79,833 research outputs found
Amorphous-silicon module hot-spot testing
Hot spot heating occurs when cell short-circuit current is lower than string operating current. Amorphous cell hot spot are tested to develop the techniques required for performing reverse bias testing of amorphous cells. Also, to quantify the response of amorphous cells to reverse biasing. Guidelines are developed from testing for reducing hot spot susceptibility of amorphous modules and to develop a qualification test for hot spot testing of amorphous modules. It is concluded that amorphous cells undergo hot spot heating similarly to crystalline cells. Comparison of results obtained with submodules versus actual modules indicate heating levels lower in actual modules. Module design must address hot spot testing and hot spot qualification test conducted on modules showed no instabilities and minor cell erosion
Are Stars with Planets Polluted?
We compare the metallicities of stars with radial velocity planets to the
metallicity of a sample of field dwarfs. We confirm recent work indicating that
the stars-with-planet sample as a whole is iron rich. However, the lowest mass
stars tend to be iron poor, with several having [Fe/H]<-0.2, demonstrating that
high metallicity is not required for the formation of short period Jupiter-mass
planets. We show that the average [Fe/H] increases with increasing stellar mass
(for masses below 1.25 solar masses) in both samples, but that the increase is
much more rapid in the stars-with-planet sample. The variation of metallicity
with stellar age also differs between the two samples. We examine possible
selection effects related to variations in the sensitivity of radial velocity
surveys with stellar mass and metallicity, and identify a color cutoff
(B-V>0.48) that contributes to but does not explain the mass-metallicity trend
in the stars-with-planets sample. We use Monte Carlo models to show that adding
an average of 6.5 Earth masses of iron to each star can explain both the
mass-metallicity and the age-metallicity relations of the stars-with-planets
sample. However, for at least one star, HD 38529, there is good evidence that
the bulk metallicity is high. We conclude that the observed metallicities and
metallicity trends are the result of the interaction of three effects;
accretion of about 6 Earth masses of iron rich material, selection effects, and
in some cases, high intrinsic metallicity.Comment: 19 pages 11 figure
Low-cost silicon solar array project environmental hail model for assessing risk to solar collectors
The probability of solar arrays being struck by hailstones of various sizes as a function of geographic location and service life was assessed. The study complements parallel studies of solar array sensitivity to hail damage, the final objective being an estimate of the most cost effective level for solar array hail protection
UV-T-RH combined environmental testing
A combined environmental aging chamber was developed at the Jet Propulsion Laboratory (JPL). The chamber has an ultraviolet (UV) light source that can be varied between 1 to 2 suns, temperature control from -40 to +175 C, and adjustable humidity. Results from two initial aging experiments (Tedlar and amorphous silicon colar cells) were presented
Neutrino Masses and Mixing: Where We Stand and Where We are Going
In this talk I review our present knowledge on neutrino masses and mixing as
well as the expectations from near future experiments.Comment: 19 Pages, 11 figures. Review talk given at the 10th International
Conference on Supersymmetry and Unification of Fundamental Interactions,
SUSY02 (June 17-23, 2002, DESY, Hamburg
Present Bounds on New Neutral Vector Resonances from Electroweak Gauge Boson Pair Production at the LHC
Several extensions of the Standard Model predict the existence of new neutral
spin-1 resonances associated to the electroweak symmetry breaking sector. Using
the data from ATLAS (with integrated luminosity of L=1.02 fb^{-1}) and CMS
(with integrated luminosity of L=1.55 fb^{-1}) on the production of W+W- pairs
through the process pp -> l^+ l^{\prime -} \sla{E}_T, we place model
independent bounds on these new vector resonances masses, couplings and widths.
Our analyses show that the present data excludes new neutral vector resonances
with masses up to 1-2.3 TeV depending on their couplings and widths. We also
demonstrate how to extend our analysis framework to different models working a
specific example.Comment: 10 pages, 6 figure
Non-reciprocal few-photon devices based on chiral waveguide-emitter couplings
We demonstrate the possibility of designing efficient, non reciprocal
few-photon devices by exploiting the chiral coupling between two waveguide
modes and a single quantum emitter. We show how this system can induce
non-reciprocal photon transport at the single-photon level and act as an
optical diode. Afterwards, we also show how the same system shows a
transistor-like behaviour for a two-photon input. The efficiency in both cases
is shown to be large for feasible experimental implementations. Our results
illustrate the potential of chiral waveguide-emitter couplings for applications
in quantum circuitry.Comment: Mathematica notebook attached for calculation of detection
probabilitie
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