The interplay between noise and nonlinearites can lead to escape dynamics.Associated nonlinear phe-nomena have been observed in various applications ranging from climatology to biology and engineering.For reasons of c...The interplay between noise and nonlinearites can lead to escape dynamics.Associated nonlinear phe-nomena have been observed in various applications ranging from climatology to biology and engineering.For reasons of computational ease,in most studies,Gaussian white noise is used.However,this noise model is not physical due to the associated infinite energy content.Here,the authors present extensive experimental investigations and numerical simulations conducted to examine the impact of noise color on escape times in nonlinear oscillators.With a careful parameterization of the numerical simulations,the authors are able to make quantitative comparisons with experimental results.Through the experi-ments and simulations,it is illustrated that the noise color can drastically influence escape times and escape probability.展开更多
The original article includes the incorrectly printed Figs.1,2 and 4.The correct figures are included in this note.Fig.1.(a)Experimental setup:The shaker is used to generate the external,harmonic and random excitation...The original article includes the incorrectly printed Figs.1,2 and 4.The correct figures are included in this note.Fig.1.(a)Experimental setup:The shaker is used to generate the external,harmonic and random excitation to the base of the metal cantilever.The resulting oscillations are measured with a strain gauge.A nonlinear restoring force follows from the magnets mounted at the cantilever tip and the fixed frame.(b)Measured cantilever response to sinusoidal excitation and experimental procedure:A sweep up is used to realize the high amplitude orbit.When the excitation frequency reaches 39.6 Hz,noise is added to the input and a noise induced escape is observed.(c)Time series of a strain gauge signal:The forcing frequency is 39.6 Hz and the response is initiated in the high energy orbit.After about 37.0 s an escape towards the low amplitude orbit is observed.展开更多
Studies of fluid-structure interactions associated with flexible structures such as flapping wings require the capture and quantification of large motions of bodies that may be opaque. As a case study, motion capture ...Studies of fluid-structure interactions associated with flexible structures such as flapping wings require the capture and quantification of large motions of bodies that may be opaque. As a case study, motion capture of a free flying Manduca sexta, also known as hawkmoth, is considered by using three synchronized high-speed cameras. A solid finite element(FE) representation is used as a reference body and successive snapshots in time of the displacement fields are reconstructed via an optimization procedure. One of the original aspects of this work is the formulation of an objective function and the use of shadow matching and strain-energy regularization. With this objective function, the authors penalize the projection differences between silhouettes of the captured images and the FE representation of the deformed body. The process and procedures undertaken to go from high-speed videography to motion estimation are discussed, and snapshots of representative results are presented.Finally, the captured free-flight motion is also characterized and quantified.展开更多
基金CMMI 1760366 and the as-sociated data science supplementsA preliminary report of this work has been presented and discussed at the ASME 2022 Inter-national Design Engineering Technical Conference&Computer and Information in Engineering conference(IDETC/CIE 2022)。
文摘The interplay between noise and nonlinearites can lead to escape dynamics.Associated nonlinear phe-nomena have been observed in various applications ranging from climatology to biology and engineering.For reasons of computational ease,in most studies,Gaussian white noise is used.However,this noise model is not physical due to the associated infinite energy content.Here,the authors present extensive experimental investigations and numerical simulations conducted to examine the impact of noise color on escape times in nonlinear oscillators.With a careful parameterization of the numerical simulations,the authors are able to make quantitative comparisons with experimental results.Through the experi-ments and simulations,it is illustrated that the noise color can drastically influence escape times and escape probability.
文摘The original article includes the incorrectly printed Figs.1,2 and 4.The correct figures are included in this note.Fig.1.(a)Experimental setup:The shaker is used to generate the external,harmonic and random excitation to the base of the metal cantilever.The resulting oscillations are measured with a strain gauge.A nonlinear restoring force follows from the magnets mounted at the cantilever tip and the fixed frame.(b)Measured cantilever response to sinusoidal excitation and experimental procedure:A sweep up is used to realize the high amplitude orbit.When the excitation frequency reaches 39.6 Hz,noise is added to the input and a noise induced escape is observed.(c)Time series of a strain gauge signal:The forcing frequency is 39.6 Hz and the response is initiated in the high energy orbit.After about 37.0 s an escape towards the low amplitude orbit is observed.
基金Support received for this project from the US National Science Foundation (Grant CMMI-1250187)the US Air Force Office of Scientific Research (Grant FA95501510134) is gratefully acknowledged
文摘Studies of fluid-structure interactions associated with flexible structures such as flapping wings require the capture and quantification of large motions of bodies that may be opaque. As a case study, motion capture of a free flying Manduca sexta, also known as hawkmoth, is considered by using three synchronized high-speed cameras. A solid finite element(FE) representation is used as a reference body and successive snapshots in time of the displacement fields are reconstructed via an optimization procedure. One of the original aspects of this work is the formulation of an objective function and the use of shadow matching and strain-energy regularization. With this objective function, the authors penalize the projection differences between silhouettes of the captured images and the FE representation of the deformed body. The process and procedures undertaken to go from high-speed videography to motion estimation are discussed, and snapshots of representative results are presented.Finally, the captured free-flight motion is also characterized and quantified.
