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Search Results: 1 - 10 of 120538 matches for " Xudong Wang "
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Joint Angle and Frequency Estimation Using Multiple-Delay Output Based on ESPRIT
Xudong Wang
EURASIP Journal on Advances in Signal Processing , 2010,
Abstract: This paper presents a novel ESPRIT algorithm-based joint angle and frequency estimation using multiple-delay output (MDJAFE). The algorithm can estimate the joint angles and frequencies, since the use of multiple output makes the estimation accuracy greatly improved when compared with a conventional algorithm. The useful behavior of the proposed algorithm is verified by simulations.
Joint Angle and Frequency Estimation Using Multiple-Delay Output Based on ESPRIT
Wang Xudong
EURASIP Journal on Advances in Signal Processing , 2010, DOI: 10.1155/2010/358659
Application of Ant Colony Algorithm to the Analysis of Common Mode EMI Model of DC Motor  [PDF]
Jinfeng Liu, Xudong Wang, Jiang Nan
Energy and Power Engineering (EPE) , 2011, DOI: 10.4236/epe.2011.32013
Abstract: The Electromagnetic Compatibility (EMC) of direct current (DC) motor windings is a system model which is used to reflect the functional characters of the system in the whole EMC specified frequency (150 KHz ~ 30 MHz). For most motor designing process, it is always used to evaluate the inductance of windings in lower or working frequency; however, when analyzing the conducted interference, it is necessary to take some pa-rameters in high frequency into account in building up the EMC model, such as the noticeable capacitance distributed among the windings or between windings and shells. Past research neglected the common-mode current generated by the high frequency interference within motor bearings coupled with shells, since the parasitic capacitance of rotor core comes from armature windings supplied sufficient paths. In EMC model-ing process for DC motor problem, first, test the impedance of windings by experiments; then, generate the equivalent circuit with overall parameters. At present, it is a difficulty that how to choose the parameters. Most researchers preferred to adopt analytical calculation results, however, it could not reflect the essence of the model since it requires many simplification. Based on this point, this paper adopted ant colony algorithm (ACA) with positive feedback to intelligently search and globally optimize the parameters of equivalent cir-cuit. Simulation result showed that the impedance of equivalent circuit calculated by this algorithm was the same as experimental result in the whole EMC frequency. In order to further confirm the validity of ACA, PSPICE circuit simulation was implemented to simulate the spectrum of common mode Electromagnetic Interference (EMI) of equivalent circuit. The simulation result accords well with the experiment result re-ceived by EMI receiver. So it sufficiently demonstrated correctness of ACA in the analysis of high frequency equivalent circuit.
Effect of blocking Rac1 expression in cholangiocarcinoma QBC939 cells
Xudong, Liu;Guangyi, Wang;
Brazilian Journal of Medical and Biological Research , 2011, DOI: 10.1590/S0100-879X2011007500057
Abstract: cholangiocarcinomas (ccs) are malignant tumors that originate from epithelial cells lining the biliary tree and gallbladder. ras correlative c3 creotoxin substrate 1 (rac1), a small guanosine triphosphatase, is a critical mediator of various aspects of endothelial cell functions. the objective of the present investigation was to study the effect of blocking rac1 expression in ccs. seventy-four extrahepatic cc (ecc) specimens and matched adjacent normal mucosa were obtained from the department of pathology, inner mongolia medicine hospital, between 2007 and 2009. our results showed that the expression of rac1 was significantly higher (53.12%) in tumor tissues than in normal tissues. western blotting data indicated a significant reduction in rac1-mirna cell protein levels. rac1-mirna cell growth rate was significantly different at 24, 48, and 72 h after transfection. flow cytometry analysis showed that rac1-mirna cells undergo apoptosis more effectively than control qbc939 cells. blocking rac1 expression by rnai effectively inhibits the growth of ccs. mirna silencing of the rac1 gene suppresses proliferation and induces apoptosis of qbc939 cells. these results suggest that rac1 may be a new gene therapy target for cc. blocking rac1 expression in cc cells induces apoptosis of these tumor cells and may thus represent a new therapeutic approach.
Mechanisms of particle vertical diffusion in sediment-laden flows
Guangqian Wang,Xudong Fu
Chinese Science Bulletin , 2004, DOI: 10.1007/BF03184041
Abstract: Diffusion coefficient of natural sediments and effects of lift force and gradient in particle velocity fluctuations were investigated through using a closed kinetic model. Comparison against experimental data of Einstein & Chien (1955) validated the model. The diffusion coefficient εyy of medium and large sediments distinctly exceeds fluid eddy viscosityv f t , while εyy of fine sediments approximately equalsv f t . In the measured region of0.03
Existence of solutions for discontinuous p(x)-Laplacian problems with critical exponents
Xudong Shang,Zhigang Wang
Electronic Journal of Differential Equations , 2012,
Abstract: In this article, we study the existence of solutions to the problem $$displaylines{ -hbox{div}(| abla u|^{p(x)-2} abla u) =lambda |u|^{p^{*}(x)-2}u + f(u)quad x in Omega ,cr u = 0 quad x in partialOmega, }$$ where $Omega$ is a smooth bounded domain in ${mathbb{R}}^{N}$, $p(x)$ is a continuous function with $1
An Extended Image Hashing Concept: Content-Based Fingerprinting Using FJLT
Lv Xudong,Wang ZJane
EURASIP Journal on Information Security , 2009,
Abstract: Dimension reduction techniques, such as singular value decomposition (SVD) and nonnegative matrix factorization (NMF), have been successfully applied in image hashing by retaining the essential features of the original image matrix. However, a concern of great importance in image hashing is that no single solution is optimal and robust against all types of attacks. The contribution of this paper is threefold. First, we introduce a recently proposed dimension reduction technique, referred as Fast Johnson-Lindenstrauss Transform (FJLT), and propose the use of FJLT for image hashing. FJLT shares the low distortion characteristics of a random projection, but requires much lower computational complexity. Secondly, we incorporate Fourier-Mellin transform into FJLT hashing to improve its performance under rotation attacks. Thirdly, we propose a new concept, namely, content-based fingerprint, as an extension of image hashing by combining different hashes. Such a combined approach is capable of tackling all types of attacks and thus can yield a better overall performance in multimedia identification. To demonstrate the superior performance of the proposed schemes, receiver operating characteristics analysis over a large image database and a large class of distortions is performed and compared with the state-of-the-art image hashing using NMF.
Information-Theoretic Study on Routing Path Selection in Two-Way Relay Networks
Shanshan Wu,Xudong Wang
Mathematics , 2012,
Abstract: Two-way relaying is a promising technique to improve network throughput. However, how to apply it to a wireless network remains an unresolved issue. Particularly, challenges lie in the joint design between the physical layer and the routing protocol. Applying an existing routing protocol to a two-way relay network can easily compromise the advantages of two-way relaying. Considering routing path selection and two-way relaying together can be formulated as a network optimization problem, but it is usually NP-hard. In this paper, we take a different approach to study routing path selection for two-way relay networks. Instead of solving the joint optimization problem, we study the fundamental characteristics of a routing path consisting of multihop two-way relaying nodes. Information theoretical analysis is carried out to derive bandwidth efficiency and energy efficiency of a routing path in a two-way relay network. Such analysis provides a framework of routing path selection by considering bandwidth efficiency, energy efficiency and latency subject to physical layer constraints such as the transmission rate, transmission power, path loss exponent, path length, and the number of relays. This framework provides insightful guidelines on routing protocol design of a two-way relay network. Our analytical framework and insights are illustrated by extensive numerical results.
A++ Random Access for Two-way Relaying in Wireless Networks
Wenguang Mao,Xudong Wang
Mathematics , 2012,
Abstract: Two-way relaying can significantly improve performance of next generation wireless networks. However, due to its dependence on multi-node cooperation and transmission coordination, applying this technique to a wireless network in an effective and scalable manner poses a challenging problem. To tackle this problem without relying on complicated scheduling or network optimization algorithms, we propose a scalable random access scheme that takes measures in both the physical layer and the medium access control layer. Specifically, we propose a two-way relaying technique that supports fully asynchronous transmission and is modulation-independent. It also assumes no priori knowledge of channel conditions. On the top of this new physical layer technique, a random access MAC protocol is designed to dynamically form two-way relaying cooperation in a wireless network. To evaluate the scalable random access scheme, both theoretical analysis and simulations are carried out. Performance results illustrate that our scheme has achieved the goal of scalable two-way relaying in a wireless network and significantly outperforms CSMA/CA protocol.
Positive-Definite Sparse Precision Matrix Estimation  [PDF]
Lin Xia, Xudong Huang, Guanpeng Wang, Tao Wu
Advances in Pure Mathematics (APM) , 2017, DOI: 10.4236/apm.2017.71002
Abstract: The positive-definiteness and sparsity are the most important property of high-dimensional precision matrices. To better achieve those property, this paper uses a sparse lasso penalized D-trace loss under the positive-definiteness constraint to estimate high-dimensional precision matrices. This paper derives an efficient accelerated gradient method to solve the challenging optimization problem and establish its converges rate as \"\". The numerical simulations illustrated our method have competitive advantage than other methods.
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