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    A new approach to study the Zeno effect for a macroscopic quantum system under frequent interactions with a harmonic environment

    , Article Scientific Reports ; Volume 9, Issue 1 , 2019 ; 20452322 (ISSN) Ghasemi, F ; Shafiee, A ; Sharif University of Technology
    Nature Publishing Group  2019
    Quantum Zeno and anti-Zeno behaviors of a two-level macroscopic quantum system in interaction with a harmonic environment are studied using the perturbation theory. The system-environment interactions are applied in a successive and step-by-step way. A new expression for the probability of surviving the macrosystem in its initial state, after the Nth interaction step, is derived through a different method of calculation. It is shown that multiple transitions between Zeno and anti-Zeno behaviors can be found in our approach. We have shown that in addition to the environmental parameters like the Ohmicity, the macroscopic trait of the system also has a notable effect on the decay rate Γ(τ).... 

    Minimal continuous model identification via Markov parameter estimation

    , Article 6th European Control Conference, ECC 2001, 4 September 2001 through 7 September 2001 ; 2001 , Pages 1858-1863 ; 9783952417362 (ISBN) Isapour, A ; Sadati, N ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2001
    In this paper, an attractive and novel algorithm for improving irreducible model identification of continuous time(CT) MIMO systems has been presented. The algorithm is based on least - squares (LS) estimates of Markov parameters (MP) using input output data and residual whitening. By choosing a linear-in-parameters model structure, the estimation becomes linear and asymptotically robust to zero-mean additive disturbances. CT Markov parameters may result in diverging approximations even for stable systems. To remove the existing limitations in the case of systems with low or zero damping, Markov Poisson parameters have been used to lend much flexibility to the estimation model. The MIMO... 

    Improvement of the photovoltaic parameters of perovskite solar cells using a reduced-graphene-oxide-modified titania layer and soluble copper phthalocyanine as a hole transporter

    , Article Physical Chemistry Chemical Physics ; Volume 20, Issue 4 , 2018 , Pages 2388-2395 ; 14639076 (ISSN) Nouri, E ; Mohammadi, M. R ; Xu, Z. X ; Dracopoulos, V ; Lianos, P ; Sharif University of Technology
    Royal Society of Chemistry  2018
    Functional perovskite solar cells can be made by using a simple, inexpensive and stable soluble tetra-n-butyl-substituted copper phthalocyanine (CuBuPc) as a hole transporter. In the present study, TiO2/reduced graphene oxide (T/RGO) hybrids were synthesized via an in situ solvothermal process and used as electron acceptor/transport mediators in mesoscopic perovskite solar cells based on soluble CuBuPc as a hole transporter and on graphene oxide (GO) as a buffer layer. The impact of the RGO content on the optoelectronic properties of T/RGO hybrids and on the solar cell performance was studied, suggesting improved electron transport characteristics and photovoltaic parameters. An enhanced... 

    Adaptive synchronization of two different chaotic systems with time varying unknown parameters

    , Article Chaos, Solitons and Fractals ; Volume 37, Issue 1 , 2008 , Pages 125-136 ; 09600779 (ISSN) Salarieh, H ; Shahrokhi, M ; Sharif University of Technology
    In this paper a nonlinear control method based on Lyapunov stability theorem is proposed to design an adaptive controller for synchronizing two different chaotic systems. It is assumed that the unknown parameters of the drive and the response chaotic systems are time varying. It is shown that the proposed scheme can identify the system parameters if the system parameters are time invariant and the richness conditions is satisfied. To demonstrate the effectiveness of the proposed technique it has been applied to Lorenz-Chen dynamic systems, as drive-response systems. Simulation results indicate that the proposed adaptive controller has a high performance in synchronizing two chaotic systems.... 

    The effect of machining parameters on force signal and tool wear in stone cutting

    , Article AIP Conference Proceedings, 24 October 2010 through 27 October 2010, Paris ; Volume 1315 , 2010 , Pages 961-966 ; 0094243X (ISSN) ; 9780735408715 (ISBN) Yousefi, R ; Gorjizadeh, A ; Mikaeil, R ; Sharif University of Technology
    The application of sensor system is becoming more commonplace in improving productivity and reliability. Although measuring force signal have been widely used for monitoring of metal machining process that their application to stone cutting has not been well investigated. In this paper, the effect of machining parameter on force signal and tool wear was investigated. The result indicate that increasing of the depth of cut and spindle speed will increase the force and tool wear while increasing feed rate will increase force and decrease tool wear  

    Multiple target parameter estimation in multi-frequency array radar

    , Article International Review of Electrical Engineering ; Volume 5, Issue 6 , Nov/Dec , 2010 , Pages 2692-2709 ; 18276660 (ISSN) Sebt, M. A ; Nayebi, M. M ; Amindavar, H. R ; Sharif University of Technology
    Since space diversity and frequency diversity are both efficient techniques in the radar applications, we propose in this paper a method for simultaneous usage of both techniques. On this basis, multi-frequency array radar in which all frequencies are used simultaneously to increase the number of targets that can be uniquely identified, is introduced and analyzed. First, the signal model for such a system is derived and then, it is shown how the use of multi-frequency signal can noticeably improve the parameter identifiability. Specifically, we show the maximum number of targets that can be uniquely identified by the multi-frequency array radar is L times that of its single-frequency array... 

    Systematic renormalization of the effective theory of Large Scale Structure

    , Article Journal of Cosmology and Astroparticle Physics ; Volume 2016, Issue 5 , 2016 ; 14757516 (ISSN) Abolhasani, A. A ; Mirbabayi, M ; Pajer, E ; Sharif University of Technology
    Institute of Physics Publishing  2016
    A perturbative description of Large Scale Structure is a cornerstone of our understanding of the observed distribution of matter in the universe. Renormalization is an essential and defining step to make this description physical and predictive. Here we introduce a systematic renormalization procedure, which neatly associates counterterms to the UV-sensitive diagrams order by order, as it is commonly done in quantum field theory. As a concrete example, we renormalize the one-loop power spectrum and bispectrum of both density and velocity. In addition, we present a series of results that are valid to all orders in perturbation theory. First, we show that while systematic renormalization... 

    The study on microbial polymers: Pullulan and PHB

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 28, Issue 1 , 2009 , Pages 13-21 ; 10219986 (ISSN) Iran, A ; Sharif University of Technology
    Microbial cells are producers of natural polymers present in plant cells. Production of pullulan (an extracellular microbial polysaccharide) by Aureobasidium pullularia pullulans (P. pullulans) was studied under fermentation conditions, and kinetic parameters were determined. Pullulan formation obeyed a growth and non-growth associated term. PHB (polyhydroxybutyrates) an intracellular biopolymer production by Rastonia eutropha (Alcaligen eutrophus), R. eutropha was studied under different culture media, including synthetic and natural carbon sources. Molasses as a natural carbon source in the culture media presented high efficiency in cell and biopolymer accumulation  

    Solvatochromic parameters for binary mixtures of an ionic liquid with various protic molecular solvents

    , Article Monatshefte fur Chemie ; Volume 140, Issue 3 , 2009 , Pages 329-334 ; 00269247 (ISSN) Khodadadi Moghaddam, M ; Habibi Yangjeh, A ; Gholami, M. R ; Sharif University of Technology
    Solvatochromic parameters (E T N , normalized polarity parameter; π, dipolarity/polarizability; β, hydrogen-bond acceptor basicity; α, hydrogen-bond donor acidity) have been determined for binary mixtures of propan-2-ol, propan-1-ol, ethanol, methanol and water with recently synthesized ionic liquid (IL; 2-hydroxyethylammonium formate) at 25 °C. In all solutions except aqueous solution, E T N values of the media increase abruptly with the ILs mole fraction and then increase gradually to the value of pure IL. A synergistic behavior is observed for the α parameter in all solutions. The behavior of π and β are nearly ideal for all solutions except for solutions of methanol with the IL. The... 

    Transit timing variations in the WASP-4 planetary system

    , Article Monthly Notices of the Royal Astronomical Society ; Volume 490, Issue 3 , 2019 , Pages 4230-4236 ; 00358711 (ISSN) Southworth, J ; Dominik, M ; Jorgensen, U. G ; Andersen, M. I ; Bozza, V ; Burgdorf, M. J ; D'Ago, G ; Dib, S ; Figuera Jaimes, R ; Fujii, Y. I ; Gill, S ; Haikala, L. K ; Hinse, T. C ; Hundertmark, M ; Khalouei, E ; Korhonen, H ; Longa-Pena, P ; Mancini, L ; Peixinho, N ; Rabus, M ; Rahvar, S ; Sajadian, S ; Skottfelt, J ; Snodgrass, C ; Spyratos, P ; Tregloan Reed, J ; Unda Sanzana, E ; Von Essen, C ; Sharif University of Technology
    Oxford University Press  2019
    Transits in the planetary system WASP-4 were recently found to occur 80 s earlier than expected in observations from the TESS satellite. We present 22 new times of mid-transit that confirm the existence of transit timing variations, and are well fitted by a quadratic ephemeris with period decay dP/dt = −9.2 ± 1.1 ms yr−1. We rule out instrumental issues, stellar activity, and the Applegate mechanism as possible causes. The light-time effect is also not favoured due to the non-detection of changes in the systemic velocity. Orbital decay and apsidal precession are plausible but unproven. WASP-4 b is only the third hot Jupiter known to show transit timing variations to high confidence. We... 

    Pull-in parameters of cantilever type nanomechanical switches in presence of Casimir force

    , Article Nonlinear Analysis: Hybrid Systems ; Volume 1, Issue 3 , 2007 , Pages 364-382 ; 1751570X (ISSN) Ramezani, A ; Alasty, A ; Akbari, J ; Sharif University of Technology
    In this paper, the effect of the Casimir force on pull-in parameters of cantilever type nanomechanical switches is investigated by using a distributed parameter model. In modeling of the electrostatic force, the fringing field effect is taken into account. The model is nonlinear due to the inherent nonlinearity of the Casimir and electrostatic forces. The nonlinear differential equation of the model is transformed into the integral form by using the Green's function of the cantilever beam. The integral equation is solved analytically by assuming an appropriate shape function for the beam deflection. The pull-in parameters of the switch are computed in three cases including nanoactuators... 

    H∞ control of a flexible transmission system

    , Article Proceedings of the Thirty-Sixth Southeastern Symposium on System Theory (SSST04), Atlanta, GA., 14 March 2004 through 16 March 2004 ; Volume 36 , 2004 , Pages 536-540 Amirifar, R ; Sadati, N ; Sharif University of Technology
    An application of a continuous-time H∞ control to a flexible transmission system is presented. This approach has been proposed in order to assure high control performance in the presence of large load variation on the system. In this approach, the loading variations are considered as the multiplicative perturbation of the nominal plant. The desired specifications are enforced in the H∞ problem as the constraints on weighting functions. After an initial design procedure, the parameters of weighting functions, in order to obtain the desired performances, are tuned and then the final weighting functions are derived. The simulation results for three different loadings are given and compared  

    Application of an optimization algorithm for estimating intrinsic kinetic parameters of immobilized enzymes

    , Article Journal of Bioscience and Bioengineering ; Volume 94, Issue 1 , 2002 , Pages 1-7 ; 13891723 (ISSN) Khorasheh, F ; Kheirolomoom, A ; Mireshghi, S ; Sharif University of Technology
    Society of Fermentation and Bioengineering  2002
    A simple optimization methodology is applied to estimate the intrinsic kinetic parameters for both reversible and irreversible unireactant immobilized enzyme systems that follow the Michaelis-Menten mechanism. The method utilizes a direct-search optimization algorithm along with the numerical solution of the governing differential equations. The usefulness and validity of the method is demonstrated by comparing the predicted values of the intrinsic kinetic constants using the proposed method with a series of experimental values reported in the literature for different immobilized enzyme systems with irreversible and reversible reactions  

    Comparing the stability regions for fractional-order PI controllers and their integer-order approximations

    , Article Proceedings of the IEEE Conference on Decision and Control, 15 December 2010 through 17 December 2010, Atlanta, GA ; 2010 , Pages 720-725 ; 01912216 (ISSN) ; 9781424477456 (ISBN) Rahimian, M. A ; Tavazoei, M. S ; Sharif University of Technology
    This paper proposes a scheme for computing the stable regions from which the parameters of a fractional-order PI controller can be selected. In particular, we extend a previously investigated method for plotting the stability regions of PIλ controllers to their integer-order approximations. Next we compare the two stability regions and derive their overlapping sections, which is referred to as the implementable stability region. In order for the final closed-loop system to be stable, the designer must choose the controller parameters from the overlapping section of the two stability regions. The devised scheme we believe can facilitate the design procedure for fractional-order PI... 

    Physical properties of the planetary systems WASP-45 and WASP-46 from simultaneous multiband photometry

    , Article Monthly Notices of the Royal Astronomical Society ; Volume 456, Issue 1 , 2016 , Pages 990-1002 ; 00358711 (ISSN) Ciceri, S ; Mancini, L ; Southworth, J ; Lendl, M ; Tregloan Reed, J ; Brahm, R ; Chen, G ; D'Ago, G ; Dominik, M ; Figuera Jaimes, R ; Galianni, P ; Harpsøe, K ; Hinse, T. C ; Jørgensen, U. G ; Juncher, D ; Korhonen, H ; Liebig, C ; Rabus, M ; Bonomo, A. S ; Bott, K ; Henning, T ; Jordán, A ; Sozzetti, A ; Alsubai, K. A ; Andersen, J. M ; Bajek, D ; Bozza, V ; Bramich, D. M ; Browne, P ; Calchi Novati, S ; Damerdji, Y ; Diehl, C ; Elyiv, A ; Giannini, E ; Gu, S. H ; Hundertmark, M ; Kains, N ; Penny, M ; Popovas, A ; Rahvar, S ; Scarpetta, G ; Schmidt, R. W ; Skottfelt, J ; Snodgrass, C ; Surdej, J ; Vilela, C ; Wang, X. B ; Wertz, O ; Sharif University of Technology
    Oxford University Press  2016
    Accurate measurements of the physical characteristics of a large number of exoplanets are useful to strongly constrain theoretical models of planet formation and evolution, which lead to the large variety of exoplanets and planetary-system configurations that have been observed. We present a study of the planetary systemsWASP-45 andWASP-46, both composed of a mainsequence star and a close-in hot Jupiter, based on 29 new high-quality light curves of transits events. In particular, one transit of WASP-45 b and four of WASP-46 b were simultaneously observed in four optical filters, while one transit of WASP-46 b was observed with the NTT obtaining a precision of 0.30 mmag with a cadence of... 

    Simulation of welding residual stresses in resistance spot welding, FE modeling and X-ray verification

    , Article Journal of Materials Processing Technology ; Volume 205, Issue 1-3 , 26 August , 2008 , Pages 60-69 ; 09240136 (ISSN) Ranjbar Nodeh, I ; Serajzadeh, S ; Kokabi, A. H ; Sharif University of Technology
    In the present study, an electro-thermo-mechanical model is utilized to predict electrical potential, temperature and residual stress distributions during different stages of resistance spot welding. In order to improve accuracy, material properties including physical, thermal and mechanical properties supposed to be temperature-dependent. The employed model is capable of considering the effects of welding parameters such as heat input and welding time on residual stress distribution. The model results are then compared with the measured residual stresses and good agreement is observed. Predictions show that maximum tensile residual stresses are located at the weld center while they are... 

    Optimization of caustic current efficiency in a zero-gap advanced chlor-alkali cell with application of genetic algorithm assisted by artificial neural networks

    , Article Chemical Engineering Journal ; Volume 140, Issue 1-3 , 2008 , Pages 157-164 ; 13858947 (ISSN) Mirzazadeh, T ; Mohammadi, F ; Soltanieh, M ; Joudaki, E ; Sharif University of Technology
    The effects of various process parameters on caustic current efficiency (CCE) in a zero-gap oxygen-depolarized chlor-alkali cell employing a state-of-the-art silver plated nickel screen electrode (ESNS®) were studied. For doing a thorough research, we selected the process parameters from both cathodic and anodic compartments. Seven process parameters were studied including anolyte pH, temperature, flow rate and brine concentration from the anode side, oxygen temperature and flow rate from the cathode side and the applied current density. The effect of these parameters on CCE was determined quantitatively. A feed forward neural network model with the Levenberg-Marquardt (LM) back propagation... 

    Application of neural network to find initial state of optimization parameters

    , Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 10716947 (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) Babakhani, A. R ; Sayyaadi, H ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2006
    This paper derives an estimated function made by simple Neural Network to find initial state of optimization parameters. It changes a system of differential equations with boundary values to a system of equations with initial values. So a lot of time would be saved to solve it. As a result, the system with differential equations will reach the desired final state. Copyright © 2006 by ASME  

    Encoding the information in relative parameters

    , Article Physics Letters, Section A: General, Atomic and Solid State Physics ; Volume 407 , 2021 ; 03759601 (ISSN) Rezazadeh, F ; Mani, A ; Sharif University of Technology
    Elsevier B.V  2021
    We investigate the problem of communicating three parameters in the absence of shared reference frame. We explore two methods in which the relative angles of spins are used to encode the parameters. In the first method we use three spins that carry the information in their relative angles while in the second method we use three disjoint spin-pairs and the information is sent through the relative angles of each individual pair. We show that in the first method, the information conveyed by each qubit is more than the second one, and that is while it requires fewer particles. © 2021 Elsevier B.V  

    Dual-parameter correlations on rate of dehydration step of a condensation reaction in aqueous solutions of ethanol, propan-2-ol and 2-methylpropan-2-ol

    , Article Journal of Physical Organic Chemistry ; Volume 14, Issue 12 , 2001 , Pages 884-889 ; 08943230 (ISSN) Habibi Yangjeh, A ; Gholami, M. R ; Mostaghim, R ; Sharif University of Technology
    The reaction kinetics of the dehydration step of the condensation reaction between phenylhydrazine and benzaldehyde was studied spectrophotometrically in aqueous solutions of ethanol, propan-2-ol and 2-methylpropan-2-ol at pH 11.5 at 25 °C. The apparent second-order rate constants k2app of the reaction increase with mole fraction of water in all the aqueous solutions. Single-parameter correlations of log k2app versus π* (dipolarity/polarizability), α (hydrogen-bond donor acidity) and ETN (normalized polarity parameter) were obtained in all the aqueous solutions. In all cases, the correlations versus ETN and π* are acceptable, but correlations versus α are poor (e.g. in aqueous solutions of...