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Characteristics of a biopolymer flocculant produced by Bacillus sp.As-101
, Article Scientia Iranica ; Volume 8, Issue 3 , 2001 , Pages 207-210 ; 10263098 (ISSN) ; Alemzadeh, I ; Salehizadeh, H ; Sharif University of Technology
Sharif University of Technology
2001
Abstract
In this paper, a biopolymer flocculant-producing bacteria, strain As-101, isolated from activated sludge and identified as Bacillus species is considered. Study of the basic characteristics and comparison of the strain were carried out according to Bergey's manual of bacteriology and the bacterium was identified as Bacillus Coagulants. The activated sludge was treated by a commercial protease (trypsin) with an optimum concentration of 0.4 mg/ml for producing the maximum extent of deflocculation, which was near 16%. The production of bioflocculant by Bacillus As-101 was not parallel to the cell growth and a large amount of the bioflocculant was released into the culture at the end of the...
Mitigation of Current Transformer Residual Flux to Optimize the Current Transformer Core Dimension (in Auto-Reclose Scheme)
, M.Sc. Thesis Sharif University of Technology ; Vakilian, Mehdi (Supervisor)
Abstract
Residual flux in a current transformer (CT) could result in CT saturation while short-circuit faults occur. This phenomenon causes unreliable operation of protective relays. This problem gets worse especially when autoreclosure scheme is used. In this research, a novel method is proposed for the mitigation of CT residual flux in duration of reclosing dead time. This method is implemented by a low-voltage dc source, a suitable power-electronic switching unit (inverter), and a simple and efficient controller. In the proposed method, the dead time of reclosing is detected based on a least error squarer (LES) filter. Then switching controller leads the CT to both opposite saturation regions and...
Some investigations on bioflocculant producing bacteria
, Article Biochemical Engineering Journal ; Volume 5, Issue 1 , 2000 , Pages 39-44 ; 1369703X (ISSN) ; Vossoughi, M ; Alemzadeh, I ; Sharif University of Technology
2000
Abstract
Bacillus sp. As-101 which produces flocculating substances was isolated from activated sludge, using a proteolytic enzyme. Bioflocculant As-101 was partially purified by cold ethanol and cetylpyridinium chloride. The partially purified flocculating substance was an acidic polysaccharide including uronic, pyruvic and acetic acids, respectively, in an approximate ratio of 11.4%, 6.1%, 0.4%. The biopolymer is also a sugar-protein derivative consisting of glucose, mannose and galactose. The protein, the sugar contents ratio is about 83-17%. Bioflocculant As-101 acted under acidic condition and the maximum activity was observed at optimum pH ˜ 3.7 and optimum concentration of 30 ppm in kaolin...
Analyzing the Kinematic Synergies of Cerebral Palsy Patients in Comparison with Healthy Individuals Based on Identical Activation Patterns
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor)
Abstract
One of the common motor disorders among children is cerebral palsy. On average, 1 to 4 out of every 1000 children born are affected by this disease. Defects in the central nervous system, along with musculoskeletal system disorders, are noticeable in cerebral palsy. In recent years, various methods have been proposed for motor control analysis. One of these methods is the synergy hypothesis, which can be used to explain the performance of the central nervous system in controlling and moving body parts. However, in previous studies, the kinematic synergies of healthy and cerebral palsy groups have often been extracted separately without considering their interrelation. Typically, four or five...
An integrated model for citizen energy communities and renewable energy communities based on clean energy package: a two-stage risk-based approach
, Article Energy ; Volume 277 , 2023 ; 03605442 (ISSN) ; Rashidinejad, M ; Fatemi Ardestani, F ; Abdollahi, A ; Salehizadeh, M. R ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
Energy communities are at the heart of forming sustainable cities. Beside their important role in decarbonization, they can bring economic, and social benefits to the End-users. Based on the Clean Energy Package (CEP) definition in European Union, an energy community is categorized as: Citizen Energy Communities (CECs) and Renewable Energy Communities (RECs). In this regard, modeling an energy management system framework in a Smart Multi-Carrier Energy Network (SMCEN) associated with CECs and RECs is much of interest. In this paper, a two-stage risk-based optimization model is proposed to handle an energy management structure incorporating energy communities. To this purpose, Energy...
A home energy management model considering energy storage and smart flexible appliances: A modified time-driven prospect theory approach
, Article Journal of Energy Storage ; Volume 48 , 2022 ; 2352152X (ISSN) ; Rashidinejad, M ; Fatemi Ardestani, S. F ; Abdollahi, A ; Salehizadeh, M. R ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Smart home is a small but an important energy segment that has a significant potential to implement authentic energy policies, where human is a major decision-maker in the home energy management dilemma. Therefore, humans’ emotions and tendencies plays a vital role as the End-User's daily decisions. In this paper, we develop a behavioral home energy management model based on time-driven prospect theory incorporating energy storage devices, distributed energy resources, and smart flexible home appliances. The conventional prospect theory is then modified by considering the psychological time discount effect in the value function. The non-flexible load and photovoltaic generation uncertainties...
Probabilistic/information gap decision theory-based bilevel optimal management for multi-carrier network by aggregating energy communities
, Article IET Renewable Power Generation ; Volume 17, Issue 6 , 2023 , Pages 1436-1465 ; 17521416 (ISSN) ; Rashidinejad, M ; Ardestani, S. F. F ; Abdollahi, A ; Salehizadeh, M. R ; Sharif University of Technology
John Wiley and Sons Inc
2023
Abstract
Energy communities are one of the vital puzzle pieces of future smart cities. This paper proposes a novel structure for a sustainable smart city by integrating energy communities in a multi-carrier energy network. Each energy community has a manager; the so-called Energy Community Managers (ECM), who trades energy with the upstream Multi-Carrier Network Operator (MCNO). On the other hand, MCNO participates in the upstream energy markets to satisfy the demands of energy communities by maximizing its own profit. Therefore, ECMs and MCNO should solve a bilevel optimization problem associated with some common variables at both levels such as: energy carrier price and the amount of energy carrier...
Nonlinear interstory drift contours for idealized forward directivity pulses using "modified fish-bone" models
, Article Advances in Structural Engineering ; Volume 18, Issue 5 , May , 2015 , Pages 603-627 ; 13694332 (ISSN) ; Khosravi, H ; Jamnani, H. H ; Sharif University of Technology
Multi-Science Publishing Co. Ltd
2015
Abstract
Four 5-, 10-, 20- and 30-story moment frames, representing low-, mid-, and two high-rise structures, were subjected to a great number of idealized directivity pulses. The amplitudes and periods of pulses vary from 0.02 g to 1.0 g and 0.5 to 12 sec, respectively. Over 1400 nonlinear dynamic analyses of low- to high-rise moment frames were performed which were feasible through using modified fish-bone model. The distribution of interstory drift along the height was studied and two applied contours were proposed: (i) the maximum interstory drift contour, and (ii) the critical story contour. These contours were demonstrated versus the ratio of natural period of the structure to the pulse period...
Analysis of singularities of a 3DOF parallel manipulator based on a novel geometrical method
, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Sadeghian, H ; Roozbehani, H ; Zohoor, H ; Sharif University of Technology
2006
Abstract
In this article singular points of a parallel manipulator are obtained based on a novel geometrical method. Here we introduce the constrained plain method (CPM) and some of its application in parallel mechanism. Given the definition of constraint plane (CP) and infinite constraint plane (ICP) the dependency conditions of constraints is achieved with the use of a new theorem based on the Ceva geometrical theorem. The direction of angular velocity of a body is achieved by having three ICPs with the use of another theorem. Finally, with the use of the above two novel theorems singularities of the 3UPF_PU mechanism are obtained. It should be emphasized that this method is completely geometrical,...
Melting enthalpy and entropy of freestanding metallic nanoparticles based on cohesive energy and average coordination number
, Article Journal of Physical Chemistry C ; Volume 115, Issue 35 , August , 2011 , Pages 17310-17313 ; 19327447 (ISSN) ; Delavari H., H ; Madaah Hosseini, H. R ; Sharif University of Technology
2011
Abstract
An analytical model is proposed to study the effect of particle size on melting enthalpy and entropy of metallic nanoparticles (NPs). The Mott's and Regel's equations for melting entropy in the combination of core average coordination number (CAC) and surface average coordination number (SAC) of freestanding NPs are considered. Clusters of icosahedral (IC), body centered cubic (BCC), and body centered tetragonal (BCT) structure without any vacancies and defects are modeled. Using the variable coordination number made this model to be in good agreement with experimental and molecular dynamic (MD) results of different crystal structures. The model predicts melting entropy and enthalpy of...
On the temperature and residual stress field during grinding
, Article WCE 2010 - World Congress on Engineering 2010, 30 June 2010 through 2 July 2010 ; Volume 2 , 2010 , Pages 1196-1200 ; 9789881821072 (ISBN) ; Farrahi, G. H ; Ghadbeigi, H ; Sharif University of Technology
2010
Abstract
Grinding is widely used for manufacturing of components that require fine surface finish and good dimensional accuracy. In this study a thermo-mechanical finite element analysis is conducted to find out how grinding parameters can affect temperature and residual stress distribution in the workpiece. Results of parametric study presented in this work indicate, by carefully selecting the grinding parameters, minimum thermal and mechanical damage can be achieved. Higher workpiece velocities produce higher surface residual stress. By increasing depths of cut, depth of tensile residual stresses increases. Convection heat coefficient does not have any considerable effect on surface residual stress...
A new lattic LP-based post filter for adaptive noise cancellers in mobile and vehicular applications
, Article Proceedings of the 8th IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2008, 16 December 2008 through 19 December 2008, Sarajevo ; 2008 , Pages 407-412 ; 9781424435555 (ISBN) ; Sameti, H ; Veisi, H ; Abutalebi, H. R ; Sharif University of Technology
2008
Abstract
Adaptive Noise Cancellation (ANC) is a well-known technique for background noise reduction in automobile and vehicular environments. The noise fields in automobile and other vehicle interior obey the diffuse noise field model closely. On the other hand, the ANC does not provide sufficient noise reduction in the diffuse noise fields. In this paper, a new multistage post-filter is designed for ANC as a solution to diffuse noise conditions. The designed post-filter is a single channel Linear Prediction (LP) based speech enhancement system. The LP is performed by an adaptive lattice filter and attempts to extract speech components by using intermediate ANC signals. The post-filter has no...
Finite element analysis of shot-peening effect on fretting fatigue parameters
, Article Tribology International ; Volume 44, Issue 11 , 2011 , Pages 1583-1588 ; 0301679X (ISSN) ; Alvandi Tabrizi, Y ; Farrahi, G. H ; Majzoobi, G. H ; Ghadbeigi, H ; Sharif University of Technology
2011
Abstract
Shot peening is widely used to improve the fretting fatigue strength of critical surfaces. Fretting fatigue occurs in contacting parts that are subjected to fluctuating loads and sliding movements at the same time. This paper presents a sequential finite element simulation to investigate the shot peening effects on normal stress, shear stress, bulk stress and slip amplitude, which are considered to be the controlling parameters of fretting damage. The results demonstrated that among the modifications related to shot peening, compressive residual stress has a dominant effect on the fretting parameters
Mechanically activated synthesis of single crystalline MgO nanostructures
, Article Journal of Alloys and Compounds ; Volume 506, Issue 2 , September , 2010 , Pages 715-720 ; 09258388 (ISSN) ; Yoozbashizadeh, H ; Askari, M ; Kobatake, H ; Fukuyama, H ; Sharif University of Technology
2010
Abstract
One-dimensional (1D) MgO structures were successfully synthesized via carbothermic reduction of mechanically activated mixture of MgO and graphite. Mechanical activation of source materials before carbothermic reduction can substantially enhance the formation of MgO products at a temperature (1000 °C) relatively lower than that required in previous approaches (≥1200 °C). However, the morphology of MgO formed is dependent on the degree of mechanical activation and the condition of the subsequent carbothermic reduction. Two distinctive morphologies were found for MgO products synthesized using our method: single crystalline nanorods with rectangular cross-sections whose diameters range from 50...
Boundary control design for vibration suppression and attitude control of flexible satellites with multi-section appendages
, Article Acta Astronautica ; Volume 173 , 2020 , Pages 22-30 ; Salarieh, H ; Nejat Pishkenari, H ; Jalili, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Attitude and vibration control of a general form of flexible satellites is addressed in this paper. Partial differential dynamic equations are derived considering new details such as multi sectioned solar panels and elastic connections between main hub and solar panels. Boundary control approach is adopted to eliminate simplification errors of discrete models, using just one actuator in the hub. Asymptotic stability of attitude dynamics is proved for a group of boundary controllers and necessary conditions for asymptotic stability of vibrations are discussed. Being independent of modeling accuracy and using easily measurable feedbacks are among advantages of the proposed class of...
Characterization and calcination behavior of a low-grade manganese ore
, Article Materials Today Communications ; Volume 25 , 2020 ; Becker, H ; Eftekhari, H ; Yoozbashizadeh, H ; Safarian, J ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Characterization and calcination behavior of a low-grade manganese ore, as a part of Mn ferroalloys production, was studied by XRF, ex-situ XRD, in-situ XRD, and SEM-EDS techniques. Calcination experiments were carried out at and up to 900 °C (1173 K) in air and argon atmospheres. The samples were in particles and powder forms. The results indicated that both quartz and calcite phases in the ore exhibit a bimodal spatial distribution; as relatively large regions and finely distributed in the Mn- and Fe-containing phases. By Rietveld analysis of the in-situ XRD data, the reactions occurring upon heating during the calcination process were deduced. Thermal decomposition and reactive diffusion...
Minimizing the error of time difference of arrival method in mobile networks
, Article 2005 International Conference on Wirelessand Optical Communications Networks, Dubai, 6 March 2005 through 8 March 2005 ; 2005 , Pages 328-332 ; 0780390199 (ISBN); 9780780390195 (ISBN) ; Aghababa, H ; Radfar, M. H ; Khalaj, B. H ; Sharif University of Technology
2005
Abstract
Estimating the position of a mobile set is of great importance in new mobile services. However, in most cases, the accuracy should be less than 100 meters. This accuracy is hard to reach especially in urban areas. The main problem is that there are a lot of obstacles like buildings between the BTS and the mobile set. Thus the time measured between BTS and the mobile set is somehow greater than the time it takes the wave to travel directly between two points. This paper introduces an optimized solution for TDOA as one of the most efficient ways for finding the location of a mobile phone. Considering the standards and limitations of both GSM and UMTS, the Authors present a solution for...
A fast and novel method of pattern synthesis for non-uniform phased array antennas
, Article Proceedings International Radar Symposium, 24 June 2015 through 26 June 2015 ; Volume 2015-August , 2015 , Pages 924-929 ; 21555753 (ISSN) ; 9783954048533 (ISBN); 9783954048533 (ISBN); 9783954048533 (ISBN) ; Sebt, M. A ; Nayebi, M. M ; Behroozi, H ; Rohling, H ; Rohling, H ; Rohling, H ; Sharif University of Technology
IEEE Computer Society
2015
Abstract
Weighting elements to achieve radiation patterns with desired characteristics is a classical work in phased array antennas. These characteristics can be low sidelobe level, narrow beamwidth, high directivity, pattern nulling in special angle and etc. For each of these characteristics, different methods have been introduced. Most of methods have been presented for uniform arrays, however there are lots of methods to obtain a desired pattern for antennas with non-uniform element distances. The problem with these methods is complexity or not very good results. In this paper, fast and easy methods based on Least Square Error that leads to good results are presented. In addition, weighting of...
Size-dependent interaction of an edge dislocation with an elliptical nano-inhomogeneity incorporating interface effects
, Article International Journal of Solids and Structures ; Volume 49, Issue 5 , March , 2012 , Pages 759-770 ; 00207683 (ISSN) ; Ahmadzadeh Bakhshayesh, H ; Gutkin, M. Y
2012
Abstract
The elastic behavior of an edge dislocation, which is positioned outside of a nanoscale elliptical inhomogeneity, is studied within the interface elasticity approach incorporating the elastic moduli and surface tension of the interface. The complex potential function method is used. The dislocation stress field and the image force acting on the dislocation are found and analyzed in detail. The difference between the solutions obtained within the classical-elasticity and interface-elasticity approaches is discussed. It is shown that for the stress field, this difference can be significant in those points of the inhomogeneity-matrix interface, where the radius of curvature is smaller and which...
Control of parallel three- phase inverters using optimal control and SVPWM technique
, Article IEEE International Symposium on Industrial Electronics, 5 July 2009 through 8 July 2009 ; 2009 , Pages 1823-1828 ; 9781424443499 (ISBN) ; Mokhtari, H ; Sharif University of Technology
2009
Abstract
In this paper, optimal control strategy is applied to parallel three-phase inverters using SVPWM technique. The three-phase system is transformed to a synchronous-stationary frame, suitable cost functions are defined, and the switching schemes are determined for the inverters. The control strategy minimizes the circulating current between the inverters, therefore, proper load sharing scheme is achieved. Simulations are performed for steady state and load change operation, and the results which show the suitability of the controller are provided. ©2009 IEEE