693 research outputs found
Adaptive Power Control Method Considering Reactive Power Reserve for Wave-Offshore Hybrid Power Generator System
AbstractThe combined generator system with the wind and wave power can share the off-shore platform and therefore have the advantage of constructing the transmission system as well as the power conversion system. The established wind power generator systems do output determination by following the transmission system operator's directions and control the turbine by focusing at PCC, but when connected with the wave-power generator; it is needed to do the complex control. Especially, since the method and impact of active power control are different, it is required to distribute demanding power and responsibility to each turbine by considering the grid condition. In this paper, the control system is formed to do output determination of the combined generator system by paying attention to reactive power reserve of utility grid with the analysis of the controllable elements of the wind and wave power generator. And the comparison with the existing system is carried out based on the real system information. Through using the PSCAD/EMTDC simulation, the suitability of the new control technique of the combined system is estimated by proposing the active power control according to the reference signal of TSO and the reactive power capability followed by it
1-GHz all-optical flip-flop operation of conventional cylindrical-shaped single-mode VCSELs under low-power optical injection.
Mucociliary Transit Assessment Using Automatic Tracking in Phase Contrast X-Ray Images of Live Mouse Nasal Airways
Purpose The rate of mucociliary transit (MCT) is an indicator of the hydration and health of the airways for cystic fibrosis (CF). To determine the effectiveness of cystic fibrosis respiratory therapies, we have developed a novel method to noninvasively quantify the local rate and patterns of MCT behaviour in vivo by using synchrotron phase contrast X-ray imaging (PCXI) to visualise the MCT motion of micron-sized spherical particles deposited onto the airway surfaces of live mice. Methods In this study the baseline MCT behaviour was assessed in the nasal airways of CFTR-null and normal mice which were then treated with hypertonic saline (HS) or mannitol. To assess MCT, the particle motion was tracked throughout the synchrotron PCXI sequences using fully-automated custom image analysis software. Results There was no significant difference in the MCT rate between normal and CFTR-null mice, but the analysis of MCT particle tracking showed that HS may have a longer duration of action in CFTR-null mice than in the normal mice. Conclusion This study demonstrated that changes in MCT rate in CF and normal mouse nasal airways can be measured using PCXI and customised tracking software and used for assessing the effects of airway rehydrating pharmaceutical treatments.Hye-Won Jung, Ivan Lee, Sang, Heon Lee, Kaye Morgan, David Parsons, Martin Donnelle
Amplitude measurements of Faraday waves
A light reflection technique is used to measure quantitatively the surface
elevation of Faraday waves. The performed measurements cover a wide parameter
range of driving frequencies and sample viscosities. In the capillary wave
regime the bifurcation diagrams exhibit a frequency independent scaling
proportional to the wavelength. We also provide numerical simulations of the
full Navier-Stokes equations, which are in quantitative agreement up to
supercritical drive amplitudes of 20%. The validity of an existing perturbation
analysis is found to be limited to 2.5% overcriticaly.Comment: 7 figure
Divergent consensuses on Arctic amplification influence on midlatitude severe winter weather
The article of record as published may be found at https://doi.org/10.1038/s41558-019-0662-yWe thank R. Blackport, C. Deser, L. Sun, J. Screen and D. Smith for discussions and
suggested revisions to the manuscript. We also thank J. Screen and L. Sun for model data.
A. Amin helped to create Fig. 2. US CLIVAR logistically and financially supported the
Arctic-Midlatitude Working Group and Arctic Change and its Influence on Mid-Latitude
Climate and Weather workshop that resulted in this article. J.C. is supported by the US
National Science Foundation grants AGS-1657748 and PLR-1504361, 1901352. M.W.
acknowledges funding by the Deutsche Forschungsgemeinschaft project no. 268020496–
TRR 172, within the Transregional Collaborative Research Center “Arctic Amplification:
Climate Relevant Atmospheric and Surface Processes, and Feedback Mechanisms (AC)3
”.
T.V. was supported by the Academy of Finland grant 317999. J.O. was supported by the
NOAA Arctic Research Program. J.F. was supported by the Woods Hole Research Center.
S.W. and H.G. are supported by the US DOE Award Number DE-SC0016605. J.Y. was
supported by the Korea Meteorological Administration Research and Development
Program under grant KMI2018-01015 and National Research Foundation grant
NRF_2017R1A2B4007480. D.H. is supported by the Helmholtz Association of German
Research Centers (grant FKZ HRSF-0036, project POLEX). The authors acknowledge the
World Climate Research Programme’s Working Group on Coupled Modelling, which is
responsible for CMIP, and thank the climate modelling groups (listed in Supplementary
Table 1) for producing and making available their model output. For CMIP, the US
Department of Energy’s PCMDI provides coordinating support and led development of
software infrastructure in partnership with the Global Organization for Earth System
Science Portals.The Arctic has warmed more than twice as fast as the global average since the late twentieth century, a phenomenon known as
Arctic amplification (AA). Recently, there have been considerable advances in understanding the physical contributions to AA,
and progress has been made in understanding the mechanisms that link it to midlatitude weather variability. Observational
studies overwhelmingly support that AA is contributing to winter continental cooling. Although some model experiments sup port the observational evidence, most modelling results show little connection between AA and severe midlatitude weather or
suggest the export of excess heating from the Arctic to lower latitudes. Divergent conclusions between model and observational
studies, and even intramodel studies, continue to obfuscate a clear understanding of how AA is influencing midlatitude weather
Multiplicity Studies and Effective Energy in ALICE at the LHC
In this work we explore the possibility to perform ``effective energy''
studies in very high energy collisions at the CERN Large Hadron Collider (LHC).
In particular, we focus on the possibility to measure in collisions the
average charged multiplicity as a function of the effective energy with the
ALICE experiment, using its capability to measure the energy of the leading
baryons with the Zero Degree Calorimeters. Analyses of this kind have been done
at lower centre--of--mass energies and have shown that, once the appropriate
kinematic variables are chosen, particle production is characterized by
universal properties: no matter the nature of the interacting particles, the
final states have identical features. Assuming that this universality picture
can be extended to {\it ion--ion} collisions, as suggested by recent results
from RHIC experiments, a novel approach based on the scaling hypothesis for
limiting fragmentation has been used to derive the expected charged event
multiplicity in interactions at LHC. This leads to scenarios where the
multiplicity is significantly lower compared to most of the predictions from
the models currently used to describe high energy collisions. A mean
charged multiplicity of about 1000-2000 per rapidity unit (at ) is
expected for the most central collisions at .Comment: 12 pages, 19 figures. In memory of A. Smirnitski
Geometric Entanglement of Symmetric States and the Majorana Representation
Permutation-symmetric quantum states appear in a variety of physical
situations, and they have been proposed for quantum information tasks. This
article builds upon the results of [New J. Phys. 12, 073025 (2010)], where the
maximally entangled symmetric states of up to twelve qubits were explored, and
their amount of geometric entanglement determined by numeric and analytic
means. For this the Majorana representation, a generalization of the Bloch
sphere representation, can be employed to represent symmetric n qubit states by
n points on the surface of a unit sphere. Symmetries of this point distribution
simplify the determination of the entanglement, and enable the study of quantum
states in novel ways. Here it is shown that the duality relationship of
Platonic solids has a counterpart in the Majorana representation, and that in
general maximally entangled symmetric states neither correspond to anticoherent
spin states nor to spherical designs. The usability of symmetric states as
resources for measurement-based quantum computing is also discussed.Comment: 10 pages, 8 figures; submitted to Lecture Notes in Computer Science
(LNCS
Measurement of single pi0 production in neutral current neutrino interactions with water by a 1.3 GeV wide band muon neutrino beam
Neutral current single pi0 production induced by neutrinos with a mean energy
of 1.3 GeV is measured at a 1000 ton water Cherenkov detector as a near
detector of the K2K long baseline neutrino experiment. The cross section for
this process relative to the total charged current cross section is measured to
be 0.064 +- 0.001 (stat.) +- 0.007 (sys.). The momentum distribution of
produced pi0s is measured and is found to be in good agreement with an
expectation from the present knowledge of the neutrino cross sections.Comment: 6 pages, 4 figures, Submitted to Phys. Lett.
Measurement of a small atmospheric ratio
From an exposure of 25.5~kiloton-years of the Super-Kamiokande detector, 900
muon-like and 983 electron-like single-ring atmospheric neutrino interactions
were detected with momentum MeV/, MeV/, and
with visible energy less than 1.33 GeV. Using a detailed Monte Carlo
simulation, the ratio was measured to be , consistent with previous results from the
Kamiokande, IMB and Soudan-2 experiments, and smaller than expected from
theoretical models of atmospheric neutrino production.Comment: 14 pages with 5 figure
Calibration of Super-Kamiokande Using an Electron Linac
In order to calibrate the Super-Kamiokande experiment for solar neutrino
measurements, a linear accelerator (LINAC) for electrons was installed at the
detector. LINAC data were taken at various positions in the detector volume,
tracking the detector response in the variables relevant to solar neutrino
analysis. In particular, the absolute energy scale is now known with less than
1 percent uncertainty.Comment: 24 pages, 16 figures, Submitted to NIM
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