Instrumental quality assessment serves as an important tool for evaluating and developing noise reduction systems. Commonly three measures are of major interest: the quality of the speech component, the level of noise attenuation, and the amount of musical tones, as a specific type of noise distortion. The first two measures can already be obtained in an instrumental manner in many applications...

At most mid-ocean ridges, a wide region of decompression melting must be reconciled with a narrow neovolcanic zone and the establishment of full oceanic crustal thickness close to the rift axis. Two competing paradigms have been proposed to explain melt focusing: narrow mantle upwelling due to dynamic effects related to in situ melt or wide mantle upwelling with lateral melt transport in inclin...

Measurements of minimum thicknesses, in a four-layer, overlying tissue model, on 22 pregnancies between 15 and 20 weeks gestation, yielded a global minimum and a mean of the minimum total thickness per patient of 1.7 and 2.9 cm, respectively, and a minimum and mean subcutaneous fat thickness of 0.7 and 1.4 cm. Conservative calculations of the minimum attenuation per patient, at 3.5 MHz indicate...

Quadriceps muscle phenotype varies widely between patients with chronic obstructive pulmonary disease (COPD) and cannot be determined without muscle biopsy. We hypothesised that measures of skeletal muscle adiposity could provide noninvasive biomarkers of muscle quality in this population. In 101 patients and 10 age-matched healthy controls, mid-thigh cross-sectional area, percentage intramuscu...

Attenuation correction is very important for quantitative SPECT imaging. We designed an uncollimated non-uniform line array source (non-uniform LAS) for attenuation correction based on transmission computed tomography (TCT) using Tc-99m and compared its performance with an uncollimated uniform line array source (uniform LAS) in a thorax phantom study. This non-uniform LAS was attached to one ca...

In conventional x-ray imaging, including CT, the peak tube voltage (kVp) is a variable setting that affects image contrast, especially that due to differences in attenuation of high molecular weight substances such as iodine and calcium. For example, attenuation due to iodine at 80 kVp is approximately double that at 120-140 kVp. However, if the tube current (mA) is not adjusted appropriately t...

PURPOSE Cerebral perfusion x-ray computed tomography (PCT) is a powerful tool for noninvasive imaging of hemodynamic information throughout the brain. Conventional PCT requires the brain to be imaged multiple times during the perfusion process, and hence radiation dose is a major concern. The authors propose a PCT reconstruction algorithm that allows for lowering the dose while maintaining a hi...

Even though there exist lots of documents on Finite Element Strength Reduction Method, cohesion and internal friction angle in these materials are reduced through the same reduction factor, which fails to reflect either of their safe reserving quality or the quality to precisely match slope failure process and mechanism. As is known, the exterior angle circumcircle yield criterion DP1 of the ge...

Estimations of scattering parameters, such as average scatterer diameter, from rf signals backscattered from random media (tissues) are made from the frequency dependence of the rf signal. The frequency dependence of the rf signal backscattered from the medium is seen in the normalized power spectrum. The normalized power spectrum is found by taking the squared magnitude of the Fourier transfor...

The object of this study was to compare organ dose and image quality effects of using bismuth and barium vinyl in-plane shields with standard and low tube current thoracic CT protocols. A RANDO phantom was scanned using a 64-slice CT scanner and three different thoracic protocols. Thermoluminescent dosemeters were positioned in six locations to record surface and absorbed breast and lung doses....