面向应急对地观测任务的多平台资源部署优化研究

提出了一种基于遗传算法的面向应急对地观测任务的多平台资源部署优化方法。该方法通过把观测区域离散化为网格点的集合,将多平台资源部署问题形式化为一个组合优化问题,其目标是在一定响应时间约束下最大化观测区域覆盖率。设计的求解算法采用整数编码表示各平台资源的部署位置,使用精英保留策略加快算法收敛速度。仿真结果表明,该方法能够快速获得满意的卫星、飞艇、无人机多平台资源部署方案。     

An Averaging Method for Singularly Perturbed Systems of Semilinear Differential Inclusions with C 0-Semigroups

We consider a system of two semilinear differential inclusions with infinitesimal generators of C ₀-semigroups. The nonlinear terms are of high frequency with respect to time and periodic with a specified period. Moreover, they are condensing in the state variables (x,y) with respect to a suitable measure of noncompactness. The goal of the paper is to give sufficient conditions to guarantee, for ∈>0 sufficiently small, the existence of periodic solutions and to study their behaviour as ∈→0. The main tool to achieve this is the topological degree theory for uppersemicontinuous, condensing vector fields.     

一带一路背景下企业地域影响力发展的规划研究

面对一个分布在新地理区域的新市场,合理规划区域服务影响力的发展战略对企业至关重要。本文假设企业的服务影响力在地理区域上的发展可以用其地理上分布的立足点来表示。单个立足点覆盖有限范围内的地理区域,并且在一个特定时刻用所有立足点所覆盖地理区域的总和来表示企业该时刻的发展状态。由于资源限制,企业对经济发展迅速的区域的覆盖必须在一定时间内逐步完成。因此,在发展时期内如何确定立足点的位置并使其位于知名城市中,是企业管理者亟待解决的问题。针对这个问题,本文首先基于时间序列预测方法建立了区域经济指标评估模型;然后使用集合覆盖理论提出了以成本和满意度为目标的选址优化模型并使用分支定界算法求解该模型;最后,使用从“一带一路”地区收集的数据对模型进行了检验。结果表明,该方法对有相关问题的企业具有较大的参考价值。     

An adaptive heuristic algorithm for VLSI test vectors selection

The increasing complexity of today’s system-on-a-chip designs is putting more pressure on the already stressed design verification process. The verification plan must cover several individual cores as well as the overall chip design. Conditions to be verified are identified by the system’s architects, the designers, and the verification team. Testing for these conditions is a must for the design to tape out, especially for high priority conditions. A significant bottleneck in the verification process of such designs is that not enough time is usually given to the final coverage phase, which makes computing cycles very precious. Thus, intelligent selection of test vectors that achieve the best coverage using the minimum number of computing cycles is crucial for on time tape out. This paper presents a novel heuristic algorithm for test vectors selection. The algorithm attempts to achieve the best coverage level while minimizing the required number of computing cycles.     

Formulating and solving a multi-mode resource-collaboration and constrained scheduling problem (MRCCSP)

The main motivation of this study is to provide, for the first time, a formulation and solution for a class of production scheduling problems (as in cluster tools) characterized mainly by resource collaboration to perform an operation and while allowing batches and considering alternative production methods. We develop a formulation for the new problem and term it a multiple mode per operation, resource collaboration, and constrained scheduling problem (MRCCSP). Some of the important new characteristics we consider are: multiple products (families); multiple orders (jobs) per family; precedence restrictions among the operations that constitute a job; alternative modes for the performance of an operation (each of which needs a set of collaborating resources) may be defined; complementary and exclusive restrictions between operation-modes; batch production is allowed; and setup times may depend on sequence and batch-size. The objective of the MRCCSP is to minimize makespan. We formulate the MRCCSP as a mixed integer linear programming model, and acknowledging the considerable size of the monolithic formulation required, we prescribe a specific method to achieve size reduction. Finally, a customized branch and bound algorithm for optimally solving this problem is proposed and examined experimentally.     

Topological properties of strongly monotone planar vector fields

We consider strongly monotone continuous planar vector fields with a finite number of fixed points. The fixed points fall into three classes, attractors, repellers and saddles. Naturally, the relative positions of the fixed points must obey a set of restrictions imposed by monotonicity. The study of these restrictions is the main goal of the paper. With any given vector field, we associate a matrix describing the arrangement of the fixed points on the plane. We then use these matrices to formulate simple necessary and sufficient conditions which allow one to determine whether a finite set of attractors, repellers and saddles at given positions on the plane can be realized as the fixed point set of a strongly monotone vector field.     

A new approach for achievement of the equilibrium efficient frontier with fixed-sum outputs

In a recent paper, Yang et al developed an algorithm based on the extended minimal adjustment strategy and the equilibrium competition strategy to achieve a common equilibrium efficient frontier. However, the computational burden of their algorithm is challenging when a sample contains many inefficient decision-making units (DMUs). In this paper, we propose a linear programming model that can achieve a common equilibrium efficient frontier in a single step, regardless of the number of inefficient DMUs. Furthermore, we demonstrate the existence and the non-uniqueness of the equilibrium efficient frontier and identify its shortcomings through an example. Next, we extend our approach to incorporate weight restrictions to indicate the relative importance of the different inputs and outputs and introduce the secondary goal of minimizing the maximal relative deviation for each fixed-sum output, which can result in a unique equilibrium efficient frontier.     

Scheduling data transfers in a network and the set scheduling problem

In this paper we consider the online ftp problem. The goal is to service a sequence of file transfer requests given bandwidth constraints of the underlying communication network. The main result of the paper is a technique that leads to algorithms that optimize several natural metrics, such as max-stretch, total flow time, max flow time, and total completion time. In particular, we show how to achieve optimum total flow time and optimum max-stretch if we increase the capacity of the underlying network by a logarithmic factor. We show that the resource augmentation is necessary by proving polynomial lower bounds on the max-stretch and total flow time for the case where online and offline algorithms are using same-capacity edges. Moreover, we also give polylogarithmic lower bounds on the resource augmentation factor necessary in order to keep the total flow time and max-stretch within a constant factor of optimum.     

Fuzzy goal programming models for analyzing demand coverage

The main objective of demand coverage models is to locate servers so that a given demand space is appropriately covered. Most existing models assume that demand is located at specific points within an area and that coverage is evaluated by certain quantifiable criteria. However, in realistic applications, the concept of coverage may also include qualitative aspects. Moreover, the location of the servers may be determined on the basis of more than one objective. In this paper, we present a number of fuzzy goal programming models for demand coverage. We consider three objectives: (a) maximization of total coverage, (b) maximization of minimum coverage, and (c) minimization of distance to servers of uncovered demand points. Through a series of realistic problem instances, we demonstrate that the proposed models provide satisfactory solutions with respect to all three objectives.     

Finite-time consensus for switching network topologies with disturbances

In this paper we investigate the properties of a decentralized consensus algorithm for a network of continuous-time integrators subject to unknown-but-bounded time-varying disturbances. The proposed consensus algorithm is based on a discontinuous local interaction rule. Under certain restrictions on the switching topology, it is proven that after a finite transient time the agents achieve an approximated consensus condition by attenuating the destabilizing effect of the disturbances. This main result is complemented by an additional result establishing the achievement of consensus under different requirements on the switching communication topology. In particular, we provide a convergence result that encompasses situations in which the time varying graph is always disconnected. Lyapunov analyses are carried out to support the suggested algorithms and results. Simulative tests considering, as case study, the synchronization problem for a network of clocks are illustrated and commented on to validate the developed analysis.     

Picard iteration convergence analysis in a Galerkin finite element approximation of the one-dimensional shallow water equations

A Fourier method for analyzing iteration convergence is applied to four different formulations of the “simple” or Picard iteration procedure of a shallow water model. The model uses the Galerkin linear FE scheme in space and the implicit θ finite differencing in time. Although the numerical scheme is implicit and linearly stable for forward centering in time (θ > 0.5), it is shown that if the Picard iteration procedure is used, there may be additional operating restrictions which need to be observed to achieve iteration convergence. These restrictions effectively limit the time step (Δt) and take the form of upper bounds on θ times the Courant number (θ?). In the 1D shallow water model, iteration convergence requires θ?$ \le 1/ \sqrt 3 $ for two of the four iteration formulations, but there are no effective restrictions for the other two formulations. These results were confirmed by numerical experiments. There is a tradeoff between computer storage and run times. The model version with the shortest run time (due to unrestricted Δt) also requires most computer storage. © 1993 John Wiley & Sons, Inc.     

Hybrid coordinate approach for the modelling and simulation of multibody systems

The main goal of the present work is to provide an add-on scheme for the formulation of multibody dynamics, based on natural coordinates, in regard to ideally balanced rigid bodies with high rotational spin, e.g. gyroscopes. The underlying aim of this approach is to achieve higher numerical accuracy whenever the preferred axis of rotation coincides with the balanced main axis of the body. This will be achieved by seperating the spin of the balanced rigid body along the denoted axis as an additional angular coordinate, whereas the other rotations will be covered by a carried frame, parameterized via natural coordinates. At the same time the carried frame provides a link to the existing modelling framework in terms of natural coordinates, enabling a straightforward implementation into existing multibody systems (e.g. rotary crane [2]). (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Parameter estimation in convection dominated nonlinear convection–diffusion problems by the relaxation method and the adjoint equation

The development of numerical methods for strongly nonlinear convection–diffusion problems with dominant convection is an ongoing topic in numerical analysis. For inverse problems in this setting, there is a need of fast and accurate solvers. Here, we present operator splitting with a Riemann solver for the convective part and a relaxation method for the diffusive part, as a means to achieve this goal. Combined with the adjoint equation method this allows us to solve inverse problems within reasonable time frames and with modest computing power. As an example, the dual-well experiment is considered and the adjoint method is compared with a conjugate gradient algorithm and a Levenberg–Marquardt type of iteration method.     

An Averaging Method for Singularly Perturbed Systems of Semilinear Differential Inclusions with C0-Semigroups

We consider a system of two semilinear differential inclusions with infinitesimal generators of C ₀-semigroups. The nonlinear terms are of high frequency with respect to time and periodic with a specified period. Moreover, they are condensing in the state variables (x,y) with respect to a suitable measure of noncompactness. The goal of the paper is to give sufficient conditions to guarantee, for >0 sufficiently small, the existence of periodic solutions and to study their behaviour as 0. The main tool to achieve this is the topological degree theory for uppersemicontinuous, condensing vector fields.     

A multiobjective model for forest planning with adjacency constraints

This work presents a nonlinear goal programming model with binary variables used to plan the management of a tree plantation, taking economic and environmental objectives into account. The aims are to stay within the limits of a given harvesting volume, limit the age of basic units targeted for clearcutting, obtain a forest with a balanced age distribution, and surpass the minimum net present value set at each planning period. This has to be achieved bearing in mind technical restrictions regarding treatments, and spatial adjacency constraints that limit the maximum adjacent surface area to which clearcutting can be applied. The outcome is a highly complex problem that is solved by applying a metaheuristic method based on Scatter Search. The proposed model has been validated by applying it to a Cuban plantation located in the region of Pinar del Río.     

Computational bifurcation of periodic solutions in systems with symmetry

A bifurcation problem given by a -symmetric parameter-dependentsystem of autonomous ordinary differential equations is considered( a finite group). The main goal is to derive an efficient numericalmethod for the computation of symmetry breaking, period doublingand symmetry breaking period doubling bifurcations of periodicsolutions. For this the bifurcation problem is reformulatedin terms of Fourier coefficient vectors. This makes it possibleto make use of the spatial and temporal symmetries of periodicsolutions in order to reduce the effort for solving the problemeffectively. Finally, a Galerkin method based on Fourier expansionsis used for the numerical treatment and this method is illustratedby a numerical example.     

Genetic algorithm based approach for the integrated airline crew-pairing and rostering problem

Airline crew scheduling problem is a complex and difficult problem faced by all airline companies.To tackle this problem, it was often decomposed into two subproblems solved successively. First, the airline crew-pairing problem, which consists on finding a set of trips – called pairings – i.e. sequences of flights, starting and ending at a crew base, that cover all the flights planned for a given period of time. Secondly, the airline crew rostering problem, which consists on assigning the pairings found by solving the first subproblem, to the named airline crew members. For both problems, several rules and regulations must be respected and costs minimized.It is sure that this decomposition provides a convenient tool to handle the numerous and complex restrictions, but it lacks, however, of a global treatment of the problem. For this purpose, in this study we took the challenge of proposing a new way to solve both subproblems simultaneously. The proposed approach is based on a hybrid genetic algorithm. In fact, three heuristics are developed here to tackle the restriction rules within the GA’s process.     

Optimal maintenance service contract negotiation with aging equipment

In recent years, there has been a growing trend to out-source service operations in which the equipment maintenance is carried out by an external agent rather than in-house. Often, the agent (service provider) offers more than one option and the owners of equipment (customers) are faced to the problem of selecting the optimal option, under the terms of a contract. In the current work, we develop a model and report results to determine the agent’s optimal strategy for a given type of contract. The model derives in a non-cooperative game formulation in which the decisions are taken by maximizing expected profits. This work extends previous models by considering the realistic case of equipments having an increasing failure intensity due to imperfect maintenance, instead of the standard assumption that considers failure times are exponentially distributed (constant failure intensity). We develop a model using a linear function of time to characterize the failure intensity. The main goal, for the agent, is to determine the pricing structure in the contract and the number of customers to service. On the other hand, for the clients, the main goal is to define the period between planned actions for preventive maintenance and the time to replace equipments. In order to give a complete characterization of the results, we also carry out a sensitivity analysis over some of the factors that would influence over the failure intensity.     

The special routes in plane graphs

Let plane undirected graph G = (V, E) be set of items of all manipulator possible trajectories. The problem is constructing of routes satisfying different restrictions. The restrictions can be classified as local and global. For local restrictions the next edge in a route is defined by the conditions set for current vertex or edge. Otherwise restriction is called global. Examples of local restrictions are straightforward paths; a route in which the next edge is defined by the given cycle order on the set of edges incident the current vertex; a route where some edges should be passed in predefined order. The example of global restriction is problem of constructing the cover with ordered enclosing. The paper presents some ways to formalize restrictions and also information about algorithms for constructing of Eulerian covering for plane graph by the sequence of allowed trails. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)