نتایج جستجو برای: reference noise

تعداد نتایج: 459024  

جعفری , محمدجواد, حاتمی , جواد, علی محمدی , ایرج, محرابی , یداله, کاظم پور , مرضیه,

Background and Purpose: Although the evolution of industrial systems toward digital technologies decreased the exposure to high levels of noise, it has created some problems encountered with low level and provoking noise (low frequency noise). In the present work, the mental performance of students exposed to low frequency and reference noises at low and high levels (45 & 65 dB) were studied....

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تحصیلات تکمیلی صنعتی کرمان - پژوهشکده برق و کامپیوتر 1390

a phase-locked loop (pll) based frequency synthesizer is an important circuit that is used in many applications, especially in communication systems such as ethernet receivers, disk drive read/write channels, digital mobile receivers, high-speed memory interfaces, system clock recovery and wireless communication system. other than requiring good signal purity such as low phase noise and low spu...

Journal: :international journal of occupational hygiene 0
mohammadjavad jafari department of occupational health engineering, school of health, shahid beheshti university of medical sciences, tehran, iran. marzieh kazempour department of occupational health engineering, school of health, shahid beheshti university of medical sciences, tehran, iran.

low frequency noise (lfn) is ubiquitous in both occupational and general environments. mental performance of subjects exposed to lfn is expected to be impaired. individual characters seem to play a significant role in this process. this study aimed to evaluate the effects of moderate levels of lfn (20–200 hz) on mental performance. fifty-three subjects (in two groups) were exposed to low and fl...

Bahareh Shalchian Hamid Soltanian-Zadeh Hossein Rajabi,

Introduction: An efficient method of tomographic imaging in nuclear medicine is positron emission tomography (PET). Compared to SPECT, PET has the advantages of higher levels of sensitivity, spatial resolution and more accurate quantification. However, high noise levels in the image limit its diagnostic utility. Noise removal in nuclear medicine is traditionally based on Fourier decomposition o...

ژورنال: سلامت کار ایران 2011
جعفری, محمد جواد, حاتمی, جواد, علیمحمدی, ایرج, محرابی, یداله, کاظم پور, مرضیه,

    Background and aims  The influences of Low Frequency Noise (LFN) on mental performance have been the objectives of many papers in recent years. Many researchers believe that the LFN even at low pressure levels has impacts on mental performance. In the present work the influences of LFN and Reference Noise (RN) at two different sound pressure levels (45 & 65 dBA) on mental performances of co...

Journal: :iranian journal of medical physics 0
bahareh shalchian ph.d. student, medical physics dept., faculty of medical sciences, tarbiat modares university, tehran, iran hossein rajabi associate professor, medical physics dept., faculty of medical sciences, tarbiat modares university, tehran, iran hamid soltanian-zadeh professor, control and intelligent processing center of excellence, electrical and computer engineering dept., university of tehran, tehran, iran

introduction: an efficient method of tomographic imaging in nuclear medicine is positron emission tomography (pet). compared to spect, pet has the advantages of higher levels of sensitivity, spatial resolution and more accurate quantification. however, high noise levels in the image limit its diagnostic utility. noise removal in nuclear medicine is traditionally based on fourier decomposition o...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت معلم تهران - دانشکده علوم 1372

in this study reference as one of the five cohesive devices in the achievement of textuality in english and persian narrative/descripitive written texts is focused on and analysed . to do so , the theoretical framework elaborated by halliday and hasan (1976) and its version adapted by the writer to match the sub-types of reference in farsi are applied to the analysis of reference in english and...

Journal: :iranian journal of medical physics 0
sh. olumi m.sc. in medical physics, tarbiat modarres university, tehran, iran h. rajabi assistant professor, medical physics dept., tarbiat modarres university, tehran, iran s.r. zakavi associate professor, nuclear medicine dept., imam reza hospital, mashhad university of medical sciences, mashhad, iran e. hajizade associate professor, biostatistics dept., tarbiat modarres university, tehran, iran h. ghiasi m.sc. in medical physics, torfe hospital, tarbiat modarres university, tehran, iran

introduction: one of the major problems in the development of nuclear medicine images is the presence of noise. the noise level in nuclear medicine images is usually reduced by the analysis of imaging data in a fourier transform environment. the main drawback of this environment belongs to low signal to noise ratio in high frequencies because removing noise frequencies may remove data and times...

E. Hajizade H. Ghiasi H. Rajabi S.R. Zakavi Sh. Olumi

Introduction: One of the major problems in the development of nuclear medicine images is the presence of noise. The noise level in nuclear medicine images is usually reduced by the analysis of imaging data in a Fourier transform environment. The main drawback of this environment belongs to low signal to noise ratio in high frequencies because removing noise frequencies may remove data and times...

Journal: :ELECTRONICS: Science, Technology, Business 2017

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