9,409 research outputs found
An Investigation of the Characteristics of Steel Diaphragms for Automatic Fuel-Injection Valves
This research on steel diaphragms was undertaken at the Langley Memorial Aeronautical Laboratory, as a part of a general investigation on fuel injection engines for aircraft. The work determined the load-deflection, load- deformation and hysteresis characteristics for single diaphragms having thicknesses from 0.00s inch to 0.012 inch, and for similar diaphragms tested in multiple having total thicknesses from 0.012 inch to 0.180 inch. The elastic limit loads and deflections, and rupture points of single diaphragms were also determined. Some work was done on diaphragms having central orifices in order to determine the effect of orifice diameter upon the load deflection characteristics
An Impulse Electric Motor for Driving Recording Instruments
The chief purpose in undertaking the development of this synchronous motor was the creation of a very small, compact power source, capable of driving the film drums of the recording aircraft instruments designed by the staff of the National Advisory Committee for Aeronautics
Effi cient Specialization in Ricardian Production
It is well known that the analysis of efficient specialization in Ricardian production with many countries and many commodities cannot be broken down to the simple case of two countries and two commodities. By drawing on some recent results of convex geometry and the theory of cephoids, this paper characterizes efficient patterns of incomplete specialization in the general case.Ricardian trade; efficient specialization; comparative cost; cephoids; deGua simplexes
Why don't households see the light? Explaining the diffusion of compact fluorescent lamps
Many countries are currently considering bans on incandescent light bulbs and other policies to enhance the residential diffusion of energy-saving compact fluorescent lamps (CFLs). However the reasons for currently limited diffusion of CFLs are largely unknown. This paper employs a Double Hurdle model to identify distinct barriers to household consideration of CFLs and the subsequent intensity of adoption using a large survey of German households. The results reveal that barriers to CFL consideration are low for all, except households with very low incomes. Further, barriers to CFL consideration are strongly linked to the characteristics of the residences of low-income households. Thus, the greatest potential for increasing the diffusion of CFLs lies not in addressing barriers to consideration, but in augmenting the intensity of household adoption particularly within high income groups. --
Disentangling Flavor Violation in the Top-Higgs Sector at the LHC
We study the LHC phenomenology of flavor changing Yukawa couplings between
top quark, Higgs boson, and either an up or charm quark. Such or
couplings arise for instance in models in which Higgs sector is extended by the
existence of additional Higgs bosons or by higher dimensional operators. We
emphasize the importance of anomalous single top plus Higgs production in these
scenarios, in addition to the more widely studied decays. By
recasting existing CMS searches in multilepton and diphoton plus lepton final
states, we show that bounds on couplings are improved by a factor of 1.5
when single top plus Higgs production is accounted for. We also recast the CMS
search for vector boson plus Higgs production into new, competitive constraints
on and couplings, setting the limits of and
. We then investigate the sensitivity of future searches in
multilepton channel and in fully hadronic channel. In multilepton searches,
studying the lepton rapidity distributions and charge assignments can be used
to discriminate between couplings, for which anomalous single top
production is relevant, and couplings, for which it is suppressed by the
parton distribution function of the charm quark. An analysis of fully hadronic
production and decay can be competitive with the multilepton
search at 100 fb of 13 TeV data if jet substructure techniques are
employed to reconstruct boosted top quarks and Higgs bosons. To show this we
develop a modified version of the HEPTopTagger algorithm, optimized for tagging
decays. Our sensitivity estimates on ()
at 100 fb of 13 TeV data for multilepton searches, vector boson plus
Higgs search and fully hadronic search are (), ()
and (), respectively.Comment: Version published in JHE
Clonal selection prevents tragedy of the commons when neighbors compete in a rock-paper-scissors game
The rock-paper-scissors game is a model example of the on-going cyclic
turnover typical of many ecosystems, ranging from the terrestrial and aquatic
to the microbial. Here we explore the evolution of a rock-paper-scissors system
where three species compete for space. The species are allowed to mutate and
change the speed by which they invade one another. In the case when all species
have similar mutation rates, we observe a perpetual arms race where no single
species prevails. When only two species mutate, their aggressions increase
indefinitely until the ecosystem collapses and only the non-mutating species
survives. Finally we show that when only one species mutates, group selection
removes individual predators with the fastest growth rates, causing the growth
rate of the species to stabilize. We explain this group selection
quantitatively.Comment: 4 pages, 4 figure
Parabolic equations with dynamical boundary conditions and source terms on interfaces
We consider parabolic equations with mixed boundary conditions and domain
inhomogeneities supported on a lower dimensional hypersurface, enforcing a jump
in the conormal derivative. Only minimal regularity assumptions on the domain
and the coefficients are imposed. It is shown that the corresponding linear
operator enjoys maximal parabolic regularity in a suitable -setting. The
linear results suffice to treat also the corresponding nondegenerate
quasilinear problems.Comment: 30 pages. Revised version. To appear in Annali di Matematica Pura ed
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