Analog implementation of a robust control strategy for mechanical systems

An analog implementation of a control structure with disturbance identification for mechanical systems is presented. This control structure is based on a discontinuous observer that estimates the state and the disturbances in the plant, improving the robustness of the closed loop system which also displays a control input free from chattering. The control structure, built with operational amplifiers, is simple, showing good performance for stabilization, regulation, and tracking objectives. The performance of the circuit is compared with a digital implementation based on a real-time data acquisition card to control a simple pendulum. In addition, the circuit performance is illustrated on an industrial 2-DOF robot

Grass-Legume Mixtures Under Grazing

Nine grass-legume mixtures were evaluated during their first year. A factorial experiment was carried out using a complete block design. Herbage on offer and residual herbage were estimated allowing calculation of net herbage production, herbage accumulation rate and grazing efficiency. The mixture of alfalfa (Medicago sativa L.) and orchard grass (Dactylis glomerata L.) with a net herbage production of 22 407 kg dry matter (DM) per ha outyielded white clover (Trifolium repens L.) mixtures. Substitution of alfalfa by white clover in the mixtures resulted in reduction of herbage accumulation rate by 19 kg DM ha-1 day-1 . Net herbage production of mixtures including orchard grass was 2800 kg DM higher than that of mixtures including perennial ryegrass (Lolium perenne L.). Net herbage production of mixtures including tall fescue (Festuca arundinacea Schreb) was similar to that of mixtures including orchard grass or perennial ryegrass

Within-wing isotopic (δ2H, δ13C, δ15N) variation of monarch butterflies: implications for studies of migratory origins and diet

Increasingly, stable isotope measurements are being used to assign individuals to broad geographic origins based on established relationships between animal tissues and tissue-specific isoscapes. In particular, the eastern North American population of the monarch butterfly (Danaus plexippus) has been the subject of several studies using established δ2H and δ13C wing-tissue isoscapes to infer natal origins of migrating and overwintering individuals. However, there has been no study investigating potential variance that can derive from sub-sampling different regions of the wings, especially those regions differing in pigmentation (orange versus black). Within-wing isotopic (δ2H, δ13C, δ15N) variance of 40 monarch butterflies collected from natural overwinter mortality on Mexican roost sites were split evenly into two groups: unwashed samples and those washed in a 2:1 chloroform:methanol solvent. Isotopic variance in δ2H and δ13C was related to pigment (within-wing range 5‰ and 0.5‰, respectively), but not region of subsampling. This variance was reduced 3 to 4 fold through solvent washing that removed pigmented surface scales and any adhered oils. Wing δ15N was similarly influenced by pigment (range 0.3‰), but this effect was not reduced through washing. We recommend future isotopic studies of monarchs and other butterflies for migration research to use the same region for sub-sampling consistently and to wash samples with solvent to reduce isotopic variance related to uncontrolled variance in discrimination (δ2H, δ13C, δ15N) and/or adsorbed water vapor (δ2H). These data also need to be included in description of methods

Efectividad de los jugadores de futsal según sus posiciones

Introducción: La lógica interna del futbol sala está formada por ataque y defensa que implican continuas transiciones ofensivas y defensivas y ocasiones de gol. Esta gran movilidad en ataque tiene como finalidad provocar y aprovechar un desequilibrio en el esquema táctico defensivo contrario, creando así un efecto sorpresa de incertidumbre que genere una opción clara de finalización y así poder anotar gol. Existen estudios que explican cómo, cuándo se consiguen los goles pero no existe ninguno que diga quién los consigue. El objetivo de este trabajo es saber cómo se distribuyen los goles entre los diferentes tipos de jugadores en las mejores ligas europeas de fútbol sala. Método: Estudio cuantitativo, descriptivo. La muestra asciende a 110 partidos en la liga italiana (11 equipos), 240 en la liga española (16 equipos) y 273 en la liga rusa (14 equipos), lo que supone un total de 623 partidos de los que se han podido analizar 619 y una muestra (n) alcanzada de 4716 goles de la temporada 2.014-2.015. Para la recogida de datos se han utilizado las actas de los partidos. Datos descriptivos dados en frecuencias, medias y porcentajes y estadística inferencial utilizando Chi-cuadrado para establecer la relación entre variables. Resultados y conclusiones: Los resultados establecen que existe una relación directa entre las posiciones de partida y la consecución de goles. Así, el pívot obtiene un 40, 37% de los goles, seguido por los alas con un 37, 24%, los cierres con un 19, 64%. Introduction: The internal logic of futsal consists of attack and defense involving continuous offensive and defensive transitions and goal chances. This great mobility in attack aims to provoke and take advantage of an imbalance in the opposing defensive tactical scheme, creating a surprise uncertainty effect that generates clear chances of finishing and thus scoring goals. There exist studies explaining how, or when, goals are achieved; however, none discusses who gets them. The objective of this paper is to assess how goals are distributed among the different types of players in the best European futsal leagues. Method: Quantitative, descriptive study. The sample consists of 110 matches in the Italian league (11 teams), 240 in the Spanish league (16 teams), and 273 in the Russian league (14 teams), with a total of 619 matches analyzed on a total of 623 available, and a sample (n) of 4, 716 goals scored during the season 2014-2015. For the collection of data, match minutes were used. Descriptive data was presented in frequencies, means and percentages, whilst inferential statistics were run using Chi-square to establish the relationship between variables. Results and conclusions: The results establish that there is a direct relationship between starting positions and achievement of goals. Pivots get 40.37% of the total goals, followed by wings with 37.24%, and closures with 19.64%

Momentos críticos del partido en las mejores ligas europeas de fútbol sala

El presente estudio pretende determinar los momentos críticos donde se consigue el mayor número de goles en la competición de fútbol sala estableciendo diferencias entre las mejores ligas europeas según títulos conseguidos. Material y método: se trata de un estudio cuantitativo, descriptivo y comparativo entre las ligas española, italiana y rusa durante la temporada 2014-2015. La muestra asciende a la totalidad de la población objeto de estudio, que corresponde a 110 partidos en la liga italiana (11 equipos), 240 en la liga española (16 equipos) y 273 en la liga rusa (14 equipos), lo que supone un total de 623 partidos de los que se han podido analizar 619 y una muestra (n) alcanzada de 4716 goles, de los que se han podido analizar 4468. Para el registro de los goles se ha dividido la variable tiempo en intervalos de 5 minutos. Se há utilizado uma estadística descriptiva e inferencial en la búsqueda de relaciones asociativas entre variables categóricas. Resultados: se obtiene que los momentos con más goles del partido son los últimos 10 minutos de la segunda parte y los últimos 5 minutos de la primera parte. Además se determina que las tres mejores ligas europeas se comportan de la misma manera no encontrando diferencias significativas entre ellas. Estos resultados proporcionan información útil sobre las características de los partidos que ayudan a entender mejor la lógica interna de este deporte. The presented research is a quantitative, descriptive and comparative study whose objective is to determine the critical moments of the futsal match by dividing the time variable up to 5 minute intervals, establishing if there are differences between the best European leagues according to titles obtained; Spanish, Italian and Russian league, during the 2014-2015 season. The sample amounts to the entire population under study, corresponding to 110 matches in the Italian league (11 teams), 240 in the Spanish league (16 teams) and 273 in the Russian league (14 teams), which means a total of 623 matches of which 619 have been analyzed and a sample (n) reached of 4716 goals, of which 4468 have been analyzed. The results obtained establish that the moments with the most goals of the game are the last 10 minutes of the second part and the last 5 minutes of the first part. In addition it is determined that the three best European leagues behave in the same way, not finding significant differences between them

Momentos críticos del partido en las mejores ligas europeas de fútbol sala

El presente estudio pretende determinar los momentos críticos donde se consigue el mayor número de goles en la competición de fútbol sala estableciendo diferencias entre las mejores ligas europeas según títulos conseguidos. Material y método: se trata de un estudio cuantitativo, descriptivo y comparativo entre las ligas española, italiana y rusa durante la temporada 2014-2015. La muestra asciende a la totalidad de la población objeto de estudio, que corresponde a 110 partidos en la liga italiana (11 equipos), 240 en la liga española (16 equipos) y 273 en la liga rusa (14 equipos), lo que supone un total de 623 partidos de los que se han podido analizar 619 y una muestra (n) alcanzada de 4716 goles, de los que se han podido analizar 4468. Para el registro de los goles se ha dividido la variable tiempo en intervalos de 5 minutos. Se há utilizado uma estadística descriptiva e inferencial en la búsqueda de relaciones asociativas entre variables categóricas. Resultados: se obtiene que los momentos con más goles del partido son los últimos 10 minutos de la segunda parte y los últimos 5 minutos de la primera parte. Además se determina que las tres mejores ligas europeas se comportan de la misma manera no encontrando diferencias significativas entre ellas. Estos resultados proporcionan información útil sobre las características de los partidos que ayudan a entender mejor la lógica interna de este deporte. The presented research is a quantitative, descriptive and comparative study whose objective is to determine the critical moments of the futsal match by dividing the time variable up to 5 minute intervals, establishing if there are differences between the best European leagues according to titles obtained; Spanish, Italian and Russian league, during the 2014-2015 season. The sample amounts to the entire population under study, corresponding to 110 matches in the Italian league (11 teams), 240 in the Spanish league (16 teams) and 273 in the Russian league (14 teams), which means a total of 623 matches of which 619 have been analyzed and a sample (n) reached of 4716 goals, of which 4468 have been analyzed. The results obtained establish that the moments with the most goals of the game are the last 10 minutes of the second part and the last 5 minutes of the first part. In addition it is determined that the three best European leagues behave in the same way, not finding significant differences between them

Cardiovascular involvement and manifestations of systemic Chikungunya virus infection: A systematic review [version 2; referees: 1 approved, 2 approved with reservations]

Background: In the last three years, chikungunya virus disease has been spreading, affecting particularly the Americas, producing more than two million cases. In this setting, not only new disease-related epidemiological patterns have been found, but also new clinical findings have been reported by different research groups. These include findings on the cardiovascular system, including clinical, electrocardiographic and echocardiographic alterations. No previous systemic reviews have been found in major databases about it. Methods: We performed a systematic review looking for reports about cardiovascular compromise during chikungunya disease. Cardiac compromise is not so common in isolated episodes; but countries where chikungunya virus is an epidemic should be well informed about this condition. We used 6 bibliographical databases as resources: Medline/Pubmed, Embase, ScienceDirect, ClinicalKey, Ovid and SciELO. Dengue reports on cardiovascular compromise were included as well, to compare both arbovirus’ organic compromises. Articles that delved mainly into the rheumatic articular and cutaneous complications were not considered, as they were not in line with the purpose of this study. The type of articles included were reviews, meta-analyses, case-controls, cohort studies, case reports and case series. This systematic review does not reach or performed a meta-analysis. Results: Originally based on 737 articles, our reviewed selected 40 articles with 54.2% at least mentioning CHIKV cardiovascular compromise within the systemic compromise. Cardiovascular manifestations can be considered common and have been reported in France, India, Sri Lanka, Malaysia, Colombia, Venezuela and USA, including mainly, but no limited to: hypotension, shock and circulatory collapse, Raynaud phenomenon, arrhythmias, murmurs, myocarditis, dilated cardiomyopathy, congestive insufficiency, heart failure and altered function profile (Troponins, CPK). Conclusions: Physicians should be encouraged to keep divulgating reports on the cardiovascular involvement of chikungunya virus disease, to raise awareness and ultimately encourage suitable diagnosis and intervention worldwide. More research about cardiovascular involvement and manifestations of systemic Chikungunya virus infection is urgently needed

Gamma-Ray Bursts in Circumstellar Shells: A Possible Explanation for Flares

It is now generally accepted that long-duration gamma ray bursts (GRBs) are due to the collapse of massive rotating stars. The precise collapse process itself, however, is not yet fully understood. Strong winds, outbursts, and intense ionizing UV radiation from single stars or strongly interacting binaries are expected to destroy the molecular cloud cores that give birth to them and create highly complex circumburst environments for the explosion. Such environments might imprint features on GRB light curves that uniquely identify the nature of the progenitor and its collapse. We have performed numerical simulations of realistic environments for a variety of long-duration GRB progenitors with ZEUS-MP, and have developed an analytical method for calculating GRB light curves in these profiles. Though a full, three-dimensional, relativistic magnetohydrodynamical computational model is required to precisely describe the light curve from a GRB in complex environments, our method can provide a qualitative understanding of these phenomena. We find that, in the context of the standard afterglow model, massive shells around GRBs produce strong signatures in their light curves, and that this can distinguish them from those occurring in uniform media or steady winds. These features can constrain the mass of the shell and the properties of the wind before and after the ejection. Moreover, the interaction of the GRB with the circumburst shell is seen to produce features that are consistent with observed X-ray flares that are often attributed to delayed energy injection by the central engine. Our algorithm for computing light curves is also applicable to GRBs in a variety of environments such as those in high-redshift cosmological halos or protogalaxies, both of which will soon be targets of future surveys such as JANUS or Lobster.Comment: 12 pages, 5 figures, Accepted by Ap