Due to the extremely arid climate in the western Qaidam Basin,the groundwater almost becomes the single water source for local residents and industrial production.It is necessary to know the reliable information on th...Due to the extremely arid climate in the western Qaidam Basin,the groundwater almost becomes the single water source for local residents and industrial production.It is necessary to know the reliable information on the groundwater cycle in this region for reasonable and sustainable exploitation of the groundwater resources with the further execution of recycling economy policies.This study focused on the recharge,the flow rate and the discharge of groundwater in the western Qaidam Basin through investigations on water chemistry and isotopes.Hydrological,chemical and isotopic characteristics show that the groundwater in the western Qaidam Basin was recharged by meltwater from new surface snow and old bottom glaciers on the northern slope of the Kunlun Mountains.In addition,the results also prove that the source water is enough and stable,and the rates of the circulation and renewal of the groundwater are relatively quick.Therefore,it can be concluded that the groundwater resources would guarantee the regional requirement if the meltwater volume of the mountains has not a great changes in future,moreover,water exploitation should be limited to the renewable amount of the groundwater reservoir in the western Qaidam Basin.展开更多
Different models have been proposed in corporate finance literature for predicting the risk of firm＇s bankruptcy and insolvency. In spite of the large amount of empirical findings, significant issues are still unsolv...Different models have been proposed in corporate finance literature for predicting the risk of firm＇s bankruptcy and insolvency. In spite of the large amount of empirical findings, significant issues are still unsolved. In this paper, the authors developed dynamic statistical models for bankruptcy prediction of Italian firms in the industrial sector by using financial indicators. The model specification has been obtained via different variable selection techniques, and the predictive accuracy of the proposed default risk models has been evaluated at various horizons by means of different accuracy measures. The reached results give evidence that dynamic models have a better performance in any of the considered scenarios.展开更多
This paper aims to derive the time-consistent investment strategy for the defined contribution(DC) pension plan under the mean-variance criterion.The financial market consists of a risk-free asset and a risky asset of...This paper aims to derive the time-consistent investment strategy for the defined contribution(DC) pension plan under the mean-variance criterion.The financial market consists of a risk-free asset and a risky asset of which price process satisfies the constant elasticity of variance(CEV) model.Compared with the geometric Brownian motion model,the CEV model has the ability of capturing the implied volatility skew and explaining the volatility smile.The authors assume that the contribution to the pension fund is a constant proportion of the pension member's salary.Meanwhile,the salary is stochastic and its volatility arises from the price process of the risky asset,which makes the proposed model different from most of existing researches and more realistic.In the proposed model,the optimization problem can be decomposed into two sub-problems:Before and after retirement cases.By applying a game theoretic framework and solving extended Hamilton-Jacobi-Bellman(HJB) systems,the authors derive the time-consistent strategies and the corresponding value functions explicitly.Finally,numerical simulations are presented to illustrate the effects of model parameters on the time-consistent strategies.展开更多
基金Under the auspices of National Natural Science Foundation of China (No 40603007)
文摘Due to the extremely arid climate in the western Qaidam Basin,the groundwater almost becomes the single water source for local residents and industrial production.It is necessary to know the reliable information on the groundwater cycle in this region for reasonable and sustainable exploitation of the groundwater resources with the further execution of recycling economy policies.This study focused on the recharge,the flow rate and the discharge of groundwater in the western Qaidam Basin through investigations on water chemistry and isotopes.Hydrological,chemical and isotopic characteristics show that the groundwater in the western Qaidam Basin was recharged by meltwater from new surface snow and old bottom glaciers on the northern slope of the Kunlun Mountains.In addition,the results also prove that the source water is enough and stable,and the rates of the circulation and renewal of the groundwater are relatively quick.Therefore,it can be concluded that the groundwater resources would guarantee the regional requirement if the meltwater volume of the mountains has not a great changes in future,moreover,water exploitation should be limited to the renewable amount of the groundwater reservoir in the western Qaidam Basin.
文摘Different models have been proposed in corporate finance literature for predicting the risk of firm＇s bankruptcy and insolvency. In spite of the large amount of empirical findings, significant issues are still unsolved. In this paper, the authors developed dynamic statistical models for bankruptcy prediction of Italian firms in the industrial sector by using financial indicators. The model specification has been obtained via different variable selection techniques, and the predictive accuracy of the proposed default risk models has been evaluated at various horizons by means of different accuracy measures. The reached results give evidence that dynamic models have a better performance in any of the considered scenarios.
基金the National Natural Science Foundation of China under Grant Nos.11201335,11301376,and 71573110
文摘This paper aims to derive the time-consistent investment strategy for the defined contribution(DC) pension plan under the mean-variance criterion.The financial market consists of a risk-free asset and a risky asset of which price process satisfies the constant elasticity of variance(CEV) model.Compared with the geometric Brownian motion model,the CEV model has the ability of capturing the implied volatility skew and explaining the volatility smile.The authors assume that the contribution to the pension fund is a constant proportion of the pension member's salary.Meanwhile,the salary is stochastic and its volatility arises from the price process of the risky asset,which makes the proposed model different from most of existing researches and more realistic.In the proposed model,the optimization problem can be decomposed into two sub-problems:Before and after retirement cases.By applying a game theoretic framework and solving extended Hamilton-Jacobi-Bellman(HJB) systems,the authors derive the time-consistent strategies and the corresponding value functions explicitly.Finally,numerical simulations are presented to illustrate the effects of model parameters on the time-consistent strategies.
