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IEEE Power India Conference

作者： M.C. Bozchalui M. Sanaye-Pasand School of Electrical and Computer Engineering University of Tehran Iran Control and Intelligent Processing Center of Excellence University of Tehran Iran

Significant changes of load as well as faults and their clearance in power systems, which disturb balance of energy in the system, often result in electromechanical oscillations. This causes variation in power flow between two areas which is usually called as power swing. An effective way to retaliate such a disturbance is through controlled islanding of the power system using out of step (OOS) protection systems. In this paper we use a method which is based on the well-known equal area criterion (EAC) and application of phasor measurement units to protect interconnected systems against loss of synchronism. System oscillation is modeled using the mth-order auto regressive model. Afterwards, using the phase difference values stability of the power system is determined using the equal area criterion

关键词： Relays Phasor measurement units Power system protection Power system modeling Power system measurements Power system relaying Power system faults Power system interconnection Power system stability Load flow

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Lyapunov Analysis of Sample-and-Hold Hybrid Feedbacks

Lyapunov Analysis of Sample-and-Hold Hybrid Feedbacks

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IEEE Conference on Decision and control

作者： Ricardo G. Sanfelice Andrew R. Teel Center for Control Dynamical Systems and Computation Electrical and Computer Engineering Department University of California Santa Barbara CA USA

ISBN: (纸本)1424401704;9781424401703

For hybrid closed-loop systems arising from hybrid control of nonlinear systems, we show that the sample-and-hold implementation of the hybrid controller preserves (semiglobally and practically) the stability properties of the closed-loop system. We provide a general model for the hybrid closed-loop system where the hybrid controller is implemented digitally and it is interfaced to the nonlinear system through sample and hold devices. We model the sample device and the digital controller/hold device as single asynchronous hybrid systems with independent timing constants and data. The main result is established by means of a Lyapunov function for the hybrid closed-loop system resulting from the interconnection of its hybrid and nonlinear subsystems

关键词： Feedback control systems Nonlinear control systems Nonlinear systems Digital control Stability analysis Emulation control system synthesis Military computing Asymptotic stability

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Quantum key distribution based on a Sagnac loop interferometer and polarization-insensitive phase modulators

Quantum key distribution based on a Sagnac loop interferomet...

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IEEE International Symposium on Information Theory

作者： Bing Qi Lei-lei Huang Hoi-kwong Lo Li Qian Center for Quantum Information and Quantum Control Department of Physics and Department of Electrical and Computer Engineering University of Toronto Toronto Canada

We present a design for a quantum key distribution (QKD) system in a Sagnac loop configuration, employing a novel phase modulation scheme based on frequency shift, and demonstrate stable BB84 QKD operation with high interference visibility and low quantum bit error rate (QBER). The phase modulation is achieved by sending two light pulses with a fixed time delay (or a fixed optical path delay) through a frequency shift element and by modulating the amount of frequency shift. The relative phase between two light pulses upon leaving the frequency-shift element is determined by both the time delay (or the optical path delay) and the frequency shift, and can therefore be controlled by varying the amount of frequency shift. To demonstrate its operation, we used an acousto-optic modulator (AOM) as the frequency-shift element, and vary the driving frequency of the AOM to encode phase information. The interference visibility for a 40 km and a 10 km fiber loop is 96% and 99%, respectively, at single photon level. We ran BB84 protocol in a 40-km Sagnac loop setup continuously for one hour and the measured QBER remained within the 2%-5% range. A further advantage of our scheme is that both phase and amplitude modulation can be achieved simultaneously by frequency and amplitude modulation of the AOM's driving signal, allowing our QKD system the capability of implementing other protocols, such as the decoy-state QKD and the continuous-variable QKD. We also briefly discuss a new type of Eavesdropping strategy ("phase-remapping" attack) in bidirectional QKD system

关键词： Sagnac interferometers Polarization Phase modulation Frequency Delay effects Optical modulation Interference Optical pulses Pulse modulation Optical interferometry

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Sagnac quantum key distribution using novel polarization-insensitive phase modulators based on frequency shift

Sagnac quantum key distribution using novel polarization-ins...

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LEOS Summer Topical Meetings

作者： Lei-Lei Huang Bing Qi R. Mong Li Qian Hoi-Kwong Lo Department of Electrical and Computer Engineering and Department of Physics Center for Quantum Information and Quantum Control University of Toronto Toronto Canada

We demonstrate a stable Sagnac quantum key distribution implementing BB84 phase-encoding protocol based on acousto-optic frequency shifters. The quantum bit error rate remains 4-6.5% for at least one hour without reca... 详细信息

关键词： Sagnac interferometers Phase modulation Frequency shift keying Pulse modulation Optical pulse generation Optical fiber polarization Quantum computing Protocols Interference Optical control

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Learning Distributed Object Pushing: Individual Learning and Distributed Cooperation Protocol

Learning Distributed Object Pushing: Individual Learning and...

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2006 IEEE/RSJ International Conference on Intelligent Robots and Systems

作者： Hossein Aminaiee Majid Nili Ahmadabadi Control and Intelligent Processing Center of Excellence Robotics and AI Lab Department of Electrical and Computer Engineering University of Tehran Iran

In this paper we study learning in cooperative object pushing systems. The proposed approach is based on the idea of learning individual skills and then mapping the required cooperative behaviors on the learned skills. The control point for each individual robot is chosen so as to simplify the design of the reinforcement signal and reduce the role of delayed reward on individual learning in addition to make cooperative protocol simpler. A fuzzy Q-learning system for learning individual object pushing is proposed, together with a method for coordination among the robots to push the object cooperatively. The coordination method takes into account the dynamics of the object and the learned individual skills. The idea of the coordination protocol is based on the notion of ability and active regions defined in this paper. In effect, the cooperation protocol is mapped to a Q-value based policy. Simulation results supportively show that the robots learn individual and cooperative object pushing efficiently

关键词： Protocols Robot kinematics Intelligent robots Fuzzy systems Learning Friction control systems Artificial intelligence Robot control Fuzzy control

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Learning Individual Skills and Team Behaviors for Distributed Object Pushing

Learning Individual Skills and Team Behaviors for Distribute...

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IEEE International Conference on Mechatronics and Automation

作者： Hossein Aminaiee Majid Nili Ahmadabadi Control and Intelligent Processing Center of Excellence Robotics Laboratory Department of Electrical and Computer Engineering University of Tehran Tehran Iran

In this paper we discuss a learning approach to distributed object pushing. In the proposed approach, first the required individual skills for single-robot object pushing are learned using a fuzzy reinforcement learning method. Then, the robots learn how to coordinate their actions to push the object to the desired configuration cooperatively in a distributed manner. The proposed team-level learning benefits from the knowledge, which is in the form of a Q-table, that the agent has gained in its individual learning phase by a special design of reward signal and state-action representation. Each robot learns a threshold on its Q-value using a single state reinforcement learning method and pushes the object when the Q-value of its best action in the current state is above this threshold. The reward signal is designed based on the robots' Q-tables and no external critic is needed for learning cooperation. Simulation results show that the robots learn their individual skills and a cooperation protocol to push the object cooperatively

关键词： Robot kinematics Learning Protocols Robot control Robotics and automation Intelligent robots Signal design Mechatronics Process control Intelligent control

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Multi-Innovation Stochastic Gradient Identification Methods

Multi-Innovation Stochastic Gradient Identification Methods

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World Congress on Intelligent control and Automation (WCICA)

作者： Feng Ding Tongwen Chen Control Science and Engineering Research Center Southern Yangtze University Wuxi Jiangsu China Department of Electrical and Computer Engineering University of Alberta Edmonton AB Canada

The stochastic gradient (SG) identification algorithm has a poor convergence rate. We extend the SG algorithm from the viewpoint of innovation modification and present multi-innovation stochastic gradient (MISG) identification algorithms. Since the multi-innovation stochastic gradient algorithms use not only the current data but also the past data at each iteration, parameter estimation accuracy can be improved. Further, we study the performance of the SG and MISG algorithms and show that the MISG algorithms have faster convergence rates and better tracking performance than their corresponding SG algorithms by simulation results

关键词： Stochastic processes Convergence Parameter estimation Eigenvalues and eigenfunctions Stochastic systems Technological innovation Gradient methods Linear regression Vectors Stochastic resonance

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Anti-windup control for an air-breathing hypersonic vehicle model

Anti-windup control for an air-breathing hypersonic vehicle ...

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AIAA Guidance, Navigation, and control Conference 2006

作者： Groves, Kevin P. Serrani, Andrea Yurkovich, Stephen Bolender, Michael A. Doman, David B. Collaborative Center of Control Science Ohio State University Columbus OH 43210 United States Air Force Research Laboratory Wright-Patterson AFB OH 45433 United States Harris Corporation FL United States Department of Electrical and Computer Engineering 2015 Neil Ave. AIAA United States Department of Electrical and Computer Engineering 2015 Neil Ave. Columbus OH United States AFRL/VACA 2210 Eighth St. United States

ISBN: (纸本)1563478196

An anti-windup controller modification is implemented in control system design for a model of the longitudinal dynamics of an air-breathing hypersonic vehicle. Anti-windup control allows the input constraints to be considered explicitly in the design of linear controllers to track a reference trajectory for the vehicle velocity, altitude, and angle of attack. The presence of anti-windup alleviates the need of keeping large penalties on the magnitude of the control input to avoid the occurrence of saturation. This, in turn, allows tighter tuning of the controller gains to obtain faster and more accurate trajectory tracking. The paper employs recent developments in anti-windup design to deal with the presence of exponentially unstable dynamics, which are typically encountered in air-breathing vehicle models. Simulation results on a fully nonlinear model are presented to validate the controller design. Copyright © 2006 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Hypersonic aerodynamics

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Security proof of a three-state quantum-key-distribution protocol without rotational symmetry

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Physical Review A 2006年第4期74卷 042342-042342页

作者： Chi-Hang Fred Fung Hoi-Kwong Lo Center for Quantum Information and Quantum Control Department of Electrical and Computer Engineering University of Toronto Toronto Ont. M5S 3G4 Canada

Standard security proofs of quantum-key-distribution (QKD) protocols often rely on symmetry arguments. In this paper, we prove the security of a three-state protocol that does not possess rotational symmetry. The three-state QKD protocol we consider involves three qubit states, where the first two states ∣0z⟩ and ∣1z⟩ can contribute to key generation, and the third state ∣+⟩=(∣0z⟩+∣1z⟩)∕2 is for channel estimation. This protocol has been proposed and implemented experimentally in some frequency-based QKD systems where the three states can be prepared easily. Thus, by founding on the security of this three-state protocol, we prove that these QKD schemes are, in fact, unconditionally secure against any attacks allowed by quantum mechanics. The main task in our proof is to upper bound the phase error rate of the qubits given the bit error rates observed. Unconditional security can then be proved not only for the ideal case of a single-photon source and perfect detectors, but also for the realistic case of a phase-randomized weak coherent light source and imperfect threshold detectors. Our result in the phase error rate upper bound is independent of the loss in the channel. Also, we compare the three-state protocol with the Bennett-Brassard 1984 (BB84) protocol. For the single-photon source case, our result proves that the BB84 protocol strictly tolerates a higher quantum bit error rate than the three-state protocol, while for the coherent-source case, the BB84 protocol achieves a higher key generation rate and secure distance than the three-state protocol when a decoy-state method is used.

关键词： Quantum cryptography

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Performance of two quantum-key-distribution protocols

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Physical Review A 2006年第1期73卷 012337-012337页

作者： Chi-Hang Fred Fung Kiyoshi Tamaki Hoi-Kwong Lo Center for Quantum Information and Quantum Control Department of Electrical and Computer Engineering University of Toronto Toronto Ont. M5S 3G4 Canada

We compare the performance of Bennett-Brassard 1984 (BB84) and Scarani-Acin-Ribordy-Gisin 2004 (SARG04) protocols, the latter of which was proposed by V. Scarani et al. [Phys. Rev. Lett. 92, 057901 (2004)]. Specifically, in this paper, we investigate the SARG04 protocol with two-way classical communications and the SARG04 protocol with decoy states. In the first part of the paper, we show that the SARG04 scheme with two-way communications can tolerate a higher bit error rate (19.4% for a one-photon source and 6.56% for a two-photon source) than the SARG04 one with one-way communications (10.95% for a one-photon source and 2.71% for a two-photon source). Also, the upper bounds on the bit error rate for the SARG04 protocol with two-way communications are computed in a closed form by considering an individual attack based on a general measurement. In the second part of the paper, we propose employing the idea of decoy states in the SARG04 scheme to obtain unconditional security even when realistic devices are used. We compare the performance of the SARG04 protocol with decoy states and the BB84 one with decoy states. We find that the optimal mean-photon number for the SARG04 scheme is higher than that of the BB84 one when the bit error rate is small. Also, we observe that the SARG04 protocol does not achieve a longer secure distance and a higher key generation rate than the BB84 one, assuming a typical experimental parameter set.

关键词： Quantum theory

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