机器人加工是航天复杂舱段内腔加工的有效手段。针对部分狭窄深腔舱段的加工需求,需在机器人末端附加延长杆以提升操作可达性。然而,延长杆在拓展加工覆盖范围的同时,会增大系统动柔度,极易引发加工颤振,进而影响加工质量与效率。为此,...机器人加工是航天复杂舱段内腔加工的有效手段。针对部分狭窄深腔舱段的加工需求,需在机器人末端附加延长杆以提升操作可达性。然而,延长杆在拓展加工覆盖范围的同时,会增大系统动柔度,极易引发加工颤振,进而影响加工质量与效率。为此,本文提出一种变频可调式调谐质量阻尼器(Tuned mass damper,TMD)的结构设计与参数优化方法,建立了集成调谐质量阻尼器与机器人加工系统的动力学模型。该方法基于偏心曲柄滑块机构实现频率可调,根据电涡流阻尼原理完成阻尼参数调控。进一步开展机器人加工系统动柔度控制试验,结果表明,本文所提方法可使末端动柔度峰值降低67.8%,显著提升加工稳定性边界。展开更多
2D materials including graphene and TMDs have proven interesting physical properties and promising optoelectronic applications.We reviewed the growth,characterization and optoelectronics based on 2D TMDs and their het...2D materials including graphene and TMDs have proven interesting physical properties and promising optoelectronic applications.We reviewed the growth,characterization and optoelectronics based on 2D TMDs and their heterostructures,and demonstrated their unique and high quality of performances.For example,we observed the large mobility,fast response and high photo-responsivity in Mo S;,WS;and WSe;phototransistors,as well as the novel performances in vd W heterostructures such as the strong interlayer coupling,am-bipolar and rectifying behaviour,and the obvious photovoltaic effect.It is being possible that 2D family materials could play an increasingly important role in the future nano- and opto-electronics,more even than traditional semiconductors such as silicon.展开更多
Two-dimensional semiconductors such as transition metal dichalcogenides(TMDs)have attracted much interest in the past decade.Herein,we present an all-physical top-down method for the scalable production of the intrins...Two-dimensional semiconductors such as transition metal dichalcogenides(TMDs)have attracted much interest in the past decade.Herein,we present an all-physical top-down method for the scalable production of the intrinsic TMD quantum sheets(QSs).The phases of the TMDs(e.g.,2H-MoSe_(2),2H-WSe_(2),and Td-WTe2)remain stable during the transformation from bulk to QSs.However,phase transition(from Td to 2H)is detected in MoTe2.Such phase-modulation by size-reduction has never been reported before.The TMD QSs can be well dispersed in solvents,resulting in remarkable photoluminescence with excitation wavelength-,concentration-,and solvent-dependence.Meanwhile,the TMD QSs can be readily solution-processed into hybrid thin films,which demonstrate exceptional nonlinear saturation absorption(NSA).Notably,2H-MoTe2 QSs in poly(methyl methacrylate)show extremely high NSA performance with(absolute)modulation depth up to 46.6%and saturation intensity down to 0.81 MW·cm^(−2).Our work paves the way towards quantum-sized TMDs.展开更多
文摘机器人加工是航天复杂舱段内腔加工的有效手段。针对部分狭窄深腔舱段的加工需求,需在机器人末端附加延长杆以提升操作可达性。然而,延长杆在拓展加工覆盖范围的同时,会增大系统动柔度,极易引发加工颤振,进而影响加工质量与效率。为此,本文提出一种变频可调式调谐质量阻尼器(Tuned mass damper,TMD)的结构设计与参数优化方法,建立了集成调谐质量阻尼器与机器人加工系统的动力学模型。该方法基于偏心曲柄滑块机构实现频率可调,根据电涡流阻尼原理完成阻尼参数调控。进一步开展机器人加工系统动柔度控制试验,结果表明,本文所提方法可使末端动柔度峰值降低67.8%,显著提升加工稳定性边界。
文摘2D materials including graphene and TMDs have proven interesting physical properties and promising optoelectronic applications.We reviewed the growth,characterization and optoelectronics based on 2D TMDs and their heterostructures,and demonstrated their unique and high quality of performances.For example,we observed the large mobility,fast response and high photo-responsivity in Mo S;,WS;and WSe;phototransistors,as well as the novel performances in vd W heterostructures such as the strong interlayer coupling,am-bipolar and rectifying behaviour,and the obvious photovoltaic effect.It is being possible that 2D family materials could play an increasingly important role in the future nano- and opto-electronics,more even than traditional semiconductors such as silicon.
基金supported by the National Natural Science Foundation of China(Nos.52073070,21673054,11874130,and 22073022)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)+1 种基金the National Key R&D Program of China(No.2018YFA0703700)the DNL Cooperation Fund CAS(No.DNL202016).
文摘Two-dimensional semiconductors such as transition metal dichalcogenides(TMDs)have attracted much interest in the past decade.Herein,we present an all-physical top-down method for the scalable production of the intrinsic TMD quantum sheets(QSs).The phases of the TMDs(e.g.,2H-MoSe_(2),2H-WSe_(2),and Td-WTe2)remain stable during the transformation from bulk to QSs.However,phase transition(from Td to 2H)is detected in MoTe2.Such phase-modulation by size-reduction has never been reported before.The TMD QSs can be well dispersed in solvents,resulting in remarkable photoluminescence with excitation wavelength-,concentration-,and solvent-dependence.Meanwhile,the TMD QSs can be readily solution-processed into hybrid thin films,which demonstrate exceptional nonlinear saturation absorption(NSA).Notably,2H-MoTe2 QSs in poly(methyl methacrylate)show extremely high NSA performance with(absolute)modulation depth up to 46.6%and saturation intensity down to 0.81 MW·cm^(−2).Our work paves the way towards quantum-sized TMDs.
