Loading...
Search for:
component
0.01 seconds
Total 1231 records
Resolution and quantification of complex mixtures of polycyclic aromatic hydrocarbons in heavy fuel oil sample by means of GC × GC-TOFMS combined to multivariate curve resolution
, Article Analytical Chemistry ; Volume 83, Issue 24 , 2011 , Pages 9289-9297 ; 00032700 (ISSN) ; Radović, J. R ; Jalali-Heravi, M ; Diez, S ; Bayona, J. M ; Tauler, R ; Sharif University of Technology
Abstract
Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) combined to multivariate curve resolution-alternating least-squares (MCR-ALS) is proposed for the resolution and quantification of very complex mixtures of compounds such as polycyclic aromatic hydrocarbons (PAHs) in heavy fuel oil (HFO). Different GC × GC-TOFMS data slices acquired during the analysis of HFO samples and PAH standards were simultaneously analyzed using the MCR-ALS method to resolve the pure component elution profiles in the two chromatographic dimensions as well as their pure mass spectra. Outstandingly, retention time shifts within and between GC × GC runs were not affecting...
Experimental investigation of constant and concentration-dependent diffusivity of a hydrocarbon solvents-heavy oil system: A comparative study
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 34, Issue 3 , 2011 , Pages 235-245 ; 15567036 (ISSN) ; Kharrat, R ; Ghazanfari, M. H ; Rashtchian, D ; Sharif University of Technology
Abstract
This work is concerned with the experimental investigation of mass transfer, which occurs during diffusion of hydrocarbon solvents in heavy oil based on constant and concentration-dependent diffusion coefficient. Here, a series of free fall diffusion experiments have been conducted in sealed test tubes at fixed temperatures. Pentane, hexane, and octane were used as solvents and were placed on heavy oil in tubes. The diffusivity of heavy oil into solvents was monitored by a digital camera. The image analysis technique was applied to extract concentration profiles in diffusion zones of solvents by means of calibration curves. Fick's second law was used to obtain both constant and...
Analytical approach to dynamic and vibration analysis of a spherical ball under contact stress
, Article Scientia Iranica ; Volume 18, Issue 6 , 2011 , Pages 1306-1312 ; 10263098 (ISSN) ; Hosseinzadeh, A ; Foumani, M. S ; Sharif University of Technology
2011
Abstract
This paper presents a nonlinear model to illustrate the effect of contact stress in the vibration behavior of mechanical components, especially rotating systems. The problem is considered in the case of the vertical vibration of a sphere on a plate. The Hertzian contact theory is used to obtain the relationship between contact force and the deflection of the mass center of the sphere. Modeling the system by a mass and a nonlinear spring, the vibration equation of the mass center of the sphere is derived. The method of LindstedtPoincar is implemented to solve the equation of motion, and obtain vibration characteristics under a compressive preload. The dependency of frequency on several...
Nonlinear vibration analysis of nano to micron scale beams under electric force using nonlocal theory
, Article Proceedings of the ASME Design Engineering Technical Conference, 28 August 2011 through 31 August 2011 ; Volume 7 , August , 2011 , Pages 145-151 ; 9780791854846 (ISBN) ; Vaghasloo, Y. A ; Ahmadian, M. T ; Moheimani, R ; Sharif University of Technology
2011
Abstract
Electrostatically actuated beams are fundamental blocks of many different nano and micro electromechanical devices. Accurate design of these devices strongly relies on recognition of static and dynamic behavior and response of mechanical components. Taking into account the effect of internal forces between material particles nonlocal theories become highly important. In this paper nonlinear vibration of a microano doubly clamped and cantilever beam under electric force is investigated using nonlocal continuum mechanics theory. Implementing differential form of nonlocal constitutive equation the nonlinear partial differential equation of motion is reformulated. The equation of motion is...
Investigation of the pressure distribution and transition point over a swept wing
, Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1277-1286 ; 10263098 (ISSN) ; Ghorbanian, K ; Masdari, M ; Sharif University of Technology
2011
Abstract
A series of wind tunnel tests are performed to examine the flow field over a swept wing under various conditions. The wing has a laminar flow airfoil section, similar to those of the NACA 6-series. Static pressure distributions over the upper surface of the wing, in both chordwise and spanwise directions, are measured at different angles of attack. The data is employed to predict the transition point at each chordwise section. The skewness parameter of the pressure data shows that this factor drops to zero in the transition region. A comparison of the calculated transition point on the wing surface with that obtained from the 2D computational method shows reasonable agreement over a portion...
Numerical simulation of thermal barrier coating system under thermo-mechanical loadings
, Article Proceedings of the World Congress on Engineering 2011, WCE 2011, 6 July 2011 through 8 July 2011 ; Volume 3 , July , 2011 , Pages 1959-1964 ; 9789881925152 (ISBN) ; Azadi, M ; Farrahi, G. H ; Sharif University of Technology
2011
Abstract
In the present paper, numerical simulation of thermal barrier coating system under thermo-mechanical loadings is performed, using the finite element method in ABAQUS software. The base material is Aluminum-silicon alloy, A356.0 which is widely used in automotive components such as diesel engine cylinder heads. Thermal barrier coatings (TBCs) are applied to combustion chamber in order to reduce fuel consumption and pollutions and also improve fatigue life of components. The roughness effect of coating layers on stress distribution of test specimens is investigated. Semi-ellipsoid roughness of the interfaces between substrate/bond coat and bond coat/top coat are simulated to get the stress...
A new multi-sample EOS model for the gas condensate phase behavior analysis
, Article Oil and Gas Science and Technology ; Volume 66, Issue 6 , September , 2011 , Pages 1025-1033 ; 12944475 (ISSN) ; Crespo, F ; Sharif University of Technology
2011
Abstract
Equations of State EOS are vastly being used to predict the phase behavior of reservoir fluids. The accuracy of EOS modeling technique over conventional correlation models would benefit an improved property prediction of these fluids. Once the crude oil or gas condensate fluid system has been probably characterized using limited laboratory tests, its PVT behavior under a variety of conditions can be easily studied. In this paper, the PVT behavior of gas condensate from a reservoir in South Pars retrograde gas field in Iran was modeled using the three-parameter Patel and Teja Equation of State. The multi-sample characterization method is used to arrive at one consistent model for retrograde...
Roller compacted concrete pavements reinforced with steel and polypropylene fibers
, Article Structural Engineering and Mechanics ; Volume 40, Issue 2 , 2011 , Pages 149-165 ; 12254568 (ISSN) ; Azizkhani, R ; Torki, M. E ; Sharif University of Technology
2011
Abstract
In this paper, the effects of both pozzolans and (steel and poly-propylene) fibers on the mechanical properties of roller compacted concrete are studied. Specimens for the experiments were made using a soil-based approach; thus, the Kango's vibration hammer was used for compaction. The tests in the first stage were carried out to determine the optimal moisture requirements for mix designs using cubic 150 × 150 × 150 mm specimens. In the tests of the second stage, the mechanical behaviors of the main specimens made using the optimal moisture obtained in the previous stage were evaluated using 28, 90, and 210 day cubic specimens. The mechanical properties of RCC pavements were evaluated using...
Carbon-Pt nanoparticles modified TiO 2 nanotubes for simultaneous detection of dopamine and uric acid
, Article Journal of Nanoscience and Nanotechnology ; Volume 11, Issue 8 , 2011 , Pages 6668-6675 ; 15334880 (ISSN) ; Luo, S ; Yang, L ; Mahshid, S. S ; Askari, M ; Dolati, A ; Cai, Q ; Sharif University of Technology
Abstract
The present work describes sensing application of modified TiO 2 nanotubes having carbon-Pt nanoparticles for simultaneous detection of dopamine and uric acid. The TiO 2 nanotubes electrode was prepared using anodizing method, followed by electrodeposition of Pt nanoparticles onto the tubes. Carbon was deposited by decomposition of polyethylene glycol in a tube furnace to improve the conductivity. The C-Pt-TiO 2 nanotubes modified electrode was characterized by cyclic voltam-metry and differential pulse voltammetry methods. The modified electrode displayed high sensitivity towards the oxidation of dopamine and uric acid in a phosphate buffer solution (pH 7.00). The electro-oxidation currents...
Nonlinear free vibration and post-buckling analysis of functionally graded beams on nonlinear elastic foundation
, Article European Journal of Mechanics, A/Solids ; Volume 30, Issue 4 , July , 2011 , Pages 571-583 ; 09977538 (ISSN) ; Aghdam, M. M ; Sharif University of Technology
2011
Abstract
In this study, simple analytical expressions are presented for large amplitude free vibration and post-buckling analysis of functionally graded beams rest on nonlinear elastic foundation subjected to axial force. Euler-Bernoulli assumptions together with Von Karman's strain-displacement relation are employed to derive the governing partial differential equation of motion. Furthermore, the elastic foundation contains shearing layer and cubic nonlinearity. He's variational method is employed to obtain the approximate closed form solution of the nonlinear governing equation. Comparison between results of the present work and those available in literature shows the accuracy of this method. Some...
Early detection of immunization: A study based on an animal model using 1H nuclear magnetic resonance spectroscopy
, Article Pakistan Journal of Biological Sciences ; Volume 14, Issue 3 , 2011 , Pages 195-203 ; 10288880 (ISSN) ; Arjmand, M ; Tafazzoli, M ; Ghohzadeh, A ; Pourfallah, F ; Sadeghi, S ; Mirzazadeh, R ; Mirkham, F ; Tahen, S ; Iravam, A ; Bayat, P ; Vahabi, F ; Sharif University of Technology
2011
Abstract
Vaccines require a period of at least three months for clinical trials, hence a method that can identify elicitation of immune response a few days after the first dose is a necessity. Evolutionary variable selections are modeling approaches for proper manipulation of available data which were used to set up an animal model for classification of time dependent 'HNMR metabolomic profiles and pattern recognition of fluctuations of metabolites in two groups of male rabbits. One group of rabbits was immunized with human red blood cells and the other used as control. Blood was obtained every 48 h from each rabbit for a period of six weeks and the serum monitored for antibodies and metabolites by...
Analysis of Iranian rosemary essential oil: Application of gas chromatography-mass spectrometry combined with chemometrics
, Article Journal of Chromatography A ; Volume 1218, Issue 18 , May , 2011 , Pages 2569-2576 ; 00219673 (ISSN) ; Moazeni, R. S ; Sereshti, H ; Sharif University of Technology
Abstract
This paper focuses on characterization of the components of Iranian rosemary essential oil using gas chromatography-mass spectrometry (GC-MS). Multivariate curve resolution (MCR) approach was used to overcome the problem of background, baseline offset and overlapping/embedded peaks in GC-MS. The analysis of GC-MS data revealed that sixty eight components exist in the rosemary essential oil. However, with the help of MCR this number was extended to ninety nine components with concentrations higher than 0.01%, which accounts for 98.23% of the total relative content of the rosemary essential oil. The most important constituents of the Iranian rosemary are 1,8-cineole (23.47%), α-pinene...
Production planning and performance optimization of reconfigurable manufacturing systems using genetic algorithm
, Article International Journal of Advanced Manufacturing Technology ; Volume 54, Issue 1-4 , 2011 , Pages 373-392 ; 02683768 (ISSN) ; Houshmand, M ; Sharif University of Technology
Abstract
To stay competitive in the new dynamic market having large fluctuations in product demand, manufacturing companies must use systems that not only produce their goods with high productivity but also allow for rapid response to market changes. Reconfigurable manufacturing system (RMS) is a new paradigm that enables manufacturing systems to respond quickly and cost effectively to market demand. In other words, RMS is a system designed from the outset, for rapid changes in both hardware and software components, in order to quickly adjust its production capacity to fluctuations in market demand and adapt its functionality to new products. The effectiveness of an RMS depends on implementing its...
Dynamic analysis of an inclined Timoshenko beam traveled by successive moving masses/forces with inclusion of geometric nonlinearities
, Article Acta Mechanica ; Volume 218, Issue 1-2 , 2011 , Pages 9-29 ; 00015970 (ISSN) ; Kargarnovin, M. H ; Sharif University of Technology
2011
Abstract
In the first part of this paper, the nonlinear coupled governing partial differential equations of vibrations by including the bending rotation of cross section, longitudinal and transverse displacements of an inclined pinned-pinned Timoshenko beam made of linear, homogenous and isotropic material with a constant cross section and finite length subjected to a traveling mass/force with constant velocity are derived. To do this, the energy method (Hamilton's principle) based on the large deflection theory in conjuncture with the von-Karman strain-displacement relations is used. These equations are solved using the Galerkin's approach via numerical integration methods to obtain dynamic...
Antepartum fetal heart rate feature extraction and classification using empirical mode decomposition and support vector machine
, Article BioMedical Engineering Online ; Volume 10 , 2011 ; 1475925X (ISSN) ; MA, M. A ; Zahedi, E ; Ahmed, S ; Hassan, F. M ; Sharif University of Technology
Abstract
Background: Cardiotocography (CTG) is the most widely used tool for fetal surveillance. The visual analysis of fetal heart rate (FHR) traces largely depends on the expertise and experience of the clinician involved. Several approaches have been proposed for the effective interpretation of FHR. In this paper, a new approach for FHR feature extraction based on empirical mode decomposition (EMD) is proposed, which was used along with support vector machine (SVM) for the classification of FHR recordings as 'normal' or 'at risk'.Methods: The FHR were recorded from 15 subjects at a sampling rate of 4 Hz and a dataset consisting of 90 randomly selected records of 20 minutes duration was formed from...
Large amplitudes free vibrations and post-buckling analysis of unsymmetrically laminated composite beams on nonlinear elastic foundation
, Article Applied Mathematical Modelling ; Volume 35, Issue 1 , 2011 , Pages 130-138 ; 0307904X (ISSN) ; Jafari Talookolaei, R. A ; Salarieh, H ; Sharif University of Technology
Abstract
The purpose of this paper is to present efficient and accurate analytical expressions for large amplitude free vibration and post-buckling analysis of unsymmetrically laminated composite beams on elastic foundation. Geometric nonlinearity is considered using Von Karman's strain-displacement relations. Besides, the elastic foundation has cubic nonlinearity with shearing layer. The nonlinear governing equation is solved by employing the variational iteration method (VIM). This study shows that the third-order approximation of the VIM leads to highly accurate solutions which are valid for a wide range of vibration amplitudes. The effects of different parameters on the ratio of nonlinear to...
In situ forming interpenetrating hydrogels of hyaluronic acid hybridized with iron oxide nanoparticles
, Article Biomaterials Science ; Volume 3, Issue 11 , Aug , 2015 , Pages 1466-1474 ; 20474830 (ISSN) ; Shi, L ; Bagheri, R ; Kabiri, K ; Hilborn, J ; Ossipov, D. A ; Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
Four derivatives of hyaluronic acid (HA) bearing thiol (HA-SH), hydrazide (HA-hy), 2-dithiopyridyl (HA-SSPy), and aldehyde groups (HA-al) respectively were synthesized. Thiol and 2-dithiopyridyl as well as hydrazide and aldehyde make up two chemically orthogonal pairs of chemo-selective functionalities that allow in situ formation of interpenetrating (IPN) disulfide and hydrazone networks simultaneously upon the mixing of the above derivatives at once. The formation of IPN was demonstrated by comparing it with the formulations of the same total HA concentration but lacking one of the reactive components. The hydrogel composed of all four components was characterized by a larger elastic...
Experimental and numerical simulation of the microcrack coalescence mechanism in rock-like materials
, Article Strength of Materials ; Volume 47, Issue 5 , September , 2015 , Pages 740-754 ; 00392316 (ISSN) ; Khaloo, A ; Marji, M. F ; Sharif University of Technology
Springer New York LLC
2015
Abstract
Rocks and rock-like materials frequently fail under compression due to the initiation, propagation and coalescence of the pre-existing microcracks. The mechanism of microcrack coalescence process in rock-like materials is experimentally and numerically investigated. The experimental study involves some uniaxial compression tests on rock-like specimens specially prepared from portland pozzolana cement, mica sheets and water. The microcrack coalescence is studied by scanning electron microscopy on some of the prepared thin specimens. It is assumed that the mica sheets play the role of microcracks within the specimens. Some analytical and numerical studies are also carried out to simulate the...
Artificial neural network assisted kinetic spectrophotometric technique for simultaneous determination of paracetamol and p-aminophenol in pharmaceutical samples using localized surface plasmon resonance band of silver nanoparticles
, Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 138 , March , 2015 , Pages 474-480 ; 13861425 (ISSN) ; Dadfarnia, S ; Haji Shabani, A. M ; Rohani Moghadam, M ; Hormozi Nezhad, M. R ; Sharif University of Technology
Elsevier
2015
Abstract
Spectrophotometric analysis method based on the combination of the principal component analysis (PCA) with the feed-forward neural network (FFNN) and the radial basis function network (RBFN) was proposed for the simultaneous determination of paracetamol (PAC) and p-aminophenol (PAP). This technique relies on the difference between the kinetic rates of the reactions between analytes and silver nitrate as the oxidizing agent in the presence of polyvinylpyrrolidone (PVP) which is the stabilizer. The reactions are monitored at the analytical wavelength of 420 nm of the localized surface plasmon resonance (LSPR) band of the formed silver nanoparticles (Ag-NPs). Under the optimized conditions, the...
Critical mass flow rate through capillary tubes
, Article American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM, 1 August 2010 through 5 August 2010 ; Volume 1, Issue PARTS A, B AND C , 2010 , Pages 51-56 ; 08888116 (ISSN) ; 9780791849484 (ISBN) ; Javidmand, P ; Fluids Engineering Division ; Sharif University of Technology
Abstract
This paper presented a numerical study that predicts critical mass flow rate, pressure, vapor quality, and void fraction along a very long tube with small diameter or capillary tub under critical condition by the drift flux model. Capillary tubes are simple expansion devices and are necessary to design and optimization of refrigeration systems. Using dimensional analysis by Buckingham's π theory, some generalized correlations are proposed for prediction of flow parameters as functions of flow properties and tube sizes under various critical conditions. This study is performed under the inlet pressure in the range of 0.8 ≤ pin ≤ 1.5Mpa, subcooling temperature between 0 ≤ ΔTsub ≤10 °C. The...