Applied Mechanics and Materials Vols. 556-562

Abstract: In this paper we present a fast indoor stereo matching algorithm based on canny edge detection and line moments. We first detect image edge by using Canny operator, then find the target objects according line moments, the feature points of the objects’ contours are extracted. Finally, matching the pixel in stereo image pair according the angle vector. The algorithm effectively reduces the computational complexity, computational cost is decreased greatly. The experimental results show that the algorithm is possible and valid.

Abstract: As a new type of guidance technology, the strapdown imaging guidance technology, which helps improve the system reliability and reduce costs efficiently, has been paid great attention and developed quickly. However, the detecting information of strapdown seeker can’t be used to proportional navigation directly because it is coupled with missile attitude. A method to estimate the inertial Line-of-Sight (LOS) rate of strapdown imaging seeker based on Cubature Kalman filter (CKF) and Tracking-Differentiator (TD) was presented. As there were high nonlinearity in both state and measurement equations and more serious non-Gaussian noise in the measurements, the Extended Kalman filter (EKF) could not completely meet the requirements of filtering. Compared with EKF and Unscented Particle filter (UKF), CKF was a congruent method for states estimating in the conditions of nonlinearity and non-Gaussian noise. CKF was applied to estimate the LOS rate of strapdown imaging seeker. Because measurement noise of missile attitude will be reflected in estimation result, TD was used to decrease noise of the missile attitude measurements for improving the estimation precision. Monte Carlo simulation results show that the proposed method can improve the precision of guidance.

Abstract: The properties of fractional Fourier transform of anomalous vortex beams are studied. A new type of analytical expression of fractional Fourier transform for anomolous vortex beams is obtained. The properties of anomolous vortex beams on different fractional Fourier transform planes with different parameters are illustrated. The results show that the anomolous vortex beams always has a doughnut profile, the distribution of intensity on different fractional Fourier transform planes highly depends on the fractional order and the beam parameters, such as the beam order and the topological charge.

Abstract: The density of supercritical CO₂ is calculated by Peng-Robinson state equation. Through comparing with the experimental values, it is founded that the calculation results are very similar with experimental values, which indicates that Peng-Rob inson state equation is an ideal method for forecasting the density of supercritical CO₂.

Abstract: A model for the deformation of fluid particle under the action of velocity gradient tensor is proposed in this article. In this contribution, the control volume/surface is geometrically simplified into micro-ellipse. By using a series of changes of basis and eigenvalue decomposition, a numerical method for the deformation of an elliptic fluid particle is then demonstrated. Finally, this method is applied in two different problems involving smoothed particle hydrodynamics (SPH) simulation and a passive scalar turbulence case.

Abstract: The distortion of particles distribution is a defect that usually leads to numerical instability in the traditional SPH method. In this contribution, we introduce a novel local regrouping method to solve this problem. The basic idea is to keep the particles undeformed by regrouping, dividing or combining the deformed particles. We succeed to simulate the Taylor-Green vortex in 2D with this method, and demonstrate the effectiveness of this method.

Abstract: A maintenance policy model based on time-variant reliability is put forward upon those mechanical systems which can carry on multiple maintenance in the whole life period, and the recurrence relations of the preventive maintenance intervals and reliability benefits is established. Two kinds of devices, one device’s mean time to failure complies with exponential distribution and another device’s mean time to failure meets the Weibull distribution, are taken as examples to get the approximate function expressions of the system's maintainability parameters of these devices through the curve fitting for data, analyze the system’s maintainability parameters and get the equipment’s maintenance policy model based on time-variant reliability. Examples verify the feasibility of the model.

Abstract: Vector quantization technology is an efficient and competitive method for data compression, but it is not easy to be implemented because of the comparatively high computation complexity it requires during the coding and decoding process. This paper presents a method of Dual Population Ant Colony Algorithm Codeword Quick Search (DPACAS), exploiting the mechanism of ant trace the optimal path through the pheromones remained, and the behavior pattern of making objects together by picking up and putting down them. It uses Parallel Ant Colony algorithm to sufficiently accelerate the convergence of the ant colony. When the scale of the codebook becomes larger, by setting parameters reasonably and exchanging the pheromones between two species, it broadens the search space, reduces the search time and improves the algorithmic global convergence effectively.

Abstract: Non-stationary noise and strong background noise is difficult to extract the actual audio signal problem, an adaptive spectral reduction algorithm is proposed. A dynamic threshold algorithm is devised, iterative update mechanism and the specific implementation are contrived in the clean speech spectrum and noise spectrum estimating. Simulation experiments show that the algorithm can effectively de-noising filter, significantly improve the intelligibility of speech recognition system performance and read, and the method is robust in different noise environments and SNR. The algorithm complexity low, the computational cost is small, real-time, easy to implement, so that the effectiveness and real-time dual meet.

Abstract: The three-dimensional (3D) geological modeling technique which is considered as an important skill of fine reservoir description has been gaining more and more attention. On one hand, it can efficiently promote the transformation of reservoir description from two-dimensional (2D) to 3D, and from qualification to quantification as well. The 3D reservoir geological model can be used as basic geological knowledge in terms of adjusting well patterns and indicating remaining oil distribution, through reflecting the spatial distribution characteristics and the variation of the reservoir physical property. On the other hand, the 3D modeling technique specializes in the representation of local micro features in comparison of regular ways. This article aims at subtly describing the structural modeling of Changling gas field of Changling fault depression. The result of this case study shows that the establishment of structural model is consistent with the understanding of fault development which was proved during the process of producing gas, thus the structural model has high reliability. Therefore, the structural model is of great guiding significance for the design of new well and the well patter optimization.