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American control Conference

作者： Anahita Mirtabatabaei Peng Jia Noah E. Friedkin Francesco Bullo Department of Mechanical Engineering and the Center for Control Dynamical Systems and Computation University of California at Santa Barbara Department of Sociology University of California at Santa Barbara

ISBN: (纸本)9781479932757

This article focuses on the evolution of interpersonal influences in a group of stubborn individuals as they discuss a sequence of issues. Each individual opinion about a single issue is updated based upon the convex combination of the individual's current opinion, the neighbors' current opinion, and the individual's initial opinion;the attachment to the initial opinion characterizes how stubborn an individual is. To model the evolution of the influence network, we employ Friedkin's "reflected appraisal" model: each individual's self-weight on a new issue is determined by the individual's average influence and relative control on other individuals on prior issue outcomes. These modeling assumptions lead to a dynamical system for the evolution of self-weights. We establish the well-posedness and continuity of the proposed dynamics and prove the existence and uniqueness of equilibria for stubborn individuals. We then study the impact of network topology on the individuals' final self-weights. We prove the convergence of all system trajectories for the special case of doubly-stochastic networks and homogeneous stubbornness. We characterize equilibrium self-weights for systems with centralized networks and heterogeneous stubbornness. Finally, our numerical simulations illustrate how existence, uniqueness and attractivity of the equilibria holds true for general network topologies and stubbornness values.

关键词： Vectors Equations Peer-to-peer computing Eigenvalues and eigenfunctions Topology Appraisal Network topology

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A comparison of image based 3D recovery methods for underwater inspections

A comparison of image based 3D recovery methods for underwat...

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7th European Workshop on Structural Health Monitoring, EWSHM 2014

作者： O'Byrne, Michael Pakrashi, Vikram Schoefs, Franck Ghosh, Bidisha Trinity College Dublin Department of Civil Structural and Environmental Engineering Ireland University College Cork Dynamical Systems and Risk Laboratory Civil and Environmental Engineering College Road Cork Ireland LUNAM Université Université de Nantes-Ecole Centrale de Nantes-CNRS GeM Institute for Research in Civil and Mechanical Engineering UMR 6183 IXEAD/CAPACITES Society University of Nantes 2 rue de la Houssinière Nantes Cedex 344322 France

Offshore structures can be subjected to millions of variable amplitude load cycles during their service life which is the primary cause of structural deterioration. Such fatigue loading is exacerbated by marine growth colonization which changes the surface roughness characteristics and increases the diameter of structural members. Having an accurate knowledge of these parameters is essential for analyzing the increased hydrodynamic forces acting on the structure. This paper addresses the issue of acquiring shape information by comparing two popular classes of image based shape recovery techniques;stereo photography and Structure from Motion (SfM). Stereo photography utilises a dual camera set-up to simultaneously photograph an object of interest from slightly different viewpoints, whilst SfM methods generally involve a single camera moving in a static scene. In this paper, these techniques are performed on a controlled shape in an underwater setting, as well as synthetic data which allows for an irregular shape typical of marine growth to be tested whilst still having knowledge of the exact geometrical shape. The results reveal that the self-calibrated stereo approach fared well at getting an appropriately scaled full metric reconstruction, whilst the SfM approach was more susceptible to breaking down. Copyright © Inria (2014).

关键词： Photography

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Protocols for Image Processing based Underwater Inspection of Infrastructure Elements

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Journal of Physics: Conference Series 2015年第1期628卷

作者： Michael O'Byrne Bidisha Ghosh Franck Schoefs Vikram Pakrashi Beaufort Environmental Research Institute University College Cork Ireland Dynamical Systems and Risk Laboratory Civil and Environmental Engineering School of Engineering University College Cork Ireland Department of Civil Structural and Environmental Engineering Trinity College Dublin Ireland LUNAM Université Université de Nantes-Ecole Centrale de Nantes CNRS GeM Institute for Research in Civil and Mechanical Engineering University of Nantes Nantes France and IXEAD/CAPACITES Society Nantes France

Image processing can be an important tool for inspecting underwater infrastructure elements like bridge piers and pile wharves. Underwater inspection often relies on visual descriptions of divers who are not necessarily trained in specifics of structural degradation and the information may often be vague, prone to error or open to significant variation of interpretation. Underwater vehicles, on the other hand can be quite expensive to deal with for such inspections. Additionally, there is now significant encouragement globally towards the deployment of more offshore renewable wind turbines and wave devices and the requirement for underwater inspection can be expected to increase significantly in the coming years. While the merit of image processing based assessment of the condition of underwater structures is understood to a certain degree, there is no existing protocol on such image based methods. This paper discusses and describes an image processing protocol for underwater inspection of structures. A stereo imaging image processing method is considered in this regard and protocols are suggested for image storage, imaging, diving, and inspection. A combined underwater imaging protocol is finally presented which can be used for a variety of situations within a range of image scenes and environmental conditions affecting the imaging conditions. An example of detecting marine growth is presented of a structure in Cork Harbour, Ireland.

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Real-time Pricing Leading to Optimal Operation under Distributed Decision Makings

Real-time Pricing Leading to Optimal Operation under Distrib...

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American control Conference

作者： Kenji Hirata Joao P. Hespanha Kenko Uchida Department of Mechanical Engineering Nagaoka University of Technology Nagaoka 940 2188 Japan Center for Control Dynamical Systems and Computation and the Department of Electrical and Computer Engineering University of California Santa Barbara CA 93106 USA Department of Electrical Engineering and Bioscience Waseda University Tokyo 169 8555 Japan

ISBN: (纸本)9781479932757

This paper investigates the optimal regulation problem with the steady-state constraints under distributed decision makings, where each agent is allowed to determine its own optimal set-point according to an individual profit. On the other hand, the utility, which corresponds to an individual public commission, tries to realize a socially optimal solution that fulfills steady-state constraints. In order to align the individual decision making of each agent with the socially optimal solution, the utility is allowed to provide additional price, which corresponds to tax or subsidy for the agent. This paper proposes a real-time pricing strategy of the utility. The proposed pricing strategy is heuristic, but we show that the resulting closed-loop system is stable, if the step size parameter in the real-time pricing strategy is sufficiently small, and realizes tracking to the socially optimal solution.

关键词： Pricing Optimization Closed loop systems Real-time systems Steady-state Stability analysis Distributed decision making

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Roadmaps using gradient extremal paths

Roadmaps using gradient extremal paths

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Ioannis Filippidis Kostas J. Kyriakopoulos Control and Dynamical Systems Department California Institute of Technology Pasadena CA USA Control Systems Laboratory Department of Mechanical Engineering National Technical University of Athens Zografou Greece

This work proposes a motion planning method based on the construction of a roadmap connecting the critical points of a potential field or a distance function. It aims to overcome the limitation of potential field methods due to local minima caused by concave obstacles. The roadmap is incrementally constructed by a two-step procedure. Starting from a minimum, adjacent saddle-points are found using a local saddle-point search method. Then, the new saddle-points are connected to the minima by gradient descent. A numerical continuation algorithm from the computational chemistry literature is used to find saddle-points. It traces the valleys of the potential field, which are gradient extremal paths, defined as the points where the gradient is an eigenvector of the Hessian matrix. The definition of gradient bisectors is also discussed. The presentation conclude simulations in cluttered environments.

关键词： Joining processes Prediction algorithms Convergence Navigation Planning Equations Mathematical model

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Steelmaking plant technology for steelmaking operations

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Nippon Steel Technical Report 2013年第104期 74-82页

作者： Mimura, Yoshihito Kinoshita, Junichi Umetsu, Kenji Seki, Takeshi Shia, Yoshiaki Ishimori, Yuichi Ohshita, Isao Matsuishi, Nagayuki Higashi, Hirofumi Wakida, Shuji Plant Engineering Div. Plant Engineering and Facility Management Center 20-1 Shintomi Futtsu Chiba 293-8511 Japan Steelmaking Technology Dept. Plant Engineering Div. Plant Engineering and Facility Management Center Japan Electrical and Instrument Maintenance Technology Dept. Systems and Control Engineering Div. Plant Engineering and Facility Management Center Japan Continuous Casting Plant Engineering Dept. Plant Engineering Div. Plant Engineering and Facility Management Center Japan Mechanical Maintenance Technology Dept. Mechanical Engineering Div. Plant Engineering and Facility Management Center Japan Mechanical Technology Dept. Equipment Div. Japan System and Control Technology Dept. Systems and Control Engineering Div. Plant Engineering and Facility Management Center Japan Structural Engineering Dept. Civil Engineering Div. Plant Engineering and Facility Management Center Japan Engineering and Development Section Steel Plant Engineering Dept.-II Plant and Machinery Div. Japan

Steelmaking technology have been developed by some needs and environmental changes. Among them, in steelmaking plant, more technology have been preceded by production of high quality products, approach for global environmental affairs and application of information technology and computer technology. From these viewpoints, some aspects and results of recent steelmaking plant technology will be described in this paper.

关键词： Steelmaking

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Stability of discrete-time systems with stochastically delayed feedback

Stability of discrete-time systems with stochastically delay...

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European control Conference (ECC)

作者： Marcella M. Gomez Gábor Orosz Richard M. Murray Department of Mechanical Engineering California Institute of Technology Pasadena CA USA Department of Mechanical Engineering University of Michigan Ann Arbor MI USA Department of Control and Dynamical Systems California Institute of Technology Pasadena CA USA

ISBN: (纸本)9781479901890

This paper investigates the stability of linear systems with stochastic delay in discrete time. Stability of the mean and second moment of the non-deterministic system is determined by a set of deterministic discrete-time equations with distributed delay. A theorem is provided that guarantees convergence of the state with convergence of the second moment, assuming that delays are identically independently distributed. The theorem is applied to a scalar equation where the stability of the equilibrium is determined.

关键词： Delays Stability analysis Convergence Equations Eigenvalues and eigenfunctions Discrete-time systems Stochastic processes

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Navigation Functions for Focally Admissible Surfaces

Navigation Functions for Focally Admissible Surfaces

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American control Conference

作者： Ioannis Filippidis Kostas J. Kyriakopoulos Control and Dynamical Systems Dept. California Institute of Technology Pasadena CA 91125 USA Control Systems Lab Dept. of Mechanical Engineering National Technical University of Athens 9 Heroon Polytechniou Street Zografou 15780 Greece

ISBN: (纸本)9781479901777

This work presents a sharper condition for the applicability of Navigation Functions (NF). The condition depends on the placement of the destination with respect to the focal surfaces of obstacles. The focal surface is the locus of centers of principal curvatures. If each obstacle encompasses at least one of its focal surfaces, then the world is navigable using a Koditschek-Rimon NF (KRNF). Moreover, the Koditschek-Rimon (KR) potential is non-degenerate for all destinations which are not on a focal surface. So, for almost all destinations there exists a non-degenerate KR potential. This establishes a link between the differential geometry of obstacle surfaces and KRNFs. Channel surfaces (e.g. Dupin cyclides) and certain Boolean operations between shapes are examples of admissible obstacles. We also prove a weak converse result about the inexistence of a KRNF for obstacles with some concave point, for large tuning parameters. Finally, our results support nontrivial simulations in a forest, a pipeline and a cynlinder rig, with some notes about allowable types of non-smoothness.

关键词： navigation Surfaces destination Differential Geometry placement

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Finite-Field Consensus

Finite-Field Consensus

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IEEE Annual Conference on Decision and control

作者： Fabio Pasqualetti Domenica Borra Francesco Bullo Mechanical Engineering Department University of California Riverside Dipartimento di Scienze Matematiche Politecnico di Torino Italy Center for Control Dynamical Systems and Computation University of California at Santa Barbara

ISBN: (纸本)9781467357159

This work studies consensus networks over finite fields, where agents process and communicate values from the set of integers {0,...,p - 1}, for some prime number p, and operations are performed modulo p. For consensus networks over finite fields we provide necessary and sufficient conditions on the network topology and weights to ensure convergence. For instance we show that, differently from the case of consensus networks over the field of real numbers, consensus networks over finite fields converge in finite time, and that properties of the agents interaction graph are not sufficient to ensure finite-field consensus. Finally, we discuss the application of finite-field consensus to distributed averaging in sensor networks.

关键词： Galois fields Network topology Prime number Converge Sufficient conditions

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Measurement of Emissions from a Passenger Truck Fueled with Biodiesel from Different Feedstocks

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Journal of Environmental Protection 2013年第8期4卷 74-82页

作者： Natchanok Pala-En Melanie Sattler Brian H. Dennis Victoria C. P. Chen Rachel L. Muncrief Automotive Air Pollution Division Pollution Control Department Bangkok Thailand Department of Civil Engineering The University of Texas at Arlington Arlington USA Department of Industrial and Manufacturing Systems Engineering The University of Texas at Arlington Arlington USA Department of Mechanical and Aerospace Engineering The University of Texas at Arlington Arlington USA International Council on Clean Transportation Washington DC USA

Biodiesel has generated increased interest recently as an alternative to petroleum-derived diesel. Due to its high oxygen content, biodiesel typically burns more completely than petroleum diesel, and thus has lower emissions of hydrocarbons (HC), carbon monoxide (CO), and particulate matter (PM). However, biodiesel may increase or decrease nitrogen oxide (NOx) and carbon dioxide (CO2) emissions, depending on biodiesel feedstock, engine type, and test cycle. The purpose of this study was to compare emissions from 20% blends of biodiesel made from 4 feedstocks (soybean oil, canola oil, waste cooking oil, and animal fat) with emissions from ultra low sulfur diesel (ULSD). Emissions of NOx and CO2 were made under real-world driving conditions using a Horiba On-Board Measurement System OBS-1300 on a highway route and arterial route;emissions of NOx, CO2, HC, CO, and PM were measured in a controlled setting using a chassis dynamometer with Urban Dynamometer Drive Schedule. Dynamometer test results showed statistically significant lower emissions of HC, CO, and PM from all B20 blends compared to ULSD. For CO2, both on-road testing (arterial, highway, and idling) and dynamometer testing showed no statistically significant difference in emissions among the B20 blends and ULSD. For NOx, dynamometer testing showed only B20 from soybean oil to have statistically significant higher emissions. This is generally consistent with the on-road testing, which showed no statistically significant difference in NOx emissions between ULSD and the B20 blends.

关键词： Alternative Fuel Biodiesel Diesel Emissions On-Road Testing Portable Emission Measurement System (PEMS) Dynamometer

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