Current Issue : January - March Volume : 2015 Issue Number : 1 Articles : 5 Articles
City intersection traffic signal control is an important method to improve the efficiency of road network and alleviate traffic\ncongestion. This paper researches traffic signal fuzzy control method on a single intersection. A two-stage traffic signal control\nmethod based on traffic urgency degree is proposed according to two-stage fuzzy inference on single intersection. At the first stage,\ncalculate traffic urgency degree for all red phases using traffic urgency evaluation module and select the red light phase with large\ntraffic urgency as the next phase to switch. At the second stage, green delay of the current green phase is determined by fuzzy\ninference based on the amount of vehicles of current green phase and next green phase. The average vehicle delays are used to\nevaluate the performance of the fuzzy signal controller. Finally, comparisons have been made with pretimed controller and fuzzy\nlogic controller without considering the urgency of red phase. Simulation results show the performance of our proposed method....
This paper considers the problem of centralized spectrum allocations in wireless sensor networks towards the following goals:\n(1) maximizing fairness, (2) reflecting the priority among sensor data, and (3) avoiding unnecessary spectrum handoff. We cast\nthis problem into a multiobjective mixed integer nonconvex nonlinear programming that is definitely difficult to solve at least\nglobally without any aid of conversion or approximation. To tackle this intractability, we first convexify the original problem using\narithmetic-geometric mean approximation and logarithmic change of the decision variables and then deploy weighted Chebyshev\nnorm-based scalarization method in order to collapse the multiobjective problem into a single objective one. Finally, we apply\nsimple rounding method in order to obtain approximate integer solutions.The results obtained from the numerical experiments\nshow that, by adjusting the weight on each objective function, the proposed algorithm allocates spectrum bands fairly with well\nobserving each sensor�s priority and reduced spectrum handoffs....
We consider a multiple vacation queueing system in which a vacation following a busy period has a different distribution from a\nvacation that is taken without serving at least one customer. For ease of analysis it is assumed that the service times are exponentially\ndistributed and the two vacation types are also exponentially distributed but with different means. The steady-state solution is\nobtained....
Experimental tests which match the application conditions might be used to properly evaluate materials for specific applications.\nHigh velocity impacts can be simulated using light-gas gun facilities, which come in different types and complexities. In this work\ndifferent setups for a one-stage light-gas gun facility have been numerically analyzed in order to evaluate their suitability for testing\nmaterials and composites used as armor protection. A maximal barrel length of 6m and a maximal reservoir pressure of a standard\nindustrial gas bottle (20MPa) were chosen as limitations. The numerical predictions show that it is not possible to accelerate the\nprojectile directly to the desired velocity with nitrogen, helium, or hydrogen as propellant gas.When using a sabot corresponding\nto a higher bore diameter, the necessary velocity is achievable with helium and hydrogen gases....
Inventory management in retailers is difficult and complex decision making process which is related to the conflict criteria, also\nexistence of cyclic changes and trend in demand is inevitable in many industries. In this paper, simulation modeling is considered\nas efficient tool for modeling of retailer multiproduct inventory system. For simulation model optimization, a novel multicriteria\nand robust surrogate model is designed based on multiple attribute decision making (MADM) method, design of experiments\n(DOE), and principal component analysis (PCA). This approach as a main contribution of this paper, provides a framework for\nrobust multiple criteria decision making under uncertainty....
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