In this paper,we study the optimal investment problem of an insurer whose surplus process follows the diffusion approximation of the classical Cramer-Lundberg model.Investment in the foreign markets is allowed,and the...In this paper,we study the optimal investment problem of an insurer whose surplus process follows the diffusion approximation of the classical Cramer-Lundberg model.Investment in the foreign markets is allowed,and therefore,the foreign exchange rate model is incorporated.Under the allowing of selling and borrowing,the problem of maximizing the expected exponential utility of terminal wealth is studied.By solving the corresponding Hamilton-Jacobi-Bellman equations,the optimal investment strategies and value functions are obtained.Finally,numerical analysis is presented.展开更多
By the reality of investment in China, a fished inv es tment model is obtained and modified by Hicks multiplicator-accelerator model. It preferable explains the status quo of investment in China. In China, The valu e ...By the reality of investment in China, a fished inv es tment model is obtained and modified by Hicks multiplicator-accelerator model. It preferable explains the status quo of investment in China. In China, The valu e of investment in period t is not only having relation to the investment of per iod t-1 and Gross Domestic Products of period t-1 (as the model of Hicks and S amuelson described) but also having some relation to the investment of period t -2.This is the reason that the model of Hicks or Samuelson can’t use in China d irectly. Then the model is analyzed by VAR(Vector Autoregressive) system. The VA R is a new model of macro-economics measurement. The advantage of VAR is that i t is avoid some complex problems as measuring off the endogenous variable and ex ogenous variable and the identifiability of model. It is composed of some dynami c equations. And it regards all the variables in equations as endogenous variabl es. By using statistical data in China a model about Gross Domestic Product and Investment is obtained and a forecasting is designed. The correlation is cal culated using Matlab. The results of the correlation of Gross Domestic Products, Investment and Consumption can analyze the rationality of policy of country and forecast the trend of economics. And it is profitable for exactly understand th e circumstance of investment. The shortage of this paper is that the gross of st atistical data is too small, only the data after the year of 1978 is available.展开更多
CA (Computer aided) investment casting technique used in superalloy castings of aerospace engine parts was presented. CA investment casting integrated computer application, RP (Rapid Prototyping) process, solidificati...CA (Computer aided) investment casting technique used in superalloy castings of aerospace engine parts was presented. CA investment casting integrated computer application, RP (Rapid Prototyping) process, solidification simulation and investment casting process. It broke the bottle neck of making metal die. Solid model of complex parts were produced by UGII or other software, then translated into STL(Stereolithography) file, after RP process of SLS(Selective Laser Sintering), wax pattern used in investment casting can be acquired without metal die in short time. These can reduce period and cost greatly of complex superalloy parts development of engine. The key processes of CA investment casting were discussed. The accuracy of model translation should match that of RP system. Choice of RP material, surface polishing, sintering parameter plays important role in RP process. Other processes, like solidification simulating and optimization of gate system were introduced. The conclusion was that complex parts can be produced by CA investment casting with lots of advantages. The accuracy of castings can reach CT5～7,and the smoothness can get Ra3～13 mm. These parts of engines worked well.展开更多
In the process of industrialization, China has been a big agricultural country, and the agricultural sector＇s economic activities have been playing important role in economic growth. This paper established the invest...In the process of industrialization, China has been a big agricultural country, and the agricultural sector＇s economic activities have been playing important role in economic growth. This paper established the investment behavior model of agricultural enterprises on the basis of Chinese practice. And then, the model presented the important factors impacting on investment, such as financing cost, wage, and policy factors, etc. Thirdly, this paper in particular used R-studio to estimate the impact of fmancing cost and policy factor on investment and capital accumulation of primary industry sector by gathering the data from 2003 to 2013. The results showed that the official interest rate of loans of financial institutions could be the proxy variable as the financing cost of agricultural enterprises, and the employment level of agricultural enterprises had negative impact on investment. Finally, this paper provided some explanations and suggestions on the basis of above results.展开更多
In this paper, an empirical research on the system risks of the Shenzhen Stock Market using capital asset pricing model is conducted. The typical composition stocks on Shenzhen Stock Market in 1998 are taken as sample...In this paper, an empirical research on the system risks of the Shenzhen Stock Market using capital asset pricing model is conducted. The typical composition stocks on Shenzhen Stock Market in 1998 are taken as samples. Some quantitative analysis results are got, which can measure the risk of stock market.展开更多
The rural human capital refers to the condensation of the physical body, knowledge, skills, and all the abilities that can improve the capacity of the rural labor productivity. The ability is a form of human capital s...The rural human capital refers to the condensation of the physical body, knowledge, skills, and all the abilities that can improve the capacity of the rural labor productivity. The ability is a form of human capital stock and it plays an important role in China＇s development of rural economy and society, but at present the situation of investment in human capital in rural areas is not optimistic. A lot of problems need to be solved such as the inadequate total investment and the irrational structure, as to these issues, strategies and recommendations were proposed in order to strengthen the human capital investment.展开更多
为在全球气候变化和碳循环研究的宏观背景下,深入探讨并准确分析区域碳储量的动态变化,同时对其未来趋势进行合理预测。通过耦合PLUS(patch-generating land use simulation model)模型与InVEST(integrated valuation of ecosystem serv...为在全球气候变化和碳循环研究的宏观背景下,深入探讨并准确分析区域碳储量的动态变化,同时对其未来趋势进行合理预测。通过耦合PLUS(patch-generating land use simulation model)模型与InVEST(integrated valuation of ecosystem services and trade-offs)模型,探讨了2010—2022年山东半岛城市群中代表性城市——潍坊市的碳储量时空演变规律,模拟了自由发展、耕地优先、发展优先、绿色优先这4种情境下2030年潍坊市碳储量的分布特征,同时使用XGBOOST+SHAP模型分析了潍坊市碳储量的驱动因素。研究结果表明:2010年至2022年潍坊市碳储量呈现出下降趋势,由2010年的16.56×10^(6)t下降至2020年的15.98×10^(6)t,主要原因为耕地面积的下降与不透水地面的扩张;在多情景模拟下,耕地优先情景下2030年碳储量总量最大,凸显了耕地作为重要碳汇的潜力及耕地保护策略的关键作用。而绿色优先情景略优于自由发展情景,通过促进林地发展增强固碳能力;发展优先情景下碳储量最小。温度和坡度对潍坊市碳储量的贡献较大,GDP和人口密度则对碳储量具有削弱作用,表明经济增长和城市扩张可能进一步加剧碳储量下降趋势。研究成果不仅揭示了城市群地区人类活动与自然生态系统间的复杂互动,还为制定科学合理的土地利用规划与碳减排策略提供了坚实的数据与理论支撑。展开更多
产水量是生态系统服务功能中表征水资源供给能力的指标之一,对生态系统评价具有重要意义。本文采用InVEST模型中Annual Water Yield(年产水量)模块,利用GIS空间分析技术,对泰安市产水量变化规律及其对多源因素(降水量、潜在蒸散量、土...产水量是生态系统服务功能中表征水资源供给能力的指标之一,对生态系统评价具有重要意义。本文采用InVEST模型中Annual Water Yield(年产水量)模块,利用GIS空间分析技术,对泰安市产水量变化规律及其对多源因素(降水量、潜在蒸散量、土地利用类型、净初级生产力、温度)的响应进行研究。研究结果表明:时间上,1990-2022年,泰安市平均产水量为234.92 mm,产水量以2.1 mm/yr的趋势增加,产水量变化主周期为25年,且在2018年存在突变。空间上,泰安市94.1%的地区产水量呈增加趋势,集聚模式为高值集聚;热点多集中于泰安市东部和城区,冷点多集中于西部和山地区。不同土地利用类型的产水能力由强到弱依次为建设用地、草地、耕地、林地、水域。多源因素中,泰安市产水量与降水量呈极强正相关性,且具有极显著性,两者在全时域、全时间尺度下都表现出强相干特征,产水量与潜在蒸散量、净初级生产力及温度相关性较弱。未来变化环境下,随着降水量的增加及城市用地的扩张,产水量呈增加趋势。研究结果对泰安市生态系统评价及水资源时空管理具有一定指导意义。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12301603).
文摘In this paper,we study the optimal investment problem of an insurer whose surplus process follows the diffusion approximation of the classical Cramer-Lundberg model.Investment in the foreign markets is allowed,and therefore,the foreign exchange rate model is incorporated.Under the allowing of selling and borrowing,the problem of maximizing the expected exponential utility of terminal wealth is studied.By solving the corresponding Hamilton-Jacobi-Bellman equations,the optimal investment strategies and value functions are obtained.Finally,numerical analysis is presented.
文摘By the reality of investment in China, a fished inv es tment model is obtained and modified by Hicks multiplicator-accelerator model. It preferable explains the status quo of investment in China. In China, The valu e of investment in period t is not only having relation to the investment of per iod t-1 and Gross Domestic Products of period t-1 (as the model of Hicks and S amuelson described) but also having some relation to the investment of period t -2.This is the reason that the model of Hicks or Samuelson can’t use in China d irectly. Then the model is analyzed by VAR(Vector Autoregressive) system. The VA R is a new model of macro-economics measurement. The advantage of VAR is that i t is avoid some complex problems as measuring off the endogenous variable and ex ogenous variable and the identifiability of model. It is composed of some dynami c equations. And it regards all the variables in equations as endogenous variabl es. By using statistical data in China a model about Gross Domestic Product and Investment is obtained and a forecasting is designed. The correlation is cal culated using Matlab. The results of the correlation of Gross Domestic Products, Investment and Consumption can analyze the rationality of policy of country and forecast the trend of economics. And it is profitable for exactly understand th e circumstance of investment. The shortage of this paper is that the gross of st atistical data is too small, only the data after the year of 1978 is available.
文摘CA (Computer aided) investment casting technique used in superalloy castings of aerospace engine parts was presented. CA investment casting integrated computer application, RP (Rapid Prototyping) process, solidification simulation and investment casting process. It broke the bottle neck of making metal die. Solid model of complex parts were produced by UGII or other software, then translated into STL(Stereolithography) file, after RP process of SLS(Selective Laser Sintering), wax pattern used in investment casting can be acquired without metal die in short time. These can reduce period and cost greatly of complex superalloy parts development of engine. The key processes of CA investment casting were discussed. The accuracy of model translation should match that of RP system. Choice of RP material, surface polishing, sintering parameter plays important role in RP process. Other processes, like solidification simulating and optimization of gate system were introduced. The conclusion was that complex parts can be produced by CA investment casting with lots of advantages. The accuracy of castings can reach CT5～7,and the smoothness can get Ra3～13 mm. These parts of engines worked well.
文摘In the process of industrialization, China has been a big agricultural country, and the agricultural sector＇s economic activities have been playing important role in economic growth. This paper established the investment behavior model of agricultural enterprises on the basis of Chinese practice. And then, the model presented the important factors impacting on investment, such as financing cost, wage, and policy factors, etc. Thirdly, this paper in particular used R-studio to estimate the impact of fmancing cost and policy factor on investment and capital accumulation of primary industry sector by gathering the data from 2003 to 2013. The results showed that the official interest rate of loans of financial institutions could be the proxy variable as the financing cost of agricultural enterprises, and the employment level of agricultural enterprises had negative impact on investment. Finally, this paper provided some explanations and suggestions on the basis of above results.
文摘In this paper, an empirical research on the system risks of the Shenzhen Stock Market using capital asset pricing model is conducted. The typical composition stocks on Shenzhen Stock Market in 1998 are taken as samples. Some quantitative analysis results are got, which can measure the risk of stock market.
基金Supported by Heilongjiang Province Social Sciences Fund Project (08E016)Natural Science Foundation of Heilongjiang (G201029)
文摘The rural human capital refers to the condensation of the physical body, knowledge, skills, and all the abilities that can improve the capacity of the rural labor productivity. The ability is a form of human capital stock and it plays an important role in China＇s development of rural economy and society, but at present the situation of investment in human capital in rural areas is not optimistic. A lot of problems need to be solved such as the inadequate total investment and the irrational structure, as to these issues, strategies and recommendations were proposed in order to strengthen the human capital investment.
文摘为在全球气候变化和碳循环研究的宏观背景下,深入探讨并准确分析区域碳储量的动态变化,同时对其未来趋势进行合理预测。通过耦合PLUS(patch-generating land use simulation model)模型与InVEST(integrated valuation of ecosystem services and trade-offs)模型,探讨了2010—2022年山东半岛城市群中代表性城市——潍坊市的碳储量时空演变规律,模拟了自由发展、耕地优先、发展优先、绿色优先这4种情境下2030年潍坊市碳储量的分布特征,同时使用XGBOOST+SHAP模型分析了潍坊市碳储量的驱动因素。研究结果表明:2010年至2022年潍坊市碳储量呈现出下降趋势,由2010年的16.56×10^(6)t下降至2020年的15.98×10^(6)t,主要原因为耕地面积的下降与不透水地面的扩张;在多情景模拟下,耕地优先情景下2030年碳储量总量最大,凸显了耕地作为重要碳汇的潜力及耕地保护策略的关键作用。而绿色优先情景略优于自由发展情景,通过促进林地发展增强固碳能力;发展优先情景下碳储量最小。温度和坡度对潍坊市碳储量的贡献较大,GDP和人口密度则对碳储量具有削弱作用,表明经济增长和城市扩张可能进一步加剧碳储量下降趋势。研究成果不仅揭示了城市群地区人类活动与自然生态系统间的复杂互动,还为制定科学合理的土地利用规划与碳减排策略提供了坚实的数据与理论支撑。
文摘产水量是生态系统服务功能中表征水资源供给能力的指标之一,对生态系统评价具有重要意义。本文采用InVEST模型中Annual Water Yield(年产水量)模块,利用GIS空间分析技术,对泰安市产水量变化规律及其对多源因素(降水量、潜在蒸散量、土地利用类型、净初级生产力、温度)的响应进行研究。研究结果表明:时间上,1990-2022年,泰安市平均产水量为234.92 mm,产水量以2.1 mm/yr的趋势增加,产水量变化主周期为25年,且在2018年存在突变。空间上,泰安市94.1%的地区产水量呈增加趋势,集聚模式为高值集聚;热点多集中于泰安市东部和城区,冷点多集中于西部和山地区。不同土地利用类型的产水能力由强到弱依次为建设用地、草地、耕地、林地、水域。多源因素中,泰安市产水量与降水量呈极强正相关性,且具有极显著性,两者在全时域、全时间尺度下都表现出强相干特征,产水量与潜在蒸散量、净初级生产力及温度相关性较弱。未来变化环境下,随着降水量的增加及城市用地的扩张,产水量呈增加趋势。研究结果对泰安市生态系统评价及水资源时空管理具有一定指导意义。
