2,793 research outputs found
Thermal conductivity of hydrate-bearing sediments
Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): B11103, doi:10.1029/2008JB006235.A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrateâsaturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrateâbearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces.This work was supported by the Chevron
Joint Industry Project on Methane Hydrates under contract DE-FC26-
01NT41330 to Georgia Institute of Technology from the U.S. Department
of Energyâs National Energy Technology Laboratory. J.C.S. received
additional support from the Goizueta Foundation. C.R. thanks the Petroleum
Research Fund of the American Chemical Society under AC8â31351
for early support of thermal conductivity research on hydrate-bearing
sediments at Georgia Institute of Technology
Identification of key risk factors related to serious road injuries and their health impacts, deliverable 7.4 of the H2020 project SafetyCube
Because of their high number and slower reduction compared to fatalities, serious road injuries are
increasingly being adopted as an additional indicator for road safety, next to fatalities. Reducing the
number of serious road injuries is one of the key priorities in the EU road safety programme 2011-
2020. In 2013, the EU Member States agreed on the following definition of serious road traffic
injuries: a serious road traffic injury is a road traffic casualty with a Maximum AIS level of 3 or higher
(MAIS3+).
One recommendation created by the EU SUSTAIN project was to conduct âA more detailed study of
the causes of serious road injuries, [which] could reveal more specific keys to reduce the number of
serious injuries in the EUâ. This recommendation is addressed through the identification of crashrelated
causation and contributory factors for selected groups of casualties with relatively many
MAIS3+ casualties compared to fatalities and groups with a relatively high burden of injury of
MAIS3+ casualties.
This deliverable is made up of two parts brought together in order to determine the main
contributory factors detailed above. This two-step approach initially identifies groups of casualties
that are specifically relevant from a serious injury perspective using national level collision and
hospital datasets from 6 countries.
Following the determination of groups of interest a detailed analysis of the selected groups using indepth
data was conducted. On the basis of in-depth data from 4 European countries the main
contributory and causal factors are determined for the selected MAIS3+ casualty groups.
Alongside the three proceeding deliverables that have formed the major outputs of WP7, deliverable
D7.4 is aimed at addressing serious injury policy at an EU levels. As such this report is broadly aimed
at policy makers although the inclusion of results from in-depth data analysis also provides
information relevant to stakeholders, particularly those working in vehicle design and manufacture
or road user behaviour
La hegemonĂa tepaneca a travĂ©s del CĂłdice Telleriano-Remensis
This paper examines the Codex Telleriano-Remensis from a political perspective focusing on the period of Tepanec hegemony, which covers the first three rulers of Tenochtitlan, and of Tlatelolco. More specifically, our source offers a particularly interesting representation of the political ritual of Huitzilihuitlâs enthronement, a rite of passage that can be interpreted as overcoming the traditional-leader configuration, and the insertion of Tenochtitlan as subordinate tlatocayotl in the political structure of the Tepanec Empire with its capital in Azcapotzalco.Examinamos el CĂłdice Telleriano-Remensis desde una perspectiva polĂtica centrada en el perĂodo de hegemonĂa tepaneca, que se relaciona con los tres primeros gobernantes de Tenochtitlan, asĂ como de Tlatelolco. En particular, nuestra fuente ofrece una representaciĂłn muy interesante del ritual polĂtico de entronizaciĂłn de Huitzilihuitl, un rito de paso que interpretamos como superaciĂłn del marco de lĂderes tradicionales e inserciĂłn de Tenochtitlan como tlatocayotl subordinado en la estructura polĂtica del Imperio Tepaneca con capital en Azcapotzalco
Differential branching fraction and angular analysis of the decay B0âKâ0ÎŒ+ÎŒâ
The angular distribution and differential branching fraction of the decay B 0â K â0 ÎŒ + ÎŒ â are studied using a data sample, collected by the LHCb experiment in pp collisions at sâ=7 TeV, corresponding to an integrated luminosity of 1.0 fbâ1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
Opposite-side flavour tagging of B mesons at the LHCb experiment
The calibration and performance of the oppositeside
flavour tagging algorithms used for the measurements
of time-dependent asymmetries at the LHCb experiment
are described. The algorithms have been developed using
simulated events and optimized and calibrated with
B
+ âJ/ÏK
+, B0 âJ/ÏK
â0 and B0 âD
ââ
Ό
+
ΜΌ decay
modes with 0.37 fbâ1 of data collected in pp collisions
at
â
s = 7 TeV during the 2011 physics run. The oppositeside
tagging power is determined in the B
+ â J/ÏK
+
channel to be (2.10 ± 0.08 ± 0.24) %, where the first uncertainty
is statistical and the second is systematic
Search for CP violation in D+âÏÏ+ and D+sâK0SÏ+ decays
A search for CP violation in D + â ÏÏ + decays is performed using data collected in 2011 by the LHCb experiment corresponding to an integrated luminosity of 1.0 fbâ1 at a centre of mass energy of 7 TeV. The CP -violating asymmetry is measured to be (â0.04 ± 0.14 ± 0.14)% for candidates with K â K + mass within 20 MeV/c 2 of the Ï meson mass. A search for a CP -violating asymmetry that varies across the Ï mass region of the D + â K â K + Ï + Dalitz plot is also performed, and no evidence for CP violation is found. In addition, the CP asymmetry in the D+sâK0SÏ+ decay is measured to be (0.61 ± 0.83 ± 0.14)%
Measurement of the branching fraction
The branching fraction is measured in a data sample
corresponding to 0.41 of integrated luminosity collected with the LHCb
detector at the LHC. This channel is sensitive to the penguin contributions
affecting the sin2 measurement from The
time-integrated branching fraction is measured to be . This is the most precise measurement to
date
Study of decays to the final state and evidence for the decay
A study of decays is performed for the first time
using data corresponding to an integrated luminosity of 3.0
collected by the LHCb experiment in collisions at centre-of-mass energies
of and TeV. Evidence for the decay
is reported with a significance of 4.0 standard deviations, resulting in the
measurement of
to
be .
Here denotes a branching fraction while and
are the production cross-sections for and mesons.
An indication of weak annihilation is found for the region
, with a significance of
2.4 standard deviations.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-022.html,
link to supplemental material inserted in the reference
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
Measurement of the mixing-induced CP-violating phase phi_s in Bs decays is of
prime importance in probing new physics. Here 7421 +/- 105 signal events from
the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp
collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A
time-dependent fit to the data yields a value of
phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard
Model expectation. No evidence of direct CP violation is found.Comment: 15 pages, 10 figures; minor revisions on May 23, 201
Measurement of the CP-violating phase phi_s in the decay Bs->J/psi phi
We present a measurement of the time-dependent CP-violating asymmetry in B_s
-> J/psi phi decays, using data collected with the LHCb detector at the LHC.
The decay time distribution of B_s -> J/psi phi is characterized by the decay
widths Gamma_H and Gamma_L of the heavy and light mass eigenstates of the
B_s-B_s-bar system and by a CP-violating phase phi_s. In a sample of about 8500
B_s -> J/psi phi events isolated from 0.37 fb^-1 of pp collisions at sqrt(s)=7
TeV we measure phi_s = 0.15 +/- 0.18 (stat) +/- 0.06 (syst) rad. We also find
an average B_s decay width Gamma_s == (Gamma_L + Gamma_H)/2 = 0.657 +/- 0.009
(stat) +/- 0.008 (syst) ps^-1 and a decay width difference Delta Gamma_s ==
Gamma_L - Gamma_H} = 0.123 +/- 0.029 (stat) +/- 0.011 (syst) ps^-1. Our
measurement is insensitive to the transformation (phi_s,DeltaGamma_s --> pi -
phi_s, - Delta Gamma_s.Comment: 9 pages, 3 figure
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