On the basis of sufficient considerations to the attributes of China's development and uniqueness of population aging, this paper examines the overall impacts of China's population aging on labor supply in the four ...On the basis of sufficient considerations to the attributes of China's development and uniqueness of population aging, this paper examines the overall impacts of China's population aging on labor supply in the four aspects of education level, skill level, work intensi(y and the share of working age population. Results indicate that despite the irreversibil#y in the decline of labor supply under the effect of intensifying degrees of population aging in the long run, this tendency will be weakened or slowed down by the improvement in labor quali^y. It is expected that China's real labor supply will not encounter a significant turning point by 2027, which is 12 years later than the occurrence of decline in nominal labor supply measured by labor quanti~展开更多
The widening gap between the supply and demand levels for livestock and poultry products in the Chinese mainland poses a significant challenge to the secure supply of feed grains. Therefore, the accurate prediction of...The widening gap between the supply and demand levels for livestock and poultry products in the Chinese mainland poses a significant challenge to the secure supply of feed grains. Therefore, the accurate prediction of the demand potential for feed grains represents a key scientific issue for ensuring food security in the Chinese mainland. This study is based on an analysis of several factors, such as the Chinese mainland’s output, trade volume, apparent consumption of livestock and poultry products, and two different scenarios for predicting the future demand for feed grains are assessed. The results indicate that output and consumption of livestock and poultry products, as well as the country’s trade deficit and the pressure of the supply and demand balance with respect to these products, have been increasing in recent years. The analysis predicts that the demand for feed grains in the Chinese mainland will reach 425.5 or 389.6 million tons in 2030 based on the two scenarios. This finding indicates that with the increasing demand for livestock and poultry products in the Chinese mainland, the demand for feed grains will continue to increase, and the shortfall in feed grains and raw materials will expand further, especially dependence on external sources of protein-rich feed grains will remain high.展开更多
This paper investigates a global asymptotic regulation control problem for a class of nonlinear systems with dynamic uncertainties.The requirement of a priori knowledge of control directions is removed and the inverse...This paper investigates a global asymptotic regulation control problem for a class of nonlinear systems with dynamic uncertainties.The requirement of a priori knowledge of control directions is removed and the inverse dynamics satisfy the weaker integral input-to-state stable condition.By application of the changing supply rates and the Nussbaum-type gain techniques,a partial state-feedback regulator is constructed.The main results demonstrate that the designed controller ensures the system state converges to the origin whereas the other signals of the closed-loop system are bounded. Simulation results are illustrated to show the effectiveness of the proposed approach.展开更多
文摘On the basis of sufficient considerations to the attributes of China's development and uniqueness of population aging, this paper examines the overall impacts of China's population aging on labor supply in the four aspects of education level, skill level, work intensi(y and the share of working age population. Results indicate that despite the irreversibil#y in the decline of labor supply under the effect of intensifying degrees of population aging in the long run, this tendency will be weakened or slowed down by the improvement in labor quali^y. It is expected that China's real labor supply will not encounter a significant turning point by 2027, which is 12 years later than the occurrence of decline in nominal labor supply measured by labor quanti~
基金The Key Deployment Project of Chinese Academy of Sciences (ZDBS-SSW-DQC)。
文摘The widening gap between the supply and demand levels for livestock and poultry products in the Chinese mainland poses a significant challenge to the secure supply of feed grains. Therefore, the accurate prediction of the demand potential for feed grains represents a key scientific issue for ensuring food security in the Chinese mainland. This study is based on an analysis of several factors, such as the Chinese mainland’s output, trade volume, apparent consumption of livestock and poultry products, and two different scenarios for predicting the future demand for feed grains are assessed. The results indicate that output and consumption of livestock and poultry products, as well as the country’s trade deficit and the pressure of the supply and demand balance with respect to these products, have been increasing in recent years. The analysis predicts that the demand for feed grains in the Chinese mainland will reach 425.5 or 389.6 million tons in 2030 based on the two scenarios. This finding indicates that with the increasing demand for livestock and poultry products in the Chinese mainland, the demand for feed grains will continue to increase, and the shortfall in feed grains and raw materials will expand further, especially dependence on external sources of protein-rich feed grains will remain high.
基金supported by the National Natural Science Foundation of China under Grant Nos.60674027, 60974127,and 60904022the Key Project Foundation of the Educational Ministry under Grant No.208074the Innovation Program of Graduate Students of Jiangsu Province of China under Grant No.CXZZ11_0155
文摘This paper investigates a global asymptotic regulation control problem for a class of nonlinear systems with dynamic uncertainties.The requirement of a priori knowledge of control directions is removed and the inverse dynamics satisfy the weaker integral input-to-state stable condition.By application of the changing supply rates and the Nussbaum-type gain techniques,a partial state-feedback regulator is constructed.The main results demonstrate that the designed controller ensures the system state converges to the origin whereas the other signals of the closed-loop system are bounded. Simulation results are illustrated to show the effectiveness of the proposed approach.