23,369 research outputs found
Challenges of Internet of Things and Big Data Integration
The Internet of Things anticipates the conjunction of physical gadgets to the
In-ternet and their access to wireless sensor data which makes it expedient to
restrain the physical world. Big Data convergence has put multifarious new
opportunities ahead of business ventures to get into a new market or enhance
their operations in the current market. considering the existing techniques and
technologies, it is probably safe to say that the best solution is to use big
data tools to provide an analytical solution to the Internet of Things. Based
on the current technology deployment and adoption trends, it is envisioned that
the Internet of Things is the technology of the future, while to-day's
real-world devices can provide real and valuable analytics, and people in the
real world use many IoT devices. Despite all the advertisements that companies
offer in connection with the Internet of Things, you as a liable consumer, have
the right to be suspicious about IoT advertise-ments. The primary question is:
What is the promise of the Internet of things con-cerning reality and what are
the prospects for the future.Comment: Proceedings of the International Conference on International
Conference on Emerging Technologies in Computing 2018 (iCETiC '18), 23rd
-24th August, 2018, at London Metropolitan University, London, UK, Published
by Springer-Verla
The Integrated Sachs-Wolfe Effect in Time Varying Vacuum Model
The integrated Sachs-Wolfe (ISW) effect is an important implication for dark
energy. In this paper, we have calculated the power spectrum of the ISW effect
in the time varying vacuum cosmological model, where the model parameter
is obtained by the observational constraint of the growth rate.
It's found that the source of the ISW effect is not only affected by the
different evolutions of the Hubble function and the dimensionless matter
density , but also by the different growth function , all
of which are changed due to the presence of matter production term in the time
varying vacuum model. However, the difference of the ISW effect in
model and model is lessened to
a certain extent due to the integration from the time of last scattering to the
present. It's implied that the observations of the galaxies with high redshift
are required to distinguish the two models
Characterization of Rock Mechanical Properties Using Lab Tests and Numerical Interpretation Model of Well Logs
The tight gas reservoir in the fifth member of the Xujiahe formation contains heterogeneous interlayers of sandstone and shale that are low in both porosity and permeability. Elastic characteristics of sandstone and shale are analyzed in this study based on petrophysics tests. The tests indicate that sandstone and mudstone samples have different stress-strain relationships. The rock tends to exhibit elastic-plastic deformation. The compressive strength correlates with confinement pressure and elastic modulus. The results based on thin-bed log interpretation match dynamic Young’s modulus and Poisson’s ratio predicted by theory. The compressive strength is calculated from density, elastic impedance, and clay contents. The tensile strength is calibrated using compressive strength. Shear strength is calculated with an empirical formula. Finally, log interpretation of rock mechanical properties is performed on the fifth member of the Xujiahe formation. Natural fractures in downhole cores and rock microscopic failure in the samples in the cross section demonstrate that tensile fractures were primarily observed in sandstone, and shear fractures can be observed in both mudstone and sandstone. Based on different elasticity and plasticity of different rocks, as well as the characteristics of natural fractures, a fracture propagation model was built
Mechanistic Modeling of Microtopographic Impacts on CO2 and CH4 Fluxes in an Alaskan Tundra Ecosystem Using the CLM-Microbe Model
Spatial heterogeneities in soil hydrology have been confirmed as a key control on CO2 and CH4 fluxes in the Arctic tundra ecosystem. In this study, we applied a mechanistic ecosystem model, CLM-Microbe, to examine the microtopographic impacts on CO2 and CH4 fluxes across seven landscape types in Utqiaġvik, Alaska: trough, low-centered polygon (LCP) center, LCP transition, LCP rim, high-centered polygon (HCP) center, HCP transition, and HCP rim. We first validated the CLM-Microbe model against static-chamber measured CO2 and CH4 fluxes in 2013 for three landscape types: trough, LCP center, and LCP rim. Model application showed that low-elevation and thus wetter landscape types (i.e., trough, transitions, and LCP center) had larger CH4 emissions rates with greater seasonal variations than high-elevation and drier landscape types (rims and HCP center). Sensitivity analysis indicated that substrate availability for methanogenesis (acetate, CO2 + H2) is the most important factor determining CH4 emission, and vegetation physiological properties largely affect the net ecosystem carbon exchange and ecosystem respiration in Arctic tundra ecosystems. Modeled CH4 emissions for different microtopographic features were upscaled to the eddy covariance (EC) domain with an area-weighted approach before validation against EC-measured CH4 fluxes. The model underestimated the EC-measured CH4 flux by 20% and 25% at daily and hourly time steps, suggesting the importance of the time step in reporting CH4 flux. The strong microtopographic impacts on CO2 and CH4 fluxes call for a model-data integration framework for better understanding and predicting carbon flux in the highly heterogeneous Arctic landscape
Positive Association of Cardiovascular Disease (CVD) with Chronic Exposure to Drinking Water Arsenic (As) at Concentrations below the WHO Provisional Guideline Value: A Systematic Review and Meta-Analysis.
To the best of our knowledge, a dose-response meta-analysis of the relationship between cardiovascular disease (CVD) and arsenic (As) exposure at drinking water As concentrations lower than the WHO provisional guideline value (10 µg/L) has not been published yet. We conducted a systematic review and meta-analyses to estimate the pooled association between the relative risk of each CVD endpoint and low-level As concentration in drinking water both linearly and non-linearly using a random effects dose-response model. In this study, a significant positive association was found between the risks of most CVD outcomes and drinking water As concentration for both linear and non-linear models (p-value for trend < 0.05). Using the preferred linear model, we found significant increased risks of coronary heart disease (CHD) mortality and CVD mortality as well as combined fatal and non-fatal CHD, CVD, carotid atherosclerosis disease and hypertension in those exposed to drinking water with an As concentration of 10 µg/L compared to the referent (drinking water As concentration of 1 µg/L) population. Notwithstanding limitations included, the observed significant increased risks of CVD endpoints arising from As concentrations in drinking water between 1 µg/L and the 10 µg/L suggests further lowering of this guideline value should be considered
Catalogue of topological phonon materials
Phonons play a crucial role in many properties of solid state systems, such
as thermal and electrical conductivity, neutron scattering and associated
effects or superconductivity. Hence, it is expected that topological phonons
will also lead to rich and unconventional physics and the search of materials
hosting topological phonons becomes a priority in the field. In electronic
crystalline materials, a large part of the topological properties of Bloch
states can be indicated by their symmetry eigenvalues in reciprocal space. This
has been adapted to the high-throughput calculations of topological materials,
and more than half of the stoichiometric materials on the databases are found
to be topological insulators or semi-metals. Based on the existing phonon
materials databases, here we have performed the first catalogue of topological
phonon bands for more than ten thousand three-dimensional crystalline
materials. Using topological quantum chemistry, we calculate the band
representations, compatibility relations, and band topologies of each isolated
set of phonon bands for the materials in the phonon databases. We have also
calculated the real space invariants for all the topologically trivial bands
and classified them as atomic and obstructed atomic bands. In particular,
surface phonon modes (dispersion) are calculated on different cleavage planes
for all the materials. Remarkably, we select more than one thousand "ideal"
non-trivial phonon materials to fascinate the future experimental studies. All
the data-sets obtained in the the high-throughput calculations are used to
build a Topological Phonon Database.Comment: 8+535 pages, 187 figures, 21 tables. The Topological Phonon Database
is available at https://www.topologicalquantumchemistry.com/topophonons or
https://www.topologicalquantumchemistry.fr/topophonon
Energy of general 4-dimensional stationary axisymmetric spacetime in the teleparallel geometry
The field equation with the cosmological constant term is derived and the
energy of the general 4-dimensional stationary axisymmetric spacetime is
studied in the context of the hamiltonian formulation of the teleparallel
equivalent of general relativity (TEGR). We find that, by means of the integral
form of the constraints equations of the formalism naturally without any
restriction on the metric parameters, the energy for the asymptotically flat/de
Sitter/Anti-de Sitter stationary spacetimes in the Boyer-Lindquist coordinate
can be expressed as . It is surprised to learn that the
energy expression is relevant to the metric components ,
and only. As examples, by using this formula
we calculate the energies of the Kerr-Newman (KN), Kerr-Newman Anti-de Sitter
(KN-AdS), Kaluza-Klein, and Cveti\v{c}-Youm spacetimes.Comment: 12 page
Symmetry energy of dense matter in holographic QCD
We study the nuclear symmetry energy of dense matter using holographic QCD.
To this end, we consider two flavor branes with equal quark masses in a
D4/D6/D6 model. We find that at all densities the symmetry energy monotonically
increases. At small densities, it exhibits a power law behavior with the
density, .Comment: 9 pages, 3 figure
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