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    Merging the Porter's diamond model with SWOT method in order to analyze the Iranian technology parks competitiveness level

    , Article 2008 Portland International Center for Management of Engineering and Technology, Technology Management for a Sustainable Economy, PICMET '08, Cape Town, 27 July 2008 through 31 July 2008 ; 2008 , Pages 276-283 ; 9781890843175 (ISBN) Naserbakht, M ; Asgharizadeh, E ; Mohaghar, A ; Naserbakht, J ; Sharif University of Technology
    2008
    Abstract
    Purpose: This research attempts to formulate an analytical model for the studying and assessment of necessary factors that have strong effects on the level of Iranian Technology Park competitiveness. The result of this model leads to increasing the effectiveness and efficiency of Technology Parks planning stage. Methodology/Approach: The main framework of this research is based on studying the projects and research, which in their methods use the Porter's diamond model or SWOT analytical method. On the other hand, this framework is customized for the future needs of Technology Parks and clarifies the kind of information that must be gathered. Finding: Identification of the core competencies... 

    Probability of missed detection as a criterion for receiver placement in MIMO PCL

    , Article IEEE National Radar Conference - Proceedings, 7 May 2012 through 11 May 2012, Atlanta, GA ; 2012 , Pages 0924-0927 ; 10975659 (ISSN) ; 9781467306584 (ISBN) Majd, M. N ; Chitgarha, M. M ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
    IEEE  2012
    Abstract
    Using multiple antennas at the transmit and receive sides of a passive radar brings both the benefits of MIMO radar and passive radar. However one of the obstacles arisen in such configuration is the receive antennas placement in proper positions so that the radar performance is improved. Here we just consider the case of positioning one receiver among multiple illuminators of opportunity. Indeed it is a start for the solution of optimizing the geometry of the multiple receivers in a passive radar  

    An efficient method for the ring opening of epoxides with aromatic amines by Sb(III) chloride under microwave irradiation

    , Article Journal of Chemical Research ; Issue 4 , 2008 , Pages 220-221 ; 03082342 (ISSN) Ghazanfari, D ; Hashemi, M. M ; Mottaghi, M. M ; Foroughi, M. M ; Sharif University of Technology
    2008
    Abstract
    SbCl3 supported on montmorillonite K-10 is an efficient catalyst for the ring opening of epoxides with aromatic amines under solvent-free conditions and microwave irradiation to give the corresponding b-amino alcohols in high yields with high regioselectivity  

    MIMO radar signal design to improve the MIMO ambiguity function via maximizing its peak

    , Article Signal Processing ; Volume 118 , 2016 , Pages 139-152 ; 01651684 (ISSN) Chitgarha, M. M ; Radmard, M ; Nazari Majd, M ; Karbasi, S. M ; Nayebi, M. M ; Sharif University of Technology
    Elsevier  2016
    Abstract
    One of the important obstacles in MIMO (Multiple Input Multiple Output) radars is the issue of designing proper transmit signals. Indeed, the capability of signal design is a significant advantage in MIMO radars, through which, the system can achieve much better performance. Many different aspects of this performance improvement have been considered yet, and the transmit signals have been designed to attain such goal, e.g., getting higher SNR or better detector's performance at the receiver. However, an important tool for evaluating the radar's performance is its ambiguity function. In this paper, we consider the problem of transmit signal design, in order to optimize the ambiguity function... 

    Detection-localization tradeoff in MIMO radars

    , Article Radioengineering ; Volume 26, Issue 2 , 2017 , Pages 581-587 ; 12102512 (ISSN) Nazari Majd, M ; Radmard, M ; Chitgarha, M. M ; Bastani, M. H ; Nayebi, M. M ; Sharif University of Technology
    2017
    Abstract
    Two gains play key roles in recently developed MIMO wireless communication systems: "spatial diversity" gain and "spatial multiplexing" gain. The diversity gain refers to the capability to decrease the error rate of the MIMO channel, while the multiplexing gain 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 diversity gain) and increasing data rate (via an increase in the multiplexing gain). On the other hand, recently, MIMO radars have attracted much attention for their superior ability to enhance... 

    Antenna placement and power allocation optimization in MIMO detection

    , Article IEEE Transactions on Aerospace and Electronic Systems ; Vol. 50, Issue 2 , April , 2014 , pp. 1468-1478 Radmard, M ; Chitgarha, M. M ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
    2014
    Abstract
    It is a well known fact that using multiple antennas at transmit and receive sides improves the detection performance. However, in such multiple-input multiple-output (MIMO) configuration, proper positioning of transmitters and receivers is a big challenge that can have significant influence on the performance of the overall system. In addition, determining the power of each transmitter under a total power constraint is a problem that should be solved in order to enhance the performance and coverage of such a system. In this paper, we design the Neyman-Pearson detector under the Rayleigh scatter model and use it to introduce a criterion for the antenna placement at both transmit and receive... 

    Ambiguity function of MIMO radar with widely separated antennas

    , Article Proceedings International Radar Symposium ; 16 -18 June , 2014 ; ISSN: 21555753 Radmard, M ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
    2014
    Abstract
    There has been much interest, recently, towards exploiting the Multiple-Input Multiple-Output (MIMO) technique in radar. It is shown that using multiple antennas at transmit and receive sides can improve the performance of the system. However, in order to analyze the system's performance, its ambiguity function, i.e. the ambiguity function of a MIMO radar, is needed to be defined. In this paper, beginning from the information theoretic definitions, we derive such function, specifically for a MIMO radar with widely separated antennas  

    Choosing the position of the receiver in a MISO passive radar system

    , Article European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 9th European Radar Conference, EuRAD 2012 ; 2012 , Pages 318-321 ; 9782874870293 (ISBN) Chitgarha, M. M ; Majd, M. N ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
    2012
    Abstract
    By combining the two ideas of MIMO (Multiple Input Multiple Output) and PCL (Passive Coherent Location) in radar, one can achieve the advantages of both recently developed techniques simultaneously. While using multiple antennas at the receive side provides a spatial diversity of the object to be detected, using multiple illuminators of opportunity, most importantly, makes the radar covert to the interceptors. One obstacle in such MIMO configuration is choosing the positions of the receive antennas. In this paper, after analyzing the Neyman-Pearson detector for the DVB-T based PCL, we introduce the probability of missed detection as a criterion to place the receive antenna. Here, we only... 

    Adaptive filtering techniques in passive radar

    , Article Proceedings International Radar Symposium, Dresden ; Volume 2 , June , 2013 , Pages 1067-1078 ; 21555753 (ISSN) ; 9783954042234 (ISBN) Chitgarha, M. M ; Radmard, M ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
    2013
    Abstract
    One of the most important obstacles in passive radar applications is removing the direct signal from the target channel. Otherwise, week echoes from the targets in the target channel would be ignored due to the limited dynamic range of the system. One of the most effective techniques in this field is using adaptive filters. In this paper various adaptive filters are introduced and their performances are shown and compared  

    Ambiguity function based receiver placement in multi-site radar

    , Article 2016 CIE International Conference on Radar, RADAR 2016, 10 October 2016 through 13 October 2016 ; 2017 ; 9781509048281 (ISBN) Radmard, M ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
    2017
    Abstract
    It has been shown that using multiple antennas in a radar system improves the performance considerably, since multiple target echoes are received from different aspect angles of the target. In this way, the target detection is improved. However, when using multiple antennas, some problems, such as designing the transmit signals, synchronization, etc. emerge that should be solved. One of such problems is the receiver placement. Receiver placement deals with choosing a proper position for the receive antenna in order to optimize the whole system's performance. In this paper, a receiver placement procedure based on improving the radar ambiguity function is proposed for the case of a multisite... 

    Improving MIMO radar's performance through receivers' positioning

    , Article IET Signal Processing ; Volume 11, Issue 5 , 2017 , Pages 622-630 ; 17519675 (ISSN) Chitgarha, M. M ; Radmard, M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
    Institution of Engineering and Technology  2017
    Abstract
    By employing the MIMO (multiple-input-multiple-output) technology in radar, some new problems emerged, that, in order to benefit the MIMO gains in radar, it was necessary to solve them suitably. One of such obstacles is determining the positions of receive antennas in a MIMO radar system with widely separated antennas (WS MIMO radar), since it is shown that the antennas' positions affect the whole system's performance considerably. In this study, a proper receivers' positioning procedure is proposed. To do this end, four criteria are developed based on the proposed MIMO detector and the MIMO ambiguity function. The simulations verify that the proposed positioning procedure improves the... 

    Silylation of hydroxy groups with HMDS under microwave irradiation and solvent-free conditions

    , Article Phosphorus, Sulfur and Silicon and Related Elements ; Volume 177, Issue 2 , 2002 , Pages 289-292 ; 10426507 (ISSN) Mojtahedi, M. M ; Saidi, M. R ; Bolourtchian, M ; Heravi, M. M ; Sharif University of Technology
    2002
    Abstract
    Phenols and alcohols are silylated with hexamethyldisilazane (HMDS) under microwave irradiation in solvent-free condition in good to excellent yields  

    Dynamic analysis of carbon nanotubes under electrostatic actuation using modified couple stress theory

    , Article Acta Mechanica ; Vol. 225, Issue 6 , June , 2014 , pp. 1523-1535 ; Online ISSN: 1619-6937 Fakhrabadi, M. M. S ; Rastgoo, A ; Ahmadian, M. T ; Mashhadi, M. M ; Sharif University of Technology
    2014
    Abstract
    Modified couple stress theory is a size-dependent theorem capturing the micro/nanoscale effects influencing the mechanical behaviors of the micro- and nanostructures. In this paper, it is applied to investigate the nonlinear vibration of carbon nanotubes under step DC voltage. The vibration, natural frequencies and dynamic pull-in characteristics of the carbon nanotubes are studied in detail. Moreover, the effects of various boundary conditions and geometries are scrutinized on the dynamic characteristics. The results reveal that application of this theory leads to the higher values of the natural frequencies and dynamic pull-in voltages  

    White space regions

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 22 January 2011 through 28 January 2011, Novy Smokovec ; Volume 6543 LNCS , 2011 , Pages 226-237 ; 03029743 (ISSN) ; 9783642183805 (ISBN) Ehsani, S ; Fazli, M ; Ghodsi, M ; Safari, M ; Saghafian, M ; Tavakkoli, M ; Sharif University of Technology
    2011
    Abstract
    We study a classical problem in communication and wireless networks called Finding White Space Regions. In this problem, we are given a set of antennas (points) some of which are noisy (black) and the rest are working fine (white). The goal is to find a set of convex hulls with maximum total area that cover all white points and exclude all black points. In other words, these convex hulls make it safe for white antennas to communicate with each other without any interference with black antennas. We study the problem on three different settings (based on overlapping between different convex hulls) and find hardness results and good approximation algorithms  

    Utilization of hybrid nanofluids in solar energy applications: A review

    , Article Nano-Structures and Nano-Objects ; Volume 20 , 2019 ; 2352507X (ISSN) Ahmadi, M. H ; Ghazvini, M ; Sadeghzadeh, M ; Alhuyi Nazari, M ; Ghalandari, M ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Hybrid nanofluids have several advantages compared with the conventional types due to their modified properties. Their enhanced thermophysical and rheological properties make them more appropriate for solar energy systems. In this review paper, an overview of solar energy systems is represented, and afterwards, applications of hybrid nanofluids in various solar technologies, especially solar thermal, are reviewed. Comparison between the nanofluidic systems, and the conventional ones is performed in order to gain a deeper insight into the advantages of using nanofluids. According to the results of the reviewed studies, the most important reason for performance enhancement of nanofluidic solar... 

    Investigating the temporal and spatial variations of water consumption in Urmia Lake River Basin considering the climate and anthropogenic effects on the agriculture in the basin

    , Article Agricultural Water Management ; Volume 213 , 2019 , Pages 782-791 ; 03783774 (ISSN) Taheri, M ; Emadzadeh, M ; Gholizadeh, M ; Tajrishi, M ; Ahmadi, M ; Moradi, M ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Urmia Lake River Basin (ULRB) is one of the most important habitats in the world and one of the major agricultural regions in Iran. On average, the ratio of irrigation to evapotranspiration in this basin is more than 73%. Investigating the irrigation water requirement pattern changes and the spatial distribution of evapotranspiration during the basin development period on a regional scale play important roles in understanding the basin situation. In this study, the actual evapotranspiration has been estimated by SEBAL model. By estimating the precipitation distribution in the basin, the agricultural irrigation water requirement pattern has been calculated using the land use map in 1995, 2010... 

    The first in situ synthesis of 1,3-dioxan-5-one derivatives and their direct use in Claisen-Schmidt reactions: Synthesis of dioxanones and their Claisen-Schmidt reactions

    , Article Heterocyclic Communications ; Volume 25, Issue 1 , 2019 , Pages 85-90 ; 07930283 (ISSN) Javad Poursharifi, M ; Mojtahedi, M. M ; Saeed Abaee, M ; Hashemi, M. M ; Sharif University of Technology
    De Gruyter  2019
    Abstract
    A method is developed for in situ generation of 1,3-dioxan-5-one derivatives 2. These compounds are simple precursors for accessing carbohydrate structures and previously had to be produced via stepwise procedures using excessive amounts of reagents. In the present work, three different derivatives of 2 were synthesized via the reaction of trialkoxyalkanes with dihydroxyacetone dimer 1 in the presence of acetic acid as the catalyst. In the same pot, derivatives of 2 were reacted with aromatic aldehydes and 30 mol% of pyrrolidine to obtain high yields of the respective bischalcones 3 within short time periods. © 2019 M. Javad Poursharifi et al., published by De Gruyter 2019  

    Spatial multiplexing gain in MIMO radars with widely separated antennas

    , Article IET Signal Processing ; Volume 12, Issue 2 , March , 2018 , Pages 207-213 ; 17519675 (ISSN) Nazari Majd, M ; Radmard, M ; Chitgarha, M. M ; Farina, A ; Bastani, M. H ; Nayebi, M. M ; Sharif University of Technology
    Institution of Engineering and Technology  2018
    Abstract
    Multiple-input multiple-output (MIMO) radars have attracted much attention for their superior ability to enhance a system's performance. In this study, the authors' goal was the study of the spatial multiplexing gain of MIMO radars with widely separated antennas (WS-MIMO), which the authors showed that is equal to the number of unambiguously detectable targets. They obtained this number from two different aspects: first, by defining the ambiguity function of a WS-MIMO radar in the case of multiple targets, suitable for such purpose; Second, by modelling the MIMO radar system with a MIMO wireless channel. They showed that a MIMO radar is indeed a MIMO wireless system communicating the... 

    Diversity-multiplexing tradeoff in MIMO radars

    , Article IET Radar, Sonar and Navigation ; Volume 11, Issue 4 , 2017 , Pages 691-700 ; 17518784 (ISSN) Nazari Majd, M ; 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) Ahmadian, M. T ; 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...