نتایج جستجو برای: fractional model

تعداد نتایج: 2154119  

Journal: :international journal of data envelopment analysis 2014
m. nazari m.r. mozaffari j. gerami

in data envelopment analyze (dea) the scale efficiency in the input-oriented ccr model is less than or equal to the scale efficiency in dea based on the fractional analysis (dea-r). also, the scale efficiency in case of multiple inputs and one output and vice versa the scale efficiencies are equal in dea and dea-r. in this paper, first, dea-r model with weight restrictions when there is relativ...

Journal: :computational methods for differential equations 0
mohammadreza ahmadi darani department of applied mathematics, faculty of mathematical sciences, shahrekord university, p.o. box 115, shahrekord, iran. mohammad hossein derakhshan department of applied mathematics, faculty of mathematical sciences, shahrekord university, p.o.box 115, shahrekord, iran alireza ansari department of applied mathematics, faculty of mathematical sciences, shahrekord university, p.o.box 115, shahrekord, iran reza khoshsiar department of applied mathematics, faculty of mathematical sciences, shahrekord university, p.o.box 115, shahrekord, iran

in this article, we survey the asymptotic stability analysis of fractional differential systems with the prabhakar fractional derivatives. we present the stability regions for these types of fractional di fferential systems. a brief comparison with the stability aspects of fractional differential systems in the sense of riemann-liouville fractional derivatives is also given.

Journal: :Journal of computational physics 2015
Farzad Sabzikar Mark M. Meerschaert Jinghua Chen

Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution....

Journal: :journal of sciences, islamic republic of iran 2012
g.b. loghmani

in this paper, boundary value problems of fractional order are converted into an optimal control problems. then an approximate solution is constructed from translations and dilations of a b-spline function such that the exact boundary conditions are satisfied. the fractional differential operators are taken in the riemann-liouville and caputo sense. several example are given and the optimal err...

Journal: :iranian red crescent medical journal 0
hoda noorkojuri department of biostatistics, faculty of medical sciences,tarbiat modares university, tarbiat modares university, tehran, ir iran ebrahim hajizadeh department of biostatistics, faculty of medical sciences,tarbiat modares university, tarbiat modares university, tehran, ir iran; tarbiat modares university, jalal ale ahmad highway, tehran, ir iran, tel: +98-2182883810, fax: +98-2182884555 ahmadreza baghestani 2. department of biostatistics, faculty of paramedical sciences, shahid beheshti university of medical sciences, tehran, ir iran mohamadamin pourhoseingholi department of biostatistics, gastroenterology and liver diseases research center, shahid beheshti university of medical sciences, tehran, ir iran

conclusions the use of smoothing methods helps us to eliminate non-linear effects but it is more appropriate to use cox proportional hazards model in medical data because of its’ ease of interpretation and capability of modeling both continuous and discrete covariates. also, cox proportional hazards model and smoothing methods analysis identified that age at diagnosis and tumor size were indepe...

2006
Carlos Escudero

The Keller-Segel model is a system of partial differential equations modelling chemotactic aggregation in cellular systems. This model has blowing up solutions for large enough initial conditions in dimensions d ≥ 2, but all the solutions are regular in one dimension; a mathematical fact that crucially affects the patterns that can form in the biological system. One of the strongest assumptions...

Fractional order diffusion equations are generalizations of classical diffusion equations which are used to model in physics, finance, engineering, etc. In this paper we present an implicit difference approximation by using the alternating directions implicit (ADI) approach to solve the two-dimensional space-time fractional diffusion equation (2DSTFDE) on a finite domain. Consistency, unconditi...

Journal: :JSW 2011
Chunna Zhao Yu Zhao Liming Luo Yingshun Li

Education assessment is one of important measures that will be to ensure and continuously improve the educational level and educational quality. A fractional order model method for education evaluation is proposed in this paper. Improved fractional Basset force model is referred to constitute the complex education evaluation model. The detailed descriptions are displayed through building block ...

Journal: :Calculus of Variations and Partial Differential Equations 2014

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