Applied Mechanics and Materials Vols. 101-102

Abstract: The basic artificial bee colony algorithm gets local extremum easily and converges slowly in optimization problems of the multi-object function. In order to enhance the global search ability of basic artificial bee colony algorithm, an improved method of artificial bee colony algorithm is proposed in this paper. The basic idea of this method is as follows: On the basis of traditional artificial bee colony algorithm, the solution vectors that found by each bee colony are recombined after each iteration, then the solution vectors of combinations are evaluated again, thus the best result is found in this iteration. In this way the possibility of sticking at local extremum is reduced. Finally the simulation experiment has been finished. The simulation experiment results have shown that the method proposed in this paper is feasible and effective, it is better than basic artificial bee colony algorithm in the global search ability.

Abstract: Air refueling technique, which has been developing for a century, displays much more important strategic significance and wider application prospect on operation and material transport in nowadays. This article begins with an exploratory problem, and by use of a modeling method, it calculates the maximum operational distance of the main fighter under once-takeoff situation for flying tanker. The key point of this article lies in that we strive to design the optimum program to group the flying tanker fleet and then control the air refueling opportunities. Heuristic rules and mathematical tools are mainly used to achieve our target.

Abstract: This paper presents two surrogate-assisted optimization strategies for structural constrained multiobjective optimization. The optimization strategies are based on hybridization of multiobjective population-based incremental learning (MOPBIL) and radial-basis function (RBF) interpolation. The first strategy uses MOPBIL for generating training points while the second strategy uses a Latin hypercube sampling (LHS) technique. The design case study is the shape and sizing design of a torque arm structure. A design problem is set to minimize structural mass and displacement while constraints include stresses due to three different load cases. Structural analysis is carried out by means of a finite element approach. The design problem is then tackled by the proposed surrogate-assisted design strategies. Numerical results show that the use of MOPBIL for generating training points is superior to the use of LHS based on a hypervolume indicator and root mean square error (RMSE).

Abstract: Reinforcement and concrete can work together to bear load in reinforced concrete structures, one of the main reasons is the relatively prefect bond between reinforcement and concrete. When steel reinforcement corrodes, the bond strength decreases and leads to the degradation of the reinforced concrete members. This paper built a finite element model by selecting appropriate stress-strain relationship of concrete and reinforcement, bond-slip relationship between concrete and corroded steel bars. The flexural behavior of corroded reinforced concrete lock-walls was analyzed by nonlinear finite element method. The calculated results were compared with the test results to verify the reliability of the finite element model. Finally, the influence of corrosion level of steel reinforcement and concrete strength on the normal section bearing capacity of lock-walls were discussed.

Abstract: Chemical mechanical polishing (CMP) is one of the most effective technologies in modern ultra-precision processing. In this paper, we consider the slurry is ferromagnetic fluid and the influence of the centrifugal force, and then obtain the equations about this slurry in CMP. The slurry pressure distribution, resultant forces and moments acting on the wafer are calculated in typical conditions, and the affects of film thickness, roll and pitch angles are also calculated.

Abstract: There are some problems such as down hole torque & drag, casing wear and so on in extended reach drilling. Therefore, friction reducers are used widely to keep the drillstring away from the cased hole in extended reach drilling. Currently, the optimum placement of friction reducers is dependent on the drillstring deflection. Friction reducers are often connected to drill pipes by tool joints, which limits their optimum placement. In addition, the placement of the first reducer is often determined by drilling engineers’ experience. The effect of friction reducer on torque & drag is assessed in this paper and the optimum placement of friction reducer is obtained to minimize the torque & drag.

Abstract: In this paper, the first order time derivative of time fractional partial differential equations are replaced by the Caputo fractional order derivative. We derive the numerical solution of this equation using the Element-free Galerkin (EFG) method. In order to obtain the discrete equation, a various method is used and the essential boundary conditions are enforced by the penalty method. Numerical examples are presented and the results are in good agreement with exact solutions.

Abstract: In order to reduce grounded current and restrain arc-grounded over voltage during single-phase grounded faults in transmission line and realize fault-line selection, the neutral grounded mode with Peterson coil in parallel with big reactor is proposed in the paper. The simulation and comparative analysis of the performance of the 10 kV distribution grid systems in different neutral grounded modes have been done. The simulation results have shown that the neutral grounded mode via Peterson coil in parallel connection with big resistances can restrain the fault current effectively and it is the best mode.

Abstract: Location decision of Service Networks is important for an enterprise to dominate market and to improve service level. Characteristics and the decentralized control strategies of service network were discussed for the enterprise of Denso class. A 0-1 mixed integer programming model was established for location problem of spare parts centers and solved by ILOG along with sensitivity analysis. Furthermore, a dynamic programming model was established for location problem of sales model shop and calculated by a numerical listing method.

Abstract: A chaos particle swarm algorithm has been used to search for the optimal placement and size of the piezoelectric sensors and actuators (S/As) bonded on smart beams as well as the optimal feedback control gains. The criterion based on the minimization of stored and needed control energy was adopted for the optimization of the control system. The optimal distributions of the piezoelectric patches and feedback control gains based on specific controlled vibration modes have also been put forward. The results showed that the control effect could be significantly improved with optimized distribution of piezoelectric patches and gains.