Before emancipation, most balck women worked for the whites as domestic slaves; After emancipation, most balck women, as domestic emloyees, still had to do hard domestic work for survival, though they had a little fre...Before emancipation, most balck women worked for the whites as domestic slaves; After emancipation, most balck women, as domestic emloyees, still had to do hard domestic work for survival, though they had a little freedom and property. Balck women's identities changed literally, but the social hierarchy of whites'supremacy to blacks and men's supremacy to women still unchanged.展开更多
This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electric...This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electrical unit,have a total volume of 306 L and a total mass of 163.8 kg.These compact and robust units can overcome mechanical vibrations and temperature fluctuations during space launch.The laser sources of the optical unit are composed of diode lasers,and the injection locking of slave lasers is automatically performed by a program.In the experiment,a blue magneto-optical trap of cold atoms was achieved,with the atom numbers estimated to be approximately(1.50±0.13)×10^(6) for 87Sr and(8.00±0.56)×10^(6) for 88Sr.This work establishes a foundation for atomic confinement and high-precision interrogation in space-based optical clocks and expands the frontiers of cold atom physics in microgravity.展开更多
Master robots are integral components of teleoperated robot-assisted minimally invasive surgery systems.Among them,parallel mechanism-based 6-degree-of-freedom master robots are distinguished by low inertia and high-f...Master robots are integral components of teleoperated robot-assisted minimally invasive surgery systems.Among them,parallel mechanism-based 6-degree-of-freedom master robots are distinguished by low inertia and high-force feedback.However,complex kinematics and singularities are the main barriers limiting its usage.This study converts the Hexa-type 6-RUS mechanism into a master robot to construct master-slave teleoperation system.The clinical background is briefly introduced and a representative surgical robot is employed to analyze the master-slave mapping relationship.The inverse/forward kinematics,the Jacobian matrix,and the translation and orientation workspace are derived as the bases of master robot’s application.The architecture parameters are optimized by the global transmission index to achieve better motion/force transmissibility.Based on the optimal result,the prototype and the master-slave control loop are constructed.Finally,the corresponding master-slave teleoperation experiment and model experiment demonstrate that the proposed master robot satisfies the basic need for medical application.展开更多
Whether to be a slave to a child and its upbringing is nowadays a hot topic in China. The term "child’s slave" has become omnipresent in cyberspace. It refers to the group of young parents born in the 1980s...Whether to be a slave to a child and its upbringing is nowadays a hot topic in China. The term "child’s slave" has become omnipresent in cyberspace. It refers to the group of young parents born in the 1980s who have to spend a large part of their income on their children. A survey on www.163.com展开更多
Rising house prices in China’s major cities is a major headache for people taking a first step on the property ladder and has led to a growing number sacrificing quality of life just to have a home of their own Close...Rising house prices in China’s major cities is a major headache for people taking a first step on the property ladder and has led to a growing number sacrificing quality of life just to have a home of their own Closely watching the family’s spend- ing展开更多
文摘Before emancipation, most balck women worked for the whites as domestic slaves; After emancipation, most balck women, as domestic emloyees, still had to do hard domestic work for survival, though they had a little freedom and property. Balck women's identities changed literally, but the social hierarchy of whites'supremacy to blacks and men's supremacy to women still unchanged.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB35010202)the National Natural Science Foundation of China(Grants No.62275268)。
文摘This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electrical unit,have a total volume of 306 L and a total mass of 163.8 kg.These compact and robust units can overcome mechanical vibrations and temperature fluctuations during space launch.The laser sources of the optical unit are composed of diode lasers,and the injection locking of slave lasers is automatically performed by a program.In the experiment,a blue magneto-optical trap of cold atoms was achieved,with the atom numbers estimated to be approximately(1.50±0.13)×10^(6) for 87Sr and(8.00±0.56)×10^(6) for 88Sr.This work establishes a foundation for atomic confinement and high-precision interrogation in space-based optical clocks and expands the frontiers of cold atom physics in microgravity.
基金the National Natural Science Foundation of China(No.62211540723)the Interdisciplinary Program of Shanghai Jiao Tong University(Nos.YG2023ZD05 and YG2023ZD14)+1 种基金the Quanzhou High-Level Talent Innovation and Entrepreneurship Project(No.2021C003R)the Research Project of Institute of Medical Robotics of Shanghai Jiao Tong University。
文摘Master robots are integral components of teleoperated robot-assisted minimally invasive surgery systems.Among them,parallel mechanism-based 6-degree-of-freedom master robots are distinguished by low inertia and high-force feedback.However,complex kinematics and singularities are the main barriers limiting its usage.This study converts the Hexa-type 6-RUS mechanism into a master robot to construct master-slave teleoperation system.The clinical background is briefly introduced and a representative surgical robot is employed to analyze the master-slave mapping relationship.The inverse/forward kinematics,the Jacobian matrix,and the translation and orientation workspace are derived as the bases of master robot’s application.The architecture parameters are optimized by the global transmission index to achieve better motion/force transmissibility.Based on the optimal result,the prototype and the master-slave control loop are constructed.Finally,the corresponding master-slave teleoperation experiment and model experiment demonstrate that the proposed master robot satisfies the basic need for medical application.
文摘Whether to be a slave to a child and its upbringing is nowadays a hot topic in China. The term "child’s slave" has become omnipresent in cyberspace. It refers to the group of young parents born in the 1980s who have to spend a large part of their income on their children. A survey on www.163.com
文摘Rising house prices in China’s major cities is a major headache for people taking a first step on the property ladder and has led to a growing number sacrificing quality of life just to have a home of their own Closely watching the family’s spend- ing
