3,181 research outputs found
Approximations from Anywhere and General Rough Sets
Not all approximations arise from information systems. The problem of fitting
approximations, subjected to some rules (and related data), to information
systems in a rough scheme of things is known as the \emph{inverse problem}. The
inverse problem is more general than the duality (or abstract representation)
problems and was introduced by the present author in her earlier papers. From
the practical perspective, a few (as opposed to one) theoretical frameworks may
be suitable for formulating the problem itself. \emph{Granular operator spaces}
have been recently introduced and investigated by the present author in her
recent work in the context of antichain based and dialectical semantics for
general rough sets. The nature of the inverse problem is examined from
number-theoretic and combinatorial perspectives in a higher order variant of
granular operator spaces and some necessary conditions are proved. The results
and the novel approach would be useful in a number of unsupervised and semi
supervised learning contexts and algorithms.Comment: 20 Pages. Scheduled to appear in IJCRS'2017 LNCS Proceedings,
Springe
Photo-excited zero-resistance states in the GaAs/AlGaAs system
The microwave-excited high mobility two-dimensional electron system exhibits,
at liquid helium temperatures, vanishing resistance in the vicinity of , where , m is an
effective mass, e is the charge, and \textit{f} is the microwave frequency.
Here, we summarize some experimental results.Comment: 7 color figures, 5 page
Properties from relativistic coupled-cluster without truncation: hyperfine constants of , , and
We demonstrate an iterative scheme for coupled-cluster properties
calculations without truncating the dressed properties operator. For
validation, magnetic dipole hyperfine constants of alkaline Earth ions are
calculated with relativistic coupled-cluster and role of electron correlation
examined. Then, a detailed analysis of the higher order terms is carried out.
Based on the results, we arrive at an optimal form of the dressed operator.
Which we recommend for properties calculations with relativistic
coupled-cluster theory.Comment: 13 pages, 4 figures, 5 table
Radiation-induced magnetoresistance oscillations in two-dimensional electron systems under bichromatic irradiation
We analyze the magnetoresistance oscillations in high-mobility
two-dimensional electron systems induced by the combined driving of two
radiation fields of frequency and , based on the
balance-equation approach to magnetotransport for high-carrier-density systems
in Faraday geometry. It is shown that under bichromatic irradiation of
, most of the characterstic peak-valley pairs in the
curve of versus magnetic field in the case of monochromatic
irradiation of either or disappear, except the one around
or . oscillations
show up mainly as new peak-valley structures around other positions related to
multiple photon processes of mixing frequencies ,
, etc. Many minima of these resistance peak-valley pairs can
descend down to negative with enhancing radiation strength, indicating the
possible bichromaticzero-resistance states.Comment: 5 pages, 3 figures. Accepted for publication in Phys. Rev.
Using video games for volcanic hazard education and communication: An assessment of the method and preliminary results
This paper presents the findings from a study aimed at understanding whether video games (or serious games) can be effective in enhancing volcanic hazard education and communication. Using the eastern Caribbean island of St. Vincent, we have developed a video game – St. Vincent's Volcano-for use in existing volcano education and outreach sessions. Its twin aims are to improve residents' knowledge of potential future eruptive hazards (ash fall, pyroclastic flows and lahars) and to integrate traditional methods of education in a more interactive manner. Here, we discuss the process of game development including concept design through to the final implementation on St. Vincent. Preliminary results obtained from the final implementation (through pre-and post-test knowledge quizzes) for both student and adult participants provide indications that a video game of this style may be effective in improving a learner's knowledge. Both groups of participants demonstrated a post-test increase in their knowledge quiz score of 9.3% for adults and 8.3% for students and, when plotted as learning gains (Hake, 1998), show similar overall improvements (0.11 for adults and 0.09 for students). These preliminary findings may provide a sound foundation for the increased integration of emerging technologies within traditional education sessions. This paper also shares some of the challenges and lessons learnt throughout the development and testing processes and provides recommendations for researchers looking to pursue a similar study
In-field soil fertility assessment of Ramat Polytechnic farm Maiduguri in North-Eastern Nigeria
In-field soil fertility valuation is an important diagnostic tool for determining the nutrient needs of plants. The main objective was to determine soil chemical characteristics. Twenty samples covering 2.5 hectares of the farm from 0-30 cm depth (< 2mm fraction) processed and analysed in the laboratory. The soils are in a state of equilibrium from the C: N ratio (14.50 to 35.00), influencing the biogeochemistry of carbon, nitrogen, and phosphorus in pedogenetic development. There was high exchangeable calcium (6.20 Cmolkg-1 to 12.40 Cmolkg-1) and magnesium (1.00Cmolkg-1 to 4.80Cmolkg-1). Potassium contents were found to be medium to high (0.27 Cmolkg-1 to 1.54 Cmolkg-1). Available phosphorus ranged from low to medium contents (1.40 mkg-1 to 22.05 mkg-1) in all the samples. Cation exchange capacity (CEC) ranged from 10.01 Cmolkg-1 to 0.41 Cmolkg-1 and percent base saturation was high having >80%. Parent materials (sedimentary deposits) had influenced the availability of phosphorus and the exchangeable bases on the farm. These findings conclude that the soils have a high fertility status. However, there are slight hazards of salinity
Microwave induced magnetoresistance oscillations at the subharmonics of the cyclotron resonance
The magnetoresistance oscillations, which occur in a two-dimensional electron
system exposed to strong microwave radiation when the microwave frequency
coincides with the n-th subharmonic of the cyclotron frequency
have been investigated for n = 2, 3 and 4. It is shown that these
subharmonic features can be explained within a non-equilibrium energy
distribution function picture without invoking multi-photon absorption
processes. The existence of a frequency threshold above which such oscillations
disappear lends further support to this explanation.Comment: 5 pages, 5 figure
Relativistic coupled-cluster calculations of Ne, Ar, Kr and Xe: correlation energies and dipole polarizabilities
We have carried out a detailed and systematic study of the correlation
energies of inert gas atoms Ne, Ar, Kr and Xe using relativistic many-body
perturbation theory and relativistic coupled-cluster theory. In the
relativistic coupled-cluster calculations, we implement perturbative triples
and include these in the correlation energy calculations. We then calculate the
dipole polarizability of the ground states using perturbed coupled-cluster
theory.Comment: 10 figures, 6 tables, submitted to PR
Fock space relativistic coupled-Cluster calculations of Two-Valence Atoms
We have developed an all particle Fock-space relativistic coupled-cluster
method for two-valence atomic systems. We then describe a scheme to employ the
coupled-cluster wave function to calculate atomic properties. Based on these
developments we calculate the excitation energies, magnetic hyperfine constants
and electric dipole matrix elements of Sr, Ba and Yb. Further more, we
calculate the electric quadrupole HFS constants and the electric dipole matrix
elements of Sr, Ba and Yb. For these we use the one-valence
coupled-cluster wave functions obtained as an intermediate in the two-valence
calculations. We also calculate the magnetic dipole hyperfine constants of
Yb.Comment: 23 pages, 12 figures, 10 tables typos are corrected and some minor
modifications in some of the section
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