354 research outputs found
State of B\"uchi Complementation
Complementation of B\"uchi automata has been studied for over five decades
since the formalism was introduced in 1960. Known complementation constructions
can be classified into Ramsey-based, determinization-based, rank-based, and
slice-based approaches. Regarding the performance of these approaches, there
have been several complexity analyses but very few experimental results. What
especially lacks is a comparative experiment on all of the four approaches to
see how they perform in practice. In this paper, we review the four approaches,
propose several optimization heuristics, and perform comparative
experimentation on four representative constructions that are considered the
most efficient in each approach. The experimental results show that (1) the
determinization-based Safra-Piterman construction outperforms the other three
in producing smaller complements and finishing more tasks in the allocated time
and (2) the proposed heuristics substantially improve the Safra-Piterman and
the slice-based constructions.Comment: 28 pages, 4 figures, a preliminary version of this paper appeared in
the Proceedings of the 15th International Conference on Implementation and
Application of Automata (CIAA
Chalcogen Elements In Snow: Relation To Emission Source
We have measured the concentrations of S, Se, and Te in samples of 1986 snow and compared our results with those of earlier measurements. We were unable to find any earlier reports on Te in snow, but values of the Se/S concentration ratio in 1986 are about a factor of 6 lower than that in snow and glacial ice of 800 B.C. Measurements on intermediate samples demonstrate that most of the decline in the Se/S ratio occurred during the past 200 years, i.e., since the start of the Industrial Revolution. This temporal change in values of the Se/S ratio probably reflected a shift in the major emission sources—from natural processes such as volcanism and biomethylation to largescale combustion of fossil fuels. © 1988, American Chemical Society. All rights reserved
Developments in impact damage modeling for laminated composite structures
Damage tolerance is the most critical technical issue for composite fuselage structures studied in the Advanced Technology Composite Aircraft Structures (ATCAS) program. The objective here is to understand both the impact damage resistance and residual strength of the laminated composite fuselage structure. An understanding of the different damage mechanisms which occur during an impact event will support the selection of materials and structural configurations used in different fuselage quadrants and guide the development of analysis tools for predicting the residual strength of impacted laminates. Prediction of the damage state along with the knowledge of post-impact response to applied loads will allow for engineered stacking sequencies and structural configurations; intelligent decisions on repair requirements will also result
Optimal design of nonuniform FIR transmultiplexer using semi-infinite programming
This paper considers an optimum nonuniform FIR transmultiplexer design problem subject to specifications in the frequency domain. Our objective is to minimize the sum of the ripple energy for all the individual filters, subject to the specifications on amplitude and aliasing distortions, and to the passband and stopband specifications for the individual filters. This optimum nonuniform transmultiplexer design problem can be formulated as a quadratic semi-infinite programming problem. The dual parametrization algorithm is extended to this nonuniform transmultiplexer design problem. If the lengths of the filters are sufficiently long and the set of decimation integers is compatible, then a solution exists. Since the problem is formulated as a convex problem, if a solution exists, then the solution obtained is unique and the local solution is a global minimum
An e-Business Logistic Model in Taiwan
The current article develops a framework for an e-business logistic model in Taiwan. The model includes e-marketplace, logistic, organization, and informational systems factors. Data used for this research come from a survey of business groups, including marine and air carriers, terminal warehousing, custom brokers, shipping centers, and marine information service providers. Our study reveals relationships between essential variables for e-business trading in the logistic industry. These include organizational advantage and information technology, strategy and vision, consumer-directed service and planning, lower cost and high quality customer service, quick merchandise delivery and low inventory, and long-term development plans. Specifically, we found that the logistic industry in Taiwan ignores the details of purchasing procedure in e-marketplace operation, focusing more on actual merchandise delivery, consumer satisfaction, and downstream consumer service. In addition, the logistical industry in Taiwan also involves employee adjustment to the new environment, support from upper management, training and, application of information technology
Study of Thick CZT Detectors for X-ray and Gamma-Ray Astronomy
CdZnTe (CZT) is a wide bandgap II-VI semiconductor developed for the
spectroscopic detection of X-rays and {\gamma}-rays at room temperature. The
Swift Burst Alert Telescope is using an 5240 cm2 array of 2 mm thick CZT
detectors for the detection of 15-150 keV X-rays from Gamma-Ray Bursts. We
report on the systematic tests of thicker (\geq 0.5 cm) CZT detectors with
volumes between 2 cm3 and 4 cm3 which are potential detector choices for a
number of future X-ray telescopes that operate in the 10 keV to a few MeV
energy range. The detectors contacted in our laboratory achieve Full Width Half
Maximum energy resolutions of 2.7 keV (4.5%) at 59 keV, 3 keV (2.5%) at 122 keV
and 4 keV (0.6%) at 662 keV. The 59 keV and 122 keV energy resolutions are
among the world-best results for \geq 0.5 cm thick CZT detectors. We use the
data set to study trends of how the energy resolution depends on the detector
thickness and on the pixel pitch. Unfortunately, we do not find clear trends,
indicating that even for the extremely good energy resolutions reported here,
the achievable energy resolutions are largely determined by the properties of
individual crystals. Somewhat surprisingly, we achieve the reported results
without applying a correction of the anode signals for the depth of the
interaction. Measuring the interaction depths thus does not seem to be a
pre-requisite for achieving sub-1% energy resolutions at 662 keV.Comment: 15 pages, 11 figure
First-order magnetic and structural phase transitions in FeSeTe
We use bulk magnetic susceptibility, electronic specific heat, and neutron
scattering to study structural and magnetic phase transitions in FeSe%
Te. FeTe exhibits a first order phase transition near 67
K with a tetragonal to monoclinic structural transition and simultaneously
develops a collinear antiferromagnetic (AF) order responsible for the entropy
change across the transition. Systematic studies of FeSeTe system
reveal that the AF structure and lattice distortion in these materials are
different from those of FeAs-based pnictides. These results call into question
the conclusions of present density functional calculations, where
FeSeTe and FeAs-based pnictides are expected to have similar Fermi
surfaces and therefore the same spin-density-wave AF order.Comment: 5 pages, 3 figure
Approximate affine linear relationship between L1 norm objective functional values and L2 norm constraint bounds
For an optimization problem with an norm objective function subject to an norm inequality constraint, this paper shows that there is an approximately linear relationship between the norm objective functional values and the norm specifications. This relationship is verified through the use of random and real world industrial data. The obtained results can be employed for 1) estimating the norm output objective functional value without solving the optimization problem numerically; 2) providing an insight for defining the norm specification in which a simple method is proposed in this paper; and 3) testing whether the obtained solutions are the globally optimal solutions or not. These advantages are demonstrated via the use of random data
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