نتایج جستجو برای: attenuation quality factor

تعداد نتایج: 1597558  

2014
Gina P Villalobos-Escobar Raúl R Castro

We used a new data set of relocated earthquakes recorded by the Seismic Network of Northeastern Sonora, Mexico (RESNES) to characterize the attenuation of S-waves in the fault zone of the 1887 Sonora earthquake (M w 7.5). We determined spectral attenuation functions for hypocentral distances (r) between 10 and 140 km using a nonparametric approach and found that in this fault zone the spectral ...

Journal: :فیزیک زمین و فضا 0
ایمان گنجی دانشجوی دکتری ژئوفیزیک، گروه ژئوفیزیک، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات حمیدرضا سیاهکوهی دانشیار، گروه فیزیک زمین، مؤسسة ژئوفیزیک دانشگاه

seismic waves travelling through inelastic media are attenuated by the conversion of elastic energy into heat. upon being attenuated, the travelling wave changes: amplitude is reduced, travelling waveform is modified due to high-frequency content absorption, and phase is delayed. attenuation is usually quantified through the quality factor q: the ratio between the energy stored and lost in each...

Journal: :Investigative radiology 2016
Kai Higashigaito Daniela B Husarik Jens Barthelmes André R Plass Robert Manka Francesco Maisano Hatem Alkadhi

OBJECTIVE The aim of this study was to evaluate the potential of contrast media (CM) reduction in computed tomography angiography (CTA) of coronary artery bypass grafts (CABGs) when adapting CM volume to automatically selected tube voltages. MATERIAL AND METHODS Sixty consecutive patients (mean age, 71 ± 14.5 years) with a total of 176 CABGs (692 bypass segments) underwent contrast-enhanced p...

2012

A of seismic waves is sensitive to the physical properties of the subsurface and has been observed in vertical seismic profiling (VSP) and reflection data. De et al. (1994) report measurements of the Pand S-wave quality factors from VSP surveys and sonic logs. Klimentos (1995) measures compressional and shear attenuation from sonic logs in sandstone formations with variable oil, water, and gas...

2017
Katarina Sjögreen Michael Ljungberg

For activity quantification based on planar scintillation camera measurements, photon attenuation is an important factor that needs to be corrected for in a patientand organ-specific manner. One possibility for obtaining attenuation correction maps is to use X-ray CT scout images. Since the intensity of scout images is in relative numbers, their image values need to be multiplied by a factor to...

Journal: :Cancer biotherapy & radiopharmaceuticals 2012
Katarina Sjögreen Gleisner Michael Ljungberg

For activity quantification based on planar scintillation camera measurements, photon attenuation is an important factor that needs to be corrected for in a patient- and organ-specific manner. One possibility for obtaining attenuation correction maps is to use X-ray CT scout images. Since the intensity of scout images is in relative numbers, their image values need to be multiplied by a factor ...

2014
Rami Reddy Satya Prasad S. China Venkateswarlu

This paper investigates the effect of Gaussian window frequency response Side lobe Attenuation on the improvement of Speech quality in terms of six objective quality measures. In Speech Enhancement process, signal corrupted by noise is segmented into frames and each segment is Windowed using Gaussian window with variation in the side lobe attenuation parameter “α”. The Windowed Speech segments ...

Journal: :Malaysian Journal of Fundamental and Applied Sciences 2023

WDM (wavelength division multiplexing) is used in this project to simultaneously send data over several channels at high speed. Single mode fiber favored Multimode for long-distance communication. As rate and optical length grow, the quality factor falls. Dispersion effects on an 8-channel dense system a will be examined using Optisystem 10 simulator. A dispersion compensation (DCF) Erbium dope...

Journal: :journal of rangeland science 2011
kh. ebrahimi s. feiznia m. jannat rostami kh. ausati

assessing the quality of groundwater is important to ensure the sustainablesafe use of these resources. however, describing the overall water quality condition isdifficult due to the spatial variability of multiple contaminants and the wide range ofindicators (chemical, physical and biological) that could be measured. therefore, in thiscase study, some water quality parameters including na, mg,...

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