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Search Results: 1 - 10 of 7538 matches for " Liangtian Wan "
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Fast Estimation of Frequency and 2-D DOAs for Cylindrical Conformal Array Antenna Using State-Space and Propagator Method
Weijian Si;Liangtian Wan;Lutao Liu;Zuoxi Tian
PIER , 2013, DOI: 10.2528/PIER12121114
Abstract: The pattern of each element in conformal array has a different direction for the curvature of conformal carrier, which results in polarization diversity of conformal array antenna. Polarization parameters of incident signals are considered in snapshot data model in order to describe the polarization diversity of conformal array antenna. It is required that the polarization parameters and direction of arrival (DOA) of incident signals are estimated together. An integrated frequency and DOA estimation method is proposed in this paper for cylindrical conformal array antenna. The frequency estimation of signal source is obtained by constructing state-space matrix. Through well-designed configuration of elements on cylindrical carriers along with estimation of signal parameters via propagator method (PM), the decoupling scheme for DOA and polarization parameters is implemented. A novel parameter pairing method for frequency and DOA of multiple sources utilizing the interpolation technique is given, based on which the fast frequency-DOA estimation algorithm is developed. Effectiveness of the proposed method is demonstrated by simulation experimental results.
High Accuracy 2D-DOA Estimation for Conformal Array Using PARAFAC
Liangtian Wan,Weijian Si,Lutao Liu,Zuoxi Tian,Naixing Feng
International Journal of Antennas and Propagation , 2014, DOI: 10.1155/2014/394707
Abstract: Due to the polarization diversity (PD) of element patterns caused by the varying curvature of the conformal carrier, the conventional direction-of-arrival (DOA) estimation algorithms could not be applied to the conformal array. In order to describe the PD of conformal array, the polarization parameter is considered in the snapshot data model. The paramount difficulty for DOA estimation is the coupling between the angle information and polarization parameter. Based on the characteristic of the cylindrical conformal array, the decoupling between the polarization parameter and DOA can be realized with a specially designed array structure. 2D-DOA estimation of the cylindrical conformal array is accomplished via parallel factor analysis (PARAFAC) theory. To avoid parameter pairing problem, the algorithm forms a PARAFAC model of the covariance matrices in the covariance domain. The proposed algorithm can also be generalized to other conformal array structures and nonuniform noise scenario. Cramer-Rao bound (CRB) is derived and simulation results with the cylindrical conformal array are presented to verify the performance of the proposed algorithm. 1. Introduction Conformal arrays mounted on curved surfaces are commonly applied in various areas such as radar, sonar, and wireless communication [1]. The conformal antennas could fulfill specific aerodynamics, space-saving, elimination of random-induced bore-sight error, potential increase in available aperture, and so on [2, 3]. Most researches focus on the design of antenna configuration [4–6], the transform between the local and global coordinate [7–10], and the pattern synthesis of conformal array [11–15]. The conventional direction-of-arrival (DOA) estimation algorithms, for example, the multiple signal classification (MUSIC) [16] and the estimation of signal parameters via rotational invariance techniques (ESPRIT) [17], are not applicable due to the varying curvature of the conformal array. The “shadow effect” of the conformal array is caused by the metallic shelter, leading to the condition that not all elements have the ability to receive the signal. As a result of the incomplete steering vector, common DOA estimation algorithms cannot be used for conformal array. Recently, DOA estimation algorithms for conformal array have been proposed for high resolution [18–22]. With the help of fourth-order cumulant and ESPRIT algorithm, a blind DOA estimation algorithm is proposed in [18]. Based on the mathematical technique of geometric algebra, 2D-DOA and polarization parameter estimations are completed by
A Low Energy Consumption DOA Estimation Approach for Conformal Array in Ultra-Wideband
Liangtian Wan,Lutao Liu,Guangjie Han,Joel J. P. C. Rodrigues
Future Internet , 2013, DOI: 10.3390/fi5040611
Abstract: Most direction-of-arrival (DOA) estimation approaches for conformal array suffer from high computational complexity, which cause high energy loss for the direction finding system. Thus, a low energy consumption DOA estimation algorithm for conformal array antenna is proposed in this paper. The arbitrary baseline direction finding algorithm is extended to estimate DOA for a conformal array in ultra-wideband. The rotation comparison method is adopted to solve the ambiguity of direction finding. The virtual baseline approach is used to construct the virtual elements. Theoretically, the virtual elements can be extended in the space flexibility. Four elements (both actual and virtual elements) can be used to obtain a group of solutions. The space angle estimation can be obtained by using sub-array divided technique and matrix inversion method. The stability of the proposed algorithm can be guaranteed by averaging the angles obtained by different sub-arrays. Finally, the simulation results verify the effectiveness of the proposed method with high DOA estimation accuracy and relatively low computational complexity.
Wavelet Frame Based Image Restoration Using Sparsity, Nonlocal and Support Prior of Frame Coefficients
Liangtian He,Yilun Wang
Computer Science , 2015,
Abstract: The wavelet frame systems have been widely investigated and applied for image restoration and many other image processing problems over the past decades, attributing to their good capability of sparsely approximating piece-wise smooth functions such as images. Most wavelet frame based models exploit the $l_1$ norm of frame coefficients for a sparsity constraint in the past. The authors in \cite{ZhangY2013, Dong2013} proposed an $l_0$ minimization model, where the $l_0$ norm of wavelet frame coefficients is penalized instead, and have demonstrated that significant improvements can be achieved compared to the commonly used $l_1$ minimization model. Very recently, the authors in \cite{Chen2015} proposed $l_0$-$l_2$ minimization model, where the nonlocal prior of frame coefficients is incorporated. This model proved to outperform the single $l_0$ minimization based model in terms of better recovered image quality. In this paper, we propose a truncated $l_0$-$l_2$ minimization model which combines sparsity, nonlocal and support prior of the frame coefficients. The extensive experiments have shown that the recovery results from the proposed regularization method performs better than existing state-of-the-art wavelet frame based methods, in terms of edge enhancement and texture preserving performance.
Linear Spatial Pyramid Matching Using Non-convex and non-negative Sparse Coding for Image Classification
Chengqiang Bao,Liangtian He,Yilun Wang
Computer Science , 2015,
Abstract: Recently sparse coding have been highly successful in image classification mainly due to its capability of incorporating the sparsity of image representation. In this paper, we propose an improved sparse coding model based on linear spatial pyramid matching(SPM) and Scale Invariant Feature Transform (SIFT ) descriptors. The novelty is the simultaneous non-convex and non-negative characters added to the sparse coding model. Our numerical experiments show that the improved approach using non-convex and non-negative sparse coding is superior than the original ScSPM[1] on several typical databases.
Analysis on the Mindbugs in Information Technology Service Management Project Implementation  [PDF]
Jiangping Wan, Dan Wan
Technology and Investment (TI) , 2011, DOI: 10.4236/ti.2011.23019
Abstract: J.N.Warfield identified and classified the mindbugs (cognitive barriers), and put forward the process-based work program of complexity, and argued that the complexity could be managed through design. The eleven kinds of common mindbugs are figured out among the twenty five kinds of mindbugs with questionnaire. The relationship between the six root risk factors of implementation of the information technology service management (ITSM) project and these common mindbugs are also identified. It is found that the influence of mindbugs of habit is most serious in the ITSM project because the implementation of ITSM project would change the original work habits and methods of people. Finally, some recommendations are put forward to mitigate the root risk factors.
Case Study on M Company Best Practice with Global IT Management  [PDF]
Jiangping Wan, Xiaoyao Wan
Technology and Investment (TI) , 2012, DOI: 10.4236/ti.2012.33019
Abstract: The propose of research is to help those global companies to improve their IT service management (ITSM) more effectively. The ITSM of M company is analyzed with global IT management model, which contains 12 structuring elements, and the structuring elements model and their best practices are established in the IT service operation and maintenance process in the views of centers of excellence, shared services and value managers. Both the 12 structuring elements and 5 M company’s best practices of ITSM are rated with both critical success factors and analytic hierarchy process. The best practices are in the following: good relationship with customers (0.279), seamless and efficient department cooperation (0.231), team proficient in business and enterprise resource planning professional knowledge (0.226), high-quality library of knowledge management (0.176) and educational training (0.088).
Research on Software Production Support Structure  [PDF]
Jiangping WAN
Journal of Software Engineering and Applications (JSEA) , 2009, DOI: 10.4236/jsea.2009.23025
Abstract: Firstly, it is found that process design is necessary for software process improvement after analyzing its complexity. Then, research methods and concepts framework are put forward, and the research content is also provided. The find-ings of research, including propositions of complexity of software process, the work program of complexity of software process improvement, software enterprise model and software production support structure are clarified. Finally, the demonstration, including mindbugs (cognitive barriers) in software process and the knowledge integration support structure of quality software production, is illustrated with case study. It is concluded that the research is useful for both software production and knowledge economy in the future.
A Novel Approach for English Phonetic Alphabet in Wireless Communication  [PDF]
Yuhui Wan
Communications and Network (CN) , 2013, DOI: 10.4236/cn.2013.53032

In this paper a novel approach of English Phonetic Alphabet applicable to Chinese people was introduced. This novel English Phonetic Alphabet was specially designed in line with the characteristics of radio telephone frequency communication in China and pronunciation habit and English level of most of Chinese people; which not only can improve the voice quality and guarantee accurate transfer of information, but also is integrated with the pronunciation characteristics of Chinese language, with the functions to avoid the uncommon, easily confusing and difficultly pronouncing English words, and efficiently improve the wireless communication efficiency.

On Xi Jinping’s Thought Regarding People’s Livelihood  [PDF]
Wan Zhiang
Chinese Studies (ChnStd) , 2015, DOI: 10.4236/chnstd.2015.42008
Abstract: Xi Jinping’s thought regarding people’s livelihood reflects a new progress made in that of CPC’s in the period of completing building a moderately prosperous society in all respects in China. The basic characteristic of Xi’s thought regarding people’s livelihood show in three aspects. It focuses on the overall layout of the construction of society to improve people’s livelihood, it bases on the construction of the rule of law and anti-corruption system to strengthen the people’s livelihood, and it holds justice for the people to promote social justice. The maximum theoretical contribution of the Xi Jinping’s people’s livelihood thought is to discuss the problem of party spirit and people from the social and power structure, then fulfill the best combination of the fundamental interests of the party and the masses of the people.
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