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Total 105 records
Design guidelines for a tunable SOI based optical isolator in a partially time-modulated ring resonator
, Article IEEE Photonics Journal ; Volume 14, Issue 5 , 2022 ; 19430655 (ISSN) ; Mehrany, K ; Memarian, M ; Jamshidi, K ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
In this paper, we present the design guidelines for a tunable optical isolator in an SOI-based ring resonator with two small time-modulated regions. By considering a physical model, the proper geometrical and modulation parameters are designed, based on a standard CMOS foundry process. The effect of the variation of the key parameters on the performance of the isolator is explained by two counter-acting mechanisms, namely the separation between the resonance frequencies of counter-rotating modes and energy transfer to the side harmonic. We show that there is a trade-off between these parameters to obtain maximum isolation. Consequently, by applying the quadrature phase difference one can...
Voltage balancing of series IGBTs in short-circuit conditions
, Article IEEE Transactions on Power Electronics ; Volume 37, Issue 5 , 2022 , Pages 5675-5686 ; 08858993 (ISSN) ; Peyghami, S ; Iannuzzo, F ; Blaabjerg, F ; Kaboli, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
This article proposes a scheme for balancing the voltage of series-connected insulated gate bipolar transistors (IGBTs), which is also very effective under short-circuit conditions. An optimized clamp-mode snubber is proposed, including an active-driver to balance the currents of the IGBTs during short-circuit, which in turn allows for a considerable reduction of the snubber capacitance. The approach is proven to be effective under short-circuit conditions by a maximum of 55 V voltage increment and a negligible difference in the current values. The effectiveness of the proposed approach is demonstrated through simulations in PSPICE software and experimental tests performed at 2 kV. ©...
Chaos and its degradation-promoting-based control in an antithetic integral feedback circuit
, Article IEEE Control Systems Letters ; Volume 6 , 2022 , Pages 1622-1627 ; 24751456 (ISSN) ; Tavazoei, M. S ; Kuznetsov, N. V ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
This letter deals with a novel variant of antithetic integral feedback controller (AIFC) motifs which can feature robust perfect adaptation, a pervasive (desired) ability in natural (synthetic) biomolecular circuits, when coupled with a wide class of process networks to be regulated. Using the separation of time-scales in the proposed kind of AIFC, here we find a reduced-order controller that captures the governing slow part of the original solutions under suitable assumptions. Inspired by Rössler systems, we then make use of such a simpler controller to show that the antithetic circuit can exhibit chaotic behaviors with strange attractors, where the bifurcation from a homeostatic state to...
Decomposition and robust non-fragile stabilisation of singular time-delay systems
, Article IET Control Theory and Applications ; Volume 12, Issue 13 , 2018 , Pages 1882-1888 ; 17518644 (ISSN) ; Haeri, M ; Sharif University of Technology
Abstract
This study presents a new approach to decompose singular time-delay systems (STDSs) in a way that they can be transformable to normal time-delay systems (TDSs) with a lower order. Necessary and sufficient conditions are provided to determine which STDSs can be transformed to TDSs. Also, a stabilisation method is provided to stabilise the system, while the time delay in the system can belong to several distinct intervals or even everywhere. The proposed method is non-fragile towards controller parameters. This method also reveals one of the many applicable situations of the proposed decomposition. The effectiveness of the proposed method is illustrated through some examples. © 2018 The...
Asymptotic stability of linear descriptor systems with time-delay by designing delay margin
, Article 5th International Conference on Control, Instrumentation, and Automation, ICCIA 2017 ; Volume 2018-January , 2018 , Pages 23-29 ; 9781538621349 (ISBN) ; Haeri, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In this paper a new approach is developed to stabilize descriptor systems with time-delay, while time-delay can belong to a given interval. This approach takes the advantages of system's singularity to simplify the model and uses the so-called Rekasius substitution to compute the controller parameters in a way that the asymptotic stability of the closed-loop system in the given interval of the delay can be guaranteed. Finally, a numerical example is provided to evaluate the proposed method's effectiveness. © 2017 IEEE
Improvement of operator position prediction in teleoperation systems with time delay: Simulation and experimental studies on Phantom Omni devices
, Article Jordan Journal of Mechanical and Industrial Engineering ; Volume 13, Issue 3 , 2019 , Pages 197-205 ; 19956665 (ISSN) ; Nikpour, M ; Beigzadeh, B ; Meghdari, A ; Sharif University of Technology
Hashemite University
2019
Abstract
An online operator position prediction approach based on artificial neural network for teleoperation systems is proposed in this paper, which predicts future position of operator's hand based on current available data. The neural network gathers inputs for some time at the beginning of the operation, then is trained, and is finally exploited through the rest of the operation. Superiority of the proposed approach can be investigated from two aspects. Firstly, no limiting assumption is required in this approach in contrast with the proposed methods in the literature. Secondly, unknown operator intention can be dealt with in real time if it is not too sudden and unpredictable. Two different...
Secure two-party computation using an efficient garbled circuit by reducing data transfer
, Article 8th International Conference on Applications and Techniques in Information Security, ATIS 2017, 6 July 2017 through 7 July 2017 ; Volume 719 , 2017 , Pages 23-34 ; 18650929 (ISSN); 9789811054204 (ISBN) ; Farzam, M. H ; Bayat Sarmadi, S ; Sharif University of Technology
Springer Verlag
2017
Abstract
Secure computation has obtained significant attention in the literature recently. Classic architectures usually use either the Garbled Circuit (GC) or the Goldreich-Micali-Wigderson (GMW) protocols. So far, to reduce the complexity of communications in these protocols, various methods have been proposed. The best known work in both methods reduces the communication up to almost 2k-bits (k is the symmetric security parameter) for each AND gate, and using XOR gate is free. In this paper, by combining GC and GMW, we propose a scheme in the semi-honest adversary model. This scheme requires an Oblivious Transfer (OT) and a 2-bit data transfer for each AND gate, keeping XOR gates free. The...
Short-circuit analysis in three-phase quasi-Z-source inverter
, Article 17th IEEE International Conference on Environment and Electrical Engineering and 2017 1st IEEE Industrial and Commercial Power Systems Europe, EEEIC / I and CPS Europe 2017, 6 June 2017 through 9 June 2017 ; 2017 ; 9781538639160 (ISBN) ; Moghani, J. S ; Noroozi, N ; Zolghadri, M. R ; IEEE EMC Society; IEEE Industry Applications Society (IAS); IEEE Power and Energy Society (PES) ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
In this paper, the short-circuit fault in three-phase quasi-Z-source inverter (q-ZSI) is analyzed and a linear model is proposed for the short-circuit analysis. The proposed model is based on the state space equations of the system. By using this model, the most critical situation during short-circuit fault is recognized; the maximum reaction time for the protection system could be estimated and elements that are prone to failure are identified as well. The analysis is categorized into two groups, leg fault and switch fault. The linear model is confirmed by simulation of 1kw three-phase q-ZSI. © 2017 IEEE
IGBT open-circuit fault diagnosis in a Quasi-Z-source inverter
, Article IEEE Transactions on Industrial Electronics ; Volume 66, Issue 4 , 2019 , Pages 2847-2856 ; 02780046 (ISSN) ; Shokrollahi Moghani, J ; Noroozi, N ; Zolghadri, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In this paper, a fast and practical method is proposed for open-circuit (OC) fault diagnosis (FD) in a three-phase quasi-Z-source inverter (q-ZSI). Compared to the existing fast OC FD techniques in three-phase voltage-source inverters (VSIs), this method is more cost-effective since no ultra-fast processor or high-speed measurement is required. Additionally, the method is independent of the load condition. The proposed method is only applicable to Z-source family inverters and is based on observing the effect of shoot-through (SH) intervals on the system variables during switching periods. The proposed algorithm includes two consecutive stages: OC detection and fault location identification....
IGBT Open-circuit fault diagnosis in a quasi-z-source inverter
, Article IEEE Transactions on Industrial Electronics ; Volume 66, Issue 4 , 2019 , Pages 2847-2856 ; 02780046 (ISSN) ; Moghani, J. S ; Noroozi, N ; Zolghadri, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, a fast and practical method is proposed for open-circuit (OC) fault diagnosis (FD) in a three-phase quasi-Z-source inverter (q-ZSI). Compared with the existing fast OC FD techniques in three-phase voltage source inverters, this method is more cost-effective since no ultrafast processor or high-speed measurement is required. Additionally, the method is independent of the load condition. The proposed method is only applicable to Z-source family inverters and is based on observing the effect of shoot-through intervals on the system variables during switching periods. The proposed algorithm includes two consecutive stages: OC detection and fault location identification. When both...
Surface engineering of TiO2 ETL for highly efficient and hysteresis-less planar perovskite solar cell (21.4%) with enhanced open-circuit voltage and stability
, Article Advanced Energy Materials ; Volume 8, Issue 23 , 2018 ; 16146832 (ISSN) ; Yadav, P ; Tavakoli, R ; Kong, J ; Sharif University of Technology
Wiley-VCH Verlag
2018
Abstract
Interfacial studies and band alignment engineering on the electron transport layer (ETL) play a key role for fabrication of high-performance perovskite solar cells (PSCs). Here, an amorphous layer of SnO2 (a-SnO2) between the TiO2 ETL and the perovskite absorber is inserted and the charge transport properties of the device are studied. The double-layer structure of TiO2 compact layer (c-TiO2) and a-SnO2 ETL leads to modification of interface energetics, resulting in improved charge collection and decreased carrier recombination in PSCs. The optimized device based on a-SnO2/c-TiO2 ETL shows a maximum power conversion efficiency (PCE) of 21.4% as compared to 19.33% for c-TiO2 based device....
Modification of the infinite-dimensional neutral-type time-Delay dynamic model for the coupled axial⇓torsional vibrations in drill strings with a drag bit
, Article Journal of Computational and Nonlinear Dynamics ; Volume 15, Issue 8 , 2020 ; Vossoughi, G ; Zohoor, H ; Azadi Yazdi, E ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2020
Abstract
Drill strings are subjected to complex coupled dynamics. Therefore, accurate dynamic modeling, which can represent the physical behavior of real drill strings, is of great importance for system analysis and control. The most widely used dynamic models for such systems are the lumped element models, which neglect the system distributed feature. In this paper, a dynamic model called neutral-type time delay model is modified to investigate the coupled axial–torsional vibrations in drill strings. This model is derived directly from the distributed parameter model by employing the d’Alembert method. Coupling of axial and torsional vibration modes occurs in the bit–rock interface. For the first...
A search for transit timing variations in the HATS-18 planetary system
, Article Monthly Notices of the Royal Astronomical Society ; Volume 515, Issue 3 , 2022 , Pages 3212-3223 ; 00358711 (ISSN) ; Barker, A. J ; Hinse, T. C ; Jongen, Y ; Dominik, M ; Jørgensen, U. G ; Longa-Peña, P ; Sajadian, S ; Snodgrass, C ; Tregloan-Reed, J ; Bach-Møller, N ; Bonavita, M ; Bozza, V ; Burgdorf, M. J ; Figuera Jaimes, R ; Helling, Ch ; Hitchcock, J. A ; Hundertmark, M ; Khalouei, E ; Korhonen, H ; Mancini, L ; Peixinho, N ; Rahvar, S ; Rabus, M ; Skottfelt, J ; Spyratos, P ; Sharif University of Technology
Oxford University Press
2022
Abstract
HATS-18 b is a transiting planet with a large mass and a short orbital period, and is one of the best candidates for the detection of orbital decay induced by tidal effects. We present extensive photometry of HATS-18 from which we measure 27 times of mid-transit. Two further transit times were measured from data from the Transiting Exoplanet Survey Satellite (TESS) and three more taken from the literature. The transit timings were fitted with linear and quadratic ephemerides and an upper limit on orbital decay was determined. This corresponds to a lower limit on the modified stellar tidal quality factor of $Q_star ^{, prime } gt 10^{5.11 pm 0.04}$. This is at the cusp of constraining the...
3D-DPS: An efficient 3D-CAC for reliable data transfer in 3D ICs
, Article Proceedings - 2016 12th European Dependable Computing Conference, EDCC 2016, 5 September 2016 through 9 September 2016 ; 2016 , Pages 97-107 ; 9781509015825 (ISBN) ; Rohbani, N ; Miremadi, S. G ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
Migration to Three Dimensional Integrated Circuits (3D ICs) can provide higher scalability, higher throughput, and lower power consumption with respect to Two Dimensional Integrated Circuits (2D ICs). Also, the latency bottleneck of interconnections in 2D ICs is efficiently solved in 3D ICs. This is due to the use of Through-Silicon-Vias (TSVs) in the communication structure of 3D ICs. TSVs are among the efficient fabrication mechanisms that connect stacked layers in 3D ICs. However, proximity and large size of TSVs make them highly prone to crosstalk faults. Crosstalk faults can cause mutual undesired influences between TSVs and thus seriously threat the reliability of data transfer on...
AM3D: An accurate crosstalk probability modeling to predict channel delay in 3D ICs
, Article Microelectronics Reliability ; Volume 102 , 2019 ; 00262714 (ISSN) ; Nikoofard, A ; Ershadi, G ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Migration from Two Dimensional Integrated Circuits (2D ICs) to Three Dimensional Integrated Circuits (3D ICs) reduces the delay due to the shorter wire length between sender and receiver. However, Through-Silicon-Vias (TSVs) that connect layers in the structure of 3D ICs can seriously increase the delay due to capacitance coupling between TSVs and lead to crosstalk fault. The severity of crosstalk faults depends on transitions appearing on TSVs that is called transition patterns. To propose an efficient crosstalk tackling mechanisms in 3D ICs, an accurate probability analytical model is required to predict the delay caused by TSVs (3D ICs) in the attendance of these transition patterns. In...
Impedance control of non-linear multi-DOF teleoperation systems with time delay: absolute stability
, Article IET Control Theory and Applications ; Volume 12, Issue 12 , 2018 , Pages 1722-1729 ; 17518644 (ISSN) ; Salarieh, H ; Behzadipour, S ; Tavakoli, M ; Sharif University of Technology
Abstract
A non-linear robust adaptive bilateral impedance controller is proposed to provide the absolute stability of multi-DOF teleoperation systems with communication delays, in addition to the force and position tracking performance. The proposed controller realises two desired (or reference) impedance models for the master and slave robots using a new non-linear robust version of the model reference adaptive control scheme. Using the absolute stability criterion, the robustness condition of the teleoperation system against communication delays is obtained, resulting in suitable adjustments of parameter values in the desired impedance models. In addition, using the Lyapunov stability theorem, the...
Integrated monolayer planar flux transformer and resonator tank circuit for high-$t-{c}$ rf-squid magnetometer
, Article IEEE Transactions on Applied Superconductivity ; Volume 27, Issue 4 , 2017 ; 10518223 (ISSN) ; Jabbari, T ; Qaderi, F ; Fardmanesh, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
The authors propose a new design for monolayer superconducting planar flux transformer integrated with a coplanar resonator serving as a gigahertz range tank circuit for high-Tc rf-SQUID magnetometers. Based on the proposed design, which is optimized using the finite element method, the transformer-resonator configuration is made of 200-nm-thick monolayer YBCO film on a crystalline LaAlO3 substrate. In this optimized design, the SQUID magnetometer is coupled through flip-chip configuration with the configuration providing high coupling coefficient between the devices. The design permits coupling of the rf signals to the SQUID efficiently, whereas the transformer is designed to couple the dc...
Design-oriented modelling of axial-flux variable-reluctance resolver based on magnetic equivalent circuits and Schwarz-Christoffel mapping
, Article IEEE Transactions on Industrial Electronics ; Volume 65, Issue 5 , May , 2018 , Pages 4322-4330 ; 02780046 (ISSN) ; Nasiri Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Axial flux variable reluctance (AFVR) resolvers have substantial benefits that make them suitable for motion control drives. However, they suffer from insufficient accuracy, especially in high-accuracy applications. Hence, optimizing the AFVR resolver structure is necessary for improving its commercial usage. However, its accurate modelling needs three-dimensional (3-D) time stepping finite element analysis (TSFEA) that is computationally expensive and unsuitable for co-usage with optimization algorithms. The aim of this paper is to establish an accurate, yet computationally fast, model suitable for optimal design of AFVR resolvers. The working of the proposed model is based on magnetic...
Performance analysis of outer-rotor single-phase induction motor based on magnetic equivalent circuit
, Article IEEE Transactions on Industrial Electronics ; Volume 68, Issue 2 , 2021 , Pages 1046-1054 ; 02780046 (ISSN) ; Nasiri Gheidari, Z ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Single-phase, outer-rotor squirrel cage induction motors are widely used in ceiling fan applications. Furthermore, they can be employed for pumps, and in-wheel hub drives. In this article, an analytical model based on magnetic equivalent circuit is proposed to evaluate the performance of the motor. The influence of rotor slots' skewing, stator end windings, slots' leakage inductance, and core saturation are included in the model. Furthermore, the windings' copper losses and the core's iron losses are calculated using the proposed model. The results of the presented model are compared with those of time variant finite element analysis (TVFEA) and experimental measurements close agreement...
Nanoplasma-Based millimeter-wave modulators on a single metal layer
, Article IEEE Electron Device Letters ; Volume 43, Issue 8 , 2022 , Pages 1355-1358 ; 07413106 (ISSN) ; Dilmaghanian, M. O ; Farzaneh, F ; Matioli, E ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Fundamental constraints imposing power-frequency trade-offs in conventional electronics have stimulated research on alternative technologies for millimeter-wave and sub-millimeter-wave applications. In this work, we use the picosecond threshold firing of nanoplasma switches to demonstrate on-chip millimeter-wave modulators that rely only on a single metal layer. We show amplitude shift keying (ASK) modulation with self-synthesized carrier frequencies up to 66 GHz (limited by the bandwidth of our experimental setup), with output powers up to 30 dBm. These all-metal nanoplasma modulators are low cost, and generally compatible with different platforms, from CMOS and III-V compounds to flexible...