1,489 research outputs found
Arquitectura human-robot scaffolding
This study presents the advances in the design of the architecture called Human-Robot Scaffolding. The Architecture allows an anthropomorphic social robot to intervene assertively during the learning of the Mean-Fines analysis strategy. Its design recognizes three aspects. Firstly, the scaffolding educational strategy. Second, the psychological theory of Flow. Third, the paradigm BDI agents for the execution of the robot's goals. The partial validation of the architecture has been done with 20 children between 10 and 13 years old from two schools in Colombia. According to the results, the modules and the goals proposed in the architecture promote in an assertive way the learning of the Mean-Fines analysis strategy.El documento presenta los avances en el diseño de la arquitectura llamada Human-Robot Scaffolding. La arquitectura permite que un robot social antropomórfico intervenga de manera asertiva durante el aprendizaje de la estrategia de análisis de Medios-Fines. Su diseño reconoce tres aspectos. Primero, la estrategia educativa de andamiaje. Segundo, la teorÃa psicológica del Fluir. Tercero, el paradigma de agentes BDI para la ejecución de las metas del robot. La validación parcial de la arquitectura ha sido hecha con 20 niños entre 10 y 13 años de dos colegios en Colombia. De acuerdo a los resultados, los módulos y las metas propuestas en la arquitectura promueven de manera asertiva el aprendizaje de la estrategia de análisis de Medios-Fines
Heterogeneous data source integration for smart grid ecosystems based on metadata mining
The arrival of new technologies related to smart grids and the resulting ecosystem of applications andmanagement systems pose many new problems. The databases of the traditional grid and the variousinitiatives related to new technologies have given rise to many different management systems with several formats and different architectures. A heterogeneous data source integration system is necessary toupdate these systems for the new smart grid reality. Additionally, it is necessary to take advantage of theinformation smart grids provide. In this paper, the authors propose a heterogeneous data source integration based on IEC standards and metadata mining. Additionally, an automatic data mining framework isapplied to model the integrated information.Ministerio de EconomÃa y Competitividad TEC2013-40767-
A new geometrical method for 3D evaluation of non-rigid registration methods for radiotherapy in prostate cancer
Three-dimensional conformal radiotherapy aims at delivering a high dose of radiation to the tumour, while sparing the surrounding normal tissue to a maximum extent. Image registration is an essential tool for monitoring radiation therapies, since allows morphological comparisons in presence of anatomic variations. The evaluation of non-rigid registration methods is very complicated owe to the absence of a known pointwise correspondence. The use of analysis of variations in target volume delineations has been proposed in the past for the evaluation of non-rigid registration methods. Delineation of the target volume is usually accomplished by outlining the contour of the volume in each separate tomographic slice. In the studies of reference, the 3D surface is rendered from the contours by means of a Delauney triangulation. This geometrical method only works correctly for convex structures. However the volumes involved on pelvic anatomy, such as bladder or prostate including the seminal vesicles, have relevant concavities that introduce a huge error in the evaluation. A new geometrical method for the evaluation of convex-concave target volumes delineation is proposed
Overview and comparative study of two control strategies used in 3-phase grid-connected inverters for renewable systems
In this paper, an overview of grid-connected renewable systems is presented, then twocurrent-control strategies for 3-phase grid-connected inverters are analyzed: firstly, the well-known d-q control in the rotating synchronous reference frame (d-q axes) using
Proportional Integral regulators is described, and secondly, the Proportional Resonant controller in the stationary reference frame (αβ axes). In order to obtain a high efficiency of the system when the 3-phase utility grid voltages are affected by harmonic pollution, a Harmonic Compensator (HC) structure is used with the Proportional Resonant controller, this due to the ease way to compensate harmonics when a Proportional Resonant control is utilized instead of a d-q control. Then both control strategies (d-qcontrol and PR+HC) are analyzed under harmonic pollution condition. For both strategies, a Positive Sequence Detector plus a Synchronous Reference Frame PhaseLook Loop (PSD+dqPLL) is used as the synchronization algorithm. After the study, it was observed that the PR controller provides a greater facility for carrying out the harmonic compensation process helping to fulfil with the international standards.
A model of a grid-connected photovoltaic system with a nominal power of 10kW is used to evaluate and compare the performance of the current-control strategies. For this, a Real-Time Digital Simulator (RTDS) platform is used.This work has been supported by a grant from La Fundación Séneca, Agencia de Ciencia y TecnologÃa de la Región de Murcia,
Spain, as a part of the Project Ref.11948/PI/09, entitled ‘‘Design and construction of a hardware/software prototype for the
synchronization and monitoring of renewable agents in a Distributed Generation System’’
Null controllability of the heat equation with boundary Fourier conditions: the linear case
In this paper, we prove the global null controllability of the linear heat equation completed with linear Fourier boundary conditions of the form ∂y
∂n + β y = 0. We consider distributed controls with support in a small set and nonregular coefficients β = β(x, t). For the proof of null controllability,
a crucial tool will be a new Carleman estimate for the weak solutions of the classical heat equation with nonhomogeneous Neumann boundary conditions.Ministerio de Educación y Cienci
Exact controllability to the trajectories of the heat equation with Fourier boundary conditions: the semilinear case
This paper is concerned with the global exact controllability of the semilinear heat equation (with nonlinear terms involving the state and the gradient) completed with boundary conditions of the form ∂y ∂n + f(y) = 0. We consider distributed controls, with support in a small set. The null controllability of similar linear systems has been analyzed in a previous first part of this work. In this second part we show that, when the nonlinear terms are locally Lipschitz-continuous and slightly superlinear, one has exact controllability to the trajectories.Ministerio de Educación y Cienci
New results on the Stackelberg-Nash exact control of linear parabolic equations
This paper is concerned with Stackelberg-Nash strategies to control parabolic equations. We have one control, the leader, that is responsible for a null controllability property; additionally, we have a couple of controls, called the followers, that provides a Nash equilibrium for two cost functionals. This is a classical situation in many fields of science and, in mathematics, leads to a lot of interesting questions and open problems and possesses many applications. In the main result, we prove the existence of a leader such that the corresponding controlled system is driven to zero. This way, we improve some questions that were left open in previous works.Instituto Nacional de Ciência e Tecnologia de Matemática, Coordenação de aperfeiçoamento de pessoal de nivel superior (Conselho Nacional de Desenvolvimento CientÃfico e Tecnológico)Mathamsud (Control Systems and Identification Problems)Ministerio de Ciencia e Innovació
Some controllability results for the N-Dimensional Navier-Stokes and Boussinesq systems with N-1 scalar controls
In this paper we deal with some controllability problems for systems of the Navier-Stokes and Boussinesq kind with distributed controls supported in small sets. Our main aim is to control N-dimensional systems (N + 1 scalar unknowns in the case of the Navier–Stokes equations) with N − 1 scalar control functions. In a first step, we present some global Carleman estimates
for suitable adjoint problems of linearized Navier–Stokes and Boussinesq systems. In this way, we obtain null controllability properties for these systems. Then, we deduce results concerning the local exact controllability to the trajectories. We also present (global) null controllability results for some (truncated) approximations of the Navier–Stokes equations.Ministerio de Educación y Cienci
Systematic Review of Plasmid AmpC Type Resistances in Escherichia coli and Klebsiella pneumoniae and Preliminary Proposal of a Simplified Screening Method for ampC
Beta-lactamase (BL) production is a major public health problem. Although not the most
frequent AmpC type, AmpC-BL is increasingly isolated, especially plasmid AmpC-BL (pAmpCBL).
The objective of this study was to review information published to date on pAmpC-BL in
Escherichia coli and Klebsiella pneumoniae, and on the epidemiology and detection methods used by
clinical microbiology laboratories, by performing a systematic review using the MEDLINE PubMed
database. The predictive capacity of a screening method to detect AmpC-BL using disks with
cloxacillin (CLX) was also evaluated by studying 102 Enterobacteriaceae clinical isolates grown in
CHROMID ESBL medium with the addition of cefepime (FEP), cefoxitin (FOX), ertapenem (ETP),
CLX, and oxacillin with CLX. The review, which included 149 publications, suggests that certain
risk factors (prolonged hospitalization and previous use of cephalosporins) are associated with
infections by pAmpC-BL-producing microorganisms. The worldwide prevalence has increased over
the past 10 years, with a positivity rate ranging between 0.1 and 40%, although AmpC was only
detected when sought in a targeted manner. CMY-2 type has been the most prevalent pAmpC-BLproducing
microorganism. The most frequently used phenotypic method has been the double-disk
synergy test (using CLX disks or phenyl-boronic acid and cefotaxime [CTX] and ceftazidime) and
the disk method combined with these inhibitors. In regard to screening methods, a 1- g oxacillin
disk with CLX showed 88.9% sensitivity, 100% specificity, 100% positive predictive value (PPV),
98.9% negative predictive value (NPV), and 98.9% validity index (VI). This predictive capacity
is reduced with the addition of extended-spectrum beta-lactamases, showing 62.5% sensitivity,
100% specificity, 100% PPV, 93.5% NPV, and 94.1% VI. In conclusion, there has been a worldwide
increase in the number of isolates with pAmpC-BL, especially in Asia, with CMY-2 being the most
frequently detected pAmpC-BL-producing type of microorganism. Reduction in its spread requires
routine screening with a combination of phenotypic methods (with AmpC inhibitors) and genotypic
methods (multiplex PCR). In conclusion, the proposed screening technique is an easy-to-apply and
inexpensive test for the detection of AmpC-producing isolates in the routine screening of multidrugresistant
microorganisms
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