基于优先权的分布式网络设备智能轮询策略研究

针对大型网络其地域分布广,监测对象较多,监测周期过长,实时性较差且管理流量负载较大等问题,提出一种分布式网络设备智能轮询策略。在域内,针对轮询周期调整问题,通过构造体现管理者意志的评判矩阵和求解反映数据特征的DFT(离散傅立叶变换)确定轮询优先级和轮询周期取值范围,提出了基于变化率的轮询周期调整算法;在域间,通过触发和查询实现对特殊事件的采集。最后进行了仿真,表明该策略能够在减轻网络负载的同时,准确刻画网络的状态。     

Optimal nonmyopic gambling strategy for the generalized Kelly criterion

We consider the optimal wagers to be made by a gambler who starts with a given initial wealth. The gambler faces a sequence of two-outcome games, i.e., “win” vs. “lose,” and wishes to maximize the expected value of his terminal utility. It has been shown by Kelly, Bellman, and others that if the terminal utility is of the form log x, where x is the terminal wealth, then the optimal policy is myopic, i.e., the optimal wager is always to bet a constant fraction of the wealth provided that the probability of winning exceeds the probability of losing. In this paper we provide a critique of the simple logarithmic assumption for the utility of terminal wealth and solve the problem with a more general utility function. We show that in the general case, the optimal policy is not myopic, and we provide analytic expressions for optimal wager decisions in terms of the problem parameters. We also provide conditions under which the optimal policy reduces to the simple myopic case. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 639–654, 1997     

Optimality of the greedy shooting strategy in the presence of incomplete damage information

Consider a situation where a single shooter engages, sequentially, a cluster of targets that may vary in terms of vulnerability and value or worth. Following the shooting of a round of fire at a certain target, the latter may either be killed or remain alive. We assume neither partial nor cumulative damage. If the target is killed, there is a possibility that the shooter is not aware of that fact and may keep on engaging that target. If the shooter recognizes a killed target as such, then this target is considered to be evidently killed. If the objective is to maximize the weighted expected number of killed targets, where the weight reflects the value of a target, then it is shown that a certain type of a shooting strategy, called a Greedy Strategy, is optimal under the general assumption that the more a target is engaged, but still not evidently killed, the less is the probability that the next round will be effective. If all weights are equal, then the greedy shooting strategy calls to engage, at each round, the least previously engaged target that is not evidently killed. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 613–622, 1997     

An application of the MTP2 property on bounds on system reliability

This paper is concerned with the joint prior distribution of the dependent reliabilities of the components of a binary system. When this distribution is MTP₂ (Multivariate Totally Positive of Order 2), it is shown in general that this actually makes the machinery of Natvig and Eide [7] available to arrive at the posterior distribution of the system's reliability, based on data both at the component and system level. As an illustration in a common environmental stress case, the joint prior distribution of the reliabilities is shown to have the MTP₂ property. We also show, similarly to Gåsemyr and Natvig [3], for the case of independent components given component reliabilities how this joint prior distribution may be based on the combination of expert opinions. A specific system is finally treated numerically. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 741–755, 1997     

Variable sampling plans for normal distribution indexed by Taguchi's loss function

Taguchi has presented an approach to quality improvement in which reduction of deviation from the target value is the guiding principle. In this approach any measured value x of a product characteristic X brings a loss to consumer in general, where the loss is expressed as a quadratic form with respect to the difference between the measured value x and the target value T of a product characteristic. Then, it is natural to reject the lot which may bring a large loss to consumer. This concept induces us to construct new variable sampling plans based on the Taguchi's loss criterion. In this article, a design procedure of the sampling plans for assuring the loss in the Taguchi's method is proposed. Some numerical results based on the proposed design procedures are illustrated. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 591–603 (1997)     

Decomposition and hybrid simulated annealing heuristics for the parallel-machine total tardiness problem

A polynomial decomposition heuristic is developed for the parallel-machine tardiness problem (P&sol& sol;T) by extending the decomposition principle embedded in the single-machine tardiness problem (1&sol/T) to a parallel-machine setting. The subproblems generated by the decomposition are solved by an effective heuristic that yields solutions such that the schedule on any individual machine satisfies the single-machine decomposition principle. A hybrid simulated annealing heuristic tailored to the P&sol/T problem is also presented. Computational results demonstrate the efficiency and effectiveness of the decomposition heuristic. © 1997 John Wiley & Sons, Inc.     

The effect of training data set size and the complexity of the separation function on neural network classification capability: The two-group case

Classification among groups is a crucial problem in managerial decision making. Classification techniques are used in: identifying stressed firms, classifying among consumer types, and rating of firms' bonds, etc. Neural networks are recognized as important and emerging methodologies in the area of classification. In this paper, we study the effect of training sample size and the neural network topology on the classification capability of neural networks. We also compare neural network capabilities with those of commonly used statistical methodologies. Experiments were designed and carried out on two-group classification problems to find answers to these questions. The prediction capability of the neural network models are better than traditional statistical models. The learning capability of the neural networks is improving compared to traditional models because the discriminate function is more complex. For real world classification problems, the usage of neural networks is highly recommended, for two reasons: learning capability and flexibility. Learning capability: Neural network classifies better in sterile experiments as performed in this research. Flexibility: Real life data are rarely not contaminated with noise, such as unknown distributions, and missing variables, etc. Neural networks differ from a statistical model that it is not dependent on any assumption concerning the data set distribution. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 699–717, 1997     

Testing or fault-finding for reliability growth: A missile destructive-test example

A new piece of equipment has been purchased in a lot of size m. Some of the items can be used in destructive testing before the item is put into use. Testing uncovers faults which can be removed from the remaining pieces of equipment in the lot. If t < m pieces of equipment are tested, then those that remain, m₁ = m − t, have reduced fault incidence and are more reliable than initially, but m₁ may be too small to be useful, or than is desirable. In this paper models are studied to address this question: given the lot size m, how to optimize by choice of t the effectiveness of the pieces of equipment remaining after the test. The models used are simplistic and illustrative; they can be straightforwardly improved. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 623–637, 1997     

Minimum cost component test plans for evaluating reliability of a highly reliable parallel system

One approach to evaluating system reliability is the use of system based component test plans. Such plans have numerous advantages over complete system level tests, primarily in terms of time and cost savings. This paper considers one of the two basic building blocks of many complex systems, namely a system of n parallel components, and develops minimum cost component test plans for evaluating the reliability of such a system when the component reliabilities are known to be high. Two different decision rules are considered and the corresponding optimization problems are formulated and solved using techniques from mathematical programming. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44 : 401–418, 1997     

Scheduling stochastic jobs with asymmetric earliness and tardiness penalties

We consider a stochastic counterpart of the well-known earliness-tardiness scheduling problem with a common due date, in which n stochastic jobs are to be processed on a single machine. The processing times of the jobs are independent and normally distributed random variables with known means and known variances that are proportional to the means. The due dates of the jobs are random variables following a common probability distribution. The objective is to minimize the expectation of a weighted combination of the earliness penalty, the tardiness penalty, and the flow-time penalty. One of our main results is that an optimal sequence for the problem must be V-shaped with respect to the mean processing times. Other characterizations of the optimal solution are also established. Two algorithms are proposed, which can generate optimal or near-optimal solutions in pseudopolynomial time. The proposed algorithms are also extended to problems where processing times do not satisfy the assumption in the model above, and are evaluated when processing times follow different probability distributions, including general normal (without the proportional relation between variances and means), uniform, Laplace, and exponential. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44, 531–557, 1997.     

On a ruckle problem in discrete games of ambush

The following zero-sum game is considered. Red chooses in integer interval [1, n] two integer intervals consisting of k and m points where k + m < n, and Blue chooses an integer point in [1, n]. The payoff to Red equals 1 if the point chosen by Blue is at least in one of the intervals chosen by Red, and 0 otherwise. This work complements the results obtained by Ruckle, Baston and Bostock, and Lee. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 353–364, 1997     

Note: Optimal allocation of resources to nodes of series systems with respect to failure-rate ordering

Allocation of spare components in a system in order to optimize the lifetime of the system with respect to a suitable criterion is of considerable interest in reliability, engineering, industry, and defense. We consider the problem of allocation of K active spares to a series system of independent and identical components in order to optimize the failure-rate function of the system. © 1997 John Wiley & Sons, Inc.     

A heuristic algorithm for determining replacement policies in k-out-of-n systems

The authors study a discrete-time, infinite-horizon, dynamic programming model for the replacement of components in a binary k-out-of-n failure system. (The system fails when k or more of its n components fail.) Costs are incurred when the system fails and when failed components are replaced. The objective is to minimize the long-run expected average undiscounted cost per period. A companion article develops a branch-and-bound algorithm for computing optimal policies. Extensive computational experiments find it effective for k to be small or near n; however, difficulties are encountered when n ≥ 30 and 10 ≤ k ≤ n − 4. This article presents a simple, intuitive heuristic rule for determining a replacement policy whose memory storage and computation time requirements are O(n − k) and O(n(n − k) + k), respectively. This heuristic is based on a plausible formula for ranking components in order of their usefulness. The authors provide sufficient conditions for it to be optimal and undertake computational experiments that suggest that it handles parallel systems (k = n) effectively and, further, that its effectiveness increases as k moves away from n. In our test problems, the mean relative errors are under 5% when n ≤ 100 and under 2% when k ≤ n − 3 and n ≤ 50. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44, 273–286, 1997.     

Probabilistic analysis of an asymptotically optimal solution for the completion time variance problem

Scheduling a set of n jobs on a single machine so as to minimize the completion time variance is a well‐known NP‐hard problem. In this paper, we propose a sequence, which can be constructed in O(n log n) time, as a solution for the problem. Our primary concern is to establish the asymptotical optimality of the sequence within the framework of probabilistic analysis. Our main result is that, when the processing times are randomly and independently drawn from the same uniform distribution, the sequence is asymptotically optimal in the sense that its relative error converges to zero in probability as n increases. Other theoretical results are also derived, including: (i) When the processing times follow a symmetric structure, the problem has 2^{⌊(n−1)/2⌋} optimal sequences, which include our proposed sequence and other heuristic sequences suggested in the literature; and (ii) when these 2^{⌊(n−1)/2⌋} sequences are used as approximate solutions for a general problem, our proposed sequence yields the best approximation (in an average sense) while another sequence, which is commonly believed to be a good approximation in the literature, is interestingly the worst. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 373–398, 1999     

战术数据链动态时隙分配算法研究

现代信息化作战中,战术数据链网络系统正发挥着越来越重要的作用。本文以战术数据链时隙分配算法为研究对象,在深入分析两种典型时隙分配算法的基础上,提出了一种动态时隙分配算法。仿真结果表明该动态时隙分配算法灵活性较好,较轮询与TDMA固定时隙分配算法,其能够更好地适应瞬息万变的战场需求。     

A dynamic-programming approach to continuous-review obsolescent inventory problems

Inventory models of modern production and service operations should take into consideration possible exogenous failures or the abrupt decline of demand resulting from obsolescence. This article analyzes continuous-review versions of the classical obsolescence problem in inventory theory. We assume a deterministic demand model and general continuous random times to obsolescence (“failure”). Using continuous dynamic programming, we investigate structural properties of the problem and propose explicit and workable solution techniques. These techniques apply to two fairly wide (and sometimes overlapping) classes of failure distributions: those which are increasing in failure rate and those which have finite support. Consequently, several specific failure processes in continuous time are given exact solutions. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 757–774, 1997     

A partial characterization of the optimal ordering/rationing policy for a periodic review system with two demand classes and backordering

We consider a finite horizon periodic review, single product inventory system with a fixed setup cost and two stochastic demand classes that differ in their backordering costs. In each period, one must decide whether and how much to order, and how much demand of the lower class should be satisfied. We show that the optimal ordering policy can be characterized as a state dependent (s,S) policy, and the rationing structure is partially obtained based on the subconvexity of the cost function. We then propose a simple heuristic rationing policy, which is easy to implement and close to optimal for intensive numerical examples. We further study the case when the first demand class is deterministic and must be satisfied immediately. We show the optimality of the state dependent (s,S) ordering policy, and obtain additional rationing structural properties. Based on these properties, the optimal ordering and rationing policy for any state can be generated by finding the optimal policy of only a finite set of states, and for each state in this set, the optimal policy is obtained simply by choosing a policy from at most two alternatives. An efficient algorithm is then proposed. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

Quantifying the performance effects of idle time utilization in multiserver systems

In many practical multiserver queueing systems, servers not only serve randomly arriving customers but also work on the secondary jobs with infinite backlog during their idle time. In this paper, we propose a c‐server model with a two‐threshold policy, denoted by (e d), to evaluate the performance of this class of systems. With such a policy, when the number of idle servers has reached d (<c), then e (<d) idle agents will process secondary jobs. These e servers keep working on the secondary jobs until they find waiting customers exist in the system at a secondary job completion instant. Using the matrix analytic method, we obtain the stationary performance measures for evaluating different (e, d) policies. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007.     

Introduction: Exploring the jungle of terminology

When twentieth-century authors wrote about ‘partisan warfare’, they usually meant an insurgency or asymmetric military operations conducted against a superior force by small bands of ideologically driven irregular fighters. By contrast, originally (i.e. before the French Revolution) ‘partisan’ in French, English, and German referred only to the leader of a detachment of special forces (party, partie, Parthey, détachement) which the major European powers used to conduct special operations alongside their regular forces. Such special operations were the classic definition of ‘small war’ (petite guerre) in the late seventeenth and in the eighteenth centuries. The Spanish word ‘la guerrilla’, meaning nothing other than ‘small war’, only acquired an association with rebellion with the Spanish War of Independence against Napoleon. Even after this, however, armies throughout the world have continued to employ special forces. In the late nineteenth century, their operations have still been referred to as prosecuting ‘la guerrilla’ or ‘small war’, which existed side by side with, and was often mixed with, ‘people's war’ or popular uprisings against hated regimes.     

What made American Civil War soldiers fight?

James M. McPherson, For Cause and Comrades: Why Men Fought in the Civil War. New York: Oxford University Press, 1997. Pp.xv + 237, appendix, notes, index. £20 (cloth); $13.95 (paper). ISBN 0–10–512499–5