DSpace Collection:
http://hdl.handle.net/2117/3919
2015-04-21T03:00:55ZAn A-infinity operad in spineless cacti
http://hdl.handle.net/2117/27453
Title: An A-infinity operad in spineless cacti
Authors: Gálvez Carrillo, Maria Immaculada
Abstract: The d.g. operad C of cellular chains on the operad of spineless cacti is isomorphic to the Gerstenhaber-Voronov operad codifying the cup product and brace operations on the Hochschild cochains of an associative algebra, and to the suboperad F_2X of the surjection operad. Its homology is the Gerstenhaber operad G. We construct an operad map psi from A-infinity to C such that psi(m_2) is commutative and the homology of psi is the canonical map A \to Com \to G. This formalises the idea that, since the cup product is commutative in homology, its symmetrisation is a homotopy associative operation. Our explicit A-infinty structure does not vanish on non-trivial shuffles in higher degrees, so does not give a map from Com-infinity to C. If such a map could be written down explicitly, it would immediately lead to a G-infinity structure on C and on Hochschild cochains, that is, to a direct proof of the Deligne conjecture2015-04-20T08:18:35ZOn the complexity of exchanging
http://hdl.handle.net/2117/27400
Title: On the complexity of exchanging
Authors: Molinero Albareda, Xavier; Olsen, Martin; Serna Iglesias, María José
Abstract: We analyze the computational complexity of the problem of deciding
whether, for a given simple game, there exists the possibility of rearranging the participants in a set of j given losing coalitions into a set of j winning coalitions. We also look at the problem of turning winning coalitions into losing coalitions. We analyze the problem when the simple game is represented by a list of wining, losing, minimal winning or maximal loosing coalitions.2015-04-16T17:13:57ZPositivity properties of relative complete intersections
http://hdl.handle.net/2117/27353
Title: Positivity properties of relative complete intersections
Authors: Barja Yáñez, Miguel Ángel; Stoppino, Lidia
Abstract: We give conditions for f-positivity of relative complete intersections in projective bundles. We
also derive an instability result for the fibres.
Description: Preprint2015-04-15T11:30:29ZLlibre de problemes de Geometria FME
http://hdl.handle.net/2117/27206
Title: Llibre de problemes de Geometria FME
Authors: Prats Duaygues, Francesc
Description: Enunciats de problemes de l'assignatura Geometria de la llicenciatura de Matemàtiques de la FME2015-04-09T10:54:19ZOn the formulation of closest-point projection algorithms in elastoplasticity. Part II: Globally convergent schemes. With applications to deviatoric and pressure-dependent plastic models.
http://hdl.handle.net/2117/26972
Title: On the formulation of closest-point projection algorithms in elastoplasticity. Part II: Globally convergent schemes. With applications to deviatoric and pressure-dependent plastic models.
Authors: Pérez Foguet, Agustí; Armero, Francisco
Description: Report UCB/SEMM 2000-02 - Dept. of Civil Engineering - University of California at Berkeley, USA2015-03-24T11:41:44ZMetas e indicadores post 2015 en agua y saneamiento: una revisión desde un enfoque de derechos humanos
http://hdl.handle.net/2117/26971
Title: Metas e indicadores post 2015 en agua y saneamiento: una revisión desde un enfoque de derechos humanos
Authors: Pérez Foguet, Agustí; Flores Baquero, Óscar; Giné Garriga, Ricard; Jiménez Fernández de Palencia, Alejandro2015-03-24T11:32:53ZA note on symplectic and Poisson linearization of semisimple Lie algebra actions
http://hdl.handle.net/2117/26960
Title: A note on symplectic and Poisson linearization of semisimple Lie algebra actions
Authors: Miranda Galcerán, Eva
Abstract: In this note we prove that an analytic symplectic action of a semisimple Lie algebra can be locally linearized in Darboux coordinates. This result yields simultaneous analytic linearization for Hamiltonian vector fields in a neighbourhood of a common zero. We also provide an example of smooth non-linearizable Hamiltonian action with semisimple linear part. The smooth analogue only holds if the semisimple Lie algebra is of compact type. An analytic equivariant b-Darboux theorem for b-Poisson manifolds and an analytic equivariant Weinstein splitting theorem for general Poisson manifolds are also obtained in the Poisson setting2015-03-23T16:46:48ZNon-integrability of measure preserving maps via Lie symmetries
http://hdl.handle.net/2117/26843
Title: Non-integrability of measure preserving maps via Lie symmetries
Authors: Cima Mollet, Anna; Gasull Embid, Armengol; Mañosa Fernández, Víctor
Abstract: We consider the problem of characterizing, for certain natural
number m, the local C^m-non-integrability near
elliptic fixed points of smooth planar measure preserving maps. Our
criterion relates this non-integrability with the existence of some
Lie Symmetries associated to the maps, together with the study of
the finiteness of its periodic points. One of the steps in the proof
uses the regularity of the period function on the whole period
annulus for non-degenerate centers, question that we believe that is
interesting by itself. The obtained criterion can be applied to
prove the local non-integrability of the Cohen map and of several
rational maps coming from second order difference equations.
Description: Preprint.2015-03-19T12:49:35ZInternal report. Numerical methods for medium scale traveling ionospheric disturbances signal pre-processing
http://hdl.handle.net/2117/26832
Title: Internal report. Numerical methods for medium scale traveling ionospheric disturbances signal pre-processing
Authors: Yang, Heng; Monte Moreno, Enrique; Hernández Pajares, Manuel
Abstract: In this paper we discuss the e ects of several signal preprocessing
methods for enhancing the Medium Scale Traveling Ionospheric Dis-
turbances (MSTIDs) signal. The MSTIDs signal are the ionospheric
signatures of waves with a typical scale variation from 50 to 300 m/s,
which can be detected and modeled from variation of the ionospheric
Vertical Total Electron Content (VTEC) with dual-frequency mea-
surements of Global Navigation Satellite Systems (GNSS). In order to
enhance the useful information of the signal, and also reduce the noise,
we purpose the use of di erent numerical methods for preprocessing
the MSTIDs signal. A rst approach to preprocessing the signal is
a simple high-pass ltering or Slant Total Electron Content (STEC)
detrending of the ionospheric carrier phase LI [see Hernndez-Pajares
et al. 2006, Hernndez-Pajares et al. 2012]. In this work, we propose
the following signal processing steps in order to enhance the signal:
(1) Parabolic subtraction adopted in eliminating the typical geometric
length variation within the ionosphere carrier phase LI, (2) decima-
tion techniques used to instead of classic STEC detrending method,
(3) low pass ltering adapted to the properties of the desired signal.
From the results by testing the observing data on the day 1, 2011
obtained from the small area GNSS network in California, it's shown
that the MSTIDs signal after preprocessing techniques are more clear,
smooth and robust.2015-03-19T11:17:45ZInternal report. Solving mixed integer non-linear programming problem applied to GNSS data
http://hdl.handle.net/2117/26831
Title: Internal report. Solving mixed integer non-linear programming problem applied to GNSS data
Authors: Yang, Heng; Monte Moreno, Enrique; Hernández Pajares, Manuel
Abstract: The purpose of this paper is to characterize Medium Scale Trav-
eling Ionospheric Disturbances (MSTIDs), by means of Mixed Integer
Nonlinear Programming (MINLP). The MINLP techniques are used
to for estimating the parameters of the equations that describe the
MSTIDs from a set of observations. A new MSTIDs wave detecting
method, which we will denote as Ambiguity Resolution in Global Navi-
gational Satellite System (GNSS) Ionospheric Interferometry (ARGII)
technique, is designed to model the MSTIDs wave with the data from
the wide low-density GNSS receivers network. The ARGII techniques
can be set as an special instance of MINLP, because the problem is set
as a series of MSTIDs equations including the unknown wave veloc-
ity (continuous) and cycle ambiguities (integers). The performance of
heuristic and direct search optimization algorithms are evaluated by
solving the MINLP problem with techniques bared an di erent prin-
ciples, and as benchmark we use the solution obtained by exhaustive
enumeration of all possible integer solutions. Among the algorithms
we have implemented in this work are genetic algorithm, simulated
annealing, particle swarm, pattern search and Nelder Mead methods.
The GNSS data used to test the these solvers is observed from the wide
GNSS network in the north of Poland on the day 353, 2013 whose di-
ameter is more than the half of wavelength and therefore will have
phase ambiguities. The evaluating experiments show that the results
computed by the simple improved optimization algorithms especially
the Nelder Mead have not only high correlations with the reference
method (i.e. exhaustive enumeration) but also extremely lower time
complexity compared to the benchmark method. Despite unguaran-
teed global optimal results for the MINLP problems, these methods
show the excellent performance in time complexity when computing
the velocities of MSTIDs with ARGII techniques from large quantity
of the GNSS data.
Description: Internal Report2015-03-19T11:14:49ZInternal report. Spectral methods for time delay estimation of MSTIDs signal
http://hdl.handle.net/2117/26830
Title: Internal report. Spectral methods for time delay estimation of MSTIDs signal
Authors: Yang, Heng; Monte Moreno, Enrique; Hernández Pajares, Manuel
Abstract: The primary goal of this work is to summarize spectral meth-
ods to estimate the time delay variations of the detrended Medium
Scale Traveling Ionospheric Disturbances (MSTIDs) signals and pre-
liminarily discuss the potential infuence of the Doppler e fects. The
MSTIDs signals are assumed as the planar waves with the wavelength
between 10-100 kilometers, which are measured from a local high-
dense receivers Global Navigation Satellite System (GNSS) network
for a given satellite. The signals show strong correlation with each
others in the whole observation time series. The time delay of the
detrended MSTIDs signals preprocessed with a speci c overlapped
sliding window can be estimated by several techniques. The data con-
sisted on two detrended MSTIDs signals measured from the GNSS
data on the day 1, 2011 obtained from the small area network in Cal-
ifornia. In this paper we have implemented the following methods
in order to estimate the time delay between signals: (1) Generalized
cross correlation method, which estimates the time delay in time do-
main after the inverse Fourier transform of appropriately weighted
cross power spectrum density, (2) generalized phase spectrum method
directly measured from the appropriately weighted cross power spec-
trum density, (3) phase spectrum di erence method calculated ap-
proximately from the fundamental waves of the signals. The results
with di erent methods show the similar variation of time delay of two
MSTIDs signals. In addition, with the phase spectrum method, the
results can present the clear frequency variation of MSTIDs signals
which may be in
uenced by potential Doppler e ect. Note that the
correct estimate of the delays required of a preprocessing of the data.
The rst di erence of the Vertical Total Electron Contents (dVTEC)
signal was preprocessed by modeling the e ect of the displacement of
the satellite by means of a parabolic component, which is subtracted,
following by detrend of 60-second intervals, decimation and a further
low pass ltering process.
Description: Internal Report2015-03-19T11:11:03ZOn the formulation of closest-point projection algorithms in elastoplasticity. Part I: The variational structure.
http://hdl.handle.net/2117/26702
Title: On the formulation of closest-point projection algorithms in elastoplasticity. Part I: The variational structure.
Authors: Armero, Francisco; Pérez Foguet, Agustí
Abstract: We present in this paper the characterization of the variational structure behind the discrete equa- tions defining the closest-point projection approximation in elastoplasticity. Rate-independent and viscoplastic formulations are considered in the infinitesimal and the finite deformation range, the later in the context of isotropic finite strain multiplicative plasticity. Primal variational prin- ciples in terms of the stresses and stress-like hardening variables are presented first, followed by the formulation of dual principles incorporating explicitly the plastic multiplier. Augmented La- grangian extensions are also presented allowing a complete regularization of the problem in the constrained rate-independent limit. The variational structure identified in this paper leads to the proper framework for the development of new improved numerical algorithms for the integration of the local constitutive equations of plasticity as it is undertaken in Part II of this work.
Description: Report UCB/SEMM 2000-01 - Dept. of Civil Engineering - University of California at Berkeley, USA2015-03-13T14:33:35ZMetas e indicadores post 2015 en agua y saneamiento: una revisión desde un enfoque de derechos humanos
http://hdl.handle.net/2117/26633
Title: Metas e indicadores post 2015 en agua y saneamiento: una revisión desde un enfoque de derechos humanos
Authors: Flores Baquero, Óscar; Giné Garriga, Ricard; Pérez Foguet, Agustí; Jiménez Fernández de Palencia, Alejandro
Description: Informe tècnic2015-03-09T13:45:22ZPost-2015 WASH targets and indicators: a review from a Human Rights Perspective
http://hdl.handle.net/2117/26632
Title: Post-2015 WASH targets and indicators: a review from a Human Rights Perspective
Authors: Flores Baquero, Óscar; Giné Garriga, Ricard; Pérez Foguet, Agustí; Jiménez Fdez de Palencia, Alejandro
Description: Informe tècnic2015-03-09T13:40:53ZApplications of numerical differentiation to computational plasticity
http://hdl.handle.net/2117/26511
Title: Applications of numerical differentiation to computational plasticity
Authors: Pérez Foguet, Agustí; Rodríguez Ferran, Antonio; Huerta, Antonio
Description: Report del Departament de Matemàtica Aplicada III - MA0102015-02-25T13:30:29Z