To develop a suitable production process for fiber reinforced investment casting shell mold,three methods were studied:the traditional method(M_(1)),the method of adding fiber into silica sol with mechanical stirring ...To develop a suitable production process for fiber reinforced investment casting shell mold,three methods were studied:the traditional method(M_(1)),the method of adding fiber into silica sol with mechanical stirring and ultrasonic agitation(M_(2)),and the method of adding fiber into slurry with mechanical stirring and ultrasonic agitation for durations of 3,15,30,and 45 min(M_(3)).The bending strength,high-temperature self-load deformation,and thermal conductivity of the shell molds were investigated.The results reveal that the enhancement of fiber dispersion through ultrasonic agitation improves the comprehensive performance of the shell molds.The maximum green bending strength of the shell mold by M_(2) reaches 3.29 MPa,which is 29% higher than that of the shell mold prepared by M_(1).Moreover,the high-temperature self-load deformation of the shell mold is reduced from 0.62% to 0.44%.In addition,simultaneous ultrasonic agitation and mechanical stirring effectively shorten the slurry preparation time while maintaining comparable levels of fiber dispersion.With the process M_(3)-45 min,the fillers are uniformly dispersed in the slurry,and the fired bending strength and the high-temperature self-load deformation reach 6.25 MPa and 0.41%,respectively.Therefore,the proposed ultrasonic agitation route is promising for the fabrication of fiber-reinforced shell molds with excellent fibers dispersion.展开更多
ln order to improve the level of investment promotion and redouble effortsto enhance services,on February l9th,the 2025 Action Plan for StabilizingForeign lnvestment was released,proposing 20 measures in four aspects....ln order to improve the level of investment promotion and redouble effortsto enhance services,on February l9th,the 2025 Action Plan for StabilizingForeign lnvestment was released,proposing 20 measures in four aspects.Cur-rently,with increasing uncertainties in the external environment,China facesmultple difficulties and challenges in attracting foreign investment.展开更多
On July 9,the launch conference of World Energy Investment Report 2025 was held at Peking University.This conference was co-hosted by the International Energy Agency(IEA)and the Institute of Energy,Peking University a...On July 9,the launch conference of World Energy Investment Report 2025 was held at Peking University.This conference was co-hosted by the International Energy Agency(IEA)and the Institute of Energy,Peking University and the Energy Foundation.Xu Li,First-level Researcher at the Second Division of International Financial Organizations under the Department of International Financial Cooperation of the Ministry of Finance and direct leader of the Ministry of Finance International Financial Research Expert Workshop,Tim Gould,Chief Energy Economist of the International Energy Agency(IEA),and Mr.Zhang Huiyong,Executive Director of International Cooperation at the Energy Foundation,attended the opening ceremony and delivered speeches.Yang Lei,Associate Dean of the Institute of Energy,Peking University,chaired the press conference.展开更多
Urban investment bonds are another financing method designed by local governments in China to avoid the legal restrictions of urban economic construction, especially urban infrastructure construction under specific ec...Urban investment bonds are another financing method designed by local governments in China to avoid the legal restrictions of urban economic construction, especially urban infrastructure construction under specific economic environment. Although the issuance of urban investment bonds has eased the financing difficulties of local governments to a certain extent, the credit risk of urban investment bonds has gradually emerged due to the rapid increase in the number of urban investment companies and the expansion of the debt scale. In the borrowing process, not only the local government has expanded the land finance, but also the financial transparency has decreased, which will affect the regional economic development level, the urbanization process and the financial and credit status of the city investment companies themselves. Therefore, first of all, the local government should promote the improvement of the tax system, reduce the government's reliance on land finance, actively enhance the government's financial transparency, reduce the information asymmetry between bond issuers and market investors, and reduce the debt risk. Secondly, for the sake of stable growth of local economy, over-investment and development of cities should be avoided. Finally, standardize enterprises to increase credit guarantee, avoid false credit guarantee, and improve the system of public disclosure of corporate financial risk information and the role of third-party market capital in strictly guarding the market, providing a more reliable capital guarantee for the issuance and operation of China's bond market.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 5186504)the University Science Foundation for Young Science and Technology Talents in Inner Mongolia Autonomous Region of China (Grant No. NJYT22078)+2 种基金the Basic Scientific Research Expenses Program of Universities directly under Inner Mongolia Autonomous Region (Grant No. JY20220059)the Inner Mongolia Autonomous Region ‘Grassland Talent’ project Young Innovative Talent Training Program Level ⅠBasic Research Expenses of Universities directly under the Inner Mongolia Autonomous Region (Grant No. ZTY2023040)。
文摘To develop a suitable production process for fiber reinforced investment casting shell mold,three methods were studied:the traditional method(M_(1)),the method of adding fiber into silica sol with mechanical stirring and ultrasonic agitation(M_(2)),and the method of adding fiber into slurry with mechanical stirring and ultrasonic agitation for durations of 3,15,30,and 45 min(M_(3)).The bending strength,high-temperature self-load deformation,and thermal conductivity of the shell molds were investigated.The results reveal that the enhancement of fiber dispersion through ultrasonic agitation improves the comprehensive performance of the shell molds.The maximum green bending strength of the shell mold by M_(2) reaches 3.29 MPa,which is 29% higher than that of the shell mold prepared by M_(1).Moreover,the high-temperature self-load deformation of the shell mold is reduced from 0.62% to 0.44%.In addition,simultaneous ultrasonic agitation and mechanical stirring effectively shorten the slurry preparation time while maintaining comparable levels of fiber dispersion.With the process M_(3)-45 min,the fillers are uniformly dispersed in the slurry,and the fired bending strength and the high-temperature self-load deformation reach 6.25 MPa and 0.41%,respectively.Therefore,the proposed ultrasonic agitation route is promising for the fabrication of fiber-reinforced shell molds with excellent fibers dispersion.
文摘ln order to improve the level of investment promotion and redouble effortsto enhance services,on February l9th,the 2025 Action Plan for StabilizingForeign lnvestment was released,proposing 20 measures in four aspects.Cur-rently,with increasing uncertainties in the external environment,China facesmultple difficulties and challenges in attracting foreign investment.
文摘On July 9,the launch conference of World Energy Investment Report 2025 was held at Peking University.This conference was co-hosted by the International Energy Agency(IEA)and the Institute of Energy,Peking University and the Energy Foundation.Xu Li,First-level Researcher at the Second Division of International Financial Organizations under the Department of International Financial Cooperation of the Ministry of Finance and direct leader of the Ministry of Finance International Financial Research Expert Workshop,Tim Gould,Chief Energy Economist of the International Energy Agency(IEA),and Mr.Zhang Huiyong,Executive Director of International Cooperation at the Energy Foundation,attended the opening ceremony and delivered speeches.Yang Lei,Associate Dean of the Institute of Energy,Peking University,chaired the press conference.
文摘Urban investment bonds are another financing method designed by local governments in China to avoid the legal restrictions of urban economic construction, especially urban infrastructure construction under specific economic environment. Although the issuance of urban investment bonds has eased the financing difficulties of local governments to a certain extent, the credit risk of urban investment bonds has gradually emerged due to the rapid increase in the number of urban investment companies and the expansion of the debt scale. In the borrowing process, not only the local government has expanded the land finance, but also the financial transparency has decreased, which will affect the regional economic development level, the urbanization process and the financial and credit status of the city investment companies themselves. Therefore, first of all, the local government should promote the improvement of the tax system, reduce the government's reliance on land finance, actively enhance the government's financial transparency, reduce the information asymmetry between bond issuers and market investors, and reduce the debt risk. Secondly, for the sake of stable growth of local economy, over-investment and development of cities should be avoided. Finally, standardize enterprises to increase credit guarantee, avoid false credit guarantee, and improve the system of public disclosure of corporate financial risk information and the role of third-party market capital in strictly guarding the market, providing a more reliable capital guarantee for the issuance and operation of China's bond market.
