Applied Mechanics and Materials Vol. 160

Abstract: We introduce type-2 fuzzy reasoning to models of cellular automata, and combine type-2 fuzzy logic and classic cellular automata model to establish a new model of evolution reasoning, cellular automata model based on type-2 fuzzy logic. The key parts of cellular automata are transition functions and cell states. We fuzzify the transition functions of cellular automata into type-2 fuzzy rules, and cell states into type-2 fuzzy states too. Thus, we establish an improved cellular automata model based on type-2 fuzzy logic.

Abstract: This paper proposed flexible torque control with the current oriented in core, and high performance dynamic positioning technology of electric actuator based on Switched Reluctance Motor (SRM) was achieved. Meanwhile the system structure of intelligent electric actuator was introduced, in which SRM is the implementation component. From the perspective of software, the current directional control, flexible starting and braking, and high-frequency algorithmic process were elaborated. Moreover taking over torque protection as illustration, the fault diagnosis algorithm was analyzed. The test data and waveform showed that all kinds of electric actuator performance have reached international advanced level.

Abstract: The characteristics of interface affect the behaviors of a whole structure considerably. The interface along with its neighbouring region is defined as the interface region and the equivalent parameters in the interface region used in the analysis are obtained by both theoretical and experimental methods. A structure including interface was taken as an example, whose calculated model was made by the interface stress element method. The comparison between the results of calculation and experiment is presented to illustrate the feasibility and effectiveness of the proposed approach.

Abstract: A performance degradation assessment method is proposed based on probability statistic of common turn-on state of power MOSFET circuit in this paper. Threshold shift transient characteristics of MOSFET are studied and the performance degradation behavior of a bridge power MOSFET circuit is simulated. Threshold voltage degradation of a power MOSFET circuit caused by half bridge arm is observed and the probability of a period transient common turn-on state is calculated to evaluate the degree. The result can be used to evaluate the performance degradation trend and can also provide data support for predicting the degradation degree before circuit failed.

Abstract: The optimization effects of the particle swarm optimization (PSO) on the parameters of Van Genuchten (VG) equation for the soil water characteristic curve were investigated. The results indicated that the VG parameters determined by the PSO were very close to those of experiments with a very high accuracy. The PSO was proven to be used as an optimization method for estimating VG parameters for the soil water characteristic curve. The PSO had the higher parameter precision than the damped least squares method and the nonlinear simplex method. The particle swarm optimization was improved and its convergence accuracy was higher than that of constriction factor particle swarm optimization (CFPSO) and PSO of Filedsend.

Abstract: The FBG sensor technologies used for real-time monitoring of the mechanical vibration have attracted more and more concerns from both academic and industrial domains. In practical applications, the vibration frequency of the equipments generally reach up to a few hundred to several thousand Hz, however, the existing FBG demodulator is incompetent to meet the actual requirements of vibration monitoring in terms of demodulation speed and algorithm structures. To solve this problem while achieving a higher accuracy at a relatively lower computation cost, a novel adaptive semi-peak-seek algorithm based on state machine is proposed, which can be divided into three parts including data collection, data analysis and data verification. The experiment result shows that for the demodulation speed of 2 KHz, we can reach a demodulation accuracy of 1pm and a static noise within ±2pm. On the basis of a long term test, the stability error that less than 2pm and the system dynamic range of 0~ -30db are concluded, and the measurement error with the optical power attenuation is limited to 4pm. Thus, the proposed algorithm is capable to meet the requirements of high-speed demodulation devices in terms of speed, precision, stability and anti-interference properties.

Abstract: Research on nonlinear dynamic response of passive vibration isolator, which was excited by foundation vibration and isolated by viscoelastic material was done. Nonlinear stiffness was expressed by the cubic polynomial function of deformation and nonlinear damping was characterized by viscoelastic fractional derivative operator. Then the fractional derivative nonlinear dynamic equation of passive vibration isolator was established. The dynamic response characteristics were analyzed by harmonic balance method and the frequency response equation and amplitude-frequency curve were obtained, and furthermore, the influence of nonlinearity on system was analyzed. Finally, the stability and the stable interval of the periodic solution were argued by the Floquet theory. The result s indicates that the proposed equation can precisely describe the dynamic characteristics of viscoelastic vibration isolator. The ignorance of nonlinearity of stiffness and damping will result in obvious error. The proposed method provides theoretic reference for design of viscoelastic isolator and the evaluation of its effect.

Abstract: This paper proposes a modified auditory feature extraction algorithm based on perceptual linear predictive analysis which is more suitable for automatic recognition of aircraft noise. In this algorithm, a different distribution of filter-bank is introduced in order to fit the physical characteristic of aircraft noise and the result shows that the modified method indeed performs better. The effect of Gammatone filter in improving the robustness of recognition algorithm is also demonstrated in the experiment.

Abstract: In order to find out the Chinese students’ abilities in the choice of English expression vocabulary,the relationship between the abilities and the quality of English expression and whether the quality. influenced by the abilities,choosing the undergraduate students of non-English major as the test objects, the author has done some investigaton and test experments,which include the cloze,the collocation of noun and verb noun and so on.Through this test,the choosing knowledge of English words of the tested is far less than their total vocabulary.Moreover, these students use more expression of their mother language instead of that of English,which is not acceptable by the people whose native language is English.Sometimes, the vocabulary collocation is easy to be replaced, however,there also exist some words and expression very difficult to be replaced. Therefore, we can draw the conclusion that English words and expression of quality is in the presence of great relevance, and students' word choosing abilities would affect the quality of the English expression to a large extent.

Abstract: OFDM has a high peak to average power ratio ( PAPR ), when the signal PAPR over power amplifier ( HPA ) linear dynamic range, will introduce nonlinear distortion, affecting the signal transmission performance. In order to overcome the defects, OFDM need to adopt the corresponding PAPR suppression technique, the signal amplitude changes of power amplifiers in the allowable range. This paper presents a new partial transmit sequence algorithm ( PTS ), double phase sequence reversal threshold algorithm, and simulation results show that the new algorithm on the PAPR suppression effectiveness, search depth of T, the inhibition on PAPR performance.