نتایج جستجو برای: time frequency transform
تعداد نتایج: 2342512 فیلتر نتایج به سال:
Background: Central retinal vein occlusion (CRVO) is the second most common retinal vascular disorder after diabetic retinopathy. In this study, we tried to examine the potentials of time-frequency methods for differentiating the eyes with CRVO. Materials and methods: Twenty patients with unilateral CRVO were included in this study. Their contralateral normal eyes were considered as the control...
When a train runs at high speed, affected by the structural characteristics of catenary, contact force changes periodically with span and dropper spacing. However, as running speed increases, periodic signal owing to fluctuation catenary vibration pantograph, which directly affects stable between pantograph catenary. Therefore, based on simulation research method, this study uses time–frequency...
magnetotelluric (mt) method is an important passive surface geophysical method which uses the earth’s natural electromagnetic fields to investigate the electrical resistivity structure of the subsurface. the depth of investigation of mt is much higher than that of other electromagnetic (em) methods (vozoff, 1991). for a general conductivity distribution in the earth, the horizontal electric fie...
Background and purpose: Retinitis Pigmentosa (RP) is one of the retinal degeneration diseases affecting the eye signals. Electroretinogram (ERG) is a signal that plays an important role in diagnosis and treatment of RP. This signal includes useful information that cannot be revealed just in time domain. We aimed to investigate the effect of RP on time, frequency, and time-frequency parameters o...
In order to improve the time-frequency resolutions of short-time fractional Fourier transform, adaptive short-time fractional Fourier transform (ASTFRFT) method is used in this paper. The optimal order of ASTFRFT is given by maximizing kurtosis of signals in fractional domain, where the window width of ASTFRFT is searched by the maximal Shannon entropy of timefrequency distribution. Short-time ...
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