16,546 research outputs found
A unification in the theory of linearization of second order nonlinear ordinary differential equations
In this letter, we introduce a new generalized linearizing transformation
(GLT) for second order nonlinear ordinary differential equations (SNODEs). The
well known invertible point (IPT) and non-point transformations (NPT) can be
derived as sub-cases of the GLT. A wider class of nonlinear ODEs that cannot be
linearized through NPT and IPT can be linearized by this GLT. We also
illustrate how to construct GLTs and to identify the form of the linearizable
equations and propose a procedure to derive the general solution from this GLT
for the SNODEs. We demonstrate the theory with two examples which are of
contemporary interest.Comment: 8 page
Vortex-antivortex annihilation in mesoscopic superconductors with a central pinning center
In this work we solved the time-dependent Ginzburg-Landau equations, TDGL, to
simulate two superconducting systems with different lateral sizes and with an
antidot inserted in the center. Then, by cycling the external magnetic field,
the creation and annihilation dynamics of a vortex-antivortex pair was studied
as well as the range of temperatures for which such processes could occur. We
verified that in the annihilation process both vortex and antivortex acquire an
elongated format while an accelerated motion takes place.Comment: 4 pages, 5 figures, work presented in Vortex VII
A Method to Tackle First Order Differential Equations with Liouvillian Functions in the Solution - II
We present a semi-decision procedure to tackle first order differential
equations, with Liouvillian functions in the solution (LFOODEs). As in the case
of the Prelle-Singer procedure, this method is based on the knowledge of the
integrating factor structure.Comment: 11 pages, late
On the distribution of high-frequency stock market traded volume: a dynamical scenario
This manuscript reports a stochastic dynamical scenario whose associated
stationary probability density function is exactly a previously proposed one to
adjust high-frequency traded volume distributions. This dynamical conjecture,
physically connected to superstatiscs, which is intimately related with the
current nonextensive statistical mechanics framework, is based on the idea of
local fluctuations in the mean traded volume associated to financial markets
agents herding behaviour. The corroboration of this mesoscopic model is done by
modelising NASDAQ 1 and 2 minute stock market traded volume
Public Health England's recovery tools: potential teaching resources?
The file attached to this record is the author's final peer reviewed version.Training to combat chemical and radiation accidents, incidents or attacks is critical for health professionals
due to recent events involving these hazards or their use as unconventional weapons, such as the use of
the nerve agent novichok in Salisbury, UK. Health professionals need to have appropriate knowledge and
skills to effectively respond to future events involving any of these substances, which requires a rapid and
coordinated response from different professionals to protect the environment and minimise the number of
people exposed and reduce morbidity and mortality. However, despite chemical and radiation incidents
becoming increasingly prevalent, literature reviews have shown that there is a lack of teaching of
appropriate competences to face future crises in Europe, particularly amongst clinicians and other health
professionals that would be part of the initial response. Thus, De Montfort University (DMU, UK) in
collaboration with different academics from the University of Alcalá (Spain) and researchers from Public
Health England (PHE) with comprehensive experience in environmental decontamination and restoration,
have created a short training course for providing undergraduate/postgraduate students with basic skills
to respond to chemical incidents, basic skills that are based on the major competences recently identified
by the European Commission [1]. This novel training has been tested with students from different
backgrounds in various European universities, recording high degrees of acquisition of the various basic
competences that we developed to initially respond to chemical events [2]. To develop the practical part
of this chemical training, we have incorporated the novel guidance and methodology developed by PHE
to successfully tailor a protection and recovery response to any incident involving chemical substances,
which is available in the “UK Recovery Handbook for Chemical Incidents” [3] and its web-based tools:
“Chemical Recovery Navigation Tool” (CRNT, [4]) and “Chemical Recovery Record Form” (CRRF, [5]).
These innovative resources aid the user to select effective protection, decontamination and restoration
techniques or strategies from a pool of up-to-date options applicable to different environments according
to the physicochemical properties of the chemical(s) involved and the area affected. The CRNT is
accompanied by the CRRF, which facilitates collection and analysis of the necessary data to inform
decisions, and an e-learning resource named “Chemical Recovery: Background” (CRB, [6]), which could
facilitate the learning of environmental decontamination and restoration. We are currently developing a
short training course to cover minor radiation incidents; this radiation training will follow the same methods
used to develop the chemical training, but with the specific PHE recovery tools to tackle such events,
specifically the “UK Recovery Handbooks for Radiation Incidents” [7] and its associated web-based tools
“Radiation Recovery Navigation Tool” (Rad RNT, [8]), one for each environment: food production systems,
inhabited areas and drinking water supplies. This communication will explore the use of the PHE’s
Recovery Navigation Tools as potential resources to facilitate the acquisition of basic knowledge to tailor
protection and recovery interventions for minor chemical and radiation incidents to protect the public
Communications-Inspired Projection Design with Application to Compressive Sensing
We consider the recovery of an underlying signal x \in C^m based on
projection measurements of the form y=Mx+w, where y \in C^l and w is
measurement noise; we are interested in the case l < m. It is assumed that the
signal model p(x) is known, and w CN(w;0,S_w), for known S_W. The objective is
to design a projection matrix M \in C^(l x m) to maximize key
information-theoretic quantities with operational significance, including the
mutual information between the signal and the projections I(x;y) or the Renyi
entropy of the projections h_a(y) (Shannon entropy is a special case). By
capitalizing on explicit characterizations of the gradients of the information
measures with respect to the projections matrix, where we also partially extend
the well-known results of Palomar and Verdu from the mutual information to the
Renyi entropy domain, we unveil the key operations carried out by the optimal
projections designs: mode exposure and mode alignment. Experiments are
considered for the case of compressive sensing (CS) applied to imagery. In this
context, we provide a demonstration of the performance improvement possible
through the application of the novel projection designs in relation to
conventional ones, as well as justification for a fast online projections
design method with which state-of-the-art adaptive CS signal recovery is
achieved.Comment: 25 pages, 7 figures, parts of material published in IEEE ICASSP 2012,
submitted to SIIM
- …