11,876 research outputs found
Application of dielectric constant measurements to radar imagery interpretation
The author has identified the following significant results. Although it is readily recognized that there is a need for ground truth to provide adequate guidance for remote sensing data interpretation, it is noted that, in terms of radar remote sensing, this ground truth is often inadequate. It is necessary to make basic electrical and physical measurements of the surface and to some depth below it. A brief outline is presented of a ground truth scheme which uses measurements of the dielectric constant. Two portable instruments were designed specifically for this purpose; these were: (1) a Q-meter for measurement of dielectric constant and loss tangent; and (2) an instrument to measure electrical properties of the two operating frequencies of the imaging radar. Although extensive data are lacking, several general cases of radar-earth surface and interaction are described; also, examples of radar imagery and some data on ice and snow are presented. It is concluded that the next logical step is to begin to quantify the radar ground truth in preparation for machine interpretation and automatic data processing of the radar imagery
Unequal arm space-borne gravitational wave detectors
Unlike ground-based interferometric gravitational wave detectors, large
space-based systems will not be rigid structures. When the end-stations of the
laser interferometer are freely flying spacecraft, the armlengths will change
due to variations in the spacecraft positions along their orbital trajectories,
so the precise equality of the arms that is required in a laboratory
interferometer to cancel laser phase noise is not possible. However, using a
method discovered by Tinto and Armstrong, a signal can be constructed in which
laser phase noise exactly cancels out, even in an unequal arm interferometer.
We examine the case where the ratio of the armlengths is a variable parameter,
and compute the averaged gravitational wave transfer function as a function of
that parameter. Example sensitivity curve calculations are presented for the
expected design parameters of the proposed LISA interferometer, comparing it to
a similar instrument with one arm shortened by a factor of 100, showing how the
ratio of the armlengths will affect the overall sensitivity of the instrument.Comment: 14 pages, 7 figures, REVTeX
Hands-on Gravitational Wave Astronomy: Extracting astrophysical information from simulated signals
In this paper we introduce a hands-on activity in which introductory
astronomy students act as gravitational wave astronomers by extracting
information from simulated gravitational wave signals. The process mimics the
way true gravitational wave analysis will be handled by using plots of a pure
gravitational wave signal. The students directly measure the properties of the
simulated signal, and use these measurements to evaluate standard formulae for
astrophysical source parameters. An exercise based on the discussion in this
paper has been written and made publicly available online for use in
introductory laboratory courses.Comment: 5 pages, 4 figures; submitted to Am. J. Phy
Loading of bosons in optical lattices into the p band
We present a method for transferring bosonic atoms residing on the lowest
s-band of an optical lattice to the first excited p-bands. Our idea hinges on
resonant tunneling between adjacent sites of accelerated lattices. The
acceleration effectively shifts the quasi-bound energies on each site such that
the system can be cast into a Wannier-Stark ladder problem. By adjusting the
acceleration constant, a situation of resonant tunneling between the s- and
p-bands is achievable. Within a mean-field model, considering 87Rb atoms, we
demonstrate population transfer from the s- to the p-bands with around 95 %
efficiency. Nonlinear effects deriving from atom-atom interactions, as well as
coupling of the quasi bound Wannier-Stark states to the continuum, are
considered.Comment: 8 pages, 7 figure
CRIMINAL LAW-PROCEDURE-RIGHT OF DEFENDANT TO INSPECT GRAND JURY MINUTES
Defendant was indicted for murder by a grand jury. The trial court denied a motion by defendant requesting that the district attorney be ordered to furnish him with a transcript of the evidence offered before the grand jury. On appeal, held, affirmed. It was within the discretion of the trial court to grant or refuse the motion. Commonwealth v. Galvin, (Mass. 1948) 80 N.E. (2d) 825
AGENCY-LIABILITY OF EMPLOYER FOR EMPLOYEE\u27S INTENTIONAL TORTS
Plaintiff, a spectator occupying a front seat at a hockey game, was struck and injured by one of the players who was attempting to strike an opponent. Beyond the fact that a hockey game was in progress, there was nothing to indicate the player\u27s motive. Plaintiff recovered judgment against appellant, the corporation that employed the player who had struck her. The lower court instructed the jury that the player who had struck the plaintiff was as a matter of law acting as a servant, agent, or employee and within the scope of his employment at the time the plaintiff was injured. On appeal, held, reversed. The question of whether or not the blow was struck within the scope of the player\u27s employment should have been submitted to the jury. M. J. Uline Co. v. Cashdan, (App. D.C. 1948) 171 F. (2d) 132
CORPORATIONS-BLUE SKY LAWS-LIABILITY OF OFFICERS AND DIRECTORS OF CORPORATION FOR VIOLATION
Plaintiff sued a corporation and its president to recover money paid for purchase of stock sold in violation of the \u27\u27blue sky laws of Michigan. The president, through correspondence, had induced plaintiff to complete the purchase. Plaintiff had judgment below against both defendants. The president alone appealed, contending among other things that he was not an agent within the meaning of the statute. Held, affirmed. The word agent in the Michigan statute1 includes officers and directors of the corporation whether they are authorized agents or are holding themselves out as agents of the corporation. Cleland v. Smart, 321 Mich. 46, 32 N.W. (2d) 42 (1948)
PRACTICES USED BY DAIRY FARMERS TO REDUCE SEASONAL PRODUCTION VARIABILITY
Results of this study further support the effectiveness of the seasonal pricing plan in reducing seasonal production variability. Florida Dairy farmers were able to change factors that affect production in order to take advantage of the seasonal pricing plan and that farmers that chose not to participate were able to affect factors to increase production seasonality.seasonality, Demand and Price Analysis, Livestock Production/Industries,
Elimination of Clock Jitter Noise in Spaceborn Laser Interferometers
Space gravitational wave detectors employing laser interferometry between
free-flying spacecraft differ in many ways from their laboratory counterparts.
Among these differences is the fact that, in space, the end-masses will be
moving relative to each other. This creates a problem by inducing a Doppler
shift between the incoming and outgoing frequencies. The resulting beat
frequency is so high that its phase cannot be read to sufficient accuracy when
referenced to state-of-the-art space-qualified clocks. This is the problem that
is addressed in this paper. We introduce a set of time-domain algorithms in
which the effects of clock jitter are exactly canceled. The method employs the
two-color laser approach that has been previously proposed, but avoids the
singularities that arise in the previous frequency-domain algorithms. In
addition, several practical aspects of the laser and clock noise cancellation
schemes are addressed.Comment: 20 pages, 5 figure
The Angular Resolution of Space-Based Gravitational Wave Detectors
Proposed space-based gravitational wave antennas involve satellites arrayed
either in an equilateral triangle around the earth in the ecliptic plane (the
ecliptic-plane option) or in an equilateral triangle orbiting the sun in such a
way that the plane of the triangle is tilted at 60 degrees relative to the
ecliptic (the precessing-plane option). In this paper, we explore the angular
resolution of these two classes of detectors for two kinds of sources
(essentially monochromatic compact binaries and coalescing massive-black-hole
binaries) using time-domain expressions for the gravitational waveform that are
accurate to 4/2 PN order. Our results display an interesting effect not
previously reported in the literature, and underline the importance of
including the higher-order PN terms in the waveform when predicting the angular
resolution of ecliptic-plane detector arrays.Comment: 13 pages, 6 figures, submitted to Phys Rev D. The current version
corrects an error in our original paper and adds some clarifying language.
The error also required correction of the graphs now shown in Figures 3
through
- …