Low frequency (O(10 Hz-10 kHz)) vibration excitation of capillary waves has been extensively studied for nearly two centuries. Such waves appear at the excitation frequency or at rational multiples of the excitation frequency through nonlinear coupling as a result of the finite displacement of the wave, most often at one-half the excitation frequency in so-called Faraday waves and twice this fr...

Active vibration control (AVC) can solve many problems. However, structural in underwater vehicles often involves other factors such as complex excitation and path coupling, etc. At present, the traditional algorithm (e.g., multi Filtered-x Least Mean Square, M-FxLMS) usually cannot effectively process multi-frequency coupling effects of multi-secondary path, which will affect its convergence s...

Abstract This paper presents the development of a cabin noise testing equipment that will be used to evaluate interior regional aircraft as well aid reduction techniques. The innovative generation system consists three loudspeaker arrays positioned around fuselage circumference synthesize pressure field is similar seen by during flight. acoustic generated loudspeakers measured number microphone...

Metamaterials have emerged as promising solutions for manipulation of sound waves in a variety of applications. Locally resonant acoustic materials (LRAM) decrease sound transmission by 500% over acoustic mass law predictions at peak transmission loss (TL) frequencies with minimal added mass, making them appealing for weight-critical applications such as aerospace structures. In this study, pot...

We report on a study of terahertz (THz) generation using implanted InGaAs photomixers and multi-wavelength quantum dot lasers. We carry out InGaAs materials growth, optical characterization, device design and fabrication, and photomixing experiments. This approach is capable of generating a comb of electromagnetic radiation from microwave to terahertz. For shortening photomixer carrier lifetime...

Multi-frequency atomic force microscopy (MF-AFM), employing the detection and/or excitation of multiple cantilever frequencies, has shown great promise in increasing the compositional sensitivity, and the spatial and temporal resolution of imaging. The multitude of frequency components generated in MF-AFM encode information about the tip-sample nonlinearity. For quantitative interpretation of t...

The dynamic characteristics of the complex relationship among sealing system, excitation, and response have a considerable impact on operational reliability hydrodynamic mechanical seals, which is critical issue in field theory technology. Scholars at home abroad established models calculated displacement responses static rings time domain based force these so that results can be used for syste...

BACKGROUND Ultrasound transient elastography technology has found its place in elastography because it is safe and easy to operate. However, it's application in deep tissue is limited. The aim of this study is to design an ultrasound transient elastography system with coded excitation to obtain greater detection depth. METHODS The ultrasound transient elastography system requires tissue vibra...

Dynamic Ratcheting (DR) is a nonlinear dynamic phenomenon occurring in hysteretic damping systems. It means the structural plastic deformation increases asymmetrically in successive cycles under an earthquake excitation. Although it is generally recognized that DR is closely related to the frequency contents of an earthquake excitation applied to thestructure, no targeted analysis has bee...