نتایج جستجو برای: domain methods in term of dimensionless frequency

تعداد نتایج: 24514066  

Journal: :فیزیک زمین و فضا 0
احسان ذبیحی نائینی حمیدرضا سیاهکوهی

spectral decomposition is a powerful tool for analysis of seismic data. fourier transform determines the frequency contents of a signal. but for analysis of non-stationary signals, 1-d transform to frequency domain is not sufficient. in early years, transforming of seismic traces into time and frequency domain was done via windowed fourier transform, called a short time fourier transform (stft)...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شاهد - دانشکده علوم پایه 1388

introduction acetic acid bacteria are large group of obligate aerobic gram negative bacteria with the ability to oxidize ethanol to acetic acid (1). they are widely distributed in natural habitats and classified in family acetobacteraceae. members of this family are useful in industrial production of vinegar(2). acetic acid bacteria (aab) can use substrates as glucose, ethanol, lactate or glyc...

2013
Marilena N. Poulou

where Ω is a bounded domain of R, n ≤ 2 with κ, α, λ > 0. The variable ψ stands for the dimensionless low frequency electron field, whereas φ denotes the dimensionless low frequency density. This system in one dimension describes the nonlinear interaction between high frequency electron waves and low frequency ion plasma waves in a homogeneous magnetic field, adapted to model the UHH plasma hea...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علامه طباطبایی 1390

introruction khawf in(iran)-herat and mazaresharif and shirkhan bandar in (afghanistan)-dushanbe in (tajikistan)_(kirgizstan)-kashghar in(china) project railway network is under construction that it is as a significant corridor for revitalizing silk road corridor in the region .at the present there are three different gauge in the region central asia with 1,520 mm gauge and turkey-islamic repu...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد یزد - دانشکده برق و الکترونیک 1392

امروزه تخمین حرکت بلوک در تصاویر بر اساس روش هایی که تمام جزئیات را شامل می شوند، تبدیل به یک مبحث فراگیر در شاخه ی پردازش تصویر گشته است. چرا که از جمله ی روش هایی به حساب می آید که باعث فشردگی و کاهش حجم داده های تصویری می گردد. جهت تحقّق این هدف، الگوریتم های متفاوتی ارائه شده اند. الگوریتم های جستجوی محلی، جستجوی پیشگویانه و... که با توجه به نیاز مسأله انتخاب و مورد استفاده قرار می گیرند، از...

Periodic noises are repetitive patterns on digital images and decreased the visual quality of images. The various methods for reducing the effects of the periodic noise in digital images are firstly investigated. Then an intelligent median filter in the frequency domain with an acceptable computational cost is proposed. In the proposed method, the regions of noise frequencies are determined by ...

Journal: :فیزیک زمین و فضا 0
مریم خاکی فیروز کارشناس ارشد پردازش داده های لرزه ای، شرکت کدکم حمیدرضا سیاهکوهی دانشیار، گروه فیزیک زمین، مؤسسة ژئوفیزیک دانشگاه تهران

the stolt (f-k) migration algorithm is a direct (i.e. non-recursive) fourier-domain technique based on a change of variables (or equivalently, a mapping) that converts the input spectrum to the output spectrum. the algorithm is simple and efficient but limited to constant velocity. a v(z)(f-k) migration method, capable of very high accuracy for vertical variations of velocity, can be formulated...

Harmonics have become an important issue in modern power systems. The widespread penetration of non-linear loads to emerging power systems has turned power quality analysis into an important operation issue under both steady state and transient conditions. This paper employs an Extended Harmonic Domain (EHD) based framework for dynamic analysis of long term analysis over voltages during the tra...

ژورنال: ژئوفیزیک ایران 2020
Mahjoobeh Meskaranian Peyman Pour Moghaddam

This study derives the discretized adjoint states full waveform inversion (FWI) in both time and frequency domains based on the Lagrange multiplier method. To achieve this, we applied adjoint state inversion on the discretized wave equation in both time domain and frequency domain. Besides, in this article, we introduce reliability tests to show that the inversion is performing as it should be ...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید