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Modeling of interphases in multiple heterogeneities reinforced composites using Voronoi cell finite elements

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Acta Mechanica Sinica 2020年第4期36卷 887-901页

作者： Rui Zhang Ting Wang ran guo Engineering Mechanics Department of Kunming University of Science and Technology Kunming 650500China

In this paper,a Voronoi cell finite element model is developed to study the microscopic and macroscopic mechanical behaviors of heterogenous materials,including arbitrary distributed heterogeneity(inclusions or fibers)coated with interphase layers,based on linear elasticity *** interphase between heterogeneity and a matrix are regarded as in the third phase(elastic layers),in contrast to the perfect interface of the spring-like Voronoi cell finite element model(VCFEM)in the *** this model,both stress and the displacement field are assumed to be independent in an *** of stress are derived for each of the three phases in an element,as is the type of *** examples were used to study the microscopic and macroscopic properties,such as the effective modulus,of the *** results of the proposed VCFEM were compared with analytical solution and numerical results obtained from a standard finite element analysis to confirm its effectiveness.

关键词： Voronoi cell finite element method Interphase Multiple fiber composites Effective elastic property

A New Hybrid Stress Element with Fluid

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Acta Mechanica Solida Sinica 2021年第5期34卷 766-778页

作者： Yingyu Qiu ran guo Ting Wang Engineering Mechanics Department of Kunming University of Science and Technology Kunming650500China

In the process of shale gas exploitation,there exits two difficult problems:one is the real numerical simulation of a tremendous number of holes in actual shale;the other is the fluid–solid coupling problem involved in holes,where the difficulty of transition at the interface between the Eulerian grid and the Lagrangian grid becomes the most *** response to these two problems,this paper establishes an element model with both fluid and *** the fluid–solid interface,the equilibrium condition of the surface force is introduced to obtain the modified complementary energy functional,and a new hybrid stress element with fluid is *** comparison of the simulation results with those of the ordinary commercial finite element software verifies the effectiveness and efficiency of this element,and proves its applicability in the problem of shale with numerous ***,this element can be extended to general problems of solid with fluid in.

关键词： Solid with fluid Hybrid stress element Shale gas exploitation Eulerian grid Lagrangian grid

Studying V-Notch Stress Intensity Factor by Digital Gradient Sensing Method

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Acta Mechanica Solida Sinica 2019年第3期32卷 378-392页

作者： Dedeng Chen Rui Zhang ran guo Department of Engineering Mechanics Kunming University of Science and Technology Kunming 650500 China

The stress intensity factor (SIF) at the V-notch tip of a single-edge-notched polymethyl methacrylate plate was measured by the digital gradient sensing (DGS) method. First, the displacement fields near the V-notch tip of the specimen were recorded using digital image correlation under three-point bending. Second, the stress gradient function of the V-notch tip with unknown SIF was deduced from the Williams series expansion for singular elastic stress fields. Finally, the relationship between the stress gradient and the angular deflection around the V-notch tip was established according to the photoelastic effect. Combined with the theory of linear elastic fracture mechanics, it was derived that the angular deflection of each point can be expressed with the unknown SIF. Considering the unavoidable effects of rigid-body translation and rotation in the experiments, the new angular deflection control equation was derived based on the traditional angular deflection control equation. The SIF was obtained by the least square method. The experimental values calculated by the new control equation were compared with the analytical values. The result shows that the DGS method can accurately measure the SIF at the V-notch tip, which effectively improves the accuracy of SIF.

关键词： Digital gradient sensing(DGS) V-notch Angular deflection Stress intensity factor (SIF) Least square method

Hybrid Finite Element Method Based on Polygon-Quadtree Meshes for Heat Transfer and Thermal Elastic Analysis

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Acta Mechanica Solida Sinica 2023年第5期36卷 745-753页

作者： Lihui Wang Rui Zhang ran guo Jiangbo Tao Faculty of Civil Engineering and Mechanics Kunming University of Science and TechnologyKunming 650000China

A steady-state thermal hybrid element model is proposed to calculate particle-reinforced composites divided by an improved quadtree *** functional of hybrid flux finite element method(HF-FEM)is constructed using the weighted residual *** functional independently assumes a heat flux field in the cell domain and a temperature field along cell *** construction of a universal heat flux function is put forward,which is approximated by a complete polynomial,and the temperature at the cell boundary is obtained by linear ***,the hybrid stress finite element method(HS-FEM)is constructed to solve the thermal *** this paper,an improved quadtree grid that can accurately describe the shape of elliptical inclusions is *** comparing several numerical examples with the traditional FEM,it is demonstrated that the hybrid element of the thermal analysis proposed in this paper is practical.

关键词： Hybridﬂux method Hybrid thermal stress method Improved quadtree grid Steady-state

Voronoi Cell Finite Element Study on Particle-Reinforced Composites Containing Interphases Considering Both Interfacial Debonding and Thermal Stress

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Acta Mechanica Solida Sinica 2022年第6期35卷 1055-1067页

作者： Jianfei Li Rui Zhang ran guo guohua Li Faculty of Civil Engineering and Mechanics Kunming University of Science and TechnologyKunming650000China

This paper derives the complementary energy functional based on the Voronoi element of particle-reinforced composites containing interphases to compute the interfacial debonding and thermal *** calculating interfacial debonding stress,it is assumed that the surface force is zero at the interface where debonding occurs,and a new modified complementary energy functional is derived with this boundary *** considering the thermal stress due to temperature change,the thermal strain is introduced into the complementary energy functional,and the thermal stress is then *** to the derived formula,a Fortran program named Voronoi cell finite element model(VCFEM)is *** interfacial debonding and thermal stress is calculated using both VCFEM and the finite element software MARC,and the calculation results are *** shows that the calculation results of the VCFEM are roughly comparable to those of the MARC,verifying the effectiveness of the VCFEM.

关键词： Voronoi VCFEM Interphase Interfacial debonding Thermal stress

Spatial and temporal relationships between precipitation and ANPP of four types of grasslands in northern China

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Journal of Environmental Sciences 2006年第5期18卷 1024-1030页

作者： guo ran WANG Xlao-ke OUYANG Zhi-yun LI Ying-nian Key Lab of Systems Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Northwest Inst tute of Plateau Biology Ch nese Academy of Sciences Xining 810001 China

Precipitation is considered to be the primary resource limiting terrestrial biological activity in water-limited regions. Its overriding effect on the production of grassland is complex. In this paper, field data of 48 sites （including temperate meadow steppe, temperate steppe, temperate desert steppe and alpine meadow） were gathered from 31 published papers and monographs to analyze the relationship between above-ground net primary productivity （ANPP） and precipitation by the method of regression analysis. The results indicated that there was a great difference between spatial pattern and temporal pattern by which precipitation influenced grassland ANPP. Mean annual precipitation （MAP） was the main factor determining spatial distribution of grassland ANPP （r^2 = 0.61, P 〈 0.01）; while temporally, no significant relationship was found between the variance of AN PP and inter-annual precipitation for the four types of grassland. However, after dividing annual preeipitation into monthly value and taking time lag effect into account, the study found significant relationships between ANPP and precipitation. For the temperate meadow steppe, the key variable determining inter-annual change of ANPP was last August-May precipitation （r^2 = 0.47, P = 0.01）; for the temperate steppe, the key variable was July precipitation （r^2 = 0.36, P = 0.02）; for the temperate desert steppe, the key variable was April-June precipitation （r^2 = 0.51, P 〈 0.01）; for the alpine meadow, the key variable was last September-May precipitation （r^2 = 0.29, P 〈 0.05）. In comparison with analogous research, the study demonstrated that the key factor determining inter-annual changes of grassland ANPP was the cumulative precipitation in certain periods of that year or the previous year.

关键词： above-ground net primary productivity mean annual precipitation spatial sensitivity inter-annual changes

Long-term quality-of-care score for predicting the occurrence of acute myocardial infarction in patients with type 2 diabetes mellitus

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World Journal of Diabetes 2023年第7期14卷 1091-1102页

作者： Pi-I Li How-ran guo Department of Family Medicine Chi Mei Medical CenterTainan 710TaiwanChina Department of Pharmacy Chia Nan University of Pharmacy and ScienceTainan 717TaiwanChina Department of Environmental and Occupational Health College of MedicineNational Cheng Kung UniversityTainan 704TaiwanChina Department of Occupational and Environmental Medicine National Cheng Kung University HospitalTainan 704TaiwanChina

BACKGROUND Cardiovascular disease(CVD)is the leading cause of death globally,and diabetes mellitus(DM)is a well-established risk *** the risk factors for CVD,DM is a major modifiable *** the fatal CVD outcomes,acute myocardial infarction(AMI)is the most common cause of *** To develop a long-term quality-of-care score for predicting the occurrence of AMI among patients with type 2 DM on the basis of the hypothesis that good quality of care can reduce the risk of AMI in patients with *** Using Taiwan’s Longitudinal Cohort of Diabetes Patients Database and the medical charts of a medical center,we identified incident patients diagnosed with type 2 DM from 1999 to 2003 and followed them until *** constructed a summary quality-of-care score(with values ranging from 0 to 8)with process indicators(frequencies of HbA1c and lipid profile testing and urine,foot and retinal examinations),intermediate outcome indicators(low-density lipoprotein,blood pressure and HbA1c),and co-morbidity of *** associations between the score and the incidence of AMI were evaluated using Cox regression *** A total of 7351 patients who had sufficient information to calculate the score were *** comparison with participants who had scores≤1,those with scores between 2 and 4 had a lower risk of developing AMI[adjusted hazard ratio(AHR)=0.71;95% confidence interval(95%CI):0.55-0.90],and those with scores≥5 had an even lower risk(AHR=0.37;95%CI:0.21-0.66).CONCLUSION Good quality of care can reduce the risk of AMI in patients with type 2 *** quality-of-care score developed in this study had a significant association with the risk of AMI and thus can be applied to guiding the care for these patients.

关键词： Acute myocardial infarction Cardiovascular disease Diabetes mellitus Quality-of-care Score

Teaching academic writing to medical professionals using computer communication media

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Teaching academic writing to medical professionals using com...

Attack Vulnerability of Network with Duplication-Divergence Mechanism

2012 International Symposium on Information Technologies in Medicine and Education(ITME2012)

作者： Yen-Cheng Tseng How-ran guo Department of Business Administration and Language Education Center Chang Jung Christian University Tainan Taiwan Department of Environmental and Occupational Medicine National Cheng Kung University College of Medicine and Hospital TainanTaiwan

ISBN: (纸本)9781467321099

Academic writing is an important skill of those medical professionals who wish to engage in education and *** addition,many medical professionals whose first language is not English need to learn academic writing in English because it is the dominant language in academic *** most universities in Taiwan,however,academic writing is not included in the undergraduate curriculum,and therefore most of the medical professionals began to learn academic writing after starting their *** professionals usually have busy schedules and need to do shift work,but learning to write in a second language is time consuming and needs a lot of *** learners can benefit from proof reading of the instructor,they can benefit even more if the instructor can guide them through the proof reading process and explain the reasons for *** study applied one of the most popular computer communication media,which has a desktop sharing function,to the teaching of academic writing and asked students report their *** comparison with face-to-face one-on-one teaching,students reported advantages including flexibilities in schedule and place,saving of traffic time,potential to broadcast to other students,no need for a classroom or office,and the option of making a recording for replaying and sharing with other *** the other hand,students reported limitations including the needs of equipment and access to network,interruptions of the connection,and bad quality of communication ***,medical professionals prefer this learning mode than face-to-face one-on-one learning.

关键词： academic writing medical professionals distance learning

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Communications in Theoretical Physics 2007年第4X期48卷 754-758页

作者： WANG Li YAN Jia-Ren LIU Zi-ran ZHANG Jian-guo Department of Physics Hunan Normal University Changsha 410081 China

We study the attack vulnerability of network with duplication-divergence mechanism. Numerical results have shown that the duplication-divergence network with larger retention probability a is more robust against target attack relatively. Furthermore, duplication-divergence network is broken down more quickly than its counterpart BA network under target attack. Such result is consistent with the fact of WWW and Internet networks under target attack. So duplication-divergence model is a more realistic one for us to investigate the characteristics of the world wide web in future. We also observe that the exponent γ of degree distribution and average degree are important parameters of networks, reflecting the performance of networks under target attack. Our results are helpful to the research on the security of network.

关键词： complex network systems attack vulnerability statistical dynamics