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Measuring limb darkening of stars in high-magnification microlensing events by the Finite Element Method
, Article Monthly Notices of the Royal Astronomical Society ; Volume 494, Issue 1 , 2020 , Pages 584-597 ; Rahvar, S ; Sharif University of Technology
Oxford University Press
2020
Abstract
The finite-size effect in gravitational microlensing provides a possibility to measure the limb darkening of distant stars. We use the Finite Element Method (FEM) as an inversion tool for discretization and inversion of the magnification-limb darkening integral equation. This method makes no explicit assumption about the shape of the brightness profile more than the flatness of the profile near the centre of the stellar disc. From the simulation, we investigate the accuracy and stability of this method and we use regularization techniques to stabilize it. Finally, we apply this method to the single lens, high-magnification transit events of OGLE-2004-BLG-254 (SAAO-I),...
Measuring Limb Darkening of Distant Stars Using Microlensing Events by Finite Element Method
, Ph.D. Dissertation Sharif University of Technology ; Rahvar, Sohrab (Supervisor)
Abstract
The finite-size effect in gravitational microlensing provides a possibility to measure the variation of surface brightness of stars from centre to limb which is called limb darkening profile. Measuring limb darkening profile provides information about star atmosphere. It is also useful in other fields of astrophysics. In this thesis we develop a numerical method to recover limb darkening of source stars from single lens microlensing light curves with finite source effect in which the lens transits the source disk. We use the Finite Element Method (FEM) as an inversion tool for discretization and inversion of the finite source effect integral equation. This method makes no explicit assumption...
Evaluating the Changes in the Mean Vector and Covariance Matrix of EDP Distribution for different IM and Ground Motion Selections
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofouei, Fayyaz (Supervisor)
Abstract
In this study, the changes in the mean vector and the covariance matrix of engineering demand parameter (EDP) distributions for different intensity measures and ground motion selections is evaluated. Although, the changes in the mean distribution of EDPs have been extensively studied in the literature, but the changes in the covariance matrix of EDPs distributions caused by ground motion selections has not been paid the due attention. In other words, no study has specifically looked into the effect of intensity measure changes on the covariance matrix; therefore, for the purpose of this study, several steel frame models were considered with perimeter special moment resisting frames (SMRF)....
Development of a Covering Location Model in Congested Networks
, M.Sc. Thesis Sharif University of Technology ; Shavandi, Hassan (Supervisor)
Abstract
Plants, distribution centers, and other facilities generally function for years or decades, during which time the environment in which they operate may change substantially. Costs, demands, travel times, and other inputs to classical facility location models may be highly uncertain. So when making decisions of location considering the factors that may change is beneficial. In this thesis a version of covering location model under uncertainty in a congested system is proposed. The aim is to locate m facilities to maximize the captured customer utility, having in mind that there may be up to q facilities established in future; the only information at hand about the number of the new facilities...
Design, construction, and evaluation of “sensor lock”: an electromechanical stance control knee joint
, Article Disability and Rehabilitation: Assistive Technology ; Volume 13, Issue 3 , 2018 , Pages 226-233 ; 17483107 (ISSN) ; Ahmadi Bani, M ; Baniasad, M ; Samadian, M ; Golchin, N ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
Background and aim: Most currently-available stance control knee ankle foot orthoses (SCKAFOs) still need full knee extension to lock the knee joint, and they are still noisy, bulky, and heavy. Therefore, the aim of this study was to design, construct, and evaluate an original electromechanical SCKAFO knee joint that could feasibly solve these problems, and thus address the problems of current stance control knee joints with regards to their structure, function, cosmesis, and cost. Method: Ten able-bodied (AB) participants and two (knee ankle foot orthosis) KAFO users were recruited to participate in the study. A custom SCKAFO with the same set of components was constructed for each...
Design, construction, and evaluation of “sensor lock”: an electromechanical stance control knee joint
, Article Disability and Rehabilitation: Assistive Technology ; 2017 , Pages 1-8 ; 17483107 (ISSN) ; Ahmadi Bani, M ; Baniasad, M ; Samadian, M ; Golchin, N ; Sharif University of Technology
2017
Abstract
Background and aim: Most currently-available stance control knee ankle foot orthoses (SCKAFOs) still need full knee extension to lock the knee joint, and they are still noisy, bulky, and heavy. Therefore, the aim of this study was to design, construct, and evaluate an original electromechanical SCKAFO knee joint that could feasibly solve these problems, and thus address the problems of current stance control knee joints with regards to their structure, function, cosmesis, and cost. Method: Ten able-bodied (AB) participants and two (knee ankle foot orthosis) KAFO users were recruited to participate in the study. A custom SCKAFO with the same set of components was constructed for each...
Design and analysis of an original powered foot clearance creator mechanism for walking in patients with spinal cord injury
, Article Disability and Rehabilitation: Assistive Technology ; March , 2018 , Pages 1-5 ; 17483107 (ISSN) ; Badri, S ; Shayestehepour, H ; Arazpour, M ; Farahmand, F ; Mousavi, M. E ; Abdolahi, E ; Farkhondeh, H ; Head, J. S ; Golchin, N ; Mardani, M. A ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
Background: The aim of this study was to assess the performance of an original powered foot clearance creator (PFCC) mechanism worn in conjunction with an isocentric reciprocal gait orthosis (IRGO) and evaluate its effect on trunk compensatory movements and spatiotemporal parameters in nine healthy subjects. Method: A PFCC motorized mechanism was designed that incorporated twin sole plates, the movements of which enabled increased toe to floor clearance during swing phase. A prototype was constructed in combination with an IRGO, and hence was re-named as an IRGO-PFCC orthosis. The effects of IRGO-PFCC usage on the spatiotemporal parameters and trunk compensatory movements during walking were...
Design and analysis of an original powered foot clearance creator mechanism for walking in patients with spinal cord injury
, Article Disability and Rehabilitation: Assistive Technology ; Volume 14, Issue 4 , 2019 , Pages 333-337 ; 17483107 (ISSN) ; Badri, S ; Shayestehepour, H ; Arazpour, M ; Farahmand, F ; Mousavi, M. E ; Abdolahi, E ; Farkhondeh, H ; Head, J. S ; Golchin, N ; Mardani, M. A ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
Background: The aim of this study was to assess the performance of an original powered foot clearance creator (PFCC) mechanism worn in conjunction with an isocentric reciprocal gait orthosis (IRGO) and evaluate its effect on trunk compensatory movements and spatiotemporal parameters in nine healthy subjects. Method: A PFCC motorized mechanism was designed that incorporated twin sole plates, the movements of which enabled increased toe to floor clearance during swing phase. A prototype was constructed in combination with an IRGO, and hence was re-named as an IRGO-PFCC orthosis. The effects of IRGO-PFCC usage on the spatiotemporal parameters and trunk compensatory movements during walking were...
Impact of rock mineralogy on reservoir souring: A geochemical modeling study
, Article Chemical Geology ; Volume 555 , November , 2020 ; Zhang, L ; Liu, L ; Shabani, A ; Sharif University of Technology
Elsevier B. V
2020
Abstract
The petroleum industry suffers from reservoir souring phenomena, which has negative impacts on production facilities, health, and environment. Injection of incompatible water into the reservoir (waterflooding), which is considered as an enhanced oil recovery (EOR) method, is one of the most common causes of reservoir souring. In general, injected brine, especially seawater, contains high amounts of sulfate ion (SO42−). A high concentration of sulfate in the presence of sulfate-reducing bacteria (SRB) leads to the microbial reservoir souring. During this phenomenon, sulfide, specifically hydrogen sulfide gas (H2S) appears in the producing fluid of the reservoir. In this paper, a coupled...
A mechanobiological mathematical model of liver metabolism
, Article Biotechnology and Bioengineering ; Volume 117, Issue 9 , 5 June , 2020 , Pages 2861-2874 ; Firoozabadi, B ; Munn, L. L ; Sharif University of Technology
John Wiley and Sons Inc
2020
Abstract
The liver plays a complex role in metabolism and detoxification, and better tools are needed to understand its function and to develop liver-targeted therapies. In this study, we establish a mechanobiological model of liver transport and hepatocyte biology to elucidate the metabolism of urea and albumin, the production/detoxification of ammonia, and consumption of oxygen and nutrients. Since hepatocellular shear stress (SS) can influence the enzymatic activities of liver, the effect of SS on the urea and albumin synthesis are empirically modeled through the mechanotransduction mechanisms. The results demonstrate that the rheology and dynamics of the sinusoid flow can significantly affect...
cis-Dioxo-molybdenum(VI)-oxazoline complex catalyzed epoxidation of olefins by tert-butyl hydrogen peroxide
, Article Inorganica Chimica Acta ; Volume 362, Issue 10 , 2009 , Pages 3698-3702 ; 00201693 (ISSN) ; Tahsini, L ; Latifi, R ; Keith Woo, L ; Sharif University of Technology
2009
Abstract
A new efficient catalytic system was investigated for the epoxidation of various olefins by cis-dioxo-bis[2-(2′-hydroxyphenyl)-oxazolinato]molybdenum(VI), cis-[MoO2(phox)2], and TBHP as oxidizing agent. Using this system as catalyst for the oxidation of aliphatic substrates at 80 °C gives the epoxide as the sole product with yields up to 100% and turnover frequency up to 5000 h-1. The efficiency of the catalyst is strongly influenced by the nature of solvent, reaction time and temperature, and a significant increase in the epoxide yields is observed in higher temperatures and longer reaction times. © 2009 Elsevier B.V
Is negative attention better than no attention? The comparative effects of ostracism and harassment at work
, Article Organization Science ; Volume 26, Issue 3 , 2015 , Pages 774-793 ; 10477039 (ISSN) ; Robinson, S. L ; Berdahl, J. L ; Banki, S ; Sharif University of Technology
INFORMS Inst.for Operations Res.and the Management Sciences
2015
Abstract
Ostracism has been recognized as conceptually and empirically distinct from harassment. Drawing from theory and research that suggests that employees have a strong need to belong in their organizations, we examine the comparative frequency and impact of ostracism and harassment in organizations across three field studies. Study 1 finds that a wide range of employees perceive ostracism, compared with harassment, to be more socially acceptable, less psychologically harmful, and less likely to be prohibited in their organization. Study 2 surveyed employees from a variety of organizations to test our theory that ostracism is actually a more harmful workplace experience than harassment....
Dielectrophoretic cell sorting via sliding cells on 3D silicon microelectrodes
, Article Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS), 22 January 2017 through 26 January 2017 ; 2017 , Pages 147-150 ; 10846999 (ISSN) ; 9781509050789 (ISBN) ; Chan, M. L ; Roshan, K. A ; Yobas, L ; Sharif University of Technology
2017
Abstract
This work presents an innovative design for a flow-through dielectrophoretic cell sorting based on silicon bulk microelectrodes featuring sidewall undercuts. The microelectrodes are configured into an interdigitated array with digits extending across the flow chamber at an oblique angle against the flow stream. Target cells under dielectrophoretic forces and hydrodynamic drag can slide along the digits to a dedicated outlet. The design has been showcased for continuous-flow sorting of viable and non-viable mammalian cells, achieving a throughput of 16,600 cells/min, an order of magnitude higher than those reported for existing continuous-flow cell sorting designs using thin-film or...
A multi-scale model for determining the effects of pathophysiology and metabolic disorders on tumor growth
, Article Scientific Reports ; Volume 10, Issue 1 , 20 February , 2020 ; Firoozabadi, B ; Mozafari, A ; Munn, L. L ; Sharif University of Technology
Nature Research
2020
Abstract
The search for efficient chemotherapy drugs and other anti-cancer treatments would benefit from a deeper understanding of the tumor microenvironment (TME) and its role in tumor progression. Because in vivo experimental methods are unable to isolate or control individual factors of the TME and in vitro models often do not include all the contributing factors, some questions are best addressed with systems biology mathematical models. In this work, we present a new fully-coupled, agent-based, multi-scale mathematical model of tumor growth, angiogenesis and metabolism that includes important aspects of the TME spanning subcellular-, cellular- and tissue-level scales. The mathematical model is...
Deviatoric stress response envelopes from multiaxial tests on sand
, Article Solid Mechanics and its Applications ; Volume 146 , 2007 , Pages 253-262 ; 09250042 (ISSN); 9781402061455 (ISBN) ; Sadek, T ; Dihoru, L ; Lings, M. L ; Sharif University of Technology
Springer Verlag
2007
Abstract
Sets of rosettes of stress probes have been performed on Hostun sand in a flexible boundary true triaxial apparatus. These have shown the effect of stress history on the local distortional stiffness of the sand. Histories have included isotropic compression, and deviatoric paths with increasingly complex shapes. These tests were performed and interpreted against a background of kinematic hardening and bounding surface plasticity, using stress response envelopes to reveal evolving distortional stiffness. Use of response envelopes to study volumetric stiffness appears to be less helpful but the phase transformation surfaces that can be extracted seem somewhat independent of recent stress...
Gas chromatography with atomic emission detection: A powerful technique
, Article TrAC - Trends in Analytical Chemistry ; Volume 21, Issue 9-10 , 2002 , Pages 618-626 ; 01659936 (ISSN) ; Brinkman, U. A.Th ; Bagheri, H ; Sharif University of Technology
Elsevier
2002
Abstract
Atomic emission detection (AED) is a sensitive as well as a selective detection technique for gas chromatography (GC) and provides element-specific information. A rapidly increasing number of applications in many different areas illustrates the versatility and analytical power of the technique - especially when complex samples have to be analysed. The complementary use of GC-AED and GC with mass-spectrometric detection often yields the most rewarding results. © 2002 Published by Elsevier Science B.V. All rights reserved
A state-of-the-art model for spatial and stochastic oil spill risk assessment: A case study of oil spill from a shipwreck
, Article Environment International ; Volume 126 , 2019 , Pages 309-320 ; 01604120 (ISSN) ; Arneborg, L ; Lindgren, J. F ; Lindhe, A ; Rosén, L ; Raie, M ; Axell, L ; Hassellöv, I. M ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Oil spills are serious environmental issues that potentially can cause adverse effects on marine ecosystems. In some marine areas, like the Baltic Sea, there is a large number of wrecks from the first half of the 20th century, and recent monitoring and field work have revealed release of oil from some of these wrecks. The risk posed by a wreck is governed by its condition, hazardous substances contained in the wreck and the state of the surrounding environment. Therefore, there is a need for a common standard method for estimating the risks associated with different wrecks. In this work a state-of-the-art model is presented for spatial and stochastic risk assessment of oil spills from...
Polymer-Supported Bis-1,2,4-triazolium ionic tag framework for an efficient Pd(0) catalytic system in biomass derived γ-valerolactone
, Article ACS Sustainable Chemistry and Engineering ; Volume 7, Issue 7 , 2019 , Pages 6939-6946 ; 21680485 (ISSN) ; Mahmoudi, H ; Bivona, L. A ; Piermatti, O ; Bagherzadeh, M ; Fusaro, L ; Aprile, C ; Marrocchi, A ; Vaccaro, L ; Sharif University of Technology
American Chemical Society
2019
Abstract
A resin-bound 1,2,4-triazolium ionic tag has been used as support for the preparation of solid palladium nanoparticles (Pd(0)-POLI-TAG-Pd). Owing to the pincer-type architecture of the triazolium ligand, the stabilization of a high amount of palladium nanoparticles (16 wt %) has been possible. The catalytic system has been fully characterized and used in low amounts (i.e., 0.1 mol % palladium loading) in representative Heck-Mizoroki cross-coupling processes. A negligible release of the metal was demonstrated, and a high activity was obtained over more runs. Besides, the protocol has been optimized for the use of safe biomass-derived γ-valerolactone reaction medium
Synthesis, crystal structure and catalytic activity of a novel Mo(VI)-oxazoline complex in highly efficient oxidation of sulfides to sulfoxides by urea hydrogen peroxide
, Article Inorganica Chimica Acta ; Volume 361, Issue 7 , 2008 , Pages 2019-2024 ; 00201693 (ISSN) ; Tahsini, L ; Latifi, R ; Ellern, A ; Woo, L. K ; Sharif University of Technology
Elsevier S.A
2008
Abstract
Novel molybdenum complex, cis-[MoO2(phox)2] has been synthesized and characterized by IR, 1H NMR, elemental analyses (CHN), and X-ray molecular structure determination methods. This complex was found to be an efficient, selective catalyst for the oxidation of various sulfides to sulfoxides with urea hydrogen peroxide (UHP) in excellent yields (100% for diallylsulfide) and short reaction times (20 min) at room temperature. The catalytic system oxidizes diallylsulfide chemoselectively to its corresponding sulfoxide without any over oxidation in double bond. © 2007 Elsevier B.V. All rights reserved
Exploring source water mixing and transient residence time distributions of outflow and evapotranspiration with an integrated hydrologic model and Lagrangian particle tracking approach
, Article Ecohydrology ; 2018 ; 19360584 (ISSN) ; Condon, L. E ; Danesh Yazdi, M ; Bearup, L. A ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
Understanding the time water takes as it moves from rain or snowmelt through the terrestrial system to arrive as stream discharge, or evapotranspiration (ET) is an important hydrologic quantity. We develop a Lagrangian particle tracking method to capture transient residence times from source to either ET or outflow in an integrated hydrologic model. This method is parallel and efficiently captures time evolution of parcels of water in the model and tracks the source of water for hydrograph or ET separation. We demonstrate this model using hypothetical hillslope simulations driven by snow or rain dominated forcing and two different land cover types. We show that land cover and forcing both...