Cross section is a fundamental concept in collision theory. This concept hasbeen formulated for binary collisions,i.e.,collisions between two incidentparticles.As far as binary collisions are concerned,one can describ...Cross section is a fundamental concept in collision theory. This concept hasbeen formulated for binary collisions,i.e.,collisions between two incidentparticles.As far as binary collisions are concerned,one can describe withdifferential and integrated cross sections any elementary processes includingdissociation and rearrangement as well as elastic and inelastic scattering.It isbelieved,however that besides binary collisions there are three-body colli-sions,i.e.,collisions among three incident particles.Thus it is of展开更多
The magnetic fields and dynamical processes in the solar polar regions play a crucial role in the solar magnetic cycle and in supplying mass and energy to the fast solar wind,ultimately being vital in controlling sola...The magnetic fields and dynamical processes in the solar polar regions play a crucial role in the solar magnetic cycle and in supplying mass and energy to the fast solar wind,ultimately being vital in controlling solar activities and driving space weather.Despite numerous efforts to explore these regions,to date no imaging observations of the Sun's poles have been achieved from vantage points out of the ecliptic plane,leaving their behavior and evolution poorly understood.This observation gap has left three top-level scientific questions unanswered:How does the solar dynamo work and drive the solar magnetic cycle?What drives the fast solar wind?How do space weather processes globally originate from the Sun and propagate throughout the solar system?The Solar Polarorbit Observatory(SPO)mission,a solar polar exploration spacecraft,is proposed to address these three unanswered scientific questions by imaging the Sun's poles from high heliolatitudes.In order to achieve its scientific goals,SPO will carry six remote-sensing and four in-situ instruments to measure the vector magnetic fields and Doppler velocity fields in the photosphere,to observe the Sun in the extreme ultraviolet,X-ray,and radio wavelengths,to image the corona and the heliosphere up to 45 R_(s),and to perform in-situ detection of magnetic fields,and low-and high-energy particles in the solar wind.The SPO mission is capable of providing critical vector magnetic fields and Doppler velocities of the polar regions to advance our understanding of the origin of the solar magnetic cycle,providing unprecedented imaging observations of the solar poles alongside in-situ measurements of charged particles and magnetic fields from high heliolatitudes to unveil the mass and energy supply that drive the fast solar wind,and providing observational constraints for improving our ability to model and predict the three-dimensional(3D)structures and propagation of space weather events.展开更多
In a system consisting of an electron and a highly-charged ion,interaction with the radiation field is important.This means radiation-damping effects must be accurately taken into account.The present work discusses th...In a system consisting of an electron and a highly-charged ion,interaction with the radiation field is important.This means radiation-damping effects must be accurately taken into account.The present work discusses the radiation-damping effect in the processes of photoionization,radiative recombination,and electron scattering.展开更多
This study presents an integrated method suitable for off-axis tension and compression testing in unidirectional composites,and its application to the testing of in-plane shear characterization.A new rotating-grip tes...This study presents an integrated method suitable for off-axis tension and compression testing in unidirectional composites,and its application to the testing of in-plane shear characterization.A new rotating-grip test fixture,incorporating the attractive features of the existing pinned-end fixture and hydraulic wedge grips,has been developed.The proposed gripping system consists of two sets of jaw faces,each with a pair of self-aligning bearings that allows for loading in the axial and radial directions.Finite element analysis and experiments were performed to evaluate the effectiveness of the rotating-grip test fixture.Results from numerical calculations show that this method reduces stress concentrations near the end and produces relatively uniform stress distributions in the specimen gage section.Mechanical testing results show a considerable increase in the measured shear properties of composites,compared with the existing end grip systems.The results indicated that the new test fixture is significantly better than the conventional fixture,and is also comparable to the method of the oblique end-tab for off-axis testing.展开更多
文摘Cross section is a fundamental concept in collision theory. This concept hasbeen formulated for binary collisions,i.e.,collisions between two incidentparticles.As far as binary collisions are concerned,one can describe withdifferential and integrated cross sections any elementary processes includingdissociation and rearrangement as well as elastic and inelastic scattering.It isbelieved,however that besides binary collisions there are three-body colli-sions,i.e.,collisions among three incident particles.Thus it is of
文摘The magnetic fields and dynamical processes in the solar polar regions play a crucial role in the solar magnetic cycle and in supplying mass and energy to the fast solar wind,ultimately being vital in controlling solar activities and driving space weather.Despite numerous efforts to explore these regions,to date no imaging observations of the Sun's poles have been achieved from vantage points out of the ecliptic plane,leaving their behavior and evolution poorly understood.This observation gap has left three top-level scientific questions unanswered:How does the solar dynamo work and drive the solar magnetic cycle?What drives the fast solar wind?How do space weather processes globally originate from the Sun and propagate throughout the solar system?The Solar Polarorbit Observatory(SPO)mission,a solar polar exploration spacecraft,is proposed to address these three unanswered scientific questions by imaging the Sun's poles from high heliolatitudes.In order to achieve its scientific goals,SPO will carry six remote-sensing and four in-situ instruments to measure the vector magnetic fields and Doppler velocity fields in the photosphere,to observe the Sun in the extreme ultraviolet,X-ray,and radio wavelengths,to image the corona and the heliosphere up to 45 R_(s),and to perform in-situ detection of magnetic fields,and low-and high-energy particles in the solar wind.The SPO mission is capable of providing critical vector magnetic fields and Doppler velocities of the polar regions to advance our understanding of the origin of the solar magnetic cycle,providing unprecedented imaging observations of the solar poles alongside in-situ measurements of charged particles and magnetic fields from high heliolatitudes to unveil the mass and energy supply that drive the fast solar wind,and providing observational constraints for improving our ability to model and predict the three-dimensional(3D)structures and propagation of space weather events.
文摘In a system consisting of an electron and a highly-charged ion,interaction with the radiation field is important.This means radiation-damping effects must be accurately taken into account.The present work discusses the radiation-damping effect in the processes of photoionization,radiative recombination,and electron scattering.
文摘This study presents an integrated method suitable for off-axis tension and compression testing in unidirectional composites,and its application to the testing of in-plane shear characterization.A new rotating-grip test fixture,incorporating the attractive features of the existing pinned-end fixture and hydraulic wedge grips,has been developed.The proposed gripping system consists of two sets of jaw faces,each with a pair of self-aligning bearings that allows for loading in the axial and radial directions.Finite element analysis and experiments were performed to evaluate the effectiveness of the rotating-grip test fixture.Results from numerical calculations show that this method reduces stress concentrations near the end and produces relatively uniform stress distributions in the specimen gage section.Mechanical testing results show a considerable increase in the measured shear properties of composites,compared with the existing end grip systems.The results indicated that the new test fixture is significantly better than the conventional fixture,and is also comparable to the method of the oblique end-tab for off-axis testing.
