Loading...
Search for:
nasirian--v--r
0.118 seconds
Total 8571 records
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) ; 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...
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) ; 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...
Machine-Vision-Based Auotomatic Landing of Unmanned Helicopter
, M.Sc. Thesis Sharif University of Technology ; 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...
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...
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 ; 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...
Development of a Biomechanical Model of the Exoped Robot with a User and a Cane
, M.Sc. Thesis Sharif University of Technology ; Behzadipour, Saeed (Supervisor)
Abstract
In this study, a forward dynamics model of the human–lower limb exoskeleton system (ExoPed model) incorporating an instrumented cane was developed to enable simulation of user–system biomechanical interactions and comparison with experimentally measured data. First, a cane equipped with a uniaxial load cell was designed and implemented, capable of measuring the axial force in real time and transmitting it wirelessly to a computer. Subsequently, motion data of the user wearing the exoskeleton and using the cane were collected through a precise marker-based protocol using a three-dimensional motion capture system during walking trials. A full-body dynamic model, including the upper body, lower...
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) ; 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...
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) ; 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) ; 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 ; 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 ; 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) ; 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...
Advancement of sensor integrated organ-on-chip devices
, Article Sensors (Switzerland) ; Volume 21, Issue 4 , 2021 , Pages 1-44 ; 14248220 (ISSN) ; 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...
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) ; 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...
Using VR in Adaptive Teaching the Optimal Use of Water and Energy to Children
, Article ICRoM 2024 - 12th RSI International Conference on Robotics and Mechatronics ; 2024 , Pages 244-249 ; 979-833152973-4 (ISBN) ; Hosseini, M ; Amiri, O ; Meghdari, A. F ; Taheri, A ; Sharif University of Technology
2024
Abstract
As global population growth and technological advancements increase the demand for natural resources, the optimal use of water and energy is becoming essential, especially as these resources face overconsumption and climate change-related scarcity. Educating children about resource conservation is critical for fostering environmental awareness in future generations. In response, we developed a game-based learning environment that uses Virtual Reality (VR) and adaptive learning algorithms to teach children aged 7-9 about water and energy conservation. Sixteen children (8 boys and 8 girls) participated in two - 15-minute VR sessions on separate days. Between these sessions, participants...
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) ; 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 C12 DMPO, C14 DMPO, C10 OH, and C10 EO5 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 C12 DMPO and C14 DMPO and for mixtures of BLG with C10 EO5 , while for mixture of BCS with C10 EO5 the value of |E| only slightly increased. The |E| values...
A rare type of Rhenium(I) diimine complexes with unsupported coordinated phosphine oxide ligands: Synthesis, Structural Characterization, Photophysical and theoretical study
, Article European Journal of Inorganic Chemistry ; Volume 2019, Issue 39-40 , 2019 , Pages 4350-4357 ; 14341948 (ISSN) ; Jamali, S ; Pavlovskiy, V. V ; Porsev, V. V ; Evarestov, R. A ; Kisel, K. S ; Koshevoy, I. O ; Shakirova, J. R ; Tunik, S. P ; Sharif University of Technology
Wiley-VCH Verlag
2019
Abstract
This paper presents synthesis and photophysical investigation of a very rare type of the ReI diimine complexes, [Re(diimine)(CO)3(OPR3)]+, R = Ph, Cy; diimine – phenanthroline and neocuproine, containing monodentate (unsupported) phosphine oxide ligands. The obtained compounds have been structurally characterized in solid phase by using XRD crystallography, which revealed unusual distortions in the pseudo octahedral rhenium environment, which may be ascribed to intramolecular interligand (phosphine oxide – diimine) interaction rather than to crystal packing effect. Optimization of the ground state structure of these molecules with the DFT method also confirmed intramolecular origin of the...
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 ; 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...
Microstructure evolution and mechanical properties analysis in dissimilar ultrasonic metal welding of aluminum to copper
, Article Journal of Materials Research and Technology ; Volume 30 , 2024 , Pages 2922-2935 ; 22387854 (ISSN) ; Kokabi, A. H ; Abedini, R ; Fartashvand, V ; Allahverdizadeh, V ; Sharif University of Technology
2024
Abstract
Ultrasonic metal welding is a solid-state welding process being widely employed for joining the interconnections of lithium-ion batteries in hybrid and plug-in hybrid vehicles. Examining the microstructure of the joint is of crucial importance to evaluate the performance. This analysis allows a comprehensive understanding of the phenomena influencing the joint strength. In this study, ultrasonic welding was utilized to join copper to aluminum sheets of 0.3 mm thickness, and then the macro- and microstructural characteristics of the weld cross-section and interface were thoroughly investigated. Finally, the microstructural changes at different values of ultrasonic welding parameters were...
Investigation of process parameters on the mechanical strength in ultrasonic metal welding of aluminum to copper dissimilar joints
, Article Transactions of the Indian Institute of Metals ; Volume 77, Issue 11 , 2024 , Pages 3707-3718 ; 09722815 (ISSN) ; Kokabi, A. H ; Abedini, R ; Fartashvand, V ; Allahverdizadeh, V ; Sharif University of Technology
2024
Abstract
As a solid-state welding method, ultrasonic welding of metals is widely used in different industries to produce high-performance materials such as lithium-ion batteries. This research aims to investigate and optimize the variables of ultrasonic metal welding to reach a maximum joint strength. The influence of welding time, welding pressure, and oscillation amplitude on the maximum load of tensile-shear and T-peel tests of dissimilar ultrasonic metal welding of aluminum 1050 and copper (purity above 99.9%) having a thickness of 0.3 mm has been investigated. Design Expert software and response surface method (RSM) have been used to obtain the optimal mode of welding parameters and check their...
The tendency towards equalization of the 234U/238U isotopic activity ratios in fractions of U(IV) and U(VI) during thermal annealing of metamict polycrase
, Article Applied Geochemistry ; Volume 161 , 2024 ; 08832927 (ISSN) ; Bogdanov, R. V ; Titov, A. V ; Fomin, E. V ; Samadfam, M ; Outokesh, M ; Sharif university of Technology
2024
Abstract
The fate of the immobilized actinides of the spent nuclear fuel in mineral-like matrices can be predicted by studying the behavior of uranium isotopes as representatives of the actinides in natural analogues. This work deals with the thermochemical behavior of uranium isotopes, which is accompanied by a redox process within the 25–800 °C temperature range in the metamict natural analogue of polycrase. The pattern of the changes in the relative contents of the U(IV) and U(VI) fractions at various temperatures was determined by a radiochemical analysis. The accuracy of the U(IV) and U(VI) values using the method of the chemical shift of the energy on the Lα1 X-ray emission line was verified....