An approach is proposed for modeling and anal- yses of rigid multibody systems with frictional translation joints and driving constraints. The geometric constraints of translational joints with small clearance are tre...An approach is proposed for modeling and anal- yses of rigid multibody systems with frictional translation joints and driving constraints. The geometric constraints of translational joints with small clearance are treated as bilat- eral constraints by neglecting the impact between sliders and guides. Firstly, the normal forces acting on sliders, the driv- ing constraint forces （or moments） and the constraint forces of smooth revolute joints are all described by complementary conditions. The frictional contacts are characterized by a set- valued force law of Coulomb＇s dry friction. Combined with the theory of the horizontal linear complementarity problem （HLCP）, an event-driven scheme is used to detect the transi- tions of the contact situation between sliders and guides, and the stick-slip transitions of sliders, respectively. And then, all constraint forces in the system can be computed easily. Secondly, the dynamic equations of multibody systems are written at the acceleration-force level by the Lagrange multiplier technique, and the Baumgarte stabilization method is used to reduce the constraint drift. Finally, a numerical example is given to show some non-smooth dynamical behaviors of the studied system. The obtained results validate the feasibility of algorithm and the effect of constraint stabilization.展开更多
This paper introduced the theory and approaches of building driving forcemodels revealing the changes in land utilization level by integrating RS, GPS, and GIS technologiesbased on the example of Yuanmou County of Yun...This paper introduced the theory and approaches of building driving forcemodels revealing the changes in land utilization level by integrating RS, GPS, and GIS technologiesbased on the example of Yuanmou County of Yunnan Province. We first created the land utilizationtype database, natural driving forces for land utilization database, and human driving forces forland utilization database. Then we obtained the dependent and the independent variables of changesin land utilization level by exploring various data. Lastly we screened major factors affectingchanges in land utilization level by using the powerful spatial correlation analysis and maincomponent analysis module of GIS and obtained a multivariable linear regression model of thechangesin land utilization level by using GIS spatial regression analysis module.展开更多
This year marks the40th anniversary of China’s opening up to the world.One of the key decisions during the early period after opening-up was the restoration of the national college entrance exam.As of today,China has...This year marks the40th anniversary of China’s opening up to the world.One of the key decisions during the early period after opening-up was the restoration of the national college entrance exam.As of today,China has produced nearly100million college students and6million overseas students,which provided a solid human resource background for China’s opening-up and economic growth.展开更多
China’s crude oil imports hit a record high in the first half of 2016 despite an economic slowdown,and analysts largely attributed the surge to low prices,not strategic maneuvering.The country imported 186.5 million ...China’s crude oil imports hit a record high in the first half of 2016 despite an economic slowdown,and analysts largely attributed the surge to low prices,not strategic maneuvering.The country imported 186.5 million tons of crude oil in the first half of the year,23.15 million展开更多
The sound of Suzhou Pingtan,an art form which combines storytelling and ballad singing in the Suzhou dialect,swirled around a hall of the International Department of theCommunist Party of China’s Central Committee(ID...The sound of Suzhou Pingtan,an art form which combines storytelling and ballad singing in the Suzhou dialect,swirled around a hall of the International Department of theCommunist Party of China’s Central Committee(IDCPC)in Beijing on August 31.The singing enchanted the audience,including 400 visiting political party leaders and ambassadors of展开更多
The third thematic seminar of the Stories of the Communist Party of China(CPC)series focusing on party-building,with'Building a Well-disciplined Party in All Aspects:The Practice of Shanxi'as its theme,was hel...The third thematic seminar of the Stories of the Communist Party of China(CPC)series focusing on party-building,with'Building a Well-disciplined Party in All Aspects:The Practice of Shanxi'as its theme,was held in Beijing on June 30.Song Tao,Minister of the International Department of the CPC Central Committee(IDCPC),Luo Huining,Secretary of the CPC Shanxi展开更多
基金supported by the National Natural Science Foundation of China(11372018 and 11172019)
文摘An approach is proposed for modeling and anal- yses of rigid multibody systems with frictional translation joints and driving constraints. The geometric constraints of translational joints with small clearance are treated as bilat- eral constraints by neglecting the impact between sliders and guides. Firstly, the normal forces acting on sliders, the driv- ing constraint forces （or moments） and the constraint forces of smooth revolute joints are all described by complementary conditions. The frictional contacts are characterized by a set- valued force law of Coulomb＇s dry friction. Combined with the theory of the horizontal linear complementarity problem （HLCP）, an event-driven scheme is used to detect the transi- tions of the contact situation between sliders and guides, and the stick-slip transitions of sliders, respectively. And then, all constraint forces in the system can be computed easily. Secondly, the dynamic equations of multibody systems are written at the acceleration-force level by the Lagrange multiplier technique, and the Baumgarte stabilization method is used to reduce the constraint drift. Finally, a numerical example is given to show some non-smooth dynamical behaviors of the studied system. The obtained results validate the feasibility of algorithm and the effect of constraint stabilization.
文摘This paper introduced the theory and approaches of building driving forcemodels revealing the changes in land utilization level by integrating RS, GPS, and GIS technologiesbased on the example of Yuanmou County of Yunnan Province. We first created the land utilizationtype database, natural driving forces for land utilization database, and human driving forces forland utilization database. Then we obtained the dependent and the independent variables of changesin land utilization level by exploring various data. Lastly we screened major factors affectingchanges in land utilization level by using the powerful spatial correlation analysis and maincomponent analysis module of GIS and obtained a multivariable linear regression model of thechangesin land utilization level by using GIS spatial regression analysis module.
文摘This year marks the40th anniversary of China’s opening up to the world.One of the key decisions during the early period after opening-up was the restoration of the national college entrance exam.As of today,China has produced nearly100million college students and6million overseas students,which provided a solid human resource background for China’s opening-up and economic growth.
文摘China’s crude oil imports hit a record high in the first half of 2016 despite an economic slowdown,and analysts largely attributed the surge to low prices,not strategic maneuvering.The country imported 186.5 million tons of crude oil in the first half of the year,23.15 million
文摘The sound of Suzhou Pingtan,an art form which combines storytelling and ballad singing in the Suzhou dialect,swirled around a hall of the International Department of theCommunist Party of China’s Central Committee(IDCPC)in Beijing on August 31.The singing enchanted the audience,including 400 visiting political party leaders and ambassadors of
文摘The third thematic seminar of the Stories of the Communist Party of China(CPC)series focusing on party-building,with'Building a Well-disciplined Party in All Aspects:The Practice of Shanxi'as its theme,was held in Beijing on June 30.Song Tao,Minister of the International Department of the CPC Central Committee(IDCPC),Luo Huining,Secretary of the CPC Shanxi
