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Zhang X.,Beihang University | Zheng Z.,State Key Laboratory of Software Development Environment | Zheng Z.,Beihang University | Zhu Y.,Beihang University | Cai K.-Y.,Beihang University
Computers and Operations Research | Year: 2014

This paper focuses on the protection issues for supply systems involving random attacks, which are described as attacks whose targets cannot be predicted. We present the random-attack median fortification problem (RAMF) to identify the fortification strategy that minimizes the expected operation cost after random attacks. RAMF is formulated as an integer-linear program and solved directly using general-purpose MIP solver. Moreover, a more complex problem, the fortification median problem for disruptions caused by mixed types of attacks (FMMA), is introduced to find a balance between defending the worst-case attacks and random attacks. Solving FMMA can achieve good protection results, which are more practical in dealing with systems with mixed types of attacks, if the proportion between the types is properly estimated. We formulate FMMA as a non-linear bilevel program and extend a typical implicit enumeration (IE) algorithm to solve the problem. Finally, computational experiments demonstrate the effectiveness of both RAMF and FMMA in dealing with protective affairs involving random attacks. The efficiency of solving the formulations of RAMF and FMMA is also testified. © 2013 Elsevier Ltd. Source

Zhu Y.,State Key Laboratory of Software Development Environment | Zhu Y.,Shanghai JiaoTong University
International Journal of Distributed Sensor Networks | Year: 2012

Detecting abnormal events represents an important family of applications for wireless sensor networks. To achieve high performance of event detection, a sensor network should stay active most of the time, which is energy inefficient for battery driven sensor networks. This paper studies the fundamental problem of bounding detection delays when the sensor network is low duty cycled. We propose a novel approach for statistically bounding detection latency for event detection in sensor networks. The key issue is the wakeup scheduling of sensor nodes and minimization of wakeup activity. We propose a lightweight distributed algorithm for coordinating the wakeup scheduling of the sensor nodes. A distinctive feature of this algorithm is that it ensures that the detection delay of any event occurring anywhere in the sensing field is statistically bounded. In addition, the algorithm exposes a convenient interface for users to define the requirement on detection latency, thereby tuning the intrinsic tradeoff between energy efficiency and event detection performance. Extensive simulations have been conducted and results demonstrate that this algorithm can successfully meet delay bound and significantly reduce energy consumption. © 2012 Yanmin Zhu. Source

Wang L.,State Key Laboratory of Software Development Environment | Wang L.,Beihang University | Wang Y.,Beihang University | Zhao Y.,Beihang University
Physica A: Statistical Mechanics and its Applications | Year: 2014

Studying the function call graphs in complex software can provide significant insights into the software evolution process. We found node in- and out-degree distributions asymmetric in the call graphs of 223 versions of Linux kernel modules (V1.1.0 to V2.4.35). Nodes newly introduced in these modules tended to attach to themselves (clustering) and existing high in-degree nodes. We proposed the αβ Model to generate call graphs for different kernel modules. The model preserved asymmetry in the degree distributions and simulated the new node behaviors. Last, we discussed how the αβ Model could be used effectively to study the robustness of complex networks. © 2014 Elsevier B.V. All rights reserved. Source

Hong L.,Nanjing University of Posts and Telecommunications | Hong L.,State Key Laboratory of Software Development Environment
Jisuanji Xuebao/Chinese Journal of Computers | Year: 2013

Pearl indicated that uncertainty was a core problem faced by intelligent systems. And an existing modality is the basis of uncertainty. However, to the best of author's knowledge, there has not been any report on the research of the existing modality of uncertainty. This paper aims at founding a general theory framework and the corresponding measure method for processing uncertainty phenomenon. Two concepts are distinguished: uncertainty and uncertainty-ness; the unattached attribute of uncertainty is described with vector; Quine-space, one existing modality of uncertainty, is constructed. The attribute standard pointer is established, and two types of the measuring models of uncertainty-ness are proposed: unitary phase and binary phase. As the given demonstrations of measuring models, the measure of fuzziness and the measure of randomness are discussed with medium truth degree and modern probability respectively; fuzzy-randomness is too discussed. The results show that the method proposed in this paper possesses features of natural-ness and universality and quantitative form processed by computers. We attempt to make the measure-value of various uncertainty attributes normalization in order that they may compare with each other in uncertain degree. Source

Qu W.-W.,Beihang University | Zhang G.-L.,State Key Laboratory of Software Development Environment | Zhang G.-L.,Beihang University | Le X.-Y.,Beihang University
Wuli Xuebao/Acta Physica Sinica | Year: 2012

he relations of fusion barrier height and position to charge number and root-mean-square radus of the interacting nucleus for a projectile fusing with the different target nuclei are systematically analyzed in this paper. The nuclear potential is calculated by using the double folding model with the density-dependence nucleon-nucleon interaction (CDM3Y6). The pocket formulas are obtained for the fusion barrier height and position for a projectile fusing with the different nuclei with mass in a range from 16 to 238. The parameterized formulas can reproduce the exact barrier heights and positions only for a projectile within the accuracy of ±1%. Moreover, the results are perfectly agreeable with the experimental data, the empirical data and the results of Royer, KNS, AW and the proximity potential. © 2012 Chinese Physical Society. Source

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