In this paper we demonstrate that price-to-income ratio （PIR） is the most precise indicator of measuring bubble levels in China＇s urban hoasing market under current conditions. We have built a model to measure the ...In this paper we demonstrate that price-to-income ratio （PIR） is the most precise indicator of measuring bubble levels in China＇s urban hoasing market under current conditions. We have built a model to measure the reasonable PIR ceiling. Based on current mortgage rates, loan terms and down payment ratios, we conclude that the reasonable PIR for China ＇s urban residents should lie between 4.38-6.78 and should not exceed 7. 7hen, using statistical data, we calculate current PIR in China ＇s major cities. With reference to proper PIR, we conclude the existence of bubbles in China ＇s urban housing market; in particular, bubbles hace grown enormously large in some first-tier cities, which pose a huge financial risk. Based on the above analysis, we propose some policy suggestions to carefully deflate the bubbles in these housing markets.展开更多
At present, part of the local government officials who like to do grandiose things to impress people blindly promote the development of the real estate, resulting in the gap with the population migration, so many ghos...At present, part of the local government officials who like to do grandiose things to impress people blindly promote the development of the real estate, resulting in the gap with the population migration, so many ghost towns are born. In addition, while building the local infrastructure of some of the districts, they also ignore the problem of the rational allocation of their own financial funds. Visibly, the implementation of the coordination between the two will help make China＇s urbanization level advancing in the health and right directions.展开更多
Understanding the dynamics of water renewal in a reservoir is essential when the transport and fate of dissolved substances are evaluated.A three-dimensional hydrodynamic model was implemented to compute average resid...Understanding the dynamics of water renewal in a reservoir is essential when the transport and fate of dissolved substances are evaluated.A three-dimensional hydrodynamic model was implemented to compute average residence time and water age in Dahuofang Reservoir in China.The model was verified for a one-year time period in 2006.A simulation reproduced intra-annual variation of mixing represented by the fall/winter mixing and the spring/summer stratification.The simulated variation of vertical thermal structures also matched observation.The spatially varying average residence times and age distribution were investigated through a series of numerical experiments using a passively dissolved and conservative tracer as a surrogate.Residence time estimations yield a broad range of values depending on the position.The average residence time for a tracer placed at the head of the reservoir under high-,mean-,and low flow conditions was found to be about 125,236 and 521 days,respectively.The age simulation reveals that the age distribution is a function of the freshwater discharge.In the vertical direction,the age of the surface layers is larger than that of the bottom layers and the age difference between the surface and bottom layers decreases further downstream.The density-induced circulation plays an important role in the circulation in the reservoir,and can generate vertical age distribution in the reservoir.These findings provide useful information for understanding the transport process in Dahuofang Reservoir that can be used to assist the water quality management of the reservoir.展开更多
A three-dimensional eutrophication model was applied to assist the management of Dahuofang Reservoir in China.Transport processes were obtained from the three-dimensional,finite volume hydrodynamic model.The hydrodyna...A three-dimensional eutrophication model was applied to assist the management of Dahuofang Reservoir in China.Transport processes were obtained from the three-dimensional,finite volume hydrodynamic model.The hydrodynamic model was verified for a one-year time period in 2006.Our simulation reproduced intra-annual variation of stratification.The simulated variation of vertical thermal structures also matched observations.The water quality model included 8 state variables,including dissolved oxygen,phytoplankton as carbon,carbonaceous biochemical oxygen demand,ammonium nitrogen,nitrate and nitrite nitrogen,ortho-phosphorus,organic nitrogen,and organic phosphorus.Sensitivity of the parameters has been analyzed to decide which process would affect the water quality in the simulation.The water quality verification suggested the model successfully computed the temporal cycles and spatial distributions of key water quality components.The comparison between water quality components before and after the first phase of the water conveyance project suggests that the project has a slight effect on the reservoir ecosystem.The model could be used as a tool to guide physico-biological engineering design or management strategies for Dahuofang Reservoir.展开更多
In this study, we identified the current distribution of five globally distributed invasive Hemidactylus species and predicted their potential and future distribution using species distribution models based on climate...In this study, we identified the current distribution of five globally distributed invasive Hemidactylus species and predicted their potential and future distribution using species distribution models based on climate and elevation data. These species included H. brookii, H. frenatus, H. garnotii, FI. mabouia, and H. turcicus. We show that many regions with tropical and Mediterranean climates are suitable for most of these species. However, their current and potential distributions sug- gest that climate is not the only limiting factor. We hypothesize that climatic conditions may affect competition and other interactions resulting in a segregated distribution of the studied Hemidactylus species. As an effect of global climate change it is likely that H. brookiiwill expand its range to areas that are currently colonized by H. mabouia and/or H. frenatus, while H. turcicus is likely to expand its range to areas that are not yet invaded by any Hemidactylus species. The role of species interactions in the range expansion of these five Hemidactylus species still remains poorly understood, but could be of major importance in understanding and managing these invasive species.展开更多
文摘In this paper we demonstrate that price-to-income ratio （PIR） is the most precise indicator of measuring bubble levels in China＇s urban hoasing market under current conditions. We have built a model to measure the reasonable PIR ceiling. Based on current mortgage rates, loan terms and down payment ratios, we conclude that the reasonable PIR for China ＇s urban residents should lie between 4.38-6.78 and should not exceed 7. 7hen, using statistical data, we calculate current PIR in China ＇s major cities. With reference to proper PIR, we conclude the existence of bubbles in China ＇s urban housing market; in particular, bubbles hace grown enormously large in some first-tier cities, which pose a huge financial risk. Based on the above analysis, we propose some policy suggestions to carefully deflate the bubbles in these housing markets.
文摘At present, part of the local government officials who like to do grandiose things to impress people blindly promote the development of the real estate, resulting in the gap with the population migration, so many ghost towns are born. In addition, while building the local infrastructure of some of the districts, they also ignore the problem of the rational allocation of their own financial funds. Visibly, the implementation of the coordination between the two will help make China＇s urbanization level advancing in the health and right directions.
基金supported by the National Science and Technology Major Special Project of China on Water Pollution Control and Management (Grant No.2009ZX07528-006-01)the National Natural Science Foundation of China (Grant No. 50839001)
文摘Understanding the dynamics of water renewal in a reservoir is essential when the transport and fate of dissolved substances are evaluated.A three-dimensional hydrodynamic model was implemented to compute average residence time and water age in Dahuofang Reservoir in China.The model was verified for a one-year time period in 2006.A simulation reproduced intra-annual variation of mixing represented by the fall/winter mixing and the spring/summer stratification.The simulated variation of vertical thermal structures also matched observation.The spatially varying average residence times and age distribution were investigated through a series of numerical experiments using a passively dissolved and conservative tracer as a surrogate.Residence time estimations yield a broad range of values depending on the position.The average residence time for a tracer placed at the head of the reservoir under high-,mean-,and low flow conditions was found to be about 125,236 and 521 days,respectively.The age simulation reveals that the age distribution is a function of the freshwater discharge.In the vertical direction,the age of the surface layers is larger than that of the bottom layers and the age difference between the surface and bottom layers decreases further downstream.The density-induced circulation plays an important role in the circulation in the reservoir,and can generate vertical age distribution in the reservoir.These findings provide useful information for understanding the transport process in Dahuofang Reservoir that can be used to assist the water quality management of the reservoir.
基金supported by the National Science and Technology Major Special Project of China on Water Pollution Control and Management (Grant No. 2009ZX07528-006-01)the National Natural Science Foundation of China (Grant No. 50839001)
文摘A three-dimensional eutrophication model was applied to assist the management of Dahuofang Reservoir in China.Transport processes were obtained from the three-dimensional,finite volume hydrodynamic model.The hydrodynamic model was verified for a one-year time period in 2006.Our simulation reproduced intra-annual variation of stratification.The simulated variation of vertical thermal structures also matched observations.The water quality model included 8 state variables,including dissolved oxygen,phytoplankton as carbon,carbonaceous biochemical oxygen demand,ammonium nitrogen,nitrate and nitrite nitrogen,ortho-phosphorus,organic nitrogen,and organic phosphorus.Sensitivity of the parameters has been analyzed to decide which process would affect the water quality in the simulation.The water quality verification suggested the model successfully computed the temporal cycles and spatial distributions of key water quality components.The comparison between water quality components before and after the first phase of the water conveyance project suggests that the project has a slight effect on the reservoir ecosystem.The model could be used as a tool to guide physico-biological engineering design or management strategies for Dahuofang Reservoir.
文摘In this study, we identified the current distribution of five globally distributed invasive Hemidactylus species and predicted their potential and future distribution using species distribution models based on climate and elevation data. These species included H. brookii, H. frenatus, H. garnotii, FI. mabouia, and H. turcicus. We show that many regions with tropical and Mediterranean climates are suitable for most of these species. However, their current and potential distributions sug- gest that climate is not the only limiting factor. We hypothesize that climatic conditions may affect competition and other interactions resulting in a segregated distribution of the studied Hemidactylus species. As an effect of global climate change it is likely that H. brookiiwill expand its range to areas that are currently colonized by H. mabouia and/or H. frenatus, while H. turcicus is likely to expand its range to areas that are not yet invaded by any Hemidactylus species. The role of species interactions in the range expansion of these five Hemidactylus species still remains poorly understood, but could be of major importance in understanding and managing these invasive species.
