نتایج جستجو برای: radiofrequency spectrum
تعداد نتایج: 241794 فیلتر نتایج به سال:
INTRODUCTION AND OBJECTIVES Although electro- physiological databases contain information about changes in the time domain in lesions produced by radiofrequency ablation, very few data on changes in the frequency domain are available. The aim of this study was to investigate changes in the spectral characteristics of ventricular fibrillation in zones with radiofrequency lesions. METHODS Recor...
Abstract The serrodyne principle enables an electromagnetic signal to be frequency shifted by applying a linear phase ramp in the time domain. This phenomenon has been exploited shift signals radiofrequency, microwave and optical regions of spectrum over ranges up few gigahertz, for example, analyse Doppler radiofrequency noise suppression stabilization. Here we employ this centre high-power fe...
The signs of radiofrequency phases and frequencies used in are also fraught with subtle sign problems, for example, NMR are examined carefully. Some fundamental problems with cross-correlated relaxation (4–9) , nuclear demagnetizing current usage are exposed by simple examples. The entire chain of field effects (10–13) , and phase or frequency shifts induced events leading to the NMR spectrum i...
Background: Pre-exposure to radiofrequency radiations of mobile phones would significantly increase the survival rate of exposed animals compared to those exposed to a lethal dose of gamma radiation alone. Stimulation of the immune system is believed to be a key mechanism for the induction of this phenomenon, the so-called “adaptive response.†The immune system protects organisms against in...
The levels of maximum power density of GSM signals in the cities of Lagos, Ibadan and Abuja were studied. Measurements were made with a calibrated hand held spectrum analyzer 200m away from 271 base stations, at 1.2m to the ground level. The maximum GSM 900 signal power density was 139.63μW/m in Lagos, 162.49μW/m in Ibadan and 5411.26μW/m in Abuja. Also, the maximum GSM 1800 signal power densit...
Minimally invasive therapies are gaining increasing attention as an alternative to standard surgical therapies in the treatment of primary hepatocellular carcinoma. These include therapies administered transcatheterally (arterial embolization, intraarterial chemoinfusion, and combination chemoembolization) and percutaneously (chemical ablation with ethanol or acetic acid, and thermal ablation w...
Advances in health information technology provide significant opportunities for improvements in surgical patient safety. The adoption and use of electronic health records can enhance communication along the surgical spectrum of care. Bar coding and radiofrequency identification technology are strategies to prevent retained surgical sponges and for tracking the operating room supply chain. Compu...
سیستم های طیف گسترده(spread spectrum) امروزه به طور وسیعی مورد استفاده قرار می گیرند. این سیستم ها ابتدا توسط ارتش آمریکا و در طی جنگ جهانی دوم مورد استفاده قرار گرفت. در سیستم های طیف گسترده دنباله خطی (direct sequence spread spectrum) سیگنال داده در یک دنباله شبه نویز ضرب می شود تا پهنای باند افزایش یابد. در گیرنده نیز سیگنال دریافتی پس از دمدولاسیون در یک دنباله شبه نویز همانند دنباله موجود ...
Numerical Modeling of Non-equilibrium Plasma Discharge of Hydrogenated Silicon Nitride (SiH4/NH3/H2)
In this work, we model a radiofrequency discharge of hydrogenated silicon nitride in a capacitive coupled plasma reactor using Maxwellian and non-Maxwellian electron energy distribution function. The purpose is to investigate whether there is a real advantage and a significant contribution using non-Maxwellian electron energy distribution function rather than Maxwellian one for determining the ...
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