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    Cardy-Verlinde formula and Achúcarro-Ortiz black hole

    , Article Physical Review D ; Volume 68, Issue 6 , 2003 ; 05562821 (ISSN) Setare, M. R ; Vagenas, E. C ; Sharif University of Technology
    American Physical Society  2003
    In this paper it is shown that the entropy of the black hole horizon in Achúcarro-Ortiz spacetime, which is the most general two-dimensional black hole derived from the three-dimensional rotating Banados-Teitelboim- Zanelli black hole, can be described by the Cardy-Verlinde formula. The latter is supposed to be an entropy formula of conformai field theory in any dimension. © 2003 The American Physical Society  

    Iterative interference cancellation and decoding for a coded UWB-TH-CDMA system in AWGN channel

    , Article 7th IEEE International Symposium on Spread Spectrum Techniques and Applications, IEEE ISSSTA 2002, 2 September 2002 through 5 September 2002 ; Volume 1 , 2002 , Pages 263-267 ; 0780376277 (ISBN) Bayesteh, A ; Nasiri Kenari, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2002
    In this paper, we consider a low-complexity iterative receiver lor decoding multi-user information data in a bandwith efficient convolutionally coded TH-UWB-CDMA system introduced in [1]. The proposed receiver structure consists of a bank of soft interference canceller likelihood calculators (SICLC). each followed by a soft-input soft-output (SISO) convolutional decoder, Information is fed back from SISO decoders to SICLCs for interference cancellation. Each SICLC then provides soft information about coded symbols in the form of log-likelihood ratio (LLR), which is used by the corresponding SISO decoder as a priori information about coded symbols. We evaluate the performance of the proposed... 

    Kinetic parameters evaluation of PWRs using static cell and core calculation codes

    , Article Annals of Nuclear Energy ; Volume 41 , 2012 , Pages 110-114 ; 03064549 (ISSN) Jahanbin, A ; Malmir, H ; Sharif University of Technology
    In this paper, evaluation of the kinetic parameters (effective delayed neutron fraction and prompt neutron lifetime) in PWRs, using static cell and core calculation codes, is reported. A new software has been developed to link the WIMS, BORGES and CITATION codes in Visual C# computer programming language. Using the WIMS cell calculation code, multigroup microscopic cross-sections and number densities of different materials can be generated in a binary file. By the use of BORGES code, these binary-form cross-sections and number densities are converted to a format readable by the CITATION core calculation code, by which the kinetic parameters can be finally obtained. This software is used for... 

    First-principle electronic structure calculation of BaFe2-x Cox As2 (X = 0,1, 2) superconductor

    , Article Journal of Superconductivity and Novel Magnetism ; Volume 28, Issue 8 , August , 2015 , Pages 2249-2254 ; 15571939 (ISSN) Shafiei, M ; Khosroabadi, H ; Akhavan, M ; Sharif University of Technology
    Springer New York LLC  2015
    The equilibrium crystal structure and electronic structure of BaFe2-x Cox As2 (x = 0,1, 2) superconductor have been investigated by using the pseudopotential Quantum Espresso code based on the ab initio density functional theory in the generalized gradient approximation. The equilibrium crystal structure for x = 1.0 has been determined by considering five different Fe/Co configurations. This study shows that the spin calculation is essential to obtain the experimental values at x = 0.0. The total and partial density of states, band structure, and Fermi surfaces of the three compounds has been calculated. Density of states calculation indicates the important... 

    Development of a 2-D 2-group neutron noise simulator for hexagonal geometries

    , Article Annals of Nuclear Energy ; Volume 37, Issue 8 , 2010 , Pages 1089-1100 ; 03064549 (ISSN) Malmir, H ; Vosoughi, N ; Zahedinejad, E ; Sharif University of Technology
    In this paper, the development of a neutron noise simulator for hexagonal-structured reactor cores using both the forward and the adjoint methods is reported. The spatial discretisation of both 2-D 2-group static and dynamic equations is based on a developed box-scheme finite difference method for hexagonal mesh boxes. Using the power iteration method for the static calculations, the 2-group neutron flux and its adjoint with the corresponding eigenvalues are obtained by the developed static simulator. The results are then benchmarked against the well-known CITATION computer code. The dynamic calculations are performed in the frequency domain which leads to discarding of the time... 

    First-principles study on ZnV2O6 and Zn2V2O7: two new photoanode candidates for photoelectrochemical water oxidation

    , Article Ceramics International ; Volume 44, Issue 6 , 2018 , Pages 6607-6613 ; 02728842 (ISSN) Sameie, H ; Sabbagh Alvani, A. A ; Naseri, N ; Du, S ; Rosei, F ; Sharif University of Technology
    Elsevier Ltd  2018
    We used first principles calculations based on density functional theory with generalized gradient approximation to investigate and compare the structural, electronic and optical properties of two photoanode materials, ZnV2O6 and Zn2V2O7, for use in photocatalytic water splitting. After geometry optimization, the calculated structural parameters evince a satisfactory agreement with the reported experimental results indicating that the used method and conditions are suitable. The electronic structures demonstrate that both photocatalysts possess favorable band gaps (2.31 and 2.52 eV) and appropriate band edge positions for oxygen evolution reaction under solar radiation. The relatively light... 

    Fuel management optimization based on power profile by Cellular Automata

    , Article Annals of Nuclear Energy ; Volume 37, Issue 12 , 2010 , Pages 1712-1722 ; 03064549 (ISSN) Fadaei, A. H ; Moghaddam, N. M ; Zahedinejad, E ; Fadaei, M. M ; Kia, S ; Sharif University of Technology
    Fuel management in PWR nuclear reactors is comprised of a collection of principles and practices required for the planning, scheduling, refueling, and safe operation of nuclear power plants to minimize the total plant and system energy costs to the extent possible. Despite remarkable advancements in optimization procedures, inherent complexities in nuclear reactor structure and strong inter-dependency among the fundamental parameters of the core make it necessary to evaluate the most efficient arrangement of the core. Several patterns have been presented so far to determine the best configuration of fuels in the reactor core by emphasis on minimizing the local power peaking factor (Pq). In... 

    Development of a Multi-Dimensional and Multi-Group Code for Black and Gray Dancoff Factor Calculation Based on Monte Carlo Method in Various Geometries

    , M.Sc. Thesis Sharif University of Technology Ghaderi Mazaher, Meysam (Author) ; Vossoughi, Nasser (Supervisor)
    Most of the nuclear codes used equivalence between a homogeneous and heterogeneous region to calculate resonance shelf-shielding. when fuels are together in a lattice arrangement, As a good approximation in the resonance shelf-shielding calculation, one could only consider a single fuel lump and consider the effect of neighbor fuels with a correction factor, i.e. the Dancoff coefficient. So far, several methods have used for calculating the Dancoff coefficient, but accuracy of these methods did not improved. In this thesis a computer program (MCDAN-3D) is developed for calculation of the multi-dimension and multi-group black and gray Dancoff coefficient, based on Monte Carlo, escape... 

    Group Authentication in Secure IP Multicast Using One-Time Password

    , M.Sc. Thesis Sharif University of Technology Ghanbari Maman, Reza (Author) ; Nemaney Pour, Alireza (Supervisor)
    Since the number of Internet users for the services such as e-applications is increasing rapidly, authentication constrains more latency as well as load to the system. It is due to large number of users whose identity needs to be checked and compared individually, and the number of simultaneous authentication requests in a specific time. To solve the stated issues, this thesis proposes a new definition of group authentication and describes group authentication protocols. Group authentication is the verification of identity of multiple requests of users at the same time. In this protocol, the authentication server inputs the multiple authentication requests in a function, and then applies... 

    Simulation & Design of a Gamma Scanner System for Radioactive Waste Drums with Low and Intermediate Level Activity

    , M.Sc. Thesis Sharif University of Technology Bagheri, Hamed (Author) ; Samadfam, Mohammad (Supervisor)
    In this thesis, a Segmented Gama Scanning System for measuring total activity of the low/intermediate level radioactive waste drums is designed and a prototype 3-segmented commercial system is manufactured by using NaI detectors. The optimum distance of detector from drum surface and the optimum number of detectors on reconstruction of the radioactivity of the waste drum were studied by MCNP simulations. In addition, the effects of inhomogeneous distribution of radioactivity, the addition of lead filters to detectors, the change in collimator length and the asymmetrical placement of a drum on the rotary plate were also examined by the MCNP calculations. In the absence of a real radioactive... 

    Elastic Moduli Tensors, Ideal Strength, and Morphology of Stanene based on an Enhanced Continuum Model and First Principles

    , M.Sc. Thesis Sharif University of Technology Etehadieh koochak, Azadeh (Author) ; Mohammadi Shoja, Hossein (Supervisor)
    Nowadays, multifunctional two-dimensional (2D) nanostructured materials due to their important role in biomedical and nanotechnological developments have gained the attention of many engineers and scientists with a wide spectrum of disciplines. The present work aims to provide an accurate description of the tensile behavior (from the initial unloaded state through axial strain of about 0.25) of the planar as well as low-buckled stanene and to capture their ideal strength in armchair- and zigzag-directions. Stanene is 2D hexagonal lattice which belongs to D6 hcrystal class having a six-fold rotational symmetry. For an accurate description of anisotropic response of such hyperelastic materials... 

    Primordial Black Holes as Dark Matter

    , M.Sc. Thesis Sharif University of Technology Rahimi, Maryam (Author) ; Baghram, Shant (Supervisor)
    The existance of Dark Matter (DM)has been proved by cosmological and astronomical observation. Yet, all the evidences are based on gravitational effects. It is plausible that DM has a gravitational nature. Any creature with a pure gravitational essence has a chance to bea DM candidate. Primordial Black holes are formed from the density perturbations that are induced by the quantum fluctuations of the vaccum during the inflationary expansion. It is probable that these creatures are the solution of DM problem. By holding the power spectrum that generates the abundance of PBH with the one resulting from observation based on the presumed inflationary model in common, considering the... 

    Design of a Barge Equipped with Turbojet for oil well Fire Extinguishing

    , M.Sc. Thesis Sharif University of Technology Heidari Aliabadi , Mojtaba (Author) ; Abbaspour Tehrani fard, Majid (Supervisor) ; Mehdigholi, Hamid (Supervisor)
    In this thesis, the use of jet-engine for oil well fire fighting which is a latest in kind is described and analyzed. For this purpose, more familiarization with this system and some knowledge’s such as hydrodynamics characteristic of nominated area, traditional ways of fire fighting in region, different types of jet engines available type of offshore vessels, type of flame and their characteristic are required, which after studying and analyzing above fields in details, the use of turbojet motors and barge has been chosen for the case to obtain optimum specification os this turbojet motors and required dimensions of barge Some information about oil well shuch as, fluid output, speed rate... 

    Structure and Conformational Study of Drug Compounds using NMR and Ab-initio Calculations

    , Ph.D. Dissertation Sharif University of Technology Chashmniam, Saeed (Author) ; Tafazzoli, Mohsen (Supervisor)
    NMR spectroscopy as a powerful technique is often used to investigate on structural and conformational studies on proteins and drug compounds. In this work, conformations and structural properties of drug compounds and some nucleoside derivations have been studied using advanced NMR techniques including H-H COSY, HMQC, HMBC and NOESY and quantum based calculations.Experimental analysis on Valsartan show that there are two simultaneous conformers (M and m) with unequal population in M-m type solvents and two stable conformers (N and n) in the N-n type solvents. As the results show, different intramolecular hydrogen bond is the reason for stability af all available conformers. In the... 

    A Nanoscopic Approach to the Determination of the Elastic Constants of Cubic Crystals in first Strain Gradient Theory

    , M.Sc. Thesis Sharif University of Technology Moosavian, Hashem (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    In many problems, the traditional elasticity cannot predict phenomenon such as nano-scale defects, surface effects, and stress concentration correctly. For example, analysis near the crack tip, dislocation and inhomogeneity shows inconsistent results because in this case values of stress go to infinity. Therefore for solving these kinds of problems, higher order continuum theories were introduced. The appearance of additional constants in the equations of motion can represent the atomic nature of materials. Furthermore, they can be utilized for determining properties of materials vibration with high frequency, granular materials, and polymers.First strain gradient theory introduced by... 

    Development a Computer Program for Burn-Up Calculation Using Monte-Carlo Method

    , M.Sc. Thesis Sharif University of Technology Khaki Arani, Mehdi (Author) ; Ghofrani, Mohammad Bagher (Supervisor) ; Feghhi, Amir Hossein (Supervisor)
    Burnup calculations based on the Monte Carlo method have been developed in line with the improvements in computing technology. Nowadays, in the field of nuclear reactor physics, it is possible to perform burnup calculation in a detailed 3D geometry and continuous energy description by the Monte Carlo method. COMB is a fully automated code in DELPHI 7 that links the MCNP4C Monte Carlo transport code with the radioactive decay and burnup calculation code system, ORIGEN2.1. The principal function of COMB is first to transfer one-group cross sections and fluxes from MCNP4C to ORIGEN2.1, and then transfer the resulting material compositions (after irradiation and/or decay) from ORIGEN2.1 back to... 

    Dose Simulation in Different Body Parts in Radiotherapy Using Fluka Monte Carlo Code on Human Phantom and Benchmarking with TL Dosimetry

    , M.Sc. Thesis Sharif University of Technology Montazam, Mahnaz (Author) ; Sohrabpour, Mostafa (Supervisor) ; Mahdavi, Rabi (Supervisor)
    Radiation therapy is a treatment modality that is used in treatment of most newly diagnosed cancer patients. In this method the interaction of radiation with matter and their biological effects is used for cancer treatment. The energy and intensity of the radiation in radiotherapy should be considered in order to have a lethal effect on tumors. Linear accelerators are substitutes for previous methods of radiotherapy in all over the world. These machines can work in both electron and photon mode. The Monte Carlo technique has become ubiquitous in medical physics in the last 50 years. The range of applications is very broad in medical physics. The increased use of Monte Carlo techniques is... 

    Kinetics and Mechanism of 4,4-Dicyano 5-Ethyl 1,5-Heptadiene Reaction in Gas and Solution Phase; Theoretical Approach

    , M.Sc. Thesis Sharif University of Technology Omidi, Masoume (Author) ; Gholami, Mohammad Reza (Supervisor) ; Sajjadi, Ali Akbar (Co-Advisor)
    Kinetics and mechanism of 4,4-dicyano-5-ethyl-1,5-heptadiene rearrangement reaction, a pericyclic type reaction, were studied with ab initio calculations in gas and solution phases. This reaction is one of the cope rearrangement in which secondary kinetic isotope effect is observed. Theoretical study on these reactions showed that probability of radicalic mechanism is inconsiderable and reaction proceeds through out a concerted mechanism with cyclic transition state. Isotope effect was studied by replacement of H1, H2 and H4,H5 with deuterium. The isotope effect data confirmed the concerted mechanism. Solvent effects on this reaction were studied by CPCM model. Solvation energies at... 

    Radiative Mass Correction in Supersymmetric Field Theories and its Implications for Supersymmetry Phenomenology

    , M.Sc. Thesis Sharif University of Technology Mohseni, Amineh (Author) ; Torabian, Mahdi (Supervisor)
    During years, supersymmetry has been a candidate for resolution of Higgs mass fine-tuning problem that is quadratic dependence of scalar mass radiative correction to UV-physics. So, supersymmetry phenomenology is of great importance. As accelerators have reached energy of 13 TeV in recent years and sparticles have not yet been observed, it is important to have a theory in hand, describing SUSY breaking dynamics with scale of SUSY breaking above the energies currently accessible to accelerators. As a result of mass-sum-rule constraint which holds in theories with spontaneous SUSY breaking at tree level and leads to light sparticles and even tachyonic directions, there are currently no... 

    Nucleoside Structure using Ab-Initio Computational Methods

    , M.Sc. Thesis Sharif University of Technology Chashmniam, Saeed (Author) ; Tafazzoli, Mohsen (Supervisor)
    The spin – spin coupling constants have been calculated by the Gaussian 2009 program in order to study the nucleosides conformation. To study the effect of solvent, the calculations were performed in four solvent including water, DMSO, chloroform and Carbon tetrachloride.
    Also, the comparison is done on two computing methods including DFT (B3LYP) and HF using 6-311++g** and 6-311g basis set.One bonding (1JC-H), two bonding (2JN-H, 2JC-H) and three bonging coupling constants (3JC-H) have been calculated for unpaired adenosine, thymidine and uridine molecules.Formation of intra-molecular hydrogen bond and electron pair repulsion, respectively, makes the compounds stable and unstable....