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1.
Semicontinuous lattices   总被引:10,自引:0,他引:10  
In this paper we introduce and study a new type of lattices, semicontinuous lattices, by using semiprime ideals. Such lattices have many properties similar to that of continuous lattices, and are closely related to the theory of continuous lattices. Received November 3, 1995; accepted in final form March 13, 1997.  相似文献
2.
Emergency Logistics Planning in Natural Disasters   总被引:10,自引:0,他引:10  
Logistics planning in emergency situations involves dispatching commodities (e.g., medical materials and personnel, specialised rescue equipment and rescue teams, food, etc.) to distribution centres in affected areas as soon as possible so that relief operations are accelerated. In this study, a planning model that is to be integrated into a natural disaster logistics Decision Support System is developed. The model addresses the dynamic time-dependent transportation problem that needs to be solved repetitively at given time intervals during ongoing aid delivery. The model regenerates plans incorporating new requests for aid materials, new supplies and transportation means that become available during the current planning time horizon. The plan indicates the optimal mixed pick up and delivery schedules for vehicles within the considered planning time horizon as well as the optimal quantities and types of loads picked up and delivered on these routes. In emergency logistics context, supply is available in limited quantities at the current time period and on specified future dates. Commodity demand is known with certainty at the current date, but can be forecasted for future dates. Unlike commercial environments, vehicles do not have to return to depots, because the next time the plan is re-generated, a node receiving commodities may become a depot or a former depot may have no supplies at all. As a result, there are no closed loop tours, and vehicles wait at their last stop until they receive the next order from the logistics coordination centre. Hence, dispatch orders for vehicles consist of sets of “broken” routes that are generated in response to time-dependent supply/demand. The mathematical model describes a setting that is considerably different than the conventional vehicle routing problem. In fact, the problem is a hybrid that integrates the multi-commodity network flow problem and the vehicle routing problem. In this setting, vehicles are also treated as commodities. The model is readily decomposed into two multi-commodity network flow problems, the first one being linear (for conventional commodities) and the second integer (for vehicle flows). In the solution approach, these sub-models are coupled with relaxed arc capacity constraints using Lagrangean relaxation. The convergence of the proposed algorithm is tested on small test instances as well as on an earthquake scenario of realistic size.  相似文献
3.
By using the method of coincidence degree and Lyapunov functional, a set of easily applicable criteria are established for the global existence and global asymptotic stability of strictly positive(componentwise)periodic solution of a periodic n-species Lotka-Volterra competition system with feedback controls and several deviating arguments.The problem considered in this paper is in many aspects more general and incorporate as special cases various problems which have been studied extensively in the literature.Moreover,our new criteria,which improve and generalize some well known results, can be easily checked.  相似文献
4.
单位圆内拟亚纯映射的重值   总被引:3,自引:1,他引:2       下载免费PDF全文
单位圆内充满圆序列是一个复杂的问题,该文改进了现有一些证法,使单位圆内充满圆证法类似于平面上充满圆证法.同时得到单位圆内K-拟亚纯映射涉及重值的充满圆序列及相应的奇异半径  相似文献
5.
关于亚纯代数体函数的奇异方向   总被引:3,自引:0,他引:3       下载免费PDF全文
设T(r, w)满足:limr →∞lg T(r, w)/lg r =0,limr→∞lg T(r, w)/lg lg r =+ ∞, 则一定存在一条方向arg z=θ0 ,使对任意给定N>0,任意复数 a (至多有2 v个例外值), 有∑i1/(lg|zi(a;?(θ0,δ))|)N=∞.设T(r, w)满足:limr→∞T(r, w)/lgKr =+∞,limr→+∞lg T(r, w) /lg lg r =M, 则一定存在一条方向argz=θ0 ,对任意复数a (至多有2 v个例外值),有∑i1/lg|zi(a;?(θ0,δ))|)σ=∞(σ = M-2或σ = M-2-ε.即使在亚纯函数,这些奇异方向也未见研究.  相似文献
6.
We present a so-called zero-crossing identification method that can crack the security shell of the chaotic encryption method [Chaos, Solitons & Fractals 19 (2004) 919] with periodic modulation. By collecting a special set of truncated data from the zero-crossing incidents of the modulated signal, we can detect the modulating function from chaotic signal. Furthermore we extend the technique to extract modulating function from noise and discuss the potential applications of this method in engineering.  相似文献
7.
A robust search algorithm should ideally exhibit reasonable performance on a diverse and varied set of problems. In an earlier paper Lim et al. (Computational Optimization and Applications, vol. 15, no. 3, 2000), we outlined a class of hybrid genetic algorithms based on the k-gene exchange local search for solving the quadratic assignment problem (QAP). We follow up on our development of the algorithms by reporting in this paper the results of comprehensive testing of the hybrid genetic algorithms (GA) in solving QAP. Over a hundred instances of QAP benchmarks were tested using a standard set of parameters setting and the results are presented along with the results obtained using simple GA for comparisons. Results of our testing on all the benchmarks show that the hybrid GA can obtain good quality solutions of within 2.5% above the best-known solution for 98% of the instances of QAP benchmarks tested. The computation time is also reasonable. For all the instances tested, all except for one require computation time not exceeding one hour. The results will serve as a useful baseline for performance comparison against other algorithms using the QAP benchmarks as a basis for testing.  相似文献
8.
We present a new approach to asset allocation with transaction costs. A multiperiod stochastic linear programming model is developed where the risk is based on the worst case payoff that is endogenously determined by the model that balances expected return and risk. Utilizing portfolio protection and dynamic hedging, an investment portfolio similar to an option-like payoff structure on the initial investment portfolio is characterized. The relative changes in the expected terminal wealth, worst case payoff, and risk aversion, are studied theoretically and illustrated using a numerical example. This model dominates a static mean-variance model when the optimal portfolios are evaluated by the Sharpe ratio. Received: August 15, 1999 / Accepted: October 1, 2000?Published online December 15, 2000  相似文献
9.
In this paper, a class of nonlinear large-scale systems with similar subsystems is studied. Both matched and unmatched uncertainties are considered by utilizing their bounding functions, and the interconnections take a more general form than considered previously. Based on a constrained Lyapunov equation, a nonlinear dynamic output feedback decentralized controller is presented. Unlike existing results, matched uncertainties are considered in the control design; by using a decomposition of the interconnections, the known and uncertain interconnections are treated separately; thus, the robustness is improved and conservativeness is reduced significantly. The computation effort for solving the Lyapunov equation is greatly reduced by taking into account the similar subsystem structure. Finally, simulation is used to illustrate the effectiveness of our results.  相似文献
10.
Quantale中的模糊滤子   总被引:2,自引:0,他引:2  
在Quantale中引入模糊滤子的概念,研究了它的一系列性质,得到了若干等价刻画,讨论了Quantale中滤子和模糊滤子之间的相互确定关系,证明了Quantale态射既保模糊滤子又反射模糊滤子。给出了模糊滤子在Quantale态射下的像的具体结构。  相似文献
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