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Fading of remote synchronization in tree networks of Stuart-Landau oscillators

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Physical Review E 2019年第5期99卷 052301-052301页

作者： Baris Karakaya Ludovico Minati Lucia Valentina Gambuzza Mattia Frasca Faculty of Engineering Department of Electrical Electronics Engineering Firat University 23119 Elazig Turkey World Research Hub Initiative—Institute of Innovative Research Tokyo Institute of Technology Yokohama 226-8503 Japan Complex Systems Theory Department Institute of Nuclear Physics—Polish Academy of Sciences (IFJ-PAN) 31-342 Kraków Poland and Center for Mind/Brain Sciences (CIMeC) University of Trento 38123 Trento Italy Dipartimento Ingegneria Elettrica Elettronica e Informatica Università degli Studi di Catania 95029 Catania Italy CNR-IASI Italian National Research Council-Institute for Systems Analysis and Computer Science “A. Ruberti” 00185 Rome Italy

Remote synchronization (RS) is characterized by the appearance of phase coherence between oscillators that do not directly interact through a structural link in a network but exclusively through other units that are not synchronized or more weakly synchronized with them. This form of phase synchronization was observed initially in starlike motifs and later in random networks. In this paper, we report on an experimental setup for the analysis of RS in networks of Stuart-Landau oscillators and in particular investigate the behavior of tree structures focusing on the path to synchronization, that is, on the analysis of how synchronization emerges as the coupling strength increases from zero. We find that RS occurs in a region wherein further increases of the coupling strength lead to a direct transition to global synchronization but may also be observed in a second region, corresponding to lower coupling values, wherein it first emerges and then disappears, hallmarking a scenario that we denote as fading of remote synchronization. We show that this result is related to the behavior of pairs of remotely synchronized nodes observed in networks with more general topologies. Experiments are corroborated by numerical simulations confirming the major findings and providing further characterization of the phenomenon. We demonstrate that the distribution of natural oscillation frequencies and the parameter uncertainty in the links both play a fundamental role in shaping the behaviors observed.

关键词： Coupled oscillators Synchronization

A lyapunov-based small-gain theorem for infinite networks

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arXiv 2019年

作者： Kawan, Christoph Mironchenko, Andrii Swikir, Abdalla Noroozi, Navid Zamani, Majid Institute of Informatics Ludwig Maximilian University of Munich Germany Faculty of Computer Science and Mathematics University of Passau Passau94032 Germany Department of Electrical and Computer Engineering Technical University of Munich Germany Otto-von-Guericke University Magdeburg Laboratory for Systems Theory and Automatic Control Magdeburg Germany Computer Science Department University of Colorado BoulderCO80309 United States Computer Science Department Ludwig Maximilian University of Munich Germany

This paper presents a small-gain theorem for networks composed of a countably infinite number of finite-dimensional subsystems. Assuming that each subsystem is exponentially input-to-state stable, we show that if the gain operator, collecting all the information about the internal Lyapunov gains, has a spectral radius less than one, the overall infinite network is exponentially input-to-state stable. The effectiveness of our result is illustrated through several examples including nonlinear spatially invariant systems with sector nonlinearities and a road traffic *** Codes 37B25, 37L15, 93D05, 93A15 Copyright © 2019, The Authors. All rights reserved.

关键词： Large scale systems

Event-triggered controller synthesis for dynamical systems with temporal logic constraints

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arXiv 2018年

作者： Maity, Dipankar Baras, John S. Department of Electrical and Computer Engineering and Institute for Systems Research University of Maryland College Park United States

In this work, we propose an event-triggered control framework for dynamical systems with temporal logical constraints. Event-triggered control methodologies have proven to be very efficient in reducing sensing, communication and computation costs. When a continuous feedback control is replaced with an event-triggered strategy, the corresponding state trajectories also differ. In a system with logical constraints, such small deviation in the trajectory might lead to unsatisfiability of the logical constraints. In this work, we develop an approach where we ensure that the event-triggered state trajectory is confined within an_tube of the ideal trajectory associated with the continuous state feedback. At the same time, we will ensure satisfiability of the logical constraints as well. Furthermore, we show that the proposed method works for delayed systems as long as the delay is bounded by a certain quantity. Copyright © 2018, The Authors. All rights reserved.

关键词： Trajectories

Secure Estimation under Causative Attacks

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arXiv 2018年

作者： Sihag, Saurabh Tajer, Ali Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute TroyNY12180 United States

This paper considers the problem of secure parameter estimation when the estimation algorithm is prone to causative attacks. Causative attacks, in principle, target decision-making algorithms (e.g., inference and learning algorithms) to alter their decisions by making them oblivious to specific attacks. Such attacks influence inference algorithms by tampering with the mechanism through which the algorithm is provided with the statistical model of the population about which an inferential decision is made. Causative attacks are viable, for instance, by contaminating the historical or training data, or by compromising an expert who provides the model. In the presence of causative attacks, the inference algorithms operate under a distorted statistical model for the population from which they collect data samples. This paper introduces specific notions of secure estimation and provides a framework under which secure estimation under causative attacks can be formulated. A central premise underlying the secure estimation framework is that forming secure estimates introduces a new dimension to the estimation objective, which pertains to detecting attacks and isolating the true model. Since detection and isolation decisions themselves are imperfect, their inclusion induces an inherent coupling between the desired secure estimation objective and the auxiliary detection and isolation decisions that need to be formed in conjunction with the estimates. This paper establishes the fundamental interplay among the decisions involved, and characterizes the general decision rules in closed-forms for any desired estimation cost function. Furthermore, to circumvent the computational complexity associated with growing parameter dimension or attack complexity, a scalable estimation algorithm and its attendant optimality guarantees are provided. Finally, the theory developed is applied to secure parameter estimation in a sensor network operating in an adversarial environment. Copyright ©

关键词： Parameter estimation

An In-Depth Look at TOI-3884b: a Super-Neptune Transiting a M4 Dwarf with Persistent Star Spot Crossings

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arXiv 2023年

作者： Libby-Roberts, Jessica E. Schutte, Maria Hebb, Leslie Kanodia, Shubham Cañas, Caleb I. Stefánsson, Guðmundur Lin, Andrea S.J. Mahadevan, Suvrath Parts, Winter Powers, Luke Wisniewski, John Bender, Chad F. Cochran, William D. Diddams, Scott A. Everett, Mark E. Gupta, Arvind F. Halverson, Samuel Kobulnicky, Henry A. Kowalski, Adam F. Larsen, Alexander Monson, Andrew Ninan, Joe P. Parker, Brock A. Ramsey, Lawrence W. Robertson, Paul Schwab, Christian Swaby, Tera N. Terrien, Ryan C. Department of Astronomy & Astrophysics 525 Davey Laboratory The Pennsylvania State University University ParkPA16802 United States Center for Exoplanets and Habitable Worlds 525 Davey Laboratory The Pennsylvania State University University ParkPA16802 United States Homer L. Dodge Department of Physics and Astronomy University of Oklahoma 440 W. Brooks Street NormanOK73019 United States Physics Department Hobart and William Smith Colleges 300 Pulteney Street GenevaNY14456 United States Department of Astronomy Cornell University 245 East Ave IthacaNY14850 United States Earth and Planets Laboratory Carnegie Institution for Science 5241 Broad Branch Road NW WashingtonDC20015 United States NASA Goddard Space Flight Center 8800 Greenbelt Road GreenbeltMD20771 United States Department of Astrophysical Sciences Princeton University 4 Ivy Lane PrincetonNJ08540 United States ETH Zurich Institute for Particle Physics & Astrophysics Switzerland Department of Physics & Astronomy George Mason University 4400 University Drive MS 3F3 FairfaxVA22030 United States Steward Observatory The University of Arizona 933 N. Cherry Avenue TucsonAZ85721 United States McDonald Observatory Department of Astronomy The University of Texas Austin United States Center for Planetary Systems Habitability The University of Texas Austin United States Electrical Computer & Energy Engineering University of Colorado 425 UCB BoulderCO80309 United States Department of Physics University of Colorado 2000 Colorado Avenue BoulderCO80309 United States Time and Frequency Division National Institute of Standards and Technology 325 Broadway BoulderCO80305 United States NSF’s National Optical-Infrared Astronomy Research Laboratory 950 N. Cherry Ave. TucsonAZ85719 United States Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive PasadenaCA91109 United States Department of Physics & Astronomy University of Wyoming LaramieWY82070 Uni

We perform an in-depth analysis of the recently validated TOI-3884 system, an M4 dwarf star with a transiting super-Neptune. Using high precision light curves obtained with the 3.5 m Apache Point Observatory and radial velocity observations with the Habitable-zone Planet Finder (HPF), we derive a planetary mass of 32.6+7.3−7.4M⨁ and radius of 6.4 ± 0.2 R⨁. We detect a distinct star spot crossing event occurring just after ingress and spanning half the transit for every transit. We determine this spot feature to be wavelength-dependent with the amplitude and duration evolving slightly over time. Best-fit star spot models show that TOI-3884b possesses a misaligned (λ = 75 ± 10◦) orbit which crosses a giant pole-spot. This system presents a rare opportunity for studies into the nature of both a misaligned super-Neptune and spot evolution on an active mid-M dwarf. © 2023, CC BY.

关键词： Orbits

A Comparison of Machine Learning Approaches to Detect Botnet Traffic

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A Comparison of Machine Learning Approaches to Detect Botnet...

International Joint Conference on Neural Networks

作者： Brendan Abraham Abhijith Mandya Rohan Bapat Fatma Alali Don E. Brown Malathi Veeraraghavan School of Systems and Information Engineering Data Science Institute Department of Electrical and Computer Engineering University of Virginia Charlottesville Virginia

During the past decade, botnets have become one of the most significant threats in the field of network security. A botnet attack typically works by infecting a device with malware and then recruiting it into a network of infected devices controlled by an attacker, which may lead to severe economic and social consequences. As a result, a considerable amount of research has been conducted to detect and prevent such attacks. In this paper, we create a foundation for an anomaly-based intrusion detection system to improve network security and to help reduce human involvement and error. The network traffic we used is captured in the form of connection logs, which are generated by a popular network monitoring framework called Bro. We use our proposed framework to compare the performances of multiple supervised learning approaches, including Logistic Regression (LR), Naive Bayes (NB), Support Vector Machine (SVM), Random Forest (RF) and Neural Networks (NN) at anomaly detection. We evaluated these models using F1 Score and Area Under Curve (AUC). Our models are trained on malicious network traffic samples from pervasive botnets like Zeus, Miuref and Conficker, as well as benign traffic samples. Using traditional cross validation, we illustrate that Random Forest has the best performance for anomaly detection. To test each algorithm's ability to generalize to unseen bot types, we implemented a custom-designed Leave-One-Out Cross Validation (LOBO-CV). In this procedure, each algorithm is trained on all but one bot family and evaluated on their ability to detect the unknown botnet traffic. We then improved overall detection performance by ensembling our two best models. Our results demonstrate we can detect both previously seen bot families and unseen botnet families with a high degree of confidence.

关键词： Botnet Hidden Markov models Malware Feature extraction Protocols Machine learning algorithms IP networks

Linear Quadratic Stochastic Differential Games under Asymmetric Value of Information

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IFAC-PapersOnLine 2017年第1期50卷 8957-8962页

作者： Maity D. Baras J.S. Department of Electrical & Computer Engineering Institute for Systems Research University of Maryland United States

This paper considers a variant of two-player linear quadratic stochastic differential games. In this framework, none of the players has access to the state observations for all the time, which restricts the possibility of continuous feedback strategies. However, they can observe the state intermittently at discrete time instances by paying some finite cost. Having on demand costly measurements ensure that open-loop strategy is not the only strategy for this game. The individual cost functions for each player explicitly incorporate the value of information and the asymmetry that comes along with different costs of state observation for different players. We study the structural properties of the Nash equilibrium for this particular class of problems when the cost of observation is finite and positive. We show that the game problem simplifies into two decoupled game problems: one for deciding the control strategies, and the other for deciding the observation acquisition times. The study also reveals that under two extreme cases -cost of observation being 0 or ∞- the strategies coincide with feedback and open-loop strategies respectively. © 2017

关键词： event-based game game theory linear-quadratic games non-cooperative game stochastic games

Reprogrammable 3D Mesostructures Through Compressive Buckling of Thin Films with Prestrained Shape Memory Polymer

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Acta Mechanica Solida Sinica 2018年第5期31卷 589-598页

作者： Xiaogang Guo Zheng Xu Fan Zhang Xueju Wang Yanyang Zi John A. Rogers Yonggang Huang Yihui Zhang Department of Engineering Mechanics Center for Mechanics and Materials and Center for Flexible Electronics Technology AML Tsinghua University Beijing 100084 China State Key Laboratory for Manufacturing and Systems Engineering School of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 China Simpson Querrey Institute and Feinberg Medical School Center for Bio-Integrated Electronics Northwestern University Evanston IL 60208 USA Departments of Materials Science and Engineering Biomedical Engineering Chemistry Mechanical Engineering Electrical Engineering and Computer Science and Neurological Surgery Center for Bio-Integrated Electronics Simpson Querrey Institute for Nano/biotechnology Northwestern University Evanston IL 60208 USA Departments of Civil and Environmental Engineering Mechanical Engineering and Materials Science and Engineering Center for Bio-Integrated Electronics Northwestern University Evanston IL 60208 USA

The mechanically guided assembly that relies on the compressive buckling of strate- gically patterned 2D thin films represents a robust route to complex 3D mesostructures in advanced materials and even functional micro-devices. Based on this approach, formation of complex 3D configurations with suspended curvy features or hierarchical geometries remains a challenge. In this paper, we incorporate the prestrained shape memory polymer in the 2D precur- sor design to enable local rolling deformations after the mechanical assembly through compressive buckling. A theoretical model captures quantitatively the effect of key design parameters on local rolling deformations. The combination of precisely controlled global buckling and local rolling expands substantially the range of accessible 3D configurations. The combined experimental and theoretical studies over a dozen of examples demonstrate the utility of the proposed strategy in achieving complex reprogrammable 3D mesostructures.

关键词： Mechanically guided 3D assembly Reprogrammable 3D mesostructures Shapememory polymer Buckling Rolling

Human intention estimation based on hidden Markov model motion validation for safe flexible robotized warehouses

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arXiv 2018年

作者： Petković, Tomislav Puljiz, David Marković, Ivan Hein, Björn University of Zagreb Faculty of Electrical Engineering and Computing Department of Control and Computer Engineering Laboratory for Autonomous Systems and Mobile Robotics Unska 3 ZagrebHR-10000 Croatia Karlsruhe Institute of Technology Institute for Anthropomatics and Robotics Intelligent Process Automation and Robotics Lab Kaiserstraße 12 Deutschland KarlsruheDE-76131

With the substantial growth of logistics businesses the need for larger warehouses and their automation arises, thus using robots as assistants to human workers is becoming a priority. In order to operate efficiently and safely, robot assistants or the supervising system should recognize human intentions in real-time. Theory of mind (ToM) is an intuitive human conception of other humans' mental state, i.e., beliefs and desires, and how they cause behavior. In this paper we propose a ToM based human intention estimation algorithm for flexible robotized warehouses. We observe human's, i.e., worker's motion and validate it with respect to the goal locations using generalized Voronoi diagram based path planning. These observations are then processed by the proposed hidden Markov model framework which estimates worker intentions in an online manner, capable of handling changing environments. To test the proposed intention estimation we ran experiments in a real-world laboratory warehouse with a worker wearing Microsoft Hololens augmented reality glasses. Furthermore, in order to demonstrate the scalability of the approach to larger warehouses, we propose to use virtual reality digital warehouse twins in order to realistically simulate worker behavior. We conducted intention estimation experiments in the larger warehouse digital twin with up to 24 running robots. We demonstrate that the proposed framework estimates warehouse worker intentions precisely and in the end we discuss the experimental results. Copyright © 2018, The Authors. All rights reserved.

关键词： Virtual reality