2,256 research outputs found
Quantitying the Effects of Traffic Calming on Emissions Using on-road Measurement
The objective of this work was to determine the effect of
one form of traffic calming on emissions. Traffic calming
is aimed at reducing average vehicle speeds, especially
in residential neighborhoods, often using physical road
obstructions such as speed bumps, but it also results in
a higher number of acceleration/deceleration events
which in turn yield higher emissions. Testing was
undertaken by driving a warmed-up Euro-1 spark ignition
passenger car over a set of speed bumps on a level
road, and then comparing the emissions output to a noncalmed
level road negotiated smoothly at a similar
average speed. For the emissions measurements, a
novel method was utilized, whereby the vehicle was
fitted with a portable Fourier Transform Infrared (FTIR)
spectrometer, capable of measuring up to 51 different
components in real-time on the road. The results
showed that increases in emissions were much greater
than was previously reported by other researchers using
different techniques. When traffic-calmed results were
compared to a smooth non-calmed road, there were
substantial increases in CO2 (90%), CO (117%), NOx
(195%) and THC (148%). These results form the basis
for a good argument against traffic calming using speed
bumps, especially for aggressive drivers. Slowing traffic
down with speed restrictions enforced by speed
cameras is a more environmentally friendly option
Evaluation of a FTIR Emission Measurement System for Legislated Emissions Using a SI Car
A series of chassis dynamometer test trials were
conducted to assess the performance of a Fourier
Transform Infra Red (FTIR) system developed for
on-road vehicle exhaust emissions measurements.
Trials used a EURO 1 emission compliant SI passenger
car which, alongside the FTIR, was instrumented to
allow the routine logging of engine speed, road speed,
throttle position, air-fuel ratio, air flow and fuel flow in
addition to engine, exhaust and catalyst temperatures.
The chassis dynamometer facility incorporated an
‘industry standard’ measurement system comprising
MEXA7400 gas analyzer and CVS bag sampling which
was the ‘benchmark’ for the evaluation of FTIR
legislated gas-phase emissions (CO, NOx, THC and
CO2) measurements.
Initial steady state measurements demonstrated strong
correlations for CO, NOx and THC (R2 of 0.99, 0.97
0.99, respectively) and a good correlation for CO2 (R2 =
0.92). Subsequent transient and total mass emissions
measurements from replicate samplings of four different
driving cycles (two standard cycles, FTP75 and NEDC,
and two novel cycles based on real-world data collected
in Leeds) also show good response of FTIR and
satisfied agreement between the FTIR and CVS bag
sampling measurements.
In general, the trial results demonstrate that the
on-board FTIR emission measurement system provides
reliable in-journey emissions data
From Quasars to Extraordinary N-body Problems
We outline reasoning that led to the current theory of quasars and look at
George Contopoulos's place in the long history of the N-body problem. Following
Newton we find new exactly soluble N-body problems with multibody forces and
give a strange eternally pulsating system that in its other degrees of freedom
reaches statistical equilibrium.Comment: 13 pages, LaTeX with 1 postscript figure included. To appear in
Proceedings of New York Academy of Sciences, 13th Florida Workshop in
Nonlinear Astronomy and Physic
Most Complex Regular Right-Ideal Languages
A right ideal is a language L over an alphabet A that satisfies L = LA*. We
show that there exists a stream (sequence) (R_n : n \ge 3) of regular right
ideal languages, where R_n has n left quotients and is most complex under the
following measures of complexity: the state complexities of the left quotients,
the number of atoms (intersections of complemented and uncomplemented left
quotients), the state complexities of the atoms, the size of the syntactic
semigroup, the state complexities of the operations of reversal, star, and
product, and the state complexities of all binary boolean operations. In that
sense, this stream of right ideals is a universal witness.Comment: 19 pages, 4 figures, 1 tabl
Service-oriented simulation using web ontology
Copyright © 2012 Inderscience Enterprises Ltd.Commercial-off-the-Shelf (COTS) Simulation Packages (CSPs) have proved popular in a wider industrial setting. Reuse of Simulation Component (SC) models by collaborating organisations or divisions is restricted, however, by the same semantic issues that restrict the inter-organisation use of other software services. Semantic models, in the form of ontology, utilised by a web-service-based discovery and deployment architecture provide one approach to support simulation model reuse. Semantic interoperation is achieved using domain-grounded SC ontology to identify reusable components and subsequently loaded into a CSP, and locally or remotely executed. The work is based on a health service simulation that addresses the transportation of blood. The ontology-engineering framework and discovery architecture provide a novel approach to inter-organisation simulation, uncovering domain semantics and providing a less intrusive mechanism for component reuse. The resulting web of component models and simulation execution environments present a nascent approach to simulation grids
Flat Information Geometries in Black Hole Thermodynamics
The Hessian of either the entropy or the energy function can be regarded as a
metric on a Gibbs surface. For two parameter families of asymptotically flat
black holes in arbitrary dimension one or the other of these metrics are flat,
and the state space is a flat wedge. The mathematical reason for this is traced
back to the scale invariance of the Einstein-Maxwell equations. The picture of
state space that we obtain makes some properties such as the occurence of
divergent specific heats transparent.Comment: 14 pages, one figure. Dedicated to Rafael Sorkin's birthda
Effects of dietary protein and fat level and rapeseed oil on growth and tissue fatty acid composition and metabolism in Atlantic salmon (Salmo salar L.) reared at low water temperatures
A 12 week feeding trial was conducted to elucidate the interactive effects of dietary fat and protein contents and oil source on growth, fatty acid composition, protein retention efficiency (PRE) and β-oxidation activity of muscle and liver in Atlantic salmon (Salmo salar L.) at low water temperatures (4.2 oC). Triplicate groups of Atlantic salmon (initial weight 1168 g) were fed six isoenergetic diets formulated to provide either 390 g kg-1 protein and 320 g kg-1 fat (high protein (HP) diets) or 340 g kg-1 protein and 360 g kg-1 fat (low protein (LP) diets); within each dietary protein/fat level crude RO comprised 0, 30 or 60% (R0, R30, R60, respectively) of the added oil. After 12 weeks the overall growth and FCR were very good for all treatments (TGC; 4.76 (±0.23), FCR; 0.85 (±0.02)). Significant effects were shown due to oil source on SGR and TGC only. The liver and muscle FA compositions were highly affected by the graded inclusion of RO. The PRE was significantly affected by the dietary protein level, while no significant effects were shown in total β-oxidation capacity of liver and muscle. The results of this study suggest that more sustainable, lower protein diets with moderate RO inclusion can be used in Atlantic salmon culture at low water temperatures with no negative effects on growth and feed conversion, no major detrimental effects on lipid and fatty acid metabolism and a positive effect on protein sparing
The mass-to-light ratio of rich star clusters
We point out a strong time-evolution of the mass-to-light conversion factor
eta commonly used to estimate masses of unresolved star clusters from observed
cluster spectro-photometric measures. We present a series of gas-dynamical
models coupled with the Cambridge stellar evolution tracks to compute
line-of-sight velocity dispersions and half-light radii weighted by the
luminosity. We explore a range of initial conditions, varying in turn the
cluster mass and/or density, and the stellar population's IMF. We find that
eta, and hence the estimated cluster mass, may increase by factors as large as
3 over time-scales of 50 million years. We apply these results to an hypothetic
cluster mass distribution function (d.f.) and show that the d.f. shape may be
strongly affected at the low-mass end by this effect. Fitting truncated
isothermal (Michie-King) models to the projected light profile leads to
over-estimates of the concentration parameter c of delta c ~ 0.3 compared to
the same functional fit applied to the projected mass density.Comment: 6 pages, 2 figures, to appear in the proceedings of the "Young
massive star clusters", Granada, Spain, September 200
Doppler-free frequency modulation spectroscopy of atomic erbium in a hollow cathode discharge cell
The erbium atomic system is a promising candidate for an atomic Bose-Einstein
condensate of atoms with a non-vanishing orbital angular momentum ()
of the electronic ground state. In this paper we report on the frequency
stabilization of a blue external cavity diode laser system on the 400.91
laser cooling transition of atomic erbium. Doppler-free saturation spectroscopy
is applied within a hollow cathode discharge tube to the corresponding
electronic transition of several of the erbium isotopes. Using the technique of
frequency modulation spectroscopy, a zero-crossing error signal is produced to
lock the diode laser frequency on the atomic erbium resonance. The latter is
taken as a reference laser to which a second main laser system, used for laser
cooling of atomic erbium, is frequency stabilized
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