Local information enhanced LBP

Based on the observation that there exists multiple information in a pixel neighbor, such as distance sum and gray difference sum, local information enhanced LBP （local binary pattern） approach, i.e. LE-LBP, is presented. Geometric information of the pixel neighborhood is used to compute minimum distance sum. Gray variation information is used to compute gray difference sum. Then, both the minimum distance sum and the gray difference sum are used to build a feature space. Feature spectrum of the image is computed on the feature space. Histogram computed from the feature spectrum is used to characterize the image. Compared with LBP, rotation invariant LBP, uniform LBP and LBP with local contrast, it is found that the feature spectrum image from LE-LBP contains more details, however, the feature vector is more discriminative. The retrieval precision of the system using LE-LBP is 91.8% when recall is 10% for bus images.     

Multi-resolution EMD and classscatter matrix extracting of tank sound

The acoustic vibration signal of tank is disassembled into the sum of intrinsic mode function(IMF) by multi-resolution empirical mode decomposition(EMD) method.The instantaneous frequency is obtained,and feature transformation matrix is figured out by class scatter matrix.Multi-dimensional scale energy vector is mapped into low-dimensional eigenvector,and classification extraction is realized.This method sufficiently separates of different sound target features.The test result indicates that it is effective.     

Contour tracking using weighted structure tensor based variational level set

A novel contour tracking method using weighted structure tensor based variational level set is proposed in this paper.The image is first converted to weighted structure tensor field by extracting apositive definite symmetric covariance matrix for each pixel.Then,a level set method is employed to represent object contour implicitly which separates the image domain into two areas each modeled by tensor field based Gaussian mixture model separately.By solving agradient flow equation of energy functional with respect to the level set,the object contour will converge to its real profile in the newly arrived frame.Experimental results on several video sequences demonstrate the better performance of our method than the other two contour tracking algorithms.     

Study on singularity analysis with differential transform method for 3-RRUR parallel robot based on Jacobian matrix

Parallel robot is used in many different fields nowadays,but the singularity of 3-RRUR parallel robot is more complicated,so a method to analyze the singularity of the 3-RRUR parallel robot is very necessary.First,the Jacobian matrix was built based on the differential transform method through the transfer matrixes between the poles.The connection between the position parameters and singularity condition was built through the analysis of the Jacobian matrix.Second,the effect on the singularity from the position parameters was analyzed,and then the singularity condition was confirmed.The effect on the singularity condition from position parameters was displayed by the curved surface charts to provide a basic method for the designing of the parallel robot.With this method,the singularity condition could be got when the length of each link is firmed,so it can be judged that if a group of parameters are appropriate or not,and the method also provides warrant for workspace and path planning of the parallel robot.     

3D surface reconstruction based on binocular vision using structured light

A 3D surface reconstruction method using a binocular stereo vision technology and a coded structured light, which combines a gray code with phase-shift has been studied. The accuracy of the 3D surface reconstruction mainly depends on the decoding of gray code views and phase-shift views. In order to find the boundary accurately, gray code patterns and their inverses are projected onto a human eye plaster model. The period dislocation between the gray code views and the phase-shift views in the course of decoding has been analyzed and a new method has been proposed to solve it. The splicing method is based on feature points. The result of the 3D surface reconstruction shows the accuracy and reliability of our method.     

Outdoor relative radiometric calibration method using gray scale targets

The radiometric calibration of remote sensors is a basis and prerequisite of information quantification in remote sensing. This paper proposes a method for outdoor relative radiometric calibration using gray scale targets. In this method, the idea of two substitutions is adopted. Sunlight is used to replace the integrating sphere light source, and gray scale targets are used to re-place the diffuser. In this way, images at different radiance levels obtained outdoors can calculate the relative radiometric cali-bration coefficients using the least square method. The characteristics of this method are as follows. Firstly, compared with la-boratory calibration, it greatly reduces the complexity of the calibration method and the test cost. Secondly, compared with the existing outdoor relative radiometric calibration of a single radiance level, it uses test images of different radiance levels to re-duce errors. Thirdly, it is easy to operate with fewer environmental requirements, has obvious advantages in the rapid calibra-tion of airborne remote sensors before or after flight and is practical in engineering. This paper theoretically and experimental-ly proves the feasibility of this method. Calibration experiments were conducted on the wide-view multispectral imager (WVMI) using this method, and the precision of this method was evaluated by analyzing the corrected images of large uniform targets on ground. The experiment results have demonstrated that the new method is effective and its precision meets the re-quirement of the absolute radiometric calibration.     

Fast motion estimation algorithm of video stabilization system

A real-time electronic image stabilization motion estimation method based on fast sub- block gray projection algorithm is proposed. In the method, each image is divided into a number of sub-blocks, and sub-blocks are sifted with their gray gradients. After removing sub-blocks whose gray gradients are lower than the given threshold, the calculation amount of projection is reduced and the motion estimation accuracy is improved. Then gray projection is done in each remained sub- block, and global motion vector of the image is calculated according to the local motion vectors of sub-blocks and the affine motion model. The drawbacks as the local motions reducing the global mo- tion estimation accuracy and traditional gray projection algorithm could not deal with rotation are re- solved well by this algorithm. The experiment results show that the algorithm is more accurate and efficient than the gray projection algorithm.     

Fast ray tracing method in 3-D structure and its proof of positive definiteness

Based on Fermat’s principle, two-point ray tracing method was studied in three-dimensional structure. By means of first order Taylor’s incomplete series expansion (i.e. no expansion to the length of the ray), a symmetry block tridiagonal matrix equation set was deduced. Further, the positive definiteness of coefficient matrix was discussed, and the positive definiteness was accurately proved in a mathematical way. It assured that the algorithm was well-posed. Associated with iterative method, the solution to ray tracing can be got through step-by-step linearized iteration of the nonlinear problem. An algorithm of the whole path iterative ray tracing method in three-dimensional velocity structure was obtained. This method shows a clear and simple as well as explicit computation formula, which makes ray tracing computation easily applicable in practice. The correction vector is obtained through finding the solution to the positive definite block tridiagonal equation set, which ensures the method is robust convergence. This study offers a new kind of feasible and efficient ray tracing method for three dimensional seismic migration and tomography. Meanwhile, it also provides the prerequisite guarantee to design a fast algorithm.     

边界元法在叶轮机械气动反问题中的应用

The boundary element method is a new type of numerical method. The main advantage of the method is the reduction by one of the dimensionality of the problem under consideration. Thus considerable savings in the data input and computer CPU time required to run it can be achieved.     

Analysis of Texture of Froth Image in Coal Flotation

Froth image features of coal flotation have been extracted and studied by neighboring grey level dependence matrix, spatial grey level dependence matrix and grey level histogram. In this paper, a basic algorithm of unsupervised learning pattern classification is presented, and coal flotation froth images are elassified by means of self-organizing map (SOM). By extracting features from 51 flotation froth images with laboratory column, four types of froth images are classified. The correct rate of SOM cluster is satisfactory,And a good relationship of froth type with average ash content is also observed.     

Bi-prism-based single-lens three dimensional digital image correlation system with a long working distance: Methodology and application in extreme high temperature deformation test

As a novel three dimensional digital image correlation(3 D DIC) method, the bi-prism-based single lens(BSL) 3 D DIC method has been proposed and developed in recent years. Making use of a bi-prism, this method is able to perform a 3 D DIC measurement using only a single camera. Thus, the integration level of a BSL 3 D DIC system could be much higher than that of the double-camera3 D DIC system. In this paper, using a small-angle bi-prism and a camera with a longer focal length, a special BSL 3 D DIC system with a long working distance is designed for measurements in extreme environments. The principle of the system is first studied,and practical methods are then proposed for the system set-up and the determination of system parameters. Then, feasibility of the measurement system is verified by out-of-plane rigid-body translation tests. Finally, the BSL 3 D DIC system is proven to be capable of combining with a high-temperature testing instrument to perform deformation tests in a high-temperature environment of up to 1500°C.     

Novel channel estimation model for OFDM in time-varying channel

A new channel estimation method for orthogonal frequency division multiplexing( OFDM)system with large subcarriers and serious intercarrier interference( ICI) is proposed. The channel frequency-domain( CFD) matrix of each delay path is factorized to the product of a diagonal delay matrix and a circular ICI matrix in this model. To reduce the coefficient number,the circular ICI matrix is squeezed by using Hamming-window as the reshaping pulse in the transmitter. Meanwhile,the elements of the diagonal delay matrix are approximated with a discrete prolate spheroidal basis expansion model( DPS-BEM). A least-square( LS) estimator is used to estimate the reduced channel coefficients. The proposed method is theoretically derived and simulated. The simulation results indicate that the model has good performance and is appropriate for various channel environments. The method also has low complexity and good spectral efficiency.     

Dominant point detecting based non-uniform B-spline approximation for grain contour

Three-dimension reconstruction from serial sections has been used in the last decade to obtain information concerning three-dimensional microstructural ge-ometry. One of the crucial steps of three-dimension reconstruction is getting compact and fairing grain contours. Based on the achievement of closed raw con-tours of ceramic composite grains by using wavelet and level set, an adaptive method is adopted for the polygonal approximation of the digitized raw contours. Instead of setting a fixed length of support region in advance, the novel method computes the suitable length of support region for each point to find the best es-timated curvature. The dominant points are identified as the points with local maximum estimated curvatures. Periodic closed B-spline approximation is used to find the most compact B-spline grain boundary contours within the given tolerance. A flexible distance selection approach is adopted to obtain the common knot vector of serial contours consisting of less knots that contain enough degrees of freedom to guarantee the existence of a B-spline curve interpolating each contour. Finally, a B-spline surface interpolating the serial contours is generated via B-spline surface skinning.     

边界元法在叶轮机械叶栅流动计算中的应用

0 Introduction The boundary element method is a new and effective numerical technique. The main advantage of this method is the reduction by one of dimensionality of the problem under consideration. Thus considerable savings in the data input and computer CPU time required to run it can be achieved. Therefore, the method has been used widely in many engineering problems, However, it is scarcely used in     

Design of hydraulic shift mechanism for AMT vehicles based on the collaborative optimization method

Based on multidisciplinary design optimization (MDO), a new design method is put forward for hydraulic shift mechanism of heavy-duty vehicle automated manual transmission (AMT). Taking a shift cylinder for example, the collaborative optimization (CO) method for the design problem of a cylinder is devided into one system level design optimization problem and three subsystem level design optimization problems. The system level is an economic model and the subsystem level is mechanics, kinetics, and a reliability model. Application of the multidisciplinary design optimization software iSIGHT modeling and solving, optimal solution of the shifting cylinder CO model is obtained. According to the optimal solution, oil cylinders are machined out and installed on the gearbox of an AMT system for the bench cycle shift test. The results show that the output force and action speed of the optimized mechanism can meet requirements very well. In addition, the optimized mechanism has a better performance compared to the structure of the traditional design method, which indicates that the CO method can optimize the design of hydraulic transmission.     

Reliability evaluation on CNC lathes based on the modified L-M method

Equivalent ways commonly used in engineering works are not effective to estimate the reliability of tandem system based on L-M method.One modified L-M method is an important means to estimate the reliability of CNC lathes.A method of using two named confidence limits for the estimation is put forward.Fitting results of the sub-systems of CNC machine tools are estimated.And the scattered level of confidence limits facing the reliability matrix of sub-systems can be clearly seen.     

Weighted sum based method on the optimal weights for weapon evaluation

In order to solve instability problem of calculation precision resulting from the selection of each target weight in evaluating weapon systems,a weighted sum based method is proposed. Specifically, the subjective weights depending on experts ’ experience are substituted by the optimal weights. The optimal weights are acquired through constructing a mathematical programming model based on subjective weights and objective weights. The method of solving subjective weights is the same as before,and the objective weights were solved by means of grey theory. The case analysis shows that the method of improved weighted sum can improve the evaluation precision up to more than 5%,and minimize the instability of calculation precision resulting from only using subjective weights. The method that the optimal weights substituted the subjective weights is brought forward in improving evaluation precision for the first time. The ideas of the optimal weights and the proposed method are described and analyzed.     

Study on Numerical Comparison Method of Four-bar Straight-line Guidance Mechanism

In order to solve four-bar straight-line guidance mechanism synthesis problem for the arbitrarily given straight-line＇s ＂angle requirement＂ and ＂point-position requirement＂, a numerical comparison synthesis method for single and double straight-line guidance mechanism is presented, which is convenient to realize by computer program. The basic idea of this method is： to select a four-bar linkage whose relative bar length of crank is 1 as a basic four-bar linkage. Then the other three relative bars＇ length is changed, and a lot of basic four-bar linkage can be obtained. There are many single and double ball-points of each basic four-bar linkage. With the motion of a basic four-bar linkage, there is straight-line segment of each Ball-point＇ s path. The data of these basic four-bar linkages is saved to a database. When designing a four-bar straight-line guidance mechanism, the design data is compared with the data in database and a satisfactory four-bar linkage can be obtained. The method effectively solves the straight-line guidance mechanism synthesis problem.     

Six-point synthetic method to estimate fundamental matrix

A new method, named the 6-point synthetic method, is developed to estimate fundamental matrix ( F matrix) based on two uncalibrated cameras and an 8-parameter model. First two parameters are found in the model by the new constraint developed, and they are the affine coordinates of an epipole. Then the rest 6 parameters are obtained by solving a set of linear equations. Finally, this method is tested by some real images and shows the advantages of obvious geometrical meaning, fewer matching pairs needed for calculation and high accuracy F matrix.     

DOA estimation of coexisted noncoherent and coherent signals via sparse representation of cleaned array covariance matrix

A new direction finding method is presented to deal with coexisted noncoherent and coherent signals without smoothing operation. First the direction-of-arrival (DOA) estimation task is herein reformulated as a sparse reconstruction problem of the cleaned array covariance matrix, which is processed to eliminate the affection of the noise. Then by using the block of matrices, the information of DOAs which we pursuit are implied in the sparse coefficient matrix. Finally, the sparse reconstruction problem is solved by the improved M-FOCUSS method, which is applied to the situation of block of matrices. This method outperforms its data domain counterpart in terms of noise suppression, and has a better performance in DOA estimation than the customary spatial smoothing technique. Simulation results verify the efficacy of the proposed method.