1,646 research outputs found
TOPYDE: A Tool for Physical Database Design
We describe a tool for physical database design based on a combination of theoretical and pragmatic approaches. The tool takes as input a relational schema, the workload defined on the schema, and some additional database characteristics and produces as output a physical schema. For the time being, the tool is tuned towards Ingres
On the Selection of Optimal Index Configuration in OO Databases
An operation in object-oriented databases gives rise to the processing of a path. Several database operations may result into the same path. The authors address the problem of optimal index configuration for a single path. As it is shown an optimal index configuration for a path can be achieved by splitting the path into subpaths and by indexing each subpath with the optimal index organization. The authors present an algorithm which is able to select an optimal index configuration for a given path. The authors consider a limited number of existing indexing techniques (simple index, inherited index, nested inherited index, multi-index, and multi-inherited index) but the principles of the algorithm remain the same adding more indexing technique
A new representation of emotion in affective computing
In the recent years, increasing attention has been paid to the area of affective computing, which deals with the complex phenomenon of human emotion. Therefore, a model for describing, structuring, and categorizing emotional states of users is required. The dimensional emotion theory is one of widely used theoretical foundations for categorization of emotions. According to the dimensional theory, emotional states are projected to the affective space, which has two dimensions: valence and arousal. In order to navigate in the affective space, Cartesian coordinate system is used, where emotion quality is defined by combination of valence and arousal. In this paper, we propose another representation of the affective space with polar coordinate system. The key advantages of such a representation include (1) capability to account not only for emotion quality, but also for emotion intensity, (2) reasonable explanation of the location of neutral emotion in the affective space, and (3) straightforward interpretation of the meaning of an emotional state (quality defined by angle and intensity defined by distance from the origin). Although in our experiment most of the induced motions can be differentiated with polar coordinate system, further investigation is still needed to find out either Cartesian or polar coordinates system represents affective space better in practice
Real-time N-finder processing algorithms for hyperspectral imagery
N-finder algorithm (N-FINDR) is probably one of most popular and widely used algorithms for endmember extraction in hyperspectral imagery. When it comes to practical implementation, four major obstacles need to be overcome. One is the number of endmembers which must be known a priori. A second one is the use of random initial endmembers to initialize N-FINDR, which generally results in different sets of final extracted endmembers. Consequently, the results are inconsistent and not reproducible. A third one is requirement of dimensionality reduction (DR) where different used DR techniques produce different results. Finally yet importantly, it is the very expensive computational cost caused by an exhaustive search for endmembers all together simultaneously. This paper re-designs N-FINDR in a real time processing fashion to cope with these issues. Four versions of Real Time (RT) N-FINDR are developed, RT Iterative N-FINDR (RT IN-FINDR), RT SeQuential N-FINDR (RT SQ N-FINDR), RT Circular N-FINDR, RT SuCcessive N-FINDR (RT SC N-FINDR), each of which has its own merit for implementation. Experimental results demonstrate that real time processing algorithms perform as well as their counterparts with no real-time processing
B_c meson rare decays in the light-cone quark model
We investigate the rare decays
and in the framework of the
light-cone quark model (LCQM). The transition form factors are calculated in
the space-like region and then analytically continued to the time-like region
via exponential parametrization. The branching ratios and longitudinal lepton
polarization asymmetries (LPAs) for the two decays are given and compared with
each other. The results are helpful to investigating the structure of
meson and to testing the unitarity of CKM quark mixing matrix. All these
results can be tested in the future experiments at the LHC.Comment: 9 pages, 11 figures, version accepted for publication in EPJ
Search for Solar Axions Produced in the Reaction
A search for the axioelectric absorption of 5.5-MeV solar axions produced in
the reaction was performed with
two BGO detectors placed inside a low-background setup. A model independent
limit on axion-photon and axion-nucleon couplings was obtained: . Constraints on the axion-electron
coupling constant were obtained for axions with masses in the MeV
range: . The solar positron flux from
decay was determined for axions with masses . Using the existing experimental data on the interplanetary positron
flux, a new constraint on the axion-electron coupling constant for axions with
masses in the MeV range was obtained: .Comment: 6 pages, 5 figure
Coulomb Effects on Electromagnetic Pair Production in Ultrarelativistic Heavy-Ion Collisions
We discuss the implications of the eikonal amplitude on the pair production
probability in ultrarelativistic heavy-ion transits. In this context the
Weizs\"acker-Williams method is shown to be exact in the ultrarelativistic
limit, irrespective of the produced particles' mass. A new equivalent
single-photon distribution is derived which correctly accounts for the Coulomb
distortions. As an immediate application, consequences for unitarity violation
in photo-dissociation processes in peripheral heavy-ion encounters are
discussed.Comment: 13 pages, 4 .eps figure
Granular discharge and clogging for tilted hoppers
We measure the flux of spherical glass beads through a hole as a systematic
function of both tilt angle and hole diameter, for two different size beads.
The discharge increases with hole diameter in accord with the Beverloo relation
for both horizontal and vertical holes, but in the latter case with a larger
small-hole cutoff. For large holes the flux decreases linearly in cosine of the
tilt angle, vanishing smoothly somewhat below the angle of repose. For small
holes it vanishes abruptly at a smaller angle. The conditions for zero flux are
discussed in the context of a {\it clogging phase diagram} of flow state vs
tilt angle and ratio of hole to grain size
Thin helium film on a glass substrate
We investigate by Monte Carlo simulations the structure, energetics and
superfluid properties of thin helium-four films (up to four layers) on a glass
substrate, at low temperature. The first adsorbed layer is found to be solid
and "inert", i.e., atoms are localized and do not participate to quantum
exchanges. Additional layers are liquid, with no clear layer separation above
the second one. It is found that a single helium-three impurity resides on the
outmost layer, not significantly further away from the substrate than
helium-four atoms on the same layer.Comment: Six figures, submitted for publication to the Journal of Low
Temperature Physic
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