The contribution rate of equipment system-of-systems architecture(ESoSA)is an important index to evaluate the equipment update,development,and architecture optimization.Since the traditional ESoSA contribution rate ev...The contribution rate of equipment system-of-systems architecture(ESoSA)is an important index to evaluate the equipment update,development,and architecture optimization.Since the traditional ESoSA contribution rate evaluation method does not make full use of the fuzzy information and uncertain information in the equipment system-of-systems(ESoS),and the Bayesian network is an effective tool to solve the uncertain information,a new ESoSA contribution rate evaluation method based on the fuzzy Bayesian network(FBN)is proposed.Firstly,based on the operation loop theory,an ESoSA is constructed considering three aspects:reconnaissance equipment,decision equipment,and strike equipment.Next,the fuzzy set theory is introduced to construct the FBN of ESoSA to deal with fuzzy information and uncertain information.Furthermore,the fuzzy importance index of the root node of the FBN is used to calculate the contribution rate of the ESoSA,and the ESoSA contribution rate evaluation model based on the root node fuzzy importance is established.Finally,the feasibility and rationality of this method are validated via an empirical case study of aviation ESoSA.Compared with traditional methods,the evaluation method based on FBN takes various failure states of equipment into consideration,is free of acquiring accurate probability of traditional equipment failure,and models the uncertainty of the relationship between equipment.The proposed method not only supplements and improves the ESoSA contribution rate assessment method,but also broadens the application scope of the Bayesian network.展开更多
The weapons system portfolio selection problem arises at the equipment demonstration stage and deals with the military application requirements.Further,the contribution rate of the system is one of the important indic...The weapons system portfolio selection problem arises at the equipment demonstration stage and deals with the military application requirements.Further,the contribution rate of the system is one of the important indicators to evaluate the role of a system,which can facilitate the weapons system portfolio selection.Therefore,combining the system contribution rate with system portfolio selection is the focus of this study.It also focuses on calculating the contribution rates of multiple equipment systems with various types of capabilities.The contribution rate is measured by establishing a hierarchical multi-criteria value model from three dimensions.Based on the value model,the feasible portfolios are developed under certain cost constraints and the optimal weapons system portfolios are obtained by using the classification optimization selection strategy.Finally,an illustrative example is presented to verify the feasibility of the proposed model.展开更多
Equipment selection is an essential work in the research and development planning of equipment.The scientific and rational development of weapons equipment portfolios is of considerable significance to the optimizatio...Equipment selection is an essential work in the research and development planning of equipment.The scientific and rational development of weapons equipment portfolios is of considerable significance to the optimization of equipment architecture design,the adequate resources allocation,and the joint combat performance.From the system view,this paper proposes a method of weapons equipment portfolios selection(WEPS)based on the contribution rate of weapon systems,providing a new idea for weapon equipment portfolio selection.Firstly,we analyze the WEPS problem and the concept of the contribution rate under the systems background.Secondly,we propose a combat network modeling method for weapon equipment systems based on the function chain.Thirdly,we propose a WEPS method based on the contribution rate,fully considering the correlation relationships between potential weapons and the old weapon systems by the combat network model,under the limitation of capability demands and budget resources,with the objective to maximally increasing the combat ability of weapon systems.Finally,we make a case study with a specific WEPS problem where the whole calculation processes and results are analyzed and exhibited to verify the feasibility and effectiveness of the proposed method model.展开更多
To scientifically evaluate the equipment system of systems(SoS)contribution rate,a contribution rate calculation method based on a structural equation model(SEM)is proposed in this paper.The connotation and evaluation...To scientifically evaluate the equipment system of systems(SoS)contribution rate,a contribution rate calculation method based on a structural equation model(SEM)is proposed in this paper.The connotation and evaluation process of the equipment SoS contribution rate were redefined and standardized.To solve the existing problems in the application of the original contribution rate formula,a modified contribution rate calculation formula is proposed.Finally,the contribution rate evaluation index was divided into latent and explicit variables.The measurement and structural equations in the SEM were used to calculate and analyze the latent variables.The simulation results show that the number of defense lines of air defense weapon equipment has a greater impact on the linear configuration than the group configuration.When the number of K-type air defense weapons is sufficient,the two-layer linear configuration should be adopted with 20 air defense weapon systems.When the number of K-type air defense weapons is insufficient,the single-layer group configuration should be adopted with 12 air defense weapon systems.展开更多
A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis( SPA) method is proposed to calculate the con...A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis( SPA) method is proposed to calculate the contribution rate of PM2.5in Dongguan City. Due to geographic,meteorological factors and the low concentration of air pollutants in Qingxi area,the PM2.5in this place is mainly contributed by the regional transport of air pollutants from other inside areas of Dongguan,and less affected by the outside of Dongguan. So the concentration of PM2.5in Qingxi area can reflect the Dongguan's basic background concentration of PM2.5. On the basis of the basic background concentration,firstly the concentration of each pollutant components is divided into the internal part and the mixed part. Secondly using the source apportionment samples of five monitoring sites in Dongguan we can respectively construct a sample set A and an evaluation set B. Thirdly the SPA is operated onto the mixed part in terms of set B.At last the connection degree between the concentration of each pollutant components and external source and internal source will be calculated,that is the contribution rate. The research reveals that the contribution rate of internal source and external source of PM2.5in Dongguan City is 83%and 17% respectively,which roughly met expectations. This method is simple and effective and it can provide a reference for the government taking reduction measures to control PM2.5pollutants emission.展开更多
Agricultural informationization is the objective demand for transforming the traditional agriculture and promoting the development of agricultural modernization. Using the statistical data of the gross agricultural ou...Agricultural informationization is the objective demand for transforming the traditional agriculture and promoting the development of agricultural modernization. Using the statistical data of the gross agricultural output value of Hubei Province in 2005-2014,based on the C-D production function,it calculated the average contribution rate(2. 48%) of agricultural informationization to the growth of agricultural economy in Hubei Province,indicating that agricultural informationization can promote growth of agricultural economy. This is basically consistent with previous findings. In addition,investment in agricultural informationization and broadband access rate also influenced the growth of agricultural economy in Hubei Province. Therefore,government should further improve the infrastructure of agricultural informationization,strengthen training of farmers’ information skills,establish auxiliary mechanism for achievement feedback of information-based agricultural production,increase the contribution rate of informationization to agricultural operation and management,promote the contribution of informationization to the growth of agricultural economy,so as to increase agricultural income of farmers.展开更多
It is the rational and exact computation of the safety economy contribution rate that has the far-reaching realistic meaning to the improvement of society cognition to safety and the investment to the nation safety an...It is the rational and exact computation of the safety economy contribution rate that has the far-reaching realistic meaning to the improvement of society cognition to safety and the investment to the nation safety and the national macro-safety decision-makings. The accurate function between safety inputs and outputs was obtained through a founded econometric model. Then the forecasted safety economy contribution rate is 3.01% and the forecasted ratio between safety inputs and outputs is 1:1.81 in China in 2005. And the model accords with the practice of China and the results are sarisfying.展开更多
The contribution of the quark loop to the gluon damping rate at zero momentum is calculated using the effective perturbative expansion technique developed by Braaten and Pisarski. It is shown that in the temperature r...The contribution of the quark loop to the gluon damping rate at zero momentum is calculated using the effective perturbative expansion technique developed by Braaten and Pisarski. It is shown that in the temperature range accessible in the present heavy-ion experiments, the contribution of the quark loop can not be ignored. The numerical results show that the quark loop provides ~n apparent contribution to the gluon damping rate at temperatures of experimental interest.展开更多
A decline in atmospheric oxygen concentration is projected in the 21st century given the background of global warming.The Qinghai-Tibetan Plateau is located at a high altitude,and thus,it faces a hypoxia challenge;how...A decline in atmospheric oxygen concentration is projected in the 21st century given the background of global warming.The Qinghai-Tibetan Plateau is located at a high altitude,and thus,it faces a hypoxia challenge;however,knowledge of the factors contributing to its atmospheric oxygen concentration is still lacking.Here,we conducted joint observations of ecosystem oxygen production and carbon sinks and near-surface atmospheric oxygen concentrations on the Qinghai-Tibetan Plateau and meteorological elements at Beijing Fangshan Station.Using seasonal differences and statistical methods,we calculated the relative contribution rates of vegetation to changes in atmospheric oxygen concentration.Our results indicate that solar radiation,atmospheric humidity,and ecosystem oxygen consumption and production have a significant impact on the atmospheric oxygen concentration,and the impact shows temporal and spatial differences.Vegetation significantly impacts the oxygen concentration,with a contribution rate of 16.7%–24.5%,which is underestimated in existing research.Our findings provide important insights into the factors that influence atmospheric oxygen concentration and highlight the contribution of vegetation.To better understand the oxygen dynamics of the Qinghai-Tibetan Plateau,we recommend further field observations of soil respiration and vegetation photosynthesis to clarify the contributions of carbon storage,carbon sinks and other factors to the near-surface atmospheric oxygen concentration.展开更多
Alpine treeline, as a prominent ecological boundary between forested mountain slopes and alpine meadow/shrub, is highly complex in altitudinal distribution and sensitive to warming climate. Great efforts have been mad...Alpine treeline, as a prominent ecological boundary between forested mountain slopes and alpine meadow/shrub, is highly complex in altitudinal distribution and sensitive to warming climate. Great efforts have been made to explore their distribution patterns and ecological mechanisms that determine these patterns for more than 100 years, and quite a number of geographical and ecophysiological models have been developed to correlate treeline altitude with latitude or a latitude related temperature. However,on a global scale, all of these models have great difficulties to accurately predict treeline elevation due to the extreme diversity of treeline site conditions.One of the major reasons is that "mass elevation effect"(MEE) has not been quantified globally and related with global treeline elevations although it has been observed and its effect on treeline elevations in the Eurasian continent and Northern Hemisphere recognized. In this study, we collected and compiled a total of 594 treeline sites all over the world from literatures, and explored how MEE affects globaltreeline elevation by developing a ternary linear regression model with intra-mountain base elevation(IMBE, as a proxy of MEE), latitude and continentality as independent variables. The results indicated that IMBE, latitude and continentality together could explain 92% of global treeline elevation variability, and that IMBE contributes the most(52.2%), latitude the second(40%) and continentality the least(7.8%) to the altitudinal distribution of global treelines. In the Northern Hemisphere, the three factors' contributions amount to 50.4%, 45.9% and 3.7% respectively; in the south hemisphere, their contributions are 38.3%, 53%, and 8.7%, respectively. This indicates that MEE, virtually the heating effect of macro-landforms, is actually the most significant factor for the altitudinal distribution of treelines across the globe, and that latitude is relatively more significant for treeline elevation in the Southern Hemisphere probably due to fewer macro-landforms there.展开更多
Using the data of 545 meteorological stations in 1961-2015,according to the rainfall intensity classification standard issued by the China Meteorological Administration,the rainfall events were divided into six intens...Using the data of 545 meteorological stations in 1961-2015,according to the rainfall intensity classification standard issued by the China Meteorological Administration,the rainfall events were divided into six intensities: light rain,moderate rain,heavy rain,torrential rain,downpour and heavy downpour. The latter three were recorded as total torrential rain,and all the six were recorded as the total rainfall. In terms of the interannual rainfall and rainy days,the whole China was regarded as an object. Firstly,the annual rainfall and rainy day of different intensity of rainfalls of 545 stations in 1961-2015 were calculated. Then,the variation trend of rainfall and rainy days was calculated. Finally,the variation trend of contribution of different intensity of rainfalls and rainy days to total rainfall and rainy days were diagnosed. It obtained the following results.( i) The light rain in China was declining from 1961 to 2015,and the trend values of light rain and rainy days were-411. 44 mm/yr and-136. 99 d/yr,respectively. Heavy rain and total heavy rainfall showed an increasing trend,with rainfall and rainy day trends of 127. 02 and 463. 94 mm/yr and 7. 93 and 4. 24 d/yr,respectively. The total rainfall showed a ' hockey' phenomenon of ' first rise,then decline',and the trend values of rainfall and rainy days were 204. 29 mm/yr and-95. 81 d/yr,respectively. Except the northern region,the rainfall in most parts of China was dominated by increasing trends and was moving towards extremes.( ii) In terms of rainfall contribution rate,the contribution of light rain to total rainfall showed a declining trend,and the trend values of rainfall and rainy day contribution were both-0. 11%/yr. The contribution of other intensity rainfalls to total rainfall showed an increasing trend. The contribution of torrential rain to the total torrential rain showed a declining trend. The contribution trends of rainfall and rainy days were-0. 06% and-0. 03%/yr,respectively. The contribution of downpour and heavy downpour to total torrential rain showed an increasing trend,indicating the intensity of torrential rain in China is increasing. Although the contribution rate of different intensity of rainfalls to total rainfall was different in different areas of China,the contribution rate of heavy rainfall to total rainfall in most areas showed an increasing trend.( iii) Through comparing the rainfall and rainy days of six different intensity of rainfalls,it can be found that China’s heavy rainfall events are increasing and the rainfall intensity is developing towards extremes.展开更多
We experimentally studied the interaction between pozzolanic material(fly ash) and dehydrated autoclaved aerated concrete(DAAC). The DAAC powder was obtained by grinding aerated concrete waste to particles fi ner ...We experimentally studied the interaction between pozzolanic material(fly ash) and dehydrated autoclaved aerated concrete(DAAC). The DAAC powder was obtained by grinding aerated concrete waste to particles fi ner than 75μm and was then heated to temperatures up to 900 ℃. New cementitious material was prepared by proportioning fly ash and DAAC, named as AF. X-ray diffraction(XRD) was employed to identify the crystalline phases of DAAC before and after rehydration. The hydration process of AF was analyzed by the heat of hydration and non-evaporable water content(Wn). The experimental results show that the highest reactivity of DAAC can be obtained by calcining the powder at 700 ℃ and the dehydrated products are mainly β-C2 S and CaO. The cumulative heat of hydration and Wn was found to be strongly dependent on the replacement level of fl y ash, increasing the replacement level of fl y ash lowered them in AF. The strength contribution rates on pozzolanic effect of fl y ash in AF are always negative, showing a contrary tendency of that of cement-fl y ash system.展开更多
Based on the research data from the economics and management platform of Inner Mongolia Agricultural University,we analyze the changes in the input of agricultural production factors,such as farmland,labor and capital...Based on the research data from the economics and management platform of Inner Mongolia Agricultural University,we analyze the changes in the input of agricultural production factors,such as farmland,labor and capital in Hohhot City. Based on the principle of econometrics,we select the agricultural production input-output data in Hohhot City during the period 1992-2010,and establish the econometric model using Cobb-Douglas production factor,to estimate the rate of contribution of agricultural input to the growth of agricultural output value,and study the quantitative relations between agricultural input and agricultural output value. The results show that in Hohhot City,the contribution of chemical fertilizer input to the growth of agricultural output value is the greatest; the contribution of mechanical power to agricultural output value is still not brought into full play; the contribution of remaining production inputs ( including technical progress) accounts for 35. 69% . In the future,Hohhot City should pay more attention to the technical input to develop agriculture.展开更多
基金supported by the National Key Research and Development Project(2018YFB1700802)the National Natural Science Foundation of China(72071206)the Science and Technology Innovation Plan of Hunan Province(2020RC4046).
文摘The contribution rate of equipment system-of-systems architecture(ESoSA)is an important index to evaluate the equipment update,development,and architecture optimization.Since the traditional ESoSA contribution rate evaluation method does not make full use of the fuzzy information and uncertain information in the equipment system-of-systems(ESoS),and the Bayesian network is an effective tool to solve the uncertain information,a new ESoSA contribution rate evaluation method based on the fuzzy Bayesian network(FBN)is proposed.Firstly,based on the operation loop theory,an ESoSA is constructed considering three aspects:reconnaissance equipment,decision equipment,and strike equipment.Next,the fuzzy set theory is introduced to construct the FBN of ESoSA to deal with fuzzy information and uncertain information.Furthermore,the fuzzy importance index of the root node of the FBN is used to calculate the contribution rate of the ESoSA,and the ESoSA contribution rate evaluation model based on the root node fuzzy importance is established.Finally,the feasibility and rationality of this method are validated via an empirical case study of aviation ESoSA.Compared with traditional methods,the evaluation method based on FBN takes various failure states of equipment into consideration,is free of acquiring accurate probability of traditional equipment failure,and models the uncertainty of the relationship between equipment.The proposed method not only supplements and improves the ESoSA contribution rate assessment method,but also broadens the application scope of the Bayesian network.
基金supported by the National Key R&D Program of China(2017YFC1405005)the National Natural Science Foundation of China(71690233)
文摘The weapons system portfolio selection problem arises at the equipment demonstration stage and deals with the military application requirements.Further,the contribution rate of the system is one of the important indicators to evaluate the role of a system,which can facilitate the weapons system portfolio selection.Therefore,combining the system contribution rate with system portfolio selection is the focus of this study.It also focuses on calculating the contribution rates of multiple equipment systems with various types of capabilities.The contribution rate is measured by establishing a hierarchical multi-criteria value model from three dimensions.Based on the value model,the feasible portfolios are developed under certain cost constraints and the optimal weapons system portfolios are obtained by using the classification optimization selection strategy.Finally,an illustrative example is presented to verify the feasibility of the proposed model.
基金supported by the National Natural Science Foundation of China(71690233)the Scientific Research Foundation of National University of Defense Technology(ZK19-16)the PLA military graduate student funding project.
文摘Equipment selection is an essential work in the research and development planning of equipment.The scientific and rational development of weapons equipment portfolios is of considerable significance to the optimization of equipment architecture design,the adequate resources allocation,and the joint combat performance.From the system view,this paper proposes a method of weapons equipment portfolios selection(WEPS)based on the contribution rate of weapon systems,providing a new idea for weapon equipment portfolio selection.Firstly,we analyze the WEPS problem and the concept of the contribution rate under the systems background.Secondly,we propose a combat network modeling method for weapon equipment systems based on the function chain.Thirdly,we propose a WEPS method based on the contribution rate,fully considering the correlation relationships between potential weapons and the old weapon systems by the combat network model,under the limitation of capability demands and budget resources,with the objective to maximally increasing the combat ability of weapon systems.Finally,we make a case study with a specific WEPS problem where the whole calculation processes and results are analyzed and exhibited to verify the feasibility and effectiveness of the proposed method model.
基金Supported by Nationai Natural Science Foundation of China (61074085), Beijing Natural Science Foundation (4122029, 4142035), and the Fundamental Research Funds for the Central Universities (F_RF-SD-12-008B, FRF-AS- 11-004B)
基金The National Social Science Foundation Military Science Project(No.16GJ003-068).
文摘To scientifically evaluate the equipment system of systems(SoS)contribution rate,a contribution rate calculation method based on a structural equation model(SEM)is proposed in this paper.The connotation and evaluation process of the equipment SoS contribution rate were redefined and standardized.To solve the existing problems in the application of the original contribution rate formula,a modified contribution rate calculation formula is proposed.Finally,the contribution rate evaluation index was divided into latent and explicit variables.The measurement and structural equations in the SEM were used to calculate and analyze the latent variables.The simulation results show that the number of defense lines of air defense weapon equipment has a greater impact on the linear configuration than the group configuration.When the number of K-type air defense weapons is sufficient,the two-layer linear configuration should be adopted with 20 air defense weapon systems.When the number of K-type air defense weapons is insufficient,the single-layer group configuration should be adopted with 12 air defense weapon systems.
基金Supported by National Natural Science Foundation of China(71171089)Research for PM_(2.5) Contamination Characteristics and Prevention and Control Countermeasures in Dongguan City(Dongcaidan[2013]222)
文摘A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis( SPA) method is proposed to calculate the contribution rate of PM2.5in Dongguan City. Due to geographic,meteorological factors and the low concentration of air pollutants in Qingxi area,the PM2.5in this place is mainly contributed by the regional transport of air pollutants from other inside areas of Dongguan,and less affected by the outside of Dongguan. So the concentration of PM2.5in Qingxi area can reflect the Dongguan's basic background concentration of PM2.5. On the basis of the basic background concentration,firstly the concentration of each pollutant components is divided into the internal part and the mixed part. Secondly using the source apportionment samples of five monitoring sites in Dongguan we can respectively construct a sample set A and an evaluation set B. Thirdly the SPA is operated onto the mixed part in terms of set B.At last the connection degree between the concentration of each pollutant components and external source and internal source will be calculated,that is the contribution rate. The research reveals that the contribution rate of internal source and external source of PM2.5in Dongguan City is 83%and 17% respectively,which roughly met expectations. This method is simple and effective and it can provide a reference for the government taking reduction measures to control PM2.5pollutants emission.
基金Supported by Soft Science Project of Wuhan City in Hubei Province(201604-0306010178)
文摘Agricultural informationization is the objective demand for transforming the traditional agriculture and promoting the development of agricultural modernization. Using the statistical data of the gross agricultural output value of Hubei Province in 2005-2014,based on the C-D production function,it calculated the average contribution rate(2. 48%) of agricultural informationization to the growth of agricultural economy in Hubei Province,indicating that agricultural informationization can promote growth of agricultural economy. This is basically consistent with previous findings. In addition,investment in agricultural informationization and broadband access rate also influenced the growth of agricultural economy in Hubei Province. Therefore,government should further improve the infrastructure of agricultural informationization,strengthen training of farmers’ information skills,establish auxiliary mechanism for achievement feedback of information-based agricultural production,increase the contribution rate of informationization to agricultural operation and management,promote the contribution of informationization to the growth of agricultural economy,so as to increase agricultural income of farmers.
基金Supported by the National Natural Science Foundation of China(50274060) State Administration of Work Safety(03-103)
文摘It is the rational and exact computation of the safety economy contribution rate that has the far-reaching realistic meaning to the improvement of society cognition to safety and the investment to the nation safety and the national macro-safety decision-makings. The accurate function between safety inputs and outputs was obtained through a founded econometric model. Then the forecasted safety economy contribution rate is 3.01% and the forecasted ratio between safety inputs and outputs is 1:1.81 in China in 2005. And the model accords with the practice of China and the results are sarisfying.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11465021 and 11065010
文摘The contribution of the quark loop to the gluon damping rate at zero momentum is calculated using the effective perturbative expansion technique developed by Braaten and Pisarski. It is shown that in the temperature range accessible in the present heavy-ion experiments, the contribution of the quark loop can not be ignored. The numerical results show that the quark loop provides ~n apparent contribution to the gluon damping rate at temperatures of experimental interest.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(Grant Nos.2019QZKK0606&2019QZKK0906)。
文摘A decline in atmospheric oxygen concentration is projected in the 21st century given the background of global warming.The Qinghai-Tibetan Plateau is located at a high altitude,and thus,it faces a hypoxia challenge;however,knowledge of the factors contributing to its atmospheric oxygen concentration is still lacking.Here,we conducted joint observations of ecosystem oxygen production and carbon sinks and near-surface atmospheric oxygen concentrations on the Qinghai-Tibetan Plateau and meteorological elements at Beijing Fangshan Station.Using seasonal differences and statistical methods,we calculated the relative contribution rates of vegetation to changes in atmospheric oxygen concentration.Our results indicate that solar radiation,atmospheric humidity,and ecosystem oxygen consumption and production have a significant impact on the atmospheric oxygen concentration,and the impact shows temporal and spatial differences.Vegetation significantly impacts the oxygen concentration,with a contribution rate of 16.7%–24.5%,which is underestimated in existing research.Our findings provide important insights into the factors that influence atmospheric oxygen concentration and highlight the contribution of vegetation.To better understand the oxygen dynamics of the Qinghai-Tibetan Plateau,we recommend further field observations of soil respiration and vegetation photosynthesis to clarify the contributions of carbon storage,carbon sinks and other factors to the near-surface atmospheric oxygen concentration.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41030528 and No. 40971064)
文摘Alpine treeline, as a prominent ecological boundary between forested mountain slopes and alpine meadow/shrub, is highly complex in altitudinal distribution and sensitive to warming climate. Great efforts have been made to explore their distribution patterns and ecological mechanisms that determine these patterns for more than 100 years, and quite a number of geographical and ecophysiological models have been developed to correlate treeline altitude with latitude or a latitude related temperature. However,on a global scale, all of these models have great difficulties to accurately predict treeline elevation due to the extreme diversity of treeline site conditions.One of the major reasons is that "mass elevation effect"(MEE) has not been quantified globally and related with global treeline elevations although it has been observed and its effect on treeline elevations in the Eurasian continent and Northern Hemisphere recognized. In this study, we collected and compiled a total of 594 treeline sites all over the world from literatures, and explored how MEE affects globaltreeline elevation by developing a ternary linear regression model with intra-mountain base elevation(IMBE, as a proxy of MEE), latitude and continentality as independent variables. The results indicated that IMBE, latitude and continentality together could explain 92% of global treeline elevation variability, and that IMBE contributes the most(52.2%), latitude the second(40%) and continentality the least(7.8%) to the altitudinal distribution of global treelines. In the Northern Hemisphere, the three factors' contributions amount to 50.4%, 45.9% and 3.7% respectively; in the south hemisphere, their contributions are 38.3%, 53%, and 8.7%, respectively. This indicates that MEE, virtually the heating effect of macro-landforms, is actually the most significant factor for the altitudinal distribution of treelines across the globe, and that latitude is relatively more significant for treeline elevation in the Southern Hemisphere probably due to fewer macro-landforms there.
基金Supported by Project of National Natural Science Foundation of China(41801064)China Postdoctoral Science Foundation(2019T120114+1 种基金 2019M650756)Central Asian Atmospheric Science Research Fund(CAAS201804)
文摘Using the data of 545 meteorological stations in 1961-2015,according to the rainfall intensity classification standard issued by the China Meteorological Administration,the rainfall events were divided into six intensities: light rain,moderate rain,heavy rain,torrential rain,downpour and heavy downpour. The latter three were recorded as total torrential rain,and all the six were recorded as the total rainfall. In terms of the interannual rainfall and rainy days,the whole China was regarded as an object. Firstly,the annual rainfall and rainy day of different intensity of rainfalls of 545 stations in 1961-2015 were calculated. Then,the variation trend of rainfall and rainy days was calculated. Finally,the variation trend of contribution of different intensity of rainfalls and rainy days to total rainfall and rainy days were diagnosed. It obtained the following results.( i) The light rain in China was declining from 1961 to 2015,and the trend values of light rain and rainy days were-411. 44 mm/yr and-136. 99 d/yr,respectively. Heavy rain and total heavy rainfall showed an increasing trend,with rainfall and rainy day trends of 127. 02 and 463. 94 mm/yr and 7. 93 and 4. 24 d/yr,respectively. The total rainfall showed a ' hockey' phenomenon of ' first rise,then decline',and the trend values of rainfall and rainy days were 204. 29 mm/yr and-95. 81 d/yr,respectively. Except the northern region,the rainfall in most parts of China was dominated by increasing trends and was moving towards extremes.( ii) In terms of rainfall contribution rate,the contribution of light rain to total rainfall showed a declining trend,and the trend values of rainfall and rainy day contribution were both-0. 11%/yr. The contribution of other intensity rainfalls to total rainfall showed an increasing trend. The contribution of torrential rain to the total torrential rain showed a declining trend. The contribution trends of rainfall and rainy days were-0. 06% and-0. 03%/yr,respectively. The contribution of downpour and heavy downpour to total torrential rain showed an increasing trend,indicating the intensity of torrential rain in China is increasing. Although the contribution rate of different intensity of rainfalls to total rainfall was different in different areas of China,the contribution rate of heavy rainfall to total rainfall in most areas showed an increasing trend.( iii) Through comparing the rainfall and rainy days of six different intensity of rainfalls,it can be found that China’s heavy rainfall events are increasing and the rainfall intensity is developing towards extremes.
基金Funded by the"863"National High-tech Research and Development Program of China(No.2012AA06A112)
文摘We experimentally studied the interaction between pozzolanic material(fly ash) and dehydrated autoclaved aerated concrete(DAAC). The DAAC powder was obtained by grinding aerated concrete waste to particles fi ner than 75μm and was then heated to temperatures up to 900 ℃. New cementitious material was prepared by proportioning fly ash and DAAC, named as AF. X-ray diffraction(XRD) was employed to identify the crystalline phases of DAAC before and after rehydration. The hydration process of AF was analyzed by the heat of hydration and non-evaporable water content(Wn). The experimental results show that the highest reactivity of DAAC can be obtained by calcining the powder at 700 ℃ and the dehydrated products are mainly β-C2 S and CaO. The cumulative heat of hydration and Wn was found to be strongly dependent on the replacement level of fl y ash, increasing the replacement level of fl y ash lowered them in AF. The strength contribution rates on pozzolanic effect of fl y ash in AF are always negative, showing a contrary tendency of that of cement-fl y ash system.
文摘Based on the research data from the economics and management platform of Inner Mongolia Agricultural University,we analyze the changes in the input of agricultural production factors,such as farmland,labor and capital in Hohhot City. Based on the principle of econometrics,we select the agricultural production input-output data in Hohhot City during the period 1992-2010,and establish the econometric model using Cobb-Douglas production factor,to estimate the rate of contribution of agricultural input to the growth of agricultural output value,and study the quantitative relations between agricultural input and agricultural output value. The results show that in Hohhot City,the contribution of chemical fertilizer input to the growth of agricultural output value is the greatest; the contribution of mechanical power to agricultural output value is still not brought into full play; the contribution of remaining production inputs ( including technical progress) accounts for 35. 69% . In the future,Hohhot City should pay more attention to the technical input to develop agriculture.