When observing China's income distribution problems .from an international perspective, we find that China's income inequality is not much different from developed countries after primary distribution. The real diff...When observing China's income distribution problems .from an international perspective, we find that China's income inequality is not much different from developed countries after primary distribution. The real difference between China and developed countries is that income inequality in developed countries will reduce greatly after income redistribution while the income inequality remains the same for China. Therefore, one can conclude that income inequality in China derives from the ineffectiveness of redistribution. However, a large income gap is not the main reason for skewed income distribution in China. In fact, the problem lies in unfair distribution resulting from factor capitalization. A handful of people have taken proceeds from public assets at the expense of all the people, which has led to social poIarization. To remove unfair distribution, China should improve its means of redistribution to narrow its income gap in order to develop a fair and reasonable pattern of income distribution.展开更多
Spatial distribution patterns are associated with life history and behavioral adaptations of animals. For studying the spatial distribution pattern of the steppe toad-headed lizard(Phrynocephalus frontalis) and its in...Spatial distribution patterns are associated with life history and behavioral adaptations of animals. For studying the spatial distribution pattern of the steppe toad-headed lizard(Phrynocephalus frontalis) and its influencing factors,we conducted experiments in Hunshandake Sandy Land in Inner Mongolia,China in July 2009. By calculating the clustered indices,we found that the lizard was aggregately distributed when the sampling quadrat was smaller than 10 m × 10 m,and uniformly distributed when it was greater than 10 m × 10 m. The Nearest Neighbor Rule showed a clustering distribution pattern for P. frontalis and the distribution pattern was quadrat-sampling dependent. Furthermore,the cluster was determined by environmental factors when the sampling quadrat was smaller than 20 m × 20 m,but it was determined by both environmental factors and characteristics of the lizard when it was larger than 20 m × 20 m. Our results suggested that the steppe toad-headed lizards tended to aggregate into suitable habitat patches in desert areas. Additionally,we discussed that the lizard aggregation could be potentially used as an indictor of movement of sand dunes.展开更多
This paper analyzes the impact of income distribution gap on consumption demand from a theoretical view,and draws the conclusion that there is an inverse relationship between income distribution gap and consumption de...This paper analyzes the impact of income distribution gap on consumption demand from a theoretical view,and draws the conclusion that there is an inverse relationship between income distribution gap and consumption demand.Then,the paper finds that the existing widening income distribution gap in China has a negative impact on consumption demand,but this is not the key factor for the insufficient consumption demand because of the low level of per capital income.At last,it suggests that governments should improve the income level of entire residents and adjust income distribution structure simultaneously.展开更多
The exploitation of mineral resources plays an important role in promoting national economic development. Mining is an essential component of China's industrial economy. Using grey correlation method to analyze th...The exploitation of mineral resources plays an important role in promoting national economic development. Mining is an essential component of China's industrial economy. Using grey correlation method to analyze the correlative effect of mineral resources exploitation to relevant industries, using national income method to calculate the pulling effect of mineral resources exploitation to economic growth and using graphs as well as tables to analyze the income distribution effect, the article obtains active economic effect of mineral resources development in Bijie, Guizhou. Moreover, from the view of resources-cored effect, the article analyzes negative effects such as single industrial structure brought by mineral resource development. Through analysis, we find that mineral resources exploitation to some extent brings active effects including gross domestic product growth, local financial revenue growth and relevant industries development; however, its negative effects should not be ignored. The negative effect can be lightened by diversifying industrial structure and prolonging industrial chain.展开更多
Based on a theoretic hypothesis that income inequality has both positive and negative effect on economic growth, this paper analyzes the influence of income distribution differences on economic growth of China by esta...Based on a theoretic hypothesis that income inequality has both positive and negative effect on economic growth, this paper analyzes the influence of income distribution differences on economic growth of China by establishing a multivariate linear regression model. The influence of income distribution difference on the economic growth of China changes with the change of time. During a short period immediately after China implemented reform and opening up policy, income inequality has a positive influence on the economic growth of China. However, along with the passing of time, such positive influence has become weaker and weaker and even convertes into negative effective. This paper proposes several advices with policy to restrain the difference of income distribution from expanding and weaken its negative effect on economic growth of China.展开更多
In this paper,based on the process data of evaluating the benchmark land prices of collective construction land and agricultural land,the score of influencing factors is calculated,and a regression model between value...In this paper,based on the process data of evaluating the benchmark land prices of collective construction land and agricultural land,the score of influencing factors is calculated,and a regression model between value-added benefits and influencing factors is established.According to the contribution of the government and collectives to value-added benefits,the distribution proportions of different purposes and levels are calculated.The research results show that there are significant differences in the distribution proportion of value-added income among different levels.The government distribution proportion decreases with the decrease of level,while the collective distribution proportion increases with the decrease of level.For each level of decrease in commercial service industry land and industrial and mining warehousing industry land,the government distribution proportion decreases by an average of 2.66%and 2.34%,while the collective distribution proportion increases by an average of 2.66%and 2.34%,respectively.The average distribution proportion of the government in the value-added income of commercial service industry land is 31.58%,which is much higher than the average income of 23.68%in the value-added income of industrial and mining warehousing industry land.展开更多
On the basis of extending Lee's(1999) model, this paper resolves the problem of biased division in the specification of equation and employs Urban Household Survey(UHS) data,China Household Income Project(CHIP) da...On the basis of extending Lee's(1999) model, this paper resolves the problem of biased division in the specification of equation and employs Urban Household Survey(UHS) data,China Household Income Project(CHIP) data and county-level minimum wage data collected by authors to investigate the wage distribution effects of change in the effective minimum wages measured by relative value. The result shows that the effective minimum wage will exert a significant spillover effect on wage distribution at the40 th percentile and below, which is favorable to reducing wage gaps at the bottom. This conclusion holds true under various robustness tests. However, the shrinking effective minimum wage has created a downward drag on wages, thus widening wage gaps at the bottom. The shrinking effective minimum wage contributed 150%,53.8%,45.5% and16.7% to the wage gaps at the 10 th, 20 th, 30 th and 40 th percentiles compared with the 50 th percentile. Therefore, the key to ensuring the effectiveness of minimum wages lies in the implementation of an automatic adjustment mechanism correlated with macroeconomic indicators. Compliance with minimum wages must be guaranteed and change in minimum wages must be measured with relative value.展开更多
We present calculations and improvement inspired by the work of Lorenzo Zaninetti, published in 2020, it concerns a problem whose origin dates back 1911 with so called Maxwell-Jüttner distribution these lies on t...We present calculations and improvement inspired by the work of Lorenzo Zaninetti, published in 2020, it concerns a problem whose origin dates back 1911 with so called Maxwell-Jüttner distribution these lies on the Lorentz factor , with . This work uses powerful modern software for a reconstruction of Zaninetti work, which computes with special functions, these are included in the Mathematica software, as by instance Bessel and Meijer G-functions ready to manipulate. A progress is made, it is possible to perform an integral that is not computed in Zaninetti paper. This author connects the correct relativistic probability law: the Maxwell-Jüttner to the synchrotron emissivity with a magnetic B field, this work generalize these results, using the linear Stark effect and deals with an electric field E.展开更多
The paper makes a comparative review and evaluation of different theories on impacts of the distribution of labor and capital income on economic growth as well as criticism of the mainstream theories and suggests usin...The paper makes a comparative review and evaluation of different theories on impacts of the distribution of labor and capital income on economic growth as well as criticism of the mainstream theories and suggests using Bhaduri-Marglin model as the theoretical basis for relevant research. By formulating the econometric model and analyzing time series data from 1978 to 2012, the paper makes an empirical research into the impact of labor share on economic growth in China. It has discovered that the positive effect of labor share on consumption demand growth in China outweighs its negative effect on investment and net export growth, concluding that growth in China is wage-led at present. That may mean that (1) increasing labor share promotes growth and the goals of equality and efficiency supports each other," (2) the demand and optimizing structure" lies in regulation tools. key to "stabilizing growth, expanding domestic establishing a set of pro-labor institution and展开更多
The paperfocuses on an analysis of the results of long-term monitoring of the concentrations of 137Cs, 90Sr and 3H in hydrosphere in the vicinity of Temelín Nuclear Power Plant (Temelín plant). The radionucl...The paperfocuses on an analysis of the results of long-term monitoring of the concentrations of 137Cs, 90Sr and 3H in hydrosphere in the vicinity of Temelín Nuclear Power Plant (Temelín plant). The radionuclides were monitored in surface water, river sediments, aquatic flora and fish species. The main objective of the study was to analyze and integrate all of the knowledge on concentrations and behaviour of these radionuclides, which originate mainly from residual contamination, in order to assess the impacts of Temelín Nuclear Power Plant on hydrosphere in these indicators during its standard operation and possible accidents. The radionuclides were analyzed in terms of spatial and temporal variability in their concentrations and their inflows and outflows, mainly into and from Orlík Reservoir. The analysis included standard radioecological characteristics, which were applicable for assessing long-term development and behavior of radionuclides in the environment affected by their possible accidental releases on the territory of the Czech Republic or outside this territory. For all of the components of the environment, the concentrations of 137Cs and 90Sr which were used for calculation of their effective and ecological half-time, were decreasing. For 137Cs in surface water and fish, the rates of the decrease in the first and second monitoring period were different. The rate of the decrease in 90Sr concentration was invariable. The results of the monitoring showed that 86% of suspended solids and 62% of 137Cs inflowing into Orlík Reservoir accumulated in the reservoir while accumulation of 90Sr was not substantiated. Outflows of 137Cs and 90Sr activities were assessed in relation to their concentrations that were accumulated in individual basins until 1986 consequently to Chernobyl accident and tests of atmospheric nuclear weapons. The results for the whole area of the Vltava, Luznice and Otava River basins upstream from the Vltava River at Solenice showed that during the period 1986-2013 only 0.49% of 137Cs activity and 3.6% of 90Sr activity that accumulated in the basins were washed and flowed out from the area. Distribution coefficients derived from summary analysis of sediments and concentration factors for biota were calculated. Concentrations of 3H in river sites not affected by Temelín plant were slowly decreasing and their values were substantially below those from the sites affected by the plant.展开更多
Microplastics(MPs)are found worldwide in high abundance,posing a potential threat to ecosystems.Despite the ubiquity of MPs in the environment,very little is known about the regional distribution of MPs and underlying...Microplastics(MPs)are found worldwide in high abundance,posing a potential threat to ecosystems.Despite the ubiquity of MPs in the environment,very little is known about the regional distribution of MPs and underlying factors affecting this distribution in the field,which likely include human activity,but also features of the environment itself.Here,out of a total of 1157 datapoints investigated in 53 Chinese studies,9.68%datapoints were removed as outliers in the heterogeneity analysis.This review revealed that the abundance of MPs was highly heterogeneous.In addition,microplastic(MP)distribution maps based on China demonstrated that the highest abundance of MPs tended to occur near large rivers and central land affected by the intersection of two monsoons.The model-fitting and previous studies showed that MP abundance in China was correlated with longitude,agricultural mulching film usage per capita,temperature,and precipitation.However,due to the heterogeneity of MPs and the low matching degree between the current environmental data and the sampling points,this pattern was not as evident as reported in any single study.Factors affecting the distribution of MPs can not be captured by linear relationships alone,and systematic selection of suitable environmental factors and further model optimization are needed to explore the cause of MP pollution in soil.Overall,this review revealed an uneven distribution of MPs and serves as a reference for model prediction to assess and control plastic pollution in natural soil environments.展开更多
The stress fields induced by a dislocation and its image dislocations around a narrow elliptic void are formulated. Based on the solution, the stress distribution and effective stress intensity factor of a blunt (elli...The stress fields induced by a dislocation and its image dislocations around a narrow elliptic void are formulated. Based on the solution, the stress distribution and effective stress intensity factor of a blunt (elliptic) crack were calculated under mode I constant loading. The results show that a dislocation-free zone (DFZ) is formed after dislocation emission. There exists a second stress peak in the DFZ except a stress peak at the blunt crack tip. With an increase in the applied stress intensity factorK la or the friction stress τf of the material, the DFZ size and the peak stress at the crack tip decrease, but the peak stress in the DFZ and the effective stress intensity factorK if presiding at the crack tip increase. Because of dislocation shíeldíing, effects, shieldíng ratioK la/K if increases with increasingK la, but it decreases with increasing τf.展开更多
Changes in atmospheric aerosols have profound effects on ecosystem productivity,vegetation growth and activity by directly and indirectly influencing climate and environment conditions.However,few studies have focused...Changes in atmospheric aerosols have profound effects on ecosystem productivity,vegetation growth and activity by directly and indirectly influencing climate and environment conditions.However,few studies have focused on the effects of atmospheric aerosols on vegetation growth and activity in the vulnerable arid and semi-arid regions,which are also the source areas of aerosols.Using the datasets of aerosol optical depth(AOD),normalized difference vegetation index(NDVI)and multiple climatic variables including photosynthetically active radiation(PAR),surface solar radiation(SSR),surface air temperature(TEM)and total precipitation(PRE),we analyzed the potential responses of vegetation activity to atmospheric aerosols and their associated climatic factors in arid and semi-arid regions of Asia from 2005 to 2015.Our results suggested that areas with decreasing growing-season NDVI were mainly observed in regions with relatively sparse vegetation coverage,while AOD tended to increase as NDVI decreased in these regions.Upon further analysis,we found that aerosols might exert a negative influence on vegetation activity by reducing SSR,PAR and TEM,as well as suppressing PRE in most arid and semi-arid regions of Asia.Moreover,the responses of atmospheric aerosols on vegetation activity varied among different growing stages.At the early growing stage,higher concentration of aerosol was accompanied with suppressed vegetation growth by enhancing cooling effects and reducing SSR and PAR.At the middle growing stage,aerosols tended to alter microphysical properties of clouds with suppressed PRE,thereby restricting vegetation growth.At the late growing stage,aerosols exerted significantly positive influences on vegetation activity by increasing SSR,PAR and TEM in regions with high anthropogenic aerosols.Overall,at different growing stages,aerosols could influence vegetation activity by changing different climatic factors including SSR,PAR,TEM and PRE in arid and semi-arid regions of Asia.This study not only clarifies the impacts of aerosols on vegetation activity in source areas,but also explains the roles of aerosols in climate.展开更多
基金This paper is a staged achievement of "Study on China's Income Distribution", a project supported by National Social Science Foundation.
文摘When observing China's income distribution problems .from an international perspective, we find that China's income inequality is not much different from developed countries after primary distribution. The real difference between China and developed countries is that income inequality in developed countries will reduce greatly after income redistribution while the income inequality remains the same for China. Therefore, one can conclude that income inequality in China derives from the ineffectiveness of redistribution. However, a large income gap is not the main reason for skewed income distribution in China. In fact, the problem lies in unfair distribution resulting from factor capitalization. A handful of people have taken proceeds from public assets at the expense of all the people, which has led to social poIarization. To remove unfair distribution, China should improve its means of redistribution to narrow its income gap in order to develop a fair and reasonable pattern of income distribution.
基金financially supported by the Knowledge Innovation Project of the Chinese Academy of Sciences(KSCX2-EW-J-2,KSCX2-EW-Z-4)the State Key Basic Research and Development Program of China(2007CB106801)
文摘Spatial distribution patterns are associated with life history and behavioral adaptations of animals. For studying the spatial distribution pattern of the steppe toad-headed lizard(Phrynocephalus frontalis) and its influencing factors,we conducted experiments in Hunshandake Sandy Land in Inner Mongolia,China in July 2009. By calculating the clustered indices,we found that the lizard was aggregately distributed when the sampling quadrat was smaller than 10 m × 10 m,and uniformly distributed when it was greater than 10 m × 10 m. The Nearest Neighbor Rule showed a clustering distribution pattern for P. frontalis and the distribution pattern was quadrat-sampling dependent. Furthermore,the cluster was determined by environmental factors when the sampling quadrat was smaller than 20 m × 20 m,but it was determined by both environmental factors and characteristics of the lizard when it was larger than 20 m × 20 m. Our results suggested that the steppe toad-headed lizards tended to aggregate into suitable habitat patches in desert areas. Additionally,we discussed that the lizard aggregation could be potentially used as an indictor of movement of sand dunes.
文摘This paper analyzes the impact of income distribution gap on consumption demand from a theoretical view,and draws the conclusion that there is an inverse relationship between income distribution gap and consumption demand.Then,the paper finds that the existing widening income distribution gap in China has a negative impact on consumption demand,but this is not the key factor for the insufficient consumption demand because of the low level of per capital income.At last,it suggests that governments should improve the income level of entire residents and adjust income distribution structure simultaneously.
基金funded by National Natural Scientific Foundation of China (Grant No.40871253 and 70873119)
文摘The exploitation of mineral resources plays an important role in promoting national economic development. Mining is an essential component of China's industrial economy. Using grey correlation method to analyze the correlative effect of mineral resources exploitation to relevant industries, using national income method to calculate the pulling effect of mineral resources exploitation to economic growth and using graphs as well as tables to analyze the income distribution effect, the article obtains active economic effect of mineral resources development in Bijie, Guizhou. Moreover, from the view of resources-cored effect, the article analyzes negative effects such as single industrial structure brought by mineral resource development. Through analysis, we find that mineral resources exploitation to some extent brings active effects including gross domestic product growth, local financial revenue growth and relevant industries development; however, its negative effects should not be ignored. The negative effect can be lightened by diversifying industrial structure and prolonging industrial chain.
文摘Based on a theoretic hypothesis that income inequality has both positive and negative effect on economic growth, this paper analyzes the influence of income distribution differences on economic growth of China by establishing a multivariate linear regression model. The influence of income distribution difference on the economic growth of China changes with the change of time. During a short period immediately after China implemented reform and opening up policy, income inequality has a positive influence on the economic growth of China. However, along with the passing of time, such positive influence has become weaker and weaker and even convertes into negative effective. This paper proposes several advices with policy to restrain the difference of income distribution from expanding and weaken its negative effect on economic growth of China.
文摘In this paper,based on the process data of evaluating the benchmark land prices of collective construction land and agricultural land,the score of influencing factors is calculated,and a regression model between value-added benefits and influencing factors is established.According to the contribution of the government and collectives to value-added benefits,the distribution proportions of different purposes and levels are calculated.The research results show that there are significant differences in the distribution proportion of value-added income among different levels.The government distribution proportion decreases with the decrease of level,while the collective distribution proportion increases with the decrease of level.For each level of decrease in commercial service industry land and industrial and mining warehousing industry land,the government distribution proportion decreases by an average of 2.66%and 2.34%,while the collective distribution proportion increases by an average of 2.66%and 2.34%,respectively.The average distribution proportion of the government in the value-added income of commercial service industry land is 31.58%,which is much higher than the average income of 23.68%in the value-added income of industrial and mining warehousing industry land.
基金a result of the Youth Program of the National Natural Science Foundation of China(Grant No.:7140328971403307)
文摘On the basis of extending Lee's(1999) model, this paper resolves the problem of biased division in the specification of equation and employs Urban Household Survey(UHS) data,China Household Income Project(CHIP) data and county-level minimum wage data collected by authors to investigate the wage distribution effects of change in the effective minimum wages measured by relative value. The result shows that the effective minimum wage will exert a significant spillover effect on wage distribution at the40 th percentile and below, which is favorable to reducing wage gaps at the bottom. This conclusion holds true under various robustness tests. However, the shrinking effective minimum wage has created a downward drag on wages, thus widening wage gaps at the bottom. The shrinking effective minimum wage contributed 150%,53.8%,45.5% and16.7% to the wage gaps at the 10 th, 20 th, 30 th and 40 th percentiles compared with the 50 th percentile. Therefore, the key to ensuring the effectiveness of minimum wages lies in the implementation of an automatic adjustment mechanism correlated with macroeconomic indicators. Compliance with minimum wages must be guaranteed and change in minimum wages must be measured with relative value.
文摘We present calculations and improvement inspired by the work of Lorenzo Zaninetti, published in 2020, it concerns a problem whose origin dates back 1911 with so called Maxwell-Jüttner distribution these lies on the Lorentz factor , with . This work uses powerful modern software for a reconstruction of Zaninetti work, which computes with special functions, these are included in the Mathematica software, as by instance Bessel and Meijer G-functions ready to manipulate. A progress is made, it is possible to perform an integral that is not computed in Zaninetti paper. This author connects the correct relativistic probability law: the Maxwell-Jüttner to the synchrotron emissivity with a magnetic B field, this work generalize these results, using the linear Stark effect and deals with an electric field E.
文摘The paper makes a comparative review and evaluation of different theories on impacts of the distribution of labor and capital income on economic growth as well as criticism of the mainstream theories and suggests using Bhaduri-Marglin model as the theoretical basis for relevant research. By formulating the econometric model and analyzing time series data from 1978 to 2012, the paper makes an empirical research into the impact of labor share on economic growth in China. It has discovered that the positive effect of labor share on consumption demand growth in China outweighs its negative effect on investment and net export growth, concluding that growth in China is wage-led at present. That may mean that (1) increasing labor share promotes growth and the goals of equality and efficiency supports each other," (2) the demand and optimizing structure" lies in regulation tools. key to "stabilizing growth, expanding domestic establishing a set of pro-labor institution and
基金support of the project Czech Electric Company No.90002551
文摘The paperfocuses on an analysis of the results of long-term monitoring of the concentrations of 137Cs, 90Sr and 3H in hydrosphere in the vicinity of Temelín Nuclear Power Plant (Temelín plant). The radionuclides were monitored in surface water, river sediments, aquatic flora and fish species. The main objective of the study was to analyze and integrate all of the knowledge on concentrations and behaviour of these radionuclides, which originate mainly from residual contamination, in order to assess the impacts of Temelín Nuclear Power Plant on hydrosphere in these indicators during its standard operation and possible accidents. The radionuclides were analyzed in terms of spatial and temporal variability in their concentrations and their inflows and outflows, mainly into and from Orlík Reservoir. The analysis included standard radioecological characteristics, which were applicable for assessing long-term development and behavior of radionuclides in the environment affected by their possible accidental releases on the territory of the Czech Republic or outside this territory. For all of the components of the environment, the concentrations of 137Cs and 90Sr which were used for calculation of their effective and ecological half-time, were decreasing. For 137Cs in surface water and fish, the rates of the decrease in the first and second monitoring period were different. The rate of the decrease in 90Sr concentration was invariable. The results of the monitoring showed that 86% of suspended solids and 62% of 137Cs inflowing into Orlík Reservoir accumulated in the reservoir while accumulation of 90Sr was not substantiated. Outflows of 137Cs and 90Sr activities were assessed in relation to their concentrations that were accumulated in individual basins until 1986 consequently to Chernobyl accident and tests of atmospheric nuclear weapons. The results for the whole area of the Vltava, Luznice and Otava River basins upstream from the Vltava River at Solenice showed that during the period 1986-2013 only 0.49% of 137Cs activity and 3.6% of 90Sr activity that accumulated in the basins were washed and flowed out from the area. Distribution coefficients derived from summary analysis of sediments and concentration factors for biota were calculated. Concentrations of 3H in river sites not affected by Temelín plant were slowly decreasing and their values were substantially below those from the sites affected by the plant.
基金supported by the specific research fund of the Innovation Platform for Academicians of Hainan Province(China)(No.YSPTZX202205)the Research Initiation Fund of Hainan University(China)(No.KYQD(ZR)20032)+3 种基金the Hainan Province Science and Technology Special Fund(China)(No.ZDYF2022SHFZ322)the Ministry of Agriculture and Rural Affairs of China(Nos.13220064 and 13210133)the Education Department of Hainan Province(China)(No.Hnjgzc2022-3)the National Nature Science Foundation of China(No.41571288).
文摘Microplastics(MPs)are found worldwide in high abundance,posing a potential threat to ecosystems.Despite the ubiquity of MPs in the environment,very little is known about the regional distribution of MPs and underlying factors affecting this distribution in the field,which likely include human activity,but also features of the environment itself.Here,out of a total of 1157 datapoints investigated in 53 Chinese studies,9.68%datapoints were removed as outliers in the heterogeneity analysis.This review revealed that the abundance of MPs was highly heterogeneous.In addition,microplastic(MP)distribution maps based on China demonstrated that the highest abundance of MPs tended to occur near large rivers and central land affected by the intersection of two monsoons.The model-fitting and previous studies showed that MP abundance in China was correlated with longitude,agricultural mulching film usage per capita,temperature,and precipitation.However,due to the heterogeneity of MPs and the low matching degree between the current environmental data and the sampling points,this pattern was not as evident as reported in any single study.Factors affecting the distribution of MPs can not be captured by linear relationships alone,and systematic selection of suitable environmental factors and further model optimization are needed to explore the cause of MP pollution in soil.Overall,this review revealed an uneven distribution of MPs and serves as a reference for model prediction to assess and control plastic pollution in natural soil environments.
文摘The stress fields induced by a dislocation and its image dislocations around a narrow elliptic void are formulated. Based on the solution, the stress distribution and effective stress intensity factor of a blunt (elliptic) crack were calculated under mode I constant loading. The results show that a dislocation-free zone (DFZ) is formed after dislocation emission. There exists a second stress peak in the DFZ except a stress peak at the blunt crack tip. With an increase in the applied stress intensity factorK la or the friction stress τf of the material, the DFZ size and the peak stress at the crack tip decrease, but the peak stress in the DFZ and the effective stress intensity factorK if presiding at the crack tip increase. Because of dislocation shíeldíing, effects, shieldíng ratioK la/K if increases with increasingK la, but it decreases with increasing τf.
基金supported by the National Key Research and Development Program of China(2016YFA0601900)the Key Frontier Program of the Chinese Academy of Sciences(QYZDJ-SSW-DQC043)+1 种基金the National Natural Science Foundation of China(41771012)the Applied and Basic Research Program from Tangshan Science and Technology Bureau,China(20130202b)。
文摘Changes in atmospheric aerosols have profound effects on ecosystem productivity,vegetation growth and activity by directly and indirectly influencing climate and environment conditions.However,few studies have focused on the effects of atmospheric aerosols on vegetation growth and activity in the vulnerable arid and semi-arid regions,which are also the source areas of aerosols.Using the datasets of aerosol optical depth(AOD),normalized difference vegetation index(NDVI)and multiple climatic variables including photosynthetically active radiation(PAR),surface solar radiation(SSR),surface air temperature(TEM)and total precipitation(PRE),we analyzed the potential responses of vegetation activity to atmospheric aerosols and their associated climatic factors in arid and semi-arid regions of Asia from 2005 to 2015.Our results suggested that areas with decreasing growing-season NDVI were mainly observed in regions with relatively sparse vegetation coverage,while AOD tended to increase as NDVI decreased in these regions.Upon further analysis,we found that aerosols might exert a negative influence on vegetation activity by reducing SSR,PAR and TEM,as well as suppressing PRE in most arid and semi-arid regions of Asia.Moreover,the responses of atmospheric aerosols on vegetation activity varied among different growing stages.At the early growing stage,higher concentration of aerosol was accompanied with suppressed vegetation growth by enhancing cooling effects and reducing SSR and PAR.At the middle growing stage,aerosols tended to alter microphysical properties of clouds with suppressed PRE,thereby restricting vegetation growth.At the late growing stage,aerosols exerted significantly positive influences on vegetation activity by increasing SSR,PAR and TEM in regions with high anthropogenic aerosols.Overall,at different growing stages,aerosols could influence vegetation activity by changing different climatic factors including SSR,PAR,TEM and PRE in arid and semi-arid regions of Asia.This study not only clarifies the impacts of aerosols on vegetation activity in source areas,but also explains the roles of aerosols in climate.
文摘在气候变暖和快速城市化背景下,北京一直面临着城市热岛效应带来的环境问题。基于北京市1981—2020年逐日气温观测资料,采用线性回归、克里金插值和相关性分析等方法,研究了北京市城郊气温变化趋势以及北京市城市热岛强度(Urban Heat Island, UHI)的时空变化特征,并评估了气象因素、人口密度和土地利用/覆盖类型对城市热岛效应的影响。结果表明:近40 a来北京市城郊区的平均气温均呈上升的变化趋势,且城区气温增幅大于郊区,表明北京市UHI上升趋势显著。就季节而言,北京市冬季UHI最强(1.22℃),秋季次之,春、夏最弱,其中秋季UHI增幅最大。同时,北京市城市热岛效应范围也在逐渐扩大,其中城六区为高值区,热岛区由西北向东南方向延伸至城市副中心通州区,朝阳区和通州区增温趋势明显。2000年以来,北京市冬季UHI出现了显著的增加趋势,高值区UHI增加至1.6℃。此外,主成分分析表明人口、建设用地和气压对城市热岛效应的形成起促进作用,而风速和耕地是缓解城市热岛效应的重要影响因素。