Systems Engineering - Theory & Practice最新文献

In this article, the simulation for the population of altruist and egoist in herd behavior model is studied with the artificial society theory in economics. The results show that although it is unfavorable to the altruist just in one game, players will choose the altruist behavior when the payoff for the altruist behavior is enough.

The notions of kernel and closure of intuitionistic fuzzy relations are proposed, and fourteen-sets theorem of intuitionistic fuzzy relations is proved. First, we propose the notions of anti-reflexive kernel, symmetric kernel, reflexive closure and symmetric closure of intuitionistic fuzzy relations by intuitionistic fuzzy anti-reflexive relations, symmetric relations and reflexive relations. Second, their accurate formulae and some properties are respectively obtained by utilizing some properties of intuitionistic fuzzy relations. Last, we conclude that fourteen different intuitionistic fuzzy relations can be constructed at most by using these properties via symmetric kernel operator, symmetric closure operator and complement operator from an intuitionistic fuzzy relation.

Based on grey system theory, the decision-making problem is discussed, in which the attribute values are interval grey numbers and maximum probability of the value of grey number is known. Firstly, three-parameter interval grey number is defined, and the method of three-parameters grey interval incidence degree is presented by using the characteristic of this kind of grey number and the advantage of classical grey incidence decision making. Secondly, considering the proximity and comparability of space position and geometry shape among every scheme's effect-evaluation vector, ideal project, and critical project, we construct the three-parameter grey interval slope incidence coefficient formula. Integrated with the above, the three-parameter grey interval incidence coefficient formula, the method of the grey interval synthesis close degree is given. Finally, by using the analytical technique of the expectation value of three-parameter interval grey numbers and projecting pursuit algorithm, the projection attribute function method is introduced. In addition, the corresponding algorithms of the above three methods are given. An example is used to demonstrate the rationality and validity of the proposed decision-making algorithms. A new approach is provided for the grey decision-making theory and its application.

A new class of assignment problem which roots in the optimization management of slabs in steel industry is considered in this article. Compared with the generalized assignment problem, flow constraints should be considered in this problem besides the capacity constraints when assigning items to knapsacks. This problem could be reduced to the generalized assignment problem, and so is NP-hard. A heuristic with oscillation strategy and long-term memory list is proposed to solve it. The oscillation strategy makes it possible that the local search oscillates between the feasible and infeasible solution spaces to find better feasible solutions. A long-term memory list is embedded to encourage the diverse moves of items, which improves the diversity of the algorithm. In order to testify the efficiency of the heuristic, 23 instances have been randomly generated for the computational experiments. The results show that for small-size instances, the maximum deviation of the heuristic from the optimal solution is 0.55% and for larger-size instances, the heuristic could find good solutions in a very short time.

Limit water level control improves water resources utilization efficiency without reducing flood control standard, while the premise is to divide the discharge series into a number of different flood stages. Db4 is selected as wavelet base, based on Mallat algorithm, put forward the model of wavelet dimension estimation method and calculated the fractal dimension of floods at the Yichang station, got the flood periods of Three Gorges reservoir. The results indicate that the method of wavelet dimension estimation can obtain the same result as traditional methods, and it has the merit of simplicity and stability. As a feasible and effective tool, the wavelet dimension estimation method is recommended in the applications of dividing flood periods.

To study the capacity planning problem under uncertainty in which market demand and product price are stochastic, multi period capacity planning model based on scenario was investigated in this paper. Two models were proposed: one is a prearranged planning model in which the capacity investment plan do not change with the stochastic market demand, and the other is an adaptive planning model in which capacity investment plan could trace the evolution progress of the stochastic market demand. The computational study compared the decision results of both models, which reveals that the adaptive planning model could suggest better decision. Moreover, based on downside risk analysis, the investment risk of stochastic capacity planning has been investigated, and a prearranged capacity planning model considering the expected downside risk of the objective revenue was proposed. In the model, a constraint of expected downside risk is added to the initial stochastic model to reflect the decision-maker's risk preference. Whether to consider the risk or not will result in different decisions, which, in the computational study, were compared.

At present, almost all kinds of fuzzy controllers are designed by using ⊙-composite operator. Particularly, people have already used ⊙-composite operator to design the industrial Boiler Drum Water Level Fuzzy Controller, and we call this designed scheme as Scheme 1 in this article. Here, @-composite operator is used to design the industrial Boiler Drum Water Level Fuzzy Controller and three new schemes are obtained, as Scheme 2, Scheme 3 and Scheme 4. Moreover, the four schemes are all implemented by using Matlab in this article. According to the experimental result analysis, Scheme 2 provides the best control effect, and this shows that @-composite operator is more appropriate for designing fuzzy controllers.

Considering such a fact that the traffic demand freshly entering a network does not have perfect information about traffic condition and then might choose travel routes randomly, we propose an improved network traffic flow evolution model in this article. The model's properties and fixed points are investigated. The fixed points of the model, which are different from traditional user equilibrium state or part user equilibrium state, can better formulate the result of traffic flow assignment in realization. Simulation results obtained from a grid network show that the model can be used to approximately model the process of realizing user equilibrium state, the network flow can indeed evolve to one or more fixed points, and the initial values of all available path flows can be zero.

Based on the research of small and medium-sized enterprises' life cycle, plus the data and the information that acquired from cancelled small and medium-sized enterprises (SMEs) in Shenzhen, Guangzhou, Changsha, Zhengzhou, Chengdu five metropolises during 2000-2007 period, this paper evaluated and comparatively analyzed the relation between the life cycle of SMEs in the five metropolises and the external environment that SMEs sit in, revealed the relation and the internal mechanism of SMEs and their external environmental situation. Further more, the countermeasures how to prolong the life cycle of SMEs in our country is proposed from perspective both of government and corporation.

This article investigates a portfolio selection problem with different borrowing–lending rates and with Value-at-Risk (VaR) as the measure of risk. The problem is formulated as a utility maximization model with a general utility function that is a function of only the mean and the VaR of portfolio return. Several properties of the efficient frontier of the mean-VaR model are first obtained and then used to give some existence conditions and characterizations of the optimal solution to the utility maximization model. Further, a solution method and a numerical algorithm for solving the optimal solution are proposed. Finally, a numerical example using the real data of Chinese stock market is given to show the validity and the practicability of these results.