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    Performance improvement of a double stage switch mode AC voltage regulator

    , Article 2012 3rd Power Electronics and Drive Systems Technology, PEDSTC 2012, 15 February 2012 through 16 February 2012 ; February , 2012 , Pages 181-186 ; 9781467301114 (ISBN) Hajimoradi, M. R ; Karimi, E ; Mokhtari, H ; Yazdian, A ; Sharif University of Technology
    2012
    Abstract
    Widespread use of sensitive loads in industries has required the need for high efficiency voltage regulators in order to provide continuous and fast dynamic adjustable AC voltage. This paper introduces a new control strategy to improve the response time and performance of a double stage switch mode regulator. The proposed strategy responds to input voltage variations quickly and improves the efficiency and performance of the circuit. Results of some simulations are presented and analyzed. Experimental tests on a laboratory prototype verify the excellent performance of the proposed system  

    Adaptive modulation technique for amplify & forward cooperative diversity and fairness analysis

    , Article 2008 International Conference on Telecommunications, ICT, St. Petersburg, 16 June 2008 through 19 June 2008 ; October , 2008 ; 9781424420360 (ISBN) Yazdian, E ; Pakravan, M. R ; Sharif University of Technology
    2008
    Abstract
    In recent years, cooperative diversity techniques have gained increased attention as a new method to combat degrading channel effects. Cooperation among two or more single antenna users generates a virtual diverse multiple-antenna transmission system in the wireless network. In this paper, we propose a scheme to improve the spectral efficiency of the Amplify and Forward system and investigate the application of adaptive modulation concept to the performance of cooperative techniques. We consider the adaptation of rate and power allocation with MQAM modulation and study the performance of Amplify & Forward scenarios in Rayleigh fading channels. We compare this system with its comparable... 

    Source Enumeration and Identification in Array Processing Systems

    , Ph.D. Dissertation Sharif University of Technology Yazdian, Ehsan (Author) ; Bastani, Mohammad Hasan (Supervisor)
    Abstract
    Employing array of antennas in amny signal processing application has received considerable attention in recent years due to major advances in design and implementation of large dimentional antennas. In many applications we deal with such large dimentional antennas which challenge the traditional signal processing algorithms. Since most of traditional signal processing algorithms assume that the number of samples is much more than the number of array elements while it is not possible to collect so many samples due to hardware and time constraints.
    In this thesis we exploit new results in random matrix theory to charachterize and describe the properties of Sample Covariance Matrices... 

    Adaptive modulation technique for cooperative diversity in wireless fading channels

    , Article 2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, Helsinki, 11 September 2006 through 14 September 2006 ; 2006 ; 1424403294 (ISBN); 9781424403295 (ISBN) Yazdian, E ; Pakravan, M. R ; Sharif University of Technology
    2006
    Abstract
    In recent years, cooperative diversity techniques have gained increased attention as a new way to combat degrading effects of Fading. Cooperation among two or more single antenna users generates a virtual diverse multiple-antenna transmission system in the wireless network. In this paper, we investigate the application of adaptive modulation concept to the performance of cooperative techniques. We consider the adaptation of rate and power allocation with M-QAM modulation, and study the performance of Amplify & Forward scenarios in Rayleigh fading channels. We compare these systems with their comparable adaptive non-cooperative scenario and evaluate the energy saving achieved through... 

    Design and implementation of spectrally-encoded spread-time CDMA transceiver

    , Article IEEE Communications Letters ; Vol. 18, issue. 5 , 2014 , pp. 741-744 ; ISSN: 10897798 Shoreh, M. H ; Hosseinianfar, H ; Akhoundi F ; Yazdian, E ; Farhang, M ; Salehi, J. A ; Sharif University of Technology
    2014
    Abstract
    In this paper, we present and discuss the physical implementation and testing of a Spectrally-Encoded Spread-Time Code Devision Multiple Access (SE/ST-CDMA) transceiver. The proposed design is suitable for multiple-access and anti jamming wireless communication systems. The design and implementation takes into account the ability to automatically detect and mitigate tone jammers by altering the corresponding Gold sequence codes assigned uniquely to each user and setting the corresponding code's chip to zero. A simple real-time anti jamming mechanism capable of dealing with frequency hopping jammers is also proposed. The simulation results are provided in terms of Bit Error Rate (BER) versus... 

    Source enumeration in large arrays using moments of eigenvalues and relatively few samples

    , Article IET Signal Processing ; Volume 6, Issue 7 , 2012 , Pages 689-696 ; 17519675 (ISSN) Yazdian, E ; Gazor, S ; Bastani, H ; Sharif University of Technology
    IET  2012
    Abstract
    This study presents a method based on minimum description length criterion to enumerate the incident waves impinging on a large array using a relatively small number of samples. The proposed scheme exploits the statistical properties of eigenvalues of the sample covariance matrix (SCM) of Gaussian processes. The authors use a number of moments of noise eigenvalues of the SCM in order to separate noise and signal subspaces more accurately. In particular, the authors assume a Marcenko-Pastur probability density function (pdf) for the eigenvalues of SCM associated with the noise subspace. We also use an enhanced noise variance estimator to reduce the bias leakage between the subspaces.... 

    Source enumeration in large arrays based on moments of eigenvalues in sample starved conditions

    , Article IEEE Workshop on Signal Processing Systems, SiPS: Design and Implementation, 17 October 2012 through 19 October 2012, Quebec ; October , 2012 , Pages 79-84 ; 15206130 (ISSN) ; 9780769548562 (ISBN) Yazdian, E ; Bastani, M. H ; Gazor, S ; Sharif University of Technology
    2012
    Abstract
    This paper presents a scheme to enumerate the incident waves impinging on a high dimensional uniform linear array using relatively few samples. The approach is based on Minimum Description Length (MDL) criteria and statistical properties of eigenvalues of the Sample Covariance Matrix (SCM). We assume that several models, with each model representing a certain number of sources, will compete and MDL criterion will select the best model with the minimum model complexity and maximum model decision. Statistics of noise eigenvalue of SCM can be approximated by the distributional properties of the eigenvalues given by Marcenko-Pastur distribution in the signal-free SCM. In this paper we use random... 

    Spectral distribution of the exponentially windowed sample covariance matrix

    , Article ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings, 25 March 2012 through 30 March 2012, Kyoto ; 2012 , Pages 3529-3532 ; 15206149 (ISSN) ; 9781467300469 (ISBN) Yazdian, E ; Bastani, M. H ; Gazor, S ; Sharif University of Technology
    IEEE  2012
    Abstract
    In this paper, we investigate the effect of applying an exponential window on the limiting spectral distribution (l.s.d.) of the exponentially windowed sample covariance matrix (SCM) of complex array data. We use recent advances in random matrix theory which describe the distribution of eigenvalues of the doubly correlated Wishart matrices. We derive an explicit expression for the l.s.d. of the noise-only data. Simulations are performed to support our theoretical claims  

    Limiting spectral distribution of the sample covariance matrix of the windowed array data

    , Article Eurasip Journal on Advances in Signal Processing ; Volume 2013, Issue 1 , 2013 ; 16876172 (ISSN) Yazdian, E ; Gazor, S ; Bastani, M. H ; Sharif University of Technology
    2013
    Abstract
    In this article, we investigate the limiting spectral distribution of the sample covariance matrix (SCM) of weighted/windowed complex data. We use recent advances in random matrix theory and describe the distribution of eigenvalues of the doubly correlated Wishart matrices. We obtain an approximation for the spectral distribution of the SCM obtained from windowed data. We also determine a condition on the coefficients of the window, under which the fragmentation of the support of noise eigenvalues can be avoided, in the noise-only data case. For the commonly used exponential window, we derive an explicit expression for the l.s.d of the noise-only data. In addition, we present a method to... 

    Design and Simulation of Simulated Moving Beds

    , M.Sc. Thesis Sharif University of Technology Yazdian Kashani, Sepideh (Author) ; Farhadi, Fathollah (Supervisor)
    Abstract
    In this thesis design and simulation of SMB for four different mixture was done with Aspen chromatography package. Simulation for three mixtures of D-Psicose and D-Fructose, racemic mixture of Bupivacaine and Ibuprofen racemate were done with the aim of validation, based on experimental data of articles. The simulation results matched well with the experimental results in articles. The separation of p-xylene from mixed C8 aromatics and Para Diethyl benzene (as desorbent), was simulated for one of the p-xylene producing units and results were validated against the PFD. The influence of various parameters on the purity and recovery of p-xylene were investigated. The studies showed high... 

    An extended algorithm for autonomous grasping of soft tissues during robotic surgery

    , Article International Journal of Medical Robotics and Computer Assisted Surgery ; Volume 16, Issue 5 , 2020 , Pages 1-15 Amirkhani, G ; Farahmand, F ; Yazdian, S. M ; Mirbagheri, A ; Sharif University of Technology
    John Wiley and Sons Ltd  2020
    Abstract
    Background: Autonomous grasping of soft tissues can facilitate the robotic surgery procedures. The previous attempts for implementing auto-grasping have been based on a simplistic representation of the actual surgery maneuvers. Method: A generalized three-zone grasp model was introduced to consider the effect of the pull force angulation on the grasp mode, that is, damage, slip, or safe grasp. Also, an extended auto-grasping algorithm was proposed in which the trigger force is automatically controlled against the pull force magnitude and direction, to achieve a safe and secure grasp. Results: The autonomous grasping experiments against a varying pull force in a phantom study indicated a good... 

    Eigenvalue estimation of the exponentially windowed sample covariance matrices

    , Article IEEE Transactions on Information Theory ; Volume 62, Issue 7 , 2016 , Pages 4300-4311 ; 00189448 (ISSN) Yazdian, E ; Gazor, S ; Bastani, M. H ; Sharifitabar, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    In this paper, we consider an exponentially windowed sample covariance matrix (EWSCM) and propose an improved estimator for its eigenvalues. We use new advances in random matrix theory, which describe the limiting spectral distribution of the large dimensional doubly correlated Wishart matrices to find the support and distribution of the eigenvalues of the EWSCM. We then employ the complex integration and residue theorem to design an estimator for the eigenvalues, which satisfies the cluster separability condition, assuming that the eigenvalue multiplicities are known. We show that the proposed estimator is consistent in the asymptotic regime and has good performance in finite sample size... 

    Investigation of the Effects of Wall Roughness on the Acoustic Field for Flow Inside a Pipe

    , M.Sc. Thesis Sharif University of Technology Yazdian Hosseinpour, Amir (Author) ; Taghizadeh Manzari, Mehrdad (Supervisor)
    Abstract
    One of the methods of measuring the flow rate in a pipe (channel) is by using the acoustic waves with long wavelenghs in Sonar flowmeters. This flowmeter consists of an array of sensors, mounted on the outer wall of the pipe. These sensors by listening and interpreting the sound waves passing through the fluid, would give a “non-intrusive” measurement of the volumetric flow rate. This means that the flowmeter is not in direct contact with the flow and therefore its repair, relocation or replacement will not disturb the flow. In this project, we will provide a clear understanding of the principles and physics involved in sonar-based acoustic flowmeters, by means of numerical simulation of the... 

    Impacts of relays coordination and alternate supply availability on radial sub-transmission networks reliability assessment

    , Article 2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific, Dalian, 15 August 2005 through 18 August 2005 ; Volume 2005 , 2005 , Pages 1-5 ; 0780391144 (ISBN); 9780780391147 (ISBN) Ahmadi, I ; Barforoushi, T ; Fotuhi Firuzabad, M ; Yazdian Variani, A ; Sharif University of Technology
    2005
    Abstract
    Protection systems play a major role in the performance of electric power systems. There are a number of techniques such as redundancy within the relay system or local and remote backup methods to improve protection system reliability to remove faults as fast as possible, coordination of protective relays is very important. Also availability to neighboring systems affects significantly on repair time after occurring an event. An approach is presented in this paper to incorporate relay coordination and alternative supply availability on radial sub-transmission system reliability. For this purpose, a computer program has been developed. As a case study, a practical 63 KV sub-transmission... 

    A Study of the Effects of Ultrasonic Vibration on the Stability of Orthogonal Cutting Process Against Chatter

    , M.Sc. Thesis Sharif University of Technology Yazdian, Mohammad (Author) ; Akbari, Javad (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor)
    Abstract
    Machining chatter is unstable and destructive vibrations that leads to damages to the surface of workpiece and reduces the tool life. These damages have significant effects on surface quality and material removal rate. Many studies have been done on chatter modeling and control in various machining processes. On the other hand, recently, ultrasonic vibrations have been used in many manufacturing processes including cutting to enhance the quality of products. Therefore, it is important to investigate the effect of ultrasonic vibrations on the stability of cutting process. Although a number of advantages such as improved surface roughness of workpiece and reduced machining forces have been... 

    Novel microfluidic graphene oxide–protein amperometric biosensor for detecting sulfur compounds

    , Article Biotechnology and Applied Biochemistry ; Volume 66, Issue 3 , 2019 , Pages 353-360 ; 08854513 (ISSN) Ghaemi, A ; Abdi, K ; Javadi, S ; Shehneh, M. Z ; Yazdian, F ; Omidi, M ; Rashedi, H ; Haghiralsadat, B. F ; Asayeshnaeini, O ; Sharif University of Technology
    Wiley-Blackwell Publishing Ltd  2019
    Abstract
    Sulfur compounds are essential for many industries and organisms; however, they cause serious respiratory problems in human beings. Therefore, determination of sulfur concentration is of paramount importance. The research approach in the field of detecting contaminants has led to smaller systems that provide faster and more effective ways for diagnosis purposes. In this study, a novel portable amperometric graphene oxide–protein biosensor platform is investigated. The main characteristic of this structure is the implementation of a microfluidic configuration. With albumin metalloprotein as the biorecognition element, graphene oxide was synthesized and characterized by transmission electron... 

    Graphene oxide-l-arginine nanogel: A pH-sensitive fluorouracil nanocarrier

    , Article Biotechnology and Applied Biochemistry ; Volume 66, Issue 5 , 2019 , Pages 772-780 ; 08854513 (ISSN) Malekimusavi, H ; Ghaemi, A ; Masoudi, G ; Chogan, F ; Rashedi, H ; Yazdian, F ; Omidi, M ; Javadi, S ; Haghiralsadat, B. F ; Teimouri, M ; Faal Hamedani, N ; Sharif University of Technology
    Wiley-Blackwell Publishing Ltd  2019
    Abstract
    Nowadays, putting forward an accurate cancer therapy method with minimal side effects is an important topic of research. Nanostructures, for their ability in controlled and targeted drug release on specific cells, are critical materials in this field. In this study, a pH-sensitive graphene oxide-l-arginine nanogel was synthesized to carry and release 5-fluorouracil. Optimized conditions using statistical analysis, based on the maximum relative viscosity of nanogel, were evaluated: 5.489 for the concentration of l-arginine and 2.404 for pH. The prepared nanogels were characterized using scanning electron microscope and transmission electron microscope images and Fourier-transform infrared... 

    Dose-dependent effects of nanoscale graphene oxide on reproduction capability of mammals

    , Article Carbon ; Volume 95 , December , 2015 , Pages 309-317 ; 00086223 (ISSN) Akhavan, O ; 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 Akhavan, O ; 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) Kashani, E. S ; 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...