48,306 research outputs found
Finite size corrections to the blackbody radiation laws
We investigate the radiation of a blackbody in a cavity of finite size. For a
given geometry, we use semiclassical techniques to obtain explicit expressions
of the modified Planck's and Stefan-Boltzmann's blackbody radiation laws as a
function of the size and shape of the cavity. We determine the range of
parameters (temperature, size and shape of the cavity) for which these effects
are accessible to experimental verification. Finally we discuss potential
applications of our findings in the physics of the cosmic microwave background
and sonoluminescence.Comment: 5 pages, 1 figure, journal versio
Comparative energetic assessment of methanol production from COâ‚‚: chemical versus electrochemical process
Emerging emission-to-liquid (eTL) technologies that produce liquid fuels from COâ‚‚ are a possible solution for both the global issues of greenhouse gas emissions and fossil fuel depletion. Among those technologies, COâ‚‚ hydrogenation and high-temperature COâ‚‚ electrolysis are two promising options suitable for large-scale applications. In this study, two COâ‚‚ -to-methanol conversion processes, i.e., production of methanol by COâ‚‚ hydrogenation and production of methanol based on high-temperature COâ‚‚ electrolysis, are simulated using Aspen HYSYS. With Aspen Energy Analyzer, heat exchanger networks are optimized and minimal energy requirements are determined for the two different processes. The two processes are compared in terms of energy requirement and climate impact. It is found that the methanol production based on COâ‚‚ electrolysis has an energy efficiency of 41%, almost double that of the COâ‚‚ hydrogenation process provided that the required hydrogen is sourced from water electrolysis. The hydrogenation process produces more COâ‚‚ when fossil fuel energy sources are used, but can result in more negative COâ‚‚ emissions with renewable energies. The study reveals that both of the eTL processes can outperform the conventional fossil-fuel-based methanol production process in climate impacts as long as the renewable energy sources are implemented
A note on static dyonic diholes
In this brief note we argue that a dyonic generalization of the Emparan-Teo
dihole solution is described by a static diagonal metric and therefore,
contrary to the claim made in a recent paper by Cabrera-Munguia et al., does
not involve any "non-vanishing global angular momentum" and rotating charges.Comment: 4 pages, 1 figure; typos corrected, matches the published versio
Electroproduction ratios of Baryon-Meson states and Strangeness Suppression
We describe the electroproduction ratios of baryon-meson states from nucleon,
inferring from the sea quarks in the nucleon using an extension of the quark
model that takes into account the sea. As a result we provide, with no
adjustable parameters, the predictions of ratios of exclusive meson-baryon
final states:, , , , and .
These predictions are in agreement with the new Jlab experimental data showing
that sea quarks play an important role in the electroproduction. We also
predicted further ratios of exclusive reactions that can be measured and tested
in future experiments. In particular, we suggested new experiments on deuterium
and tritium. Such measurements can provide crucial test of different
predictions concerning the structure of nucleon and its sea quarks helping to
solve an outstanding problem. Finally, we computed the so called strangeness
suppression factor, , that is the suppression of strange
quark-antiquarks compared to nonstrange pairs, and we found that our finding
with this simple extension of the quark model is in good agreement with the
results of Jlab and CERN experiments.Comment: 4 pages, 1figur
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