Papers by Author: Wen Xiao Zhang

Abstract: The quality improving of locomotive maintenance service is studied based on Six Sigma. The maintenance service progress has been optimized by DMAIC mode. First of all, the quality problems have been proposed. Then, the factors which impact on quality of after-sales service are found by QC tools. Secondly, the main problems in the progress would be controlled conveniently. Finally, the improved maintenance services process is developed correspondingly. In order to ensure the quality of the maintenance in the delivery period, some measures are taken such as adjusting the allocation time in the repair process, developing a strict examination system. The result shows that the maintenance efficiency and customer satisfaction has been improved significantly.

Abstract: Energy saving is the best way to energy exploitation and environment protection, especially in the case of the low carbon economy. In this paper, a hybrid approach combining particle swarm optimization (PSO) and genetic algorithms (GA) is developed for optimization design of marine waste heat recovery system. Based on exergy analysis method, the waste heat utilization degree of the marine waste heat recovery system is discussed. Considering the superheated steam temperature, evaporation temperature, economizer inlet temperature, water supply temperature and condensation temperature, a mathematical model is constructed in which the exergy efficiency of marine waste heat recovery system is taken as the objective function for optimization design of marine waste heat recovery system. The mutation operator of GA is introduced to the PSO to solve the mathematical model of marine waste heat recovery system for the diversity of particles. The effectiveness of the approach is illustrated by an optimization example.

Abstract: With the rapid development of computer technology and Internet, all kinds of distant educations based on Internet have been coming out constantly. To reduce the cost of exam and alleviate the burden of teachers, the crew examination system was designed and implemented. This system is an online examination system which integrates computer network technology, database technology and ASP technology. The B/S model was adopted in this system and using ASP visit ODBC accesses database. This system includes two functions: examination system and management system. Test library management, random questions, online testing, automatic scoring, scores query and other functions were achieved. Crew examination system realizes the change from traditional test’s way to the way based on Internet.

Abstract: Aiming at the complexity of mechanical devices and the polytrope of operating conditions for marine propulsion plant, the modeling and simulation of propeller and dull system are investigated based on MATLAB/Simulink. The simulation model of propeller and dull system is constructed in which the Chebyshev fit expression across four quadrants is given for the propeller. So it becomes practical to express static and dynamic properties of propeller and dull system. A luxury cruises fitted on two engines and two fixed pitch propellers is considered to perform simulation tests. The actual navigation conditions of marine propulsion plant, including starting, parking and reversing etc, are taken into account. The simulation results analysis illustrates the correctness and validity of modeling and simulation for propeller and dull system. Thus provides a new method for the optimization and design of marine propulsion plant.

Abstract: A new topology optimization model with holes’ geometric constraints for continuum structure is presented. It is solved by an evolutionary optimization method based on interval relaxation, in which the problem is divided into two subproblems of topology optimization process and size/shape optimization process. The optimal topology of structure can be found gradually by introducing interval relaxation factor to adjust holes’ size constraints, delete noneffective holes and by generating new holes based on the sensitivity analysis of objective function. Interior penalty-function method is employed as an optimization technique for the size/shape optimization of the structure corresponding to the topology. When the holes’ size bounds are the actual values, the optimal solution is the smallest objective function structure in the various topologies. Thus realizes the holes’ geometric size and location design, topology design and layout design together. The optimization results of example shows the method proposed is of good effectiveness and engineering applicability.

Abstract: The structure, characteristics and principles of BP neural network model are described in this paper. First, three impact factors of the dissolved oxygen are selected as the sample input of network, and then the parameters of BP neural network are selected, such as network structure, learning algorithm, output layer transfer function, learning rate and so on. Finally, the BP neural network model is established and trained, in order to approach compensate the effects of improves non-linearity. The simulation results show that BP neural network is practical and dependable in the field of dissolved oxygen modeling and has nice applied prospect.