Search for: microwaves
Total 266 records
Article IEEE Microwave Magazine ; Volume 19, Issue 3 , May , 2018 , Pages 124-128 ; 15273342 (ISSN) ; Banai, A ; Farzaneh, F ; Kamarei, M ; Moradi, G ; Rashed Mohassel, J ; Shahabadi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2018
Presents information on global MTTS society education initiatives. © 2000-2012 IEEE
An analytical approach in analysis of local oscillator near-the-carrier AM noise suppression in microwave balanced mixers, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 57, Issue 1 , 2009 , Pages 760-766 ; 00189480 (ISSN) ; Banai, A ; Farzaneh, F ; Sharif University of Technology
In this paper, a new formulation based on conversion matrix method is proposed to analyze "near-the-carrier local ocillator (LO) noise" down conversion to IF in microwave mixers. This method could be easily applied to analyze LO noise down conversion in any type of mixer. Practical results of this method have been compared with the envelope method and measurement results. It is shown that despite the conventional AM noise suppression in balanced mixers, the near-the-carrier LO noise suppression does not occur necessarily at the center frequency of hybrid in balanced mixers. AM noise suppression values are predicted precisely. © 2009 IEEE
Authors reply to comments on investigation of a class-j mode PA in presence of a second-harmonic voltage at the gate node of the transistor, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 66, Issue 7 , 2018 , Pages 3344-3344 ; 00189480 (ISSN) ; Medi, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2018
An analytical approach in analysis of local oscillator near-the-carrier AM noise suppression in microwave balanced mixers, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 57, Issue 4 , 2009 , Pages 760-766 ; 00189480 (ISSN) ; Banai, A ; Farzaneh, F ; Sharif University of Technology
In this paper, a new formulation based on conversion matrix method is proposed to analyze near-the-carrier local ocillator (LO) noise down conversion to IF in microwave mixers. This method could be easily applied to analyze LO noise down conversion in any type of mixer. Practical results of this method have been compared with the envelope method and measurement results. It is shown that despite the conventional AM noise suppression in balanced mixers, the near-the-carrier LO noise suppression does not occur necessarily at the center frequency of hybrid in balanced mixers. AM noise suppression values are predicted precisely. © 2006 IEEE
Article Oriental Journal of Chemistry ; Volume 28, Issue 3 , 2012 , Pages 1141-1145 ; 0970020X (ISSN) ; Pourjavadi, A ; Hosseinzadeh, H ; Sharif University of Technology
Conjugated enynes, dienes and simple olefins have been cleanly and selectively synthesized, good-to-excellent yields, by dehydration of corresponding alcohols using focused microwave irradiation on the surface of LiCI-acidic alumina
Article Optics InfoBase Conference Papers, 19 March 2012 through 21 March 2012 ; March , 2012 ; 21622701 (ISSN) ; 9781557529398 (ISBN) ; Abdi, M ; Milburn, G. J ; Tombesi, P ; Vitali, D ; Sharif University of Technology
We describe a quantum interface between an optical and a microwave field based on their common interaction with a nano-mechanical resonator. This is an effective source of two-mode squeezing with an optical idler and a microwave signal, enabling continuous variable teleportation
KF-Al2O3 promoted synthesis of fully substituted new indeno- and naphtho-fused thiophenes under solvent-free conditions by controlled microwave heating, Article Letters in Organic Chemistry ; Volume 4, Issue 8 , 2007 , Pages 576-584 ; 15701786 (ISSN) ; Saeidian, H ; Mirjafary, Z ; Sadeghi, A ; Sharif University of Technology
KF-Al2O3 catalyzes the reaction of arylthioacetamides with α-bromo, ketones to give fully substituted new indeno- and naphtho- fused thiophenes with good yields under solvent-free conditions by controlled microwave heating. A mechanism is proposed for the reaction course. © 2007 Bentham Science Publishers Ltd
Article 2013 Conference on Lasers and Electro-Optics Europe and International Quantum Electronics Conference, CLEO/Europe-IQEC 2013, Munich, 12 May 2013 through 16 May 2013 ; 2013 ; Abdi, M ; Milburn, G. J ; Tombesi, P ; Vitali, D ; Sharif University of Technology
IEEE Computer Society 2013
A number of schemes for a quantum interface between light at different wavelengths have been demonstrated and very recently various solutions for interfacing optics and microwaves have been proposed [1-3]. We describe here a reversible quantum interface between optical and microwave photons based on a micro-mechanical resonator in a superconducting circuit, simultaneously interacting with an optical and a microwave cavity . When the cavities are appropriately driven, the mechanical resonator mediates an effective parametric amplifier interaction, entangling an optical signal and a microwave idler. Such continuous variable (CV) entanglement can be then exploited to implement CV...
Estimation of practical Inter-Modulation Rejection values in a multi-loop feed-forward microwave power amplifier using Monte-Carlo method, Article 2007 IEEE International Conference on Telecommunications and Malaysia International Conference on Communications, ICT-MICC 2007, Penang, 14 May 2007 through 17 May 2007 ; February , 2007 , Pages 632-637 ; 1424410940 (ISBN); 9781424410941 (ISBN) ; Hemmatyar, A ; Farzaneh, F ; Sharif University of Technology
Feed-forward is one of the best methods for linearizing microwave power amplifiers, but due to device tolerance in implementation of the system components, the practical Inter-Modulation Rejection (IMR) value may differ quite much from the theoretical IMR value. One of the methods to improve the practical performance of the system is using the multi-loop configuration. Here we have introduced the multi-loop feedforward systems and we have estimated the practical IMR values of the system using Monte-Carlo analysis. As the analysis shows, although the number of components in a multi-loop system is increased with respect to a simple feed-forward system, but the difference between the practical...
Article Physical Review Letters ; Volume 109, Issue 13 , September , 2012 ; 00319007 (ISSN) ; Abdi, M ; Milburn, G. J ; Tombesi, P ; Vitali, D ; Sharif University of Technology
We describe a reversible quantum interface between an optical and a microwave field using a hybrid device based on their common interaction with a micromechanical resonator in a superconducting circuit. We show that, by employing state-of-the-art optoelectromechanical devices, one can realize an effective source of (bright) two-mode squeezing with an optical idler (signal) and a microwave signal, which can be used for high-fidelity transfer of quantum states between optical and microwave fields by means of continuous variable teleportation
Article 2008 Asia Pacific Microwave Conference, APMC 2008, Hong Kong, 16 December 2008 through 20 December 2008 ; May , 2008 ; 9781424426423 (ISBN) ; Shishegar, A. A ; Sharif University of Technology
The spatial Green's function of the open microstrip structure is usually represented by the time-consuming and computationally inefficient spectral integral. This paper introduces a new closed form Green's function for the open microstrip structure by applying the GGF method. Therefore, the numerical integration of the spectral integral can be avoided entirely, leading to a considerable decrease of calculating time. Owing to the remarkable resemblances between the CI and GGF methods, for improvement of approximation especially in large distances, some useful techniques such as extraction of the surface wave poles can be carried out. Even though only an open microstrip structure with one...
Microwave-induced Cannizzaro reaction over neutral γ-alumina as a polymeric catalyst [electronic resource], Article Reactive and Functional Polymers ; 01/2002; 51(1):49-53 ; Soleimanzadeh, B ; Marandi, G. B
γ-Alumina is used to catalyze the Cannizzaro reaction in the absence of any base under microwave irradiation in high yields. In the case of terephthalaldehyde the reaction is carried out with high selectivity
Microwave assisted preparation of flavylium salts with perchloric acid impregnated on silica gel under solvent-free conditions, Article Letters in Organic Chemistry ; Vol. 11, issue. 10 , 2014 , pp. 713-718 ; ISSN: 15701786 ; Foroushani, B. K ; Ghonouei, N ; Kalahroodi, E. L ; Sharif University of Technology
Perchloric acid immobilized on silica gel (SiO2-HClO4) has been utilized as a mild and cheap reagent for onepot preparation of different varieties of flavylium salts via tandem reaction of different acetophenones with Salicylaldehydes under solvent-free conditions. Different reaction conditions such as conventional heating and microwave irradiation have been investigated. The corresponding flavylium salts have been prepared in high yields. The procedure is milder and more convenient than the known procedures
Article Journal of Alloys and Compounds ; Volume 586 , 2014 , Pages 380-384 ; Marandi, M ; Molaei, M ; Iraji-zad, A ; Taghavinia, N ; Sharif University of Technology
We have synthesized ZnxCd1-xS nanocrystals (NCs) using a microwave assisted method. Zn(Ac)2, CdSO4 and Na2S2O3 were used as the precursors and thioglycerol (TG) was used as the capping agent. Na2S 2O3 is a photo and heat sensitive material, which supplies S species needed for the reaction upon dissociation. In this facile method, microwave irradiation provides the activation energy for the dissociation of Na2S2O3 in and leads to the formation of ZnxCd1-xS NCs in 2 min. The question that to what extent Zn is incorporated into CdS structure was addressed using UV-Vis spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Our results showed that the real value of x in...
Reconfigurable infinite impulse response (IIR) microwave-photonic filter with controllable selectivity using tunable delay line, Article Conference on Millimeter-Wave and Terahertz Technologies, MMWaTT, 24 December 2012 through 26 December 2012 ; December , 2012 , Pages 37-39 ; 21570965 (ISSN) ; 9781467349567 (ISBN) ; Jamshidi, K ; Akbari, M ; Sharif University of Technology
A tunable IIR microwave-photonic filter (MPF) with controllable selectivity is implemented using an electrically tunable delay line. The proposed method has been experimentally tested and verified. An IIR Microwave-Photonic filter with variable Q factor in the range of 238 - 257 is realized
Rapid microwave-assisted synthesis of PVP-coated ultrasmall gadolinium oxide nanoparticles for magnetic resonance imaging, Article Chemical Physics ; Volume 453-454 , May , 2015 , Pages 35-41 ; 03010104 (ISSN) ; Madaah Hosseini, H. R ; Khodaei, A ; Montazerabadi, A. R ; Irajirad, R ; Oghabian, M. A ; Delavari,H. H ; Sharif University of Technology
Synthesis of polyvinyl pyrrolidone (PVP) coated ultrasmall Gd
2O 3 nanoparticles (NPs) with enhanced T 1-weighted signal intensity and r 2/r 1 ratio close to unity is performed by a microwave-assisted polyol process. PVP coated Gd 2O 3NPs with spherical shape and uniform size of 2.5 ± 0.5 nm have been synthesized below 5 min and structure and morphology confirmed by HRTEM, XRD and FTIR. The longitudinal (r 1) and transversal relaxation (r 2) of Gd 2O 3NPs is measured by a 3 T MRI scanner. The results showed considerable increasing of relaxivity for Gd 2O 3NPs in...
Article European Signal Processing Conference, 28 August 2016 through 2 September 2016 ; Volume 2016-November , 2016 , Pages 341-344 ; 22195491 (ISSN) ; 9780992862657 (ISBN) ; Marvasti, F ; Sharif University of Technology
European Signal Processing Conference, EUSIPCO 2016
The inverse problem in MicroWave Imaging (MWI) is an ill-posed one which can be solved with the aid of the sparsity prior of the solution. In this paper, an Iterative Least Squares Algorithm (ILSA) has been proposed as an inverse solver in MWI which seeks for the sparse vector satisfying the problem constraints. Minimizing a least squares cost function, we derive a relatively simple iterative algorithm which enforces the sparsity gradually with the aid of a reweighting operator. The simulation results confirm the superiority of the suggested method compared to the state-of-the-art schemes in the quality of the recovered breast tumors in the microwave images
Article Ceramics International ; Volume 43, Issue 8 , 2017 , Pages 6105-6109 ; 02728842 (ISSN) ; Ebadzadeh, T ; Sadeghian, Z ; Barzega Bafrooei, H ; Nemati, A ; Sharif University of Technology
Elsevier Ltd 2017
Alumina-MWCNT composite was densified by microwave sintering. CNTs were coated with boehmite nanoparticles to enhance their distribution in composite samples. Calcination temperature of composite powder was determined by TGA analysis (5 °C/min). Samples containing 0 and 1vol%CNT were produced by cold isostatic pressing at 180 MPa. Microwave sintering (1520 °C for 45 min) was conducted under the flow of argon. Phase analysis of the calcined composite powder showed complete transformation of boehmite into gamma-alumina. The relative densities were 99.3% and 98.1% for monolithic alumina and composite, respectively. CNT addition improved the fracture toughness of alumina by ~37%. SEM images...
Synthesis of tetrahydrothiopyrano[2,3-b]indole fullerene derivatives via hetero-diels–alder reaction of c60 and α,β-unsaturated indole-2-thiones, Article Journal of Heterocyclic Chemistry ; Volume 54, Issue 2 , 2017 , Pages 911-915 ; 0022152X (ISSN) ; Ghanbari, B ; Behzadi, M ; Baghersad, M. H ; Sharif University of Technology
Hetero-Diels–Alder reactions of fullerene with α,β-unsaturated thio-oxindoles (3a, 3b, 3c), prepared from thio-oxindole 1 and heteroaromatic aldehydes (2a, 2b, 2c), to generate tetrahydrothiopyrano[2,3-b]indole fullerene cycloadducts (5a, 5b, 5c) under thermal or microwave irradiation were described. The yields were improved, and the reaction time was decreased by conducting the reaction under microwave irradiation. © 2016 Wiley Periodicals, Inc
Nanostructured ternary composites of PPy/CNT/NiFe2O4 and PPy/CNT/CoFe2O4: Delineating and improving microwave absorption, Article Comptes Rendus Chimie ; Volume 21, Issue 9 , 2018 , Pages 862-871 ; 16310748 (ISSN) ; Kheirjou, S ; Asgari, S ; Kazerooni, H ; Sharif University of Technology
Elsevier Masson SAS 2018
Two different ternary nanocomposites, PPy/CNT/CoFe2O4 and PPy/CNT/NiFe2O4, were synthesized by in situ polymerization method. The resulting composites were characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. They were evaluated with the aim of investigating microwave absorption properties. The results showed that the value of microwave reflection decreases as that of prepared nanocomposites increases. This happens with increase in the PPy content and polymerization on the surface. © 2018 Académie des sciences