How to build an international maritime GHG(greenhouse gas)emission reduction cooperation mechanism is an important international issue at present.Firstly,we describe the current situation of maritime transport GHG emi...How to build an international maritime GHG(greenhouse gas)emission reduction cooperation mechanism is an important international issue at present.Firstly,we describe the current situation of maritime transport GHG emission reduction and analyze the problems that still exist in international maritime transport emission reduction from four aspects:political,economic,legal and technical.For example,geopolitical aggravation hinders the solution of the FOC(Flag of Convenience)issue;maritime emissions are not included in the carbon emission trading system;the synergy of maritime emission reduction principles under the IMO(International Maritime Organization)framework and the technical level of maritime emission reduction needs to be improved.The motivation and essence of the divergent international actions on maritime emission reduction are discussed.Finally,it is proposed to implement the“true linkage principle”to solve the problem of FOCs;to promote the development of regional carbon markets and link them to the international maritime carbon emission trading market economically;to implement the CBDR(the common but differentiated responsibilities)principle legally to promote the international emission reduction work in an orderly manner;and the technical innovation of ships and increase the technical support.展开更多
With the development of hypersonic vehicle technology,ceramic-based radome materials are highly demanded due to their high operating temperatures,good dielectric properties,and high mechanical properties.Althoughα-Si...With the development of hypersonic vehicle technology,ceramic-based radome materials are highly demanded due to their high operating temperatures,good dielectric properties,and high mechanical properties.Althoughα-SiAlON is an ideal material for radome applications,its intrinsic low transmittance and high thermal conductivity limit its applications.Herein,we prepared Y-α-SiAlON porous ceramics through tert-butanol(TBA)gel-casting using the self-synthesizedα-SiAlON powder.The Y-α-SiAlON porous ceramics exhibited a uniform micron-level connected pore structure with the porosity(P)of 44.2%-58.6%.The real part of permittivity(s')was 3.13-4.18(8.2-12.4 GHz),which decreased significantly with the increasing porosity.The wave transmittance(|T|^(2))of the sample with porosity of 58.6%could exceed 80%in the thickness range of 6-10 mm.The thermal conductivity was maintained at a low level of 1.38-2.25 W·m^(-1)·K^(-1) owing to the introduction of the pore structure.The flexural strength was 44.73-88.33 MPa,which may be increased by rod-likeα-SiAlON grains.The results indicate that the prepared Y-α-SiAlON porous ceramics meet the requirements of high-temperature wave-transmitting materials for radome applications.展开更多
文摘How to build an international maritime GHG(greenhouse gas)emission reduction cooperation mechanism is an important international issue at present.Firstly,we describe the current situation of maritime transport GHG emission reduction and analyze the problems that still exist in international maritime transport emission reduction from four aspects:political,economic,legal and technical.For example,geopolitical aggravation hinders the solution of the FOC(Flag of Convenience)issue;maritime emissions are not included in the carbon emission trading system;the synergy of maritime emission reduction principles under the IMO(International Maritime Organization)framework and the technical level of maritime emission reduction needs to be improved.The motivation and essence of the divergent international actions on maritime emission reduction are discussed.Finally,it is proposed to implement the“true linkage principle”to solve the problem of FOCs;to promote the development of regional carbon markets and link them to the international maritime carbon emission trading market economically;to implement the CBDR(the common but differentiated responsibilities)principle legally to promote the international emission reduction work in an orderly manner;and the technical innovation of ships and increase the technical support.
基金supported by the International Cooperation Foundation of Shaanxi Province,China(No.2022KW-34)the National Natural Science Foundation of China(Nos.52072301,51908551,and 52272123)+3 种基金State Key Laboratory of New Ceramics&Fine Processing,Tsinghua University(No.KFZD202102)the Fundamental Research Funds for the Central Universities(No.D5000210722)Guangxi Science and Technology Plan Project(No.Gui Ke AB22035043)State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(No.P2023-003).
文摘With the development of hypersonic vehicle technology,ceramic-based radome materials are highly demanded due to their high operating temperatures,good dielectric properties,and high mechanical properties.Althoughα-SiAlON is an ideal material for radome applications,its intrinsic low transmittance and high thermal conductivity limit its applications.Herein,we prepared Y-α-SiAlON porous ceramics through tert-butanol(TBA)gel-casting using the self-synthesizedα-SiAlON powder.The Y-α-SiAlON porous ceramics exhibited a uniform micron-level connected pore structure with the porosity(P)of 44.2%-58.6%.The real part of permittivity(s')was 3.13-4.18(8.2-12.4 GHz),which decreased significantly with the increasing porosity.The wave transmittance(|T|^(2))of the sample with porosity of 58.6%could exceed 80%in the thickness range of 6-10 mm.The thermal conductivity was maintained at a low level of 1.38-2.25 W·m^(-1)·K^(-1) owing to the introduction of the pore structure.The flexural strength was 44.73-88.33 MPa,which may be increased by rod-likeα-SiAlON grains.The results indicate that the prepared Y-α-SiAlON porous ceramics meet the requirements of high-temperature wave-transmitting materials for radome applications.
