15,977 research outputs found
Classification by means of B-spline potential functions with applications to remote sensing
A method is presented for using B-splines as potential functions in the estimation of likelihood functions (probability density functions conditioned on pattern classes), or the resulting discriminant functions. The consistency of this technique is discussed. Experimental results of using the likelihood functions in the classification of remotely sensed data are given
Cryogenic thermal control technology summaries
A summarization and categorization is presented of the pertinent literature associated with cryogenic thermal control technology having potential application to in-orbit fluid transfer systems and/or associated space storage. Initially, a literature search was conducted to obtain pertinent documents for review. Reports determined to be of primary significance were summarized in detail. Each summary, where applicable, consists of; (1) report identification, (2) objective(s) of the work, (3) description of pertinent work performed, (4)major results, and (5) comments of the reviewer (GD/C). Specific areas covered are; (1) multilayer insulation of storage tanks with and without vacuum jacketing, (2) other insulation such as foams, shadow shields, microspheres, honeycomb, vent cooling and composites, (3) vacuum jacketed and composite fluid lines, and (4) low conductive tank supports and insulation penetrations. Reports which were reviewed and not summarized, along with reasons for not summarizing, are also listed
Classical Concepts in Quantum Programming
The rapid progress of computer technology has been accompanied by a
corresponding evolution of software development, from hardwired components and
binary machine code to high level programming languages, which allowed to
master the increasing hardware complexity and fully exploit its potential.
This paper investigates, how classical concepts like hardware abstraction,
hierarchical programs, data types, memory management, flow of control and
structured programming can be used in quantum computing. The experimental
language QCL will be introduced as an example, how elements like irreversible
functions, local variables and conditional branching, which have no direct
quantum counterparts, can be implemented, and how non-classical features like
the reversibility of unitary transformation or the non-observability of quantum
states can be accounted for within the framework of a procedural programming
language.Comment: 11 pages, 4 figures, software available from
http://tph.tuwien.ac.at/~oemer/qcl.html, submitted for QS2002 proceeding
Evaluation of active control technology for short haul aircraft
An evaluation of the economics of short-haul aircraft designed with active controls technology and low wing-loading to achieve short field performance with good ride quality is presented. Results indicate that for such a system incorporating gust load alleviation and augmented stability the direct operating cost is better than for aircraft without active controls
COMPTEL Observations of the Gamma-Ray Blazar PKS 1622-297
We report results of observations and analyses on the gamma-ray blazar PKS
1622-297, with emphasis on the COMPTEL data (0.75 - 30 MeV) collected between
April 1991 and November 1997. PKS 1622-297 was detected as a source of
gamma-rays by the EGRET experiment aboard CGRO in 1995 during a gamma-ray
outburst at energies above 100 MeV lasting for five weeks.
In this time period the blazar was significantly (~ 5.9 sigma) detected by
COMPTEL at 10-30 MeV. At lower COMPTEL energies the detection is marginal,
resulting in a hard MeV spectrum.
The combined COMPTEL/EGRET energy spectrum shows a break at MeV energies. The
broad-band spectrum (radio - gamma-rays) shows that the gamma-ray emission
dominates the overall power output. On top of the 5-week gamma-ray outburst,
EGRET detected a huge flare lasting for > 1 day. Enhanced MeV emission (10 - 30
MeV) is found near the time of this flare, suggesting a possible time delay
with respect to the emission above 100 MeV. Outside the 5-week flaring period
in 1995, we do not detect MeV emission from PKS 1622-297.Comment: 10 pages including 9 figures, accepted for publication in A&
Quantum cryptography with squeezed states
A quantum key distribution scheme based on the use of displaced squeezed
vacuum states is presented. The states are squeezed in one of two field
quadrature components, and the value of the squeezed component is used to
encode a character from an alphabet. The uncertainty relation between
quadrature components prevents an eavesdropper from determining both with
enough precision to determine the character being sent. Losses degrade the
performance of this scheme, but it is possible to use phase-sensitive
amplifiers to boost the signal and partially compensate for their effect.Comment: 15 pages, no figure
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