An Isochronous Testing Strategy for Hierarchical Adaptive Distributed System-Level Diagnosis

Distributed System-level diagnosis allows the fault-free components of a fault-tolerant distributed system to determine which components of the system are faulty and which are fault-free. The time it takes for nodes running the algorithm to diagnose a new event is called the algorithm's latency. In this paper we present a new distributed system-level diagnosis algorithm which presents a latency of O(log N) testing rounds, for a system of N nodes. A previous hierarchical distributed system-level diagnosis algorithm, Hi-ADSD, presents a latency of O(log ² N) testing rounds. Nodes are grouped in progressively larger logical clusters for the purpose of testing. The algorithm employs an isochronous testing strategy that forces all fault-free nodes to execute tests on clusters of the same size each testing round. This strategy is based on two main principles: a tested node must test its tester in the same round; a node only accepts tests according to a lexical priority order. We present formal proofs that the algorithm's latency is at most 2log N – 1 testing rounds and that the testing strategy of the algorithm leads to the execution of isochronous tests. Simulation results are shown for systems of up to 64 nodes.     

一种分簇无线传感网络的节点自诊断算法

众多网络为了节省能量、减少链路都是在分簇拓扑结构中实现信息传输。当分簇网络出现故障时,首先要确保簇头节点的诊断精度。文中提出一种分簇网络的WSN节点自诊断算法,算法分为两步诊断来确定节点的最终状态:第一步主要根据相邻节点的信息相似来初步确定节点状态;第二步为了防止节点被诊断错误,对节点采取进一步检验诊断。仿真结果显示,所给出的两步诊断算法有较高的诊断准确率和诊断精度。     

Fault diagnosis in wireless sensor network using clonal selection principle and probabilistic neural network approach

The fault diagnosis in wireless sensor networks is one of the most important topics in the recent years of research work. The problem of fault diagnosis in wireless sensor network can be resembled with artificial immune system in many different ways. In this paper, a detection algorithm has been proposed to identify faulty sensor nodes using clonal selection principle of artificial immune system, and then the faults are classified into permanent, intermittent, and transient fault using the probabilistic neural network approach. After the actual fault status is detected, the faulty nodes are isolated in the isolation phase. The performance metrics such as detection accuracy, false alarm rate, false‐positive rate, fault classification accuracy, false classification rate, diagnosis latency, and energy consumption are used to evaluate the performance of the proposed algorithm. The simulation results show that the proposed algorithm gives superior results as compared with existing algorithms in terms of the performance metrics. The fault classification performance is measured by fault classification accuracy and false classification rate. It has also seen that the proposed algorithm provides less diagnosis latency and consumes less energy than that of the existing algorithms proposed by Mohapatra et al, Panda et al, and Elhadef et al for wireless sensor network.     

一种低时延的短波自组网优化链路状态路由协议

优化链路状态路由(Optimized Link State Routing,OLSR)协议是一种先验式路由协议,网络中的所有节点通过周期性地发送控制消息来计算全网路由信息。在短波自组织网络中,节点周期性地发送控制消息会占据大量的信道资源,大幅增加网络的控制开销,浪费短波有限的带宽资源,导致网络通信性能急剧下降。其次,受到地形地貌、天线方向和接收性能的个体差异等影响,造成无线链路不稳定,导致网络中存在非对称链路,增加了通信端到端时延。为此,提出了一种低时延的短波自组网OLSR协议。该协议在执行MPR(Multipoint Relay)选择算法时综合考虑了节点的连接度和链路可靠性,在优化MPR节点个数的同时选择链路可靠性较大的节点作为MPR节点,在进行路由选择时能够利用网络中的非对称链路。仿真结果表明,该协议能优化数据包投递成功率、吞吐量、端到端时延和网络控制开销等性能指标。     

XPS analysis with an ultra clean vacuum substrate carrier for oxidation and airborne molecular contamination prevention

Germanium wafer oxidation has been studied by angle resolved X-ray photoelectron spectroscopy (ARXPS). These analyses have been used for testing a new concept for substrate contamination prevention methods using an ultra clean vacuum substrate carrier for semiconductor manufacturing environments. Satisfying the International Technology Roadmap for Semiconductors (ITRS) under 65 nm nodes has introduced many assignments to future semiconductor manufacture such as haze problems in lithography masks, wafer oxidation growth in queue time, or contact with airborne molecular contaminations (AMC). From our experience, silicon and germanium wafers, after HF passivation and cleaning, were transported to XPS in order to measure various aspects of the oxidation progress; one case with normal ambient air exposure and another with vacuum carrier storage without ambient exposure. The results give information on the Ge oxidation kinetic, in term of speed and bounding environment. Moreover, the tests performed using the vacuum carrier are significant proof of the efficiency of germanium oxidation prevention. The methods have a large potential for solving critical problems and decontamination methods in the short term IT road map.     

星图的自适应诊断

自适应性诊断的目的,是正确辨别出结点的性质。没有公共点的两对结点可以在同一个诊断周中出现。文中构造了星图的一个递归的哈密尔顿自适应诊断方法。在出错结点数不超过n-1个的情况下,这种方法只需要个诊断周。在最好和最坏的情况下,它分别需要n!+(n-2)和(2n-1)(n-1)!次诊断。     

Modified ShuffleNet for Multihop All-Optical WDM Networks Employing Wavelength Reuse

A modified multihop ShuffleNet configuration for WDM all-optical networks is described which is rearrangeable and allows wavelength reuse at each node as it expands. This configuration does not require any rearrangement of preceding node and wavelength assignments when new nodes and wavelengths are added and it can function with fewer overall number of nodes. By comparison, the traditional Perfect ShuffleNet requires a large number of nodes to be available for any updating of the configuration. Most of these nodes remain idle during the normal signal routing process leading to reduced network link capacity. Furthermore, to facilitate wavelength reuse when updating, the Perfect ShuffleNet necessitates the rearrangement of preceding node and wavelength assignments. This leads to generalized forms of ShuffleNet where wavelength reuse forces network architecture into irregular topologies. The modified ShuffleNet proposed here is capable of facilitating wavelength reuse without the modification of initial node and wavelength assignments and could be realised by using a star topology.     

CT图像中肿大淋巴结肺癌转移分类方法

为解决肺癌N分期中胸部CT难于对肿大淋巴结是否癌转移进行评价的问题,寻求能够有效表示淋巴结病理特性的图像特征,实现对肿大淋巴结癌转移快速准确地判别。该文采取交互式分割从CT图像中提取出肿大淋巴结;直接计算淋巴结的多分辨率直方图得到200维空间信息特征样本集;利用具有处理高维数据集优势的支持向量机(SVM)构造分类器;用测试集对经训练的SVM分类器进行测试以评价分类性能。经96例病例实验结果表明:100个淋巴结图像的200维特征计算用时1.91 s,SVM分类器训练测试用时1.36 s,敏感性76%,特异性64%,准确度70%,接受者操作特性曲线(ROC)下面积(AUC)0.6525。高维图像空间信息特征能够有效表示淋巴结特性;没有考虑医学征象进行肿大淋巴结癌转移定性诊断的准确度就达到了70%,同时分类速度比传统纹理算法提高了约10倍。     

Multiple fault analog circuit testing by sensitivity analysis

Analog circuit testing is considered to be a very difficult task. This difficulty is mainly due to the lack of fault models and accessibility to internal nodes. To overcome this problem, an approach is presented for analog circuit modeling and testing. The circuit modeling is based on first-order sensitivity computation. The testability of the circuit is analyzed by the multiple-fault model and by functional testing. Component deviations are deduced by measuring a number of output parameters, and through sensitivity analysis and tolerance computation. Using this approach, adequate tests are identified for testing catastrophic and soft faults. Some experimental results are presented for simple models as well as multiple-fault models.     

Multiple fault analog circuit testing by sensitivity analysis

Analog circuit testing is considered to be a very difficult task. This difficulty is mainly due to the lack of fault models and accessibility to internal nodes. To overcome this problem, an approach is presented for analog circuit modeling and testing. The circuit modeling is based on first-order sensitivity computation. The testability of the circuit is analyzed by the multiple-fault model and by functional testing. Component deviations are deduced by measuring a number of output parameters, and through sensitivity analysis and tolerance computation. Using this approach, adequate tests are identified for testing catastrophic and soft faults. Some experimental results are presented for simple models as well as multiple-fault models.     

Improved Shuffled Frog-Leaping Algorithm Based QoS Constrained Multicast Routing for Vanets

Prompt and reliable communication between vehicular nodes are essential as its limited coverage and dynamic mobility rate introduces frequent change of network topology. The key feature of vehicular communication that establishes direct connectivity or Road Side Unit-based data transfer among vehicular nodes is responsible for sharing emergency information during critical situations. Multicast routing data dissemination among vehicular nodes is considered to be the potential method of parallel data transfer as they facilitate the option of determining an optimal multicast tree from feasible number of multicast trees established between the source and destinations. This estimation of optimal multicast tree using meta-heuristic techniques is confirmed to improve the throughput and reliability of the network when QoS-based constraints are imposed during multicast routing. An Improved Shuffled Frog-Leaping Algorithm-Based QoS Constrained Multicast Routing (ISFLABMR) is proposed for estimating an optimal multicast tree that confirms effective multi-constrained applied multicast routing between vehicular nodes. ISFLABMR minimizes the cost of transmission to 22% by reducing the number of multicast clusters formed during multicasting through the utilization of local and global-based optimizations. The simulation results of ISFLABMR proveits predominant reduction rate of 24% and 21% in average packet latency and energy consumptions incurred under multicast routing.     

Multicasting in a class of multicast-capable WDM networks

Multicast is the ability to transmit information from a single source node to multiple destination nodes. Multicast can be supported more efficiently in optical domain by utilizing the inherent light-splitting capacity of optical switches than by copying data in electronic domain. In this paper, we study multicast communication in a class of multicast-capable WDM networks (i.e., the networks that have light splitting switches) with regular topologies under some commonly used routing algorithms. Upper and lower bounds on the minimum number of wavelengths required are determined for a network to be rearrangeable for arbitrary multicast assignments, and compared with those WDM networks without light splitting switches. Our results indicate that in most of the networks we study, the number of wavelengths required can be significantly reduced by utilizing light splitting switches     

A Distributed Message-passing Approach for Clustering Cognitive Radio Networks

Forming collaborative wireless network clusters in dynamically changing environments is essential for cognitive radios to achieve such desired objectives as interference resilience and low communications overhead. In this paper, a novel approach to form efficient node clusters in an ad hoc cognitive radio network (CRN) is introduced based on the affinity propagation (AP) message-passing technique. With this approach, nodes exchange messages containing local network information with their direct neighbours until a high quality set of clusterheads and an efficient cluster structure emerges. The groupings are based on measures of similarity between the network nodes, which are selected based on application requirements. As an initial application, we show how the AP technique can be used to distributively determine cluster assignments and elect a small number of clusterheads that cover a CRN. Such an objective is commonly used to reduce communication overhead in key network functions such as resource management and routing table maintenance. To demonstrate the merits of the proposed approach, the clustering efficiency of the AP technique is evaluated on randomly generated open spectrum access scenarios. The simulation results demonstrate that the proposed approach provides a smaller number of clusters than a standard technique based on approximating the minimum dominating sets of the corresponding ad hoc network graphs.     

一个基于并行集团的系统级故障概率诊断算法

概率诊断算法是系统级故障诊断研究的一个重要方面,本文提出了一种基于并行集团的概率诊断算法-PGSFPD算法,并设计了一个系统级故障诊断软件仿真系统,对诊断算法进行仿真,分析比较各算法的性能,仿真结果表明PGSFPD算法性能优于经典的概率诊断算法-Somani & Agrawal算法,可在只需较少测试数的情况下,在保持很高诊断正确率的同时,大大降低系统的规模.     

Optimal memory management strategies for a mobile user in abroadcast data delivery system

Data broadcasting has been considered as a promising way of disseminating information to a massive number of users in a wireless communication environment. In a broadcast data delivery system, there is a server which is broadcasting data to a user community. Due to the lack of communication from the users to the server, the server cannot know what a user needs. In order to access a certain item, a user has to wait until the item appears in the broadcast. The waiting time will be considerably long if the server's broadcast schedule does not match the user's access needs. If a user has a local memory, it can alleviate its access latency by selectively prefetching the items from the broadcast and storing them in the memory. A good memory management strategy can substantially reduce the user's access latency, which is a major concern in a broadcast data delivery system. An optimal memory management policy is identified that minimizes the expected aggregate latency. We present optimal memory update strategies with limited look ahead as implementable approximations of the optimal policy. Some interesting special cases are given for which the limited look-ahead policies are optimal. We also show that the same formulation can be used to find the optimal memory management policy which minimizes the number of deadline misses when users generate information requests which have to be satisfied within some given deadlines     

Multilevel space–time trellis coded cooperation with channel state information at transmitter

In this paper, the authors propose a system where a number of cooperating mobile nodes transmit information to a common destination node. Each cooperating node has a set of decoders to detect the information of other nodes and a set of encoders to further encode the decoded information as well as its own information using multilevel space–time trellis coding (MLSTTC) scheme. The coded information is mapped using multi‐resolution modulation partitioning to M‐ary quadrature amplitude modulation constellation. The mapped symbols are weighted based on the available channel state information at transmitting nodes. The weighting of transmitting symbols provides beamforming resulting in receive signal‐to‐noise ratio gain. The weighted symbols are sent to destination node through two transmit antennas. If the information of other nodes has been correctly decoded at the cooperating node, then the destination node receives the information of each node as many times as there are number of transmitting nodes, thus achieving full diversity order. A multistage Viterbi decoder is used at the destination node to extract information of each mobile node. The results indicate that the performance of proposed cooperative MLSTTC system is superior to non‐cooperative MLSTTC system. Copyright © 2016 John Wiley & Sons, Ltd.     

Impact of number of angles on the performance of the data vortex optical interconnection network

Reducing communication latency in multiprocessor interconnection networks can increase system performance on a broad range of applications. The data vortex photonic network reduces message latency by utilizing all-optical end-to-end transparent links and deflection routing. Cylinders replace node storage for buffering messages. The cylinder circumference (measured as number of angles) has a significant impact on the message acceptance rate and average message latency. A new symmetric mode of usage for the data vortex is discussed in which a fraction of the angles is used for input/output (I/O), and the remainder is used for "virtual buffering" of messages. For single-angle injection, six total angles provide the best performance. Likewise, the same ratio of 5 : 1 purely routing nodes versus I/O nodes is shown to produce greater than 99% acceptance, under normal loading conditions for all other network sizes studied. It is shown that for a given network I/O size, a shorter height and wider circumference data vortex organization provides acceptable latency with fewer total nodes than a taller but narrower data vortex. The performance versus system cost is discussed and evaluated, and the 5 : 1 noninjection-to-injection angle ratio is shown to be cost effective when constructing a system in current optical technology.     

一种低复杂度的多元LDPC译码算法

针对多元低密度奇偶校验(LDPC)码译码复杂度高、时延大等问题,提出了一种基于硬信息的低复杂度多元LDPC译码算法.来自信道的接收信号在初始化时,先进行非均匀量化预处理.在迭代过程中,校验节点端只需传输单个比特的二进制硬可靠度信息至变量节点.在变量节点端,可靠度信息按比特位进行简单的累加和更新,无需任何的系数修正操作.同时,变量节点使用了全信息的方式将信息传输至与其相邻的校验节点.仿真结果显示,与基于比特可靠度(BRB)的多元LDPC译码算法相比,提出的算法在较低量化比特情况下,能获得约0.3 dB的译码性能增益,且译码复杂度更低.     

Sprinkler: A Reliable and Energy Efficient Data Dissemination Service for Extreme Scale Wireless Networks of Embedded Devices

We present Sprinkler, a reliable data dissemination service for wireless embedded devices which are constrained in energy, processing speed, and memory. Sprinkler embeds a virtual grid over the network whereby it can locally compute a connected dominating set of the devices to avoid redundant transmissions and a transmission schedule to avoid collisions. Sprinkler transmits O(1) times the optimum number of packets in O(1) of the optimum latency; its time complexity is O(1). Sprinkler is tolerant to fail-stop and state corruption faults. Thus, Sprinkler is suitable for resource-constrained wireless embedded devices. We evaluate the performance of Sprinkler in terms of the number of packet transmissions and the latency, both in an outdoor and indoor environment. The outdoor evaluation is based on data from project ExScal, which deployed 203 extreme scale stargazer (XSS). Our indoor evaluation is based on an implementation in the Kansei testbed, which houses 210 XSSs whose transmission power is controllable to even low ranges. We compare Sprinkler with the existing reliable data dissemination services, analytically or using simulations also. Our evaluations show that Sprinkler is not only energy efficient as compared to existing schemes, but also has less latency. Further, the energy consumption of nodes and the latency grows linearly as a function of newly added nodes as the network grows larger.     

Data aggregation in sensor networks using learning automata

One way to reduce energy consumption in wireless sensor networks is to reduce the number of packets being transmitted in the network. As sensor networks are usually deployed with a number of redundant nodes (to overcome the problem of node failures which is common in such networks), many nodes may have almost the same information which can be aggregated in intermediate nodes, and hence reduce the number of transmitted packets. Aggregation ratio is maximized if data packets of all nodes having almost the same information are aggregated together. For this to occur, each node should forward its packets along a path on which maximum number of nodes with almost the same information as the information of the sending node exist. In many real scenarios, such a path has not been remained the same for the overall network lifetime and is changed from time to time. These changes may result from changes occurred in the environment in which the sensor network resides and usually cannot be predicted beforehand. In this paper, a learning automata-based data aggregation method in sensor networks when the environment’s changes cannot be predicted beforehand will be proposed. In the proposed method, each node in the network is equipped with a learning automaton. These learning automata in the network collectively learn the path of aggregation with maximum aggregation ratio for each node for transmitting its packets toward the sink. To evaluate the performance of the proposed method computer simulations have been conducted and the results are compared with the results of three existing methods. The results have shown that the proposed method outperforms all these methods, especially when the environment is highly dynamic.