Guo Dong Gao

Research on Crew Examination System Based on Web

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.

Surplus Fatigue Life Prediction of Diesel Engine Piston by the Equivalent J-Integral Approach

Three dimension temperature fields and stress-strain fields of the 6110-type diesel engine piston were analyzed by using the program ANSYS. The simulating tests of crack propagation under high temperature low cycle fatigue were carried out with pre-crack notched specimens. According to the theory of high temperature strength and fracture, the equivalent J-integral range ΔJf were induced to predict the surplus fatigue life of diesel engine piston. It was concluded that this approach is suitable and provides valuable reference for designers of diesel engine.

Study on Expanded Food Quality Improving Based on Six Sigma

This paper addresses on quality improvement of expanded food. The five stages of six sigma implementation process are applied to define the problem and set a target for improvement. Then possible causes to the quality problems in expanded food are investigated, and the capabilities of the measuring system are evaluated and improved. Based on the results, the experiment scheme is conducted to find and optimize the key factors. Improvement result shows that sigma level of production process increased to 4.6, which is beyond the expectation and can save the cost.

Research on Dissolve Oxygen Modeling Based on Neural Network

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.

Multiaxial Low Cycle Fatigue Life Prediction at 300 °C Using Equivalent Strain Appoach

The low cycle fatigue behavior was experimentally studied with the 3-dimension notched LD8 aluminum alloy specimens at 300°C. The 3- dimension stress-strain responses of specimens were calculated by means of the program ADINA. The multiaxial fatigue life prediction was carried out according to von Mises’s equivalent theory. The results from the prediction showed that the equivalent strain range can be served as the valid mechanics for predicting multiaxial high temperature and low cyclic fatigue life.

Thermal Fatigue and Fracture Mechanics Analysis of Aluminium Alloy

The in-phase and out-of-phase thermal fatigue of aluminum alloy were experimentally studied. The fatigue life was evaluated analytically by using the elastic-plastic fracture mechanics method (mainly J integral). The results of experiments and calculations showed that the life of out-of-phase fatigue was longer than that of in-phase fatigue within the same strain range. This is the same as the results of other materials such as medium and low carbon steel. On the other hand, the predicted life was consistent with experimental results. This suggests that J integral as a mechanics parameter for characterizing the thermal fatigue strength of aluminum alloy and the calculation method developed here is efficient. A parameter ΔW was proposed from energy aspect to characterize the capacity of crack propagation. The in-phase thermal fatigue life was the same as the out-of-phase thermal fatigue life for identical ΔW values.

Research on High Temperature Low Cycle Fatigue Crack Propagation of 2.25Cr-lMo Steel under Complex Stress State

The crack propagation law of 2.25Cr-1Mo steel with notched cylinder was researched under high temperature low cycle fatigue. The crack propagation life was viewed by fatigue experiment and the equivalent stress-strain on the crack tip was calculated by the ANSYS. The equivalent J-integral range which was computed by equivalent elastic and plastic strain ranges were employed to denote the fatigue crack propagation rate. The results showed that crack propagation law of this material under complex stress state can be characterized by equivalent J-integral ranges and the relation between da/dN and ΔJf is not influenced by the type of notch and the load strain range.

The Residual Life Estimation of Thermo-Mechanical Fatigue of Coke Tower

In this paper, the tests of the thermo-mechanical fatigue of the material, cut from a coke tower were performed. The tower made of 20G has been in service for 20 years. Then, we calculated the temperature and stress-strain. The results showed that the tower can be in service for another four years．

Research on Diesel Engine Fault Diagnosis Modeling Based on Elman Neural Network

In order to solve the fault diagnosis problem of diesel engine, Elman neural network (ENN) was applied to build a fault diagnosis model of diesel engine. The training algorithm is in introduced and at the same time, the process of diesel engine fault diagnosis is also expatiated. The diagnosis results indicate the reliability. So a contingent fault of diesel engine can be identified effectively.

Discussion of the Evaluating Criterion of 400°C Low Cycle Fatigue Life under Multiaxial Stress States

By the investigation of the 400°C low cycle fatigue behavior of 4 kinds of notched cylindrical specimens made 2.25Cr-1Mo stee1. The high temperature low cycle fatigue life was evaluated by the criterons of equivalent range. The results show that equivalent criterion for evaluating high temperature low cycle fatigue life has its experimental and theoretical foundation, but further investigation is still needed．