278 research outputs found
A hybrid MPPT algorithm based on DE-IC for photovoltaic systems under partial shading conditions
This paper presents a hybrid maximum power point tracking (MPPT), which combines a metaheuristic algorithm and a traditional MPPT method applied in a photovoltaic system operating under partial shading conditions. The MPPTs based on traditional methods are not able to track the global maxi-mum power point (GMPP) when partial shadings occur. Thus, MPPT algorithms based on metaheuristic algorithms, which are used for global optimization, have presented efficiency to extract the maximum power from photovoltaic arrays. However, these methods are random, resulting in large power oscillations in transients of small variations in solar irradiance. Therefore, this paper proposes the metaheuristic algorithm called Differential Evolution (DE) to seek and track the GMPP. After the DE convergence, the MPPT algorithm is switched to Incremental Conductance (IC) in order to refine the tracking. The effectiveness of the algorithm is proved through simulation results. Furthermore, comparative analyses are provided for each algorithm (DE and IC) to evaluate their performances in the PV system
Corn yield response to residual effect of fertilization with sewage sludge compost and rock phosphate
Objetivou-se, com este trabalho, avaliar o efeito residual da adubação com composto de lodo de esgoto e fosfato natural de Gafsa sobre os teores de nutrientes no solo, na planta e na produtividade do milho. O trabalho foi realizado em Cambissolo Håplico. Os tratamentos, em esquema fatorial 2 x 4, corresponderam a 2 doses de fosfato de Gafsa (0 e 90 kg ha-1 de P2O5) e 4 doses de composto de lodo de esgoto (0; 25; 50 e 75 t ha-1, em base seca). O delineamento experimental utilizado foi em blocos casualizados, com 3 repetiçþes. Em geral, a produtividade e os teores de nutrientes no solo e na planta no segundo cultivo sucessivo de milho não foram influenciados pela adubação com fosfato natural reativo. Entretanto, a produtividade de milho e os teores de nutrientes no solo e nas folhas de milho aumentaram com a dose de composto de lodo de esgoto ao solo, sendo a dose de 75 Mg ha-1, a de maior efeito residual. A produtividade do milho Ê menor no segundo cultivo sucessivo em razão do empobrecimento do solo em fósforo e potåssio, recomendando-se novas adubaçþes com lodo de esgoto, a cada cultivo realizado
Regulation of glucose and fatty acid metabolism in skeletal muscle during contraction
O ciclo glicose-ĂĄcido graxo explica a preferĂŞncia do tecido muscular pelos ĂĄcidos graxos durante atividade moderada de longa duração. Em contraste, durante o exercĂcio de alta intensidade, hĂĄ aumento na disponibilidade e na taxa de oxidação de glicose. A produção de espĂŠcies reativas de oxigĂŞnio (EROs) durante a atividade muscular sugere que o balanço redox intracelular ĂŠ importante na regulação do metabolismo de lipĂdios/carboidratos. As EROs diminuem a atividade do ciclo de Krebs e aumentam a atividade da proteĂna desacopladora mitocondrial. O efeito oposto ĂŠ esperado durante a atividade moderada. Assim, as questĂľes levantadas nesta revisĂŁo sĂŁo: Por que o mĂşsculo esquelĂŠtico utiliza preferencialmente os lipĂdios no estado basal e de atividade moderada? Por que o ciclo glicose-ĂĄcido graxo falha em exercer seus efeitos durante o exercĂcio intenso? Como o mĂşsculo esquelĂŠtico regula o metabolismo de lipĂdios e carboidratos em regime envolvendo o ciclo contração-relaxamento555303313CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQCOORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL DE NĂVEL SUPERIOR - CAPESFUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESPsem informaçãoThe glucose-fatty acid cycle explains the preference for fatty acid during moderate and long duration physical exercise. In contrast, there is a high glucose availability and oxidation rate in response to intense physical exercise. The reactive oxygen species (ROS) production during physical exercise suggests that the redox balance is important to regulate of lipids/carbohydrate metabolism. ROS reduces the activity of the Krebs cycle, and increases the activity of mitochondrial uncoupling proteins. The opposite effects happen during moderate physical activity. Thus, some issues is highlighted in the present review: Why does skeletal muscle prefer lipids in the basal and during moderate physical activity? Why does glucose-fatty acid fail to carry out their effects during intense physical exercise? How skeletal muscles regulate the lipids and carbohydrate metabolism during the contraction-relaxation cycle
Regulation of glucose and fatty acid metabolism in skeletal muscle during contraction
O ciclo glicose-ĂĄcido graxo explica a preferĂŞncia do tecido muscular pelos ĂĄcidos graxos durante atividade moderada de longa duração. Em contraste, durante o exercĂcio de alta intensidade, hĂĄ aumento na disponibilidade e na taxa de oxidação de glicose. A produção de espĂŠcies reativas de oxigĂŞnio (EROs) durante a atividade muscular sugere que o balanço redox intracelular ĂŠ importante na regulação do metabolismo de lipĂdios/carboidratos. As EROs diminuem a atividade do ciclo de Krebs e aumentam a atividade da proteĂna desacopladora mitocondrial. O efeito oposto ĂŠ esperado durante a atividade moderada. Assim, as questĂľes levantadas nesta revisĂŁo sĂŁo: Por que o mĂşsculo esquelĂŠtico utiliza preferencialmente os lipĂdios no estado basal e de atividade moderada? Por que o ciclo glicose-ĂĄcido graxo falha em exercer seus efeitos durante o exercĂcio intenso? Como o mĂşsculo esquelĂŠtico regula o metabolismo de lipĂdios e carboidratos em regime envolvendo o ciclo contração-relaxamento.The glucose-fatty acid cycle explains the preference for fatty acid during moderate and long duration physical exercise. In contrast, there is a high glucose availability and oxidation rate in response to intense physical exercise. The reactive oxygen species (ROS) production during physical exercise suggests that the redox balance is important to regulate of lipids/carbohydrate metabolism. ROS reduces the activity of the Krebs cycle, and increases the activity of mitochondrial uncoupling proteins. The opposite effects happen during moderate physical activity. Thus, some issues is highlighted in the present review: Why does skeletal muscle prefer lipids in the basal and during moderate physical activity? Why does glucose-fatty acid fail to carry out their effects during intense physical exercise? How skeletal muscles regulate the lipids and carbohydrate metabolism during the contraction-relaxation cycle
Black hole thermodynamical entropy
As early as 1902, Gibbs pointed out that systems whose partition function
diverges, e.g. gravitation, lie outside the validity of the Boltzmann-Gibbs
(BG) theory. Consistently, since the pioneering Bekenstein-Hawking results,
physically meaningful evidence (e.g., the holographic principle) has
accumulated that the BG entropy of a black hole is
proportional to its area ( being a characteristic linear length), and
not to its volume . Similarly it exists the \emph{area law}, so named
because, for a wide class of strongly quantum-entangled -dimensional
systems, is proportional to if , and to if
, instead of being proportional to (). These results
violate the extensivity of the thermodynamical entropy of a -dimensional
system. This thermodynamical inconsistency disappears if we realize that the
thermodynamical entropy of such nonstandard systems is \emph{not} to be
identified with the BG {\it additive} entropy but with appropriately
generalized {\it nonadditive} entropies. Indeed, the celebrated usefulness of
the BG entropy is founded on hypothesis such as relatively weak probabilistic
correlations (and their connections to ergodicity, which by no means can be
assumed as a general rule of nature). Here we introduce a generalized entropy
which, for the Schwarzschild black hole and the area law, can solve the
thermodynamic puzzle.Comment: 7 pages, 2 figures. Accepted for publication in EPJ
Violation of the fluctuation-dissipation theorem in glassy systems: basic notions and the numerical evidence
This review reports on the research done during the past years on violations
of the fluctuation-dissipation theorem (FDT) in glassy systems. It is focused
on the existence of a quasi-fluctuation-dissipation theorem (QFDT) in glassy
systems and the currently supporting knowledge gained from numerical simulation
studies. It covers a broad range of non-stationary aging and stationary driven
systems such as structural-glasses, spin-glasses, coarsening systems,
ferromagnetic models at criticality, trap models, models with entropy barriers,
kinetically constrained models, sheared systems and granular media. The review
is divided into four main parts: 1) An introductory section explaining basic
notions related to the existence of the FDT in equilibrium and its possible
extension to the glassy regime (QFDT), 2) A description of the basic analytical
tools and results derived in the framework of some exactly solvable models, 3)
A detailed report of the current evidence in favour of the QFDT and 4) A brief
digression on the experimental evidence in its favour. This review is intended
for inexpert readers who want to learn about the basic notions and concepts
related to the existence of the QFDT as well as for the more expert readers who
may be interested in more specific results.Comment: 120 pages, 37 figures. Topical review paper . Several typos and
misprints corrected, new references included and others updated. to be
published in J. Phys. A (Math. Gen.
Nutrition of Tithonia diversifolia and attributes of the soil fertilized with biofertilizer in irrigated system
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Performance and Operation of the CMS Electromagnetic Calorimeter
The operation and general performance of the CMS electromagnetic calorimeter
using cosmic-ray muons are described. These muons were recorded after the
closure of the CMS detector in late 2008. The calorimeter is made of lead
tungstate crystals and the overall status of the 75848 channels corresponding
to the barrel and endcap detectors is reported. The stability of crucial
operational parameters, such as high voltage, temperature and electronic noise,
is summarised and the performance of the light monitoring system is presented
Testing General Relativity with Present and Future Astrophysical Observations
One century after its formulation, Einstein's general relativity has maderemarkable predictions and turned out to be compatible with all experimentaltests. Most of these tests probe the theory in the weak-field regime, and thereare theoretical and experimental reasons to believe that general relativityshould be modified when gravitational fields are strong and spacetime curvatureis large. The best astrophysical laboratories to probe strong-field gravity areblack holes and neutron stars, whether isolated or in binary systems. We reviewthe motivations to consider extensions of general relativity. We present a(necessarily incomplete) catalog of modified theories of gravity for whichstrong-field predictions have been computed and contrasted to Einstein'stheory, and we summarize our current understanding of the structure anddynamics of compact objects in these theories. We discuss current bounds onmodified gravity from binary pulsar and cosmological observations, and wehighlight the potential of future gravitational wave measurements to inform uson the behavior of gravity in the strong-field regime
- âŚ