We report the development of a field programmable gate array (FPGA) based frequency response analyzer (FRA) for impedance frequency response function (FRF) measurements using periodic excitations, i.e. sine waves and multisines. The stepped sine measurement uses two dedicated hardware-built digital embedded multiplier blocks to extract the phase and quadrature components of the output signal. T...

The Frequency Response Function (FRF) of a nonlinear system under white Gaussian ezcitation is computed up to O(P2) in the power spectral density of the input P. The FRF qualitatively shows the ezpected shifts in resonant frequency and supports the observed fact that FRFs from fandam excitation are returned as lkar system FRFs by the Hzlbert transform test.

The frequency domain technique is both iterative and adaptive, involving convolution of the measured Inverse Multiple Input Multiple Output (MIMO) Frequency Response Function (FRF) matrix with the matrix of reference time histories. In contrast to the time domain technique, the frequency domain technique can adapt during a test by performing real time updates of the FRF matrix between drive and...

This paper aims to give a quantitative description of the linguistic acoustic properties, i.e., fundamental frequency and duration, of a seven-tone dialect in Qiyang County (QY hereafter), south of Hunan Province, China. There are seven surface contrasting tones in the QY dialect, a branch of Old Xiang group . No acoustic analysis has been done in the QY dialect so far. What this paper concentr...

The success rate of orthopaedic implants is strongly dependent on the initial fixation, but the objective intra-operative assessment of primary stability of cementless implants is still a challenge and, moreover, excessive press-fitting of the implant can cause intraoperative fractures. In a series of in vitro and in vivo experiments the change in the frequency response function (FRF) of the hi...

A Finite Element Analysis (FEA) and Fourier transform approach to obtain frequency response function (FRF) is presented in this paper. The aim in this paper is to eliminate the need for the classical impact experimental approach used in extracting structure’s FRF. The numerical and experimental FRFs have been used to obtain stable regions in machining of thin walled structures, which gives a go...

This paper introduces an interval sensitivity procedure that calculates the sensitivity of the envelope response function in the outcome of the interval FRF analysis to each individual interval model uncertainty. The procedure focuses on the calculation of the sensitivity of the bounds defining the FRF response range to the width of each individual uncertain input parameter. The approach differ...

The dynamic responses of finite element model do not match with those of the experimental results due to modeling and measurement errors. It is impractical to collect the data for the full set of DOFs of a dynamic system. And there are some cases to have difficulty in measuring the response such as slope. This work presents an analytical method to estimate the frequency response function (FRF) ...

The need of high frame-rate imaging has been triggered by the new applications of ultrasound imaging to transient elastography and real-time 3D ultrasound. Using plane wave excitation (PWE) is one of the methods to achieve very high frame-rate imaging since an image can be formed with a single insonification. However, due to the lack of transmit focusing, the image quality with PWE is lower com...

The utility of a risk function in clinical practice is an important concept that has received insufficient attention. The authors evaluated the clinical usefulness of the Framingham risk function (FRF) for cardiovascular disease in a Middle Eastern population (2,640 men and 3,584 women aged 30–74 years) free of cardiovascular disease at baseline in 1999. They calculated the net benefit fraction...