Papers by Keyword: Branch Algorithm

Abstract: In order to realize scientific planning the layout of strategic loading station, the strategic-loading –station location problem was proposed, which is related to determine the location of each stay with station and the transportation plan on the precise of satisfying the general location constraints and problem related special constraints. Based on theory of capacitated facility location with multiple souring in two stage supply chain, one mixed integer linear programming model was established which took whole logistic cost embedding transportation and location costs as objective. When confronted with small and medium size problem, this model could be exactly solved by optimization software using branch and bound algorithm, and when the problem size was big, this model could be heuristically solved by genetic algorithm which used 0-1 and priority-based combined encoding method to represent solution, cost-based and random-generated combined method to generate initial solution, solution repaired strategy and penalty method and special fitness function to deal illegal individual, and greedy based method to heuristically solve transshipment problem. At last, according to computational tests on randomly generated data demonstrated the practical feasibility of this method.

Abstract: Ultra-wideband(UWB) is currently one of three new technologies of wireless communication. Multi-user detection technique is mainly used to eliminate multiple access interference（MAI）in DS-CDMA UWB communication systems. Linear multi-user detection algorithm for multi-access interference suppression or even elimination has certain results. But for a fixed decision threshold is set to 0, the detection performance of linear multi-user detection algorithm will be decreased significantly. Therefore a kind of multi-user detection with pre-processing has been researched. Through the pre-processing, we set dynamic threshold to direct decision the user's data bit information so as to solve the problem the linear multi-user detector’s decision threshold which is fixed impact the detection performance. We may get the global optimal solution though pre-processing of using the thought of the branch and bound algorithm and forcing rules. Then the original problem changes into a smaller multi-user detection problem, in order to get the aim of reducing MAI, increasing the probability of a correct decision and reducing the bit error rate. From the simulation experiment results, it is shown that it has a significant effect in system detection, because after pre-processing the probability of a correct decision has increased, and the bit error rate has been reduced.

Abstract: This paper deals with an optimal method for solving a 2-stage flexible flow shop scheduling problem with group constraint, batch released dates. This problem is known to be NP-hard. In this paper, first of all, we construct a mathematical model for the problem. Then, we develop a branch and bound method with heuristic algorithm for the optimal solution of the problem. During the initialization, we use a heuristic algorithm H’ as the initial solution. We propose two branching algorithms in the branching procedure and two algorithms for the lower bound. We also propose a set of instances for this type of problem. The results are shown that our branch and bound method is effective for small and medium-sized problem but large-sized problem.

Abstract: In this technical note, we develop an approach to globally solve a class of optimization problems in system engineering based on the recent paper ([1]). Actually the problem we investigated is more general, since we extend numerators and denominators of linear ratios to generalized polynomial functions. And we give a new linear relaxation method for obtaining the lower bound of problems. Our approach is easy to be implemented, since it need not additional special program to the upper and lower bound for numerator and denominator of each generalized polynomial ratio.

Abstract: In this paper, we proposed an algorithm to globally solve a class of mathematical problems in mechanical system. Firstly, by utilizing equivalent problem and linear relaxation technique, a linear relaxation programming of original mathematical problem is established. Secondly, by using branch and bound theory, a feasible algorithm is proposed for globally solving original problem. Finally, the convergence of the proposed algorithm is proven, and numerical experiments showed that the presented algorithm is feasible.

Abstract: In this paper, we develop an algorithm to globally solve a class of mathematical models in system engineering. Firstly, by utilizing equivalent problem and linear relaxation method, a linear relaxation programming of original problem is established. Secondly, by using branch and bound technique, a determined branch and bound algorithm is proposed for globally solving original problem. Finally, the convergence of the proposed algorithm is given and numerical examples showed that the presented algorithm is feasible.

Abstract: Photo-oxidation of polyethylene (PE) has been studied thoroughly these years owing to its high output and various applications, which makes knowledge about its degradation of vital practical importance. Polyethylene products often suffer from service environment factors including ultraviolet, heat or chemicals, which may deteriorate their mechanical properties. The degradation behavior varies with the chain structure and morphology of polyethylene, e.g., branches, linear segments length and crystallization. Natural degradation of three kinds of polyethylene (HDPE, LDPE and LLDPE) has been examined in samples using different annealing conditions in this work. The extent of degradation, described as carbonyl index, was evaluated by Fourier transform infrared spectroscopy (FTIR). Crystallinity measurements were made using differential scanning calorimetry(DSC). The investigation indicates that the branch structure plays a dominant role in the photo-oxidation of polyethylene. Annealing will change the crystallinity of polyethylene before aging, but do not show obvious dependence on the oxidation.