When modal vectors are estimated from measured frequency response function (FRF) data, some amount of contamination in terms of random and bias errors is always present. The sources of these errors may be the experimental data acquisition process (calibration inconsistencies, averaging limitations, leakage errors, etc.) or due to limitations of the modal parameter estimation methods (mismatch b...

ABSTRACT Frequency response functions (FRF) are the primary means of experimentally evaluating the structural characteristics of vibrating systems. Vibration analyzers estimate the FRF through the ratio of the output/input power spectral densities (PSD); which in turn are estimated using periodograms. However, periodograms are inconsistent estimators. In addition, noise in the input and output ...

The University of Salford has derived exposure-response relationships for vibration caused by railway construction and operation in residential environments. The exposure assessment methodology for almost 1000 case studies has its key factor in the measurement of synchronized ground-to-building frequency response functions (FRF). The latter is obtained by averaging the spectral content of simul...

Of 197 cases of canine oral malignant melanoma, 29 cases with myxoid, cartilage, and osteoid formation were studied pathologically and immunohistochemically. Tumor tissues were classified into spindle cell type (13 cases), epithelioid cell type (1 case), and mixed type (15 cases). Myxoid matrixes (29 tumors) were formed mainly in the tissues of spindle cell type and were positive for Alcian blu...

A well-designed free-running oscillator provides a periodic signal of constant amplitude and frequency fo from the energy delivered by direct-current (dc) sources. This has an immediate application for the realization of local oscillators used in the frequency-conversion stages of communication systems [1]. In receivers, the modulated signal at radio-frequency (RF) fRF is mixed with the output ...

Forty-three patients with cirrhosis and ascites, 21 with normal renal function, 10 with a progressive functional renal failure (FRF), and 12 with a steady FRF, were investigated for the presence of endotoxaemia by the Limulus lysate test. Endotoxaemia was found in nine patients with FRF and in none of the 21 with normal renal function (P less than 0-01). A positive Limulus test was almost exclu...

BACKGROUND Insulin deficiency is the prime basis of all diabetic manifestations and agents that can bring about insulin secretion would be of pivotal significance for cure of diabetes. To test this hypothesis, we carried out bioactivity guided fractionation of Oreocnide integrifolia (Urticaceae); a folklore plant consumed for ameliorating diabetic symptoms using experimental models. METHODS W...

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...

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...

A nonlinear frequency response based adaptive vibration controller is proposed for a class of nonlinear mechanical systems. In order to obtain the nonlinear Frequency Response Function (FRF), the convergence properties of the system are studied by using the convergence (contraction) theory. If the system under consideration is: 1) convergent, it directly enables to derive a nonlinear FRF for a ...