In-situ SEM (Scanning Electron Microscope) observation of fatigue crack propagation in aluminium alloys reveals that crack growth occurs in a continuous way over the time period during the load cycle. Based on this ob...In-situ SEM (Scanning Electron Microscope) observation of fatigue crack propagation in aluminium alloys reveals that crack growth occurs in a continuous way over the time period during the load cycle. Based on this observation, a new parameter da/dS is introduced to describe the fatigue crack propagation rate, which defines the fatigue crack propagation rate with the change of the applied stress at any moment of a stress cycle. The relationship is given between this new parameter and the conventional used parameter da/dN which describes the fatigue crack propagation rate per stress cycle. Using this new parameter, an analysis has been performed and a model has been set up to consider the effect of the applied stress ratio on the fatigue crack propagation rate. The obtained results have been used to correlate the published test data and a good correlation has been achieved. This method is very easy to use and no fatigue crack closure measurement is needed, therefore this model is significant in engineering application.展开更多
As natural ecosystems provide the material basis and fundamental support for regional sustainable devel-opment,the sustainability of natural ecosystems is an important prerequisite and a viable approach for the achiev...As natural ecosystems provide the material basis and fundamental support for regional sustainable devel-opment,the sustainability of natural ecosystems is an important prerequisite and a viable approach for the achievement of regional sustainable development.It is also the final criteria to assess whether sustainable development paradigm is successful.Along with the increasing impacts of human activities on natural ecosystems,the evaluation of regional ecological sustainability has become one of the key issues for research on macro ecology and sustainable development.Based on different unit of indicators,this study firstly groups the evaluation frameworks of regional ecological sus-tainability into three major types:comprehensive index evaluation with dimensionless unit,monetary valuation,and biophysical quantity measurement.We then discuss and compare these types in terms of basic principles,scope of ap-plications,advantages and shortcomings.Finally,drawn on the discussion about characteristics of ecological sustain-ability,we outline the current trend and future directions of regional ecological sustainability evaluation,for instance,transition from sustainable development evaluation to sustainability science,integration of goal-oriented and problem-solving approaches,combination of spatial pattern analysis and ecological sustainability evaluation,and en-hancement of ecological sustainability evaluation at landscape scale.展开更多
China＇s circular economy is still at the initial stage, whose development has many difficulties and problems requir- ing immediate resolution theoretically and practically. Due to the differences of regions on the sc...China＇s circular economy is still at the initial stage, whose development has many difficulties and problems requir- ing immediate resolution theoretically and practically. Due to the differences of regions on the scale of land, endowment of resources, economic basis and cultural background, the devel- opmental levels and capabilities of circular economy are inevi- tably different. Based on establishing the indicator system for assessing the developmental level of regional circular economy, spatial variation of China＇s circular economy is measured by the quantitative measurement using principal component analysis, and the existing problems are also analyzed and discussed. On one hand, the differences of the development capability of the circular economy of different provinces （cities） are profound in China; （!）Difference between the first category （strong） and the second category （relatively strong） is 1.1264 points. Difference between the second category and the third category （relatively weak） is 0.3867 points. Difference between the third category and the fourth category （weak） is 1.0238 points. Differencebetween the tlrst category and the tourtla category reaches up to 2.0869 points. Average difference between the area where the developmental level of circular economy is relatively strong and the area where the developmental level of circular economy is relatively weak is 1.3617 points. （~）The differences of the dis- tribution of the areas, with different development capability of circular economy, which are located in the three economic regions of China, are also profound. The regions with a relatively strong development capability of circular economy are mainly located in the eastern economic area, which account for 22.58% of the whole regions, while only account for 12.90% in the middle and western economic areas. On the contrary, the regions with a relatively weak development capability of circular economy account for 48.39% in the middle and western area, while ac- count for 16.13% in the eastern area. On the other hand, among regions with different development capability of circular econ- omy, the regions with a relatively weak development capability of circular economy are in a dominant position, which accountfor 64.52% of all the provinces （cities）, which indicates that the development of the China＇s circular economy still has a long way to go. Though certain achievements have been made in the development of China＇s circular economy, in general, there are still some obstacles to be tacked in the development of China＇s circular economy which require the economic, legal and administrative methods.展开更多
This paper is a two-year empirical investigation of cultivating students' autonomous learning capacity in College English teaching at Shanxi University of Finance and Economics (SUFE). The goal of the study is to ...This paper is a two-year empirical investigation of cultivating students' autonomous learning capacity in College English teaching at Shanxi University of Finance and Economics (SUFE). The goal of the study is to optimize students' language learning and to find a new direction of teaching innovation. The paper analyzes the current teaching context and presents a critical review of the literature on learner autonomy. The author explores understanding of learner autonomy in Chinese context and produces an autonomous learning model in the experimental study. The paper presents some strategies for fostering autonomy such as instructing students how to learn, level-based teaching and collaborative learning. It was found that only by encouraging greater learner autonomy can students raise their English learning effectiveness.展开更多
基金the National Natural Science Foundation of China (Grant No. 10772063, 10572068, and 10772064)
文摘In-situ SEM (Scanning Electron Microscope) observation of fatigue crack propagation in aluminium alloys reveals that crack growth occurs in a continuous way over the time period during the load cycle. Based on this observation, a new parameter da/dS is introduced to describe the fatigue crack propagation rate, which defines the fatigue crack propagation rate with the change of the applied stress at any moment of a stress cycle. The relationship is given between this new parameter and the conventional used parameter da/dN which describes the fatigue crack propagation rate per stress cycle. Using this new parameter, an analysis has been performed and a model has been set up to consider the effect of the applied stress ratio on the fatigue crack propagation rate. The obtained results have been used to correlate the published test data and a good correlation has been achieved. This method is very easy to use and no fatigue crack closure measurement is needed, therefore this model is significant in engineering application.
基金Under the auspices of National Natural Science Foundation of China (No.40635028,40801066)State Key Laboratory of Earth Surface Processes and Resource Ecology of China (No.2008-KF-04)
文摘As natural ecosystems provide the material basis and fundamental support for regional sustainable devel-opment,the sustainability of natural ecosystems is an important prerequisite and a viable approach for the achievement of regional sustainable development.It is also the final criteria to assess whether sustainable development paradigm is successful.Along with the increasing impacts of human activities on natural ecosystems,the evaluation of regional ecological sustainability has become one of the key issues for research on macro ecology and sustainable development.Based on different unit of indicators,this study firstly groups the evaluation frameworks of regional ecological sus-tainability into three major types:comprehensive index evaluation with dimensionless unit,monetary valuation,and biophysical quantity measurement.We then discuss and compare these types in terms of basic principles,scope of ap-plications,advantages and shortcomings.Finally,drawn on the discussion about characteristics of ecological sustain-ability,we outline the current trend and future directions of regional ecological sustainability evaluation,for instance,transition from sustainable development evaluation to sustainability science,integration of goal-oriented and problem-solving approaches,combination of spatial pattern analysis and ecological sustainability evaluation,and en-hancement of ecological sustainability evaluation at landscape scale.
基金Major Project of National Social Fund (GrantNo.06&ZD038)Program of Science and Technology Development Plan of Jilin Province (Grant No. 20110655)part of research results of NENU Scholar Training Program of Youthful Academic Backbone
文摘China＇s circular economy is still at the initial stage, whose development has many difficulties and problems requir- ing immediate resolution theoretically and practically. Due to the differences of regions on the scale of land, endowment of resources, economic basis and cultural background, the devel- opmental levels and capabilities of circular economy are inevi- tably different. Based on establishing the indicator system for assessing the developmental level of regional circular economy, spatial variation of China＇s circular economy is measured by the quantitative measurement using principal component analysis, and the existing problems are also analyzed and discussed. On one hand, the differences of the development capability of the circular economy of different provinces （cities） are profound in China; （!）Difference between the first category （strong） and the second category （relatively strong） is 1.1264 points. Difference between the second category and the third category （relatively weak） is 0.3867 points. Difference between the third category and the fourth category （weak） is 1.0238 points. Differencebetween the tlrst category and the tourtla category reaches up to 2.0869 points. Average difference between the area where the developmental level of circular economy is relatively strong and the area where the developmental level of circular economy is relatively weak is 1.3617 points. （~）The differences of the dis- tribution of the areas, with different development capability of circular economy, which are located in the three economic regions of China, are also profound. The regions with a relatively strong development capability of circular economy are mainly located in the eastern economic area, which account for 22.58% of the whole regions, while only account for 12.90% in the middle and western economic areas. On the contrary, the regions with a relatively weak development capability of circular economy account for 48.39% in the middle and western area, while ac- count for 16.13% in the eastern area. On the other hand, among regions with different development capability of circular econ- omy, the regions with a relatively weak development capability of circular economy are in a dominant position, which accountfor 64.52% of all the provinces （cities）, which indicates that the development of the China＇s circular economy still has a long way to go. Though certain achievements have been made in the development of China＇s circular economy, in general, there are still some obstacles to be tacked in the development of China＇s circular economy which require the economic, legal and administrative methods.
文摘This paper is a two-year empirical investigation of cultivating students' autonomous learning capacity in College English teaching at Shanxi University of Finance and Economics (SUFE). The goal of the study is to optimize students' language learning and to find a new direction of teaching innovation. The paper analyzes the current teaching context and presents a critical review of the literature on learner autonomy. The author explores understanding of learner autonomy in Chinese context and produces an autonomous learning model in the experimental study. The paper presents some strategies for fostering autonomy such as instructing students how to learn, level-based teaching and collaborative learning. It was found that only by encouraging greater learner autonomy can students raise their English learning effectiveness.
