Search for: analytic-method
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    Bio-inspired nanostructured sensor for the detection of ultralow concentrations of explosives [electronic resource]

    , Article Journal of Angewandte Chemie International Edition ; 29 May 2012, Volume 51, Issue 22, P.5334-5338 Dourandish, M. (Mahdi) ; Simchi, A. (Abdolreza) ; Tamjid Shabestary, Elnaz ; Hartwig, Thomas ; Sharif University of Technology
    TNT: Silicon microcantilevers modified with a three-dimensional layer of vertical titanium dioxide nanotubes can be used in micromechanical sensors with optical signal detection to detect low levels of explosives such as 2,4,6-trinitrotoluene (TNT) in the gas phase, even in the presence of other volatile impurities such as n-heptane and ethanol  

    An analytical model for prediction of controlled release from bulk biodegrading polymer microspheres

    , Article Asian Journal of Pharmaceutical and Clinical Research ; Volume 11, Issue 3 , March , 2018 , Pages 432-437 ; 09742441 (ISSN) Sivandzade, F ; Sharif University of Technology
    Innovare Academics Sciences Pvt. Ltd  2018
    Objective: a convenient numerical model has been developed to predict release profile of different types of agents from bulk biodegrading polymer microspheres, including magnitude methods are less accurate than analytical methods. Usually, this study used analytical solutions for the model and compared the analytical results with numerical solution and experimental data. Methods: The objective drug controlled release profiles were modeled based on a four-phase pattern. Then, a specific formulation was considered based on Fick’s second law. After calculating various parameters, the equations were solved using an analytical method. Results: Comparison results showed that analytical solution... 

    Analytical and rigorous method for analysis of an array of magnetically-biased graphene ribbons

    , Article Optics Express ; Volume 27, Issue 20 , 2019 ; 10944087 (ISSN) Rahmanzadeh, M ; Rejaei, B ; Memarian, M ; Khavasi, A ; Sharif University of Technology
    OSA - The Optical Society  2019
    A sheet of graphene under magnetic bias attains anisotropic surface conductivity, opening the door for realizing compact devices such as Faraday rotators, isolators and circulators. In this paper, an accurate and analytical method is proposed for a periodic array of graphene ribbons under magnetic bias. The method is based on integral equations governing the induced surface currents on the coplanar array of graphene ribbons. For subwavelength size ribbons subjected to an incident plane wave, the current distribution is derived leading to analytical expressions for the reflection/transmission coefficients. The results obtained are in excellent agreement with full-wave simulations and predict... 

    An investigation into the structure and thermal properties of lead hydroxide

    , Article Scientia Iranica ; Volume 14, Issue 2 , 2007 , Pages 169-173 ; 10263098 (ISSN) Sajadi, S. A. A ; Alamolhoda, A. A ; Hashemian, S. J ; Sharif University of Technology
    Sharif University of Technology  2007
    The compound, lead hydroxide Pb6O4(OH)4, was prepared by a method used for the first time in the authors laboratory. The compound was identified by XRD and it's purity was determined by analytical methods (100%). The thermal characteristics of this compound were investigated by using a thermogravimetry (TGA). This compound was found to be stable at room temperature and at 160°C will decompose completely to produce lead (II) oxide. © Sharif University of Technology, April 2007  

    Finite element modelling of perturbed stellar systems

    , Article Monthly Notices of the Royal Astronomical Society ; Volume 404, Issue 3 , Jan , 2010 , Pages 1519-1528 ; 00358711 (ISSN) Jalali, M. A ; Sharif University of Technology
    I formulate a general finite element method (FEM) for self-gravitating stellar systems. I split the configuration space to finite elements, and express the potential and density functions over each element in terms of their nodal values and suitable interpolating functions. General expressions are then introduced for the Hamiltonian and phase-space distribution functions of the stars that visit a given element. Using the weighted residual form of Poisson's equation, I derive the Galerkin projection of the perturbed collisionless Boltzmann equation, and assemble the global evolutionary equations of nodal distribution functions. The FEM is highly adaptable to all kinds of potential and density... 

    Implementing an accurate generalized gaussian quadrature solution to find the elastic field in a homogeneous anisotropic media

    , Article Journal of the Serbian Society for Computational Mechanics ; Volume 11, Issue 1 , 2017 , Pages 11-19 ; 18206530 (ISSN) Kabir, H ; Matikolaei, S. A. H. H ; Sharif University of Technology
    In the current study, the elastic field in an anisotropic elastic media is determined by implementing a general semi-analytical method. In this specific methodology, the displacement field is computed as a sum of finite functions with unknown coefficients. These aforementioned functions exactly satisfy both the homogeneous and inhomogeneous boundary conditions in the proposed media. It is worth mentioning that the unknown coefficients are determined by implementing the principle of minimum potential energy. The numerical integration is done by employing the Generalized Gaussian Quadrature rule. Furthermore, and with the aid of the calculated unknown coefficients, the displacement fields as... 

    New biorthogonal potential-density basis functions

    , Article Monthly Notices of the Royal Astronomical Society ; Volume 393, Issue 4 , 2009 , Pages 1459-1466 ; 00358711 (ISSN) Rahmati, A ; Jalali, M. A ; Sharif University of Technology
    We use the weighted integral form of spherical Bessel functions and introduce a new analytical set of complete and biorthogonal potential-density basis functions. The potential and density functions of the new set have finite central values and they fall off, respectively, similar to r-(1+ l) and r-(4+ l) at large radii, where l is the latitudinal quantum number of spherical harmonics. The lowest order term associated with l = 0 is the perfect sphere of de Zeeuw. Our basis functions are intrinsically suitable for the modelling of three-dimensional, soft-centred stellar systems and they complement the basis sets of Clutton-Brock, Hernquist & Ostriker and Zhao. We test the performance of our... 

    Analysis of fluid flow in cylindrical microchannels subjected to uniform wall injection

    , Article 3rd ASME Integrated Nanosystems Conference - Design, Synthesis, and Applications, Pasadena, CA, 22 September 2004 through 24 September 2004 ; 2004 , Pages 139-146 ; 0791841774 (ISBN); 9780791841778 (ISBN) Layeghi, M ; ASME Nanotechnology Institute ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    Analytical analysis of fluid flow in cylindrical microchannels subjected to uniform wall injection at various Reynolds numbers is presented. The classical Navier-Stokes equations are used in the present study. Mathematically, using an appropriate change of variable, Navier-Stokes equations are transformed to a set of nonlinear ordinary differential equations. The governing equations are solved analytically using series solution method. The presented analytical results can be used for the prediction of velocity profiles and pressure drops in the cylindrical micro channels. The results are validated against available data in the literature and have shown good agreement. Copyright © 2004 by... 

    Design and evaluation of a TNA explosive-detection system to screen carry-on luggage

    , Article Journal of Radioanalytical and Nuclear Chemistry ; Volume 248, Issue 3 , 2001 , Pages 695-697 ; 02365731 (ISSN) Tavakkoli Farsoni, A ; Mireshghi, S. A ; Sharif University of Technology
    Thermal neutron analysis (TNA) technology has been used for the non-destructive detection of explosives. The system uses a relatively weak 252Cf neutron source (1.03.107 n/s) and two 3″3×″ NaI(Tl) detectors. The presence of explosives is confirmed via detection of the 10.83 MeV prompt gamma-ray associated with nitrogen decay. The MCNP4A code was used to simulate the neutron and gamma transport through the system. The thermal neutron flux in the activation position was measured using gold and indium foils. The measured thermal neutron flux was lower, by not more than 9.5%, than that of simulation. In this report the results of the preliminary tests on the system are described  

    Out-of-plane buckling of Y-braced frames with rigid joints

    , Article Proceedings of the Institution of Civil Engineers: Structures and Buildings ; Volume 166, Issue 1 , 2013 , Pages 28-37 ; 09650911 (ISSN) Zamani, M. S ; Vafai, A ; Kazemi, M.T ; Sharif University of Technology
    Because of the complicated buckling characteristics of Y-shaped bracings, calculation of their strength is beyond routine engineering procedures. A method based on slope-deflection equations incorporating stability functions has been used for computation of buckling eigenvalues and effective length factors. Lateral strength is computed based on the least buckling strength of bracing members. This study is limited to bracings with similar sections and fixed end connections resisting out-of-plane rotation. Lateral strengths predicted by the analytical method for two cases are compared with experimental results on full-scale specimens. It is shown that the proposed analytical method predicts... 

    A size-dependent exact theory for thermal buckling, free and forced vibration analysis of temperature dependent FG multilayer GPLRC composite nanostructures restring on elastic foundation

    , Article International Journal of Mechanics and Materials in Design ; Volume 15, Issue 3 , 2019 , Pages 569-583 ; 15691713 (ISSN) Safarpour, H ; Esmailpoor Hajilak, Z ; Habibi, M ; Sharif University of Technology
    Springer Netherlands  2019
    In this paper, thermal buckling and free/forced vibration characteristics of size-dependent composite cylindrical nanoshell reinforced with graphene platelets (GPLs) is presented. Also, the nanoshell is embedded in an elastic pasternak medium, which is obtained by adding a shear layer to the Winkler model. The present nano-resonator is based on a vibrating first order nanoscale cylindrical shell subjected to transverse pressure. The temperature-dependent material properties of piece-wise functionally graded graphene-reinforced composites (FG-GRCs) are assumed to be graded in the thickness direction of a cylindrical nanoshell and are estimated through a nanomechanical model. Also, Halpin–Tsai... 

    An Analytical Approach to Nonlinear Vibrations of a Three-Layered Sandwich Beam with a Viscoelastic Core, under the Effects of Internal Resonance, Employing MMS

    , M.Sc. Thesis Sharif University of Technology PashaJavid, Babak (Author) ; Haddadpour, Hassan (Supervisor)
    Vibrations with high amplitudes in continuous systems and models with multiple degrees of freedom, in specific conditions, is concomitant with a phenomenon called internal resonance. In the presence of this phenomenon, energy is transferred from one directly excited mode to the other vibrating modes of the structure results in response of the structure to be combination of the excited modes. In that situation occurrence of the internal resonance may decrease the level of undesired vibrations of the structure. This behavior is of interest especially in sandwich structures with viscoelastic cores that are designated to improve the damping characteristics of the structure and the property may... 

    Fabrication and Theoretical Investigation of a Single Bubble Nozzle-Diffuser Micropump

    , M.Sc. Thesis Sharif University of Technology Pirouzpanah, Sahand (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Saeedi, Mohammad Saeed (Supervisor)
    The potential of phase change process in liquids at microscale has been a favorite for the scientists to fabricate this type of micropumps. To hold unidirectional flow in microchannels usually nozzle-diffuser arrangement is used. Due to the existence of difference in pressure drop in the nozzle and diffuser sections, one can see unidirectional flow through diffuser direction. The objective of this article is to analyze analytically the thermo-hydrodynamic behavior of the Isopropyl Alcohol (IPA) bubble of a phase change micropump. Considering the simultaneous effects of hydrodynamic and thermal characteristics of the bubble in the bubble generation chamber, and temperature-saturation... 

    Analytical and learning-based spectrum sensing time optimisation in cognitive radio systems

    , Article IET Communications ; Volume 7, Issue 5 , 2013 , Pages 480-489 ; 17518628 (ISSN) Shokri Ghadikolaei, H ; Abdi, Y ; Nasiri Kenari, M ; Sharif University of Technology
    In this study, the average throughput maximisation of a secondary user (SU) by optimising its spectrum sensing time is formulated, assuming that a priori knowledge of the presence and absence probabilities of the primary users (PUs) is available. The energy consumed to find a transmission opportunity is evaluated, and a discussion on the impacts of the number of PUs on SU throughput and consumed energy are presented. To avoid the challenges associated with the analytical method, as a second solution, a systematic adaptive neural network-based sensing time optimisation approach is also proposed. The proposed scheme is able to find the optimum value of the channel sensing time without any... 

    Study of water entry of circular cylinder by using analytical and numerical solutions

    , Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 34, Issue 3 , July , 2012 , Pages 225-232 ; 16785878 (ISSN) Ghadimi, P ; Dashtimanesh, A ; Djeddi, S. R ; Sharif University of Technology
    Water impact phenomenon in the case of a circular cylinder is an important issue in offshore industry where cross members may be in the splash zone of the incident wave. An analytical method as well as a numerical solution are employed to study the water entry problem of a circular section. The procedure for derivation of the analytical formulas is demonstrated step by step. The volume of fluid (VOF) simulation of the water entry problem is also performed to offer comparison of the results of the linearized analytical solution with a fully nonlinear and viscous fluid flow solution. To achieve this, the FLOW- 3D code is utilized. Some consideration has also been given to the points of... 

    Estimation of damage induced by single-hole rock blasting: A review on analytical, numerical, and experimental solutions

    , Article Energies ; Volume 14, Issue 1 , 2021 ; 19961073 (ISSN) Shadabfar, M ; Gokdemir, C ; Zhou, M ; Kordestani, H ; Muho, E. V ; Sharif University of Technology
    MDPI AG  2021
    This paper presents a review of the existing models for the estimation of explosion-induced crushed and cracked zones. The control of these zones is of utmost importance in the rock explosion design, since it aims at optimizing the fragmentation and, as a result, minimizing the fine grain production and recovery cycle. Moreover, this optimization can reduce the damage beyond the set border and align the excavation plan with the geometric design. The models are categorized into three groups based on the approach, i.e., analytical, numerical, and experimental approaches, and for each group, the relevant studies are classified and presented in a comprehensive manner. More specifically, in the... 

    The Pr and oxygen correlation in the GdPr123 system

    , Article Modern Physics Letters B ; Volume 16, Issue 25 , 2002 , Pages 943-953 ; 02179849 (ISSN) Khosroabadi, H ; Daadmehr, V ; Akhavan, M ; Sharif University of Technology
    We prepared single-phase polycrystalline Gd1-xPrx Ba2Cu3O7-δ samples with x = 0, 0.10, 0.15, and 0.20. The deoxygenation process of these samples was performed by an annealing method. Electrical resistivity measurements revealed depression of the transition temperature with the increase of x and δ. We calculated the hole concentration in the CuO2 plane for different values of x and δ. A linear dependence of transition temperature and hole concentration in the CuO2 plane was found as a function of 2δ + x. It is proposed that a combination of the localization and filling of holes should be considered as the effective mechanisms for the appearance of the Pr anomaly in HTSCs  

    Exergy Analysis of Thermoacoustic Heat Pump with Industrial Application

    , Ph.D. Dissertation Sharif University of Technology Karimi, Mohsen (Author) ; Ghorbanian, Kaveh (Supervisor)
    Typical thermoacoustic systems deal with the conversion of heat energy to sound energy and vice versa. Recent advances in the field of thermoacoustics have altered the working mechanism of many conventional heating and cooling devices. These systems have three highlighted advantages: first, they have simple structure, no moving parts, low cost of manufacture, and high reliability; second, by using inert gases as working fluid, they are environmentally friendly; and finally, heat driven thermoacoustic devices can be driven by low quality energy sources such as waste heat and solar energy.
    The main focus of the present thesis is on the application of the thermoacoustic technology in the... 

    Solution of Coupled Thermoelasticity Problem in Rotating Disks with Constant and Variable Thickness

    , Ph.D. Dissertation Sharif University of Technology Entezari, Ayoob (Author) ; Kouchakzadeh, Mohammad Ali (Supervisor)
    The main purpose of this dissertation is to study thermoelastic behaviors in rotating disks subjected to thermal shock loads based on the generalized and classic theories of coupled thermoelasticity. To this end, this research has been carried out in two stages. In the first stage, thermoelasticity problems in an axisymmetric rotating disk with constant thickness made of a homogeneous isotropic material are analytically solved. In this stage, based on the classical and generalized coupled theories, and dynamic and quasi-static uncoupled theories, an analytical method based on the Fourier-Bessel transform is employed to obtain the thermoelastic solutions. Then, closed-form formulations are... 

    The Evolution of a Geometric Space in in the Nineteenth Century

    , M.Sc. Thesis Sharif University of Technology Karimi, Ehsan (Author) ; Shahshahani, Siavash (Supervisor)
    The meaning and the nature of space and it’s essential properties seems to be one of the oldest problems which has been continuing to occupy human’s mind during centuries. It can be counted as a common ground between philosophy, mathematics, physics and even art. However this thesis concentrates on the philosophical and mathematical attitudes, neglecting the other aspects of the issue. Prima facie, it appears that the concept of space is essentially mingled with geometry, the science which seems to investigate the essentials of space. Taking it for granted, Kant regarded space, and so Euclidean geometry which dominates it, as an indispensible and necessary structure of the human’s mind....