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Search Results: 1 - 10 of 78186 matches for " Duofang Chen "
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Extended Finite Element Method with Simplified Spherical Harmonics Approximation for the Forward Model of Optical Molecular Imaging
Wei Li,Huangjian Yi,Qitan Zhang,Duofang Chen,Jimin Liang
Computational and Mathematical Methods in Medicine , 2012, DOI: 10.1155/2012/394374
Abstract: An extended finite element method (XFEM) for the forward model of 3D optical molecular imaging is developed with simplified spherical harmonics approximation ( ). In XFEM scheme of equations, the signed distance function is employed to accurately represent the internal tissue boundary, and then it is used to construct the enriched basis function of the finite element scheme. Therefore, the finite element calculation can be carried out without the time-consuming internal boundary mesh generation. Moreover, the required overly fine mesh conforming to the complex tissue boundary which leads to excess time cost can be avoided. XFEM conveniences its application to tissues with complex internal structure and improves the computational efficiency. Phantom and digital mouse experiments were carried out to validate the efficiency of the proposed method. Compared with standard finite element method and classical Monte Carlo (MC) method, the validation results show the merits and potential of the XFEM for optical imaging. 1. Introduction Light propagation model in biological tissue is the foundation of optical imaging. An accurate forward model is important for location and quantification of target distribution in the fields of optical imaging modalities, such as diffusion optical tomography (DOT), fluorescence molecular tomography (FMT), bioluminescence tomography (BLT), and Cerenkov luminescence tomography (CLT) [1–5]. The propagation of the emission photons in tissue can be accurately represented by the radiative transfer equation (RTE) or Monte Carlo (MC) models, but they are extremely computationally expensive. Therefore, the commonly used mathematical model in optical imaging field is the diffusion approximation (DA) to RTE. However, the DA model can be used only in the highly scattering property of the biological tissue, and is not suitable for the real mouse with complex internal tissues. To reach a compromise between the accuracy and efficiency, simplified spherical harmonics approximation ( ) to RTE is employed due to its capacity in improving the solution in transport-like domains with high absorption and small geometries [6, 7]. Owing to the complex and curvilinear geometries associated with the biological tissues, the classical finite element methods (FEM) with approximation become necessary for optical imaging, especially for heterogeneous tissues [8–10]. In the FEM scheme, the region of heterogeneous tissue is divided into small tetrahedron elements. The linear functions of the tetrahedron element are employed in the standard finite element basis
Sparse Regularization-Based Reconstruction for Bioluminescence Tomography Using a Multilevel Adaptive Finite Element Method
Xiaowei He,Yanbin Hou,Duofang Chen,Yuchuan Jiang,Man Shen,Junting Liu,Qitan Zhang,Jie Tian
International Journal of Biomedical Imaging , 2011, DOI: 10.1155/2011/203537
Abstract: Bioluminescence tomography (BLT) is a promising tool for studying physiological and pathological processes at cellular and molecular levels. In most clinical or preclinical practices, fine discretization is needed for recovering sources with acceptable resolution when solving BLT with finite element method (FEM). Nevertheless, uniformly fine meshes would cause large dataset and overfine meshes might aggravate the ill-posedness of BLT. Additionally, accurately quantitative information of density and power has not been simultaneously obtained so far. In this paper, we present a novel multilevel sparse reconstruction method based on adaptive FEM framework. In this method, permissible source region gradually reduces with adaptive local mesh refinement. By using sparse reconstruction with 1 regularization on multilevel adaptive meshes, simultaneous recovery of density and power as well as accurate source location can be achieved. Experimental results for heterogeneous phantom and mouse atlas model demonstrate its effectiveness and potentiality in the application of quantitative BLT.
Normalized Born Approximation-Based Two-Stage Reconstruction Algorithm for Quantitative Fluorescence Molecular Tomography
Huangjian Yi,Duofang Chen,Wei Li,Shuang Zhou,Miao Ning,Shouping Zhu,Jie Tian,Jimin Liang
Journal of Electrical and Computer Engineering , 2012, DOI: 10.1155/2012/838967
Abstract: Fluorescence molecular tomography (FMT) is a promising technique for in vivo small animal imaging. In this paper, a two-stage reconstruction method based on normalized Born approximation is developed for FMT, which includes two steps for quantitative reconstruction. First, the localization of fluorescent fluorophore is determined by -norm regularization method. Then, in the location region of fluorophore, which is provided by the first stage, algebraic reconstruction technique (ART) is utilized for the fluorophore concentration reconstruction. The validity of the two-stage quantitative reconstruction algorithm is testified by simulation experiments on a 3D digital mouse atlas and physical experiments on a phantom. The results suggest that we are able to recover the fluorophore location and concentration.
Qualitative Simulation of Photon Transport in Free Space Based on Monte Carlo Method and Its Parallel Implementation
Xueli Chen,Xinbo Gao,Xiaochao Qu,Duofang Chen,Bin Ma,Lin Wang,Kuan Peng,Jimin Liang,Jie Tian
International Journal of Biomedical Imaging , 2010, DOI: 10.1155/2010/650298
Abstract: During the past decade, Monte Carlo method has obtained wide applications in optical imaging to simulate photon transport process inside tissues. However, this method has not been effectively extended to the simulation of free-space photon transport at present. In this paper, a uniform framework for noncontact optical imaging is proposed based on Monte Carlo method, which consists of the simulation of photon transport both in tissues and in free space. Specifically, the simplification theory of lens system is utilized to model the camera lens equipped in the optical imaging system, and Monte Carlo method is employed to describe the energy transformation from the tissue surface to the CCD camera. Also, the focusing effect of camera lens is considered to establish the relationship of corresponding points between tissue surface and CCD camera. Furthermore, a parallel version of the framework is realized, making the simulation much more convenient and effective. The feasibility of the uniform framework and the effectiveness of the parallel version are demonstrated with a cylindrical phantom based on real experimental results.
Research on the Incentive Mechanism of Hidilao Hotpot’s Employees Based on Grounded Theory  [PDF]
Chen Chen
Journal of Human Resource and Sustainability Studies (JHRSS) , 2018, DOI: 10.4236/jhrss.2018.61031
Abstract: The traditional classical incentive model only reveals the general rule of organizational incentive, and does not give specific operation rules. The matching between organizational incentives and employee needs is still black box, and it does not reveal its core operation mechanism from the perspective of mechanism. This paper took through the literature review, the Hidilao Hotpot company as a case study, through a variety of ways to collect data, the use of grounded theory to encode data analysis, and ultimately extracted 58 concepts, 26 sub-areas, 7 main areas, concluded that the Hidilao Hotpot Employee motivation formed the path, and ultimately extracted the micro-level employee motivation mechanism model. The research result of this article comes from the practice of the enterprise, which has enlightenment to the organizational incentive of the traditional catering industry and also provides a micro-research perspective and systematic mechanism research for the incentive field.
Digital Image Watermarking Based on Mixed Error Correcting Code  [PDF]
Yonghong Chen, Jiancong Chen
Journal of Information Security (JIS) , 2012, DOI: 10.4236/jis.2012.32018
Abstract: In this paper, we present a novel technique based on a mixed Error Correcting Code(ECC)-the convolutional code and the repetition code to enhance the robustness of the embedded watermark. Before embedding, the binary watermark is scanned to one-dimension sequence and later inputted into the (3, 1, 2) convolutional encoder and (3, 1) repetition encoder frame by frame, which will improve the error correcting capability of decoder. The output code sequence is scanned to some matrixes as the new watermark messages. The watermarking is selected in low frequency band of the Discrete Wavelet Transform (DWT) and therefore it can resist the destruction of image processing. Experimental results are presented to demonstrate that the robustness of a watermark with mixed ECC is much higher than the traditional one just with repetition coding while suffering JPEG lossy compression, salt and pepper noise and center cutting processing.
Operator Equation and Application of Variation Iterative Method  [PDF]
Ning Chen, Jiqian Chen
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.38127
Abstract: In this paper, we study some semi-closed 1-set-contractive operators A and investigate the boundary conditions under which the topological degrees of 1-set contractive fields, deg (I-A, Ω, p) are equal to 1. Correspondingly, we can obtain some new fixed point theorems for 1-set-contractive operators which extend and improve many famous theorems such as the Leray-Schauder theorem, and operator equation, etc. Lemma 2.1 generalizes the famous theorem. The calculation of topological degrees and index are important things, which combine the existence of solution of for integration and differential equation and or approximation by iteration technique. So, we apply the effective modification of He’s variation iteration method to solve some nonlinear and linear equations are proceed to examine some a class of integral-differential equations, to illustrate the effectiveness and convenience of this method.
Blow-Up and Attractor of Solution for Problems of Nonlinear Schrodinger Equations  [PDF]
Ning Chen, Jiqian Chen
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.312263
Abstract: In this paper, the authors study the blow-up of solution for a class of nonlinear Schrodinger equation for some initial boundary problem. On the other hand, the authors give out some analyses and that new conclusion by Eigen-function method. In last section, the authors check the nonlinear parameter for light rule power by using of parameter method to get ground state and excite state correspond case, and discuss the global attractor of some fraction order case, and combine numerical test. To illustrate this physics meaning in dimension d = 1, 2 case. So, by numerable solution to give out these wave expression.
Some Approximation in Cone Metric Space and Variational Iterative Method  [PDF]
Ning Chen, Jiqian Chen
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.312276
Abstract: In this paper, we give some new results of common fixed point theorems and coincidence point case for some iterative method. By using of variation iteration method and an effective modification of He’s variation iteration method discusses some integral and differential equations, we give out some new conclusion and more new examples.
Photoconductive Effect of Liquid and Utilization of Solar Energy  [PDF]
Ziwei Chen, Shihao Chen
Open Journal of Physical Chemistry (OJPC) , 2014, DOI: 10.4236/ojpc.2014.41003
Abstract:

Experiments described in this paper show that there is the photoconductive effect of liquid, i.e. when light shines into a sort of alkali, acid or salt solution, the conductivity of the solution will increase. The mechanism of the effect is explained as follows. When hydrated ions in the solution absorb photons with their high enough energies, they will decompose to naked ions and water-molecules. The naked ions can reach an anode or a cathode more easily and faster than the hydrated ions; It is possible that when a molecule in the solution absorbs a photon with its high enough energy, it will decompose to negative and positive ions. Based on the effect, a device producing hydrogen by the solar-energy had been devised.

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