5,666 research outputs found
A method of automatically stabilizing helicopter sling loads
The effect of geometric and aerodynamic characteristics on the stability of the lateral degrees of freedom of a typical helicopter sling load is examined. The feasibility of stabilizing the suspended load by controllable fins was also studied. Linear control theory was applied to the design of a simple control law that stabilized the load over a wide range of helicopter airspeeds
Crystallization of random trigonometric polynomials
We give a precise measure of the rate at which repeated differentiation of a
random trigonometric polynomial causes the roots of the function to approach
equal spacing. This can be viewed as a toy model of crystallization in one
dimension. In particular we determine the asymptotics of the distribution of
the roots around the crystalline configuration and find that the distribution
is not Gaussian.Comment: 10 pages, 3 figure
How Do You Qualify as a Whistleblower Under The Dodd-Frank Act? Blowing the Whistle on a Circuit Split
       Recently, a circuit split has arisen with regard to the Dodd-Frank Wall Street Reform and Consumer Protection Act. The circuit split concerns the question of what it takes for an individual to qualify as a âwhistleblowerâ under the terms of the statute. This circuit split is surprising, as the Dodd- Frank Act purports to answer this question itself by providing a definition of this term, a definition which the Fifth Circuit has treated as being conclusive. Nonetheless, the Second and the Ninth Circuits have held that with respect to some, but not all, of the Dodd-Frank Act, this statutory âwhistleblowerâ definition does not apply. Shortly, the Supreme Court will have the opportunity to resolve the matter when it hears an appeal of the Ninth Circuitâs decision in Somers v. Digital Realty Trust Inc. This article provides three broad reasons why the Supreme Court should reject the Second and Ninth Circuitsâ interpretations. First, the interpretation endorsed by the Second and Ninth Circuits is the result of a flawed exercise in statutory interpretation that incorrectly applies principles recently set down by the Supreme Court in King v. Burwell, and Utility Air Regulatory Group v. EPA. Secondly, while the Second and Ninth Circuits rejected the Fifth Circuitsâ interpretation on the basis that it withholds the protection of the Dodd-Frank Act from auditors and attorneys, the Second and Ninth Circuitsâ preferred interpretations also fail to protect auditors and attorneys. Finally, the policy reasons in favor of extending the Dodd-Frank Actâs whistleblower protections to auditors and attorneys are insufficiently strong to warrant departing from the natural meaning of the statutory language at issue. Â
Studies on the development of butter cultures from mixtures of organisms
Studies on the bacteriology of butter cultures have shown that two types of bacteria are normally present, one which attacks primarily the lactose with the formation of large amounts of lactic acid, while the other is characterized by its production of volatile acid from citric acid. These findings suggest the development of butter cultures under carefully controlled conditions by making mixtures of the two types of organisms. While many satisfactory butter cultures have been secured with this procedure, mixtures made with organisms that appear typical on the basis of morphology, cultural characteristics and the usual biochemical tests, often fail to develop a satisfactory aroma and flavor and, accordingly, the percentage of the attempts that are successful is small
Distribution of parallel vortices studied by spin-polarized neutron reflectivity and magnetization
We present the studies of non-uniformly distributed vortices in Nb/Al
multilayers at applied field near parallel to film surface by using
spin-polarized neutron reflectivity (SPNR) and DC magnetization measurements.
We have observed peaks above the lower critical field, Hc1, in the M-H curves
from the multilayers.
Previous works with a model calculation of minimizing Gibbs free energy have
suggested that the peaks could be ascribed to vortex line transitions for
spatial commensuration in a thin film superconductor. In order to directly
determine the distribution of vortices, we performed SPNR measurements on the
multilayer and found that the distribution and density of vortices are
different at ascending and descending fields. At ascending 2000 Oe which is
just below the first peak in the M-H curve, SPNR shows that vortices are mostly
localized near a middle line of the film meanwhile the vortices are distributed
in broader region at the descending 2000 Oe. That is related to the observation
of more vortices trapped at the descending field. As the applied field is
sightly tilted (< 3.5degree), we observe another peak at a smaller field. The
peak position is consistent with the parallel lower critical field (Hc1||). We
discuss that the vortices run along the applied field below Hc1|| and rotate
parallel to the surface at Hc1||.Comment: 17 pages, 9 figure
Random polynomials, random matrices, and -functions
We show that the Circular Orthogonal Ensemble of random matrices arises
naturally from a family of random polynomials. This sheds light on the
appearance of random matrix statistics in the zeros of the Riemann
zeta-function.Comment: Added background material. Final version. To appear in Nonlinearit
Premise Selection and External Provers for HOL4
Learning-assisted automated reasoning has recently gained popularity among
the users of Isabelle/HOL, HOL Light, and Mizar. In this paper, we present an
add-on to the HOL4 proof assistant and an adaptation of the HOLyHammer system
that provides machine learning-based premise selection and automated reasoning
also for HOL4. We efficiently record the HOL4 dependencies and extract features
from the theorem statements, which form a basis for premise selection.
HOLyHammer transforms the HOL4 statements in the various TPTP-ATP proof
formats, which are then processed by the ATPs. We discuss the different
evaluation settings: ATPs, accessible lemmas, and premise numbers. We measure
the performance of HOLyHammer on the HOL4 standard library. The results are
combined accordingly and compared with the HOL Light experiments, showing a
comparably high quality of predictions. The system directly benefits HOL4 users
by automatically finding proofs dependencies that can be reconstructed by
Metis
Plasma density measurements using chirped pulse broad-band Raman amplification
Stimulated Raman backscattering is used as a non-destructive method to determine the density of plasma media at localized positions in space and time. By colliding two counter-propagating, ultra-short laser pulses with a spectral bandwidth larger than twice the plasma frequency, amplification occurs at the Stokes wavelengths, which results in regions of gain and loss separated by twice the plasma frequency, from which the plasma density can be deduced. By varying the relative delay between the laser pulses, and therefore the position and timing of the interaction, the spatio-temporal distribution of the plasma density can be mapped out
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