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Thermodynamic analysis of a hybrid gas turbine/thermoacoustic heat pump/refrigeration engine
, Article International Journal of Exergy ; Volume 15, Issue 2 , 1 November , 2014 , Pages 152-170 ; ISSN: 17428297 ; Karimi, M ; Sharif University of Technology
Abstract
Possible performance enhancement of small gas turbine power plants through the application of thermoacoustic systems is examined. The thermoacoustic subsystem is powered only by the waste heat of the gas turbine. Two different gas turbine configurations are considered: a Thermoacoustic refrigerator assisted gas turbine (TRG) and a Combined thermoacoustic heat pump and refrigeration assisted gas turbine (CTHRG). Exergy, rational efficiency and relative power gain (RPG) of these configurations are compared with those from the recuperated gas turbine engine. The results indicate that the integration of thermoacoustic system to a simple gas turbine cycle will not only enhance the energy/exergy...
Design and optimization of a heat driven thermoacoustic refrigerator
, Article Applied Thermal Engineering ; Volume 62, Issue 2 , 25 January 2014 , Pages 653–661 ; Karimi, M ; Sharif University of Technology
Abstract
The present paper deals with the design and optimization of a heat driven thermoacoustic refrigerator. A simplified model is developed which enables to pinpoint and examine the most important physical characteristics of a compact traveling wave thermoacoustic refrigerator driven by a traveling wave thermoacoustic engine. The model can explain the so-called traveling standing wave effect in thermoacoustics very well. The position, length and hydraulic radius of the refrigerator are optimized for the maximum total COP. The prime mover efficiency, refrigerator COP and dimensionless dissipation and their impacts on total COP are investigated and discussed. The results indicate that a COP of...
Design and optimization of a heat driven thermoacoustic refrigerator
, Article Applied Thermal Engineering ; Volume 61, Issue 2 , 2013 , Pages 653-661 ; 13594311 (ISSN) ; Karimi, M ; Sharif University of Technology
2013
Abstract
The present paper deals with the design and optimization of a heat driven thermoacoustic refrigerator. A simplified model is developed which enables to pinpoint and examine the most important physical characteristics of a compact traveling wave thermoacoustic refrigerator driven by a traveling wave thermoacoustic engine. The model can explain the so-called traveling standing wave effect in thermoacoustics very well. The position, length and hydraulic radius of the refrigerator are optimized for the maximum total COP. The prime mover efficiency, refrigerator COP and dimensionless dissipation and their impacts on total COP are investigated and discussed. The results indicate that a COP of...
Evaluation of the geo-mechanical parameters of the interface between asphalt concrete and sand with applying direct shear test and numerical modeling
, Article Advanced Materials Research ; Volume 587 , 2012 , Pages 116-121 ; 10226680 (ISSN) ; 9783037855133 (ISBN) ; Rostami, A ; Karimi, M. M ; Taherkhani, H
2012
Abstract
Asphaltic concrete has been used as waterproofing core in embankment dams, since 1948. In this application, the asphaltic core is surrounded by granular filter materials. The interaction of the asphaltic concrete and the granular materials has not been sufficiently investigated. In this paper the mechanical behavior of the interface between a natural smooth sand filter and asphaltic concrete at different levels of normal stresses and a constant shear strain rate has been studied. Small scale direct shear test has been conducted in this study, in which the shear surface is considered as the interface. Asphalt concrete specimens used in the shear test were cut in square shape (10×10×2.5 cm)...
Chemically modified organic/inorganic nanoporous composite particles for the adsorption of reactive black 5 from aqueous solution
, Article Reactive and Functional Polymers ; Volume 86 , 2015 , Pages 7-15 ; 13815148 (ISSN) ; Shojaei, A ; Karimi, M ; Sharif University of Technology
Elsevier
2015
Abstract
In the present work, we report a chemically modified polyacrylamide/silica nanoporous composite adsorbent for the removal of reactive black 5 (RB5) azo dye from aqueous solutions. The composite adsorbent was synthesized in a packed bed and modified by ethylenediamine (EDA). The adsorbent was characterized by Fourier transformation infrared (FT-IR), thermogravimetric analysis (TGA), thermoporometry, Brunauer, Emmett and Teller (BET) method and scanning electron microscopy (SEM). Mechanical stability of the adsorbent was examined in a packed bed by following the back-pressure of the column. Pore diameter of the composite adsorbent in dry and wet states was estimated to be about 18.71 nm and...
Exergy analysis of an integrated gas turbine thermoacoustic engine
, Article ASME 2010 4th International Conference on Energy Sustainability, ES 2010, 17 May 2010 through 22 May 2010, Phoenix, AZ ; Volume 1 , 2010 , Pages 945-951 ; 9780791843949 (ISBN) ; Karimi, M ; Sharif University of Technology
2010
Abstract
An attempt is made to utilize exhaust gases of a small gas turbine in augmenting power output through the employment of a thermoacoustic system. It is assumed that the thermoacoustic system is powered only by the waste heat of the gas turbine. A comprehensive cycle analysis of the integrated gas turbine thermoacoustic engine "IGTTE" is carried out from energy and exergy point of view. Results indicate the thermodynamic advantages of the IGTTE
Determination of hydrocarbon-water interfacial tension using a new empirical correlation
, Article Fluid Phase Equilibria ; Volume 415 , 2016 , Pages 42-50 ; 03783812 (ISSN) ; Daryasafar, A ; Karimi, M ; Sharif University of Technology
Elsevier
2016
Abstract
Interfacial tension is one of the very important parameters in pharmacology science, chemical engineering and petroleum engineering. The interfacial tension between pure hydrocarbons and water is widely used in chemical and petroleum engineering and so that it is highly desirable to find its accurate values. In this study a new unique correlation has been developed based on a comprehensive database of pure hydrocarbons-water interfacial tension values which contained both aliphatic and aromatic compounds (32 different hydrocarbons) with pressure ranges of 0.1-300 MPa and temperature ranges of 252.44-550 K. The proposed correlation uses the density difference between pure hydrocarbon and...
Multihypothesis compressed video sensing technique
, Article IEEE Transactions on Circuits and Systems for Video Technology ; Volume 26, Issue 4 , 2016 , Pages 627-635 ; 10518215 (ISSN) ; Karimi, M ; Marvasti, F ; Sharif University of Technology
Abstract
In this paper, we present a compressive sampling and multihypothesis (MH) reconstruction strategy for video sequences that has a rather simple encoder, while the decoding system is not that complex. We introduce a convex cost function that incorporates the MH technique with the sparsity constraint and the Tikhonov regularization. Consequently, we derive a new iterative algorithm based on these criteria. This algorithm surpasses its counterparts (Elasticnet and Tikhonov) in recovery performance. Besides, it is computationally much faster than Elasticnet and comparable with Tikhonov. Our extensive simulation results confirm these claims
Non-linear analysis of functionally graded sector plates with simply supported radial edges under transverse loading
, Article Mechanics of Advanced Composite Structures ; Volume 6, Issue 1 , 2019 , Pages 65-74 ; 24234826 (ISSN) ; Karimi, M. H ; Sharif University of Technology
Semnan University, Faculty of Mechanical Engineering
2019
Abstract
In this study, nonlinear bending of functionally graded (FG) circular sector plates with simply supported radial edges subjected to transverse mechanical loading has been investigated. Based on the first-order shear deformation plate theory with von Karman strain-displacement relations, the nonlinear equilibrium equations of sector plates are obtained. Introducing a stress function and a potential function, the governing equations which are five non-linear coupled equations with total order of ten are reformulated into three uncoupled ones including one linear edge-zone equation and two nonlinear interior equations with total order of ten. The uncoupling makes it possible to present...
On the relationship between entropy and information
, Article Physics Essays ; Volume 20, Issue 3 , 2007 , Pages 487-493 ; 08361398 (ISSN) ; Karimi, M ; Sharif University of Technology
2007
Abstract
In this paper we analyze the relationship between entropy and information in the context of the mixing process of two identical ideal gases. We will argue that entropy has a special information-based feature that is enfolded in the statistical entropy, but the second law does not include it directly. Therefore, in some given processes in thermodynamics where there is no matter and energy interaction between the system and the environment, the state of the system may go toward a situation of lower probability to increase the observer's information about the environment. This is a kind of information-based interaction in which the total entropy is not constrained by the second law
Effect of thermal treatment on fracture behavior of solder joints at various strain rates: Comparison of cyclic and constant temperature
, Article Engineering Failure Analysis ; Volume 128 , 2021 ; 13506307 (ISSN) ; Nourani, A ; Karimi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Fracture tests on Sn93Pb37 solder joints in a double cantilever beam (DCB) configuration were performed at two different strain rates of 10−5 and 0.03 s−1 under mode I loading conditions. In each case, the critical strain energy release rate for crack initiation, Jci, was obtained. Effects of storing specimens at a constant temperature of 75 °C and cyclic temperature varying between 32 and 75 °C were examined at these strain rates. In the strain rate of 0.03 s−1, storing samples in a constant or cyclic temperature caused the fracture energy to decrease significantly with respect to the specimens maintained in ambient temperature. The significant reduction in fracture energy by placing the...
Effect of environmental conditions on fracture behavior of solder joints
, Article Theoretical and Applied Fracture Mechanics ; Volume 112 , 2021 ; 01678442 (ISSN) ; Nourani, A ; Karimi, M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Double cantilever beam (DCB) specimens were prepared according to standard surface mount technology (SMT). The samples were stored inside an environmental chamber at two different relative humidity values (i.e. 40 or 100%) for either 2 or 4 h. Then they were aged at 25 °C, 75 °C or 125℃ for the same time. Finally, after being cooled to room temperature, fracture tests were performed under mode-I loading conditions at a strain rate of 0.03 s−1 at room temperature. Storage time did not have a significant effect on the fracture behavior. The fracture load and energy of the solder joints decreased significantly when the temperature was increased from 25 to 75℃. By further increase in the...
Carbon-paste electrode modified with cobalt-5-nitrolsalophen as a sensitive voltammetric sensor for detection of captopril
, Article Sensors and Actuators, B: Chemical ; Volume 109, Issue 2 , 2005 , Pages 278-284 ; 09254005 (ISSN) ; Karimi, M ; Khajehsharifi, H ; Sharif University of Technology
2005
Abstract
The electrochemical behavior of captopril at the surface of a carbon-paste electrode (CPE) modified with cobalt-5-nitrolsalophen (CoNSal) is described. The prepared electrode shows an excellent electrocatalytic activity toward the oxidation of captopril, which is leading to marked lowering in the anodic overpotential and considerable improvement of sensitivity (anodic current). Whereas at the surface of unmodified electrode an electrochemical activity for captopril cannot be observed, a very sharp anodic wave with an anodic peak potential about 650 mV (versus Ag/AgCl) is obtained using the prepared modified electrode. This catalytic wave is assigned to mediating of Co(III)/Co(II) redox...
Voltammetric studies of a cobalt(II)-4-methylsalophen modified carbon-paste electrode and its application for the simultaneous determination of cysteine and ascorbic acid
, Article Electrochimica Acta ; Volume 50, Issue 1 , 2004 , Pages 77-84 ; 00134686 (ISSN) ; Karimi, M ; Sharif University of Technology
2004
Abstract
A carbon-paste electrode (CPE) chemically modified with the cobalt(II)-4-methylsalophen (CoMSal) as a Schiff base complex was used as a highly sensitive and fairly selective electrochemical sensor for simultaneous, determination of minor mounts of ascorbic acid (AA) and cysteine. This modified electrode shows very efficient electrocatalytic activity for anodic oxidation of both AA and cysteine via substantially decreasing of anodic overpotentials for both compounds. The. mechanism of electrochemical oxidation of both AA and cysteine using CoMSal-modified electrode was thoroughly investigated by cyclic voltammetry and polarization studies. Results of cyclic voltammetry (CV) and differential...
Simulating of X-states and the two-qubit XYZ Heisenberg system on IBM quantum computer
, Article Physica Scripta ; Volume 97, Issue 2 , 2022 ; 00318949 (ISSN) ; Karimi, M ; Karimipour, V ; Sharif University of Technology
IOP Publishing Ltd
2022
Abstract
Two qubit density matrices which are of X-shape, are a natural generalization of Bell Diagonal States (BDSs) recently simulated on the IBM quantum device. We generalize the previous results and propose a quantum circuit for simulation of a general two qubit X-state, implement it on the same quantum device, and study its entanglement for several values of the extended parameter space. We also show that their X-shape is approximately robust against noisy quantum gates. To further physically motivate this study, we invoke the two-spin Heisenberg XYZ system and show that for a wide class of initial states, it leads to dynamical density matrices which are X-states. Due to the symmetries of this...
Three-dimensional nonlinear seismic analysis of concrete faced rockfill dams subjected to scattered P, SV, and SH waves considering the dam-foundation interaction effects
, Article Soil Dynamics and Earthquake Engineering ; Volume 31, Issue 5-6 , 2011 , Pages 792-804 ; 02677261 (ISSN) ; Mohsen Haeri, S ; Karimi, M ; Sharif University of Technology
2011
Abstract
In this study, the nonlinear seismic analysis of a typical three-dimensional concrete faced rockfill dam is reported. Three components of the Loma Prieta (Gilroy 1 station) earthquake acceleration time history are used as input excitation. The dam under study is considered as if it were located in a prismatic canyon with a trapezoidal cross-section. A nonlinear model for the rockfill material is used, and contact elements with Coulomb friction law are utilized at the slab-rockfill interface. Vertical joints in the face slab are also considered in the finite element model. A substructure method, in which the unbounded soil is modelled by the scaled boundary finite element method (SBFEM), is...
A sensitive colorimetric detection of ascorbic acid in pharmaceutical products based on formation of anisotropic silver nanoparticles
, Article Scientia Iranica ; Volume 17, Issue 2 F , 2010 , Pages 148-153 ; 10263098 (ISSN) ; Karimi, M. A ; Shahheydari, F ; Sharif University of Technology
2010
Abstract
A sensitive colorimetric method for the detection of ascorbic acid was proposed in this research based on the reduction of silver ions by ascorbic acid in the presence of citrate-stabilized silver seeds, additional trisodium citrate and a polymer such as polyvinylpyrrolidone. The color of the stable sol is controlled by varying the concentration of trisodium citrate (TSC), polyvinylpyrrolidone, silver nitrate and silver seeds. The reduction of Ag + to triangle silver nanoparticles (Ag-NPs) by ascorbic acid in the presence of trisodium citrate (TSC) and silver seeds produced two very intense surface plasmon resonance peaks of Ag-NPs. The plasmon absorbance of Ag-NPs allows the quantitative...
A numerical analysis of thermal conductivity, thermal dispersion, and structural effects in the injection part of the resin transfer molding process
, Article Journal of Porous Media ; Volume 13, Issue 4 , 2010 , Pages 375-385 ; 1091028X (ISSN) ; Karimi, M ; Seyf, H. R ; Sharif University of Technology
2010
Abstract
Thermal conductivity, thermal dispersion, and structural effects in resin transfer molding (RTM) process are studied numerically. The injection part of the RTM process is modeled as a transport of resin flow through a fibrous porous medium in a long rectangular channel. The fluid flow is modeled using the Darcy-Brinkman-Forchheimer model and the heat transfer process using the energy equation based on local thermal equilibrium assumption. Both isotropic and anisotropic heat transfer in porous media are investigated. The governing equations are solved numerically for the isotropic heat transfer case and analytically for the anisotropic case. The numerical results are fitted to the available...
Microstructure-based visco-elastoplastic continuum model of asphalt concrete
, Article RILEM Bookseries ; Volume 11 , 2016 , Pages 37-48 ; 22110844 (ISSN) ; Karimi, M. M ; Tabatabaee, N ; Sharif University of Technology
Kluwer Academic Publishers
2016
Abstract
Asphalt concrete is a heterogeneous and multi-phase material that consists of aggregates, asphalt binder, and pores. These components create a complex microstructure. There is no consensus on how to quantify the microstructure and the required parameters from two-dimensional images. The load transfer can be managed by aggregate-aggregate or aggregate-mastic interactions that depend on the gradation, aggregate internal structure, and asphalt binder viscoelastic properties. The most important internal structure indices affecting the behavior of HMA are aggregate orientation, contact orientation, contact length, and number of contact points. In this paper, the influence of aggregate structure...
Experimental and numerical investigation of low-temperature performance of modified asphalt binders and mixtures
, Article Road Materials and Pavement Design ; 2016 , Pages 1-22 ; 14680629 (ISSN) ; Karimi, M. M ; Tabatabaee, N ; Sharif University of Technology
Taylor and Francis Ltd
2016
Abstract
Thermal cracking is the prevalent type of distress experienced by asphalt pavements in cold regions. It is widely assumed that when thermal stresses induced in the pavement exceed the tensile strength of the asphalt surface layer, cracking occurs; however, the role of thermal fatigue should not be ignored. To better describe the low-temperature (LT) performance properties of modified asphalt binders, a new parameter, normalised tensile stress (NTS), was defined in this research. NTS values were compared with bending beam rheometer (BBR), direct tension (DT) and semi-circular bending (SCB) fracture test results. The m-value parameter of the BBR test specifies the type of asphalt binder. This...