Applied Mechanics and Materials Vols. 239-240

Abstract: Memristor is a kind of circuit element with nano scale, its appearance may radically change the traditional circuit. Recently, dopant drift model is a hot issue in research works connected to memristor. However, because of lack of transparency in the process of simulation, simulation method on dopant drift model of memristor needs to be strengthened. Dopant drift model was analyzed, circuit characteristics and relations between different circuit variables were studied. Based on those works above, a kind of numerical simulation method was designed to simulate and validate the memristor model. Simulation results show that the method designed accurately expresses conducting behaviour of memristor physical model, which provides a new feasible way for simulations of memristor model.

Abstract: In this paper, an effective digital signal processing method based on the merger of the increasing and decreasing time-series sequences (MIDS) is introduced. On the basis of the merging of EEG signals, a new IED (Interictal Epileptiform Discharges) detection method is proposed. The first step of this new method is to establish a database by selecting peaked wave fragments. Then, the similarity between pending test fragment and peaked wave samples in the database is calculated. When the maximum similarity is greater than a certain threshold, the fragment is judged to be a peaked wave. Finally, the wave type i.e. spike wave, sharp wave, spike-and-slow wave or sharp-and-slow wave can be determined by whether there is a subsequent slow wave or not. Continuous sharp wave can be viewed as spike rhythm. In this research, 92 IED fragments from 4 suspected epilepsy patients are collected to establish the sample database. The proposed method was tested on EEG recordings from other 31 suspected patients. The results show that 98.11% of the IED fragments marked by doctors were detected. The experimental results show that this method performs well at IED detection in the clinical EEG data. The similarity is measured based on the comparison between fragments of different time length and can be viewed as a novel approach for the detection of typical EEG waveform. This research draws two conclusions: (1) the waveform of individual peaked wave is stable during 24-hour EEG recording process; (2) the database containing a small number peaked wave samples can be used to detect IED fragments.

Abstract: In this paper we proposed an effective but simple table recognition algorithm in the OCR field. First a binary image template is built for the tables to be recognized, which consists of all the lines describing the table cells we are interested in. Then the images to be analyzed are thresholded and deskewed. Vertical and horizontal lines are extracted from the preprocessed image to form a table “scene”. Finally the binary image template is aligned to the table “scene” by minimizing their Hausdorff distance. From the alignment the image regions of interest corresponding to the table cells are extracted for further recognition task. Experiments show that the proposed method with the template can cope with many low quality images and achieve good recognition results.

Abstract: Aiming at the result of Mean-Shift tracking method is not satisfactory when color of the target is similar to the back ground or another similar object is close to the target, a real- time target tracking method combined with Mean shift and color co-occurrence histograms (CCH) was proposed in this paper. The method used CCH to represent target model of the Mean-Shift. And then the Mean-Shift was used to locate the target position. Moreover, the studied model updating strategy based on multi-scale CCH and the similarity measure of Bhattacharyya value is constructed in the method. Experiments in the complex environment were done. The results show that the proposed method has more accurate target locating and better robustness than the traditional Mean-Shift.

Abstract: Moving targets passive tracking by single moving observer is a difficult problem. A new location method based on measurement data fusion is proposed in this paper. Firstly, the adaptive passive tracking initiation algorithm is introduced. Secondly, a new data association algorithm is proposed, based on the data fusion of multiple measurements, the decision of synthetic data association is made. Finally, with the help of computer simulations, the proposed algorithms are proven to be correct and effective.

Abstract: The decomposition result of empirical mode decomposition (EMD) may be incorrect if some frequency components of original signal are close to each other. To avoid illusive result and get an exact one suiting for analysis, a harmonic wavelet filtering can be used before the EMD is performed. In the course of application of harmonic wavelet filtering, data was decomposed subsection overlapped to overcome the edge effect of usual digital filter that is caused by data truncation. The experiments showed its feasibility and validity in application of real-time processing.

Abstract: In this paper, a robust image watermarking method in two-dimensional space/spatial-frequency distributions domain is proposed which is robust against geometric distortion. This watermarking is detected by a linear frequency change. The one-dimensional chirplet transformation and radon transformation are used to detect the watermark. The chirp signals are used as watermarks and this type of signals is resistant to all stationary filtering methods and exhibits geometrical symmetry. In the two-dimensional Radon-Wigner transformation domain, the chirp signals used as watermarks change only its position in space/spatial-frequency distribution, after applying linear geometrical attack, such as scale rotation and cropping. But the two-dimensional Radon-Wigner transformation needs too much difficult computing. So the image is put into a series of 1D signal by choosing scalable local time windows. The watermarks are embedded in the 1D Chirplet-Radon transformation domains. The watermark thus generated is invisible and performs well in StirMark test. Compared with other watermarking algorithms, this algorithm is more robust, especially against geometric distortion, while having excellent frequency properties.

Abstract: Digital subtraction angiograph system is widely used in the angiograph examinations. Its primitive images cannot be used directly by doctors because of their considerable noises. The human’s brain blood vessels usually squirm slowly, so there is much more correlativity between two adjacent frame images, and they can be described as low frequency signals. A low-pass self-adaptive recursive filter is designed to eliminate the noises of DSA images, of which the filtering factor attenuates exponentially with the differences of two adjacent frames. A practical DSA image processing system is designed with a Field Programmable Gate Array, including the image sampler, analog to digital converter, filter, and display device. The system has been successfully applied in hospitals, and it can meet the clinical needs.

Abstract: Visual comfort is an important factor that should be considered in the production of stereoscopic HDTV programs. This paper reports the result of recent researches on the relationship between visual comfort and the depth-movements, and analyses the experimental results in terms of the principle of vergence-accommodation conflict. The analysis result indicates that the depth-movements will cause viewers’ visual discomfort and fatigue, especially when the depth-movement range is large and the speed is fast. The research result is of significance to reach a balance between the realistic stereoscopic visual effects and visual comfort.

Abstract: A new multivariate threshold function for image denoising in the shearlet transfrom is proposed. The new threshod exploits a multivariate normal inverse gaussian probability density function to model neighboring shearlet coefficients. Under this prior, a multivariate Bayesian shearlet estimator is derived by using the maximum a posteriori rule. Experimental results show that the new method achieves state-of-art performance in terms of peak signal-to-noise ratio (PSNR), structural similarity (SSIM) index and visual quality than existing shearlet-based image denoising methods.