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Design and Implementation of a X Band Front-end Receiver in GaAs Technology
, M.Sc. Thesis Sharif University of Technology ; Medi, Ali (Supervisor)
Abstract
This thesis begins in an attempt to design an X band front-end receiver in GaAs pHEMT technology, suitable for microwave circuits which should be high frequency, low noise, high gain, as well as high power handling and should have stable characteristics at large number of productions. The front-end receiver consists of three blocks, namely limiter, low noise amplifier, and mixer, which are designed in ISDL group previously. The measurement result of the fabricated low noise amplifier was satisfactory, since it was close to its simulation result. However, due to the drawbacks of modeling the switching behavior of devices, the results of the two other blocks, i.e., limiter and mixer – which...
Resource Allocation in mmWave Massive MIMO Transmission in the Presence of Neighboring Cells Interference
, M.Sc. Thesis Sharif University of Technology ; Nasiri Kenari, Masoumeh (Supervisor)
Abstract
In Massive multiple input multiple output (MIMO) systems, due to utilizing a large antenna array in each base station, each user’s channel is orthogonal to one another. These systems have some valuable advantages such as the reduction of energy needed for transmission and significant improvement in spectral efficiency, which makes them be suitable for the next generation of wireless communication systems. In this thesis a massive MIMO working is considered on TDD mode, for wich the channel estimation is done in the base station using the pilot sequences recieved from users. At the beginning of each coherence block, users send their pilot sequences and the rest of the times is allocated to...
PLA- PMMA- PEG Blends, Shape Memory Investigation
, M.Sc. Thesis Sharif University of Technology ; Forounchi, Masoud (Supervisor)
Abstract
Semi-crystalline polylactic acid (PLA) and amorphous polymethyl methacrylate can form a soluble and miscible alloy in which the crystalline regions in the polylactic acid act as the fixed and immutable region and amorphous regions of the two polymers act as the changeable region. The two polymers can form a lattice structure with physical connections having shape-memory. So that the deformed polymer returns to its original shape above a certain temperature. These materials are used in sensors, smart materials, and medicine. On the other hand, Polyethylene glycol (PEG) is compatible with polylactic acid (PLA) and it seems that adding it will increase the ductility of polylactic acid (PLA). In...
Fabrication and evaluation of bioresorbable scaffolds for interventional cardiology application with sufficient drug release
, Article Iranian Journal of Basic Medical Sciences ; Volume 25, Issue 3 , 2022 , Pages 372-382 ; 20083866 (ISSN) ; Sadrnezhaad, S. K ; Asefnejad, A ; Nemati, N. H ; Sharif University of Technology
Mashhad University of Medical Sciences
2022
Abstract
Objective(s): Bioresorbable scaffolds have been advocated as the new generation in interventional cardiology because they could provide temporary scaffolds and then disappear with resorption. Although, the available stents in clinical trials exhibited biosafety, efficacy, no death, and no apparent thrombosis, Mg-substrate degradation on drug release has not been investigated. Materials and Methods: Therefore, more research has been needed to legitimize the replacement of current stents with Mg-based stents. UV-Vis spectrophotometer, scanning electron microscope (SEM), X-ray diffraction (XRD), pH measurement, H2 evolution, and corrosion tests determined the change in hybrid properties and...
Asynchronous downlink massive MIMO networks: A stochastic geometry approach
, Article IEEE Transactions on Wireless Communications ; Volume 19, Issue 1 , 2020 , Pages 579-594 ; Azimi Abarghouyi, S. M ; Makki, B ; Nasiri Kenari, M ; Svensson, T ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
Massive multiple-input multiple-output (M-MIMO) is recognized as a promising technology for the next generation of wireless networks because of its potential to increase the spectral efficiency. In initial studies of M-MIMO, the system has been considered to be perfectly synchronized throughout the entire cells. However, perfect synchronization may be hard to attain in practice. Therefore, we study a M-MIMO system whose cells are not synchronous to each other, while transmissions in a cell are still synchronous. We analyze an asynchronous downlink M-MIMO system in terms of the coverage probability and the ergodic rate by means of the stochastic geometry tool. For comparison, we also obtain...
Relativistic and Nonlinear Lffects in Large Scale Structures
, Ph.D. Dissertation Sharif University of Technology ; Mansouri, Reza (Supervisor) ; Taghizadeh Firouzjaee, Javad (Co-Supervisor)
Abstract
Although general relativity is the underlying assumption in modern cosmology, there are still many simplifying assumptions neglecting higher order general relativistic effects. Given the precision cosmology and future surveys and the amount of data on large scales, higher order relativistic effects are to be taken into account. We will consider two categories of relativistic effects on large scale structures. First, the inhomogeneities between the source and the observer may lead to observable effects neglected so far. As future surveys will probe the universe on large scales, these effects have been the focus of recent studies. The observables being defined first, are cosmic rulers and...
Dose-dependent effects of nanoscale graphene oxide on reproduction capability of mammals
, Article Carbon ; Volume 95 , December , 2015 , Pages 309-317 ; 00086223 (ISSN) ; Ghaderi, E ; Hashemi, E ; Akbari, E ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
In vivo dose-dependent effects of nanoscale graphene oxide (NGO) sheets on reproduction capability of Balb/C mice were investigated. Biodistribution study of the NGO sheets (intravenously injected into male mice at dose of ∼2000 μg/mL or 4 mg/kg of body weight) showed a high graphene uptake in testis. Hence, in vivo effects of the NGO sheets on important characteristics of spermatozoa (including their viability, morphology, kinetics, DNA damage and chromosomal aberration) were evaluated. Significant in vivo effects was found at the injected concentrations ≥200 μg/mL after (e.g., ∼45% reduction in sperm viability and motility at 2000 μg/mL). Observation of remarkable DNA fragmentations and...
Accelerated differentiation of neural stem cells into neurons on ginseng-reduced graphene oxide sheets
, Article Carbon ; Volume 66 , January , 2014 , Pages 395-406 ; Ghaderi, E ; Abouei, E ; Hatamie, S ; Ghasemi, E ; Sharif University of Technology
2014
Abstract
Asian red ginseng was used for green reduction of chemically exfoliated graphene oxide (GO) into reduced graphene oxide (rGO). The reduction level and electrical conductivity of the ginseng-rGO sheets were comparable to those of hydrazine-rGO ones. Reduction by ginseng resulted in repairing the sp 2 graphitic structure of the rGO, while hydrazine-rGO showed more defects and/or smaller aromatic domains. The ginseng-rGO sheets presented a better stability against aggregation than the hydrazine-rGO ones in an aqueous suspension. Whilst the hydrophobic hydrazine-rGO films exhibited no toxicity against human neural stem cells (hNSCs), the hydrophilic GO and ginseng-rGO films (as more...
Contested framings and policy controversies: Analysing biosafety policy-making in Iran
, Article Science and Public Policy ; Volume 40, Issue 5 , 2013 , Pages 616-627 ; 03023427 (ISSN) ; Millstone, E ; Sharif University of Technology
2013
Abstract
Vigorous debates have taken place within and between many countries about regulatory policy regimes covering the assessment and approval of genetically modified (GM) crops. In Iran, a very vigorous and hotly contested policy debate concerning legislation covering GM crops occurred between 2004 and 2009, but it was confined within government circles with almost no public discussion. This paper analyses the Iranian policy-making process in the period 2006-9. It explains how and why a stalemate arose in disputes between ministries and departments. The chosen analytical framework draws mainly on the regulation of technological risks and the analysis of public policy-making. It deploys the...
On the possible volumes of μ-way latin trades
, Article Aequationes Mathematicae ; Volume 63, Issue 3 , 2002 , Pages 303-320 ; 00019054 (ISSN) ; Billington, E. J ; Bryant, D. E ; Mahmoodian, E. S ; Sharif University of Technology
Birkhauser Verlag Basel
2002
Abstract
A μ-way latin trade of volume s is a set of μ partial latin rectangles (of inconsequential size) containing exactly the same s filled cells, such that if cell (i, j) is filled, it contains a different entry in each of the μ partial latin rectangles, and such that row i in each of the μ partial latin rectangles contains, set-wise, the same symbols and column j, likewise. In this paper we show that all μ-way latin trades with sufficiently large volumes exist, and state some theorems on the non-existence of μ-way latin trades of certain volumes. We also find the set of possible volumes (that is, the volume spectrum) of μ-way latin trades for μ = 4 and 5. (The case μ = 2 was dealt with by Fu,...
The three-way intersection problem for latin squares
, Article Discrete Mathematics ; Volume 243, Issue 1-3 , 2002 , Pages 1-19 ; 0012365X (ISSN) ; Billington, E. J ; Bryant, D. E ; Mahmoodian, E. S ; Sharif University of Technology
2002
Abstract
The set of integers k for which there exist three latin squares of order n having precisely k cells identical, with their remaining n2 -k cells different in all three latin squares, denoted by I3[n], is determined here for all orders n. In particular, it is shown that I3[n] = {0,.,n2 -15}U [n2 - 12,n2-9,n2], for n ≫8. ©2002 Eisevier Science B.V. All rights reserved
Integration of spatial fuzzy clustering with level set for segmentation of 2-D angiogram
, Article IECBES 2014, Conference Proceedings - 2014 IEEE Conference on Biomedical Engineering and Sciences: "Miri, Where Engineering in Medicine and Biology and Humanity Meet", 8 December 2014 through 10 December 2014 ; December , 2015 , Pages 309-314 ; 9781479940844 (ISBN) ; Zahedi, E ; Fatemizadeh, E ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Coronary angiography is a vital instrument to detect the prevailing of vascular diseases, and accurate vascular segmentation acts a crucial role for proper quantitative analysis of the vascular tree morphological features. Level set methods are popular for segmenting the coronary arteries, but their performance is related to suitable start-up and optimum setting of regulating parameters, essentially done manually. This research presents a novel fuzzy level set procedure with the objective of segmentation of the coronary artery tree in 2-D X-ray angiography as automatically. It is clever to clearly develop from the early segmentation with spatial fuzzy grouping. The adjusting parameters of...
Deep relative attributes
, Article 13th Asian Conference on Computer Vision, ACCV 2016, 20 November 2016 through 24 November 2016 ; Volume 10115 LNCS , 2017 , Pages 118-133 ; 03029743 (ISSN); 9783319541921 (ISBN) ; Noury, E ; Adeli, E ; Sharif University of Technology
Springer Verlag
2017
Abstract
Visual attributes are great means of describing images or scenes, in a way both humans and computers understand. In order to establish a correspondence between images and to be able to compare the strength of each property between images, relative attributes were introduced. However, since their introduction, hand-crafted and engineered features were used to learn increasingly complex models for the problem of relative attributes. This limits the applicability of those methods for more realistic cases. We introduce a deep neural network architecture for the task of relative attribute prediction. A convolutional neural network (ConvNet) is adopted to learn the features by including an...
A public code for astrometric microlensing with contour integration
, Article Monthly Notices of the Royal Astronomical Society ; Volume 505, Issue 1 , 2021 , Pages 126-135 ; 00358711 (ISSN) ; Khalouei, E ; Bachelet, E ; Sharif University of Technology
Oxford University Press
2021
Abstract
We present the first public code for the calculation of the astrometric centroid shift occurring during microlensing events. The computation is based on the contour integration scheme and covers single and binary lensing of finite sources with arbitrary limb darkening profiles. This allows for general detailed investigations of the impact of finite source size in astrometric binary microlensing. The new code is embedded in version 3.0 of vbbinarylensing, which offers a powerful computational tool for extensive studies of microlensing data from current surveys and future space missions. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
Toward electrically tunable, lithography-free, ultra-thin color filters covering the whole visible spectrum
, Article Scientific Reports ; Volume 8, Issue 1 , 2018 ; 20452322 (ISSN) ; Serebryannikov, A. E ; Khavasi, A ; Vandenbosch, G. A. E ; Ozbay, E ; Sharif University of Technology
Nature Publishing Group
2018
Abstract
The possibility of real-time tuning of optical devices has attracted a lot of interest over the last decade. At the same time, coming up with simple lithography-free structures has always been a challenge in the design of large-area compatible devices. In this work, we present the concept and the sample design of an electrically tunable, lithography-free, ultra-thin transmission-mode color filter, the spectrum of which continuously covers the whole visible region. A simple Metal-Insulator-Metal (MIM) cavity configuration is used. It is shown that using the electro-optic dielectric material of 4-dimethyl-amino-N-methyl-4-stilbazoliumtosylate (DAST) as the dielectric layer in this...
A novel method for modeling the magnetizing yoke
, Article Electromagnetics ; Volume 30, Issue 3 , 2010 , Pages 297-308 ; 02726343 (ISSN) ; Norouzi, E
2010
Abstract
Magnetic flux leakage is the most widely used method for oil and gas pipeline non destructive testing. The saturation level of the sample under test has a significant effect on its efficiency; therefore, the magnetizing yoke requires an elaborate design. The finite element method is the conventional approach used for this purpose, but it is very time consuming. In this article, a neuro-fuzzy method is presented to model the behavior of the magnetizing yoke. Modeling a few different designs with the finite element method and using the results for training the neuro-fuzzy model eradicates the necessity of modeling a huge number of designs with the finite element method. The acquired...
On decomposing complete tripartite graphs into 5-cycles
, Article Australasian Journal of Combinatorics ; Volume 54, Issue 2 , 2012 , Pages 289-301 ; 10344942 (ISSN) ; Mahmoodian, E. S ; Mollaahmadi, E ; Sharif University of Technology
AJC
2012
Abstract
The problem of finding necessary and sufficient conditions to decompose a complete tripartite graph K(r, s, t) into 5-cycles was first considered by Mahmoodian and Mirzakhani (1995). They stated some necessary conditions and conjectured that these conditions are also sufficient. Since then, many cases of the problem have been solved by various authors; however the case when the partite sets r ≤ s ≤ t have odd and distinct sizes remains open. A necessary condition is t ≤ 3r. Billington and Cavenagh (2011) have shown that when r, s, and t are all odd and r ≤ s ≤ t ≤ κr, where κ ≈ 1.0806, then the conjectured necessary conditions for decomposing are also sufficient. We extend this result...
Ultra-sensitive detection of leukemia by graphene
, Article Nanoscale ; Vol. 6, issue. 24 , Dec , 2014 , p. 14810-14819 ; Ghaderi, E ; Hashemi, E ; Rahighi, R ; Sharif Universit of Technology
2014
Abstract
Graphene oxide nanoplatelets (GONPs) with extremely sharp edges (lateral dimensions ∼20-200 nm and thicknesses <2 nm) were applied in extraction of the overexpressed guanine synthesized in the cytoplasm of leukemia cells. The blood serums containing the extracted guanine were used in differential pulse voltammetry (DPV) with reduced graphene oxide nanowall (rGONW) electrodes to develop fast and ultra-sensitive electrochemical detection of leukemia cells at leukemia fractions (LFs) of ∼10-11 (as the lower detection limit). The stability of the DPV signals obtained by oxidation of the extracted guanine on the rGONWs was studied after 20 cycles. Without the guanine extraction, the DPV peaks...
Specific picomolar detection of a breast cancer biomarker her-2/neu protein in serum: electrocatalytically amplified electroanalysis by the aptamer/peg-modified electrode
, Article ChemElectroChem ; Volume 4, Issue 4 , 2017 , Pages 872-879 ; 21960216 (ISSN) ; Kékedy Nagy, L ; Ferapontova, E. E ; Sharif University of Technology
Wiley-VCH Verlag
2017
Abstract
Specific and sensitive electroanalysis of blood-circulating protein cancer biomarkers is often complicated by interference from serum proteins nonspecifically adsorbing at the biosensing interface and masking specific reactions of interest. Here, we have developed an electrocatalytically amplified assay for specific and sensitive analysis of human epidermal growth factor receptor-2 (HER-2/neu, a protein cancer biomarker over-expressed in breast cancers) that allows us to avoid both the interference from bovine serum albumin (BSA) and electrocatalytic amplification of the signal stemming from the specific aptamer−HER-2/neu binding. A HER-2/neu-specific thiolated aptamer sequence was...
A two layer texture modeling based on curvelet transform and spiculated lesion filters for recognizing architectural distortion in mammograms
, Article Middle East Conference on Biomedical Engineering, MECBME ; 17 - 20 February , 2014 , pp. 21-24 ; Nadjar, H. S ; Fatemizadeh, E ; Mohammadi, E ; Sharif University of Technology
2014
Abstract
This paper presents a two layer texture modeling method to recognize architectural distortion in mammograms. We propose a method that models a Gaussian mixture on the Curvelet coefficients and the outputs of Spiculated Lesion Filters. The Curvelet transform and the Spiculated Lesion Filters have been applied to extract textural features of mammograms in literature. However the key difference between this study and the previous ones is that in our approach, a Gaussian mixture models the textural features extracted by the Curvelet transform and the Spiculated Lesion Filters. The results of the current study are shown in the form of accuracy and the area under the receiver operating...