2,041 research outputs found
Mapping prior information onto LMI eigenvalue-regions for discrete-time subspace identification
In subspace identification, prior information can be used to constrain the
eigenvalues of the estimated state-space model by defining corresponding LMI
regions. In this paper, first we argue on what kind of practical information
can be extracted from historical data or step-response experiments to possibly
improve the dynamical properties of the corresponding model and, also, on how
to mitigate the effect of the uncertainty on such information. For instance,
prior knowledge regarding the overshoot, the period between damped oscillations
and settling time may be useful to constraint the possible locations of the
eigenvalues of the discrete-time model. Then, we show how to map the prior
information onto LMI regions and, when the obtaining regions are non-convex, to
obtain convex approximations.Comment: Under revie
Quaternion-Based Robust Attitude Estimation Using an Adaptive Unscented Kalman Filter
This paper presents the Quaternion-based Robust Adaptive Unscented Kalman Filter (QRAUKF) for attitude estimation. The proposed methodology modifies and extends the standard UKF equations to consistently accommodate the non-Euclidean algebra of unit quaternions and to add robustness to fast and slow variations in the measurement uncertainty. To deal with slow time-varying perturbations in the sensors, an adaptive strategy based on covariance matching that tunes the measurement covariance matrix online is used. Additionally, an outlier detector algorithm is adopted to identify abrupt changes in the UKF innovation, thus rejecting fast perturbations. Adaptation and outlier detection make the proposed algorithm robust to fast and slow perturbations such as external magnetic field interference and linear accelerations. Comparative experimental results that use an industrial manipulator robot as ground truth suggest that our method overcomes a trusted commercial solution and other widely used open source algorithms found in the literature
Weld lines in extrusion: Understanding the role of the flow conditions
This work reports the implemen
tation and verification of a new so
lver in OpenFOAM® open source
computational library, able to cope w
ith integral viscoelastic
models based on the integral upper-convected Maxwell
model. The code is verified through the
comparison of its predictions with anal
ytical solutions and numerical results
obtained with the differential
upper-convected Maxwell modelCAPES, FCT projects PEsT-C/CTM/LA0025/2013, PTDC/MAT/121185/2010 and FEDE
Semiparametric Identification of Hammerstein Systems Using Input Reconstruction and a Single Harmonic Input
Abstract-We present a two-step method for identifying SISO Hammerstein systems. First, using a persistent input with retrospective cost optimization, we estimate a parametric model of the linear system. Next, we pass a single harmonic signal through the system. We use -delay input reconstruction with the parametric model of the linear system to estimate the inaccessible intermediate signal. Using the estimate of the intermediate signal we estimate a nonparametric model of the static nonlinearity, which is assumed to be only piecewise continuous. This method is demonstrated on several numerical and experimental examples of increasing complexity
Ictiofauna de três praias da baía da Ribeira, Angra dos Reis, Rio de JanEiro
O presente trabalho objetiva descrever a composição, a distribuição, a abundância relativa e a riqueza das espécies de peixes que ocorrem em três praias da Baía da Ribeira, situada no município de Angra dos Reis, Rio de Janeiro. Coletas mensais foram realizadas de dezembro de 1998 a janeiro de 2000 em três áreas: a área 1, localizada na praia da Aroeira, a nordeste da Baía da Ribeira; a área 2, localizada na praia do canal do Bracuí, a oeste; e a área 3, localizada na praia do Saco Piraquara de Fora, a sudoeste. Foram capturados 509 espécimes, compreendendo 17 famílias e 28 espécies. As abundâncias relativas das 6 espécies mais representativas por área de coleta foram: Atherinella brasiliensis com 47,9%, Oligoplites saurus com 12%, Diapterus rhombeus com 9,6%, Gerres aprion com 7,3%, Chirocentrodon bleekerianus com 4,1% e Sphoeroides testudineus com 3,7%. A área 1 apresentou maior abundância relativa com 62,9% do total; a área 2 com 30% e a área 3 com 7,1%. A maior riqueza específica foi observada na área 1 com 6,8, seguida da área 3 com 6,0 e da área 2 com 4,1. ABSTRACT Ichthyofauna of three beaches of Ribeira’s bay, Angra dos Reis, Rio de Janeiro The aim of this paper is to describe the composition, the distribution, the relative abundance and the fishes species wealth that occur in three beaches of Baía da Ribeira, situated in Angra dos Reis’ municipal district, Rio de Janeiro. Monthly collections were accomplished from December 1998 to January 2000 in three areas: the area 1, located in the Aroeira beach, the Baía da Ribeira northeast; the area 2, located in the channel beach of Bracuí, to the west; and the area 3, located in the beach of Saco Piraquara de Fora, the southwest. Five hundred and nine specimens were captured, with 17 families comprehending 28 species. The relative abundance of the six more representative species by the collection areas were: Atherinella brasiliensis with 47.9%, Oligoplites saurus with 12%, Diapterus rhombeus with 9.6%, Eucinostomus aprion with 7.3%, Chirocentrodon bleekerianus with 4.1% and Sphoeroides testudineus with 3.7%. The area 1 showed a larger relative abundance with 62.9% from the total; the area 2 with 30% and the area 3 with 7.1%. Fish-species richness was observed in the area 1 with 6.8, followed by the area 3 with 6.0 and by area 2 with 4.1. Key words: Community, fishes, beaches, bay
Nematodes infecting <em>Anotosaura vanzolinia</em> (Squamata: Gymnophthalmidae) from Caatinga, northeastern Brazil
The present study investigated the composition of helminth parasites of the completely unknown lizard Anotosaura vanzolinia (Squamata: Gymnophthalmidae) and evaluated the effects of sex, host size, and seasonality on endoparasite abundance in two areas of Caatinga, northeast Brazil. We collected 110 lizards between May 2013 to June 2014 and found 173 nematodes (overall prevalence: 16.3%), with 49 nematodes infecting seven adult males (prevalence: 25%), 84 nematodes infecting six adult females (Prevalence: 23%), and 40 nematodes infecting five juveniles (prevalence: 8.9%), where one nematode was in the lungs and 172 were in the gastrointestinal tracts. We identified all nematodes as Oswaldocruzia brasiliensis, representing a new record for the host and for Gymnophthalmidade, showing overall intensity of infection ± SD of 9.6 ± 5.2. Furthermore, abundance of endoparasites was related to the rainy season and sex, but not to host body size (SVL)
Nematodes infecting Anotosaura vanzolinia (Squamata: Gymnophthalmidae) from Caatinga, northeastern Brazil
The present study investigated the composition of helminth parasites of the completely unknown lizard Anotosaura vanzolinia (Squamata: Gymnophthalmidae) and evaluated the effects of sex, host size, and seasonality on endoparasite abundance in two areas of Caatinga, northeast Brazil. We collected 110 lizards between May 2013 to June 2014 and found 173 nematodes (overall prevalence: 16.3%), with 49 nematodes infecting seven adult males (prevalence: 25%), 84 nematodes infecting six adult females (Prevalence: 23%), and 40 nematodes infecting five juveniles (prevalence: 8.9%), where one nematode was in the lungs and 172 were in the gastrointestinal tracts. We identified all nematodes as Oswaldocruzia brasiliensis, representing a new record for the host and for Gymnophthalmidade, showing overall intensity of infection ± SD of 9.6 ± 5.2. Furthermore, abundance of endoparasites was related to the rainy season and sex, but not to host body size (SVL)
nutrition and performance in football
Nutrition is an undeniable part of promoting health and performance among football (soccer) players.
Nevertheless, nutritional strategies adopted in elite football can vary significantly depending on culture,
habit and practical constraints and might not always be supported by scientific evidence. Therefore, a group of
28 Portuguese experts on sports nutrition, sports science and sports medicine sought to discuss current practices in the elite football landscape and review the existing evidence on nutritional strategies to be applied when supporting football players. Starting from understanding football?s physical and physiological demands, five different moments were identified: preparing to play, match-day, recovery after matches, between matches and during injury or rehabilitation periods. When applicable, specificities of nutritional support to young athletes and female players were also addressed. The result is a set of practical recommendations that gathered consensus among involved experts, highlighting carbohydrates periodisation, hydration and conscious use of dietary supplements.D915-7373-ED16 | Cesar LeaoN/
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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