210 resultados para deceleration
Resumo:
It is shown that an electromagnetic wave equation in time domain is reduced in paraxial approximation to an equation similar to the Schrodinger equation but in which the time and space variables play opposite roles. This equation has solutions in form of time-varying pulses with the Airy function as an envelope. The pulses are generated by a source point with an Airy time varying field and propagate in vacuum preserving their shape and magnitude. The motion is according to a quadratic law with the velocity changing from infinity at the source point to zero in infinity. These one-dimensional results are extended to the 3D+time case when a similar Airy-Bessel pulse is excited by the field at a plane aperture. The same behaviour of the pulses, the non-diffractive preservation and their deceleration, is found. © 2011 IEEE.
Resumo:
The economic and financial crisis of 2007/2009 has posed unexpected challenges on both the global and the regional level. Besides the US, the EU has been the most severely hit by the current economic crisis. The financial and banking crisis on the one hand and the sovereign debt crisis on the other hand have clearly shown that without a bold, constructive and systematic change of the economic governance structure of the Union, not just the sustainability of the monetary zone but also the viability of the whole European integration process can be seriously undermined. The current crisis is, however, only a symptom, which made all those contradictions overt that were already heavily embedded in the system. Right from the very beginning, the deficit and the debt rules of the Maastricht Treaty and the Stability and Growth Pact have proved to be controversial cornerstones in the fiscal governance framework of the European Economic and Monetary Union (EMU). Yet, member states of the EU (both within and outside of the EMU) have shown an immense interest in adopting numerical constraints on the domestic level without hesitation. The main argument for the introduction of national fiscal rules was mostly to strengthen the accountability and credibility of national fiscal policy-making. The paper, however, claims that a relatively large portion of national rules were adopted only after the start of deceleration of the debt-to-GDP ratios. Accordingly, national rules were hardly the sole triggering factors of maintaining fiscal discipline; rather, they served as the key elements of a comprehensive reform package of public budgeting. It can be safely argued, therefore, that countries decide to adopt fiscal rules because they want to explicitly signal their strong commitment to fiscal discipline. In other words, it is not fiscal rules per se what matter in delivering fiscal stability but a strong political commitment.
Resumo:
A production of low velocity and monoenergetic atomic beams would increase the resolution in spectroscopic studies and many other experiments in atomic physics. Laser Cooling uses the radiation pressure to decelerate and cool atoms. The effusing from a glow discharge metastable argon atomic beam is affected by a counterpropagating laser light tuned to the cycling transition in argon. The Zeeman shift caused by a spatially varying magnetic field compensates for the changing Doppler shift that takes the atoms out of resonance as they decelerated. Deceleration and velocity bunching of atoms to a final velocity that depends on the detuning of the laser relative to a frequency of the transition have been observed. Time-of-Flight (TOF) spectroscopy is used to examine the velocity distribution of the cooled atomic beam. These TOF studies of the laser cooled atomic beam demonstrate the utility of laser deceleration for atomic-beam "velocity selection".
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This study aims to contribute with evidence to reinforce or not the thesis of a possible deindustrialization of the Brazilian economy, with emphasis on period after 1995. The debate began in the late 80s, however, recently the industry deceleration gained strength in discussions academic. Between the main theses in this debate is the new-development that believes in precocious deindustrialization caused primarily by overvaluation exchange rate. However, part of heterodoxy believes the industry downturn is more related to the rate of investment than the exchange rate. Nevertheless, according to the orthodox thesis the loss of competitiveness due to the high cost of production may have caused the de-industrialization in Brazil. On the other hand, part of Orthodoxy does not believe that the country is deindustrializing it, but is occurring convergence of Brazilian industry the world average. Thus, in an attempt to shed light on this debate, this study intends to identify the reasons for the deceleration of the Brazilian industry, emphasizing aspects underexplored in the literature and define whether or not the country suffers a process of deindustrialization. When analyzing various indicators, especially the quantum level we find strong indications that the deceleration of the Brazilian industry can be characterized as a deindustrialization, though still insufficient to qualify as precocious, given the loss of share in physical production in total output and the share of primary goods in the export basket
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We consider the simplest relevant problem in the foaming of molten plastics, the growth of a single bubble in a sea of highly viscous Newtonian fluid, and without interference from other bubbles. This simplest problem has defied accurate solution from first principles. Despite plenty of research on foaming, classical approaches from first principles have neglected the temperature rise in the surrounding fluid, and we find that this oversimplification greatly accelerates bubble growth prediction. We use a transport phenomena approach to analyze the growth of a solitary bubble, expanding under its own pressure. We consider a bubble of ideal gas growing without the accelerating contribution from mass transfer into the bubble. We explore the roles of viscous forces, fluid inertia, and viscous dissipation. We find that bubble growth depends upon the nucleus radius and nucleus pressure. We begin with a detailed examination of the classical approaches (thermodynamics without viscous heating). Our failure to fit experimental data with these classical approaches, sets up the second part of our paper, a novel exploration of the essential decelerating role of viscous heating. We explore both isothermal and adiabatic bubble expansion, and also the decelerating role of surface tension. The adiabatic analysis accounts for the slight deceleration due to the cooling of the expanding gas, which depends on gas polyatomicity. We also explore the pressure profile, and the components of the extra stress tensor, in the fluid surrounding the growing bubble. These stresses can eventually be frozen into foamed plastics. We find that our new theory compares well with measured bubble behavior.
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El objeto de este artículo es estudiar la influencia del nivel educativo (capital cultural) en los procesos de precariedad-afluencia de la población española entre los años posteriores a la crisis de inicio de la década de 1990 y los años más duros de la crisis de 2007. A partir de los datos de las encuestas PHOGUE y ECV del Instituto Nacional de Estadística (INE) se han construido cuatro indicadores para medir la precariedad laboral, de ingresos, de salud y de vivienda y su distribución según distintas variables demográficas. Se pretende contrastar la hipótesis de que más educación significa más protección frente a la precariedad, estudiando diferentes condiciones de las condiciones de vida y existencia en momentos tanto de crecimiento como de crisis económica. Mediante un análisis multivariable se intenta determinar el nivel de impacto del capital cultural, alcance, evolución y, sobre todo, si sus efectos positivos o negativos están en proceso de expansión o desaceleración. El resultado tiene una doble aportación: de un lado, metodológica, consistente en la construcción de los indicadores; de otro lado, los resultados, con los que se puede reevaluar algunas generalizaciones sobre la pérdida de importancia del rol de la educación en las sociedades contemporáneas.
Resumo:
We analyze how a set of 22 European countries was affected by increased Chinese export competition between 1995 and 2008. Employing product-group level data, we observe a reduction in the export volumes of European countries due to increased Chinese export competition. This deceleration in the export sector induces changes within the manufacturing industries, especially a decline in employment. When using more aggregated, regional-level data, our analysis shows that the industry sector as a whole declines, resulting in an increased unemployment rate. The importance of Chinese export competition for Europe is attributable to its high export intensity.
Resumo:
Rabindranath Tagore’s ideas can still inspire education in the East as well as in the West today. In this paper, I survey Tagore’s philosophical anthropology and argue that there is more coherence to his philosophy and pedagogy than is usually seen. For Tagore, the highest goal is to make the world one’s own, as well as to enlarge one’s self to encompass the world. The educational practices through which this ideal can be reached can be classified as “creative action,” “love,” and “freedom.” On the basis of such an ideal, realms such as the arts, nature, and movement no longer remain expendable additions to the kind of knowledge-driven education that aims primarily at making everyone economically productive.One of the problems with such a pedagogical strategy is that it treats human beings as means and not as ends. Tagore’s educational approach (his “method of nature”) refrains from turning children into adults as soon as possible and accepts the deceleration of learning and the simplification of living asmost forward-leading approach to a successful and comprehensive education.
Resumo:
Electric vehicle (EV) batteries tend to have accelerated degradation due to high peak power and harsh charging/discharging cycles during acceleration and deceleration periods, particularly in urban driving conditions. An oversized energy storage system (ESS) can meet the high power demands; however, it suffers from increased size, volume and cost. In order to reduce the overall ESS size and extend battery cycle life, a battery-ultracapacitor (UC) hybrid energy storage system (HESS) has been considered as an alternative solution. In this work, we investigate the optimized configuration, design, and energy management of a battery-UC HESS. One of the major challenges in a HESS is to design an energy management controller for real-time implementation that can yield good power split performance. We present the methodologies and solutions to this problem in a battery-UC HESS with a DC-DC converter interfacing with the UC and the battery. In particular, a multi-objective optimization problem is formulated to optimize the power split in order to prolong the battery lifetime and to reduce the HESS power losses. This optimization problem is numerically solved for standard drive cycle datasets using Dynamic Programming (DP). Trained using the DP optimal results, an effective real-time implementation of the optimal power split is realized based on Neural Network (NN). This proposed online energy management controller is applied to a midsize EV model with a 360V/34kWh battery pack and a 270V/203Wh UC pack. The proposed online energy management controller effectively splits the load demand with high power efficiency and also effectively reduces the battery peak current. More importantly, a 38V-385Wh battery and a 16V-2.06Wh UC HESS hardware prototype and a real-time experiment platform has been developed. The real-time experiment results have successfully validated the real-time implementation feasibility and effectiveness of the real-time controller design for the battery-UC HESS. A battery State-of-Health (SoH) estimation model is developed as a performance metric to evaluate the battery cycle life extension effect. It is estimated that the proposed online energy management controller can extend the battery cycle life by over 60%.
Resumo:
Ce mémoire explore les productions et les articulations des appartenances au mouvement Slow Fashion sur Twitter. En réaction au modèle actuel prédominant du Fast Fashion, basé sur une surproduction et une surconsommation des vêtements, le Slow Fashion sensibilise les différents acteurs du secteur de la mode à avoir une vision plus consciente des impacts de leurs pratiques sur les travailleurs, les communautés et les écosystèmes (Fletcher, 2007) et propose une décélération des cycles de production et de consommation des vêtements. L’enjeu de cette recherche est de montrer que le Slow Fashion se dessine notamment à travers les relations entres les différents acteurs sur Twitter et que l'ensemble de ces interactions prend la forme d'un rhizome, c’est-à-dire d’un système dans lequel les éléments qui le composent ne suivent aucune arborescence, aucune hiérarchie et n’émanent pas d’un seul point d’origine. (Deleuze & Guattari, 1976) Sur Twitter, les appartenances au Slow Fashion font surface, se connectent les unes aux autres par des liens de nature différente. Consommateurs, designers, entreprises, journalistes, etc., ces parties prenantes construisent collectivement le Slow Fashion comme mouvement alternatif à la mode mainstream actuelle. Mon cadre théorique s’est construit grâce à une analyse de la littérature des concepts de mode, d’identité et d’appartenance afin de mieux appréhender le contexte dans lequel le mouvement a émergé. Puis, j’ai également réalisé une étude exploratoire netnographique sur Twitter au cours de laquelle j’ai observé, tout en y participant, les interactions sur la plateforme abordant le Slow Fashion et/ou la mode éthique. Publiée sur ce blogue (http://belongingtoslowfashion.blogspot.ca), cette « creative presentation of research » (Chapman & Sawchuk, 2012) ne constitue pas une histoire présentant les prétendues origines de ce mouvement mais plutôt une photographie partielle à un certain moment du Slow Fashion. Construite tel un rhizome, elle n’a ni début, ni fin, ni hiérarchie. J’invite alors les lectrices/lecteurs à choisir n’importe quelle entrée et à délaisser toute logique linéaire et déductive. Cette exploration sera guidée par des liens hypertextes ou des annotations qui tisseront des connexions avec d’autres parties ou feront émerger d’autres questionnements. Il s’agit d’offrir une introduction aux enjeux que pose le Slow Fashion, d’ouvrir la voie à d’autres recherches et d’autres réflexions, ou encore de sensibiliser sur ce sujet.
Resumo:
The high velocity of free atoms associated with the thermal motion, together with the velocity distribution of atoms has imposed the ultimate limitation on the precision of ultrahigh resolution spectroscopy. A sample consisting of low velocity atoms would provide a substantial improvement in spectroscopy resolution. To overcome the problem of thermal motion, atomic physicists have pursued two goals; first, the reduction of the thermal motion (cooling); and second, the confinement of the atoms by means of electromagnetic fields (trapping). Cooling carried sufficiently far, eliminates the motional problems, whereas trapping allows for long observation times. In this work the laser cooling and trapping of an argon atomic beam will be discussed. The experiments involve a time-of-flight spectroscopy on metastable argon atoms. Laser deceleration or cooling of atoms is achieved by counter propagating a photon against an atomic beam of metastable atoms. The solution to the Doppler shift problem is achieved using spatially varying magnetic field along the beam path to Zeeman shift the atomic resonance frequency so as to keep the atoms in resonance with a fixed frequency cooling laser. For trapping experiments a Magnetooptical trap (MOT) will be used. The MOT is formed by three pairs of counter-propagating laser beams with mutual opposite circular polarization and a frequency tuned slightly below the center of the atomic resonance and superimposed on a magnetic quadrupole field.
Resumo:
Ce mémoire explore les productions et les articulations des appartenances au mouvement Slow Fashion sur Twitter. En réaction au modèle actuel prédominant du Fast Fashion, basé sur une surproduction et une surconsommation des vêtements, le Slow Fashion sensibilise les différents acteurs du secteur de la mode à avoir une vision plus consciente des impacts de leurs pratiques sur les travailleurs, les communautés et les écosystèmes (Fletcher, 2007) et propose une décélération des cycles de production et de consommation des vêtements. L’enjeu de cette recherche est de montrer que le Slow Fashion se dessine notamment à travers les relations entres les différents acteurs sur Twitter et que l'ensemble de ces interactions prend la forme d'un rhizome, c’est-à-dire d’un système dans lequel les éléments qui le composent ne suivent aucune arborescence, aucune hiérarchie et n’émanent pas d’un seul point d’origine. (Deleuze & Guattari, 1976) Sur Twitter, les appartenances au Slow Fashion font surface, se connectent les unes aux autres par des liens de nature différente. Consommateurs, designers, entreprises, journalistes, etc., ces parties prenantes construisent collectivement le Slow Fashion comme mouvement alternatif à la mode mainstream actuelle. Mon cadre théorique s’est construit grâce à une analyse de la littérature des concepts de mode, d’identité et d’appartenance afin de mieux appréhender le contexte dans lequel le mouvement a émergé. Puis, j’ai également réalisé une étude exploratoire netnographique sur Twitter au cours de laquelle j’ai observé, tout en y participant, les interactions sur la plateforme abordant le Slow Fashion et/ou la mode éthique. Publiée sur ce blogue (http://belongingtoslowfashion.blogspot.ca), cette « creative presentation of research » (Chapman & Sawchuk, 2012) ne constitue pas une histoire présentant les prétendues origines de ce mouvement mais plutôt une photographie partielle à un certain moment du Slow Fashion. Construite tel un rhizome, elle n’a ni début, ni fin, ni hiérarchie. J’invite alors les lectrices/lecteurs à choisir n’importe quelle entrée et à délaisser toute logique linéaire et déductive. Cette exploration sera guidée par des liens hypertextes ou des annotations qui tisseront des connexions avec d’autres parties ou feront émerger d’autres questionnements. Il s’agit d’offrir une introduction aux enjeux que pose le Slow Fashion, d’ouvrir la voie à d’autres recherches et d’autres réflexions, ou encore de sensibiliser sur ce sujet.
Resumo:
One of the most popular sports globally, soccer has seen a rise in the demands of the game over recent years. An increase in intensity and playing demands, coupled with growing social and economic pressures on soccer players means that optimal preparation is of paramount importance. Recent research has found the modern game, depending on positional role, to consist of approximately 60% more sprint distance in the English Premier League, which was also found to be the case for frequency and success of discrete technical actions (Bush et al., 2015). As a result, the focus on soccer training and player preparedness is becoming more prevalent in scientific research. By designing the appropriate training load, and thus periodization strategies, the aim is to achieve peak fitness in the most efficient way, whilst minimising the risk of injury and illness. Traditionally, training intensity has been based on heart rate responses, however, the emergence of tracking microtechnology such as global positioning system (GPS) and inertial sensors are now able to further quantify biomechanical load as well as physiological stress. Detailed pictures of internal and external loading indices such as these then combine to produce a more holistic view of training load experience by the player during typical drills and phases of training in soccer. The premise of this research is to gain greater understanding of the physical demands of common training methodologies in elite soccer to support optimal match performance. The coaching process may then benefit from being able to prescribe the most effective training to support these. The first experimental chapter in this thesis began by quantify gross training loads of the pre-season and in-season phases in soccer. A broader picture of the training loads inherent in these distinct phases brought more detail as to the type and extent of external loading experienced by soccer players at these times, and how the inclusion of match play influences weekly training rhythms. Training volume (total distance) was found to be high at the start compared to the end of pre-season (37 kilometres and 28 kilometres), where high cardiovascular loads were attained as part of the conditioning focus. This progressed transiently, however, to involve higher-speed, acceleration and change-of-direction stimuli at the end of pre-season compared to the start and to that in-season (1.18 kilometres, 0.70 kilometres and 0.42 kilometres high-intensity running; with 37, 25 and 23 accelerations >3m/s2 respectively) . The decrease in volume and increase in maximal anaerobic activity was evident in the training focus as friendly matches were introduced before the competitive season. The influence of match-play as being a large physical dose in the training week may then determine the change in weekly periodisation and how resulting training loads applied and tapered, if necessary. The focus of research was then directed more specifically to the most common mode of training in soccer, that also featured regularly in the pre-season period in the present study, small-sided games (SSG). The subsequent studies examined numerous manipulations of this specific form of soccer conditioning, such as player numbers as well as absolute and relative playing space available. In contrast to some previous literature, changing the number of players did not seem to influence training responses significantly, although playing format in the possession style brought about larger effects for heart rate (89.9%HRmax) and average velocity (7.6km/h-1). However, the following studies (Chapters 5, 6 and 7) revealed a greater influence of relative playing space available to players in SSG. The larger area at their disposal brought about greater aerobic responses (~90%HRmax), by allowing higher average and peak velocities (>25km/h-1), as well as greater distance acceleration behaviour at greater thresholds (>2.8m/s2). Furthermore, the data points towards space as being a large determinant in strategy of the player in small-sided games (SSG), subsequently shaping their movement behaviour and resulting physical responses. For example, higher average velocities in a possession format (8km/h-1) reflects higher work rate and heart rate load but makes achieving significant neuromuscular accelerations at a high level difficult given higher starting velocities prior to the most intense accelerations (4.2km/h-1). By altering space available and even through intentional numerical imbalances in team numbers, it may be easier for coaches to achieve the desired stimulus for the session or individual player, whether that is for aerobic and neuromuscular conditioning. Large effects were found for heart rate being higher in the underloaded team (85-90%HRmax) compared to the team with more players (80-85%HRmax) as well as for RPE (5AU versus 7AU). This was also apparent for meterage and therefore average velocity. It would also seem neuromuscular load through high acceleration and deceleration efforts were more pronounced with less numbers (given the need to press and close down opponents, and in a larger area relative to the number of players on the underloaded team. The peak accelerations and deceleration achieved was also higher when playing with less players (3-6.2m/s2 and 3-6.1m/s2) Having detailed ways in which to reach desired physical loading responses in common small training formats, Chapter 8 compared SSG to larger 9v9 formats with full-size 11v11 friendly matches. This enabled absolute and relative comparisons to be made and to understand the extent to which smaller training formats are able to replicate the required movements to be successful in competition. In relative terms, it was revealed that relative acceleration distance and Player Load were higher in smaller 4v4 games than match-play (1.1m.min-1 and 0.3m.min-1 >3m/s2; 16.9AU versus 12AU). Although the smallest format did not replicate the high-velocity demands of matches, the results confirmed their efficacy in providing significant neuromuscular load during the training week, which may then be supplemented by high-intensity interval running in order to gain exposure to more maximal speed work. In summary, the data presented provide valuable information from GPS and inertial sensor microtechnology which may then be used to understand training better to manipulate types of load according to physical conditioning objectives. For example, a library of resources to direct planning of drills of varying cardiovascular, neuromuscular and perceptual load can be created to give more confidence in session outcomes. Combining external and internal load data of common soccer training drills, and their application across different phases and training objectives may give coaches a powerful tool to plan and periodize training.
Resumo:
Background:In vitrocell suspension cultivation systems have been largely reported assafe and standardized methods for production of secondary metabolites with medicinaland agricultural interest.Capsicum annuumis one of the most widely grown vegetablein the world and its biological activities have been demonstrated against insects, fungi,bacteria and other groups of organisms. The determination of procedures for thededifferentiation of cells into callus cells and the subsequent study of the callus growthpattern are necessary for the establishment of cellsuspensions and also to subsidizestudies regarding the bioactivity of its secondarymetabolites. To date, no study hasdescribed the development of protocols for callus induction inC. annuumL. cv. Etna. Objective:The objective of this study was to establish a protocol for dedifferentiationof leaf cells of the cultivarC. annuumcv. Etna and to determine the growth pattern ofthe calluses with a focus on the deceleration phase, when the callus cells must besubcultured into a liquid medium in order to establish cell suspension cultivationsaiming at the production of secondary metabolites.Results:The treatment that resultedin the highest %CI, ACCC and callus weight was thecombination of 4.52 μ M 2,4-D +0.44 μ M BA. The calluses produced were friable andwhitish and their growth patternfollowed a sigmoid shape. The deceleration phase started on the 23rdday of cultivation.Conclusion:Callus induction in leaf explants ofC. annuumcv. Etnacan be achieved inMS medium supplemented with 4.52 μ M 2,4-D + 0.44 μ MBA, which results in highcellular proliferation; in order to start a cell suspension culture, callus cells on the 23rdday of culture should be used.
Resumo:
Since the first subdivisions of the brain into macro regions, it has always been thought a priori that, given the heterogeneity of neurons, different areas host specific functions and process unique information in order to generate a behaviour. Moreover, the various sensory inputs coming from different sources (eye, skin, proprioception) flow from one macro area to another, being constantly computed and updated. Therefore, especially for non-contiguous cortical areas, it is not expected to find the same information. From this point of view, it would be inconceivable that the motor and the parietal cortices, diversified by the information encoded and by the anatomical position in the brain, could show very similar neural dynamics. With the present thesis, by analyzing the population activity of parietal areas V6A and PEc with machine learning methods, we argue that a simplified view of the brain organization do not reflect the actual neural processes. We reliably detected a number of neural states that were tightly linked to distinct periods of the task sequence, i.e. the planning and execution of movement and the holding of target as already observed in motor cortices. The states before and after the movement could be further segmented into two states related to different stages of movement planning and arm posture processing. Rather unexpectedly, we found that activity during the movement could be parsed into two states of equal duration temporally linked to the acceleration and deceleration phases of the arm. Our findings suggest that, at least during arm reaching in 3D space, the posterior parietal cortex (PPC) shows low-level population neural dynamics remarkably similar to those found in the motor cortices. In addition, the present findings suggest that computational processes in PPC could be better understood if studied using a dynamical system approach rather than studying a mosaic of single units.