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Ghorashi A.H.,Nuclear Science and Technology Research Institute, Iran | Rahimi A.,Islamic Azad University at Tehran
Renewable and Sustainable Energy Reviews | Year: 2011

This paper reviews the present energy status in Islamic Republic of Iran with an emphasis on utilization of environmentally friendly energy resources. The paper reveals the huge energy losses due to technological gaps and absence of relevant art of know-how in conventional energy industries. It also includes some critical issues effecting the efficient operation of Renewable Energy Converting Systems (RECS) having specific site and climate dependency. The environmentally friendly scaled energy balance presented in this paper is self explaining for energy policy makers to achieve a suitable scenario based on various positions of scale pointer which may alter depending on implementation level of advanced technologies and relevant art of know-how. The paper, besides being informative in achieving optimal energy prospects in Iran, also provides useful quid lines to energy planners not only at home but also in other Asian/Middle Eastern countries having similar alternative energy scenarios. © 2010 Elsevier Ltd.

Hosseinkhani H.,Nuclear Science and Technology Research Institute, Iran | Modarres M.,University of Tehran
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

The leading order (LO) and the next-to-leading order (NLO) unintegrated parton distribution functions (UPDF) are calculated by using the latest version of integrated parton distribution functions (PDF) of Martin et al. (MSTW2008) as the inputs. Similar to our previous works, rather than the Ciafaloni-Catani-Fiorani-Marchesini (CCFM) evolution equations, the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) collinear approximation is used to consider the dependence of parton distributions on the second scale, kt2, the partons transverse momenta, beside the first scale, μ 2, which is included in the last step of DGLAP evolution equation (Kimber et al. procedure). The three-dimensional UPDF are presented in terms of different [x, μ 2]-planes and in the range of CERN LHC energies and the parametrization procedure for the various values of kt2. It is shown that the two-scale UPDF behave similar to their corresponding PDF at large kt2≃106GeV2. In both LO and NLO levels at each kt2 a peak is observed around μ2=kt2 especially at x≃10 -4 (x≤10 -4) for the gluons (quarks). In contrast to the complication which exists in the parameterized PDF i.e. the negative gluon distribution at small x and μ 2, the UPDF are always positive except at large x (≃1) which is mainly due to the angular ordering which makes numerical instability in this region (the values of UPDF are very small). We hope present results could help a better understanding of the LHC data at CERN. © 2012 Elsevier B.V.

Arkani M.,Nuclear Science and Technology Research Institute, Iran | Raisali G.,Nuclear Science and Technology Research Institute, Iran
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2015

Non-random event losses due to dead time effect in nuclear radiation detection systems distort the original Poisson process into a new type of distribution. As the characteristics of the distribution depend on physical properties of the detection system, it is possible to estimate the dead time parameters based on time interval analysis, this is the problem investigated in this work. A BF3 ionization chamber is taken as a case study to check the validity of the method in experiment. The results are compared with the data estimated by power rising experiment performed in Esfahan Heavy Water Zero Power Reactor (EHWZPR). Using Monte Carlo simulation, the problem is elaborately studied and useful range for counting rates of the detector is determined. The proposed method is accurate and applicable for all kinds of radiation detectors with no potential difficulty and no need for any especial nuclear facility. This is not a time consuming method and advanced capability of online examination during normal operation of the detection system is possible. © 2014 Elsevier B.V. Allrightsreserved.

Biosorption of lanthanum (III) and cerium (III) from aqueous solution by tangerine (Citrus reticulate) peel has been investigated in a batch system as a function of pH, biosorbent dosage, contact time, and temperature. The equilibrium pH was found to severely affect the biosorption performance; pH 5.0 was found to be an optimum pH for favorable biosorption of La (III) and Ce (III). The biosorption of lanthanum and cerium was investigated by the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Maximum biosorption uptakes, according to the Langmuir model, were obtained as 154.86 and 162.79 (mg/g) for La(III) and Ce(III), respectively. The biosorption kinetic was tested with pseudo-first order and pseudo-second order models. The results showed that the kinetics of the biosorption process were described by the pseudo-second order model very well. Thermodynamic parameters including the change of Gibbs free energy (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) for both sorption systems were determined at four different temperatures. The results showed that the biosorption of La(III) and Ce(III) on tangerine (C. reticulate) peel is a spontaneous and endothermic process. FTIR analysis demonstrated that carboxyl and hydroxyl groups were involved in the biosorption of the metal ions.

Khani M.H.,Nuclear Science and Technology Research Institute, Iran
Environmental Science and Pollution Research | Year: 2011

Introduction: Kinetic, thermodynamic, and equilibrium isotherms of the biosorption of uranium ions onto Padina sp., a brown algae biomass, in a batch system have been studied. Discussion: The kinetic data were found to follow the pseudo-second-order model. Intraparticle diffusion is not the sole rate-controlling factor. The equilibrium experimental results were analyzed in terms of Langmuir isotherm depending with temperature. Equilibrium data fitted very well to the Langmuir model. The maximum uptakes estimated by using the Langmuir model were 434.8, 416.7, 400.0, and 370.4 mg/g at 10°C, 20°C, 30°C, and 40°C, respectively. Gibbs free energy was spontaneous for all interactions, and the adsorption process exhibited exothermic enthalpy values. Padina sp. algae were shown to be a favorable biosorbent for uranium removal from aqueous solutions. © 2011 Springer-Verlag.

Khani M.H.,Nuclear Science and Technology Research Institute, Iran
Powder Technology | Year: 2011

Prediction of hydrodynamic characteristics is a prerequisite in the design and operation of tapered and mini-tapered fluidized beds. This paper has been focused on the development of generalized models for prediction of minimum fluidization velocity and maximum pressure drop in gas-solid tapered and mini-tapered fluidized beds. The empirical correlations were developed based on dimensionless analysis of empirical data. These correlations have the ability to predict the minimum fluidization velocity and maximum pressure drop in both tapered and cylindrical beds (the beds with tapered angle of zero). The empirical data were collected from tapered beds with different cone angles for various particles. The predicting capability of correlations has been discussed. Predicted values of minimum fluidization velocity and maximum pressure drop by the proposed models compared well with the empirical data. The effects of tapered angle are also discussed. © 2010 Elsevier B.V.

Khani M.H.,Nuclear Science and Technology Research Institute, Iran
Environmental Science and Pollution Research | Year: 2011

Introduction: The application of response surface methodology is presented for optimizing the removal of U ions from aqueous solutions using Padina sp., a brown marine algal biomass. Methods: Box-Wilson central composite design was employed to assess individual and interactive effects of the four main parameters (pH and initial uranium concentration in solutions, contact time and temperature) on uranium uptake. Results and discussion: Response surface analysis showed that the data were adequately fitted to second-order polynomial model. Analysis of variance showed a high coefficient of determination value (R2 = 0.9746) and satisfactory second-order regression model was derived. Conclusion: The optimum pH and initial uranium concentration in solutions, contact time and temperature were found to be 4.07, 778.48 mg/l, 74.31 min, and 37.47°C, respectively. Maximized uranium uptake was predicted and experimentally validated. The equilibrium data for biosorption of U onto the Padina sp. were well represented by the Langmuir isotherm, giving maximum monolayer adsorption capacity as high as 376.73 mg/g. © 2010 Springer-Verlag.

Hariri A.,Nuclear Science and Technology Research Institute, Iran | Sarikhani S.,Nuclear Science and Technology Research Institute, Iran
Optics Letters | Year: 2012

Based on the geometrical modeling of the unified gain coefficient and the reported amplified spontaneous emission (ASE) output energy measurement εASE versus amplifying excitation length, lAMP in a KrF laser oscillator, we managed, as an example, to explain the ASE output energy behavior both numerically and analytically. In this approach, introducing the ASE gain-coefficient profile for the KrF laser, gASE 0.KrF, was not avoidable. It was found that while the g ASE0.KrF profile follows the introduced gain-modeling formulation, it is, however, slightly lower than the KrF laser gain profile, gexp0.KrF, deduced from the measurements reported by different researchers. The present approach, up to the present time, is able to explain all of the existing ambiguities on understanding the ASE behavior. © 2012 Optical Society of America.

Doroudi A.,Nuclear Science and Technology Research Institute, Iran
International Journal of Mass Spectrometry | Year: 2010

In this paper the homotopy perturbation method is used for calculation of axial secular frequencies of a nonlinear ion trap with only hexapole superposition. The motion of the ion in a rapidly oscillating field is transformed to the motion in an effective potential. The equation of ion motion in the effective potential is the equation of an anharmonic oscillator with quadratic nonlinearity. The homotopy perturbation method is used for solving the resulted nonlinear equation and obtaining the expression for ion secular frequency as a function of nonlinear field parameter. The calculated secular frequencies are compared with the results of L.-P. method and the exact results. © 2010 Elsevier B.V.

Farhadi K.,Nuclear Science and Technology Research Institute, Iran
Progress in Nuclear Energy | Year: 2010

In the present paper a mathematical model is developed upon which the velocity of flow during coastdown transient is determined analytically without the use of characteristics of centrifugal pump. The influence of the two most important parameters, kinetic energy in the piping system and kinetic energy of the pump, is considered in the form of a ratio called hereafter an effective energy ratio. This parameter, the effective energy ratio, is found to be a very accurate indicator of the pumping task duration. Preliminary test of the model were made on the existing piping systems related to nuclear reactors. As a case of study the safety of the Tehran Research Reactor (TRR) primary cooling system, an open pool MTR-type research reactor, is investigated. An excellent agreement is noted when the results of the present analytical model are compared with those obtained by the use of experimental characteristics of centrifugal pump of the TRR. A further comparison of the analytical results with collected experimental data for flow coastdown also shows a very good agreement. © 2010 Elsevier Ltd. All rights reserved.

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