41,417 research outputs found
Hamiltonisation, measure preservation and first integrals of the multi-dimensional rubber Routh sphere
We consider the multi-dimensional generalisation of the problem of a sphere,
with axi-symmetric mass distribution, that rolls without slipping or spinning
over a plane. Using recent results from Garc\'ia-Naranjo (arXiv: 1805:06393)
and Garc\'ia-Naranjo and Marrero (arXiv: 1812.01422), we show that the reduced
equations of motion possess an invariant measure and may be represented in
Hamiltonian form by Chaplygin's reducing multiplier method. We also prove a
general result on the existence of first integrals for certain Hamiltonisable
Chaplygin systems with internal symmetries that is used to determine conserved
quantities of the problem.Comment: 23 pages, 1 figure. Submitted to the special issue of Theor. Appl.
Mech. in honour of Chaplygin's 150th anniversar
Conversión hidrotermal de biomasa en bioproductos valiosos
Los procesos hidrotérmicos son una excelente alternativa para convertir desechos de biomasa en productos de alto valor energético. El alcance de este proyecto ofrece el estudio de 5 tipos de biomasa distintos: café, madera blanca, arroz, lignina y madera negra (Zilkha).
La reacción se llevó a cabo en un reactor continúo cambiando las condiciones de presión y temperatura. El café demostró ser la materia primar de mayor rendimiento, alcanzando valores de hasta el 70% y, por el contrario, la lignina alcanzó muy bajos rendimientos, no sobrepasando el 13%.
Para analizar el bioproducto solido obtenido se realizó un análisis termogravimétrico. A partir de estos datos, se propuso un nuevo método denominado ‘desplazamiento’ que refleja las diferencias entre los perfiles del producto sólido logrado y la biomasa no tratada.
También se utilizaron técnicas de HPLC y MALDI-TOF-MS que demostraron mayores concentraciones en los bioproductos líquidos obtenidos según aumentaba la temperatura de reacción.University of NottinghamGrado en Ingeniería Químic
Measuring dispersion in the context of ordered qualitative scales
Producción CientíficaThe main purpose of this contribution is to measure the dispersion associated with the different results of a variable when they form a set of linguistic terms obtained after examining different qualities of people, services, etc, ordered, but with a non-homogeneous and non-quantifiable distance between the linguistic terms.Ministerio de Economía, Industria y Competitividad (project ECO2016-77900-P
Gauge Transformations, Twisted Poisson Brackets and Hamiltonization of Nonholonomic Systems
In this paper we study the problem of Hamiltonization of nonholonomic systems
from a geometric point of view. We use gauge transformations by 2-forms (in the
sense of Severa and Weinstein [29]) to construct different almost Poisson
structures describing the same nonholonomic system. In the presence of
symmetries, we observe that these almost Poisson structures, although gauge
related, may have fundamentally different properties after reduction, and that
brackets that Hamiltonize the problem may be found within this family. We
illustrate this framework with the example of rigid bodies with generalized
rolling constraints, including the Chaplygin sphere rolling problem. We also
see how twisted Poisson brackets appear naturally in nonholonomic mechanics
through these examples
Past observable dynamics of a continuously monitored qubit
Monitoring a quantum observable continuously in time produces a stochastic
measurement record that noisily tracks the observable. For a classical process
such noise may be reduced to recover an average signal by minimizing the mean
squared error between the noisy record and a smooth dynamical estimate. We show
that for a monitored qubit this usual procedure returns unusual results. While
the record seems centered on the expectation value of the observable during
causal generation, examining the collected past record reveals that it better
approximates a moving-mean Gaussian stochastic process centered at a distinct
(smoothed) observable estimate. We show that this shifted mean converges to the
real part of a generalized weak value in the time-continuous limit without
additional postselection. We verify that this smoothed estimate minimizes the
mean squared error even for individual measurement realizations. We go on to
show that if a second observable is weakly monitored concurrently, then that
second record is consistent with the smoothed estimate of the second observable
based solely on the information contained in the first observable record.
Moreover, we show that such a smoothed estimate made from incomplete
information can still outperform estimates made using full knowledge of the
causal quantum state.Comment: 11 pages, 4 figure
Hitchin-Kobayashi correspondence, quivers, and vortices
A twisted quiver bundle is a set of holomorphic vector bundles over a complex
manifold, labelled by the vertices of a quiver, linked by a set of morphisms
twisted by a fixed collection of holomorphic vector bundles, labelled by the
arrows. When the manifold is Kaelher, quiver bundles admit natural
gauge-theoretic equations, which unify many known equations for bundles with
extra structure. In this paper we prove a Hitchin--Kobayashi correspondence for
twisted quiver bundles over a compact Kaehler manifold, relating the existence
of solutions to the gauge equations to a stability criterion, and consider its
application to a number of situations related to Higgs bundles and dimensional
reductions of the Hermitian--Einstein equations.Comment: 28 pages; larger introduction, added references for the introduction,
added a short comment in Section 1, typos corrected, accepted in Comm. Math.
Phy
Teaching-innovation experience in competitiveness and innovation in business
The aim of this paper is to contrast the students’ opinions about the teaching innovation experience carried out in the subject “Competitividad en Innovación en la Empresa” (Competitiveness and Innovation in Business). The procedure will start with the subject’s profile, going through the main objectives and teaching methodology, to finish with evaluation and assessment, as suggested in the subject’s syllabus for the academic year 2007/08. Taking this as a starting point and, due to the fact that the number of students in the control group is not very high, we suggest changing both the teaching methodology and the evaluation. These changes will be contrasted with the students’ acceptance and involvement.PROCEEDINGS C
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