15,055 research outputs found
Instrument for measuring the dynamic behavior of liquids Patent
Pressure sensor network for measuring liquid dynamic response in flight including fuel tank acceleration, liquid slosh amplitude, and fuel depth monitorin
Health and sustainable development
If sustainable development is to mean anything, people must be healthy enough to benefit from it and not have their lives cut off prematurely. Development without health is meaningless. But the processes which are likely to occur in a world undergoing globalisation, climate change, urbanisation, population increase and many other changes, will impact upon human health in complex ways. Some of them will benefit us, others will create new or augmented threats to survival and health, while many others will have a complex mixture of effects
Why Two Renormalization Groups are Better than One
The advantages of using more than one renormalization group (RG) in problems
with more than one important length scale are discussed. It is shown that: i)
using different RG's can lead to complementary information, i.e. what is very
difficult to calculate with an RG based on one flow parameter may be much more
accessible using another; ii) using more than one RG requires less physical
input in order to describe via RG methods the theory as a function of its
parameters; iii) using more than one RG allows one to solve problems with more
than one diverging length scale. The above points are illustrated concretely in
the context of both particle physics and statistical physics using the
techniques of environmentally friendly renormalization. Specifically, finite
temperature theory, an Ising-type system in a film geometry, an
Ising-type system in a transverse magnetic field, the QCD coupling constant at
finite temperature and the crossover between bulk and surface critical
behaviour in a semi-infinite geometry are considered.Comment: 17 pages LaTex; to be published in the Proceedings of RG '96, Dubn
A review of Leptospermum scoparium (Myrtaceae) in New Zealand
Information about Leptospermum scoparium (Myrtaceae), the most widespread and important New Zealand indigenous shrub species, is reviewed. L. scoparium is a variable species, requiring more study of the genetically based differences between New Zealand populations and the affinity of these populations to Australian populations and other closely allied Australian species. Improved understanding of the species’ variation will assist both its conservation roles and economic uses, and the need to sustain genetically distinct varieties is emphasised. Ecologically, the species has a dominant role in infertile and poorly drained environments, and a wider occurrence as a seral shrub species in successions to forest where it may be regarded as a woody weed of pasture or a useful species for erosion control, carbon sesquestration, and vegetation restoration. The main economic products derived from the species are ornamental shrubs, essential oils, and honey. The species’ development as an ornamental plant and further definition of the pharmacologically active components are recommended as priority areas for research
IEEE 802.11n MAC frame aggregation mechanisms for next-generation high-throughput WLANs [Medium access control protocols for wireless LANs]
IEEE 802.11n is an ongoing next-generation wireless LAN standard that supports a very highspeed connection with more than 100 Mb/s data throughput measured at the medium access control layer. This article investigates the key MAC enhancements that help 802.11n achieve high throughput and high efficiency. A detailed description is given for various frame aggregation mechanisms proposed in the latest 802.11n draft standard. Our simulation results confirm that A-MSDU, A-MPDU, and a combination of these methods improve extensively the channel efficiency and data throughput. We analyze the performance of each frame aggregation scheme in distinct scenarios, and we conclude that overall, the two-level aggregation is the most efficacious
Discovery of a Binary Centaur
We have identified a binary companion to (42355) 2002 CR46 in our ongoing
deep survey using the Hubble Space Telescope's High Resolution Camera. It is
the first companion to be found around an object in a non-resonant orbit that
crosses the orbits of giant planets. Objects in orbits of this kind, the
Centaurs, have experienced repeated strong scattering with one or more giant
planets and therefore the survival of binaries in this transient population has
been in question. Monte Carlo simulations suggest, however, that binaries in
(42355) 2002 CR46 -like heliocentric orbits have a high probability of survival
for reasonable estimates of the binary's still-unknown system mass and
separation. Because Centaurs are thought to be precursors to short period
comets, the question of the existence of binary comets naturally arises; none
has yet been definitively identified. The discovery of one binary in a sample
of eight observed by HST suggests that binaries in this population may not be
uncommon.Comment: 20 pages, 4 figures, 1 table accepted for publication in Icaru
Letters between C. Larsen and William Kerr\u27s secretary
Letters concerning a position in the modern languages department at Utah Agricultural College
Effective Critical Exponents for Dimensional Ccrossover and Quantum Systems from an Environmentally Friendly Renormalization Group
Series for the Wilson functions of an ``environmentally friendly''
renormalization group are computed to two loops, for an vector model, in
terms of the ``floating coupling'', and resummed by the Pad\'e method to yield
crossover exponents for finite size and quantum systems. The resulting
effective exponents obey all scaling laws, including hyperscaling in terms of
an effective dimensionality, {d\ef}=4-\gl, which represents the crossover in
the leading irrelevant operator, and are in excellent agreement with known
results.Comment: 10 pages of Plain Tex, Postscript figures available upon request from
[email protected], preprint numbers THU-93/18, DIAS-STP-93-1
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