نتایج جستجو برای: Positivity

تعداد نتایج: 21000  

Journal: :archives of pediatric infectious diseases 0
ferial lotfian clinical tuberculosis and epidemiology research center, national research institute of tuberculosis and lung diseases (nritld), masih daneshvari hospital, shahid beheshti university of medical sciences, tehran, ir iranسازمان اصلی تایید شده: دانشگاه علوم پزشکی شهید بهشتی (shahid beheshti university of medical sciences) payam mehrian chronic respiratory diseases research center, national research institute of tuberculosis and lung diseases (nritld), masih daneshvari hospital, shahid beheshti university of medical sciences, tehran, ir iran; chronic respiratory diseases research center, national research institute of tuberculosis and lung diseases (nritld), masih daneshvari hospital, shahid beheshti university of medical sciences, tehran, ir iran. tel: +98-2127122003, fax: +98-2120109484سازمان اصلی تایید شده: دانشگاه علوم پزشکی شهید بهشتی (shahid beheshti university of medical sciences)

background cavitary pulmonary tuberculosis (tb) is rare in children. objectives the aim of this study was to evaluate the characteristics of cavitary pulmonary tb in children. patients and methods this retrospective study was conducted on 97 children less than 15 years old with pulmonary tb to assess the clinical characteristics and radiographic findings of patients with cavitary lesions. resul...

Journal: :journal of mathematical modeling 0
mohammad mehdizadeh khalsaraei department of mathematics, faculty of science, university of maragheh maragheh, iran reza shokri jahandizi department of mathematics, faculty of science, university of maragheh, maragheh, iran

classical explicit finite difference schemes are unsuitable for the solution of the famous black-scholes partial differential equation, since they impose severe restrictions on the time step. furthermore, they may produce spurious oscillations in the solution. we propose a new scheme that is free of spurious oscillations and guarantees the positivity of the solution for arbitrary stepsizes. the...

Journal: :journal of mining and environment 2013
ali nejati kalateh amin roshandel kahoo

we inverse the surface gravity data to recover subsurface 3d density distribution with two strategy. in the first strategy, we assumed wide density model bound for inverting gravity data and in the second strategy, the inversion procedure have been carried out by limited bound density. wediscretize the earth model into rectangular cells of constant andunidentified density. the number of cells i...

Journal: :computational methods for differential equations 0
mohammad mehdizadeh khalsaraei university of maragheh

systems in which reaction terms are coupled to diffusion and advection transports arise in awide range of chemical engineering applications, physics, biology and environmental. in these cases, thecomponents of the unknown can denote concentrations or population sizes which represent quantities andthey need to remain positive. classical finite difference schemes may produce numerical drawbacks s...

2009
Rajendra Bhatia Takashi Sano

We give elementary proofs of the fact that the Loewner matrices [ f(pi)−f(pj) pi−pj ] corresponding to the function f(t) = t on (0,∞) are positive semidefinite, conditionally negative definite, and conditionally positive definite, for r in [0, 1], [1, 2], and [2, 3], respectively. We show that in contrast to the interval (0,∞) the Loewner matrices corresponding to an operator convex function on...

When one solves differential equations, modeling physical phenomena, it is of great importance to take physical constraints into account. More precisely, numerical schemes have to be designed such that discrete solutions satisfy the same constraints as exact solutions. Based on general theory for positivity, with an explicit third-order Runge-Kutta method (we will refer to it as RK3 method) pos...

Journal: :Annals of Physics 1999

Journal: :Linear Algebra and its Applications 1988

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