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
为探索InVEST模型应用研究的热点和趋势,文章利用CiteSpace对中国知网(CNKI)和Web of Science ^(TM)核心合集的1130篇InVEST模型应用研究文献进行定量分析。结果表明:InVEST模型应用研究的首篇文献发表于2010年,2019年以后年发文量快速...为探索InVEST模型应用研究的热点和趋势,文章利用CiteSpace对中国知网(CNKI)和Web of Science ^(TM)核心合集的1130篇InVEST模型应用研究文献进行定量分析。结果表明:InVEST模型应用研究的首篇文献发表于2010年,2019年以后年发文量快速增加,2019—2022年发文量占总文献80.3%;中国的英文发文量占英文文献总量的75%,中国科学院大学和中国科学院生态环境研究中心是核心研究机构。生境质量、土壤保持、产水服务和固碳是模型研究应用的主要生态系统服务类别,研究热点指向生态系统服务权衡/协同关系、生态系统服务演变预测以及价值评估等。最后从提高模型参数精准性、时空尺度耦合等方面提出展望,为模型未来的应用发展和服务管理提供支持。展开更多
Investment remains a cornerstone of China’s economic resilience amid global headwinds and structural transitions.In the short term,it drives sectoral growth,creates jobs,and stabilizes economic momentum.Over the long...Investment remains a cornerstone of China’s economic resilience amid global headwinds and structural transitions.In the short term,it drives sectoral growth,creates jobs,and stabilizes economic momentum.Over the long term,a well-structured investment allocation fuels industrial innovation and upgrading,laying a solid foundation for sustainable economic development.展开更多
In this work,the influences of surface layer slurry at different temperatures(10℃,14℃,18℃,22℃)on wax patterns deformation,shrinkage,slurry coating characteristics,and the surface quality of the casting were invest...In this work,the influences of surface layer slurry at different temperatures(10℃,14℃,18℃,22℃)on wax patterns deformation,shrinkage,slurry coating characteristics,and the surface quality of the casting were investigated by using a single factor variable method.The surface morphologies of the shell molds produced by different temperatures of the surface(first)layer slurries were observed via electron microscopy.Furthermore,the microscopic composition of these shell molds was obtained by EDS,and the osmotic effect of the slurry on the wax patterns at different temperatures was also assessed by the PZ-200 Contact Angle detector.The forming reasons for the surface cracks and holes of thick and large ZTC4 titanium alloy by investment casting were analyzed.The experimental results show that the surface of the shell molds prepared by the surface layer slurry with a low temperature exhibits noticeable damage,which is mainly due to the poor coating performance and the serious expansion and contraction of wax pattern at low temperatures.The second layer shell material(SiO_(2),Al_(2)O_(3))immerses into the crack area of the surface layer,contacts and reacts with the molten titanium to form surface cracks and holes in the castings.With the increase of the temperature of surface layer slurry,the damage to the shell surface tends to weaken,and the composition of the shell molds'surface becomes more uniform with less impurities.The results show that the surface layer slurry at 22℃is evenly coated on the surface of the wax patterns with appropriate thickness,and there is no surface shell mold rupture caused by sliding slurry after sand leaching.The surface layer slurry temperature is consistent with the wax pattern temperature and the workshop temperature,so there is no damage of the surface layer shell caused by expansion and contraction.Therefore,the shell mold prepared by the surface layer slurry at this temperature has good integrity,isolating the contact between the low inert shell material and the titanium liquid effectively,and the ZTC4 titanium alloy cylinder casting prepared by this shell mold is smooth,without cracks and holes.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.
文摘为探索InVEST模型应用研究的热点和趋势,文章利用CiteSpace对中国知网(CNKI)和Web of Science ^(TM)核心合集的1130篇InVEST模型应用研究文献进行定量分析。结果表明:InVEST模型应用研究的首篇文献发表于2010年,2019年以后年发文量快速增加,2019—2022年发文量占总文献80.3%;中国的英文发文量占英文文献总量的75%,中国科学院大学和中国科学院生态环境研究中心是核心研究机构。生境质量、土壤保持、产水服务和固碳是模型研究应用的主要生态系统服务类别,研究热点指向生态系统服务权衡/协同关系、生态系统服务演变预测以及价值评估等。最后从提高模型参数精准性、时空尺度耦合等方面提出展望,为模型未来的应用发展和服务管理提供支持。
文摘Investment remains a cornerstone of China’s economic resilience amid global headwinds and structural transitions.In the short term,it drives sectoral growth,creates jobs,and stabilizes economic momentum.Over the long term,a well-structured investment allocation fuels industrial innovation and upgrading,laying a solid foundation for sustainable economic development.
文摘In this work,the influences of surface layer slurry at different temperatures(10℃,14℃,18℃,22℃)on wax patterns deformation,shrinkage,slurry coating characteristics,and the surface quality of the casting were investigated by using a single factor variable method.The surface morphologies of the shell molds produced by different temperatures of the surface(first)layer slurries were observed via electron microscopy.Furthermore,the microscopic composition of these shell molds was obtained by EDS,and the osmotic effect of the slurry on the wax patterns at different temperatures was also assessed by the PZ-200 Contact Angle detector.The forming reasons for the surface cracks and holes of thick and large ZTC4 titanium alloy by investment casting were analyzed.The experimental results show that the surface of the shell molds prepared by the surface layer slurry with a low temperature exhibits noticeable damage,which is mainly due to the poor coating performance and the serious expansion and contraction of wax pattern at low temperatures.The second layer shell material(SiO_(2),Al_(2)O_(3))immerses into the crack area of the surface layer,contacts and reacts with the molten titanium to form surface cracks and holes in the castings.With the increase of the temperature of surface layer slurry,the damage to the shell surface tends to weaken,and the composition of the shell molds'surface becomes more uniform with less impurities.The results show that the surface layer slurry at 22℃is evenly coated on the surface of the wax patterns with appropriate thickness,and there is no surface shell mold rupture caused by sliding slurry after sand leaching.The surface layer slurry temperature is consistent with the wax pattern temperature and the workshop temperature,so there is no damage of the surface layer shell caused by expansion and contraction.Therefore,the shell mold prepared by the surface layer slurry at this temperature has good integrity,isolating the contact between the low inert shell material and the titanium liquid effectively,and the ZTC4 titanium alloy cylinder casting prepared by this shell mold is smooth,without cracks and holes.
