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New discrete element models for elastoplastic problems

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Acta Mechanica Sinica 2009年第5期25卷 629-637页

作者： ming cheng Weifu liu Kaixin liu LTCS and Department of Mechanics and Aerospace Engineering,College of Engineering, Peking University, 100871 Beijing, China LTCS and Department of Mechanics and Aerospace Engineering College of Engineering Peking University Beijing China

The discrete element method （DEM） has attractive features for problems with severe damages, but lack of theoretical basis for continua behavior especially for nonlinear behavior has seriously restricted its application. The present study proposes a new approach to developing the DEM as a general and robust technique for modeling the elastoplastic behavior of solid materials. New types of connective links between elements are proposed, the interelement parameters are theoretically determined based on the principle of energy equivalence and a yield criterion and a flow rule for DEM are given for describing nonlinear behavior of materials. Moreover, a numerical scheme, which can be applied to modeling the behavior of a continuum as well as the transformation from a continuum to a discontinuum, is obtained by introducing a fracture criterion and a contact model into the DEM. The elastoplastic stress wave propagations and the tensile failure process of a steel plate are simulated, and the numerical results agree well with those obtained from the finite element method （FEM） and corresponding experiment, and thus the accuracy and efficiency of the DEM scheme are demonstrated.

关键词： DEM Continuum Plasticity Fracture

Study of muon tomographic imaging for high-Z material detection with a Micromegas-based tracking system

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Radiation Detection Technology and Methods 2020年第3期4卷 263-268页

作者： cheng-ming liu Qun-Gang Wen Zhi-Yong Zhang Guang-Shun Huang State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China AnHui University Hefei 230061China

Purpose To study the cosmic ray muon tomographic imaging of high-Z material with Micromegas-based tracking *** A high-spatial-resolution tracking system was set up with the micro-mesh gaseous structure(Micromegas)detec-tors in order to study the muon tomographic imaging *** layers of 90 mm×90 mm one-dimensional readout Micromegas were used to construct a tracking *** and conclusion The imaging test using some metallic bars was performed with cosmic ray muons.A two-dimensional imaging of the test object was presented with a newly proposed ratio *** result of this work shows that the ratio algorithm is well performed.

关键词： Muon tomography imaging Micromegas detector Ratio algorithm High spatial resolution

First-order multiples imaging aided by water bottom

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Petroleum Science 2021年第6期18卷 1650-1661页

作者： Zhen-Hua Xu Sheng-He Wu ming-cheng liu Jun-Shou Zhao Zhao-Hui Chen Ke Zhang Jia-Jia Zhang Zhao liu State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum-BeijingBeijing 102249China College of Geosciences China University of Petroleum-BeijingBeijing102249China Bohai Petroleum Research Institute CNOOC Tianjin BranchTianjin300459China Sinopec Geophysical Research Institute NanjingJiangsu211103China

Surface-related multiples frequently propagate into the subsurface and contain abundant information on small reflection *** with the conventional migration of primaries,migration of multiples offers complementary illumination and a higher vertical ***,crosstalk artifacts caused by unrelated multiples during reverse time migration(RTM)using multiples severely degrade the reliability and interpretation of the final migration ***,we proposed RTM using first-order receiver-side water-bottom-related multiples for eliminating crosstalk artifacts and enhancing vertical *** first backward propagate the first-order receiver-side water-bottom-related multiples using a water-layer model,followed by saving the upper boundary *** we produce the source wavefield using a seismic wavelet and the receiver wavefield by back-extrapolating the saved ***,the cross-correlation imaging condition is applied to generate the final *** method transforms the receiver-side multiples into primaries,followed by the conventional migration processing *** examples using synthetic datasets demonstrate that our method significantly enhances the imaging quality by eliminating crosstalk artifacts and improving the resolution.

关键词： Surface-related multiples Multiples imaging Multiples elimination

Energy correction based on fluorescence attenuation of DAMPE

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Research in Astronomy and Astrophysics 2020年第8期20卷 163-168页

作者： Li-Bo Wu Yun-Long Zhang Zhi-Yong Zhang Yi-Feng Wei Si-cheng Wen Hao-Ting Dai cheng-ming liu Xiao-Lian Wang Zi-Zong Xu Guang-Shun Huang State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China

The major scientific goals of the DArk Matter Particle Explorer(DAMPE)are to study cosmicray electrons(including positrons)and gamma rays from 5 GeV to 10 TeV and nuclei from Z=1 to 26 up to 100 *** deposited energy measured by the Bismuth Germanate Oxide(BGO)calorimeter of DAMPE is affected by fluorescence attenuation in BGO crystals that are 600 mm *** this work,an in-orbit attenuation calibration method is reported,and energy correction of the sensitive detector unit of the BGO calorimeter is also presented.

关键词： DAMPE BGO calorimeter fluorescence attenuation dark matter

Agent- oriented Software Engineering

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Journal of Systems Science and Systems Engineering 2001年第1期13卷 44-49页

作者： GUAN Xu, cheng ming, liu Bao School of Management, Tianjin University, Tianjin 300072, China School of Management Tianjin University Tianjin 300072 China

：An increasing number of computer systems are being viewed in terms of autonomous *** people believe that agent-oriented approach is well suited to design and build complex systems. Yet. todate, little effort had been devoted to discuss the advantages of agent-oriented approach as a mainstreamsoftware engineering paradigm. Here both of this issues and the relation between object-oriented and agent-oriented will be argued. we describe an agent-oriented methodology and provide a quote for designing anauction system.

关键词： agent-oriented approach software engineering multi-agent systems

Clinical observation of salvianolic acid B in treatment of liver fibrosis in chronic hepatitis B

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World Journal of Gastroenterology 2002年第4期8卷 679-685页

作者： Ping liu Yi-Yang Hu cheng liu Hui-ming Xue Zhi-Qiang Xu Lie-ming Xu cheng-Hai liu Hong-Tu Gu Shanghai University of Traditional Chinese Medicine,Shanghai 200032,China Da-Yuan Zhu Shanghai Institute of Metaria Medica,Chinese Academy of Sciences,Shanghai 200031,China Zhi-Qing Zhang the 4~(th) Hualyin City Hospital,Hualan City,223000,JiangSu Province,China Shanghai University of Traditional Chinese Medicine Shanghai 200032 China. liuliver@***

AIM: To evaluate the clinical efficacy of salvianolic acidB (SA-B) on liver fibrosis in chronic hepatitis ***: Sixty patients with definite diagnosis of liverfibrosis with hepatitis B were included in the ***-γ (IFN-γ) was used as control drug. Thepatients took orally SA-B tablets or received muscularinjection of IFN-γ in the double blind randomized test,The complete course lasted 6 months. The histologicalchanges of liver biopsy specimen before and after thetreatment were the main evidence in evaluation, incombination with the results of contents of serum HA,LN, Ⅳ-C, P-Ⅲ-P, liver ultrasound imaging, andsymptoms and ***: Reverse rate of fibrotic stage was 36.67 % inSA-B group and 30.0 % in IFN-γgroup. Inflammatoryalleviating rate was 40.0 % in SA-B group and 36.67 %in IFN-γ group. The average content of HA and Ⅳ-Cwas significantly lower than that before treatment. Theabnormal rate also decreased remarkably. Overallanalysis of 4 serological fibrotic markers showedsignificant improvement in SA-B group as comparedwith the IFN-γgroup. Score of liver ultrasound imagingwas lower in SA-B group than in IFN-γgroup (HA 36.7 %vs80 %,Ⅳ-C 3.3 % vs23.2 %). Before the treatment,ALT AST activity and total bilirubin content of patientswho had regression of fibrosis after oral administrationof SA-B, were significantly lower than those of patientswho had aggravation of fibrosis after oraladministration of SA-B. IFN-γ showed certain sideeffects (fever and transient decrease of leukocytes,occurrence rates were 50 % and 3.23 %), but SA-Bshowed no side ***: SA-B could effectively reverse liverfibrosis in chronic hepatitis B. SA-B was better than IFN-γ in reduction of serum HA content, overall decrease of4 serum fibrotic markers, and decrease of ultrasoundimaging score. Liver fibrosis in chronic hepatitis B withslight liver injury was more suitable to SA-B in anti-fibrotic treatment. SA-B showed no obvious side effects.

关键词：丹酚乙酸治疗乙型肝炎肝纤维化临床观察

Effects of water discharge on river-dominated delta growth

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Petroleum Science 2021年第6期18卷 1630-1649页

作者： Yan-Bao Zhang Yi-Ke liu Jia Yi Xue-Jian liu Institute of Geophysics China Earthquake AdministrationBeijing100081China Key Laboratory of Petroleum Resources Research Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China China Earthquake Disaster Prevention Center China Earthquake AdministrationBeijing100029China The Pennsylvania State University Department of GeosciencesUniversity ParkPA16802USA

River-dominated deltas are commonly developed at modern bays and lakes and ancient petroliferous *** discharge is an important variable at pay zone scales in river-dominated delta reservoirs,which affects deltaic sand distributions and ***,it's unclear how it influences riverdominated delta *** paper integrates Delft3 D simulations and modern analogs to analyze the effects of water discharge,considering growth time,sediment supply,and coupled effects of sediment *** water discharges lead to the formation of lobate deltas,and the water discharge of 1,000 m~3/s is a referenced threshold ***-grained,highly-cohesive sediments increase the threshold values of water discharge at which the deltas become lobate from digitate,and vice *** the same simulation time,high water discharges favor more rugose shorelines,more distributary channels(especially secondary distributaries),and longer and wider deltas with more land ***,for the same sediment supply,high water discharges have few effects on shoreline roughness and the number of distributary channels.

关键词： River-dominated delta Water discharge Morphology Distributary channel Hydrocarbon exploration

Neural differentiation of human Wharton＇s jelly-derived mesenchymal stem cells improves the recovery of neurological function after transplantation in ischemic stroke rats

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Neural Regeneration Research 2017年第7期12卷 1103-1110页

作者： Lei Zhang Lin-mei Wang Wei-wei Chen Zhi Ma Xiao Han cheng-ming liu Xiang cheng Wei Shi Jing-jing Guo Jian-bing Qin Xiao-qing Yang Guo-hua Jin Xin-hua Zhang Department of Anatomy Nantong University Nantong Jiangsu Province China Department of Radiation Oncology Third People's Hospital of Yancheng Yancheng Jiangsu Province China Department of Neurosurgery the-Affiliated Hosptial of Nantong University Nantong Jiangsu Province China Department of Obstetricsand Gynecology the Affiliated Hosptial of Nantong University Nantong Jiangsu Province China Co-innovation Center of Neuroregeneration Nantong University Nantong Jiangsu Province China

Human Wharton＇s jelly-derived mesenchymal stem cells（h WJ-MSCs）have excellent proliferative ability,differentiation ability,low immunogenicity,and can be easily ***,there are few studies on their application in the treatment of ischemic stroke,therefore their therapeutic effect requires further *** this study,h WJ-MSCs were transplanted into an ischemic stroke rat model via the tail vein 48 hours after transient middle cerebral artery *** 4 weeks,neurological functions of the rats implanted with h WJ-MSCs were significantly ***,many h WJ-MSCs homed to the ischemic frontal cortex whereby they differentiated into neuron-like cells at this *** results confirm that h WJ-MSCs transplanted into the ischemic stroke rat can differentiate into neuron-like cells to improve rat neurological function and behavior.

关键词： nerve regeneration human Wharton's jelly-derived mesenchymal stem cells ischemic stroke cell transplantation middle cerebral arteryocclusion neural differentiation neurological function neural regeneration

Method of Separating Cosmic-Ray Positrons from Electrons in the DAMPE Experiment

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Research in Astronomy and Astrophysics 2022年第3期22卷 115-121页

作者： Hao-Ting Dai Jing-Jing Zang Ying Wang Chuan-Ning Luo Yun-Long Zhang Zhi-Yong Zhang Yi-Feng Wei Li-Bo Wu cheng-ming liu Cong Zhao Xiao-Lian Wang Zi-Zong Xu Guang-Shun Huang State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China School of Physics and Electronic Engineering Linyi UniversityLinyi 276000China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China Gran Sasso Science Institute (GSSI)

A method of identifying positron/electron species from the cosmic rays was studied in the DArk Matter Particle Explorer(DAMPE)*** there is no onboard magnet on the satellite,the different features imposed by the geomagnetic field on these two species were exploited for the particle *** of this method to the simulation of on-orbit electrons/positrons/protons and the real flight data proves that separately measuring the CR positrons/electrons with DAMPE is feasible,though limited by the field of view for the present observation *** analysis on the positron flux with this method can be expected in the future.

关键词： (ISM:)cosmic rays magnetic fields (cosmology:)dark matter