2,118 research outputs found
The Civil War Gulf Blockade: The Unpublished Journal of a U.S. Navy Warrant Officer Aboard the USS Vincennes, 1861-1864
âThis paper attempts to (1) describe the unpublished journal of Nicholas Lynch, Warrant Officer (Sailmaker), U.S. Navy; (2) expand upon the most remarkable incident in the journal, the Affair at the Passes of the Mississippi River, a minor disaster for the Union navy in the first year of the war; (3) discuss the thoughts and moods of Sailmaker Lynch during the Union blockade from 1861 through 1864. The journal offers rare insights about naval warfare from the point of view of a sailor of the line. It also reveals that officers and crew were unable to maintain discipline and esprit de corps when faced with years of monotony and inaction on blockade duty aboard a sailing vessel.ââIntroduction to article
Book Reviews: If by Sea: The Forging of the American NavyâFrom the American Revolution to the War of 1812; The Age of the Ship of the Line: The British & French Navies, 1650-1815; Six Frigates: The Epic History of the Founding of the U.S. Navy
This document is Dr. Oxley\u27s review of three books: If by Sea: The Forging of the American Navy--From the American Revolution to the War of 1812, by George C. Daughan. Basic Books, 2008. 563 pp. Maps, glossary, notes, bibliography, index. ISBN 978-0-465-01607-5 30; The Age of the Ship of the Line: The British & French Navies, 1650-1815, by Jonathan R. Dull. University of Nebraska Press, 2009. 260 pp. Maps, diagrams, notes, index. ISBN 978-0-8032-1930-4 29.95; and Six Frigates: The Epic History of the Founding of the U.S. Navy, by Ian W. Toll. W.W. Norton, 2006. 560 pp. Illustrations, chronology, notes, bibliography, index. ISBN 978-0-393-33032-8 $16.9
Novel thermal management of power electronic devices: high power high frequency planar gunn diodes
Thermal management of next generation of semiconductor devices is becoming more challenging, as the device power
increases and device dimensions decrease. The work is addressing novel thermal measurement and management for
planar heterostructure Gunn diodes, which will be of strategic importance for UK technology and industry
Dark energy records in lensed cosmic microwave background
We consider the weak lensing effect induced by linear cosmological
perturbations on the cosmic microwave background (CMB) polarization
anisotropies. We find that the amplitude of the lensing peak in the BB mode
power spectrum is a faithful tracer of the dark energy dynamics at the onset of
cosmic acceleration. This is due to two reasons. First, the lensing power is
non-zero only at intermediate redshifts between the observer and the source,
keeping record of the linear perturbation growth rate at the corresponding
epoch. Second, the BB lensing signal is expected to dominate over the other
sources. The lensing distortion on the TT and EE spectra do exhibit a similar
dependence on the dark energy dynamics, although those are dominated by primary
anisotropies. We investigate and quantify the effect by means of exact tracking
quintessence models, as well as parameterizing the dark energy equation of
state in terms of the present value () and its asymptotic value in the
past (); in the interval allowed by the present constraints on dark
energy, the variation of induces a significant change in the BB
mode lensing amplitude. A Fisher matrix analysis, under conservative
assumptions concerning the increase of the sample variance due to the lensing
non-Gaussian statistics, shows that a precision of order 10% on both
and is achievable by the future experiments probing a large sky
area with angular resolution and sensitivity appropriate to detect the lensing
effect on the CMB angular power spectrum. These results show that the CMB can
probe the differential redshift behavior of the dark energy equation of state,
beyond its average.Comment: New version including substantial text change, three more figures and
two more table
A Millimeter-Wave Achromatic Half Wave Plate
We have constructed an achromatic half wave plate (AHWP) suitable for the
millimeter wavelength band. The AHWP was made from a stack of three sapphire
a-cut birefringent plates with the optical axes of the middle plate rotated by
50.5 degrees with respect to the aligned axes of the other plates. The measured
modulation efficiency of the AHWP at 110 GHz was %. In contrast,
the modulation efficiency of a single sapphire plate of the same thickness was
%. Both results are in close agreement with theoretical predictions.
The modulation efficiency of the AHWP was constant as a function of incidence
angles between 0 and 15 degrees. We discuss design parameters of an AHWP in the
context of astrophysical broad band polarimetry at the millimeter wavelength
band.Comment: In print - Applied Optics, 14 pages, 7 figure
On Local Equivalence, Surface Code States and Matroids
Recently, Ji et al disproved the LU-LC conjecture and showed that the local
unitary and local Clifford equivalence classes of the stabilizer states are not
always the same. Despite the fact this settles the LU-LC conjecture, a
sufficient condition for stabilizer states that violate the LU-LC conjecture is
missing. In this paper, we investigate further the properties of stabilizer
states with respect to local equivalence. Our first result shows that there
exist infinitely many stabilizer states which violate the LU-LC conjecture. In
particular, we show that for all numbers of qubits , there exist
distance two stabilizer states which are counterexamples to the LU-LC
conjecture. We prove that for all odd , there exist stabilizer
states with distance greater than two which are LU equivalent but not LC
equivalent. Two important classes of stabilizer states that are of great
interest in quantum computation are the cluster states and stabilizer states of
the surface codes. To date, the status of these states with respect to the
LU-LC conjecture was not studied. We show that, under some minimal
restrictions, both these classes of states preclude any counterexamples. In
this context, we also show that the associated surface codes do not have any
encoded non-Clifford transversal gates. We characterize the CSS surface code
states in terms of a class of minor closed binary matroids. In addition to
making connection with an important open problem in binary matroid theory, this
characterization does in some cases provide an efficient test for CSS states
that are not counterexamples.Comment: LaTeX, 13 pages; Revised introduction, minor changes and corrections
mainly in section V
Preliminary report on the analysis of the stresses in a die-bolster combination
An analysis is presented of the stresses in a carbide die-steel
bolster combination. Results from a computer treatment of this analysis
are given in tabular and graphical form. Suggestions are made as to the
choice of interface diameters, and a nomogram is drawn enabling the maximum
allowable interference to be selected
Thermal profiles within the channel of planar gunn diodes using micro-particle sensors
The paper describes the use of a novel microparticle sensor (~3 ÎŒm diameter) and infra-red (IR) microscopy to measure the temperature profile within the active channel (typically 3 ÎŒm length and 120 ÎŒm width) of planar Gunn diodes. The method has enabled detailed temperature measurements showing an asymmetrical temperature profile along the active width of these devices. The asymmetrical temperature profile suggests a similar behaviour in the channel current density, which may contribute to the lower than expected RF output power
Calculating the shear angle in orthogonal metal cutting from fundamental stress-strain-strain rate properties of the work material
An analysis of the orthogonal metal cutting process is made which
enables the shear angle to be calculated from certain fundamental properties
of the work material and the specified cutting conditions. Shear angles
are calculated for a range of cutting conditions and good agreement is
shown between theory and experiment. In particular, such trends as the
decrease in shear angle with decrease in cutting speed and the tendency
for the chip to become discontinuous at slow cutting speeds which are found
experimentally and cannot be explained in terms of previous shear angle
analyses, are shown to be consistent with the present analysis
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