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Influences of initial porosity,stress triaxiality and Lode parameter on plastic deformation and ductile fracture

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Acta Mechanica Solida Sinica 2017年第5期30卷 493-506页

作者： Ying-Song Ma Dong-Zhi Sun Florence Andrieux Ke-shi zhang College of Civil Engineering and Architecture Guangxi UniversityKey Lab of Disaster Prevention and Structural SafetyGuangxi Key Lab Disaster Prevention and Engineering SafetyNanning 530004China Department of Mining Engineering Shanxi Datong UniversityDatong 037003China Fraunhofer Institute for Mechanics of Materials IWM Woehlerstrasse 1179108 FreiburgGermany

Local mechanical properties in aluminum cast components are inhomogeneous as a con- sequence of spatial distribution of microstructure, e.g., porosity, inclusions, grain size and arm spacing of secondary dendrites. In this work, the effect of porosity is investigated. Cast components contain voids with different sizes, forms, orientations and distributions. This is approximated by a porosity distribution in the following. The aim of this paper is to in- vestigate the influence of initial porosity, stress triaxiality and Lode parameter on plastic deformation and ductile fracture. A micromechanical model with a spherical void located at the center of the matrix material, called the representative volume element （RVE）, is de- veloped. Fully periodic boundary conditions are applied to the RVE and the values of stress triaxiality and Lode parameter are kept constant during the entire course of loading. For this purpose, a multi-point constraint （MPC） user subroutine is developed to prescribe the loading. The results of the RVE model are used to establish the constitutive equations and to further investigate the influences of initial porosity, stress triaxiality and Lode parameter on elastic constant, plastic deformation and ductile fracture of an aluminum die castin~ alloy.

关键词： Stress triaxialityLode parameterVoidDuctile fractureRVE

Large Bi-Polar Signature in a Perpendicular Electric Field of Two-Dimensional Electrostatic Solitary Waves Associated with Magnetic Reconnection: Statistics and Discussion

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Chinese Physics Letters 2013年第1期30卷 231-234页

作者： LI shi-You zhang shi-Feng DENG Xiao-Hua CAI Hong College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073 Department of Space Physics Wuhan UniversityWuhan 430072 Nanchang University Nanchang 330031

More than 300 electrostatic solitary waves(ESWs)with a large perpendicular component which is a bi-polar waveform structure are observed in the boundary layer within the magnetic reconnection diffusion region in the near-Earth *** ESWs are called two-dimensional ESWs.A Singe-reconnection-based-statistical study of two-dimensional ESWs shows that:(1)ESWs can be continuously observed in the plasma sheet boundary layer(PSBL)associated with the magnetic reconnection diffusion region,and their amplitude ranges are mainly from several tens to hundreds ofμV/m;(2)both one-dimension-like ESWs(very small magnitude on E⊥)and two-dimension-like ESWs(large magnitude on E⊥,which are even comparable to that in the E||)are observed within a small time interval;(3)within the observation time spans,more than 61%of ESWs are regarded as two-dimensional ESWs for the I_(2)D>20%.We discuss the bi-polar structure in E⊥.The observation of ESWs with a large bi-polar structure in the perpendicular electric field gives evidence that the unique waveform differs from previous understanding from observations and simulations which suggests that it should be a uni-polar waveform structure in the E⊥of ESWs.

关键词： structure dimension Polar

Spatial Evolution of Electrostatic Solitary Waves along Plasma Sheet Boundary Layer Adjacent to the Magnetic Reconnection X-Line

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Chinese Physics Letters 2012年第8期29卷 313-317页

Analysis on the spatial structure of electrostatic solitary waves(ESWs)along the plasma sheet boundary layer(PSBL)near an on-going magnetic reconnection X-line is *** of the ESWs in the PSBL of R3 region near reconnection X-line are propagating earthwards away from the reconnecting *** analysis of their spatial structure shows that,when ESWs propagate along the ambient field in the PSBL,outwards from the magnetic reconnection X-line,their amplitude will finally attenuate and thus the electron hole will fade away but their spatial scale remains ***,the spatial structure of propagating ESWs evolves from 1-D-like to 2-D-like though totally in a 1-D structure.

关键词： Spatial propagating structure

Exploring the Constrained Maximum Edge-weight Connected Graph Problem

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Acta Mathematicae Applicatae Sinica 2009年第4期25卷 697-708页

作者： Zhen-ping Li shi-hua zhang Xiang-Sun zhang Luo-nan Chen School of Information Beijing Wuzi University Beijing 101149 China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China Institute of Systems Biology Shanghai University Shanghai 200444 China Department of Electrical Engineering and Electronics Osaka Sangyo University Osaka 574-8530 Japan

Given an edge weighted graph, the maximum edge-weight connected graph （MECG） is a connected subgraph with a given number of edges and the maximal weight sum. Here we study a special case, i.e. the Constrained Maximum Edge-Weight Connected Graph problem （CMECG）, which is an MECG whose candidate subgraphs must include a given set of k edges, then also called the k-CMECG. We formulate the k-CMECG into an integer linear programming model based on the network flow problem. The k-CMECG is proved to be NP-hard. For the special case 1-CMECG, we propose an exact algorithm and a heuristic algorithm respectively. We also propose a heuristic algorithm for the k-CMECG problem. Some simulations have been done to analyze the quality of these algorithms. Moreover, we show that the algorithm for 1-CMECG problem can lead to the solution of the general MECG problem.

关键词： connected subgraph integer linear programming model network flow constraint Steiner network maximum edge weight, heuristic algorithm

Effect of Western medicine therapy assisted by Ginkgo biloba tablet on vascular cognitive impairment of none dementia

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Asian Pacific Journal of Tropical Medicine 2012年第8期5卷 661-664页

作者： shi-Jin zhang Zhan-You Xue Department of Traditional Chinese Medicine People's Hospital of Zhengzhou Department of Neurology the First Affiliated Hospital of Zhengzhou University

Objective:To discuss the clinical effects of Western medicine therapy assisted by Ginkgo biloba tablet(GBT) on patients with vascular cognitive impairment of none dementia(VCIND).Methods: A total of 80 patients with VCIND were divided into two groups randomly:Conventional treatment group(control group) and combined treatment *** treatment group was given conventional treatment with anti-platelet *** this group,75 mg aspirin was given three times a day for 3 *** in combined treatment group,19.2 mg CRT was given three times a day for 3 months together with conventional treatment(anti-platelet aggregation drugs). Montreal cognitive assessment(MoCA) and transcranial Doppler(TCD) were used to observe changes of cognitive ability and cerebral blood flow in VCIND patients before and after treatment in both *** the clinical data were analyzed so as to compare the efficacy in two groups. Results:After 3 month-treatment in combined treatment group,the scores of executive ability, attention,abstract,delayed memory,orientation in the MoCA were significantly increased compared with those before treatment and those in control group after ***,blood flow velocity of anterior cerebral artery increased significandy than that before treatment and that in control group after ***:CBT tablet can improve the therapeutic efficacy as well improve cognitive ability and cerebral blood flow supply of patients with VCIND.

关键词： Combination of traditional Chinese and Western medicine Cognitive impairment Ginkgo tablet Clinical evaluation

A STUDY ON WETLAND CLASSIFICATION MODEL OF REMOTE SENSING IN THE SANGJIANG PLAIN

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Chinese Geographical Science 2000年第1期10卷 69-74页

作者： Shu-qing zhang shi-kui zhang Jun-yan zhang Changchun Jingyuetan Remote Sensing Test Site Changchun Institute of Geography the Chinese Academy of Sciences Changchun P. R. China Municipal Engineering Design & Research Institute of China Changchun P. R. China

The Sanjiang Plain, where nearly 20 kinds of wetlands exist now, is one of the largest wetlands distributed area of wetlands in China. To identify each of them and pick up them separately by means of automatic interpretation of remote sensing from TM Landsat images is extremely important. However, most of the types of wetlands can not be divided each other due to the similarity and the illegibility of the wetland spectrum shown in TM images. Special disposals to remote sensing images include the spectrum enhancement of wetland information, the pseudo color composite of TM images of different bands and the algebra enhancement of TM images. By this way some kinds of wetlands such as Sparganium stoloniferum and Bolboschoenus maritimus can be identified. But in many cases, these methods are still insufficient because of the noise brought from the atmosphere transportation and so on. The physical features of wetlands reflecting the diversification of spectrum information of wetlands, which include the spatial temporal characteristics of the wetlands distribution, the landscape differences of wetlands from season to season, the growing environment and the vertical structure of wetlands vegetation and so on, must be taken into consideration. Besides these, the artificial alteration to spatial structure of wetlands such as the exploitation of some types of them can be also used as important symbols of wetlands identification from remote sensing images. On the basis of the above geographics analysis, a set of wetlands classification models of remote sensing could be established, and many types of wetlands such as paddy field, reed swamp, peat mire, meadow, CAREX marsh and paludification meadow and so on, will be distinguished consequently. All the ways of geographical analysis and model establishment will be given in detail in this article.

关键词： wetlands in the Sanjiang Plain wetland classification model remote sensing classification image disposal

Clinical features of adverse reactions associated with telbivudine

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World Journal of Gastroenterology 2008年第22期14卷 3549-3553页

作者： Xue-Song zhang Rui Jin shi-Bin zhang Ming-Ling Tao Department of GI and Hepatology Beijing Youan Hospital affiliated to Capital Medical University Beijing 100069 China

AIM: To analyze the clinical features and risk factors of adverse reactions associated with telbivudine. METHODS: Clinical data were collected from cases that presented with serious adverse reactions to telbivudine. We analyzed general information and medicine status, clinical features, results of examination, and misdiagnosis. RESULTS: Out of 105 patients who were treated with telbivudine for hepatitis B in an outpatient department from January, 2007 to January, 2008, five presented with serious adverse drug reactions. Most of these five patients had used other nucleoside analogues in the past. Four were treated with a combination of telbivudine and interferon or another nucleoside analogue, while the other received an increased dose of telbivudine. The main adverse reactions were myalgia and general weakness. This was accompanied by cardiac arrhythmia in one patient, and nervous symptoms in three. Serum creatine kinase was elevated. The rate of misdiagnosis was high. CONCLUSION: The adverse reactions were related to telbivudine, but the biological mechanism of the reactions is not yet clear. Combination therapy with interferon or another nucleoside analogue and a high dose may increase the risk of adverse reactions.

关键词： Adverse drug reaction Hepatitis B Mitochondria Nucleoside analogue Telbivudine

Influences of Mechanical Vibration on Rapidly Solidified Al_2O_3/YSZ Ceramics Prepared by Combustion Synthesis

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Chinese Journal of Aeronautics 2006年第B12期19卷 27-30页

作者： ZHAO Zhong-min zhang Long WANG Wei-guo zhang shi-yue Institute of Advanced Materials Mechanical Engineering College Shijiazhuang 050003 China Science Research Department Mechanical Engineering College Shijiazhuang 050003 China Foreign Training Department Mechanical Engineering College Shijiazhuang 050003 China

Al2O3/YSZ composite ceramics was fabricated with combustion synthesis technology, and the influences of mechanical vibration on its microstructures and properties were investigated. It is found that under the mechanical vibration of ever-increasing frequency, increasing combustion temperature, accelerating ceramics/metal liquid-liquid separation and quickening ceramic solidification could not only reduce the average diameter and the size distribution of aligned ZrO2 nano-micron fibers in rod-shaped Al2O3 matrix grains, but also make the randomly-oriented rod-shaped grains finer and increase their aspect ratios. As a result, a remarkable increase in flexural strength and fracture toughness of the ceramics can be observed.

关键词： ceramic matrix composite combustion synthesis rapid solidification nanocrystalline microstructure mechanical vibration

Clinical and pathological characteristics and prognosis of 132 cases of rectal neuroendocrine tumors

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World Journal of Gastrointestinal Oncology 2020年第8期12卷 893-902页

作者： Yong-Jun Yu Yu-Wei Li Yang shi Zhao zhang Min-Ying Zheng shi-Wu zhang Department of Colorectal Surgery Tianjin Union Medical CenterTianjin 300121China Department of Pathology Tianjin Union Medical CenterTianjin 300121China

BACKGROUND Neuroendocrine tumors(NETs)frequently occur in the gastrointestinal tract,lung,and pancreas,and the rectum and appendix are the sites with the highest *** statistics show that an estimated 8000 people every year in the United States are diagnosed with NETs occurring in the gastrointestinal tract,including the stomach,intestine,appendix,colon,and *** pathological changes and clinical symptoms of NETs are not specific,and therefore they are frequently *** To investigate the clinical symptoms,pathological characteristics,treatment,and prognosis of rectal neuroendocrine tumors(RNETs)by analyzing the clinical and pathological data of 132 RNET cases at our *** All RNETs were graded according to Ki-67 positivity and mitotic *** tumors were staged as clinical stages I,II,III,and IV according to infiltrative depth and tumor *** proportional hazard model was used to assess the main risk factors for *** These 132 RNETs included 83 cases of G1,21 cases of G2,and 28 cases of G3(neuroendocrine carcinoma)*** staining showed that 89.4%of RNETs were positive for synaptophysin and 39.4%positive for chromogranin *** were 19,85,23,and 5 cases of clinical stages I,II,III,and IV,*** median patient age was 52.96 *** diameter of tumor,depth of invasion,and pathological grade were the main reference factors for the treatment of *** survival rates at 6,12,36,and 60 mo after operation were 98.5%,94.6%,90.2%,and 85.6%,***,tumor size,tumor grade,lymph node or distant organ metastasis,and radical resection were the main factors associated with prognosis of *** analysis showed that tumor size and grade were independent prognostic *** The clinical symptoms of RNETs are not specific,and they are easy to *** is the main treatment *** grade and stage of RNETs are the main indices to evaluate pr

关键词： Neuroendocrine tumors Prognosis Univariate analysis Tumor size Tumor grade Neuroendocrine carcinoma