5,483 research outputs found
Advanced technology applications for second and third general coal gasification systems
The historical background of coal conversion is reviewed and the programmatic status (operational, construction, design, proposed) of coal gasification processes is tabulated for both commercial and demonstration projects as well as for large and small pilot plants. Both second and third generation processes typically operate at higher temperatures and pressures than first generation methods. Much of the equipment that has been tested has failed. The most difficult problems are in process control. The mechanics of three-phase flow are not fully understood. Companies participating in coal conversion projects are ordering duplicates of failure prone units. No real solutions to any of the significant problems in technology development have been developed in recent years
Polarized light ions and spectator nucleon tagging at EIC
An Electron-Ion Collider (EIC) with suitable forward detection capabilities
would enable a unique experimental program of deep-inelastic scattering (DIS)
from polarized light nuclei (deuterium 2H, helium 3He) with spectator nucleon
tagging. Such measurements promise significant advances in several key areas of
nuclear physics and QCD: (a) neutron spin structure, by using polarized
deuterium and eliminating nuclear effects through on-shell extrapolation in the
spectator proton momentum; (b) quark/gluon structure of the bound nucleon at x
> 0.1 and the dynamical mechanisms acting on it, by measuring the spectator
momentum dependence of nuclear structure functions; (c) coherent effects in
QCD, by exploring shadowing in tagged DIS on deuterium at x << 0.1. The JLab
MEIC design (CM energy sqrt{s} = 15-50 GeV/nucleon, luminosity ~ 10^{34}
cm^{-2} s^{-1}) provides polarized deuterium beams and excellent coverage and
resolution for forward spectator tagging. We summarize the physics topics, the
detector and beam requirements for spectator tagging, and on-going R&D efforts.Comment: 6 pages, 2 figures. Prepared for proceedings of DIS 2014, XXII.
International Workshop on Deep-Inelastic Scattering and Related Subjects,
University of Warsaw, Poland, April 28 - May 2, 201
Neutron spin structure with polarized deuterons and spectator proton tagging at EIC
The neutron's deep-inelastic structure functions provide essential
information for the flavor separation of the nucleon parton densities, the
nucleon spin decomposition, and precision studies of QCD phenomena in the
flavor-singlet and nonsinglet sectors. Traditional inclusive measurements on
nuclear targets are limited by dilution from scattering on protons, Fermi
motion and binding effects, final-state interactions, and nuclear shadowing at
x << 0.1. An Electron-Ion Collider (EIC) would enable next-generation
measurements of neutron structure with polarized deuteron beams and detection
of forward-moving spectator protons over a wide range of recoil momenta (0 <
p_R < several 100 MeV in the nucleus rest frame). The free neutron structure
functions could be obtained by extrapolating the measured recoil momentum
distributions to the on-shell point. The method eliminates nuclear
modifications and can be applied to polarized scattering, as well as to
semi-inclusive and exclusive final states. We review the prospects for neutron
structure measurements with spectator tagging at EIC, the status of R&D
efforts, and the accelerator and detector requirements.Comment: 11 pages, 3 figures. To appear in proceedings of Tensor Polarized
Solid Target Workshop, Jefferson Lab, March 10-12, 201
Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering
We propose a new approach to the problem of rapidity gap survival (RGS) in
the production of high-mass systems (H = dijet, heavy quarkonium, Higgs boson)
in double-gap exclusive diffractive pp scattering, pp -> p + (gap) + H + (gap)
+ p. It is based on the idea that hard and soft interactions proceed over
widely different time- and distance scales and are thus approximately
independent. The high-mass system is produced in a hard scattering process with
exchange of two gluons between the protons. Its amplitude is calculable in
terms of the gluon generalized parton distributions (GPDs) in the protons,
which can be measured in J/psi production in exclusive ep scattering. The hard
scattering process is modified by soft spectator interactions, which we
calculate in a model-independent way in terms of the pp elastic scattering
amplitude. Contributions from inelastic intermediate states are suppressed. A
simple geometric picture of the interplay of hard and soft interactions in
diffraction is obtained. The onset of the black-disk limit in pp scattering at
TeV energies strongly suppresses diffraction at small impact parameters and is
the main factor in determining the RGS probability. Correlations between hard
and soft interactions (e.g. due to scattering from the long-range pion field of
the proton, or due to possible short-range transverse correlations between
partons) further decrease the RGS probability. We also investigate the
dependence of the diffractive cross section on the transverse momenta of the
final-state protons ("diffraction pattern"). By measuring this dependence one
can perform detailed tests of the interplay of hard and soft interactions, and
even extract information about the gluon GPD in the proton. Such studies appear
to be feasible with the planned forward detectors at the LHC.Comment: 26 pages, 17 figures, uses revtex
Optimal conditions of mycelial growth of three wild edible mushrooms from northern Thailand
In this study, three wild mushrooms namely Lentinus connatus, L. roseus, and Pleurotusgiganteus were selected to study if they could be domesticated. Initially, the fruiting bodies of the three mushrooms were collected from forests in northern Thailand and morphologically characterized. In this paper we report the optimal in vitro culture conditions of three wild mushrooms. Among seven culture media tested for the optimal mycelial growth of three wild mushrooms, black bean agar, red bean and soy bean agar were the best for the mycelial growth of L. connatus, L. roseus and Pleurotusgiganteus, respectively. The mushroom mycelia were able to grow at temperatures ranging from 20-30 °C, with optimal growth temperatures of 30 °C and 25 °C for Lentinus and Pleurotus species, respectively. The optimum pH range observed for mycelial growth was 5.0 - 7.0
Kuiper Binary Object Formation
It has been observed that binary Kuiper Belt Objects (KBOs) exist contrary to
theoretical expectations. Their creation presents problems to most current
models. However, the inclusion of a third body (for example, one of the outer
planets) may provide the conditions necessary for the formation of these
objects. The presence of a third massive body not only helps to clear the
primordial Kuiper Belt but can also result in long lived binary Kuiper belt
objects. The gravitational interaction between the KBOs and the third body
causes one of four effects; scattering into the Oort cloud, collisions with the
growing protoplanets, formation of binary pairs, or creation of a single Kuiper
belt object. Additionally, the initial location of the progenitors of the
Kuiper belt objects also has a significant effect on binary formation
Investigation of shock waves in explosive blasts using fibre optic pressure sensors
The published version of this article may be accessed at the link below. Copyright @ IOP Publishing, 2006.We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1 mm(2) in overall cross-section with rise times in the mu s regime and pressure ranges typically 900 kPa (9 bar). Their performance is suitable for experimental studies of the pressure-time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Results from blast tests are presented in which up to six sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front.Support from the UK Engineering&Physical
Sciences Research Council and Dstl Fort Halstead through the MoD Joint Grants Scheme are acknowledged. WN MacPherson is supported by an EPSRC Advanced Research Fellowship
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