网络垃圾信息ILDR传播模型

针对网络垃圾信息传播研究多采用定性分析方法,难以揭示垃圾信息内在传播规律的问题,基于病毒传播的建模思想,考虑不同输入率和移出率等现实因素,提出了垃圾信息的ILDR传播模型。首先,计算了平衡点和传播阈值,并给出了平衡点的稳定性条件。其次,利用Routh-Hurwitz准则证明了无垃圾信息和垃圾信息的局部稳定性,并采用LaSlle的不变性原理证明了无垃圾信息全局稳定性,根据Bendixson判据证明了垃圾信息的全局稳定性。理论研究表明:当传播阈值小于1时,无垃圾信息平衡点全局渐进稳定;当传播阈值大于1时,垃圾信息平衡点全局渐进稳定。根据数值模拟可知:减小潜伏者到传播者的转化率,增加无知者到移出者的转化率和潜伏者到移出者的转化率,可以减小传播阈值的值;减小无知者到潜伏者的比例系数,增加传播者到移出者的转化率和系统的移出率,可以使传播者的取值减小。     

基于常数输入的蠕虫传播模型及其分析

针对蠕虫病毒提出了易感主机有常数输入并具有标准传染率的SIRS传播模型,考虑蠕虫病毒在传播期间主机总数的动态变化性,应用微分方程定性与稳定性理论对该模型进行分析, 讨论了不同因素对蠕虫病毒控制的影响。并利用Abilene网络分析了网络拓扑对病毒传播速率的影响。最后,通过CAIDA提供的蠕虫数据对该模型进行了检验。     

基于两阶段免疫接种的SIRS计算机病毒传播模型

针对现有的带有免疫接种策略的病毒传播模型的不足,根据生物学中的传染病模型提出了带有阶段免疫接种特点的SIRS计算机病毒传播模型。该模型充分考虑了在达到感染阈值时免疫接种概率的变化对于病毒传播的影响。此外,利用动力学稳定性理论分析并证明了病毒平衡点的存在和稳定条件。数值仿真结果表明,提高免疫接种率和设定适当的感染阈值可以有效控制计算机病毒在网络中的传播。     

基于传播能力差异的IWSR垃圾信息传播模型

为研究用户传播能力差异性对垃圾信息传播的影响,根据仓室建模思想,将传播网络中的人群划分为I(ignorant),W(weakly spreader),S(strongly spreader),R(removal)四个仓室并提出状态转换规则,运用微分动力系统理论建立一个具有传播能力差异的IWSR垃圾信息传播模型。通过计算模型的基本再生数,利用Hurwitz判据、Lyapunov稳定性定理和LaSalle不变性原理,得出垃圾信息传播平衡点的局部稳定和全局稳定条件。最后通过数值仿真与新浪微博真实数据集的对比实验证明所得结论的合理、有效性。     

具常数移出率和阶段结构的SIR传染病模型

对一类具常数移出率和阶段结构传染病模型进行了分析,得到了传染病最终消除和成为地方病的阈值,当它小于1时,无病平衡点是全局渐近稳定的,此时疾病消除.当它大于1时,地方病平衡点是局部渐近稳定的,此时传染病成为地方病.     

带可移动存储设备的P2G网络病毒传播模型

基于计算机病毒可以通过可移动存储设备传播和P2G网络病毒传播的特点,提出了带可移动存储设备的P2G网络病毒传播模型。利用微分动力学系统理论分析发现该模型只存在唯一的有病毒平衡点,这意味着网络中的病毒将无法根除,即病毒既有可能存在于计算机中,也有可能存在于移动存储设备中。同时,研究了此平衡点的动力学特性（局部稳定性和全局稳定性）。最后,通过数值仿真验证了理论分析的正确性。     

对等网络中被动型蠕虫传播动力学建模与分析

鉴于被动型蠕虫对网络的安全构成了威胁，考虑网络异质性和一次搜索允许的跳数，提出一个带有补充率和移除率的新动力学模型，推导出决定被动型蠕虫能否传播的阈值--基本再生数，分析了无蠕虫平衡点和正平衡点的稳定性问题。最后通过数值模拟验证了理论的正确性，并对参数敏感性进行了分析。研究结果发现，当基本再生数大于1时，跳数的增加不但加快被动型蠕虫的传播，而且使感染节点的数量也增加；当基本再生数小于1时，跳数的增加使感染节点的数量迅速减少，最终被动型蠕虫灭绝。     

基于元胞自动机的网络蠕虫病毒传播仿真

针对模拟网络蠕虫病毒的传播,提出基于元胞自动机模型的网络蠕虫病毒传播的方法。将病毒的传播过程分为2个阶段,并分别对不同的阶段建模。经过仿真,可以获得不同状态的计算机系统的数量、蠕虫病毒的数量和病毒传播趋势等信息。结果表明,用元胞自动机模型仿真蠕虫病毒传播能够更清晰地反映出网络蠕虫病毒传播的趋势,与实际的蠕虫病毒传播符合较好。     

移动无线传感器网络中抑制病毒传播模型

为了更好地控制病毒在移动无线传感器网络中的传播,根据传染病学理论建立了改进的病毒传播的动力学模型。该模型不仅在网络中加入死亡节点,还增加了病毒节点在传播过程中的通信半径以及移动和停留两种状态。之后针对该模型建立微分方程组,并进行平衡点存在性和稳定性分析,得出病毒传播的控制和消亡条件,进而分析了节点通信半径、移动速度、密度、易感节点免疫率、感染节点病毒查杀率和节点死亡率等对移动无线传感器网络中病毒传播的影响。最后通过仿真实验表明,调整该模型中的参数可以有效地遏制病毒在移动无线传感器网络中的传播。     

移动自组网病毒传播模型及稳定性分析

考虑移动自组网中节点的移动特性,基于平均场理论提出移动自组网中病毒传播模型,并对建立的方程组进行平衡点存在性和稳定性分析,得出病毒传播的阈值及消亡条件,从而研究节点移动速度、通信半径、免疫成功率和免疫失效率对移动自组网中病毒传播行为和传播临界特性的影响。结果表明:当病毒基本再生数R0<1时,网络全局渐近稳定在无病毒平衡点;当R0>1时,网络全局渐近稳定在地方病平衡点。最后通过数值仿真验证了该模型的正确性。     

Norwegian Overnight Interbank Interest Rates

This article addresses the lack of reliable information about overnight interest rates in the Norwegian interbank market. We infer actual interest rates from interbank transactions recorded in the real-time gross settlement (RTGS) system of Norges Bank over the period October 2006–November 2010. We propose a new measure of overnight interest rates, NONIA, which may be calculated daily as a value-weighted average of overnight interest rates on individual loans. This may supplement information provided by indicative interest rates such as NIBOR. We also compute an indicator based on dispersion of interest rates across individual loans and the spread between NONIA and the key policy rate. The indicator may be useful for assessing whether overnight interest rates are close to Norges Bank’s key policy rate, consistent with its liquidity policy objective.     

Verification of Reduced Convergence Rates

In this short article, we recalculate the numerical example in Kíek and Neittaanmäki (1987) for the Poisson solution u=x(1–x)siny in the unit square S as . By the finite difference method, an error analysis for such a problem is given from our previous study by where h is the meshspacing of the uniform square grids used, and C₁ and C₂ are two positive constants. Let =u–u_h, where u_h is the finite difference solution, and is the discrete H¹ norm. Several techniques are employed to confirm the reduced rate of convergence, and to give the constants, C₁=0.09034 and C₂=0.002275 for a stripe domain. The better performance for arises from the fact that the constant C₁ is much large than C₂, and the h in computation is not small enough.     

Risk Processes with Random Interest Rates

The behavior of the capital value of a life insurance company with one type of policies and a random interest rate is investigated.     

Sharing Resources at Nonuniform Access Rates

We introduce DPPr (for ``Dining Philosophers Problem with rates') as a generalization of the heavy-load case of the Dining Philosophers Problem (DPP). In DPPr, processes are required to be scheduled to access shared resources with prespecified relative frequencies. DPPr is an abstraction of resource-sharing problems to which the synchronization of some distributed algorithms for neural-network models and the generation of timing signals in asynchronous digital circuits are related. Two fully distributed, synchronous solutions are given for DPPr in this paper. The first solution employs a reduction to heavy-load DPP and after that a distributed scheduling mechanism that has been used to solve this problem with optimal concurrency. The second solution tackles the DPPr instance directly by operating on a multigraph based on that instance. We conclude by indicating how the two synchronous solutions carry over to the asynchronous case. Received January 1998, and in final form May 5, 2000. Online publication October 13, 2000.     

Edge-Cut Bounds on Network Coding Rates

Active networks are network architectures with processors that are capable of executing code carried by the packets passing through them. A critical network management concern is the optimization of such networks and tight bounds on their performance serve as useful design benchmarks. A new bound on communication rates is developed that applies to network coding, which is a promising active network application that has processors transmit packets that are general functions, for example a bit-wise XOR, of selected received packets. The bound generalizes an edge-cut bound on routing rates by progressively removing edges from the network graph and checking whether certain strengthened d-separation conditions are satisfied. The bound improves on the cut-set bound and its efficacy is demonstrated by showing that routing is rate-optimal for some commonly cited examples in the networking literature.     

Rates of A-statistical convergence of approximating operators

Abstract Using the concepts of rates of statistical convergence we investigate approximation properties of positive linear operators defined on the space C[0,b], 0<b<1, which includes many well-known operators in approximation theory. We also use the modulus of continuity and Lipschitz functions.     

Cell-Deformability-Monitoring Chips Based on Strain-Dependent Cell-Lysis Rates

We present a novel cell-deformability-monitoring chip based on the digitally measured cell-lysis rate which is dependent on the areal strain of the cell membrane. This method offers simple and automated cell-deformability monitoring based on the mechanical property of the cell membrane. We suggest a filter design that considers the areal strain imposed on the cell membrane passing through the filter array with a gradually increased orifice length. In the experiment using erythrocytes, we characterized the cell deformability in terms of the average fracture areal strains that were 0.24 plusmn 0.014 and 0.21 plusmn 0.002 for normal and chemically treated erythrocytes, respectively. We also verified that the areal strain of 0.15 effectively discriminates the deformability difference of the normal and chemically treated erythrocytes. We compared the lysis rates and their difference for the samples from different donors and found that the patient-specific difference is negligible. However, the additional work on clinical demonstration is required to apply the present chips to the diagnostics. The experimental results demonstrate the simple structure and high performance of the present cell-deformability-monitoring chips, which are applicable to simple and cost-effective cell-aging-process monitoring.     

On Linear-Quadratic Stackelberg Games With Time Preference Rates

This note deals with linear-quadratic Stackelberg differential games including time preference rates with an open-loop information structure. The properties of the characteristic matrix associated with the necessary conditions for a Stackelberg strategy are pointed out. It is shown that such a matrix exhibits a special symmetry property of its eigenvalues. Sufficient conditions to guarantee a predefined degree of stability are given based on the distribution of the eigenvalues in the complex plane.