【Title】【Author】Snowpack is a combination of several snow layers. Accordingly, snowpack natural metamorphism is composed of several stages. The aim of this study is to investigate the natural snow metamorphism at t...【Title】【Author】Snowpack is a combination of several snow layers. Accordingly, snowpack natural metamorphism is composed of several stages. The aim of this study is to investigate the natural snow metamorphism at the snow layer unit. The field investigation was conducted at the Tianshan Station for Snow Cover and Avalanche Research, Chinese Academy of Sciences （43°16＇ N, 84°24＇ E, and 1,776 m a.s.l.）, during the winter of 2010-2011. A complete metamorphic procedure and the corresponding microstructure of a target snow layer were tracked. The results indicate that： the ideal and complete metamorphic process and the corresponding predominant snow grain shape have 5 stages： 1） unstable kinetic metamorphism near the surface; 2） unstable kinetic metamorphism under pressure; 3） stable kinetic metamorphism; 4） equilibrium metamorphism; 5） wet snow metamorphism. Snow grain size sharply decreased in the surface stage, and then changed to continuously increase. Rapid increase of grain size occurred in the stable kinetic metamorphism and wet snow metamorphism stage. The characteristic length was introduced to represent the real sizes of depth hoar crystals. The snow grain circularity ratio had a variation of “rapid increase – slow decrease – slow increase”, and the snow aggregations continuously increased with time. Snow density grew stepwise and remained steady from the stable kinetic to the equilibrium metamorphism stage. The differences in metamorphism extent and stages among snow layers, led to the characteristic layered structure of snowpack.展开更多
Damping behavior of Ti50.1Ni49.9 shape memory alloy during reverse martensitic transformation has been investigated by dynamic mechanical analyzer in a dual-cantilever mode. With the increase of strain amplitude, inte...Damping behavior of Ti50.1Ni49.9 shape memory alloy during reverse martensitic transformation has been investigated by dynamic mechanical analyzer in a dual-cantilever mode. With the increase of strain amplitude, internal friction （IF） of the alloy increases in martensite and austenite states while decreases in transformation region. Based on the regularity of IF attenuation in isothermal condition, IFTr and （IFpT＋ 1FI） are decomposed from the strain amplitude dependent IF in transformation region. For practical application of shape memory alloys as a damping material, it is significant to evaluate the damping capacity by eliminating the influence of IFTr and consider its time independent real IF （IFpT＋ IFI）.展开更多
In the last few years, ＂the BRICS＂ or Brazil, Russia, India, China, and South Africa have been increasingly investing in developing their cooperation and seeking to exert joint global influence. BRICS＇ mobilization...In the last few years, ＂the BRICS＂ or Brazil, Russia, India, China, and South Africa have been increasingly investing in developing their cooperation and seeking to exert joint global influence. BRICS＇ mobilization has been visible in the cooperation of high-level officials, deeper policy coordination, and the creation of BRICS institutions. As the BRICS intensify their pursuit of multipolarity, surprisingly little attention has been paid to the ways in which the BRICS has been received in the United States （US）, which is a crucial stakeholder in creating a multipolar system. How is the BRICS represented in US foreign policy circles？ This article examines the state of the US debate on the BR/CS, drawing on the per- spectives from foreign policy officials, top think tanks, and academics. It argues that there is a considerable gap between BRICS＇ multipolar aspirations and the perceptions of the grouping＇s promise and potential in the US. The BRICS is often marginalized in the US as an entity, and---even if accepted as such--it is considered ineffective in terms of its results. However, the BRICS benefits US foreign policy development： it challenges US officials to clarify their message on multipolarity; it reframes the debate from bilateral China vs. US competition to multilateral processes of providing global public goods; it generates a subfield of BRICS studies, which internationalize the production and consumption of knowledge in the field of global politics.展开更多
Joint Funds of National Natural Science Foundation of China （ NSFC ） are initiated by different stakeholders, which aim to play a better 9ufdin9 role to support basic research in specific areas and directions. They ...Joint Funds of National Natural Science Foundation of China （ NSFC ） are initiated by different stakeholders, which aim to play a better 9ufdin9 role to support basic research in specific areas and directions. They have formed an important part of the national natural science funding system, which is responsible for advancing science and technology in an expanding frontier. The article would briefly summarize the joint funds strategic goals, programs implementation and achievements in the past decade, and provide a perspective on their future development.展开更多
基金supported by National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No.2012BAC23B01)National Natural Science Foundation of China (Grant No.41171066)the R&D Special Fund for Public Welfare Industry of China(Grant No.GYHY201206026)
文摘【Title】【Author】Snowpack is a combination of several snow layers. Accordingly, snowpack natural metamorphism is composed of several stages. The aim of this study is to investigate the natural snow metamorphism at the snow layer unit. The field investigation was conducted at the Tianshan Station for Snow Cover and Avalanche Research, Chinese Academy of Sciences （43°16＇ N, 84°24＇ E, and 1,776 m a.s.l.）, during the winter of 2010-2011. A complete metamorphic procedure and the corresponding microstructure of a target snow layer were tracked. The results indicate that： the ideal and complete metamorphic process and the corresponding predominant snow grain shape have 5 stages： 1） unstable kinetic metamorphism near the surface; 2） unstable kinetic metamorphism under pressure; 3） stable kinetic metamorphism; 4） equilibrium metamorphism; 5） wet snow metamorphism. Snow grain size sharply decreased in the surface stage, and then changed to continuously increase. Rapid increase of grain size occurred in the stable kinetic metamorphism and wet snow metamorphism stage. The characteristic length was introduced to represent the real sizes of depth hoar crystals. The snow grain circularity ratio had a variation of “rapid increase – slow decrease – slow increase”, and the snow aggregations continuously increased with time. Snow density grew stepwise and remained steady from the stable kinetic to the equilibrium metamorphism stage. The differences in metamorphism extent and stages among snow layers, led to the characteristic layered structure of snowpack.
基金supported by the National Natural Science Foundation of China (Grant No. 51001100)
文摘Damping behavior of Ti50.1Ni49.9 shape memory alloy during reverse martensitic transformation has been investigated by dynamic mechanical analyzer in a dual-cantilever mode. With the increase of strain amplitude, internal friction （IF） of the alloy increases in martensite and austenite states while decreases in transformation region. Based on the regularity of IF attenuation in isothermal condition, IFTr and （IFpT＋ 1FI） are decomposed from the strain amplitude dependent IF in transformation region. For practical application of shape memory alloys as a damping material, it is significant to evaluate the damping capacity by eliminating the influence of IFTr and consider its time independent real IF （IFpT＋ IFI）.
文摘In the last few years, ＂the BRICS＂ or Brazil, Russia, India, China, and South Africa have been increasingly investing in developing their cooperation and seeking to exert joint global influence. BRICS＇ mobilization has been visible in the cooperation of high-level officials, deeper policy coordination, and the creation of BRICS institutions. As the BRICS intensify their pursuit of multipolarity, surprisingly little attention has been paid to the ways in which the BRICS has been received in the United States （US）, which is a crucial stakeholder in creating a multipolar system. How is the BRICS represented in US foreign policy circles？ This article examines the state of the US debate on the BR/CS, drawing on the per- spectives from foreign policy officials, top think tanks, and academics. It argues that there is a considerable gap between BRICS＇ multipolar aspirations and the perceptions of the grouping＇s promise and potential in the US. The BRICS is often marginalized in the US as an entity, and---even if accepted as such--it is considered ineffective in terms of its results. However, the BRICS benefits US foreign policy development： it challenges US officials to clarify their message on multipolarity; it reframes the debate from bilateral China vs. US competition to multilateral processes of providing global public goods; it generates a subfield of BRICS studies, which internationalize the production and consumption of knowledge in the field of global politics.
基金supported by grants from the National Natural Science Foundation of China (grants M1121009)
文摘Joint Funds of National Natural Science Foundation of China （ NSFC ） are initiated by different stakeholders, which aim to play a better 9ufdin9 role to support basic research in specific areas and directions. They have formed an important part of the national natural science funding system, which is responsible for advancing science and technology in an expanding frontier. The article would briefly summarize the joint funds strategic goals, programs implementation and achievements in the past decade, and provide a perspective on their future development.
