performance of CORBA because of binding overheads associated with remote invocations. It has been proposed that an implementation with reasonable performance may require certain criteria to be integrated into the design, including caching of network states, aggregation of access to the switch server object, and parallel processing of a single call request. This paper considers the effectiveness of these design criteria and the associated performance issues of a connection management system for ATM networks.     

A computational model of perceptual saliency for 3D objects in virtual environments

When giving directions to the location of an object, people typically use other attractive objects as reference, that is, reference objects. With the aim to select proper reference objects, useful for locating a target object within a virtual environment (VE), a computational model to identify perceptual saliency is presented. Based on the object’s features with the major stimulus for the human visual system, three basic features of a 3D object (i.e., color, size, and shape) are individually evaluated and then combined to get a degree of saliency for each 3D object in a virtual scenario. An experiment was conducted to evaluate the extent to which the proposed measure of saliency matches with the people’s subjective perception of saliency; the results showed a good performance of this computational model.     

基于时延优化的软件定义网络控制层部署策略

当前大多数软件定义网络（SDN）中控制器的部署方案均重点考虑正常网络状态下传播时延对性能的影响,而忽略了链路故障状态下对时延的影响,针对此问题,提出了一种基于时延优化的控制层部署方案。首先,在综合考虑网络正常运行以及单链路故障等多种网络状态下的最坏情况时延最小化问题的基础上,以网络状态时延作为新的时延优化目标并建立了相应的数学模型。其次,提出了解决上述模型的两种启发式部署算法：基于贪婪算法的控制层部署算法（GA-CPA）和基于粒子群优化（PSO）算法的控制层部署算法（PSO-CPA）。最后,选取了真实网络拓扑及数据进行验证。仿真结果表明,GA-CPA和PSO-CPA两种部署算法均能在不同程度上降低网络状态时延,从而保证了大部分网络状态下的最坏情况时延维持在较低范围。