The cubic stiffness force model(CSFM)and Bouc-Wen model(BWM)are introduced and compared innovatively.The unknown coefficients of the nonlinear models are identified by the genetic algorithm combined with experiments.B...The cubic stiffness force model(CSFM)and Bouc-Wen model(BWM)are introduced and compared innovatively.The unknown coefficients of the nonlinear models are identified by the genetic algorithm combined with experiments.By fitting the identified nonlinear coefficients under different excitation amplitudes,the nonlinear vibration responses of the system are predicted.The results show that the accuracy of the BWM is higher than that of the CSFM,especially in the non-resonant region.However,the optimization time of the BWM is longer than that of the CSFM.展开更多
Dielectric ceramics are essential components in communication systems that operate within the microwave frequency range.In high-density packages,dielectric substrates ceramics must possess high thermal conductivity to...Dielectric ceramics are essential components in communication systems that operate within the microwave frequency range.In high-density packages,dielectric substrates ceramics must possess high thermal conductivity to efficiently dissipate heat.However,achieving adequate thermal conductivity(k)in ceramics sintered at low temperatures is challenging.In this study,we employed the cold sintering process(CSP)to fabricate Li_(2)MoO_(4)-x%Al_(2)O_(3)(0≤x≤80,in volume)ceramics under 200 MPa pressure at 150℃.The Li_(2)MoO_(4)-40%Al_(2)O_(3)composite exhibited significantly enhanced k of 5.4 W·m^(-1)·K^(-1),an 80%increase compared to pure Li_(2)MoO_(4)ceramic with k of 3 W·m^(-1)·K^(-1).At 40%Al_(2)O_(3)content,the Li_(2)MoO_(4)eAl_(2)O_(3)ceramic demonstrated notable microwave properties(ε~6.67,Q×f~17,846 GHz,tf~^(-1)05×10^(-6)℃^(-1)).Additionally,simulation of a microstrip patch antenna for 5 GHz applications using Li_(2)MoO_(4)-20%Al_(2)O_(3)ceramic as dielectric substrate via Finite Element Simulation software showed excellent performance,with radiation efficiency exceeding 99%and low return loss(S_(11)<-30 dB)at both 4.9 GHz and 28.0 GHz center frequencies.These findings underscore the suitability of Li_(2)MoO_(4)eAl_(2)O_(3)ceramics for microwave dielectric substrate.展开更多
文摘The cubic stiffness force model(CSFM)and Bouc-Wen model(BWM)are introduced and compared innovatively.The unknown coefficients of the nonlinear models are identified by the genetic algorithm combined with experiments.By fitting the identified nonlinear coefficients under different excitation amplitudes,the nonlinear vibration responses of the system are predicted.The results show that the accuracy of the BWM is higher than that of the CSFM,especially in the non-resonant region.However,the optimization time of the BWM is longer than that of the CSFM.
基金supported by National Natural Science Foundation of China(No.52361165625)Shenzhen Science and Technology Program,Guangdong Province,China(Nos.KQTD20180411143514543,JCYJ20220818100613029,and JSGGZD20220822095603006)We acknowledge the support of Project 2019CX01C079 of Guangdong Province。
文摘Dielectric ceramics are essential components in communication systems that operate within the microwave frequency range.In high-density packages,dielectric substrates ceramics must possess high thermal conductivity to efficiently dissipate heat.However,achieving adequate thermal conductivity(k)in ceramics sintered at low temperatures is challenging.In this study,we employed the cold sintering process(CSP)to fabricate Li_(2)MoO_(4)-x%Al_(2)O_(3)(0≤x≤80,in volume)ceramics under 200 MPa pressure at 150℃.The Li_(2)MoO_(4)-40%Al_(2)O_(3)composite exhibited significantly enhanced k of 5.4 W·m^(-1)·K^(-1),an 80%increase compared to pure Li_(2)MoO_(4)ceramic with k of 3 W·m^(-1)·K^(-1).At 40%Al_(2)O_(3)content,the Li_(2)MoO_(4)eAl_(2)O_(3)ceramic demonstrated notable microwave properties(ε~6.67,Q×f~17,846 GHz,tf~^(-1)05×10^(-6)℃^(-1)).Additionally,simulation of a microstrip patch antenna for 5 GHz applications using Li_(2)MoO_(4)-20%Al_(2)O_(3)ceramic as dielectric substrate via Finite Element Simulation software showed excellent performance,with radiation efficiency exceeding 99%and low return loss(S_(11)<-30 dB)at both 4.9 GHz and 28.0 GHz center frequencies.These findings underscore the suitability of Li_(2)MoO_(4)eAl_(2)O_(3)ceramics for microwave dielectric substrate.
