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Diversity-multiplexing tradeoff in MIMO radars
, Article IET Radar, Sonar and Navigation ; Volume 11, Issue 4 , 2017 , Pages 691-700 ; 17518784 (ISSN) ; Radmard, M ; Chitgarha, M. M ; Farina, A ; Nayebi, M. M ; Bastani, M. H ; Sharif University of Technology
Institution of Engineering and Technology
2017
Abstract
Two gains play key roles in recently developed multiple-input-multiple-output (MIMO) wireless communication systems: 'spatial diversity' gain and 'spatial multiplexing' gain. The diversity gain (DG) refers to the capability to decrease the error rate of the MIMO channel, whereas the multiplexing gain (MG) implicitly refers to the amount of increase in the capacity of the MIMO channel. It has been shown that there is a fundamental tradeoff between these two types of gains, meaning interplay between increasing reliability (via an increase in the DG) and increasing data rate (via an increase in the MG). On the other hand, recently, MIMO radars have attracted much attention for their superior...
Design and application of a new tapered superelement for analysis of revolving geometries
, Article Finite Elements in Analysis and Design ; Volume 47, Issue 11 , November , 2011 , Pages 1242-1252 ; 0168874X (ISSN) ; Movahhedy, M. R ; Rezaei, M. M ; Sharif University of Technology
2011
Abstract
Structures of tapered geometry are customarily used in a variety of applications. The analysis of such structures is usually made through finite element method using traditional beam, shell or brick elements. In this paper, a new tapered superelement is presented that lends itself to modeling revolving geometries under lateral, axial and torsional loads. The presented tapered superelement has 16 nodes. The performance of this element under static and dynamic loading and in rotating condition is examined. It is shown that this element yields accurate results with higher computational efficiency compared to conventional elements. Furthermore, it is verified that a single tapered superelement...
Modelling and improvement of non-standard queuing systems: A gas station case study
, Article International Journal of Applied Decision Sciences ; Volume 4, Issue 4 , 2011 , Pages 324-340 ; 17558077 (ISSN) ; Yazdi, M. M ; Haddadi, M ; Fathi, M ; Sharif University of Technology
2011
Abstract
This research has modelled a queuing system with no standard states. In order to analyse these systems, some parameters such as the mean of waiting time and the length of queue are computed. These situations usually occur when there is delay in the service, for example, in the gas queuing system that cars are unable to leave after receiving the required services due to the presence of other cars in front of them. These kinds of non-standard queuing systems are usually applied to the assembly and production lines. In this paper, a queuing model for the special non-standard state queuing system is developed to be used in gas stations. The proposed model is implemented in fuel stations in Iran...
Mo(vi) complex supported on Fe3 O4 nanoparticles: magnetically separable nanocatalysts for selective oxidation of sulfides to sulfoxides
,
Article
RSC Advances
;
Volume 5, Issue 66
,
Jun
,
2015
,
Pages 53349-53356
;
20462069 (ISSN)
; Balali, M
; Haghdoost, M. M
; Bagherzadeh, M
;
Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
A molybdenum complex, [MoO2 Cl2 (DMSO)2 ], was immobilized on amino propyl and Schiff base modified magnetic Fe3 O4 @SiO2 nanoparticles by covalent linkage. The resulting nanoparticles were used as efficient and recyclable catalysts for the selective oxidation of sulfides to sulfoxides using urea hydrogen peroxide as the oxidant. The complete characterization of catalysts was carried out by means of thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), elemental analysis, FT-IR and Raman microprobe...
Selective storage and evolution of hydrogen on nafion/NaCl/graphene quantum dot mixed matrix using tensammetry as power electrochemical technique
, Article International Journal of Hydrogen Energy ; Volume 42, Issue 15 , 2017 , Pages 9428-9439 ; 03603199 (ISSN) ; Zakipour, M ; Doroodmand, M. M ; Mehrtash, M ; Sharif University of Technology
2017
Abstract
Hydrogen storage/evolution behavior of nafion/NaCl/graphene quantum dot (GQD) mixed matrix as selective hydrogen capacitor (power source) was evaluated in detail through an electrochemical process at two independent potential ranges. For this purpose, a three-electrode system included Pt disk as counter electrode, Ag/AgCl as reference electrode and GQD-based mixed matrix-modified Pt disk as working electrode. For hydrogen storage, the deposition potential and time were evaluated to −1.0 V (vs. Ag/AgCl) and 120 s, respectively under high basic solution generated using NaOH (1.0 M) solution, followed by evolution of hydrogen at +0.8 V (vs. Ag/AgCl) during formation of hydrogen bubbles. The...
Wide-band VHF nulling by five elements spiral array antenna
, Article ITST 2006 - 2006 6th International Conference on ITS Telecommunications, Proceedings, Chengdu, 21 June 2006 through 23 June 2006 ; 2006 , Pages 446-448 ; 0780395867 (ISBN); 9780780395862 (ISBN) ; Mousavi, M ; Emadi, M ; Nayebi, M. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2006
Abstract
Genetic algorithm for optimization of beam forming in spiral array antenna is used. The goal is to achieve a -20 dB in null over the wide frequency band. Our simulation shows -20 dB over 75 MHz Null Band width, in VHF band. © 2006 IEEE
Receivers' placement of a MIMO radar in the presence of mountains
, Article 2014 International Radar Conference, Radar 2014 ; 2014 ; ISBN: 9781479941957 ; Nazari Majd, M ; Bahrololoom, E ; Chitgarha, M. M ; Nayebi, M. M ; Sharif University of Technology
2014
Abstract
This paper studies the placement of antennas in presence of mountains for widely separated multiple-input multiple-output (MIMO) radar. One of the challenges in this configuration is proper placement of the receive antennas in order to achieve good performance. We derived Neyman-Pearson decision rule for target detection. Via several scenarios we show that proper placement of receivers can provide better performance
VirSense: A novel haptic device with fixed-base motors and a gravity compensation system
, Article Industrial Robot ; Vol. 41, Issue. 1 , 2014 , pp. 37-49 ; ISSN: 0143991X ; Nahvi, A ; Yazdani, M ; Moghadam, M. M ; Arbabtafti, M ; Norouzi, M ; Sharif University of Technology
2014
Abstract
Purpose - This paper aims to present the design and implementation of VirSense, a novel six-DOF haptic interface system, with an emphasis on its gravity compensation and fixed-base motors. Design/methodology/approach - In this paper, the design and manufacture of the VirSense robot and its comparison with the existing haptic devices are presented. The kinematic analysis of the robot, design of the components, and manufacturing of the robot are explained as well. Findings - The proposed system is employed to generate a Virtual Sense (VirSense) with fixed-base motors and a spring compensation system for counterbalancing the torques generated by the weight of the links. The fixed bases of the...
A review on application of nanofluid in various types of heat pipes
, Article Journal of Central South University ; Volume 26, Issue 5 , 2019 , Pages 1021-1041 ; 20952899 (ISSN) ; Ahmadi, M. H ; Sadeghzadeh, M ; Shafii, M. B ; Goodarzi, M ; Sharif University of Technology
Central South University of Technology
2019
Abstract
Nanotechnology is widely used in heat transfer devices to improve thermal performance. Nanofluids can be applied in heat pipes to decrease thermal resistance and achieve a higher heat transfer capability. In the present article, a comprehensive literature review is performed on the nanofluids’ applications in heat pipes. Based on reviewed studies, nanofluids have a high capacity to boost the thermal behavior of various types of heat pipes such as conventional heat pipes, pulsating heat pipes, and thermosyphons. Besides, it is observed that there must be a selected amount of concentration for the high-performance utilization of nanoparticles; high concentration of nanoparticles causes a...
A water-oxidizing dinuclear iron complex as an efficient catalyst toward organic sulfide oxidation
, Article Journal of Coordination Chemistry ; Vol. 67, issue. 18 , Jul , 2014 , p. 3026-3032 ; Najafpour, M. M ; Zare, M ; Holynska, M ; Moghaddam, A. N ; Bagherzadeh, M ; Sharif University of Technology
2014
Abstract
In this paper, we report that a known dinuclear Fe complex, [tpa(H2O)FeOFe(H2O)tpa](ClO4)4 (tpa: tris(2-pyridylmethyl)amine), is an efficient catalyst toward organic sulfide oxidation in the presence of urea-hydrogen peroxide
Spatial diversity gain of MIMO single frequency network in passive coherent location
, Article Scientia Iranica ; Vol. 21, Issue. 6 , 2014 , pp. 2186-2199 ; ISSN: 10263098 ; Majd, M. N ; Chitgarha, M. M ; Khalaj, B. H ; Nayebi, M. M ; Sharif University of Technology
2014
Abstract
Recently, it has been shown that applying MIMO technology, i.e. using multiple antennas at the transmit side and multiple antennas at the receive side, improves the performance of object detection and localization. In such scenarios, the spatial diversity specifically helps overcome the fading of the cross section of the object, leading to reduced probability of missed detection. Such a phenomenon is, in fact, the dual of probability of bit error reduction in communication systems due to diversity gain. Despite the importance of such performance enhancement, this subject has not been sufficiently investigated in the PCL (Passive Coherent Location) schemes, where the transmitters (or...
The detector's output SNR as a criterion for receiver placement in MIMO DVB-T based passive coherent location
, Article International Congress on Ultra Modern Telecommunications and Control Systems and Workshops ; 2012 , Pages 431-435 ; 21570221 (ISSN) ; 9781467320153 (ISBN) ; Radmard, M ; Majd, M. N ; Khalaj, B. H ; Nayebi, M. M ; Sharif University of Technology
2012
Abstract
As the DVB-T (Digital Video Broadcasting-Terrestrial)'s use is outspreading, one of its interesting emerging applications is to use DVB-T stations as non-cooperative transmitters in order to detect and localize targets. An important and favorable characteristic of DVB-T for this application is its being working in a Single Frequency Network (SFN), so that multiple transmitters can be used simultaneously to detect the targets. In addition, using multiple antennas at the receiver side leads to the well known configuration known as MIMO. However, one of the obstacles, arisen in such configurations, is the receive antennas' placement in proper positions so that the detection performance is...
Receivers' positioning in multiple-input multiple-output digital video broadcast-terrestrial-based passive coherent location
, Article IET Radar, Sonar and Navigation ; Volume 6, Issue 7 , 2012 , Pages 603-610 ; 17518784 (ISSN) ; Khalaj, B. H ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
IEEE
2012
Abstract
Using multiple illuminators of opportunity at the transmit side and multiple antennas at the receiver side in a passive coherent location (PCL) scheme is expected to improve the detection performance. However, in such multiple-input multiple-output (MIMO) configuration choosing the position of the receivers is an obstacle that can have significant influence on the resulting performance. In this study, the authors consider the case of digital video broadcast (DVB)-T stations as non-cooperative transmitters and introduce a procedure based on the probability of missed detection to properly place receive antennas in a MIMO digital video broadcasting (DVB)-T based PCL configuration
Erratum to Non-linear dynamical features of center of pressure extracted by recurrence quantification analysis in people with unilateral anterior cruciate ligament injury [Gait Posture, 31, 4, (2010), 450-455]
, Article Gait and Posture ; Volume 32, Issue 1 , 2010 , Pages 148 ; 09666362 (ISSN) ; Salavati, M ; Mazaheri, M ; Sanjari, M. A ; Hadian, M. R ; Parnianpour, M ; Shrif University of Technology
2010
Non-linear dynamical features of center of pressure extracted by recurrence quantification analysis in people with unilateral anterior cruciate ligament injury
, Article Gait and Posture ; Volume 31, Issue 4 , 2010 , Pages 450-455 ; 09666362 (ISSN) ; Salavati, M ; Mazaheri, M ; Sanjari, M. A ; Hadian, M. R ; Parnianpour, M ; Sharif University of Technology
2010
Abstract
Knowledge about the non-linear dynamical pattern of postural sway may provide important insights into the adaptability (flexibility) of human postural control in response to everyday stresses imposed on the body. A commonly used non-linear tool, i.e. recurrence quantification analysis, was chosen to investigate the effect of prior anterior cruciate ligament injury on the deterministic pattern of postural sway under different conditions of postural and cognitive difficulty. In double leg stance, as postural difficulty increased from open-eyes to closed-eyes and rigid-surface to foam-surface, the centre of pressure regularity (%determinism) increased as well. In comparison to healthy...
Pr–Co co-doped BFO multiferroics nanomaterials for absorber applications
, Article Ceramics International ; Volume 47, Issue 2 , 2021 , Pages 2144-2154 ; 02728842 (ISSN) ; Yousaf, M ; Baqir, M. A ; Batoo, K. M ; Khan, M. A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Pr and Co co-doped BiFeO3 multiferroics of the following composition BiCoxPrxFe1-2xO3, where (x = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.25) were prepared via sol-gel route. XRD, FTIR, SEM, VSM and VNA were used to evaluate the structural, phase, morphological and electromagnetic properties of Pr and Co co-doped multiferroics. All the undoped and Pr–Co co-doped multiferroics were of single rhombohedral phased whereas at higher concentration the orthorhombic structure was present. FTIR analysis exhibited the presence of orthorhombic phase. SEM images revealed that the grains of Pr and Co doped multiferroics are circular and elliptical in shape. Dielectric and electromagnetic properties were...
Highly regioselective ring opening of epoxides with thiols catalyzed by SbCl3 under solvent-free conditions
, Article Phosphorus, Sulfur and Silicon and the Related Elements ; Volume 183, Issue 12 , 2008 , Pages 3018-3022 ; 10426507 (ISSN) ; Hashemi, M. M ; Akhgar, M. R ; Foroughi, M. M ; Najafi Zadeh, F ; Sharif University of Technology
2008
Abstract
The ring-opening reaction of epoxides with thiols by SbCl3 supported on Kieselguhr under solvent-free conditions, afforded high yields of β-hydroxy sulfides. Nucleophilic attack of the thiols occurs regioselectively at the less hindered side of the epoxides. Copyright © Taylor & Francis Group, LLC
Pr–Co co-doped BFO multiferroics nanomaterials for absorber applications
, Article Ceramics International ; Volume 47, Issue 2 , 2021 , Pages 2144-2154 ; 02728842 (ISSN) ; Yousaf, M ; Baqir, M. A ; Batoo, K. M ; Khan, M. A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Pr and Co co-doped BiFeO3 multiferroics of the following composition BiCoxPrxFe1-2xO3, where (x = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.25) were prepared via sol-gel route. XRD, FTIR, SEM, VSM and VNA were used to evaluate the structural, phase, morphological and electromagnetic properties of Pr and Co co-doped multiferroics. All the undoped and Pr–Co co-doped multiferroics were of single rhombohedral phased whereas at higher concentration the orthorhombic structure was present. FTIR analysis exhibited the presence of orthorhombic phase. SEM images revealed that the grains of Pr and Co doped multiferroics are circular and elliptical in shape. Dielectric and electromagnetic properties were...
Radar HRRP modeling using dynamic system for radar target recognition
, Article Radioengineering ; Vol. 23, issue. 1 , 2014 , p. 121-127 ; Hadavi, M ; Bastani, M. H ; Nayebi, M. M ; Sharif University of Technology
2014
Abstract
High resolution range profile (HRRP) is being known as one of the most powerful tools for radar target recognition. The main problem with range profile for radar target recognition is its sensitivity to aspect angle. To overcome this problem, consecutive samples of HRRP were assumed to be identically independently distributed (IID) in small frames of aspect angles in most of the related works. Here, considering the physical circumstances of maneuver of an aerial target, we have proposed dynamic system which models the short dependency between consecutive samples of HRRP in segments of the whole HRRP sequence. Dynamic system (DS) is used to model the sequence of PCA (principal component...
A new pseudolinear solution to bearing-only tracking
, Article IEEE National Radar Conference - Proceedings ; 2013 ; 10975659 (ISSN) ; 9781467357920 (ISBN) ; Khalili, M. M ; Norouzi, Y ; Nayebi, M. M ; Sharif University of Technology
2013
Abstract
The main focus of this paper is on the estimation of target motion parameters using bearing measurements. Here, based on a linearization of measurements, a recursive least squares (RLS) solution is developed. The performance of the proposed method is compared to PLE which uses the same approach in measurement linearization. Simulation results show the excellence of the proposed method over the PLE, and RLS results are in vicinity of the CRLB