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FUNDAMENTAL SOLUTION BASED GRADED ELEMENT MODEL FOR STEADY-STATE HEAT TRANSFER IN FGM

Acta Mechanica Solida Sinica 2012年第4期25卷 377-392页

作者： Leilei cao Hui Wang Qing-hua Qi Key Laboratory for Highway Construction Technology and Equipment of Ministry of Education Chang'an University Xi'an 710064 China School of Engineering Australian National University canberra ACT 0200 Australia College of Civil Engineering and Architecture Henan University of Technology Zhengzhou 450052 China

A novel hybrid graded element model is developed in this paper for investigating thermal behavior of functionally graded materials （FGMs）. The model can handle a spatially varying material property field of FGMs. In the proposed approach, a new variational functional is first constructed for generating corresponding finite element model. Then, a graded element is formulated based on two sets of independent temperature fields. One is known as intra-element temperature field defined within the element domain; the other is the so-called frame field defined on the element boundary only. The intra-element temperature field is constructed using the linear combination of fundamental solutions, while the independent frame field is separately used as the boundary interpolation functions of the element to ensure the field continuity over the interelement boundary. Due to the properties of fundamental solutions, the domain integrals appearing in the variational functional can be converted into boundary integrals which can significantly simplify the calculation of generalized element stiffness matrix. The proposed model can simulate the graded material properties naturally due to the use of the graded element in the finite element （FE） model. Moreover, it inherits all the advantages of the hybrid Trefftz finite element method （HT-FEM） over the conventional FEM and boundary element method （BEM）. Finally, several examples are presented to assess the performance of the proposed method, and the obtained numerical results show a good numerical accuracy.

关键词： graded element hybrid FEM heat conduction functionally graded materials

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The DFF-PSP Iterative Separation and Theoretical Bound for PCMA with Long Memory

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Chinese Journal of Electronics 2016年第5期25卷 880-885页

作者： CUI Penghui JIANG hua cao Kai LI Taozhu National Digital Switching Engineering Technological Research Center

This paper proposes the Decision feedbackfeedforward per-survivor processing(DFF-PSP) iterative separation algorithm and the Monte Carlo integrationbased method to compute the theoretical bound for Paired carrier multiple access(PCMA) Single channel blind separation(SCBS) which is highly complex with long memory. The truncated PSP is employed while the pre- and post- cursors are disregarded to control the *** delayed decisions feedforward and local decisions feedback filters are designed to process the pre- and postcursors. The Bit-interleaved code modulation iterative decoder(BICM-ID) is combined with the second soft decision of the truncated PSP to obtain a better *** mixture signal model is regarded as a Multiple-access channel(MAC) with memory, and the theoretical performance bound is obtained via entropy inequality, Monte Carlo integration and Fano inequality. Simulation results show that the DFF-PSP iterative separation provides the good tradeoff between complexity and performance.

关键词： Paired carrier multiple access(PCMA) Single channel blind separation(SCBS) Decision feedbackfeedforward Per-survivor processing Bit-interleaved code modulation iterative decoder(BICM-ID) Multiple-access channel(MAC) Theoretical performance bound

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Hybrid graded element model for transient heat conduction in functionally graded materials

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Acta Mechanica Sinica 2012年第1期28卷 128-139页

作者： Lei-Lei cao Qing-hua Qin Ning Zhao Key Laboratory for Road Construction Technology＆ Equipment of MOE Chang＇ an University 710064 Xi＇ an China Research School of Engineering Australian National UniversityCanberra ACT 0200 Australia School of Mechatronics Northwestern Polytechnical University710072 Xi＇an China

This paper presents a hybrid graded element model for the transient heat conduction problem in functionally graded materials （FGMs）. First, a Laplace transform approach is used to handle the time variable. Then, a fundamental solution in Laplace space for FGMs is constructed. Next, a hybrid graded element is formulated based on the obtained fundamental solution and a frame field. As a result, the graded properties of FGMs are naturally reflected by using the fundamental solution to interpolate the intra-element field. Further, Stefest＇s algorithm is employed to convert the results in Laplace space back into the time-space domain. Finally, the performance of the proposed method is assessed by several benchmark examples. The results demonstrate well the efficiency and accuracy of the proposed method.

关键词： Graded element model Functionally graded materials Hybrid FEM Transient heat conduction

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A Comparative Study of Various Flow Instability Criteria in Processing Map of Superalloy GH4742

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Journal of Materials Science & Technology 2014年第3期30卷 217-222页

作者： Ge Zhou hua Ding Furong cao Beijiang Zhang College of Materials and Metallurgy Northeastern University High Temperature Materials Division Central Iron and Steel Research Institute

Hot compression tests were conducted on a Gleeble-1500D thermal simulating tester. Based on the deformation behavior and microstructural evolution of superalloy GH4742, different types of instability criteria of Prasad, Gegel, Malas, Murty and Semiatin were compared, and the physical significance of parameters was analyzed. Meanwhile, the processing maps with different instability criteria were obtained. It was shown that instability did not occur when average power dissipation rate was larger than 50% in the temperature range of 1020- 1130℃, corresponding to the strain rate range of 5 × 10-4-3.2 × 10-3 s-1. The domain is appropriate for the processing deformation of superalloy GH4742.

关键词： GH4742 superalloy Hot compression tests Flow instability criterion Processing map

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Biomechanical Study on the Novel Biomimetic Hemi-Pelvis Prosthesis

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Journal of Bionic Engineering 2013年第4期10卷 506-513页

作者： Zikai hua Yongwei Fan Qinghong cao Xianbo Wu Departrment of Mechatronics Engineering and Automation Shanghai University Shanghai 200072 P. R. China Shanghai Thytec Co. Ltd Shanghai 201112 P. R. China

A pelvic endoprosthesis is the primary means of pelvic reconstruction after internal hemipelvectomy. In this study, a novel biomimetic hemipelvic prosthesis, including an artificial ilium, an artificial acetabulum, and an artificial pubis, was developed. A Finite Element Method （FEM） was carried out to investigate the biomechanical performance of a pelvis reconstructed with biomimetic hemipelvic prosthesis. Two models, including the reconstructed pelvis and the original pelvis （control model）, were established according to the geometry from CT data of a human male patient with pelvic bone sarcomas. The FE models predict that the biomeehanical function of the pelvic ring can be reestablished using this prosthesis. Results show that the body force loaded on the S 1 vertebra is restored and transferred towards the sacro-iliac joint, and along the ilium onto the bearing surface of the artificial ilium, then to the artificial acetabulum and pubis. Von Mises stresses observed in this reconstructed pelvis model are still within a low and elastic range below the yielding strength of cortical bone and Ti6A14V. The values of deformation and strain of the reconstructed pelvis are close to the data obtained in the original pelvis. With the partial replacement of the pubis, little influence is found towards the pubis symphysis. However, the interface between the prosthesis and pelvic bone may become the critical part of the reconstructed pelvis due to the discontinuity in the material properties, which results in stress shielding and deformation constraining. So a biomimetic flexible connection or inter layer to release the deformation of pelvis is suggested in future designing.

关键词： biomimetic prosthesis pelvic reconstruction biomechanics FEM

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Bilayered HA/CS/PEGDA hydrogel with good biocompatibility and self-healing property for potential application in osteochondral defect repair

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Journal of Materials Science & Technology 2018年第6期34卷 1016-1025页

作者： Baihao You Qingtao Li hua Dong Tao huang Xiaodong cao hua Liao School of Materials Science and Engineering South China University of Technology Guangzhou 510641 China National Engineering Research Centre for Tissue Restoration and Reconstruction Guangzhou 510006 China School of Medicine South China University of Technology Guangzhou 510006 China Department of Anatomy Guangdong Provincial Key Laboratory of Construction and Detection in Tissue Engineering Southern Medical University Guangzhou 510515 China

The fabrication of osteochondral tissue engineering scaffolds comprised of different layers is a big challenge. Herein, bilayers comprised of double network hydrogels with or without nano hydroxyapatite （HAp） were developed by exploiting the radical reaction of poly（ethylene glycol） diacrylate （PEGDA） and the Schiff-base reaction of N-carboxyethyl chitosan （CEC） and oxidized hyaluronic acid sodium （OHA） for osteochondral tissue engineering. The bilayered osteochondral scaffold was successfully fabricated based on the superior self-healing property of both hydrogels and evaluated by scanning electron microscopy, macroscopic observation and mechanical measurements. In addition, the hydrogels exhibited good biocompatibility as demonstrated by the in vitro cytotoxicity and in vivo implantation tests. The results indicated that the bilayered hydrogel had great potential for application in osteochondral tissue engineering.

关键词： Bilayered hydrogel Self-healing Osteochondral scaffold Chitosan Hyaluronic acid

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Classifying Genomic Sequences by Sequence Feature Analysis

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Genomics, Proteomics & Bioinformatics 2005年第4期3卷 201-205页

作者： Zhi-hua Liu dian Jia Xiao Sun State Key Laboratory of Bioelectronics Southeast University Nanjing 210096 China.

Traditional sequence analysis depends on sequence alignment. In this study, we analyzed various functional regions of the human genome based on sequence features, including word frequency, dinucleotide relative abundance, and base-base correlation. We analyzed the human chromosome 22 and classified the upstream, exon, intron, downstream, and intergenic regions by principal component analysis and discriminant analysis of these features. The results show that we could classify the functional regions of genome based on sequence feature and discriminant analysis.

关键词： genome sequence feature analysis BBC PCA discriminant analysis

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Solving SAT problem by heuristic polarity decision-making algorithm

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Science in China(Series F) 2007年第6期50卷 915-925页

作者： JING MingE ZHOU dian TANG PuShan ZHOU XiaoFang ZHANG hua State Key Laboratory of ASIC & System Microelectronics Department Fudan University Shanghai201203 China E. E. Department the University of Texas at Dallas TX 75083 USA

This paper presents a heuristic polarity decision-making algorithm for solving Boolean satisfiability （SAT）. The algorithm inherits many features of the current state-of-the-art SAT solvers, such as fast BCP, clause recording, restarts, etc. In addition, a preconditioning step that calculates the polarities of variables according to the cover distribution of Karnaugh map is introduced into DPLL procedure, which greatly reduces the number of conflicts in the search process. The proposed approach is implemented as a SAT solver named DiffSat. Experiments show that DiffSat can solve many ＂real-life＂ instances in a reasonable time while the best existing SAT solvers, such as Zchaff and MiniSat, cannot. In particular, DiffSat can solve every instance of Bart benchmark suite in less than 0.03 s while Zchaff and MiniSat fail under a 900 s time limit. Furthermore, DiffSat even outperforms the outstanding incomplete algorithm DLM in some instances.

关键词： SAT problem DPLL complete algorithm decision-making

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Antitumor and synergistic effect of Chinese medicine “Bushen huayu jiedu recipe” and chemotherapy on transplanted animal hepatocarcinoma

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World Journal of Gastroenterology 2005年第33期11卷 5218-5220页

作者： Yong cao Qing-hua Xia hua Meng An-Pu Zhong Department of Traditional Chinese Medicine Medical College Jinan UniversityGuangzhou 510632 Guangdong Province China

AIM： To investigate the antitumor and synergistic effect of Chinese medicine “Bushen huayu jiedu recipe” （recipe for invigorating the kidney, removing blood stasis and toxic substances） and chemotherapy on mice hepatocarcinoma. METHODS： Bushen huayu jiedu recipe （BSHYJDR） consisting of Chinese Cassia Bark, Psoralea, Zedoary, Rhubarb, etc. is equal to 1.5 g/mL liquid of originated herbs after being decoded, filtered, and concentrated. Kunming mice, weighing 18-22 g, were injected with 0.2 mL ascitic hepatocarcinoma H22 containing 1 × 10^7 cells/mL into armpit of the right forelimb of mice. After 24 h, the mice were weighed and randomly divided into tumor-bearing model control group, cisplatin （DDP） group, BSHYJDR high dosage group, low dosage BSHYJDR group, DDP combined with high and low dosage BSHYJDR group, 10 mice in each group. DDP group received injection intraperitoneally （ip） at the dosage of 1 mg/kg （equal to 1/10 LD50）, once a day for 4 d. High and low dosage BSHYJDR groups received intragastric BSHYJDR at the dosages of 26.6 and 13.3 g/kg （20 and 10 times each of clinical adult dosage） respectively, while tumor-bearing model group received the equal volume of distilled water once a day for 10 d. On the 11^th d, the mice were weighed and killed, then the tumor was dissected and weighed, the repression rate （RR） was calculated according to the mean weight of tumor （MWT）. RESULTS： Compared to the model group （MWT： 1.30±0.73）, DDP group （MWT： 0.41±0.09, RR： 68.46%） had a significant difference in the inhibition of hepatocarcinoma H22 （P〈0.01）. High dosage BSHYJDR group （MWT： 0.69±0.29, RR： 46.92%） also had a significant difference in inhibition （P〈0.05）, while no difference was found in low dosage BSHYJDR group （MVVT： 0.85±0.34, RR： 34.62%）（P〉0.05）. When DDP was combined with high dosage BSHYJDR （MWT： 0.29±0.17, RR： 77.69%） and low dosage BSHYJDR （MWT： 0.38±0.21, RR： 70.77%） respectively, we could see improvement of the inhibition effect of DDP on transplanted

关键词： Bushen huayu jiedu recipe Mice hepatocarcinoma H22 Antitumor effects Synergy

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A review of object representation based on local features

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Journal of Zhejiang University-Science C(Computers and Electronics) 2013年第7期14卷 495-504页

作者： Jian cao dian-hui MAO Qiang CAI Hai-sheng LI Jun-ping DU College of Computer and Information Engineering Beijing Technology and Business University School of Computer Science Beijing University of Posts and Telecommunications

Object representation based on local features is a topical subject in the domain of image understanding and computer vision. We discuss the defects of global features in present methods and the advantages of local features in object recognition, and briefly explore state-of-the-art recognition methods using local features, especially the main approaches of local feature extraction and object representation. To clearly explain these methods, the problem of local feature extraction is divided into feature region detection, feature region description, and feature space optimization. The main components and merits of these steps are presented. Technologies for object presentation are classified into three types: vector space, sliding window, and structure relationship models. Future development trends are discussed briefly.

关键词： Object presentation Local feature Image understanding Object recognition Visual words

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