3,443 research outputs found
Electrical cabling withstands severe environmental conditions
Multiconductor electrical cables retain their circuit integrity and remain flexible and abrasion resistant in severe environmental conditions of heat, vibration, and water
Does the butterfly diagram indicate asolar flux-transport dynamo?
We address the question whether the properties of the observed latitude-time
diagram of sunspot occurence (the butterfly diagram) provide evidence for the
operation of a flux-transport dynamo, which explains the migration of the
sunspot zones and the period of the solar cycle in terms of a deep equatorward
meridional flow. We show that the properties of the butterfly diagram are
equally well reproduced by a conventional dynamo model with migrating dynamo
waves, but without transport of magnetic flux by a flow. These properties seem
to be generic for an oscillatory and migratory field of dipole parity and thus
do not permit an observational distinction between different dynamo approaches.Comment: 4 pages, 1 figur
Compact Gas Turbine Sub-Project - TC 4.2 Compact, High Overall Pressure Ratio (OPR 50+) Gas Generator
This is an overview of the technical challenges, objectives, and approaches to enable compact, high overall pressure
ratio gas turbine engine in support of NASA N+3 goals
Laser anemometer measurements in a transonic axial-flow fan rotor
Laser anemometer surveys were made of the 3-D flow field in NASA rotor 67, a low aspect ratio transonic axial-flow fan rotor. The test rotor has a tip relative Mach number of 1.38. The flowfield was surveyed at design speed at near peak efficiency and near stall operating conditions. Data is presented in the form of relative Mach number and relative flow angle distributions on surfaces of revolution at nine spanwise locations evenly spaced from hub to tip. At each spanwise location, data was acquired upstream, within, and downstream of the rotor. Aerodynamic performance measurements and detailed rotor blade and annulus geometry are also presented so that the experimental results can be used as a test case for 3-D turbomachinery flow analysis codes
Measurement of Synchrotron x-ray energies and line shapes using diffraction markers
Standard reference markers for accurate, reproducible synchrotron x-ray energies are obtained using a three Si crystal spectrometer. The first two crystals are in the monochromator and the third is used to obtain diffraction markers which monitor the energy. Then for any value of the glancing angle on the reference Si crystal the energy for the (333) diffraction must occur at 3/4 that of the (444) and 3/5 of that for the (555). This establishes for the first time an absolute synchrotron energy scale. Higher-order diffractions are used to determine excitation line profiles. We conclude that the use of reference diffractions is necessary to measure reproducible x-ray energies and to analyze the incident photons\u27 line profile. The detection of diffractions near the edge of measurement and near the Cu edge will provide a fast secondary standard which will allow comparison of edge data between different laboratories. The diffraction profiles will allow the proper analysis of spectral line widths
Geomagnetic Activity Indicates Large Amplitude for Sunspot Cycle 24
The level of geomagnetic activity near the time of solar activity minimum has been shown to be a reliable indicator for the amplitude of the following solar activity maximum. The geomagnetic activity index aa can be split into two components: one associated with solar flares, prominence eruptions, and coronal mass ejections which follows the solar activity cycle and a second component associated with recurrent high speed solar wind streams which is out of phase with the solar activity cycle. This second component often peaks before solar activity minimum and has been one of the most reliable indicators for the amplitude of the following maximum. The size of the recent maximum in this second component indicates that solar activity cycle 24 will be much higher than average - similar in size to cycles 21 and 22
Design and performance of controlled-diffusion stator compared with original double-circular-arc stator
The capabilities of two stators, one with controlled-diffusion (CD) blade sections and one with double-circular-arc (DCA) blade sections, were compared. A CD stator was designed and tested that had the same chord length but half the blades of the DCA stator. The same fan rotor (tip speed, 429 m/sec; pressure ratio, 1.65) was used with each stator row. The design and analysis system is briefly described. The overall stage and rotor performances with each stator are compared, as are selected blade element data. The minimum overall efficiency decrement across the stator was approximately 1 percentage point greater with the CD balde sections than with the DCA blade sections
The Waldmeier Effect in Sunspot Cycles
We discuss two aspects of the Waldmeier Effect, namely (1) the rise times of
sunspot cycles are anti-correlated to their strengths (WE1) and (2) the rates
of rise of the cycles are correlated to their strengths (WE2). From analysis of
four different data sets we conclude that both WE1 and WE2 exist in all the
data sets. We study these effects theoretically by introducing suitable
stochastic fluctuations in our regular solar dynamo model.Comment: Magnetic Coupling between the Interior and Atmosphere of the Sun;
Astrophysics and Space Science Proceeding
Magnetic Flux Transport at the Solar Surface
After emerging to the solar surface, the Sun's magnetic field displays a
complex and intricate evolution. The evolution of the surface field is
important for several reasons. One is that the surface field, and its dynamics,
sets the boundary condition for the coronal and heliospheric magnetic fields.
Another is that the surface evolution gives us insight into the dynamo process.
In particular, it plays an essential role in the Babcock-Leighton model of the
solar dynamo. Describing this evolution is the aim of the surface flux
transport model. The model starts from the emergence of magnetic bipoles.
Thereafter, the model is based on the induction equation and the fact that
after emergence the magnetic field is observed to evolve as if it were purely
radial. The induction equation then describes how the surface flows --
differential rotation, meridional circulation, granular, supergranular flows,
and active region inflows -- determine the evolution of the field (now taken to
be purely radial). In this paper, we review the modeling of the various
processes that determine the evolution of the surface field. We restrict our
attention to their role in the surface flux transport model. We also discuss
the success of the model and some of the results that have been obtained using
this model.Comment: 39 pages, 15 figures, accepted for publication in Space Sci. Re
Population, sexual and reproductive health, rights and sustainable development: forging a common agenda.
This article suggests that sexual and reproductive health and rights activists seeking to influence the post-2015 international development paradigm must work with sustainable development advocates concerned with a range of issues, including climate change, environmental issues, and food and water security, and that a way of building bridges with these communities is to demonstrate how sexual and reproductive health and rights are relevant for these issues. An understanding of population dynamics, including urbanization and migration, as well as population growth, can help to clarify these links. This article therefore suggests that whether or not sexual and reproductive health and rights activists can overcome resistance to discussing "population", become more knowledgeable about other sustainable development issues, and work with others in those fields to advance the global sustainable development agenda are crucial questions for the coming months. The article also contends that it is possible to care about population dynamics (including ageing and problems faced by countries with a high proportion of young people) and care about human rights at the same time. It expresses concern that, if sexual and reproductive health and rights advocates do not participate in the population dynamics discourse, the field will be left free for those for whom respecting and protecting rights may be less of a priority
- …
