نتایج جستجو برای: مدل echo

تعداد نتایج: 150396  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی اصفهان - دانشکده برق و کامپیوتر 1388

دانشمندان معتقدند که افزایش غلظت گازهای گلخانه ای در اتمسفر باعث تغییر اقلیم خواهد شد. مدل های جهانی اقلیم (gcms) برای تخمین میزان این تغییرات در آینده گسترش یافته اند. اما قدرت تفکیک پایین مدل های جهانی اقلیم، استفاده از آنها را برای مطالعات هیدرولوژیکی و محلی ناممکن کرده است. اکثر مدل های جهانی اقلیم دارای قدرت تفکیک بیشتر ازدو درجه عرض و طول جغرافیایی هستند. به دلیل تفکیک فضایی کم، حذف و یا ...

Journal: :مجله دانشکده پزشکی دانشگاه علوم پزشکی تهران 0
ناصر ابراهیمی دریانی ebrahimi daryani n محسن قناعتی ghenaati m مهدی موسوی moosavi m

hepatomegaly, decrease in the liver paranchymal echo and increase in the gallbladder wall thickness has been shown in acute viral hepatitis. the present study was done to determine sonographic changes in acute viral hepatitis. we performed liver and bile ducts sonography and specific tests on 42 patients (mean age: 31.5 and 61% male) with acute viral hepatitis. gallbladder wall thickness was se...

Journal: : 2022

با توجه به رشد بالای جمعیت در جهان و نیاز اطمینان از امنیت غذایی، افزایش تولید واحد سطح محصولات زراعی به‌منزلة راهبردی اساسی حل مسئلة تأمین غذا به‌شمار می‌رود. سوی دیگر، وجود محدودیت زیرکشت پایین‌بودن میانگین عملکرد برخی کشاورزی مانند گندم کشور، محصول می‌تواند راهکاری عملی پاسخ کشور محسوب شود. یکی مهم‌ترین بیماری‌های فوزاریوم است که، نقش پیش‌بینی این بیماری جلوگیری کاهش بهره‌وری محصول، مدل‌هایی...

Journal: :iranian journal of veterinary medicine 0
mojtaba alishahi associated professor, department of clinical sciences, faculty of veterinary medicine, shahid chamran university of ahvaz, ahvaz, iran zahra tulaby dezfuly faculty of veterinary medicine, shahid chamran university of ahvaz, ahvaz, iran takavar mohammadian faculty of veterinary medicine, shahid chamran university of ahvaz, ahvaz, iran

background: evaluation of herbicide pollution in aquatic environments needs the great concern and the most important echo-pollutant effects of herbicides are related to their effects on non target aquatic organisms. native fish can serve as a proper bio-indicator for evaluation  of pollution on aquatic ecosystems. objectives: to find environmentally friendly herbicides, in this study the acute ...

Journal: :iranian journal of medical physics 0
mahmood nazarpoor department of radiology, faculty of paramedicine, tabriz university of medical sciences, tabriz, iran

introduction contrast-enhanced fluid-attenuated inversion recovery (flair) is one of the mri sequences that can be used for detection and evaluation of pathological changes in the brain. in this work, we have studied the effect of different echo times (te) on the maximum relationship between signal intensity and concentration of the contrast agent using the flair sequence. materials and methods...

Journal: :iranian journal of medical physics 0
mohammad ali oghabian neuroimaging and analysis group, research center of molecular and cellular imaging, tehran university of medical sciences, tehran, iran

introduction echo-planar imaging (epi) is a group of fast data acquisition methods commonly used in fmri studies. it acquires multiple image lines in k-space after a single excitation, which leads to a very short scan time. a well-known problem with epi is that it is more sensitive to distortions due to the used encoding scheme. source of distortion is inhomogeneity in the static b0 field that ...

Journal: :international journal of advanced design and manufacturing technology 0
mohammadmahdi amiri phd student center of excellence in precision dimensional measurement technology development institute (tdi), acecr, sharif university branch. tehran, iran. m. tabatabaee ghomi assistant professor center of excellence in precision dimensional measurement technology development institute (tdi), acecr, sharif university branch. tehran, iran. *corresponding author gh. liaghat full professor mechanical engineering department tarbiat modares university tehran, iran.

in this paper a new method for nondestructive testing or nondestructive evaluation is proposed for glass-epoxy composite. for this purpose, impact-echo is used to evaluate the properties of composite materials, detecting internal defects and thickness measurement. in the impact-echo method a steel ball impacts on a composite plate and generates stress waves or p-waves which will be transferred ...

Journal: :رادار 0
رضا منصوری رضا محسنی

one of the most common signals used for achieving high range resolution in radar is stepped-frequency signals. when a target is stationary in these radars, dft (discrete fourier transform) based processing is used to attain high range resolution profile (hrrp). however, in the case of moving target, due to spreading of the echo signal spectrum, dft based processing is not optimal and decreases ...

بکرانی, مهدی , لطفی زاد, مجتبی ,

Stereophonic acoustic echo cancellation is one of the expanding areas in the field of the speech/multimedia communication systems. In a conventional stereophonic acoustic echo canceller, working in a stereo communication system, the existence of the strong cross-correlation between the input signals to the two channels has the problem of the low convergence speed of the weights of the adaptive ...

Journal: :The European Physical Journal C 2019

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