Advanced Materials Research Vols. 989-994

Abstract: Aircraft manufacturing process normally requires very high precision assembly parts which are achieved in practice by a high-precision machining parts followed by a high coordination degree assembly process. The current practice in aircraft parts manufacturing process is that the manufacturing cycle is long, the rework rate is high and the manufacturing precision is difficult to improve. This can be sometimes infeasible or very costly. In this paper, we consider a fit degree calculation method to achieve precision aircraft parts with economical manufacturing processes. We consider an analytical approach to establish a physical process model to guide the design and machining process of assembly parts, which can assume the fit degree. The results show that the approach can obtain the nearly optimal process parameters at designated fit degree. At last, a case is developed to verify the proposed methods.

Abstract: A new self-adjusting PID controller based fuzzy inferences is proposed. Using fuzzy inferences method, the PID parameters can be adjusted adaptively online for the varying state of the system. This approach has more significant performance and robustness than conventional PID contorllers in any conditions. Traditional fuzzy control systems have difficulties for plants with great delay.A fuzzy PID system based on the Smith compensation theorem is proposed in the paper.It allows to change the transfer function of the plant.Simulation results are also given.

Abstract: The accurate diagnose of the timing of regeneration is the key factor of solving the problem that the filter body is damaged and the process of regeneration is uncomplete. The timing of regeneration judged by the exhaust back pressure is a type of widely accepted control method, the essence of which means to estimate whether the quantity of particle in the filter can fulfil the demand of regeneration or not. In the process of practical application, this kind of method is influenced by the engine conditions, therefore, we must monitor the engine at any moment by speed and load of signal acquisition.In this article,it summarizes two dimensional pulse spectrum" exhaust flow--pressure drop” through universal characteristics test. Meanwhile it conducts the temperature correction in order to simplify the complexity of the judge-ment of regeneration opportunity.

Abstract: Based on Hangzhou Zhijiang Bridge, FEA models of arch steel tower in construction and completed stages are established by using ANSYS software. Before closed and completed are considered to compute the dynamic characteristics of different structural system for arch steel tower. The results show that the wind-reduced vibration can be generated easily. It can cause some bad effect on the construction, equipments and the safety of staff. So, some proper measures should be adopted to decrease the wind-induced vibration of arch steel tower in construction and completed stages. So, some meaningful references are provided for the further research on control of wind-Induced vibration for arch steel tower.

Abstract: Perceptual load theory was considered to resolve the conflict between early and late selection models. We investigated whether perceptual load work well using IOR paradigm. The results showed that IOR disappeared in different level of perceptual load. The results indicated the onset time of IOR was influenced by perceptual load, indicating that perceptual load hinder the spatiotemporal correspondence between the cue and target integration.

Abstract: Brushless DC mo tor speed control system is a multivariate, strong coupling, non linear, time-varying complex system, but adopting traditional PID control method to carry ou t control is difficult to achieve good control effect A kind of PID controller with fuzzy algorithm setting on-line PID parameters automatically was designed and applied in brush less DC motor speed control system, using the voltage , speed and torque equation of brush less DC motor, according to the parameters of the mo tor, the controler adopts fuzzy theory to adjust the PID parameters, in order to obtain high-precision speed control Results of simulation experiment show that the fuzzy PID control method compared with normal PID control is with better control performance, non overshoot quick velocity response, higher control precision and good rubustness, which is insensitive to the parameter chattering and many disturbances.

Abstract: There are many factors that can affect network performance, such as delay, packet loss and capacity utilization. Vehicle handling directional stability has been more and more important, experiments for steering wheel corner step input response, steering oil tank response property, steady state turning and steering angle of all steering wheels were conducted in this paper, the experimental results show that multi-wheel steering system can fulfill its function very well and reach target angle, it provides a new method for researching for the vehicle handling directional stability.

Abstract: Because the traditional linear vectorization methods have some shortcomings including processing data slowly, being sensitive to noises and being easy to be distorted. Fuzzy rules and its inference mechanism are the assurance of achieving feature fusion. This paper has a design and analysis on the dual thumb pneumatic flexible robot hand base on the active flexible bending joints we have developed. The flexible joint is composed of four elongation artificial muscles with parallel arrangement. The robot hand has five multi-actuated fingers each with three flexible joints. To improve the flexibility and stability of grasp, the other four fingers are orthogonal and symmetrical except the middle finger, which forms the dual thumb oriented grasp model. Furthermore, we study on the position and posture of fingers applying the parameterized homogeneous transformation to the large deformation and nonlinear problems of flexible joint.

Abstract: Pipeline in the entire oil and gas transportation industry play an important role and in the soil is corroded in order to produce the stress corrosion crack. The topic analyzes and calculates cracked pipeline with finite element method by use of ANSYS software mainly, and provides the theory basis for safety evaluation of pipeline.

Abstract: To study the correlation effect of multiple defects of metal magnetic memory (MMM) testing technology, the stress-magnetization effect on 20# steel specimen with dual defects under exercise of the geomagnetic field and tensile load is simulated by using the finite element analysis (FEA) software ANSYS. With the stimulation, the magnetic flux leakage (MFL) distribution with different measured paths and different lift-off values of the surface specimen is given. The results showed that the correlation effect of dual defects produce more severe stress concentration phenomenon on the associated region of ferromagnetic specimen, and had no obvious effect on the edge of ferromagnetic materials; Gradient value K of the normal component H(z) of leakage magnetic field in the specimen, as a parameter evaluation of stress concentration in the specimen, has high reliability in areas without correlation effect, but it has no credibility in areas under dual defect correlation effect. Moreover, this article also discusses the influence of measured path and the lift-off value on magnetic memory signals.