14,477 research outputs found
Energy levels and radiative rates for transitions in Fe V, Co VI and Ni VII
Energy levels, Land\'{e} -factors and radiative lifetimes are reported for
the lowest 182 levels of the 3d, 3d4s and 3d4p configurations of
Fe~V, Co~VI and Ni~VII. Additionally, radiative rates (-values) have been
calculated for the E1, E2 and M1 transitions among these levels. The
calculations have been performed in a quasi-relativistic approach (QR) with a
very large {\em configuration interaction} (CI) wavefunction expansion, which
has been found to be necessary for these ions. Our calculated energies for all
ions are in excellent agreement with the available measurements, for most
levels. Discrepancies among various calculations for the radiative rates of E1
transitions in Fe~V are up to a factor of two for stronger transitions (), and larger (over an order of magnitude) for weaker ones. The reasons for
these discrepancies have been discussed and mainly are due to the differing
amount of CI and methodologies adopted. However, there are no appreciable
discrepancies in similar data for M1 and E2 transitions, or the -factors for
the levels of Fe~V, the only ion for which comparisons are feasible.Comment: This paper of 78 pages including 9 Tables will appear in ADNDT (2016
Energy levels and radiative rates for transitions in Cr-like Co IV and Ni V
We report calculations of energy levels and radiative rates (-values) for
transitions in Cr-like Co IV and Ni V. The quasi-relativistic Hartree-Fock
(QRHF) code is adopted for calculating the data although GRASP (general-purpose
relativistic atomic structure package) and flexible atomic code (FAC) have also
been employed for comparison purposes. No radiative rates are available in the
literature to compare with our results, but our calculated energies are in
close agreement with those compiled by NIST for a majority of the levels.
However, there are discrepancies for a few levels of up to 3\%. The -values
are listed for all significantly contributing E1, E2 and M1 transitions, and
the corresponding lifetimes reported, although unfortunately no previous
theoretical or experimental results exist to compare with our data.Comment: The paper will appear in ADNDT (2016) and in October 2015 on the we
Cumulative effect of Weibel-type instabilities in counterstreaming plasmas with non-Maxwellian anisotropies
Counterstreaming plasma structures are widely present in laboratory
experiments and astrophysical systems, and they are investigated either to
prevent unstable modes arising in beam-plasma experiments or to prove the
existence of large scale magnetic fields in astrophysical objects.
Filamentation instability arises in a counterstreaming plasma and is
responsible for the magnetization of the plasma. Filamentationally unstable
mode is described by assuming that each of the counterstreaming plasmas has an
isotropic Lorentzian (kappa) distribution. In this case, the filamentation
instability growth rate can reach a maximum value markedly larger than that for
a a plasma with a Maxwellian distribution function. This behaviour is opposite
to what was observed for the Weibel instability growth rate in a bi-kappa
plasma, which is always smaller than that obtained for a bi-Maxwellian plasma.
The approach is further generalized for a counterstreaming plasma with a
bi-kappa temperature anisotropy. In this case, the filamentation instability
growth rate is enhanced by the Weibel effect when the plasma is hotter in the
streaming direction, and the growth rate becomes even larger. These effects
improve significantly the efficiency of the magnetic field generation, and
provide further support for the potential role of the Weibel-type instabilities
in the fast magnetization scenarios
On fixed linear systems with a generalized performance criteria
Fixed linear systems with generalized performance criteri
Studies in matter antimatter separation and in the origin of lunar magnetism
A progress report, covering lunar and planetary research is introduced. Data cover lunar ionospheric models, lunar and planetary geology, and lunar magnetism. Wind tunnel simulations of Mars aeolian problems and a comparative study of basaltic analogs of Lunar and Martial volcanic features was discussed
Annealing of defects in Fe after MeV Heavy ion irradiation
We report study of recovery dynamics, followed by in-situ resistivity
measurement after 100 MeV oxygen ion irradiation, in cold rolled Fe at 300K.
Scaling behavior with microstructural density and temperature of sample have
been used to establish stress induced defects formed during irradiation as a
new type of sink. The dynamics after irradiation has been shown to be due to
migration of defects to two types of sinks i.e. stress induced defect as
variable sinks and internal surfaces as fixed sinks. Experimental data obtained
under various experimental conditions have been fitted to theoretical curves.
Parameters thus obtained from fitting are employed to establish effect of
electronic energy loss and temperature on recovery dynamics and stress
associated with variable sinks.Comment: 12 pages, 7 figures. Europhysics Letter (in press
Electron Impact Excitation Cross Sections for Hydrogen-Like Ions
We present cross sections for electron-impact-induced transitions n --> n' in
hydrogen-like ions C 5+, Ne 9+, Al 12+, and Ar 17+. The cross sections are
computed by Coulomb-Born with exchange and normalization (CBE) method for all
transitions with n < n' < 7 and by convergent close-coupling (CCC) method for
transitions with n 2s and 1s
--> 2p are presented as well. The CCC and CBE cross sections agree to better
than 10% with each other and with earlier close-coupling results (available for
transition 1 --> 2 only). Analytical expression for n --> n' cross sections and
semiempirical formulae are discussed.Comment: RevTeX, 5 pages, 13 PostScript figures, submitted to Phys. Rev.
The STAR Photon Multiplicity Detector
Details concerning the design, fabrication and performance of STAR Photon
Multiplicity Detector (PMD) are presented. The PMD will cover the forward
region, within the pseudorapidity range 2.3--3.5, behind the forward time
projection chamber. It will measure the spatial distribution of photons in
order to study collective flow, fluctuation and chiral symmetry restoration.Comment: 15 pages, including 11 figures; to appear in a special NIM volume
dedicated to the accelerator and detectors at RHI
Managing Climatic Risks to Combat Land Degradation and Enhance Food security: Key Information Needs
This paper discusses the key information needs to reduce the negative impacts of weather variability and climate change on land degradation and food security, and identifies the opportunities and barriers between the information and services needed. It suggests that vulnerability assessments based on a livelihood concept that includes climate information and key socio-economic variables can overcome the narrow focus of common one-dimensional vulnerability studies. Both current and future climatic risks can be managed better if there is appropriate policy and institutional support together with technological interventions to address the complexities of multiple risks that agriculture has to face. This would require effective partnerships among agencies dealing with meteorological and hydrological services, agricultural research, land degradation and food security issues. In addition a state-of-the-art infrastructure to measure, record, store and disseminate data on weather variables, and access to weather and seasonal climate forecasts at desired spatial and temporal scales would be needed
Малая автоматизация на ЦВМ "Урал-11Б"
Wireless communication technologies like GPRS, UMTS and WLAN, combined with the availability of high-end, affordable mobile devices enable the development of the advanced and innovative mobile services. Devices such as mobile phones and Personal Digital Assistants let the users access a wide range of new offerings whenever and wherever they happen to be. A strategic approach for the quality assurance of these mobile data services should take into account a number of characteristics unique to the mobile paradigm, the increased complexity of emerging handheld devices, the greater sensitivity to security and load related problems in wireless infrastructure and increased complexities of scale. This paper identifies the major factors influencing the development and testing strategies for these applications and accordingly elaborates effective quality assurance principles to ensure productive and scalable mobile data services
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