Robert B. Hayes
Abstract
A recently conceived nuclear reactor design is evaluated here for
preliminary theoretical burn-up
characteristics which is intended to meet Global Nuclear Energy
Partnership (GNEP) goals. This
reactor uses Natural Uranium (NU) metal as a single material fuel with
beryllium moderation. The reactor also uses light water as a coolant. At
constant power, the core reactivity initially
decreases followed by a long term increase within 1 month. The
reactivity increase eventually
hits a maximum followed by a decline ending around a burn-up of over 30
GW-d when all the fuel
is analyzed as a single material. By considering a strategic power
history profile, this property
can be exploited for advantage to allow power increases to eventually
fall in the range of 100 to
500 MW for a once through cycle. Alternatively, by using a small
fraction of the initial loading as
either a slightly enriched mix of uranium or reprocessed spent fuel from
this reactor, overall
higher operating powers can be realized. By running the reactor for any
moderate length of time
sufficient to create appreciable amounts of plutonium, the hyper
breeding nature of the reactor
converts a large fraction of the isotope Pu-239 into Pu-240 supporting a
proliferation resistant
nature of the design. By reprocessing the spent fuel without ever
separating the plutonium from
the uranium, GNEP goals can be supported by mixing the spent fuel with
natural or depleted
uranium. In this way, the reactor might be used in normal operations for
transmutation of the long lived actinides.
Full Article
Studies on antimicrobial, antioxidant and phytochemical analysis of
Urena lobata Leave extract
Adeloye, O. Adewale, Akinpelu, A. David, Ogundaini, O. Abiodun, Obafemi,
A. Craig
Abstract
The leaves extracts of Urena lobata
L were examined for their antioxidant, antibacterial and
antifungal activities. Preliminary evaluation of both the crude and the
solvent fractions showed a broad spectrum of activity since the extracts
inhibit the growth of both gram positive and gram negative bacterial
isolates. The ethyl acetate and n-butanol
fractions had a fast antioxidant reaction with DPPH solution, while the
n-hexane and dichloromethane
fractions gave no reaction. Three
compounds were isolated from the ethyl acetate fraction and their
structures determined, on the basis of spectroscopic data, to be kaempferol 1,
quercetin 2,
and 3-O-β-D-(6″-O-trans-p coumaroyl)-α-L-glucopyranosyl-kaempferol
3 (tiliroside). The compounds showed strong antimicrobial activity
against Escherichia coli,
Bacillus subtilis,
Klebsiella pneumoniae,
Bacillus polyxyma
and Candida
albicans. The compounds also showed
moderate to fast radical scavenging properties against DPPH radical. It
was concluded that the isolated flavanoids may be part of the compounds
responsible for the biological activity of
Urena lobata
leaf extract. This study therefore supports the traditional uses of the
plant in the treatment of infectious diseases.
Full Article
A Simple Laboratory Experiment for the Measurement of Single Phase
Permeability
Ali R. Zand, Yuri Sikorski, Matthew S. Sanders, Homayun K. Navaz
Abstract
A simple experiment for
measuring single-phase permeability of fully saturated porous medium
is introduced. The experiment
utilizes radial flow of a non-volatile wetting fluid through a porous
medium such as ceramic tile,
concrete or sand. The radial position of flow front is measured as
a function of time and the
collected data are analyzed using Darcy’s Law to determine the
permeability. In addition, the
phenomenon of the multiphase flow through the medium with a
broad pore size distribution
is demonstrated.
Full Article
Composition of two Lorentz boosts through spatial and space-time
rotations
Chandru Iyer and G. M. Prabhu
Abstract
We develop the Lorentz matrix
in two-dimensional space by two methods consisting of three
parameters each. By comparing
the two and utilizing the natural invariant properties of the
elements, we evolve the
composition of two Lorentz boosts. The development specifies how to
switch from one
three-parameter set to the other. A numerical tool to combine two planar
boosts
is provided. We extend the
method to three spatial dimensions by confining the boosts to a
plane.Thus we show, without assuming the existence of a four-dimensional
continuum, that the ordered composition of two Lorentz boosts in
three-dimensional space yields a Lorentz boost.
Full Article
The Stability of an Inviscid Liquid Sheet Containing Vapor Bubbles
Layachi Hadji and Willard Schreiber
Abstract
The development of a liquid
spray exiting a nozzle begins with the breakup of a liquid jet or sheet
injected into a gas. The presence of vapor bubbles in a liquid jet can
modify the instabilities, such as the Kelvin-Helmholtz interface
instability, which causes a liquid jet or sheet to break up into a
dispersion of small liquid droplets. A previously derived model is used
in the present paper to investigate the influence of the presence of
bubbles on the Kelvin-Helmholtz instability of an inviscid liquid sheet.
It is predicted that the presence of bubbles would yield smaller liquid
droplets.
Full Article
Can We Be More Efficient in Oil and Gas Exploitation? A Review of the
Shortcomings of Recovery Factor and the Need for an Open Worldwide
Production Database
Gioia Falcone, Bob Harrison, Catalin Teodoriu
Abstract
This paper critically reviews
the concept of recovery factor (RF) of oil and gas fields. Although this
simple parameter is used
throughout the oil and gas industry, it is subject to misunderstanding
and misuse. Besides changing
continually through the producing life of a field, the estimate of RF is
affected by geological uncertainty, inappropriate reserves reporting,
technological
shortcomings, commercial
practices and political decisions. At present, the information necessary
to fully evaluate RF is not unequivocally determined, audited or
reported, which makes it impossible to produce consistent global field
statistics. Based on the authors’ experience, the
paper outlines the
shortcomings of RF and suggests how they may be overcome. To promote
clarity and transparency in RF
calculations, a template for an open worldwide production
database is proposed.
Full Article
|
