1,065 research outputs found
Theoretical principles of petroleum hydrogeology of the West Siberian megabasin (WSMB)
Comprehensive study of the chemical and gas composition, temperatures, levels, pressure of deep underground water in deep wells is associated with the beginning of the systematic development of the oil and gas potential in Western Siberia and the first discovery of large deposits here. The development of new branches of hydrogeology is due to the fact of more and more available data. Thus, fundamental understandings of the WSMB hydrogeological conditions are being translated into new theories. Geodynamically, the WSMB structure was revised and based on hydrogeological data, regional and local prediction of oil and gas occurrence exploration criteria were developed. Based on the dispersion halo water-dissolved substance theory, exploration methodology of "neglected" deposits were formulated, conceptual issues of technogenic changes of oil and gas hydrogeosphere areas were being developed
Simulations of protostellar collapse using multigroup radiation hydrodynamics. I. The first collapse
Radiative transfer plays a major role in the process of star formation. Many
simulations of gravitational collapse of a cold gas cloud followed by the
formation of a protostellar core use a grey treatment of radiative transfer
coupled to the hydrodynamics. However, dust opacities which dominate extinction
show large variations as a function of frequency. In this paper, we used
frequency-dependent radiative transfer to investigate the influence of the
opacity variations on the properties of Larson's first core. We used a
multigroup M1 moment model in a 1D radiation hydrodynamics code to simulate the
spherically symmetric collapse of a 1 solar mass cloud core. Monochromatic dust
opacities for five different temperature ranges were used to compute Planck and
Rosseland means inside each frequency group. The results are very consistent
with previous studies and only small differences were observed between the grey
and multigroup simulations. For a same central density, the multigroup
simulations tend to produce first cores with a slightly higher radius and
central temperature. We also performed simulations of the collapse of a 10 and
0.1 solar mass cloud, which showed the properties of the first core to be
independent of the initial cloud mass, with again no major differences between
grey and multigroup models. For Larson's first collapse, where temperatures
remain below 2000 K, the vast majority of the radiation energy lies in the IR
regime and the system is optically thick. In this regime, the grey
approximation does a good job reproducing the correct opacities, as long as
there are no large opacity variations on scales much smaller than the width of
the Planck function. The multigroup method is however expected to yield more
important differences in the later stages of the collapse when high energy (UV
and X-ray) radiation is present and matter and radiation are strongly
decoupled.Comment: 9 pages, 5 figures, accepted for publication in A&
Numerical simulation of strongly nonlinear and dispersive waves using a Green-Naghdi model
We investigate here the ability of a Green-Naghdi model to reproduce strongly
nonlinear and dispersive wave propagation. We test in particular the behavior
of the new hybrid finite-volume and finite-difference splitting approach
recently developed by the authors and collaborators on the challenging
benchmark of waves propagating over a submerged bar. Such a configuration
requires a model with very good dispersive properties, because of the
high-order harmonics generated by topography-induced nonlinear interactions. We
thus depart from the aforementioned work and choose to use a new Green-Naghdi
system with improved frequency dispersion characteristics. The absence of dry
areas also allows us to improve the treatment of the hyperbolic part of the
equations. This leads to very satisfying results for the demanding benchmarks
under consideration
Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start-up
Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated
Dilepton production in heavy ion collisions at intermediate energies
We present a unified description of the vector meson and dilepton production
in elementary and in heavy ion reactions. The production of vector mesons
() is described via the excitation of nuclear resonances ().
The theoretical framework is an extended vector meson dominance model (eVMD).
The treatment of the resonance decays with arbitrary spin is
covariant and kinematically complete. The eVMD includes thereby excited vector
meson states in the transition form factors. This ensures correct asymptotics
and provides a unified description of photonic and mesonic decays. The
resonance model is successfully applied to the production in
reactions. The same model is applied to the dilepton production in elementary
reactions (). Corresponding data are well reproduced. However, when
the model is applied to heavy ion reactions in the BEVALAC/SIS energy range the
experimental dilepton spectra measured by the DLS Collaboration are
significantly underestimated at small invariant masses. As a possible solution
of this problem the destruction of quantum interference in a dense medium is
discussed. A decoherent emission through vector mesons decays enhances the
corresponding dilepton yield in heavy ion reactions. In the vicinity of the
-peak the reproduction of the data requires further a substantial
collisional broadening of the and in particular of the meson.Comment: 32 pages revtex, 19 figures, to appear in PR
They are not all same: variations in Asian consumers' value perceptions of luxury brands
Asian markets are steadily becoming key growth regions for luxury brands. However, despite the growth, many luxury brand firms are unable to obtain the desired economic returns through their marketing strategies in Asia. Often these firms treat consumers across Asian markets as homogenous groups, which could lead to inaccurate luxury brand management strategy. Additionally, there is limited understanding of consumer value perceptions toward luxury brands across the Asian markets. Employing impression management theory and the horizontal/vertical collectivistic cultural distinctions, this study examines differences and similarities in constituent luxury value perceptions across three prominent Asian markets, namely China, India, and Indonesia. The results of a quantitative survey conducted with 626 real luxury consumers in these three countries identify variations in perceptions of symbolic, experiential, and functional value of luxury brands. The study contributes to knowledge on constituent luxury value perceptions, along with providing theoretical explanations for the differences between consumers across Asian markets. With the emerging novel insights on Asian consumers, luxury brand firms can align their marketing strategies to respective markets by leveraging the similarities and differences in consumer value perceptions. This approach, informed by empirical evidence, will enhance luxury brands’ competitiveness and profit opportunities in the high-growth Asian markets. The study identifies a number of future research directions
Forced Solid-State Interactions for the Selective “Turn-On” Fluorescence Sensing of Aluminum Ions in Water Using a Sensory Polymer Substrate
Selective and sensitive solid sensory substrates for detecting Al(III) in pure
water are reported. The material is a flexible polymer film that can be handled and exhibits gel
behavior and membrane performance. The film features a chemically anchored salicylaldehyde
benzoylhydrazone derivative as an aluminum ion fluorescence sensor. A novel procedure for
measuring Al(III) at the ppb level using a single solution drop in 20 min was developed. In this
procedure, a drop was allowed to enter the hydrophilic material for 15 min before a 5 min
drying period. The process forced the Al(III) to interact with the sensory motifs within the
membrane before measuring the fluorescence of the system. The limit of detection of Al(III)
was 22 ppm. Furthermore, a water-soluble sensory polymer containing the same sensory
motifs was developed with a limit of detection of Al(III) of 1.5 ppb, which was significantly
lower than the Environmental Protection Agency recommendations for drinking water.Spanish Ministerio de Economía
y Competitividad-Feder
(MAT2011-22544) and by the Consejería
de Educación - Junta
de Castilla y León (BU232U13)
Enhancing organisational competitiveness via social media - a strategy as practice perspective
The affordances, popularity and pervasive use of social media platforms such as Facebook, Twitter and Instagram have made these platforms attractive to organisations for enhancing their competitiveness and creating business value. Despite this apparent significance of social media for businesses, they are struggling with the development of a social media strategy as well as understanding the implications of social media on practice within their organisations. This paper explores how social media has become a tool for competitiveness and its influence on organisational strategy and practice. Using the 'strategy as practice' lens and guided by the interpretivist philosophy, this paper uses the empirical case of a telecom organisation in Tanzania. The findings show that social media is influencing competitiveness through imitation and product development. Also, the findings indicate how social media affects the practices within an organisation, consequently making the social media strategy an emergent phenomenon
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