116 research outputs found
NAUTILUS-DTU10 MW Floating Offshore Wind Turbine at Gulf of Maine: Public numerical models of an actively ballasted semisubmersible
This study presents two numerical multiphysics models of the NAUTILUS-10 floating support structure mounting the DTU10 MW Reference Wind Turbine at Gulf of Maine site, and analyses its dynamics. With the site conditions and the FAST model of the onshore turbine as the starting point, the floating support structure: tower, floating substructure with its corresponding active ballast system and station keeping system, was designed by NAUTILUS. The numerical models were developed and the onshore DTU wind energy controller was tuned to avoid the resonance of the operating FOWT by TECNALIA, in the framework of H2020 LIFES50+ project. This concept and its subsystems are fully characterised throughout this paper and implemented in opensource code, FAST v8.16. Here, the mooring dynamics are solved using MoorDyn, and the hydrodynamic properties are computed using HydroDyn. Viscous effects, not captured by radiation-diffraction theory, are modelled using two different approaches: (1) through linear and quadratic additional hydrodynamic damping matrices and (2) by means of Morison elements. A set of simulations (such as, decay, wind only and broadband irregular waves tests) were carried out with system identification purposes and to analyse the differences between the two models presented. Then, a set of simulations in stochastic wind and waves were carried out to characterise the global response of the FOWT.European Union Horizon2020
programme under the agreement H2020-LCE-2014-1-640741, LIFES50+ projec
Hydrodynamic identification of NAUTILUS FOWT platform from small scale tests
A small-scale tank test campaign of the NAUTILUS offshore wind floating semisub-mersible platform was held at the Ifremer Deep Water Basin within the framework of the MaRINET 2 project. The support structure consists in four stabilized columns on a square pontoon supporting a generic 8-MW wind turbine. The tests were carried out at 1:36 Froude scale in parked conditions, and the mooring system was modelled as a set of aerial mooring springs providing a nonlinear stiffness. The hydrodynamic characterization of the floater from experimental data was tackled by using traditional techniques in naval architecture), as well as approaches derived from operational modal analysis in the frequency domain, such as the Sub Space Identification—Covariance (SSI-COV) method. The validity of this approach and its potential application to the identification of such kind of structures is discussed against the results of a more traditional technique based on the fitting of decay tests
A 800 kW wind-diesel test bench based on the MADE AE-52 variable speed wind turbine
A field work have been made about the practical installation of a wind-diesel autonomous power system. A remarkable innovation on the control of the latter wind-diesel system is the ability of taking advantage of the kinetic energy available from the wind turbine. With such an extra energy, a power quality improvement can be achieved in the presence of load commutations. Besides of that, a convenient power sharing out can be obtained, allowing a high renewable energy penetration and fuel savings. Several results show the behaviour of the whole system, apart of the power quality improvement. Index Terms—Renewable hybrid system, isolated power system, power quality, diesel generator, wind turbine
Treatments for alopecia areata: a network meta-analysis
Acknowledgement: “This Protocol of a Cochrane Review was published in the Cochrane Database of Systematic Reviews 2020, Issue 9. Cochrane Protocols and Reviews are regularly updated as new evidence emerges and in response to feedback, and the Cochrane Database of Systematic Reviews should be consulted for the most recent version of the Protocol.'Copyright © 2020 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. Objectives: This is a protocol for a Cochrane Review (intervention). The objectives are as follows:. To assess the comparative effectiveness and safety of interventions used in the management of alopecia areata (AA), including patchy alopecia (PA), alopecia totalis (AT) and alopecia universalis (AU). To establish rankings of the available treatments for AA, based on their effectiveness and safety (primary outcomes), through a network meta-analysis
First observations on courtship and nesting behavior of Kinosternon vogti (Testudines: Kinosternidae)
Kinosternon vogti is one of the most narrowly distributed kinosternid turtles in Mexico; it is apparently restricted to small streams and ponds in the urban area of Puerto Vallarta, Jalisco and Bahía de Banderas, Nayarit. There is little information on the biology of this recently described and endangered species, particularly regarding reproductive biology. We report reproductive behaviors on two mating pairs of K. vogti in captivity. Males exhibited combat for copulating with female. During courtship, the male blocks the female movements, the female bites male´s rostrum scute, the male displays titillation posture, and finally the male moves to position himself above the female. The reproductive season begins with courtship in August-September and ends with egg-laying in November-December. Six and two eggs per clutch (non-viable eggs; average size, n = 5: 28.83 ± 1.19 x 15.95 ± 0.55 mm). Minimal reproductive size of females and males were CL (carapace length) = 88.37 mm and CL = 78.7 mm, respectively.Asociación Herpetológica Argentin
Substructures in the Keplerian disc around the O-type (proto-)star G17.64+0.16
We present the highest angular resolution (̃20 × 15 mas-44 × 33 au) Atacama Large Millimeter/sub-millimeter Array (ALMA) observations that are currently possible of the proto-O-star G17.64+0.16 in Band 6. The Cycle 5 observations with baselines out to 16 km probe scales < 50 au and reveal the rotating disc around G17.64+0.16, a massive forming O-type star. The disc has a ring-like enhancement in the dust emission that is especially visible as arc structures to the north and south. The Keplerian kinematics are most prominently seen in the vibrationally excited water line, H2O 55, 0-64, 3 ν2 = 1 (Eu = 3461.9 K). The mass of the central source found by modelling the Keplerian rotation is consistent with 45 ± 10 M☉. The H30α (231.9 GHz) radio-recombination line and the SiO (5-4) molecular line were detected at up to the ̃10σ level. The estimated disc mass is 0.6 - 2.6 M☉ under the optically thin assumption. Analysis of the Toomre Q parameter in the optically thin regime indicates that the disc stability is highly dependent on temperature. The disc currently appears stable for temperatures > 150 K; this does not preclude that the substructures formed earlier through disc fragmentation. Data cubes of the source are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/627/L6
Peripheral and placental immune responses in sheep after experimental infection with "Toxoplasma gondii" at the three terms of gestation
P. 1-9Although it is known that gestation could infuence the clinical course of ovine toxoplasmosis, the precise efect of the term of gestation when sheep are infected are yet mostly unknown. The aim of this study was to evaluate the peripheral and placental immune responses developed in pregnant sheep after experimental infection with Toxoplasma gondiiat diferent times of gestation. Thirty‑six pregnant sheep were allocated in diferent groups, orally inocu‑lated with sporulated oocysts of T. gondiiat early, mid and late gestation and culled within 30 days post‑infection. The peripheral humoral and cytokine responses were evaluated, as well as the transcription of cytokines at the placenta.
Serological analysis revealed that, regardless the term of gestation when infected, specifc IgG against T. gondiiwere detected from day 8 post‑infection and there was an early peripheral release of IFN‑γ at the frst week post‑infection followed by a short peak of IL10 and TNF‑α at the second week post‑infection. There were no signifcant diferences in this response between infected groups. At the placenta, a similar increase in transcription of IFN‑γ, and TNF‑α was found at the three terms of gestation, while IL‑4 increased mainly at the frst and second terms and IL‑10 transcription was higher at the last term. While these fndings show that both Th1 and Th2 cytokines play a key role in the patho‑genesis of ovine toxoplasmosis and that placental and peripheral immune responses do not closely correlate, there seems to be no clear modulation of these responses along the gestation.S
Interstellar MHD Turbulence and Star Formation
This chapter reviews the nature of turbulence in the Galactic interstellar
medium (ISM) and its connections to the star formation (SF) process. The ISM is
turbulent, magnetized, self-gravitating, and is subject to heating and cooling
processes that control its thermodynamic behavior. The turbulence in the warm
and hot ionized components of the ISM appears to be trans- or subsonic, and
thus to behave nearly incompressibly. However, the neutral warm and cold
components are highly compressible, as a consequence of both thermal
instability in the atomic gas and of moderately-to-strongly supersonic motions
in the roughly isothermal cold atomic and molecular components. Within this
context, we discuss: i) the production and statistical distribution of
turbulent density fluctuations in both isothermal and polytropic media; ii) the
nature of the clumps produced by thermal instability, noting that, contrary to
classical ideas, they in general accrete mass from their environment; iii) the
density-magnetic field correlation (or lack thereof) in turbulent density
fluctuations, as a consequence of the superposition of the different wave modes
in the turbulent flow; iv) the evolution of the mass-to-magnetic flux ratio
(MFR) in density fluctuations as they are built up by dynamic compressions; v)
the formation of cold, dense clouds aided by thermal instability; vi) the
expectation that star-forming molecular clouds are likely to be undergoing
global gravitational contraction, rather than being near equilibrium, and vii)
the regulation of the star formation rate (SFR) in such gravitationally
contracting clouds by stellar feedback which, rather than keeping the clouds
from collapsing, evaporates and diperses them while they collapse.Comment: 43 pages. Invited chapter for the book "Magnetic Fields in Diffuse
Media", edited by Elisabete de Gouveia dal Pino and Alex Lazarian. Revised as
per referee's recommendation
Plasticity in dendroclimatic response across the distribution range of Aleppo pine (Pinus halepensis)
We investigated the variability of the climate-growth relationship of Aleppo pine across its distribution range in the Mediterranean Basin. We constructed a network of tree-ring index chronologies from 63 sites across the region. Correlation function analysis identified the relationships of tree-ring index to climate factors for each site. We also estimated the dominant climatic gradients of the region using principal component analysis of monthly, seasonal, and annual mean temperature and total precipitation from 1,068 climatic gridpoints. Variation in ring width index was primarily related to precipitation and secondarily to temperature. However, we found that the dendroclimatic relationship depended on the position of the site along the climatic gradient. In the southern part of the distribution range, where temperature was generally higher and precipitation lower than the regional average, reduced growth was also associated with warm and dry conditions. In the northern part, where the average temperature was lower and the precipitation more abundant than the regional average, reduced growth was associated with cool conditions. Thus, our study highlights the substantial plasticity of Aleppo pine in response to different climatic conditions. These results do not resolve the source of response variability as being due to either genetic variation in provenance, to phenotypic plasticity, or a combination of factors. However, as current growth responses to inter-annual climate variability vary spatially across existing climate gradients, future climate-growth relationships will also likely be determined by differential adaptation and/or acclimation responses to spatial climatic variation. The contribution of local adaptation and/or phenotypic plasticity across populations to the persistence of species under global warming could be decisive for prediction of climate change impacts across populations. In this sense, a more complex forest dynamics modeling approach that includes the contribution of genetic variation and phenotypic plasticity can improve the reliability of the ecological inferences derived from the climate-growth relationships.This work was partially supported by Spanish Ministry of Education and Science co-funded by FEDER program (CGL2012-31668), the European Union and the National Ministry of Education and Religion of Greece (EPEAEK- Environment – Archimedes), the Slovenian Research Agency (program P4-0015), and the USDA Forest Service. The cooperation among international partners was supported by the COST Action FP1106, STREeSS
Population genomics applications for conservation: the case of the tropical dry forest dweller Peromyscus melanophrys
Recent advances in genomic sequencing have opened new horizons in the study of population genetics and evolution in non-model organisms. However, very few population genomic studies have been performed on wild mammals to understand how the landscape affects the genetic structure of populations, useful information for the conservation of biodiversity. Here, we applied a genomic approach to evaluate the relationship between habitat features and genetic patterns at spatial and temporal scales in an endangered ecosystem, the Tropical Dry Forest (TDF). We studied populations of the Plateau deer mouse Peromyscus melanophrys to analyse its genomic diversity and structure in a TDF protected area in the Huautla Mountain Range (HMR), Mexico based on 8,209 SNPs obtained through Genotyping-by-Sequencing. At a spatial scale, we found a significant signature of isolation-by-distance, few significant differences in genetic diversity indices among study sites, and no significant differences between habitats with different levels of human perturbation. At a temporal scale, while genetic diversity levels fluctuated significantly over time, neither seasonality nor disturbance levels had a significant effect. Also, outlier analysis revealed loci potentially under selection. Our results suggest that the population genetics of P. melanophrys may be little impacted by anthropogenic disturbances, or by natural spatial and temporal habitat heterogeneity in our study area. The genome-wide approach adopted here provides data of value for conservation planning, and a baseline to be used as a reference for future studies on the effects of habitat fragmentation and seasonality in the HMR and in TDF
- …