Loading...
Search for:
javan-molaei--b
0.127 seconds
Total 3692 records
A data-driven robust decision-making model for configuring a resilient and responsive relief supply chain under mixed uncertainty
, Article Annals of Operations Research ; 2024 ; 02545330 (ISSN) ; Tavakkoli Moghaddam, R ; Ghanavati Nejad, M ; Asghari Asl, A ; Sharif University of Technology
2024
Abstract
The crucial role of the Relief Supply Chains (RSCs) in the response phase of disaster management is undeniable. However, the literature shows that the simultaneous consideration of the resilience and responsiveness dimensions in designing the RSCs under mixed uncertainty has been ignored by researchers. In this regard, to cover the mentioned gap, the current study aims to configure an RSC by considering two critically important features namely resilience and responsiveness under mixed uncertainty. For this purpose, this work proposed a multi-stage Decision-Making Framework (DMF). In the first stage, a Multi-Objective Model (MOM) is proposed that minimizes the total cost, maximizes the...
URANS simulation of 2D continuous and discontinuous gravity currents
, Article Journal of Applied Sciences ; Volume 8, Issue 16 , 2008 , Pages 2801-2813 ; 18125654 (ISSN) ; Namin, M. M ; Salehi, A. A ; Firoozabadi, B ; Javan, M ; Sharif University of Technology
2008
Abstract
This study seeks to explore the ability of unsteady Reynolds-averaged Navier-Stokes (URANS) simulation approach for resolving two-dimensional (2D) gravity currents on fine computational meshes. A 2D URANS equations closed by a buoyancy-modified k-ε turbulence model are integrated in time with a second-order fractional step approach coupled with a direct implicit method and discretized in space on a staggered mesh using a second-order accurate finite volume approach incorporating a high resolution semi-Lagrangian technique for the convective terms. A series of 2D simulations are carried out for gravity currents from both discontinuous and continuous sources. Comparisons with experimental...
Biological Removal of Nutrients in MBBR Reactors, Using Bardenpho Process Principle
, M.Sc. Thesis Sharif University of Technology ; Borghei, Mehdi (Supervisor)
Abstract
Given that the most polluting industries in the country there. A suitable treatment system for degradation of these compounds is necessary unless unexpected effect on environment will occur.Moving Bed Biofilm Reactor (MBBR) was developed to adopt the best features of the activated sludge process as well as those of the biofilter processes. MBBR has biomass growth on carriers that move freely in the water volume of the reactor. High surface area of carriers make a good condition for biomass attached growth. This system has had good operation in the urban and some industrial wastewaters.In this study, four reactor volume of approximately 16 litr and 6, respectively, in the aerobic, anoxic...
A Novel Approach for Reconstructing Paths Using Visibility Graph
, M.Sc. Thesis Sharif University of Technology ; Zarei, Alireza (Supervisor)
Abstract
Visibility graph is a graph that comprises information about visibility of a set of objects in 2 or 3-dimensional space. By constructing this graph with respect to conditions of environment one can answer questions like minimum Euclidean distance. Inverse of this procedure is required too; i.e. knowing geometrical structure of objects and information about their visibility we want to guess their location in space and, as the saying goes, reconstruct the environment. For example some methods to reconstruct specific polygons knowing which vertices each vertex sees is proposed. In this dissertation we try to reconstruct a 2-dimensional environment that only has two x-monotone paths (chains)
A simple SVM technique on three-phase mpuc7 inverter for solar photovoltaic system
, Article Advances in Electrical and Electronic Engineering ; Volume 20, Issue 2 , 2022 , Pages 170-184 ; 13361376 (ISSN) ; Asgari, M. P ; Sharif University of Technology
VSB-Technical University of Ostrava
2022
Abstract
In This paper, a simple single-dimension Space Vector Modulation (SVM) technique is introduced to implement on three-phase thirteen-level Modified Packed U-Cell (MPUC) inverter for photo-voltaic system in which many DC sources are avail-able. The three-phase thirteen-level converter con-sists of three single-phase seven-level MPUCs that each phase has six switches and two isolated DC sources. One major advantage of proposed method is to produce an output voltage with nearly constant amplitude in desired range in case of input DC voltage fluctuations, which is common in renewable sources like Photovoltaic Systems (PV). On the other hand, the conventional Pulse Width Modulation (PWM)...
A Novel Framework for Change Management Leadership with Focus on Human Resource (HR) Factors
, M.Sc. Thesis Sharif University of Technology ;
Abstract
The world around us changes almost every second, so the economy in this world feels it more by every single minute. When we look at the organizational structures, they experience lots of things for keeping the companies competitive and the human resources have the main role among the other stimulating factors.The human resource management and its improvements have done a lot in this century to organize and manage the human problems in organizations. After that those companies that had more effective strategies become on top of this important management system. By changing fast the work models companies experience more and immediate changes that may not happen even through the years. In this...
Numerical Study of Bubble Behavior in Two-and Three-Dimensional Gas-Solid Fluidized Beds
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
Because of the importance of gas-solid fluidized beds in chemical industrial plants, many experimental and modeling efforts have been conducted the prediction of their behaviors up to now. Gas bubbles have a pivotal role in the hydrodynamics of bubbling gas-solid fluidized beds; so, fundamental understanding of the bubbling behavior of fluidized beds is required to describe bubble-related phenomena such as solids mixing and segregation, reaction conversion, heat and mass transfer, erosion of heat-transfer tubes and particle entrainment. In this work, the effects of different parameters such as bed aspect ratio, bed width, superficial gas velocity, and particle size distribution on the...
Electronic structure of some thymol derivatives correlated with the radical scavenging activity: Theoretical study
, Article Food Chemistry ; Vol. 165, issue , Dec , 2014 , p. 451-459 ; Jebeli Javanb, M ; Sharif University of Technology
2014
Abstract
Molecules acting as antioxidants capable of scavenging reactive oxygen species (ROS) are of upmost importance in the living cell. Thymol derivatives exhibit various antioxidant activities and potential health benefits. Exploration of structure-radical scavenging activity (SAR) was approached with a wide range of thymol derivatives. To accomplish this task, the DPPH experimental assay along with quantum-chemical calculations were also employed for these compounds. By comparing the structural properties of the derivatives of interest, their antioxidant activity was explained by the formation of an intramolecular hydrogen bond and the presence of unsaturated double bond (–CHdouble bond; length...
Analysis and Optimization of the Electronic Health System Using the Blockchain
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor)
Abstract
The electronic health system plays a crucial role in modern healthcare, facilitating efficient data management, secure information exchange, and improved patient care. However, existing systems often face challenges related to security, privacy, scalability, and interoperability. The primary objectives of this study are proposing a system that ensures data security, patient and peer privacy, scalability, data integrity, deniability, traceability, secure data sharing, access control, transparency, real-time monitoring, and security in the drug supply chain. To achieve these objectives, we have proposed a system that encompasses a wide range of requirements of healthcare system. To enhance...
Effects of nano-clay particles on the short-term properties of self-compacting concrete
, Article European Journal of Environmental and Civil Engineering ; Volume 0 - Issue 0 , Oct , 2015 , Page 1-21 ; 19648189 (ISSN) ; Afshar, A ; Vafaei, B ; Booshehrian, A ; Molaei Raisi, E ; Esrafili, A ; Sharif University of Technology
Taylor and Francis Ltd
2015
Abstract
The properties of self-compacting concrete (SCC) can be manipulated by the addition of nano-montmorillonite (NMMT) clays. This paper presents the results of an experimental investigation on incorporating small dosages of NMMT clays (.25, .50, .75 and 1.00% addition by mass of total cementitious material) into SCC. Tests were conducted on fresh and hardened specimens to measure workability (by slump flow, V-funnel and L-box), mechanical (by compressive and splitting tensile strengths), durability (electrical resistivity and water penetration) and microstructural (X-ray diffraction and scanning electron microscopy) properties of control and NMMT-reinforced SCCs. The results showed that the...
Effects of nano-clay particles on the short-term properties of self-compacting concrete
, Article European Journal of Environmental and Civil Engineering ; Volume 21, Issue 2 , 2017 , Pages 127-147 ; 19648189 (ISSN) ; Afshar, A ; Vafaei, B ; Booshehrian, A ; Molaei Raisi, E ; Esrafili, A ; Sharif University of Technology
Taylor and Francis Ltd
2017
Abstract
The properties of self-compacting concrete (SCC) can be manipulated by the addition of nano-montmorillonite (NMMT) clays. This paper presents the results of an experimental investigation on incorporating small dosages of NMMT clays (.25,.50,.75 and 1.00% addition by mass of total cementitious material) into SCC. Tests were conducted on fresh and hardened specimens to measure workability (by slump flow, V-funnel and L-box), mechanical (by compressive and splitting tensile strengths), durability (electrical resistivity and water penetration) and microstructural (X-ray diffraction and scanning electron microscopy) properties of control and NMMT-reinforced SCCs. The results showed that the...
Novel type of two-impinging-jets reactor for solid-liquid enzyme reactions
, Article AIChE Journal ; Volume 52, Issue 2 , 2006 , Pages 692-704 ; 00011541 (ISSN) ; Sharif University of Technology
2006
Abstract
The isomerization of D-glucose to D-fructose using the immobilized glucose isomerase, as a typical model system of solid-liquid enzyme reactions has been carried out in a novel type of two-impinging-jets reactor (TIJR), which is characterized by a rotating inner cylinder in a stationary one. Because of the impinging process, turbulence, and complex trajectory of the solid particles within the reactor, the fractional conversion of glucose obtained in the TIJR increased dramatically compared to that obtained by conventional reaction systems. A compartment model was considered to describe the pattern of flow [residence time distribution (RTD) of solid particles] within the TIJR. Considering...
Structural behavior of sugar radicals formed by proton transfer reaction of deoxycytidine cation radical: Detailed view from NBO analysis
, Article Structural Chemistry ; Volume 23, Issue 4 , 2012 , Pages 1185-1192 ; 10400400 (ISSN) ; Tehrani, Z. A ; Fattahi, A ; Sharif University of Technology
2012
Abstract
The cation radicals of DNA constituents generated by the ionizing radiation initiate the alteration of the bases, which is one main type of cytotoxic DNA lesions. These cation radical spices are known for their role in producing nucleic acid strand break, and it is important to identify the cation radical formation at particular atomic site in these molecules so that the major pathway for the nucleic acid damage may be trapped. In the present study, we explored theoretically energetic, structural, and electronic properties of the possible radicals formed via proton atom abstraction at various sites of sugar part of deoxycytidine cation radical by employing density functional theory at...
Load balancing in UTRAN by bipartite graphs
, Article 4th European Conference on Circuits and Systems for Communications, ECCSC '08, Bucharest, 10 July 2008 through 11 July 2008 ; 2008 , Pages 301-306 ; 9781424424207 (ISBN) ; Bouzari, S. M ; Tabandeh, M ; Sharif University of Technology
2008
Abstract
3g wireless communication is the next version of mobile networks. Load balancing in networks causes efficient using of network resources. In this paper, we propose an efficient algorithm for load balancing of Radio Network Controllers (RNCs) in Radio Access Networks (RANs). As the characteristics of connections between RNCs and BTSs in a RAN are similar to those of graphs, we make use of graphs to solve our problem. The algorithm is based on the finding a path by which the RNCs could exchange their overloads. By using these paths the algorithm load balances the RNCs in an efficient and fast way. By testing our algorithm on networks with different topology and comparing the results, the...
Quick Evaluation Instructions of Earthquake Damage in the Piping Systems Inside the Industrial Complexes
,
M.Sc. Thesis
Sharif University of Technology
;
Ghannad, Mohammad Ali
(Supervisor)
Abstract
This existing research has been conducted to reach quick evaluation instructions to pipe earthquake damages in the piping systems inside the industrial complexes. In the old complexes of such kinds there are cases where field inspections and quality evaluations are urgently required subject to peculiar conditions affecting each piping system inside the units and in certain cases subject to lack of access to the as built-drawings. However, so far any definite instruction hasn’t been available for a quick evaluation of likely damages in piping system: all because of various pipe types, complexity of pipes geometry, different temperatures and pressures in different sections. In this research...
Vibration and Stability of a Pipe Conveying Flow and Application in Firefighting UAVs
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Rohollah (Supervisor)
Abstract
In this project, vibration and stability condition of a pipe conveying flow has been studied for use in firefighting plane. The Plane is a multi-rotor that carries the pipe to a certain height and it does the washing work there, bassed on the fluid flow from the nozzle embedded in the end of the pipe. Due to the flexibility of the pipe in this application, structure modeling is based on cable without bending stiffness. The Galerkin method is used to solve equations by considering the assumed mode shape for structure. At first, by analyzing free vibrations, different boundary conditions were considered for the pipe and the natural frequencies and natural shape modes were extracted in...
Transient and steady-state analysis of heat, mass, and momentum transfer in developing and fully-developed regions of homogeneous tubular reactors with non-Newtonian fluid flow
, Article Energy Conversion and Management ; Volume 65 , 2013 , Pages 308-321 ; 01968904 (ISSN) ; Hashemi Amrei, S. M. H ; Molaei Dehkordi, A ; Haghi, M ; Sharif University of Technology
2013
Abstract
In this article, the problem of simultaneous heat, mass, and momentum transfer in the developing region of tubular reactors with homogeneous chemical reaction and laminar power-law fluid flow under unsteady-state conditions has been solved. In this regard, the general governing equations were solved using finite-difference method and analyzed carefully. Moreover, the influences of various parameters and dimensionless numbers such as power-law index, heat of reaction, reaction order, and Damköhler number value on the numerical results were investigated. In addition, the numerical results obtained for the fully-developed velocity distribution of Newtonian fluid flow and Sherwood number value...
Theoretical investigation on antioxidant activity of bromophenols from the marine red alga Rhodomela confervoides: H-atom vs electron transfer mechanism
, Article Journal of Agricultural and Food Chemistry ; Volume 61, Issue 7 , 2013 , Pages 1534-1541 ; 00218561 (ISSN) ; Javan, M. J ; Tehrani, Z. A ; Sharif University of Technology
2013
Abstract
Bromophenols are known as antioxidant radical scavengers for some biomolecules such as those in marine red alga. Full understanding of the role played by bromophenols requires detailed knowledge of the radical scavenging activities in probable pathways, a focus of ongoing research. To gain detailed insight into two suggested pathways, H-atom transfer and electron transfer, theoretical studies employing first principle quantum mechanical calculations have been carried out on selected bromophenols. Detailed investigation of the aforementioned routes revealed that upon H-atom abstraction or the electron transfer process, bromophenols cause an increase in radical species in which the unpaired...
Investigation of in situ prepared polypropylene/clay nanocomposites properties and comparing to melt blending method
, Article Materials and Design ; Volume 31, Issue 1 , 2010 , Pages 76-84 ; 02641275 (ISSN) ; Ramazani S. A. A ; Javan Nikkhah, S ; Sharif University of Technology
2010
Abstract
The morphological, physical and mechanical properties of polypropylene/clay nanocomposites (PPCNs) were prepared by in situ polymerization are investigated. Non-modified scmectite type clay (e.g. bentonite) was used to prepare bi-supported Ziegler-Natta catalyst of TiCl4/Mg(OEt)2/clay. Exfoliated PPCNs were obtained by in situ intercalative polymerization of propylene using produced bi-supported catalyst. X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) micrograph were used to assess the clay morphology and dispersion of clay. The crystalline structures of PPCNs were characterized by differential scanning calorimetry (DSC). The mechanical properties of PPCNs were...
A low power high resolution time to digital converter for ADPLL application
, Article 59th IEEE International Midwest Symposium on Circuits and Systems, MWSCAS 2016, 16 October 2016 through 19 October 2016 ; 2017 ; 15483746 (ISSN); 9781509009169 (ISBN) ; Hajsadeghi, K ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
A new nonlinear Time to Digital Converter (TDC) based on time difference amplification is the proposed. A new gain compensation method is presented to expand the DR of conventional × 2 Time Amplifiers (TAs). Instead of conventional gain compensation approach based on changing strength of current sources, the proposed technique uses current difference which results more stable gain over wider DR. In order to avoid two different paths of the stages, a sign bit detection part is the proposed at the front of the TDC to allow using one path of stages for both positive and negative input time differences. As a result, the most advantages of the proposed TDC are its high resolution, wide DR, and...