نتایج جستجو برای: Radiation models

تعداد نتایج: 1129070  

Journal: :desert 2009
n. ghahreman b. bakhtiari

precipitation and air temperature data, only, are often recorded at meteorological stations, with radiation beingmeasured at very few weather stations, especially in developing countries. therefore there arises a need for suitablemodels to estimate solar radiation for a completion of data sets. this paper is about an evaluation of eight models foran estimation of daily solar radiation (q) from ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ارومیه 1377

the methods which are used to analyze microstrip antennas, are divited into three categories: empirical methods, semi-empirical methods and full-wave analysis. empirical and semi-empirical methods are generally based on some fundamental simplifying assumptions about quality of surface current distribution and substrate thickness. thses simplificatioms cause low accuracy in field evaluation. ful...

Journal: :جغرافیا و توسعه ناحیه ای 0
موسوی بایگی موسوی بایگی اشرف اشرف

the solar radiation received by earth surface is one of the most applicable parameter that is so important in hydrology, agriculture, meteorology and climatological modeling. because of very expensive instrument for measuring the radiation, researchers suggested many different experimental equations to estimate this parameter in different climate. seven models which are calibrated for semi-arid...

Journal: :iranian journal of radiation research 0
s. nikzad department of medical physics, faculty of medical sciences, tarbiat modares university, tehran, iran b. hashemi department of medical physics, faculty of medical sciences, tarbiat modares university, tehran, iran h. mozdarani department of medical genetics, faculty of medical sciences, tarbiat modares university, tehran, iran m.h. zuhair department of immunology, faculty of medical sciences, tarbiat modares university, tehran, iran

background: increasing the complexity in modern radiotherapy techniques have increased the delivery time lowering consequently the treatment efficacy. through simulating the delivery time delay encountered in such techniques, its’ effect on two cancer cell lines and the compensating doses given to prevent such effect was investigated. materials and methods: f10b16 and 4t1 cancer cell lines were...

ژورنال: علوم آب و خاک 2012
سید مجید میرلطیفی, , کامیار بیات, ,

Global solar radiation (Rs( on a horizontal surface in the estimation of evapotranspiration of plants and hydrology studies is an important factor. Average daily global solar radiation on a horizontal surface was estimated by artificial neural networks (ANNs) and five empirical models including FAO (No.56), Hargreaves-Samani, Mahmood-Hubard, Bahel and Annandale. The weather data was selected fr...

Journal: Desert 2009
B. Bakhtiari N. Ghahreman

Precipitation and air temperature data, only, are often recorded at meteorological stations, with radiation beingmeasured at very few weather stations, especially in developing countries. Therefore there arises a need for suitablemodels to estimate solar radiation for a completion of data sets. This paper is about an evaluation of eight models foran estimation of daily solar radiation (Q) from ...

Journal: :iranian journal of nuclear medicine 2008
mohsen hajizadeh seyed rasoul zakavi mehdi momen-nejad maryam naji

introduction: ordered subset expectation maximization (osem), is an effective iterative method for spect image reconstruction. the aim of this study is the evaluation of the role of system matrix in osem image reconstruction method using four different physical beam radiation models with three detection configurations. methods: spect was done with an arc of 180 degree in 32 projections after i...

Journal: :journal of agricultural science and technology 2015
sh. gorjian b. ghobadian t. tavakkoli hashjin

solar radiation data play an important role in solar energy relevant researches. these data are not available for some locations due to the absence of the meteorological stations. therefore, solar radiation data have to be predicted by using solar radiation estimation models. this study presents an integrated artificial neural network (ann) approach for estimating solar radiation potential over...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان - دانشکده برق و کامپیوتر 1392

abstract nowadaysphotovoltaic solar cells (pvs) areacknowledged the fastest growing energy technology in the word, however, they only account for only fraction of current global renewable energy capacity. it isrecognized that this incomplete market penetration has been largely a result of the technology’sexcessive cost. so researchers are trying to find innovative, economic way with theaim of ...

ژورنال: سوخت و احتراق 2008

 A numerical simulation of reactive swirling methane/air non-premixed flame in a new three-dimensional model combustion chamber is carried out to assess the performance of two thermal radiation models, namely, the Discrete Transfer Radiation Model and the P-1 Model. A Finite Volume staggered grid approach is employed to solve the governing equations.The second-order upwind scheme is applied for...

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