نتایج جستجو برای: filters

تعداد نتایج: 44041  

Filters are particularly important class of LTI systems. Digital filters have great impact on modern signal processing due to their programmability, reusability, and capacity to reduce noise to a satisfactory level. From the past few decades, IIR digital filter design is an important research field. Design of an IIR digital filter with desired specifications leads to a no convex optimization pr...

Journal: :iranian journal of nuclear medicine 2003
ahmad bitarafan rajabi hossein rajabi nahid yaghoobi fereidoon rastgoo seyed hassan firoozabadi

myocardial perfusion spect imaging with tc99m-sestamibi is the most accurate non-invasive means of detecting coronary artery disease and assessing the severity of perfusion abnormalities in the patients with coronary stenosis. though simple and straight forward the results produced by the technique is very much affected by the details being used. one of the main problems with the test, which ha...

Background and Objectives: In the most Iranian hospitals the internal air is cooled by a system comprising centrifugal blower fan and excelsior filters. Because amoeba can be present in air and dust it may enter into filters of cooling systems. It has been suggested that diffusion of amoebae cyst through air canals may contribute to various types of nosocomial infections. This ...

ژورنال: سلامت و محیط زیست 2011
رضایی, لیلا, علی پور, ولی,

Background and Objectives:Dual media filters have two different layer beds consist of sand and Anthracite. Advantage of dual media filters is longer run duration and more filtration rate. The purpose of this study was to achieve a performable model to improve single media Filters in water treatment plants.Materials and Methods: in this cross-sectional study, two pilots mono and dual media were ...

A Mostaar, M Tabatabaeefar N Yousefi Moteghaed,

Background: Nowadays, image de-noising plays a very important role in medical analysis applications and pre-processing step. Many filters were designed for image processing, assuming a specific noise distribution, so the images which are acquired by different medical imaging modalities must be out of the noise. Objectives: This study has focused on the sequence filters which are selected ...

 A step-by-step algorithm for enhancement of periodic signals that are highly corrupted by additive uncorrelated white gausian noise is proposed. In each adaptation step a new parallel second-order section is added to the previous filters. Every section has only one adjustable parameter, i.e., the center frequency of the self-tuning filter. The bandwidth and the convergence factor of each secti...

Journal: :iranian journal of nuclear medicine 2007
elham raeisi hossein rajabi mahmoud reza aghamiri ebrahim hajizadeh shahram seifollahi-asl

introduction: filtering can greatly affect the quality of clinical images. determining the best filter and the proper degree of smoothing can help to ensure the most accurate diagnosis. methods: forty five patient’s data aquired during brain phantom spect studies were reconstructed using filtered back-projection technique. the ramp, shepp-logan, cosine, hamming, hanning, butterworth, metz and w...

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