Applied Mechanics and Materials Vols. 55-57

Abstract: As the Internet developed, the problem of spam has become increasingly serious. Not only caused great distress to individuals, but also have a great business costs. With improvements in computing speed, neural network is becoming a very good tool for text classification. The purpose of this study is to conduct few experiments by using neural network approach for Chinese mails’ content. The result shows that neural network approach is effective for Chinese mails’ spam-identification and the adjustments of some parameters (the number of keywords, the number of nodes, and the number of categories) also increase the accurate rate, while reducing false positives.

Abstract: The traditional intelligent tutoring system as a web-based education tools used for adaptive learning can’t solve the encountered question in time while the student is learning with the absence of nature language understanding system. In this paper, a web-based intelligent tutoring system is firstly introduced to solve the encountered question in real time. Secondly, a concept model representing the concept connotation, the extension and the relation between them is presented to support the nature language understanding system in order to extract the question’s meaning. Furthermore, a knowledge representation of verb and noun in impersonal mature domain is involved. Thirdly, the semantic processing arithmetic of the verb phase is given. Finally, the result of experiment and application of arithmetic are shown.

Abstract: For the purpose of measuring physical property of a coating by non-destructive testing (NDT), acoustic characteristics of plasma-sprayed coating has been studied with the ultrasonic testing. The analytic equation of ultrasonic propagation in the coating based on spectrum analysis is deduced. A transfer function H(f) is established, which contains information on the acoustic properties of the coating. Not only the ultrasonic propagation velocity in the coating, but reflection coefficient, attenuation coefficient, density of the coating can be acquired. This method overcomes shortcomings that the acoustic parameters cannot be measured due to mutual superposition of multiple reflected waves at the same interface of the coating. Porosities of the coatings were tested by buoyancy method. It is found these parameters mentioned above can characterize physical property of the coating. The relationships between porosity and reflection coefficient, sound velocity, attenuation coefficient were investigated, respectively.The results show that reflection coefficient and attenuation coefficient increases with the increase of porosity of the coating. The sound velocity decreases with the increase of porosity. The method is suitable for the evaluation of the coating quality.

Abstract: This paper describes SBW system structure and principle, for different vehicle speed inputs and steering wheel angle step inputs, the simulation model run in Simulink, and obtain yaw rate response characteristics, so the steering system control requirements is proposed, establishes fuzzy logic control system. This control strategy can improve vehicle’s stability and fast respond characteristics. Simulations are carried out to gain a series of transmission ratio curves, show the validity of the proposed fuzzy logic control method.

Abstract: In the design of anchor bolt for slope reinforcement, determination of safety factor, anchorage length and free part length, choosing anchor-type were closely linked with the practical situation and experience of the designer. In this paper, in terms of above four aspects, some problems in the process of design have been discussed and corresponding solutions have also been put forward based on the codes and personal experience.

Abstract: This thesis put forward the treatment concept of “without Biomass Retention Sequential Batch Intensified Pretreatment (WSIP)” in leachate treatment, for sake of improving performance of nitrogen removal, optimizing excess water’s nutritional ratio and benefitting the follow-up aerobic biological treatment. Based on orthogonal experiment of WSIP Reactor’s leachate treatment performance, Conclusions can be drew: the removal performance of ammonia nitrogen and TN is higher of WSIP, in which short-cut nitrification and denitrification can be realized; HRT, DO and sequential period are remarkable factors of ammonia removal performance, TN removal performance and realization of short-cut nitrification and denitrification; In normal temperature, the most perfect functional parameter of WSIP Reactor is: HRT=4d, DO=0.75mg/L and sequential period is 6h.

Abstract: Shuanglong Lake is a shallow lake in the urban city, which has been a typical eutrophic lake. After synthesizing harnessing and control of outside pollutions, the endogenesis pollutions caused by polluted sediment may become the main nutritional burden of the lake. As for this, it is important to ascertain the releasing principles of nitrogen, which is the restrict nutrition factor of the lake. It can rehabilitate and maintain water quality of the Shuanglong lake, provide that the scientific foundation for harnessing the lake and protecting the environment. This paper had reported the investigation of nitrogen release from sediment of lake, and marked environmental factors include temperature,dissolvable oxygen, pH and hydrodynamic power, the releasing model can be obtained: r=12.931+0.103[T]－0.36[pH]－0.728[DO]+0.490[K], which can be applied to analyzing and estimating nitrogen released from polluted sediment, and control the release by raising the level of dissolvable oxygen in the lake.

Abstract: The caoting layer of each industry structure detected by ultrasonic testing is one commonly used thickness detection technique. This article proposed a method which used the extreme value of resonant amplitude spectrum to extract the thickness feature value, it can solve the feature value extraction difficult question which caused by two situations of time domain signals aliasing when the coating layer thickness is quite small and signals weak when signal attenuates seriously. And when the extreme point distributed unevenly in the actual detection, some measurements to improve the feature value extraction precision are proposed, which increased the detection signal-to-noise rated effectively. Take the structure of steel shell bonding rubber coating layer as the detection object, the detection experiment is studied to confirm its validity.

Abstract: The loading rate dependency of the hysteretic dynamics of Magnetorheological (MR) dampers is investigated in the current paper. The model is constructed on the basis of a phenomenological phase-transition theory. The hysteretic dynamics is treated as the responses of a nonlinear system upon external loadings. With appropriately chosen coefficients, the proposed model is able to capture the loading-rate dependency feature of the hysteretic dynamics. Comparisons between the numerical and experimental results are presented, and perfect agreements are obtained.

Abstract: The rectifier implements bidirectional power flow, sinusoidal current and unit power factor control in grid side. This paper describes the design and implementation of the current inner-loop and the voltage outer-loop based on space vector pulse width modulation (SVPWM). A control system based on the fuzzy self-tuning PID for three-phase rectifier is proposed in this paper. The new algorithm based on the fuzzy self-tuning PID can improve the performance of the system. Also, the overshoot of the voltage fluctuation is reduced. Simulation and experimentation results show that the validity of the proposed strategy.