<正>第十一届国际数学教育大会将于2008年7月6日~7月13日在墨西哥的蒙特雷(Monterrey)召开(大会的网址:http://icme.upn.mx/icme11/index.html).国际数学教育大会的通用语言是英语,它每4年举行一次,是数学教育界规模最大、参与者...<正>第十一届国际数学教育大会将于2008年7月6日~7月13日在墨西哥的蒙特雷(Monterrey)召开(大会的网址:http://icme.upn.mx/icme11/index.html).国际数学教育大会的通用语言是英语,它每4年举行一次,是数学教育界规模最大、参与者最多、影响最大的一次盛会.国际数学教育大会有多种组织形式,其中较为重要的一种形式是专题研究小组(Topic Study Group).展开更多
在第九届国际数学教育大会(ICME9)上,前国际数学教育委员会秘书长 M·尼斯(Mogens Niss,丹麦)在所作的大会主题报告《数学教育的关键课题及趋势》(Key Issues andTrends in Research on MathematicalEducation)中,对近几十年数学教...在第九届国际数学教育大会(ICME9)上,前国际数学教育委员会秘书长 M·尼斯(Mogens Niss,丹麦)在所作的大会主题报告《数学教育的关键课题及趋势》(Key Issues andTrends in Research on MathematicalEducation)中,对近几十年数学教育研究的发展历程进行了总结和反思.如果说在当前的数学教育中,我们对发展学生的“元认知”展开更多
The chance of an Interplanetary Coronal Mass Ejection (ICME) observed by widely-separated spacecraft is rare. However, such an event provides us a good opportunity to study the propagation and evolution of ICMEs in th...The chance of an Interplanetary Coronal Mass Ejection (ICME) observed by widely-separated spacecraft is rare. However, such an event provides us a good opportunity to study the propagation and evolution of ICMEs in the heliosphere. On day 72 of 1975, an ICME was observed by Helios 1 at 0.3 AU, while a similar solar wind structure was observed by IMP 8 at Earth on day 70 of 1975. On the basis of comparison of the plasma signatures and the transit time from Helios 1 to IMP 8, we hypothesize the observed ICMEs by both spacecraft are resulted from the same active region on the solar surface. A one-dimensional MHD model was used to track the ICME from Helios 1 (0.3 AU) to Earth. The observed plasma profiles and timing are close to those predicted by our MHD model and thus, give the supports to the model.展开更多
The Martian hydrogen exosphere extends out of the bow shock, forming a "hydrogen corona". The solar wind interacts directly with the hydrogen corona. During an ICME event on 7 March 2015, the SWIA instrument...The Martian hydrogen exosphere extends out of the bow shock, forming a "hydrogen corona". The solar wind interacts directly with the hydrogen corona. During an ICME event on 7 March 2015, the SWIA instrument onboard Mars Atmosphere and Volatile Evolution mission (MAVEN) observed that the pick-up H+ fluxes in upstream solar wind were enhanced. Also increased were the penetrating H+ fluxes in the Martian atmosphere. Quantitatively, these penetrating H+ fluxes cannot increase by a factor of 5 simply due to a factor of 3 increase in the solar wind density, suggesting that the increased abundance of exospheric hydrogen upstream of the bow shock was a consequence of the passage of the ICME. A denser outer hydrogen corona at high altitudes suggests that the expansion of the neutral atmosphere was caused by the ICME. The excited and heated hydrogen exosphere probably indicates an elevated hydrogen escape rate during an ICME.展开更多
Integrated computational materials engineering (ICME) is an emerging discipline that can speed up product development by unifying material, design, fabrication, and computational power in a virtual environment. Develo...Integrated computational materials engineering (ICME) is an emerging discipline that can speed up product development by unifying material, design, fabrication, and computational power in a virtual environment. Developing and adapting ICME in industries is a grand challenge technically and culturally. To help develop a strategy for development of this new technology area, an ICME approach was proposed and implemented in optimizing thin welded structure design. The key component in this approach is a database which includes material properties, static strength, impact strength, and failure parameters for a weld. The heat source models, microstructure model, and thermo-mechanical model involved in ICME for welding simulation were discussed. The shell elements representing method for a fusion weld were introduced in details for a butt joint, lap joint, and a Tee joint. Using one or multiple solid elements representing a spot weld in a shell model was also discussed. Database building methods for resistance spot welding and fusion welding have been developed.展开更多
文摘<正>第十一届国际数学教育大会将于2008年7月6日~7月13日在墨西哥的蒙特雷(Monterrey)召开(大会的网址:http://icme.upn.mx/icme11/index.html).国际数学教育大会的通用语言是英语,它每4年举行一次,是数学教育界规模最大、参与者最多、影响最大的一次盛会.国际数学教育大会有多种组织形式,其中较为重要的一种形式是专题研究小组(Topic Study Group).
文摘在第九届国际数学教育大会(ICME9)上,前国际数学教育委员会秘书长 M·尼斯(Mogens Niss,丹麦)在所作的大会主题报告《数学教育的关键课题及趋势》(Key Issues andTrends in Research on MathematicalEducation)中,对近几十年数学教育研究的发展历程进行了总结和反思.如果说在当前的数学教育中,我们对发展学生的“元认知”
基金Supported by the National Natural Science Foundation of China(40325010)
文摘The chance of an Interplanetary Coronal Mass Ejection (ICME) observed by widely-separated spacecraft is rare. However, such an event provides us a good opportunity to study the propagation and evolution of ICMEs in the heliosphere. On day 72 of 1975, an ICME was observed by Helios 1 at 0.3 AU, while a similar solar wind structure was observed by IMP 8 at Earth on day 70 of 1975. On the basis of comparison of the plasma signatures and the transit time from Helios 1 to IMP 8, we hypothesize the observed ICMEs by both spacecraft are resulted from the same active region on the solar surface. A one-dimensional MHD model was used to track the ICME from Helios 1 (0.3 AU) to Earth. The observed plasma profiles and timing are close to those predicted by our MHD model and thus, give the supports to the model.
基金funded by the Science and Technology Development Fund, Macao SAR (File no.0002/2019/A1)National Natural Science Foundation of China (NSFC) under grant 41731067supported by CNRS, CNES, Observatoire de Paris and Université Paul Sabatier, Toulouse
文摘The Martian hydrogen exosphere extends out of the bow shock, forming a "hydrogen corona". The solar wind interacts directly with the hydrogen corona. During an ICME event on 7 March 2015, the SWIA instrument onboard Mars Atmosphere and Volatile Evolution mission (MAVEN) observed that the pick-up H+ fluxes in upstream solar wind were enhanced. Also increased were the penetrating H+ fluxes in the Martian atmosphere. Quantitatively, these penetrating H+ fluxes cannot increase by a factor of 5 simply due to a factor of 3 increase in the solar wind density, suggesting that the increased abundance of exospheric hydrogen upstream of the bow shock was a consequence of the passage of the ICME. A denser outer hydrogen corona at high altitudes suggests that the expansion of the neutral atmosphere was caused by the ICME. The excited and heated hydrogen exosphere probably indicates an elevated hydrogen escape rate during an ICME.
文摘Integrated computational materials engineering (ICME) is an emerging discipline that can speed up product development by unifying material, design, fabrication, and computational power in a virtual environment. Developing and adapting ICME in industries is a grand challenge technically and culturally. To help develop a strategy for development of this new technology area, an ICME approach was proposed and implemented in optimizing thin welded structure design. The key component in this approach is a database which includes material properties, static strength, impact strength, and failure parameters for a weld. The heat source models, microstructure model, and thermo-mechanical model involved in ICME for welding simulation were discussed. The shell elements representing method for a fusion weld were introduced in details for a butt joint, lap joint, and a Tee joint. Using one or multiple solid elements representing a spot weld in a shell model was also discussed. Database building methods for resistance spot welding and fusion welding have been developed.
