2,598 research outputs found
Neural Network Local Navigation of Mobile Robots in a Moving Obstacles Environment
IF AC Intelligent Components and Instruments for Control Applications, Budapest, Hungary, 1994This paper presents a local navigation method based on generalized predictive control. A modified cost function to avoid moving and static obstacles is presented. An Extended Kaiman Filter is proposed to predict the motions of the obstacles. A Neural Network implementation of this method is analysed. Simulation results are shown.Ministerio de Ciencia y Tecnología TAP93-0408Ministerio de Ciencia y Tecnología TAP93-058
Methodology to quantify clogging coefficients for grated inlets: application to SANT MARTI catchment (Barcelona)
This is the accepted version of the following article: Gómez, M, Parés, J, Russo, B, Martínez‐Gomariz, E. Methodology to quantify clogging coefficients for grated inlets. Application to SANT MARTI catchment (Barcelona). J Flood Risk Management. 2019; 12:e12479. https://doi.org/10.1111/jfr3.12479, which has been published in final form at https://onlinelibrary.wiley.com/doi/10.1111/jfr3.12479.Within the drainage system of a city, the set of inlets is in charge of taking the runoff produced by local storms to the stormwater/sewer. In the drainage system design the selection of appropriate inlet models and their location is one of the fundamental aspects. The hydraulics of these inlets has received great attention within the last years; however, few inlet makers provide the hydraulic capacity of their products. In addition, these data usually consider clean water, while in reality, numerous inlets can be either totally or partially clogged. This aspect should be kept in mind within the design process. In this paper, a methodology to consider the hydraulic effects of clogging phenomena is presented. The work started from a visual inspection of the grated inlets throughout the urban catchment of Sant Martí, Barcelona, as a means of identifying clogging patterns, their repetitive forms and their associated frequency. After that, clogged patterns were reproduced in laboratory testing of typical inlets types, thereby obtaining the real quantity of water that could be captured by each of them. It was shown that the same expression employed to describe the efficiency of clean inlets can be used to assess the efficiency of those clogged. A reduction factor in terms of hydraulic capacity and related to each clogging pattern has been defined for use in hydraulic studies of runoff along streets. Finally, the paper compares the obtained results in terms of clogging coefficient with another experimental campaign carried out in other catchment of the city.Peer ReviewedPostprint (author's final draft
Emergence of multilateral proto-institutions in global health and new approaches to governance: analysis using path dependency and institutional theory
The role of multilateral donor agencies in global health is a new area of research, with limited research on how these agencies differ in terms of their governance arrangements, especially in relation to transparency, inclusiveness, accountability, and responsiveness to civil society. We argue that historical analysis of the origins of these agencies and their coalition formation processes can help to explain these differences. We propose an analytical approach that links the theoretical literature discussing institutional origins to path dependency and institutional theory relating to proto institutions in order to illustrate the differences in coalition formation processes that shape governance within four multilateral agencies involved in global health. We find that two new multilateral donor agencies that were created by a diverse coalition of state and non-state actors, such as the Global Fund to Fight AIDS, Tuberculosis and Malaria and GAVI, what we call proto-institutions, were more adaptive in strengthening their governance processes. This contrasts with two well-established multilateral donor agencies, such as the World Bank and the Asian Development Bank, what we call Bretton Woods (BW) institutions, which were created by nation states alone; and hence, have different origins and consequently different path dependent processes
Evolution Operators for Linearly Polarized Two-Killing Cosmological Models
We give a general procedure to obtain non perturbative evolution operators in
closed form for quantized linearly polarized two Killing vector reductions of
general relativity with a cosmological interpretation. We study the
representation of these operators in Fock spaces and discuss in detail the
conditions leading to unitary evolutions.Comment: Accepted for publication in Physical Review
The time-dependent quantum harmonic oscillator revisited: Applications to Quantum Field Theory
In this article, we formulate the study of the unitary time evolution of
systems consisting of an infinite number of uncoupled time-dependent harmonic
oscillators in mathematically rigorous terms. We base this analysis on the
theory of a single one-dimensional time-dependent oscillator, for which we
first summarize some basic results concerning the unitary implementability of
the dynamics. This is done by employing techniques different from those used so
far to derive the Feynman propagator. In particular, we calculate the
transition amplitudes for the usual harmonic oscillator eigenstates and define
suitable semiclassical states for some physically relevant models. We then
explore the possible extension of this study to infinite dimensional dynamical
systems. Specifically, we construct Schroedinger functional representations in
terms of appropriate probability spaces, analyze the unitarity of the time
evolution, and probe the existence of semiclassical states for a wide range of
physical systems, particularly, the well-known Minkowskian free scalar fields
and Gowdy cosmological models.Comment: 31 pages, 3 figures. Accepted for publication in Annals of Physic
Quantum unitary evolution of linearly polarized S^1\times S^2 and S^3 Gowdy models coupled to massless scalar fields
The purpose of this paper is to study in detail the problem of defining
unitary evolution for linearly polarized S^1 x S^2 and S^3 Gowdy models (in
vacuum or coupled to massless scalar fields). We show that in the Fock
quantizations of these systems no choice of acceptable complex structure leads
to a unitary evolution for the original variables. Nonetheless, unitarity can
be recovered by suitable redefinitions of the basic fields. These are dictated
by the time dependent conformal factors that appear in the description of the
standard deparameterized form of these models as field theories in certain
curved backgrounds. We also show the unitary equivalence of the Fock
quantizations obtained from the SO(3)-symmetric complex structures for which
the dynamics is unitarily implemented.Comment: Final version to appear in Classical and Quantum Gravit
Anthropometric measures as predictive indicators of metabolic risk in a population of “holy week costaleros”
Preventive measures are a priority in those groups that perform intense physical efforts without physical preparation and that can also be overweight or obese. One of the groups that reflect these characteristics is the costaleros of the Holy Week of Andalusia, Spain. This paper aims to describe the effect of obesity on blood pressure. A descriptive cross-sectional study was conducted on 101 costaleros. The anthropometric measures were determined through segmental impedance. Cardiac
recovery and anaerobic power were measured through the Ruffier–Dickson test and the Abalakov test, respectively. Blood pressure was measured when the individuals were at rest. The Kruskal–Wallis test was applied for of continuous parameters and the X2 test for dichotomous measures. Binary logistic regression models were used for the subsequent analysis with R-square and Receiver Operating Characteristic (ROC) curves. The average population was 28 years of age, 173.7 cm tall, and 82.59 Kg weigh. The excess of body fat was 11.27 Kg and Body Mass Index was 27.33 Kg/m2. 72.3% showed abnormal blood pressure and 68.2% were overweight. 32.7% had a waist-hip ratio higher than 0.94. The probability of presenting abnormal blood pressure was higher among the subjects whose fat content was higher and muscle content was lower
RESEÑAS
La historiografía tradicional a considerado a El Chocó cómo unaunidad geográfica y cultural. Este trabajo se inscribe dentro de la nuevatendencia de estudios que pretenden revaluar dicho postulado. Justificarque El Chocó del siglo XVIII estaba conformado por tres territoriosheterogéneos; y no sólo a nivel fisiográfico, debido a que seencontraban divididos por las fronteras naturales que establecían lastres vertientes de los ríos Atrato, Baudó y San Juan, sino también por laexistencia entre ellos de procesos de poblamiento y construccióndisímiles; es sin duda la tesis central que el historiador Orían Jiménezarguye en dicho libro
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