There are clearances in mechanism because of manufacture and assembly error,which reduces operation life and working accuracy of mechanism and has a great impact on dynamical responses.At the moment,research in this a...There are clearances in mechanism because of manufacture and assembly error,which reduces operation life and working accuracy of mechanism and has a great impact on dynamical responses.At the moment,research in this area mainly focuses on single degree⁃of⁃freedom mechanism considering one clearance,while research of multi⁃DOF mechanism considering multi⁃clearance is less.With the purpose of studying the dynamical characteristics of complex multi⁃DOF mechanism with multi⁃clearances,a dynamic model was developed.The dynamic responses of 2⁃DOF mechanism with two clearances under different positions,values,and numbers of clearance were analyzed.The displacement,velocity,acceleration,collision force,and the axis trajectory at clearance were then given.In addition,there is a limited amount of literature on chaotic phenomena,which mainly focuses on the chaotic phenomena of end⁃effector of mechanism.But in this paper,the non⁃linear characteristics were analyzed by chaotic phenomenon of clearance joint,then chaotic phenomenon was identified by Poincarémappings and phase diagrams.Bifurcation diagrams were given.The results will offer a reliable technical support for the study of dynamical responses of planar mechanisms and the analysis of chaotic phenomena.展开更多
We investigate the influence of fin architecture on linearity characteristics of AlGaN/GaNFinFET.It is found that the Fin FET with scaled fin dimensions exhibits much flatter Gm characteristics than the one with long ...We investigate the influence of fin architecture on linearity characteristics of AlGaN/GaNFinFET.It is found that the Fin FET with scaled fin dimensions exhibits much flatter Gm characteristics than the one with long fins as well as planar HEMT.According to the comparative study,we provide direct proof that source resistance rather than tri-gate structure itself dominates the Gm behavior.Furthermore,power measurements show that the optimized FinFET is capable of delivering a much higher output power density along with significant improvement in linearity characteristics than conventional planar HEMT.This study also highlights the importance of fin design in GaN-based FinFET for microwave power application,especially high-linearity applications.展开更多
Polarization holography is a newly researched field,that has gained traction with the development of tensor theory.It primarily focuses on the interaction between polarization waves and photosensitive materials.The ex...Polarization holography is a newly researched field,that has gained traction with the development of tensor theory.It primarily focuses on the interaction between polarization waves and photosensitive materials.The extraordinary capabil-ities in modulating the amplitude,phase,and polarization of light have resulted in several new applications,such as holo-graphic storage technology,multichannel polarization multiplexing,vector beams,and optical functional devices.In this paper,fundamental research on polarization holography with linear polarized wave,a component of the theory of polariz-ation holography,has been reviewed.Primarily,the effect of various polarization changes on the linear and nonlinear po-larization characteristics of reconstructed wave under continuous exposure and during holographic recording and recon-struction have been focused upon.The polarization modulation realized using these polarization characteristics exhibits unusual functionalities,rendering polarization holography as an attractive research topic in many fields of applications.This paper aims to provide readers with new insights and broaden the application of polarization holography in more sci-entific and technological research fields.展开更多
This hybrid transducer type linear ultrasonic motor is a new troe of the lineax ultrasonic motor proposed by the authors. This paper describes its basic structure and operation principle, provides its mechedsm of the ...This hybrid transducer type linear ultrasonic motor is a new troe of the lineax ultrasonic motor proposed by the authors. This paper describes its basic structure and operation principle, provides its mechedsm of the large thrust and large seif lock force when power is cut off. The measured characteristics of the prototype motor are shown, its mtalmum thrust is 11 N and mtalmum output power is 1.4 W, the backward and forward motion performances are roughly coincident展开更多
IN 1932, Stone [1] gave the first result concerning C<sub>0</sub> semigroups generated by an unbounded operator,which says that a linear operator is the infinitesimal generator of a C<sub>0</sub&g...IN 1932, Stone [1] gave the first result concerning C<sub>0</sub> semigroups generated by an unbounded operator,which says that a linear operator is the infinitesimal generator of a C<sub>0</sub> group of unitary operators on a Hilbert space if and only if it is skew-adjoint. This result has been applied extensively to linear partial differential equations （PDEs） with a law of conservation. Hille [2] then discovered the generation theorem of the Hille-Yosida type for a C<sub>0</sub> group on a Banach space. There are also some conditions under which a C<sub>0</sub> semigroup on a Banach space can be embedded in a C<sub>0</sub> group. We refer the readers to ref. [3] for details of the results mentioned above.展开更多
基金Sponsored by the Shandong Key Research and Development Public Welfare Program(Grant No.2019GGX104011)the Natural Science Foundation of Shandong Province(Grant No.ZR2017MEE066).
文摘There are clearances in mechanism because of manufacture and assembly error,which reduces operation life and working accuracy of mechanism and has a great impact on dynamical responses.At the moment,research in this area mainly focuses on single degree⁃of⁃freedom mechanism considering one clearance,while research of multi⁃DOF mechanism considering multi⁃clearance is less.With the purpose of studying the dynamical characteristics of complex multi⁃DOF mechanism with multi⁃clearances,a dynamic model was developed.The dynamic responses of 2⁃DOF mechanism with two clearances under different positions,values,and numbers of clearance were analyzed.The displacement,velocity,acceleration,collision force,and the axis trajectory at clearance were then given.In addition,there is a limited amount of literature on chaotic phenomena,which mainly focuses on the chaotic phenomena of end⁃effector of mechanism.But in this paper,the non⁃linear characteristics were analyzed by chaotic phenomenon of clearance joint,then chaotic phenomenon was identified by Poincarémappings and phase diagrams.Bifurcation diagrams were given.The results will offer a reliable technical support for the study of dynamical responses of planar mechanisms and the analysis of chaotic phenomena.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61504125,61474101,and 61505181)
文摘We investigate the influence of fin architecture on linearity characteristics of AlGaN/GaNFinFET.It is found that the Fin FET with scaled fin dimensions exhibits much flatter Gm characteristics than the one with long fins as well as planar HEMT.According to the comparative study,we provide direct proof that source resistance rather than tri-gate structure itself dominates the Gm behavior.Furthermore,power measurements show that the optimized FinFET is capable of delivering a much higher output power density along with significant improvement in linearity characteristics than conventional planar HEMT.This study also highlights the importance of fin design in GaN-based FinFET for microwave power application,especially high-linearity applications.
基金supports from National Key R&D Program of China(2018YFA0701800)Project of Fujian Province Major Science and Technology(2020HZ01012).
文摘Polarization holography is a newly researched field,that has gained traction with the development of tensor theory.It primarily focuses on the interaction between polarization waves and photosensitive materials.The extraordinary capabil-ities in modulating the amplitude,phase,and polarization of light have resulted in several new applications,such as holo-graphic storage technology,multichannel polarization multiplexing,vector beams,and optical functional devices.In this paper,fundamental research on polarization holography with linear polarized wave,a component of the theory of polariz-ation holography,has been reviewed.Primarily,the effect of various polarization changes on the linear and nonlinear po-larization characteristics of reconstructed wave under continuous exposure and during holographic recording and recon-struction have been focused upon.The polarization modulation realized using these polarization characteristics exhibits unusual functionalities,rendering polarization holography as an attractive research topic in many fields of applications.This paper aims to provide readers with new insights and broaden the application of polarization holography in more sci-entific and technological research fields.
文摘This hybrid transducer type linear ultrasonic motor is a new troe of the lineax ultrasonic motor proposed by the authors. This paper describes its basic structure and operation principle, provides its mechedsm of the large thrust and large seif lock force when power is cut off. The measured characteristics of the prototype motor are shown, its mtalmum thrust is 11 N and mtalmum output power is 1.4 W, the backward and forward motion performances are roughly coincident
文摘IN 1932, Stone [1] gave the first result concerning C<sub>0</sub> semigroups generated by an unbounded operator,which says that a linear operator is the infinitesimal generator of a C<sub>0</sub> group of unitary operators on a Hilbert space if and only if it is skew-adjoint. This result has been applied extensively to linear partial differential equations （PDEs） with a law of conservation. Hille [2] then discovered the generation theorem of the Hille-Yosida type for a C<sub>0</sub> group on a Banach space. There are also some conditions under which a C<sub>0</sub> semigroup on a Banach space can be embedded in a C<sub>0</sub> group. We refer the readers to ref. [3] for details of the results mentioned above.
