102,354 research outputs found
Receding-horizon switched linear system design: a semidefinite programming approach with distributed computation
No full textThis dissertation presents a framework for analysis and controller synthesis problems for switched linear systems. These are multi-modal systems whose parameters vary within a finite set according to the state of a discrete time automaton; the switching signal may be unconstrained or may be drawn from a language of admissible switching signals. This model of system dynamics and discrete logic has many applications in a number of engineering contexts. A receding-horizon type approach is taken by designing controllers with access to a finite-length preview of future modes and finite memory of past modes; the length of both preview and memory are taken as design choices. The results developed here take the form of nested sequences of SDP feasibility problems. These conditions are exact in that the feasibility of any element of the sequence is sufficient to construct a suitable controller, while the existence of a suitable controller necessitates the feasibility of some element of the sequence.
Considered first is the problem of controller synthesis for the stabilization of switched systems. These developments serve both as a control problem of interest and a demonstration of the methods used to solve subsequent switched control problems. Exact conditions for the existence of a controller are developed, along with converse results which rule out levels of closed-loop stability based on the infeasibility of individual SDP problems. This permits the achievable closed-loop performance level to be approximated to arbitrary accuracy.
Examined next are two different performance problems: one of disturbance attenuation and one of windowed variance. For each problem, controller synthesis conditions are presented exactly in the form of SDP feasibility problems which may be optimized to determine levels of performance. In both cases, the performance level may be taken as uniform or allowed to vary based on the switching path encountered.
The controller synthesis conditions presented here can grow both large and computationally intensive, but they share a common structural sparsity which may be exploited. The last part of this dissertation examines this structure and presents a distributed approach to solving such problems. This maintains the tractability of these results even at large scales, expanding the scope of systems to which these methods can be applied.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2019-02-05 without embargo termsThe student, Raymond Essick V, accepted the attached license on 2018-10-16 at 21:27.The student, Raymond Essick V, submitted this Dissertation for approval on 2018-10-16 at 21:37.This Dissertation was approved for publication on 2018-10-22 at 15:08.DSpace SAF Submission Ingestion Package generated from Vireo submission #13035 on 2019-02-05 at 11:08:24Made available in DSpace on 2019-02-06T19:32:44Z (GMT). No. of bitstreams: 4
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Previous issue date: 2018-10-2
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
ORBITAL DECAY OF HOT JUPITERS DUE TO NONLINEAR TIDAL DISSIPATION WITHIN SOLAR-TYPE HOSTS
No full textWe study the orbital evolution of hot Jupiters due to the excitation and damping of tidally driven g-modes within solar-type host stars. Linearly resonant g-modes (the dynamical tide) are driven to such large amplitudes in the stellar core that they excite a sea of other g-modes through weakly nonlinear interactions. By solving the dynamics of large networks of nonlinearly coupled modes, we show that the nonlinear dissipation rate of the dynamical tide is several orders of magnitude larger than the linear dissipation rate. We find stellar tidal quality factors Q[' over *] ≃ 10[superscript 5]–10[superscript 6] for systems with planet mass M[subscript p] ≳ 0.5M[subscript J] and orbital period P ≲ 2\;\mathrm{days},$ which implies that such systems decay on timescales that are small compared to the main-sequence lifetime of their solar-type hosts. According to our results, there are ≃ 10 currently known exoplanetary systems, including WASP-19b and HAT-P-36-b, with orbital decay timescales shorter than a Gyr. Rapid, tidally induced orbital decay may explain the observed paucity of planets with M[subscript p] ≳ M[subscript J] and P < 2 days around solar-type hosts and could generate detectable transit-timing variations in the near future.National Science Foundation (U.S.) (Laser Interferometer Gravitational-Wave Observatory PHY-0757058)United States. National Aeronautics and Space Administration (NNX14AB40G
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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The twelve large colour prints of William Blake: a study on techniques, materials and context
No full textThe aim of this thesis is to study in entirety the group of large colour prints which William Blake made between 1795 and 1805. The series of prints represents the single most important and complete development of Blake’s skill as an innovative printmaker. Although they include some of Blake’s best-known images, they have not been studied before in their entirety or from the point of view of analysing the techniques and methods Blake had used. My study will show how Blake executed these truly impressive prints in terms of materials, method and motives. The first half of the thesis deals with the materialistic aspects of Blake’s colour printing. In chapter one tracing the controversial two-pull discussion to the root, I will make clear the focus points as well as revealing the early tradition of experimental criticism on Blake’s colour printing method. Focusing on two important critics, W. Graham Robertson and Ruthven Todd, and the periods they lived, I attempt to reveal the role they played in a wider context. Also I show how the tradition of Blake’s art was inherited directly through the Ancients to the Pre-Raphaelite Brotherhood, which leads to Robertson and Todd. In the second chapter I deal with the development of Blake’s colour printing experiments. It is obvious that the Twelve Large Colour Prints were produced as a result of Blake’s series of colour printing experiments, starting with monocolour simple prints, going through the illuminated books progressing with more colours and higher skills
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3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
The Right to Strike under the United States Constitution: Theory, Practice, and Possible Implications for Canada
No full textAnswering critics of the Canadian Supreme Court's judgment in B.C. Health, the author argues that the Court laid the foundation for a principled and durable doctrine protecting constitutional labour rights, one that goes directly to the heart of the matter — the inequality of workers’ power in the employment relation. In the author’s view, two paths could lead from B.C. Health to the recognition of Charter protec- tion for a right to strike: one that treats the right as an accessory to col- lective bargaining, and one that upholds the right directly on the basis of the Charter values of equality and participation. The author supports the latter approach, contending that constitutional rights should be defined in relation to fundamental values, in a way that is not contingent on time-bound or fact-sensitive assessments about the role of strikes within a particular collective bargaining regime. Although a Charter right to strike may involve the courts in difficult choices about when to defer to legislative policy decisions, and courts may lack the institutional capac- ity to deal effectively with labour law issues, the author points out that judges can look to ILO standards for expert guidance. Noting that the U.S. experience in this area might be of considerable use to Canadians, the author concludes by providing an overview of American case law concerning a constitutional right to strike.Peer reviewe
Impact of the tidal p−g instability on the gravitational wave signal from coalescing binary neutron stars
No full textRecent studies suggest that coalescing neutron stars are subject to a fluid instability involving the nonlinear coupling of the tide to p modes and g modes. Its influence on the inspiral dynamics and thus the gravitational wave signal is, however, uncertain because we do not know precisely how the instability saturates. Here we construct a simple, physically motivated model of the saturation that allows us to explore the instability’s impact as a function of the model parameters. We find that for plausible assumptions about the saturation, current gravitational wave detectors might miss >70% of events if only point particle waveforms are used. Parameters such as the chirp mass, component masses, and luminosity distance might also be significantly biased. On the other hand, we find that relatively simple modifications to the point particle waveform can alleviate these problems and enhance the science that emerges from the detection of binary neutron stars.United States. National Aeronautics and Space Administration (ATP Grant NNX14AB40G)National Science Foundation (U.S.)Laser Interferometer Gravitational Wave Observator
G-Rank: Unsupervised Continuous Learn-to-Rank for Edge Devices in a P2P Network
No full textRanking algorithms in traditional search engines are powered by enormous training data sets that are meticulously engineered and curated by a centralized entity. Decentralized peer-to-peer (p2p) networks such as torrenting applications and Web3 protocols deliberately eschew centralized databases and computational architectures when designing services and features. As such, robust search-and-rank algorithms designed for such domains must be engineered specifically for decentralized networks, and must be lightweight enough to operate on consumer-grade personal devices such as a smartphone or laptop computer. We introduce G-Rank, an unsupervised ranking algorithm designed exclusively for decentralized networks. We demonstrate that accurate, relevant ranking results can be achieved in fully decentralized networks without any centralized data aggregation, feature engineering, or model training. Furthermore, we show that such results are obtainable with minimal data preprocessing and computational overhead, and can still return highly relevant results even when a user’s device is disconnected from the network. G-Rank is highly modular in design, is not limited to categorical data, and can be implemented in a variety of domains with minimal modification. The results herein show that unsupervised ranking models designed for decentralized p2p networks are not only viable, but worthy of further research.https://github.com/awrgold/G-RankComputer Scienc
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