Search for: reduction
Total 1194 records
Article International Journal of Therapy and Rehabilitation ; Volume 14, Issue 2 , 2007 , Pages 63-69 ; 17411645 (ISSN) ; Karimi, H ; Farahmand, F ; Naghdi, S ; Faghihzadeh, S ; Sharif University of Technology
MA Healthcare Ltd 2007
The assessment of the various impairments in brain damage including spasticity is important. The purpose of this study was to develop a new biomechanical method based on quantification of velocity reduction (VR) suitable for clinical use
Influence of polyaniline synthesis conditions on its capability for removal and recovery of chromium from aqueous solution, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 3 , 2011 , Pages 97-100 ; 10219986 (ISSN) ; Borghei, S. M ; Olad, A ; Chaichi, M. J ; Sharif University of Technology
Absorptive characteristics of polyaniline synthesized in different solvents were studied. Water and mixture of water with other solvents were implemented for polyaniline synthesis. Synthesized polyanilines in powder shape is used as an adsorbent to remove toxic hexavalent chromium from aqueous solutions. Experiments were conducted in batch mode. Removal mechanism involving polyaniline is the combination of surface adsorption and reduction. The kind of solvent used at synthesizing stage can affect the capacity of produced polyanilines for removal of heavy metals including chromium. Synthesized polyaniline in water had the maximum chromium removal efficiency. The morphology study of...
Article Journal of Environmental Studies ; Volume 36, Issue 55 , 2010 , Pages 91-98 ; 10258620 (ISSN) ; Borghei, S. M ; Olad, A ; Chaichi, M. J ; Sharif University of Technology
Article Automatica ; Volume 37, Issue 11 , 2001 , Pages 1689-1702 ; 00051098 (ISSN) ; Karimi, A ; Constantinescu, A ; Sharif University of Technology
The paper addresses the problem of directly estimating the parameters of a reduced order digital controller using a closed loop type identification algorithm. The algorithm minimizes the closed loop plant input error between the nominal closed loop system and the closed loop system using the reduced order controller. It is assumed that a plant model (if necessary validated in closed loop with the nominal controller) is available. One of the original features of this approach is that it can use either simulated or real data. The frequency bias distribution of the parameter estimates shows that the reduced order controller maintains the critical performance of the nominal closed loop system. A...
Article Arabian Journal for Science and Engineering ; Volume 36, Issue 5 , 2011 , Pages 809-825 ; 13198025 (ISSN) ; Ehsan, M ; Sharif University of Technology
The characteristics of integrating distributed generation (DG) in a distribution network have changed. These electrical resources are used as an alternative energy source to the main grid. The technical and economical benefits of such units are achieved only when they are optimally sized and placed in the network. In this paper, a static mixed integer non-linear model for distributed generation planning is defined and solved using a modified NSGA method (Non-dominated Sorting Genetic Algorithm). Different DG technologies are considered and the objective functions for minimization are defined as the total active loss, investment and operational costs, and environmental pollution. The method...
Article International Journal of Modern Physics A ; Volume 33, Issue 22 , 2018 ; 0217751X (ISSN) ; Golshani, M ; Jafari, G ; Sharif University of Technology
In objective gravitational reduction of the wave function of a quantum system, the classical limit of the system is obtained in terms of the objective properties of the system. On the other hand, in Bohmian quantum mechanics the usual criterion for getting classical limit is the vanishing of the quantum potential or the quantum force of the system, which suffers from the lack of an objective description. In this regard, we investigated the usual criterion of getting the classical limit of a free particle in Bohmian quantum mechanics. Then we argued how it is possible to have an objective gravitational classical limit related to the Bohmian mechanical concepts like quantum potential or...
Article International Journal of Modern Physics A ; Volume 36, Issue 26 , 2021 ; 0217751X (ISSN) ; Golshani, M ; Sharif University of Technology
World Scientific 2021
In this study, we use the concept of Bohmian trajectories to present a dynamical and deterministic interpretation for the gravity-induced wave function reduction. We shall classify all possible regimes for the motion of a particle, based on the behavior of trajectories in the ensemble and under the influence of quantum and gravitational forces. In the usual approaches all the information is obtained from the wave function evolution. But, on the basis of Bohm's deterministic quantum theory, we can investigate the motion of the particle during the reduction processes. This leads to analytical and numerical results for the reduction time and equation of motion of the particle. In this regard, a...
Article Journal of Supercomputing ; Vol. 70, issue. 2 , 2014 , p. 845-879 ; Momtazpour, M ; Goudarzi, M ; Sharif University of Technology
Size and number of high-performance data centers are rapidly growing all around the world in recent years. The growth in the leakage power consumption of servers along with its exponential dependence on the ever increasing process variation in nanometer technologies has made it inevitable to move toward variation-aware power reduction strategies in data centers. In this paper, we address the problem of joint server placement and chassis consolidation to minimize power consumption of high-performance computing data centers under process variation. To this end, we introduce two variation-aware server placement heuristics as well as an integer linear programming (ILP)-based server placement...
Article Modelling and Simulation in Materials Science and Engineering ; Volume 15, Issue 5 , 2007 , Pages 487-507 ; 09650393 (ISSN) ; Saboohi, Y ; Sharif University of Technology
A mathematical model is developed to investigate the reduction process of hematite in the reduction zone of the Midrex shaft furnace as a moving bed reactor. It is described as a counter-current moving bed cylindrical reactor in which hematite pellets are reduced by a gaseous mixture of hydrogen, water vapour, carbon dioxide and carbon monoxide, namely Syngas. It is laterally injected into the bed at the lower part close to the bottom. Governing equations, including continuity, momentum, energy and mass equations, are derived based on the conceptual model for both gas and solid phases in the cylindrical coordinate system. A three interface unreacted shrinking core model (USCM) is applied to...
Comparison and reduction of the chemical kinetic mechanisms proposed for thermal partial oxidation of methane (TPOX) in porous media, Article International Journal of Hydrogen Energy ; Volume 46, Issue 37 , 2021 , Pages 19312-19322 ; 03603199 (ISSN) ; Rahimpour, M ; Sharif University of Technology
Elsevier Ltd 2021
The effectiveness and reducibility of the methane combustion kinetic mechanisms were examined for the TPOX process in a porous medium. To this end, TPOX was successfully simulated using ANSYS CHEMKIN-Pro through a reactor network model composed of perfectly stirred and honeycomb-monolith reactors. The efficacy of six chemical kinetic mechanisms was compared for the equivalence ratios (ERs) ranging from 2.4 to 2.6 with a constant thermal load of 1540 kW/m2. This comparison revealed that Konnov was the most successful mechanism in the prediction of the H2 and CO mole fractions. This mechanism along with the GRI-3.0 and USC-Mech 2.0 mechanisms were then reduced by the direct relation graph with...
M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad
Nd-Fe-B alloys as permanent magnets are used in the components of the computer, sensors, medical equipments and etc. Two main methods which used for making these alloys, are calciothermic reduction process and fused salt electrolysis technique. In this study, a new affordable process for producing Fe-Nd alloys have been suggested.In this research, aluminothermic reduction and co-reduction processes were used to make a Pb-Nd alloy from neodymium oxide (Nd2O3) and Lead Oxide (PbO). Then by using liquid-liquid extraction at high temperature, Fe-Nd alloy was produced. Experiments were performed at temperature of about 1600°C and in the air atmosphere. Different weight ratios were also tried. The...
Article Journal of polymer materials ; December 1994, Volume 11, Number 4; Page(s) 239 To 247 ; Pourjavadi, A ; Nadali, M ; Sharif University of Technology
This article reviews the oil-soluble polymeric drag-reducing agents (DRAs) with an outlook to their large-scale application in petroleum industry. A general discussion on mechanism of the DR phenomenon and mechanical degradation of the drag reducers in turbulent flow is offered with an emphasis on the molecular parameters. Furthermore, low charge density associating polymers, as a new class of oil-soluble flow improvers, are described
Article International Journal of Hydrogen Energy ; Volume 37, Issue 20 , October , 2012 , Pages 15423–15432 ; Ghasemi, S. (Shahnaz) ; Irajizada, A. (Azam) ; Akhavana, O. (Omid) ; Gholami, M. R. (Mohammad Reza) ; Sharif University of Technology
Reduced graphene oxide (RGO) was used to improve the hydrogen sensing properties of Pd and Pt-decorated TiO2 nanoparticles by facile production routes. The TiO2 nanoparticles were synthesized by sol–gel method and coupled on GO sheets via a photoreduction process. The Pd or Pt nanoparticles were decorated on the TiO2/RGO hybrid structures by chemical reduction. X-ray photoelectron spectroscopy demonstrated that GO reduction is done by the TiO2 nanoparticles and Ti–C bonds are formed between the TiO2 and the RGO sheets as well. Gas sensing was studied with different concentrations of hydrogen ranging from 100 to 10,000 ppm at various temperatures. High sensitivity (92%) and fast response time...
Rapid, efficient and selective reduction of aromatic nitro compounds with hydrazine hydrate in the presence of the plain and supported platinum nanoparticles as catalysts, Article Journal of the Iranian Chemical Society ; Vol. 11, issue. 6 , 2014 , pp. 1587-1592 ; ISSN: 1735207X ; Ahmadi, S. J ; Sadjadi, S ; Outokesh, M ; Sharif University of Technology
The current study aimed at application of the plain and supported platinum nanoparticles as a heterogenous catalyst for the reduction of aromatic nitro compounds. Monodispersed platinum nanoparticles were synthesized by reduction of H2PtCl6 by ethanol in the presence of polyvinyl pyrrolidone as a stabilizer, and then were immobilized on four types of zeolites. The obtained catalyst granules were characterized by X-ray diffractometry and transmission electron microscopy. The study then focused on elaboration of the catalytic activity of the nano catalysts under different operational conditions. It was found that reaction is adequately rapid at ambient temperature, and by utilizing a...
Extended rank reduction formulas containing Wedderburn and Abaffy-Broyden-Spedicato rank reducing processes, Article Linear Algebra and Its Applications ; Volume 439, Issue 11 , 2013 , Pages 3318-3331 ; 00243795 (ISSN) ; Golpar Raboky, E ; Sharif University of Technology
The Wedderburn rank reduction formula and the Abaffy-Broyden-Spedicato (ABS) algorithms are powerful methods for developing matrix factorizations and many fundamental numerical linear algebra processes such as Gram-Schmidt, conjugate direction and Lanczos methods. We present a rank reduction formula for transforming the rows and columns of A, extending the Wedderburn rank reduction formula and the ABS approach. By repeatedly applying the formula to reduce the rank, an extended rank reducing process is derived. The biconjugation process associated with the Wedderburn rank reduction process and the scaled extended ABS class of algorithms are shown to be in our proposed rank reducing process,...
Article International Review on Modelling and Simulations ; Volume 5, Issue 3 , June , 2012 , Pages 1322-1326 ; 19749821 (ISSN) ; Masoumzadeh Tork, A ; Yazdan Talab, E ; Ramezanpour, H ; Darmani, G ; Sharif University of Technology
In recent years, several techniques based on repetition of the image are used to remove noise. In this paper a new method based on Cellular Automata for image noise removal in mammography images is recommended. We present a new formulation that makes improvements. The formulation uses a neighborhood with sizes and format adapted to the features of the image on reconstruction. We demonstrated through experiments and comparison with other common used techniques that this procedure produces excellent results for the problem of restoring true color images
Electrodeposited Rh and Rh-Cu Alloys as Ethanol-Tolerant Electrocatalysts for Oxygen Reduction in Alkaline Media, Article Electrocatalysis ; Volume 2, Issue 1 , December , 2011 , Pages 42-51 ; 18682529 (ISSN) ; Arab, R ; Sharif University of Technology
In this study, rhodium-copper alloys of different compositions are electrodeposited on graphite electrode from aqueous solutions. The bulk compositions of these alloys are determined using energy dispersive X-ray analysis and surface morphologies are investigated by scanning electron microscopy. The catalytic performance of these alloys in oxygen reduction reaction (ORR) in alkaline media is investigated by linear sweep voltammetry on rotating disk electrode assembly. The number of electrons transferred per O 2 molecule (n) obtained at different potentials is four indicating full reduction of oxygen to hydroxide ion. It is shown that Rh-Cu alloys are better electrocatalysts than Rh with...
Aluminothermic-carbothermal reduction synthesis of nano crystalline Al2O3-Ti(C,N) composite with different bed types, Article Iranian Journal of Materials Science and Engineering ; Volume 12, Issue 1 , 2015 , Pages 66-75 ; 17350808 (ISSN) ; Naghizadeh, R ; Samadi, H ; Nemati, A ; Sharif University of Technology
Iran University of Science and Technology 2015
Ceramic-matrix composites containing TiC-TiN have been used in a variety of application because of their superior properties such as high hardness, good wear resistance and high chemical stability. In this research, effect of coke and coke/calcium beds in synthesis of Al2O3-Ti(C, N) composites using alumino-carbothermic reduction ofTiO2 has been investigated. Al, TiO2 and active carbon with additives of extra carbon and NaCl and without additives, in separate procedures, have been mixed. Afterwards, mixtures were pressed and synthesized in 1200°C for 4hrs, in coke and coke/calcium beds, separately. Al2O3-Ti(C,N) composite was synthesized in ternary system of Al-TiO2-C with excess carbon and...
Behavior of three non-coking coals from Iranian's deposits in simulated thermal regime of tunnel kiln direct reduction of iron, Article Journal of Analytical and Applied Pyrolysis ; 2016 ; 01652370 (ISSN) ; Askari, M ; Fabritius, T ; Sharif University of Technology
Elsevier B.V 2016
The behavior of three types of non-coking coals from Iranian's deposits in thermal regime of tunnel kiln direct reduction of the iron (TKDRI) process has been investigated. The heating condition of raw materials in tunnel kiln was simulated in a vertical TGA for three different non-coking coals. For non-isothermal devolatilization of coals from room temperature to 1100. C, the heating rates of 1.5, 3 and 7. C/min were chosen. Coal mass and volumetric changes during devolatilization were observed by TGA and dilatometry analysis. XRD and scanning electron microscopy of raw coals and chars were used to analyze coal structural changes. In non-isothermal low heating rate pyrolysis of coal, most...
Effect of CO2-laser irradiation on properties and performance of thin-film composite polyamide reverse osmosis membrane, Article Korean Journal of Chemical Engineering ; Volume 33, Issue 3 , 2016 , Pages 1028-1036 ; 02561115 (ISSN) ; Mousavi, S. A ; Farhadi, F ; Vatanpour, V ; Sabzi, B ; Chenari, Z ; Sharif University of Technology
Springer New York LLC 2016
CO2-laser irradiation was used to modify the surface properties of thin-film composite (TFC) polyamide reverse osmosis (RO) membranes. These membranes were first synthesized via interfacial polymerization of m-phenylenediamine (MPD) monomers and trimesoyl chloride (TMC) over porous polysulfone ultrafiltration support, followed by a CO2-irradiation. AFM, ATR-FTIR, SEM and contact angle measurements were used to characterize the surface properties of these membranes. The ATR-FTIR results indicated that CO2-laser irradiation did not induce any functional groups on the membrane surface. However, it was found that the laser irradiation enhanced the NaCl salt rejection and slightly reduced the...