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baghbanzadeh--sima
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Geometry, supertransfer, and optimality in the light harvesting of purple bacteria
, Article Journal of Physical Chemistry Letters ; Volume 7, Issue 19 , 2016 , Pages 3804-3811 ; 19487185 (ISSN) ; Kassal, I ; Sharif University of Technology
American Chemical Society
2016
Abstract
The remarkable rotational symmetry of the photosynthetic antenna complexes of purple bacteria has long been thought to enhance their light harvesting and excitation energy transport. We study the role of symmetry by modeling hypothetical antennas whose symmetry is broken by altering the orientations of the bacteriochlorophyll pigments. We find that in both LH2 and LH1 complexes, symmetry increases energy transfer rates by enabling the cooperative, coherent process of supertransfer. The enhancement is particularly pronounced in the LH1 complex, whose natural geometry outperforms the average randomized geometry by 5.5 standard deviations, the most significant coherence-related enhancement...
Distinguishing the roles of energy funnelling and delocalization in photosynthetic light harvesting
, Article Physical Chemistry Chemical Physics ; Volume 18, Issue 10 , 2016 , Pages 7459-7467 ; 14639076 (ISSN) ; Kassal, I ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
Photosynthetic complexes improve the transfer of excitation energy from peripheral antennas to reaction centers in several ways. In particular, a downward energy funnel can direct excitons in the right direction, while coherent excitonic delocalization can enhance transfer rates through the cooperative phenomenon of supertransfer. However, isolating the role of purely coherent effects is difficult because any change to the delocalization also changes the energy landscape. Here, we show that the relative importance of the two processes can be determined by comparing the natural light-harvesting apparatus with counterfactual models in which the delocalization and the energy landscape are...
Using satellite data to extract volume-area-elevation relationships for Urmia Lake, Iran
, Article Journal of Great Lakes Research ; Volume 39, Issue 1 , March , 2013 , Pages 90-99 ; 03801330 (ISSN) ; Tajrishy, M ; Sharif University of Technology
2013
Abstract
Urmia Lake in the northwest of Iran is the second largest hyper-saline lake worldwide. During the past two decades, a significant water level decline has occurred in the lake. The existing estimations for the lake water balance are widely variable because the lake bathymetry is unknown. The main focus of this study is to extract the volume-area-elevation (V-A-L) characteristics of Urmia Lake utilizing remote sensing data and analytical models. V-A-L equations of the lake were determined using radar altimetry data and their concurrent satellite-derived surface data. Next, two approximate models, a power model (PM) and a truncated pyramid model (TPM), were parameterized for Urmia Lake and...
Monitoring temperature changes in a hypersaline lake using MODIS-derived water temperatures (the case of Urmia Lake, Iran)
, Article 6th International Symposium on Environmental Hydraulics, Athens, 23 June 2010 through 25 June 2010 ; Volume 2 , 2010 , Pages 881-886 ; 9780415595469 (ISBN) ; Tajrishy, M ; Sharif University of Technology
2010
Abstract
Lake surface temperature is an important indicator of the lake state and a driver of regional weather and climate near large lakes. The objective of this study is to use thermal imagery from the MODIS on board the Earth Observing System Terra and Aqua platforms to assess the spatial and temporal variations in Urmia lake temperature. Urmia Lake, located in northwestern Iran is one of the largest permanent hypersaline lakes in the world. The surface temperature of Urmia Lake is examined between 2008 and 2009, as dry years. MODIS-derived lake SWT then was calibrated with monthly observations. MODIS-derived lake SWT exhibits a cool bias (-0.72°C) relative to in situ temperature observations in...
Water allocation for wetland environmental water requirements: The case of Shadegan wetland, Jarrahi catchment, Iran
, Article World Environmental and Water Resources Congress 2006: Examining the Confluence of Environmental and Water Concerns, Omaha, NE, 21 May 2006 through 25 May 2006 ; 2007 ; 0784408564 (ISBN); 9780784408568 (ISBN) ; Tajrishy, M ; Sharif University of Technology
2007
Abstract
The Shadegan Wetland is a Ramsar-listed wetland in the south-west of Iran at the head of the Persian Gulf. It is the largest wetland of Iran covering about 400,000 hectares. The wetland plays a significant hydrological and ecological role in the natural functioning of the northern Gulf. It also supports a very diverse flora and fauna and is the most important site in the world for Marbled Teal. The water regime is threatened by upstream abstraction of water for irrigation and the saline discharge from sugar cane industries and irrigation schemes. This will result in an overall reduction in wetland water quantity and quality, leading to a change in plant community composition. This paper...
Modelling Evaporation & Salinity Variation in Saline Lakes Using Spatial System Dynamics: The Case of Urmia Lake
,
Ph.D. Dissertation
Sharif University of Technology
;
Tajrishy, Masoud
(Supervisor)
Abstract
Evaporation is the most important water loss from terminal lakes which can influence the chemistry of lakes. In large lakes, the spatial distributions of meteorological and water quality variables affect the evaporation rates. Therefore, it is crucial to consider such variations in estimating evaporation rates from large lakes. This study aims at developing an evaporation estimation model for saline lakes considering salinity and spatial distribution of variables in/over the lakes and investigating the interaction between meteorological, hydrological and water quality variables in natural saline systems. To accomplish these objectives, first a distributed model was developed for estimating...
Distillation of free entanglement from bound entangled states using weak measurements
, Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 88, Issue 6 , 2013 ; ISSN: 10502947 ; Rezakhani, A. T ; Sharif University of Technology
2013
Abstract
We propose a scheme for distillation of free bipartite entanglement from bipartite bound entangled states. The crucial element of our scheme is an ancillary system that is coupled to the initial bound entangled state via appropriate weak measurements. We show that in this protocol free entanglement can be always generated with nonzero probability by using a single copy of the bound entangled state. We also derive a lower bound on the entanglement cost of the protocol and conclude that, on average, applying weaker measurements results in relatively higher values of free entanglement as well as lower costs
Temperature effects on quantum cloning of states and entanglement
, Article Physics Letters, Section A: General, Atomic and Solid State Physics ; Volume 373, Issue 8-9 , 2009 , Pages 821-825 ; 03759601 (ISSN) ; Rezakhani, A. T ; Sharif University of Technology
2009
Abstract
Performances of the symmetric universal and phase-covariant cloning transformations and entanglement cloners - qubit case - are investigated when the initial state of the hardware or the original state to be cloned is weakly coupled to a thermal environment. Different behaviors of each of these transformations are analyzed and contrasted with the ideal cases. © 2009 Elsevier B.V. All rights reserved
Mapping surface temperature in a hyper-saline lake and investigating the effect of temperature distribution on the lake evaporation
, Article Remote Sensing of Environment ; Volume 136 , 2013 , Pages 374-385 ; 00344257 (ISSN) ; Ahmadalipour, A ; Tajrishy, M ; Sharif University of Technology
2013
Abstract
Remote sensing is an effective tool for capturing spatial and temporal variations of water surface temperature (WST) in large lakes. The WST of Urmia Lake in northwestern Iran was examined from 2007 to 2010, using MODIS land surface temperature (LST) products. Spatial and temporal (diurnal, monthly, seasonal and inter-annual) variations of Urmia Lake WST were also investigated. Results indicate that the MODIS-derived WSTs are in a good agreement with the in situ data (R2=0.92 and bias=-0.27). Spatial analysis of WST revealed that there are three thermal zones along the lake: the shallow region in barriers of the causeway, islands and the shoreline; the south part; and the deep north parts....
Bound entanglement in quantum phase transitions
, Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 81, Issue 4 , 2010 ; 10502947 (ISSN) ; Alipour, S ; Rezakhani, A. T ; Sharif University of Technology
2010
Abstract
We investigate quantum phase transitions in which a change in the type of entanglement from bound entanglement to either free entanglement or separability may occur. In particular, we present a theoretical method to construct a class of quantum spin-chain Hamiltonians that exhibit this type of quantum criticality. Given parameter-dependent two-site reduced density matrices (with prescribed entanglement properties), we lay out a reverse construction for a compatible pure state for the whole system, as well as a class of Hamiltonians for which this pure state is a ground state. This construction is illustrated through several examples
Application of the WEPP model to determine sources of run-off and sediment in a forested watershed
, Article Hydrological Processes ; Volume 29, Issue 4 , 2015 , Pages 481-497 ; 08856087 (ISSN) ; Meghdadi, A. R ; Sima, S ; Sharif University of Technology
John Wiley and Sons Ltd
2015
Abstract
This study investigates critical run-off and sediment production sources in a forested Kasilian watershed located in northern Iran. The Water Erosion Prediction Project (WEPP) watershed model was set up to simulate the run-off and sediment yields. WEPP was calibrated and validated against measured rainfall-run-off-sediment data. Results showed that simulated run-off and sediment yields of the watershed were in agreement with the measured data for the calibration and validation periods. While low and medium values of run-off and sediment yields were adequately simulated by the WEPP model, high run-off and sediment yield values were underestimated. Performance of the model was evaluated as...
Low-cost reciprocating electromagnetic-based micropump for high-flow rate applications
, Article Journal of Micro/ Nanolithography, MEMS, and MOEMS ; Volume 14, Issue 3 , July , 2015 ; 19325150 (ISSN) ; Salari, A ; Shafii, M. B ; Sharif University of Technology
SPIE
2015
Abstract
A reciprocating single-chamber micropump is designed and experimentally tested. The actuation technique of the pump is based on Lorentz force acting on an array of low-weight microwires placed on a flexible membrane surface. A square-wave electric current (5.6 and 7.8 A) with a low-frequency range (5.6 to 7.6 Hz) is applied through the microwires in the presence of a perpendicular magnetic field (0.08 to 0.09 T). The resultant oscillating Lorentz force causes the membrane to oscillate with the same frequency, and pushes the fluid to flow toward the outlet using a high-efficiency ball-valve. The micropump has exhibited a maximum efficiency of 2.03% with a flow rate as high as 490 μl/s and...
Investigating the rheological properties of nanofluids of water/hybrid nanostructure of spherical silica/MWCNT
, Article Thermochimica Acta ; Volume 578 , 20 February , 2014 , Pages 53-58 ; ISSN: 00406031 ; Rashidi, A ; Soleimanisalim, A. H ; Rashtchian, D ; Sharif University of Technology
2014
Abstract
Regarding the importance of rheological properties of water based drilling fluids, the effects of silica nanospheres, multiwall carbon nanotubes (MWCNTs) and two types of their hybrid, i.e. H1 (80 wt.% silica nanosphere/20 wt.% MWCNT) and H2 (50 wt.% silica nanosphere/50 wt.% MWCNT) on the viscosity and density of distilled water were investigated. According to the results, viscosity and density of the nanofluids increased with the concentration, while they were reduced by increasing the temperature. At high concentrations, the least increase in the viscosity of distilled water by adding the nanomaterials is related to H2 (8.2% increase at 1.0 wt.%). Likewise, the optimum operating...
Improvement of Aqueous Electrolyte for use in Calcium Ion Batteries
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhaad, Khatiboleslam (Supervisor) ; Askari, Masoud (Supervisor)
Abstract
Nowadays, along with the increasing development of renewable energy sources such as solar and wind, the need to use cost-effective fixed energy storage systems with cyclic stability at high rates is increasing. Due to their abundance and high safety, aqueous rechargeable calcium-ion batteries have the potential to meet the growing needs of stationary energy storage devices. In addition, they can be produced at low cost and have a higher volume capacity. However, the electrochemical stability window, which is controlled by the hydrogen production reaction on the anode and the oxygen production reaction on the cathode, severely limits the application of electrode materials in aqueous...
Synthesis of spherical silica/multiwall carbon nanotubes hybrid nanostructures and investigation of thermal conductivity of related nanofluids
, Article Thermochimica Acta ; Volume 549 , 2012 , Pages 87-94 ; 00406031 (ISSN) ; Rashidi, A ; Rashtchian, D ; Lotfi, R ; Amrollahi, A ; Sharif University of Technology
2012
Abstract
In this study, a hybrid of silica nanosphere/multiwall carbon nanotube (MWCNT) has been synthesized by wet chemical method at room temperature. The effect of MWCNTs, silica nanospheres and hybrid nanostructures (80% silica nanosphere/20% MWCNT and 50% silica nanosphere/50% MWCNT) on the thermal conductivity of distilled water has been investigated. SDBS was used as the dispersant to stabilize nanomaterials in the aqueous suspension and its concentration was 1.5 times of the concentration of nanomaterials. As results show, by increasing the concentration of nanomaterials, effective thermal conductivity of nanofluids increased. The most and the least enhancement in the effective thermal...
The Role of Quantum Coherence and Geometry on the Excitonic Energy Transfer in Photosynthetic Structures
, M.Sc. Thesis Sharif University of Technology ; Karimipour, Vahid (Supervisor) ; Rezakhani, Ali (Supervisor)
Abstract
It has been of great interest to know whether quantum effects can play an essential role in the biological processes. Considering that quantum features, such as coherence and entanglement,can be harnessed to perform quantum information processing tasks, which are believed to be hard classically, the question is whether nature has also exploited these features in order to enhance the performance of biological systems. Although the presence of warm and wet environment around the biological systems results in the rapid destruction of quantum effects, recent experiments reported the existence of quantum coherence in light-harvesting complexes of some photosynthetic systems.This coherence lasts...
Experimental investigation on laminar forced convection heat transfer of ferrofluids under an alternating magnetic field
, Article Experimental Thermal and Fluid Science ; Volume 49 , 2013 , Pages 193-200 ; 08941777 (ISSN) ; Dibaei, M. H ; Hakim Sima, A ; Shafii, M. B ; Sharif University of Technology
2013
Abstract
This research study presents an experimental investigation on forced convection heat transfer of an aqueous ferrofluid flow passing through a circular copper tube in the presence of an alternating magnetic field. The flow passes through the tube under a uniform heat flux and laminar flow conditions. The primary objective was to intensify the particle migration and disturbance of the boundary layer by utilizing the magnetic field effect on the nanoparticles for more heat transfer enhancement. Complicated convection regimes caused by interactions between magnetic nanoparticles under various conditions were studied. The process of heat transfer was examined with different volume concentrations...
A Proper Method of Upscaling Permeability data in a Typical Iranian Reservoir
, M.Sc. Thesis Sharif University of Technology ; Shadizadeh, Reza (Supervisor) ; Jonoud, Sima (Co-Supervisor)
Abstract
In this paper we have tried to mention a proper method of upscaling permeability data in a typical Iranian reservoir. Firstly a literature review is made on some common upscaling methods witch have been used so far. We introduced common upscaling methods like full tensor method, streamline method, stone method , vertical equilibrium method and also Kyte & Berry method. Additionally we have explained their advantages and also disadvantages. After selecting two upscaling methods, Kyte & Berry method and vertical equilibrium method, we applied these algorithms for upscaling of permeability data of Soroosh Oil Field. Soroosh oilfield is a heavy oil, Iranian reservoir located in Persian Gulf....
A new desalination system using a combination of heat pipe, evacuated tube and parabolic through collector
, Article Energy Conversion and Management ; Volume 99 , July , 2015 , Pages 141-150 ; 01968904 (ISSN) ; Mamouri, S. J ; Shafii, M. B ; Hakim Sima, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
The solar collectors have been commonly used in desalination systems. Recent investigations show that the use of a linear parabolic through collector in solar stills can improve the efficiency of a desalination system. In this work, a combination of a heat pipe and a twin-glass evacuated tube collector is utilized with a parabolic through collector. Results show that the rate of production and efficiency can reach to 0.27 kg/(m2 h) and 22.1% when aluminum conducting foils are used in the space between the heat pipe and the twin-glass evacuated tube collector to transfer heat from the tube collector to the heat pipe. When oil is used as a medium for the transfer of heat, filling the space...
Preparation of Nanofluid by Using Hybrid Nanostructures and Investigation of Thermal and Rheological Properties and Using it in the Petroleum Fluids
, M.Sc. Thesis Sharif University of Technology ; Rashtchian , Davood (Supervisor) ; Rashidi, Alimorad (Supervisor) ; Lotfi, Roghayeh (Co-Advisor)
Abstract
In this study, thermal and rheological properties of nanofluids of water/carbon nanotubes, water/spherical silica nanoparticles and water/hybrid nanoparticles (hybrid of carbon nanotubes and spherical silica nanoparticles) have been investigated. To do so, carbon nanotubes have been synthesized by CCVD process and spherical silica nanoparticles and hybrid nanoparticles by wet chemical method. After synthesis of nanomaterials, nanofluids have been prepared by using SDBS as a dispersant with the concentration of 1.5 times of concentration of nanomaterials and then thermal conductivity, kinematic viscosity, dynamic viscosity and density of nanofluids have been investigated. As the results show,...