Design of a bridgeless PFC with line-modulated fixed off-time current control and zero-voltage switching

, Article PECon2010 - 2010 IEEE International Conference on Power and Energy, 29 November 2010 through 1 December 2010 ; 2010 , Pages 129-134 ; 9781424489466 (ISBN) Haghi, R ; Zolghadri, M. R ; Nasirian, V ; Noroozi, N ; Sharif University of Technology

2010

Abstract

In this paper, the Line-Modulated Fixed Off-Time method is used as the current control strategy for a Power Factor Corrector (PFC) pre-regulator. A zero voltage switching PWM (ZVS-PWM) auxiliary circuit is configured to perform ZVS in the switches. Soft commutation of the main switch is achieved without additional current stress. A significant reduction in the total conduction loss is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path .The proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode...

Machine-Vision-Based Auotomatic Landing of Unmanned Helicopter

, M.Sc. Thesis Sharif University of Technology Nasirian, Behnam (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

In this project an algorithm is designed for automatic landing of unmanned helicopter on a pad moving with six degrees of freedom. The designed controller is based on state dependent riccati equations (SDRE).by developing nonlinear mathematical model of helicopter and then converting this model to state dependent coefficient (SDC) form. A nonlinear compensator is added to controller to compensate effect of some nonlinear terms of model that are not able to translate and then state dependent riccati equations are solved.
The relative pose-estimation of landing pad is based on vision. Corner detection algorithm is used to identify and detect features by processing of image taken from...

Small-signal modeling and fast response control strategy for DCVM Cúk converters in PFC applications.انجام شد

, Article Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC ; 2011 , Pages 1795-1802 ; 9781424480845 (ISBN) Nasirian, V. R ; Karimi, Y ; Zolghadri, M. R ; Ahmadian, M ; Moayedi, A ; Davoudi, A ; Sharif University of Technology

2011

Abstract

Cúk Converter operating in discontinuous capacitor voltage mode is an inherent PFC converter in which, unity power factor can be achieved using constant duty cycle and switching frequency. In this paper, a reduced-order switch network modeling technique is applied to Cúk converter operating in DCVM in order to derive small-signal model of the converter assuming a dc voltage source as the input source of the converter. This model is extended to derive the small-signal behavior of the converter while operating as a PFC converter. The validity of the proposed model is confirmed by both simulation and experimental results. Afterwards, a new control strategy is proposed in which switching...

A novel model for three-dimensional imaging using interferometric ISAR in any curved target flight path

, Article IEEE Transactions on Geoscience and Remote Sensing ; Vol. 52, issue. 6 , 2014 , pp. 3236-3245 ; ISSN: 01962892 Nasirian, M ; Bastani, M. H ; Sharif University of Technology

2014

Abstract

Using a second receiver antenna close to the main transceiver antenna of inverse synthetic aperture radar (ISAR), it is possible to find 3-D positions of target scattering points. Such system is called bistatic, monopulse, or interferometric ISAR (InISAR). In the conventional model of ISAR, the unknown flying object should have a linear trajectory, and only small deviations from this trajectory can be compensated. Target motions which are highly nonlinear or curvy cannot be used in the conventional model. In this paper, we propose a new model for InISAR to process all collected data from the target, regardless of the form of the flight path. More accuracy is achieved for 3-D positioning of...

Output power maximization and optimal symmetric freewheeling excitation for switched reluctance generators

, Article IEEE Transactions on Industry Applications ; Volume 49, Issue 3 , 2013 , Pages 1031-1042 ; 00939994 (ISSN) Nasirian, V ; Kaboli, S ; Davoudi, A ; Sharif University of Technology

2013

Abstract

Space constraint is a limiting factor for the widespread commercial adaptation of switched reluctance generators (SRGs). Maximizing the output power and minimizing the dc bus filter size are thus highly desired. The output power profiles of a typical SRG are determined by applying various excitation angles. Excitation for maximum output power is obtained while limiting the rms value of the phase currents. The dc bus current of an SRG drive, operating in single pulse mode, is highly distorted by low-frequency ripples. Introducing a freewheeling angle in the excitation pattern can lower the current ripple factor. A novel transform is proposed to establish a relationship between the...

Feasibility of a novel beamforming algorithm via retrieving spatial harmonics

, Article Journal of Systems Engineering and Electronics ; Volume 33, Issue 1 , 2022 , Pages 38-46 ; 16711793 (ISSN) Norolahi, J ; Azmi, P ; Nasirian, M ; Sharif University of Technology

Beijing Institute of Aerospace Information 2022

Abstract

This paper introduces an algorithm for beamforming systems by the aid of multidimensional harmonic retrieval (MHR). This algorithm resolves problems, removes limitations of sampling and provides a more robust beamformer. A new sample space is created that can be used for estimating weights of a new beamforming called spatial-harmonics retrieval beamformer (SHRB). Simulation results show that SHRB has a better performance, accuracy, and applicability and more powerful eigenvalues than conventional beamformers. A simple mathematical proof is provided. By changing the number of harmonics, as a degree of freedom that is missing in conventional beamformers, SHRB can achieve more optimal outputs...

Nonlinear Modeling and Control of Switched Reluctance Generator for Maximum

, M.Sc. Thesis Sharif University of Technology Nasirian, Vahid Reza (Author) ; Kaboli, Shahriyar (Supervisor)

Abstract

Switched Reluctance Generator (SRG) has some unique features such as low cost, simple and rugged structure and high performance operation in wide range of speed. These features make the SRG one of the best candidates for optimum power generation. SRG has used as starter-alternator in Hybrid Electric Vehicles (HEV) and aircrafts. An SRG drive system operates by exciting the SRG phases with a DC voltage source and then discharging the stored and developed magnetic energy to the connected DC supply. Therefore, output power of a Switched Reluctance Generator directly depends on the excitation angles when operates in the Single Pulse Mode. In this dissertation the goal is to control a SRG in the...

A Novel Model for Three-Dimensional Imaging Using Interferometric ISAR in Curved Target Flight Paths

, Ph.D. Dissertation Sharif University of Technology Nasirian, Mahdi (Author) ; Bastani, Mohammad Hasan (Supervisor)

Abstract

A Synthetic Aperture Radar (SAR) is a system which collects the received signal from a ground target area along linear motion of a flying vehicle carrying it, in order to provide a very high resolution 2D image of it. In Inverse SAR (ISAR), the radar is fixed on the ground and the data collection is performed along the linear motion of the aerial target. Using a second receiver antenna close to the main transceiver antenna of ISAR, it is possible to make a three-dimensional (3D) image of the target, or equivalently find the 3D coordinates of the target scattering points. Such system is called bistatic, monopulse or interferometric ISAR (InISAR). In the conventional model of ISAR, the flying...

High-fidelity magnetic characterization and analytical model development for switched reluctance machines

, Article IEEE Transactions on Magnetics ; Volume 49, Issue 4 , 2013 , Pages 1505-1515 ; 00189464 (ISSN) Nasirian, V ; Kaboli, S ; Davoudi, A ; Moayedi, S ; Sharif University of Technology

2013

Abstract

This paper proposes a new experimental procedure for magnetic characterization of switched reluctance machines. In the existing methods, phase voltage and current data are captured and further processed to find the flux linkage. Conventionally, assuming zero initial flux value, the flux linkage can be found by integrating the corresponding voltage term. However, the initial flux value is usually unknown, e.g., it can be nonzero when the current is zero due to the residual flux effect, and, thus, imposes error in magnetic characterization. The proposed method addresses this issue by considering an additional equation in steady state. This method injects a low-frequency sinusoidal current to...

Excitation shifting: A general low-cost solution for eliminating ultra-low-frequency torque ripple in switched reluctance machines

, Article IEEE Transactions on Magnetics ; Volume 49, Issue 9 , Sept , 2013 , Pages 5135-5149 ; 00189464 (ISSN) Nasirian, V ; Davoudi, A ; Kaboli, S ; Edrington, C. S ; Sharif University of Technology

2013

Abstract

Switched reluctance machines (SRMs) suffer from ultra-low-frequency torque ripple in single pulse mode. This ripple is the result of an imbalance in phase currents, when multiphase excitation occurs. This paper investigates the origin of this imbalance and identifies the imbalanced phase. Excitation shifting strategy, which delays excitation of the imbalanced phase, is then proposed. The delay angle adjusts current amplitude in the imbalanced phase to attain a perfect balance between all phases. The excitation shifting strategy is a general solution, which is applicable to both three-phase and four-phase machines. In addition, the proposed method can be implemented by a much simpler drive...

Dynamic model development and variable switching-frequency control for DCVM Cúk converters in PFC applications

, Article IEEE Transactions on Industry Applications ; Volume 49, Issue 6 , 2013 , Pages 2636-2650 ; 00939994 (ISSN) Nasirian, V ; Karimi, Y ; Davoudi, A ; Zolghadri, M. R ; Ahmadian, M ; Moayedi, S ; Sharif University of Technology

2013

Abstract

A Cúk converter operating in discontinuous capacitor voltage mode (DCVM) is an inherent power factor correction converter. A reduced-order switch-network model of a Cúk converter in DCVM is developed, which is valid for both dc-dc and ac-dc applications. The model can be used for controller analysis and design. Moreover, a fast dynamic response controller is proposed, which is an integration of a switching-frequency control unit and a proportional-integral (PI) controller. The PI controller is in charge of duty ratio adjustment. In the proposed controller, unlike conventional PI controllers, switching frequency is no longer fixed and varies as load changes. The switching-frequency control...

Advancement of sensor integrated organ-on-chip devices

, Article Sensors (Switzerland) ; Volume 21, Issue 4 , 2021 , Pages 1-44 ; 14248220 (ISSN) Clarke, G.A ; Hartse, B. X ; Niaraki Asli, A. E ; Taghavimehr, M ; Hashemi, N ; Abbasi Shirsavar, M ; Montazami, R ; Alimoradi, N ; Nasirian, V ; Ouedraogo, L. J ; Hashemi, N. N ; Sharif University of Technology

MDPI AG 2021

Abstract

Organ-on-chip devices have provided the pharmaceutical and tissue engineering worlds much hope since they arrived and began to grow in sophistication. However, limitations for their applicability were soon realized as they lacked real-time monitoring and sensing capabilities. The users of these devices relied solely on endpoint analysis for the results of their tests, which created a chasm in the understanding of life between the lab the natural world. However, this gap is being bridged with sensors that are integrated into organ-on-chip devices. This review goes in-depth on different sensing methods, giving examples for various research on mechanical, electrical resistance, and bead-based...

NIR emitting platinum pincer complexes based on the N^N^C ligand containing {benz[4,5]imidazo[1,2-a]pyrazin} aromatic system; synthesis, characterization and photophysical study

, Article Inorganica Chimica Acta ; Volume 511 , 2020 Shakirova, J. R ; Hendi, Z ; Zhukovsky, D. D ; Sokolov, V. V ; Jamali, S ; Pavlovskiy, V. V ; Porsev, V. V ; Evarestov, R. A ; Tunik, S. P ; Sharif University of Technology

Elsevier S.A 2020

Abstract

In the present work we obtained a series of NIR luminescent platinum(II) complexes with a pincer N^N^C ligand based on the conjugated {benzoimidazo[1,2-a]pyrazine} system with the [Pt(N^N^C)L]n+ structural motif (L = phosphine, alkynyl or pyridine-type ligands). We have also synthesized two complexes with bidentate phosphines that demonstrate different types of coordination: 1) as chelating ligand (in case of 1,2-bis(diphenylphosphino)benzene), that led to de-coordination of pyridine ring of N^N^C ligand and formation of a [Pt(N^C)dppb]+ complex; 2) as a bridging ligand (in case of bis(diphenylphosphino)methane) between two {Pt(N^N^C)} fragments in a dimeric complex of type...

Targeted synthesis of NIR luminescent rhenium diimine cis,trans-[Re(NN)(CO)2(L)2]n+ complexes containing N-Donor axial ligands: photophysical, electrochemical, and theoretical studies

, Article ChemPlusChem ; Volume 85, Issue 11 , 2020 , Pages 2518-2527 Shakirova, J. R ; Nayeri, S ; Jamali, S ; Porsev, V. V ; Gurzhiy, V. V ; Levin, O. V ; Koshevoy, I. O ; Tunik, S. P ; Sharif University of Technology

Wiley-VCH Verlag 2020

Abstract

The combined action of ultraviolet irradiation and microwave heating onto acetonitrile solution of [Re((Formula presented.))(CO)3(NCMe)]OTf ((Formula presented.) =phenantroline and neocuproine) afforded cis,trans-Re((Formula presented.))(CO)2(NCMe)2]+ acetonitrile derivatives. Substitution of relatively labile NCMe with a series of aromatic N-donor ligands (pyridine, pyrazine, 4,4’-bipyridine, N-methyl-4,4’-bipyridine) gave a novel family of the diimine cis,trans-[Re((Formula presented.))(CO)2(L)2]+ complexes. Photophysical studies of the obtained compounds in solution revealed unusually high absorption across the visible region and NIR phosphorescence with emission band maxima ranging from...

Spectra of Deza graphs

, Article Linear and Multilinear Algebra ; 2020 Akbari, S ; Ghodrati, A. H ; Hosseinzadeh, M. A ; Kabanov, V. V ; Konstantinova, E. V ; Shalaginov, L. V ; Sharif University of Technology

Taylor and Francis Ltd 2020

Abstract

A Deza graph with parameters (n, k, b, a) is a k-regular graph with n vertices such that any two of its vertices have b or a common neighbours, where b ≥ a. In this paper we investigate spectra of Deza graphs. In particular, using the eigenvalues of a Deza graph we determine the eigenvalues of its children. Divisible design graphs are significant cases of Deza graphs. Sufficient conditions for Deza graphs to be divisible design graphs are given, a few families of divisible design graphs are presented and their properties are studied. Our special attention goes to the invertibility of the adjacency matrices of Deza graphs. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group

Spectra of deza graphs

, Article Linear and Multilinear Algebra ; Volume 70, Issue 2 , 2022 , Pages 310-321 ; 03081087 (ISSN) Akbari, S ; Ghodrati, A. H ; Hosseinzadeh, M. A ; Kabanov, V. V ; Konstantinova, E. V ; Shalaginov, L. V ; Sharif University of Technology

Taylor and Francis Ltd 2022

Abstract

A Deza graph with parameters (Formula presented.) is a k-regular graph with n vertices such that any two of its vertices have b or a common neighbours, where (Formula presented.). In this paper we investigate spectra of Deza graphs. In particular, using the eigenvalues of a Deza graph we determine the eigenvalues of its children. Divisible design graphs are significant cases of Deza graphs. Sufficient conditions for Deza graphs to be divisible design graphs are given, a few families of divisible design graphs are presented and their properties are studied. Our special attention goes to the invertibility of the adjacency matrices of Deza graphs. © 2020 Informa UK Limited, trading as Taylor &...

Adsorption of proteins at the solution/air interface influenced by added nonionic surfactants at very low concentrations for both components. 3. dilational surface rheology

, Article Journal of Physical Chemistry B ; Volume 119, Issue 9 , January , 2015 , Pages 3768-3775 ; 15206106 (ISSN) Fainerman, V. B ; Aksenenko, E. V ; Lylyk, S. V ; Lotfi, M ; Miller, R ; Sharif University of Technology

2015

Abstract

The influence of the addition of the nonionic surfactants C12DMPO, C14DMPO, C10OH, and C10EO5 at concentrations between 10-5 and 10-1 mmol/L to solutions of β-casein (BCS) and β-lactoglobulin (BLG) at a fixed concentration of 10-5 mmol/L on the dilational surface rheology is studied. A maximum in the viscoelasticity modulus |E| occurs at very low surfactant concentrations (10-4 to 10-3 mmol/L) for mixtures of BCS with C12DMPO and C14DMPO and for mixtures of BLG with C10EO5, while for mixture of BCS with C10EO5 the value of |E| only slightly increased. The |E| values...

Treatment of beet sugar wastewater by UAFB bioprocess

, Article Bioresource Technology ; Volume 98, Issue 16 , 2007 , Pages 3080-3083 ; 09608524 (ISSN) Farhadian, M ; Borghei, M ; Umrania, V. V ; Sharif University of Technology

2007

Abstract

The aim of this work was to study the treatment of strong beet sugar wastewater by an upflow anaerobic fixed bed (UAFB) at pilot plant scale. Three fixed bed bioreactors (each 60 L) were filled with standard industrial packing, inoculated with anaerobic culture (chicken manure, cow manure, anaerobic sludge digested from domestic wastewater) and operated at 32-34 °C with 20 h hydraulic retention time (HRT) and influent COD ranging between 2000-8000 mg/L. Under these conditions the maximum efficiency of organic content reduction in the reactor ranged from 75% to 93%. The reactor filled with standard pall rings made of polypropylene with an effective surface area of 206 m2/m3 performed best in...

GHZ states as near-optimal states for reference frame alignment

, Article Quantum Information Processing ; Volume 20, Issue 10 , 2021 ; 15700755 (ISSN) Koochakie, M. M. R ; Jannesary, V ; Karimipour, V ; Sharif University of Technology

Springer 2021

Abstract

Let two coordinate systems, in possession of Alice and Bob, be related to each other by an unknown rotation R∈ SO (3). Alice is to send identical states | ψ⟩ to Bob who will make measurements on the received state and will determine the rotation R. The task of Bob is to estimate these parameters of the rotation R by the best possible measurements. Based on the quantum Fisher information, we show that Greenberger–Horne–Zeilinger (GHZ) states are near optimal states for this task. We show concrete measurements which will allow Bob to determine the rotation R. This shows that GHZ states, as superposition of macroscopically distinct states, are useful in yet another context in quantum...

Spectra of strongly Deza graphs

, Article Discrete Mathematics ; Volume 344, Issue 12 , 2021 ; 0012365X (ISSN) Akbari, S ; Haemers, W. H ; Hosseinzadeh, M. A ; Kabanov, V. V ; Konstantinova, E. V ; Shalaginov, L ; Sharif University of Technology

Elsevier B.V 2021

Abstract

A Deza graph G with parameters (n,k,b,a) is a k-regular graph with n vertices such that any two distinct vertices have b or a common neighbours. The children GA and GB of a Deza graph G are defined on the vertex set of G such that every two distinct vertices are adjacent in GA or GB if and only if they have a or b common neighbours, respectively. A strongly Deza graph is a Deza graph with strongly regular children. In this paper we give a spectral characterisation of strongly Deza graphs, show relationships between eigenvalues, and study strongly Deza graphs which are distance-regular. © 2021 Elsevier B.V