Advanced Materials Research Vols. 204-210

Abstract: Magnetic flux leakage (MFL) is a non-destructive testing method used to inspect ferrous materials. However, there are a variety of factors that can affect the MFL inspection tool’s ability to detect and characterize anomalies. MFL signals obtained during the inspection of pipes have been simulated using 3D finite element analysis (FEA) and the effects of magnetic concentrator on MFL signals are investigated. Measurements of the leakage flux with various defect depths or widths indicate that the axial component of MFL are improved by magnetic concentrator with the result that significant advantages could be obtained in defect detection schemes, in that the signal to noise ratio (SNR) of MFL signals can be improved by magnetic concentrator.

Abstract: On the basis of analyzing the character of target detecting and tracking algorithm, referencing the successful application of embedded system in the fields of electronics，signal processing and computer technology, combining target detecting and tracking and embedded technology, an embedded target tracking system is proposed which based on s3c24lO on which running clipping Linux system, and a tracking example of flying target is given. The whole system reaches the target of small size and good real-time. It’s a useful attempt to realize the small and intelligent of target tracking system.

Abstract: This paper is concerned with the problem of automatic inspection of hot-rolled plate surface using computer vision. An automated visual inspection system has been developed to take images of external hot-rolled plate surfaces and an intelligent surface defect detection paradigm based on gradient spectrum technique is presented. Gradient spectrum characterizes the spatial configuration of local image texture and is robust against any monotonic transformation of the gray scale. Texture features based on gradient spectrum are extracted from ROI in hot-rolled plate surface images and integrated into a feature vector which uniquely differentiates the abnormal regions from normal surface. Classification accuracies using the gradient spectrum and gradient-based method are compared. The results indicate that gradient spectrum performs well in classifying the samples with the lowest classification error.

Abstract: The batch reactor has strong nonlinearity and hysteresis, the conventional control method is hard to meet the control requirements. According to the batch processes temperature control, this thesis proposed an intelligent control scheme. Combined neural networks with fuzzy logic control, searching and optimized parameters of fuzzy neural network by using Genetic Algorithm (GA), displayed the design method and optimization steps, and the simulation results verify the control scheme which proposed is feasible and effective.

Abstract: Pressure reducing and control is the key technology in hydrogen transmission for fuel cell cars. A double step system with two direct reducing valves had been provided in this paper. These two valves depressurize the tank hydrogen pressure from 35MPa or 70MPa to 5MPa at first, then to 0.16MPa, adapting the fuel cell demands. The valves static analysis show the flow rate and pressure characteristics are rigid. The dynamic simulation display the valves quick response and pressure control accuracy are satisfied fuel cell working condition. The analogue experiments verify the system reducing performance and the double step reducing system is applicable to fuel cell cars hydrogen transmission.

Abstract: A robust adaptive terminal sliding mode control(SMC) algorithm is developed for the trajectory control of the rigid manipulators. The upper bounds of uncertain nonlinearities and unknown internal parameters of rigid manipulators are estimated through an adaptive mechanism and used for the main part of the controller, and additional part based terminal sliding mode technique is used to compensate the bounded parameters estimation error and achieve robustness of the control system. Continuous sliding mode controller is developed by replacing the signum functions with saturation functions to reduce the chattering that traditional sliding mode have common. The proposed design method is evaluated on a 2-DOF robot manipulator to demonstrate the effectiveness of the theory.

Abstract: Thermal analysis of aircraft hydraulic systems is an important subject for system’s design. Heat generation and dissipation of aircraft hydraulic systems had been discussed in this article. Heat exchange was calculated based on heat transfer theory. A formula of temperature variation was derived based on the assumption that oil flow in the hydraulic system was one-dimension unsteady flow. Take the hydraulic system of a certain commercial aircraft for example, a model was established to simulate the temperature change of aircraft hydraulic systems based on AMESim. The simulation results are in consistent with test data.

Abstract: This study aims to create a college English coursebook corpus of coursebooks widely used in universities in China to form the basis of an analysis. The comparative study based on Cunningsworth [1] coursebook evaluation theory, in view of several checklist items and the adoption of quantitative and qualitative approach, involves: vocabulary size, the coverage of vocabulary and collocations and the readability of texts. The statistics of evaluation show that there is a gap between requirements and coursebooks. It is hoped that the indices examined in this study would be of some help for English teachers to take vocabulary and collocation size and text readability into account in teaching practice and possibly for administrators to adjust curriculum design and for editors or publishers to revise existing coursebooks.

Abstract: The complexity of modern equipment is higher than before, thus it cannot meet the need of speedy fault diagnosis to use single diagnosis pattern. According to these troubles, a fault tree was introduced to analyze fault information of gear. Fault tree analysis is a logical and diagrammatic method to evaluate the probability of an accident resulting from sequences and combinations of faults and failure events. In conventional fault tree analysis, probabilities and consequences are treated as exact values. In many engineering applications, however, it is difficult to evaluate the probabilities and consequences from past experiences, so a fuzzy set defined in probability is proposed. The principle of fuzzy diagnosis is taken as basics and symptom sets and faults sets are extracted through fault tree analysis. Experiments show this method is effective for fault diagnosis of gear.

Abstract: A new process of low temperature triple-effect distillation desalination is designed. Firstly, the appropriate effect number is determined. The total heat transfer coefficients and the heat loads of each evaporator are calculated. When the pressure differences between near effects are equal to △P, the freshwater outputs and the heat transfer coefficients of every effect would be increased as △P improved; if △P is too low, the seawater un-evaporated in the last evaporator would be difficult to flow into the next one. By analysis, the appropriate value of △P is 0.005 MPa. If the seawater flowing into the first effect is preheated by the heat source flow outpouring the unit, the total heat utilization rate and the freshwater output would be enhanced.