A new dynamic optimal m2m rf interface setting in relay selection algorithm (dorsa) for iot applications

, Article IEEE Access ; Volume 10 , 2022 , Pages 5327-5342 ; 21693536 (ISSN) Ghasri, M. A. G ; Hemmatyar, A. M. A ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2022

Abstract

Machine-to-Machine (M2M) communication is an important type of communication in the Internet-of-Things (IoT). How to send data in these high-density communications using relay selection can help improve the performance of this type of communication in various applications. In addition, the possibility of simultaneous use of different Radio Frequency (RF) interfaces helps to use the spectrum more efficiently. In this work, we try to further use machine communication RF equipment and improve the average data rate of networks in some applications such as the IoT, which have their own bandwidth requirements. Therefore, we provide an optimization algorithm for relay selection as well as the...

On The Interaction Between Location-Allocation of Population-Employment and Transportation Based on Living Costs

, M.Sc. Thesis Sharif University of Technology Ghasri, Milad (Author) ; Poorzahedy, Hossein (Supervisor)

Abstract

This study is an endeavor to model the interaction between transportation and land use, as a constituent of a joint land use-network design problem defined in the context of transit oriented development (TOD). Population and employment follow a Garin-Lowry model; the endogenously determined transportation demand is administered by a joint mode choice-assignment model; and mode choice is governed by a logit model. Equilibrium of population choice of place of residence, employment choice of place of retailing, and passenger choice of mode and path, are all governed by a maximum utility principle. An algorithm is devised to reach these equilibrium states by an evolutionary process, whose engine...

Active Noise Cancellation Using System Identification and Control Based on Neural Network

, M.Sc. Thesis Sharif University of Technology Ghasri, Homa (Author) ; Haj Sadeghi, Khosro (Supervisor)

Abstract

This thesis presents a new approach to feedback active noise cancellation. The problem of Reducing the noise level in the environment has been the focus of research over the years. Active Noise Cancellation (ANC) is one such approach that has been proposed to eliminate Noise. ANC refers to an electro acoustic approach of canceling acoustic disturbance to Produce a quieter environment. The basic principle of ANC is to introduce a canceling “anti Noise” signal that has the same amplitude but the exact opposite phase, thus resulting in Reducing the remainder noise signal. We use neural networks based on system identification And predict control to cancel acoustic noise. Canceling acoustic...

Enhancement of the MAC Layer of Mobile Broadband Wireless Access Network

, M.Sc. Thesis Sharif University of Technology Gholi Ghasri, Monireh Allah (Author) ; Ajorloo, Hossein (Supervisor)

Abstract

Mobile Broadband Wireless Access technologies provide mobile users with broadband services, for example music downloading, online games and etc. IEEE 802.20 standard is one of the Mobile Broadband Wireless Access technologies , which has been published to support mobile users with high vehicular speed up to 250(km/h). The issue studied in this research is enhancement of MAC layer in IEEE 802.20 standard.
By having this intention in mind we firstly developed a simulator for IEEE 802.20 MAC layer implementation , then we tried implementing 3 different approaches for connecting mobile users to a new network in order to analyze their performance. Then we provided a method for decreasing...

Experimental investigation of water alternating CH4-CO2 mixture gas injection to light oil reservoirs

, Article 74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources, 4 June 2012 through 7 June 2012 ; June , 2012 , Pages 3919-3923 ; 9781629937908 (ISBN) Ghazanfari, M. H. G. H ; Alizadeh, A

European Association of Geoscientists and Engineers, EAGE 2012

Abstract

In this work effect of composition changes of injection gas, CH4 + CO2, on the performance of immiscible WAG injection in light oil, 41 oAPI, which has been rarely attended in the available literature is investigated. Presence of CO2 helps to reduce the MMP of CH4 significantly. Core flood experiments are conducted at reservoir conditions and fixed flow rate of 0.5cc/min on a sandstone sample with the brine concentration of 5000 ppm, and the influence of injection gas composition as well as WAG ratio on oil recovery is investigated. Different mole percents of methane in mixture, 0%, to 100% are examined, and the tests continued to ten alternate cycles with a slug size of 0.1 pore volumes and...

Mechanistic evaluation of cationic dyes adsorption onto low-cost calcinated aerated autoclaved concrete wastes

, Article International Journal of Environmental Science and Technology ; 2021 ; 17351472 (ISSN) Gheibi, M ; Eftekhari, M ; Tabrizi, M. G ; Fathollahi Fard, A. M ; Tian, G ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2021

Abstract

Application of construction and demolition (C&D) wastes were considered as sustainable development goals (SDGs) for maintaining raw materials. Also, lightweight concretes such as aerated autoclaved concrete (AAC) were used for partitioning spaces in the building industry. Moreover, the waste products of the mentioned materials were increased due to the rise of old construction demolitions. This study contributes a calcinated aerated autoclaved concrete (CAAC) which is efficient, powerful, highly rapid, non-expensive and novel adsorbent for the removal of cationic dyes including malachite green (MG), methyl violet (MV) and methylene blue (MB) form water samples. The impacts of different...

Mechanistic evaluation of cationic dyes adsorption onto low-cost calcinated aerated autoclaved concrete wastes

, Article International Journal of Environmental Science and Technology ; Volume 19, Issue 7 , 2022 , Pages 6429-6444 ; 17351472 (ISSN) Gheibi, M ; Eftekhari, M ; Tabrizi, M. G ; Fathollahi Fard, A. M ; Tian, G ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2022

Abstract

Application of construction and demolition (C&D) wastes were considered as sustainable development goals (SDGs) for maintaining raw materials. Also, lightweight concretes such as aerated autoclaved concrete (AAC) were used for partitioning spaces in the building industry. Moreover, the waste products of the mentioned materials were increased due to the rise of old construction demolitions. This study contributes a calcinated aerated autoclaved concrete (CAAC) which is efficient, powerful, highly rapid, non-expensive and novel adsorbent for the removal of cationic dyes including malachite green (MG), methyl violet (MV) and methylene blue (MB) form water samples. The impacts of different...

The propagation of laser light in skin by Monte Carlo-diffusion method: A fast and accurate method to simulate photon migration in biological tissues

, Article Journal of Lasers in Medical Sciences ; Volume 2, Issue 3 , 2011 , Pages 109-114 ; 20089783 (ISSN) Golshan, M. A ; Tarei, M. G ; Ansari, M. A ; Amjadi, A ; Sharif University of Technology

2011

Abstract

Introduction: Due to the importance of laser light penetration and propagation in biological tissues, many researchers have proposed several numerical methods such as Monte Carlo, finite element and green function methods. Among them, the Monte Carlo method is an accurate method which can be applied for different tissues. However, because of its statistical nature, Monte Carlo simulation requires a large number of photon pockets to be traced, so it is computationally expensive and time-consuming. Although other numerical methods based on the diffusion method are fast, they have two important limitations: first, they are not valid near the bounder of sample and source, and second, their...

Modified Chitosan. 2. H-chitoPAN, a novel pH-responsive superabsorbent hydrogel [electronic resource]

, Article Journal of Applied Polymer Science ; Volume 90, Issue 11, pages 3115–3121, 9 December 2003 Pourjavadi, A. (Ali) ; Mahdavinia, G. R ; Zohuriaan-Mehr, M. J

Abstract

Chitosan was modified with polyacrylonitrile (PAN) through ceric-initiated graft copolymerization. The chitosan-g-PAN product was saponified using sodium hydroxide aqueous solution to prepare a novel superabsorbent hydrogel, H-chitoPAN. Duration of completing the saponification reaction as well as the water absorbency capacity of the hydrogel was decreased with increasing the alkaline concentration. Either chitosan-g-PAN or H-chitoPAN was characterized by FTIR spectroscopy and DSC, TGA, and DTG thermal methods. According to FTIR, all the nitrile groups were converted to carboxylate and carboxamide groups. Both modified chitosans exhibited enhanced thermal stability over chitosan. The...

Nonlinear displacement-based and hybrid-mixed quadrilaterals for three-dimensional stress analysis through sampling surfaces formulation

, Article Thin-Walled Structures ; Volume 155 , October , 2020 Kulikov, G. M ; Bohlooly, M ; Plotnikova, S. V ; Kouchakzadeh, M. A ; Glebov, A. O

Elsevier Ltd 2020

Abstract

The finite deformation displacement-based and hybrid-mixed four-node quadrilateral elements using the sampling surfaces (SaS) technique are developed. The SaS formulation is based on choosing inside the plate N not equally spaced SaS parallel to the middle surface to introduce the displacements of these surfaces as basic plate unknowns. Such choice of unknowns with the consequent use of Lagrange polynomials of degree N–1 in the thickness direction permits the presentation of the plate formulation in a very compact form. The SaS are located at only Chebyshev polynomial nodes that allows one to minimize uniformly the error due to the Lagrange interpolation. To circumvent shear locking and have...

Performance of the Pre/Post-FFT smart antenna methods for OFDM-based wireless LANs in an indoor channel with interference

, Article 2006 IEEE International Conference on Communications, ICC 2006, Istanbul, 11 July 2006 through 15 July 2006 ; Volume 9 , 2006 , Pages 4291-4296 ; 05361486 (ISSN); 1424403553 (ISBN); 9781424403554 (ISBN) Alihemmati, R ; Jedari, E ; Enayati, A. R ; Shishegar, A. A ; Roozbahani, M. G ; Dadashzadeh, G ; Sharif University of Technology

2006

Abstract

The performance of OFDM-based Wireless Local Area Networks (WLANs) is investigated by employing different smart antenna techniques at the receiver. The use of multiple antennas at the Access Point (AP) receiver in IEEE802.11a standard-compliant Single Input Multiple Output (SIMO) configuration, improves the physical layer performance in different channel scenarios and interference that may arise from other stations sharing the same frequency band. For this purpose, a comparative study of smart antenna architectures for IEEE802.11a WLAN system using pre-FFT and post-FFT array processing techniques is presented. Simulations are performed on a new model for IEEE802.11a system using a...

An efficient approach to monocular depth estimation for autonomous vehicle perception systems

, Article Sustainability (Switzerland) ; Volume 15, Issue 11 , 2023 ; 20711050 (ISSN) Afshar, M. F ; Shirmohammadi, Z ; Ghahramani, S. A. A. G ; Noorparvar, A ; Hemmatyar, A. M. A ; Sharif University of Technology

MDPI 2023

Abstract

Depth estimation is critical for autonomous vehicles (AVs) to perceive their surrounding environment. However, the majority of current approaches rely on costly sensors, making wide-scale deployment or integration with present-day transportation difficult. This issue highlights the camera as the most affordable and readily available sensor for AVs. To overcome this limitation, this paper uses monocular depth estimation as a low-cost, data-driven strategy for approximating depth from an RGB image. To achieve low complexity, we approximate the distance of vehicles within the frontal view in two stages: firstly, the YOLOv7 algorithm is utilized to detect vehicles and their front and rear...

Mechanical and microstructural properties of cement paste incorporating nano silica particles with various specific surface areas

, Article Key Engineering Materials, 8 July 2010 through 9 July 2010 ; Volume 478 , July , 2011 , Pages 19-24 ; 10139826 (ISSN) ; 9783037851357 (ISBN) Khaloo, A. R ; Vayghan, A. G ; Bolhasani, M ; Sharif University of Technology

2011

Abstract

In this study, the effect of agglomeration and non-uniform dispersion of silica particles on the mechanical and microstructural properties of cement paste incorporating silica fume and nanosilica (NS) with various specific surface areas (SSA) is experimentally investigated. The SSA and replacement percent of silica particles were considered as test variables and four series of mixes were made including one set of mixes for silica fume with a SSA of 20 m2/g and three sets of mixes for three different types of NS with SSA equal to 90, 200 and 380 m2/g. In each series of mix designs three different cement replacement percents of 1.5%, 3% and 5% were applied. The results indicate that as the SSA...

Calculation of equilibrium and transport properties using modified hard-core potential models

, Article Chemical Physics ; Volume 326, Issue 2-3 , 2006 , Pages 527-534 ; 03010104 (ISSN) Parsafar, G. A ; Khanpour, M ; Mohammadi, A. A ; Sharif University of Technology

2006

Abstract

We present in this paper a new method of modifying hard-core potentials to correctly predict the equilibrium and non-equilibrium properties of real fluids at low densities (specifically when ρ ≤ B/C where ρ is density, and B and C are the second and third virial coefficients) only by one set of potential parameters. Because the molecular diameter becomes smaller when temperature increases, we introduced a new expression for the variation of molecular diameter with temperature that incorporates this effect. The temperature dependence of the diameter was used in both Sutherland (ST) and square-well (SW) potential models to modify the second virial coefficient. Then we have shown that the...

Structural, magnetic and dielectric properties of Dy-Co substituted Sr-Ba-Mg-based magnetic oxides

, Article Applied Physics A: Materials Science and Processing ; Volume 127, Issue 11 , 2021 ; 09478396 (ISSN) Lodhi, M. Y ; Khan, M. A ; Majeed, A ; Akhtar, M. N ; Ahmad, M ; Hussain, A ; Islam, M ; Nasar, G ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2021

Abstract

In present research six samples of nano X-type hexagonal ferrites with general formula SrBaMg2-xCoxDyyFe28-yO46 (x = 0–1; y = 0–0.1 with step size of 0.2 and 0.02, respectively) were synthesized by sol–gel technique. The temperature required for the phase formation of these materials was estimated using thermogravimetric analysis. X-ray diffraction patterns revealed the pure phase of the prepared materials up to the doping concentration of x = 0.4, y = 0.04 along with the second phase for higher doping concentration. The secondary phase appeared due to the solubility limit of higher ionic radius Dy3+ ions into the hexagonal lattice. The mean crystalline size decreased from 29 to 18 nm while...

Forensic detection of image manipulation using the zernike moments and pixel-pair histogram

, Article IET Image Processing ; Volume 7, Issue 9 , December , 2013 , Pages 817-828 ; 17519659 (ISSN) Shabanifard, M ; Shayesteh, M. G ; Akhaee, M. A ; Sharif University of Technology

2013

Abstract

Integrity verification or forgery detection of an image is a difficult procedure, since the forgeries use various transformations to create an altered image. Pixel mapping transforms, such as contrast enhancement, histogram equalisation, gamma correction and so on, are the most popular methods to improve the objective property of an altered image. In addition, fabricators add Gaussian noise to the altered image in order to remove the statistical traces produced because of pixel mapping transforms. A new method is introduced to detect and classify four various categories including original, contrast modified, histogram-equalised and noisy images. In the proposed method, the absolute value of...

Steganalysis of JPEG images using enhanced neighbouring joint density features

, Article IET Image Processing ; Volume 9, Issue 7 , 2015 , Pages 545-552 ; 17519659 (ISSN) Karimi, H ; Shayesteh, M. G ; Akhaee, M. A ; Sharif University of Technology

Institution of Engineering and Technology 2015

Abstract

In this study, a blind steganalysis approach which accurately discloses low rate data hiding schemes is proposed. The absolute values of neighbouring joint density (absNJ) are used for feature extraction. In this way, the intra- and inter-block situations are employed providing a variety of different features. Aside from the absolute values of discrete cosine transform (DCT) coefficients, the differential DCT coefficients are also exploited to extract the features. Moreover, the absNJ features will be extended and used over differential DCT coefficients. It is shown that applying the Pth power of the DCT coefficients instead of their first power gains more discriminative features. Then,...

The effect of shot peening on fatigue life of welded tubular joint in offshore structure

, Article Materials and Design ; Volume 36 , 2012 , Pages 250-257 ; 02641275 (ISSN) Habibi, N ; H-Gangaraj, S. M ; Farrahi, G. H ; Majzoobi, G. H ; Mahmoudi, A. H ; Daghigh, M ; Yari, A ; Moridi, A ; Sharif University of Technology

2012

Abstract

An offshore structure is exposed to environmental loading and cyclic stress variations throughout its life. This would result in the possibility of fatigue cracking in its members. Cracks in these structures usually initiate around welded areas, then grow progressively from the heat-affected zone to base metal through the thickness of the tubular members. Therefore, fatigue life improvement of offshore structures is of great importance. In this paper, structural analysis of an offshore platform is carried out and the critical joint is specified. The welding process is simulated and the residual stresses due to the welding are determined. Experimental residual stress measurement is carried...

Optimization of catalytic activity of sulfated titania for efficient synthesis of isoamyl acetate by response surface methodology

, Article Monatshefte fur Chemie ; Volume 146, Issue 12 , December , 2015 , Pages 1949-1957 ; 00269247 (ISSN) Afshar, S ; Sadehvand, M ; Azad, A ; Dekamin, M. G ; Jalali Heravi, M ; Mollahosseini, A ; Amani, M ; Tadjarodi, A ; Sharif University of Technology

Springer-Verlag Wien 2015

Abstract

TiO2 nanoparticles were synthesized by sol-gel method using titanium tetraisopropoxide. Sulfate ions were introduced on the titania by impregnation method using sulfuric acid as precursor of sulfate ions. Fourier transform infrared and energy-dispersive X-ray spectroscopy, X-ray fluorescence as well as X-ray diffraction, scanning electron microscopy, and BET methods were used for the characterization of the obtained nanoparticles. The esterification of isoamyl alcohol with acetic acid was investigated to prove the catalytic activity of the TiO2 nanoparticles under solvent-free conditions. Response surface methodology was applied to optimize the effect of some parameters such as the molar...

Mechanochromic and thermally activated delayed fluorescence dyes obtained from D–A–D′ type, consisted of xanthen and carbazole derivatives as an emitter layer in organic light emitting diodes

, Article Chemical Engineering Journal ; Volume 430 , 2022 ; 13858947 (ISSN) Nasiri, S ; Dashti, A ; Hosseinnezhad, M ; Rabiei, M ; Palevicius, A ; Doustmohammadi, A ; Janusas, G ; Sharif University of Technology

Elsevier B.V 2022

Abstract

In this study, we designed, engineered and investigated two new thermally activated delayed fluorescence (TADF) dyes obtained from D–A–D′ type, consisted of 2-(9H-carbazol-9-yl)-3-(3-methoxy-9H-carbazol-9-yl)-9H-xanthen and 2-(3,6-di-tert-butyl-9H-carbazol-9-yl)-3-(3-methoxy -9H-carbazol-9-yl)-9H-xanthen. In these dyes, xanthen derivative and carbazole derivatives have played important roles as an acceptor and two unsymmetrical donor units. In addition, the photophysical properties of these dyes were evaluated by the UV–VIS absorption, photoluminescence spectroscopy and photoluminescence decay lifetime analysis in solution, initial dye, non-doped and doped solid state (neat–film) at...