Academic literature on the topic 'MLT winds'
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Journal articles on the topic "MLT winds"
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Mbatha, N., V. Sivakumar, S. B. Malinga, H. Bencherif, and S. R. Pillay. "Study on the impact of sudden stratosphere warming in the upper mesosphere-lower thermosphere regions using satellite and HF radar measurements." Atmospheric Chemistry and Physics Discussions 9, no. 6 (November 2, 2009): 23051–72. http://dx.doi.org/10.5194/acpd-9-23051-2009.
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Abstract. The occurrence of sudden stratospheric warming (SSW) excites disturbances in the mesosphere-lower thermospheric (MLT) wind and temperature. Here, we have examined the high frequency (HF) radar wind data from the South African National Antarctic Expedition, SANAE (72° S, 3° W), a radar which is part of the Super Dual Auroral Radar Network (SuperDARN). Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (TIMED) satellite temperature data and National Centre for Environmental Prediction (NCEP) temperature and wind data were use to investigate the dynamical effects of the unprecedented September 2002 SSW in the Antarctica stratosphere and MLT. The mean zonal wind (from SANAE HF radar) at the MLT shows reversal in approximately 7 days before the reversal at 10 hPa (from NCEP). This indicates that there was a downwards propagation of circulation disturbance. Westerly zonal winds dominate the winter MLT, but during the 2002 winter there were many periods of westward winds observed compared to other years. The dynamic spectrums of both meridional and zonal winds show presence of planetary waves (of ~14-day period) before the occurrence of the SSW. The SABER vertical temperature profiles indicated the cooling of the MLT region before the SSW event.
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Mbatha, N., V. Sivakumar, S. B. Malinga, H. Bencherif, and S. R. Pillay. "Study on the impact of sudden stratosphere warming in the upper mesosphere-lower thermosphere regions using satellite and HF radar measurements." Atmospheric Chemistry and Physics 10, no. 7 (April 12, 2010): 3397–404. http://dx.doi.org/10.5194/acp-10-3397-2010.
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Abstract. The occurrence of a sudden stratospheric warming (SSW) excites disturbances in the mesosphere-lower thermospheric (MLT) wind and temperature. Here, we have examined the high frequency (HF) radar wind data from the South African National Antarctic Expedition, SANAE (72° S, 3° W), a radar which is part of the Super Dual Auroral Radar Network (SuperDARN). Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (TIMED) satellite temperature data and National Centre for Environmental Prediction (NCEP) temperature and wind data are used to investigate the dynamical effects of the unprecedented September 2002 SSW in the Antarctica stratosphere and MLT. The mean zonal wind (from SANAE HF radar) at the MLT shows reversal approximately 7 days before the reversal at 10 hPa (from NCEP). This indicates that there was a downwards propagation of circulation disturbance. Westerly zonal winds dominate the winter MLT, but during the 2002 winter there are many periods of westward winds observed compared to other years. The normalised power spectrums of both meridional and zonal winds show presence of planetary waves (of ~14-day period) before the occurrence of the SSW. The SABER vertical temperature profiles indicated the cooling of the MLT region before the SSW event.
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Portnyagin, Y. I., T. V. Solovjova, N. A. Makarov, E. G. Merzlyakov, A. H. Manson, C. E. Meek, W. Hocking, et al. "Monthly mean climatology of the prevailing winds and tides in the Arctic mesosphere/lower thermosphere." Annales Geophysicae 22, no. 10 (November 3, 2004): 3395–410. http://dx.doi.org/10.5194/angeo-22-3395-2004.
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Abstract. The Arctic MLT wind regime parameters measured at the ground-based network of MF and meteor radar stations (Andenes 69° N, Tromsø 70° N, Esrange 68° N, Dixon 73.5° N, Poker Flat 65° N and Resolute Bay 75° N) are discussed and compared with those observed in the mid-latitudes. The network of the ground-based MF and meteor radars for measuring winds in the Arctic upper mesosphere and lower thermosphere provides an excellent opportunity for study of the main global dynamical structures in this height region and their dependence from longitude. Preliminary estimates of the differences between the measured winds and tides from the different radar types, situated 125-273km apart (Tromsø, Andenes and Esrange), are provided. Despite some differences arising from using different types of radars it is possible to study the dynamical wind structures. It is revealed that most of the observed dynamical structures are persistent from year to year, thus permitting the analysis of the Arctic MLT dynamics in a climatological sense. The seasonal behaviour of the zonally averaged wind parameters is, to some extent, similar to that observed at the moderate latitudes. However, the strength of the winds (except the prevailing meridional wind and the diurnal tide amplitudes) in the Arctic MLT region is, in general, less than that detected at the moderate latitudes, decreasing toward the pole. There are also some features in the vertical structure and seasonal variations of the Arctic MLT winds which are different from the expectations of the well-known empirical wind models CIRA-86 and HWM-93. The tidal phases show a very definite longitudinal dependence that permits the determination of the corresponding zonal wave numbers. It is shown that the migrating tides play an important role in the dynamics of the Arctic MLT region. However, there are clear indications with the presence in some months of non-migrating tidal modes of significant appreciable amplitude.
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Griffith, Matthew J., Shaun M. Dempsey, David R. Jackson, Tracy Moffat-Griffin, and Nicholas J. Mitchell. "Winds and tides of the Extended Unified Model in the mesosphere and lower thermosphere validated with meteor radar observations." Annales Geophysicae 39, no. 3 (June 10, 2021): 487–514. http://dx.doi.org/10.5194/angeo-39-487-2021.
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Abstract. The mesosphere and lower thermosphere (MLT) is a critical region that must be accurately reproduced in general circulation models (GCMs) that aim to include the coupling between the lower and middle atmosphere and the thermosphere. An accurate representation of the MLT is thus important for improved climate modelling and the development of a whole atmosphere model. This is because the atmospheric waves at these heights are particularly large, and so the energy and momentum they carry is an important driver of climatological phenomena through the whole atmosphere, affecting terrestrial and space weather. The Extended Unified Model (ExUM) is the recently developed version of the Met Office's Unified Model which has been extended to model the MLT. The capability of the ExUM to model atmospheric winds and tides in the MLT is currently unknown. Here, we present the first study of winds and tides from the ExUM. We make a comparison against meteor radar observations of winds and tides from 2006 between 80 and 100 km over two radar stations – Rothera (68∘ S, 68∘ W) and Ascension Island (8∘ S, 14∘ W). These locations are chosen to study tides in two very different tidal regimes – the equatorial regime, where the diurnal (24 h) tide dominates, and the polar regime, where the semi-diurnal (12 h) tide dominates. The results of this study illustrate that the ExUM is capable of reproducing atmospheric winds and tides that capture many of the key characteristics seen in meteor radar observations, such as zonal and meridional wind maxima and minima, the increase in tidal amplitude with increasing height, and the decrease in tidal phase with increasing height. In particular, in the equatorial regime some essential characteristics of the background winds, tidal amplitudes and tidal phases are well captured but with significant differences in detail. In the polar regime, the difference is more pronounced. The ExUM zonal background winds in austral winter are primarily westward rather than eastward, and in austral summer they are larger than observed above 90 km. The ExUM tidal amplitudes here are in general consistent with observed values, but they are also larger than observed values above 90 km in austral summer. The tidal phases are generally well replicated in this regime. We propose that the bias in background winds in the polar regime is a consequence of the lack of in situ gravity wave generation to generate eastward fluxes in the MLT. The results of this study indicate that the ExUM has a good natural capability for modelling atmospheric winds and tides in the MLT but that there is room for improvement in the model physics in this region. This highlights the need for modifications to the physical parameterization schemes used in the model in this region – such as the non-orographic spectral gravity wave scheme – to improve aspects such as polar circulation. To this end, we make specific recommendations of changes that can be implemented to improve the accuracy of the ExUM in the MLT.
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Rokade, M. V., R. Kondala Rao, S. S. Nikte, R. N. Ghodpage, P. T. Patil, A. K. Sharma, and S. Gurubaran. "Intraseasonal oscillation (ISO) in the MLT zonal wind over Kolhapur (16.8° N) and Tirunelveli (8.7° N)." Annales Geophysicae 30, no. 12 (December 5, 2012): 1623–31. http://dx.doi.org/10.5194/angeo-30-1623-2012.
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Abstract. Simultaneous observations of the mean zonal winds at 88 km obtained by the medium-frequency (MF) radars at Kolhapur (16.8° N, 74.2° E) and Tirunelveli (8.7° N, 77.8° E) have been used to study the intraseasonal oscillation (ISO) in the MLT region. The influences of the intraseasonal variations in the lower tropospheric convective activity associated with the Madden-Julian oscillations on the latitudinal behavior of intraseasonal oscillations (ISO) of the zonal winds in the equatorial mesosphere and lower thermosphere (MLT) have been studied. The ISO activity in the lower tropospheric convective activity is examined by employing outgoing long wave radiation (OLR) as a proxy for deep convective activity occurring in the tropical lower atmosphere. The ISO activity in the zonal wind over TIR is more correlated with that in the convective activity compared to the ISO over KOL. The latitudinal and temporal variabilities of the ISO in MLT zonal winds are explained in terms of the intraseasonal variabilities in the convective activity.
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Hasebe, F., T. Tsuda, T. Nakamura, and M. D. Burrage. "Validation of HRDI MLT winds with meteor radars." Annales Geophysicae 15, no. 9 (September 30, 1997): 1142–57. http://dx.doi.org/10.1007/s00585-997-1142-7.
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Abstract. A validation study of the mesospheric and lower-thermospheric (MLT) wind velocities measured by the High-Resolution Doppler Imager (HRDI) on board the Upper-Atmosphere Research Satellite (UARS) has been carried out, comparing with observations by meteor radars located at Shigaraki, Japan and Jakarta, Indonesia. The accuracy of the HRDI winds relative to the meteor radars is obtained by a series of simultaneous wind measurements at the time of UARS overpasses. Statistical tests on the difference in the wind vectors observed by HRDI and the meteor radars are applied to determine whether the wind speed has been overestimated by HRDI (or underestimated by the MF radars) as previously noticed in HRDI vs. MF radar comparisons. The techniques employed are the conventional t-test applied to the mean values of the paired wind vector components as well as wind speeds, and two nonparametric tests suitable for testing the paired wind speed. The square-root transformation has been applied before the t-tests of the wind speed in order to fit the wind-speed distribution function to the normal distribution. The overall results show little evidence of overestimation by HRDI (underestimation by meteor radars) of wind velocities in the MLT region. Some exceptions are noticed, however, at the altitudes around 88 km, where statistical differences occasionally reach a level of significance of 0.01. The validation is extended to estimate the precision of the wind velocities by both HRDI and meteor radars. In the procedure, the structure function defined by the mean square difference of the observed anomalies is applied in the vertical direction for the profile data. This method assumes the isotropy and the homogeneity of variance for the physical quantity and the homogeneity of variance for the observational errors. The estimated precision is about 6ms–1 for the Shigaraki meteor radar, 15ms–1 for the Jakarta meteor radar, and 20ms–1 for HRDI at 90-km altitude. These values can be used to confirm the statistical significance of the wind field obtained by averaging the observed winds.
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Jacobi, Christoph, Tatiana Ermakova, Daniel Mewes, and Alexander I. Pogoreltsev. "El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3 ° N, 13 ° E)." Advances in Radio Science 15 (September 21, 2017): 199–206. http://dx.doi.org/10.5194/ars-15-199-2017.
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Abstract. Mesosphere/lower thermosphere (MLT) zonal winds continuously measured by a VHF meteor radar at Collm, Germany (51.3° N, 13.0° E) in the height range 82 – 97 km from 2004 to date are analyzed with respect to the signature of El Niño. The comparison of Niño3 equatorial SST index and MLT wind time series shows that in January and especially in February zonal winds are positively correlated with the Niño3 index. We note a delay of about one month of the MLT zonal wind effect with respect to equatorial sea surface temperature variability. The signal is strong for the upper altitudes (above 90 km) accessible to the radar observations, but weakens with decreasing height. This reflects the fact that during El Niño years the westerly winter middle atmosphere wind jet is weaker, and this is also the case with the easterly lower thermospheric jet. Owing to the reversal of the absolute El Niño signal from negative to positive with altitude, at the height of the maximum meteor flux, which is around 90 km, the El Niño signal is weak. The experimental results can be qualitatively reproduced by numerical experiments using a mechanistic global circulation model with prescribed tropospheric temperatures and latent heat release for El Niño and La Niña conditions.
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Naniwadekar, G. P., S. Gurubaran, A. P. Jadhav, R. N. Ghodpage, P. T. Patil, and D. S. Burud. "Studies on the variability of mean winds in the mesosphere and lower thermosphere region (MLT) over Kolhapur (16.8oN, 74.2oE)." Journal of Geomatics 17, no. 1 (April 28, 2023): 93–100. http://dx.doi.org/10.58825/jog.2023.17.1.78.
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We present the study of mesospheric winds in the 78–98 km height range using observations by a partial reflection radar station (MF–radar) situated at Kolhapur (16.8° N, 74.2° E), India. The sequential wind profiles over the period of 2014–2019 obtained from this radar operated at 1.98 MHz are used for this study. To delineate the behaviour of the winds in the mesosphere and lower thermosphere (MLT) region, we use wind data providing horizontal wind velocities averaged for an hour. Details of the seasonal, annual, and inter-annual variations and also the climatology of mean motion in zonal (East-West) and meridional (North-South) components in the MLT region over the aforementioned period are presented. The zonal wind below 90 km has been observed with eastward flow for the period of solstices and westward flow at equinoxes, showing strong semi-annual oscillations (SAO). While above 90 km, annual oscillations (AO) are seen to be dominant. Annual oscillations (AO) are observed in the mean meridional wind, with poleward motion during winter and equatorward motion during the remaining seasons. At higher altitudes (above 92 km), the poleward motion weakens and the equatorward wind flow becomes strong.
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Middleton, H. R., N. J. Mitchell, and H. G. Muller. "Mean winds of the mesosphere and lower thermosphere at 52° N in the period 1988–2000." Annales Geophysicae 20, no. 1 (January 31, 2002): 81–91. http://dx.doi.org/10.5194/angeo-20-81-2002.
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Abstract. A meteor radar in the UK (near 52° N) has been used to measure the mean winds of the mesosphere/lower-thermosphere (MLT) region over the period 1988–2000. The seasonal course and interannual variability is characterised and comparisons are made with a number of models. Annual mean wind trends were found to be + 0.37 ms-1 yr-1 for the zonal component and + 0.157 ms-1 yr-1 for the meridional component. Seasonal means revealed significant trends in the case of meridional winds in spring ( + 0.38 ms-1 yr-1) and autumn ( + 0.29 ms-1 yr-1), and zonal winds in summer ( + 0.48 ms-1 yr-1) and autumn ( + 0.38 ms-1 yr-1). Significant correlation coefficients, R, between the sunspot number and seasonal mean wind are found in four instances. In the case of the summer zonal winds, R = + 0.732; for the winter meridional winds, R = - 0.677; for the winter zonal winds, R = - 0.472; and for the autumn zonal winds R = + 0.508.Key words. Meteorology and atmospheric dynamics (climatology; general circulation; middle atmospheric dynamics)
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Stober, Gunter, Alan Liu, Alexander Kozlovsky, Zishun Qiao, Witali Krochin, Guochun Shi, Johan Kero, et al. "Identifying gravity waves launched by the Hunga Tonga–Hunga Ha′apai volcanic eruption in mesosphere/lower-thermosphere winds derived from CONDOR and the Nordic Meteor Radar Cluster." Annales Geophysicae 41, no. 1 (April 18, 2023): 197–208. http://dx.doi.org/10.5194/angeo-41-197-2023.
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Abstract. The Hunga Tonga–Hunga Ha′apai volcano eruption was a unique event that caused many atmospheric phenomena around the globe. In this study, we investigate the atmospheric gravity waves in the mesosphere/lower-thermosphere (MLT) launched by the volcanic explosion in the Pacific, leveraging multistatic meteor radar observations from the Chilean Observation Network De Meteor Radars (CONDOR) and the Nordic Meteor Radar Cluster in Fennoscandia. MLT winds are computed using a recently developed 3DVAR+DIV algorithm. We found eastward- and westward-traveling gravity waves in the CONDOR zonal and meridional wind measurements, which arrived 12 and 48 h after the eruption, and we found one in the Nordic Meteor Radar Cluster that arrived 27.5 h after the volcanic detonation. We obtained observed phase speeds for the eastward great circle path at both locations of about 250 m s−1, and they were 170–150 m s−1 for the opposite propagation direction. The intrinsic phase speed was estimated to be 200–212 m s−1. Furthermore, we identified a potential lamb wave signature in the MLT winds using 5 min resolved 3DVAR+DIV retrievals.
Dissertations / Theses on the topic "MLT winds"
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Hack, Brian E. "Analysis of MIT campus wind resources for future wind turbine installation." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45837.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 23).
As our nation's continuing dependence on fossil energy and the problems that result from that dependence grow more apparent, we must look to alternative sources of energy to power the country. As a global scientific and technological leader, MIT is expected to take a part in the search for and support of alternative energy sources. One such source that has tremendous potential, yet tends to be underrepresented, is wind energy. Following the previous wind resource analysis done by Richard Bates, Samantha Fox, Katherine McCusker, and Kathryn Pesce, I have expanded upon the suggestions made at the conclusion of their analysis. The Eastgate building on MIT's campus was identified as one possible location for small scale wind turbines. I completed a computational fluid dynamics (CFD) analysis on that building as well as the Johnson Athletic Center to determine if there were adequate wind resources to make the installation of a wind turbine on one of these buildings economical. The results of the CFD analysis show that the west edge of the roof on the Johnson Athletic Center is a promising location for the installation of a roof-top wind turbine. Further investigation of the wind resources at that location should be conducted.
by Brian E. Hack.
S.B.
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Vasudevan, Santhosh. "HURRICANE WIND RETRIEVAL ALGORITHM DEVELOPMENT FOR AN AIRBORNE CONICAL SCANNING SCATTEROMETER." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3222.
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Reliable ocean wind vector measurements can be obtained using active microwave remote sensing (scatterometry) techniques. With the increase in the number of severe hurricanes making landfall in the United States, there is increased emphasis on operational monitoring of hurricane winds from aircraft. This thesis presents a data processing algorithm to provide real-time hurricane wind vector retrievals (wind speed and direction) from conically scanning airborne microwave scatterometer measurements of ocean surface backscatter. The algorithm is developed to best suit the specifications for the National Oceanic and Atmospheric Administration (NOAA) Hurricane Research Division's airborne scatterometer – Integrated Wind and Rain Airborne Profiler (IWRAP). Based on previous scatterometer wind retrieval methodologies, the main focus of the work is to achieve rapid data processing to provide real-time measurements to the NOAA Hurricane Center. A detailed description is presented of special techniques used. Because IWRAP flight data were not available at the time of this development, the wind retrieval performance was evaluated using a Monte Carlo simulation, whereby radar backscatter measurements were simulated with instrument and geophysical noise and then used to infer the surface wind conditions in a simulated (numerical weather model) hurricane wind fieldM.S.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Eppanapelli, Lavan Kumar. "Investigation of wind potential variation at three measurement sites based on atmospheric stability and power production." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-136935.
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As tapping energy from wind expands rapidly worldwide, it is a common procedure to locate a practicable site to extract energy from abundant wind flow by building wind farms. Comprehensive understanding of wind resource at a site is important to perform the main activities say, wind flow modeling, wind turbines micro siting, annual energy yield calculation and cost of energy estimation. Wind measuring campaigns involve using of measuring instruments such as meteorological tower instrumented with anemometers, wind vanes and temperature sensors; remote sensing devices such as SoDAR, LiDAR. These meteorological devices provide detailed information on wind behavior with respect to the height, time and temperature. These systems were proven in providing promising wind measurements even though they are susceptible to certain weather conditions. The study progressed by focusing on the wind behavior at three locations to investigate the possible factors that varies the wind character. A location with one met mast and two AQ500 SoDAR systems was considered for this project where one AQ500 is 800m away and other AQ500 is 5515m away from the point of Met mast. The location is contemplated as a decent approach to the spatial analysis of the wind resource as there is a large scope to analyze the wind character between two nearby sites and two faraway sites. Monostatic 3-beam SoDAR systems from AQ System, Sweden and 100m meteorological tower with instruments are used in this project work for collecting the wind data. One-year worth of wind data at standard 10min intervals has been collected from the three systems. This report outlines the theoretical description of project location, AQ500 SoDAR and Met mast. A detailed explanation of the data quality control and filtering methods are discussed along with respective reasons. The conclusion is drawn after performing the statistical analysis between wind speed and other parameters such as turbulent intensity, wind direction, thermal stability and temperature. Mat lab is used for computing and analyzing the wind data from three systems.
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Corrigan, Daniel James. "Local Met-Ocean Conditions over Lake Erie as Measured at the Cleveland Water Intake Crib." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1396609064.
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Gaihre, Nirajan. "ANALYTICAL AND NUMERICAL MODELING OF FOUNDATIONS FOR TALL WIND TURBINE IN VARIOUS SOILS." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2650.
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Wind farm construction is increasing progressively, to cope-up with the current global energy scenario. The advantage of clean energy and sustainability helps wind turbine construction to flourish rapidly. Location of wind turbines is independent of foundation soil condition but depends on the wind speeds and socio-environment issues. Hence, a construction sites may not be favorable in terms of geotechnical demands. The taller wind towers facilitate the generation of high energy production, which will increase loads on the foundation, and eventually increase the dimension of the foundation. Hence, the choice of a suitable foundation system is necessary for geotechnical engineer to design tall wind towers. This study aims to analyze different foundation types e.g., raft/mat foundation, pile group foundation, and piled raft/mat foundation using analytical calculation verified with numerical models using PLAXIS 3D software. The foundation for steel wind turbine towers 100 m high was designed for different types of soils e.g., soft clayey soil, medium-stiff clayey soil, stiff clayey soil, and sandy soil. The design wind speed was taken from the ASCE 7-10 (2010) standard for Occupancy Category III and IV Buildings and Other Structures, as the Illinois region falls in that category. The parametric study was performed by varying the diameter of raft/mat, wind speed, number of piles, and soil types to evaluate the settlement in any type of foundation with load sharing proportion in piled raft/mat foundation. First, the raft/mat foundation design was carried out manually by changing the diameter of 15 m, 20 m, 25 m, 30 m, and 35 m, and changing load by considering different wind speed. Then the foundation was modeled using PLAXIS 3D software with a raft/mat diameter of 25 m, 30 m, and 35 m only, by considering the eccentricity and factor of safety criteria. With the increase in wind speed, the differential settlement on the raft/mat foundation was found to be increased. However, the increase in diameter of raft/mat caused the reduction in differential settlement. Soft clayey soil was found to be more sensitive than other soils used in the present study. For the same diameter of raft/mat, applied the same wind load, the differential settlement of foundation in soft clayey soil was found to be 6-10 times higher than the sandy soil.The position of piles was fixed based on the spacing criteria in the pile group foundation. The number of piles used in this study were 23, 32, and 46. Settlement was found to be varied with the number of piles in all soils used in this study. The lateral deflection for soft clayey soil decreased to half, when number of piles increased from 23 to 46. The differential settlement was found to be increased with the increase in wind speed in pile group foundation. Raft/mat foundation settlement was found to be 4 to 6 times higher than the settlement in pile group foundation in any soils, used in this study, for a given wind speed.The result of piled raft/mat foundation showed that the majority of the total load is shared by the piles (i.e., 60% to 94%) and remaining load is shared by the raft/mat (i.e., 6% to 40%), based on the stiffness of raft/mat and piles as well as pile-soil-pile interaction. The increase in wind speed in the wind turbines increased the differential settlement of piled raft/mat foundation in all soils. Similarly, the lateral deflection also increased with the increase in wind speed in pile raft/mat foundation in all soils. The PLAXIS 3D analysis revealed that the differential settlement in soft clayey soil was 1.5 to 2.0 times higher than the settlement in sandy soil.The validation of numerical modeling was carried out by the raft/mat foundation using Boussinesq’s theory and calculating settlement for single pile and group pile foundation. The current study showed that the soft clayey soil and medium-stiff clayey soil favor deep foundation, like pile group and piled raft/mat rather than shallow foundation, like raft/mat foundation. The results obtained from both analytical calculation and numerical modeling was found to be approximately matching. This study will help local construction company and geotechnical engineer to guide a proper foundation design of tall onshore wind turbine.
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Winde, Friederike [Verfasser], and Thomas [Gutachter] Meyer. "Blasenaugmentation mit Hilfe eines biokompatiblen Materials im Rattenmodell / Friederike Winde ; Gutachter: Thomas Meyer." Würzburg : Universität Würzburg, 2018. http://d-nb.info/1173616705/34.
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Gabrielli, M. "CHEMICAL MARKERS FOR THE EVALUATION OF SENSORY AND ANTIOXIDANT PROPERTIES OF WINES." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/230019.
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Sotolon (3-Hydroxy-4,5-dimethyl-2(5)-furanone) is a chiral lactone responsible for the oxidized flavour in fortified wines and wine produced by oxidative ageing. The perception threshold of the racemic mixture in wine is 8 – 10 μg/L and the flavour is reported as curry, aged honey, aged sake and fenugreek. Though it is considered a typical flavour note in Madera, Porto and Sherry, it is an off-flavour in dry white wine where its oxidative note is detrimental for the fresh taste and odour. The sotolon formation pathways, during winemaking, are affected by chemical and physical factors such as: oxygen concentration, storage temperature and time, reducing sugar concentration and antioxidant compounds concentration (e.g. sulphur dioxide or (GSH) glutathione). Due to the number of chemical and physical factors affecting the Sotolon formation in wine this compound has been suggested as chemical marker of white wine shelf-life.
A fast, sensitive and easy to apply analytical method (UHPLC-UV) and it was applied to the evaluation of SO2-free Franciacorta DOCG wines in order to assess the effect of different disgorgement conditions (antioxidant additives, ageing time and temperature) on the sotolon formation. The sotolon concentration was measured in sparkling wine stored at 15°C and 25°C for 6 months added to three different antioxidant preparations (2 g/hL and 4 g/hL) potentially substituting the sulfur dioxide. Furthermore, we investigated the chemical and physical factors could affect the sotolon formation in synthetic wine. Model solution conitaing increasing concentration of pentoses, GSH, amino group, catechin, oxygen, ethanal, tartaric acid and iron are stored at two temperatures (70°C and 5°C) for five days in order to clarify the compositive factors affecting the sotolon synthesis in white wine. Finally, we compared the performances of analytical methods (HPLC-UV and UHPLC-MS) for sotolon quantification, which were previously developed. Separately, we developed a fast, sensitive and easy to apply analytical method (UHPLC-UV) for the biogenic amines (BAs) assessment in red wine treated with different malolactic fermentation condition (Spontaneous MLF; Inoculum and Co-inoculum techniques). Moreover was checked the trend of intra and extra-cellular glutathione and their effect on the aromatic matrix of South African Sauvignon blanc (Stellenbosch) must and wine during the alcholic fermentation and aging. The Must was treated with GSH and a GSH-enriched inactive dry yeast preparation (GSH-IDYs).
The proposed analytical methods (UHPLC-UV; HPLC-UV and UHPLC-MS) provide a sample preparation faster and easier-to-apply than those previously reported for the routine analyses of sotolon. The methods (HPLC-UV; UHPLC-MS/MS; UHPLC-UV) were proved suitable for the determination of sotolon concentrations in white wine and in model solution under its sensory perception threshold. Two analytical methods compared (HPLC-UV; UHPLC-MS/MS) were successfully used for the screening of 70 commercial South African wines’ sotolon levels. The samples of Franciacorta sparkling wines treated with SO2 show the best protection against wine oxidation whereas the other commercial antioxidants tested caused detrimental effects due to the sotolon production. The phenolic composition of commercial antioxidants has influenced the production of sotolon. The sotolon formation tests carried out showed which sotolon can be formed by several formation pathways indeed it was generated under both reducing and oxidative conditions. Sotolon formation is enhanced by simultaneous presence of Fe++ and O2, of amino groups and of phenols. Glutathione inhibited the formation of sotolon only when it was simultaneously added with amino groups and phenols in an oxidizing environment or when it was present in oxidative conditions. Under anoxic conditions the sotolon formation test has been demonstrated that there is a high dependence between sotolon and reducing sugar contents, whereas tartaric acid and acetaldehyde didn't affect the formation of sotolon. The formation of
sotolon in anoxic environment has not yet been clarified and further tests will be conduct to understand the role of tartaric acid, ethanol, ethanal and ribose on sotolon production in synthetic wine. The analytical method for the BAs quantification showed good linearity and repeatability and was able to quantify the ABs in red wine. The preliminary results concerning the different malolactic fermentation conditions, suggest that co-inoculum technique does not seem to prevent BAs formation in wine. The trial data on GSH (intra and extra-cellular) have yet to be processed and will be assessed in the future.
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Malekian, Boroujeni Kaveh. "Modellierung des Oberschwingungsverhaltens von Windparks mit probabilistischen Ansätzen." Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-202982.
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Oberschwingungen als ein Merkmal der Elektroenergiequalität gewinnen durch die starke Netzintegration leistungselektronisch geregelter Anlagen wie Windenergieanlagen und nichtlineare Lasten zunehmend an Bedeutung. Bestehende Normen entsprechen nicht den zukünftigen Erfordernissen des Elektroenergiesystems und bedürfen diesbezüglich einer Überarbeitung. In der Arbeit werden wesentliche Einflussfaktoren auf das Oberschwingungsverhalten von Windparks identifiziert, beschrieben und modelliert. Dabei wird der stochastische Charakter der Oberschwingungen mithilfe von probabilistischen Ansätzen erfasst. Des Weiteren wird ein neuer Ansatz zur Untersuchung der Wechselwirkung zwischen dem Windpark und dem vorgelagerten Netz entwickelt. Der Ansatz ermöglicht, die vom Windpark verursachte Änderung der Oberschwingungsspannung am Netzanschlusspunkt zu ermitteln. Diese Arbeit liefert einen Beitrag zur Verbesserung bestehender Normen für die Anbindung von WindparksHarmonics, as one of the power quality criteria, are increasingly gaining attention due to the progressive contribution of renewable energy resources and the application of the nonlinear load in the power system. Current standards do not conform to the future requirements of the power system, thus requiring a revision. In this work, main influence factors on the harmonic behavior of wind farms are identified, explained, and modelled. Thereby, the stochastic nature of harmonics is taken into account using probabilistic approaches. Moreover, a novel approach is developed to investigate the interaction between the wind farm and the upstream grid. With the aid of this approach, it is possible to determine the voltage change caused by the wind farm at the point of connection. This work contributes to improve the existing standards for the connection of wind farms
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Alfarra, Anas [Verfasser], and Andreas [Akademischer Betreuer] Dittrich. "Numerische Analyse von Bauwerk-Wind-Wechselwirkungen mit RANS-Turbulenzmodellen / Anas Alfarra ; Betreuer: Andreas Dittrich." Braunschweig : Technische Universität Braunschweig, 2015. http://d-nb.info/1175818682/34.
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Bauer-Pfundstein, Matthias [Verfasser]. "Bestimmung von Turbulenzparametern und der Schallabsorption mit einem Wind-Temperatur-RADAR / Matthias Bauer-Pfundstein." Karlsruhe : KIT-Bibliothek, 1999. http://d-nb.info/1198223731/34.
Full textBooks on the topic "MLT winds"
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Holderied, Wilhelm. Mit Schatten und Wind. München: Obalski & Astor, 1993.
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Braun, Sabrina. Windlandschaft: Neue Landschaften mit Windenergieanlagen. Berlin: WVB, Wissenschaftlicher Verlag Berlin, 2006.
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1942-, Bingham Charlotte, ed. Flieg mit dem Wind: Roman. Augsburg: Weltbild, 2005.
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1961-, Bass Catriona, ed. Gebetsfahnen im Wind: Begegnung mit Tibet. München: Frederking und Thaler, 2001.
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Die mit dem Wind reitet: Roman. Gütersloh: Bertelsmann Club, 1992.
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Thenior, Ralf. Drache mit Zahnweh im Wind: Reisegedichte. Frankfurt am Main: Tende, 1990.
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Drache mit Zahnweh im Wind: Reisegedichte. Dülmen-Hiddingsel: Tende, 1990.
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Die Windenergieindustrie: Evolution von Akteuren und Unternehmensstrukturen in einer Wachstumsindustrie mit räumlicher Perspektive. Hamburg: Geographische Gesellschaft, 2011.
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Klaus, Braun. Der Einfluss mesoskaliger Windfelder auf die räumliche Verteilung des Niederschlags: Eine Untersuchung zur Regionalisierung von Niederschlagsdaten mit Hilfe eines mesoskaligen Strömungsmodells. Freiburg: Im Selbstverlag des Institutes für Physische Geographie der Albert-Ludwigs-Universität Freiburg i. Br., 1997.
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Makait, Martin. Investitionsplanung für Seeschiffe mit Windzusatzantrieb. Göttingen: Vandenhoeck & Ruprecht, 1986.
Find full textBook chapters on the topic "MLT winds"
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Seifert, Carsten. "Wind Zones." In Spiele entwickeln mit Unity, 263–66. München: Carl Hanser Verlag GmbH & Co. KG, 2014. http://dx.doi.org/10.3139/9783446441293.013.
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Seifert, Carsten. "Wind Zones." In Spiele entwickeln mit Unity 5, 339–42. München: Carl Hanser Verlag GmbH & Co. KG, 2015. http://dx.doi.org/10.3139/9783446445802.013.
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Seifert, Carsten, and Jan Wislaug. "Wind Zones." In Spiele entwickeln mit Unity 5, 367–70. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9783446453685.013.
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Johnsen, Björn. "Mit Laserstrahlen in den Wind schießen." In Meer – Wind – Strom, 105–16. Wiesbaden: Springer Fachmedien Wiesbaden, 2016. http://dx.doi.org/10.1007/978-3-658-09783-7_12.
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Latniak, Erich. "Erfahrungen mit Beteiligung." In Frischer Wind in der Fabrik, 227–39. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-58430-5_11.
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Wagenaar, J. W. "Met Mast Measurements of Wind Turbine Wakes." In Handbook of Wind Energy Aerodynamics, 1179–95. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-31307-4_57.
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Wagenaar, J. W. "Met Mast Measurements of Wind Turbine Wakes." In Handbook of Wind Energy Aerodynamics, 1–17. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-05455-7_57-1.
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Kinkel, Steffen, and Gunter Lay. "Zum Umgang mit Kennzahlen als Indikatoren wirtschaftlichen Erfolgs." In Frischer Wind in der Fabrik, 271–81. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-58430-5_16.
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Bothe, Ingeborg. "Ansatz, Funktionen und Erfahrungen mit „mitarbeiterorientiertem Prozeßcontrolling“ in betrieblichen Veränderungsprozessen." In Frischer Wind in der Fabrik, 257–63. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-58430-5_14.
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Veith, Michael, Cosima Lindemann, Andreas Kiefer, and Martin Koch. "Windkraft und Fledermausschutz im Wald – eine kritische Betrachtung der Planungs- und Zulassungspraxis." In Evidenzbasiertes Wildtiermanagement, 149–97. Berlin, Heidelberg: Springer Berlin Heidelberg, 2023. http://dx.doi.org/10.1007/978-3-662-65745-4_7.
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ZusammenfassungDer Ausbau der Windenergie findet zunehmend im Wald statt, da hier häufig windhöffige und damit ökonomisch attraktive Standorte zu finden sind. Allerdings ist hier der Konflikt mit dem Artenschutz im Allgemeinen und dem Fledermausschutz im Speziellen besonders hoch. In diesem Beitrag beleuchten wir vor dem Hintergrund des gesetzlich vorgegebenen normativen Rahmens den artenschutzrechtlichen Teil der Windkraftplanung im Wald mit Bezug auf Fledermäuse – von der Untersuchungsplanung über die eingesetzten Methoden bis zur Bewertung. Bezogen auf Fledermäuse stehen hier insbesondere die Vermeidung der direkten Tötung sowie die Verminderung der Beeinträchtigung ihres Lebensraums im Fokus der Betrachtung. Bundesland-spezifische Arbeitshilfen stecken den Untersuchungsumfang, die einzusetzenden Erfassungsmethoden und den räumlichen und zeitlichen Untersuchungsrahmen ab. Sie empfehlen zudem Maßnahmen zur Kompensation potenziell negativer Auswirkungen eines Eingriffs. Ihr Effekt auf die methodische Qualität der Fachbeiträge zu Fledermäusen ist jedoch gering. Meist kommen im Rahmen der speziellen artenschutzrechtlichen Prüfung zu Fledermäusen die Quartierbaumsuche, Netzfang, unterschiedliche Varianten des akustischen Monitorings (aktiv und passiv) sowie die Radiotelemetrie zum Einsatz. Insbesondere bei der bevorzugt empfohlenen akustischen Erfassung mindern zahlreiche methodische Probleme auf der technischen und der analytischen Ebene die Aussagekraft. Auch der Erfolg des Fangs von Fledermäusen mit Netzen hängt von zahlreichen Parametern ab. Die Quartierbaumerfassung lässt sich in ihrem Erfolg deutlich durch die Radiotelemetrie verbessern. Zur sinnvollen Quantifizierung des Lebensraumanspruchs einer Fledermauspopulation jedoch werden mittels Radiotelemetrie in der Regel zu wenige Tiere zu kurz untersucht. Die Bewertung der erhobenen Daten, hier gezeigt anhand akustisch ermittelter Aktivitätsdichten, erfolgt subjektiv, da Bewertungskriterien fehlen. Die am häufigsten empfohlenen und somit umgesetzten Methoden der Konfliktvermeidung und -minimierung sind CEF- (= Continued Ecological Function) und FCS-Maßnahmen (= Favourable Conservation Status) sowie das Gondelmonitoring und die selektive Abschaltung der WEA. Auch diese Maßnahmen entfalten z. T. Schwächen; die Bewahrung und Entwicklung von Waldstandorten als/zu ökologisch wertvollen Lebensräumen sowie die Verminderung der Schlagopferzahl durch spezielle Algorithmen (ProBat-Tool) sehen wir jedoch als sinnvoll an. Abschließend formulieren wir Anregungen zur Verbesserung und Objektivierung der Eingriffsplanung von WEA im Wald.SummaryThe development of wind energy is concentrating in forests, as windy and thus economically favourable sites can often be found here. However, the conflict with species conservation in general and bat conservation in particular is especially high in forests. We here examine the impact assessment on bats in the context of the legally prescribed normative framework in wind farm planning in the forest – from the study design to the methods used and the assessment itself. With regard to bats, the focus here is on avoiding direct killing and reducing the impairment of their habitat. Guidance documents for the German federal states define the extent of the surveys, the survey methods, and the spatial and temporal scope of a survey. They also recommend measures to compensate for potential negative impacts of wind energy plants (WEP). However, their effect on the quality of the expert reports on bats is low. In most cases, the search for roost trees, mist netting, different types of acoustic monitoring (active and passive) and radio tracking are used. In particular, numerous methodological problems at the technical and analytical levels reduce the validity of acoustic surveys. The success of mist netting bats also depends on numerous parameters. The success of roost tree surveys can be significantly improved by radio tracking. However, for a meaningful quantification of the habitat requirements of a bat population, radio tracking is usually used on too few animals for too short a time. The evaluation of the collected data, shown here on the basis of acoustically determined activity densities, is subjective because evaluation criteria are lacking. The most frequently recommended and thus implemented methods of conflict mitigation are CEF (= Continued Ecological Function and FCS (= Favourable Conservation Status) measures as well as nacelle monitoring and selective shut-down of wind turbines. These measures also show some weaknesses, but we consider the maintenance and development of forest sites as or into ecologically valuable habitats, as well as the reduction of the number of bat fatalities by means of specific algorithms (ProBat tool), to be sensible. Finally, we make suggestions for improving and objectifying the impact assessment of wind-energy facilities in forests.
Conference papers on the topic "MLT winds"
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Egito, Fábio, Paulo P. Batista, Barclay R. Clemesha, and Ricardo A. Buriti. "Vertical winds and 3-4 day momentum flux in the MLT inferred from meteor radar measurements." In 14th International Congress of the Brazilian Geophysical Society & EXPOGEF, Rio de Janeiro, Brazil, 3-6 August 2015. Brazilian Geophysical Society, 2015. http://dx.doi.org/10.1190/sbgf2015-289.
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Jeans, Gus, Dave Quantrell, Andrew Watson, Laure Grignon, and Gil Lizcano. "A New Assessment of Offshore Wind Profile Relationships." In ASME 2018 1st International Offshore Wind Technical Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/iowtc2018-1052.
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Engineering design codes specify a variety of different relationships to quantify vertical variations in wind speed, gust factor and turbulence intensity. These are required to support applications including assessment of wind resource, operability and engineering design. Differences between the available relationships lead to undesirable uncertainty in all stages of an offshore wind project. Reducing these uncertainties will become increasingly important as wind energy is harnessed in deeper waters and at lower costs. Installation of a traditional met mast is not an option in deep water. Reliable measurement of the local wind, gust and turbulence profiles from floating LiDAR can be challenging. Fortunately, alternative data sources can provide improved characterisation of winds at offshore locations. Numerical modelling of wind in the lower few hundred metres of the atmosphere is generally much simpler at remote deepwater locations than over complex onshore terrain. The sophistication, resolution and reliability of such models is advancing rapidly. Mesoscale models can now allow nesting of large scale conditions to horizontal scales less than one kilometre. Models can also provide many decades of wind data, a major advantage over the site specific measurements gathered to support a wind energy development. Model data are also immediately available at the start of a project at relatively low cost. At offshore locations these models can be validated and calibrated, just above the sea surface, using well established satellite wind products. Reliable long term statistics of near surface wind can be used to quantify winds at the higher elevations applicable to wind turbines using the wide range of existing standard profile relationships. Reduced uncertainty in these profile relationships will be of considerable benefit to the wider use of satellite and model data sources in the wind energy industry. This paper describes a new assessment of various industry standard wind profile relationships, using a range of available met mast datasets and numerical models.
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Thys, Alexandre C., and Roger H. Charlier. "Marine Winds Energy on the Forefront of Development." In ASME 2005 International Solar Energy Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/isec2005-76254.
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Not so many decades ago any proposal to capture the energy of marine winds would have been met with condescending smiles and the conviction that if even such electricity source would be put to use it would be on at best a pilot scale. Really thoughts of large installations were just one of those far-fetched engineers’ dreams best relegated to the pages of scientific periodicals. Yet, of all the marine sources of energy harnessed to produce electricity, wind power is among the leaders. This paper will consider the wind farms established off and on shore; the largest projects have been implanted in the Scandinavian countries though their southern neighbors, particularly Germany and The Netherlands are displaying a solid determination to use marine winds for electricity generation. The technology exists, the environmental nuisance is benign if sites are carefully selected. But detractors still exist and they object to aesthetic damage that, they claim, is brought about. Implementation is occasionally stymied for judiciary and/or political reasons; the case of Belgium is used as an example.
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Westwater, E. R., and B. B. Stankov. "Recent Results in Combined Ground-based and Satellite Remote Sensing." In Optical Remote Sensing of the Atmosphere. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/orsa.1993.mc.2.
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The implementation of the Wind Profiler Demonstration Network [1] is an indication of the increased reliance of the operational community on remote sensors. The Wind Profilers themselves can measure winds to about 16 km with a spatial resolution of 300-900 m on an hourly basis; their horizontal spacings vary from about 200 to 300 km. If the same spatial and temporal coverage of temperature, water vapor and clouds could be achieved many of the needs of forecasters and researchers could be met. However, even if the ambitious goal of measuring both dynamic and thermodynamic variables from a network of surface-based stations could be met, station deployment on a 25 to 50 km grid would be prohibitively expensive. Observations from both polar-orbiting and geostationary satellites, when combined with data from a limited grid of surface-based remote sensors, may provide the necessary horizontal coverage as well as improve upper altitude accuracy. In this paper, we present new results and discuss several possibilities of combining surface-based and satellite data.
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Rasheed, Adil, Jakob Kristoffer Süld, and Mandar Tabib. "Effect of Uni- and Bi-Directional Coupling of Ocean-Met Interaction on Significant Wave Height and Local Wind." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61681.
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Accurate prediction of near surface wind and wave height are important for many offshore activities like fishing, boating, surfing, installation and maintenance of marine structures. The current work investigates the use of different methodologies to make accurate predictions of significant wave height and local wind. The methodology consists of coupling an atmospheric code HARMONIE and a wave model WAM. Two different kinds of coupling methodologies: unidirectional and bidirectional coupling are tested. While in Unidirectional coupling only the effects of atmosphere on ocean surface are taken into account, in bidirectional coupling the effects of ocean surface on the atmosphere are also accounted for. The predicted values of wave height and local wind at 10m above the ocean surface using both the methodologies are compared against observation data. The results show that during windy conditions, a bidirectional coupling methodology has better prediction capability.
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Locke, James, Ulyses Valencia, and Kosuke Ishikawa. "Design Studies for Twist-Coupled Wind Turbine Blades." In ASME 2003 Wind Energy Symposium. ASMEDC, 2003. http://dx.doi.org/10.1115/wind2003-1043.
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This study presents results obtained for three designs of the Northern Power Systems (NPS) 9.2-meter version of the ERS-100 wind turbine rotor blade. The ERS-100 wind turbine rotor blade was designed and developed by TPI composites. The baseline design uses e-glass unidirectional fibers in combination with ±45-degree and random mat layers for the skin and spar cap. This project involves developing structural finite element models of the baseline design and carbon hybrid designs with twist-bend coupling. All designs were evaluated for a unit load condition and two extreme wind conditions. The unit load condition was used to evaluate the static deflection, twist and twist-coupling parameter. Maximum deflections and strains were determined for the extreme wind conditions. Buckling eigenvalues were determined for a tip load condition. The results indicate that carbon fibers can be used to produce twist-coupled designs with comparable deflections, strains and buckling loads.
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Melville, W. Kendall, Lenonel Romero, and Jessica Kleiss. "Observations of Surface Waves and Wave Breaking: A Tribute to Nick Newman." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57490.
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The Gulf of Tehuantepec is well known for having strong offshore winds, which occur predominantly during the winter months when significant atmospheric pressure differences develop between the Gulf of Mexico and the Pacific Ocean, forcing winds through a mountain gap at the head of the gulf. During the Gulf of Tehuantepec Experiment (GOTEX), conducted in February 2004, we collected surface-wave and wave-breaking measurements using a conical scanning lidar (NASA Airborne Terrain Mapper, ATM) and a downward-looking video camera on the NSF/NCAR C-130 aircraft. We present ATM observations of surface waves as well as statistical and spectral descriptions of the wave field. We also present measurements of the occurrence and strength of breaking using digital video data to identify actively breaking waves. In order to infer the dynamics of breaking from simple physical models, the kinematics of the breaking must be separated from the kinematics of the underlying waves. This is done using linear and nonlinear estimates of the underlying orbital velocities from the spatio-temporal surface displacement data measured by the ATM. Nonlinear estimation of the orbital velocities is described in a companion paper in this symposium (Grue et al., OMAE 2008). Frequent breaking is observed under the strong wind forcing. Examples of the spatial structure of waves are compared to simultaneous video imagery, giving an indication of the scale at which wave breaking occurs. The GOTEX observations, to almost full wave development, are tested against the latest wind-wave numerical spectral models that include the effects of wave generation, nonlinear wave-wave interactions and wave dissipation due to breaking. This paper is dedicated to Nick Newman by the lead author in appreciation of Nicks encouragement and assistance when he (WKM) moved to MIT in the early 1980s.
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Nordstrom, Christina D., Peter B. Lacey, Bob Grant, and Derek D. Hee. "Impact of FPSO Heading on Fatigue Design in Non-Collinear Environments." In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28133.
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To achieve confidence in continuous 20+ year FPSO service without fatigue cracks leading to costly repair offshore or in dry-dock, ExxonMobil has developed a prescriptive Fatigue Methodology Specification (FMS, ref. 5) for new-build FPSOs. An important FMS requirement for turret-moored FPSOs is to determine relative wave headings in non-collinear wind, current and wave environments using a first-principles approach. Based on initial review with FPSO designers, this FMS requirement may pose a significant challenge because appropriately defined met-ocean criteria and efficient analytical design tools are not readily available. To date, FPSO designers typically account for weather-vaning in non-collinear environments by assuming a distribution of relative wave headings based on experience. For example, one assumption is to use 0 degrees (head seas) for 70% of the time and within ±30 degrees off the bow for the remaining 30%. In certain environments, this assumption can lead to a non-conservative fatigue design for hull structural details that are sensitive to beam seas, and an overly conservative fatigue design for details sensitive to head seas. ExxonMobil contracted Moffat & Nichol to develop a time-domain procedure to predict mean FPSO headings by considering wave, wind and current induced loads on the FPSO hull and topsides throughout the FPSO’s 20+ year operational life. A key element of this methodology is a directional representation of met-ocean data, including waves, winds and currents for every 3- or 6-hour sea-state. We have implemented our heading analysis procedure in robust software, which includes processing of the 20+ year met-ocean data in the time domain. Once the FPSO heading time history is known, fatigue lives at critical structural connections are predicted using the spectral fatigue method prescribed in the FMS. To demonstrate the heading methodology and assess its efficiency for project use, an example analysis was performed for an FPSO at a specific geographic location, where relatively strong currents exist. Comparison of predicted FPSO headings and fatigue lives with those using the existing industry practices confirmed the need for a first principles based heading methodology for FPSO fatigue design. The heading and fatigue analysis procedure described here can lead to more accurate, robust fatigue designs for FPSOs in non-collinear environments.
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Burdett, Timothy A., and Kenneth W. Van Treuren. "Small-Scale Wind Turbines Optimized for Class 2 Wind: A Wind Siting Survey and Annual Energy Production Analysis." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26243.
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A crucial step in evaluating a potential location for a wind turbine, especially small-scale wind turbines, is a proper wind site survey. Eventually the wind site survey is used to calculate the annual energy production (AEP) of the wind turbine and determine if this location will be profitable. Generally, a wind classification of 3 or above is recommended for any wind turbine site, according to the U.S. Department of Energy. Wind Classes of 1–2 are not considered suitable; however, data suggests that a wind site with Class of 2 wind has the potential to be more cost effective than even the least expensive offshore wind and deserves consideration. Wind data usually exists at locations such as local airports; however, the height at which this data are taken is not representative of the heights at which wind turbines will be installed and thus, airport wind data should not be used. Also, with the variability in wind from location to location, the airport data are generally not near the potential site for the wind turbine and thus, are not useful. A local wind site survey generally entails a two year study of the site using a meteorological (MET) tower. Waco, TX is being studied for the application of small-scale wind turbines. Waco is in a Class 2 wind area; however, no proper wind survey had ever been accomplished. Such a study was undertaken using a MET tower of 100 ft with two anemometers at 100 ft, one anemometer at 75 ft and one anemometer at 50 ft. This paper will describe the potential of Class 2 wind as an energy source, the erection of the MET tower, collection of the data and analysis of the data for the potential of locating a small-scale wind turbine at the site. Techniques for analyzing data when two anemometers are present will be discussed. Focus will be on identifying invalid data with an emphasis on correcting this invalid data. The data from two anemometers was then used in a novel way to identify and correct the invalid data found at both the 75 ft and 50 ft elevations. A filtering technique has also been developed to help identify invalid data. Based on the results of the wind survey, it will be shown that it is feasible to purposely design wind turbine blades for Class 2 wind which will perform better than commercially available small-scale wind turbines.
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Wang, Zixu, Jianhong Zhu, Juping Gu, Junjie Hu, Bojun Zhou, and Jiahao Zhao. "Fault Diagnosis of Wind Turbine Bearing on SATLBO-MLP." In 2022 China Automation Congress (CAC). IEEE, 2022. http://dx.doi.org/10.1109/cac57257.2022.10056041.
Full textReports on the topic "MLT winds"
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Kieslinger, Daniel, and Judith Owsianowski. Newsletter Inklusion jetzt! November 2022. BVKE, EREV, Inklusion jetzt!, November 2022. http://dx.doi.org/10.54953/gszg2767.
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Der November bringt wieder viele Turbulenzen und Themen mit sich: nun zeigen die Temperaturen deutlich, dass es Herbst wird. Die Blätter haben sich bunt verfärbt und überlassen sich schon zum großen Teil durch den Wind dem Wandel der Zeit. Auch in der Kinder- und Jugendhilfe geht der Wandel weiter: Am 17.11.2022 begann mit dem ersten AG-Treffen des Prozesses „Gemeinsam zum Ziel – Wir gestalten die inklusive Kinder- und Jugendhilfe“ der Beteiligungsprozess für die Weiterentwicklung des SGB VIII. Bis Ende 2024 soll eine Antwort darauf gefunden sein, wie die „Inklusive Lösung“ umgesetzt werden kann – bis dahin soll der Entwurf zu einem neuen Gesetz vorliegen. Aber auch an anderen Stellen schreiten Entwicklungsprozesse fort, zu denen wir in diesem Newsletter kleine interessante Einblicke geben wollen.
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Manor, M. J., and S. J. Piercey. Whole-rock lithogeochemistry, Nd-Hf isotopes, and in situ zircon geochemistry of VMS-related felsic rocks, Finlayson Lake VMS district, Yukon. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328992.
Full textAbstract:
The Finlayson Lake district in southeastern Yukon is composed of a Late Paleozoic arc-backarc system that consists of metamorphosed volcanic, plutonic, and sedimentary rocks of the Yukon-Tanana and Slide Mountain terranes. These rocks host >40 Mt of polymetallic resources in numerous occurrences and styles of volcanogenic massive sulphide (VMS) mineralization. Geochemical and isotopic data from these rocks support previous interpretations that volcanism and plutonism occurred in arc-marginal arc (e.g., Fire Lake formation) and continental back-arc basin environments (e.g., Kudz Ze Kayah formation, Wind Lake formation, and Wolverine Lake group) where felsic magmatism formed from varying mixtures of crust- and mantle-derived material. The rocks have elevated high field strength element (HFSE) and rare earth element (REE) concentrations, and evolved to chondritic isotopic signatures, in VMS-proximal stratigraphy relative to VMS-barren assemblages. These geochemical features reflect the petrogenetic conditions that generated felsic rocks and likely played a role in the localization of VMS mineralization in the district. Preliminary in situ zircon chemistry supports these arguments with Th/U and Hf isotopic fingerprinting, where it is interpreted that the VMS-bearing lithofacies formed via crustal melting and mixing with increased juvenile, mafic magmatism; rocks that were less prospective have predominantly crustal signatures. These observations are consistent with the formation of VMS-related felsic rocks by basaltic underplating, crustal melting, and basalt-crustal melt mixing within an extensional setting. This work offers a unique perspective on magmatic petrogenesis that underscores the importance of integrating whole-rock with mineral-scale geochemistry in the characterization of VMS-related stratigraphy.
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Avis, William. Drivers, Barriers and Opportunities of E-waste Management in Africa. Institute of Development Studies (IDS), December 2021. http://dx.doi.org/10.19088/k4d.2022.016.
Full textAbstract:
Population growth, increasing prosperity and changing consumer habits globally are increasing demand for consumer electronics. Further to this, rapid changes in technology, falling prices and consumer appetite for better products have exacerbated e-waste management challenges and seen millions of tons of electronic devices become obsolete. This rapid literature review collates evidence from academic, policy focussed and grey literature on e-waste management in Africa. This report provides an overview of constitutes e-waste, the environmental and health impacts of e-waste, of the barriers to effective e-waste management, the opportunities associated with effective e-waste management and of the limited literature available that estimate future volumes of e-waste. Africa generated a total of 2.9 million Mt of e-waste, or 2.5 kg per capita, the lowest regional rate in the world. Africa’s e-waste is the product of Local and imported Sources of Used Electronic and Electrical Equipment (UEEE). Challenges in e-waste management in Africa are exacerbated by a lack of awareness, environmental legislation and limited financial resources. Proper disposal of e-waste requires training and investment in recycling and management technology as improper processing can have severe environmental and health effects. In Africa, thirteen countries have been identified as having a national e-waste legislation/policy.. The main barriers to effective e-waste management include: Insufficient legislative frameworks and government agencies’ lack of capacity to enforce regulations, Infrastructure, Operating standards and transparency, illegal imports, Security, Data gaps, Trust, Informality and Costs. Aspirations associated with energy transition and net zero are laudable, products associated with these goals can become major contributors to the e-waste challenge. The necessary wind turbines, solar panels, electric car batteries, and other "green" technologies require vast amounts of resources. Further to this, at the end of their lifetime, they can pose environmental hazards. An example of e-waste associated with energy transitions can be gleaned from the solar power sector. Different types of solar power cells need to undergo different treatments (mechanical, thermal, chemical) depending on type to recover the valuable metals contained. Similar issues apply to waste associated with other energy transition technologies. Although e-waste contains toxic and hazardous metals such as barium and mercury among others, it also contains non-ferrous metals such as copper, aluminium and precious metals such as gold and copper, which if recycled could have a value exceeding 55 billion euros. There thus exists an opportunity to convert existing e-waste challenges into an economic opportunity.
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Whitaker, Stephen. Rocky intertidal community monitoring at Channel Islands National Park: 2018–19 annual report. National Park Service, August 2023. http://dx.doi.org/10.36967/2299674.
Full textAbstract:
Channel Islands National Park includes the five northern islands off the coast of southern California (San Miguel, Santa Rosa, Santa Cruz, Anacapa, and Santa Barbara Islands) and the surrounding waters out one nautical mile. There are approximately 176 miles of coastline around the islands, about 80% of which is composed of rock. The diversity and undisturbed nature of the tidepools of this rocky coastline were recognized as special features of the islands in the enabling legislation. To conserve these communities unimpaired for future generations, the National Park Service has been monitoring the rocky intertidal communities at the islands since 1982. Sites were established between 1982 and 1998. Site selection considered visitation, accessibility, presence of representative organisms, wildlife disturbance, and safety. This report summarizes the 2018–2019 sampling year efforts (from November 2018 to April 2019) and findings of the Channel Islands National Park Rocky Intertidal Community Monitoring Program. Specific monitoring objectives are 1) to determine the long-term trends in percent cover of key sessile organisms in the rocky intertidal ecosystem, and 2) to determine population dynamics of black abalone (Haliotis cracherodii), owl limpets (Lottia gigantea), and ochre sea stars (Pisaster ochraceus). Objectives were met by monitoring percent cover of core species in target intertidal zones using photoplots and transects, and by measuring size frequency and abundance of black abalone, owl limpets, and sea stars using fixed plots or timed searches. Twelve key species or assemblages, as well as the substrate, tar, have been monitored twice per year at 21 sites on the five park islands as part of the rocky intertidal community monitoring program. Fixed photoplots were used to monitor the percent cover of thatched and acorn barnacles (Tetraclita rubescens, Balanus glandula/Chthamalus spp., respectively), mussels (Mytilus californianus), rockweeds (Silvetia compressa, and Pelvetiopsis californica (formerly Hesperophycus californicus), turfweed (Endocladia muricata), goose barnacles (Pollicipes polymerus) and tar. Point-intercept transects were used to determine the percent cover of surfgrass (Phyllospadix spp.). Information about size distribution (i.e., “size frequency” data) was collected for owl limpets in circular plots. Size distribution and relative abundance of black abalone and ochre sea stars were determined using timed searches. The maximum number of shorebirds and pinnipeds seen at one time were counted at each site. The number of concession boat visitors to the Anacapa tidepools was collected and reported. All sites were monitored in 2018–2019. This was the third year that we officially reduced our sampling interval from twice per year (spring and fall) to once in order to streamline the program and allow for the implementation of additional protocols. Weather conditions during the site visits were satisfactory, but high wind coupled with strong swell and surge limited or prevented the completion of some of the abalone and sea star searches. The percent cover for most key species or assemblages targeted in the photoplots was highly variable among sites. Mussel (Mytilus californianus) cover remained below average at Anacapa and Santa Barbara Islands. Record or near record low abundances for Mytilus were measured at Middle West Anacapa (Anacapa Island), Harris Point (San Miguel Island), Prisoner’s Harbor (Santa Cruz Island), and Sea Lion Rookery (Santa Barbara Island) sites. The only site that appeared to have above average Mytilus cover was Scorpion Rock on Santa Cruz Island. All other sites had mussel cover near or below the long-term mean. Qualitatively, Mytilus recruitment appeared low at most sites. Both rockweed species, Silvetia compressa and Pelvetiopsis californica (formerly Hesperophycus californicus), continued to decrease markedly in abundance this year at the majority of sites compared to combined averages for previous years. Fossil Reef and Northwest-Talcott on Santa Rosa Island, Sea Lion Rookery on Santa Barbara Island, and South Frenchy’s Cove on Anacapa Island were the only sites that supported Silvetia cover that was near the long-term mean. No sites exhibited above average cover of rockweed. Extremely high levels of recruitment for Silvetia and Pelvetiopsis were documented at many sites. Most sites exhibited marked declines in S. compressa abundances beginning in the early 2000s, with little recovery observed for the rockweed through this year. Barnacle (Chthamalus/Balanus spp.) cover fell below the long-term means at all islands except Anacapa, where barnacle cover was slightly above average. Endocladia muricata abundances remained comparable to the grand mean calculated for previous years at Santa Barbara, Santa Cruz, and Santa Rosa Islands, while cover of the alga decreased slightly below the long-term means at Anacapa and San Miguel Islands. Black abalone (Haliotis cracherodii) abundances at the islands remain less than one percent of 1985 population levels. Zero abalone were found throughout the entire site at Landing Cove on Santa Barbara Island and South Frenchy’s Cove on Anacapa Island. Above average abundances relative to the long-term mean generated from post-1995 data were observed at all but five sites. Juvenile black abalone were seen at all islands except Santa Barbara. Ochre sea star (Pisaster ochraceus) populations crashed in 2014 at all monitoring sites due to Sea Star Wasting Syndrome, an illness characterized by a suite of symptoms that generally result in death. The mortality event was widely considered to be the largest mortality event for marine diseases ever seen. Beginning in June 2013, the disease swiftly and significantly impacted P. ochraceus (among other species of sea stars) populations along the North American Pacific coast from Alaska to Baja California, Mexico. By the beginning of 2014, P. ochraceus abundances had declined by >95% at nearly all Channel Islands long-term intertidal monitoring sites, in addition to numerous other locations along the West Coast. At various times during the past decade, extremely high abundances (~ 500 P. ochraceus) have been observed at multiple sites, and most locations have supported >100 sea stars counted during 30-minute site-wide searches. This year, abundances ranged 0–13 individuals per site with all but one site having fewer than 10 P. ochraceus seen during routine searches. Insufficient numbers of sea stars were seen to accurately estimate the size structure of P. ochraceus populations. Only two juveniles (i.e., <50 mm) were observed at all sites combined. Giant owl limpet densities in 2018–2019 were comparable or slightly above the long-term mean at seven sites. Exceptionally high densities were measured at Northwest-Talcott on Santa Rosa Island, Otter Harbor on San Miguel Island, and Willows Anchorage on Santa Cruz Island. The sizes of L. gigantea this year varied among sites and islands. The smallest L. gigantea were observed at Otter Harbor followed closely by Willows Anchorage and Anacapa Middle West, and the largest were seen at Northwest-Talcott. Temporally, the mean sizes of L. gigantea in 2018–2019 decreased below the long-term mean at each island except Anacapa. Surfgrasses (Phyllospadix spp.) are typically monitored biannually at two sites each on Santa Cruz and Santa Rosa Islands. Beginning in 2015, all transects at each of the monitoring sites were only sampled once per year. At East Point on Santa Rosa Island, the conditions were not conducive to sampling the surfgrass transects, but qualitatively, percent cover of surfgrass appeared to be near 100% on all three transects. Relative to past years, cover of surfgrass increased above the long-term mean at Fraser Cove on Santa Cruz Island, fell slightly below the mean at Trailer on Santa Cruz Island, and remained approximately equivalent to the mean at the two Santa Rosa Island sites. Overall, the abundance and diversity of shorebirds in 2018–2019 at all sites appeared similar to observations made in recent years, with the exception of elevated numbers of brown pelicans (Pelecanus occidentalis) observed at East Point on Santa Rosa Island. Black oystercatchers (Haematopus bachmani) were the most ubiquitous shorebird seen at all sites. Black turnstones (Arenaria melanocephala) were not common relative to past years. Pinniped abundances remained comparable in 2018–2019 to historical counts for all three species that are commonly seen at the islands. Harbor seals (Phoca vitulina) were seen in the vicinity of eight sites this year. As in past years, harbor seals were most abundant at Otter Harbor and Harris Point on San Miguel Island. Elephant seals (Mirounga angustirostris) were seen at six sites during the year, where abundances ranged 1–5 individuals per location. California sea lions (Zalophus californianus) were common at Santa Barbara Island; 117 individuals were observed at Sea Lion Rookery. Sea lion abundances were higher than usual at Harris Point (N = 160) and Otter Harbor (N = 82) on San Miguel Island. Relative to past years, abundances this year were considered average at other locations.