104,796 research outputs found
Estimates of the bistable region in metal cutting
No full textThe classical model of regenerative vibration is investigated with new kinds of nonlinear cutting force characteristics. The standard nonlinear characteristics are subjected to a critical review from the nonlinear dynamics viewpoint based on the experimental results available in the literature. The proposed nonlinear model includes finite derivatives at zero chip thickness and has an essential inflexion point. In the case of the one degree-of-freedom model of orthogonal cutting, the existence of unstable self-excited vibrations is proven along the stability limits, which is strongly related to the force characteristic at its inflexion point. An analytical estimate is given for a certain area below the stability limit where stable stationary cutting and a chaotic attractor coexist. It is shown how this domain of bistability depends on the theoretical chip thickness. The comparison of these results with the experimental observations and also with the subcritical Hopf bifurcation results obtained for standard nonlinear cutting force characteristics provides relevant information on the nature of the cutting force nonlinearit
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Stepan Trofimovitch Verhovensky: the Key to The Possessed
No full textIn the "metaphysical vacuum" of The Possessed Stepan Trofimovitch Verhovensky is symbolic of a non-productive stewardship--a father who did not father, a teacher who did not teach, and elder who did not will wisdom and tradition to the dependent younger generation. It is puzzling how little critical notice has been taken of Stepan, and it is a lonely position to find in him the key to the teeming, chaotic world of the novel, but this is the thesis which will be pursued
Illjustrirovannyj sputnik po Volgě v 3-ch častjach s kartoju Volgi : istoriko-statističeskij očerk i spravočnyj ukazatelʹ
No full textBeilagekarte Karta Volgi ot Nižnjago-Novgoroda do AstrachaniBeilage Spravočnyja svěděnija o g. Astrachanisostavil S. Monastyrski
Supercritical bifurcation of the digital position control of a single-dof robot model under symmetric nonlinear force
No full textFaster Algorithms for Half-Integral T-Path Packing
No full textLet G = (V, E) be an undirected graph, a subset of vertices T be a set of terminals. Then a natural combinatorial problem consists in finding the maximum number of vertex-disjoint paths connecting distinct terminals. For this problem, a clever construction suggested by Gallai reduces it to computing a maximum non-bipartite matching and thus gives an O(mn^1/2 log(n^2/m)/log(n))-time algorithm (hereinafter n := |V|, m := |E|).
Now let us consider the fractional relaxation, i.e. allow T-path packings with arbitrary nonnegative real weights. It is known that there always exists a half-integral solution, that is, one only needs to assign weights 0, 1/2, 1 to maximize the total weight of T-paths. It is also known that an optimum half-integral packing can be found in strongly-polynomial time but the actual time bounds are far from being satisfactory.
In this paper we present a novel algorithm that solves the half-integral problem within O(mn^1/2 log(n^2/m)/log(n)) time, thus matching the complexities of integral and half-integral versions
Scraping the Monumental: Stepan Bandera through the Lens of Quantitative Memory Studies
No full textIn this essay we use the example of Stepan Bandera to demonstrate the effectiveness of web-scraping methods as a tool to explore how people interact with memory content online. Using data from Wikipedia, Twitter and YouTube, we analyse the traces left by users interested in Stepan Bandera and assess how these differ between Ukraine, Russia and Poland. Applying data mining and content analysis to data traditionally analysed from a purely qualitative perspective, we show how Polish content about Bandera follows completely different patterns in comparison to Ukrainian and Russian debates. Our tools, made available online, also include attempts at analysing video content
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
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