Wind-blown sand on beaches: an evaluation of models

Science.gov (United States)

Sherman, Douglas J.; Jackson, Derek W. T.; Namikas, Steven L.; Wang, Jinkang

1998-03-01

Five models for predicting rates of aeolian sand transport were evaluated using empirical data obtained from field experiments conducted in April, 1994 at a beach on Inch Spit, Co. Kerry, Republic of Ireland. Measurements were made of vertical wind profiles (to derive shear velocity estimates), beach slope, and rates of sand transport. Sediment samples were taken to assess characteristics of grain size and surface moisture content. Estimates of threshold shear velocity were derived using grain size data. After parsing the field data on the basis of the quality of shear velocity estimation and the occurrence of blowing sand, 51 data sets describing rates of sand transport and environmental conditions were retained. Mean grain diameter was 0.17 mm. Surface slopes ranged from 0.02 on the foreshore to about 0.11 near the dune toe. Mean shear velocities ranged from 0.23 m s -1 (just above the observed transport threshold) to 0.65 m s -1. Rates of transport ranged from 0.02 kg m -1 h -1 to more than 80 kg m -1 h -1. These data were used as input to the models of Bagnold [Bagnold, R.A., 1936. The Movement of Desert Sand. Proc. R. Soc. London, A157, 594-620], Kawamura [Kawamura, R., 1951. Study of Sand Movement by Wind. Translated (1965) as University of California Hydraulics Engineering Laboratory Report HEL 2-8, Berkeley], Zingg [Zingg, A.W., 1953. Wind tunnel studies of the movement of sedimentary material. Proc. 5th Hydraulics Conf. Bull. 34, Iowa City, Inst. of Hydraulics, pp. 111-135], Kadib [Kadib, A.A., 1965. A function for sand movement by wind. University of California Hydraulics Engineering Laboratory Report HEL 2-8, Berkeley], and Lettau and Lettau [Lettau, K. and Lettau, H., 1977. Experimental and Micrometeorological Field Studies of Dune Migration. In: K. Lettau and H. Lettau (Eds.), Exploring the World's Driest Climate. University of Wisconsin-Madison, IES Report 101, pp. 110-147]. Correction factors to adjust predictions of the rate of transport to account

Distribution and provenance of wind-blown SE Pacific surface sediments

NARCIS (Netherlands)

Saukel, C.; Lamy, F.; Stuut, J.B.W.; Tiedemann, R.; Vogt, C.

2011-01-01

The reconstruction of low-latitude ocean-atmosphere interactions is one of the major issues of (paleo-) environmental studies. The trade winds, extending over 20 degrees to 30 degrees of latitude in both hemispheres, between the subtropical highs and the intertropical convergence zone, are major

Comparison of mass and energy balances for air blown and thermally ballasted fluidized bed gasifiers

International Nuclear Information System (INIS)

Lysenko, Steve; Sadaka, Samy; Brown, Robert C.

2012-01-01

The objective of this study was to compare the mass and energy balances for a conventional air blown fluidized bed gasifier and a ballasted fluidized bed gasifier developed at Iowa State University. The ballasted gasifier is an indirectly heated gasifier that uses a single reactor for both combustion and pyrolysis. Heat accumulated in high-temperature phase change material during the combustion phase is released during the pyrolysis phase to generate producer gas. Gas composition, tar and char contents, cold gas efficiency, carbon conversion, and hydrogen yield per unit biomass input were determined as part of these evaluation. During the pyrolysis phase of ballasted gasification, higher volumetric concentrations of hydrogen and methane were obtained than during air blown gasification. Hydrogen yield for ballasted gasification was 14 g kg −1 of biomass, which was about 20% higher than that obtained during air blown gasification. The higher heating value of the producer gas also reached higher levels during the ballasted pyrolysis phase than that of air blown gasification. Heating value for air blown gasification was 5.2 MJ m −3 whereas the heating value for the ballasted pyrolysis phase averaged 5.5 MJ m −3 , reaching a maximum of 8.0 MJ m −3 . The ballasted gasifier was expected to yield producer gas with average heating value as high as 15 MJ m −3 but excessive use of nitrogen to purge and cool the fuel feeder system greatly diluted the producer gas. Relatively simple redesign of the feeder system would greatly reduce the use of purge gas and may increase the heating values to about 17.5 MJ m −3 . Higher char production per kilogram of biomass was associated with the ballasted system, producing 140 g kg −1 of biomass compared to only 53 g kg −1 of biomass during air blown gasification. On the other hand, tar concentrations in the producer gas were 6.0 g m −3 for ballasted gasification compared to 11.7 g m −3 for air blown gasification. On

Contribution of large scale coherence to wind turbine power: A large eddy simulation study in periodic wind farms

Science.gov (United States)

Chatterjee, Tanmoy; Peet, Yulia T.

2018-03-01

Length scales of eddies involved in the power generation of infinite wind farms are studied by analyzing the spectra of the turbulent flux of mean kinetic energy (MKE) from large eddy simulations (LES). Large-scale structures with an order of magnitude bigger than the turbine rotor diameter (D ) are shown to have substantial contribution to wind power. Varying dynamics in the intermediate scales (D -10 D ) are also observed from a parametric study involving interturbine distances and hub height of the turbines. Further insight about the eddies responsible for the power generation have been provided from the scaling analysis of two-dimensional premultiplied spectra of MKE flux. The LES code is developed in a high Reynolds number near-wall modeling framework, using an open-source spectral element code Nek5000, and the wind turbines have been modelled using a state-of-the-art actuator line model. The LES of infinite wind farms have been validated against the statistical results from the previous literature. The study is expected to improve our understanding of the complex multiscale dynamics in the domain of large wind farms and identify the length scales that contribute to the power. This information can be useful for design of wind farm layout and turbine placement that take advantage of the large-scale structures contributing to wind turbine power.

HashDist: Reproducible, Relocatable, Customizable, Cross-Platform Software Stacks for Open Hydrological Science

Science.gov (United States)

Ahmadia, A. J.; Kees, C. E.

2014-12-01

Developing scientific software is a continuous balance between not reinventing the wheel and getting fragile codes to interoperate with one another. Binary software distributions such as Anaconda provide a robust starting point for many scientific software packages, but this solution alone is insufficient for many scientific software developers. HashDist provides a critical component of the development workflow, enabling highly customizable, source-driven, and reproducible builds for scientific software stacks, available from both the IPython Notebook and the command line. To address these issues, the Coastal and Hydraulics Laboratory at the US Army Engineer Research and Development Center has funded the development of HashDist in collaboration with Simula Research Laboratories and the University of Texas at Austin. HashDist is motivated by a functional approach to package build management, and features intelligent caching of sources and builds, parametrized build specifications, and the ability to interoperate with system compilers and packages. HashDist enables the easy specification of "software stacks", which allow both the novice user to install a default environment and the advanced user to configure every aspect of their build in a modular fashion. As an advanced feature, HashDist builds can be made relocatable, allowing the easy redistribution of binaries on all three major operating systems as well as cloud, and supercomputing platforms. As a final benefit, all HashDist builds are reproducible, with a build hash specifying exactly how each component of the software stack was installed. This talk discusses the role of HashDist in the hydrological sciences, including its use by the Coastal and Hydraulics Laboratory in the development and deployment of the Proteus Toolkit as well as the Rapid Operational Access and Maneuver Support project. We demonstrate HashDist in action, and show how it can effectively support development, deployment, teaching, and

DIST: a computer code system for calculation of distribution ratios of solutes in the purex system

Energy Technology Data Exchange (ETDEWEB)

Tachimori, Shoichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1996-05-01

Purex is a solvent extraction process for reprocessing the spent nuclear fuel using tri n-butylphosphate (TBP). A computer code system DIST has been developed to calculate distribution ratios for the major solutes in the Purex process. The DIST system is composed of database storing experimental distribution data of U(IV), U(VI), Pu(III), Pu(IV), Pu(VI), Np(IV), Np(VI), HNO{sub 3} and HNO{sub 2}: DISTEX and of Zr(IV), Tc(VII): DISTEXFP and calculation programs to calculate distribution ratios of U(IV), U(VI), Pu(III), Pu(IV), Pu(VI), Np(IV), Np(VI), HNO{sub 3} and HNO{sub 2}(DIST1), and Zr(IV), Tc(VII)(DITS2). The DIST1 and DIST2 determine, by the best-fit procedures, the most appropriate values of many parameters put on empirical equations by using the DISTEX data which fulfill the assigned conditions and are applied to calculate distribution ratios of the respective solutes. Approximately 5,000 data were stored in the DISTEX and DISTEXFP. In the present report, the following items are described, 1) specific features of DIST1 and DIST2 codes and the examples of calculation 2) explanation of databases, DISTEX, DISTEXFP and a program DISTIN, which manages the data in the DISTEX and DISTEXFP by functions as input, search, correction and delete. and at the annex, 3) programs of DIST1, DIST2, and figure-drawing programs DIST1G and DIST2G 4) user manual for DISTIN. 5) source programs of DIST1 and DIST2. 6) the experimental data stored in the DISTEX and DISTEXFP. (author). 122 refs.

Contribution To The Sedimentology Of The Bahariya Formation Of Gebel El-Dist, Bahariya Oasis, Western Desert, Egypt

OpenAIRE

Hilmy, M. E. [محمد عز الدين حلمي; Saad, N.; Abu-Zeid, M. M.

1983-01-01

Combined microscopic, grain-size and heavy-mineral analyses were carried out on the Bahariya Formation at Gebel El-Dist (type section), Bahariya Oasis. These studies revealed that the formation is composed of moderately poorly-sorted silty sandstones and sandy siltstones with few intercalations of sandstones, siltstones and clayey siltstones. The heavy-mineral suite is composed of (in order of decreasing abundance): opaques, zircon, rutile. staurolite, tourmaline, kyanite, garnet and bioti...

Protection of surface assets on Mars from wind blown jettisoned spacecraft components

Science.gov (United States)

Paton, Mark

2017-07-01

Jettisoned Entry, Descent and Landing System (EDLS) hardware from landing spacecraft have been observed by orbiting spacecraft, strewn over the Martian surface. Future Mars missions that land spacecraft close to prelanded assets will have to use a landing architecture that somehow minimises the possibility of impacts from these jettisoned EDLS components. Computer modelling is used here to investigate the influence of wind speed and direction on the distribution of EDLS components on the surface. Typical wind speeds encountered in the Martian Planetary Boundary Layer (PBL) were found to be of sufficient strength to blow items having a low ballistic coefficient, i.e. Hypersonic Inflatable Aerodynamic Decelerators (HIADs) or parachutes, onto prelanded assets even when the lander itself touches down several kilometres away. Employing meteorological measurements and careful characterisation of the Martian PBL, e.g. appropriate wind speed probability density functions, may then benefit future spacecraft landings, increase safety and possibly help reduce the delta v budget for Mars landers that rely on aerodynamic decelerators.

DIST/AVC Out-Put Definition.

Science.gov (United States)

Wilkinson, Gene L.

The first stage of development of a management information system for DIST/AVC (Division of Instructional Technology/Audio-Visual Center) is the definition of out-put units. Some constraints on the definition of output units are: 1) they should reflect goals of the organization, 2) they should reflect organizational structure and procedures, and…

THE CONTRIBUTION OF CORONAL JETS TO THE SOLAR WIND

Energy Technology Data Exchange (ETDEWEB)

Lionello, R.; Török, T.; Titov, V. S.; Mikić, Z.; Linker, J. A. [Predictive Science Inc., 9990 Mesa Rim Road, Suite 170, San Diego, CA 92121 (United States); Leake, J. E.; Linton, M. G., E-mail: lionel@predsci.com [US Naval Research Laboratory 4555 Overlook Avenue, SW Washington, DC 20375 (United States)

2016-11-01

Transient collimated plasma eruptions in the solar corona, commonly known as coronal (or X-ray) jets, are among the most interesting manifestations of solar activity. It has been suggested that these events contribute to the mass and energy content of the corona and solar wind, but the extent of these contributions remains uncertain. We have recently modeled the formation and evolution of coronal jets using a three-dimensional (3D) magnetohydrodynamic (MHD) code with thermodynamics in a large spherical domain that includes the solar wind. Our model is coupled to 3D MHD flux-emergence simulations, i.e., we use boundary conditions provided by such simulations to drive a time-dependent coronal evolution. The model includes parametric coronal heating, radiative losses, and thermal conduction, which enables us to simulate the dynamics and plasma properties of coronal jets in a more realistic manner than done so far. Here, we employ these simulations to calculate the amount of mass and energy transported by coronal jets into the outer corona and inner heliosphere. Based on observed jet-occurrence rates, we then estimate the total contribution of coronal jets to the mass and energy content of the solar wind to (0.4–3.0)% and (0.3–1.0)%, respectively. Our results are largely consistent with the few previous rough estimates obtained from observations, supporting the conjecture that coronal jets provide only a small amount of mass and energy to the solar wind. We emphasize, however, that more advanced observations and simulations (including parametric studies) are needed to substantiate this conjecture.

Distribution and provenance of wind-blown SE Pacific surface sediments

OpenAIRE

Saukel, C.; Lamy, F.; Stuut, J.B.W.; Tiedemann, R.; Vogt, C.

2011-01-01

The reconstruction of low-latitude ocean-atmosphere interactions is one of the major issues of (paleo-) environmental studies. The trade winds, extending over 20 degrees to 30 degrees of latitude in both hemispheres, between the subtropical highs and the intertropical convergence zone, are major components of the atmospheric circulation and little is known about their long-term variability on geological time-scales, in particular in the Pacific sector. We present the modern spatial pattern of...

System analysis of dry black liquor gasification based synthetic gas production comparing oxygen and air blown gasification systems

International Nuclear Information System (INIS)

Naqvi, Muhammad; Yan, Jinyue; Dahlquist, Erik

2013-01-01

Highlights: ► Circulating fluidized bed system for black liquor gasification with direct causticization. ► Effects of gasifying medium i.e. oxygen or air, on gasification are studied. ► Direct causticization eliminates energy intensive limekiln reducing biomass use. ► Results show 10% higher SNG production from O 2 blown system than air blown system. ► SNG production is higher in O 2 blown system than air blown system. - Abstract: The black liquor gasification based bio-fuel production at chemical pulp mill is an attractive option to replace conventional recovery boilers increasing system energy efficiency. The present paper studies circulating fluidized bed system with direct causticization using TiO 2 for the gasification of the black liquor to the synthesis gas. The advantage of using direct causticization is the elimination of energy-intensive lime kiln which is an integral part of the conventional black liquor recovery system. The study evaluates the effects of gasifying medium i.e. oxygen or air, on the fluidized bed gasification system, the synthesis gas composition, and the downstream processes for the synthesis gas conversion to the synthetic natural gas (SNG). The results showed higher synthetic natural gas production potential with about 10% higher energy efficiency using oxygen blown gasification system than the air blown system. From the pulp mill integration perspective, the material and energy balance results in better integration of air blown system than the oxygen blown system, e.g. less steam required to be generated in the power boiler, less electricity import, and less additional biomass requirement. However, the air blown system still requires a significant amount of energy in terms of the synthesis gas handling and gas upgrading using the nitrogen rejection system

Tar formation in a steam-O2 blown CFB gasifier and a steam blown PBFB gasifier (BabyHPR) : Comparison between different on-line measurement techniques and the off-line SPA sampling and analysis method

NARCIS (Netherlands)

Meng, X.; Mitsakis, P.; Mayerhofen, M.; De Jong, W.; Gaderer, M.; Verkooijen, A.H.M.; Spliethoff, H.

2012-01-01

Two on-line tar measurement campaigns were carried out using an atmospheric pressure 100 “”kWth steam-O2 blown circulating fluidized bed (CFB) gasifier at the Delft University of Technology (TUD) and a 30–40kWth steam blown pressurized bubbling fluidized bed (PBFB) gasifier BabyHPR (Heatpipe

The Contribution of Stellar Winds to Cosmic Ray Production

Science.gov (United States)

Seo, Jeongbhin; Kang, Hyesung; Ryu, Dongsu

2018-04-01

Massive stars blow powerful stellar winds throughout their evolutionary stages from the main sequence to Wolf-Rayet phases. The wind mechanical energy of a massive star deposited to the interstellar medium can be comparable to the explosion energy of a core-collapse supernova that detonates at the end of its life In this study, we estimate the kinetic energy deposition by massive stars in our Galaxy by considering the integrated Galactic initial mass function and modeling the stellar wind luminosity. The mass loss rate and terminal velocity of stellar winds during the main sequence, red supergiant, and Wolf-Rayet stages are estimated by adopting theoretical calculations and observational data published in the literature. We find that the total stellar wind luminosity by all massive stars in the Galaxy is about Lw ≈ 1.1×1041 ergs, which is about 1/4 of the power of supernova explosions, LSN ≈ 4.8×1041 ergs. If we assume that ˜1-1% of the wind luminosity could be converted to Galactic cosmic rays (GCRs) through collisonless shocks such as termination shocks in stellar bubbles and superbubbles, colliding-wind shocks in binaries, and bow-shocks of massive runaway stars, stellar winds are expected to make a significant contribution to GCR production, though lower than that of supernova remnants.

Distúrbios de memória em pacientes epilépticos

Directory of Open Access Journals (Sweden)

STELLA FLORINDO

1999-01-01

Full Text Available O autor estudou distúrbios de memória em pacientes epilépticos com crises parciais complexas (CPC, com os objetivos de: 1 identificar estes distúrbios; e 2 comparar os resultados dos pacientes com os dos controles. Foram estudados 50 pacientes adultos e 20 sujeitos sem enfermidades neuropsiquiátricas. Os métodos consistiram em: 1 investigação da atividade mnemônica através do Teste de Memória de Wechsler (subtestes: Armazenamento e Recuperação, Memória Recente e Memória Imediata; e 2 comparação entre os resultados de ambos os grupos. 3 associação entre SPECT Cerebral e atividade mnemônica. Nos três subtestes, os pacientes apresentaram desempenho cognitivo significativamente inferior ao dos controles (p <0,05. Constatou-se a associação entre hipofluxo em região temporal esquerda e distúrbio da memória nos três subtestes. Concluiu-se que há associação entre CPC e distúrbios da atividade mnemônica.

The vertical structure of airflow turbulence characteristics within a boundary layer during wind blown sand transport over a beach

Science.gov (United States)

Lee, Z. S.; Baas, A. C.; Jackson, D.; Cooper, J. A.; Lynch, K.; Delgado-Fernandez, I.; Beyers, M.

2010-12-01

Recent studies have suggested the significant role of boundary layer turbulence and coherent flow structures on sand transport by wind over beaches and desert dunes. Widespread use of sonic anemometry and high-frequency sand transport sensors and traps have facilitated a move beyond the basic monitoring of shear velocities and bulk sediment transport to more detailed measurements at much higher spatio-temporal resolutions. In this paper we present results of a small-scale point-location field study of boundary layer turbulence and shear stresses conducted under obliquely onshore winds over a beach at Magilligan Strand, Northern Ireland. High-frequency (25 Hz) 3D wind vector measurements were collected at five different heights between 0.13 and 1.67 metres above the bed using sonic anemometry for durations of several hours, and the associated sand transport response was measured using an array of Safires. The wind data are used to investigate the vertical structure of Reynolds shear stresses and burst-sweep event characteristics, as well as a comparison with the standard logarithmic (law-of-the-wall) wind profile. The study explores the identification and selection of a characteristic event duration based on integral time-scales as well as spectral analysis, and includes an assessment of the issues involved with data rotations for yaw, pitch, and roll corrections relative to flow streamlines, and the subsequently derived turbulence parameters based on fluctuating vector components (u’, v’, w’). Results show how the contributions to shear stress and the average pitch of bursts and sweeps changes as a function of height above the bed, indicating the transformation of top-down turbulent eddies as they travel toward the surface. A comparison between the turbulence data and the synchronous sand transport events, meanwhile, reveals the potential effects of enhanced saltation layer roughness feedback on eddies close to the bed.

Presentation of a stochastic model estimating the wind energy contribution in remote island electrical networks

International Nuclear Information System (INIS)

Kaldellis, J.K.; Kapsali, M.; Tiligadas, D.

2012-01-01

Highlights: ► This study estimates the maximum wind energy contribution to an isolated micro-grid. ► An integrated computational tool is developed on the basis of stochastic analysis. ► The probability distribution of the wind energy surplus and deficit is estimated. ► The results indicate that a strict penetration limit is imposed to wind energy. -- Abstract: The electrification in remote islands whose electricity distribution network is not connected to the mainland’s grid is mostly based on Autonomous Power Stations (APSs) that are usually characterized by a considerably high electricity production cost, while at the same time the contribution of Renewable Energy Sources (RES) in these regions accounts for less than 10% of the total electricity generation. This actually results from the fact that despite the excellent wind potential of most of these islands, the wind energy contribution is significantly restricted from limits imposed to protect the remote electrical grids from possible instability problems, due to the stochastic wind speed behavior and the variable electricity consumption. On the basis of probability distribution of the load demand of a representative Greek island and the corresponding data related to the available wind potential, the present study estimates the maximum – acceptable by the local grid – wind energy contribution. For that reason, an integrated computational algorithm has been developed from first principles, based on a stochastic analysis. According to the results obtained, it becomes evident that with the current wind turbine technology, wind energy cannot play a key role in coping with the electrification problems encountered in many Greek island regions, excluding however the case of introducing bulk energy storage systems that may provide considerable recovery of the remarkable wind energy rejections expected.

Modelo competitivo da distância percorrida por futebolistas na Uefa Euro 2008

Directory of Open Access Journals (Sweden)

Tiago Volpi Braz

2010-05-01

Full Text Available O objetivo do presente estudo centra-se em conhecer o modelo competitivo da distância percorrida por futebolistas na Uefa Euro 2008, mediante as posições de jogo, os tempos e a distância total percorrida durante as partidas. Foram analisadas todas as partidas das 16 seleções, totalizando 31 jogos, dos quais participaram 460 futebolistas. Posteriormente, produziram-se informações descritivas e inferenciais. Os principais resultados apontam que: i futebolistas da elite europeia percorreram 10232 ± 852m; ii meio-campistas (10894 ± 648m percorreram maior distância, seguidos pelos laterais (10274±694m, atacantes (10108 ± 624m, zagueiros (9498 ± 592m e goleiros (4198 ± 610m; iii a distância média percorrida no 1º tempo (4907 ± 201m das partidas foi maior do que a do 2º tempo (4890 ± 238m.

DistMap: a toolkit for distributed short read mapping on a Hadoop cluster.

Directory of Open Access Journals (Sweden)

Ram Vinay Pandey

Full Text Available With the rapid and steady increase of next generation sequencing data output, the mapping of short reads has become a major data analysis bottleneck. On a single computer, it can take several days to map the vast quantity of reads produced from a single Illumina HiSeq lane. In an attempt to ameliorate this bottleneck we present a new tool, DistMap - a modular, scalable and integrated workflow to map reads in the Hadoop distributed computing framework. DistMap is easy to use, currently supports nine different short read mapping tools and can be run on all Unix-based operating systems. It accepts reads in FASTQ format as input and provides mapped reads in a SAM/BAM format. DistMap supports both paired-end and single-end reads thereby allowing the mapping of read data produced by different sequencing platforms. DistMap is available from http://code.google.com/p/distmap/

Contributions from the Department of Wind Energy and Atmospheric Physics to EWEC `99 in Nice, France

Energy Technology Data Exchange (ETDEWEB)

Larsen, Gunner C; Westermann, Kirsten; Noergaard, Per [eds.

1999-03-01

The first conference following the merger of the series of European Union Wind Energy Conference and the European Wind Energy Conferences - EWEC`99 - was held in Nice, France during the period 1-5 March 1999. About 600 delegates, mainly from Europe but also from other parts of the world, attended the conference. The conference contributions included 96 oral presentations and 305 posters. The Department of Wind Energy and Atmospheric Physics contributed with 29 oral presentations and 36 posters with members of the department as authors or co-authors. The present report contains the set of these papers available at the deadline 19 March 1999. The contributions cover a wide spectrum of subjects including wind resources, aerodynamics, reliability and load assessment, grid connection, measurement methods, innovative wind turbines and market aspects. (au)

Measuring Density Profiles of Electrons and Heavy Particles in a Stable Axially Blown Arc

Science.gov (United States)

Carstensen, J.; Stoller, P.; Galletti, B.; Doiron, C. B.; Sokolov, A.

2017-08-01

Two-color spatial carrier wave interferometry employing pulsed 532- and 671-nm lasers is used to measure the electron-density and heavy-particle-density profiles in the stagnation point of a stable, axially blown arc in argon for currents of 50 to 200 A and stagnation point pressures of 0.2 to 16 bar. This technique takes advantage of the fact that the free-electron contribution to the refractive index depends strongly on the wavelength, while that of the heavy particles does not. The high spatial resolution achieved allows the hot core of the arc to be readily distinguished from the surrounding boundary layer. A custom-built test device is used to ensure flow conditions that lead to a stable, axisymmetric arc; this permits the reconstruction of the density and temperature profiles using a single projection (interferometric image) of the refractive-index distribution through the arc (at two wavelengths). The arc radius determined from the heavy-particle density decreases with increasing stagnation pressure and increases with the current. These measurements are in good agreement with a simple axially blown arc model taking into account Ohmic heating, radiation losses, and enthalpy flow for core temperatures of approximately 16 500 K. The measured electron density at the center of the arc agrees well with a prediction based on local thermodynamic equilibrium.

DISTING: A web application for fast algorithmic computation of alternative indistinguishable linear compartmental models.

Science.gov (United States)

Davidson, Natalie R; Godfrey, Keith R; Alquaddoomi, Faisal; Nola, David; DiStefano, Joseph J

2017-05-01

We describe and illustrate use of DISTING, a novel web application for computing alternative structurally identifiable linear compartmental models that are input-output indistinguishable from a postulated linear compartmental model. Several computer packages are available for analysing the structural identifiability of such models, but DISTING is the first to be made available for assessing indistinguishability. The computational algorithms embedded in DISTING are based on advanced versions of established geometric and algebraic properties of linear compartmental models, embedded in a user-friendly graphic model user interface. Novel computational tools greatly speed up the overall procedure. These include algorithms for Jacobian matrix reduction, submatrix rank reduction, and parallelization of candidate rank computations in symbolic matrix analysis. The application of DISTING to three postulated models with respectively two, three and four compartments is given. The 2-compartment example is used to illustrate the indistinguishability problem; the original (unidentifiable) model is found to have two structurally identifiable models that are indistinguishable from it. The 3-compartment example has three structurally identifiable indistinguishable models. It is found from DISTING that the four-compartment example has five structurally identifiable models indistinguishable from the original postulated model. This example shows that care is needed when dealing with models that have two or more compartments which are neither perturbed nor observed, because the numbering of these compartments may be arbitrary. DISTING is universally and freely available via the Internet. It is easy to use and circumvents tedious and complicated algebraic analysis previously done by hand. Copyright © 2017 Elsevier B.V. All rights reserved.

An Overview of Wind-Driven Rovers for Planetary Exploration

Science.gov (United States)

Hajos, Gregory A.; Jones, Jack A.; Behar, Alberto; Dodd, Micheal

2005-01-01

The use of in-situ propulsion is considered enabling technology for long duration planetary surface missions. Most studies have focused on stored energy from chemicals extracted from the soil or the use of soil chemicals to produce photovoltaic arrays. An older form of in-situ propulsion is the use of wind power. Recent studies have shown potential for wind driven craft for exploration of Mars, Titan and Venus. The power of the wind, used for centuries to power wind mills and sailing ships, is now being applied to modern land craft. Efforts are now underway to use the wind to push exploration vehicles on other planets and moons in extended survey missions. Tumbleweed rovers are emerging as a new type of wind-driven science platform concept. Recent investigations by the National Aeronautics and Space Administration (NASA) and Jet Propulsion Laboratory (JPL) indicate that these light-weight, mostly spherical or quasi-spherical devices have potential for long distance surface exploration missions. As a power boat has unique capabilities, but relies on stored energy (fuel) to move the vessel, the Tumbleweed, like the sailing ships of the early explorers on earth, uses an unlimited resource the wind to move around the surface of Mars. This has the potential to reduce the major mass drivers of robotic rovers as well as the power generation and storage systems. Jacques Blamont of JPL and the University of Paris conceived the first documented Mars wind-blown ball in 1977, shortly after the Viking landers discovered that Mars has a thin CO2 atmosphere with relatively strong winds. In 1995, Jack Jones, et al, of JPL conceived of a large wind-blown inflated ball for Mars that could also be driven and steered by means of a motorized mass hanging beneath the rolling axis of the ball. A team at NASA Langley Research Center started a biomimetic Tumbleweed design study in 1998. Wind tunnel and CFD analysis were applied to a variety of concepts to optimize the aerodynamic

Modeling and analysis of solar wind generated contributions to the near-Earth magnetic field

DEFF Research Database (Denmark)

Vennerstrøm, Susanne; Moretto, T.; Rastatter, L.

2006-01-01

Solar wind generated magnetic disturbances are currently one of the major obstacles for improving the accuracy in the determination of the magnetic field due to sources internal to the Earth. In the present study a global MHD model of solar wind magnetosphere interaction is used to obtain...... a physically consistent, divergence-free model of ionospheric, field-aligned and magnetospheric currents in a realistic magnetospheric geometry. The magnetic field near the Earth due to these currents is analyzed by estimating and comparing the contributions from the various parts of the system, with the aim...... of identifying the most important aspects of the solar wind disturbances in an internal field modeling context. The contribution from the distant magnetospheric currents is found to consist of two, mainly opposing, contributions from respectively the dayside magnetopause currents and the cross-tail current...

Contribution of Strong Discontinuities to the Power Spectrum of the Solar Wind

International Nuclear Information System (INIS)

Borovsky, Joseph E.

2010-01-01

Eight and a half years of magnetic field measurements (2 22 samples) from the ACE spacecraft in the solar wind at 1 A.U. are analyzed. Strong (large-rotation-angle) discontinuities in the solar wind are collected and measured. An artificial time series is created that preserves the timing and amplitudes of the discontinuities. The power spectral density of the discontinuity series is calculated and compared with the power spectral density of the solar-wind magnetic field. The strong discontinuities produce a power-law spectrum in the ''inertial subrange'' with a spectral index near the Kolmogorov -5/3 index. The discontinuity spectrum contains about half of the power of the full solar-wind magnetic field over this ''inertial subrange.'' Warnings are issued about the significant contribution of discontinuities to the spectrum of the solar wind, complicating interpretation of spectral power and spectral indices.

Micro Fine Sized Palm Oil Fuel Ash Produced Using a Wind Tunnel Production System

Directory of Open Access Journals (Sweden)

R. Ahmadi

2016-01-01

Full Text Available Micro fine sized palm oil fuel ash (POFA is a new supplementary cementitious material that can increase the strength, durability, and workability of concrete. However, production of this material incurs high cost and is not practical for the construction industry. This paper investigates a simple methodology of producing micro fine sized POFA by means of a laboratory scale wind tunnel system. The raw POFA obtained from an oil palm factory is first calcined to remove carbon residue and then grinded in Los Angeles abrasion machine. The grinded POFA is then blown in the fabricated wind tunnel system for separation into different ranges of particle sizes. The physical, morphological, and chemical properties of the micro fine sized POFA were then investigated using Laser Particle Size Analyser (PSA, nitrogen sorption, and Scanning Electron Microscopy with Energy Dispersive X-Ray (SEM-EDX. A total of 32.1% micro fine sized POFA were collected from each sample blown, with the size range of 1–10 micrometers. The devised laboratory scale of wind tunnel production system is successful in producing micro fine sized POFA and, with modifications, this system is envisaged applicable to be used to commercialize micro fine sized POFA production for the construction industry.

Processing precious metals in a top-blown rotary converter

Science.gov (United States)

Whellock, John G.; Matousek, Jan W.

1990-09-01

Copper-nickel/platinum-palladium flotation concentrates produced by the Stillwater Mining Company were smelted and refined in an integrated pilot plant consisting of a submerged-arc electric furnace and top-blown rotary converter. The conversion of high-iron electric furnace mattes was achieved with apparent oxygen efficiencies in excess of 100 percent. Platinum and palladium recoveries averaged 99 percent, and copper and nickel recoveries were 94 percent.

Wind tunnel experimental study on the effect of PAM on soil wind erosion control.

Science.gov (United States)

He, Ji-Jun; Cai, Qiang-Guo; Tang, Ze-Jun

2008-10-01

In recent years, high-molecular-weight anionic polyacrylamide (PAM) have been widely tested on a variety of soils, primarily in water erosion control. However, little information is available regarding the effectiveness of PAM on preventing soil loss from wind erosion. The research adopted room wind tunnel experiment, two kinds of soils were used which were from the agro-pastoral area of Inner Mongolia, the northwest of China, the clay content of soils were 22.0 and 13.7%, respectively. For these tests, all the treatments were performed under the condition of wind velocity of 14 m s(-1) and a blown angle of 8.75%, according to the actual situation of experimented area. The study results indicated that using PAM on the soil surface could enhance the capability of avoiding the wind erosion, at the same time, the effect of controlling wind soil erosion with 4 g m(-2) PAM was better than 2 g m(-2) PAM's. Economically, the 2 g m(-2) PAM used in soil surface can control wind erosion effectively in this region. The prophase PAM accumulated in soil could not improve the capability of avoiding the wind erosion, owing to the degradation of PAM in the soil and the continual tillage year after year. The texture of soil is a main factor influencing the capability of soil avoiding wind erosion. Soil with higher clay content has the higher capability of preventing soil from wind erosion than one with the opposite one under the together action of PAM and water.

A modified Gaussian model for the thermal plume from a ground-based heat source in a cross-wind

International Nuclear Information System (INIS)

Selander, W.N.; Barry, P.J.; Robertson, E.

1990-06-01

An array of propane burners operating at ground level in a cross-wind was used as a heat source to establish a blown-over thermal plume. A three-dimensional array of thermocouples was used to continuously measure the plume temperature downwind from the source. The resulting data were used to correlate the parameters of a modified Gaussian model for plume rise and dispersion with source strength, wind speed, and atmospheric dispersion parameters

Optical and Mechanical Properties of Glass Blown In Vacuo

Science.gov (United States)

Manning, andrew; Tucker, Dennis; Mooney, Theodore; Herren, Kenneth; Gregory, Don A.

2006-01-01

Theoretically, the strength of glass processed in vacuum should be higher due to outgassing of contaminants normally present in the glass, such as bulk water in the form of OH bonds that tends to weaken the glass structure. In this research, small discs of a few types of glass have been subjected to various temperatures for extended periods of time in vacuum. Their strength was then tested using a standard flexure technique, facilitated by a custom-designed test fixture, and the results were compared to glass tested in air using the same fixture. The purpose of the glass blowing investigation was to prove the basic feasibility of a high-level concept for in-space manufacture of optical elements. The central requirement was that the glass bubble had to be blown into a support structure such that the bubble could be handled by manipulation of the structure. The blown bubble attached itself to a mullite ring geometrically and mechanically, as a demonstration in the initial experiments described here, by expanding through and around it. The vacuum system used was custom made, as were most of the components of the system, such as the heating element, the glass and ring support structure, and the gas inlet system that provided the pressure needed to blow the glass.

Distúrbios do sono em adultos de uma cidade do Estado de São Paulo

Directory of Open Access Journals (Sweden)

Everton Alex Carvalho Zanuto

2015-03-01

Full Text Available OBJETIVO: Analisar a ocorrência de distúrbios relacionados ao sono entre adultos de Presidente Prudente, São Paulo, bem como identificar suas associações com variáveis comportamentais, sociodemográficas e de estado nutricional. MÉTODOS: Após a seleção aleatória da amostra, foram realizadas entrevistas face a face com 743 adultos de ambos os sexos, residentes na cidade de Presidente Prudente, São Paulo. Foram aplicados questionários para análise de distúrbios relacionados ao sono, variáveis sociodemográficas (sexo, idade, etnia, escolaridade, comportamentais (atividade física no lazer, etilismo e tabagismo e de estado nutricional. RESULTADOS: Foram observados distúrbios relacionados ao sono em 46,7% da amostra, com intervalo de confiança de 95% (IC95% 43,1 - 50,2. Após a análise multivariada, foi observado que o sexo feminino, com odds ratio (OR = 1,74 (IC95% 1,26 - 2,40, escolaridade (OR = 0,49; IC95% 0,28 - 0,82, sobrepeso (OR = 1,99; IC95% 1,39 - 2,85 e obesidade (OR = 2,90; IC95% 1,94 - 4,35 foram associados à ocorrência de distúrbios relacionados ao sono. CONCLUSÃO: É elevada a ocorrência de distúrbios de sono na amostra analisada, os quais foram mais frequentes em mulheres, pessoas de menor escolaridade e com sobrepeso e obesidade.

Relative contributions of local wind and topography to the coastal upwelling intensity in the northern South China Sea

Science.gov (United States)

Wang, Dongxiao; Shu, Yeqiang; Xue, Huijie; Hu, Jianyu; Chen, Ju; Zhuang, Wei; Zu, TingTing; Xu, Jindian

2014-04-01

Topographically induced upwelling caused by the interaction between large-scale currents and topography was observed during four cruises in the northern South China Sea (NSCS) when the upwelling favorable wind retreated. Using a high-resolution version of the Princeton Ocean Model, we investigate relative contributions of local wind and topography to the upwelling intensity in the NSCS. The results show that the topographically induced upwelling is sensitive to alongshore large-scale currents, which have an important contribution to the upwelling intensity. The topographically induced upwelling is comparable with the wind-driven upwelling at surface and has a stronger contribution to the upwelling intensity than the local wind does at bottom in the near-shore shelf region. The widened shelf to the southwest of Shanwei and west of the Taiwan Banks intensifies the bottom friction, especially off Shantou, which is a key factor for topographically induced upwelling in terms of bottom Ekman transport and Ekman pumping. The local upwelling favorable wind enhances the bottom friction as well as net onshore transport along the 50 m isobath, whereas it has less influence along the 30 m isobath. This implies the local wind is more important in upwelling intensity in the offshore region than in the nearshore region. The contribution of local upwelling favorable wind on upwelling intensity is comparable with that of topography along the 50 m isobath. The effects of local upwelling favorable wind on upwelling intensity are twofold: on one hand, the wind transports surface warm water offshore, and as a compensation of mass the bottom current transports cold water onshore; on the other hand, the wind enhances the coastal current, and the bottom friction in turn increases the topographically induced upwelling intensity.

Prepare to be blown away

CERN Multimedia

Katarina Anthony

2013-01-01

On 16 April, the TE-VSC team began identifying and repairing the LHC’s faulty radiofrequency fingers. Their main tool: an “RF ball” that will be – quite literally – blown through the beam pipe.   RF ball tests carried out in 2007. In the bellows of the LHC interconnects, you’ll find the vacuum pipe held together by some flexible metallic connectors known as “RF fingers”. These RF fingers maintain the electrical contact between the LHC magnets, ensuring the continuity of the beam pipe. As the magnets contract and expand when heated up and cooled down, the fingers preserve their connection by simply sliding over each other. However, experience has shown that the movement of the LHC magnets can cause the fingers to buckle. “It’s not a question of bad design,” explains Vincent Baglin, from TE's Vacuum, Surfaces and Coatings (TE-VSC) group. “Rather, there were slight non...

Water-Blown Polyurethane Foams Showing a Reversible Shape-Memory Effect

Directory of Open Access Journals (Sweden)

Elena Zharinova

2016-11-01

Full Text Available Water-blown polyurethane (PU foams are of enormous technological interest as they are widely applied in various fields, i.e., consumer goods, medicine, automotive or aerospace industries. The discovery of the one-way shape-memory effect in PU foams provided a fresh impetus for extensive investigations on porous polymeric actuators over the past decades. High expansion ratios during the shape-recovery are of special interest when big volume changes are required, for example to fill an aneurysm during micro-invasive surgery or save space during transportation. However, the need to program the foams before each operation cycle could be a drawback impeding the entry of shape-memory polymeric (SMP foams to our daily life. Here, we showed that a reversible shape-memory effect (rSME is achievable for polyurethane water-blown semicrystalline foams. We selected commercially available crystallizable poly(ε-caprolactone-diols of different molecular weight for foams synthesis, followed by investigations of morphology, thermal, thermomechanical and shape-memory properties of obtained compositions. Densities of synthesized foams varied from 110 to 180 kg∙m−3, while peak melting temperatures were composition-dependent and changed from 36 to 47 °C, while the melting temperature interval was around 15 K. All semicrystalline foams exhibited excellent one-way SME with shape-fixity ratios slightly above 100% and shape-recovery ratios from the second cycle of 99%. The composition with broad distribution of molecular weights of poly(ε-caprolactone-diols exhibited an rSME of about 12% upon cyclic heating and cooling from Tlow = 10 °C and Thigh = 47 °C. We anticipate that our experimental study opens a field of systematic investigation of rSMEs in porous polymeric materials on macro and micro scale and extend the application of water-blown polyurethane foams to, e.g., protective covers with zero thermal expansion or even cushions adjustable to a certain body

Contributions from the Department of Meteorology and Wind Energy to the EUWEC`96 conference in Goeteborg, Sweden

Energy Technology Data Exchange (ETDEWEB)

Larsen, G C [ed.

1996-08-01

The 5th European Union Wind Energy Conference and Exhibition-EUWEC `96- was held in Gothenburg, Sweden during the period 20-24 May 1996. 520 delegates, mainly from Europe but also from other parts of the world, attended the conference. The conference contributions included roughly 70 oral presentations and 200 posters. The Department of Meteorology and Wind Energy contributed with 17 oral presentations and 15 posters with members of the department as authors or co-authors. The present report contains the full set of these papers, covering a wide spectrum of subjects including research strategy, wind resources, power quality, grid connection, wind-diesel systems, aerodynamics, load assessment and reliability, and certification. (au) 49 tabs., 146 ills., 228 refs.

Contributions from the Department of Meteorology and Wind Energy to the EWEC'94 conference in Thessaloniki, Greece

International Nuclear Information System (INIS)

Larsen, G.C.

1995-01-01

The 5'th European Wind Energy Association Conference and Exhibition - EWEC'94 - was held in Thessaloniki, Greece during the period 10-14 October 1994. 461 delegates, mainly from Europe but also from other parts of the world, attended the conference. The conference contributions included 235 oral presentations and 143 posters. The Department of Meteorology and Wind Energy contributed with 18 oral presentations and 3 poster with members of the department as authors or co-authors. The present report contains the full set of these papers, covering a wide spectrum of subjects including wind resources, reliability and load assessment, grid connection, wind-diesel systems, and marked aspects. (au) (36 tabs., 163 ills., 150 refs.)

Contributions from the Department of Meteorology and Wind Energy to the EWEC`94 conference in Thessaloniki, Greece

Energy Technology Data Exchange (ETDEWEB)

Larsen, G C [ed.

1995-01-01

The 5`th European Wind Energy Association Conference and Exhibition - EWEC`94 - was held in Thessaloniki, Greece during the period 10-14 October 1994. 461 delegates, mainly from Europe but also from other parts of the world, attended the conference. The conference contributions included 235 oral presentations and 143 posters. The Department of Meteorology and Wind Energy contributed with 18 oral presentations and 3 poster with members of the department as authors or co-authors. The present report contains the full set of these papers, covering a wide spectrum of subjects including wind resources, reliability and load assessment, grid connection, wind-diesel systems, and marked aspects. (au) (36 tabs., 163 ills., 150 refs.)

Environmental impacts of micro-wind turbines and their potential to contribute to UK climate change targets

International Nuclear Information System (INIS)

Greening, Benjamin; Azapagic, Adisa

2013-01-01

This paper evaluates the life cycle environmental sustainability of micro-wind turbines in the UK in comparison with grid electricity and solar PV (photovoltaics). The results suggests that per kWh electricity generated, the majority of environmental impacts from the wind turbines are lower than from grid electricity, ranging from 26% lower terrestrial toxicity to 92% lower global warming. However, depletion of abiotic elements, fresh-water and human toxicities are 82%, 74% and 53% higher than for grid electricity, respectively. The wind turbines are more environmentally sustainable than solar PV for seven out of 11 impacts, ranging from 7.5% lower eutrophication to 85% lower ozone layer depletion. However, depletion of fossil resources, fresh-water, human and terrestrial toxicities are higher for the wind turbine than for the PV, ranging from 5% for the former to 87% for the latter. UK-wide deployment of micro-wind turbines would save between 0.6 and 1% of GHG (greenhouse gas) emissions on 2009 levels. Therefore, the potential of micro-wind turbines to contribute towards UK's climate change targets is limited. - Highlights: • Life cycle environmental impacts of micro-wind turbines estimated for UK conditions. • The majority impacts are lower for micro-wind turbines than for grid electricity and solar PV. • Some impacts from micro-wind are higher, notably fresh-water and human toxicity. • At the national level, wind turbines would save only 0.6% GHG emissions on 2009 levels. • The potential of micro-wind turbines to contribute to UK's climate change targets is limited

Kinetic and Potential Sputtering of Lunar Regolith: The Contribution of the Heavy Highly Charged (Minority) Solar Wind Ions

Science.gov (United States)

Meyer, F. W.; Barghouty, A. F.

2012-01-01

Solar wind sputtering of the lunar surface helps determine the composition of the lunar exosphere and contributes to surface weathering. To date, only the effects of the two dominant solar wind constituents, H+ and He+, have been considered. The heavier, less abundant solar wind constituents have much larger sputtering yields because they have greater mass (kinetic sputtering) and they are highly charged (potential sputtering) Their contribution to total sputtering can therefore be orders of magnitude larger than their relative abundances would suggest

On generalization of electric field strength in longitudinally blown arcs

OpenAIRE

Yas'ko, O.I.; Esipchuk, A.M.; Qing, Z.; Schram, D.C.; Fauchais, P.

1997-01-01

Generalization of av. elec. field strength for different discharge conditions in longitudinally blown arcs is considered. Exptl. data for distinctive devices and different gases were used for phys. modeling. Anal. showed that heat transfer processes are responsible for I-E characteristic formation. Turbulent heat transfer is the most effective for atm. pressure discharges while convection plays the main role in vacuum arcs. A generalized I-E characteristic was obtained. [on SciFinder (R)

Uma arquitetura de um sistema learning companion para ensino a distância

OpenAIRE

Faraco, Rafael Avila

2003-01-01

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção. Atualmente o ensino a distância constitui-se em uma modalidade de ensino importante no sentido em que procura atender a uma demanda por capacitação contínua de um público que sofre com a concorrência acirrada, mercado de trabalho competitivo, falta de tempo e dificuldade de acesso à informação com qualidade. A evolução do ensino a distância, acompanhada pela ...

Arremessar por cima do ombro e a distância percorrida pelo implemento

OpenAIRE

Silva,Samuel Bento da; Vilela Junior,Guanis de Barros; Toloka,Rute Estanislava

2009-01-01

A habilidade de arremessar por cima do ombro tem sido bastante estudada, observando-se a velocidade do implemento, porém enquanto muitas tarefas têm como objetivo arremessar o mais longe possível, a distância percorrida pelo objeto ainda não tem sido investigada. O objetivo deste estudo foi verificar se existe relação entre o estágio de desenvolvimento motor nesta habilidade e a distância percorrida pelo implemento e observar diferenças entre os gêneros masculino e feminino; 50 crianças, com ...

A Method to Quantify the Wind and Non-wind Contribution to Year-to-year Air Quality Variation and its Application in China

Science.gov (United States)

LI, Y.; Lau, A. K. H.; Wong, A.; Fung, J. C. H.

2017-12-01

Changes in emissions and wind are often identified as the two dominant factors contributing to year-to-year variations in the concentration of primary pollutants. However, because changes in wind and emissions are intertwined, it has been difficult to quantitatively differentiate their effects on air quality directly from observed data. In particular, if the annual mean concentration of pollutants is higher than the previous year, it is difficult to identify whether the deterioration in air quality is caused by wind blowing from more polluted regions or an increase in contributing emissions. In this paper, based on wind and pollution roses, we propose a method to differentiate the effects of wind and non-wind (e.g., emissions) changes using direct observation. An index (L) is first defined to quantify the validity of the linear decomposition. The method is then validated by idealized experiments, numerical experiments and a two-year observation dataset from an actual emissions control program. Finally, we demonstrate the proposed method by studying long-term PM10 variations in Hong Kong during 2000-2011. We find that for most of the period, the linear decomposition of the changes in annual PM10 is valid (up to 90% confidence) and is dominated by the change in non-wind effects (e.g., emissions), whereas the average absolute effect from the wind variability is about 20%. Sensitivity analyses also suggest that our method should work in any location as long as the observed wind and pollution data have sufficient duration and resolution to resolve the corresponding wind and pollution roses. The method is applied for estimating the control effectiveness of the intervention programs in the Shanghai Expo, the longest socioeconomic international event held in China. The results show that integrated effect of control policies taken for improving the air quality in Shanghai are significantly effective for PM10 reduction and also effective for SO2 reduction, whereas the

A distância: a escola Lula para a formação de professores

Directory of Open Access Journals (Sweden)

Maria de Fátima Rodrigues Pereira

2012-08-01

Full Text Available A educação a distância com novas tecnologias de informação e comunicação (TICs estrutura-se, no Brasil, a partir da década de 1970, porque, também a partir de então, as TICs foram associadas ao processo produtivo. A educação a distância com TICs compõe uma conjuntura histórica de transição de um trabalho sob a gerência fordista para o toyotismo. Se, sob o fordismo as relações de trabalho se caracterizavam pelo caráter parcelar, fragmentado, da indústria seriada, da produção em série; sob o toyotismo o trabalho caracteriza-se pela flexibilização, a desregulamentação, a polivalência. Estas mudanças na base produtiva, do mundo da “empresa flexível, como diz o capital, ou do mundo da acumulação liofilizada, não alteram a forma de ser do capital, mas alteram, em muito, o que se pede à educação. Os que defendem a educação a distância com TICS apontam seu potencial de promover cidadania: demandas de difícil atendimento podem ser atingidas; possibilitam encurtamento de distâncias entre sujeitos e informações. Analisamse as políticas de educação a distância, em curso no Brasil, nomeadamente para a formação de professores. Recorre-se às contribuições da ciência política e da reflexão ontológica para este entendimento. O objetivo é contribuir com o debate, as práticas e as políticas de formação de professores.

Optimal Control and Operation Strategy for Wind Turbines Contributing to Grid Primary Frequency Regulation

Directory of Open Access Journals (Sweden)

Mun-Kyeom Kim

2017-09-01

Full Text Available This study introduces a frequency regulation strategy to enable the participation of wind turbines with permanent magnet synchronous generators (PMSGs. The optimal strategy focuses on developing the frequency support capability of PMSGs connected to the power system. Active power control is performed using maximum power point tracking (MPPT and de-loaded control to supply the required power reserve following a disturbance. A kinetic energy (KE reserve control is developed to enhance the frequency regulation capability of wind turbines. The coordination with the de-loaded control prevents instability in the PMSG wind system due to excessive KE discharge. A KE optimization method that maximizes the sum of the KE reserves at wind farms is also adopted to determine the de-loaded power reference for each PMSG wind turbine using the particle swarm optimization (PSO algorithm. To validate the effectiveness of the proposed optimal control and operation strategy, three different case studies are conducted using the PSCAD/EMTDC simulation tool. The results demonstrate that the optimal strategy enhances the frequency support contribution from PMSG wind turbines.

Contribution of wind energy to future electricity requirements of Pakistan

International Nuclear Information System (INIS)

Harijan, K.; Uqaili, M. A.; Memon, M.

2007-01-01

Pakistan is an energy deficit country. About half of the country's population has no access to electricity and per capita supply is only 520 kWh. About 67% of the conventional electricity is generated from fossil fuels with 51% and 16% share of gas and oil respectively. It has been projected that electricity demand in Pakistan would increase at an average annual growth rate of 5% to 12% under different scenarios. The indigenous reserves of oil and gas are limited and the country heavily depends on imported oil. The oil import bill is a serious strain on the country's economy and has been deteriorating the balance of payment situation. Pakistan is becoming increasingly more dependent on a few sources of supply and its energy security often hangs on the fragile threat of imported oil that is subject to supply disruptions and price volatility. The production and consumption of fossil fuels also adversely affects the quality of the environment due to indiscriminate release of toxic substances. Pakistan spends huge amount on the degradation of the environment. This shows that Pakistan must develop alternate, indigenous and environment friendly energy resources such as wind energy to meet its future electricity requirements. This paper presents an overview of wind power generation potential and assessment of its contribution to future electricity requirements of Pakistan under different policy scenarios. The country has about 1050 km long coastline. The technical potential of centralized grid connected wind power and wind home systems in the coastal area of the country has been estimated as about 484 TWh and 0.135 TWh per year respectively. The study concludes that wind power could meet about 20% to 50% of the electricity demand in Pakistan by the year 2030. The development and utilization of wind power would reduce the pressure on oil imports, protect the environment from pollution and improve the socio-economic conditions of the people

Educação a distância e diversidade no ensino superior

OpenAIRE

Aires, Luísa; Moura, Ana Pinto de; Seabra, Filipa; Moreira, J. António

2014-01-01

Os textos desta publicação refletem, de forma aprofundada, o pensamento dos autores sobre Educação a Distância e Inovação Pedagógica e, em particular, sobre o papel das metodologias, interações e dos recursos educacionais na inclusão e participação da população adulta no Ensino Superior. Estas reflexões foram, inicialmente, apresentadas no Seminário Educação a Distância e Diversidade no Ensino Superior, realizado no Porto, em julho de 2014 e, posteriormente, aprofundadas para publicação no pr...

The use of wind to produce energy in Ketodestrin province

International Nuclear Information System (INIS)

Shirani, E.; Ahmadkia, H.; Talebi, F.; Mojib, J.

2004-01-01

Productivity of oil and gas and their high cost benefit in matters than combustion, in one hand and their problem of environmental pollution when they are burnt, on the other hand attracted the decision markers in Iran to consider the wind energy as a good alternative for energy resources . It is especially important because of the existence of regions with high potential for wind energy in Iran. The Kurdestan province is one of the windy places in Iran that has not been considered for wind energy yet. In this paper, the general characteristics of the different kinds of winds which are blown throughout the year in Kurdestan province are considered firstly. Then by using the information from the stations in the sixth major cities in the province, the wind characteristics including power, direction, intensity and probability at different months of the year, are considered. The statistical studies show that Bijar, Zarine Obatoo, Ghorveh, Sanandaj and Marivan have the most wind energy potential, and Bijar and Ghorveh are the best places to install the wind turbine. for all of the above regions, the maximum of the wind average speed and powe are obtained in March, April. May, and the minimum of the average wind speed occurs in December. Bijar, Ghorveh and Zarine Obatoo have high average wind speed and its recommended to search for best places in these regions for the wind turbine sites

Statistical Investigation on Coherent Vortex Structure in Turbulent Drag Reducing Channel Flow with Blown Polymer Solution

International Nuclear Information System (INIS)

Ishitsuka, Shota; Motozawa, Masaaki; Kawaguchi, Yasuo; Iwamoto, Kaoru; Ando, Hirotomo; Senda, Tetsuya

2011-01-01

Coherent vortex structure in turbulent drag-reducing channel flow with blown polymer solution from the wall was investigated. As a statistical analysis, we carried out Galilean decomposition, swirling strength and linear stochastic estimation of the PIV data obtained by the PIV measurement in x – y plane. Reynolds number based on bulk velocity and channel height was set to 40000. As a result, the angle of shear layer that cleared up by using Galilean decomposition becomes small in the drag-reducing flow. Q3 events were observed near the shear layer. In addition, as a result of linear stochastic estimation (LSE) based on swirling strength, we confirmed that the velocity under the vortex core is strong in the water flow. This result shows Q2 (ejection) are dominant in the water flow. However, in the drag-reducing flow with blown polymer solution, the velocity above the vortex core become strong, that is, Q4 (sweep) events are relatively strong around the vortex core. This is the result of Q4 events to come from the channel center region because the polymer solution does not exist in this region. The typical structure like this was observed in the drag -reducing flow with blown polymer solution from the wall.

Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel: A preliminary report

International Nuclear Information System (INIS)

Ligotke, M.W.

1988-12-01

Tests of wind erosion were performed in a controlled-environment wind tunnel to support the development of natural-material protective barriers for long-term isolation of radioactive waste. Barrier performance standards currently being developed for internal and external barrier performance are expected to mandate a surface layer that is resistant to wind erosion. The purpose of this study was to initiate a series of tests to determine suitable soil and gravel mixtures for such a barrier and to test worst-case surface layer conditions under the influence of high wind speeds. Six mixed soil and gravel surfaces were prepared, weathered to represent natural wind-blown desert areas, and subjected to controlled wind erosion forces in a wind tunnel. The applied erosive forces, including surface shear forces, were characterized to provide a means of relating wind tunnel results with actual field conditions. Soil particle losses from the surfaces caused by suspension, saltation, and surface creep were monitored by aerosol sample probes and mass balance measurements. 23 refs., 22 figs., 3 tabs

Blown Away

Science.gov (United States)

Scott, Alan

2014-01-01

On Aug. 13, 2011, at 8:45 p.m. country music fans were eagerly awaiting the band Sugarland to make its entry onto the main stage at the Indiana State Fairgrounds. Also competing for the fans' attention was an approaching storm. Sugarland never made their entrance. At 8:49 p.m. the stage rigging was hit by 59 mile/h (94 km/h) winds causing it to…

Real‐Time Measurement of Wheel Performance on a Rover

Data.gov (United States)

National Aeronautics and Space Administration — Wind-blown sand on Mars produces a high risk of entrapment for Mars rovers. This was evident when the Mars Exploration Rover Spirit was immobilized in a wind blown...

Contribution of VSC-HVDC to Frequency Regulation of Power Systems With Offshore Wind Generation

DEFF Research Database (Denmark)

Liu, Hongzhi; Chen, Zhe

2015-01-01

to the onshore system grid through voltage-source converter-based–high voltage direct current (VSC-HVdc) transmission systems. Due to the decoupling of VSC-HVdc and signal transmission delay, offshore wind farms may not be able to respond to the onshore grid frequency excursion in time and, consequently......, the stability and security of the power system will be put at risk, especially for those with high wind penetration. This paper proposes a coordinated control scheme to allow VSC-HVdc link to contribute to the system frequency regulation by adjusting its dc-link voltage. By means of this approach, the dc...... capacitors of VSC-HVdc are controlled to absorb or release energy so as to provide frequency support. To further enhance the system frequency response, the frequency support from VSC-HVdc is also finely coordinated with that from offshore wind farm according to the latency of offshore wind farm responding...

Eficácia do Programa de Treinamento Auditivo em escolares com distúrbio de aprendizagem

OpenAIRE

Pinheiro, Fábio Henrique [UNESP

2009-01-01

O termo distúrbio de aprendizagem refere-se a um grupo heterogêneo de distúrbios, de origem neurológica, que se manifestam por dificuldades significativas na aquisição e no uso da compreensão oral, de fala, leitura e escrita, raciocínio e habilidades matemáticas. O transtorno do processamento auditivo refere-se especificamente à alteração de um ou mais mecanismos ou processos do sistema auditivo, responsáveis pelos fenômenos comportamentais relacionados à audição. O objetivo geral deste estud...

Blown by the wind: the ecology of male courtship display behavior in orchid bees.

Science.gov (United States)

Pokorny, Tamara; Vogler, Ira; Losch, René; Schlütting, Patrick; Juarez, Pedro; Bissantz, Nicolai; Ramírez, Santiago R; Eltz, Thomas

2017-04-01

Many insects rely on chemical signals to transmit precise information on the location, identity, and quality of potential mates. Chemical signals are often broadcasted at sites with physical properties that maximize signal propagation and signal transmission. Male neotropical orchid bees (Euglossini) perch and display on vertical branches and tree trunks in the forest to expose volatile blends (perfumes) that they previously collected from their environment. Previous studies have shown that the chemical composition of perfume blends is highly differentiated even between closely related species. However, variation in behavioral components of perfume exposure and male display remain poorly understood. We conducted a four-year study on orchid bee display sites (8 species) in pacific Costa Rica, using field observations along with chemical analysis and cage experiments to assess display niche partitioning among sympatric species. We evaluated the influence of physical factors (terrain, wind, light) on the distribution of perch sites and on display behavior, and tested a prediction of the sex pheromone-analogue hypothesis, i.e., that displaying males have above-average quantities or qualities of acquired perfumes. Males of different species displayed in the same general area and sometimes in close proximity to each other, but partitioned the display niche by selecting different perch diameters, display heights, and by displaying at different times of the day. Most perch sites were located inside the forest on elevated ground, especially along ridges, where stronger winds may help disperse perfume signals. Furthermore, the angular position of displaying males on perches was narrowly determined by wind direction, with males being positioned on the downwind side of the perch, where they would be most conspicuous to conspecifics approaching on an odor trail. Although our results generally support the hypothesis that perfumes serve as pheromone analogues, we did not find

Inovação pedagógica no Ensino Superior – o ensino a distância no ISCAP

OpenAIRE

Mesquita, Anabela; Peres, Paula

2014-01-01

O ensino a distância evoluiu muito desde o tempo em que o formando recebia os materiais por correspondência. Já nessa altura os formandos trabalhavam ao seu ritmo e concluíam a formação de acordo com o seu trabalho e agenda pessoal. Hoje, apesar dos cursos por correspondência ainda existirem, estão rapidamente a ser substituídos pela formação a distância. E este sucesso da educação a distância tem levado ao surgimento de ofertas diferentes e novos modelos de negócio. Existem diversas soluç...

Bio-Based Polyols from Seed Oils for Water-Blown Rigid Polyurethane Foam Preparation

Directory of Open Access Journals (Sweden)

Paweena Ekkaphan

2016-01-01

Full Text Available The preparation of water-blown rigid polyurethane (RPUR foams using bio-based polyols from sesame seed oil and pumpkin seed oil has been reported. Polyols synthesis involved two steps, namely, hydroxylation and alcoholysis reaction. FTIR, NMR, and ESI-MS were used to monitor the process of the synthesized polyols and their physicochemical properties were determined. The resulting polyols have OH number in the range of 340–351 mg KOH/g. RPUR foams blown with water were produced from the reaction of biopolyols with commercial polymeric methylene diphenyl diisocyanate (PMDI. The proper PUR formulations can be manipulated to produce the desired material applications. These seed oil-based RPUR foams exhibited relatively high compressive strength (237.7–240.2 kPa with the density in the range of 40–45 kg/m3. Additionally, the cell foam morphology investigated by scanning electron microscope indicated that their cellular structure presented mostly polygonal closed cells. The experimental results demonstrate that these bio-based polyols can be used as an alternative starting material for RPUR production.

Julgamento de colinearidade e percepção de distância exocêntrica em campo aberto

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Javier Enrique Santillán

2011-01-01

Full Text Available O propósito foi investigar experimentalmente o desempenho dos observadores numa original tarefa de julgamento de colinearidade em campo aberto (dimensões 20 x 30 m. Participaram do experimento 30 observadores. Os estímulos foram estacas verticais de alturas variáveis, quatro fixos e quatro móveis. A tarefa consistiu em ajustar os dois estímulos móveis (mediante controle à distância para que ficassem colineares aos dos estímulos fixos nos extremos de cada diagonal. Foi realizada uma análise de variância (ANOVA fatorial sobre os erros de colinearidade, revelando somente efeito significativo para o fator ‘Estímulo Móvel’ (F(3,473=69,86 p<0,001 notando-se uma sistemática na distribuição dos erros. As pequenas variações na distância exocêntrica percebida (com erros constantes dez vezes menores que os encontrados ao avaliar as distâncias egocêntricas e a relação dos erros cometidos com as distâncias egocêntricas indicariam que o marco de referência eliciado por esta tarefa de colinearidade, embora possa estar baseado nos indícios exocêntricos, é escalado por um fator egocêntrico.

The many sides of RCW 86: a Type Ia supernova remnant evolving in its progenitor's wind bubble

Science.gov (United States)

Broersen, Sjors; Chiotellis, Alexandros; Vink, Jacco; Bamba, Aya

2014-07-01

We present the results of a detailed investigation of the Galactic supernova remnant RCW 86 using the XMM-Newton X-ray telescope. RCW 86 is the probable remnant of SN 185 A.D., a supernova that likely exploded inside a wind-blown cavity. We use the XMM-Newton Reflection Grating Spectrometer to derive precise temperatures and ionization ages of the plasma, which are an indication of the interaction history of the remnant with the presumed cavity. We find that the spectra are well fitted by two non-equilibrium ionization models, which enables us to constrain the properties of the ejecta and interstellar matter plasma. Furthermore, we performed a principal component analysis on EPIC MOS and pn data to find regions with particular spectral properties. We present evidence that the shocked ejecta, emitting Fe K and Si line emission, are confined to a shell of approximately 2 pc width with an oblate spheroidal morphology. Using detailed hydrodynamical simulations, we show that general dynamical and emission properties at different portions of the remnant can be well reproduced by a Type Ia supernova that exploded in a non-spherically symmetric wind-blown cavity. We also show that this cavity can be created using general wind properties for a single degenerate system. Our data and simulations provide further evidence that RCW 86 is indeed the remnant of SN 185, and is the likely result of a Type Ia explosion of single degenerate origin.

Relação entre incontinência urinária em mulheres atletas corredoras de longa distância e distúrbio alimentar The relationship between urinary incontinence and eating disorders in female long-distance runners

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Maíta Poli de Araújo

2008-04-01

Full Text Available OBJETIVO: Avaliar a ocorrência de incontinência urinária (IU em atletas corredoras de longa distância e associá-la a presença ou não de distúrbios alimentares. MÉTODOS: Um total de 37 corredoras de longa distância completaram os questionários ¨International Consultation on Incontinence Questionnaire-Short Form¨ (ICIQ-SF e o ¨Eating Attitudes Test¨ (EAT-26. O teste do absorvente de uma hora foi realizado para quantificar a perda de urina. A análise estatística das variáveis contínuas foi feita pelo teste t pareado, ou teste de Mann-Whitney. RESULTADOS: 23 atletas (62,2% tinham queixa de perda de urina. A média dos escores do ICIQ-SF neste grupo foi de 4,03 ± 5,06. Houve diferença estatisticamente significante entre o valor do teste do absorvente (p=0,02 e o resultado do questionário EAT-26 (p=0,03 no grupo de atletas incontinentes. CONCLUSÃO: Encontramos IU em atletas corredoras de longa distância e houve correlação com distúrbios alimentar. Técnicos devem estar atentos para a ocorrência de eventuais distúrbios e encaminhar tais atletas para uma equipe multidisciplinar.BACKGROUND: To determine the prevalence of urinary incontinence in female long-distance runners and to compare it with the presence or not of eating disorders. Methods - A total of 37 women have completed the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF and the short version of the Eating Attitudes Test (EAT-26. A one-hour pad test was performed to determine urine loss. Mean values of continuous variables were compared using an independent sample t-test or the Mann-Whitney U test. RESULTS: 23 athletes (62.2% reported urine loss. The mean of the ICIQ-SF was 4.03 ± 5.06. There was a significant relation between the 1-hour pad test (p=0.02 and eating disorders (p=0.03. CONCLUSIONS: There was urinary incontinence in female long-distance runners and a correlation with eating disorders. Coaches should improve their knowledge

Solar Wind Charge Exchange Contribution To The ROSAT Sky Survey Maps

Science.gov (United States)

Uprety, Y.; Chiao, M.; Collier, M. R.; Cravens, T.; Galeazzi, M.; Koutroumpa, D.; Kuntz, K. D.; Lallement, R.; Lepri, S. T.; Liu, W.;

Review on fiber morphology obtained by bubble electrospinning and blown bubble spinning

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He Ji-Huan

2012-01-01

Full Text Available Here we show an intriguing phenomenon in the bubble electrospinning process that the ruptured film might be stripped upwards by an electronic force to form a very thin and long plate-like strip, which might been received in the metal receiver as discontinuous backbone-like wrinkled materials, rather than smooth nano-fibers or microspheres. The processes are called the bubble electrospinning. The electronic force can be replaced by a blowing air, and the process is called as the blown bubble spinning. We demonstrate that the size and thickness of the ruptured film are the crucial parameters that are necessary to understand the various observations including beads and nanoporous materials. We identify the conditions required for a ruptured film to form discontinuous structure, and a critical width of the ruptured film to form a cylindrical fiber, above which a long and thin plate-like strip might be obtained, and a criterion for oscillatory jet diameter, which leads to bead morphology of the obtained fibers. The space of the adjacent beads depends on the fiber size. We anticipate our assay to be a starting point for more sophisticated study of the bubble electrospinning and the blown bubble spinning and for mass-production of both nanofibers and nanoscale discontinuous materials.

Mixing Phenomena in a Bottom Blown Copper Smelter: A Water Model Study

Science.gov (United States)

Shui, Lang; Cui, Zhixiang; Ma, Xiaodong; Akbar Rhamdhani, M.; Nguyen, Anh; Zhao, Baojun

2015-03-01

The first commercial bottom blown oxygen copper smelting furnace has been installed and operated at Dongying Fangyuan Nonferrous Metals since 2008. Significant advantages have been demonstrated in this technology mainly due to its bottom blown oxygen-enriched gas. In this study, a scaled-down 1:12 model was set up to simulate the flow behavior for understanding the mixing phenomena in the furnace. A single lance was used in the present study for gas blowing to establish a reliable research technique and quantitative characterisation of the mixing behavior. Operating parameters such as horizontal distance from the blowing lance, detector depth, bath height, and gas flow rate were adjusted to investigate the mixing time under different conditions. It was found that when the horizontal distance between the lance and detector is within an effective stirring range, the mixing time decreases slightly with increasing the horizontal distance. Outside this range, the mixing time was found to increase with increasing the horizontal distance and it is more significant on the surface. The mixing time always decreases with increasing gas flow rate and bath height. An empirical relationship of mixing time as functions of gas flow rate and bath height has been established first time for the horizontal bottom blowing furnace.

Gamma rays from active regions in the galaxy: the possible contribution of stellar winds

International Nuclear Information System (INIS)

Cesarsky, C.J.; Montmerle, Thierry.

1982-08-01

Massive stars release a considerable amount of mechanical energy in the form of strong stellar winds. A fraction of this energy may be transferred to relativistic cosmic rays by diffusive shock acceleration at the wind boundary, and/or in the expanding, turbulent wind itself. Massive stars are most frequently found in OB associations, surrounded by H II regions lying at the edge of dense molecular clouds. The interaction of the freshly accelerated particles with matter gives rise to #betta#-ray emission. In this paper, we first briefly review the current knowledge on the energetics of strong stellar winds from O and Wolf-Rayet stars, as well as from T Tauri stars. Taking into account the finite lifetime of these stars, we then proceed to show that stellar winds dominate the energetics of OB associations during the first 4 to 6 million years, after which supernovae take over. In the solar neighborhood, the star formation rate is constant, and a steady-state situation prevails, in which the supernova contribution is found to be dominant. A small, but meaningful fraction of the CO S-B #betta#-ray sources may be fueled by WR and O stellar winds in OB associations, while the power released by T Tauri stars alone is perhaps insufficient to account for the #betta#-ray emission of nearby dark clouds. Finally, we discuss some controversial aspects of the physics of particle acceleration by stellar winds

Effect of land uses and wind direction on the contribution of local sources to airborne pollen.

Science.gov (United States)

Rojo, Jesús; Rapp, Ana; Lara, Beatriz; Fernández-González, Federico; Pérez-Badia, Rosa

2015-12-15

The interpretation of airborne pollen levels in cities based on the contribution of the surrounding flora and vegetation is a useful tool to estimate airborne allergen concentrations and, consequently, to determine the allergy risk for local residents. This study examined the pollen spectrum in a city in central Spain (Guadalajara) and analysed the vegetation landscape and land uses within a radius of 20km in an attempt to identify and locate the origin of airborne pollen and to determine the effect of meteorological variables on pollen emission and dispersal. The results showed that local wind direction was largely responsible for changes in the concentrations of different airborne pollen types. The land uses contributing most to airborne pollen counts were urban green spaces, though only 0.1% of the total surface area studied, and broadleaved forest which covered 5% of the study area. These two types of land use together accounted for 70% of the airborne pollen. Crops, scrubland and pastureland, though covering 80% of the total surface area, contributed only 18.6% to the total pollen count, and this contribution mainly consisted of pollen from Olea and herbaceous plants, including Poaceae, Urticaceae and Chenopodiaceae-Amaranthaceae. Pollen from ornamental species were mainly associated with easterly (Platanus), southerly (Cupressaceae) and westerly (Cupressaceae and Platanus) winds from the areas where the city's largest parks and gardens are located. Quercus pollen was mostly transported by winds blowing in from holm-oak stands on the eastern edge of the city. The highest Populus pollen counts were associated with easterly and westerly winds blowing in from areas containing rivers and streams. The airborne pollen counts generally rose with increasing temperature, solar radiation and hours of sunlight, all of which favour pollen release. In contrast, pollen counts declined with increased relative humidity and rainfall, which hinder airborne pollen transport

As políticas educacionais a distância em uma sociedade globalizada

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Miguel Alfredo Orth

2010-04-01

Full Text Available O presente artigo busca sistematizar a atuallegislação educacional do país na modalidadea distância em nível superior. Paratanto, caracterizamos, inicialmente, a sociedadeinformacional, global ou em redes,para na sequência, apresentar a legislaçãopertinente à modalidade a distância deeducação e, a partir desta, tecer algumasanálises. Entre essas análises, queremosdestacar aquela que evidencia as amarrasengendradas pelo modelo socioeconômicopolíticoe cultural do país e do mundoglobalizado, bem como a do rico diálogoque órgãos competentes do governo estãoestabelecendo com pesquisadores, educadores,instituições superiores de ensino esociedade civil no intuito de transpor as fronteirasdas atuais políticas públicas na área.

Hydrological Implications of Covering Wind-Blown Snow Accumulations with Geotextiles on Mount Aragats, Armenia

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Alexander Nestler

2014-07-01

Full Text Available Snow is an excellent water reservoir, naturally storing large quantities of water at time scales from a few days to several months. In summer-dry countries, like Armenia, runoff due to snow melt from mountain regions is highly important for a sustained water supply (irrigation, hydropower. Snow fields on Mount Aragats, Armenia’s highest peak, often persist until July, providing vital amounts of melt water. Artificially managing these wind-driven snow accumulations as a natural water reservoir might have considerable potential. In the context of the Swiss-Armenian joint venture, Freezwater, snow fields are covered with geotextiles in order to delay snow melt long enough to provide additional melt water in the dry season of the year. In this study, we analyze the hydrological effectiveness of the artificial management of the natural snow cover on Mount Aragats based on various field measurements acquired over a three-year period and numerical modeling. Over the winter season, partly more than five meter-thick snow deposits are formed supported by snow redistribution by strong wind. Repeated mappings of snow fields indicate that snow cover patterns remain highly consistent over time. Measurements of ablation below manually applied geotextiles show a considerable reduction of melt rates by more than 50%. Simulations with an energy-balance model and a distributed temperature-index model allow assessing the hydrological effect of artificial snow management for different initial snow depths and elevations and suggest that coverage is needed at a large scale in order to generate a significant impact on discharge.

A educação a distância no ensino superior e a lógica das competências

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Irene Jeanete Lemos Gilberto

2013-01-01

Full Text Available http://dx.doi.org/10.5007/1983-4535.2013v6n1p273 A expansão de cursos de licenciatura a distância tem gerado debates sobre a qualidade de ensino e a formação de professores. Os documentos oficiais que tratam da educação a distância, ao enfatizar a formação de qualidade, sinalizam que, na dinâmica pedagógica da educação a distância, o professor é um elemento imprescindível para o processo da aprendizagem e, como tal, precisa estar bem preparado, conhecer as tecnologias, sem limitar-se ao tecnicismo. O texto põe em discussão questões voltadas para a educação a distância, partindo do pressuposto de que, sendo a universidade o espaço livre da produção do conhecimento, torna-se fundamental compreender a educação a distância como prática social e política que possibilita o desenvolvimento da autonomia do educando. O trabalho aborda essas questões com base em resultado de pesquisa realizada com professores que atuam em cursos de licenciatura na modalidade a distância, e tem por objetivo trazer reflexões sobre a formação, que envolve a lógica das competências. Considerando a concepção nuclear de qualidade nos documentos oficiais, os resultados da pesquisa apontaram o redirecionamento dado pelos pesquisadores à questão das competências, dentro de uma perspectiva crítica que busca revitalizar a compreensão dos saberes nos processos de aprendizagem.

Educação a distância na internet: abordagens e contribuições dos ambientes digitais de aprendizagem

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Almeida Maria Elizabeth Bianconcini de

2003-01-01

Full Text Available Os avanços e a disseminação do uso das tecnologias de informação e comunicação (TIC descortinam novas perspectivas para a educação a distância com suporte em ambientes digitais de aprendizagem acessados via internet. Considerando-se que a distância geográfica e o uso de múltiplas mídias são características inerentes à educação a distância, mas não suficientes para definirem a concepção educacional, discute-se a educação a distância (EaD não como uma solução paliativa para atender alunos situados distantes geograficamente das instituições educacionais nem apenas como a simples transposição de conteúdos e métodos de ensino presencial para outros meios e com suporte em distintas tecnologias. Os programas de EaD podem ter o nível de diálogo priorizado ou não segundo a concepção epistemológica, tecnologias de suporte e respectiva abordagem pedagógica. Este artigo pretende discutir as abordagens usuais da educação a distância, destacando o uso das TIC para o desenvolvimento de um processo educacional interativo que propicia a produção de conhecimento individual e grupal em processos colaborativos favorecidos pelo uso de ambientes digitais e interativos de aprendizagem, os quais permitem romper com as distâncias espaço-temporais e viabilizam a recursividade, múltiplas interferências, conexões e trajetórias, não se restringindo à disseminação de informações e tarefas inteiramente definidas a priori.

Perspectivas da Educação a Distância no ensino da Matemática

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Renata Aparecida Pereira Teodoro

2016-02-01

Full Text Available Este artigo analisa a o ensino da Matemática por meio da Educação a Distância. O trabalho objetiva apresentar reflexões sobre a influência das novas tecnologias da informação e comunicação no ensino da Matemática. Faz-se uma análise acerca do cenário de autoformação e a acessibilidade presente na modalidade de ensino a distância, além de reflexões sobre o papel da tutoria no processo de formação do alunado. Consideraram-se aqui os atributos de versatilidade e flexibilidade da modalidade com aprendizagem focada no aluno. Observou-se a necessidade de atualização do perfil docente na busca de novas metodologias de aprendizagem e a interação com recursos e possibilidades tecnológicas, reforçando o potencial do ensino a distância em democratizar e oportunizar formação de qualidade e aprendizado efetivo a um público cada vez mais amplo.

Effect of land uses and wind direction on the contribution of local sources to airborne pollen

International Nuclear Information System (INIS)

Rojo, Jesús; Rapp, Ana; Lara, Beatriz; Fernández-González, Federico; Pérez-Badia, Rosa

2015-01-01

The interpretation of airborne pollen levels in cities based on the contribution of the surrounding flora and vegetation is a useful tool to estimate airborne allergen concentrations and, consequently, to determine the allergy risk for local residents. This study examined the pollen spectrum in a city in central Spain (Guadalajara) and analysed the vegetation landscape and land uses within a radius of 20 km in an attempt to identify and locate the origin of airborne pollen and to determine the effect of meteorological variables on pollen emission and dispersal. The results showed that local wind direction was largely responsible for changes in the concentrations of different airborne pollen types. The land uses contributing most to airborne pollen counts were urban green spaces, though only 0.1% of the total surface area studied, and broadleaved forest which covered 5% of the study area. These two types of land use together accounted for 70% of the airborne pollen. Crops, scrubland and pastureland, though covering 80% of the total surface area, contributed only 18.6% to the total pollen count, and this contribution mainly consisted of pollen from Olea and herbaceous plants, including Poaceae, Urticaceae and Chenopodiaceae–Amaranthaceae. Pollen from ornamental species were mainly associated with easterly (Platanus), southerly (Cupressaceae) and westerly (Cupressaceae and Platanus) winds from the areas where the city's largest parks and gardens are located. Quercus pollen was mostly transported by winds blowing in from holm-oak stands on the eastern edge of the city. The highest Populus pollen counts were associated with easterly and westerly winds blowing in from areas containing rivers and streams. The airborne pollen counts generally rose with increasing temperature, solar radiation and hours of sunlight, all of which favour pollen release. In contrast, pollen counts declined with increased relative humidity and rainfall, which hinder airborne pollen transport

Effect of land uses and wind direction on the contribution of local sources to airborne pollen

Energy Technology Data Exchange (ETDEWEB)

Rojo, Jesús; Rapp, Ana; Lara, Beatriz; Fernández-González, Federico; Pérez-Badia, Rosa

2015-12-15

The interpretation of airborne pollen levels in cities based on the contribution of the surrounding flora and vegetation is a useful tool to estimate airborne allergen concentrations and, consequently, to determine the allergy risk for local residents. This study examined the pollen spectrum in a city in central Spain (Guadalajara) and analysed the vegetation landscape and land uses within a radius of 20 km in an attempt to identify and locate the origin of airborne pollen and to determine the effect of meteorological variables on pollen emission and dispersal. The results showed that local wind direction was largely responsible for changes in the concentrations of different airborne pollen types. The land uses contributing most to airborne pollen counts were urban green spaces, though only 0.1% of the total surface area studied, and broadleaved forest which covered 5% of the study area. These two types of land use together accounted for 70% of the airborne pollen. Crops, scrubland and pastureland, though covering 80% of the total surface area, contributed only 18.6% to the total pollen count, and this contribution mainly consisted of pollen from Olea and herbaceous plants, including Poaceae, Urticaceae and Chenopodiaceae–Amaranthaceae. Pollen from ornamental species were mainly associated with easterly (Platanus), southerly (Cupressaceae) and westerly (Cupressaceae and Platanus) winds from the areas where the city's largest parks and gardens are located. Quercus pollen was mostly transported by winds blowing in from holm-oak stands on the eastern edge of the city. The highest Populus pollen counts were associated with easterly and westerly winds blowing in from areas containing rivers and streams. The airborne pollen counts generally rose with increasing temperature, solar radiation and hours of sunlight, all of which favour pollen release. In contrast, pollen counts declined with increased relative humidity and rainfall, which hinder airborne pollen

Wind erosion of waste impoundments in arid climates and mitigation of dust pollution.

Science.gov (United States)

Blight, G E

2008-12-01

Wind can erode and disperse fine-grained material from an impoundment of mining, industrial or municipal waste that stands above the level of its surroundings. Such dust dispersion can be a serious nuisance as well as a health hazard to inhabitants and animals in nearby settlements. It can also degrade crops, making them less marketable, and pollute soil, surface water and ground water. Wind can seasonally erode waste impoundments in all types of climate, but the erosion intensifies and persists for more of each year as regional aridity increases. As clouds of dust are often observed billowing across the top surfaces of waste impoundments in dry windy weather, there is a common misconception that dust arises from erosion of the top surface of an impoundment, resulting in much effort and money being misspent on top treatments when in fact the sloped sides of the impoundments are the true source of blown dust. This paper offers a brief review of general waste impoundment wind erosion issues and then focuses in more detail on the mechanics of how wind erodes surfaces of waste impoundments. Recommendations are offered for mitigating the effects of wind-eroded dust.

A genética dos distúrbios do sono na infância e adolescência

OpenAIRE

Nunes,Magda Lahorgue; Bruni,Oliviero

2008-01-01

OBJETIVO: O objetivo deste artigo é revisar a literatura sobre a genética dos distúrbios do sono na infância e adolescência. FONTES DOS DADOS: As palavras-chave "sono" e "genética" foram usadas para pesquisar por artigos publicados nos últimos cinco anos no banco de dados MEDLINE. A seguir, seus resumos foram analisados. A pesquisa também incluiu artigos clássicos, com a primeira descrição dos genes. SÍNTESE DOS DADOS: A recorrência familiar de muitos distúrbios do sono é um achado freqüente,...

Surface Length 3D: Plugin do OsiriX para cálculo da distância em superfícies

Directory of Open Access Journals (Sweden)

Alexandre Campos Moraes Amato

Full Text Available Resumo Softwares tradicionais de avaliação de imagens médicas, como DICOM, possuem diversas ferramentas para mensuração de distância, área e volume. Nenhuma delas permite medir distâncias entre pontos em superfícies. O menor trajeto entre pontos possibilita o cálculo entre óstios de vasos, como no caso de aneurismas aórticos, e a avaliação dos vasos viscerais para planejamento cirúrgico. O desenvolvimento de um plugin para OsiriX para mensuração de distâncias em superfícies mostrou-se factível. A validação da ferramenta ainda se faz necessária.

Panorama da educação à distância em enfermagem no Brasil

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Priscila Tagliaferro Rojo

2011-12-01

Full Text Available O desenvolvimento da educação à distância está associado à popularização e democratização do acesso às tecnologias de informação e de comunicação. A enfermagem vem se apropriando desta modalidade de ensino em seus cursos de graduação e pós-graduação, o que tem possibilitado conhecimento de novas tecnologias, facilidade de acesso, flexibilidade temporal e espacial e custos reduzidos. Objetivou-se realizar um mapeamento nacional de forma a identificar os cursos de ensino superior de enfermagem na modalidade educação à distância. Trata-se de um estudo exploratório descritivo, desenvolvido a partir de consultas a sites governamentais, não governamental e institucionais. Foram encontrados dois cursos de graduação e nove de pós-graduação oferecidos na área de enfermagem, o que é considerado um número ainda baixo, já que a educação à distância é uma ferramenta pedagógica adequada que permite a qualificação de grande contingente de enfermeiros que estão dispersos geograficamente e que não possuem acesso aos processos convencionais de ensino.

Educação a distância no ensino superior: expansão com qualidade?/Distance learning in higher education: expansion and quality?

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Francisco Paulo do Nascimento

2007-12-01

Full Text Available Este estudo objetivou investigar e analisar a necessidade de expansão da educação a distância no ensino superior, bem como a possibilidade de esse novo paradigma oferecer educação com a qualidade necessária para enfrentamento dos desafios de socialização do conhecimento. Foi elaborado por meio de pesquisa bibliográfica que alcançou contribuições teóricas sobre a relevância do conhecimento para o desenvolvimento mundial e de pessoas, educação, pesquisas sobre demanda e oferta de vagas no ensino superior, estudo comparativo entre ensino tradicional e ensino a distância, referenciais para educação a distância de qualidade, entrevistas em reportagens com professores e autoridades educacionais e relatos sobre experiências em aulas não presenciais. O trabalho indica que há demanda reprimida e crescente por vagas no ensino superior, que a infra-estrutura do País não é capaz de gerar a quantidade de vagas demandadas, e que o ensino a distância é capaz de ensejar educação de qualidade. The objective of this study was to examine and analyze the need to expanding distance learning in higher education, as well as the possibility of this new paradigm offering education with the necessary quality to face up the challenges of knowledge socialization. The study was developed through bibliographic research which reached theoretical contributions on the relevance of knowledge to world and people development, education, research on supply and demand of openings in higher education, comparative study between traditional and distance education, standards of distance education, interviews with professors and educational authorities and reports on docent experiences in non-presential classes. This study indicates that there is an unfulfilled and growing demand for openings in higher education, that our country’s infrastructure is not able to generate the urged amount of vacancies and that distance learning figures to be capable of

Evaluation of respirable particle matter in gold mine tailings on the Witwatersrand

International Nuclear Information System (INIS)

Ojelede, M.E.; Annegarn, H.J.

2007-01-01

Within the Witwatersrand gold mining area of South Africa, wind-blown dust is a significant contributor to atmospheric air pollution brought to the fore with the reworking of old mine tailings. Approximately 40,000 hectares are covered with tailings in the Witwatersrand. Wind-erosion during late austral winter and early spring causes surfaces of these tailings to be exposed, particularly during higher wind speeds and in the absence of rainfall. Local residents complain as the surrounding areas experience unpleasant dust episodes. As a result of urban PM 10 and PM 2.5 respirable particulate matter, increased respiratory ailments, morbidity and mortality, and concerns about the health impacts of wind-blown mine tailings in South Africa have been reported. Since 1981, significant monitoring of dustfall has taken place on the Witwatersrand, however, characterization of the respirable fraction of gold mine tailings material and dustfall is lacking. This paper presented the results of a study that established the content of respirable particulate matter in exposed mine tailings and wind-blown dust, and their likely contributions to ambient air. The initial results of the particulate size distribution of material samples from tailings and dust deposits collected in ambient dustfall-monitors were provided. Particle size distributions from different deposit types include slimes and sand deposits, surface and core material, and wind-winnowed secondary deposits. Fractions of PM 10 in source and deposited material were also discussed. It was concluded that there was a significant fraction of PM 10 material in the mine tailings, and that further work to quantify the population exposure risk is needed. 11 refs., 1 tab., 6 figs

Wind Vision: A New Era for Wind Power in the United States

Energy Technology Data Exchange (ETDEWEB)

U.S. Department of Energy

2015-03-12

With more than 4.5% of the nation's electricity supplied by wind energy today, the Department of Energy has collaborated with industry, environmental organizations, academic institutions, and national laboratories to develop a renewed Wind Vision, documenting the contributions of wind to date and envisioning a future where wind continues to provide key contributions to the nation’s energy portfolio. Building on and updating the 2008 20% Wind Energy by 2030 report, the new Wind Vision Report quantifies the economic, environmental, and social benefits of a robust wind energy future and the actions that wind stakeholders can take to make it a reality.

Ocorrência de Distúrbios Fisiológicos em Manga, var. Tommy Atkins

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V.R. SAMPAIO

1998-01-01

Full Text Available Procurou-se determinar os fatores da relação planta/ambiente que predispõem frutos da variedade de manga Tommy Atkins a apresentarem distúrbios fisiológicos. Para isso, foram analisados os posicionamentos dos frutos na planta, estádios de maturação e a relação vigor do ramo/fruto. As avaliações permitiram concluir que: a o posicionamento dos frutos na planta não tem influência alguma na ocorrência das desordens fisiológicas; b existe certa relação entre vigor dos ramos e a presença dos distúrbios nos frutos; c o percentual de ocorrência dos distúrbios fisiológicos é altamente influenciado pelo estádio de maturação do fruto à colheita, sendo que, é de pequena monta em frutos colhidos precocemente.Factors of the relation plant/environment which predispose mangoe fruits, var. Tommy Atkins, to physiological disorders were determined. Therefore, fruit location in the plant, the degree of ripeness and the relation of vigor between branch/fruit were analysed. The results allowed the following conclusions: a the fruit positioning in the plant has no influence on the occurence of physiological disorders; b there is a certain relation between vigor of the branch and the presence of disorders in the fruit; c the percentage of occurrence of physiological disorders is a function of the fruit ripeness degree at harvest time, being very small when the fruit is harvested early.

PLA and single component silicone rubber blends for sub-zero temperature blown film packaging applications

Science.gov (United States)

Meekum, Utai; Khiansanoi, Apichart

2018-06-01

The poly(lactic acid) (PLA) blend with single component silicone rubber in the presence of reactive amino silane coupling agent and polyester polyols plasticizer were studied. The manufacturing of film packaging for sub-zero temperature applications from the PLA blend was the main objective. The mechanical properties, especially the impact strengths, of PLA/silicone blends were significantly depended on the silicone loading. The outstanding impact strengths, tested at sub-zero temperature, of the blend having silicone content of 8.0 phr was achieved. It was chosen as the best candidate for the processability improvement. Adding the talc filler into the PLA/silicone blend to enhance the rheological properties was investigated. The ductility of the talc filled blends were decreased with increasing the filler contents. However, the shear viscosity of the blend was raised with talc loading. The blend loaded with 40 phr of talc filler was justified as the optimal formula for the blown film process testing and it was successfully performed with a few difficulties. The obtained blown film showed relative good flexibility in comparison with LDPE but it has low transparency.

Estimation of wind erosion from construction of a railway in arid Northwest China

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Benli Liu

2017-06-01

Full Text Available A state-of-the-art wind erosion simulation model, the Wind Erosion Prediction System and the United States Environmental Protection Agency's AP 42 emission factors formula, were combined together to evaluate wind-blown dust emissions from various construction units from a railway construction project in the dry Gobi land in Northwest China. The influence of the climatic factors: temperature, precipitation, wind speed and direction, soil condition, protective measures, and construction disturbance were taken into account. Driven by daily and sub-daily climate data and using specific detailed management files, the process-based WEPS model was able to express the beginning, active, and ending phases of construction, as well as the degree of disturbance for the entire scope of a construction project. The Lanzhou-Xinjiang High-speed Railway was selected as a representative study because of the diversities of different climates, soil, and working schedule conditions that could be analyzed. Wind erosion from different working units included the building of roadbeds, bridges, plants, temporary houses, earth spoil and barrow pit areas, and vehicle transportation were calculated. The total wind erosion emissions, 7406 t, for the first construction area of section LXS-15 with a 14.877 km length was obtained for quantitative analysis. The method used is applicable for evaluating wind erosion from other complex surface disturbance projects.

Mechanical behavior and essential work of fracture of starch-based blown films

Science.gov (United States)

Nottez, M.; Chaki, S.; Soulestin, J.; Lacrampe, M. F.; Krawczak, P.

2015-05-01

A fracture mechanics approach (Essential Work of Fracture, EWF) was applied to assess the toughness of novel partly starch-grafted polyolefin blown films, compared to that of a neat polyethylene reference. Tests were performed on double-end notched samples. The digital image correlation method was used to monitor the deformation field around the notch. Regular tensile and tear tests were also carried out. The specific essential work of fracture is a characteristic which is much more sensitive to materials structural modifications than the tensile or tear properties.

Evaluation of chemical stabilizers and windscreens for wind erosion control of uranium mill tailings

International Nuclear Information System (INIS)

Elmore, M.R.; Hartley, J.N.

1984-08-01

Potential wind erosion of uranium mill tailings is a concern for the surface disposal of tailings at uranium mills. Wind-blown tailings may subsequently be redeposited on areas outside the impoundment. Pacific Northwest Laboratory (PNL) is investigating techniques for fugitive dust control at uranium mill tailings piles. Laboratory tests, including wind tunnel studies, were conducted to evaluate the relative effectiveness of 43 chemical stabilizers. Seventeen of the more promising stabilizers were applied to test plots on a uranium tailings pile at the American Nuclear Corporation-Gas Hills Project mill site in central Wyoming. The durabilities of these materials under actual site conditions were evaluated over time. In addition, field testing of commercially available windscreens was conducted. Test panels were constructed of eight different materials at the Wyoming test site to compare their durability. A second test site was established near PNL to evaluate the effectiveness of windscreens at reducing wind velocity, and thereby reduce the potential for wind erosion of mill tailings. Results of the laboratory land field tests of the chemical stabilizers and windscreens are presented, along with costs versus effectiveness of these techniques for control of wind erosion at mill tailings piles. 12 references, 4 figures, 6 tables

Educação a distância na ótica discente

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Simone de Souza

2016-03-01

Full Text Available Resumo Este artigo apresenta parte das reflexões desenvolvidas durante uma pesquisa de doutorado que buscou respostas à questão: o que revelam os discursos de estudantes veteranos dos cursos de licenciatura em física e em pedagogia da Universidade Estadual de Maringá, Paraná, a respeito da modalidade de educação a distância e, mais especificamente, dos elementos constitutivos de cada curso? Para tanto, vinte e seis acadêmicos concederam entrevistas, que foram gravadas em áudio, transcritas e compreendidas segundo a teoria da Análise do Discurso de linha francesa, o que permitiu desvelar os sentidos que emanaram dos dizeres dos participantes da pesquisa, sem pretensão de generalizações. O objetivo foi compreender os discursos de estudantes quanto às suas experiências pessoais em cursos de graduação, na modalidade a distância, nos âmbitos estrutural, organizacional e pedagógico. Do resultado das análises, destacaram-se: a forte influência das imagens construídas ao longo da história pela escolarização na modalidade presencial; a facilidade de acesso ao ensino superior via educação a distância (EaD e sua adequação às condições de vida dos alunos; a preferência dos estudantes pelo livro impresso e pelas videoaulas como suportes à aprendizagem; as resistências, as falhas técnicas e o uso limitado das tecnologias de informação e comunicação (TIC como mediadores do processo de ensino e de aprendizagem; a presença de fragilidades no processo de comunicação entre tutores e alunos.

A genética dos distúrbios do sono na infância e adolescência The genetics of sleep disorders in childhood and adolescence

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Magda Lahorgue Nunes

2008-08-01

Full Text Available OBJETIVO: O objetivo deste artigo é revisar a literatura sobre a genética dos distúrbios do sono na infância e adolescência. FONTES DOS DADOS: As palavras-chave "sono" e "genética" foram usadas para pesquisar por artigos publicados nos últimos cinco anos no banco de dados MEDLINE. A seguir, seus resumos foram analisados. A pesquisa também incluiu artigos clássicos, com a primeira descrição dos genes. SÍNTESE DOS DADOS: A recorrência familiar de muitos distúrbios do sono é um achado freqüente, mas loci genéticos foram descobertos para poucos deles. Descrevemos aqui distúrbios do sono transmitidos por herança genética e também aqueles que apresentam altos índices de recorrência familiar, apesar de nenhum gene específico haver sido encontrado. CONCLUSÕES: Apesar da maioria dos distúrbios do sono ainda não terem uma base molecular identificada, técnicas modernas são cada vez mais utilizadas para determinar a contribuição dos genes ao sono e aos seus distúrbios associados. A importância clínica destas descobertas pode estar relacionada com a melhoria de métodos diagnósticos, mas também como alvo para o desenvolvimento de medicações específicas.OBJECTIVE: To review the literature regarding the genetics of sleep disorders in childhood and adolescence. SOURCES: Articles published in the past 5 years were searched on MEDLINE using the keywords sleep and genetics. Abstracts were then analyzed. Classical articles with the first description of genes were also included. SUMMARY OF THE FINDINGS: We often find familial recurrence in many sleep disorders. However, gene loci were discovered for only a few of them. We describe sleep disorders transmitted by genetic heritance and also those in that, although a gene was not found, familial recurrence is high. CONCLUSION: Although most of the sleep disorders do not have by now an identified molecular basis, modern techniques are being increasingly applied to determine the

High melt strength, tear resistant blown film based on poly(lactic acid)

Science.gov (United States)

Edmonds, Neil R.; Plimmer, Peter N.; Tanner, Chris

2015-05-01

A major problem associated with the commercial manufacture of thin films from PLA is inferior processing characteristics on blown film lines compared to low density polyethylene. PLA has poor melt strength (leading to bubble instability) and develops a permanent crease in the flattened film as it exits the tower of the film line. In addition, the thin film product has poor tear strength and an unacceptable `noise' level when converted into flexible packaging. Furthermore, fabricated articles based on PLA are known to show an unattractive tendency toward dimensional instability. This behaviour is associated with `cold crystallization', a phenomenon which also causes exudation of any plasticizer added for improving flexibility. Blow moulded articles based on PLA also exhibit dimensional sensitivity above 60°C. All of these issues have been overcome by the technology described in this paper. This has been accomplished without loss of the valuable compostability characteristic of PLA; this was confirmed by evaluation of film in a commercial composting operation. These results have been achieved through novel reactive compounding technology which: (a) Creates a PLA-rich structure containing long chain crosslinks, (b) generates a low glass transition temperature phase covalently bonded to the PLA structure, and (c) provides a material which performs like LDPE in a blown film manufacturing operation. The technology developed is covered by NZ Patent 580231 (3). The patent is held by UniServices Ltd, The University of Auckland, New Zealand.

Educação superior a distância no Brasil: uma construção consorciada e em rede

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Luiz Roberto Rodrigues Martins

2006-03-01

Full Text Available Este artigo descreve a experiência de implantação da política de fomento aos cursos de Graduação a Distância (EAD no Brasil adotada pela Secretaria de Educação a Distância do Ministério da Educação (SEED/MEC a partir de 2004. Essa política prioriza a criação de cursos de licenciatura e a distância. Analisaremos essa experiência pioneira e ainda não consolidada, buscando interpretar os fatores que dificultam a institucionalização da EAD no ensino superior. Nesse trabalho analisaremos algumas alternativas de institucionalização apresentadas pelos oito consórcios participantes da Chamada Pública 001/2004 SEED/MEC na reunião de trabalho realizada em abril de 2005. As proposições dos consórcios, encaminhadas ao MEC pela UniRede, pretendem assegurar a continuidade da política pública de fomento à EAD no ensino superior público, garantindo a continuidade dos cursos oferecidos e a ampliação de vagas nos próximos anos. Palavras-chave: Políticas públicas, educação a distância, institucionalização da EAD.

Determination of the effect of wind velocity and direction changes on turbidity removal in rectangular sedimentation tanks.

Science.gov (United States)

Khezri, Seyed Mostafa; Biati, Aida; Erfani, Zeynab

2012-01-01

In the present study, a pilot-scale sedimentation tank was used to determine the effect of wind velocity and direction on the removal efficiency of particles. For this purpose, a 1:20 scale pilot simulated according to Frude law. First, the actual efficiency of total suspended solids (TSS) removal was calculated in no wind condition. Then, the wind was blown in the same and the opposite directions of water flow. At each direction TSS removal was calculated at three different velocities from 2.5 to 7 m/s. Results showed that when the wind was in the opposite direction of water flow, TSS removal efficiency initially increased with the increase of wind velocity from 0 to 2.5 m/s, then it decreased with the increase of velocity to 5 m/s. This mainly might happen because the opposite direction of wind can increase particles' retention time in the sedimentation tank. However, higher wind velocities (i.e. 3.5 and 5.5 m/s) could not increase TSS removal efficiency. Thus, if sedimentation tanks are appropriately exposed to the wind, TSS removal efficiency increases by approximately 6%. Therefore, energy consumption will be reduced by a proper site selection for sedimentation tank unit in water and waste water treatment plants.

Um Enfoque Empreendedor Para a Educação à Distância - LED/UFSC

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Anderson Antônio Mattos Martins

2002-03-01

Full Text Available O presente artigo tem por finalidade apontar, dentre as novas modalidades de ensino, a Educação a Distância (EAD como melhor alternativa para o mercado de trabalho cada vez mais sofisticado e globalizado, já que é concebida como uma construção criativa e reflexiva que propicia a democratização educacional. Inicialmente são analisados alguns aspectos da sociedade contemporânea em cujo contexto a educação passa por adaptabilidades em função das modernas formas de comunicação eletrônica, entre outras. Em seguida, fazem-se reflexões sobre EAD, Empreendedorismo e Competências, resgatando origem e conceitos. Também apresenta-se o Laboratório de Ensino a Distância (LED que desenvolve estratégias e metodologias de EAD em ambientes multimídias integrados por redes de comunicação. Por fim, considera-se um novo caminho para a educação: a EAD que possibilita o atendimento às expectativas do mundo do trabalho, através da adoção de currículos relevantes, flexíveis e adaptados às exigências sociais e individuais. PALAVRAS-CHAVE: Educação a Distância, Empreendedorismo, Competências

Computational Fluid Dynamics (CFD) Investigation of Submerged Combustion Behavior in a Tuyere Blown Slag-fuming Furnace

Science.gov (United States)

Huda, Nazmul; Naser, Jamal; Brooks, G. A.; Reuter, M. A.; Matusewicz, R. W.

2012-10-01

A thin-slice computational fluid dynamics (CFD) model of a conventional tuyere blown slag-fuming furnace has been developed in Eulerian multiphase flow approach by employing a three-dimensional (3-D) hybrid unstructured orthographic grid system. The model considers a thin slice of the conventional tuyere blown slag-fuming furnace to investigate details of fluid flow, submerged coal combustion dynamics, coal use behavior, jet penetration behavior, bath interaction conditions, and generation of turbulence in the bath. The model was developed by coupling the CFD with the kinetics equations developed by Richards et al. for a zinc-fuming furnace. The model integrates submerged coal combustion at the tuyere tip and chemical reactions with the heat, mass, and momentum interfacial interaction between the phases present in the system. A commercial CFD package AVL Fire 2009.2 (AVL, Graz, Austria) coupled with several user-defined subroutines in FORTRAN programming language were used to develop the model. The model predicted the velocity, temperature field of the molten slag bath, generated turbulence and vortex, and coal use behavior from the slag bath. The tuyere jet penetration length ( l P) was compared with the equation provided by Hoefele and Brimacombe from isothermal experimental work ( {{l_{{P}} }/{d_{o }} = 10.7( {N^' }_{Fr} } )^{0.46} ( {ρ_{{g}} /ρl } )^{0.35} } ) and found 2.26 times higher, which can be attributed to coal combustion and gas expansion at a high temperature. The jet expansion angle measured for the slag system studied is 85 deg for the specific inlet conditions during the simulation time studied. The highest coal penetration distance was found to be l/L = 0.2, where l is the distance from the tuyere tip along the center line and L is the total length (2.44 m) of the modeled furnace. The model also predicted that 10 pct of the injected coal bypasses the tuyere gas stream uncombusted and carried to the free surface by the tuyere gas stream, which

Theoretical contributions to solar wind research - a review

International Nuclear Information System (INIS)

Cuperman, S.

1977-01-01

The theoretical work on the solar wind phenomena done since 1958 can be divided into two main parts: Part I - development and refinement of Parker's initial macroscopic model, the emphasis being placed upon steady state, spherically symmetric flow and the identification of the structure-less background solar wind plasma with the low speed flow. It is in this part that much progress in understanding the solar wind phenomenon has been achieved; Part II - generalization of Parker's initial model such as to include microscopic (kinetic) aspects, temporal variations, deviations from spherically symmetric conditions, complex local magnetic configurations, etc. The last two aspects, in particular, have received considerable attention with the discovery of the coronal holes, their association with high-speed flows and the tentative identification of these flows with the structure-less background solar wind plasma. This review is confined to Part I, as defined above. However, for completeness, several important aspects connected with the subjects enumerated under Part II and which represent the objects of the most recent investigation are also briefly reviewed. (Auth.)

Effects of wind and simulated acid mist on leaf cuticles

International Nuclear Information System (INIS)

Hoad, S.P.; Jeffree, C.E.; Grace, J.

1994-01-01

The combined effect of wind and simulated acid mist on leaf cuticles was investigated in beech (Fagus sylvatica L.) and birch (Betula pubescens Ehr.). Macroscopic and microscopic features of wind damage are described. Visibly damaged leaf area and the numbers of microscopic cuticular lesions were measured. The cuticular conductance to water vapour (g c ) of the astomatous adaxial surfaces of the leaves was measured by a gravimetric method. Field experimenntal sites were selected to provide either: 1. Direct wind action on widely-spaced plants caused by high speed and impaction of wind-blown particles, but with minimal mutual leaf abrasion 2. Indirect wind action via a high degree of mutual abrasion between closely-spaced plants. Direct wind action increased water loss via the leaf adaxial cuticle two- to three-fold in each species, by increasing the numbers of microscopic cuticular lesions. Indirect wind action caused more visible damage to leaves than direct wind action, increased g c by about threefold compared with complete shelter, and induced the most cuticular lesions. Acid mists at pH 3 or pH 5 were applied to the plants in situ at weekly intervals over a 100-day period. In sheltered plants, no effect of acid mist was detected on visibly damaged leaf area, the numbers of microscopic cuticular lesions, or on g c . However, acid mists in combination with wind exposure caused significant effects on cuticular integrity that were dependent on the type of wind action. Direct wind action combined with pH 3 acid mist resulted in the largest numbers of microscopic cuticular lesions, and the highest g c . By contrast, indirect wind action combined with pH 3 acid mist caused most visible damage to leaf tissue, but fewer microscopic lesions, and lower g c , than in plants treated with water mist. In severely-abraded leaves exposed to indirect wind action and low-pH acid rain, g c may be reduced by wound-isolation of blocks of non-functional leaf tissue. (orig.)

InfraSound from wind turbines : observations from Castle River wind farm. Volume 1

International Nuclear Information System (INIS)

Edworthy, J.; Hepburn, H.

2005-01-01

Although infrasound has been discussed as a concern by groups opposed to wind farm facilities, there is very little information available about infrasound and wind turbines. This paper presented details of a project conducted by VisionQuest, the largest wind power producer in Canada. Three sensor types were used: precision sound analyzer, seismic geophones, and calibrated microphones to take measurements in low, medium and high winds. The project also measured infrasound when the wind farm was not operating. Acquisition geometry was presented, as well as details of apparent attenuations of wind noise. It was noted that high wind noise was a dominant factor and that there was little difference when the wind farm was not operational. It was suggested that turbines have no impact with high wind, since wind noise is not attenuated with distance. It was noted that increased geophone amplitudes indicate high wind coupled motion which is attenuated when the turbines are on. Results indicate that all frequencies showed attenuation with distance. Evidence showed that low frequency sound pressure levels were often lower when the turbines were switched on. Where turbines contributed to sound pressure levels, the magnitude of the contribution was below levels of concern to human health. Ambient sound pressure levels were much higher than contributions from wind turbines. It was concluded that wind itself generates infrasound. Wind turbines generate low levels of infrasound, detectable very close to facilities at low to medium wind speeds. Wind turbines may reduce ambient infrasound levels at high wind speeds by converting the energy from the wind into electricity. refs., tabs., figs

Uso das TICs na Educação Superior presencial e a distância: a visão dos professores

Directory of Open Access Journals (Sweden)

Mathias, Carmen V.

2011-01-01

Full Text Available As tecnologias possuem um potencial formativo que pode contribui para ampliação dos espaços e dos tempos pedagógicos, para a flexibilização do currículo e para o aumento da interação entre os sujeitos tanto na educação presencial quanto na educação a distância. A partir dessa premissa, objetivamos investigar como ocorre o uso das TICs aplicadas a educação superior presencial e a distância sob o ponto de vista dos professores universitários. O trabalho teve uma abordagem qualitativa, os dados foram coletados por um questionário online aplicado a vinte e dois professores atuantes na educação superior presencial e a distância. As informações foram trabalhadas através da análise de conteúdo. Alguns resultados: todos os professores utilizam TICs, alguns de forma mais freqüente e diversificada; algumas tecnologias são mais utilizadas na educação presencial, outras na educação a distância; a maioria dos professores possui formação para o uso das TICs; foi significativo o indicativo da falta de formação para os professores usarem de maneira adequada as tecnologias; a maioria dos professores reconheceu a existência de diferenças no uso das tecnologias na educação presencial e a distância; os professores apontam muitas vantagens para o uso das tecnologias aplicadas a educação e reconhecem algumas desvantagens

Aerodynamic excitation and sound production of blown-closed free reeds without acoustic coupling: The example of the accordion reed

Science.gov (United States)

Ricot, Denis; Caussé, René; Misdariis, Nicolas

2005-04-01

The accordion reed is an example of a blown-closed free reed. Unlike most oscillating valves in wind musical instruments, self-sustained oscillations occur without acoustic coupling. Flow visualizations and measurements in water show that the flow can be supposed incompressible and potential. A model is developed and the solution is calculated in the time domain. The excitation force is found to be associated with the inertial load of the unsteady flow through the reed gaps. Inertial effect leads to velocity fluctuations in the reed opening and then to an unsteady Bernoulli force. A pressure component generated by the local reciprocal air movement around the reed is added to the modeled aerodynamic excitation pressure. Since the model is two-dimensional, only qualitative comparisons with air flow measurements are possible. The agreement between the simulated pressure waveforms and measured pressure in the very near-field of the reed is reasonable. In addition, an aeroacoustic model using the permeable Ffowcs Williams-Hawkings integral method is presented. The integral expressions of the far-field acoustic pressure are also computed in the time domain. In agreement with experimental data, the sound is found to be dominated by the dipolar source associated by the strong momentum fluctuations of the flow through the reed gaps. .

TWO REGIMES OF INTERACTION OF A HOT JUPITER’S ESCAPING ATMOSPHERE WITH THE STELLAR WIND AND GENERATION OF ENERGIZED ATOMIC HYDROGEN CORONA

Energy Technology Data Exchange (ETDEWEB)

Shaikhislamov, I. F.; Prokopov, P. A.; Berezutsky, A. G.; Zakharov, Yu. P.; Posukh, V. G. [Institute of Laser Physics SB RAS, Novosibirsk (Russian Federation); Khodachenko, M. L.; Lammer, H.; Kislyakova, K. G.; Fossati, L. [Space Research Institute, Austrian Acad. Sci., Graz (Austria); Johnstone, C. P., E-mail: maxim.khodachenko@oeaw.ac.at [Department of Astrophysics, University of Vienna, Vienna (Austria)

2016-12-01

The interaction of escaping the upper atmosphere of a hydrogen-rich non-magnetized analog of HD 209458b with a stellar wind (SW) of its host G-type star at different orbital distances is simulated with a 2D axisymmetric multi-fluid hydrodynamic (HD) model. A realistic Sun-like spectrum of X-ray and ultraviolet radiation, which ionizes and heats the planetary atmosphere, together with hydrogen photochemistry, as well as stellar-planetary tidal interaction are taken into account to generate self-consistently an atmospheric HD outflow. Two different regimes of the planetary and SW interaction have been modeled. These are: (1) the “ captured by the star ” regime, when the tidal force and pressure gradient drive the planetary material beyond the Roche lobe toward the star, and (2) the “ blown by the wind ” regime, when sufficiently strong SW confines the escaping planetary atmosphere and channels it into the tail. The model simulates in detail the HD interaction between the planetary atoms, protons and the SW, as well as the production of energetic neutral atoms (ENAs) around the planet due to charge exchange between planetary atoms and stellar protons. The revealed location and shape of the ENA cloud, either as a paraboloid shell between the ionopause and bowshock (for the “ blown by the wind ” regime), or a turbulent layer at the contact boundary between the planetary stream and SW (for the “ captured by the star ” regime) are of importance for the interpretation of Ly α absorption features in exoplanetary transit spectra and characterization of the plasma environments.

TWO REGIMES OF INTERACTION OF A HOT JUPITER’S ESCAPING ATMOSPHERE WITH THE STELLAR WIND AND GENERATION OF ENERGIZED ATOMIC HYDROGEN CORONA

International Nuclear Information System (INIS)

Shaikhislamov, I. F.; Prokopov, P. A.; Berezutsky, A. G.; Zakharov, Yu. P.; Posukh, V. G.; Khodachenko, M. L.; Lammer, H.; Kislyakova, K. G.; Fossati, L.; Johnstone, C. P.

2016-01-01

The interaction of escaping the upper atmosphere of a hydrogen-rich non-magnetized analog of HD 209458b with a stellar wind (SW) of its host G-type star at different orbital distances is simulated with a 2D axisymmetric multi-fluid hydrodynamic (HD) model. A realistic Sun-like spectrum of X-ray and ultraviolet radiation, which ionizes and heats the planetary atmosphere, together with hydrogen photochemistry, as well as stellar-planetary tidal interaction are taken into account to generate self-consistently an atmospheric HD outflow. Two different regimes of the planetary and SW interaction have been modeled. These are: (1) the “ captured by the star ” regime, when the tidal force and pressure gradient drive the planetary material beyond the Roche lobe toward the star, and (2) the “ blown by the wind ” regime, when sufficiently strong SW confines the escaping planetary atmosphere and channels it into the tail. The model simulates in detail the HD interaction between the planetary atoms, protons and the SW, as well as the production of energetic neutral atoms (ENAs) around the planet due to charge exchange between planetary atoms and stellar protons. The revealed location and shape of the ENA cloud, either as a paraboloid shell between the ionopause and bowshock (for the “ blown by the wind ” regime), or a turbulent layer at the contact boundary between the planetary stream and SW (for the “ captured by the star ” regime) are of importance for the interpretation of Ly α absorption features in exoplanetary transit spectra and characterization of the plasma environments.

Curso de Geografia à distância: considerações sobre a atuação da tutoria

Directory of Open Access Journals (Sweden)

Aldênia Oliveira Mendes Dias

2015-06-01

Full Text Available A Educação a Distância é uma modalidade com um importante papel de democratizar o ensino e separar o conectado do não conectado, o marginalizado do incluído, enfim, visibilizar as diferenças, utilizando as tecnologias da comunicação. Essa ideia se fortalece com a crença de que os meios virtuais de aprendizagem substituem o professor. No ensino a distância, quando o professor não se envolve nas interações com os alunos, cabe ao docente tutor fazê-lo. O docente tutor aproxima o aluno dos conteúdos do curso ministrado e do próprio “conteúdo tecnológico”, necessário ao trânsito autônomo em ambientes virtuais de aprendizagem. Este estudo foi conduzido numa abordagem qualitativa, exploratória e descritiva, relacionando a tutoria com o ensino da geografia. A metodologia adotada segue os parâmetros da pesquisa bibliográfica, com foco nas relações entre a tecnologia e o ensino de Geografia. Os objetivos deste trabalho são: conhecer o papel e a importância do docente tutor à distância no processo ensino-aprendizagem; apontar as múltiplas funções do docente tutor à distância no curso de geografia e o seu papel no curso e identificar os desafios e possibilidades do trabalho do tutor na EAD. Este estudo vem possibilitar a atuação do docente tutor da área de Geografia para a mediação do conhecimento por meio da plataforma Virtualmontes, na internet.

Simple passive methods for the assessment of the directional and vertical distributions of wind-blown particulates

International Nuclear Information System (INIS)

Orza, J. A.G.; Cabello, M.; Mateo, J.

2009-01-01

We have designed and tested two types of passive collectors to study aeolian erosion in the field. The first passive sampler is a sticky pad that allows for directional particulate assessment by an automatic particle counting procedure. the second one features an omni-directional capture opening, and mass of retained particles is gravimetric ally quantified. Vertical arrays of these passive collectors have been constructed to obtain vertical profiles of the horizontal particle flux as a function of soil properties, nearby sources and wind speed. We present some first results from field campaigns. (Author) 3 refs.

DTU contributions to IEA Wind Annex 25 Phase 2

DEFF Research Database (Denmark)

Sørensen, Poul Ejnar; Cutululis, Nicolaos Antonio; Meibom, Peter

The objective of Task 25 is to analyse and further develop the methodology to assess the impact of wind power on power systems. The Task has established an international forum for exchange of knowledge and experiences related to power system operation with large amounts of wind power and has...... and design, mainly: balancing, grid impacts and capacity credit of wind power. In the meetings, all participants have made presentations of the wind integration issues in their country, results so far and on-going activities. In the latest meetings presentations have been grouped to different topics...... actively followed parallel activities with Transmission System Operators other R&D Task work. The participants have collected and shared information on the experience gained and the studies made up to and during the task. The case studies have addressed different aspects of power system operation...

Model of wind shear conditional on turbulence and its impact on wind turbine loads

DEFF Research Database (Denmark)

Dimitrov, Nikolay Krasimirov; Natarajan, Anand; Kelly, Mark C.

2015-01-01

proposed for flat terrain and that can significantly decrease the uncertainty associated with fatigue load predictions for wind turbines with large rotors. An essential contribution is the conditioning of wind shear on the 90% quantile of wind turbulence, such that the appropriate magnitude of the design...... fatigue load is achieved. The proposed wind shear model based on the wind measurements is thereby probabilistic in definition, with shear jointly distributed with wind turbulence. A simplified model for the wind shear exponent is further derived from the full stochastic model. The fatigue loads over...... is most pronounced on the blade flap loads. It is further shown that under moderate wind turbulence, the wind shear exponents may be over-specified in the design standards, and a reduction of wind shear exponent based on the present measurements can contribute to reduced fatigue damage equivalent loads...

Distância interincisiva máxima em crianças respiradoras bucais Maximum interincisal distance in mouth breathing children

Directory of Open Access Journals (Sweden)

Débora Martins Cattoni

2009-12-01

Full Text Available INTRODUÇÃO: a distância interincisiva máxima é um importante aspecto na avaliação miofuncional orofacial, pois distúrbios miofuncionais orofaciais podem limitar a abertura da boca. OBJETIVO: mensurar a distância interincisiva máxima de crianças respiradoras bucais, relacionando-a com a idade, e comparar as médias dessas medidas com as médias dessa distância em crianças sem queixas fonoaudiológicas. MÉTODOS: participaram 99 crianças respiradoras bucais, de ambos os gêneros, com idades entre 7 anos e 11 anos e 11 meses, leucodermas, em dentadura mista. O grupo controle foi composto por 253 crianças, com idades entre 7 anos e 11 anos e 11 meses, leucodermas, em dentadura mista, sem queixas fonoaudiológicas. RESULTADOS: os achados evidenciam que a média das distâncias interincisivas máximas das crianças respiradoras bucais foi, no total da amostra, de 43,55mm, não apresentando diferença estatisticamente significativa entre as médias, segundo a idade. Não houve diferença estatisticamente significativa entre as médias da distância interincisiva máxima dos respiradores bucais e as médias dessa medida das crianças do grupo controle. CONCLUSÕES: a distância interincisiva máxima é uma medida que não variou nos respiradores bucais, durante a dentadura mista, segundo a idade, e parece não estar alterada em portadores desse tipo de disfunção. Aponta-se, também, a importância do uso do paquímetro na avaliação objetiva da distância interincisiva máxima.INTRODUCTION: The maximum interincisal distance is an important aspect in the orofacial myofunctional evaluation, because orofacial myofunctional disorders can limit the mouth opening. AIM: To describe the maximum interincisal distance of the mouth breathing children, according to age, and to compare the averages of the maximum interincisal distance of mouth breathing children to those of children with no history of speech-language pathology disorders. METHODS

The formation of filamentary structures from molten silicates: Peleʼs hair, angel hair, and blown clinker

Science.gov (United States)

Villermaux, Emmanuel

2012-08-01

We conduct an analysis of the concomitant, competing phenomena at play in the formation of long filamentary structures from a stream of hot, very viscous and cohesive liquid as it is blown by a fast, cool air stream. The situation is relevant to a broad class of problems, namely volcanic glass threads or fibers formed when small particles of molten material are thrown into the air and spun out by the wind into long hair-like strands (called Pele's hair), to the process of prilling, the manufacture of glass fibers, and the formation of coke in furnaces and combustion chambers. The air stream blowing on the molten material both breaks up the liquid into fragments stabilized by capillarity, and cools the liquid down to solidification. There are, in this problem, four characteristic times. First, a deformation time of the liquid masses, setting the rate at which drops elongate into ligaments. Then, two timescales set the time of capillary breakup of these ligaments, one prevailing on the other depending on the relative weight of inertia on viscous slowing (that point is illustrated by an original experiment). Finally, a solidification time of the ligaments. Thin solid strands will only form when solidification occurs before capillary breakup. We have discovered that this condition is likely to apply when the liquid is strongly viscous, as for clinker in the cement industry, considered here as a generic example. We formulate recommendations to remove (or enhance) the formation of these objects.

DistAMo: A web-based tool to characterize DNA-motif distribution on bacterial chromosomes

Directory of Open Access Journals (Sweden)

Patrick eSobetzko

2016-03-01

Full Text Available Short DNA motifs are involved in a multitude of functions such as for example chromosome segregation, DNA replication or mismatch repair. Distribution of such motifs is often not random and the specific chromosomal pattern relates to the respective motif function. Computational approaches which quantitatively assess such chromosomal motif patterns are necessary. Here we present a new computer tool DistAMo (Distribution Analysis of DNA Motifs. The algorithm uses codon redundancy to calculate the relative abundance of short DNA motifs from single genes to entire chromosomes. Comparative genomics analyses of the GATC-motif distribution in γ-proteobacterial genomes using DistAMo revealed that (i genes beside the replication origin are enriched in GATCs, (ii genome-wide GATC distribution follows a distinct pattern and (iii genes involved in DNA replication and repair are enriched in GATCs. These features are specific for bacterial chromosomes encoding a Dam methyltransferase. The new software is available as a stand-alone or as an easy-to-use web-based server version at http://www.computational.bio.uni-giessen.de/distamo.

Epidemiologia dos distúrbios respiratórios do sono Epidemiology of sleep-disordered breathing

Directory of Open Access Journals (Sweden)

Carlos Alberto de Assis Viegas

2010-06-01

Full Text Available Os principais distúrbios respiratórios do sono, ronco e SAOS, são muito prevalentes na população geral, embora se acredite que a maioria dos casos continue não diagnosticada. Devemos estar atentos para os principais fatores de risco que favorecem o aparecimento desses distúrbios, como gênero masculino, obesidade, envelhecimento e características crânio-faciais. Da mesma forma, a presença de hipertensão arterial sistêmica, enfermidades cardiovasculares e metabólicas deve nos alertar para a possibilidade da concomitância de SAOS.The principal types of sleep-disordered breathing-snoring and obstructive sleep apnea syndrome-are highly prevalent in the general population, although it is believed that the majority of cases continue to go undiagnosed. We should be aware of the principal risk factors that favor the onset of these disorders, such as male gender, obesity, aging and craniofacial features. Similarly, systemic arterial hypertension, cardiovascular diseases and metabolic disorders should alert us to the possibility of obstructive sleep apnea syndrome.

A modalidade de educação a distância (sem distância) na unisinos : um novo conceito para inovação?

OpenAIRE

Schlemmer, Eliane; Garrido, Susane; Caleffi, Paula

2006-01-01

Esse artigo apresenta um breve relato sobre a Educação à distância no contexto da Universidade do Vale do Rio dos Sinos - UNISINOS e discute o conceito de inovação no âmbito do paradigma da complexidade, na Sociedade em Rede ao analisar as transformações sociais e as novas formas de pensamento oriundas das mudanças dos meios tecnológicos. Assim, faz um convite à reflexão sobre o que constitui inovação nos processos de ensino e de aprendizagem, na gestão e na estrutura organizacional, estabele...

Wind and Wave Setup Contributions to Extreme Sea Levels at a Tropical High Island: A Stochastic Cyclone Simulation Study for Apia, Samoa

Directory of Open Access Journals (Sweden)

Ron Karl Hoeke

2015-09-01

Full Text Available Wind-wave contributions to tropical cyclone (TC-induced extreme sea levels are known to be significant in areas with narrow littoral zones, particularly at oceanic islands. Despite this, little information exists in many of these locations to assess the likelihood of inundation, the relative contribution of wind and wave setup to this inundation, and how it may change with sea level rise (SLR, particularly at scales relevant to coastal infrastructure. In this study, we explore TC-induced extreme sea levels at spatial scales on the order of tens of meters at Apia, the capitol of Samoa, a nation in the tropical South Pacific with typical high-island fringing reef morphology. Ensembles of stochastically generated TCs (based on historical information are combined with numerical simulations of wind waves, storm-surge, and wave setup to develop high-resolution statistical information on extreme sea levels and local contributions of wind setup and wave setup. The results indicate that storm track and local morphological details lead to local differences in extreme sea levels on the order of 1 m at spatial scales of less than 1 km. Wave setup is the overall largest contributor at most locations; however, wind setup may exceed wave setup in some sheltered bays. When an arbitrary SLR scenario (+1 m is introduced, overall extreme sea levels are found to modestly decrease relative to SLR, but wave energy near the shoreline greatly increases, consistent with a number of other recent studies. These differences have implications for coastal adaptation strategies.

O uso da educação a distância para o ensino de Libras

Directory of Open Access Journals (Sweden)

Mariana da Cunha Teixeira de Souza

2017-02-01

Full Text Available O presente artigo tem como objetivo apresentar uma experiência de oferta durante o primeiro semestre de 2011 de um curso de Libras, na modalidade a distância, para estudantes de cursos de Licenciatura da Universidade Federal Fluminense.

O papel do tutor em cursos de educação a distância: competências e habilidades

Directory of Open Access Journals (Sweden)

Ana Maria Araújo Passos de Oliveira

2014-02-01

Full Text Available O papel profissional do tutor em cursos em EAD deve ser concebido como o conjunto de condições necessárias para o processo de ensino-aprendizagem à distância. Diante desse contexto, este trabalho tem como objetivo conhecer as competências e as habilidades necessárias ao papel do Tutor em cursos à distância. Para alcançar o objetivo proposto, utilizou-se do deli-neamento exploratório, através de pesquisa bibliográfica em que foram analisadas as conside-rações sobre a EAD, o sistema de tutoria e o papel do Tutor em cursos a distância, bem como a formação necessária para essa função. A partir da análise dos resultados, concluiu-se que o conjunto básico das competências e as habilidades necessárias que caracterizam o papel do tutor em cursos EAD são: possuir habilidades de comunicação, liderança, dinamismo, iniciativa, entusiasmo, criatividade, participação, motivação, competência interpessoal e de trabalho em equipe, além de comprometimento com a formação dos alunos, agilidade no atendimento ao aluno, proporcionando feedback das atividades, conhecer a organização pedagógica, adminis-trativa do curso e ter uma formação condizente com as atividades que irá desenvolver. Por isso, além de uma formação acadêmica em nível de graduação e pós-graduação, ele deve ter cursos específicos na área da Educação à Distância.

A Rádio Educativa Unoesc FM como recurso didático na Educação a Distância

Directory of Open Access Journals (Sweden)

Roseli Rocha Moterle

2010-07-01

Full Text Available A Educação a Distância é uma modalidade de ensino que utiliza diversos meios e tecnologias de informação e comunicação no processo de mediação, de modo que favoreçam a construção do conhecimento e da autonomia de aprendizagem do aluno. Neste artigo apresentam-se os resultados de um projeto de pesquisa, cujo objetivo foi investigar as contribuições da Rádio Educativa no processo de ensino-aprendizagem das disciplinas de Metodologia Científica e de Ética e Sociedade, oferecidas pela Universidade do Oeste de Santa Catarina (Unoesc, na modalidade a distância, por meio de uma radionovela, destacando conflitos éticos em debate na sociedade atual: aborto, pena de morte, plágio e formação ética. A pesquisa foi organizada em três momentos: inicialmente, foram elaborados roteiros dos episódios da radionovela; num segundo momento, foram gravados os programas e veiculados na Rádio Educativa 106,7 FM, na internet ou por download; num terceiro momento, foi disponibilizado aos alunos, por meio do Portal de Ensino, um questionário de pesquisa para avaliar as contribuições desse recurso no processo de ensino-aprendizagem, com a participação de 63% dos alunos matriculados nas disciplinas. Os resultados apontam a Rádio Educativa como um importante recurso didático na Educação a Distância, pois facilita a compreensão dos conteúdos, problematiza situações e casos que se aproximam da realidade do aluno e aprofunda a reflexão de questões difíceis de se reproduzir no material impresso. Recomenda-se a elaboração de novos projetos por meio da Rádio Educativa, aprimorando técnica e metodologicamente o uso da rádio como um recurso didático, a fim de contribuir no processo de ensino-aprendizagem, especialmente na modalidade a distância. Palavras-chave: Rádio Educativa. Radionovela. Educação e Comunicação. Educação a Distância.

Distúrbios alimentares e sua associação com erosão e cárie dentária em adolescentes

OpenAIRE

Brandt, Lorenna Mendes Temóteo

2015-01-01

Os prejuízos na saúde bucal de indivíduos portadores de distúrbios alimentares vêm sendo investigados, trazendo consigo questões discordantes quanto ao comprometimento dos dentes. Diante disso, realizou-se um estudo transversal controlado, com o objetivo de avaliar a ocorrência de erosão e cárie dentária em adolescentes mulheres, de 15 a 18 anos, em risco de estarem sofrendo de distúrbios alimentares e compará-las a adolescentes saudáveis. A amostra probabilística foi compos...

Warm-season severe wind events in Germany

Science.gov (United States)

Gatzen, Christoph

2013-04-01

A 15-year data set of wind measurements was analyzed with regard to warm season severe wind gusts in Germany. For April to September of the years 1997 to 2011, 1035 wind measurements of 26 m/s or greater were found. These wind reports were associated with 268 wind events. In total, 252 convective wind events contributed to 837 (81%) of the wind reports, 16 non-convective synoptic-scale wind events contributed to 198 reports (19%). Severe wind events were found with synoptic situations characterized by rather strong mid-level flow and advancing mid-level troughs. Severe convective wind events were analyzed using radar images and classified with respect to the observed radar structure. The most important convective mode was squall lines that were associated with one third of all severe wind gusts, followed by groups, bow echo complexes, and bow echoes. Supercells and cells were not associated with many wind reports. The low contribution of isolated cells indicates that rather large-scale forcing by synoptic-scale features like fronts is important for German severe wind events. Bow echoes were found to be present for 58% of all wind reports. The movement speed of bow echoes indicated a large variation with a maximum speed of 33 m/s. Extreme wind events as well as events with more than 15 wind reports were found to be related to higher movement speeds. Concentrating on the most intense events, derechos seem to be very important to the warm season wind threat in Germany. Convective events with a path length of more than 400 km contributed to 36% of all warm-season wind gusts in this data set. Furthermore, eight of nine extreme gusts exceeding 40 m/s were recorded with derecho events.

A história e a expansão da educação a distância: um estudo de caso da UNICESUMAR

Directory of Open Access Journals (Sweden)

Larissa Costa dos Santos

2018-01-01

Full Text Available Com o advento da sociedade da informação, a tecnologia motivou novos comportamentos, atitudes e relações sociais, influenciando a vida em sociedade. A educação também foi uma das áreas que obteve mudanças motivadas pela tecnologia e uma das formas de educação onde essa realidade está mais presente é a Educação a Distância (EaD. Em vista disso, a presente pesquisa teve como objetivo descrever a história e a expansão da Educação a Distância no mundo e no Brasil e, ainda, descrever a história e a expansão da educação a distância em um caso específico: na instituição de ensino superior Unicesumar. Para tanto, foi realizada pesquisa qualitativa e a coleta de dados foi realizada por meio de pesquisa bibliográfica, análise de documentos da Unicesumar e entrevistas. Por fim, ressalta-se que a Educação a Distância no mundo, no Brasil e na instituição de ensino Unicesumar alcançaram notáveis avanços, contudo ainda há desafios a serem superados, devido ao fato de que ainda existem lugares onde não há acesso à educação e também trabalhar no combate ao preconceito que a modalidade sofre, visto que a Educação a Distância exerce uma função considerável no tocante a democratização do ensino.

Blown films of PA6/MMT nanocomposites: structural characterization by SAXs

International Nuclear Information System (INIS)

Marini, J.; Beatrice, C.A.G.; Lucas, A.A.; Bretas, R.E.S.

2016-01-01

In this work the influence of the processing conditions (take up and blow up ratios, TUR and BUR, respectively) in the nano-periodicity and lamellae orientation of PA6 nanocomposites blown films with natural (MMT) and organically modified montmorillonite (oMMT) was studied by SAXS. Unexpectedly, a preferred orientation of the crystalline lamellae along the normal direction (ND) was observed for all analyzed films. Such behavior can be explained by the preservation of the initial lamellae orientation of the PA6 chains imposed by the spiral flow in the die, almost null elastic recovery and fast crystallization kinetics of PA6 at the processing conditions applied. The orientation of the nanoparticles (measured by TEM) showed to be directly dependent on the TUR and BUR. The presence of the reinforcing fillers and the different processing conditions showed no significant influence on the nanoperiodicity. (author)

Investigation of Wind Turbine Rotor Concepts for Offshore Wind Farms

International Nuclear Information System (INIS)

Ceyhan, Özlem; Grasso, Francesco

2014-01-01

Current plans in offshore wind energy developments call for further reduction of cost of energy. In order to contribute to this goal, several wind turbine rotor concepts have been investigated. Assuming the future offshore wind turbines will operate only in the offshore wind farms, the rotor concepts are not only evaluated for their stand-alone performances and their potential in reducing the loads, but also for their performance in an offshore wind farm. In order to do that, the 10MW reference wind turbine designed in Innwind.EU project is chosen as baseline. Several rotor parameters have been modified and their influences are investigated for offshore wind turbine design purposes. This investigation is carried out as a conceptual parametrical study. All concepts are evaluated numerically with BOT (Blade optimisation tool) software in wind turbine level and with Farmflow software in wind farm level for two wind farm layouts. At the end, all these concepts are compared with each other in terms of their advantages and disadvantages

Sliding Window Technique for Calculating System LOLP Contributions of Wind Power Plants

International Nuclear Information System (INIS)

Milligan, M. R.

2001-01-01

Conventional electric power generation models do not typically recognize the probabilistic nature of the power variations from wind plants. Most models allow for an accurate hourly representation of wind power output, but do not incorporate any probabilistic assessment of whether the given level of wind power will vary from its expected value. The technique presented in this paper uses this variation to calculate an effective forced-outage rate for wind power plants (EFORW). Depending on the type of wind regime undergoing evaluation, the length and diurnal characteristics of a sliding time window can be adjusted so that the EFORW is based on an appropriate time scale. The algorithm allows us to calculate the loss-of-load probability (LOLP) on an hourly basis, fully incorporating the variability of the wind resource into the calculation. This makes it possible to obtain a more accurate assessment of reliability of systems that include wind generation when system reliability is a concern

DTU contributions to IEA Wind Annex 25 Phase 2

Energy Technology Data Exchange (ETDEWEB)

Soerensen, Poul; Cutululis, N.; Meibom, P.

2012-10-15

The objective of Task 25 is to analyse and further develop the methodology to assess the impact of wind power on power systems. The Task has established an international forum for exchange of knowledge and experiences related to power system operation with large amounts of wind power and has actively followed parallel activities with Transmission System Operators other R and D Task work. The participants have collected and shared information on the experience gained and the studies made up to and during the task. The case studies have addressed different aspects of power system operation and design, mainly: balancing, grid impacts and capacity credit of wind power. In the meetings, all participants have made presentations of the wind integration issues in their country, results so far and on-going activities. In the latest meetings presentations have been grouped to different topics to better dwell into the details of modelling challenges. In addition, there has been some telephone/web meetings for the journal articles and Recommendations report. In the Task 25 meetings, updates from other international work are also given (EU/TPWIND and SET-Plan, IEEE, IPCC). TSO collaboration is important for Task 25 work. There has been TSO participation in all meetings, with the participants from Canada, Denmark and Italy in most meetings and some other countries sending TSO participants in fewer meetings. (Author)

Avaliação de treinamento a distância : reação, suporte à transferência e impactos no trabalho

OpenAIRE

Carvalho, Renata Silveira; Abbad, Gardênia da Silva

2006-01-01

O uso da Internet em treinamentos a distância vem sendo enfatizado, porém se percebem poucas avaliações sistemáticas dessas intervenções. A presente pesquisa avalia modelos de predição de três variáveis critério: Escores de Aprendizagem e Impacto do Treinamento no Trabalho, medido em Profundidade e em Amplitude. As variáveis antecedentes dos modelos integram os componentes de Reação, Características da Clientela e Suporte à Transferência. Foi avaliado um curso a distância, medi...

Wind Power in Ontario: Its Contribution to the Electricity Grid

Science.gov (United States)

Rowlands, Ian H.; Jernigan, Carey

2008-01-01

The purpose of this article is to investigate wind turbine production, the variability of that production, and the relationship between output and system-wide demand. A review of the literature reveals that a variety of measures (and methods) to explore the variability of wind power production exist. Attention then turns to the province of Ontario…

Flexible Slippery Surface to Manipulate Droplet Coalescence and Sliding, and Its Practicability in Wind-Resistant Water Collection.

Science.gov (United States)

Wang, Yuanfeng; Qian, Baitai; Lai, Chuilin; Wang, Xiaowen; Ma, Kaikai; Guo, Yujuan; Zhu, Xingli; Fei, Bin; Xin, John H

2017-07-26

A flexible slippery membrane (FSM) with tunable morphology and high elastic deformability has been developed by infusing perfluoropolyether (PFPE) into a fluorinated-copolymer-modified thermoplastic polyurethane (TPU) nanofiberous membrane. To immobilize PFPE in TPU matrix, we synthesized a fluorinated-copolymer poly(DFMA-co-IBOA-co-LMA) with low surface energy, high chemical affinity to PFPE, adequate flexibility, and strong physical adhesion on TPU. Upon external tensile stress, the as-prepared FSM can realize a real-time manipulation of water sliding and coalescence on it. Furthermore, it exhibits the ability to preserve the captured water from being blown away by strong wind, which ensures the water collection efficiency in windy regions.

Educação a Distância e formação continuada do professor Distance Education and further teacher development

Directory of Open Access Journals (Sweden)

Leda Maria Borges da Cunha Rodrigues

2012-12-01

Full Text Available Tem sido significativo o papel da Educação a Distância (EaD na formação continuada de docentes. Assim, esta pesquisa teve como objetivo levantar e analisar dados em relação à sua utilização para formação continuada de professores quanto ao processo de inclusão da pessoa com deficiência. Construído e aplicado questionário semiestruturado, participaram da pesquisa 182 alunos do Curso a distância da Unesp-Bauru/SP, realizado em parceria com o Ministério da Educação. Os resultados indicam que a flexibilidade de horário e o atendimento a grande número de alunos, em diferentes áreas geográficas, destacam-se como pontos positivos desta modalidade, porém, para seu sucesso, é necessária a formação adequada dos formadores/tutores na utilização das novas ferramentas no processo de ensino-aprendizagem, sendo imprescindível que os alunos tenham a sensação de serem assistidos em todos os momentos, contribuindo para a construção da comunidade virtual e efetivando, na Educação a Distância, a formação de qualidade.Distance Education has had a significant role in further teacher development. The aim of this study was to collect and analyze data related to distance education for the further teacher development related to the inclusion process of people with disability. One hundred and eighty two students from the Distance Training course from Unesp - Bauru / SP participated in the research, constructing and applying a semi-structured questionnaire. The results indicate that scheduling flexibility and attendance of a great number of students in different geographical areas stand out as positive points of this modality, however, for it to be a success, tutors must be adequately prepared to use new tools in the teaching-learning process. It is essential that the students feel they are being assisted in every moment, contributing to the construction of a virtual community and effecting quality development in distance education.

A prática dos tutores em um programa de formação pedagógica a distância: avanços e desafios

Directory of Open Access Journals (Sweden)

Maria de Fátima S. O. Barbosa

2006-12-01

Full Text Available Este trabalho foi realizado no âmbito de um programa de formação pedagógica a distância de trabalhadores da área de enfermagem, buscando conhecer a prática dos tutores e os obstáculos e desafios enfrentados por eles na ação educativa a distância. Os obstáculos apontados pelos tutores foram: dificuldade em assimilar a concepção pedagógica construtivista nas atividades de tutoria (transpor a proposta pedagógica para a prática; dificuldade no uso das tecnologias; falta de infra-estrutura de telecomunicações de alguns municípios; dificuldade em realizar atividades necessárias ao desenvolvimento do curso em função da falta de tempo. Os tutores consideraram um desafio desempenhar a tutoria, por ser uma experiência nova para a qual não há modelo predefinido a seguir. Os resultados indicaram que a educação a distância ainda não foi culturalmente assimilada pelos tutores e que superar a distância pode ser ainda mais difícil para profissionais de enfermagem que possuem dupla jornada de trabalho.

O trágico, o cômico e a "distância artística": arte e conhecimento n'A Gaia Ciência, de Nietzsche

Directory of Open Access Journals (Sweden)

Ernani Chaves

2005-12-01

Full Text Available A partir da leitura de A Gaia Ciência, pretendemos mostrar alguns elementos importantes que, nesse livro, se constituem em torno do tema da "distância". Analisando principalmente três aforismos do livro, procura-se esclarecer o deslocamento no texto e no pensamento de Nietzsche da distância como Ferne, de origem romântica, à distância como Distanz. Entretanto, procura-se ao final mostrar que Nietzsche desloca o tema romântico da Ferne, caracterizando-a como uma "distância artística", que se torna o traço distintivo entre a perspectiva da arte e a perspectiva do conhecimento.This reading of The Gay Science intends to show some important elements which, in this book, gravitate around the theme of "distance". Analysing particularly three aphorisms of the book, our goal is to clarify the movement, in the text and in Nietzsche's thought as well, from distance as Ferne, with its romantic source, to distance as Distanz. However, in the end, we intend to show that Nietzsche dislocates the romantic theme of the Ferne, taking it as an "artistic distance", which becomes the distinctive trace between the perspectives of art and knowledge.

MICROBIOLOGICAL CHARACTERISTICS OF THE AIR BLOWN BY WARM AIR HAND DRYERS

Directory of Open Access Journals (Sweden)

Recai OÐUR; Omer Faruk TEKBAS; Osman HANCI; Umut OZCAN

2005-02-01

Full Text Available The aim of the study was to determine the microbiological characteristics of air blown from warm air hand dryers, and to compare findings with the microbiological characteristics of indoor air in which the dryer settled. Air samples was taken from different public places (shopping centers, restaurants and hospitals and investigated for total viable counts, coagulase negative Staphylococcus, E. Coli, Staphylococcus aureus and enteric pathogens. There were differences between sampling indoor places for some of the microorganisms, but all of the air samples taken from dryers contained more microorganisms than indoor air, and the differences between hand dryers and indoor air were statistically significant (p<0.05 except for enteric pathogens. As a result it could be said that warm air hand dryers could be microbiological contamination sources in restrooms or the other places that they are used. [TAF Prev Med Bull 2005; 4(1.000: 1-7

The causes and consequences of blown-up coal dust

International Nuclear Information System (INIS)

Vrins, E.L.M.; Van Zuylen, E.J.

1991-11-01

The goal of the Dutch National Research Program Coal (NOK), which started in 1983, is to eliminate technical, economic and ecological objections, connected with the large-scale use of coal. The Blown-up Coal Dust program, which is completed in 1991, aimed at problems that arise, due to the dispersion of coal dust in the vicinity of coal storage and transshipment areas. The accumulated knowledge is categorized according to the route the dust itself follows, starting with activities that cause the dust and continuing up to the effects, of which nuisance in the neighborhood is the most important. The successive chapters are: Activities, Emission, Concentration, Deposition, Pollution and Nuisance and other effects. Inventories of available knowledge, models and measuring equipment have been carried out for each part. The models describe the connection between the various stages of the progress of the dust, from cause to consequence. Newly developed measuring equipment was tested in practice. Various analysis techniques were used and evaluated, such as gravimetric, chemical and optical analysis. A specific coal dust analysis technique is not available. 15 figs., 23 tabs., 1 appendix, 263 refs

Sociedade da Informação e a Educação a Distância no Brasil: O novo enfoque do ensino superior a distância na gestão pública. Information society and distance education in Brazil: a new approach of higher education distance in public management

Directory of Open Access Journals (Sweden)

Vieira, Rejane Esther

2010-05-01

Full Text Available O objetivo central do presente artigo é analisar a importância do ensino a distância na formação de gestores públicos na atual sociedade da informação. Questiona-se: Qual o papel do ensino a distância e das tecnologias aplicadas na democratização do conhecimento no Ensino Superior a distância no Brasil? Neste contexto, destaca-se que a formação de novos gestores públicos está sendo concretizada por meio da educação a distância no ensino superior brasileiro, promovendo a inovação e a democratização do conhecimento na área pública. Sabe-se que Educação a distância é uma forma de ensino que possibilita a autoaprendizagem, com a mediação de recursos didáticos sistematicamente organizados, apresentados em diferentes suportes de informação, utilizados isoladamente ou combinados, e veiculados pelos diversos meios de comunicação. É cada vez mais consensual a intensificação tecnológica na educação, com o uso das tecnologias digitais, com ênfase na disseminação da Internet, tem entre as suas premissas “integradas” possibilitar a emergência de uma nova geração da educação a distância, entendida, portanto, como Universidade Virtual. A metodologia utilizada é bibliográfica e documental.The main objective of this study is to analyze the importance of distance education in the training of public managers in today's information society. Question: What is the role of distance education and technology applied in the democratization of knowledge in higher education distance in Brazil? In this context, we emphasize that the formation of new public management is being achieved through distance education in higher education in Brazil, promoting the democratization of knowledge and innovation in the public area. We know that distance education is a form of education that enables self-learning, with the mediation of learning resources systematically organized, presented in different media, used alone or combined

The contribution of the social sciences to wind power research

International Nuclear Information System (INIS)

Edge, H.M.

1990-01-01

Research has been carried out to investigate future scenarios for renewable resources and their use in rural areas of the UK, and attitudes to wind and other renewables technology, amongst sample population in the north east of Scotland. Future scenarios were explored by means of a three road 'Delphi' survey. Attitudinal data was gathered by questionnaire survey. Results suggest a degree of antipathy towards new technology and little correlation between confidence in the future of such technology and enthusiasm for it. Further research is proposed to explore the relationships between attitudes to wind turbines and political and ideological belief. Such research will fill a gap in knowledge relating to Scottish attitudes to the exploration of this large sector of the UK wind energy resource. (Author)

"E quando o paciente não quer comer?" um estudo sobre as queixas alimentares de crianças com distúrbios de apetite

OpenAIRE

Ferraz, Aline Oliveira

2006-01-01

Esta pesquisa objetivou estudar a alimentação à luz da teoria winnicottiana, para compreender as queixas alimentares de crianças com distúrbios do apetite no contexto da clínica fonoaudiológica. O hiato entre a queixa materna e a demanda do próprio paciente fundamentou o interesse em entender os significados do distúrbio alimentar, a partir de uma perspectiva relacional. As dificuldades em torno da alimentação indicaram a necessidade de ultrapassar um olhar clínico voltado exclusivamente à fu...

Performance of spanish wind turbines

International Nuclear Information System (INIS)

Lago, C.

1995-01-01

In this document we can find a statistical evaluation for the wind energy generation from each spanish wind farm referred to 1994, going on with the work that has been carried out since 1992, by initiative of the Wind Energy Division from Renewable Energy Institute. The purpose of this work is to contribute with interesting information for the wind environment and offer a global view from monthly performances of different wind farms. (Author)

Development of thermoplastic starch blown film by incorporating plasticized chitosan.

Science.gov (United States)

Dang, Khanh Minh; Yoksan, Rangrong

2015-01-22

The objective of the present work was to improve blown film extrusion processability and properties of thermoplastic starch (TPS) film by incorporating plasticized chitosan, with a content of 0.37-1.45%. The effects of chitosan on extrusion processability and melt flow ability of TPS, as well as that on appearance, optical properties, thermal properties, viscoelastic properties and tensile properties of the films were investigated. The possible interactions between chitosan and starch molecules were evaluated by FTIR and XRD techniques. Chitosan and starch molecules could interact via hydrogen bonds, as confirmed from the blue shift of OH bands and the reduction of V-type crystal formation. Although the incorporation of chitosan caused decreased extensibility and melt flow ability, as well as increased yellowness and opacity, the films possessed better extrusion processability, increased tensile strength, rigidity, thermal stability and UV absorption, as well as reduced water absorption and surface stickiness. The obtained TPS/chitosan-based films offer real potential application in the food industry, e.g. as edible films. Copyright © 2014 Elsevier Ltd. All rights reserved.

Contribution to the chapter on wind power in: Energy technology perspectives 2008, IEA

Energy Technology Data Exchange (ETDEWEB)

Lemming, J.; Morthorst, P.E.; Clausen, Niels-Erik; Hjuler Jensen, P.

2009-01-15

Over the last 5 years the growth rate in wind energy has been as high as 30% an on average nearly 25% in all continents, and a considerable number of countries have very ambitious goals concerning their wind energy development, therefore it could be likely to cover as much as 20% of the world's electricity consumption by wind in 2030 and 35% in 2050, although on the shorter term growth is expected to take place mainly in Europe, USA and China. The market is maturing, therefore achieving more stable economies in the wind energy sector. As a result, better electrical grids suited for wind power are being developed and better planning tools as well as other frameworks, which benefit the market for installation of wind turbines, are being implemented across all wind energy countries. The cost of wind-generated electricity has fallen steadily for the last two decades, driven largely by technological advances, increased production levels and the use of larger turbines. Between 1985 and 2005, production costs energy from of wind turbines decreased by nearly 100% in 2006 prices. The price rises seen in last three years due to capacity problems in the industry are expected to stop, once supply system constraints are overcome. Onshore wind is considered commercial at sites with good wind resources and grid access. Cost reductions in both turbines and infrastructure are expected to bring investment costs to 0.88 mill. Euro/MW in 2030 and 0.8 mill. Euro/MW in 2050. On the other hand, offshore wind is in pre-commercial development phase. Considerable costs improvements are expected in all areas making costs go down to 1. 4 mill. Euro/MW in 2030 and 1.3 mill. Euro/MW in 2050. Priority RD and D areas to foster continued growth in wind power are to increase the value and reduce uncertainties. This will mean further cost reductions on longer terms, enabling large-scale use by improved grid integration and storage facilities and minimizing environmental impact. (au)

Wind Power Plant Control Optimisation with Incorporation of Wind Turbines and STATCOMs

DEFF Research Database (Denmark)

Petersen, Lennart; Kryezi, Fitim; Iov, Florin

2015-01-01

This paper addresses a detailed design and tuning of a wind power plant slope voltage control with reactive power contribution of wind turbines and STATCOMS. First, small-signal models of a single wind turbine and the whole wind power plant are developed, being appropriate for voltage control...... assessment. An exemplary wind power plant located in the United Kingdom and the corresponding grid code requirements are used as a base case. The final design and tuning process of the voltage controller results in a guidance, proposed for this particular control architecture. It provides qualitative...... outcomes regarding the impact of system delays, grid conditions and various operating conditions of the wind power plant, with and without incorporation of STATCOMS....

Distúrbios nutricionais em atletas femininas e suas inter-relações Nutrition disorders in female athletes and their interrelationships

Directory of Open Access Journals (Sweden)

Teresa Cristina Ciavaglia VILARDI

2001-04-01

Full Text Available Pesquisas indicam que é elevada a prevalência de distúrbios alimentares em atletas femininas jovens envolvidas em esportes que preconizam a magreza e o baixo peso corporal, tais como ginástica olímpica e corridas de longa distância. A fim de compreender a etiologia destes problemas, esta revisão apresenta os principais distúrbios nutricionais encontrados em atletas femininas, incluindo definições, critérios para diagnóstico, fatores de risco, presença de desordens inter-relacionadas - anemia, irregularidades menstruais e desmineralização óssea e suas conseqüências sobre a saúde e rendimento atlético. É fundamental ressaltar a importância da nutrição no desempenho físico. A presença de um baixo peso corporal e um consumo energético severamente restrito é o principal fator de risco para o desenvolvimento de tais distúrbios. Como as atletas e seus treinadores não apresentam adequados conhecimentos sobre nutrição, é necessária uma orientação nutricional individualizada, de forma a evitar o desenvolvimento destas alterações.Researches have indicated that the prevalence of nutrition disorders is high among young female athletes engaged in sports that emphasize the importance of leanness and low body weight, such as olympic gymnastics and distance running. In order to understand the etiology of these problems, this review presents the main nutrition disorders in female athletes, including definitions, diagnostic criteria, risk factors, presence of interrelated disorders (anemia, menstrual irregularities and failure of bone mineralization and their consequences on health and athletic performance. It is fundamental to point out the importance of nutrition on physical performance. The presence of a low body weight and a very restricted energy intake is the principal risk factor for the development of nutritional disturbances. The athletes and their coaches do not have an apropriate knowledge about nutrition, so it is

A Rádio Educativa Unoesc FM como recurso didático na Educação a Distância

Directory of Open Access Journals (Sweden)

Roseli Rocha Moterle

2010-07-01

Full Text Available A Educação a Distância é uma modalidade de ensino que utiliza diversos meios e tecnologias de informação e comunicação no processo de mediação, de modo que favoreçam a construção do conhecimento e da autonomia de aprendizagem do aluno. Neste artigo apresentam-se os resultados de um projeto de pesquisa, cujo objetivo foi investigar as contribuições da Rádio Educativa no processo de ensino-aprendizagem das disciplinas de Metodologia Científica e de Ética e Sociedade, oferecidas pela Universidade do Oeste de Santa Catarina (Unoesc, na modalidade a distância, por meio de uma radionovela, destacando conflitos éticos em debate na sociedade atual: aborto, pena de morte, plágio e formação ética. A pesquisa foi organizada em três momentos: inicialmente, foram elaborados roteiros dos episódios da radionovela; num segundo momento, foram gravados os programas e veiculados na Rádio Educativa 106,7 FM, na internet ou por download; num terceiro momento, foi disponibilizado aos alunos, por meio do Portal de Ensino, um questionário de pesquisa para avaliar as contribuições desse recurso no processo de ensino-aprendizagem, com a participação de 63% dos alunos matriculados nas disciplinas. Os resultados apontam a Rádio Educativa como um importante recurso didático na Educação a Distância, pois facilita a compreensão dos conteúdos, problematiza situações e casos que se aproximam da realidade do aluno e aprofunda a reflexão de questões difíceis de se reproduzir no material impresso. Recomenda-se a elaboração de novos projetos por meio da Rádio Educativa, aprimorando técnica e metodologicamente o uso da rádio como um recurso didático, a fim de contribuir no processo de ensino-aprendizagem, especialmente na modalidade a distância.

Wind farm economics

International Nuclear Information System (INIS)

Milborrow, D.J.

1995-01-01

The economics of wind energy are changing rapidly, with improvements in machine performance and increases in size both contributing to reduce costs. These trends are examined and future costs assessed. Although the United Kingdom has regions of high wind speed, these are often in difficult terrain and construction costs are often higher than elsewhere in Europe. Nevertheless, wind energy costs are converging with those of the conventional thermal sources. At present, bank loan periods for wind projects are shorter than for thermal plant, which means that energy prices are higher. Ways of overcoming this problem are explored. It is important, also, to examine the value of wind energy. It is argued that wind energy has a higher value than energy from centralized plant, since it is fed into the low-voltage distribution network. (Author)

Accurate Short-Term Power Forecasting of Wind Turbines: The Case of Jeju Island’s Wind Farm

OpenAIRE

BeomJun Park; Jin Hur

2017-01-01

Short-term wind power forecasting is a technique which tells system operators how much wind power can be expected at a specific time. Due to the increasing penetration of wind generating resources into the power grids, short-term wind power forecasting is becoming an important issue for grid integration analysis. The high reliability of wind power forecasting can contribute to the successful integration of wind generating resources into the power grids. To guarantee the reliability of forecas...

Fault current contribution from VSC-based wind turbines to the grid

DEFF Research Database (Denmark)

Valentini, Massimo; Akhmatov, Vladislav; Iov, Florin

2008-01-01

current injections during the fault. In this paper an equivalent VSC-based wind turbine model for short-circuit calculations at steady-state conditions is developed and presented. The model is implemented in DigSILENT PowerFactory using the DPL-Programming Language. The developed wind turbine model...

Wind Tunnel Tests for Wind Pressure Distribution on Gable Roof Buildings

Science.gov (United States)

2013-01-01

Gable roof buildings are widely used in industrial buildings. Based on wind tunnel tests with rigid models, wind pressure distributions on gable roof buildings with different aspect ratios were measured simultaneously. Some characteristics of the measured wind pressure field on the surfaces of the models were analyzed, including mean wind pressure, fluctuating wind pressure, peak negative wind pressure, and characteristics of proper orthogonal decomposition results of the measured wind pressure field. The results show that extremely high local suctions often occur in the leading edges of longitudinal wall and windward roof, roof corner, and roof ridge which are the severe damaged locations under strong wind. The aspect ratio of building has a certain effect on the mean wind pressure coefficients, and the effect relates to wind attack angle. Compared with experimental results, the region division of roof corner and roof ridge from AIJ2004 is more reasonable than those from CECS102:2002 and MBMA2006.The contributions of the first several eigenvectors to the overall wind pressure distributions become much bigger. The investigation can offer some basic understanding for estimating wind load distribution on gable roof buildings and facilitate wind-resistant design of cladding components and their connections considering wind load path. PMID:24082851

Second wind in the offshore wind industry

International Nuclear Information System (INIS)

Philippe, Edouard; Neyme, Eric; Deboos, Christophe; Villageois, Jean-Remy; Gouverneur, Philippe; Gerard, Bernard; Fournier, Eric; Petrus, Raymond; Lemarquis, David; Dener, Marc; Bivaud, Jean-Pierre; Lemaire, Etienne; Nielsen, Steffen; Lafon, Xavier; Lagandre, Pierre; Nadai, Alain; Pinot de Villechenon, Edouard; Westhues, Markus; Herpers, Frederick; Bisiaux, Christophe; Sperlich, Miriam; Bales, Vincent; Vandenbroeck, Jan; His, Stephane; Derrey, Thierry; Barakat, Georges; Dakyo, Brayima; Carme, Laurent; Petit, Frederic; Ytournel, Sophie; Westhues, Markus; Diller, Armin; Premont, Antoine de; Ruer, Jacques; Lanoe, Frederic; Declercq, Jan; Holmager, Morten; Fidelin, Daniel; Guillet, Jerome; Dudziak, Gregory; Lapierre, Anne; Couturier, Ludovic; Audineau, Jean-Pierre; Rouaix, Eric; De Roeck, Yann-Herve; Quesnel, Louis; Duguet, Benjamin

2011-06-01

After several keynote addresses, this publication contains contributions and Power Point presentations proposed during this conference on the development of offshore wind energy. The successive sessions addressed the following issues: the offshore mass production of electricity (examples of Denmark and Belgium, laying and protecting offshore cables), the space, economic and environmental planning (the Danish experience, the role of the Coastal area integrated management, importance of the public debate, so on), the logistics of port infrastructures (simulation tools, example of Bremerhaven, issues related to project management), innovation at the core of industrial strategies (high power wind turbines, the 6 MW Alstom turbine, chain value and innovation in offshore wind energy, the Vertiwing innovating project of a floating wind turbine, a bench test in Charleston, foundations, gravity base structures, the British experience, the Danish experience), the economic and organisational conditions for development, the validation and certification of technologies

Wind energy economics

International Nuclear Information System (INIS)

Milborrow, D.J.

1995-01-01

The economics of wind energy have improved rapidly in the past few years, with improvements in machine performance and increases in size both contributing to reduce costs. These trends are examined and future costs assessed. As bank loan periods for wind projects are shorter than for thermal plant, the effect on the price of wind energy is discussed. It is argued that wind energy has a higher value than that of centralised plant, since it is fed into the low voltage distribution network and it follows that the price of wind energy is converging with its value. The paper also includes a brief review of the capacity credit of wind plant and an assessment of the cost penalties which are incurred due to the need to hold extra plant on part load. These penalties are shown to be small. (author)

Contribution to the study of the wind and solar radiation over Guadeloupe

International Nuclear Information System (INIS)

Bertin, A.; Frangi, J.P.

2013-01-01

Highlights: • We study wind and solar resource in Guadeloupe (FWI). • Weibull distributions reveal a nocturnal radiative layer blocking wind at airport. • We provide monthly and annual irradiations, horizontal and tilted, for four sites. • Five Linke turbidity coefficient calculation methods are reviewed and compared. - Abstract: Guadeloupean archipelago must reach energy autonomy in 2030 and include at least 50% of renewables in 2020, where wind and photovoltaics can play a significant role. Still, Guadeloupe gathers a lot of landscapes having great impact on wind and solar resource. Study of three 10-years database and one 5-year database locates a nocturnal radiative layer above the airport meteorological station, drastically limiting the wind potential there, and gives all the irradiation components (monthly sums) and therefore key parameters for photovoltaic energy yield. This paper also points out the underestimation of Linke turbidity coefficient in the airport station with Solar Radiation Database (SoDa), compared to ground-based determination, and calculates the value of this coefficient for three stations across Guadeloupe. All those parameters are discussed, as being of importance to make fair predictions of statistical relationships involving preliminary assessment and modeling of wind and solar energy systems. These results can then be used in neighboring countries, Guadeloupe having various meteorological conditions retrieved in Caribbean

Distúrbios cognitivos na doença de Parkinson: correlações eletrencefalográficas

Directory of Open Access Journals (Sweden)

João Santos Pereira

1995-03-01

Full Text Available 62 pacientes com diagnóstico de doença de Parkinson idiopática e 30 pacientes controle foram avaliados quanto a distúrbios mnemônicos e psíquicos, utilizando-se os critérios do DSM III-R, o mini-mental e a escala de Hamilton para depressão. Todos foram submetidos a eletrencefalograma (EEG com fotoestimulação intermitente. Dos pacientes parkinsonianos, 24,2% apresentavam depressão psíquica, 14,5% ansiedade, 12,9% distimia, 3,2% demência e 45,2% não apresentavam quaisquer alterações de acordo com os critérios dos DSM III-R. Nos EEG evidenciavam-se ondas teta bilaterais com predomínio fronto-temporal ou temporal, com maior comprometimento à esquerda, em 58,1% desses pacientes. Em apenas 16 (7% dos pacientes controle tais achados foram observados, porém, em nenhum dos dois grupos ocorreram alterações no EEG pela fotoestimulação. As alterações do EEG foram estatisticamente significantes quando se compararam pacientes parkinsonianos com pacientes controle (p<0,001; o mesmo não ocorreu quando se compararam pacientes parkinsonianos que apresentavam distúrbio psíquico com aqueles que não o apresentavam.

RELATIVE CONTRIBUTION OF THE MAGNETIC FIELD BARRIER AND SOLAR WIND SPEED IN ICME-ASSOCIATED FORBUSH DECREASES

International Nuclear Information System (INIS)

Bhaskar, Ankush; Vichare, Geeta; Subramanian, Prasad

2016-01-01

We study 50 cosmic-ray Forbush decreases (FDs) from the Oulu neutron monitor data during 1997–2005 that were associated with Earth-directed interplanetary coronal mass ejections (ICMEs). Such events are generally thought to arise due to the shielding of cosmic rays by a propagating diffusive barrier. The main processes at work are the diffusion of cosmic rays across the large-scale magnetic fields carried by the ICME and their advection by the solar wind. In an attempt to better understand the relative importance of these effects, we analyze the relationship between the FD profiles and those of the interplanetary magnetic field (B) and the solar wind speed (V sw ). Over the entire duration of a given FD, we find that the FD profile is generally (anti)correlated with the B and V sw profiles. This trend holds separately for the FD main and recovery phases too. For the recovery phases, however, the FD profile is highly anti-correlated with the V sw profile, but not with the B profile. While the total duration of the FD profile is similar to that of the V sw profile, it is significantly longer than that of the B profile. Using the convection–diffusion model, a significant contribution of advection by solar wind is found during the recovery phases of the FD.

RELATIVE CONTRIBUTION OF THE MAGNETIC FIELD BARRIER AND SOLAR WIND SPEED IN ICME-ASSOCIATED FORBUSH DECREASES

Energy Technology Data Exchange (ETDEWEB)

Bhaskar, Ankush; Vichare, Geeta [Indian Institute of Geomagnetism, Kalamboli Highway, New Panvel, Navi Mumbai 410218 (India); Subramanian, Prasad, E-mail: ankushbhaskar@gmail.com [Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008 (India)

2016-09-10

We study 50 cosmic-ray Forbush decreases (FDs) from the Oulu neutron monitor data during 1997–2005 that were associated with Earth-directed interplanetary coronal mass ejections (ICMEs). Such events are generally thought to arise due to the shielding of cosmic rays by a propagating diffusive barrier. The main processes at work are the diffusion of cosmic rays across the large-scale magnetic fields carried by the ICME and their advection by the solar wind. In an attempt to better understand the relative importance of these effects, we analyze the relationship between the FD profiles and those of the interplanetary magnetic field (B) and the solar wind speed (V {sub sw}). Over the entire duration of a given FD, we find that the FD profile is generally (anti)correlated with the B and V {sub sw} profiles. This trend holds separately for the FD main and recovery phases too. For the recovery phases, however, the FD profile is highly anti-correlated with the V {sub sw} profile, but not with the B profile. While the total duration of the FD profile is similar to that of the V {sub sw} profile, it is significantly longer than that of the B profile. Using the convection–diffusion model, a significant contribution of advection by solar wind is found during the recovery phases of the FD.

Post-IR IRSL₂₉₀ dating of K-rich feldspar sand grains in a wind-dominated system on Sardinia

DEFF Research Database (Denmark)

Andreucci, S.; Sechi, D.; Buylaert, Jan-Pieter

2017-01-01

The reliability of a post-IR elevated temperature IRSL (290 °C; pIRIR290) is tested on wind-blown, sand-sized (180–250 μm) K-rich feldspar grains. The pIRIR290 ages were compared with quartz SAR-OSL data, other independent age controls and historical information. Three study areas along the coast....... The pIRIR290 ages indicate an offset up to ∼1000 years. We can conclude that the pIRIR290 method on sand-sized K-feldspar grains shows great promise for samples at or beyond the quartz OSL age limit but should not be applied to Late Holocene or modern deposits....

Wind Observatory 2017. Analysis of the wind power market, wind jobs and future of the wind industry in France

International Nuclear Information System (INIS)

2017-09-01

Two years after the enactment of the Energy Transition for Green Growth Act, wind power capacity continues to grow in France, exceeding 12 GWatt the end of 2016 and soon to account for 5% of France's electric power consumption. This vitality, which is set to continue in 2017, will help France achieve its objectives of an installed capacity of 15,000 MW in onshore wind by 2018 and 21,800 to 26,000 MW by 2023. The current pace will nevertheless have to be accelerated in order to reach the realistic objective of 26 GW by 2023 mentioned in the multi-annual energy plan (PPE). With 1,400 jobs created in one year and more than 3,300 over the last two years, the relevance of wind power as a driving force of sustainable job creation throughout the country is unequivocally confirmed: the increase in wind power capacity continues to contribute to the growth in employment in the country. Prepared in collaboration with the consulting firm BearingPoint, the 2017 edition of the Observatory aims to give the reader an overview of employment in the wind industry and the wind power market over the period under consideration. Any changes from the three previous editions are highlighted. It is based on a comprehensive census of all market participants on three themes: employment, the market and the future of wind power. The Observatory gives an accurate picture of how the wind energy industry is structured, thereby presenting a precise overview of the wind energy industry and all its components

Contribution of wind power and CHP to exports from Western Denmark during 2000-2004

International Nuclear Information System (INIS)

Mignard, D.; Harrison, G.P.; Pritchard, C.L.

2007-01-01

The experience of Denmark is used by the United Kingdom's anti-wind lobby to demonstrate that intermittency and inaccuracies in wind forecasting make wind power ineffective and expensive. A further assertion is that most of the power is 'unwanted' since up to 80% of it is exported. Here, available data for Danish energy production for 2000-2004 is used to assess the link between wind generation and exports and test the validity of these claims. Net exports in Western Denmark showed good correlation with wind production. However, they were more significantly correlated with the production from local combined heat and power (CHP) plants. In order to test the 80% export claim, a simple technique was devised to correlate and rank hourly net exports and generation from wind and local CHP. In the case where net exports were primarily attributed to (or blamed on) wind, 44-84% of annual wind production was deemed to be exported, with wind 'causing' 57-79% of net annual exports. For this extreme scenario, the percentage values are in line with those of critics. However, under the opposite extreme scenario in which exports are attributed to local CHP, 77-94% of exports were caused by CHP and only 4-32% of wind production was exported. Overall, this study shows that there is some degree of correlation between net exports and wind power, but that the claim that 80% is exported is unwarranted since it ignores the demonstrably stronger influence of local CHP. (author)

IEA Wind Task 32: Wind lidar identifying and mitigating barriers to the adoption of wind lidar

DEFF Research Database (Denmark)

Clifton, Andrew; Clive, Peter; Gottschall, Julia

2018-01-01

IEA Wind Task 32 exists to identify and mitigate barriers to the adoption of lidar for wind energy applications. It leverages ongoing international research and development activities in academia and industry to investigate site assessment, power performance testing, controls and loads, and complex...... flows. Since its initiation in 2011, Task 32 has been responsible for several recommended practices and expert reports that have contributed to the adoption of ground-based, nacelle-based, and floating lidar by the wind industry. Future challenges include the development of lidar uncertainty models......, best practices for data management, and developing community-based tools for data analysis, planning of lidar measurements and lidar configuration. This paper describes the barriers that Task 32 identified to the deployment of wind lidar in each of these application areas, and the steps that have been...

Modeling of the dynamics of wind to power conversion including high wind speed behavior

DEFF Research Database (Denmark)

Litong-Palima, Marisciel; Bjerge, Martin Huus; Cutululis, Nicolaos Antonio

2016-01-01

This paper proposes and validates an efficient, generic and computationally simple dynamic model for the conversion of the wind speed at hub height into the electrical power by a wind turbine. This proposed wind turbine model was developed as a first step to simulate wind power time series...... for power system studies. This paper focuses on describing and validating the single wind turbine model, and is therefore neither describing wind speed modeling nor aggregation of contributions from a whole wind farm or a power system area. The state-of-the-art is to use static power curves for the purpose...... of power system studies, but the idea of the proposed wind turbine model is to include the main dynamic effects in order to have a better representation of the fluctuations in the output power and of the fast power ramping especially because of high wind speed shutdowns of the wind turbine. The high wind...

EDITORIAL: Wind energy

Science.gov (United States)

Mann, Jakob; Nørkær Sørensen, Jens; Morthorst, Poul-Erik

2008-01-01

Wind energy is rapidly growing. In 2006 the installed generating capacity in the world increased by 25%, a growth rate which has more or less been sustained during the last decade. And there is no reason to believe that this growth will slow significantly in the coming years. For example, the United Kingdom's goal for installed wind turbines by 2020 is 33 GW up from 2 GW in 2006, an average annual growth rate of 22% over that period. More than half of all turbines are installed in Europe, but United States, India and lately China are also rapidly growing markets. The cradle of modern wind energy was set by innovative blacksmiths in rural Denmark. Now the wind provides more than 20% of the electrical power in Denmark, the industry has professionalized and has close ties with public research at universities. This focus issue is concerned with research in wind energy. The main purposes of research in wind energy are to: decrease the cost of power generated by the wind; increase the reliability and predictability of the energy source; investigate and reduce the adverse environmental impact of massive deployment of wind turbines; build research based educations for wind energy engineers. This focus issue contains contributions from several fields of research. Decreased costs cover a very wide range of activities from aerodynamics of the wind turbine blades, optimal site selection for the turbines, optimization of the electrical grid and power market for a fluctuating source, more efficient electrical generators and gears, and new materials and production techniques for turbine manufacturing. The United Kingdom recently started the construction of the London Array, a 1 GW off-shore wind farm east of London consisting of several hundred turbines. To design such a farm optimally it is necessary to understand the chaotic and very turbulent flow downwind from a turbine, which decreases the power production and increases the mechanical loads on other nearby turbines. Also

Blown by the wind. Replacing nuclear power in German electricity generation

International Nuclear Information System (INIS)

Lechtenböhmer, Stefan; Samadi, Sascha

2013-01-01

to gradually reduce fossil fuel generated electricity. Whether the reduction in fossil fuel use will be sufficient to adequately contribute to national greenhouse gas mitigation targets significantly depends on an active policy to promote electricity savings, continuous efforts to increase the use of renewables and a higher share of natural gas (preferably used in combined heat and power plants) in fossil fuel power generation.

The AMPTE program's contribution to studies of the solar wind-magnetosphere-ionosphere interaction

International Nuclear Information System (INIS)

Sibeck, D.G.

1990-01-01

The Active Magnetospheric Particle Tracer Explorers (AMPTE) program provided important information on the behavior of clouds of plasma artificially injected into the solar wind and the earth's magnetosphere. Now that the releases are over, data from the satellites are being analyzed to investigate the processes by which the ambient solar wind mass, momentum, and energy are transferred to the magnetosphere. Work in progress at APL indicates that the solar wind is much more inhomogeneous than previously believed, that the solar wind constantly buffets the magnetosphere, and that ground observers may remotely sense these interactions as geomagnetic pulsations. 8 refs

Mitigating Wind Induced Truck Crashes

Science.gov (United States)

2009-12-25

Dangerous weather and high wind in particular, is a common contributing factor in truck crashes. High wind speeds have been documented as a perennial cause of truck crashes in Kansas and other Great Plains states. The possibility of reducing such cra...

Efficiency enhancement in IGCC power plants with air-blown gasification and hot gas clean-up

International Nuclear Information System (INIS)

Giuffrida, Antonio; Romano, Matteo C.; Lozza, Giovanni

2013-01-01

Air-blown IGCC systems with hot fuel gas clean-up are investigated. In detail, the gas clean-up station consists of two reactors: in the first, the raw syngas exiting the gasifier and passed through high-temperature syngas coolers is desulfurized by means of a zinc oxide-based sorbent, whereas in the second the sulfided sorbent is duly regenerated. The hot fuel gas clean-up station releases H 2 S-free syngas, which is ready to fuel the combustion turbine after hot gas filtration, and a SO 2 -laden stream, which is successively treated in a wet scrubber. A thermodynamic analysis of two air-blown IGCC systems, the first with cold fuel gas clean-up and the second with hot fuel gas clean-up, both with a state-of-the-art combustion turbine as topping cycle, shows that it is possible to obtain a really attractive net efficiency (more than 51%) for the second system, with significant improvements in comparison with the first system. Nevertheless, higher efficiency is accomplished with a small reduction in the power output and no sensible efficiency improvements seem to be appreciated when the desulfurization temperature increases. Other IGCC systems, with an advanced 1500 °C-class combustion turbine as the result of technology improvements, are investigated as well, with efficiency as high as 53%. - Highlights: ► Hot fuel gas clean-up is a highly favorable technology for IGCC concepts. ► Significant IGCC efficiency improvements are possible with hot fuel gas clean-up. ► Size reductions of several IGCC components are possible. ► Higher desulfurization temperatures do not sensibly affect IGCC efficiency. ► IGCC efficiency as high as 53% is possible with a 1500°C-class combustion turbine

Offshore wind farm repowering optimization

DEFF Research Database (Denmark)

Hou, Peng; Enevoldsen, Peter; Hu, Weihao

2017-01-01

is focused on optimization of offshore wind farm repowering, which is one option for the wind farm owner at end of life for the offshore wind farm. The LCoE is used as the evaluation index to identify whether it is economical to invest in such a way. In an optimized repowering strategy, different types...... of wind turbines are selected to replace the original wind turbines to reconstruct the wind farm, which is demonstrated to be better than the refurbishment approach which replaces the old wind turbines with the same type. The simulations performed in this research reveal that the reconstructed wind farm......, which consists of multiple types of wind turbine, has a smaller LCoE (10.43%) than the refurbishment approach, which shows the superiority of the proposed method. This research contributes an optimization tool to the wind industry, which consequently drives down the cost of energy produced by offshore...

The potential of wind farms

International Nuclear Information System (INIS)

Hauge Madsen, P.; Lundsager, P.

1992-09-01

Papers presented at the European wind energy conference on the potential of wind farms are presented. The aim of the conference was to bring into focus the problems, experiences and potential of the application of wind power in wind power farms as a contribution to the European and global energy supply. It was considered that the interchange of experience among representatives of science, utilities, industry, environment and energy planning, together with those who represent financial and insurance interests, would create a better understanding of all aspects of wind power for its future successful development. The subjects covered concern surveys of national planning and policies regarding wind energy utilization and national and global development of wind turbine arrays. The performance of some individual wind farms is described. Papers also deal with utility and project planning, wind prediction and certification, wind loads and fatigus, wakes, noise and control. (AB)

The potential of wind farms

International Nuclear Information System (INIS)

Hauge Madsen, P.; Lundsager, P.

1992-09-01

Papers presented at the European wind energy conference on the potential of wind farms are presented. The aim of the conference was to bring into focus the problems, experiences and potential of the application of wind power in wind power farms as a contribution to the European and global energy supply. It was considered that the interchange of experience among representatives of science, utilities, industry, environment and energy planning, together with those who represent financial and insurance interests, would create a better understanding of all aspects of wind power for its future successful development. The subjects covered concern surveys of national planning and policies regarding wind energy utilization and national and global development of wind turbine arrays. The performance of some individual wind farms is described. Papers also deal with utility and project planning, wind prediction and certification, wind loads and fatigues, wakes, noise and control. (AB)

Atitudes com relação à educação a distância em uma universidade Attitudes towards college education at a distance

Directory of Open Access Journals (Sweden)

Andrea Valéria Steil

2005-08-01

Full Text Available Este artigo descreve os resultados de uma pesquisa exploratória que investigou as atitudes de alunos com relação à educação a distância. A população-alvo foi de 22 alunos matriculados em uma disciplina a distância do curso Ciência da Computação de uma instituição de ensino superior do Sul do Brasil, oferecida no primeiro semestre de 2003. A pesquisa foi de natureza descritiva e aplicada, realizada sob uma perspectiva predominantemente quantitativa. Os resultados revelaram atitudes negativas dos alunos, especialmente nas categorias desempenho, flexibilidade e conveniência, preparação para a educação a distância, material didático e dinâmica de grupo na lista de discussão. Esses resultados indicam que o impacto positivo esperado da educação a distância pode não se efetivar quando a instituição desconsidera tanto a complexidade do processo educacional a distância quanto as variáveis envolvidas no processo de adoção e aceitação de inovações educacionais pelos alunos.The present article describes the results of an exploratory research in which the students' attitudes regarding education at the distance was investigated. The subjects of the study were 22 students enrolled in a discipline at the distance in the Computer Science undergraduate course. The course was offered in the first semester of 2003 in a college institution located in the South of Brazil. The research was of descriptive and applied nature, accomplished under a predominantly quantitative perspective. The results revealed the students' negative attitudes, especially towards the categories of performance, flexibility and convenience, preparation to the education at the distance, instructor-generated learning material, and group dynamics in the discussion list. These results suggest that the expected positive impact of the education at the distance may not be accomplished when the educational institution does not take into consideration the

20% Wind Energy by 2030: Increasing Wind Energy's Contribution to U.S. Electricity Supply; Executive Summary (Revised)

Energy Technology Data Exchange (ETDEWEB)

2008-12-01

This document is a 21-page summary of the 200+ page analysis that explores one clearly defined scenario for providing 20% of our nation's electricity demand with wind energy by 2030 and contrasts it to a scenario of no new U.S. wind power capacity.

Electrical Aspects of Wind Turbines

DEFF Research Database (Denmark)

Chen, Zhe; Blaabjerg, Frede

2009-01-01

This is the most authoritative single volume on offshore wind power yet published. Distinguished experts, mainly from Europe's leading universities, have contributed a collection of peer reviewed papers on the interfaces between wind power technology and marine engineering. The range of issues...

The transport sectors potential contribution to the flexibility in the power sector required by large-scale wind power integration

DEFF Research Database (Denmark)

Nørgård, Per Bromand; Lund, H.; Mathiesen, B.V.

2007-01-01

-scale integration of renewable energy in the power system – in specific wind power. In the plan, 20 % of the road transport is based on electricity and 20 % on bio- fuels. This, together with other initiatives allows for up to 55-60 % wind power penetration in the power system. A fleet of 0.5 mio electrical...... vehicles in Denmark in 2030 connected to the grid 50 % of the time represents an aggregated flexible power capacity of 1- 1.5 GW and an energy capacity of 10-150 GWh.......In 2006, the Danish Society of Engineers developed a visionary plan for the Danish energy system in 2030. The paper presents and qualifies selected part of the analyses, illustrating the transport sectors potential to contribute to the flexibility in the power sector, necessary for large...

Application of wind-profiling radar data to the analysis of dust weather in the Taklimakan Desert.

Science.gov (United States)

Wang, Minzhong; Wei, Wenshou; Ruan, Zheng; He, Qing; Ge, Runsheng

2013-06-01

The Urumqi Institute of Desert Meteorology of the China Meteorological Administration carried out an atmospheric scientific experiment to detect dust weather using a wind-profiling radar in the hinterland of the Taklimakan Desert in April 2010. Based on the wind-profiling data obtained from this experiment, this paper seeks to (a) analyze the characteristics of the horizontal wind field and vertical velocity of a breaking dust weather in a desert hinterland; (b) calculate and give the radar echo intensity and vertical distribution of a dust storm, blowing sand, and floating dust weather; and (c) discuss the atmosphere dust counts/concentration derived from the wind-profiling radar data. Studies show that: (a) A wind-profiling radar is an upper-air atmospheric remote sensing system that effectively detects and monitors dust. It captures the beginning and ending of a dust weather process as well as monitors the sand and dust being transported in the air in terms of height, thickness, and vertical intensity. (b) The echo intensity of a blowing sand and dust storm weather episode in Taklimakan is about -1~10 dBZ while that of floating dust -1~-15 dBZ, indicating that the dust echo intensity is significantly weaker than that of precipitation but stronger than that of clear air. (c) The vertical shear of horizontal wind and the maintenance of low-level east wind are usually dynamic factors causing a dust weather process in Taklimakan. The moment that the low-level horizontal wind field finds a shear over time, it often coincides with the onset of a sand blowing and dust storm weather process. (d) When a blowing sand or dust storm weather event occurs, the atmospheric vertical velocity tends to be of upward motion. This vertical upward movement of the atmosphere supported with a fast horizontal wind and a dry underlying surface carries dust particles from the ground up to the air to form blown sand or a dust storm.

Using rare earth elements to trace wind-driven dispersion of sediments from a point source

Science.gov (United States)

Van Pelt, R. Scott; Barnes, Melanie C. W.; Strack, John E.

2018-06-01

The entrainment and movement of aeolian sediments is determined by the direction and intensity of erosive winds. Although erosive winds may blow from all directions, in most regions there is a predominant direction. Dust emission causes the removal preferentially of soil nutrients and contaminants which may be transported tens to even thousands of kilometers from the source and deposited into other ecosystems. It would be beneficial to understand spatially and temporally how the soil source may be degraded and depositional zones enriched. A stable chemical tracer not found in the soil but applied to the surface of all particles in the surface soil would facilitate this endeavor. This study examined whether solution-applied rare earth elements (REEs) could be used to trace aeolian sediment movement from a point source through space and time at the field scale. We applied erbium nitrate solution to a 5 m2 area in the center of a 100 m diameter field 7854 m2 on the Southern High Plains of Texas. The solution application resulted in a soil-borne concentration three orders of magnitude greater than natively found in the field soil. We installed BSNE sampler masts in circular configurations and collected the trapped sediment weekly. We found that REE-tagged sediment was blown into every sampler mast during the course of the study but that there was a predominant direction of transport during the spring. This preliminary investigation suggests that the REEs provide a viable and incisive technique to study spatial and temporal variation of aeolian sediment movement from specific sources to identifiable locations of deposition or locations through which the sediments were transported as horizontal mass flux and the relative contribution of the specific source to the total mass flux.

A eficácia do treinamento auditivo formal em adultos com distúrbio do processamento auditivo (central

Directory of Open Access Journals (Sweden)

Ana Carolina Almendra Cruz

2013-12-01

Full Text Available OBJETIVO: comparar o desempenho de adultos com distúrbio do processamento auditivo em testes comportamentais pré e pós-treinamento auditivo formal, visando verificar a eficácia desse treinamento. MÉTODOS: trata-se de um estudo retrospectivo quantitativo com 18 indivíduos com distúrbio do processamento auditivo comprovado pela avaliação comportamental, idade entre 16 e 38 anos. Todos os indivíduos foram submetidos a um programa de treinamento auditivo formal realizado em oito sessões de 45 minutos cada, duas vezes por semana, cujas sessões foram organizadas em ordem crescente de complexidade visando o treinamento das habilidades auditivas de fechamento auditivo, figura-fundo para frases, palavras, sílabas e sons não verbais e de processamento temporal dos sons (análise da intensidade, duração e frequência dos sons. Foram comparados os resultados dos testes SSW em Português, SSI (MCI e Reconhecimento de Padrão de Duração e de Frequência obtidos no pré e pós - treinamento auditivo, envolvendo as variáveis: orelha e sexo. RESULTADOS: não foram observadas diferenças estatisticamente significantes entre as orelhas. Tanto homens quanto mulheres quando analisados separadamente demonstraram resultados melhores no pós-treinamento. Estas diferenças foram estatisticamente significantes nos testes de padrão de duração e frequência, para homens e mulheres. No SSW melhora no sexo masculino e no SSI R/S -15 no sexo feminino, respectivamente. Além disso, todos os indivíduos relataram melhor desempenho comunicativo e de atenção no pós-treinamento. CONCLUSÃO: o treinamento auditivo formal melhora as habilidades auditivas de figura - fundo para sons verbais e de processamento temporal medidas por testes comportamentais em adultos diagnosticados com distúrbio de processamento auditivo.

Winds of Change: How Black Holes May Shape Galaxies

Science.gov (United States)

2010-03-01

New observations from NASA's Chandra X-ray Observatory provide evidence for powerful winds blowing away from the vicinity of a supermassive black hole in a nearby galaxy. This discovery indicates that "average" supermassive black holes may play an important role in the evolution of the galaxies in which they reside. For years, astronomers have known that a supermassive black hole grows in parallel with its host galaxy. And, it has long been suspected that material blown away from a black hole - as opposed to the fraction of material that falls into it -- alters the evolution of its host galaxy. A key question is whether such "black hole blowback" typically delivers enough power to have a significant impact. Powerful relativistic jets shot away from the biggest supermassive black holes in large, central galaxies in clusters like Perseus are seen to shape their host galaxies, but these are rare. What about less powerful, less focused galaxy-scale winds that should be much more common? "We're more interested here in seeing what an "average"-sized supermassive black hole can do to its galaxy, not the few, really big ones in the biggest galaxies," said Dan Evans of the Massachusetts Institute of Technology who presented these results at the High Energy Astrophysics Division of the American Astronomical Society meeting in Kona, Hawaii. Evans and his colleagues used Chandra for five days to observe NGC 1068, one of the nearest and brightest galaxies containing a rapidly growing supermassive black hole. This black hole is only about twice as massive as the one in the center of our Galaxy, which is considered to be a rather ordinary size. The X-ray images and spectra obtained using Chandra's High Energy Transmission Grating Spectrometer (HETGS) showed that a strong wind is being driven away from the center of NGC 1068 at a rate of about a million miles per hour. This wind is likely generated as surrounding gas is accelerated and heated as it swirls toward the black hole. A

Performance of spanish wind turbines. Year 1995

International Nuclear Information System (INIS)

Lago, C.

1997-01-01

In this document we can find a statistical evaluation for the wind energy generation from each spanish wind farm referred to 1995 going on with the work that has been carried out since 1992, by initiative of the Wind Energy Division from Renewable Energy Institute. The purpose of this work is to contribute with interesting information for the wind environment and offer a global view from monthly performances of different wind farms. (Author)

Performance of spanish wind turbines. Year 1996

International Nuclear Information System (INIS)

Lago, C.

1998-01-01

In this document we can find a statistical evaluation for the wind energy generation from each spanish wind farm referred to 1996 going on with the work that has been carried out since 1992, by initiative of the Wind Energy Division from Renewable Energy Institute. The purpose of this work is to contribute with interesting information for the wind environment and offer a global view from monthly performances of different wind farms. (Author) 4 refs

El web 2.0 com a distòpia en la recent internet

Directory of Open Access Journals (Sweden)

Toni Cambra

2008-05-01

Full Text Available El terme web 2.0 ha passat a formar part recentment del llenguatge associat a internet. De semàntica imprecisa, vol capturar un moment en l'esdevenir de la xarxa en què l'usuari se n'erigeix en element dinamitzador central en virtut d'un augment de la seua capacitat d'expressió, interacció i participació, afavorit per certes tecnologies de recent aparició. No obstant això, certes veus i autors es mostren crítics amb la deriva actual, a la qual acusen de portar aparellada tota una sèrie d'efectes que, lluny de considerar-se desitjables, qüestionarien la idoneïtat evolutiva de la mateixa internet. Expressions com aplanament cultural, culte a l'amateur o intel·ligència col·lectiva (entesa aquesta pejorativament s'amalgamen per a envoltar el terme web 2.0 d'una aurèola de ressonàncies distòpiques. En aquest article es vol relativitzar part dels arguments esgrimits que constituirien aquesta visió distòpica del web 2.0, en situar la reflexió sobre internet en un horitzó de discussió alternatiu que ens permeta comprendre el fenomen sense sucumbir al pessimisme que hi pareix subjaure, d'acord amb la visió de tals autors. Lluny de pressuposar-hi un telos al qual hauria d'obeir-ne el desenvolupament, es defén una comprensió d'internet com a camp pragmàtic d'experimentació, que es legitima en tant que "camí" i no com a "destí" de cap esdevenir implícit o esperable. Text complet (PDF

IEA Wind Task 32: Wind Lidar Identifying and Mitigating Barriers to the Adoption of Wind Lidar

Directory of Open Access Journals (Sweden)

Andrew Clifton

2018-03-01

Full Text Available IEA Wind Task 32 exists to identify and mitigate barriers to the adoption of lidar for wind energy applications. It leverages ongoing international research and development activities in academia and industry to investigate site assessment, power performance testing, controls and loads, and complex flows. Since its initiation in 2011, Task 32 has been responsible for several recommended practices and expert reports that have contributed to the adoption of ground-based, nacelle-based, and floating lidar by the wind industry. Future challenges include the development of lidar uncertainty models, best practices for data management, and developing community-based tools for data analysis, planning of lidar measurements and lidar configuration. This paper describes the barriers that Task 32 identified to the deployment of wind lidar in each of these application areas, and the steps that have been taken to confirm or mitigate the barriers. Task 32 will continue to be a meeting point for the international wind lidar community until at least 2020 and welcomes old and new participants.

Percepção de distância em crianças durante a locomoção Distance perception in children while walking

Directory of Open Access Journals (Sweden)

Eliane Mauerberg-deCastro

2002-01-01

Full Text Available O objetivo do presente estudo foi investigar a percepção de crianças sobre distância na ausência de informação visual durante a locomoção. Ainda, se parâmetros biomecânicos relativos à locomoção são alterados durante a locomoção nas diferentes distâncias. Sete crianças na idade de 6 anos (GC e 10 adultos (GA foram convidados a andar vendados até alvos pré-estabelecidos. O expoente da função de potência e parâmetros biomecânicos (Ex.: duração da passada, proporção da passada e velocidade da passada foram obtidos para cada grupo. Diferenças foram encontradas somente para os valores de distância produzida ao longo das distâncias testadas. Nenhum dos parâmetros biomecânicos diferiu entre GC e GA. Alterações quantitativas foram observadas nos parâmetros biomecânicos para distâncias curtas, embora o padrão do movimento não tenha sido alterado. Crianças desta faixa etária demonstram, em tarefas não usuais (Ex.: locomoção sem visão, adaptabilidade e capacidade de orientar-se no espaço utilizando apenas da sensibilidade háptica e provavelmente da imagem mental-construída da observação feita antes da realização da tarefa sem informação visual.The purpose of this study was to investigate children's distance perception while walking blindfolded. Also, in order to measure differences at various distances, biomechanical parameters were assessed. Seven children, aged 6 (CG, and 10 adults (AG were asked to walk to previously seen targets placed at different distances. Exponent and biomechanical parameters (i.e., stride duration, stride proportion, and stride velocity were calculated for each group. The CG and AG exhibited similarities in biomechanical parameters, which for both groups changed with the length of the distance. We concluded that both children and adults used similar strategies to accomplish the distance perception task; that locomotion at short distances requires adaptations in gait patterns

Evaluation of Wind Farm Controller based Fault Detection and Isolation

DEFF Research Database (Denmark)

Odgaard, Peter Fogh; Shafiei, Seyed Ehsan

2015-01-01

detection and isolation and fault tolerant control has previously been proposed. Based on this model, and international competition on wind farm FDI was organized. The contributions were presented at the IFAC World Congress 2014. In this paper the top three contributions to this competition are shortly......In the process of lowering cost of energy of power generated by wind turbines, some focus has been drawn towards fault detection and isolation and as well as fault tolerant control of wind turbines with the purpose of increasing reliability and availability of the wind turbines. Most modern wind...

Contributions of solar-wind induced potential sputtering to the lunar surface erosion rate and it's exosphere

Science.gov (United States)

Alnussirat, S. T.; Barghouty, A. F.; Edmunson, J. E.; Sabra, M. S.; Rickman, D. L.

2018-04-01

Sputtering of lunar regolith by solar-wind protons and heavy ions with kinetic energies of about 1 keV/amu is an important erosive process that affects the lunar surface and exosphere. It plays an important role in changing the chemical composition and thickness of the surface layer, and in introducing material into the exosphere. Kinetic sputtering is well modeled and understood, but understanding of mechanisms of potential sputtering has lagged behind. In this study we differentiate the contributions of potential sputtering from the standard (kinetic) sputtering in changing the chemical composition and erosion rate of the lunar surface. Also we study the contribution of potential sputtering in developing the lunar exosphere. Our results show that potential sputtering enhances the total characteristic sputtering erosion rate by about 44%, and reduces sputtering time scales by the same amount. Potential sputtering also introduces more material into the lunar exosphere.

Development of advanced air-blown entrained-flow two-stage bituminous coal IGCC gasifier

Directory of Open Access Journals (Sweden)

Abaimov Nikolay A.

2017-01-01

Full Text Available Integrated gasification combined cycle (IGCC technology has two main advantages: high efficiency, and low levels of harmful emissions. Key element of IGCC is gasifier, which converts solid fuel into a combustible synthesis gas. One of the most promising gasifiers is air-blown entrained-flow two-stage bituminous coal gasifier developed by Mitsubishi Heavy Industries (MHI. The most obvious way to develop advanced gasifier is improvement of commercial-scale 1700 t/d MHI gasifier using the computational fluid dynamics (CFD method. Modernization of commercial-scale 1700 t/d MHI gasifier is made by changing the regime parameters in order to improve its cold gas efficiency (CGE and environmental performance, namely H2/CO ratio. The first change is supply of high temperature (900°C steam in gasifier second stage. And the second change is additional heating of blast air to 900°C.

Uma análise exploratória da jornada flexível de trabalho sob a perspectiva de tutores na educação a distância

OpenAIRE

Torres, Elvia Florêncio

2009-01-01

A Era da Informação vem proporcionando o desenvolvimento acelerado das tecnologias na docência, o que está viabilizando o aumento de cursos à distância e a flexibilidade na jornada de trabalho dos tutores. Nesse contexto, objetivou-se estudar a influência do trabalho flexível no desenvolvimento das atividades e na vida pessoal dos tutores na Educação à Distância da Universidade Federal do Rio Grande do Norte. Mais especificamente, buscou-se comparar os tipos de flexibilidade detectados; id...

The Impact of Variable Wind Shear Coefficients on Risk Reduction of Wind Energy Projects.

Science.gov (United States)

Corscadden, Kenneth W; Thomson, Allan; Yoonesi, Behrang; McNutt, Josiah

2016-01-01

Estimation of wind speed at proposed hub heights is typically achieved using a wind shear exponent or wind shear coefficient (WSC), variation in wind speed as a function of height. The WSC is subject to temporal variation at low and high frequencies, ranging from diurnal and seasonal variations to disturbance caused by weather patterns; however, in many cases, it is assumed that the WSC remains constant. This assumption creates significant error in resource assessment, increasing uncertainty in projects and potentially significantly impacting the ability to control gird connected wind generators. This paper contributes to the body of knowledge relating to the evaluation and assessment of wind speed, with particular emphasis on the development of techniques to improve the accuracy of estimated wind speed above measurement height. It presents an evaluation of the use of a variable wind shear coefficient methodology based on a distribution of wind shear coefficients which have been implemented in real time. The results indicate that a VWSC provides a more accurate estimate of wind at hub height, ranging from 41% to 4% reduction in root mean squared error (RMSE) between predicted and actual wind speeds when using a variable wind shear coefficient at heights ranging from 33% to 100% above the highest actual wind measurement.

Wind farm progress in Denmark

DEFF Research Database (Denmark)

Frandsen, Sten Tronæs; Andersen, Per Dannemand

1996-01-01

The paper presents a status of wind power in Denmark and on the technical and industrial achievements. The present total installed capacity is be the end of 1995 approx. 630 MW, and the contribution to the electric energy generation in Denmark is approx. 4%.......The paper presents a status of wind power in Denmark and on the technical and industrial achievements. The present total installed capacity is be the end of 1995 approx. 630 MW, and the contribution to the electric energy generation in Denmark is approx. 4%....

Distúrbios da aquisição da linguagem e da aprendizagem Language and learning disorders

Directory of Open Access Journals (Sweden)

Carolina R. Schirmer

2004-04-01

Full Text Available OBJETIVO: O objetivo deste artigo é instrumentalizar os profissionais da saúde, em especial o pediatra, para que possam agir no diagnóstico e na prevenção primária dos distúrbios de linguagem oral e escrita. FONTES DOS DADOS: Foi realizada revisão da literatura sobre o tema proposto na MEDLINE nos últimos 5 anos e foram incluídas referências de livros-texto considerados como base para a compreensão dos distúrbios da linguagem e do aprendizado na infância. SÍNTESE DOS DADOS: Sabe-se que as causas de alterações de linguagem e de dificuldades de aprendizagem podem ser variadas, apesar de existirem muitos estudos indicando fatores neurológicos para tais problemas. CONCLUSÃO: Ressalta-se a importância de uma adequada investigação buscando um correto diagnóstico para, então, direcionar o melhor tratamento indicado para cada caso.OBJECTIVE: To aid health professionals, especially pediatricians, in the diagnosis and prevention of language and learning disorders. SOURCES OF DATA: Review of the relevant literature published in the past 5 years (MEDLINE and textbooks. SUMMARY OF THE FINDINGS: Multiple variables, among them neurological diseases, may be related to the etiology of language and learning disorders. CONCLUSION: An adequate diagnostic investigation may guide the choice of treatment.

Eficácia do programa de treinamento auditivo em escolares com distúrbios de aprendizagem

OpenAIRE

Pinheiro, Fábio Henrique; Nunes, Cristiane Lima; Capellini, Simone Aparecida

2009-01-01

Objetivos: Verificar a eficácia terapêutica do programa de treinamento auditivo em escolares com distúrbio de aprendizagem. Método: Participaram deste estudo 40 escolares de 8 a 14 anos, de ambos os gêneros, de 2 a 4ª séries do ensino fundamental. Como procedimentos foram utilizados o Instrumento de Avaliação Seqüencial – CONFIAS e testes de avaliação do processamento auditivo e o programa Audio Training®. Conclusão: Os achados evidenciaram a eficácia do programa pela melhora o...

Numerical Model of Dephosphorization Reaction Kinetics in Top Blown Converter Coupled with Flow Field

Science.gov (United States)

Liu, Wei; Yang, Shufeng; Li, Jingshe; Wang, Minghui

2017-07-01

A 3D transient numerical model of dephosphorization kinetics coupled with flow field in a top blown converter was built. Through the model the dephosphorization reaction rate influenced by the oxygen jets and the steel flow were simulated. The results show that the dephosphorization rate at the droplet metal-slag interface is two orders of magnitude faster than that at bath metal-slag interface. When the lance oxygen pressure increases from 0.7 to 0.8 MPa, the dephosphorization rate increases notably and the end content of P has a decrease of 19 %. However, when the pressure continues rising to 0.9 MPa, the dephosphorization rate has no significant increase. In addition, the lance height shows a nearly linear relation to the end P content of steel, that the lower the height, the faster the dephosphorization rate.

MCMC for Wind Power Simulation

NARCIS (Netherlands)

Papaefthymiou, G.; Klöckl, B.

2008-01-01

This paper contributes a Markov chain Monte Carlo (MCMC) method for the direct generation of synthetic time series of wind power output. It is shown that obtaining a stochastic model directly in the wind power domain leads to reduced number of states and to lower order of the Markov chain at equal

Renewable energy policy and wind energy development in Germany

Energy Technology Data Exchange (ETDEWEB)

Zitzer, Suzanne E [UFZ - Umweltforschungszentrum Leipzig-Halle GmbH, Leipzig (Germany). Department Urban Ecology, Environmental Planing and Transport

2009-07-15

The author of the contribution under consideration reports on the renewable energy policy and wind energy development in the Federal Republic of Germany. First of all, the author describes the historical development of the renewable energy policy since the 1970ies. Then, the environmental policies of the Red-Green Coalition (till to 2005) and of the Grand Coalition (since 2005) as well as the Renewable Energy Sources Act are described. The next section of this contribution is concern to the development of wind energy in the Federal Republic of Germany under consideration of onshore wind energy and offshore wind energy.

Wind energy in Europe

International Nuclear Information System (INIS)

Evans, L.C.

1992-01-01

Wind energy should be an important part of the energy supply mix, both at home and abroad, to provide cleaner air and a more stable fuel supply. Not only can wind energy contribute to solving complex global issues, it also can provide a large market for American technological leadership. Even though utilities are paying more attention to wind in a number of states, there are no plans for major installations of wind power plants in the United States. At the same time, European nations have developed aggressive wind energy development programs, including both ambitious research and development efforts and market incentives. Many countries recognize the importance of the clean energy provided by wind technology and are taking steps to promote their fledgling domestic industries. The emphasis on market incentives is starting to pay off. In 1991, European utilities and developers installed nearly twice as much wind capacity as Americans did. In 1992 the gap will be even greater. This article reviews aggressive incentives offered by European governments to boost their domestic wind industries at home and abroad in this almost $1 billion per year market. By offering substantial incentives - considerably more than the American Wind Energy Association (AWEA) is proposing - European nations are ensuring dramatic near-term wind energy development and are taking a major step toward dominating the international wind industry of the 21st century

Revisiting the dispersion measure of fast radio bursts associated with gamma-ray burst afterglows

Energy Technology Data Exchange (ETDEWEB)

Yu, Yun-Wei, E-mail: yuyw@mail.ccnu.edu.cn [Institute of Astrophysics, Central China Normal University, Wuhan 430079 (China)

2014-12-01

Some fast radio bursts (FRBs) are expected to be associated with the afterglow emission of gamma-ray bursts (GRBs), while a short-lived, supermassive neutron star (NS) forms during the GRBs. I investigate the possible contributions to the dispersion measure (DM) of the FRBs from the GRB ejecta and the wind blown from the precollapsing NS. On the one hand, sometimes an internal X-ray plateau afterglow could be produced by the NS wind, which indicates that a great number of electron-positron pairs are carried by the wind. If the pair-generation radius satisfies a somewhat rigorous condition, the relativistic and dense wind would contribute a high DM to the associated FRB, which can be comparable to and even exceed the DM contributed by the intergalactic medium. On the other hand, if the wind only carries a Goldreich-Julian particle flux, its DM contribution would become negligible; meanwhile, the internal plateau afterglow would not appear. Alternatively, the FRB should be associated with a GRB afterglow produced by the GRB external shock, i.e., an energy-injection-caused shallow-decay afterglow or a normal single-power-law afterglow if the impulsive energy release of the GRB is high enough. In the latter case, the DM contributed by the high-mass GRB ejecta could be substantially important, in particular, for an environment of main-sequence stellar wind. In summary, a careful assessment on the various DM contributors could be required for the cosmological application of the expected FRB-GRB association. The future DM measurements of GRB-associated FRBs could provide a constraint on the physics of NS winds.

Revisiting the dispersion measure of fast radio bursts associated with gamma-ray burst afterglows

International Nuclear Information System (INIS)

Yu, Yun-Wei

2014-01-01

Some fast radio bursts (FRBs) are expected to be associated with the afterglow emission of gamma-ray bursts (GRBs), while a short-lived, supermassive neutron star (NS) forms during the GRBs. I investigate the possible contributions to the dispersion measure (DM) of the FRBs from the GRB ejecta and the wind blown from the precollapsing NS. On the one hand, sometimes an internal X-ray plateau afterglow could be produced by the NS wind, which indicates that a great number of electron-positron pairs are carried by the wind. If the pair-generation radius satisfies a somewhat rigorous condition, the relativistic and dense wind would contribute a high DM to the associated FRB, which can be comparable to and even exceed the DM contributed by the intergalactic medium. On the other hand, if the wind only carries a Goldreich-Julian particle flux, its DM contribution would become negligible; meanwhile, the internal plateau afterglow would not appear. Alternatively, the FRB should be associated with a GRB afterglow produced by the GRB external shock, i.e., an energy-injection-caused shallow-decay afterglow or a normal single-power-law afterglow if the impulsive energy release of the GRB is high enough. In the latter case, the DM contributed by the high-mass GRB ejecta could be substantially important, in particular, for an environment of main-sequence stellar wind. In summary, a careful assessment on the various DM contributors could be required for the cosmological application of the expected FRB-GRB association. The future DM measurements of GRB-associated FRBs could provide a constraint on the physics of NS winds.

Attitude and acceptance of offshore wind farms

DEFF Research Database (Denmark)

Ladenburg, Jacob; Möller, B.

2011-01-01

farms attributes on attitude towards offshore wind farms. The results point towards that the travel time and the attributes of the nearest offshore wind farm influence the attitude significantly. Travel time has mixed effects on the attitude, whilst offshore wind farms with many turbines generate more...... a novel contribution to this field. First of all, we give a thorough review of the studies that have analysed the relation between experience with wind turbines and attitude. In addition, we supplement the review by analysing the effect of travel distance to the nearest offshore wind farm and the wind...

Numerical Simulations of Multiphase Winds and Fountains from Star-forming Galactic Disks. I. Solar Neighborhood TIGRESS Model

Science.gov (United States)

Kim, Chang-Goo; Ostriker, Eve C.

2018-02-01

Gas blown away from galactic disks by supernova (SN) feedback plays a key role in galaxy evolution. We investigate outflows utilizing the solar neighborhood model of our high-resolution, local galactic disk simulation suite, TIGRESS. In our numerical implementation, star formation and SN feedback are self-consistently treated and well resolved in the multiphase, turbulent, magnetized interstellar medium. Bursts of star formation produce spatially and temporally correlated SNe that drive strong outflows, consisting of hot (T> 5× {10}5 {{K}}) winds and warm (5050 {{K}} 1 {kpc} from the midplane has mass and energy fluxes nearly constant with d. The hot flow escapes our local Cartesian box barely affected by gravity, and is expected to accelerate up to terminal velocity of {v}{wind}∼ 350{--}500 {km} {{{s}}}-1. The mean mass and energy loading factors of the hot wind are 0.1 and 0.02, respectively. For warm gas, the mean outward mass flux through d=1 {kpc} is comparable to the mean star formation rate, but only a small fraction of this gas is at velocity > 50 {km} {{{s}}}-1. Thus, the warm outflows eventually fall back as inflows. The warm fountain flows are created by expanding hot superbubbles at d< 1 {kpc}; at larger d neither ram pressure acceleration nor cooling transfers significant momentum or energy flux from the hot wind to the warm outflow. The velocity distribution at launching near d∼ 1 {kpc} is a better representation of warm outflows than a single mass loading factor, potentially enabling development of subgrid models for warm galactic winds in arbitrary large-scale galactic potentials.

IEA Wind TCP Task 26: Impacts of Wind Turbine Technology on the System Value of Wind in Europe

Energy Technology Data Exchange (ETDEWEB)

Lantz, Eric J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Riva, Alberto D [Ea Energy Analyses; Hethey, Janos [Ea Energy Analyses; Vitina, Aisma [Danish Energy Agency

2018-05-01

This report analyzes the impact of different land-based wind turbine designs on grid integration and related system value and cost. This topic has been studied in a number of previous publications, showing the potential benefits of wind turbine technologies that feature higher capacity factors. Building on the existing literature, this study aims to quantify the effects of different land-based wind turbine designs in the context of a projection of the European power system to 2030. This study contributes with insights on the quantitative effects in a likely European market setup, taking into account the effect of existing infrastructure on both existing conventional and renewable generation capacities. Furthermore, the market effects are put into perspective by comparing cost estimates for deploying different types of turbine design. Although the study focuses on Europe, similar considerations and results can be applied to other power systems with high wind penetration.

Wind Turbine Providing Grid Support

DEFF Research Database (Denmark)

2011-01-01

changing the operation of the wind turbine to a more efficient working point.; When the rotational speed of the rotor reaches a minimum value, the wind turbine enters a recovery period to re-accelerate the rotor to the nominal rotational speed while further contributing to the stability of the electrical......A variable speed wind turbine is arranged to provide additional electrical power to counteract non-periodic disturbances in an electrical grid. A controller monitors events indicating a need to increase the electrical output power from the wind turbine to the electrical grid. The controller...... is arranged to control the wind turbine as follows: after an indicating event has been detected, the wind turbine enters an overproduction period in which the electrical output power is increased, wherein the additional electrical output power is taken from kinetic energy stored in the rotor and without...

Wind resource characterization in the Arabian Peninsula

KAUST Repository

Yip, Chak Man Andrew; Gunturu, Udaya; Stenchikov, Georgiy L.

2015-01-01

Wind energy is expected to contribute to alleviating the rise in energy demand in the Middle East that is driven by population growth and industrial development. However, variability and intermittency in the wind resource present significant

Illustration of Modern Wind Turbine Ancillary Services

DEFF Research Database (Denmark)

Margaris, Ioannis D.; Hansen, Anca Daniela; Sørensen, Poul Ejnar

2010-01-01

Increasing levels of wind power penetration in modern power systems has set intensively high standards with respect to wind turbine technology during the last years. Security issues have become rather critical and operation of wind farms as conventional power plants is becoming a necessity as wind...... turbines replace conventional units on the production side. This article includes a review of the basic control issues regarding the capability of the Doubly Fed Induction Generator (DFIG) wind turbine configuration to fulfill the basic technical requirements set by the system operators and contribute...

Power reserve provision with wind farms. Grid integration of wind power

Energy Technology Data Exchange (ETDEWEB)

Gesino, Alejandro J.

2011-07-01

Wind power is, admittedly, different from other power technologies and integrating large amounts of it in the existing power systems is a challenge that requires innovative approaches to keep the sustainability of the power system operation. In the coming years its contribution to the system security will become mandatory as far as the trend goes towards more decentralized structures and an increase in complexity due to a higher number of market participants. This PhD addresses one of the fundamental ancillary services researching about a secure and flexible methodology for power reserve provision with wind farms. Based on the current needs and security standards of those highly developed European grid codes, a new model for power reserve provision with wind power is developed. This methodology, algorithms and variables are tested based on real scenarios from five German wind farm clusters. Finally, once the methodology for power reserve provision with wind power has been tested, real control capabilities from already installed wind farms in Germany and Portugal are analyzed. Their capabilities of following control commands as well as an error deviation analysis are also presented. (orig.)

Projected contributions of future wind farm development to community noise and annoyance levels in Ontario, Canada

International Nuclear Information System (INIS)

Whitfield Aslund, Melissa L.; Ollson, Christopher A.; Knopper, Loren D.

2013-01-01

Wind turbines produce sound during their operation; therefore, jurisdictions around the world have developed regulations regarding the placement of electricity generating wind farms with the intent of preventing unacceptable levels of ‘community noise’ in their vicinity. However, as survey results indicate that the relationship between wind turbine noise and annoyance may differ from noise-annoyance relationships for other common noise sources (e.g., rail, traffic), there are concerns that the application of general noise guidelines for wind turbines may lead to unacceptably high levels of annoyance in communities. In this study, previously published survey results that quantified wind turbine noise and self-reported annoyance were applied to the predicted noise levels (from turbines and transformers) for over 8000 receptors in the vicinity of 13 planned wind power developments in the province of Ontario, Canada. The results of this analysis indicate that the current wind turbine noise restrictions in Ontario will limit community exposure to wind turbine related noise such that levels of annoyance are unlikely to exceed previously established background levels of noise-related annoyance from other common noise sources. This provides valuable context that should be considered by policy-makers when evaluating the potential impacts of wind turbine noise on the community. -- highlights: •Wind turbine noise-annoyance relationship used to predict annoyance in Ontario. •Noise annoyance predicted to be <8% for non-participants <1 km from turbines. •Predicted levels of wind turbine noise annoyance similar to that from traffic noise. •Wind turbine noise annoyance not expected to exceed existing background levels

Wind Powering America

International Nuclear Information System (INIS)

Flowers, L.; Dougherty, P. J.

2001-01-01

At the June 1999 Windpower Conference, the Secretary of Energy launched the Office of Energy Efficiency and Renewable Energy's Wind Powering America (WPA) initiative. The goals of the initiative are to meet 5% of the nation's energy needs with wind energy by 2020 (i.e., 80,000 megawatts installed), to double the number of states that have more than 20 megawatts (MW) of wind capacity to 16 by 2005 and triple it to 24 by 2010, and to increase wind's contribution to Federal electricity use to 5% by 2010. To achieve the Federal government's goal, DOE would take the leadership position and work with its Federal partners. Subsequently, the Secretary accelerated the DOE 5% commitment to 2005. Achieving the 80,000 MW goal would result in approximately$60 billion investment and$1.5 billion of economic development in our rural areas (where the wind resources are the greatest). The purpose of this paper is to provide an update on DOE's strategy for achieving its goals and the activities it has undertaken since the initiative was announced

Las empresas multinivel como modelo distópico: estudio de representaciones sociales

Directory of Open Access Journals (Sweden)

Mónica Maisterrena González

2014-07-01

Full Text Available El presente estudio muestra las estrategias utilizadas por las empresas multinivel para ejercer un esquema homogéneo de representaciones sociales entre los asociados de las mismas. Se ha determinado la inevitabilidad de mantener un control "ideológico” sobre los asociados para el correcto funcionamiento de la empresa. La dinámica empresarial de estas compañías propone un modelo de satisfacción personal que debe ser transmitido y no puede ser cuestionado y que, por tanto, violenta la individualidad de los asociados. Se han utilizado, a manera de analogía, las novelas 1984 de George Orwell y Un mundo feliz de Aldous Huxley como modelos de una sociedad distópica que han sido llevadas a la práctica por las empresas multinivel.

The extreme carbon dioxide outburst at the Menzengraben potash mine 7 July 1953

DEFF Research Database (Denmark)

Hedlund, Frank Huess

2012-01-01

Carbon dioxide is an asphyxiant and an irritant gas. An extreme outburst of carbon dioxide took place 7 July 1953 in a potash mine in the former East Germany. During 25 min, a large amount of CO2 was blown out of the mine shaft with great force. It was wind still and concentrated CO2 accumulated....... It is concluded that 1100–3900 tonnes of CO2 were blown out of the mine shaft, possibly with intensities around 4 tonnes/s. It is also concluded that the large majority of the gas escaped as a near-vertical high-velocity jet with only little loss of momentum due to impingement. The release was modelled using...... histories to date include sudden releases of CO2 of up to 50 tonnes only, far too small to provide a suitable empirical perspective on predicted hazard distances for CCS projects. The 1953 outburst contributes to filling this gap....

76 FR 52008 - Keālia Pond National Wildlife Refuge (NWR) and Kakahai'a NWR, Maui County, HI; Draft...

Science.gov (United States)

2011-08-19

... control the most aggressive invasive species. Reduce midge swarms, wind-blown dust, and foul-smelling... the main pond recedes due to evaporation, trade winds disperse dust from the pond to the south... well, installing a water pump and distribution line, and repairing the electric panel. This alternative...

Towards a Reactive Power Oscillation Damping Controller for Wind Power Plant Based on Full Converter Wind Turbines

DEFF Research Database (Denmark)

Knüppel, Thyge; Kumar, Sathess; Thuring, Patrik

2012-01-01

In this paper a power oscillation damping controller (POD) based on modulation of reactive power (Q POD) is analyzed where the modular and distributed characteristics of the wind power plant (WPP) are considered. For a Q POD it is essential that the phase of the modulated output is tightly...... contributes to a collective response. This ability is shown with a 150 wind turbine (WT) WPP with all WTs represented, and it is demonstrated that the WPP contributes to the inter-area damping. The work is based on a nonlinear, dynamic model of the 3.6 MW Siemens Wind Power WT....... controlled to achieve a positive damping contribution. It is investigated how a park level voltage, reactive power, and power factor control at different grid strengths interact with the Q POD in terms of a resulting phase shift. A WPP is modular and distributed and a WPP Q POD necessitate that each WT...

Análise de distância genética entre acessos do gênero Psidium via marcadores ISSR

Directory of Open Access Journals (Sweden)

Názila Nayara Silva de Oliveira

2014-12-01

Full Text Available O objetivo deste trabalho foi avaliar a distância genética entre 37 acessos da espécie cultivada Psidium guajava, L. (goiaba e de araçás do gênero Psidium do banco de germoplasma da Universidade Estadual do Norte Fluminense (UENF, via marcadores moleculares ISSR. Nos 17 marcadores selecionados, foram obtidas 216 bandas polimórficas. Pelo método de agrupamento UPGMA, houve a formação de cinco principais grupos. Os acessos de araçá da espécie P. cattleyanum Sabine , ficaram alocados nos grupos I e II. No grupo II, foi observada, dentro da espécie P cattleyanum, maior proximidade com a goiabeira. No grupo III, ficou alocado o acesso da espécie P. guineense Sw (araçá-do-campo e dentre os araçás, foi o que ficou mais próximo da goiaba. Os genótipos de goiabeira ficaram alocados do grupo IV e V, confirmando sua alta divergência. Os marcadores moleculares foram eficientes em estimar a distância genética intra e interespecífica.

Análise da prática de tutores em cursos de educação a distância para adultos: Identificando requisitos para ambientes virtuais de ensino

OpenAIRE

Martins da Silva, Wilson

2009-01-01

A maioria dos estudos sobre Educação a Distância direciona sua atenção para o papel do aluno. O que está correto, pois atender às necessidades do aluno deve ser o objetivo principal do processo ensino-aprendizagem. No entanto, a crescente utilização de cursos a distância por adultos muitos desses alunos com idade, experiência profissional e postura diferente do aluno mais jovem traz à tona a necessidade de rever algumas práticas utilizadas na condução dos referidos curso...

Educação a Distância: análise das perspectivas e avanços da metodologia de ensino na construção do conhecimento

Directory of Open Access Journals (Sweden)

Ana Maria Teixeira Alves

2016-02-01

Full Text Available Este trabalho investiga a Educação a Distância (EAD a partir de sua metodologia de ensino e o processo de aprendizagem. A proposta do estudo foi a de analisar as perspectivas e avanços da metodologia de ensino a distância na construção do conhecimento discutindo perspectivas e cenários. A discussão foi estabelecida a partir de subsídios teóricos que debatem os aspectos metodológicos, didáticos e pedagógicos que envolvem o processo de ensino-aprendizagem com foco sob a modalidade de ensino a distância. Para a construção do conhecimento, isto é, para efetivar o processo educacional é necessário que metodologias de ensino tomem forma no contexto EAD, influenciando de forma positiva e qualitativa sua condução. Observa-se que a diversificação metodológica isolada não garante a efetivação do aprendizado, todavia uma parceria entre alunos e professores possibilita o protagonismo na produção de conhecimento significativo e concreto.

2016 Fee Wind energy directory

International Nuclear Information System (INIS)

2015-12-01

France is currently engaged in the energy transition where ambitious goals are at stake to allow the country to be one of the leading European countries in renewable energies. The cost of onshore wind is getting more and more competitive and for this reason, wind energy professionals are committed in contributing actively to reach the 32 % objective of renewable energies in the final energy consumption and 40 % of renewable energies in the electricity mix for 2030. 2014 was marked by a swift growth of the installed onshore wind energy, the positive trend is confirmed in 2015 with more than 500 MW connected to the grid in the first half of the year, corresponding to the annual forecast of 1,200 MW for 2015. Thanks to the energy transition law, operational policies will be implemented through the multi-annual energy programming (PPE- programmation pluriannuelle de l'energie). France will therefore continue increasing its development of renewable energies. This law will also allow France to develop offshore wind energy and to strengthen its position regarding wind energy: with an objective of 15 GW of fixed offshore wind energy and 6 GW of floating wind energy to be built in the 2030 horizon, the sector will be able to guarantee its development, especially in the current context of strong worldwide competition. Some 10,000 direct and indirect jobs are awaited for offshore wind energy on the national territory and wind energy professionals underline that the development of the offshore wind sector will contribute to the economic dynamism of the country. This sector is thus a job creating sector as confirmed in the figures of the wind employment monitor (observatoire de l'emploi) in France, recording a significant growth in 2013 with 10,800 jobs. This upward trend was confirmed in 2014. This proves the continuous commitment of the wind industry in seeing the success of the energy transition in France in a context marked by numerous energy and climate events

Grid support capabilities of wind turbines

DEFF Research Database (Denmark)

Michalke, Gabriele; Hansen, Anca Daniela

2013-01-01

Wind power has gained a significant penetration level in several power systems all over the world. Due to this reason modern wind turbines are requested to contribute to power system support. Power system operators have thus introduced grid codes, which specify a set of requirements for wind...... turbines, such as fault ride-through and reactive power supply during voltage sags. To date different wind turbine concepts exist on the market comprising different control features in order to provide ancillary services to the power system. In the first place the present chapter emphasizes the most...... important issues related to wind power grid integration. Then different wind turbine concepts are characterized and their grid support capabilities are analysed and compared. Simulation cases are presented in which the respective wind turbine concepts are subjected to a voltage dip specified in a grid code....

Simulations of large winds and wind shears induced by gravity wave breaking in the mesosphere and lower thermosphere (MLT) region

OpenAIRE

X. Liu; X. Liu; J. Xu; H.-L. Liu; J. Yue; W. Yuan

2014-01-01

Using a fully nonlinear two-dimensional (2-D) numerical model, we simulated gravity waves (GWs) breaking and their contributions to the formation of large winds and wind shears in the mesosphere and lower thermosphere (MLT). An eddy diffusion coefficient is used in the 2-D numerical model to parameterize realistic turbulent mixing. Our study shows that the momentum deposited by breaking GWs accelerates the mean wind. The resultant large background wind increases the GW's app...

Wind's share in global energy markets

International Nuclear Information System (INIS)

Madsen, B.T.

1997-01-01

The question of how great of a contribution wind power can really make to the world's energy needs is discussed. Emphasis up until recently has been mainly on improving wind turbine technology and siting practices as it is these that will provide an answer. The International Energy Agency predicts that world energy demand will increase by 30-50% by 2010. More countries than ever are either using wind power now or are preparing for its use. Wind power continues to improve its price competitiveness. There is enough wind to cover our energy needs many times over, according to some reports twice the world's electricity supply could be met by utilizing just 5-10% of areas identified as having average wind speeds of 5 m/s or greater - ignoring population centers, forests and specially protected areas. But a major limiting factor to utilizing the available wind resource is the established grid systems, which can only base 20% of supply on wind power. It is concluded that wind can contribute significantly to the world's energy needs in the next century and beyond. If wind, which has taken giant leaps in improving its competitiveness over the past 20 hears, can be a major energy contributor by early next century, other renewables such as solar and biomass might also evolve to become major contributors too. If so, renewables, including hydro, could conceivably cover 50% of our energy needs by the middle of the next century. Much will depend on decision-makers at the centers of power. For Europe and certain other areas of the world, policies governing cross-border trade of electricity as well as the framework for environmental protection related to energy production will determine the final outcome

Arremessar por cima do ombro e a distância percorrida pelo implemento Overarm throw and the distance traveled by the implement

Directory of Open Access Journals (Sweden)

Samuel Bento da Silva

2009-12-01

Full Text Available A habilidade de arremessar por cima do ombro tem sido bastante estudada, observando-se a velocidade do implemento, porém enquanto muitas tarefas têm como objetivo arremessar o mais longe possível, a distância percorrida pelo objeto ainda não tem sido investigada. O objetivo deste estudo foi verificar se existe relação entre o estágio de desenvolvimento motor nesta habilidade e a distância percorrida pelo implemento e observar diferenças entre os gêneros masculino e feminino; 50 crianças, com idade entre 7-8 anos, de ambos os gêneros, procedentes de Piracicaba - SP foram analisadas enquanto arremessavam uma bola de tênis de campo, o mais longe possível. Cada criança realizou três arremessos intercalados e foi filmada com duas câmeras mini DV, tanto em vista lateral quanto posterior, enquanto arremessava. O nível de desenvolvimento das crianças foi classificado, utilizando-se uma sequência de desenvolvimento e a distância percorrida pela bola foi registrada. Foi encontrada correlação significativa entre o nível do desenvolvimento e a distância atingida. Diferenças entre os gêneros foram observadas: os meninos encontravam-se em níveis desenvolvimentais mais avançados em todas as ações e alcançaram maiores distâncias. Assim, o nível de desenvolvimento desta habilidade mostrou-se importante para o alcance de seu objetivo (arremessar mais longe. Sugere-se que o nível de habilidade é influenciado pelo meio ambiente e que oportunidades de movimento devem ser providenciadas para auxiliar o desenvolvimento integral da criança.Overarm throwing skill has been widely studied regarding the farthest throwing distance analysing the velocity of the implement; however the object's distance has not been investigated. The aim of this study was to verify if there is a relationship between the skill development and the distance reached by the object and to observe differences between genders. Fifty children, ages 7-8 years, both

Modelos utilizados pela educação a distância: uma síntese centrada nas instituições de ensino superior brasileiras

Directory of Open Access Journals (Sweden)

Andreza Regina Lopes da Silva

2011-09-01

Full Text Available O artigo tem como objetivo apresentar os diferentes modelos de práticas de Educação a Distância utilizados pelas Instituições de Ensino Superior no Brasil. Para tanto, a metodologia utilizada caracteriza a pesquisa como teórico-empírico; já a sua abordagem classifica-se como quantitativa. A unidade de análise escolhida foi a totalidade das Instituições de Ensino Superior credenciadas pelo Ministério da Educação no ano de 2010, o que caracteriza o estudo como censitário para este universo. As análises foram realizadas com base em dados primários, adquiridos por meio de contatos realizados com as Instituições via sites, chats e emails. Como resultado, observa-se que, das Instituições credenciadas em 2010 para a modalidade da educação a distância, o modelo semipresencial é o mais utilizado, com 75%, seguido pelo virtual (14%, após o da tele-educação (7% e, por último, o híbrido (3%. Conclui-se que a educação a distância, em sua prática, vem assumindo um caráter multimidiático, haja vista que o modelo “hegemônico” utilizado pelas Instituições deste estudo possui, em seu cerne, tal característica.

Psicodiagnóstico compreensivo de crianças com distúrbios de conduta: aspectos psicodinâmicos

OpenAIRE

Ana Angelica Roncolato

2011-01-01

Essa pesquisa aborda o quadro psiquiátrico mais frequente na infância. O distúrbio de conduta é caracterizado por comportamento antissocial persistente com violação de normas sociais e direitos individuais. Os comportamentos antissociais podem surgir precocemente na infância ou na adolescência, e configuram quadro psiquiátrico de difícil tratamento. Fatores individuais, familiares e sociais influenciam no desenvolvimento e na persistência do comportamento antissocial, interagindo de forma com...

'Wind in motion'. The rough guide to wind energy development

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-07-15

This project, which will run from January 2005 to October 2005, aims to develop a promotional DVD to inform and reassure the public and specific audiences on controversial aspects of proposed new wind farms. The DVD would also be used as a tool to gain acceptance and contributions from bodies involved in wind energy developments. 'Wind in Motion' complements a number of other public relations campaigns being undertaken bor proposed by the Department of Trade and Industry (DTI) and the British Wind Energy Association (BWEA). The DVD would cover issues such as the impact of wind farms of wild birds, the visual impact of wind farms on the landscape, the impact on tourism in scenic areas, the impact of local house prices, the impact on local residents during the construction and operational phases, and comparisons with the capacity and efficiencies of other electricity generating systems such as coal, gas and nuclear. The project's objectives are to facilitate the deployment of wind energy by addressing information barriers and providing information to help industry with transferable skills to diversify in the supply chain. Work will include cataloguing the footage taken for the DVD to allow it to be made available to the industry and producing case studies of the benefits of skills transfer.

A Water Model Study on Mixing Behavior of the Two-Layered Bath in Bottom Blown Copper Smelting Furnace

Science.gov (United States)

Shui, Lang; Cui, Zhixiang; Ma, Xiaodong; Jiang, Xu; Chen, Mao; Xiang, Yong; Zhao, Baojun

2018-05-01

The bottom-blown copper smelting furnace is a novel copper smelter developed in recent years. Many advantages of this furnace have been found, related to bath mixing behavior under its specific gas injection scheme. This study aims to use an oil-water double-phased laboratory-scale model to investigate the impact of industry-adjustable variables on bath mixing time, including lower layer thickness, gas flow rate, upper layer thickness and upper layer viscosity. Based on experimental results, an overall empirical relationship of mixing time in terms of these variables has been correlated, which provides the methodology for industry to optimize mass transfer in the furnace.

Flow separation on wind turbines blades

NARCIS (Netherlands)

Corten, G.P.

2001-01-01

In the year 2000, 15GW of wind power was installed throughout the world, producing 100PJ of energy annually. This contributes to the total electricity demand by only 0.2%. Both the installed power and the generated energy are increasing by 30% per year world-wide. If the airflow over wind turbine

O ensino a distância e a falência da educação Distance learning and the demise of education

Directory of Open Access Journals (Sweden)

Maria Helena Souza Patto

2013-06-01

Full Text Available A partir da análise do discurso oficial em defesa do ensino superior a distância, identificam-se os silêncios que o estruturam. De um lado, esse discurso ignora a dimensão ideológica da ciência e da técnica; de outro, desconsidera a complexidade da relação pedagógica. A ausência de ambos os temas, tão fundamentais, faculta a defesa da aplicação de tecnologias de comunicação e de informação no processo educativo sem que sejam investigadas as consequências deletérias de tal procedimento sobre a formação do educando. O texto destaca a educação concebida como formação e a contrapõe à semi ou pseudoformação, nos termos de filósofos da Escola de Frankfurt. A partir de um exame da natureza das atividades previstas em cursos a distância, questiona-se a própria existência de um professor e de um aluno nessa modalidade de ensino, bem como de uma relação entre eles que garanta a formação ético-política de um educando atento às relações de poder presentes nas instituições sociais, no conhecimento científico e no exercício profissional. Tal estado de coisas demanda pesquisa sobre os resultados alcançados pelos cursos a distância, sobretudo por aqueles que se destinam à formação de professores.An analysis of the official discourse in defense of distance learning in higher education identifies the silences that structure it. On the one hand, such discourse ignores the ideological dimension of science and technique; on the other, it disregards the complexity of the pedagogical relation. The absence of such fundamental themes makes it possible to defend the application of communication and information technologies in the education process without investigating the deleterious consequences of such procedure upon the formation of those being educated. The present text emphasizes education as formation, and contrasts it with semi- or pseudo-formation as described by the philosophers of the Frankfurt School. Based

Wind Powering America

Energy Technology Data Exchange (ETDEWEB)

Flowers, L. (NREL); Dougherty, P. J. (DOE)

2001-07-07

At the June 1999 Windpower Conference, the Secretary of Energy launched the Office of Energy Efficiency and Renewable Energy's Wind Powering America (WPA) initiative. The goals of the initiative are to meet 5% of the nation's energy needs with wind energy by 2020 (i.e., 80,000 megawatts installed), to double the number of states that have more than 20 megawatts (MW) of wind capacity to 16 by 2005 and triple it to 24 by 2010, and to increase wind's contribution to Federal electricity use to 5% by 2010. To achieve the Federal government's goal, DOE would take the leadership position and work with its Federal partners. Subsequently, the Secretary accelerated the DOE 5% commitment to 2005. Achieving the 80,000 MW goal would result in approximately $60 billion investment and $1.5 billion of economic development in our rural areas (where the wind resources are the greatest). The purpose of this paper is to provide an update on DOE's strategy for achieving its goals and the activities it has undertaken since the initiative was announced.

Look at Use of Wind Energy

International Nuclear Information System (INIS)

Tolun, Suleyman

2006-01-01

Electricity from wind energy has expanded globally 43.4% in 2005. The goal of the contributing countries is to increase its share in electricity production to 20% in 2020-30 period. Incentives play an important role in promoting the wind energy in countries. As wind energy conversion technology is the most developed one among other renewable energies there is a chance of installing advanced technology turbines on windy sites of the country by precise evaluation of the source and technology it needs.

Doença de Lafora e distúrbios do movimento: relato de dois casos

Directory of Open Access Journals (Sweden)

QUADROS ANIBAL DE

2000-01-01

Full Text Available Relatamos dois casos de doença de Lafora que apresentaram distúrbios do movimento, ataxia cerebelar, disartria e fenômeno do "susto exagerado", como manifestações clínicas iniciais. Estes sintomas precederam as convulsões, mioclonias e a demência progressiva. O diagnóstico foi confirmado pela identificação de corpos de inclusão, PAS positivo, na biópsia de pele de ambos os casos. Os pacientes relatados apresentam uma progressão lenta da doença, o que é incomum, com longa sobrevida. A doença de Lafora deve sempre ser incluída entre as causas de ataxia lentamente progressiva associada com epilepsia.

China, Norway and offshore wind development. A win-win wind relationship?

Energy Technology Data Exchange (ETDEWEB)

Enslow, Rachel

2010-03-15

This study published by WWF Norway, outlines the status of offshore wind power development in China and looks at how the Norwegian offshore industry can contribute to speed it up. Today China is the world's fastest growing market for renewable energy. China's annual offshore wind energy generation potential is 11,000 TWh, similar to that of the North Sea. The study estimates that in the next decade China will install 30 GW of offshore wind energy generation capacity. This could mitigate 1.3 billion tons of CO{sub 2} over the 20 year asset lifetime (more than the total Norwegian emissions forecast over the same period). To unleash China's potential and speed up development of offshore wind energy production, however, bridges must to be built between stakeholders with the relevant experience and the best available technology and policy makers and project developers in China. This study puts forward possible ways for future cooperation between China and Norway - a country with a world leading offshore industry cluster - in order to leverage mutual strengths to upscale and commercialize offshore wind technology for the global market. (Author)

China, Norway and offshore wind development. A win-win wind relationship?

Energy Technology Data Exchange (ETDEWEB)

Enslow, Rachel

2010-03-15

This study published by WWF Norway, outlines the status of offshore wind power development in China and looks at how the Norwegian offshore industry can contribute to speed it up. Today China is the world's fastest growing market for renewable energy. China's annual offshore wind energy generation potential is 11,000 TWh, similar to that of the North Sea. The study estimates that in the next decade China will install 30 GW of offshore wind energy generation capacity. This could mitigate 1.3 billion tons of CO{sub 2} over the 20 year asset lifetime (more than the total Norwegian emissions forecast over the same period). To unleash China's potential and speed up development of offshore wind energy production, however, bridges must to be built between stakeholders with the relevant experience and the best available technology and policy makers and project developers in China. This study puts forward possible ways for future cooperation between China and Norway - a country with a world leading offshore industry cluster - in order to leverage mutual strengths to upscale and commercialize offshore wind technology for the global market. (Author)

Optimized Placement of Wind Turbines in Large-Scale Offshore Wind Farm using Particle Swarm Optimization Algorithm

DEFF Research Database (Denmark)

Hou, Peng; Hu, Weihao; Soltani, Mohsen

2015-01-01

With the increasing size of wind farm, the impact of the wake effect on wind farm energy yields become more and more evident. The arrangement of the wind turbines’ (WT) locations will influence the capital investment and contribute to the wake losses which incur the reduction of energy production....... As a consequence, the optimized placement of the wind turbines may be done by considering the wake effect as well as the components cost within the wind farm. In this paper, a mathematical model which includes the variation of both wind direction and wake deficit is proposed. The problem is formulated by using...... Levelized Production Cost (LPC) as the objective function. The optimization procedure is performed by Particle Swarm Optimization (PSO) algorithm with the purpose of maximizing the energy yields while minimizing the total investment. The simulation results indicate that the proposed method is effective...

Design and Tuning of Wind Power Plant Voltage Controller with Embedded Application of Wind Turbines and STATCOMs

DEFF Research Database (Denmark)

Petersen, Lennart; Kryezi, Fitim; Iov, Florin

2017-01-01

This study addresses a detailed design and tuning of a wind power plant voltage control with reactive power contribution of wind turbines and static synchronous compensators (STATCOMs). First, small-signal models of a single wind turbine and STATCOM are derived by using the state-space approach....... A complete phasor model of the entire wind power plant is constructed, being appropriate for voltage control assessment. An exemplary wind power plant located in the United Kingdom and the corresponding grid code requirements are used as a base case. The final design and tuning process of the voltage...... controller results in a guidance, proposed for this particular control architecture. It provides qualitative outcomes regarding the parametrisation of each individual control loop and how to adjust the voltage controller depending on different grid stiffnesses of the wind power plant connection...

Modelos utilizados pela educação a distância: uma síntese centrada nas instituições de ensino superior brasileiras

Directory of Open Access Journals (Sweden)

Andreza Regina Lopes da Silva

2011-06-01

Full Text Available http://dx.doi.org/10.5007/1983-4535.2011v4n3p153   O artigo tem como objetivo apresentar os diferentes modelos de práticas de Educação a Distância utilizados pelas Instituições de Ensino Superior no Brasil. Para tanto, a metodologia utilizada caracteriza a pesquisa como teórico-empírico; já a sua abordagem classifica-se como quantitativa. A unidade de análise escolhida foi a totalidade das Instituições de Ensino Superior credenciadas pelo Ministério da Educação no ano de 2010, o que caracteriza o estudo como censitário para este universo. As análises foram realizadas com base em dados primários, adquiridos por meio de contatos realizados com as Instituições via sites, chats e e-mails. Como resultado, observa-se que, das Instituições credenciadas em 2010 para a modalidade da educação a distância, o modelo semipresencial é o mais utilizado, com 75%, seguido pelo virtual (14%, após o da tele-educação (7% e, por último, o híbrido (3%. Conclui-se que a educação a distância, em sua prática, vem assumindo um caráter multimidiático, haja vista que o modelo “hegemônico” utilizado pelas Instituições deste estudo possui, em seu cerne, tal característica.

Educação a Distância: Contribuições da Modalidade para uma Qualificação Empreendedora

Directory of Open Access Journals (Sweden)

Ricardo Arruda Mauro

2017-12-01

Full Text Available O Brasil enfrenta inúmeras dificuldades no seu desenvolvimento relacionadas às questões sociais ligadas à fragilidade do processo educacional. O Empreendedorismo, além de cooperar para a promoção do crescimento econômico e da diminuição das desigualdades sociais, também ajuda na melhoria da qualidade de vida da população por meio do aumento da empregabilidade e de uma melhor distribuição de renda. A Educação a Distância (EaD é uma modalidade formativa tornando-se cada vez mais um instrumento funda­mental na ascensão de oportunidades para muitas pessoas. Assim sendo, acredita-se que ela demonstra ser uma modalidade de ensino que se ajusta às necessidades brasileiras, pois além de minimizar as distâncias, os isolamentos geográficos e as desigualdades sociais, pode também suprir a carência de formação educacional da população do país. O objetivo deste artigo é avaliar como o Capital Humano dos egressos qualificados pela EaD proporciona uma maior capacidade para exercer atividades empreendedoras a partir de uma pesquisa de campo realizada com alunos egressos dos cursos de Pós-Graduação Lato Sensu de uma instituição de ensino superior privada do interior do Estado de São Paulo. Os sujeitos da pesquisa foram 712 alunos egressos dos 190 cursos de Pós-graduação Lato Sensu – Nível de Especialização da instituição de ensino na modalidade à distância, concluintes no período de 2011 até maio de 2016. Os resultados coletados permitiram concluir que a EaD contribui para que o indivíduo, após capacitado por esta modalidade, se torne um profissional participativo na criação de soluções estratégicas para os problemas e necessidades da sociedade.

Case study of the constraints and potential contributions regarding wind curtailment in Northeast China

DEFF Research Database (Denmark)

Xiong, Weiming; Wang, Yu; Mathiesen, Brian Vad

2016-01-01

The wind power industry in China is faced with the obstacle of ineffective use due to severe wind curtailment recently. With detailed representation of the electricity and heat sectors in an energy-system-modeling tool, we evaluated the potential of technical improvements that could be implemented...

A atuação do docente tutor na Educação a Distância

Directory of Open Access Journals (Sweden)

Regina Maria Dutra

2015-06-01

Full Text Available A Educação a Distância (EAD sofreu novo impulso com o surgimento das novas tecnologias de informação e comunicação (TICs, que com a Internet tornou possível o aparecimento de formas alternativas de geração e distribuição do conhecimento. Essa nova modalidade de ensino vem crescendo sistematicamente no interior do país, principalmente nos locais onde não existem instituições de Ensino Superior para atender a demanda local e regional. Com o advento da EAD tornou-se necessário o emprego de inúmeras ferramentas tecnológicas que possibilitam a diminuição da distância física. Entretanto, as tecnologias não são suficientes para que a aprendizagem dos alunos seja eficaz. Sabe-se que educar requer a presença de um profissional que garanta o efetivo e legítimo processo de aprendizagem. Na EAD esse profissional é o docente tutor, do qual precisamos conhecer a função, prática e papel dentro desse sistema. Nesse sentido, este artigo tem como objetivo central discutir o papel do docente tutor presencial na EAD, evidenciando sua relevância social, identificando os aspectos que facilitam ou causam entraves para execução de sua função, além de discutir o papel da tutoria na EAD.

Development of standardized air-blown coal gasifier/gas turbine concepts for future electric power systems

Energy Technology Data Exchange (ETDEWEB)

Sadowski, R.S.; Brown, M.J.; Harriz, J.T.; Ostrowski, E.

1991-01-01

The cost estimate provided for the DOE sponsored study of Air Blown Coal Gasification was developed from vendor quotes obtained directly for the equipment needed in the 50 MW, 100 MW, and 200 MW sized plants and from quotes from other jobs that have been referenced to apply to the particular cycle. Quotes were generally obtained for the 100 MW cycle and a scale up/down factor was used to generate the cost estimates for the 200 MW and 50 MW cycles, respectively. Information from GTPro (property of Thermoflow, Inc.) was used to estimate the cost of the 200 MW and 50 MW gas turbine, HRSG, and steam turbines. To available the use of GTPro's estimated values for this equipment, a comparison was made between the quotes obtained for the 100 MW cycle (ABB GT 11N combustion turbine and a HSRG) against the estimated values by GTPro.

Antimicrobial Activity of Nisin and Natamycin Incorporated Sodium Caseinate Extrusion-Blown Films: A Comparative Study with Heat-Pressed/Solution Cast Films.

Science.gov (United States)

Colak, Basak Yilin; Peynichou, Pierre; Galland, Sophie; Oulahal, Nadia; Prochazka, Frédéric; Degraeve, Pascal

2016-05-01

Antimicrobial edible films based on sodium caseinate, glycerol, and 2 food preservatives (nisin or natamycin) were prepared by classical thermomechanical processes. Food preservatives were compounded (at 65 °C for 2.5 min) with sodium caseinate in a twin-screw extruder. Anti-Listeria activity assays revealed a partial inactivation of nisin following compounding. Thermoplastic pellets containing food preservatives were then used to manufacture films either by blown-film extrusion process or by heat-press. After 24 h of incubation on agar plates, the diameters of K. rhizophila growth inhibition zones around nisin-incorporated films prepared by solution casting (control), extrusion blowing or heat pressing at 80 °C for 7 min of nisin-containing pellets were 15.5 ± 0.9, 9.8 ± 0.2, and 8.6 ± 1.0 mm, respectively. Since heat-pressing for 7 min at 80 °C of nisin-incorporated pellets did not further inactivate nisin, this indicates that nisin inactivation during extrusion-blowing was limited. Moreover, the lower diameter of the K. rhizophila growth inhibition zone around films prepared with nisin-containing pellets compared to that observed around films directly prepared by solution casting confirms that nisin inactivation mainly occurred during the compounding step. Natamycin-containing thermoplastic films inhibited Aspergillus niger growth; however, by contrast with nisin-containing films, heat-pressed films had higher inhibition zone diameters than blown films, therefore suggesting a partial inactivation of natamycin during extrusion-blowing. © 2016 Institute of Food Technologists®

Pela possibilidade do uso de novas metáforas na pesquisa transcultural: menos distância e mais fricção

Directory of Open Access Journals (Sweden)

Ana Celano

Full Text Available A metáfora da distância cultural vem dominando a área de estudos transculturais há mais de quatro décadas por meio de uma visão centrada, sobretudo, no interesse econômico e nas diferenças culturais entre países. O uso dessa metáfora se fundamenta em epistemologia positivista e adota lentes de uma visão estreita; embora, paradoxalmente, seja aplicada à área internacional. O objetivo deste artigo é problematizar os argumentos de Shenkar (2001; 2008 e Luo e Shenkar (2007, segundo os quais a metáfora de "distância" não é apropriada para compreensão, descrição e análise do impacto da questão cultural em negócios internacionais. Propõe-se, aqui, sua substituição pela metáfora da "fricção cultural", que captura de forma mais legítima a essência das questões transculturais aplicadas aos fenômenos em negócios internacionais.

Educação Superior à Distância: a qualidade passa pela avaliação

OpenAIRE

Castanheira, Nelson Pereira; Centro Integrado de Educação, Ciência e Tecnologia

2012-01-01

Na última década, houve um aumento na oferta de vagas no ensino superior no Brasil,  com a implantação de cursos superiores na modalidade de educação a distância (EaD). Cabe frisar o desenvolvimento de tecnologias educacionais como ferramenta didática e operacional neste processo. Assim, este artigo versa sobre as transformações que ocorreram e as perspectivas futuras sobre a EaD. Os dados a serem apresentados vislumbram o crescimento desta modalidade de ensino, que vêm permitindo às Institui...

Influence of local wind speed and direction on wind power dynamics – Application to offshore very short-term forecasting

DEFF Research Database (Denmark)

Gallego, Cristobal; Pinson, Pierre; Madsen, Henrik

2011-01-01

Wind power time series usually show complex dynamics mainly due to non-linearities related to the wind physics and the power transformation process in wind farms. This article provides an approach to the incorporation of observed local variables (wind speed and direction) to model some of these e......Wind power time series usually show complex dynamics mainly due to non-linearities related to the wind physics and the power transformation process in wind farms. This article provides an approach to the incorporation of observed local variables (wind speed and direction) to model some...... on one-step ahead forecasting and a time series resolution of 10 min. It has been found that the local wind direction contributes to model some features of the prevailing winds, such as the impact of the wind direction on the wind variability, whereas the non-linearities related to the power...... transformation process can be introduced by considering the local wind speed. In both cases, conditional parametric models showed a better performance than the one achieved by the regime-switching strategy. The results attained reinforce the idea that each explanatory variable allows the modelling of different...

Worldwide potential of wind energy

Energy Technology Data Exchange (ETDEWEB)

Flavin, C

1982-01-01

A well-documented discussion is presented dealing with the worldwide potential of wind energy as a source of electrical and mechanical power. It is pointed out that 2% of the solar insolation is converted to wind kinetic energy; it is constantly renewed and nondepletable. Efficiency of windmills are discussed (20 to 40%) and payback periods of less than 5 years are cited. Effects of wind velocity and site location are described. Wind pumps are reviewed and the need for wind pumps, particularly in the developing countries is stressed. The generation of electricity by windmills using small turbines is reviewed and appears promising in areas with wind velocities greater than 12 mi/hr. The development of large windmills and groups of windmills (windfarms) for large scale electrical power is discussed, illustrated, and reviewed (offshore sites included). Environmental and safety problems are considered as well as the role of electrical utilities, government support and research activities. It is concluded that the potential contribution of wind energy is immense and that mechanical windmills may become one of the most important renewable technologies. Electrical generating potential is estimated at 20 to 30% of electrical needs. International programs are discussed briefly. 57 references. (MJJ)

Life cycle assessment of offshore and onshore sited wind farms

Energy Technology Data Exchange (ETDEWEB)

NONE

2004-10-15

This report makes up the final reporting for the project 'Life cycle assessment (LCA) of turbines Analysis of possibilities of product directed environmental optimisation'. The purpose of the project is to carry through a life cycle assessment of an offshore wind farm and an onshore wind farm, respectively, as a basis for assessment of environmental improvement possibilities for wind farms through their life cycles. Likewise, the results are used to elaborate an environmental declaration of contents for power delivered to the grid from both types of wind farms. The project states the environmental impact for electricity produced at Horns Reef offshore wind farm and Tjaereborg onshore wind farm, respectively, as representatives for contemporary Danish offshore wind farms and onshore wind farms, respectively. Tjaereborg onshore wind farm is placed at an utmost favourably location with regard to wind, which means that the production at this wind farm is high compared with other onshore wind farms in Denmark. The high production rate is a factor that is taken into account when assessing the impact on the environment emanating from this wind farm. The results of the environmental life cycle assessments that have been carried out for the two wind farms do not show significant variance. If it is taken into account that Tjaereborg onshore wind farm is placed utmost favourably, the comparison shows that power from an average located onshore wind farm would have a more adverse or corresponding environmental impact as an unfavourably located offshore wind farm. The results show that it is the turbines that causes the largest environmental impact and not to a very high extent the transmission grid. For the turbines, the all-important environmental contribution comes from manufacturing and removal of the turbines, as it is the materials that cause the large environmental strain. The operation of the wind farms gives practically no contribution to the total

Educacão a distância e inovacão tecnológica

OpenAIRE

Belloni,Maria Luiza

2005-01-01

A crescente integração das Tecnologias de Informação e Comunicação (TIC) aos processos de comunicação e educação torna necessária a concepção de novas formas de se organizar e ofertar o ensino. Neste contexto, o presente artigo aborda a educação a distância (Ead) apontando para os riscos implicados em se confundir inovação técnica com inovação pedagógica e destacando a importância de se transferir o foco da discussão sobre a EaD da 'modalidade' para o 'método', da organização do ensino para o...

Wind turbine supply in Canada

International Nuclear Information System (INIS)

Snodin, H.

2007-01-01

This study reported on wind turbine supplies to the Canadian market. The report was written to address concerns for Canada's supply outlook in the near future due to the booming wind energy market. Turbine shortages have arisen as a result of continued growth in both European and North American markets. Long lead-times on turbine orders are now increasing the pressure to lock in turbine supply during the initial phases of the development process. Future growth of the wind energy industry will be impacted if turbine supply difficulties continue to contribute to uncertainties in the development process. The report provided an overview of the North American and global wind energy markets, as well as a summary of telephone interviews conducted with turbine suppliers. The implications for the future of turbine supply to the Canadian market were also analyzed. It was concluded that policy-makers should focus on supporting the expansion of manufacturing facilities for small wind turbines and control infrastructure in Canada 7 refs., 3 figs

In the wind of change. The wind power as pacesetters and guide to a fast turn to renewable energies; Im Wind des Wandels. Die Windkraft als Schrittmacher und Wegweiser zu einer schnellen Wende zu Erneuerbaren Energien

Energy Technology Data Exchange (ETDEWEB)

Scheer, H.; Alt, F.

2007-07-01

All renewable energy potentials (water power, bioenergy, wave power, geothermal energy) clearly are widespread as oil, natural gas, coal or uranium. For these potentials there are natural, spatial restrictions. In contrast to this, there exist any spatial restrictions for solar power and wind force. Under this aspect, the author of the contribution under consideration reports on wind force as a pacesetter and guide to a fast turn to renewable energy. Solar energy and wind energy have two crucial advantages of realizations: (a) The solar power plants and wind power plants can be installed faster than all other plants for generation of electrical power; (b) Solar power plants and wind power plants enable a radical shortening and simplification for the power supply. The generation and supply of electricity from solar power and wind power are also economically undefeatable. It is not a utopia to increase the contribution of the wind energy at the German power generation on basis of the renewable energy law in few years on over 40 %. The thesis, a further development of the wind power only is possible with offshore installations, because no suitable locations are present in the inland, is not correct. The emphasis of the use of wind power must remain with onshore plants. A broad dispersion of wind power plants should have priority, because the grid entrance is more easily realizable. The political attention must be directed toward the overcoming of the permission obstacles. Wind energy enables the passing of electricity from the shade of atomic and fossil power supply.

Statement on Wind Power

Energy Technology Data Exchange (ETDEWEB)

2010-01-15

Wind power will grow in importance in future electricity supply. In the next few decades it will to some degree replace fossil power but it will, at the same time also depend on fossil-b beyond, when wind power is expected to have a substantial share of the electricity market, CO{sub 2} emission-free electricity plants that are well suited for balancing the wind intermittency will be required. Predictions of the future penetration of wind power into the electricity market are critically dependent on a number of policy measures and will be especially influenced by climate driven energy policies. Very large investments will also be necessary as is shown by the lEA's Blue Map Scenario which includes 5,000 TWh wind electricity by 2050 at a cost of USD 700 billion. This implies an average 8% increase of wind electricity per year energy system, i.e. an energy system so large that it affects the entire world. The Energy Committee's scenario for electricity production in the year 2050 includes 5,000 TWh wind electricity out of a total of 45,000 TWh. Wind electricity thus has a within presently reached penetration of wind energy in a single country and within the calculated future projections of its penetration. Future large continental and intercontinental power grids may enable higher penetrations of wind energy since contributions of wind power from a larger area will tend to reduce its intermittency. Also, large-scale storage systems (thermal storage as is intermittent power systems. These alternatives have been discussed from a technical point of view [3] but for the required large-scale systems, further studies on the social, environmental and economical implications are needed

Establishing an In-House Wind Maintenance Program

Energy Technology Data Exchange (ETDEWEB)

None

2011-12-01

Update to the 2008 guidebook titled “Establishing an In-house Wind Maintenance Program”, which was developed to support utilities in developing O&M strategies. This update includes significant contributions from utilities and other stakeholders around the country, representing all perspectives and regardless of whether or not they own wind turbines or projects.

A water blown urethane insulation for use in cryogenic environments

Science.gov (United States)

Blevins, Elana; Sharpe, Jon

1995-01-01

Thermal Protection Systems (TPS) of NASA's Space Shuttle External Tank include polyurethane and polyisocyanurate modified polyurethane foam insulations. These insulations, currently foamed with CFC 11 blowing agent, serve to maintain cryogenic propellant quality, maintain the external tank structural temperature limits, and minimize the formation of ice and frost that could potentially damage the ceramic insulation on the space shuttle orbiter. During flight the external tank insulations are exposed to mechanical, thermal and acoustical stresses. TPS must pass cryogenic flexure and substrate adhesion tests at -253 C, aerothermal and radiant heating tests at fluxes up to approximately 14 kilowatts per square meter, and thermal conductivity tests at cryogenic and elevated temperatures. Due to environmental concerns, the polyurethane insulation industry and the External Tank Project are tasked with replacing CFC 11. The flight qualification of foam insulations employing HCFC 141b as a foaming agent is currently in progress; HCFC 141b blown insulations are scheduled for production implementation in 1995. Realizing that the second generation HCFC blowing agents are an interim solution, the evaluation of third generation blowing agents with zero ozone depletion potential is underway. NASA's TPS Materials Research Laboratory is evaluating third generation blowing agents in cryogenic insulations for the External Tank; one option being investigated is the use of water as a foaming agent. A dimensionally stable insulation with low friability, good adhesion to cryogenic substrates, and acceptable thermal conductivity has been developed with low viscosity materials that are easily processed in molding applications. The development criteria, statistical experimental approach, and resulting foam properties will be presented.

Wake Measurement Downstream of a Hybrid Wing Body Model with Blown Flaps

Science.gov (United States)

Lin, John C.; Jones, Gregory S.; Allan, Brian G.; Westra, Bryan W.; Collins, Scott W.; Zeune, Cale H.

2010-01-01

Flow-field measurements were obtained in the wake of a full-span Hybrid Wing Body model with internally blown flaps. The test was performed at the NASA Langley 14 x 22 Foot Subsonic Tunnel at low speeds. Off-body measurements were obtained with a 7-hole probe rake survey system. Three model configurations were investigated. At 0deg angle of attack the surveys were completed with 0deg and 60deg flap deflections. At 10deg angle of attack the wake surveys were completed with a slat and a 60deg flap deflection. The 7-hole probe results further quantified two known swirling regions (downstream of the outboard flap edge and the inboard/outboard flap juncture) for the 60deg flap cases with blowing. Flowfield results and the general trends are very similar for the two blowing cases at nozzle pressure ratios of 1.37 and 1.56. High downwash velocities correlated with the enhanced lift for the 60deg flap cases with blowing. Jet-induced effects are the largest at the most inboard station for all (three) velocity components due in part to the larger inboard slot height. The experimental data are being used to improve computational tools for high-lift wings with integrated powered-lift technologies.

Sleep disorders are associated with impulsivity in school children aged 8 to 10 years Distúrbios de sono associam-se com impulsividade em escolares de 8 a 10 anos de idade

Directory of Open Access Journals (Sweden)

Marilaine Medeiros

2005-09-01

Full Text Available CONTEXT: Sleep has an important function in the physical and emotional development of children. Some studies suggest an association between impulsivity and sleep disorders. However, little is known about this association in schoolchildren aged 8 to 10 years. METHOD: We studied 1180 children, 547 with sleep disorders (SD and 633 without SD (control group, classified with SD questionnaires. Within the SD group, 53 children with sleep-related respiratory disorders (SRRD and 521 children with non-respiratory sleep disorders (NRSD were analyzed. We acessed emotional indicators of impulsivity with Bender test. RESULTS: More SD children presented impulsivity than control group (pCONTEXTO: O sono tem função importante no desenvolvimento físico e emocional das crianças. Alguns estudos sugerem a associação de impulsividade e distúrbios do sono, sendo pouco conhecida esta associação em escolares na faixa etária de 8 a 10 anos. MÉTODO: Estudamos 1180 crianças, 547 com distúrbio do sono (DS e 633 normais (grupo controle, classificadas através de questionários sobre distúrbios do sono. Dentro do grupo DS, analisamos separadamente as crianças com distúrbio respiratório relacionado ao sono (DRRS e com distúrbios não respiratórios do sono (DNRS. Aplicamos o Teste Gestáltico de Bender (TB para detectar os indicadores emocionais de impulsividade. RESULTADOS: Maior número de crianças com DS apresentaram impulsividade em relação às crianças do grupo controle (p<0,05. Mais crianças de 10 anos de idade do grupo DNRS apresentaram impulsividade em relação ao grupo controle da mesma idade (p=0,001. Impulsividade e DRRS estiveram associados apenas entre as crianças de 8 anos de idade (p<0,05. CONCLUSÃO: Crianças com DS em geral, crianças com DRRS de 8 anos de idade, e crianças com 10 anos de idade do grupo DNRS apresentaram maior proporção de indicadores de impulsividade do que crianças do grupo controle.

Distributed Wind Market Applications

Energy Technology Data Exchange (ETDEWEB)

Forsyth, T.; Baring-Gould, I.

2007-11-01

Distributed wind energy systems provide clean, renewable power for on-site use and help relieve pressure on the power grid while providing jobs and contributing to energy security for homes, farms, schools, factories, private and public facilities, distribution utilities, and remote locations. America pioneered small wind technology in the 1920s, and it is the only renewable energy industry segment that the United States still dominates in technology, manufacturing, and world market share. The series of analyses covered by this report were conducted to assess some of the most likely ways that advanced wind turbines could be utilized apart from large, central station power systems. Each chapter represents a final report on specific market segments written by leading experts in this field. As such, this document does not speak with one voice but rather a compendium of different perspectives, which are documented from a variety of people in the U.S. distributed wind field.

Optimal wind energy penetration in power systems: An approach based on spatial distribution of wind speed

International Nuclear Information System (INIS)

Zolfaghari, Saeed; Riahy, Gholam H.; Abedi, Mehrdad; Golshannavaz, Sajjad

2016-01-01

Highlights: • Chronological wind speeds at distinct locations of the wind farm are not the same. • Spatial distribution of wind speed affects wind farm’s output power expectation. • Neglecting wind speed’s spatial doubt leads to mistake in wind energy penetration. • Scenario-based method can be used for effective wind capacity penetration level. - Abstract: Contributing in power system expansions, the present study establishes an efficient scheme for optimal integration of wind energy resources. The proposed approach highly concerns the spatial distribution of wind speed at different points of a wind farm. In mathematical statements, a suitable probability distribution function (PDF) is well-designed for representing such uncertainties. In such conditions, it is likely to have dissimilar output powers for individual and identical wind turbines. Thus, the overall aggregated PDF of a wind farm remarkably influences the critical parameters including the expected power and energy, capacity factor, and the reliability metrics such as loss of load expectation (LOLE) and expected energy not supplied (EENS). Furthermore, the proposed approach is deployed for optimal allocation of wind energy in bulk power systems. Hence, two typical test systems are numerically analyzed to interrogate the performance of the proposed approach. The conducted survey discloses an over/underestimation of harvestable wind energy in the case of overlooking spatial distributions. Thus, inaccurate amounts of wind farm’s capacity factor, output power, energy and reliability indices might be estimated. Meanwhile, the number of wind turbines may be misjudged to be installed. However, the proposed approach yields in a fair judgment regarding the overall performance of the wind farm. Consequently, a reliable penetration level of wind energy to the power system is assured. Extra discussions are provided to deeply assess the promising merits of the founded approach.

The contribution of wind energy to electric power generation; Der Beitrag der Windenergie zur Stromerzeugung

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

The conference discussed the following five subjects: (1) Status and perspectives of wind power in Germany and Japan; (2) Grid connection of wind power systems; (3) Wind power and electric power supply; (4) Future fields of application, technical perspectives; (5) Panel discussion. [German] Der Tagungsband beinhaltet Beitraege in fuenf Bloecken, die die folgenden Ueberschriften haben: (1) Stand und Perspektiven der Windenergienutzung in Deutschland und Japan; (2) Netzintegration von Windenergieanlagen; (3) Windenergie in der elektrischen Energieversorgung; (4) zukuenftige Anwendungsfelder, technische Perspektiven sowie (5) Paneldiskussion. (AKF)

Wind power error estimation in resource assessments.

Directory of Open Access Journals (Sweden)

Osvaldo Rodríguez

Full Text Available Estimating the power output is one of the elements that determine the techno-economic feasibility of a renewable project. At present, there is a need to develop reliable methods that achieve this goal, thereby contributing to wind power penetration. In this study, we propose a method for wind power error estimation based on the wind speed measurement error, probability density function, and wind turbine power curves. This method uses the actual wind speed data without prior statistical treatment based on 28 wind turbine power curves, which were fitted by Lagrange's method, to calculate the estimate wind power output and the corresponding error propagation. We found that wind speed percentage errors of 10% were propagated into the power output estimates, thereby yielding an error of 5%. The proposed error propagation complements the traditional power resource assessments. The wind power estimation error also allows us to estimate intervals for the power production leveled cost or the investment time return. The implementation of this method increases the reliability of techno-economic resource assessment studies.

Wind power error estimation in resource assessments.

Science.gov (United States)

Rodríguez, Osvaldo; Del Río, Jesús A; Jaramillo, Oscar A; Martínez, Manuel

2015-01-01

Estimating the power output is one of the elements that determine the techno-economic feasibility of a renewable project. At present, there is a need to develop reliable methods that achieve this goal, thereby contributing to wind power penetration. In this study, we propose a method for wind power error estimation based on the wind speed measurement error, probability density function, and wind turbine power curves. This method uses the actual wind speed data without prior statistical treatment based on 28 wind turbine power curves, which were fitted by Lagrange's method, to calculate the estimate wind power output and the corresponding error propagation. We found that wind speed percentage errors of 10% were propagated into the power output estimates, thereby yielding an error of 5%. The proposed error propagation complements the traditional power resource assessments. The wind power estimation error also allows us to estimate intervals for the power production leveled cost or the investment time return. The implementation of this method increases the reliability of techno-economic resource assessment studies.

DISC ATMOSPHERES AND WINDS IN X-RAY BINARIES

Directory of Open Access Journals (Sweden)

Maria Díaz Trigo

2013-12-01

Full Text Available We review the current status of studies of disc atmospheres and winds in low mass X-ray binaries. We discuss the possible wind launching mechanisms and compare the predictions of the models with the existent observations. We conclude that a combination of thermal and radiative pressure (the latter being relevant at high luminosities can explain the current observations of atmospheres and winds in both neutron star and black hole binaries. Moreover, these winds and atmospheres could contribute significantly to the broad iron emission line observed in these systems.

Educação a distância: como revisar os materiais didáticos

OpenAIRE

Bezri Hermont, Arabie; Bonomo Assumpção, Solange

2010-01-01

A produção de materiais destinados à Educação a Distância (ou EaD) vem sendo alvo de atenção por diferentes instituições de ensino. Um dos aspectos implicados nessa produção é o processo de revisão de materiais que envolve tanto aspectos didáticos quanto linguísticos. Ao privilegiar uma concepção dialógica de linguagem na revisão dos materiais para a EaD, a equipe responsável por essa atividade contribui para que os autores dessas produções reavaliem seus materiais na direção da contextualiza...

Development and Application of SKSSIM Simulation Software for the Oxygen Bottom Blown Copper Smelting Process

Directory of Open Access Journals (Sweden)

Qinmeng Wang

2017-10-01

Full Text Available The oxygen bottom blown copper smelting process (SKS process is a newly developed intense smelting process, which has been widely applied to copper production in China. A multiphase equilibrium model for the SKS process was established based on its mechanism characteristics and the principle of Gibbs energy minimization, and an efficient simulation software—SKSSIM (SKS Simulation—was developed based on the model. Industrial data from the SKS process were used to compare with the calculated data from the SKSSIM software. The calculated data on the compositions of slag and matte as well as the distribution ratios of minor elements (such as Pb, Zn, As, Sb and Bi among the slags, mattes and off-gases were in good agreement with the actual plant data. Accordingly, the SKSSIM simulation software has the potentail to be used for the prediction of smelting production and for optimizing the operating parameters of the SKS process.

Conflitos organizacionais: a utilização da Educação a Distância para ensinar esse conteúdo nos Cursos de Graduação da Área da Saúde

OpenAIRE

Spagnol, Carla Aparecida; Guimarães, Eliane Marina Palhares; Godoy, Solange Cervinho Bicalho; Marques, Renata Lacerda

2015-01-01

O tema conflito organizacional é difícil de ser trabalhado somente com aulas expositivas, pois é um fenômeno que depende da situação, das pessoas envolvidas e do contexto em que ocorreu. Atualmente as tecnologias educacionais digitais são utilizadas em cursos na modalidade presencial ou a distância, tornando-se indispensável utilizar metodologias ativas. Este artigo é um relato de experiência que tem o objetivo de descrever e analisar uma disciplina a distância, que utiliza um material multim...

Assessment of the wind behavior in the northern coast of Santa Catarina Estudo do comportamento do vento no litoral centro-norte de Santa Catarina

Directory of Open Access Journals (Sweden)

Eliane Cristina Truccolo

2011-09-01

Full Text Available The spatial and temporal coherence of wind characteristics of coastal areas of Navegantes and Praia Grande, SC, 100 km apart each other, were assessed. Despite the relatively short distance, the oceanographic and geomorphological characteristics are different and can change the local and synoptic wind behavior, which are important for the understanding of the factors controlling the hydrodynamics and water quality of coastal environments. The comparison was performed through statistical analysis in the time and frequency domain, over a data set comprising hourly records from July to December, 1996. Both stations presented similarities regarding the north-south wind component. Therefore, quite different behavior is noticed for the east-west wind component, such as the breeze effect. The north-south wind pattern in Praia Grande is similar to the general wind regime for the Brazilian south-southwest areas, with dominance of northerly winds, and with southerly winds during the passage of cold-front systems, with small account of land-sea breeze. On the other hand, the breeze is the main factor contributing for the wind kinetics for the Navegantes area. We suggest that this differentiation is partially due to the combination of the mountain-valley circulation system of Vale do Itajaí with the breeze system, indicating a strong role of the local geomorphology on the wind regime. Additionally, it is may be possible that the sea surface temperature can also contribute, since there is a general trend of smaller temperatures southwards, though increasing the thermal gradient between the land and the sea.Registros horários de velocidade e direção dos ventos em Navegantes e Praia Grande, SC, equidistante 100 km, foram utilizados para avaliar a coerência espaço-temporal dos ventos entre as duas regiões costeiras. Apesar da pouca distância, as características oceanográficas e geomorfológicas destas regiões são distintas e podem alterar o

Gasification of torrefied Miscanthus × giganteus in an air-blown bubbling fluidized bed gasifier.

Science.gov (United States)

Xue, G; Kwapinska, M; Horvat, A; Kwapinski, W; Rabou, L P L M; Dooley, S; Czajka, K M; Leahy, J J

2014-05-01

Torrefaction is suggested to be an effective method to improve the fuel properties of biomass and gasification of torrefied biomass should provide a higher quality product gas than that from unprocessed biomass. In this study, both raw and torrefied Miscanthus × giganteus (M×G) were gasified in an air-blown bubbling fluidized bed (BFB) gasifier using olivine as the bed material. The effects of equivalence ratio (ER) (0.18-0.32) and bed temperature (660-850°C) on the gasification performance were investigated. The results obtained suggest the optimum gasification conditions for the torrefied M × G are ER 0.21 and 800°C. The product gas from these process conditions had a higher heating value (HHV) of 6.70 MJ/m(3), gas yield 2m(3)/kg biomass (H2 8.6%, CO 16.4% and CH4 4.4%) and cold gas efficiency 62.7%. The comparison between raw and torrefied M × G indicates that the torrefied M × G is more suitable BFB gasification. Copyright © 2014 Elsevier Ltd. All rights reserved.

Financing wind energy projects

International Nuclear Information System (INIS)

Blom, P.

1996-01-01

Triodos Bank has more than 10 years of experience with developing and financing wind projects in the Netherlands. Over 50 Megawatt has been installed with direct involvement of the bank. The experience is both as a bank and as a venture capital fund. In this contribution the perspective will be more from a venture capital point of view than as a bank. The bank's activities in the wind energy sector started in 1986 by forming a joint venture with an engineering bureau, experienced i wind energy but not yet in developing wind projects. From 1989 onwards the joint venture started to build wind farms, both as a private company and in a joint venture with utilities. The European Investment Bank became involved with a long-term debt finance facility (15 years, fixed interest loan). The main difficulties were long-term commitments from landowners (Dike authorities) and utilities with regard to power contracts. The development got really stuck when utilities refused to pay a fair price anymore. Also, site development became more and more difficult. Even the poor technical performance improved drastically and did not frighten developers and banks too much. (author)

Human reproductive system disturbances and pesticide exposure in Brazil Distúrbios do sistema reprodutivo humano e exposição a pesticidas no Brasil

Directory of Open Access Journals (Sweden)

Sergio Koifman

2002-04-01

Full Text Available The observation of reproductive disturbances in humans and in the wildlife has been reported in the last decade in different countries. Exposure to different chemicals possibly acting in the endocrine system or endocrine disruptors, including pesticides, has been a hypothesis raised to explain the observed changes. This paper aimed to present results of an epidemiological ecologic study carried out to explore population data on pesticides exposure in selected Brazilian states in the eighties and human reproductive outcomes in the nineties. Pearson correlation coefficients were ascertained between available data pesticides sales in eleven states in Brazil in 1985 and selected further reproductive outcomes or their surrogates. Moderate to high correlations were observed to infertility, testis, breast, prostate and ovarian cancer mortality. Despite the restrains of ecologic studies to establish cause-effect relationships, the observed results are in agreement with evidence supporting a possible association between pesticides exposure and the analyzed reproductive outcomes.A observação de distúrbios reprodutivos em seres humanos e na vida animal tem sido relatada em diferentes países na última década, sendo apontada como possível explicação para tal fenômeno, a exposição a diversas substâncias químicas com possível interferência no sistema endócrino, incluindo pesticidas. Este trabalho apresenta os resultados de um estudo epidemiológico, com delineamento ecológico explorando dados de exposição a pesticidas durante os anos oitenta, em estados brasileiros selecionados e distúrbios reprodutivos observados nos anos noventa. Foram obtidos coeficientes de correlação de Pearson entre o volume de vendas de pesticidas em onze estados brasileiros em 1985 e indicadores diretos ou substitutos da ocorrência de distúrbios reprodutivos nas mesmas localidades. Coeficientes de correlação moderados e elevados foram observados para a

Wind energy: A review of technical and market issues

Energy Technology Data Exchange (ETDEWEB)

Garrad, A.D. [Garrad Hassan & Partners Ltd., Bristol (United Kingdom)

1996-12-31

Opinions on the world market for wind power are presented in this paper. The paper is divided into three sections: the market, the technology, and general conclusions. The market section compares European and US wind energy growth and contributing factors and barriers to growth. A technology overview discusses wind turbine concepts, mass reduction, blade structural flexibility, and growth in machine size. Political decisions, economic aspects, public acceptance, and technology limitations are assessed for their influence on the growth of wind energy. 11 figs.

POSSPOW: Possible Power of Offshore Wind Power Plants

DEFF Research Database (Denmark)

Giebel, Gregor; Göçmen, Tuhfe; Sørensen, Poul Ejnar

2013-01-01

Introduction In recent years, the very large offshore wind farms were designed as wind power plants, including possibilities to contribute to the stability of the grid by offering grid services (also called ancillary services). One of those services is reserve power, which is achieved by down......-regulating the wind farm from its maximum possible power. The power can be ramped up quite quickly, but the influence of wakes makes it difficult to assess the exact amount of down-regulation available to sell. Currently, Transmission System Operators (TSOs) have no real way to determine exactly the possible power...... will be verified on some of the large offshore wind farms owned by Vattenfall, and possibly in a DONG Energy wind farm too. Dedicated experiments to the wind flow in large offshore wind farms are planned. Main body of abstract Modern wind turbines have a SCADA signal called possible power. In normal operation...

China's experimental pragmatics of "Scientific development" in wind power: Algorithmic struggles over software in wind turbines

DEFF Research Database (Denmark)

Kirkegaard, Julia

2016-01-01

. This increased focus on quality, to ensure the sustainable and scientific development of China's wind energy market, requires improved indigenous Chinese innovation capabilities in wind turbine technology. To shed light on how the turn to quality impacts upon the industry and global competition, this study......This article presents a case study on the development of China's wind power market. As China's wind industry has experienced a quality crisis, the Chinese government has intervened to steer the industry towards a turn to quality, indicating a pragmatist and experimental mode of market development...... unfold over issues associated with intellectual property rights (IPRs), certification and standardisation of software algorithms. The article concludes that the use of this STS lens makes a fresh contribution to the often path-dependent, structuralist and hierarchical China literature, offering instead...

Offshore wind energy - Proceedings of the 2009 Le Havre International Meetings

International Nuclear Information System (INIS)

Gerard, Bernard; Rufenacht, Antoine; Marchand, Philippe; Perrot, Jean-Yves; Blanchard, Loic; Leredde, Bruno; Gouverneur, Philippe; Buch, Mette; Westra, Chris; Deswartes, Fabien; Kaelble, Laure; Lutsen, Didier; Kolb, Jean-Mathieu; Moine, Sebastien; Kipke, Ruediger; Coelingh, Jan; Fagot, Guillaume; Noury, Bruno; Herpers, Frederick; Bersani, Catherine; Lanoe, Frederic; Grosdemange, Didier; Uhl, Frederic; Lapierre, Anne; Dumarquez, Philippe; Ruer, Jacques; Huberson, Serge; Barakat, Georges; Cooke, Richard; Reisse, Eric; Bihel, Pierre-Nicolas; Mohr, Rainer; Goesswein, Jens; Brossard, Jerome; Duval, Stephane; Bonnefond, Thierry; Jacquemin, Jerome; His, Stephane; Fazio, Bertrand; Theobald, Fabrice; Boeuf, Marc; Ruer, Jacques; Mercher, Gerard; Poitou, Pascal; Lemarquis, David; Bal, Jean-Louis; Abonnel, Cyrille; Mouslim, Hakim; Rousset, Jean-Marc; Brochard, Emmanuel; Lengyel, Jacques; Antolini, Andre; Gerard, Bernard

2009-11-01

This document gathers keynote addresses, contributions and Power Point presentations of a colloquium on the development of offshore wind energy. This colloquium comprises several sessions: the strategy of offshore wind energy development, the planning of wind energy development, the keys of wind energy development, the associated environmental, technological and industrial challenges, the industrial and port deployment for the development of marine energies

Redes sociais online em projetos de educação a distância: o caso do projeto-piloto “Geração Movimento” (2015

Directory of Open Access Journals (Sweden)

Bruno Leal Pastor de Carvalho

2016-06-01

Full Text Available Em 2015, a Fundação Roberto Marinho, em parceria com o Instituto Coca-Cola Brasil e a Coca-Cola Brasil, realizou um projeto-piloto de formação continuada de modalidade híbrida (presencial e a distância para 145 professores do Ensino Fundamental de escolas da rede pública de Joinville, Santa Catarina. Este proje-to, chamado “Geração Movimento”, visou desenvolver conceitos relacionados ao corpo, à atividade física e ao movimento corporal. O presente trabalho se debruça sobre a rede social na internet que integrou à parte a distância do projeto. São focados, neste sentido, o engajamento dos participantes, suas respostas frente às estratégias de comunicação dos gestores e o uso das principais ferramentas tecnológicas desta rede.

Wind energy - The facts. An analysis of wind energy in the EU-25

International Nuclear Information System (INIS)

2004-02-01

Since the previous edition of Wind Enera - The Facts was published five years ago, the wind energy sector has undergone rapid change and transformation. There has been an explosion in demand for and Interest in a cleaner energy world from politicians, institutions, policy makers and regulators, the media, commentators and the general public. Such interest necessitates a greater depth of understanding of the wind power sector if informed choices and policy decisions are to be made. The European Wind Energy Association (EWEA), and the European Commission's Directorate General for Transport' and Energy have collaborated on this report to provide a detailed overview of the wind power sector. Wind Enera - The Facts provides a comprehenslve overview of the essential issues concerning wind power today: technology, cost, prices, environment, industry and employment, market, and research and development. Wind energy is a relatively young but rapidly expanding industry. Over the past decade, global installed capacity has increased from 2,500 megawatts (MW) in 1992 to just over 40,000 MW at the end of 2003, at an annual growth rate of near 30%. Almost three quarters of this capacity has been installed in Europe. Penetration levels in the electricity sector have reached 20% in Denmark and about 5% in both Germany and Spain. The north German state of Schleswig-Holstein has 1,800 MW of installed wind capacity, enough to meet 30% of the region's total electricity demand, while in Navarra, in Spain, 50% of consumption is met by wind power. If positive policy support continues to develop, EWEA has projected that wind power will achieve an installed capacity of 75,000 MW in the EU-15 by 2010. This would represent an overall contribution to electricity supply of 5.5%. By 2020, this figure is expected to increase to more than 12%, with wind power providing energy equal to the demand of 195 million European household consumers. (au)

2065-IJBCS-Article-Okorie Edmund

African Journals Online (AJOL)

hp

Okaba coal mine in Kogi State, Nigeria by energy-dispersive x-ray fluorescence ... Successive generations of plant growth and death formed deep ..... finely divided and readily wind-blown. Radioactive ... (X-ray absorption fine structure).

Take-Off and Landing Characteristics of a 0.13-Scale Model of the Convair XFY-1 Vertically Rising Airplane in Steady Winds, TED No. NACA DE 368

Science.gov (United States)

Schade, Robert O.; Smith, Charles C., Jr.; Lovell, P. M., Jr.

1954-01-01

An experimental investigation has been conducted to determine the stability and control characteristics of a 0.13-scale free-flight model of the Convair XFY-1 airplane during take-offs and landings in steady winds. The tests indicated that take-offs in headwinds up to at least 20 knots (full scale) will be fairly easy to perform although the airplane may be blown downstream as much as 3 spans before a trim condition can be established. The distance that the airplane will be blown down-stream can be reduced by restraining the upwind landing gear until the instant of take-off. The tests also indicated that spot landings in headwinds up to at least 30 knots (full scale) and in crosswinds up to at least 20 knots (full scale) can be accomplished with reasonable accuracy although, during the landing approach, there will probably be an undesirable nosing-up tendency caused by ground effect and by the change in angle of attack resulting from vertical descent. Some form of arresting gear will probably be required to prevent the airplane from rolling downwind or tipping over after contact. This rolling and tipping can be prevented by a snubbing line attached to the tip of the upwind' wing or tail or by an arresting gear consisting of a wire mesh on the ground and hooks on the landing gear to engage the mesh.

Assessing the impact of marine wind farms on birds through movement modelling.

Science.gov (United States)

Masden, Elizabeth A; Reeve, Richard; Desholm, Mark; Fox, Anthony D; Furness, Robert W; Haydon, Daniel T

2012-09-07

Advances in technology and engineering, along with European Union renewable energy targets, have stimulated a rapid growth of the wind power sector. Wind farms contribute to carbon emission reductions, but there is a need to ensure that these structures do not adversely impact the populations that interact with them, particularly birds. We developed movement models based on observed avoidance responses of common eider Somateria mollissima to wind farms to predict, and identify potential measures to reduce, impacts. Flight trajectory data that were collected post-construction of the Danish Nysted offshore wind farm were used to parameterize competing models of bird movements around turbines. The model most closely fitting the observed data incorporated individual variation in the minimum distance at which birds responded to the turbines. We show how such models can contribute to the spatial planning of wind farms by assessing their extent, turbine spacing and configurations on the probability of birds passing between the turbines. Avian movement models can make new contributions to environmental assessments of wind farm developments, and provide insights into how to reduce impacts that can be identified at the planning stage.

Wind resource characterization in the Arabian Peninsula

KAUST Repository

Yip, Chak Man Andrew

2015-12-28

Wind energy is expected to contribute to alleviating the rise in energy demand in the Middle East that is driven by population growth and industrial development. However, variability and intermittency in the wind resource present significant challenges to grid integration of wind energy systems. These issues are rarely addressed in the literature of wind resource assessment in the Middle East due to sparse meteorological observations with varying record lengths. In this study, the wind field with consistent space–time resolution for over three decades at three hub heights (50m, 80m, 140m) over the whole Arabian Peninsula is constructed using the Modern Era Retrospective-Analysis for Research and Applications (MERRA) dataset. The wind resource is assessed at a higher spatial resolution with metrics of temporal variations in the wind than in prior studies. Previously unrecognized locations of interest with high wind abundance and low variability and intermittency have been identified in this study and confirmed by recent on-site observations. In particular, the western mountains of Saudi Arabia experience more abundant wind resource than most Red Sea coastal areas. The wind resource is more variable in coastal areas along the Arabian Gulf than their Red Sea counterparts at a similar latitude. Persistent wind is found along the coast of the Arabian Gulf.

Analysis of the reduced wake effect for available wind power calculation during curtailment

NARCIS (Netherlands)

Sanchez Perez Moreno, S.; Ummels, B. C.; Zaayer, M B

2017-01-01

With the increase of installed wind power capacity, the contribution of wind power curtailment to power balancing becomes more relevant. Determining the available power during curtailment at the wind farm level is not trivial, as curtailment changes the wake effects in a wind farm. Current best

European wind turbine catalogue

International Nuclear Information System (INIS)

1994-01-01

The THERMIE European Community programme is designed to promote the greater use of European technology and this catalogue contributes to the fulfillment of this aim by dissemination of information on 50 wind turbines from 30 manufacturers. These turbines are produced in Europe and are commercially available. The manufacturers presented produce and sell grid-connected turbines which have been officially approved in countries where this approval is acquired, however some of the wind turbines included in the catalogue have not been regarded as fully commercially available at the time of going to print. The entries, which are illustrated by colour photographs, give company profiles, concept descriptions, measured power curves, prices, and information on design and dimension, safety systems, stage of development, special characteristics, annual energy production, and noise pollution. Lists are given of wind turbine manufacturers and agents and of consultants and developers in the wind energy sector. Exchange rates used in the conversion of the prices of wind turbines are also given. Information can be found on the OPET network (organizations recognised by the European Commission as an Organization for the Promotion of Energy Technologies (OPET)). An article describes the development of the wind power industry during the last 10-15 years and another article on certification aims to give an overview of the most well-known and acknowledged type approvals currently issued in Europe. (AB)

Wind deployment in the United States: states, resources, policy, and discourse.

Science.gov (United States)

Wilson, Elizabeth J; Stephens, Jennie C

2009-12-15

A transformation in the way the United States produces and uses energy is needed to achieve greenhouse gas reduction targets for climate change mitigation. Wind power is an important low-carbon technology and the most rapidly growing renewable energy technology in the U.S. Despite recent advances in wind deployment, significant state-by-state variation in wind power distribution cannot be explained solely by wind resource patterns nor by state policy. Other factors embedded within the state-level socio-political context also contribute to wind deployment patterns. We explore this socio-political context in four U.S. states by integrating multiple research methods. Through comparative state-level analysis of the energy system, energy policy, and public discourse as represented in the media, we examine variation in the context for wind deployment in Massachusetts, Minnesota, Montana, and Texas. Our results demonstrate that these states have different patterns of wind deployment, are engaged in different debates about wind power, and appear to frame the risks and benefits of wind power in different ways. This comparative assessment highlights the complex variation of the state-level socio-political context and contributes depth to our understanding of energy technology deployment processes, decision-making, and outcomes.

Analysis of TIMS performance subjected to simulated wind blast

Science.gov (United States)

Jaggi, S.; Kuo, S.

1992-01-01

assumed to be at ambient temperature as recorded by the TIMS for each scanline. Using the slope and the intercept the flux corresponding to this target was converted into digital counts. The counts were observed to have a strong correlation with the actual video as recorded by the TIMS. The attached graphs describe the performance of the TIMS when compressed air is blown at each one of the blackbodies at different speeds. The effect of blowing a fan and changing the room temperature is also being analyzed. Results indicate that the TIMS system responds to variation in wind speed in real time and maintains the capability to produce accurate temperatures on a scan line basis.

ewec 2007 - Europe's premier wind energy event

International Nuclear Information System (INIS)

Chaviaropoulos, T.

2007-01-01

This online collection of papers - the ewec 2007 proceedings - reflects the various sessions and lectures presented at the ewec wind-energy convention held in Milan in 2007. The first day's sessions looked at the following topics: Renewable Energy Roadmap, the changing structure of the wind industry, politics and programmes, aerodynamics and innovation in turbine design, wind resources and site characterisation (2 sessions), energy scenarios, harmonisation of incentive schemes, structural design and materials, forecasting, integration studies, integrating wind into electricity markets, wind-turbine electrical systems and components, as well as loads, noise and wakes. The second day included sessions on offshore: developments and prospects, extreme wind conditions and forecasting techniques, small wind turbines, distributed generation and autonomous systems cost effectiveness, cost effectiveness of wind energy, financing wind energy concepts, wind and turbulence, wind power plants and grid integration, offshore technology, global challenges and opportunities, aero-elasticity, loads and control, operations and maintenance, carbon trading and the emission trading schemes, investment strategies of power producers, wind power plants and grid integration, wind turbine electrical systems and components, and wakes. The third day offered sessions on environmental issues, condition monitoring, operation and maintenance, structural design and materials, the Up-Wind workshop, winning hearts and minds, offshore technology, advances in measuring methods and advancing drive-train reliability. In a closing session the conference was summarised, awards for poster contributions were made and the Poul la Cour Prize was presented

Educação a distância como estratégia educacional e organizacional: o caso de uma escola de Administração de uma universidade pública brasileira

Directory of Open Access Journals (Sweden)

Christine da Silva Schröeder

2017-05-01

Full Text Available O presente ensaio teórico-empírico tem por objetivo apresentar o caso de uma Escola de Administração que mantém cursos na modalidade de educação a distância (EAD em uma grande universidade pública brasileira, relatando sua experiência, mais precisamente entre os anos de 2003 e 2009. As atividades de EAD na instituição foram desenvolvidas por um Núcleo de Aprendizagem Virtual (ou NAVI que, por sua vez, desenvolveu uma plataforma de aprendizagem para cursos de extensão, graduação e pós-graduação. Nesse contexto, o ensino (ou educação a distância é analisado enquanto estratégia educacional e, sobretudo, organizacional, sob diferentes perspectivas: a estratégica estrutural, a humana, a tecnológica, a cultural e a política, trazendo à instituição novos desafios e possibilidades, em especial no que concerne à focalização externa e de estruturação interna, aprofundando, assim, a criação e a avaliação de estratégias de uma modalidade emergente de aprendizagem: a educação a distância.

Modeling wind-blown desert dust in the southwestern United States for public health warning: A case study

Science.gov (United States)

Yin, Dazhong; Nickovic, Slobodan; Barbaris, Brian; Chandy, Beena; Sprigg, William A.

A model for simulating desert dust cycle was adapted and applied for a dust storm case in the southwest United States (US). This is an initial test of the model's capability as part of a future public health early warning system. The modeled meteorological fields, which drive a dust storm, were evaluated against surface and upper-air measurement data. The modeled dust fields were compared with satellite images, in situ surface PM2.5 and PM10 data, and visibility data in the areas affected by the dust event. The model predicted meteorological fields reasonably well. The modeled surface and upper-air field patterns were in agreement with the measured ones. The vertical profiles of wind, temperature, and humidity followed closely with the observed profiles. Statistical analyses of modeled and observed meteorological variables at surface sites showed fairly good model performance. The modeled dust spatial distributions were comparable with the satellite-observed dust clouds and the reduced visibility patterns. Most encouragingly, the model-predicted and observed PM2.5 peak hours matched reasonably well. The model produced better PM2.5 peak hours than PM10 peak hours. The temporal varying trends of daily and hourly PM2.5 and PM10 concentrations at most of the measurement sites were similar to those observed. Discrepancies between the values of the modeled and the measured surface PM2.5 and PM10 concentrations differed with time and location. Sometimes the modeled and measured concentrations can have one order of magnitude differences. These revealed there were possible deficiencies in the simulation of the dust production strength and location, and the representation of dust particle size in the modeling. Better land surface data and size representation of the dust production are expected to further improve model performance.

Next Generation Wind Turbine

Energy Technology Data Exchange (ETDEWEB)

Cheraghi, S. Hossein [Western New England Univ., Springfield, MA (United States); Madden, Frank [FloDesign Wind Turbine Corp., Waltham, MA (United States)

2012-09-01

The goal of this collaborative effort between Western New England University's College of Engineering and FloDesign Wind Turbine (FDWT) Corporation to wok on a novel areodynamic concept that could potentially lead to the next generation of wind turbines. Analytical studies and early scale model tests of FDWT's Mixer/Ejector Wind Turbine (MEWT) concept, which exploits jet-age advanced fluid dynamics, indicate that the concept has the potential to significantly reduce the cost of electricity over conventional Horizontal Axis Wind Turbines while reducing land usage. This project involved the design, fabrication, and wind tunnel testing of components of MEWT to provide the research and engineering data necessary to validate the design iterations and optimize system performance. Based on these tests, a scale model prototype called Briza was designed, fabricated, installed and tested on a portable tower to investigate and improve the design system in real world conditions. The results of these scale prototype efforts were very promising and have contributed significantly to FDWT's ongoing development of a product scale wind turbine for deployment in multiple locations around the U.S. This research was mutually beneficial to Western New England University, FDWT, and the DOE by utilizing over 30 student interns and a number of faculty in all efforts. It brought real-world wind turbine experience into the classroom to further enhance the Green Engineering Program at WNEU. It also provided on-the-job training to many students, improving their future employment opportunities, while also providing valuable information to further advance FDWT's mixer-ejector wind turbine technology, creating opportunities for future project innovation and job creation.

Wind power in Argentina: Policy instruments and economic feasibility

International Nuclear Information System (INIS)

Recalde, M.

2010-01-01

Despite its great wind endowment, Argentina has not still succeeded in increasing wind power share in its wholesale market. However, the energy supply problem that this country is facing from 2004 on seems to open an opportunity for wind energy projects. A wide range of legislation has recently emerged. In this context, this paper discusses whether policy instruments in the Argentinean regulatory frame contribute to economic feasibility for wind power projects or not. To this purpose, we study wind installed capacity, Argentinean wind potential, the different promotion tools used worldwide and those employed in Argentina. Finally, we realize a feasibility study for a typical project. We found, that in spite of its high wind potential, economic feature, related to policy instruments, have been a boundary to the development of wind energy into the energy mix. (author)

Mean and peak wind load reduction on heliostats

Energy Technology Data Exchange (ETDEWEB)

Peterka, J.A.; Tan, L.; Bienkiewcz, B.; Cermak, J.E.

1987-09-01

This report presents the results of wind-tunnel tests supported through the Solar Energy Research Institute (SERI) by the Office of Solar Thermal Technology of the US Department of Energy as part of the SERI research effort on innovative concentrators. As gravity loads on drive mechanisms are reduced through stretched-membrane technology, the wind-load contribution of the required drive capacity increases in percentage. Reduction of wind loads can provide economy in support structure and heliostat drive. Wind-tunnel tests have been directed at finding methods to reduce wind loads on heliostats. The tests investigated both mean and peak forces, and moments. A significant increase in ability to predict heliostat wind loads and their reduction within a heliostat field was achieved. In addition, a preliminary review of wind loads on parabolic dish collectors was conducted, resulting in a recommended research program for these type collectors. 42 refs., 38 figs., 1 tab.

IFREMER-ADEME colloquium 'Offshore renewable energies: offshore wind energy - sea currents and waves. Collection of abstracts

International Nuclear Information System (INIS)

2004-10-01

This document contains programme and abstracts of contributions presented during a colloquium. These contributions first addresses the context, and regulatory and economic aspects of offshore wind and sea energy: specificities related to the Public Maritime Domain for the implantation of offshore wind turbines, economy of sea energies within a perspective of de-carbonation of the world energy sector, case of offshore wind turbines and assessment of economic impacts of the implantation of sea renewable energy production units, financing stakes for offshore wind energy projects. A second set of contribution addresses the state-of -the-art and feedbacks for offshore wind energy installations. The third set addresses the assessment of resource potential, measurements, models and production prediction for offshore wind energy: case of French coasts, use of radar for remote sensing, wind climatology modelling, data acquisition for wind farm and data processing. The fourth set of contributions addresses the state-of-the-art, feedback, and R and D for sea current energy, while the fifth one addressed the same aspects for sea wave energy. Technology, installations, maintenance and storage in the field of wind energy are then addressed, and the last set deals with environmental and social-economical impacts of sea renewable energies

Grid Integration of Wind Farms

Science.gov (United States)

Giæver Tande, John Olav

2003-07-01

This article gives an overview of grid integration of wind farms with respect to impact on voltage quality and power system stability. The recommended procedure for assessing the impact of wind turbines on voltage quality in distribution grids is presented. The procedure uses the power quality characteristic data of wind turbines to determine the impact on slow voltage variations, flicker, voltage dips and harmonics. The detailed assessment allows for substantially more wind power in distribution grids compared with previously used rule-of-thumb guidelines. Power system stability is a concern in conjunction with large wind farms or very weak grids. Assessment requires the use of power system simulation tools, and wind farm models for inclusion in such tools are presently being developed. A fixed-speed wind turbine model is described. The model may be considered a good starting point for development of more advanced models, hereunder the concept of variable-speed wind turbines with a doubly fed induction generator is briefly explained. The use of dynamic wind farm models as part of power system simulation tools allows for detailed studies and development of innovative grid integration techniques. It is demonstrated that the use of reactive compensation may relax the short-term voltage stability limit and allow integration of significantly more wind power, and that application of automatic generation control technology may be an efficient means to circumvent thermal transmission capacity constraints. The continuous development of analysis tools and technology for cost-effective and secure grid integration is an important aid to ensure the increasing use of wind energy. A key factor for success, however, is the communication of results and gained experience, and in this regard it is hoped that this article may contribute.

A review of the European offshore wind innovation system

NARCIS (Netherlands)

Wieczorek, A.J.; Negro, S.O.; Harmsen, R.; Heimeriks, G.J.; Luo, L.; Hekkert, M.P.

2013-01-01

Offshore wind has the potential of becoming an important pillar of the future European energy system. It can contribute to policy objectives on climate change, energy security, green growth and social progress. However, the large potential of offshore wind does not automatically lead to a large

Wind2050 – a transdisciplinary research partnership about wind energy

DEFF Research Database (Denmark)

Borch, Kristian; Nyborg, Sophie; Clausen, Laura Tolnov

2017-01-01

Strategic orientation and priority setting in energy planning are high on the political agenda in Denmark due to the ambitious national goal of fossil-free energy systems. One key issue concerns the involvement of stakeholders – and non-expert stakeholders in particular – in discussions on how...... such as environment and health or what is per-ceived as an unfair distribution of economic gains, as well as how wind turbines could contribute to local development or be seen as a local contribution to a national transi-tion of the energy system. This calls for a transdisciplinary approach to science and innovation...

Clean energy stakes too important for nuclear to be blown off course

Energy Technology Data Exchange (ETDEWEB)

Shepherd, John [nuclear 24, St George' s Redditch (United Kingdom)

2017-10-15

New figures indicating that offshore wind farms could be built for a record low price in the UK - and produce cheaper electricity than nuclear - sent an initial chill through the nuclear energy industry. Wind lobbyists were quick to trumpet the figures from the Department for Business, Energy and Industrial Strategy (UK), which were unveiled following a 'contracts for difference' auction for subsidies. The spokesperson's comments were more astonishing than the data that emerged from the report. As the chief executive of the Nuclear Industry Association (NIA), Tom Greatrex, pointed out: ''Reports that the cost of future offshore wind projects may fall (if they are constructed) is good news, but as the UK renewable trade body, informed commentators and industry experts have made clear, one technology alone can't solve the UK's power challenge''.

SuperLU{_}DIST: A scalable distributed-memory sparse direct solver for unsymmetric linear systems

Energy Technology Data Exchange (ETDEWEB)

Li, Xiaoye S.; Demmel, James W.

2002-03-27

In this paper, we present the main algorithmic features in the software package SuperLU{_}DIST, a distributed-memory sparse direct solver for large sets of linear equations. We give in detail our parallelization strategies, with focus on scalability issues, and demonstrate the parallel performance and scalability on current machines. The solver is based on sparse Gaussian elimination, with an innovative static pivoting strategy proposed earlier by the authors. The main advantage of static pivoting over classical partial pivoting is that it permits a priori determination of data structures and communication pattern for sparse Gaussian elimination, which makes it more scalable on distributed memory machines. Based on this a priori knowledge, we designed highly parallel and scalable algorithms for both LU decomposition and triangular solve and we show that they are suitable for large-scale distributed memory machines.

Impact of active and break wind spells on the demand-supply balance in wind energy in India

Science.gov (United States)

Kulkarni, Sumeet; Deo, M. C.; Ghosh, Subimal

2018-02-01

With an installed capacity of over 19,000 MW, the wind power currently accounts for almost 70% of the total installed capacity among the renewable energy sector in India. The extraction of wind power mainly depends on prevailing meteorology which is strongly influenced by monsoon variability. The monsoon season is characterized by significant fluctuations in between periods of wet and dry spells. During the dry spells, the demand for power from agriculture and cooling equipment increases, whereas during the wet periods, such demand reduces, although, at the same time, the power supply increases because of strong westerly winds contributing to an enhanced production of wind energy. At this backdrop, we aim to assess the impact of intra-seasonal wind variability on the balance of energy supply and demand during monsoon seasons in India. Further, we explore the probable cause of wind variability by relating it to El Nino events. It is observed that the active and break phases in wind significantly impact the overall wind potential output. Although the dry spells are generally found to reduce the overall wind potential, their impact on the potential seems to have declined after the year 2000. The impact of meteorological changes on variations in wind power studied in this work should find applications typically in taking investment decisions on conventional generation facilities, like thermal, which are currently used to maintain the balance of power supply and demand.

On the origin of the system PSR B1757-24/SNR G5.4-1.2

OpenAIRE

Gvaramadze, V. V.

2003-01-01

A scenario for the origin of the system PSR B1757-24/supernova remnant (SNR) G5.4-1.2 is proposed. It is suggested that both objects are the remnants of a supernova (SN) that exploded within a pre-existing bubble blown-up by a runaway massive star (the SN progenitor) during the final (Wolf-Rayet) phase of its evolution. This suggestion implies that (a) the SN blast centre was significantly offset from the geometric centre of the wind-blown bubble (i.e. from the centre of the future SNR), (b) ...

CanWEA Pan-Canadian wind integration study paper

Energy Technology Data Exchange (ETDEWEB)

Tremblay, Martin [GL Garrad Hassan Canada Inc, Ottawa, ON (Canada); Gardner, Paul [GL Garrad Hassan and Partners, Glasgow (United Kingdom); Price, Doug; Le, Don [GL Garrad Hassan America, San Diego, CA (United States)

2010-07-01

GL Garrad Hassan has been contracted by CanWEA to undertake a scoping study for a future Pan-Canadian Wide-Scale Wind Integration Study. The scoping study provides the methodology and the rationale on which the actual wind integration study and request for proposals will be based on. Major system operators and owners of each Canadian Province along with experts involved in major US wind integration studies have been consulted and contributed to the decisional process. This paper provides a summary of the factors considered in the study and outline the actual methodology that was adopted for the future Pan-Canadian wind integration study. (orig.)

On the relative contributions of wind vs. animals to seed dispersal of four Sierra Nevada pines.

Science.gov (United States)

Vander Wall, Stephen B

2008-07-01

Selective pressures that influence the form of seed dispersal syndromes are poorly understood. Morphology of plant propagules is often used to infer the means of dispersal, but morphology can be misleading. Several species of pines, for example, have winged seeds adapted for wind dispersal but owe much of their establishment to scatter-hoarding animals. Here the relative importance of wind vs. animal dispersal is assessed for four species of pines of the eastern Sierra Nevada that have winged seeds but differed in seed size: lodgepole pine (Pinus contorta murrayana, 8 mg); ponderosa pine (Pinus ponderosa ponderosa, 56 mg); Jeffrey pine (Pinus jeffreyi, 160 mg); and sugar pine (Pinus lambertiana, 231 mg). Pre-dispersal seed mortality eliminated much of the ponderosa pine seed crop (66%), but had much less effect on Jeffrey pine (32% of seeds destroyed), lodgepole pine (29%), and sugar pine (7%). When cones opened most filled seeds were dispersed by wind. Animals removed > 99% of wind-dispersed Jeffrey and sugar pine seeds from the ground within 60 days, but animals gathered only 93% of lodgepole pine seeds and 38% of ponderosa pine seeds during the same period. Animals gathered and scatter hoarded radioactively labeled ponderosa, Jeffrey, and sugar pine seeds, making a total of 2103 caches over three years of study. Only three lodgepole pine caches were found. Caches typically contained 1-4 seeds buried 5-20 mm deep, depths suitable for seedling emergence. Although Jeffrey and sugar pine seeds are initially wind dispersed, nearly all seedlings arise from animal caches. Lodgepole pine is almost exclusively wind dispersed, with animals acting as seed predators. Animals treated ponderosa pine in an intermediate fashion. Two-phased dispersal of large, winged pine seeds appears adaptive; initial wind dispersal helps to minimize pre-dispersal seed mortality whereas scatter hoarding by animals places seeds in sites with a higher probability of seedling establishment.

III Colóquio luso-brasileiro de educação a distância e elearning

OpenAIRE

Amante, Lúcia; Mendes, António Quintas; Barros, Daniela Melaré Vieira; Cardoso, Teresa; Spilker, Maria João

2013-01-01

O livro de atas do III Colóquio Luso-Brasileiro de Educação a Distância e Elearning, realizado em Lisboa em dezembro de 2013, reúne um vasto conjunto de comunicações apresentadas no evento e que se distribuem por 10 grandes temas a saber: EaD e Políticas educativas; Boas Práticas em Educação Online; Modelos e Processos Pedagógicos em Educação online; Web 2.0 e tecnologias emergentes; Pedagogias emergentes (PLEs, MOOCs, REAs, …); Realidade Virtual em EaD; Jogos e gamification em EaD; Mobile Le...

A century of wind tunnels since Eiffel

Science.gov (United States)

Chanetz, Bruno

2017-08-01

Fly higher, faster, preserve the life of test pilots and passengers, many challenges faced by man since the dawn of the twentieth century, with aviation pioneers. Contemporary of the first aerial exploits, wind tunnels, artificially recreating conditions encountered during the flight, have powerfully contributed to the progress of aeronautics. But the use of wind tunnels is not limited to aviation. The research for better performance, coupled with concern for energy saving, encourages manufacturers of ground vehicles to perform aerodynamic tests. Buildings and bridge structures are also concerned. This article deals principally with the wind tunnels built at ONERA during the last century. Somme wind tunnels outside ONERA, even outside France, are also evocated when their characteristics do not exist at ONERA.

Challenges and options for large scale integration of wind power

International Nuclear Information System (INIS)

Tande, John Olav Giaever

2006-01-01

Challenges and options for large scale integration of wind power are examined. Immediate challenges are related to weak grids. Assessment of system stability requires numerical simulation. Models are being developed - validation is essential. Coordination of wind and hydro generation is a key for allowing more wind power capacity in areas with limited transmission corridors. For the case study grid depending on technology and control the allowed wind farm size is increased from 50 to 200 MW. The real life example from 8 January 2005 demonstrates that existing marked based mechanisms can handle large amounts of wind power. In wind integration studies it is essential to take account of the controllability of modern wind farms, the power system flexibility and the smoothing effect of geographically dispersed wind farms. Modern wind farms contribute to system adequacy - combining wind and hydro constitutes a win-win system (ml)

Global wind power development: Economics and policies

International Nuclear Information System (INIS)

Timilsina, Govinda R.; Cornelis van Kooten, G.; Narbel, Patrick A.

2013-01-01

Existing literature indicates that theoretically, the earth's wind energy supply potential significantly exceeds global energy demand. Yet, only 2–3% of global electricity demand is currently derived from wind power despite 27% annual growth in wind generating capacity over the last 17 years. More than 95% of total current wind power capacity is installed in the developed countries plus China and India. Our analysis shows that the economic competitiveness of wind power varies at wider range across countries or locations. A climate change damage cost of US$20/tCO 2 imposed to fossil fuels would make onshore wind competitive to all fossil fuels for power generation; however, the same would not happen to offshore wind, with few exceptions, even if the damage cost is increased to US$100/tCO 2 . To overcome a large number of technical, financial, institutional, market and other barriers to wind power, many countries have employed various policy instruments, including capital subsidies, tax incentives, tradable energy certificates, feed-in tariffs, grid access guarantees and mandatory standards. Besides, climate change mitigation policies, such as the Clean Development Mechanism, have played a pivotal role in promoting wind power. Despite these policies, intermittency, the main technical constraint, could remain as the major challenge to the future growth of wind power. - Highlights: • Global wind energy potential is enormous, yet the wind energy contribution is very small. • Existing policies are boosting development of wind power. • Costs of wind energy are higher than cost of fossil-based energies. • Reasonable premiums for climate change mitigation substantially promote wind power. • Intermittency is the key challenge to future development of wind power

Tontura associada a distúrbio do pânico e agorafobia: relato de caso e revisão da literatura Dizziness associated with panic disorder and agoraphobia: case report and literature review

Directory of Open Access Journals (Sweden)

João Daniel Caliman e Gurgel

2007-08-01

Full Text Available Tontura é uma das queixas mais freqüentes no consultório médico tanto primário quanto especializado. Muitos dos pacientes que se apresentam com tontura sem causa orgânica aparente, portanto considerados como portadores de tontura idiopática, podem ter um distúrbio psiquiátrico. Além disso, mesmo a tontura de causa orgânica pode desencadear ou exacerbar alterações psiquiátricas "latentes". Um dos distúrbios mais comumente associados à tontura é o Distúrbio do Pânico, com ou sem Agorafobia. O objetivo deste estudo é relatar o caso de uma paciente com essa associação e realizar uma revisão da literatura relacionada ao assunto.Dizziness is one of the most frequent complaints in both primary and specialized medical care facilities. Many dizzy patients, without a known organic cause, considered as having idiopathic dizziness, may have a psychiatric disorder. Besides, even organic dizziness may cause or exacerbate latent psychiatric alterations. One of the most common disorders associated with dizziness is Panic Disorder with or without Agoraphobia. The aim of this paper is to report a patient’s case and make a literature review on the subject.

Wind energy market study Eastern Europe. Poland

International Nuclear Information System (INIS)

Skjerk Christensen, P.

1994-04-01

The main objective of the THERMIE Associated Measure WE05 is to study market conditions and estimate the market for wind power in Eastern Europe. This report describes the results of a study of the conditions in Poland, which has been concentrated on the following areas: wind energy potential in Poland; data concerning the present structure of the power production system including costs; payback prices, subsidies, etc. with relation to renewable energy sources, especially wind power; information on existing wine turbines and their production in Poland; possibilities for co-production of wind turbines by Polish and EC factories, and rules and legislation pertaining to the establishment of wind turbines and to power production by wind, eg regulations related to grid connection, safety and environment. According to existing data there are possibilities for using the wind potential in certain parts of poland. The wind data have to be improved if particular sites are considered for wind parks. The current official plans concerning the energy system have taken renewable sources into consideration, including wind power that is estimated to contribute ∼ 1 GWh by 2005-2010. Wind turbines may be connected to the public grid with due regard to the strength of the line. Presently, the owner has to pay all the costs, however, new rules are under consideration. The conditions for the connection and operation of wind turbines have to be discussed with the particular utility on an an-hoc basis. (EG)

Detection of psychiatric morbidity in the primary medical care setting in Brazil Distúrbios psiquiátricos e assistência primária à saúde no Brasil

Directory of Open Access Journals (Sweden)

Jair de Jesus Mari

1987-12-01

Full Text Available The aims of this study were a to assess the ability of primary care doctors to make accurate ratings of psychiatric disturbance and b to evaluate the use of a case-finding questionnaire in the detection of psychiatric morbidity. The estudy took place in three primary care clinics in the city of São Paulo, Brazil, during a six-month survey. A time sample of consecutive adult attenders were asked to complete a case-finding questionnaire for psychiatric disorders (the Self Report Questionnaire - SRQ and a subsample were selected for a semi-structured psychiatric interview (the Clinical Interview Schedule - CIS. At the end of the consultation the primary care doctors were asked to assess, in a standardized way, the presence or absence of psychiatric disorder; these assessments were then compared with that ratings obtained in the psychiatric interview. A considerable proportion of minor psychiatric morbidity remained undetected by the three primary care doctors: the hidden morbidity ranged from 22% to 79%. When these were compared to those of the case-finding questionnaire, they were consistently lower, indicating that the use of these instruments can enhance the recognition of psychiatric disorders in primary care settings. Four strategies for adopting the questionnaire are described, and some of the clinical consequences of its use are discussed.Objetivou-se avaliar a habilidade de clínicos gerais em diagnosticar distúrbios emocionais na assistência primária, e investigar a possibilidade de se introduzir um questionário de "screening" para auxiliar o diagnóstico de doenças psiquiátricas. O estudo foi realizado em dois centros de saúde e um ambulatório de clínica geral na cidade de São Paulo (Brasil, por um período de 6 meses. Uma amostra representativa de pacientes adultos (16 anos atendidos por clínico geral preencheu um questionário de "screening" para distúrbios psiquiátricos menores. Uma sub-amostra foi selecionada para

75 FR 23263 - Alta Wind I, LLC; Alta Wind II, LLC; Alta Wind III, LLC; Alta Wind IV, LLC; Alta Wind V, LLC...

Science.gov (United States)

2010-05-03

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL10-62-000] Alta Wind I, LLC; Alta Wind II, LLC; Alta Wind III, LLC; Alta Wind IV, LLC; Alta Wind V, LLC; Alta Wind VI, LLC; Alta Wind VII, LLC; Alta Wind VIII, LLC; Alta Windpower Development, LLC; TGP Development Company, LLC...

77 FR 29633 - Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC...

Science.gov (United States)

2012-05-18

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL12-68-000] Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC, Alta Wind XIII, LLC, Alta Wind XIV, LLC, Alta Wind XV, LLC, Alta Windpower Development, LLC, TGP Development Company, LLC...

Wind energy in the next millennium and the next year

International Nuclear Information System (INIS)

Chabot, B.

1999-01-01

The rapid development of wind energy was once again confirmed in 1998 and everything points to the fact that this road will in the next century rapidly become the third channel of primary electricity production in the world, both in terms of annual sales and contribution of energy. In particular, a scenario for the development, of wind energy in the coming century is proposed, taking as model and minimum objective the historical development of success of wind energy should prove perfectly feasible, it is difficult to foresee in the short term the actual impact of the liberalization of electricity markets on existing inducements in favour of wind energy and even more difficult to estimate the effectiveness of new inducements more in line with this liberalization process. These difficulties may be overcome by selecting - for the long term scenario - a starting point within the next decade which is in line with the best market studies currently available and by constructing the model for variations in operational stock world-wide on the basis of a Rayleigh distribution, adjusted for the market conditions defined in the short term, in order that the future contributions defined in the short term, in order that the future contribution of wind energy might come to equal that of hydro-electricity before the end of the next century. (author)

Wind power development. Status and perspectives

International Nuclear Information System (INIS)

Morthorst, P.E.

1998-09-01

This is the final report on the status and long-term perspectives for the development of wind power, contributing to the Macro Task E1 on production cost for fusion and alternative technologies, part of the programme for Socio-Economic Research on Fusion. The report concentrates on the development of the production costs for wind power, limited to turbines connected to the public grid. The report shows status and perspectives for production costs for wind turbines until the year 2020-30. In general two trends have dominated the grid-connected wind turbine development until now: The average size of the turbines sold at the market place has increased substantially, while at the same time the efficiency of turbine electricity production has increased steadily. Together these trends have increased the cost-effectiveness of wind power by almost 45% over a time span of 9-10 years. Looking at perspectives, a substantial cut in wind power cost per kWh can be expected within the next 20-30 years. A survey performed for a number of long-term forecasts for the wind power technology in general shows a decrease in production costs of 2-2.5% p.a., which implies that the cost of wind-generated electricity would be halved by the year 2030, probably making it fully competitive to conventional fossil fuel based electricity production. (au)

A cybernetic view on wind-up.

Science.gov (United States)

Farajidavar, Aydin; Gharibzadeh, Shahriar; Towhidkhah, Farzad; Saeb, Sohrab

2006-01-01

Wind-up is described traditionally as a frequency dependent increase in the excitability of spinal cord neurons, evoked by electrical stimulation of afferent C-fibers. Different kinds of wind-up have been reported, but wind-up of Abeta fibers in hyperalgesic states has gained little attention. In this paper, we present a cybernetic view on Abeta fiber wind-up and consider the involved molecular mechanisms as feedback and feedforward processes. Furthermore, our previous hypothesis, the sprouting phenomenon, is included in this view. Considering the proposed model, wind-up in hyperalgesic states might leave out in three different ways: (1) blocking the NMDA receptors by increasing extracellular Mg2+, 2) blocking the receptors and channels that contribute to Ca2+ inward current, and 3) blocking the Abeta fibers by local anesthetics. It seems that wind-up may be inhibited more effectively by using these three blocking mechanisms simultaneously, because in this case, the feedback process (main controller), the feedforward process (trigger), and Abeta stimulation (trigger) would be inhibited concurrently. Wind up may aggravate the pain in clinical hyperalgesic situations such as post-surgical states, some neuropathic pains, fibromyalgia syndrome, and post-herpetic neuralgia. Surely, clinical studies are needed to validate the effectiveness of our abovementioned suggestions in relieving such clinical pains.

Relative contributions of wind and water erosion to total soil loss and its effect on soil properties in sloping croplands of the Chinese Loess Plateau.

Science.gov (United States)

Tuo, Dengfeng; Xu, Mingxiang; Gao, Guangyao

2018-08-15

Wind and water erosion are two dominant types of erosion that lead to soil and nutrient losses. Wind and water erosion may occur simultaneously to varying extents in semi-arid regions. The contributions of wind and water erosion to total erosion and their effects on soil quality, however, remains elusive. We used cesium-137 ( 137 Cs) inventories to estimate the total soil erosion and used the Revised Universal Soil Loss Equation (RUSLE) to quantify water erosion in sloping croplands. Wind erosion was estimated from the subtraction of the two. We also used 137 Cs inventories to calculate total soil erosion and validate the relationships of the soil quality and erosion at different slope aspects and positions. The results showed that wind erosion (1460tkm -2 a -1 ) on northwest-facing slope was responsible for approximately 39.7% of the total soil loss, and water erosion (2216tkm -2 a -1 ) accounted for approximately 60.3%. The erosion rates were 58.8% higher on northwest- than on southeast-facing slopes. Northwest-facing slopes had lower soil organic carbon, total nitrogen, clay, and silt contents than southeast-facing slopes, and thus, the 137 Cs inventories were lower, and the total soil erosions were higher on the northwest-facing slopes. The variations in soil physicochemical properties were related to total soil erosion. The lowest 137 Cs inventories and nutrient contents were recorded at the upper positions on the northwest-facing slopes due to the successive occurrence of more severe wind and water erosion at the same site. The results indicated that wind and water could accelerate the spatial variability of erosion rate and soil properties and cause serious decreases in the nutrient contents in sloping fields. Our research could help researchers develop soil strategies to reduce soil erosion according to the dominant erosion type when it occurs in a hilly agricultural area. Copyright © 2018 Elsevier B.V. All rights reserved.

Wind Power Technologies FY 2017 Budget At-A-Glance

Energy Technology Data Exchange (ETDEWEB)

None, None

2016-03-01

The Wind Program accelerates U.S. deployment of clean, affordable, and reliable domestic wind power through research, development, and demonstration activities. These advanced technology investments directly contribute to the goals for the United States to generate 80% of the nation’s electricity from clean, carbon-free energy sources by 2035; reduce carbon emissions 26%-28% below 2005 levels by 2025; and reduce carbon emissions 80% by 2050 by reducing costs and increasing performance of wind energy systems.

Sand transportation and reverse patterns over leeward face of sand dune

Science.gov (United States)

Jiang, Hong; Dun, Hongchao; Tong, Ding; Huang, Ning

2017-04-01

Sand saltation has complex interactions with turbulent flow and dune form. Most models of wind-blown sand consider ideal circumstances such as steady wind velocity and a flat surface, and the bulk of data on wind flow and sand transport over an individual dune has focused mostly on the influence of dune shape or inter-dune space on the wind flow, neglecting the effect of morphology on sand saltation, particularly airflow and sand transportation over the leeward slope. Wind flow structures over the leeward slope of sand dunes have a fundamental influence on the organization of sand dunes. In order to understand sand dune dynamics, lee face airflow and sediment transportation should be paid more attention. Previous field observations could not measure turbulent flow structure well because of the limited observation points and the influence of experiment structure on wind field. In addition, the reverse sand particles over leeward face could not be collected by sand trap in field. Numerous field observations could not measure turbulent flow structure because of the limited observation points and the influence of experimental structures on the wind field. In addition, the reverse transport of sand particles over leeward face could not be collected by sand traps in field. Therefore, this paper aims to investigate the turbulent flow structure and sand transport pattern over the leeward slope. A numerical model of sand saltation over slope terrain is constructed, which also considers the coupling effects between air flow and sand particles. The large eddy simulation method is used to model turbulent flow. Sand transport is simulated by tracking the trajectory of each sand particle. The results show that terrain significantly alters the turbulent air flow structure and wind-blown sand movement, especially over the leeward slope. Here, mass flux increases initially and then decreases with height in the reversed flow region in the direction of wind flow, and the mass flux

Statistical modelling of space-time processes with application to wind power

DEFF Research Database (Denmark)

Lenzi, Amanda

. This thesis aims at contributing to the wind power literature by building and evaluating new statistical techniques for producing forecasts at multiple locations and lead times using spatio-temporal information. By exploring the features of a rich portfolio of wind farms in western Denmark, we investigate...... propose spatial models for predicting wind power generation at two different time scales: for annual average wind power generation and for a high temporal resolution (typically wind power averages over 15-min time steps). In both cases, we use a spatial hierarchical statistical model in which spatial...

Intensity of geodynamic processes in the Lithuanian part of the Curonian Spit

Science.gov (United States)

Česnulevičius, Algimantas; Morkūnaitė, Regina; Bautrėnas, Artūras; Bevainis, Linas; Ovodas, Donatas

2017-06-01

The paper considers conditions and intensity of aeolian and dune slope transformation processes occurring in the wind-blown sand strips of the dunes of the Curonian Spit. An assessment of the intensity of aeolian processes was made based on the analysis of climatic factors and in situ observations. Transformations in aeolian relief forms were investigated based on the comparison of geodetic measurements and measurements of aerial photographs. Changes in micro-terraces of dune slopes were investigated through comparison of the results of repeated levelling and measurements of aerial photographs. The periods of weak, medium, and strong winds were distinguished, and sand moisture fluctuations affecting the beginning of aeolian processes were investigated. The wind-blown sand movements were found to start when sand moisture decreased by 2 % in the surface sand layer and by up to 5 % at a depth of 10 cm. In 2004-2016, the wind-blown sand movements affected the size of reference deflation relief forms: scarp length by 8 %, scarp width by 35 %, pothole length by 80 %, pothole width by 80 %, roll length by 17 %, roll width by 18 %, hollow length by 17 %, and hollow width by 39 %. The elementary relief forms in the leeward eastern slopes of the dunes experienced the strongest transformations. During a period of 5 months, the height of micro-terraces of the eastern slope of the Parnidis Dune changed from 0.05 to 0.64 cm. The change was related to fluctuations in precipitation intensity: in July-August 2016 the amount of precipitation increased 1.6-fold compared with the multiannual average, thus causing the change in the position of terrace ledges by 21 %.

The contribution of sting-jet windstorms to extreme wind risk in the North Atlantic

Science.gov (United States)

Hart, Neil C.; Gray, Suzanne L.; Clark, Peter A.

2016-04-01

Windstorms are a major winter weather risk for many countries in Europe. These storms are predominantly associated with explosively-developing extratropical cyclones that track across the region. A substantial body of literature exists on the synoptic-scale dynamics, predictability and climatology of such storms. More recently, interest in the mesoscale variability of the most damaging winds has led to a focus on the role of sting jets in enhancing windstorm severity. We present a present-era climatology of North Atlantic cyclones that had potential to produce sting jets. Considering only explosively-developing cyclones, those with sting-jet potential are more likely to have higher relative vorticity and associated low-level wind maxima. Furthermore, the strongest winds for sting-jet cyclones are more often in the cool sector, behind the cold front, when compared with other explosively-developing cyclones which commonly have strong warm-sector winds too. The tracks of sting-jet cyclones, and explosively-developing cyclones in general, show little offset from the climatological storm track. While rare over Europe, sting-jet cyclones are relatively frequent within the main storm track with up to one third of extratropical cyclones exhibiting sting-jet potential. Thus, the rarity and, until recently, lack of description of sting-jet windstorms is more due to the climatological storm track location away from highly-populated land masses, than due to an actual rarity of such storms in nature.

Integrating wind power in the (French) power system

International Nuclear Information System (INIS)

Pellen, A.

2007-03-01

RTE and EDF have no other technological option than to restrain the contribution of the French wind power fleet to base-load generation where it comes in direct competition with the nuclear power plants. The author aims to explain this situation and answer the following questions. Why the fossil fueled reactor fleet in France will not be affected by an evolution of the wind power capacity? Why, in France electric power generation-demand SYSTEM wind power cannot be a substitute for fossil fueled thermal units? (A.L.B.)

Experimental characterization of vertical-axis wind turbine noise.

Science.gov (United States)

Pearson, C E; Graham, W R

2015-01-01

Vertical-axis wind turbines are wind-energy generators suitable for use in urban environments. Their associated noise thus needs to be characterized and understood. As a first step, this work investigates the relative importance of harmonic and broadband contributions via model-scale wind-tunnel experiments. Cross-spectra from a pair of flush-mounted wall microphones exhibit both components, but further analysis shows that the broadband dominates at frequencies corresponding to the audible range in full-scale operation. This observation has detrimental implications for noise-prediction reliability and hence also for acoustic design optimization.

Wind and water erosion control on semiarid lands

International Nuclear Information System (INIS)

Siddoway, F.H.

1980-01-01

Commercial crop production on semiarid lands is difficult because insufficient water is often present to manage the system effectively. Erosion control presents the major management problem. The factors contributing to wind erosion and their interaction have been quantified into a wind erosion equation. The control of wind erosion through agronomic alteration of the various factors is discussed. The quantification and control of water erosion is also discussed with respect to the Universal Soil Loss Equation. Radioisotopes tracers have been used in conjunction with these erosion equations to measure soil losses. (author)

Impact of Shaft Stiffness on Inertial Response of Fixed Speed Wind Turbines

Institute of Scientific and Technical Information of China (English)

2012-01-01

Future power＇ system faces several challenges, one of them is the high penetration level of intermittent wind power generation, providing small or even no inertial response and being not contributing to the frequency stability. The effect of shaft stiffness on inertial response of fixed speed wind turbines is presented. Four different drive-train models based on the multi-body system are developed. The small-signal analysis demonstrates no significant differences between models in terms of electro-mechanical eigen-values for increasing shaft stiffness. The natural resonance frequency of drive-train torsion modes shows slightly different values between damped and undamped models, but no significant differences are found in the number-mass models. Time-domain simulations show the changes in the active power contribution of a wind farm based on a fixed speed wind turbine during the system frequency disturbance. The changes in the kinetic energy during the dynamic process are calculated and their contribution to the inertia constant is small and effective. The largest contribution of the kinetic energy is provided at the beginning of the system frequency disturbance to reduce the rate of the frequency change, it is positive for the frequency stability.

Global long-term cost dynamics of offshore wind electricity generation

NARCIS (Netherlands)

Gernaat, David E H J; Van Vuuren, Detlef P.; Van Vliet, Jasper; Sullivan, Patrick; Arent, Douglas J.

2014-01-01

Using the IMAGE/TIMER (The Targets IMage Energy Regional) long-term integrated assessment model, this paper explores the regional and global potential of offshore wind to contribute to global electricity production. We develop long-term cost supply curve for offshore wind, a representation of the

Atração e refração na educação a distância: constatações sobre o isolacionismo e a evasão do aluno

Directory of Open Access Journals (Sweden)

Gisela Biacchi Emanuelli

2011-06-01

Full Text Available http://dx.doi.org/10.5007/1983-4535.2011v4n2p205   A Lei de Diretrizes e Bases da Educação no Brasil incentiva a educação a distância como meio econômico e abrangente de acesso ao ensino e à aprendizagem. O método apresenta vantagens, mas não são suficientes para evitar que a auto-didática conduza à evasão dos alunos dos cursos. Amostra coletada junto à Instituição de Ensino Superior do Distrito Federal confirma o paradoxo da atração que a EaD exerce por sua economicidade e flexibilidade e a refração dos alunos por força do isolamento e pela necessidade do professor. Para demonstrar o binômio atração – refração do aluno ao ensino a distância partiu-se dessa amostragem para conclusões gerais, endossadas por outras pesquisas. O resultado coincide com a preocupação do Ministério da Educação de ser a Educação a Distância um meio de ensino no qual há índices significativos de evasão.

Relocation of major ions in snow along the tundra-taiga ecotone

Energy Technology Data Exchange (ETDEWEB)

Pomeroy, J.W.; Marsh, P. (Environment Canada, Saskatoon (Canada)); Lesack, L. (Simon Fraser Univeristy, Burnaby, (Canada))

1993-01-01

The chemistry of seasonal snowcovers north of Unuvik, Northwest Territories, Canada was stratified by biophysical landscape. In this region, deposition of ions in winter occurs largely through the redistribution of wind-blown snow with accumulations in forest-edges and valley sides 8 to 12 times that of the open tundra. While dominated by this snow redistribution, the loading of most ions, except for SO[sub 4][sup 2-], does not scale exactly with that of snow, there being several mechanisms by which ion concentrations become relatively enriched or depleted in various landscape units. Vaporisation during temperature-gradient metamorphism in shallow-snow and uptake during either photochemical reactions or gaseous scavenging to well-exposed snow transformed concentrations of NO[sub 3][sup -] by 50%. Dry deposition of aerosols to forested terrain and valley bottoms enriched Cl[sup -], Na[sup +], Mg[sup 2]-[sup +], K[sup +] and Ca[sup 2+] concentrations up to more than two-fold, however scavenging of aerosols to blowing snow particles contributed an additional 40% to the sea-salt enrichment and 20% to the Ca[sup 2+] enrichment in wind-blown treeline forests. It is concluded that central measurements of snow chemistry in the Arctic cannot be reliably extrapolated without reference to changes caused by over-winter physical and chemical metamorphic processes. Associating the physical/chemical changes with readily identifiable Arctic landscape units suggests a simple and robust method for spatial extrapolation. (au) (26 refs.)

Wind and solar energy incentives in Iran

International Nuclear Information System (INIS)

Taleghani, G.; Kazemi Karegar, H.

2006-01-01

Incentive have yet been viewed as a means of supporting technological developments until a new technology becomes cost competitive wind based electricity is not jet generally competitive with alternate sources of electricity such as fossil fuels. This paper presents the potential for wind and solar in Iran and shows how much electric energy is now produced by renewable power plants compared to steam and gas. The importance of renewable energy effects on Iran environment and economy is also discussed and the issue of the contribution of renewable energy for producing electricity in the future will be shown. Also this paper highlights the ability of Iran to manufacture the components of the wind turbine and solar system locally, and its effect on the price of wind turbine and solar energy

Performance of spanish wind turbines; Estadisticas de produccion de parques eolicos en Espana

Energy Technology Data Exchange (ETDEWEB)

Lago, C

1995-07-01

In this document we can find a statistical evaluation for the wind energy generation from each spanish wind farm referred to 1994, going on with the work that has been carried out since 1992, by initiative of the Wind Energy Division from Renewable Energy Institute. The purpose of this work is to contribute with interesting information for the wind environment and offer a global view from monthly performances of different wind farms. (Author)

Diagnóstico de competências individuais de tutores que atuam na modalidade a distância

Directory of Open Access Journals (Sweden)

João Paulo Fonseca Borges

2014-12-01

Full Text Available Neste trabalho, considera-se que a educação a distância (EaD tem representado papel imprescindível à aquisição de competências por parte de aprendizes nos cenários nacional e internacional. O papel dos tutores é estratégico à sua efetividade, especialmente no que tange a competências técnicas, relativas ao uso do ambiente virtual de aprendizagem (AVA, e comportamentais, estimulando o aprendiz a se comprometer e a não evadir. O presente trabalho teve como objetivo geral diagnosticar, empiricamente, competências individuais (técnicas e comportamentais necessárias ao desempenho efetivo da função de tutor no ensino a distância no âmbito da Universidade Aberta do Brasil (UAB. Por meio de dois estudos, foi realizada triangulação de dados, que envolveu fase qualitativa, composta por análise documental, entrevistas e grupos de foco (Estudo 1, e fase quantitativa, com aplicação de questionário fechado (Estudo 2. O tratamento dos dados qualitativos foi feito por análise de conteúdo, e dos dados quantitativos, por meio de análise estatística. A amostra (N=200 foi predominantemente feminina, atuando há pelo menos dois anos com tutoria. Os resultados apontaram baixas lacunas de competência, o que indica que as atividades de captação, treinamento e desenvolvimento de competências provavelmente têm sido realizadas de forma condizente com as necessidades das atribuições dos tutores. Sugere-se, para pesquisas futuras, a investigação com maior número de participantes, de modo a permitir análises estatísticas mais complexas.

Equivalent models of wind farms by using aggregated wind turbines and equivalent winds

International Nuclear Information System (INIS)

Fernandez, L.M.; Garcia, C.A.; Saenz, J.R.; Jurado, F.

2009-01-01

As a result of the increasing wind farms penetration on power systems, the wind farms begin to influence power system, and therefore the modeling of wind farms has become an interesting research topic. In this paper, new equivalent models of wind farms equipped with wind turbines based on squirrel-cage induction generators and doubly-fed induction generators are proposed to represent the collective behavior on large power systems simulations, instead of using a complete model of wind farms where all the wind turbines are modeled. The models proposed here are based on aggregating wind turbines into an equivalent wind turbine which receives an equivalent wind of the ones incident on the aggregated wind turbines. The equivalent wind turbine presents re-scaled power capacity and the same complete model as the individual wind turbines, which supposes the main feature of the present equivalent models. Two equivalent winds are evaluated in this work: (1) the average wind from the ones incident on the aggregated wind turbines with similar winds, and (2) an equivalent incoming wind derived from the power curve and the wind incident on each wind turbine. The effectiveness of the equivalent models to represent the collective response of the wind farm at the point of common coupling to grid is demonstrated by comparison with the wind farm response obtained from the detailed model during power system dynamic simulations, such as wind fluctuations and a grid disturbance. The present models can be used for grid integration studies of large power system with an important reduction of the model order and the computation time

78 FR 29364 - Exelon Corporation, Exelon Wind 1, LLC, Exelon Wind 2, LLC, Exelon Wind 3, LLC, Exelon Wind 4...

Science.gov (United States)

2013-05-20

...-005, QF07-55-005, QF07-56-005, QF07-257-004] Exelon Corporation, Exelon Wind 1, LLC, Exelon Wind 2, LLC, Exelon Wind 3, LLC, Exelon Wind 4, LLC, Exelon Wind 5, LLC, Exelon Wind 6, LLC, Exelon Wind 7, LLC, Exelon Wind 8, LLC, Exelon Wind 9, LLC, Exelon Wind 10, LLC, Exelon Wind 11, LLC, High Plains...

A percepção dos docentes frente a Educação a Distância no Stricto Sensu

Directory of Open Access Journals (Sweden)

Iris Linhares Pimenta

2011-08-01

Full Text Available A Educação à distância (EAD apresenta-se atualmente como um elemento de auxílio à democratização do ensino em todo o mundo. No Brasil, a interiorização da oferta do ensino superior carece de soluções inovadoras e neste cenário a EAD contribui cada vez mais com a ampliação e disponibilidade de elementos que possibilitam o alcance do conhecimento Este trabalho utilizou uma pesquisa exploratória, o universo de pesquisa foram catorze professores, onde a amostra por conveniência de cinco entrevistados, a coleta de dados foi através de entrevista com roteiro estruturado e para análise foi utilizada a análise de conteúdo. Conclui-se que o ensino à distância alcança cada dia mais espaço e ganha força diante da população que passa a utilizar esse modelo de forma mais natural fruto do avanço das tecnologias, passam a fazer parte do cotidiano da sociedade contemporânea. No Stricto Sensu acredita-se na utilização dessa modalidade de forma híbrida, uma vez que os encontros presenciais ainda apresentam resultados bastante objetivos de forma a não excluir plenamente o contato humano, que se acredita ser essencial na modalidade.

Proceedings of the wind energy industry conference : develop, innovate, export : held in conjunction with Quebec's first wind energy industry gala

International Nuclear Information System (INIS)

2008-01-01

This conference was dedicated to the wind energy industry and business opportunities in Quebec, the rest of Canada and abroad. It was held in conjunction with Quebec's first wind energy industry gala which highlighted the organizations and individuals that have made outstanding contributions to the wind power sector in Quebec over the past three years. The entire conference focused on current and future requests for proposals in Quebec, innovation, and exports. Some fifteen reputed speakers shared their knowledge and experience regarding technological development and technical support available in Quebec. It was intended to clarify current and future issues affecting the wind power industry and to build key relations with leading wind energy players. The sessions of the conference were entitled: the wind energy industry in Quebec and Canada; issues surrounding requests for proposals; the players involved in the request for proposals; visual impacts of wind farms; data transmission during wind farm construction; innovating to move ahead of the crowd; innovation in practice; exporting as a means of development; and, exports in practice. A tour of the Baie-des-Sable wind farm was also provided. The conference featured 24 presentations, of which 2 have been catalogued separately for inclusion in this database. refs., tabs., figs

Short-Term Wind Speed Forecasting Using Decomposition-Based Neural Networks Combining Abnormal Detection Method

Directory of Open Access Journals (Sweden)

Xuejun Chen

2014-01-01

Full Text Available As one of the most promising renewable resources in electricity generation, wind energy is acknowledged for its significant environmental contributions and economic competitiveness. Because wind fluctuates with strong variation, it is quite difficult to describe the characteristics of wind or to estimate the power output that will be injected into the grid. In particular, short-term wind speed forecasting, an essential support for the regulatory actions and short-term load dispatching planning during the operation of wind farms, is currently regarded as one of the most difficult problems to be solved. This paper contributes to short-term wind speed forecasting by developing two three-stage hybrid approaches; both are combinations of the five-three-Hanning (53H weighted average smoothing method, ensemble empirical mode decomposition (EEMD algorithm, and nonlinear autoregressive (NAR neural networks. The chosen datasets are ten-minute wind speed observations, including twelve samples, and our simulation indicates that the proposed methods perform much better than the traditional ones when addressing short-term wind speed forecasting problems.

SAT-WIND project. Final report[Winds from satellites for offshore and coastal wind energy mapping and wind-indexing

Energy Technology Data Exchange (ETDEWEB)

Hasager, C.B.; Astrup, P.; Nielsen, M. (and others)

2007-04-15

The SAT-WIND project 'Winds from satellites for offshore and coastal wind energy mapping and wind-indexing' was a research project funded by STVF/DSF in the years 2003 to 2006 (Sagsnr. 2058-03-0006). The goal of the project was to verify the applicability of satellite wind maps derived from passive microwave, altimeter, scatterometer and imaging Synthetic Aperture Radar (SAR) technologies for wind energy tools for wind resources and wind-indexing. The study area was the Danish Seas including the North Sea, interior seas and the Baltic Sea. The report describes technical details on the satellite data sources including: 1) passive microwave (SSM/I, AMSR-E), 2) passive microwave polarimetric (WindSat), 3) scatterometer (ERS, QuikSCAT, Midori-2 and NSCAT), 4) altimeter (ERS, Topex, Poseidon, GFO-1, Jason-1), 5) SAR (ERS, Envisat). The SAR wind maps were treated in S-WAsP developed by Risoe National Laboratory in cooperation with GRAS A/S in the innovative project SAT-WIND-SMV (Sagsnr. 2104-05-0084) in the years 2005 and 2006 in parallel with SAT-WIND. The results from the SAT-WIND project are presented. These include ocean wind statistics, offshore wind resource estimates and comparison results for wind-indexing. (au)

SAT-WIND project. Final report[Winds from satellites for offshore and coastal wind energy mapping and wind-indexing

Energy Technology Data Exchange (ETDEWEB)

Hasager, C B; Astrup, P; Nielsen, M [and others

2007-04-15

The SAT-WIND project 'Winds from satellites for offshore and coastal wind energy mapping and wind-indexing' was a research project funded by STVF/DSF in the years 2003 to 2006 (Sagsnr. 2058-03-0006). The goal of the project was to verify the applicability of satellite wind maps derived from passive microwave, altimeter, scatterometer and imaging Synthetic Aperture Radar (SAR) technologies for wind energy tools for wind resources and wind-indexing. The study area was the Danish Seas including the North Sea, interior seas and the Baltic Sea. The report describes technical details on the satellite data sources including: 1) passive microwave (SSM/I, AMSR-E), 2) passive microwave polarimetric (WindSat), 3) scatterometer (ERS, QuikSCAT, Midori-2 and NSCAT), 4) altimeter (ERS, Topex, Poseidon, GFO-1, Jason-1), 5) SAR (ERS, Envisat). The SAR wind maps were treated in S-WAsP developed by Risoe National Laboratory in cooperation with GRAS A/S in the innovative project SAT-WIND-SMV (Sagsnr. 2104-05-0084) in the years 2005 and 2006 in parallel with SAT-WIND. The results from the SAT-WIND project are presented. These include ocean wind statistics, offshore wind resource estimates and comparison results for wind-indexing. (au)

Innovation and the price of wind energy in the US

International Nuclear Information System (INIS)

Berry, David

2009-01-01

In the last ten years, the wind energy industry has experienced many innovations resulting in wider deployment of wind energy, larger wind energy projects, larger wind turbines, and greater capacity factors. Using regression analysis, this paper examines the effects of technological improvements and other factors on the price of wind energy charged under long-term contracts in the United States. For wind energy projects completed during the period 1999-2006, higher capacity factors and larger wind farms contributed to reductions in wind energy contract prices paid by regulated investor owned utilities in 2007. However, this effect was offset by rising construction costs. Turbine size (in MW) shows no clear relationship to contract prices, possibly because there may be opposing factors tending to decrease costs as turbine size increases and tending to increase costs as turbine size increases. Wind energy is generally a low-cost resource that is competitive with natural gas-fired power generation.

CONDITIONED ANALYSIS OF HIGH-LATITUDE SOLAR WIND INTERMITTENCY

International Nuclear Information System (INIS)

D'Amicis, R.; Consolini, G.; Bavassano, B.; Bruno, R.

2012-01-01

The solar wind is a turbulent medium displaying intermittency. Its intermittent features have been widely documented and studied, showing how the intermittent character is different in fast and slow wind. In this paper, a statistical conditioned analysis of the solar wind intermittency for a period of high-latitude fast solar wind is presented. In particular, the intermittent features are investigated as a function of the Alfvénic degree of fluctuations at a given scale. The results show that the main contribution to solar wind intermittency is due to non-Alfvénic structures, while Alfvénic increments are found to be characterized by a smaller level of intermittency than the previous ones. Furthermore, the lifetime statistics of Alfvénic periods are discussed in terms of a multiscale texture of randomly oriented flux tubes.

Harmonic Instability Source Identification in Large Wind Farms

DEFF Research Database (Denmark)

Ebrahimzadeh, Esmaeil; Blaabjerg, Frede; Wang, Xiongfei

2017-01-01

A large-scale power electronics based power system like a wind farm introduces the passive and active impedances. The interactions between the active and passive impedances can lead to harmonic-frequency oscillations above the fundamental frequency, which can be called harmonic instability....... This paper presents an approach to identify which wind turbine and which bus has more contribution to the harmonic instability problems. In the approach, a wind farm is modeled as a Multi-Input Multi-Output (MIMO) dynamic system. The poles of the MIMO transfer matrix are used to predict the system...... instability and the eigenvalues sensitivity analysis in respect to the elements of the MIMO matrix locates the most influencing buses of the wind farm. Time-domain simulations in PSCAD software environment for a 400-MW wind farm validate that the presented approach is an effective tool to determine the main...

Ecodesign framework for developing wind turbines

DEFF Research Database (Denmark)

Bonou, Alexandra; Skelton, Kristen; Olsen, Stig Irving

2016-01-01

such as workshops, pilots, interviews and life cycle assessment were applied. The ecodesign framework was aligned with the company's formal product lifecycle management process. When combined with life cycle assessment, the framework can identify potential environmental improvements and contribute to coherent......Despite a wind turbines perceived environmental benefits, there are still many improvements that can be made in the product development process to improve its environmental performance across life cycles. This is especially important as the wind power industry continues to grow, both in volume...... and size, in response to increasing global market demands. Planning, implementing, monitoring, documenting and communicating product related environmental activities of wind turbines in a life cycle management context is the focal point of this article. The development and application of an ecodesign...

Developing a Local Neurofuzzy Model for Short-Term Wind Power Forecasting

Directory of Open Access Journals (Sweden)

E. Faghihnia

2014-01-01

Full Text Available Large scale integration of wind generation capacity into power systems introduces operational challenges due to wind power uncertainty and variability. Therefore, accurate wind power forecast is important for reliable and economic operation of the power systems. Complexities and nonlinearities exhibited by wind power time series necessitate use of elaborative and sophisticated approaches for wind power forecasting. In this paper, a local neurofuzzy (LNF approach, trained by the polynomial model tree (POLYMOT learning algorithm, is proposed for short-term wind power forecasting. The LNF approach is constructed based on the contribution of local polynomial models which can efficiently model wind power generation. Data from Sotavento wind farm in Spain was used to validate the proposed LNF approach. Comparison between performance of the proposed approach and several recently published approaches illustrates capability of the LNF model for accurate wind power forecasting.

Modelling, Analysis and Control of DC-connected Wind Farms to Grid

DEFF Research Database (Denmark)

Iov, Florin; Sørensen, Poul; Hansen, Anca Daniela

2006-01-01

wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics the control capabilities of these wind turbines/farms are extended and thus the grid requirements...... are fulfilled.  However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid have less control capabilities. These wind turbines/farms cannot regulate their production and contribute to power system stability. A DC transmission system for connection...... of the active stall wind farms to the grid can provide these features and also maximize the produced power especially at low wind speeds by using variable voltage/frequency for the wind farm. The focus in this paper is in studying the variable speed operation for the active stall wind farms using a voltage...

ANEMOS: Development of a next generation wind power forecasting system for the large-scale integration of onshore and offshore wind farms.

Science.gov (United States)

Kariniotakis, G.; Anemos Team

2003-04-01

Objectives: Accurate forecasting of the wind energy production up to two days ahead is recognized as a major contribution for reliable large-scale wind power integration. Especially, in a liberalized electricity market, prediction tools enhance the position of wind energy compared to other forms of dispatchable generation. ANEMOS, is a new 3.5 years R&D project supported by the European Commission, that resembles research organizations and end-users with an important experience on the domain. The project aims to develop advanced forecasting models that will substantially outperform current methods. Emphasis is given to situations like complex terrain, extreme weather conditions, as well as to offshore prediction for which no specific tools currently exist. The prediction models will be implemented in a software platform and installed for online operation at onshore and offshore wind farms by the end-users participating in the project. Approach: The paper presents the methodology of the project. Initially, the prediction requirements are identified according to the profiles of the end-users. The project develops prediction models based on both a physical and an alternative statistical approach. Research on physical models gives emphasis to techniques for use in complex terrain and the development of prediction tools based on CFD techniques, advanced model output statistics or high-resolution meteorological information. Statistical models (i.e. based on artificial intelligence) are developed for downscaling, power curve representation, upscaling for prediction at regional or national level, etc. A benchmarking process is set-up to evaluate the performance of the developed models and to compare them with existing ones using a number of case studies. The synergy between statistical and physical approaches is examined to identify promising areas for further improvement of forecasting accuracy. Appropriate physical and statistical prediction models are also developed for

Repetitive model predictive approach to individual pitch control of wind turbines

DEFF Research Database (Denmark)

Adegas, Fabiano Daher; Stoustrup, Jakob; Odgaard, Peter Fogh

2011-01-01

prediction. As a consequence, individual pitch feed-forward control action is generated by the controller, taking ”future” wind disturbance into account. Information about the estimated wind spatial distribution one blade experience can be used in the prediction model to better control the next passing blade......Wind turbines are inherently exposed to nonuniform wind fields with of wind shear, tower shadow, and possible wake contributions. Asymmetrical aerodynamic rotor loads are a consequence of such periodic, repetitive wind disturbances experienced by the blades. A controller may estimate and use...... this peculiar disturbance pattern to better attenuate loads and regulate power by controlling the blade pitch angles individually. A novel model predictive (MPC) approach for individual pitch control of wind turbines is proposed in this paper. A repetitive wind disturbance model is incorporated into the MPC...

Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

OpenAIRE

Ju Feng; Wen Zhong Shen

2015-01-01

Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distributions of wind speed and wind direction, which is based on the parameters of sector-wise Weibull distributions and interpolations between direction sectors. It is applied to the wind measurement data a...

Fatores determinantes do uso de inovação tecnológica na educação a distância: um estudo com docentes dos cursos na área de negócios

OpenAIRE

Leal, Edvalda Araújo

2012-01-01

A proposta deste trabalho foi identificar os fatores que determina o uso de inovação tecnológica na Educação a Distância (EaD), na percepção dos docentes atuantes em cursos na área de negócios (Administração e Ciências Contábeis). Tendo em vista a expansão do oferecimento dos cursos na modalidade de educação a distância e a crescente adesão à tecnologia na educação, geram-se muitos questionamentos sobre as práticas pedagógicas dos professores, principalmente, aqueles relacionados aos desafios...

Wind energy generation and pollution control

International Nuclear Information System (INIS)

Mohibullah; Mohd Nishat Anwar

2009-01-01

Full text: In India, power generation from wind has emerged as one of the most successful programme. It is making meaningful contributions to the overall power requirements in some of the states. India is emerging as fifth nation in wind power generation. As per the projections made by Ministry of New and Renewable Energy, Govt. of India, 10 % of the total capacity of power generation will come from renewable energy sources by the year 2012. It is envisaged that 50 % of this capacity may come from wind power alone. The paper describes a WECS (Wind Energy Conversion Systems) structure implemented in the MATLAB-Simulink simulation environment by using the specialized PSB toolbox, designed for modeling and simulation of electrical equipment. A study is made to show effectiveness in pollution control. An analytical study is also made regarding the potential of wind energy in limiting the amount of green house gases added into the atmosphere per year in different states in India. The amount of green house gases which are saved in the process are calculated for nine wind potential sites in India. The amount of green house gases saved is considerable to reduce environmental pollution and saving in carbon credit. Approximately an amount of 70681 Euro per year may be saved if the scheme is implemented and use of wind energy known in India is fully utilized for power generation. (author)

Design and Operation of Power Systems with Large Amounts of Wind Power: Final Summary Report, IEA WIND Task 25, Phase Three 2012-2014

Energy Technology Data Exchange (ETDEWEB)

Holttinen, Hannele; Kiviluoma, Juha; Forcione, Alain; Milligan, Michael; Smith, Charles J.; Dillon, Jody; Dobschinski, Jan; van Roon, Serafin; Cutululis, Nicolaos; Orths, Antje; Eriksen, Peter Borre; Carlini, Enrico Maria; Estanqueiro, Ana; Bessa, Ricardo; Soder, Lennart; Farahmand, Hossein; Torres, Jose Rueda; Jianhua, Bai; Kondoh, Junji; Pineda, Ivan; Strbac, Goran

2016-06-01

This report summarizes recent findings on wind integration from the 16 countries participating in the International Energy Agency (IEA) Wind collaboration research Task 25 in 2012-2014. Both real experience and studies are reported. The national case studies address several impacts of wind power on electric power systems. In this report, they are grouped under long-term planning issues and short-term operational impacts. Long-term planning issues include grid planning and capacity adequacy. Short-term operational impacts include reliability, stability, reserves, and maximizing the value in operational timescales (balancing related issues). The first section presents variability and uncertainty of power system-wide wind power, and the last section presents recent wind integration studies for higher shares of wind power. Appendix 1 provides a summary of ongoing research in the national projects contributing to Task 25 in 2015-2017.

Panorama das pesquisas em educação a distância no Brasil Overview of researches in distance education in Brazil

Directory of Open Access Journals (Sweden)

Gardênia da Silva Abbad

2010-12-01

Full Text Available O investimento em treinamento, desenvolvimento e educação continua sendo um diferencial competitivo para as organizações. Nesse contexto, a educação a distância (EAD é analisada como uma possibilidade viável na construção de mecanismos que favoreçam a aprendizagem e qualificação contínuas e ao longo da vida. O presente estudo se insere nesse conjunto de reflexões. Seu objetivo é descrever brevemente o contexto e o foco das pesquisas sobre treinamentos a distância (TAD no Brasil, no período de 2003 a 2009, a partir de pesquisa bibliográfica e de dados do Anuário Brasileiro Estatístico de Educação Aberta e a Distância (ABRAED. A revisão da produção de conhecimentos em EAD no Brasil mostra a necessidade de mais pesquisas nas áreas de educação corporativa, qualificação profissional e avaliação. O ritmo das pesquisas é incompatível com o acelerado crescimento desse tipo de aprendizagem em organizações. Outras considerações são realizadas e uma agenda de pesquisa é proposta.Investment in training, development and education is a competitive advantage for organizations. In this context, distance learning education (EAD is regarded as a viable possibility in the construction of mechanisms which encourage continuous learning and acquirement of skills throughout life. The present study is within the set of reflections. Its goal is to briefly describe the context and focus of research on distance training in Brazil, from 2003 to 2009, based on literature and data review at the Brazilian Statistical Yearbook of Education Open and Distance (ABRAED. The production review of knowledge in distance education in Brazil shows the need for more research in corporate education, professional training, and evaluation. The pace of research is incompatible with the rapid growth of this type of learning in organizations. Other considerations are taken and a research agenda is proposed.

Experimental and computational study and development of the bituminous coal entrained-flow air-blown gasifier for IGCC

International Nuclear Information System (INIS)

Abaimov, N A; Osipov, P V; Ryzhkov, A F

2016-01-01

In the paper the development of the advanced bituminous coal entrained-flow air- blown gasifier for the high power integrated gasification combined cycle is considered. The computational fluid dynamics technique is used as the basic development tool. The experiment on the pressurized entrained-flow gasifier was performed by “NPO CKTI” JSC for the thermochemical processes submodel verification. The kinetic constants for Kuznetsk bituminous coal (flame coal), obtained by thermal gravimetric analysis method, are used in the model. The calculation results obtained by the CFD model are in satisfactory agreements with experimental data. On the basis of the verified model the advanced gasifier structure was suggested which permits to increase the hydrogen content in the synthesis gas and consequently to improve the gas turbine efficiency. In order to meet the specified requirements vapor is added on the second stage of MHI type gasifier and heat necessary for air gasification is compensated by supplemental heating of the blasting air. (paper)

Wind park of the Hannover-Braunschweigische Stromversorgungs-Aktiengesellschaft (HASTRA)

International Nuclear Information System (INIS)

Hahnefeld; Fenske.

1993-01-01

In order to achieve the share of wind power in public electric power supply prognosticated for the year 2005 by the Enquete Commission it is necessary that favourable sites are utilized optimally with plants of medium size. The wind park of HASTRA serves as a reference plant. In the scope of this contribution the following subjects regarding this plant are mentioned: site and plant selection, licensing procedure, investments and profitability, energy economic aspects of wind power as well as operating experience and public acceptance. (BWI) [de

2016 Wind Technologies Market Report

Energy Technology Data Exchange (ETDEWEB)

Wiser, Ryan H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bolinger, Mark [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2017-08-10

The U.S. Department of Energy (DOE)’s Wind Technologies Market Report provides an annual overview of trends in the U.S. wind power market. You can find the report, a presentation, and a data file on the Files tab, below. Additionally, several data visualizations are available in the Data Visualizations tab. Highlights of this year’s report include: -Wind power additions continued at a rapid clip in 2016: $13 billion was invested in new wind power plants in 2016. In 2016, wind energy contributed 5.6% of the nation’s electricity supply, more than 10% of total electricity generation in fourteen states, and 29% to 37% in three of those states—Iowa, South Dakota, and Kansas. -Bigger turbines are enhancing wind project performance: Increased blade lengths, in particular, have dramatically increased wind project capacity factors, one measure of project performance. For example, the average 2016 capacity factor among projects built in 2014 and 2015 was 42.6%, compared to an average of 32.1% among projects built from 2004 to 2011 and 25.4% among projects built from 1998 to 2001. -Low wind turbine pricing continues to push down installed project costs: Wind turbine prices have fallen from their highs in 2008, to $800–$1,100/kW. Overall, the average installed cost of wind projects in 2016 was $1,590/kW, down $780/kW from the peak in 2009 and 2010. -Wind energy prices remain low: After topping out at nearly 7¢/kWh for power purchase agreements (PPAs) executed in 2009, the national average price of wind PPAs has dropped to around 2¢/kWh—though this nationwide average is dominated by projects that hail from the lowest-priced Interior region of the country (such as Texas, Iowa, Oklahoma). These prices, which are possible in part due to federal tax support, compare favorably to the projected future fuel costs of gas-fired generation. -The supply chain continued to adjust to swings in domestic demand for wind equipment: Wind sector employment reached a new high of

Evaluation of Noise Exposure Secondary to Wind Noise in Cyclists.

Science.gov (United States)

Seidman, Michael D; Wertz, Anna G; Smith, Matthew M; Jacob, Steve; Ahsan, Syed F

2017-11-01

Objective Determine if the noise levels of wind exposure experienced by cyclists reach levels that could contribute to noise-induced hearing loss. Study Design Industrial lab research. Setting Industrial wind tunnel. Subjects and Methods A commercial-grade electric wind tunnel was used to simulate different speeds encountered by a cyclist. A single cyclist was used during the simulation for audiometric measurements. Microphones attached near the ears of the cyclist were used to measure the sound (dB sound pressure level) experienced by the cyclist. Loudness levels were measured with the head positioned at 15-degree increments from 0 degrees to 180 degrees relative to the oncoming wind at different speeds (10-60 mph). Results Wind noise ranged from 84.9 dB at 10 mph and increased proportionally with speed to a maximum of 120.3 dB at 60 mph. The maximum of 120.3 dB was measured at the downwind ear when the ear was 90 degrees away from the wind. Conclusions Wind noise experienced by a cyclist is proportional to the speed and the directionality of the wind current. Turbulent air flow patterns are observed that contribute to increased sound exposure in the downwind ear. Consideration of ear deflection equipment without compromising sound awareness for cyclists during prolonged rides is advised to avoid potential noise trauma. Future research is warranted and can include long-term studies including dosimetry measures of the sound and yearly pre- and postexposure audiograms of cyclists to detect if any hearing loss occurs with long-term cycling.

Simulating European wind power generation applying statistical downscaling to reanalysis data

DEFF Research Database (Denmark)

Gonzalez-Aparicio, I.; Monforti, F.; Volker, Patrick

2017-01-01

generation time series dataset for the EU-28 and neighbouring countries at hourly intervals and at different geographical aggregation levels (country, bidding zone and administrative territorial unit), for a 30 year period taking into account the wind generating fleet at the end of 2015. (C) 2017 The Authors...... and characteristics of the wind resource which is related to the accuracy of the approach in converting wind speed data into power values. One of the main factors contributing to the uncertainty in these conversion methods is the selection of the spatial resolution. Although numerical weather prediction models can...... could not be captured by the use of a reanalysis technique and could be translated into misinterpretations of the wind power peaks, ramping capacities, the behaviour of power prices, as well as bidding strategies for the electricity market. This study contributes to the understanding what is captured...

Wind turbines, is it just wind?

International Nuclear Information System (INIS)

Boiteux, M.

2012-01-01

The author first outlines that wind energy is not only random, but almost absent in extreme situations when it would be needed (for example and notably, very cold weather without wind). He suggests the association of a gas turbine to each wind turbine, so that the gas turbine will replace non operating wind turbines. He notices that wind turbines are not proximity energy as they were said to be, and that profitability in fact requires tens of grouped giant wind turbines. He also outlines the high cost of construction of grids for the connection of these wind turbines. Thus, he states that wind energy is far from being profitable in the present conditions of electricity tariffs in France

Wind energy in Denmark and within the Elsam utility area

International Nuclear Information System (INIS)

Friis, P.; Grauballe, J.

1995-01-01

At the turn of 1994, 3,700 wind turbines, with a total installed capacity of 540 MW were connected to the Danish utility grid. In 1994 these turbines fed 1,118 GWh wind energy into the grid, corresponding to approximately 3.3% of the total electricity consumption. The ELSAM utility area supplies the electric energy consumed by half the Danish population. The area has a large wind energy potential and approx. 75% of the installed wind energy capacity in Denmark is situated here accounting for 400 MW. In 1994 the ELSAM utilities supplied a total of 18,450 GWh with wind power contributing 850 GWh, i.e. 4.6% of the ELSAM sales to the consumers. (Author)

Proceedings of CanWEA's 2006 small wind conference

International Nuclear Information System (INIS)

2006-01-01

Small wind energy systems are typically comprised of a single wind turbine for on-site power generation of between 300 watts to 100 kW. They are suited for use in remote locations, as well as on farms or for on-grid residential applications. Small wind customers are concerned about environmental issues as well as the reliability of the electric power grid. Recent increases in electricity prices have contributed to a renewed interest in small wind systems. Primary distributed wind market growth areas include residential grid-connected sites; schools, public facilities and farmer co-operatives; and farms, business and industry. Growth in small wind applications has not been matched by an increase in government incentives, and the lack of clear technical standards for wind systems may negatively impact public perceptions of the industry. This conference provided an overview of the small wind industry in Canada. The conference provided a forum for wind industry members, government agencies, and academics to explore challenges and barriers to the growth of the small wind industry. The conference, which was held as part of the larger annual CanWEA 2006 conference and trade show, was divided into 3 sessions: (1) policies to support small wind; (2) doing business with small wind; and (3) small wind technical insights. Recommendations for the certification of small wind turbines were provided, as well as a model zoning by-law. Technical issues included the development of high penetration wind/diesel systems for isolated communities in the Arctic; technical challenges with small turbines; and siting guidelines for consumers. Several small wind turbine owners reviewed some of the challenges of both buying and using wind systems. Technical and market barriers for distributed wind applications were also discussed. The conference featured 13 presentations, of which 12 were catalogued separately for inclusion in this database. refs., tabs., figs

Concept Specifications/Prerequisites for DeepWind Deliverable D8.1

DEFF Research Database (Denmark)

Schmidt Paulsen, Uwe; Schløer, Signe; Larsén, Xiaoli Guo

(NL), NREL(USA), STATOIL(N), VESTAS(DK) and NENUPHAR(F). The report discuss the design considerations for offshore wind turbines, both in general and specifically for Darrieus-type floating turbines, as is the focus of the DeepWind project. The project is considered in a North Sea environment, notably close......The work is a result of the contributions within the DeepWind project which is supported by the European Commission, Grant 256769 FP7 Energy 2010 - Future emerging technologies, and by the DeepWind beneficiaries: DTU(DK), AAU(DK), TUDELFT(NL), TUTRENTO(I), DHI(DK), SINTEF(N), MARINTEK(N), MARIN...

Sleep disorders and starting time to school impair balance in 5-year-old children Distúrbios do sono, período escolar e equilíbrio em crianças com 5 anos de idade

Directory of Open Access Journals (Sweden)

Cristiane Aparecida Moran

2005-09-01

Full Text Available OBJECTIVE: To verify if sleep disorders and differents starting time to school have impaired motor skills in 5-year-old children. METHOD: Cross-sectional design consisting of 132 children with sleep disorders and 136 normal controls of the public school in the city of São Paulo. The group with sleep disorders was identified based on a questionnaire, and motor tests for global motor coordination, fine motor coordination, perceptual-motor coordination, and static and dynamic balance were applied in all children. RESULTS: In the static balance test, more specifically in the sharpened Romberg (Tandem test, 34% of boys from the study group, who studied in the morning, failed the test (p OBJETIVO: Verificar se distúrbios do sono e diferentes períodos escolares comprometem as habilidades motoras de crianças de 5 anos. MÉTODO: Realizou-se estudo transversal com 132 crianças com distúrbio do sono e 136 controles normais de escolas públicas da cidade de São Paulo. Foram utilizados questionários para distúrbios do sono e testes para coordenação motora global, motora fina, percepto-motora, equilíbrio estático e dinâmico. RESULTADOS: No teste de equilíbrio estático, mais especificamente na prova pé ante pé, 34% dos meninos do grupo estudo, que estudavam no período da manhã, falharam no teste (p < 0,05. Na prova de apoio monopodal, 62% dos meninos do grupo estudo, que estudavam no período da manhã, falharam no teste (p < 0,05. CONCLUSÃO: Este estudo sugere que os distúrbios do sono podem interagir com o período escolar e alterar a performance motora, principalmente de meninos que estudam no período da manhã.

Wind: new wind markets

International Nuclear Information System (INIS)

Cameron, A.

2005-01-01

The June 2005 edition of 'Wind Force 12' suggests that wind could generate 12% of global electricity requirements by 2020. But what moves a potential market into an emerging one? Geographical factors include a good wind resource, plenty of open space and the ability to get the generated electricity to end-users. A country's political framework is equally important, with fixed price systems, renewable quota systems and political will all playing a part. Some potential wind markets around the world are thought to have the conditions necessary to become key players in the wind industry. The emerging markets in countries such as Australia, Brazil, Canada, France, Japan and the Philippines are highlighted as examples

A General Probabilistic Forecasting Framework for Offshore Wind Power Fluctuations

DEFF Research Database (Denmark)

Trombe, Pierre-Julien; Pinson, Pierre; Madsen, Henrik

2012-01-01

Accurate wind power forecasts highly contribute to the integration of wind power into power systems. The focus of the present study is on large-scale offshore wind farms and the complexity of generating accurate probabilistic forecasts of wind power fluctuations at time-scales of a few minutes...... fluctuations are characterized by highly volatile dynamics which are difficult to capture and predict. Due to the lack of adequate on-site meteorological observations to relate these dynamics to meteorological phenomena, we propose a general model formulation based on a statistical approach and historical wind...... power measurements only. We introduce an advanced Markov Chain Monte Carlo (MCMC) estimation method to account for the different features observed in an empirical time series of wind power: autocorrelation, heteroscedasticity and regime-switching. The model we propose is an extension of Markov...

Limited Area Forecasting and Statistical Modelling for Wind Energy Scheduling

DEFF Research Database (Denmark)

Rosgaard, Martin Haubjerg

forecast accuracy for operational wind power scheduling. Numerical weather prediction history and scales of atmospheric motion are summarised, followed by a literature review of limited area wind speed forecasting. Hereafter, the original contribution to research on the topic is outlined. The quality...... control of wind farm data used as forecast reference is described in detail, and a preliminary limited area forecasting study illustrates the aggravation of issues related to numerical orography representation and accurate reference coordinates at ne weather model resolutions. For the o shore and coastal...... sites studied limited area forecasting is found to deteriorate wind speed prediction accuracy, while inland results exhibit a steady forecast performance increase with weather model resolution. Temporal smoothing of wind speed forecasts is shown to improve wind power forecast performance by up to almost...

Optimal application of climate data to the development of design wind speeds

DEFF Research Database (Denmark)

Kruger, Andries C.; Retief, Johan V.; Goliger, Adam M.

2014-01-01

Africa (WASA project) focuses, amongst others, on the development of a Regional Extreme Wind Climate (REWC) for South Africa. Wind farms are planned for areas with relatively strong and sustained winds, with wind turbines classed according to their suitability for different wind conditions. The REWC...... statistics are used during the construction and design phase to make assumptions about the local strong wind climate that the wind turbines will be exposed to, with the local environment and topography as additional input. The simultaneous development of the REWC and revision of the extreme wind statistics...... of South Africa created an opportunity to bring together a range of expertise that could contribute to the optimal development of design wind speed information. These include the knowledge of the statistical extraction of extreme wind observations from reanalysis and model data, the quality control...

Galactic Winds and the Role Played by Massive Stars

Science.gov (United States)

Heckman, Timothy M.; Thompson, Todd A.

Galactic winds from star-forming galaxies play at key role in the evolution of galaxies and the intergalactic medium. They transport metals out of galaxies, chemically enriching the intergalactic medium and modifying the chemical evolution of galaxies. They affect the surrounding interstellar and circumgalactic media, thereby influencing the growth of galaxies though gas accretion and star formation. In this contribution we first summarize the physical mechanisms by which the momentum and energy output from a population of massive stars and associated supernovae can drive galactic winds. We use the prototypical example of M 82 to illustrate the multiphase nature of galactic winds. We then describe how the basic properties of galactic winds are derived from the data, and summarize how the properties of galactic winds vary systematically with the properties of the galaxies that launch them. We conclude with a brief discussion of the broad implications of galactic winds.

Application of a ray theory model to the prediction of noise emissions from isolated wind turbines and wind parks

International Nuclear Information System (INIS)

Prospathopoulos, John M.; Voutsinas, Spyros G.

2006-01-01

Various propagation models have been developed to estimate the level of noise near residential areas. Predictions and measurements have proven that proper modelling of the propagation medium is of particular importance. In the present work, calculations are performed using a ray theory methodology. The ray trajectory and transport equations are derived from the linear acoustics equations for a moving medium in three dimensions. Ground and atmospheric absorption, wave refraction and diffraction and atmospheric turbulence are taken into account by introducing appropriate coefficients in the equations. In the case of a wind turbine (W/T) it is assumed that noise is produced by a point source located at the rotor centre. Given the sound power spectrum, the noise spectrum at the receiver is obtained by solving the axisymmetric propagation problem. The procedure consists of (a) finding the eigenrays, (b) calculating the energy losses along the eigenrays and (c) synthesizing the sound pressure level (SPL) by superposing the contributions of the eigenrays. In the case of a wind park the total SPL is calculated by superposing the contributions of all W/Ts. Application is made to five cases of isolated W/Ts in terrains of varying complexity. In flat or even smooth terrain the predictions agree well with the measurements. In complex terrain the predictions can be considered satisfactory, taking into account the assumption of constant wind velocity profile. Application to a wind park shows clearly the influence of the terrain on the wind velocity and consequently on the SPL. (Author)

Soil erosion rates caused by wind and saltating sand stresses in a wind tunnel

International Nuclear Information System (INIS)

Ligotke, M.W.

1993-02-01

Wind erosion tests were performed in a wind tunnel in support of the development of long-term protective barriers to cap stabilized waste sites at the Hanford Site. Controlled wind and saltating sand erosive stresses were applied to physical models of barrier surface layers to simulate worst-case eolian erosive stresses. The goal of these tests was to provide information useful to the design and evaluation of the surface layer composition of an arid-region waste site barrier concept that incorporates a deep fine-soil reservoir. A surface layer composition is needed that will form an armor resistant to eolian erosion during periods of extreme dry climatic conditions, especially when such conditions result in the elimination or reduction of vegetation by water deprivation or wildfire. Because of the life span required of Hanford waste barriers, it is important that additional work follow these wind tunnel studies. A modeling effort is planned to aid the interpretation of test results with respect to the suitability of pea gravel to protect the finite-soil reservoir during long periods of climatic stress. It is additionally recommended that wind tunnel tests be continued and field data be obtained at prototype or actual barrier sites. Results wig contribute to barrier design efforts and provide confidence in the design of long-term waste site caps for and regions

Emissions and temperature benefits: The role of wind power in China.

Science.gov (United States)

Duan, Hongbo

2017-01-01

As a non-fossil technology, wind power has an enormous advantage over coal because of its role in climate change mitigation. Therefore, it is important to investigate how substituting wind power for coal-fired electricity will affect emission reductions, changes in radiative forcing and rising temperatures, particularly in the context of emission limits. We developed an integrated methodology that includes two parts: an energy-economy-environmental (3E) integrated model and an emission-temperature response model. The former is used to simulate the dynamic relationships between economic output, wind energy and greenhouse gas (GHG) emissions; the latter is used to evaluate changes in radiative forcing and warming. Under the present development projection, wind energy cannot serve as a major force in curbing emissions, even under the strictest space-restraining scenario. China's temperature contribution to global warming will be up to 21.76% if warming is limited to 2 degrees. With the wind-for-coal power substitution, the corresponding contribution to global radiative forcing increase and temperature rise will decrease by up to 10% and 6.57%, respectively. Substituting wind power for coal-fired electricity has positive effects on emission reductions and warming control. However, wind energy alone is insufficient for climate change mitigation. It forms an important component of the renewable energy portfolio used to combat global warming. Copyright © 2016 Elsevier Inc. All rights reserved.

Fatores de risco para o desenvolvimento de distúrbios alimentares: um estudo em universitárias Risk factors in the development of eating disorders: study in a group of college women

Directory of Open Access Journals (Sweden)

Giovanna Medeiros Rataichesck FIATES

2001-01-01

Full Text Available Este trabalho buscou identificar, em mulheres universitárias, aquelas que apresentavam fatores de risco para o desenvolvimento de distúrbios alimentares. Aplicou-se o questionário Eating Attitudes Test em 221 mulheres (114 estudantes de nutrição e 107 estudantes de outras áreas não relacionadas à saúde. Os resultados indicaram que 22,17% das estudantes apresentaram fatores de risco para o desenvolvimento de distúrbio alimentar, sendo que no grupo de alunas da nutrição o percentual foi maior (25,43% do que no grupo de estudantes de outros cursos (18,69%. Embora a diferença não tenha sido significativa, as futuras nutricionistas podem estar inseridas em um ambiente mais favorável ao desenvolvimento de distúrbios alimentares.This work studied a group of 221 college women, to identify those who presented risk factors compatible with the development of eating disorders. The Eating Attitudes Test was applied to 221 women (114 nutrition students and 107 students from other areas, unrelated to the health field. Results indicated that 22.17% of the group presented risk factors in the development of an eating disorder. Nutrition students presented a higher percentage (25.43% than the other students (18.69%, but this difference was not significant. However, women who study nutrition may be exposed to an environment more propitious to the development of eating disorders.

Grid Integration of Offshore Wind | Wind | NREL

Science.gov (United States)

Grid Integration of Offshore Wind Grid Integration of Offshore Wind Much can be learned from the existing land-based integration research for handling the variability and uncertainty of the wind resource Arklow Bank offshore wind park consists of seven GE Wind 3.6-MW wind turbines. Integration and

Development of wind energy in Denmark

Energy Technology Data Exchange (ETDEWEB)

Nielsen, P. [Danske Elvaerkers Forenings Udredningsafdeling (DEFU), Lyngby (Denmark)

1994-12-31

In Denmark, wind energy has for centuries been used for many purposes, among these water pumping, milling of grain, and electricity generation. This paper discusses the development of grid-connected wind turbines on a large-scale sponsored by the national government, the Commission of the European Communities and the Danish electric utilities, and small-scale grid-connected wind turbines both privately and utility owned. Siting investigations have shown that it is possible to find sites of reasonable quality for a potential electricity production of at least 10 percent of the expected electricity consumption in 2005 which corresponds to about 1500 MW of installed capacity. Regulations were introduced in 1991 limiting the owners of wind turbines to noise levels from the wind turbines to the existing levels of 45 dB in rural areas, and 40 dB in residential areas and other noise sensitive areas. Studies of the effects of wind turbines on birds found that compared with other human activities, such as farming and car driving, a wind turbine in a bird sanctuary does not have a particular impact on bird life, although there were some effects such as birds moving away from the turbine to breed, forage etc. The Danish Government`s aim to establish 1500 MW of wind power by the year 2005 has some problems. Funding for research, a combination of agreements with the utilities, and production subsidies to private persons and co-operative societies is contributing to the resolution of these problems. 1 tab., 2 figs.

Aeroservoelasticity of wind turbines

Energy Technology Data Exchange (ETDEWEB)

Skovmose Kallesoee, B.

2007-12-14

This thesis deals with the fundamental aeroelastic interaction between structural motion, Pitch action and control for a wind turbine blade. As wind turbines become larger, the interaction between pitch action, blade motion, aerodynamic forces, and control become even more important to understand and address. The main contribution of this thesis is the development of an aeroelastic blade model which on the one hand includes the important effects of steady state blade deformation, gravity and pitch action, and on the other it is transparent, suitable for analytical analysis and parameter studies, and furthermore linear and therefore suitable for control design. The development of the primary aeroelastic blade model is divided into four steps: 1) Nonlinear partial differential equations (PDEs) of structural blade motion are derived together with equations of pitch action and rotor speed; the individual terms in these equations are discussed and given physical interpretations; 2) Steady state blade deformation and induced velocities are computed by combining the PDEs with a steady state aerodynamic model; 3) Aeroelastic modes of motion are computed by combining the linearized PDEs with a linear unsteady aerodynamic model; this model is used to analyze how blade deformation effects the modes of motion; and 4) the linear aeroelastic blade model is derived by a modal expansion of the linearized PDEs combined with a linear unsteady aerodynamic model. The aeroelastic blade model has many similarities to a 2D blade section model, and it can be used instead of this in many applications, giving a transparent connection to a real wind turbine blade. In this work the aeroelastic blade model is used to analyze interaction between pitch action, blade motion and wind speed variations. Furthermore the model is used to develop a state estimator for estimating the wind speed and wind shear, and to suggest a load reducing controller. The state estimator estimates the wind shear very

Induced Torques on Synchronous Generators from Operation of Wind Power Plant based on Full-Load Converter Interfaced Wind Turbines

DEFF Research Database (Denmark)

Knüppel, Thyge; Nielsen, Jørgen N.; Jensen, Kim H.

2011-01-01

It is expected that large wind power plants (WPP) contribute to stable and reliable operation of the electric power system. This includes participation with delivery of system services such as voltage and frequency support. With variable-speed WPPs this can be achieved by adding auxiliary...... be predicted with the presented method. The work is based on a nonlinear, dynamic model of the 3.6 MW Siemens Wind Power wind turbine....... controllers that control the active and reactive power output accordingly. While being designed for a given system service, any feedback control affects the closed-loop behavior of the overall system and thereby its small-signal stability properties. Eigenvalue analysis conveniently determines the stability...

Characteristics for wind energy and wind turbines by considering vertical wind shear

Institute of Scientific and Technical Information of China (English)

郑玉巧; 赵荣珍

2015-01-01

The probability distributions of wind speeds and the availability of wind turbines were investigated by considering the vertical wind shear. Based on the wind speed data at the standard height observed at a wind farm, the power-law process was used to simulate the wind speeds at a hub height of 60 m. The Weibull and Rayleigh distributions were chosen to express the wind speeds at two different heights. The parameters in the model were estimated via the least square (LS) method and the maximum likelihood estimation (MLE) method, respectively. An adjusted MLE approach was also presented for parameter estimation. The main indices of wind energy characteristics were calculated based on observational wind speed data. A case study based on the data of Hexi area, Gansu Province of China was given. The results show that MLE method generally outperforms LS method for parameter estimation, and Weibull distribution is more appropriate to describe the wind speed at the hub height.

ewec 2007 - Europe's premier wind energy event

Energy Technology Data Exchange (ETDEWEB)

Chaviaropoulos, T. (ed.)

2007-07-01

This online collection of papers - the ewec 2007 proceedings - reflects the various sessions and lectures presented at the ewec wind-energy convention held in Milan in 2007. The first day's sessions looked at the following topics: Renewable Energy Roadmap, the changing structure of the wind industry, politics and programmes, aerodynamics and innovation in turbine design, wind resources and site characterisation (2 sessions), energy scenarios, harmonisation of incentive schemes, structural design and materials, forecasting, integration studies, integrating wind into electricity markets, wind-turbine electrical systems and components, as well as loads, noise and wakes. The second day included sessions on offshore: developments and prospects, extreme wind conditions and forecasting techniques, small wind turbines, distributed generation and autonomous systems cost effectiveness, cost effectiveness of wind energy, financing wind energy concepts, wind and turbulence, wind power plants and grid integration, offshore technology, global challenges and opportunities, aero-elasticity, loads and control, operations and maintenance, carbon trading and the emission trading schemes, investment strategies of power producers, wind power plants and grid integration, wind turbine electrical systems and components, and wakes. The third day offered sessions on environmental issues, condition monitoring, operation and maintenance, structural design and materials, the Up-Wind workshop, winning hearts and minds, offshore technology, advances in measuring methods and advancing drive-train reliability. In a closing session the conference was summarised, awards for poster contributions were made and the Poul la Cour Prize was presented.

Development of Pneumatic Aerodynamic Devices to Improve the Performance, Economics, and Safety of Heavy Vehicles

International Nuclear Information System (INIS)

Robert J. Englar

2000-01-01

Under contract to the DOE Office of Heavy Vehicle Technologies, the Georgia Tech Research Institute (GTRI) is developing and evaluating pneumatic (blown) aerodynamic devices to improve the performance, economics, stability and safety of operation of Heavy Vehicles. The objective of this program is to apply the pneumatic aerodynamic aircraft technology previously developed and flight-tested by GTRI personnel to the design of an efficient blown tractor-trailer configuration. Recent experimental results obtained by GTRI using blowing have shown drag reductions of 35% on a streamlined automobile wind-tunnel model. Also measured were lift or down-load increases of 100-150% and the ability to control aerodynamic moments about all 3 axes without any moving control surfaces. Similar drag reductions yielded by blowing on bluff afterbody trailers in current US trucking fleet operations are anticipated to reduce yearly fuel consumption by more than 1.2 billion gallons, while even further reduction is possible using pneumatic lift to reduce tire rolling resistance. Conversely, increased drag and down force generated instantaneously by blowing can greatly increase braking characteristics and control in wet/icy weather due to effective ''weight'' increases on the tires. Safety is also enhanced by controlling side loads and moments caused on these Heavy Vehicles by winds, gusts and other vehicles passing. This may also help to eliminate the jack-knifing problem if caused by extreme wind side loads on the trailer. Lastly, reduction of the turbulent wake behind the trailer can reduce splash and spray patterns and rough air being experienced by following vehicles. To be presented by GTRI in this paper will be results developed during the early portion of this effort, including a preliminary systems study, CFD prediction of the blown flowfields, and design of the baseline conventional tractor-trailer model and the pneumatic wind-tunnel model

Intensity of geodynamic processes in the Lithuanian part of the Curonian Spit

Directory of Open Access Journals (Sweden)

A. Česnulevičius

2017-06-01

Full Text Available The paper considers conditions and intensity of aeolian and dune slope transformation processes occurring in the wind-blown sand strips of the dunes of the Curonian Spit. An assessment of the intensity of aeolian processes was made based on the analysis of climatic factors and in situ observations. Transformations in aeolian relief forms were investigated based on the comparison of geodetic measurements and measurements of aerial photographs. Changes in micro-terraces of dune slopes were investigated through comparison of the results of repeated levelling and measurements of aerial photographs. The periods of weak, medium, and strong winds were distinguished, and sand moisture fluctuations affecting the beginning of aeolian processes were investigated. The wind-blown sand movements were found to start when sand moisture decreased by 2 % in the surface sand layer and by up to 5 % at a depth of 10 cm. In 2004–2016, the wind-blown sand movements affected the size of reference deflation relief forms: scarp length by 8 %, scarp width by 35 %, pothole length by 80 %, pothole width by 80 %, roll length by 17 %, roll width by 18 %, hollow length by 17 %, and hollow width by 39 %. The elementary relief forms in the leeward eastern slopes of the dunes experienced the strongest transformations. During a period of 5 months, the height of micro-terraces of the eastern slope of the Parnidis Dune changed from 0.05 to 0.64 cm. The change was related to fluctuations in precipitation intensity: in July–August 2016 the amount of precipitation increased 1.6-fold compared with the multiannual average, thus causing the change in the position of terrace ledges by 21 %.

Development of Pneumatic Aerodynamic Devices to Improve the Performance, Economics, and Safety of Heavy Vehicles

Energy Technology Data Exchange (ETDEWEB)

Robert J. Englar

2000-06-19

Under contract to the DOE Office of Heavy Vehicle Technologies, the Georgia Tech Research Institute (GTRI) is developing and evaluating pneumatic (blown) aerodynamic devices to improve the performance, economics, stability and safety of operation of Heavy Vehicles. The objective of this program is to apply the pneumatic aerodynamic aircraft technology previously developed and flight-tested by GTRI personnel to the design of an efficient blown tractor-trailer configuration. Recent experimental results obtained by GTRI using blowing have shown drag reductions of 35% on a streamlined automobile wind-tunnel model. Also measured were lift or down-load increases of 100-150% and the ability to control aerodynamic moments about all 3 axes without any moving control surfaces. Similar drag reductions yielded by blowing on bluff afterbody trailers in current US trucking fleet operations are anticipated to reduce yearly fuel consumption by more than 1.2 billion gallons, while even further reduction is possible using pneumatic lift to reduce tire rolling resistance. Conversely, increased drag and down force generated instantaneously by blowing can greatly increase braking characteristics and control in wet/icy weather due to effective ''weight'' increases on the tires. Safety is also enhanced by controlling side loads and moments caused on these Heavy Vehicles by winds, gusts and other vehicles passing. This may also help to eliminate the jack-knifing problem if caused by extreme wind side loads on the trailer. Lastly, reduction of the turbulent wake behind the trailer can reduce splash and spray patterns and rough air being experienced by following vehicles. To be presented by GTRI in this paper will be results developed during the early portion of this effort, including a preliminary systems study, CFD prediction of the blown flowfields, and design of the baseline conventional tractor-trailer model and the pneumatic wind-tunnel model.

Challenges and opportunities for wind power for future energy supplies in Pakistan

International Nuclear Information System (INIS)

Farooq, M.; Javed, M.T.; Waheed, K.; Khan, N.A.

2009-01-01

Due to rapid modernization the energy resources are depleting rapidly throughout the world while the energy demand is rising steadily. The crude oil price has soared upto $140.0 per barrel that has triggered the use of renewable energy recourses. Pakistan particular is the most energy deficient country where a shortfall of as high as 4500 MW is recorded in the recent year. The Renewable Energy Technologies (RET's) are important and had gained the prime importance these days with specific focus on solar and wind power. This paper highlights the challenges and opportunities for wind power in Pakistan. The wind potential in different areas has been explored, including a vital area of about 9700 km/sup 2/ in Sindh. Wind power is a new energy resource in Pakistan's history, uptil now main resources are Fossil Fuel contributing 65%, hydel 33% and nuclear only 2% respectively. Wind is an environment friendly resource and its appreciable contribution will be achieved in future. Paper analyses the present energy scenario through wind power in Pakistan and leads to future progress in order to secure energy security in the country. (author)

Impacto na qualidade de vida de um programa educacional para prevenção de distúrbios osteomusculares relacionados ao trabalho (LERDORT)

OpenAIRE

Antonio Cardoso dos Santos

2009-01-01

Introdução: Os Distúrbios Osteomusculares Relacionados ao Trabalho (LERDORT) são um grande problema em saúde pública e frequentemente são causas de incapacidade temporária ou permanente. LERDORT constitui uma síndrome que se manifesta por patologias diversas: sinovites, tenossinovites, neurites, síndrome miofascial, epicondilites, tendinites, bursites, que acometem principalmente os membros superiores, coluna, mas também os membros inferiores. São de etiologia multifatorial: ergonômicas, orga...

Failure analysis of collector circuits associated with wind farms

Directory of Open Access Journals (Sweden)

Clifton Ashley P.

2017-01-01

Full Text Available Wind farm collector circuits generally comprise several wind turbine generators (WTG’s. WTG’s are connected in parallel to a substation. This connection acts as the point-of-connection to the national electricity grid. The electrical load in these circuits is close to component (power cables and accessories ratings. The objective of this paper is to identify cable joint failure paths; and, develop an understanding of specific contributing factors. All findings presented were established from literature review involving data analysis and discussion with industry experts working across the wind industry. Application of forces, inadequate workmanship, incorrect thermal resistance or other contributing factors, all contribute to high conductor operating temperatures. High conductor operating temperatures highlight issues including insufficient environmental heat transfer due to the use of inadequate cable trenching materials. This in turn results in the imbalanced application of force, experienced at the cable joint, as a direct result of frequent thermal expansion and contraction. For most cable joint failures, the root cause is insulation breakdown due to sustained deterioration of the cross-linked polyethylene insulation. This is a direct result from excessive operating temperatures.

Advanced Offshore Wind Energy - Atlantic Consortium

Energy Technology Data Exchange (ETDEWEB)

Kempton, Willett

2015-11-04

This project developed relationships among the lead institution, U of Delaware, wind industry participants from 11 companies, and two other universities in the region. The participating regional universities were University of Maryland and Old Dominion University. Research was carried out in six major areas: Analysis and documentation of extreme oceanic wind events & their impact on design parameters, calibration of corrosivity estimates measured on a coastal turbine, measurment and modeling of tower structures, measurement and modeling of the tribology of major drive components, and gearbox conditioning monitoring using acoustic sensors. The project also had several educational goals, including establishing a course in wind energy and training graduate students. Going beyond these goals, three new courses were developed, a graduate certificate program in wind power was developed and approved, and an exchange program in wind energy was established with Danish Technical University. Related to the installation of a Gamesa G90 turbine on campus and a Gamesa-UD research program established in part due to this award, several additional research projects have been carried out based on mutual industry-university interests, and funded by turbine revenues. This award and the Gamesa partnership have jointly led to seven graduate students receiving full safety and climb training, to become “research climbers” as part of their wind power training, and contributing to on-turbine research. As a result of the educational program, already six graduate students have taken jobs in the US wind industry.

Simulating European wind power generation applying statistical downscaling to reanalysis data

International Nuclear Information System (INIS)

González-Aparicio, I.; Monforti, F.; Volker, P.; Zucker, A.; Careri, F.; Huld, T.; Badger, J.

2017-01-01

Highlights: •Wind speed spatial resolution highly influences calculated wind power peaks and ramps. •Reduction of wind power generation uncertainties using statistical downscaling. •Publicly available dataset of wind power generation hourly time series at NUTS2. -- Abstract: The growing share of electricity production from solar and mainly wind resources constantly increases the stochastic nature of the power system. Modelling the high share of renewable energy sources – and in particular wind power – crucially depends on the adequate representation of the intermittency and characteristics of the wind resource which is related to the accuracy of the approach in converting wind speed data into power values. One of the main factors contributing to the uncertainty in these conversion methods is the selection of the spatial resolution. Although numerical weather prediction models can simulate wind speeds at higher spatial resolution (up to 1 × 1 km) than a reanalysis (generally, ranging from about 25 km to 70 km), they require high computational resources and massive storage systems: therefore, the most common alternative is to use the reanalysis data. However, local wind features could not be captured by the use of a reanalysis technique and could be translated into misinterpretations of the wind power peaks, ramping capacities, the behaviour of power prices, as well as bidding strategies for the electricity market. This study contributes to the understanding what is captured by different wind speeds spatial resolution datasets, the importance of using high resolution data for the conversion into power and the implications in power system analyses. It is proposed a methodology to increase the spatial resolution from a reanalysis. This study presents an open access renewable generation time series dataset for the EU-28 and neighbouring countries at hourly intervals and at different geographical aggregation levels (country, bidding zone and administrative

Societal acceptance of wind farms: Analysis of four common themes across Australian case studies

International Nuclear Information System (INIS)

Hall, N.; Ashworth, P.; Devine-Wright, P.

2013-01-01

Australia's renewable energy target (RET) seeks to provide 20 per cent of Australia's electricity generation from renewable energy sources by 2020. As wind power is relatively advanced, it was anticipated that wind power will contribute a major component of the early target. However, high levels of societal resistance to wind farms, combined with new regulatory policies, indicate the RET may not be dominated by wind power. This research involved an examination of seven case studies around wind farm deployment. Qualitative interviews were the primary data for the case studies and analysed using methods informed by grounded theory. Despite the diversity of stakeholder views, the qualitative analysis identified strong community support for wind farms but four common themes emerged that influence this societal acceptance of wind farms in Australia: trust, distributional justice, procedural justice and place attachment. Without addressing these factors through integration into policy development and engagement approaches, wind energy is unlikely to provide the early and majority of new renewable energy. Similar international experiences are incorporated in the discussion of the Australian wind industry's societal acceptance. - Highlights: ► Seven case studies of wind farms in Australia are described. ► Acceptance affects whether wind significantly contributes to the Aust. RE target. ► Four themes were identified regarding societal acceptance of Australian wind farms. ► Four themes are trust, distributional and procedural justice, and place attachment. ► International similarities to the Australian experience are provided

Statistics-Based Compression of Global Wind Fields

KAUST Repository

Jeong, Jaehong

2017-02-07

Wind has the potential to make a significant contribution to future energy resources. Locating the sources of this renewable energy on a global scale is however extremely challenging, given the difficulty to store very large data sets generated by modern computer models. We propose a statistical model that aims at reproducing the data-generating mechanism of an ensemble of runs via a Stochastic Generator (SG) of global annual wind data. We introduce an evolutionary spectrum approach with spatially varying parameters based on large-scale geographical descriptors such as altitude to better account for different regimes across the Earth\\'s orography. We consider a multi-step conditional likelihood approach to estimate the parameters that explicitly accounts for nonstationary features while also balancing memory storage and distributed computation. We apply the proposed model to more than 18 million points of yearly global wind speed. The proposed SG requires orders of magnitude less storage for generating surrogate ensemble members from wind than does creating additional wind fields from the climate model, even if an effective lossy data compression algorithm is applied to the simulation output.

On wind power in the Nordic countries

International Nuclear Information System (INIS)

Nilsson, Lars J.

1993-01-01

The purpose of this article is to discuss the prospects for a large scale introduction of wind power in the Nordic countries especially with respect to the consequences for small independent power producers of the ongoing and planned deregulation of the electricity sector. The recoverable wind resources are great and integration costs are small due to the good load following capability of the existing Swedish and Norwegian hydroelectric capacity. The structure of the present electricity system and the current principles for electricity trade are reviewed. To what extent wind power will be the technology of choice for capacity replacement and expansion depends on how intermittent power will be valued on the future electricity market. In a deregulated market, wind power may be priced below its value unless appropriate pricing mechanisms are developed. Market reforms should therefore include consideration of the large contribution that wind energy must make in a future electricity system which, in addition to being economically efficient, is compatible with broader societal goals. 47 refs, 2 figs

Statistics-Based Compression of Global Wind Fields

KAUST Repository

Jeong, Jaehong; Castruccio, Stefano; Crippa, Paola; Genton, Marc G.

2017-01-01

Wind has the potential to make a significant contribution to future energy resources. Locating the sources of this renewable energy on a global scale is however extremely challenging, given the difficulty to store very large data sets generated by modern computer models. We propose a statistical model that aims at reproducing the data-generating mechanism of an ensemble of runs via a Stochastic Generator (SG) of global annual wind data. We introduce an evolutionary spectrum approach with spatially varying parameters based on large-scale geographical descriptors such as altitude to better account for different regimes across the Earth's orography. We consider a multi-step conditional likelihood approach to estimate the parameters that explicitly accounts for nonstationary features while also balancing memory storage and distributed computation. We apply the proposed model to more than 18 million points of yearly global wind speed. The proposed SG requires orders of magnitude less storage for generating surrogate ensemble members from wind than does creating additional wind fields from the climate model, even if an effective lossy data compression algorithm is applied to the simulation output.

Serviço de apoio a distância ao professor em sala de aula pela tv digital interativa

Directory of Open Access Journals (Sweden)

José Manuel Martin Rios

2004-01-01

Full Text Available Este é um artigo de um projeto em andamento desenvolvido em parceria com a Diretoria Técnica de Serviços do CPqD Telecom & IT Solutions e a Faculdade de Educação da UNICAMP, que objetiva estabelecer um serviço de apoio a distância aos professores em sala de aula em 03 Escolas da região de Barão Geraldo em Campinas/ SP , para utilizar a TV Digital Interativa como ferramenta de busca e desenvolvimento de conteúdo multimídia interativo nas práticas pedagógicas. Fundamentalmente esta ferramenta será de fácil uso por utilizar como terminal de escolha e exibição um televisor colocado nas salas de aula das escolas e controlado por controle remoto. O professor poderá interagir com o conteúdo exibido no televisor de modo a obter uma programação não linear que se desenvolverá conforme o seu projeto pedagógico. As principais características do serviço são a facilidade de uso, fornecimento a distância de material multimídia interativo, baixo custo de implantação e grande área geográfica de cobertura, proporcionada pela disponibilidade quase total de sinal de televisão no território nacional. Este serviço é parte de um conjunto de serviços de teleducação que estão sendo desenvolvidos para o futuro Sistema de TV Digital terrestre que será implantado no Brasil.

Diurnal evolution of wind structure and data availability measured by the DOE prototype radar system

Science.gov (United States)

Hirth, Brian D.; Schroeder, John L.; Guynes, Jerry G.

2017-11-01

A new Doppler radar prototype has been developed and deployed at Texas Tech University with a focus on enhancing the technologies’ capability to contribute to wind plant relevant complex flow measurements. In particular, improvements in data availability, total data coverage, and autonomous operation were targeted to enable contributions to a wider range of wind energy applications. Doppler radar offers rapid scan speeds, extended maximum range and excellent along-beam range resolution allowing for the simultaneous measurement of various wind phenomena ranging from regional and wind plant scales to inflow and wake flow assessment for an individual turbine. Data examples and performance improvements relative to a previous edition of the technology are presented, including insights into the influence of diurnal atmospheric stability evolution of wind structure and system performance.

Siemens Wind Power 3.6 MW wind turbines for large offshore wind farms

Energy Technology Data Exchange (ETDEWEB)

Akhmatov, Vladislav; Nygaard Nielsen, Joergen; Thisted, Jan; Groendahl, Erik; Egedal, Per; Noertoft Frydensbjerg, Michael; Jensen, Kim Hoej [Siemens Wind Power A/S, Brande (Denmark)

2008-07-01

Siemens Wind power A/S is the key player on the offshore wind power market. The Siemens Wind Power 3.6 MW variable-speed wind turbine is among the word's largest, most advanced and competitive wind turbines with a solid portfolio of large offshore wind farms. Transmission system operators and developers require dynamic wind turbine models for evaluation of fault-ride-through capability and investigations of power system stability. The even larger size of the on- and offshore wind farms has entailed that the grid impact of the voltage and frequency control capability of the wind farm can be appropriated modelled and evaluated. Siemens Wind Power has developed a dynamic model of the 3.6 MW variable-speed wind turbine with the fault-ride-through sequences and models of the voltage and frequency controllers to be applied for large offshore wind farms. The dynamic models have been implemented in the commercially available simulation tools such as DIgSILENT PowerFactory and Siemens PTI PSS/E and successfully validated from measurements. (orig.)

Power Electronics and Controls for Wind Turbine Systems

DEFF Research Database (Denmark)

Blaabjerg, Frede; Iov, Florin; Chen, Zhe

2010-01-01

term) based energy sources to renewable energy sources. Another is to use power electronics to achieve high efficiency in power generation, transmission/distribution and utilization. This paper discuss trends of the most promising renewable energy sources, wind energy, which ,integrated with power...... electronics, is changing the future electrical infrastructure and also contributes steadily to non-carbon based electricity production. The paper’s focus is on the power electronics technologies used in wind turbine systems....

Wind power project at Pasni

International Nuclear Information System (INIS)

Masud, Jamil

1998-01-01

Major power generation capacity additions have recently been achieved in Pakistan as a result of policy initiatives taken in response to widespread power shortages in the eighties. These additions are based mainly on residual fuel oil and natural gas as fuel, resulting in a marked shift in favor of thermal generation and away from the traditionally dominant hydel sources. In recent decades, the supply of electricity to less developed areas has also been accorded high priority in Pakistan, although economic considerations in grid expansion have largely limited an otherwise aggressive rural electrification program to areas easily accessible from the national grid. These factors, coupled with relatively high system losses, have contributed to an unprecedented increase in emissions of greenhouse gases from the power generation industry in the country. An option which merits serious consideration in Pakistan is wind power. Wind power provides an opportunity to reduce dependence on imported fossil fuels and, at the same time, expand the power supply capacity to remote locations where grid expansion is not practical. Preliminary analysis of wind data in selected coastal locations in the Balochistan province indicates that a potential exists for harvesting wind energy using currently available technologies. (author)

Transmission cost minimization strategies for wind-electric generating facilities

Energy Technology Data Exchange (ETDEWEB)

Gonzalez, R. [Northern States Power Company, Minneapolis, MN (United States)

1997-12-31

Integrating wind-electric generation facilities into existing power systems presents opportunities not encountered in conventional energy projects. Minimizing outlet cost requires probabilistic value-based analyses appropriately reflecting the wind facility`s operational characteristics. The wind resource`s intermittent nature permits relaxation of deterministic criteria addressing outlet configuration and capacity required relative to facility rating. Equivalent capacity ratings of wind generation facilities being a fraction of installed nameplate rating, outlet design studies contingency analyses can concentrate on this fractional value. Further, given its non-dispatchable, low capacity factor nature, a lower level of redundancy in outlet facilities is appropriate considering the trifling contribution to output unreliability. Further cost reduction opportunities arise from {open_quotes}wind speed/generator power output{close_quotes} and {open_quotes}wind speed/overhead conductor rating{close_quotes} functions` correlation. Proper analysis permits the correlation`s exploitation to safely increase line ratings. Lastly, poor correlation between output and utility load may permit use of smaller conductors, whose higher (mostly off-peak) losses are economically justifiable.

A gestão da inovação na educação a distância

OpenAIRE

Araújo,Elenise Maria de; Oliveira Neto,José Dutra de; Cazarini,Edson Walmir; Oliveira,Selma Regina Martins

2013-01-01

A reflexão sobre o processo de inovação no setor educacional envolve uma série de componentes que, da perspectiva da Engenharia de Produção, são sistematizados e possibilitam um considerável lucro e valor para as instituições. A sedimentação deste processo no planejamento estratégico e no modelo de negócio da instituição depende da postura dos gestores e da equipe de profissionais, que devem promover a quebra de paradigmas e a constituição de um novo modelo de negócio para a Educação a Distân...

Wind conditions for wind turbine design

Energy Technology Data Exchange (ETDEWEB)

Maribo Pedersen, B.

1999-04-01

Delegates from Europe and USA attended the meeting and discussed general aspects of wind conditions for wind turbine design. The subjects and the presented papers covered a very broad range of aspects of wind conditions and related influence on the wind turbine. (EHS)

Remote sensing for wind energy

Energy Technology Data Exchange (ETDEWEB)

Pena, A.; Bay Hasager, C.; Lange, J. [Technical Univ. of Denmark. DTU Wind Energy, DTU Risoe Campus, Roskilde (Denmark) (and others

2013-06-15

The Remote Sensing in Wind Energy report provides a description of several topics and it is our hope that students and others interested will learn from it. The idea behind it began in year 2008 at DTU Wind Energy (formerly Risoe) during the first PhD Summer School: Remote Sensing in Wind Energy. Thus it is closely linked to the PhD Summer Schools where state-of-the-art is presented during the lecture sessions. The advantage of the report is to supplement with in-depth, article style information. Thus we strive to provide link from the lectures, field demonstrations, and hands-on exercises to theory. The report will allow alumni to trace back details after the course and benefit from the collection of information. This is the third edition of the report (first externally available), after very successful and demanded first two, and we warmly acknowledge all the contributing authors for their work in the writing of the chapters, and we also acknowledge all our colleagues in the Meteorology and Test and Measurements Sections from DTU Wind Energy in the PhD Summer Schools. We hope to continue adding more topics in future editions and to update and improve as necessary, to provide a truly state-of-the-art 'guideline' available for people involved in Remote Sensing in Wind Energy. (Author)

As contribuições de Charcot e de Marsden para o desenvolvimento dos distúrbios do movimento nos séculos XIX e XX

Directory of Open Access Journals (Sweden)

Teive Hélio A.G.

2001-01-01

Full Text Available Charcot contribuiu significativamente no século XIX na descrição de várias enfermidades neurológicas, em particular na área dos distúrbios do movimento. Charcot contribuiu de forma exponencial na descrição clínica minuciosa da doença de Parkinson, além de introduzir o primeiro tratamento farmacológico. Na área das hipercinesias realizou estudos sobre a síndrome de Tourette, o diagnóstico diferencial dos tremores, das coréias e o estudo inicial sobre startle. Marsden, recentemente falecido, destacou-se no século XX com inúmeras publicações na área dos movimentos anormais.São contribuições seminais os estudos sobre a doença de Parkinson, distonias, mioclonias , tremor essencial, a descrição das síndromes " Painful Legs Moving Toes ", "Gait Ignition Failure" e o "Tremor Primário da Escrita". As contribuições de Charcot no século XIX e de Marsden no século XX na área dos distúrbios do movimento permitem concluir que ambos foram as figuras mais representativas desta área nos últimos dois séculos.

A percepção dos docentes frente a Educação a Distância no Stricto Sensu

OpenAIRE

Iris Linhares Pimenta; César Augusto Barreto Silva

2011-01-01

A Educação à distância (EAD) apresenta-se atualmente como um elemento de auxílio à democratização do ensino em todo o mundo. No Brasil, a interiorização da oferta do ensino superior carece de soluções inovadoras e neste cenário a EAD contribui cada vez mais com a ampliação e disponibilidade de elementos que possibilitam o alcance do conhecimento Este trabalho utilizou uma pesquisa exploratória, o universo de pesquisa foram catorze professores, onde a amostra por conveniência de cinco entrevis...

A Rádio Educativa Unoesc FM como recurso didático na Educação a Distância

OpenAIRE

Roseli Rocha Moterle; Ardinete Rover; Larissa C. Colusso; Evandro Ricardo Guindani; Alex Baseggio

2010-01-01

A Educação a Distância é uma modalidade de ensino que utiliza diversos meios e tecnologias de informação e comunicação no processo de mediação, de modo que favoreçam a construção do conhecimento e da autonomia de aprendizagem do aluno. Neste artigo apresentam-se os resultados de um projeto de pesquisa, cujo objetivo foi investigar as contribuições da Rádio Educativa no processo de ensino-aprendizagem das disciplinas de Metodologia Científica e de Ética e Sociedade, oferecidas pela Universidad...

Large-scale integration of wind power into power systems as well as on transmission networks for offshore wind power plants. Proceedings

Energy Technology Data Exchange (ETDEWEB)

Betancourt, Uta; Ackermann, Thomas (eds.)

2013-11-01

This proceedings contains contributions to the followings main topics: Grid integration experiences; Flexibility and economics of integration; Voltage control issues; Offshore wind power plants; Forecasting; Grid code issues; HVDC connection issues; Frequency control issues; National grid's perspective; Power system balancing; Power system issues; New grid and generators issues; Flexibility with storage and demand side management; AC connected offshore wind power plants; Economic and market issues; Modelling issues; Offshore grid issues.

Wind energy development: Danish experiences and international options

International Nuclear Information System (INIS)

Frandsen, S.; Hasted, F.; Josephsen, L.; Nielson, J.H.

1989-01-01

In Denmark, wind energy makes a visible contribution to energy planning. Since 1976, over 1,800 wind turbine units have been installed in Denmark, representing a capacity of ca 140 MW out of a grid capacity of 8,000 MW. These units are all grid-connected and the unit sizes range from 55 kW to 400 kW. The installed wind energy capacity represents a substantial development of technologies for wind energy utilization during the last 15 years, involving participation from research institutes, electric utilities, private industry, and the national energy administration. A considerable improvement of the technical and economic performance of wind turbines, along with increased reliability and durability, has been strongly supported by comprehensive government programs. In 1985, another large construction program was initiated which will add 100 MW wind power capacity by the end of 1990. Parallel with commercial development, Danish utilities have developed and constructed a number of megawatt-size wind turbines on a pilot basis. In general terms the wind energy resources in Denmark are rather good, and many suitable sites exist, but installed wind energy capacity is limited by the high population density. Consequently, research is being conducted on the feasibility of offshore wind turbines. In other countries, wind energy developments similar to those in Denmark are taking place. In communities with no connection to the national grid, special attention should be paid to hybrid systems such as wind-diesel and hydro-wind systems. A substantial transfer of technology is required for facilitating significant development of hybrid systems in developing countries. 11 refs., 7 figs., 2 tabs

Distância percebida até as instalações de lazer e sua associação com a prática de atividade física e de exercícios em adolescentes de Curitiba, Paraná, Brasil

Directory of Open Access Journals (Sweden)

Alex Vieira Lima

2013-08-01

Full Text Available O objetivo deste estudo foi verificar a associação entre a distância percebida até instalações de lazer (parques, praças, academias, ginásios e ciclovias com a prática de atividade física e de exercícios em adolescentes de Curitiba, Paraná, Brasil. Estudo transversal realizado com amostra representativa de 1.474 adolescentes (14-18 anos, alunos da rede pública de ensino. Foi verificada associação inversa entre a distância > 31 minutos até academias e ginásios com a prática de atividade física nos meninos (RP = 0,78; IC95%: 0,69-0,88 e RP = 0,79; IC95%: 0,66-0,95, respectivamente. O número de instalações próximas da residência associou-se positivamente com a prática de atividade física nos meninos (RP = 1,18; IC95%: 1,04-1,34. Para as meninas, a distância > 31 minutos até um ginásio apresentou associação inversa com a prática de exercícios de força (RP = 0,93; IC95%: 0,87-0,99. Esses achados sugerem que a distância e a quantidade de instalações de lazer no bairro podem afetar o padrão de atividade física de adolescentes, sendo essa relação diferente entre os sexos.

Indian offshore wind energy policy - lessons from Europe

Energy Technology Data Exchange (ETDEWEB)

Mani, S.; Dhingra, T. [Univ. of Petroleum and Energy Studies (UPES), Dehradun (India)

2012-07-01

Indian Economy is growing at 8% for the past few years and is expected to continue this momentum into the foreseeable future. To sustain this growth, power sector needs to build additional generation capacity at an unprecedented pace. However, continued dependence on fossil fuels (especially Coal and Oil) to power the growth of electricity generation capacity, is hardly sustainable in the long run. The reasons are well known - Environmental concerns, depleting fossil fuel resources, excessive dependency on Oil imports - that it hardly merits repetition. Renewable Energy source forms a miniscule portion (25 GW, {approx} 12%) of India's overall Energy consumption today (202 GW). The share of wind energy (17 GW) is 67% of the total renewable energy basket. But the contribution from offshore wind farms is non-existent, as all the wind energy generated in India is only through onshore Wind farms. India needs a policy framework to encourage the development of offshore wind farms. Several European countries, most notably the UK, Germany and Denmark, have effective offshore wind energy policies that have helped them to accelerate the growth of their offshore wind energy sector. This paper does an exhaustive study to identify the building blocks of a successful offshore wind energy policy initiative adopted by selected European countries, which can be leveraged by India to articulate its own offshore wind energy policy. This paper also suggests a model to predict the log-odds of growth of offshore wind energy sector in India. (Author)

Challenges and prospects for wind energy to attain 20% grid penetration by 2020 in India

DEFF Research Database (Denmark)

Madsen, Peter Hauge; Natarajan, Anand

2011-01-01

With wind energy being the most realistic large-scale renewable energy source in the near future, we examine the target for wind energy penetration in India for 2020. Achieving the target set by the Indian Wind Power Association of 20% wind power grid penetration by 2020 will act as a lighthouse......-scale integration of wind power. In the article, we discuss the trends in the development of wind energy and the factors which we consider decisive for the development of wind power in India. Experiences and policies from Europe and Denmark, where wind power already today contributes 20% to the total electricity...

Mediação pedagógica em educação a distância : inovação na docência universiária no processo de elaboração de materiais didático

OpenAIRE

Mallmann, Elena Maria

2010-01-01

A preocupação central é mapear as especificidades da inovação na docência universitária na elaboração de materiais didáticos impressos e hipermidiáticos para mediação pedagógica em Educação a Distância. Os ciclos espiralados de planejamento, ação, observação e reflexão orientaram metodologicamente a investigação que envolveu professores-autores e designers de mediação da equipe multidisciplinar de um curso Licenciatura em Física na Modalidade a Distância. As categorias analíticas ...

Optimal support vessel and access system selection for offshore wind farms

NARCIS (Netherlands)

Asgarpour, M.; Serraris, J.W.; Ridder, E. de; Broek, J. van den; Bos, J.E.

2016-01-01

Operation and maintenance (O&M) costs contribute to a significant part of Cost of Energy produced by offshore wind. In order to reduce the O&M costs and to guarantee safety and wellbeing of the maintenance technicians, for each individual wind farm an optimal set of support vessels and access

Wind resource in metropolitan France: assessment methods, variability and trends

International Nuclear Information System (INIS)

Jourdier, Benedicte

2015-01-01

France has one of the largest wind potentials in Europe, yet far from being fully exploited. The wind resource and energy yield assessment is a key step before building a wind farm, aiming at predicting the future electricity production. Any over-estimation in the assessment process puts in jeopardy the project's profitability. This has been the case in the recent years, when wind farm managers have noticed that they produced less than expected. The under-production problem leads to questioning both the validity of the assessment methods and the inter-annual wind variability. This thesis tackles these two issues. In a first part are investigated the errors linked to the assessment methods, especially in two steps: the vertical extrapolation of wind measurements and the statistical modelling of wind-speed data by a Weibull distribution. The second part investigates the inter-annual to decadal variability of wind speeds, in order to understand how this variability may have contributed to the under-production and so that it is better taken into account in the future. (author) [fr

Wind resource estimation and siting of wind turbines

DEFF Research Database (Denmark)

Lundtang Petersen, Erik; Mortensen, N.G.; Landberg, L.

1994-01-01

Detailed knowledge of the characteristics of the natural wind is necessary for the design, planning and operational aspect of wind energy systems. Here, we shall only be concerned with those meteorological aspects of wind energy planning that are termed wind resource estimation. The estimation...... of the wind resource ranges from the overall estimation of the mean energy content of the wind over a large area - called regional assessment - to the prediction of the average yearly energy production of a specific wind turbine at a specific location - called siting. A regional assessment will most often...... lead to a so-called wind atlas. A precise prediction of the wind speed at a given site is essential because for aerodynamic reasons the power output of a wind turbine is proportional to the third power of the wind speed, hence even small errors in prediction of wind speed may result in large deviations...

Wind power production: from the characterisation of the wind resource to wind turbine technologies

International Nuclear Information System (INIS)

Beslin, Guy; Multon, Bernard

2016-01-01

Illustrated by graphs and tables, this article first describes the various factors and means related to the assessment of wind resource in the World, in Europe, and the factors which characterize a local wind resource. In this last respect, the authors indicate how local topography is taken into account to calculate wind speed, how time variations are taken into account (at the yearly, seasonal or daily level), the different methods used to model a local wind resource, how to assess the power recoverable by a wind turbine with horizontal axis (notion of Betz limit). In the second part, the authors present the different wind turbines, their benefits and drawbacks: vertical axis, horizontal axis (examples of a Danish-type wind turbine, of wind turbines designed for extreme conditions). Then, they address the technology of big wind turbines: evolution of technology and of commercial offer, aerodynamic characteristics of wind turbine and benefit of a varying speed (technological solutions, importance of the electric generator). They describe how to choose a wind turbine, how product lines are organised, how the power curve and energy capacity are determined. The issue of integration of wind energy into the power system is then addressed. The next part addressed the economy of wind energy production (annualized production cost, order of magnitude of wind electric power production cost). Future trends are discussed and offshore wind energy production is briefly addressed

Performance of a prototype micro wind turbine in the manmade wind field from air conditioner of buildings

Directory of Open Access Journals (Sweden)

K. H. Goh

2012-03-01

Full Text Available Harnessing waste energy from the manmade air fields of buildings presents a new area of renewable energy to explore. Due to the unpredictability of the natural wind, this study is to evaluate the practicality for harnessing waste energy from the air conditioner exhaust units which are a more constant and predictable source available in the buildings. A prototype of the micro wind turbine has been designed to minimize the negative effect of the exhaust sources. After the micro wind turbine was manufactured, the performance of the turbine was tested in the selected air conditioner exhaust unit. Increasing the rotor solidity and decreasing the resistance of the generator contribute to improved starting torque and decreased generator break in torque respectively in the design. The power generation of the micro wind turbine increases with an increase of the rotor speed. The 24-hour operation of the prototype presents an observation for both exhaust performance and power generation prediction when the prototype is mounted on the exhaust unit.

Wind tunnel experiments on the effects of tillage ridge features on wind erosion horizontal fluxes

Directory of Open Access Journals (Sweden)

M. Kardous

2005-11-01

Full Text Available In addition to the well-known soil factors which control wind erosion on flat, unridged surfaces, two specific processes affect the susceptibility of tillage ridged surfaces to wind erosion: ridge-induced roughness and ridge- trapping efficiency. In order to parameterize horizontal soil fluxes produced by wind over tillage ridges, eight-ridge configurations composed of sandy soil and exhibiting ridge heights to ridge spacing (RH/RS ratios ranging from 0.18 to 0.38 were experimented in a wind tunnel. These experiments are used to develop a parameterization of the horizontal fluxes over tillage ridged surfaces based only on the geometric characteristics of the ridges. Indeed, the key parameters controlling the horizontal flux, namely the friction velocity, threshold friction velocity and the adjustment coefficient, are derived through specific expressions, from ridge heights (RH and ridge spacing (RS. This parameterization was evaluated by comparing the results of the simulations to an additional experimental data set and to the data set obtained by Hagen and Armbrust (1992. In both cases, predicted and measured values are found to be in a satisfying agreement. This parameterization was used to evaluate the efficiency of ridges in reducing wind erosion. The results show that ridged surfaces, when compared to a loose, unridged soil surface, lead to an important reduction in the horizontal fluxes (exceeding 60%. Moreover, the effect of ridges in trapping particles contributes for more than 90% in the flux reduction while the ridge roughness effect is weak and decreases when the wind velocity increases.

Wind farm project economics : value of wind

Energy Technology Data Exchange (ETDEWEB)

Bills-Everett, T. [Mainstream Renewable Power, Toronto, ON (Canada)

2010-07-01

This PowerPoint presentation discussed methods of increasing the value of wind power projects. Appropriate turbine selection and layout is needed to ensure that wind resources are fully developed. Construction costs have a significant impact on project costs. The world turbine price index has not significantly fluctuated since 2006. Operating costs, and the value of wind power projects, are linked with OPEX fluctuations. Wind power projects can significantly reduce greenhouse gas (GHG) emissions. An increase in wind power capacity will reduce the overall cost of energy produced from wind power. Countries can use wind power as part of a renewable energy portfolio designed to reduce risks related to diminishing petroleum supplies. Wind power will help to ensure a global transition to renewable energy use. tabs., figs.

Wind Power Today: Wind Energy Program Highlights 2001

Energy Technology Data Exchange (ETDEWEB)

2002-05-01

Wind Power Today is an annual publication that provides an overview of the U.S. Department of Energy's Wind Energy Program accomplishments for the previous year. The purpose of Wind Power Today is to show how DOE's Wind Energy Program supports wind turbine research and deployment in hopes of furthering the advancement of wind technologies that produce clean, low-cost, reliable energy. Content objectives include: educate readers about the advantages and potential for widespread deployment of wind energy; explain the program's objectives and goals; describe the program's accomplishments in research and application; examine the barriers to widespread deployment; describe the benefits of continued research and development; facilitate technology transfer; and attract cooperative wind energy projects with industry. This 2001 edition of Wind Power Today also includes discussions about wind industry growth in 2001, how DOE is taking advantage of low wind speed regions through advancing technology, and distributed applications for small wind turbines.

Investigation of the Airflow around a Sail.

Science.gov (United States)

Gray, Rachel P.

1986-01-01

Shows how air flows around a sail, explaining why a dinghy is able to move toward the wind rather than be blown backwards. Also illustrates the effects of alternating the angle of a sail, using different sail shapes and using a rig consisting of two sails. (JN)

Development of Advanced High Lift Leading Edge Technology for Laminar Flow Wings

Science.gov (United States)

Bright, Michelle M.; Korntheuer, Andrea; Komadina, Steve; Lin, John C.

2013-01-01

This paper describes the Advanced High Lift Leading Edge (AHLLE) task performed by Northrop Grumman Systems Corporation, Aerospace Systems (NGAS) for the NASA Subsonic Fixed Wing project in an effort to develop enabling high-lift technology for laminar flow wings. Based on a known laminar cruise airfoil that incorporated an NGAS-developed integrated slot design, this effort involved using Computational Fluid Dynamics (CFD) analysis and quality function deployment (QFD) analysis on several leading edge concepts, and subsequently down-selected to two blown leading-edge concepts for testing. A 7-foot-span AHLLE airfoil model was designed and fabricated at NGAS and then tested at the NGAS 7 x 10 Low Speed Wind Tunnel in Hawthorne, CA. The model configurations tested included: baseline, deflected trailing edge, blown deflected trailing edge, blown leading edge, morphed leading edge, and blown/morphed leading edge. A successful demonstration of high lift leading edge technology was achieved, and the target goals for improved lift were exceeded by 30% with a maximum section lift coefficient (Cl) of 5.2. Maximum incremental section lift coefficients ( Cl) of 3.5 and 3.1 were achieved for a blown drooped (morphed) leading edge concept and a non-drooped leading edge blowing concept, respectively. The most effective AHLLE design yielded an estimated 94% lift improvement over the conventional high lift Krueger flap configurations while providing laminar flow capability on the cruise configuration.

Yearbook of wind energy law 2014; Jahrbuch Windenergierecht 2014

Energy Technology Data Exchange (ETDEWEB)

Brandt, Edmund (ed.) [Technische Univ. Braunschweig (Germany). Lehrstuhl Staats- und Verwaltungsrecht sowie Verwaltungswissenschaften; Koordinierungsstelle Windenergierecht k:wer, Braunschweig (Germany)

2015-07-01

In the yearbook 2014, the technical contributions surround mainly the position and shape of the wind energy, small wind turbines, the compatibility of the EEG with higher-ranking law, as well as to the implementation of recent instrumental requirements. In other contributions the central lines of development of the jurisdiction are identified and (legal) political developments, judical decisions and literature are documented. [German] Im Jahrbuch 2014 ranken sich die Fachbeitraege schwerpunktmaessig um die Stellung und Ausformung der Windenergie, um Kleinwindanlagen, um die Vereinbarkeit des EEG mit hoeherrangigem Recht sowie um die Umsetzung neuerer instrumenteller Anforderungen. In weiteren Beitraegen werden die zentralen Entwicklungslinien der Rechtsprechung herausgearbeitet und (rechts-)politische Entwicklungen, Gerichtsentscheidungen und Literatur dokumentiert.

Proceedings of the Canadian Wind Energy Association's 2009 wind matters conference : wind and power systems

International Nuclear Information System (INIS)

2009-01-01

This conference provided a forum for wind energy and electric power industry experts to discuss issues related to wind and power systems. An overview of wind integration studies and activities in Canada and the United States was provided. New tools and technologies for facilitating the integration of wind and improve market conditions for wind energy developers were presented. Methods of increasing wind penetration were evaluated, and technical issues related to wind interconnections throughout North America were reviewed. The conference was divided into the following 5 sessions: (1) experiences with wind integration, and lessons learned, (2) update on ongoing wind integration initiatives in Canada and the United States, (3) initiatives and tools to facilitate wind integration and market access, (4) developments in wind interconnection and grid codes, (5) wind energy and cold weather considerations, and (6) challenges to achieving the 20 per cent WindVision goal in Canada. The conference featured 21 presentations, of which 13 have been catalogued separately for inclusion in this database. refs., tabs., figs

Wind Speed Influences on Marine Aerosol Optical Depth

Directory of Open Access Journals (Sweden)

Colin O'Dowd

2010-01-01

Full Text Available The Mulcahy (Mulcahy et al., 2008 power-law parameterization, derived at the coastal Atlantic station Mace Head, between clean marine aerosol optical depth (AOD and wind speed is compared to open ocean MODIS-derived AOD versus wind speed. The reported AOD versus wind speed (U was a function of ∼U2. The open ocean MODIS-derived AOD at 550 nm and 860 nm wavelengths, while in good agreement with the general magnitude of the Mulcahy parameterization, follows a power-law with the exponent ranging from 0.72 to 2.47 for a wind speed range of 2–18 m s−1. For the four cases examined, some MODIS cases underestimated AOD while other cases overestimated AOD relative to the Mulcahy scheme. Overall, the results from MODIS support the general power-law relationship of Mulcahy, although some linear cases were also encountered in the MODIS dataset. Deviations also arise between MODIS and Mulcahy at higher wind speeds (>15 m s−1, where MODIS-derived AOD returns lower values as compared to Mulcahy. The results also support the suggestion than wind generated sea spray, under moderately high winds, can rival anthropogenic pollution plumes advecting out into marine environments with wind driven AOD contributing to AOD values approaching 0.3.

Frequency Activated Fast Power Reserve for Wind Power Plant Delivered from Stored Kinetic Energy in the Wind Turbine Inertia

DEFF Research Database (Denmark)

Knüppel, Thyge; Thuring, P.; Kumar, S

2011-01-01

is proposed that delivers a short-term power reserve from the kinetic energy in the wind turbine (WT) inertia, while considering the inherent characteristics of a wind power plant. The aim is to contribute with a fast power reserve to stabilize the frequency drop during large and sudden production deficits......With increased penetration of converter interfaced generation, synchronous generators may start to be displaced to keep the overall power balance. As a consequence the resulting inertia in the system may decrease and make the power system more exposed to frequency excursions. Here, a control...

Governo colonial, distância e espera nas minas e capitania de Goiás

Directory of Open Access Journals (Sweden)

Fernando Lobo Lemes

Full Text Available A temporalidade da espera associada aos intervalos impostos pelas distâncias geográficas à burocracia do governo colonial instala a vida dos habitantes de Goiás num ambiente transitório, constituído de eventos provisórios, onde os protagonistas devem fazer face às incertezas, enquanto esperam pelas decisões do rei de Portugal. Com a morte súbita do capitão-general João Manoel de Melo, a formação de um governo provisório aparece como estratégia das elites locais para controlar o tempo de espera e preencher o vazio de poder deixado pela ausência do governador. Neste cenário, os acontecimentos são percebidos como interações de força, cujas tensões podem transformar, ainda que transitoriamente, as relações estabelecidas na hierarquia dos poderes do império.

Emissions and temperature benefits: The role of wind power in China

Energy Technology Data Exchange (ETDEWEB)

Duan, Hongbo, E-mail: hbduan@ucas.ac.cn

2017-01-15

Background: As a non-fossil technology, wind power has an enormous advantage over coal because of its role in climate change mitigation. Therefore, it is important to investigate how substituting wind power for coal-fired electricity will affect emission reductions, changes in radiative forcing and rising temperatures, particularly in the context of emission limits. Methods: We developed an integrated methodology that includes two parts: an energy-economy-environmental (3E) integrated model and an emission-temperature response model. The former is used to simulate the dynamic relationships between economic output, wind energy and greenhouse gas (GHG) emissions; the latter is used to evaluate changes in radiative forcing and warming. Results: Under the present development projection, wind energy cannot serve as a major force in curbing emissions, even under the strictest space-restraining scenario. China's temperature contribution to global warming will be up to 21.76% if warming is limited to 2 degrees. With the wind-for-coal power substitution, the corresponding contribution to global radiative forcing increase and temperature rise will decrease by up to 10% and 6.57%, respectively. Conclusions: Substituting wind power for coal-fired electricity has positive effects on emission reductions and warming control. However, wind energy alone is insufficient for climate change mitigation. It forms an important component of the renewable energy portfolio used to combat global warming. - Highlights: • We assess the warming benefits associated with substitution of wind power for coal. • The effect of emission space limits on climate responses is deeply examined. • China is responsible for at most 21.76% of global warming given the 2-degree target. • Wind power alone may not be sufficient to face the challenge of climate change. • A fertile policy soil and an aggressive plan are necessary to boost renewables.

Emissions and temperature benefits: The role of wind power in China

International Nuclear Information System (INIS)

Duan, Hongbo

2017-01-01

Background: As a non-fossil technology, wind power has an enormous advantage over coal because of its role in climate change mitigation. Therefore, it is important to investigate how substituting wind power for coal-fired electricity will affect emission reductions, changes in radiative forcing and rising temperatures, particularly in the context of emission limits. Methods: We developed an integrated methodology that includes two parts: an energy-economy-environmental (3E) integrated model and an emission-temperature response model. The former is used to simulate the dynamic relationships between economic output, wind energy and greenhouse gas (GHG) emissions; the latter is used to evaluate changes in radiative forcing and warming. Results: Under the present development projection, wind energy cannot serve as a major force in curbing emissions, even under the strictest space-restraining scenario. China's temperature contribution to global warming will be up to 21.76% if warming is limited to 2 degrees. With the wind-for-coal power substitution, the corresponding contribution to global radiative forcing increase and temperature rise will decrease by up to 10% and 6.57%, respectively. Conclusions: Substituting wind power for coal-fired electricity has positive effects on emission reductions and warming control. However, wind energy alone is insufficient for climate change mitigation. It forms an important component of the renewable energy portfolio used to combat global warming. - Highlights: • We assess the warming benefits associated with substitution of wind power for coal. • The effect of emission space limits on climate responses is deeply examined. • China is responsible for at most 21.76% of global warming given the 2-degree target. • Wind power alone may not be sufficient to face the challenge of climate change. • A fertile policy soil and an aggressive plan are necessary to boost renewables.

Assessing the impact of marine wind farms on birds through movement modelling

OpenAIRE

Masden, Elizabeth A.; Reeve, Richard; Desholm, Mark; Fox, Anthony D.; Furness, Robert W.; Haydon, Daniel T.

2012-01-01

Advances in technology and engineering, along with European Union renewable energy targets, have stimulated a rapid growth of the wind power sector. Wind farms contribute to carbon emission reductions, but there is a need to ensure that these structures do not adversely impact the populations that interact with them, particularly birds. We developed movement models based on observed avoidance responses of common eider Somateria mollissima to wind farms to predict, and identify potential measu...

Wind power today: 1999 Wind Energy program highlights

Energy Technology Data Exchange (ETDEWEB)

Weis-Taylor, Pat

2000-04-06

Wind Power Today is an annual publication that provides an overview for the Department of Energy's Wind Energy Program. The purpose of Wind Power Today is to show how DOE's Wind Energy Program supports wind turbine research and deployment in hopes of furthering the advancement of wind technologies that produce clean, low-cost, reliable energy for the 21st century. Content objectives include: Educate readers about the advantages and potential for widespread deployment of wind energy; explain DOE wind energy program objectives and goals; describe program accomplishments in research and application; examine the barriers to widespread deployment; describe benefits of continued research and development; facilitate technology transfer; attract cooperative wind energy projects with industry.

Cumulative effects of wind turbines. Volume 2: Report on qualitative public attitude research in mid-Wales

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

This report summarises the results of research to develop a planning tool for assessing the cumulative effect of wind turbines carried out in Montgomeryshire through contact with those involved in wind farms, and those living near and further away from the wind turbine arrays. Topics examined included people's feeling about wind farms, noise, experience with wind farm developers, availability of related jobs, awareness of income to farmers from wind farms, developers' contributions to local funds, awareness of government policy, appreciation of wind as a resource, and the effects on tourism.

Cumulative effects of wind turbines. Volume 2: Report on qualitative public attitude research in mid-Wales

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

This report summarises the results of research to develop a planning tool for assessing the cumulative effect of wind turbines carried out in Montgomeryshire through contact with those involved in wind farms, and those living near and further away from the wind turbine arrays. Topics examined included people's feeling about wind farms, noise, experience with wind farm developers, availability of related jobs, awareness of income to farmers from wind farms, developers' contributions to local funds, awareness of government policy, appreciation of wind as a resource, and the effects on tourism.

Wind energy. To produce electricity with the wind

International Nuclear Information System (INIS)

Bareau, Helene

2015-11-01

This guide addresses the different aspects of wind-based power generation. It outlines the role of wind energy to meet objectives related to the share of renewable energies in the French energy mix, that wind energy is actually replacing fossil energies, that it is based on local resources within higher safety and less wastage, that current advances are made to integrate wind energy production into the grid, and that it is a solution to diversify energy production. Some figures are presented and commented, regarding onshore wind energy production in France, the location of wind farms, and wind energy production in comparison with other renewable sources. The operation of a wind turbine is described and the different types of wind turbines are evoked. The issue of wind farm planning with citizen participation is addressed: regional planning, studies of pre-feasibility for location selection, procedure, and content of the impact study (radars, fauna and flora, landscapes, safety, health). Other features are outlined: a planned dismantling, and a globally favourable perception. The next part addresses offshore wind energy: the interesting potential of stronger and more reliable wind at sea (European situation, French opportunities, elements comprised in an offshore wind farm), impacts (on marine ecosystems, on neighbouring localities, and interests for visitors). Economic aspects are then addressed: cost and profitability, economic spin-offs, and perspectives. The last part concerns individuals and the possibilities to participate to wind farm projects or to invest in small wind turbines with some prerequisites (constant and steady winds, installation assessment, required expertise, indispensable preliminary steps, costs, aids and profitability)

Understanding the environmental implications of energy transitions. A case study for wind power

Energy Technology Data Exchange (ETDEWEB)

Arvesen, Anders

2013-03-01

A fundamental change in the ways in which we provide energy to run our economies, an energy transition, is needed to mitigate climate change. Wind power is an important part of future global energy supply in most energy scenarios. This thesis aims to contribute to a better understanding of the environmental implications of energy transitions, primarily by examining the case of wind power. This involves new investigations of both potential negative impacts of wind power and the positive role of the technology in emission reduction, as well as a critical review of past research. Three papers on wind power are presented: a comprehensive literature review of life cycle assessments (LCA) of wind power, a scenario-based LCA of large-scale adoption of wind power, and an LCA of an offshore wind farm. A hybrid LCA methodology is employed in the scenario-based LCA and LCA of an offshore wind farm. Another paper is presented which is not concerned with wind power in particular, but takes the form of an evaluation of limitations of climate change mitigation literature. It helps to achieve the aim stated above by bringing together knowledge of indirect effects of mitigation measures, and by elucidating how these effects may influence the viability of proposed mitigation strategies. The literature review aims to take stock of insights from past research, with a particular view to identifying remaining challenges. A survey of results indicates 0.063 ({+-}0.061) and 0.055 ({+-}0.037) kWh energy used and 20 ({+-}14) and 16 ({+-}10) Co2 emitted per kWh electricity for onshore and offshore cases. Evidence suggests strong positive effects of scale in the lower end of the turbine size spectrum, but is inconclusive for the megawatt range. LCAs tend to assume higher capacity factors than current real-world averages. Limitations of existing research are discussed; this includes poorly understood toxicity and resource depletion impacts, cut-off errors and seemingly inconsistent modelling

Educação a distância: configurações, políticas e contradições engendradas no trabalho docente

Directory of Open Access Journals (Sweden)

Elcio Gustavo Benini

2015-06-01

Comunicação (TICs constituem a base objetiva dos discursos e das práticas sobre a democratização do acesso ao ensino superior. De fato, observamos que, na primeira década do século XXI, houve um crescimento vultoso de matrículas no ensino superior brasileiro na modalidade a distância. Tal crescimento, contudo, tem engendrado contradições, como a intensificação, a alienação, a precarização e a divisão do trabalho docente.

Dependency in State Transitions of Wind Turbines

DEFF Research Database (Denmark)

Herp, Jürgen; Ramezani, Mohammad Hossein; S. Nadimi, Esmaeil

2017-01-01

© 2017 IEEE. Turbine states and predicting the transition into failure states ahead of time is important in operation and maintenance of wind turbines. This study presents a method to monitor state transitions of a wind turbine based on the online inference on residuals. In a Bayesian framework...... be abstracted from generated data. Two models are presented: 1) assuming independence and 2) assuming dependence between states. In order to select the right models, machine learning is utilized to update hyperparameters on the conditional probabilities. Comparing fixed to learned hyperparameters points out...... the impact machine learning concepts have on the predictive performance of the presented models. In conclusion, a study on model residuals is performed to highlight the contribution to wind turbine monitoring. The presented algorithm can consistently detect the state transition under various configurations...

Wind power in Arctic regions

International Nuclear Information System (INIS)

Lundsager, P.; Ahm, P.; Madsen, B.; Krogsgaard, P.

1993-07-01

Arctic or semi-arctic regions are often endowed with wind resources adequate for a viable production of electricity from the wind. Only limited efforts have so far been spent to introduce and to demonstrate the obvious synergy of combining wind power technology with the problems and needs of electricity generation in Arctic regions. Several factors have created a gap preventing the wind power technology carrying its full role in this context, including a certain lack of familiarity with the technology on the part of the end-users, the local utilities and communities, and a lack of commonly agreed techniques to adapt the same technology for Arctic applications on the part of the manufacturers. This report is part of a project that intends to contribute to bridging this gap. The preliminary results of a survey conducted by the project are included in this report, which is a working document for an international seminar held on June 3-4, 1993, at Risoe National Laboratory, Denmark. Following the seminar a final report will be published. It is intended that the final report will serve as a basis for a sustained, international effort to develop the wind power potential of the Arctic and semi-arctic regions. The project is carried out by a project group formed by Risoe, PA Energy and BTM Consult. The project is sponsored by the Danish Energy Agency of the Danish Ministry of Energy through grant no. ENS-51171/93-0008. (au)

2008 wind farm submission requirements

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-05-01

Wind turbines used to generate electricity can have important visual, environmental and amenity impacts depending on their location. Planning can contribute to the provision of renewable energy by enabling wind energy development in appropriate locations in a manner that appropriately balances their environmental, social and economic benefits with any demonstrated visual, environmental and amenity impacts. The County of Bruce, Ontario and member municipalities are attempting to balance these matters in favour of an overall net community benefit. Planning applications need to include sufficient information and explanation to allow the approval authorities to come to a sound and timely decision, in order to facilitate a viable wind energy industry. This document outlined the County of Bruce application requirements in order to assist in the design and siting of proposed wind energy facilities and in preparing planning applications. The County of Bruce official plan and policies for large wind energy conversion systems (LWECS) were presented. Submissions requirements include an environmental screening report; a federal environmental assessment clearance; a prime agricultural land justification report; a general project description; turbine specifications; noise evaluation; shadow flicker calculations; visual effect modelling; NAV Canada/Transport Canada clearance; grid connections and routing; project staging; overshadowing study; electromagnetic interference study; turbine foundation drawings; and an environmental management plan. Other requirements include lot level maps; project area maps; sensitive receptor table; shadow flicker; stage 2 archaeological study; type certification; statement of planning policy conformity; and a submission checklist. 6 refs., 1 tab., 3 appendices.

Review of grid code frequency requirements for wind farms

Energy Technology Data Exchange (ETDEWEB)

El Itani, S.; Joos, G. [McGill Univ., Montreal, PQ (Canada)

2010-07-01

This paper presented frequency grid code requirements for the connection of wind farms to power systems at the high voltage level. The necessity of ensuring that connected wind farms will contribute to the secure operation of the power system in a manner similar to conventional generators has led to the development of several grid code requirements (GCRs) for the integration of wind farms to the grid. These provisions are in place to ensure that wind projects do not negatively impact system stability and reliability. A comparative overview of the main requirements was conducted, looking at national and regional codes from areas with high wind penetration levels. These requirements provide wind farms with the control and regulation capabilities encountered in conventional power plants, which is necessary for the safe, reliable, and economic operation of the system. These requirements have heavily influenced the development of wind turbine generator (WTGs) technology over the last decade. It was concluded that modern WTGs are capable of meeting all the requirements thus far set for active power and ramp rates, extended frequency range, and frequency response required for functional incorporation into modern power grids. 17 refs., 6 tabs., 11 figs.

Estimating generation costs for wind power production in France

International Nuclear Information System (INIS)

Benazet, J.F.; Probert, E.J.

1997-01-01

Wind power is being exploited in several European countries as one of a possible number of sources of renewable energy. However, in France there is a heavy reliance on nuclear and hydro-electric power and the potential of wind power as part of the energy mix has been virtually ignored. One of the reasons advanced for the under utilisation of this technology is that it is financially unattractive. In this paper the contribution which wind power could potentially make to overall power production levels in France is examined. A cost estimate model is developed which derives electricity generation costs and determines realistic levels of production for the future. The model automatically determines the associated number of wind turbines required and the geographical areas in which they should be located. (author)

Short circuit signatures from different wind turbine generator types

DEFF Research Database (Denmark)

Martinez, Jorge; Kjær, Philip C.; Rodriguez, Pedro

2011-01-01

Modern wind power plants are required and designed to ride through faults in the network, subjected to the fault clearance and following grid code demands. Beside voltage support during faults, the wind turbine fault current contribution is important to establish the correct settings for the relay...... of the protections. The following wind turbine generator during faults have been studied: (i) induction generator, (ii) induction generator with variable rotor resistance (iii) converter-fed rotor (often referred to as DFIG) and (iv) full scale converter. To make a clear comparison and performance analysis during...... faults, and the consequent effects on substation protections, the aforementioned configurations have been simulated using PSCAD/EMTDC, with the same power plant configuration, electrical grid and generator data. Additionally, a comparison of these wind turbine technologies with a conventional power plant...

Wind power integration : From individual wind turbine to wind park as a power plant

NARCIS (Netherlands)

Zhou, Y.

2009-01-01

As power capacities of single wind turbine, single wind park and total wind power installation are continuously increasing, the wind power begins to challenge the safety operation of the power system. This thesis focuses on the grid integration aspects such as the dynamic behaviours of wind power

Posturografia em idosos com distúrbios vestibulares e quedas

Directory of Open Access Journals (Sweden)

Camila Macedo

2013-05-01

Full Text Available Introdução: A posturografia estática e dinâmica tem sido usada para analisar a habilidade de idosos com disfunção vestibular em manter o equilíbrio corporal em diferentes condições de conflitos sensoriais. O objetivo do exame é quantificar a velocidade de oscilação e o deslocamento do centro de pressão nas condições de conflitos visual, somatossensorial e interação visuo-vestibular, e o limite de estabilidade. Objetivo: Analisar a literatura referente ao controle do equilíbrio corporal em idosos com distúrbios vestibulares por meio de posturografia computadorizada estática e dinâmica. Métodos: Revisão nas bases de dados LILACS, EMBASE, MEDLINE, Scielo, Cochrane, ISI Web of Knowledge e bibliotecas virtuais de teses e dissertações, utilizando as palavras-chave “Idoso”, “Equilíbrio Postural”, “Avaliação”, “Controle Postural”, “Quedas”, “Posturografia”, “Vestibular” e/ou “Tontura” de publicações dos últimos vinte anos. Resultados: Há vários modelos de posturografias que mensuram as respostas posturais e o risco de quedas em indivíduos idosos, perante os diferentes estímulos sensoriais, incluindo a tecnologia de realidade virtual. Os idosos com desequilíbrio corporal, tontura, e/ou com histórico de quedas apresentam pior desempenho que idosos sem queixas, sem histórico de quedas e indivíduos mais jovens. Conclusão: A posturografia é uma valiosa ferramenta para análise quantitativa do controle postural, permitindo a identificação das condições sensoriais nas quais os idosos vestibulopatas apresentam maior instabilidade.

An evaluation of the WindEye wind lidar

DEFF Research Database (Denmark)

Dellwik, Ebba; Sjöholm, Mikael; Mann, Jakob

Prevision of the wind field by remote sensing wind lidars has the potential to improve the performance of wind turbines. The functionality of a WindEye lidar developed by Windar Photonics A/S (Denmark) for the wind energy market was tested in a two months long field experiment. The WindEye sensor...... with a high accuracy during the whole campaign....

Wind turbine blade waste in 2050.

Science.gov (United States)

Liu, Pu; Barlow, Claire Y

2017-04-01

Wind energy has developed rapidly over the last two decades to become one of the most promising and economically viable sources of renewable energy. Although wind energy is claimed to provide clean renewable energy without any emissions during operation, but it is only one side of the coin. The blades, one of the most important components in the wind turbines, made with composite, are currently regarded as unrecyclable. With the first wave of early commercial wind turbine installations now approaching their end of life, the problem of blade disposal is just beginning to emerge as a significant factor for the future. This paper is aimed at discovering the magnitude of the wind turbine blade waste problem, looking not only at disposal but at all stages of a blade's lifecycle. The first stage of the research, the subject of this paper, is to accurately estimate present and future wind turbine blade waste inventory using the most recent and most accurate data available. The result will provide a solid reference point to help the industry and policy makers to understand the size of potential environmental problem and to help to manage it better. This study starts by estimating the annual blade material usage with wind energy installed capacity and average blade weight. The effect of other waste contributing factors in the full lifecycle of wind turbine blades is then included, using industrial data from the manufacturing, testing and in-service stages. The research indicates that there will be 43 million tonnes of blade waste worldwide by 2050 with China possessing 40% of the waste, Europe 25%, the United States 16% and the rest of the world 19%. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

How ambitious can we be in contributing to the world's energy needs with bioenergy, wind, solar and storage?

Energy Technology Data Exchange (ETDEWEB)

Bindslev, H. (eds.)

2009-08-15

There is broad consensus among climate scientists that to keep the risk of dangerous climate changes to a reasonable level energy production in the world must be virtually free of green house gas emissions well before the end of this century. How far can we go, what stands in the way and what should the leading actors do? That is what the workshop addressed. The aim of the workshop, which was part of the DTU Climate Change Technologies programme (www.dtu.dk/climate), was to define a number of ambitious but realistic targets and describe roadmaps to reach these targets. The roadmaps will be given as input to the UN Climate Change Conference, COP 15, and as inspiration for action to meet climate challenges. The roadmaps describe contributions and commitments needed from industry, research and policy. The workshop addressed the challenges for increasing the contribution from wind power, bioenergy and solar energy. The aim was to identify initiatives that can accelerate development and deployment of these technologies. This includes energy storage and implementation and interaction of storage technologies with the overall energy system. (LN)

Wind Structure and Wind Loading

DEFF Research Database (Denmark)

Brorsen, Michael

The purpose of this note is to provide a short description of wind, i.e. of the flow in the atmosphere of the Earth and the loading caused by wind on structures. The description comprises: causes to the generation of windhe interaction between wind and the surface of the Earthhe stochastic nature...

An Appropriate Wind Model for Wind Integrated Power Systems Reliability Evaluation Considering Wind Speed Correlations

Directory of Open Access Journals (Sweden)

Rajesh Karki

2013-02-01

Full Text Available Adverse environmental impacts of carbon emissions are causing increasing concerns to the general public throughout the world. Electric energy generation from conventional energy sources is considered to be a major contributor to these harmful emissions. High emphasis is therefore being given to green alternatives of energy, such as wind and solar. Wind energy is being perceived as a promising alternative. This source of energy technology and its applications have undergone significant research and development over the past decade. As a result, many modern power systems include a significant portion of power generation from wind energy sources. The impact of wind generation on the overall system performance increases substantially as wind penetration in power systems continues to increase to relatively high levels. It becomes increasingly important to accurately model the wind behavior, the interaction with other wind sources and conventional sources, and incorporate the characteristics of the energy demand in order to carry out a realistic evaluation of system reliability. Power systems with high wind penetrations are often connected to multiple wind farms at different geographic locations. Wind speed correlations between the different wind farms largely affect the total wind power generation characteristics of such systems, and therefore should be an important parameter in the wind modeling process. This paper evaluates the effect of the correlation between multiple wind farms on the adequacy indices of wind-integrated systems. The paper also proposes a simple and appropriate probabilistic analytical model that incorporates wind correlations, and can be used for adequacy evaluation of multiple wind-integrated systems.