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Weak visibility queries in simple polygons
, Article Proceedings of the 23rd Annual Canadian Conference on Computational Geometry, CCCG 2011 ; 2011 ; Ghodsi, M ; Sharif University of Technology
Abstract
In this paper, we consider the problem of computing the weak visibility (WV ) of a query line segment in- side a simple polygon. Our algorithm first preprocesses the polygon and creates data structures from which any WV query is answered efficiently in an output sensitive manner. In our solution, the preprocessing is performed in time O(n3 log n) and the size of the constructed data structure is O(n3). It is then possible to report the WV polygon of any query line segment in time O(log n+k), where k is the size of the output. Our algorithm im- proves the current results for this problem
Numerical investigation on the temperature dependence of the cylindrical-gate-all-arounD Si-NW-FET
, Article Modern Physics Letters B ; Volume 25, Issue 29 , 2011 , Pages 2269-2278 ; 02179849 (ISSN) ; Saghafi, K ; Faez, R ; Moravvej-Farshi, M. K ; Sharif University of Technology
2011
Abstract
We report the results of our numerical investigation on the temperature dependence of the characteristics of the cylindrical gate-all-around Si nanowire field effect transistor (Si-NW-FET). Assuming the effect of temperature on the energy band structure of Si just like the effect of strain, we simulate the transistor characteristics at various temperatures (50 K ≤ T ≤ 300 K). In this investigation, we demonstrate the temperature dependence of the transistor sub-threshold swing and the threshold voltage are both linear functions of the temperature, represented by 61.5 × (T/300) + 63.4 (mV/decade) and 220140 × (T/300-1) (mV). By calculating the IDS - T characteristics for VDS = 0.4 V and...
A new approach to model sensitivity of graphene-based gas sensors
, Article Semiconductor Science and Technology ; Volume 30, Issue 4 , March , 2015 ; 02681242 (ISSN) ; Ismail, R ; Naraghi, B ; Taheri Abed, S ; Kavosi, D ; Fotovatikhah, F ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
Carbon-based sensors are attractive because of their excellent sensing capability. In this paper, we propose a new approach to analytically model the sensitivity of these devices based on graphene. The model relies on the surface potential and current of the device. For the first time, we included ionization in the modelling and examined the importance of this effect. In order to validate the model, the results are compared with experimental data from a fabricated device
A new control strategy for hybrid electric vehicles equipped with a continuously variable transmission
, Article Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering ; Volume 230, Issue 6 , Aug , 2015 , Pages 803-816 ; 09544070 (ISSN) ; Saadat Foumani, M ; Lashgarian Azad, N ; Rostami, P ; Sharif University of Technology
SAGE Publications Ltd
2015
Abstract
The electric assist control strategy is one of the well-known methods for managing the power sources of hybrid electric vehicles. Because of the dependence of the electric assist control strategy approach on its parameters, optimization of this strategy can improve its performance, which results in lower fuel consumption and lower emission levels. However, one of the main concerns about optimization of this strategy is its dependence on the driving behaviour. This paper aims to propose a new control strategy based on the electric assist control strategy with a smaller number of control parameters and less dependence on the driving behaviour. This strategy is usable only for vehicles equipped...
Defect study of TiO2 nanorods grown by a hydrothermal method through photoluminescence spectroscopy
, Article Journal of Luminescence ; Volume 157 , January , 2015 , Pages 235-242 ; 00222313 (ISSN) ; Shogh, S ; Iraji Zad, A ; Sharif University of Technology
Elsevier
2015
Abstract
This paper describes the photoluminescence study of titanium dioxide (TiO2) nanorods grown by a hydrothermal synthesis method on the surface of fluorine doped tin oxide (FTO) coated glass. The effects of growth conditions including: reaction time, precursor concentration and adding NaCl to hydrothermal solution on the structural and optical properties of productions are examined by using SEM, XRD, TEM and room temperature photoluminescence measurements. Also, the performance of the TiO2 nanorods as a photoanode of dye sensitized solar cells is investigated. The different excitation energies and intensities are chosen to verify the discrete electronic state of radiative recombination centers...
A review of 2D-based counter electrodes applied in solar-assisted devices
, Article Coordination Chemistry Reviews ; Volume 324 , 2016 , Pages 54-81 ; 00108545 (ISSN) ; Naseri, N ; Beke, S ; Sharif University of Technology
Elsevier
2016
Abstract
The alarming energy and environmental crisis of our modern era necessitates scientists to propose alternatives to replace the scarce and harmful fossil fuels. The Sun, as a free, and abundant clean energy resource, presents a motivation for researchers to convert the sunlight to electrical power and store the H2 as an energy carrier by developing solar cells as well as water splitting devices, respectively. One of the fundamental parts of a solar energy convertor (solar cell/photoelectrochemical device), where the reduction reaction occurs, is the counter electrode (CE); the CE is commonly based on rare Pt. It is critical to substitute costly CEs with efficient, low-cost replacements, which...
Molecular engineering of bithiazole-based organic dyes with different electron-rich linkers toward highly efficient dye-sensitized solar cells
, Article Journal of Photochemistry and Photobiology A: Chemistry ; Volume 349 , 2017 , Pages 171-182 ; 10106030 (ISSN) ; Hadipour, N. L ; Parsafar, G ; Sharif University of Technology
Abstract
A series of bithiazole-based dye sensitizers have been designed by employing various electron-rich moieties as π-spacer, which are based on the reported experimentally synthesized dye T-BT, to shed a light on the impact of both the nature and position of electron-rich moiety on the efficiency of dyes in DSSCs. To evaluate the efficiency of these dyes, various key parameters associated with overall conversion efficiency (η), including electronic and optical properties of free dyes are calculated, based on the computational methods. Besides, the dye/TiO2 structures have been taken into account to investigate the interfacial features of the dye sensitizers adsorbed on TiO2 semiconductor and...
Luminescent Spectral Conversion to Improve the Performance of Dye-Sensitized Solar Cells
, Article ChemPhysChem ; Volume 18, Issue 23 , 2017 , Pages 3292-3308 ; 14394235 (ISSN) ; Taghavinia, N ; Wei Guang Diau, E ; Sharif University of Technology
Abstract
Relative to the broadband solar spectrum, a narrow range of spectral absorption of photovoltaic (PV) devices is considered an important determinant that the efficiency of light harvesting of these devices is less than unity. Having the narrowest spectral response to solar radiation among all PV devices, dye-sensitized solar cells (DSSCs) suffer severely from this loss. Luminescent spectral conversion provides a mechanism to manipulate and to adapt the incident solar spectrum by converting, through photoluminescence, the energies of solar photons into those that are more effectively captured by a PV device. This mechanism is particularly helpful for DSSCs because there is much flexibility in...
Dye-sensitized solar cells based on TiO2 particulate gels: Impact of gel formation mechanism on photovoltaic performance
, Article Journal of Photochemistry and Photobiology A: Chemistry ; Volume 338 , 2017 , Pages 104-114 ; 10106030 (ISSN) ; Mohammadi, M. R ; Sharif University of Technology
Elsevier B.V
2017
Abstract
In this work the influence of different particulate gels on morphology and photoelectric performance of TiO2 dye-sensitized solar cells (DSCs) is studied. Two coagulant and flocculant agents are used to convert a TiO2 particulate sol into the gels using double layer compression and charge neutralization mechanisms. One more TiO2 particulate gel is also prepared by changing the pH of the sol using acid: alkoxide molar ratio higher than the critical ratio to obtain an unstable sol. Based on X-ray diffraction (XRD) analysis, the films contain primary nanoparticles with average crystallite size of 13–15 nm. Field emission scanning electron microscopy (FE-SEM) images show uniform, nanostructured...
Sensitivity of the population of states to the value of q and legitimate range of q in tsallis statistics
, Article Journal of the Iranian Chemical Society ; Volume 6, Issue 2 , 2009 , Pages 341-344 ; 1735207X (ISSN) ; Parsafar, G ; Sharif University of Technology
2009
Abstract
In the framework of the Tsallis statistical mechanics, we study the change of the population of states when the parameter q is varied, for some model systems; the results show that the difference between predictions of the Boltzmann-Gibbs and Tsallis statistics can be much smaller than the precision of any existing experiment. Also, the relation between privilege of rare and frequent events and the value of q is restudied. It is shown that positive q privilege frequent and negative q privilege rare events. Finally, the convergence criteria of the partition function of some simple model systems, in the framework of Tsallis statistical mechanics, is studied. Based on this study, we conjecture...
PM dispersion during stable winter episodes in tehran and effect of governmental emission regulations
, Article Atmospheric Pollution Research ; Volume 11, Issue 8 , 2020 , Pages 1316-1328 ; Arhami, M ; Azoji, H ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Tehran is one of the most polluted cities in Middle East which during winter extremely high levels of particulate matter (PM) occurs due to frequent stable weather episodes. This study aims to identify major sources of PM and quantify effectiveness of possible control measures and strategies during these episodes. The Brute Force Method (BFM) with Community Multiscale Air Quality model (CMAQ) was implemented to estimate the contributions from major local anthropogenic sources on PM levels. In this regard several scenarios including the effect of existing governmental policies and regulations to upgrade vehicles emission standards were investigated. Emission due to the existing condition and...
A new framework for advancement of power management strategies in hybrid electric vehicles
, Article International Journal of Engineering Transactions C: Aspects ; Volume 33, Issue 3 , 2020 , Pages 468-476 ; Saadat Foumani, M ; Lashgarian Azad, N ; Sharif University of Technology
Materials and Energy Research Center
2020
Abstract
Power management strategies play a key role in the design process of hybrid electric vehicles. Electric Assist Control Strategy (EACS) is one of the popular power management strategies for hybrid electric vehicles (HEVs). The present investigation proposes a new framework to advance the EACS. Dynamic Programming method is applied to an HEV model in several drive cycles, and as a result, some optimal operating regions are found. The obtained regions are almost distinct, and consequently, some threshold lines can be defined to separate them. The obtained threshold lines are used to eliminate some parameters of the EACS to reduce its sensitivity to the driving behavior. It is shown that by...
Fluctuation bounds for the max-weight policy with applications to state space collapse
, Article Stochastic Systems ; Volume 10, Issue 3 , 2020 , Pages 223-250 ; Tsitsiklis, J. N ; Jamaloddin Golestani, S ; Sharif University of Technology
INFORMS Inst.for Operations Res.and the Management Sciences
2020
Abstract
We consider a multihop switched network operating under a max-weight scheduling policy and show that the distance between the queue length process and a fluid solution remains bounded by a constant multiple of the deviation of the cumulative arrival process from its average. We then exploit this result to prove matching upper and lower bounds for the time scale over which additive state space collapse (SSC) takes place. This implies, as two special cases, an additive SSC result in diffusion scaling under nonMarkovian arrivals and, for the case of independent and identically distributed arrivals, an additive SSC result over an exponential time scale. © 2020 The Author(s)
Extended-gate field-effect transistor based sensor for detection of hyoscine n-butyl bromide in its pharmaceutical formulation
, Article Analytical and Bioanalytical Electrochemistry ; Volume 12, Issue 2 , 2020 , Pages 238-249 ; Mirzaie, S. I ; Fardmanesh, M ; Norouzi, P ; Sharif University of Technology
Center of Excellence in Electrochemistry, Univ. of Tehran
2020
Abstract
A novel recognition method for selective determination of the hyoscine N-Butyl bromide (HBB), an antispasmodic agent for smooth muscles, was devised using extended gate field-effect transistor (EG-FET) as transducing unit. For this purpose a PVC membrane, containing hyoscine n-butyl-tetraphenyl borate ion-pair as recognition component, was coated on Ag/AgCl wire, which was connected to the extended metal gate. In optimal conditions, the linear range for HBB was 10-8-10-5 molL−1 with limit of detection 1.7×10-9 molL-1. The proposed sensor was applied in real sample, it showed fast response with high accuracy, and therefore it could be used as HPLC detector in the pharmaceutical samples in...
Enhanced CO sensitivity and selectivity of gold nanoparticles-doped SnO2 sensor in presence of propane and methane
, Article Sensors and Actuators, B: Chemical ; Volume 133, Issue 1 , 26 July , 2008 , Pages 352-356 ; 09254005 (ISSN) ; Khodadadi, A ; Kazemeini, M ; Mortazavi, Y ; Sharif University of Technology
2008
Abstract
We report the effect of gold nanoparticles on the sensitivity and selectivity of SnO2-based sensors for detection of CO in the presence of methane and C3H8, a model compound representing liquid petroleum gas (LPG). 1.0 wt% Au/SnO2 powder was prepared by a co-precipitation method. The powder formed was washed, dried at 150 °C, and calcined at 300 °C for 3 h. The BET surface area of SnO2 and Au/SnO2 was measured to be 210 and 110 m2/g, corresponding to 4 and 7.5 nm loose spherical particles, respectively. Responses of the Au/SnO2 and SnO2 sensors to 40-1000 ppm CO, 0.2-1.0% C3H8 and 1.0-3.0% CH4 were studied at 170-300 °C in an automated gas sensing system. In this temperature range, the...
Evaluation of imperial performance characteristic of turbocharger turbine and compressor
, Article 9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference Proceedings, San Francisco, CA, 5 June 2006 through 8 June 2006 ; Volume 2 , 2006 , Pages 1019-1028 ; 1563478153 (ISBN); 9781563478154 (ISBN) ; Hajilouy, A ; Shahhosseini, M. R ; Sharif University of Technology
2006
Abstract
Performance characteristics of turbocharger turbine and compressor such as efficiency, mass parameter and power are determined experimentally at turbocharger laboratory. Accurate determination of the performance map is significant for manufacturers as well as end users. To this end accurate measurement of test parameters such as temperature, pressure, and speed are required. In this paper an analytic method to predict the measurement uncertainties in turbocharger laboratory, is described. Furthermore the effect of each test parameter on the performance uncertainty is considered. Test parameters that have the most significant influence on the performance uncertainties are identified....
Partially hydrolyzed kappa carrageenan - polyacrylonitrile as a novel biopolymer-based superabsorbent hydrogel: synthesis, characterization, and swelling behaviors
, Article Polymer Engineering and Science ; Volume 46, Issue 12 , 2006 , Pages 1778-1786 ; 00323888 (ISSN) ; Pourjavadi, A ; Sharif University of Technology
2006
Abstract
In this paper, synthesis and swelling behavior of a novel superabsorbent hydrogel based on kappa carrageenan (κC) and polyacrylonitrile (PAN) was investigated. To achieve partially hydrolyzed κC-PAN hydrogel, physical mixture of κC and PAN was hydrolyzed by NaOH solution. During alkaline hydrolysis, the nitrile groups of PAN are converted to a mixture of hydrophilic carboxamide and carboxylate groups follow by in situ crosslinking of the grafted PAN chains. The reaction variables affecting on the swelling capacity of the hydrogel were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. Under the optimized conditions concluded, super swelling hydrogel...
Use of a hybrid wind—solar—diesel—battery energy system to power buildings in remote areas: A case study
, Article Sustainability (Switzerland) ; Volume 13, Issue 16 , 2021 ; 20711050 (ISSN) ; Hosseini Dehshiri, S. S ; Hosseini Dehshiri, S. J ; Mostafaeipour, A ; Issakhov, A ; Techato, K ; Sharif University of Technology
MDPI
2021
Abstract
The emerging environmental consequences of overdependence on fossil fuels have pushed many countries to invest in clean and renewable sources of power. Countries like Iran where these sources can be found in abundance can take advantage of this potential to reduce their dependence on fossil fuels. This study investigated the feasibility of the standalone use of a hybrid renewable energy system (HRES) to power buildings in the Bostegan village in the Hormozgan province of Iran. Technical, economic, and environmental assessments were performed with the help of the Hybrid Optimization of Multiple Energy Resources (HOMER) software, and the optimal configuration for the system components was...
Use of a hybrid wind—solar—diesel—battery energy system to power buildings in remote areas: a case study
, Article Sustainability (Switzerland) ; Volume 13, Issue 16 , 2021 ; 20711050 (ISSN) ; Hosseini Dehshiri, S ; Hosseini Dehshiri, J ; Mostafaeipour, A ; Issakhov, A ; Techato, K ; Sharif University of Technology
MDPI
2021
Abstract
The emerging environmental consequences of overdependence on fossil fuels have pushed many countries to invest in clean and renewable sources of power. Countries like Iran where these sources can be found in abundance can take advantage of this potential to reduce their dependence on fossil fuels. This study investigated the feasibility of the standalone use of a hybrid renewable energy system (HRES) to power buildings in the Bostegan village in the Hormozgan province of Iran. Technical, economic, and environmental assessments were performed with the help of the Hybrid Optimization of Multiple Energy Resources (HOMER) software, and the optimal configuration for the system components was...
Enhanced light harvesting with a reflective luminescent down-shifting layer for dye-sensitized solar cells
, Article ACS Applied Materials and Interfaces ; Volume 5, Issue 12 , 2013 , Pages 5397-5402 ; 19448244 (ISSN) ; Huang, W. K ; Tsai, C. M ; Chen, T. M ; Taghavinia, N ; Diau, E. W. G ; Sharif University of Technology
2013
Abstract
For a dye-sensitized solar cell with a near-infrared squaraine (SQ1) sensitizer, the photovoltaic performance was enhanced remarkably with a reflective luminescent down-shifting (R-LDS) layer to increase the light-harvesting efficiency at the wavelength region 400-550 nm where the SQ1 dye has weak absorption. Relative enhancements greater than 200% in IPCE near 500 nm and 40-54% in JSC were achieved with red phosphor CaAlSiN 3:Eu2+ as the LDS material, attaining 5.0 and 4.8% overall efficiencies of power conversion for the R-LDS layer coated on the counter electrode (front illumination) and working electrode (back illumination), respectively