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DETERMINATION OF THE DYNAMIC STRESS INTENSITY FACTORS,K_Ⅰ~d AND K_Ⅱ~d,FOR A MIXED-MODE PROPAGATING CRACK 被引量:4
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作者 Liu Cheng (Department of Mechanics,Peking University) 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1989年第3期244-252,共9页
In this paper,the dynamic propagation problem of a mixed-mode crack was studied by means of the experimental method of caustics.The initial curve and caustic equations were derived un- der the mixed-mode dynamic condi... In this paper,the dynamic propagation problem of a mixed-mode crack was studied by means of the experimental method of caustics.The initial curve and caustic equations were derived un- der the mixed-mode dynamic condition.A multi-point measurement method for determining the dy- namic stress intensity factors,K_Ⅰ~d and K_Ⅱ~d,and the position of the crack tip was developed.Several other methods were adopted to check this method,and showed that it has a good precision.Finally, the dynamic propagating process of a mixed-mode crack in a three-point bending beam specimen was investigated with our method. 展开更多
关键词 caustic method stress intensity factor dynamic fracture
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Dynamic Variations and Influencing Factors of Groundwater Levels in Lhasa City 被引量:3
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作者 FANJi-hui LIUQiao +3 位作者 ZHANGYan CHENGGen-wei FANXiang-de LUWen-ming 《Wuhan University Journal of Natural Sciences》 EI CAS 2005年第4期665-673,共9页
This paper focuses on the dynamic variation of groundwater level in Lhasacity. According to the data, the obvious characteristic of the groundwater level of the city is thatit is changing seasonally. Lhasa is divided ... This paper focuses on the dynamic variation of groundwater level in Lhasacity. According to the data, the obvious characteristic of the groundwater level of the city is thatit is changing seasonally. Lhasa is divided into three districts according to hydrogeologicalconditions: the alluvial plain of the Lhasa-river, the alluvial plain of the Doilung-river, and thealluvial fan of inter mountain, which presents a downward trend, a slight upward trend and basicallystabilizing trend over the years individually. The analysis indicates that meteorological andhydrological factors lead to the obvious dynamic change of the groundwater level. However, more andmore human activities and over-exploitation of the groundwater cause the downward trend inthegroundwater level. 展开更多
关键词 LHASA groundwater level dynamic variation factor
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A fractional differential constitutive model for dynamic stress intensity factors of an anti-plane crack in viscoelastic materials 被引量:2
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作者 Run-Tao Zhan Zhao-Xia Li Lei Wang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2014年第3期403-409,共7页
Fractional differential constitutive relationships are introduced to depict the history of dynamic stress inten- sity factors (DSIFs) for a semi-infinite crack in infinite viscoelastic material subjected to anti-pla... Fractional differential constitutive relationships are introduced to depict the history of dynamic stress inten- sity factors (DSIFs) for a semi-infinite crack in infinite viscoelastic material subjected to anti-plane shear impact load. The basic equations which govern the anti-plane deformation behavior are converted to a fractional wave-like equation. By utilizing Laplace and Fourier integral transforms, the fractional wave-like equation is cast into an ordinary differential equation (ODE). The unknown function in the solution of ODE is obtained by applying Fourier transform directly to the boundary conditions of fractional wave-like equation in Laplace domain instead of solving dual integral equations. Analytical solutions of DSIFs in Laplace domain are derived by Wiener-Hopf technique and the numerical solutions of DSIFs in time domain are obtained by Talbot algorithm. The effects of four parameters α, β, b1, b2 of the fractional dif- ferential constitutive model on DSIFs are discussed. The numerical results show that the present fractional differential constitutive model can well describe the behavior of DSIFs of anti-plane fracture in viscoelastic materials, and the model is also compatible with solutions of DSIFs of anti-plane fracture in elastic materials. 展开更多
关键词 dynamic fracture Stress intensity factors Fractional differentiation - Anti-plane fracture Viscoelasticmaterial WIENER-HOPF
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Effects of dynamic ventilatory factors on ventilatorinduced lung injury in acute respiratory distress syndrome dogs 被引量:8
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作者 Rui-lan Wang Kan Xu +2 位作者 Kang-long Yu Xue Tang Hui Xie 《World Journal of Emergency Medicine》 CAS 2012年第4期287-293,共7页
BACKGROUND: Mechanical ventilation is a double-edged sword to acute respiratory distress syndrome (ARDS) including lung injury, and systemic inflammatory response high tidal volumes are thought to increase mortalit... BACKGROUND: Mechanical ventilation is a double-edged sword to acute respiratory distress syndrome (ARDS) including lung injury, and systemic inflammatory response high tidal volumes are thought to increase mortality. The objective of this study is to evaluate the effects of dynamic ventilatory factors on ventilator induced lung injury in a dog model of ARDS induced by hydrochloric acid instillation under volume controlled ventilation and to investigate the relationship between the dynamic factors and ventilator-induced lung injuries (VILI) and to explore its potential mechanisms.METHODS: Thirty-six healthy dogs were randomly divided into a control group and an experimental group. Subjects in the experimental group were then further divided into four groups by different inspiratory stages of flow. Two mL of alveolar fluid was aspirated for detection of IL-8 and TNF-α. Lung tissue specimens were also extracted for total RNA, IL-8 by western blot and observed under an electronic microscope.RESULTS: IL-8 protein expression was significantly higher in group B than in groups A and D. Although the IL-8 protein expression was decreased in group C compared with group B, the difference was not statistically significant. The TNF-a ray degree of group B was significantly higher than that in the other groups (P〈0.01), especially in group C (P〉0.05). The alveolar volume of subjects in group B was significantly smaller, and cavity infiltration and cell autolysis were marked with a significant thicker alveolar septa, disorder of interval structures, and blurring of collagenous and elastic fiber structures. A large number of necrotic debris tissue was observed in group B.CONCLUSION: Mechanical ventilation with a large tidal volume, a high inspiratory flow and a high ventilation frequency can cause significant damage to lung tissue structure. It can significantly increase the expression of TNF-α and IL-8 as well as their mRNA expression. Furthermore, the results of our study showed that small tidal ventilation significantly reduces the release of proinflammatory media. This finding suggests that greater deterioration in lung injury during ARDS is associated with high inspiratory flow and high ventilation rate. 展开更多
关键词 Acute respiratory distress syndrome dynamic factors Inspiratory flow Ventilator-induced lung injury
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Dynamic amplification factors for a system with multiple-degrees-of-freedom 被引量:4
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作者 Zhang Chao Hao Hong +1 位作者 Bi Kaiming Yan Xueyuan 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2020年第2期363-375,共13页
It is well-known that the responses of a structure are different when subjected to a static load or a sudden step load.The dynamic amplification factor(DAF),which is defined as the ratio of the amplitude of the vibrat... It is well-known that the responses of a structure are different when subjected to a static load or a sudden step load.The dynamic amplification factor(DAF),which is defined as the ratio of the amplitude of the vibratory response to the static response,is normally used to depict the dynamic effect.For a single-degree-of-freedom system(SDOF)subjected to a sudden dynamic load,the maximum value of DAF is 2.Many design guidelines therefore use 2 as an upper bound to consider the dynamic effect.For a civil engineering structure,which is normally a multiple-degrees-of-freedom(MDOF)system,the DAF may exceed 2 in certain circumstances.The adoption of 2 as the upper bond as suggested by the design guidelines therefore may lead to unsafe structural design.Very limited studies systematically investigate the DAF of a MDOF sysCorrespondence to:Bi Kaiming,Centre for Infrastructure Monitoring and Protection,School of Civil and Mechanical Engineering,Curtin University,Kent Street,Bentley WA 6102,Australia Tel:(+61)892665139 E-mail:kaiming.bi@curtin.edu.autem.This study theoretically investigates the DAF of a MDOF system when it is subjected to a step load based on the fundamental theory of structural dynamics.The condition on which the DAF may exceed 2 is defined.Two numerical examples and one experimental study of a cable-stayed bridge subjected to sudden cable loss are presented to illustrate the problem. 展开更多
关键词 dynamic AMPLIFICATION factors(DAF) multiple-degrees-of-freedom(MDOF) step load
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Influencing Factors and Dynamic Mechanism of Industrial Structure from the Perspective of Supply-side Reform 被引量:2
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作者 Deng GAO Shuhui SHAO 《Asian Agricultural Research》 2018年第12期37-40,共4页
The supply-side reform is an important measure for the high-quality development of China's economy in the new era. The purpose of this paper is to explore the mechanism and influence of technological progress,huma... The supply-side reform is an important measure for the high-quality development of China's economy in the new era. The purpose of this paper is to explore the mechanism and influence of technological progress,human capital,consumption demand,resource endowment and government intervention on the adjustment and upgrading of industrial structure,and to deepen the understanding of supply-side reform. 展开更多
关键词 Supply-side REFORM INDUSTRIAL structure Influencing factors dynamic mechanism
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Multi-factor dynamic analysis of the deformation of a coal bunker in a coal preparation plant 被引量:2
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作者 Shuangshuang Xiao Qing Yang +1 位作者 Guowei Dong Hongsheng Wang 《International Journal of Coal Science & Technology》 EI CAS CSCD 2021年第5期1067-1077,共11页
To assess the deformation of a coal bunker and propose effective preventative measures for such,a real-time monitoring system was designed.Moreover,methods were proposed for monitoring the coal-bunker inclination,sett... To assess the deformation of a coal bunker and propose effective preventative measures for such,a real-time monitoring system was designed.Moreover,methods were proposed for monitoring the coal-bunker inclination,settlement,groundwater level,temperature,and material level.By using a vector autoregression model and time-series data for the coal-bunker deformation,a long-term equilibrium relationship was derived between the coal-bunker inclination and settlement and their influencing factors.The dynamic effects of each factor on the coal-bunker inclination and settlement and how the contribution of each factor changes were revealed by using an impulse response function and variance decomposition.The results show that the coal-bunker inclination and settlement vary hysteretically.Groundwater level has constant and small negative effects on the coal-bunker inclination and settlement,and temperature has continuous and significant negative effects;however,material level has constant positive effects on the coal-bunker settlement and slightly influences the eastward inclination while significantly influencing the northward inclination of the coal bunker.Also,unbalanced loading has little influence on the coal-bunker settlement and eastward inclination but significant influence on its northward inclination.Therefore,monitoring of the coal-bunker deformation should be strengthened in summer,and sudden changes in material level and unbalanced loading should be avoided during production.Moreover,the coal-bunker inclination can be adjusted by unbalanced loading in the reverse direction. 展开更多
关键词 Coal bunker SETTLEMENT Influence factor dynamic analysis
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STUDY ON DYNAMIC STRESS INTENSITY FACTORS OF DISK WITH A RADIAL EDGE CRACK SUBJECTED TO EXTERNAL IMPULSIVE PRESSURE 被引量:1
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作者 Chen Aijun 《Acta Mechanica Solida Sinica》 SCIE EI 2007年第1期41-49,共9页
A dynamic weight function method is presented for dynamic stress intensity factors of circular disk with a radial edge crack under external impulsive pressure. The dynamic stresses in a circular disk are solved under ... A dynamic weight function method is presented for dynamic stress intensity factors of circular disk with a radial edge crack under external impulsive pressure. The dynamic stresses in a circular disk are solved under abrupt step external pressure using the eigenfunction method. The solution consists of a quasi-static solution satisfying inhomogeneous boundary conditions and a dynamic solution satisfying homogeneous boundary conditions. By making use of Fourier- Bessel series expansion, the history and distribution of dynamic stresses in the circular disk are derived. Furthermore, the equation for stress intensity factors under uniform pressure is used as the reference case, the weight function equation for the circular disk containing an edge crack is worked out, and the dynamic stress intensity factor equation for the circular disk containing a radial edge crack can be given. The results indicate that the stress intensity factors under sudden step external pressure vary periodically with time, and the ratio of the maximum value of dynamic stress intensity factors to the corresponding static value is about 2.0. 展开更多
关键词 circular disk cracks dynamic stress intensity factors dynamic weight function Fourier-Bessel series
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Analysis of dynamic stress intensity factors of thick-walled cylinder under internal impulsive pressure 被引量:3
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作者 Aijun Chen Lianfang Liao Dingguo Zhang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2009年第6期803-809,共7页
Dynamic stress intensity factors are evaluated for thick-walled cylinder with a radial edge crack under internal impulsive pressure. Firstly, the equation for stress intensity factors under static uniform pressure is ... Dynamic stress intensity factors are evaluated for thick-walled cylinder with a radial edge crack under internal impulsive pressure. Firstly, the equation for stress intensity factors under static uniform pressure is used as the reference case, and then the weight function for a thick-walled cylinder containing a radial edge crack can be worked out. Secondly, the dynamic stresses in uncracked thick-walled cylinders are solved under internal impulsive pressure by using mode shape function method. The solution consists of a quasi-static solution satisfying inhomogeneous boundary conditions and a dynamic solution satisfying homogeneous boundary condi- tions, and the history and distribution of dynamic stresses in thick-walled cylinders are derived in terms of Fourier-Bessel series. Finally, the dynamic stress intensity factor equations for thick-walled cylinder containing a radial edge crack sub- jected to internal impulsive pressure are given by dynamic weight function method. The finite element method is utilized to verify the results of numerical examples, showing the validity and feasibility of the proposed method. 展开更多
关键词 Thick-walled cylinder . Cracks .dynamic stress intensity factors . Weight function methodMode shape function
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Dynamic characteristics and influencing factors of CO_(2) huff and puff in tight oil reservoirs 被引量:3
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作者 TANG Xiang LI Yiqiang +7 位作者 HAN Xue ZHOU Yongbing ZHAN Jianfei XU Miaomiao ZHOU Rui CUI Kai CHEN Xiaolong WANG Lei 《Petroleum Exploration and Development》 CSCD 2021年第4期946-955,共10页
CO_(2)huff and puff experiments of different injection parameters,production parameters and soaking time were carried out on large-scale cubic and long columnar outcrop samples to analyze dynamic characteristics and i... CO_(2)huff and puff experiments of different injection parameters,production parameters and soaking time were carried out on large-scale cubic and long columnar outcrop samples to analyze dynamic characteristics and influencing factors of CO_(2)huff and puff and the contribution of sweeping mode to recovery.The experimental results show that the development process of CO_(2)huff and puff can be divided into four stages,namely,CO_(2)backflow,production of gas with some oil,high-speed oil production,and oil production rate decline stages.The production of gas with some oil stage is dominated by free gas displacement,and the high-speed oil production stage is dominated by dissolved gas displacement.CO_(2)injection volume and development speed are the major factors affecting the oil recovery.The larger the injected CO_(2)volume and the lower the development speed,the higher the oil recovery will be.The reasonable CO_(2)injection volume and development speed should be worked out according to oilfield demand and economic evaluation.There is a reasonable soaking time in CO_(2)huff and puff.Longer soaking time than the optimum time makes little contribution to oil recovery.In field applications,the stability of bottom hole pressure is important to judge whether the soaking time is sufficient during the huff period.The oil recovery of CO_(2)huff and puff mainly comes from the contribution of flow sweep and diffusion sweep,and diffusion sweep contributes more to the oil recovery when the soaking time is sufficient. 展开更多
关键词 tight oil CO_(2)huff and puff dynamic characteristics oil recovery influencing factors oil-displacement mechanism
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Granular dynamic shear strength and its influencing factors 被引量:1
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作者 吴爱祥 孙业志 《Journal of Central South University of Technology》 2002年第1期36-40,共5页
The granular dynamic shear strength is the same as that of the static one in nature, as found from numerous experiments and investigations. The shear strength is equal to the sum of the internal frictional force and t... The granular dynamic shear strength is the same as that of the static one in nature, as found from numerous experiments and investigations. The shear strength is equal to the sum of the internal frictional force and the cohesive force. The influences of type, shape, size distribution, pore ratio, moisture content and variation of vibration velocity on the dynamic shear strength of granules were studied. Based on numerous vibration shear experiments, the authors investigate the mechanism of dynamic shear strength in granules in terms of the fundamental principle and the relevant theory of modern tribology. 展开更多
关键词 dynamic shear strength GRANULES influencing factor MECHANISM
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Effects of three-body interaction on dynamic and static structure factors of an optically-trapped Bose gas
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作者 漆伟 梁兆新 张志东 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第9期292-297,共6页
We investigate how three-body interactions affect the elementary excitations and dynamic structure factor of a Bose- Einstein condensate trapped in a one-dimensional optical lattice. To this end, we numerically solve ... We investigate how three-body interactions affect the elementary excitations and dynamic structure factor of a Bose- Einstein condensate trapped in a one-dimensional optical lattice. To this end, we numerically solve the Gross-Pitaevskii equation and then the corresponding Bogoliubov equations. Our results show that three-body interactions can change both the Bogoliubov band structure and the dynamical structure factor dramatically, especially in the case of the two-body interaction being relatively small. Furthermore, when the optical lattice is strong enough, the analytical results, combined with the sum-rule approach, help us to understand that: the effects of three-body interactions on the static structure Ihctor can be significantly amplified by an optical lattice. Our predictions should be observable within the current Bragg spectroscopy experiment. 展开更多
关键词 dynamic structure factor three-body interaction optical lattice
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Analysis of dynamic stress intensity factors of three-point bend specimen containing crack
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作者 陈爱军 曹俊俊 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2011年第2期203-210,共8页
A new formula is obtained to calculate dynamic stress intensity factors of the three-point bending specimen containing a single edge crack in this study. Firstly, the weight function for three-point bending specimen c... A new formula is obtained to calculate dynamic stress intensity factors of the three-point bending specimen containing a single edge crack in this study. Firstly, the weight function for three-point bending specimen containing a single edge crack is derived from a general weight function form and two reference stress intensity factors, the coefficients of the weight function are given. Secondly, the history and distribution of dynamic stresses in uncracked three-point bending specimen are derived based on the vibration theory. Finally~ the dynamic stress intensity factors equations for three-pointing specimen with a single edge crack subjected to impact loadings are obtained by the weight function method. The obtained formula is verified by the comparison with the numerical results of the finite element method (FEM). Good agreements have been achieved. The law of dynamic stress intensity factors of the three-point bending specimen under impact loadings varing with crack depths and loading rates is studied. 展开更多
关键词 CRACK dynamic stress intensity factor weight function method three-pointbending specimen loading rate
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Dynamic Characteristics and Influencing Factors of Groundwater Level in Qianyang County
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作者 Zhao Dan Zhou Qi Jing Yanxia 《Meteorological and Environmental Research》 CAS 2016年第4期44-49,共6页
The dynamic characteristics and influencing factors of groundwater level in Qianyang County were analyzed.The results showed that in the south bank of the Qianhe River,the change of groundwater level was mainly affect... The dynamic characteristics and influencing factors of groundwater level in Qianyang County were analyzed.The results showed that in the south bank of the Qianhe River,the change of groundwater level was mainly affected by precipitation,and the response of the groundwater level to the change of precipitation was one year later.The groundwater level presented a downward trend on the whole.In the north bank of the Qianhe River,the supply source of the groundwater level included precipitation and hydrology,and the groundwater level showed a rising trend on the whole.In the plain area,there was a sudden change in the groundwater level under the control of human activities.In a word,the main factors influencing the groundwater level in various geological conditions were different,so there were great differences between various regions in the dynamic characteristics of the groundwater level in Qianyang County. 展开更多
关键词 GROUNDWATER LEVEL dynamic CHARACTERISTICS Influencing factors Qianyang COUNTY China
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Dynamic change of agricultural energy efficiency and its influencing factors in China
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作者 Haipeng Li Li Luo +1 位作者 Xiong Zhang Junbiao Zhang 《Chinese Journal of Population,Resources and Environment》 2021年第4期311-320,共10页
In order to practice the concept of‘lucid waters and lush mountains are invaluable assets’and promote the green development of agriculture,it is necessary to improve the efficiency of agricultural energy utilization... In order to practice the concept of‘lucid waters and lush mountains are invaluable assets’and promote the green development of agriculture,it is necessary to improve the efficiency of agricultural energy utilization.Based on the panel data of 28 provinces from 1995 to 2018,this paper calculated China’s agricultural energy input from two categories of direct energy and indirect energy,and used EBM(Epsilon-based Measure)mixed distance function model to measure the energy efficiency of agriculture in China.The nuclear density function and spatial autocorrelation were used to analyze the dynamic evolution of agricultural energy efficiency,and the dynamic panel model was used to analyze the influencing factors of agricultural energy efficiency.The results showed that:①From 1995 to 2018,the total agricultural energy input had increased year by year in China,with an average annual growth rate of 2%.Energy input structure changed from indirect energy-based to direct energy-based.Agricultural energy efficiency showed an evolutionary trend of‘rising-stagnating-rising rapidly’in China.The agricultural energy efficiency was generally low in China,and there was a large space for improvement in agricultural energy efficiency.②From 1995 to 2018,the average annual growth rate of agricultural energy efficiency in the eastern,central and western regions was 2.7%,1.9%and 1.4%respectively.In 2018,the agricultural energy efficiency in the eastern,central and western regions was 0.81,0.71 and 0.59 respectively.The gap between regions was expanding rapidly,and the agricultural energy efficiency in the central and western regions needed to be improved.③From 1995 to 2018,the agricultural energy efficiency of each province was polarized and the absolute gap was widened.There was obvious improvement in agricultural energy efficiency in Guangdong,Shandong,Jiangxi,Jiangsu,Liaoning and Tianjin,while the agricultural energy efficiency of Xinjiang,Guizhou,Zhejiang,Shanghai,and Inner Mongolia deteriorated.④From 1995 to 2018,there was no global spatial correlation of China’s agricultural energy efficiency.However,local‘high-high’concentration gradually appeared in the eastern region since 2010.⑤The first lag of energy efficiency had a significant positive impact on agricultural energy efficiency,and agricultural energy efficiency improvement had a time lag.The level of human capital,per capita net income of farmers and the level of urbanizaton had a significant positive impact on agricultural energy efficiency.The disaster rate,the level of development of secondary and tertiary industries,and the level of opening up had a significant negative impact on agricultural energy efficiency.In the implementation of the strategy of rural revitalization,we should focus on the central and western regions,take the cultivation of professional farmers as the key,focus on improving agricultural production conditions,enhance the level of cooperation between regions,exert the leading role of the secondary and tertiary industries,and enhance the ability of agricultural disaster prevention and mitigation. 展开更多
关键词 EBM model dynamic panel model Agricultural energy efficiency dynamic change Influencing factor
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Investigating the Effect of Weather and Seasonal Factors on Root Stability Using Dynamic Measurements
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作者 Shadabeh Fathi Laszlo Bejo Ferenc Divos 《Open Journal of Forestry》 2020年第1期124-134,共11页
The dynamic tree stability assessment technique allows trees to be measured efficiently, under realistic weather conditions. In this study, the stability of four trees, including two conifers and two broad-leaved spec... The dynamic tree stability assessment technique allows trees to be measured efficiently, under realistic weather conditions. In this study, the stability of four trees, including two conifers and two broad-leaved species was assessed in the Botanical Gardens of the University of Sopron, Hungary. The examined trees included Horse chestnut, Japanese zelkova, Douglas fir and Giant sequoia. Each tree was measured in various weather and seasonal conditions. Results show that the seasons affected the stability of broadleaved trees significantly, due to considerable changes in the crown surface area, while this difference was much lower in softwoods. Rainy weather loosens the topsoil, which adversely affects the stability of trees with relatively shallow roots. Lower layers take longer to saturate, and therefore trees with very deep roots are usually unaffected by the looser topsoil, while the increased weight of the top layer compacts the lower layers and improves stability, as evidenced by results measured on Sequoia. Snow accumulation on the branches increases the inertia of the tree, which imposes higher torque on the root collar, decreasing stability. In the meantime, the increased resistance offered by frozen ground stabilizes the tree, which more-or-less counterbalances this effect. A more extensive database of tree stability under different conditions is being built to allow for more comprehensive analysis of various factors, like wind direction, tree health and morphology, shading, etc. 展开更多
关键词 Tree STABILITY dynamic STABILITY Assessment Safety factor WIND Direction Precipitation FOLIAGE Critical WIND Pressure
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Spatiotemporal Dynamics of Green Total-factor Water-use Efficiency and Its Influencing Factors in China
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作者 MA Dalai ZHANG Fengtai +3 位作者 GAO Lei YANG Guangming YANG Qing AN Youzhi 《Chinese Geographical Science》 SCIE CSCD 2021年第5期795-814,共20页
In this study,we developed an evaluation index system for green total-factor water-use efficiency(GTFWUE)which reflected both economic and green efficiencies of water resource utilization.Then we measured the GTFWUE o... In this study,we developed an evaluation index system for green total-factor water-use efficiency(GTFWUE)which reflected both economic and green efficiencies of water resource utilization.Then we measured the GTFWUE of 30 provinces/municipalities/autonomous regions(hereafter provinces)in China(not including Tibet,Hong Kong,Macao,Taiwan as no data)from 2000 to 2018 using a minimum distance to the strong frontier model that contained an undesirable output.We further analyzed the regional differences and spatial correlations of GTFWUE using these values based on Global and Local Moran’s I statistics,and empirically determined the factors affecting GTFWUE using a spatial econometric model.The evaluation results revealed that the GTFWUE differed substantially between the regions.The provinces with high and low GTFWUE values were located in the coastal and inland areas of China,respectively.The eastern region had a significantly higher GTFWUE than the central and western regions.The GTFWUEs for all three regions(eastern,central,and western regions)decreased slowly from 2000 to 2011(except 2005),remained stable from 2012 to 2016,and rapidly increased in 2017 before decreasing again in 2018.We found significant spatial correlations between the provincial GTFWUEs.The GTFWUE for most provinces belonged to the high-high or low-low cluster region,revealing a significant spatial clustering effect of provincial GTFWUEs.We also found that China’s GTFWUE was highly promoted by economic growth,population size,opening-up level,and urbanization level,and was evidently hindered by water endowment,technological progress,and government influence.However,the water-use structure had little impact on GTFWUE.This study fully demonstrated that the water use mode would be improved,and water resources needed to be used more efficiently and green in China.Moreover,based on the findings of this study,several policy recommendations were proposed from the aspects of cross-regional cooperation,economy,society,and institution. 展开更多
关键词 green total-factor water-use efficiency(GTFWUE) spatiotemporal dynamics water scarcity influencing factors spatial econometric model
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Effect of crack face contact on dynamic stress intensity factors for a hole-edge crack
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作者 盖秉政 王立清 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第2期194-197,共4页
In order to determine the dynamic stress intensity factors(DSIFs)for a single edge crack at the center hole of a finite plate under a compressive step loading parallel to the crack,the finite element method was employ... In order to determine the dynamic stress intensity factors(DSIFs)for a single edge crack at the center hole of a finite plate under a compressive step loading parallel to the crack,the finite element method was employed to solve the cracked plate problem.The square-root stress singularity around the crack tip was simulated by quarter point singular elements collapsed by 8-node two-dimensional isoparametric elements.The DSIFs with and without considering crack face contact situations were evaluated by using the displacement correlation technique,and the influence of contact interaction between crack surfaces on DSIFs was investigated.The numerical results show that if the contact interaction between crack surfaces is ignored,the negative mode I DSIFs may be obtained and a physically impossible interpenetration or overlap of the crack surfaces will occur.Thus the crack face contact has a significant influence on the mode I DSIFs. 展开更多
关键词 CRACK contact interaction dynamic stress intensity factors (DSIFs) finite element method
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FINITE ELEMENT METHOD COMBINED WITH DYNAMIC PHOTOELASTIC ANALYSIS TO DETERMINE DYNAMIC STRESS-INTENSITY FACTORS
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作者 宁杰 钱伟长 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1989年第10期909-914,共6页
The present paper is addressed to the finite element method combined with dynamic photoelastic analysis of propagating cracks, that is, on the basis of [1] by Chien Wei-zang, finite elements which incorporate the prop... The present paper is addressed to the finite element method combined with dynamic photoelastic analysis of propagating cracks, that is, on the basis of [1] by Chien Wei-zang, finite elements which incorporate the propagating crack-tip singularity intrinsic to two-dimensional elasticity are employed. THe relation between crack opening length and time step obtained from dynamic photoelaslie analysis is used as a definite condition for solving the dynamic equations and simulating the crack propagations as well As an example, the impact response of dynamie-bending-test specimen is investigated and the dynamic stress-intensity factor obtained from the mentioned finite element analysis and dynamic photoelasticity is in reasonable agreement with each other. 展开更多
关键词 FINITE ELEMENT METHOD COMBINED WITH dynamic PHOTOELASTIC ANALYSIS TO DETERMINE dynamic STRESS-INTENSITY factors LENGTH
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Effects of edaravone combined with hyperbaric oxygen on cerebral vascular dynamics, oxidative stress products and inflammatory factors in patients with acute cerebral hemorrhage
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作者 Xia Li Lan Xiong +1 位作者 Ling Li Zi-Lian Fan 《Journal of Hainan Medical University》 2017年第20期126-129,共4页
Objective: To investigate the effect of edaravone combined with hyperbaric oxygen therapy on cerebral vasculature, oxidative stress and inflammatory cytokines in patients with acute cerebral hemorrhage (ACH). Methods:... Objective: To investigate the effect of edaravone combined with hyperbaric oxygen therapy on cerebral vasculature, oxidative stress and inflammatory cytokines in patients with acute cerebral hemorrhage (ACH). Methods: A total of 96 patients with ACH were divided into control group (n=48) and observation group (n=48) according to the random number table. Both groups were treated routinely. On this basis, the control group was treated with edaravone injection, and the observation group was treated with edaravone injection combined with hyperbaric oxygen therapy. The change of cerebrovascular dynamics, oxidative stress products and inflammatory factors were examined in all subjects before and after treatment. Results: There were no significant differences in cerebrovascular function between the two groups before treatment. After treatment, the levels of Vmean and Qmean in both groups were significantly higher than those before treatment. The levels of Vmean and Qmean in the observation group were higher than those of the control group after treatment. There was no significant difference in serum oxidative stress between the two groups before treatment. After treatment, the levels of SOD in two groups were significantly higher than those before treatment. The level of SOD in the observation group was higher than that in the control group after treatment. After treatment, the levels of MDA in the two groups were significantly lower than that before treatment. The level of MDA in the observation group was lower than that of the control group after treatment. There were no significant differences in the level of serum inflammatory factors between the two groups before treatment. After treatment, the level of TNF-α and IL-1β in two groups were significantly lower than before treatment. The level of TNF-α and IL-1β in the observation group was lower than those of the control group after treatment. Conclusion:Edaravone combined with hyperbaric oxygen therapy can effectively improve cerebral vascular dynamics, reduce oxidative stress and inflammatory response in patients with ACH, which is beneficial to the prognosis of patients. 展开更多
关键词 Acute CEREBRAL HEMORRHAGE EDARAVONE HYPERBARIC Oxygen CEREBRAL VASCULAR dynamicS Oxidative Stress Inflammatory factor
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