Applied Mechanics and Materials Vols. 130-134

Abstract: Intermittent intensity clutter in wind profiling radar severely interferes with the identification and spectrum estimation of atmospheric echo signals. In order to remove such clutter, a method based on Fractional Fourier transform (FrFT) is presented. The proposed method makes use of energy concentration property of intermittent clutter in fractional Fourier frequency domain. Not only the intermittent intensity clutter can be removed in the fractional Fourier frequency domain by using a narrow band-stop filter, but also the atmospheric signal in the time domain can be reconstructed after removing the clutter. Computer simulations have verified the effectiveness of the method.

Abstract: Anomalous traffic often has a significant impact on network activities and lead to the severe damage to our networks because they usually are involved with network faults and network attacks. How to detect effectively network traffic anomalies is a challenge for network operators and researchers. This paper proposes a novel method for detecting traffic anomalies in a network, based on continuous wavelet transform. Firstly, continuous wavelet transforms are performed for network traffic in several scales. We then use multi-scale analysis theory to extract traffic characteristics. And these characteristics in different scales are further analyzed and an appropriate detection threshold can be obtained. Consequently, we can make the exact anomaly detection. Simulation results show that our approach is effective and feasible.

Abstract: In this paper, image enhancement algorithm is applied to multi-phase CT system imaging. Aiming at artifact imaging of multiphase flow CT system image reconstruction, this paper uses image enhancement algorithm to enhance the reconstructed image. The simulation results prove that with a small amount projection angle data about reconstruction it can also get clear images by using image enhancement algorithm processing and also remove artifacts for reconstructed image. It is efficient to shorten the multi-phase CT system image reconstruction data collection time, and benefit to analysis multi-phase transient flow pattern.

Abstract: In this paper, an image processing and recognition system of the coal and gangue has been studied. We adopt digital video processing technology of high performance---DaVinci technology to design the system, which is made up by the chip DM6437 and some peripheral auxiliary equipment. The system takes advantage of the high performance of the chip to process the real-time image collected by the CCD camera. The system uses optimized image processing and recognition algorithms, and makes the recognition of coal and gangue by the different characteristic of their histograms. In the system, the histogram and processing image of coal and gangue can be displayed on the monitor.

Abstract: A method to inspect fabric defects based on compactly supported biorthogonal wavelet transform is presented. Firstly, the fabric images are captured by CCD camera. Then fabric defects are detected by means of the strategy of compactly supported biorthogonal wavelet transform. The phase shifts with the orthogonal and the biorthogonal wavelet techniques are compared aiming at the warp-lacking. It is shown that the phase shifts of orthogonal wavelet behave as different degrees, the ones of biorthogonal wavelet are zero. Finally, employing the biorthogonal wavelet method to inspect fabric defects, including warp-lacking, weft-lacking, oil stains, and holes, is given by experiments, in which the results are satisfied.

Abstract: This paper makes analyses on the basic regulation characteristics of Static Var Generator (SVG). From the perspective of AC and DC’s instantaneous power balance, the approximate equivalent model of small signal perturbations method is established for analysing the system stability. The stability and dynamic characteristics research is performed accordingly, which provide a basis for parameters design of SVG.

Abstract: According to analyze the characteristic of the operational progress of short-range air defense, Petri net (PN) is applied to describe the operational progress, which includes the radar reconnaissance, the operational plans decision-making, and the operational effectiveness evaluation. Based on study of the component model of short-range air defense, the corresponding PN model is established, and the time delay is also analyzed. The results indicate that PN is an effective tool for establishing dynamic system simulation model of complex discrete event.

Abstract: ALOHA algorithm can’t prevent collision much effectively, the process of anti-collision is longer while the amount of tags plunged collision is numerous, and sometimes the problem about estimating mistakenly arises. Binary search algorithm, which identification efficiency is higher, the problem about estimating mistakenly can’t arise, but its delay tima is more longer, security is short. The amelioration algorithm, return binary search algorithm can identify tag more effectively and rapidly, identifying time and the amount of tags is the relation of line form. The significance is very momentous that vast goods are identified, traced and managed by this amelioration algorithm.

Abstract: On the basis of summing up the Frequency-Domain Blind Deconvolution (FDBD), a method combine Complex-Domain FastICA algorithm and amplitude correlation was proposed to extract the typical defect signals from mechanical equipment. The application in combined failure rolling bearing acceleration signals demonstrate that, comparing with the existing Time-Domain Blind Signal Processing methods, FDBD has more advantages and better prospects in mechanical fault detection.

Abstract: The stabilized platform servo system ensures the carrier communicating with satellites stably while in motion. The key to this system is to isolate disturbance coursed by the moving of the carrier and maintain the stability of antenna directivity. This paper has compared PID algorithm and I-PD algorithm, and designed a control scheme for the stabilized platform using the combination of speed-change integral I-PD algorithm and feed-forward control. The results of the simulation and actual testing indicate that the design this paper presents has a strong suppression to disturbance and meets the precision requirements of the mobile satellite communication system.