The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.Thi...The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.This allows estimates of the characteristics of asteroid 2016HO_(3),the target of the first Chinese asteroid exploration mission,Tianwen 2.We obtain 80 characteristic parameters in 9 categories and analyze their impacts on the mission.By comparing three close-range exploration modes,we provide advantages and disadvantages of each,and propose suitable methods for the exploration of 2016HO_(3).Owing to the weak gravity and small size of 2016HO_(3),a combination of multiple hovering positions and active orbiting is recommended for scientific exploration.展开更多
为了研究中卫市香山地区冻雨天气成因并提高该地区冻雨天气的预报能力,本文利用常规观测资料、加密气象观测资料、MICAPS资料和香山风电场工作日志资料,对2016年3月中卫香山风电场出现的一次冰冻雨雪灾害天气过程进行天气学分析,并对冻...为了研究中卫市香山地区冻雨天气成因并提高该地区冻雨天气的预报能力,本文利用常规观测资料、加密气象观测资料、MICAPS资料和香山风电场工作日志资料,对2016年3月中卫香山风电场出现的一次冰冻雨雪灾害天气过程进行天气学分析,并对冻雨发生的物理量场、大气垂直结构和地形作用进行分析。结果表明,500 h Pa"东高西低"的环流形势是此次天气过程产生的背景条件,低层的偏南暖湿气流输送和低值系统的共同作用是产生降水的根本条件;冻雨产生时段大气温度垂直结构上、中、下层呈冷、暖、冷分布,中层有温度>0℃的暖层,近地面层为0℃或以下,中层冷平流对暖层会有破坏作用,垂直温度结构改变,降水相态随之发生变化;在同一降水过程中,山地和川区大气垂直结构存在明显差别,需关注降水相态是否一致。展开更多
Conventional synthetic aperture radar(SAR)interferometry(InSAR)has been successfully used to precisely measure surface deformation in the line-of-sight(LOS)direction,while multiple-aperture SAR interferometry(MAI)has ...Conventional synthetic aperture radar(SAR)interferometry(InSAR)has been successfully used to precisely measure surface deformation in the line-of-sight(LOS)direction,while multiple-aperture SAR interferometry(MAI)has provided precise surface deformation in the along-track(AT)direction.Integration of the InSAR and MAI methods enables precise measurement of the two-dimensional(2D)deformation from an interferometric pair;recently,the integration of ascending and descending pairs has allowed the observation of precise three-dimensional(3D)deformation.Precise 3D deformation measurement has been applied to better understand geological events such as earthquakes and volcanic eruptions.The surface deformation related to the 2016 Kumamoto earthquake was large and complex near the fault line;hence,precise 3D deformation retrieval had not yet been attempted.The objectives of this study were to①perform a feasibility test of precise 3D deformation retrieval in large and complex deformation areas through the integration of offset-based unwrapped and improved multiple-aperture SAR interferograms and②observe the 3D deformation field related to the 2016 Kumamoto earthquake,even near the fault lines.Two ascending pairs and one descending the Advanced Land Observing Satellite-2(ALOS-2)Phased Array-type L-band Synthetic Aperture Radar-2(PALSAR-2)pair were used for the 3D deformation retrieval.Eleven in situ Global Positioning System(GPS)measurements were used to validate the 3D deformation measurement accuracy.The achieved accuracy was approximately 2.96,3.75,and 2.86 cm in the east,north,and up directions,respectively.The results show the feasibility of precise 3D deformation measured through the integration of the improved methods,even in a case of large and complex deformation.展开更多
四年一届的世界第一印刷展drupa 2016在5月31日—6月10日如期召开。经过60多年的发展,drupa展会在印刷包装行业内有着无可取代的地位,其新宣言是成为印刷和跨媒体领域的顶级展会。drupa 2016的主题是“触摸未来（touch the future）”,...四年一届的世界第一印刷展drupa 2016在5月31日—6月10日如期召开。经过60多年的发展,drupa展会在印刷包装行业内有着无可取代的地位,其新宣言是成为印刷和跨媒体领域的顶级展会。drupa 2016的主题是“触摸未来（touch the future）”,重点展出与印刷和跨媒体领域相关的各类加工技术,覆盖行业全系列应用成果及业务领域,以解决方案为导向的技术和应用成果、展开更多
In this paper,we investigate the orbital behavior of the transition between the quasisatellite(QS)and horseshoe(HS)motions of 2016 HO3.Based on the phase space structure in the Sun-Earth circular restricted three-body...In this paper,we investigate the orbital behavior of the transition between the quasisatellite(QS)and horseshoe(HS)motions of 2016 HO3.Based on the phase space structure in the Sun-Earth circular restricted three-body problem,we find that the surface of 2016 HO in the torus space is a compound surface formed by QS and HS portions.Its co-orbital motion is therefore a QS-HS transition.2016 HO3 is currently located in a QS state,and its locus clings to the QS portion in the isosurface in agreement with the semi-analytical results.We provide a criterion to separate the QS and HS stages in the transition and obtain accurate incoming and outgoing epochs of the QS motion.We then propose an approximate curve to describe the locus of 2016 HO3 in the w-e projection.Virtual asteroids(VAs)near 2016 HO in the isosurface were created to study the infuence of the initial state of the QS-HS transition.We find that the duration of the QS state is mainly influenced by the loci in the w-e projection.The VAs with large QS durations usually have longer loci across the QS region than those with shorter durations.In addition,although some VAs are close to 2016 HO3 in the w-e projection,their co-orbital behaviors are significantly different from that of the latter.This indicates that the QS-HS transition of 2016 HO3 is sensitive to the(w,e)position.展开更多
Asteroid 469219 Kamo'oalewa,also named 2016 HO3,is a small-size fast-rotating near-Earth asteroid,which is a potential target for future explorations.Owing to its weak gravity and fast spin rate,the dynamics on th...Asteroid 469219 Kamo'oalewa,also named 2016 HO3,is a small-size fast-rotating near-Earth asteroid,which is a potential target for future explorations.Owing to its weak gravity and fast spin rate,the dynamics on the surface or in the vicinity of 2016 HO3 are significantly different from those of planets or other small bodies explored in previous missions.In this study,the geophysical and orbital environments of 2016 HO3 were investigated to facilitate a potential mission design.First,the geormnetric and geopotential topographies of 2016 HO3 were examined using difterent shape models.The liftoff and escape conditions on its fast-rotating surface were investigated.Then,the periodic orbits around 2016 HO3 were studied in the asteroid-fixed frame and the Sun-asteroid frame considering the solar radiation pressure.The stable regions of the terminator orbits were discussed using different parameters.Finally,the influence of the nonspherical shape on the terminator orbits was examined.The precise terminator orbits around a real shape model of 2016 HO3 were obtained and verified in the high-fidelity model.This study shows that the polar region of 2016 HO3 is the primary region for landing or sampling,and the terminator orbits are well suited for global mapping and measurements of 2016 HO3.The analysis and methods can also serve as references for the exploration of other small fast-rotating bodies.展开更多
自然界云由于具有动态模式多变、外表不规则等特点,故基于虚拟现实自然现象云模拟是最为复杂的模拟对象之一。该文运用环境光、漫反射光、镜面反射光处理云的光影,采用3ds MAX 2016和Open GL,实现了一天中不同时刻云的仿真以及10种具有...自然界云由于具有动态模式多变、外表不规则等特点,故基于虚拟现实自然现象云模拟是最为复杂的模拟对象之一。该文运用环境光、漫反射光、镜面反射光处理云的光影,采用3ds MAX 2016和Open GL,实现了一天中不同时刻云的仿真以及10种具有代表性云的构造与仿真。通过VC++2016编写程序,并利用AE和PR技术进行后期制作,实现了晴天云、雨天云、雪天云三种常见天气仿真,模拟效果逼真。展开更多
文摘The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.This allows estimates of the characteristics of asteroid 2016HO_(3),the target of the first Chinese asteroid exploration mission,Tianwen 2.We obtain 80 characteristic parameters in 9 categories and analyze their impacts on the mission.By comparing three close-range exploration modes,we provide advantages and disadvantages of each,and propose suitable methods for the exploration of 2016HO_(3).Owing to the weak gravity and small size of 2016HO_(3),a combination of multiple hovering positions and active orbiting is recommended for scientific exploration.
文摘为了研究中卫市香山地区冻雨天气成因并提高该地区冻雨天气的预报能力,本文利用常规观测资料、加密气象观测资料、MICAPS资料和香山风电场工作日志资料,对2016年3月中卫香山风电场出现的一次冰冻雨雪灾害天气过程进行天气学分析,并对冻雨发生的物理量场、大气垂直结构和地形作用进行分析。结果表明,500 h Pa"东高西低"的环流形势是此次天气过程产生的背景条件,低层的偏南暖湿气流输送和低值系统的共同作用是产生降水的根本条件;冻雨产生时段大气温度垂直结构上、中、下层呈冷、暖、冷分布,中层有温度>0℃的暖层,近地面层为0℃或以下,中层冷平流对暖层会有破坏作用,垂直温度结构改变,降水相态随之发生变化;在同一降水过程中,山地和川区大气垂直结构存在明显差别,需关注降水相态是否一致。
基金This study was funded by the Korea Meteorological Administration Research and Development Program(KMI2017-9060)the National Research Foundation of Korea funded by the Korea government(NRF-2018M1A3A3A02066008)+1 种基金In addition,the ALOS-2 PALSAR-2 data used in this study are owned by the Japan Aerospace Exploration Agency(JAXA)and were provided through the JAXA’s ALOS-2 research program(RA4,PI No.1412)The GPS data were provided by the Geospatial Information Authority of Japan.
文摘Conventional synthetic aperture radar(SAR)interferometry(InSAR)has been successfully used to precisely measure surface deformation in the line-of-sight(LOS)direction,while multiple-aperture SAR interferometry(MAI)has provided precise surface deformation in the along-track(AT)direction.Integration of the InSAR and MAI methods enables precise measurement of the two-dimensional(2D)deformation from an interferometric pair;recently,the integration of ascending and descending pairs has allowed the observation of precise three-dimensional(3D)deformation.Precise 3D deformation measurement has been applied to better understand geological events such as earthquakes and volcanic eruptions.The surface deformation related to the 2016 Kumamoto earthquake was large and complex near the fault line;hence,precise 3D deformation retrieval had not yet been attempted.The objectives of this study were to①perform a feasibility test of precise 3D deformation retrieval in large and complex deformation areas through the integration of offset-based unwrapped and improved multiple-aperture SAR interferograms and②observe the 3D deformation field related to the 2016 Kumamoto earthquake,even near the fault lines.Two ascending pairs and one descending the Advanced Land Observing Satellite-2(ALOS-2)Phased Array-type L-band Synthetic Aperture Radar-2(PALSAR-2)pair were used for the 3D deformation retrieval.Eleven in situ Global Positioning System(GPS)measurements were used to validate the 3D deformation measurement accuracy.The achieved accuracy was approximately 2.96,3.75,and 2.86 cm in the east,north,and up directions,respectively.The results show the feasibility of precise 3D deformation measured through the integration of the improved methods,even in a case of large and complex deformation.
文摘四年一届的世界第一印刷展drupa 2016在5月31日—6月10日如期召开。经过60多年的发展,drupa展会在印刷包装行业内有着无可取代的地位,其新宣言是成为印刷和跨媒体领域的顶级展会。drupa 2016的主题是“触摸未来（touch the future）”,重点展出与印刷和跨媒体领域相关的各类加工技术,覆盖行业全系列应用成果及业务领域,以解决方案为导向的技术和应用成果、
基金supported by the Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘In this paper,we investigate the orbital behavior of the transition between the quasisatellite(QS)and horseshoe(HS)motions of 2016 HO3.Based on the phase space structure in the Sun-Earth circular restricted three-body problem,we find that the surface of 2016 HO in the torus space is a compound surface formed by QS and HS portions.Its co-orbital motion is therefore a QS-HS transition.2016 HO3 is currently located in a QS state,and its locus clings to the QS portion in the isosurface in agreement with the semi-analytical results.We provide a criterion to separate the QS and HS stages in the transition and obtain accurate incoming and outgoing epochs of the QS motion.We then propose an approximate curve to describe the locus of 2016 HO3 in the w-e projection.Virtual asteroids(VAs)near 2016 HO in the isosurface were created to study the infuence of the initial state of the QS-HS transition.We find that the duration of the QS state is mainly influenced by the loci in the w-e projection.The VAs with large QS durations usually have longer loci across the QS region than those with shorter durations.In addition,although some VAs are close to 2016 HO3 in the w-e projection,their co-orbital behaviors are significantly different from that of the latter.This indicates that the QS-HS transition of 2016 HO3 is sensitive to the(w,e)position.
基金support from the National Natural Science Foundation of China(Grant Nos.12002028 and 51827806)Beijing Institute of Technology Research Fund Program for Young Scholars,China Postdoctoral Science Foundation funded project(Grant No.2019QT0038)Ann and H.J.Smead Aerospace Engineering Science Department,University of Colorado Boulder。
文摘Asteroid 469219 Kamo'oalewa,also named 2016 HO3,is a small-size fast-rotating near-Earth asteroid,which is a potential target for future explorations.Owing to its weak gravity and fast spin rate,the dynamics on the surface or in the vicinity of 2016 HO3 are significantly different from those of planets or other small bodies explored in previous missions.In this study,the geophysical and orbital environments of 2016 HO3 were investigated to facilitate a potential mission design.First,the geormnetric and geopotential topographies of 2016 HO3 were examined using difterent shape models.The liftoff and escape conditions on its fast-rotating surface were investigated.Then,the periodic orbits around 2016 HO3 were studied in the asteroid-fixed frame and the Sun-asteroid frame considering the solar radiation pressure.The stable regions of the terminator orbits were discussed using different parameters.Finally,the influence of the nonspherical shape on the terminator orbits was examined.The precise terminator orbits around a real shape model of 2016 HO3 were obtained and verified in the high-fidelity model.This study shows that the polar region of 2016 HO3 is the primary region for landing or sampling,and the terminator orbits are well suited for global mapping and measurements of 2016 HO3.The analysis and methods can also serve as references for the exploration of other small fast-rotating bodies.
文摘自然界云由于具有动态模式多变、外表不规则等特点,故基于虚拟现实自然现象云模拟是最为复杂的模拟对象之一。该文运用环境光、漫反射光、镜面反射光处理云的光影,采用3ds MAX 2016和Open GL,实现了一天中不同时刻云的仿真以及10种具有代表性云的构造与仿真。通过VC++2016编写程序,并利用AE和PR技术进行后期制作,实现了晴天云、雨天云、雪天云三种常见天气仿真,模拟效果逼真。
