نتایج جستجو برای: spectral methods

تعداد نتایج: 2013357  

2016
J. Jaros F. Vaverka B. E. Treeby

The simulation of ultrasound wave propagation through biological tissue has a wide range of practical applications. However, large grid sizes are generally needed to capture the phenomena of interest. Here, a novel approach to reduce the computational complexity is presented. The model uses an accelerated k-space pseudospectral method which enables more than one hundred GPUs to be exploited to ...

2013
Yiting Huang Minling Zheng

This paper presents a numerical scheme for space fractional diffusion equations (SFDEs) based on pseudo-spectral method. In this approach, using the Guass-Lobatto nodes, the unknown function is approximated by orthogonal polynomials or interpolation polynomials. Then, by using pseudo-spectral method, the SFDE is reduced to a system of ordinary differential equations for time variable t. The hig...

Journal: :international journal of industrial mathematics 0
a. shoja‎ department of mathematics‎, ‎science and research branches‎, ‎islamic azad university‎, ‎tehran‎, ‎iran. e. babolian department of mathematics‎, ‎science and research branches‎, ‎islamic azad university‎, ‎tehran‎, ‎iran. a. r. vahidi department of mathematics‎, ‎science and research branches‎, ‎islamic azad university‎, ‎tehran‎, ‎iran.

in this paper, a new spectral-iterative method is employed to give approximate solutions of fractional logistic differential equation. this approach is based on combination of two different methods, i.e. the iterative method cite{35} and the spectral method. the method reduces the differential equation to systems of linear algebraic equations and then the resulting systems are solved by a numer...

Journal: :تحقیقات مهندسی کشاورزی 0
محمدعلی رستمی استادیار بخش تحقیقات فنی و مهندسی کشاورزی مرکز تحقیقات کشاورزی و منابع طبیعی استان کرمان محمدحسین رئوفت استاد گروه مکانیک ماشین های کشاورزی دانشگاه شیراز

satellite imagery was used as a rapid and spatially explicit method to delineate crop residue cover and to estimate the use and intensity of conservation tillage. the potential of multispectral high-spatial resolution of worldview-2 local data was evaluated using 11 satellite spectral indices and linear spectral unmixing analysis (lsua). experimental plots were examined; residue cover was measu...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه پیام نور - دانشگاه پیام نور استان تهران - دانشکده علوم اجتماعی و اقتصادی 1389

abstract nowadays, the science of decision making has been paid to more attention due to the complexity of the problems of suppliers selection. as known, one of the efficient tools in economic and human resources development is the extension of communication networks in developing countries. so, the proper selection of suppliers of tc equipments is of concern very much. in this study, a ...

In many applications of color technology such as spectral color reproduction it is of interest to represent the spectral data with lower dimensions than spectral space’s dimensions. It is more than half of a century that Principal Component Analysis PCA method has been applied to find the number of independent basis vectors of spectral dataset and representing spectral reflectance with lower di...

Journal: :پژوهش های جغرافیای طبیعی 0
مهدی بلواسی کارشناسی ارشد سنجش از دور و gis، دانشکدة جغرافیا، دانشگاه تبریز صیاد اصغری سراسکانرود استادیار گروه ژئومورفولوژی، دانشکدة ادبیات و علوم انسانی، دانشگاه ارومیه بتول زینالی استادیار گروه اقلیم شناسی، دانشکدة ادبیات و علوم انسانی، دانشگاه محقق اردبیلی سعیده صاحبی وایقان دانشجوی کارشناسی ارشد سنجش از دور و gis، دانشکدة جغرافیا، دانشگاه خوارزمی

introduction in recent decades, a large variety of science experts, including geology and mine scientists, have considered remote sensing technology as one of the most important instruments to receive information. access to hyper spectral data is one of the main evolutions in the remote sensing technology. the main feature of the technology is its application in identification of minerals and d...

Identifying spoken language automatically is to identify a language from the speech signal. Language identification systems can be divided into two categories, spectral-based methods and phonetic-based methods. In the former, short-time characteristics of speech spectrum are extracted as a multi-dimensional vector. The statistical model of these features is then obtained for each language. The ...

2010
Wilhelm Heinrichs WILHELM HEINRICHS

For the known spectral methods (Galerkin, Tau, Collocation) the condition number behaves like 0(N4) (N: maximal degree of polynomials). We introduce a spectral method with an 0(N2) condition number. The advantages with respect to propagation of rounding errors and preconditioning are demonstrated. A direct solver for constant coefficient problems is given. Extensions to variable coefficient pro...

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