نتایج جستجو برای: multiple diffraction and inhomogeneous medium

تعداد نتایج: 16957240  

2006
V. A. Khokhlova O. A. Sapozhnikov

A new parabolic equation is derived to describe the propagation of nonlinear sound waves in inhomogeneous moving media. The equation accounts for diffraction, nonlinearity, absorption, scalar inhomogeneities (density and sound speed), and vectorial inhomogeneities (flow). A numerical algorithm employed earlier to solve the KZK equation is adapted to this more general case. A two-dimensional ver...

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

the present research study attempted to find out the extent to which two pre-task activities of “glossary of unknown vocabulary items” and “content related support” assisted efl language learners with their performance on listening comprehension questions across two different proficiency levels (low and high). data for this study were obtained from a total of 120 language learners, female and m...

Journal: :European journal of applied physic 2021

Although the diffraction of light is a simple experiment in optics, no complete interpretation that satisfactorily describes any instance has been developed. Classical physics unable to describe phenomena by considering photons solely as particles. In addition, modern mathematical solutions based on wave-particle duality, including Rayleigh–Sommerfeld theory, are merely approximations, and fail...

M. Allahverdi, M.H. Zahmatkesh, M.R. Ay, N. Riyahi Alam, T. Allahverdi Pourfallah,

Background: Polymer gel dosimetry is still the only dosimetry method for direct measuring of threedimensional dose distributions. MRI Polymer gel dosimeters are tissue equivalent and can act as a phantom material. In this study the obtained isodose maps with PAGAT polymer gel dosimeter were compared to those calculated with EGSnrs for singleshot irradiations of 8 and 18 mm collimators of...

Journal: :Acta Crystallographica Section A Foundations of Crystallography 1981

2002
J. Ponce

In brane-world theory in five dimensions, the bulk metric is usually written in gaussian coordinates, where g 4µ = 0 and g 44 = −1. However, the choice g 44 = −1 is not mandatory. The presence of matter in the brane can generate temporal and spatial variations of g 44 , which in turn backreact on the brane. In this paper we study the consequences of having g 44 = ǫΦ 2 , where ǫ = ±1 and Φ is a ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه کاشان - دانشکده علوم انسانی 1389

abstract poor reading comprehension can result in failure in using references, benefiting from professional gatherings and resources, keeping up with the growing body of knowledge in the virtual world of the internet, and failing to achieve in efl programs. the purpose of the present quasi-experimental study was to explore the effects of background knowledge and previewing narrative and expos...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت دبیر شهید رجایی - دانشکده علوم انسانی 1392

the main purpose of the present study was to investigate the relationship between listening proficiency and metacognitive listening strategies awareness among low, mid, and highly self-regulated students. three hundred and seventy one efl students participated in this study (all grade 3 and 4 high-school students who were studying in khansar in academic year 1391-92). to gather the data, three ...

2014
Timothy Van Renterghem

The finite-difference time-domain (FDTD) method, solving the inhomogeneous, moving medium sound propagation equations, also referred to as the Linearized Euler(ian) Equations (LEE), has become a mature reference outdoor sound propagation model during the last two decades. It combines the ability to account for complex wave effects like reflection, scattering and diffraction near arbitrary objec...

2005
K. E. Feldman

A new method of diagonalisation of the XY-Hamiltonian of inhomogeneous open linear chains with periodic (in space) changing Larmor frequencies and coupling constants is developed. As an example of application, multiple quantum dynamics of an inhomogeneous chain consisting of 1001 spins is investigated. Intensities of multiple quantum coherences are calculated for arbitrary inhomogeneous chains ...

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