6,875 research outputs found
Modeling the process of producing hydrogen from methane
Using the chemical reactions that accompany the production of syngas via the steam reforming of methane as a basis, the differential material balance equations were derived and solved for all conversion products on an aluminum/nickel catalyst. For the following stage of hydrogen synthesis on an iron/chromium catalyst, the system of two differential equations of the material balance of the direct and reverse reactions of steam carbon monoxide conversion was obtained and solved. The analytical solutions were compared with the experiment. © 2013 Pleiades Publishing, Ltd
The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN Spacecraft
We analyzed 44 passes of the MAVEN spacecraft through the magnetosphere,
arranged by the angle between electric field vector and the projection of
spacecraft position radius vector in the YZ plane in MSE coordinate system
( E ). All passes were divided into 3 angular sectors near 0{\deg},
90{\deg} and 180{\deg} E angles in order to estimate the role of IMF
direction in plasma and magnetic properties of dayside Martian magnetosphere.
The time interval chosen was from January 17 through February 4, 2016 when
MAVEN was crossing the dayside magnetosphere at SZA ~ 70{\deg}. Magnetosphere
as the region with prevailing energetic planetary ions is always found between
the magnetosheath and the ionosphere. 3 angular sectors of dayside interaction
region in MSE coordinate system with different orientation of the solar wind
electric field vector E = -1/c V x B showed that for each sector one can find
specific profiles of the magnetosheath, the magnetic barrier and the
magnetosphere. Plume ions originate in the northern MSE sector where motion
electric field is directed from the planet. This electric field ejects
magnetospheric ions leading to dilution of magnetospheric heavy ions
population, and this effect is seen in some magnetospheric profiles. Magnetic
barrier forms in front of the magnetosphere, and relative magnetic field
magnitudes in these two domains vary. The average height of the boundary with
ionosphere is ~530 km and the average height of the magnetopause is ~730 km. We
discuss the implications of the observed magnetosphere structure to the
planetary ions loss mechanism.Comment: 24 pages, 13 figure
Search for invisible decays of sub-GeV dark photons in missing-energy events at the CERN SPS
We report on a direct search for sub-GeV dark photons (A') which might be
produced in the reaction e^- Z \to e^- Z A' via kinetic mixing with photons by
100 GeV electrons incident on an active target in the NA64 experiment at the
CERN SPS. The A's would decay invisibly into dark matter particles resulting in
events with large missing energy. No evidence for such decays was found with
2.75\cdot 10^{9} electrons on target. We set new limits on the \gamma-A' mixing
strength and exclude the invisible A' with a mass < 100 MeV as an explanation
of the muon g_\mu-2 anomaly.Comment: 6 pages, 3 figures; Typos corrected, references adde
Event Generators for WW Physics
The report summarizes the results of the activities of the Working Group on
Event Generators for WW Physics at CERN during 1995.Comment: 99 Latex, including 30 figures, 24 tables. The report is part of:
G.Altarelli,T.Sjostrand and F.Zwirner (eds), Physics at LEP2 CERN 96-0
The Influence of Low-Frequency Seismic Phenomena Effects on the Process of Boiling up the Coolant
This paper studies the low frequency seismic phenomena on the overheating boiling process and the cavitation state of the coolant in a small volume of system. This experiment is basically the imitation of the situation in a nuclear reactor core where distilled water was used as coolant during the experiment. Temperature of the coolant was recorded during the normal state and the time of implementing external low frequency. The stretched state of the liquid due to overheating and the cavitation destruction process were investigated. © Published under licence by IOP Publishing Ltd
Phase diagrams in nonlocal PNJL models constrained by Lattice QCD results
Based on lattice QCD-adjusted SU(2) nonlocal Polyakov--Nambu--Jona-Lasinio
(PNJL) models, we investigate how the location of the critical endpoint in the
QCD phase diagram depends on the strenght of the vector meson coupling, as well
as the Polyakov-loop (PL) potential and the form factors of the covariant
model. The latter are constrained by lattice QCD data for the quark propagator.
The strength of the vector coupling is adjusted such as to reproduce the slope
of the pseudocritical temperature for the chiral phase transition at low
chemical potential extracted recently from lattice QCD simulations. Our study
supports the existence of a critical endpoint in the QCD phase diagram albeit
the constraint for the vector coupling shifts its location to lower
temperatures and higher baryochemical potentials than in the case without it.Comment: 23 pages, 10 figures. Version accepted in Phys. Part. Nucl. Lett. (to
appear), references adde
Detecting ancient codispersals and host shifts by double dating of host and parasite phylogenies: Application in proctophyllodid feather mites associated with passerine birds
Inferring cophylogeographic events requires matching the timing of these events on both host and symbiont (e.g., parasites) phylogenies because divergences of hosts and their symbionts may not temporally coincide, and host switches may occur. We investigate a large radiation of birds (Passeriformes) and their permanent symbionts, the proctophyllodid feather mites (117 species from 116 bird species; six genes, 11,468 nt aligned) using two time‐calibration strategies for mites: fossils only and host phylogeography only. Out of 10 putative cophylogeographic events 4 agree in timing for both symbiont and host events being synchronous co‐origins or codispersals; three were based on host shifts, but agree in timing being very close to the origin of modern hosts; two disagree; and one large basal mite split was seemingly independent from host phylogeography. Among these events was an ancient (21–25.3 Mya), synchronous codispersal from the Old World leading to the origin and diversifications of New World emberizoid passerids and their mites, the thraupis + quadratus species groups of Proctophyllodes. Our framework offers a more robust detection of host and symbiont cophylogeographic events (as compared to host‐symbiont reconciliation analysis and using host phylogeography for time‐calibration) and provides independent data for testing alternative hypotheses on timing of host diversification and dispersal.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/1/evo13309-sup-0003-figureS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/2/evo13309.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/3/evo13309-sup-0006-figureS6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/4/evo13309_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/5/evo13309-sup-0009-figureS9.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/6/evo13309-sup-0005-figureS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/7/evo13309-sup-0004-figureS4.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/8/evo13309-sup-0002-figureS2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/9/evo13309-sup-0008-figureS8.pd
Four-Fermion Production in Electron-Positron Collisions
This report summarises the results of the four-fermion working group of the
LEP2-MC workshop, held at CERN from 1999 to 2000. Recent developments in the
calculation of four-fermion processes in electron-positron collisions at LEP-2
centre-of-mass energies are presented, concentrating on predictions for four
main reactions: W-pair production, visible photons in four-fermion events,
single-W production and Z-pair production. Based on a comparison of results
derived within different approaches, theoretical uncertainties on these
predictions are established.Comment: 150 pages, 73 figures, 45 table
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