Applied Mechanics and Materials Vols. 263-266

Abstract: In order to supply an effective and reliable tool for the Psychology research in quantity, a multi-parameters psychophysiological feedback analysis system was designed. It can measure several physiological parameters closely related to psychological factors and can realize automatically controlling test gain using a DAC feedback adaptive circuit. Communication protocol is used to increase reliability of data communication and LMS algorithm was used in the system for noise elimination, real-time and data accuracy can be guaranteed. After the debug and verified, multi-parameter system can collect real-time and stable physiological parameters with a higher precision, it provides a feasible monitoring program for psychological assessment.

Abstract: The small step frequency conversion module is an important unit for a type of simulation equipment. This paper tries to design a kind of small step frequency conversion module which solves the design problem of frequency converter in simulation equipment. The study of small step frequency conversion technology is the main part in this paper. It is using two-stage PLL and DDS which sets frequency and controls step, to meet the design need.

Abstract: With a uniform linear antenna array, a new direction-of-arrival (DOA) estimation method is proposed for wideband coherent signals in the presence of unknown correlated noise but with structured covariance matrix. Based on this proposed structure, i.e. Hermitian Toeplitz, a spatial differencing operation that exploits this symmetry is applied to remove the effect of the unknown noise and a new matrix is constructed accordingly at each frequency bin. Following this step, a focusing operation is performed to give the corresponding aligned covariance matrix. Finally, an eigenstructure-based DOA estimation method is applied. The validity of the method is supported by numerical simulation under various conditions.

Abstract: This paper focuses on the problem of H∞ filter design for continuous Takagi-Sugeno (T-S) fuzzy systems with an interval time-varying delay in the state. Based on the free weighting matrix method combined with a matrix decoupling approach, some new sufficient results are proposed in forms of linear matrix inequalities (LMIs), which can achieve much less conservative feasibility conditions. Finally, the effectiveness of the proposed method is demonstrated ba an example.

Abstract: Contourlet transform is superior to wavelet transform in representing texture information and sparser in describing geometric structures in digital images, but lack of robust character of shift invariance. Non-subsampled contourlet transform (NSCT) alleviates this shortcoming hence more suitable for texture and has been studied for image de-noising, enhancement, and retrieval situations. Focus on improving the retrieval rates of existing contourlet transforms retrieval systems, a new texture retrieval algorithm was proposed. In the algorithm, texture information was represented by four statistical estimators, namely, L2-energy, kurtosis, standard deviation and L1-energy of each sub-band coefficients in NSCT domain. Experimental results show that the new algorithm can make a higher retrieval rate than the combination of standard deviation and energy which is most commonly used today.

Abstract: Regularization is a method for improving the solution of ill-posed problems with neural networks. In regularization, a penalty term, called regularizer or prior, is added to the performance function. The penalty term is weighted with a regularization parameter, , to balance the trade-off between model bias and model variance. We have compared the performances of different priors on several different time series data sets, to see if there is any consistent difference in performance between priors. The conclusions from our study on real world time series data has weight decay the best performance and the Bishop smoother is the worst choice.

Abstract: Recurrent events gap time is the time difference between two adjacent failures of recurrent events. In this paper, an additive-accelerated hazard ratio model is presented for multiple type recurrent events gap time data, and the estimation methods of unknown parameter and non-parameter function is given. Moreover, the asymptotic properties of estimators are proved.

Abstract: A state time delay always exists in practical systems. Analysis of the delay phenomenon in a continuous time domain is sophisticated. It is appropriate to obtain its corresponding discrete time model for implementation via a digital computer. A new method for the discretization of nonlinear systems is proposed in this paper. This method is applied to the sampled data representation of a nonlinear system with constant state time delay. The proposed scheme provides a finite dimensional representation for nonlinear systems with state time delay enabling existing nonlinear controller design techniques to be applied to them. A performance of the proposed method is evaluated using a nonlinear system with state time delay.

Abstract: Surface electromyography (sEMG) signals, a non-invasive bioelectric signal, can be used for the rehabilitation and control of artificial extremities. But this signal is so weak that the electrical voltages ranging from -5 to +5 mv. In order to eliminate the 50Hz noise included in sEMG and hold details of the signal, IIR50HZ notch filter and FIR 50Hz notch filter are design. The compared simulation results show that the application of FIR 50Hz is better than IIR 50Hz in sEMG patter recognition system.

Abstract: In this paper, a method for convolutive blind separation for communication sources is introduced. The method works in time-domain, and it is based on the recently very successful algorithm EFICA for Independent Component Analysis, which is an enhanced version of more famous FastICA. In addition, an automatic method of wavelet de-noising processing is proposed, using the 'mini-maxi' soft-threshold model, wavelet decomposition is performed at level 5 for the noisy separated communication signal, it can improve the performance of BSS system, and this is confirmed in the experiment for communication signals with same carrier frequencies and modulation.