The dynamical framework of the nine-level version of the IAP AGCM is presented in this paper. The emphasis of the model's description is put on the following two aspects:(1) A model's standard atmosphere, whic...The dynamical framework of the nine-level version of the IAP AGCM is presented in this paper. The emphasis of the model's description is put on the following two aspects:(1) A model's standard atmosphere, which is a satisfactory approximation to the observed troposphere and lower stratosphere standard atmosphere, is introduced into the equations of the model to permit a more accurate calculation of the vertical transport terms, especially near the tropopause; (2) The vertical levels of the model are carefully selected to guarantee a smooth dependence of layer thickness upon pressure in order to reduce the truncation error involved in the unequal interval vertical finite-differencing. For testing the model, two kinds of linear baroclinic Rossby-Haurwitz waves, one of which has a dynamically stable vertical structure and the other has a relatively unstable one, are constructed to provide initial conditions for numerical experiments. The two waves have been integrated for more than 300 days and 100 days respectively by using the model and both of them are propagating westward with almost identical phase-speed during the time period of the integrations. No obvious change of the wave patterns is found at the levels in the model's troposphere. The amplitudes of both two waves at the uppermost level, however, exhibit rather significant oscillation with time, of which the periods are exactly 20 days and 25 days espectively.The explanation of this interesting phenomena is still under investigation.展开更多
The challenge of meeting the ever-increasing food demand for the growing population will be further exacerbated by climate change in Ethiopia. This paper presents the simulated economy-wide impacts of climate change o...The challenge of meeting the ever-increasing food demand for the growing population will be further exacerbated by climate change in Ethiopia. This paper presents the simulated economy-wide impacts of climate change on the agriculture sector of Ethiopia using a dynamic computable general equilibrium (CGE) model. The study simulated the scenarios of agricultural productivity change induced by climate change up to the year 2050. At national level, the simulation results suggest that crop production will be adversely affected during the coming four decades and the severity will increase over the time period. Production of teff, maize and sorghum will decline by 25.4, 21.8 and 25.2 percent, respectively by 2050 compared to the base period. Climate change will also cause losses of 31.1 percent agricultural GDP at factor cost by 2050. Climate change affects more the income and consumption of poor rural households than urban rural non-farming households. The reduction in agricultural production will not be evenly distributed across agro ecological zones, and will not all be negative. Among rural residents, climate change impacts tend to hurt the income of the poor more in drought prone regions. Income from labor, land and livestock in moisture sufficient highland cereal-based will decline by 5.1, 8.8 and 15.2 percent in 2050. This study indicated that since climate change is an inevitable phenomenon, the country should start mainstreaming adaptation measures to sustain the overall performance of the economy.展开更多
The role of the construction industry in economic growth has been widely discussed in the extant literature,but existing studies have not investigated the disaggregated impact of construction investments on the produc...The role of the construction industry in economic growth has been widely discussed in the extant literature,but existing studies have not investigated the disaggregated impact of construction investments on the production and social sectors.This study examines the disaggregated effect of construction investments on the Saudi economy.The study uses a social accounting matrix of Saudi Arabia and constructs a dynamic computable general equilibrium model.The findings reveal that construction investments significantly boosted GDP and aggregate investments in the first two periods;however,the growth declined in the following three periods.This finding underlines the importance of long-term investments in the construction sector and calls for continuous monitoring and updating of the investment policy for sustainable development.This study also presents the disaggregated impact of investments on the value-added by each sector of the economy.The ranking of sectors exhibits that mining and quarry activities underwent a high increase in value-added,second to construction activities.Other economic activities also experienced growth in value-added and some of them changed their ranks within the five years.展开更多
To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" s...To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" simulation platform was established to carry out fundamental tests on its motion characteristics, stability, and controllability. A motion control strategy consisting of both position and speed control in a horizontal plane was designed for different task assignments of underwater vehicles. Combined control of heave and pitch was adopted to compensate for the reduction of vertical tunnel thrusters when the vehicle is moving at a high speed. An improved S-surface controller based on the capacitor plate model was developed with flexible gain selections made possible by different forms of restricting the error and changing the rate of the error. Simulation results show that the derived general mathematical model together with simulation platform can provide a test bed for fundamental tests of motion control. Additionally, the capacitor plate model S-surface control shows a good performance in guiding the vehicle to achieve the desired position and speed with sufficient accuracy.展开更多
It was planned to build 36 million units of social welfare housing during the twelve-five2011-2015 in China.This paper introduces the estimation of owner occupied dwelling sector and develops a dynamic computable gene...It was planned to build 36 million units of social welfare housing during the twelve-five2011-2015 in China.This paper introduces the estimation of owner occupied dwelling sector and develops a dynamic computable general equilibrium model for China's real estate and macro-economy,to simulate the policy effects.The simulation results show that this policy can meet the increased requirements of housing demand due to fast urbanization and improvement of living conditions,therefore it will effectively cool down the price boom of housing market.Meanwhile,although the investment on social welfare housing will reduce the investment on other sectors,it will still stimulate GDP growth.展开更多
文摘The dynamical framework of the nine-level version of the IAP AGCM is presented in this paper. The emphasis of the model's description is put on the following two aspects:(1) A model's standard atmosphere, which is a satisfactory approximation to the observed troposphere and lower stratosphere standard atmosphere, is introduced into the equations of the model to permit a more accurate calculation of the vertical transport terms, especially near the tropopause; (2) The vertical levels of the model are carefully selected to guarantee a smooth dependence of layer thickness upon pressure in order to reduce the truncation error involved in the unequal interval vertical finite-differencing. For testing the model, two kinds of linear baroclinic Rossby-Haurwitz waves, one of which has a dynamically stable vertical structure and the other has a relatively unstable one, are constructed to provide initial conditions for numerical experiments. The two waves have been integrated for more than 300 days and 100 days respectively by using the model and both of them are propagating westward with almost identical phase-speed during the time period of the integrations. No obvious change of the wave patterns is found at the levels in the model's troposphere. The amplitudes of both two waves at the uppermost level, however, exhibit rather significant oscillation with time, of which the periods are exactly 20 days and 25 days espectively.The explanation of this interesting phenomena is still under investigation.
文摘The challenge of meeting the ever-increasing food demand for the growing population will be further exacerbated by climate change in Ethiopia. This paper presents the simulated economy-wide impacts of climate change on the agriculture sector of Ethiopia using a dynamic computable general equilibrium (CGE) model. The study simulated the scenarios of agricultural productivity change induced by climate change up to the year 2050. At national level, the simulation results suggest that crop production will be adversely affected during the coming four decades and the severity will increase over the time period. Production of teff, maize and sorghum will decline by 25.4, 21.8 and 25.2 percent, respectively by 2050 compared to the base period. Climate change will also cause losses of 31.1 percent agricultural GDP at factor cost by 2050. Climate change affects more the income and consumption of poor rural households than urban rural non-farming households. The reduction in agricultural production will not be evenly distributed across agro ecological zones, and will not all be negative. Among rural residents, climate change impacts tend to hurt the income of the poor more in drought prone regions. Income from labor, land and livestock in moisture sufficient highland cereal-based will decline by 5.1, 8.8 and 15.2 percent in 2050. This study indicated that since climate change is an inevitable phenomenon, the country should start mainstreaming adaptation measures to sustain the overall performance of the economy.
文摘The role of the construction industry in economic growth has been widely discussed in the extant literature,but existing studies have not investigated the disaggregated impact of construction investments on the production and social sectors.This study examines the disaggregated effect of construction investments on the Saudi economy.The study uses a social accounting matrix of Saudi Arabia and constructs a dynamic computable general equilibrium model.The findings reveal that construction investments significantly boosted GDP and aggregate investments in the first two periods;however,the growth declined in the following three periods.This finding underlines the importance of long-term investments in the construction sector and calls for continuous monitoring and updating of the investment policy for sustainable development.This study also presents the disaggregated impact of investments on the value-added by each sector of the economy.The ranking of sectors exhibits that mining and quarry activities underwent a high increase in value-added,second to construction activities.Other economic activities also experienced growth in value-added and some of them changed their ranks within the five years.
基金the National Science Foundation under Grant No.50879014,No.50909025
文摘To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" simulation platform was established to carry out fundamental tests on its motion characteristics, stability, and controllability. A motion control strategy consisting of both position and speed control in a horizontal plane was designed for different task assignments of underwater vehicles. Combined control of heave and pitch was adopted to compensate for the reduction of vertical tunnel thrusters when the vehicle is moving at a high speed. An improved S-surface controller based on the capacitor plate model was developed with flexible gain selections made possible by different forms of restricting the error and changing the rate of the error. Simulation results show that the derived general mathematical model together with simulation platform can provide a test bed for fundamental tests of motion control. Additionally, the capacitor plate model S-surface control shows a good performance in guiding the vehicle to achieve the desired position and speed with sufficient accuracy.
基金supported by the Natural Science Foundation of China under Grant No.71103176
文摘It was planned to build 36 million units of social welfare housing during the twelve-five2011-2015 in China.This paper introduces the estimation of owner occupied dwelling sector and develops a dynamic computable general equilibrium model for China's real estate and macro-economy,to simulate the policy effects.The simulation results show that this policy can meet the increased requirements of housing demand due to fast urbanization and improvement of living conditions,therefore it will effectively cool down the price boom of housing market.Meanwhile,although the investment on social welfare housing will reduce the investment on other sectors,it will still stimulate GDP growth.
