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By
Herbertz, Joachim; Grünter, Konrad
Zusammenfassung
Um die generellen Ansatzpunkte.für eine Frequenzsteuerung von Ultraschallpfeifen mit Hohlraumresonator aufzuzeigen, werden im folgenden die bekannten Grundtypen diskutiert.
By
Li, GuoQiang; Zhang, Chao; Lou, GuoBiao; Wang, YongChang; Wang, LingLing
Show all (5)
34 Citations
Intumescent coatings are now the dominant passive fire protection materials used for steel construction. Intumescent coatings will react at high temperatures and the thermal properties of intumescent coatings can not be measured directly by the current standard test methods which are originally designed for the traditional inert fireproofing materials. This paper proposed a simple procedure to assess the fire resistance of intumescent coatings by using the concept of equivalent constant thermal resistance. The procedure is based on the approximate formula for predicting the limiting temperatures of protected steel members subjected to the standard fire. Test data from investigations on both smallscale samples and fullscale steel members are used to calculate the equivalent constant thermal resistance. Using the equivalent constant thermal resistance of intumescent coatings, the calculated steel temperatures agree well with the test data in the range of the limiting temperatures from 400°C to 600°C. The procedure needs no complex computation and is recommended for practical usage. The equivalent constant thermal resistance could be used to quantify the insulation capacity of intumescent coatings.
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By
Santos, Ariane L.; Martin, Luiz A. B. San
6 Citations
Let S be a subsemigroup with nonempty interior of a connected complex simple Lie group G. It is proved that S = G if S contains a subgroup G(α) ≈ Sl (2,
$ \mathbb{C} $
) generated by the exp
$ {{\mathfrak{g}}_{{\pm \alpha }}} $
, where
$ {{\mathfrak{g}}_{\alpha }} $
is the root space of the root α. The proof uses the fact, proved before, that the invariant control set of S is contractible in some flag manifold if S is proper, and exploits the fact that several orbits of G(α) are 2spheres not null homotopic. The result is applied to revisit a controllability theorem and get some improvements.
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By
Goren, Omer ; Calisal, Sander M.; Bulent Danisman, D.
It has been more than a decade since Calisal et al. (J Ship Res 46(3):208–213, 2002) presented their concept of wave resistance reduction by allowing an increase in the beam of a ship accompanied by smoothing the shoulders. Since then a series of computational and experimental studies have been performed to provide evidence for the design idea that an increase in the beam with waterline parabolization may give reduced wave resistance for moderate Froude numbers in most cases in contrast to the common understanding among naval architects. The procedure in the design concept mentioned has been based on a systematic search supported by computational work and validated by experimental studies. The present study attempts to rationalize the introduced design concept by establishing a mathematical programming basis which employs the thinship approximation for wave resistance and a quadratic programming in finding the optimal shape of the design waterline (DWL), for minimum wave resistance, for the given design constraints. In this case, the shape of the DWL and in turn the hull shape in accordance with DWL is determined by a welldefined optimization procedure, which is dictated by the mathematical programming routine. Computational tools are employed to check the hydrodynamic characteristics of the hull form determined by the optimization routine, before tank testing. An experimental work is carried out to confirm the computational results and to validate the proposed methodology. Both the computational and the experimental work point out that the present design approach is effective particularly for Froude numbers greater than 0.21 and less than 0.4 where the shipgenerated wavelength along the hull is less than the body length.
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By
Pfeffer, KarlHeinz; Zipsner, Thomas
Zusammenfassung
Eine sehr anschauliche Anwendung der Vektorrechnung ist die Analytische Geometrie, bei der Geraden und Ebenen in vektorieller Darstellung erläutert werden. Ausführlich werden verschiedene Arten von Geraden und Ebenengleichungen dargestellt sowie wichtige Beziehungen von Punkt und Gerade sowie Schnittpunkt und Spurpunkt von Geraden gezeigt.
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By
GarcíaBlanco, Raquel; Díez, Pedro ; Borzacchiello, Domenico; Chinesta, Francisco
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2 Citations
The power flow model performs the analysis of electric distribution and transmission systems. With this statement at hand, in this work we present a summary of those solvers for the power flow equations, in both algebraic and parametric version. The application of the Alternating Search Direction method to the power flow problem is also detailed. This results in a family of iterative solvers that combined with Proper Generalized Decomposition technique allows to solve the parametric version of the equations. Once the solution is computed using this strategy, analyzing the network state or solving optimization problems, with inclusion of generation in realtime, becomes a straightforward procedure since the parametric solution is available. Complementing this approach, an error strategy is implemented at each step of the iterative solver. Thus, error indicators are used as an stopping criteria controlling the accuracy of the approximation during the construction process. The application of these methods to the model IEEE 57bus network is taken as a numerical illustration.
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By
Eroshenko, V. M.; Ershov, A. V.; Zaichik, L. I.
4 Citations
We have calculated turbulent quasideveloped flow and heat transfer in a circular pipe, taking account of the temperature dependence of the physical properties of the gas when there is injection through porous walls.
By
Bernardes, Marciele Berger; Andrade, Francisco Pacheco; Novais, Paulo
Considering that information technology penetrates all areas and domains of the public sector, it has to be considered the extension of the required regulation needed for warranting that this phenomenon becomes an advantage and not a threat. In this sense, this study has as aims to discuss certain aspects associated with fair use of emerging and disruptive technologies and (such as Artificial Intelligence, Internet of Things, Big Data) in the public sector. The emphasis may fall upon the treatment of this subject by traditional regulatory instances, such as Data Protection RegulationGDPR, in the sense of enhancing the capacity of Governments to ensure privacy, data protection, and the protection of citizens.
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