1,172 research outputs found
Improving wear performance of wind turbine gearboxes using ionic liquids as additives of lubricants
Wind resources are a proven source of clean, affordable and sustainable energy.
Wind energy does not produce harmful pollution gases such carbon dioxide, sulphur
dioxide, or other gases that have contributed to global warming. The wind energy
industry has seen rapid growth within the last decade; however the cost of
maintaining the turbines is a major drawback. Wind turbine gearboxes present one of
the more challenging current practical tribological problems. Contact failures in gear
and bearing components have been the source of costly repairs and downtime of the
turbine’s drivetrain and actuator. A potential solution to reduce contact failures in
wind turbines and increase their lifespan, is the use of ionic liquids (IL) as lubricant or
additives of lubricants. ILs have the ability to form stable ordered layers on the
contact area between the materials, reducing friction and wear.
In this work, the wear behavior of trihexyltetradecylphosphonium
bis(trifluoromethylsulfonyl) amide used as additive in two oils is studied and
compared to commercially available, fully formulated lubricant. Lubricated disks of
steel AISI 52100 mated with AISI 440C stainless steel balls are studied using a ballon-
flat reciprocating configuration under variable conditions of normal applied load
and sliding frequency. The use of the IL as additive in a base oil reduce wear,
particularly under the lowest frequency studied.The authors acknowledge financial support from New York State Pollution
Prevention Institute (NYSP2I 2013)-Increasing the Reliability and Efficiency of
Wind Turbines by Reducing Gearbox Friction and Wear
Kaon electromagnetic production: constraints set by new data
The CLAS data on the photo-production of K+ off the proton are utilised to
study reaction mechanism of the process in frame of the isobaric approach. The
missing D13 resonance is shown to be important for successful description of
the data in the whole kinematical region. Constructed models provide
satisfactory predictions for the process.Comment: 4 pages, 4 figures, contribution to the VIII International Conference
on Hypernuclear & Strange Particle Physics, Jefferson Lab, Virginia, U.S.A.,
October 14-18, 200
Spitzer observations of extragalactic H II regions - III. NGC 6822 and the hot star, H II region connection
Using the short-high module of the Infrared Spectrograph on the Spitzer Space
Telescope, we have measured the [S IV] 10.51, [Ne II] 12.81, [Ne III] 15.56,
and [S III] 18.71-micron emission lines in nine H II regions in the dwarf
irregular galaxy NGC 6822. These lines arise from the dominant ionization
states of the elements neon (Ne, Ne) and sulphur (S,
S), thereby allowing an analysis of the neon to sulphur abundance ratio
as well as the ionic abundance ratios Ne/Ne and S/S.
By extending our studies of H II regions in M83 and M33 to the lower
metallicity NGC 6822, we increase the reliability of the estimated Ne/S ratio.
We find that the Ne/S ratio appears to be fairly universal, with not much
variation about the ratio found for NGC 6822: the median (average) Ne/S ratio
equals 11.6 (12.20.8). This value is in contrast to Asplund et al.'s
currently best estimated value for the Sun: Ne/S = 6.5. In addition, we
continue to test the predicted ionizing spectral energy distributions (SEDs)
from various stellar atmosphere models by comparing model nebulae computed with
these SEDs as inputs to our observational data, changing just the stellar
atmosphere model abundances. Here we employ a new grid of SEDs computed with
different metallicities: Solar, 0.4 Solar, and 0.1 Solar. As expected, these
changes to the SED show similar trends to those seen upon changing just the
nebular gas metallicities in our plasma simulations: lower metallicity results
in higher ionization. This trend agrees with the observations.Comment: 22 pages, 13 figures. To be published in MNRAS. reference added and
typos fixed. arXiv admin note: text overlap with arXiv:0804.0828, which is
paper II by Rubin et al. (2008
Recommended from our members
T-REX Design Considerations for Detection of Concealed 238U
Here they outline considerations that might inform choices for the design of a laser/linac-based light source used to detect {sup 238}U via excitation of the resonance at 680.11 keV in this isotope. They assume that the principal concern is speed of interrogation and not, e.g., how much radiological dose is imparted during a scan. It is found that if the photon detectors used in the system have an energy resolution better than or comparable to that of the interrogation beam, then to a first approximation the light source should be designed to have the highest possible specific fluence (photons per unit energy per unit time). there is also a weak dependence of scan time on the number of photons emitted per pulse of the light source. A simple formula describing the tradeoff between specific fluence and number of photons per pulse is presented
Overview of the BlockNormal Event Trigger Generator
In the search for unmodeled gravitational wave bursts, there are a variety of
methods that have been proposed to generate candidate events from time series
data. Block Normal is a method of identifying candidate events by searching for
places in the data stream where the characteristic statistics of the data
change. These change-points divide the data into blocks in which the
characteristics of the block are stationary. Blocks in which these
characteristics are inconsistent with the long term characteristic statistics
are marked as Event-Triggers which can then be investigated by a more
computationally demanding multi-detector analysis.Comment: GWDAW-8 proceedings, 6 pages, 2 figure
A Space and Atmospheric Visualization Science System
SAVS (a Space and Atmospheric Visualization Science system) is an integrated system with user-friendly functionality that employs a 'push-button' software environment that mimics the logical scientific processes in data acquisition, reduction, analysis, and visualization. All of this is accomplished without requiring a detailed understanding of the methods, networks, and modules that link the tools and effectively execute the functions. This report describes SAVS and its components, followed by several applications based on generic research interests in interplanetary and magnetospheric physics (IMP/ISTP), active experiments in space (CRRES), and mission planning focused on the earth's thermospheric, ionospheric, and mesospheric domains (TIMED). The final chapters provide a user-oriented description of interface functionalities, hands-on operations, and customized modules, with details of the primary modules presented in the appendices. The overall intent of the report is to reflect the accomplishments of the three-year development effort and to introduce potential users to the power and utility of the integrated data acquisition, analysis, and visualization system
Superdeformation in Po
The Yb(Si,5n) reaction at 148 MeV with thin targets was used
to populate high-angular momentum states in Po. Resulting rays
were observed with Gammasphere. A weakly-populated superdeformed band of 10
-ray transitions was found and has been assigned to Po. This is
the first observation of a SD band in the region in a nucleus
with . The of the new band is very similar to those of
the yrast SD bands in Hg and Pb. The intensity profile suggests
that this band is populated through states close to where the SD band crosses
the yrast line and the angular momentum at which the fission process dominates.Comment: 10 pages, revtex, 2 figs. available on request, submitted to Phys.
Rev. C. (Rapid Communications
Plans for the LIGO-TAMA Joint Search for Gravitational Wave Bursts
We describe the plans for a joint search for unmodelled gravitational wave
bursts being carried out by the LIGO and TAMA collaborations using data
collected during February-April 2003. We take a conservative approach to
detection, requiring candidate gravitational wave bursts to be seen in
coincidence by all four interferometers. We focus on some of the complications
of performing this coincidence analysis, in particular the effects of the
different alignments and noise spectra of the interferometers.Comment: Proceedings of the 8th Gravitational Wave Data Analysis Workshop,
Milwaukee, WI, USA. 10 pages, 3 figures, documentclass ``iopart'
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