Search for: loading-rate
Molecular dynamics investigation of β-SiC behavior under three-axial tensile loading [electronic resource], Article Journal of Computational and Theoretical Nanoscience ; November 2011, Volume 8, Number 11, PP. 2187-2192 ; Simchi, A. (Abdolreza) ; Besharati-Givi, M.K ; Rajabpour, A ; Sharif University of Technology
Molecular dynamics (MD) simulations were used to study the mechanical behaviour of β-SiC at nano-scale under tensile loading. Effects of loading rate and tensile temperature on the mechanical properties and failure were studied. Modified embedded-atom method (MEAM) potential and Berendsen thermostat were utilized for modelling. Periodic boundary conditions were employed and the behaviour of material was analyzed under three-axial loading condition at which the stress–strain relation was acceptably size independent. It is shown that with increasing the loading rate from 5 m/s to 70 m/s, the failure strain increases without a remarkable change in the stress–strain relationship. The MD...
Nitrogen removal from high organic loading wastewater in modified Ludzack-Ettinger configuration MBBR system, Article Water Science and Technology ; Volume 72, Issue 8 , October , 2015 , Pages 1274-1282 ; 02731223 (ISSN) ; Borghei, S. M ; Tahmasebian, S ; Andalibi, M. R ; Sharif University of Technology
IWA Publishing 2015
A moving bed biofilm reactor with pre-denitrification configuration was fed with a synthetic wastewater containing high chemical oxygen demand (COD) and ammonia. By changing different variables including ammonium and COD loading, nitrification rate in the aerobic reactor and denitrification rate in the anoxic reactor were monitored. Changing the influent loading was achieved via adjusting the inlet COD (956-2,096 mg/L), inlet ammonium (183-438 mg/L), and hydraulic retention time of the aerobic reactor (8, 12, and 18 hours). The overall organic loading rate was in the range of 3.60-17.37 gCOD/m2·day, of which 18.5-91% was removed in the anoxic reactor depending on the operational conditions....
Article Chemical Engineering Transactions ; Volume 24 , 2011 , Pages 1291-1296 ; 19749791 (ISSN) ; Shayegan, J ; Sharif University of Technology
Italian Association of Chemical Engineering - AIDIC 2011
Fruit and vegetable wastes are produced in large quantities in Iran, and constitute a source of nuisance in municipal landfills. The objective of this study was to optimize the applications of anaerobic digestion for the treatment of municipal organic wastes. We studied the effect of organic loading rates on anaerobic digestion of vegetable wastes. The complete-mix, pilot-scale digester with working volume of 70 1 was used. The experiments were conducted at 34°C with a fixed hydraulic retention time of 25 days. The digester was operated at different organic feeding rates of 1.4, 2 and 2.75 kg VS/(m3.d). The biogas produced had methane composition of 49.7- 64% and biogas production rates of...
Article Journal of Applied Polymer Science ; Volume 125, Issue 3 , January , 2012 , Pages 2476-2483 ; 00218995 (ISSN) ; Kouchakzadeh, M. A ; Bagheri, R ; Sharif University of Technology
Effect of loading rate on toughness characteristics of hybrid rubber-modified epoxy was investigated. Epoxy was modified by amine-terminated butadiene acrylonitrile (ATBN) and recycled tire. Samples were tested at various loading rates of 1-1000 mm/min. Fracture toughness measurements revealed synergistic toughening in hybrid system at low loading rates (1-10 mm/min); hybrid system exhibited higher fracture toughness value in comparison with the ATBN-modified resin with same modifier content. However, synergistic toughening was eliminated by increasing the loading rate. At higher loading rates (10-1000), the fracture toughness of hybrid system decreased gradually to the level lower than that...
Article Chemical Engineering Transactions ; Volume 24 , 2011 , Pages 1285-1290 ; 19749791 (ISSN) ; Shayegan, J ; Sharif University of Technology
This study was carried out for examination of a lab-scale UASB reactor for optimization of organic loading rate and hydraulic retention time. The total volume of the reactor was 5 1 with an effective height of 160 cm and diameter of 5 cm. This reactor was used to treat fortified municipal wastewater at volumetric organic loadings of 3.6, 7.2, 10.8, and 14.4 kg m3 d 1 at temperature 30°C. The result of present work indicated an optimum range for organic loading (7.2 to 10.8 kg m-3 d-1) with COD removal efficiency of about 85%. Moreover, optimum HRT for influent COD concentration of 1200mg/l is shown to be only 4 hours. Furthermore nitrate removal efficiency was about 80% at optimized organic...
Article Journal of Macromolecular Science, Part B: Physics ; Volume 49, Issue 3 , 2010 , Pages 602-614 ; 00222348 (ISSN) ; Khademi, V ; Bagheri, R ; Motamedi, P ; Kouchakzadeh, M. A ; Haddadpour, H ; Sharif University of Technology
The effect of loading rate on toughening mechanisms of rubber-modified epoxy resin was investigated using amine-terminated butadiene acrylonitrile (ATBN) rubber. Rubber-modified samples were tested at various loading rates in the range of 1-1000 mm/min. At low loading rates, modified resin exhibited a high fracture toughness, which decreased by increasing the rate of loading. At higher loading rate a transition region was observed, where the fracture toughness did not change noticeably with increasing the loading rate. Beyond the transition region, the resin fracture toughness dropped dramatically to the level of unmodified epoxy. Fractography of the damage zone showed different toughening...
M.Sc. Thesis Sharif University of Technology ; Borgheei, Mahdi ; Pak, Ali
Numerical simulation of ductile crack growth under cyclic and dynamic loading with a damage-viscoplasticity model, Article Engineering Fracture Mechanics ; Volume 99 , 2013 , Pages 169-190 ; 00137944 (ISSN) ; Eghbalian, M ; Azadi, H ; Saffar, H ; Sharif University of Technology
In this paper, the crack propagation in ductile materials is simulated under cyclic and dynamic loading. The adaptive finite element method is used to model the discontinuity due to crack propagation. The ductile fracture assumptions and continuum damage mechanics are utilized to model the material rupture behavior. Moreover both the rate-independent and rate-dependent constitutive equations are elaborated and the crack closure effect and combined hardening model are discussed in addition to some aspects of finite element implementation. Finally, a comparison is performed between the numerical simulation results and those of experiments to illustrate the robustness of proposed computational...
Article Journal of Computational and Theoretical Nanoscience ; Volume 8, Issue 11 , 2011 , Pages 2187-2192 ; 15461955 (ISSN) ; Simchi, A ; Besharati Givi, M. K ; Rajabpour, A ; Sharif University of Technology
Molecular dynamics (MD) simulations were used to study the mechanical behaviour of β-SiC at nano-scale under tensile loading. Effects of loading rate and tensile temperature on the mechanical properties and failure were studied. Modified embedded-atom method (MEAM) potential and Berendsen thermostat were utilized for modelling. Periodic boundary conditions were employed and the behaviour of material was analyzed under three-axial loading condition at which the stress- strain relation was acceptably size independent. It is shown that with increasing the loading rate from 5 m/s to 70 m/s, the failure strain increases without a remarkable change in the stress-strain relationship. The MD...
Article Magazine of Concrete Research ; Volume 70, Issue 1 , 2018 , Pages 42-54 ; 00249831 (ISSN) ; Shabani, A ; England, G. L ; Shahsavar Gargari, M ; Sharif University of Technology
ICE Publishing 2018
As the reinforcing bars used in concrete structures located in earthquake-prone areas experience strain rates higher than normal quasi-static ones, it is necessary to have a comprehensive understanding of the behaviour of such materials under these rates of loading. In this work, in order to study the behaviour of grade A-III reinforcing-bar steel (based on the GOST standard, a set of technical standards maintained by the Euro-Asian Council for Standardization, Metrology and Certification), a number of monotonic tests on its tensile and compressive strength on (short and long) specimens at various strain rates, 0·002, 0·01, 0·02 and 0·04 s-1, experienced during earthquakes, were carried out....
Article IEEE Transactions on Signal Processing ; Volume 58, Issue 7 , Jun , 2010 , Pages 3828-3841 ; 1053587X (ISSN) ; Khalaj, B. H ; Gershman, A. B ; Sharif University of Technology
To achieve the available performance gains in half-duplex wireless relay networks, several cooperative schemes have been earlier proposed using either distributed space-time coding or distributed beamforming for the transmitter without and with channel state information (CSI), respectively. However, these schemes typically have rather high implementation and/or decoding complexities, especially when the number of relays is high. In this paper, we propose a simple low-rate feedback-based approach to achieve maximum diversity with a low decoding and implementation complexity. To further improve the performance of the proposed scheme, the knowledge of the second-order channel statistics is...