3,157 research outputs found
LEF2 - A strategic freight transport model for Great Britain.
INTRODUCTION
This paper reports some innovative model building that yields a useful addition to models of freight in Great Britain. Currently, the Great Britain Freight Model (GBFM) is part of the Department for Transport's (DtT) national
model suite. That model is over-detailed for some purposes and internally only models mode choice effects. Freight modelling requirements in Great Britain were reviewed in work for the DtT, the Strategic Rail Authority (SRA), the
Highways Agency (HA) and Transport for London (TfL). Arising from our work on that project, and our involvement with GBFM, we identified a need for a strategic freight transport model, near instantaneous to run, that could handle both the mode choice effects and market size effects of policies. Section 2 of this paper sets out the background to our work. Section 3 introduces the LEeds Freight Transport (LEFT) model series. Section 4
describes the model LEFT2 from that series, and section 5 gives some results using version LEFT2.6. Section 6 lists the plans we currently have for LEFT3, and section 7 concludes
Long Distance Business Travel and Mode Choice: The Results of Two Surveys of Business Travellers.
This report contains a descriptive analysis of two UK samples of lomg distance business travellers. Each sample answered the same mailback quesitonnaire which asked for detailed information about a recent long distance business trip and a limited amount of socio-economic data from each respondent. In particular; questions were asked about reasons for choice of the main travel mode and the alternative modes available to the respondent. In both samples it was found that the main factors influencing mode choices were journeytime and a convenient start time; with the ability to work en route being a significant factor for rail travellers. Company travel policies did not appear to have a significant influence on mode choice; although the set of permitted alternative modes was dependent on the respondents' income and occupation
The Development of the LEFT2 Model
Construction of the LEeds Freight Transport Model (LEFT) series was begun as part of the
ITeLS project, although other funding has helped and will take forward its development. The
initial version, now referred to by us as LEFT1, was a simple mode split model intended to
give a rough idea of the magnitudes of the effects of various scenarios, possibly as a way of
filtering which scenarios might be investigated using more detailed models. Besides being
limited to mode split, LEFT1 suffered from a range of minor defects and deficiencies which
led to its abandonment in favour of its successor, LEFT2.
LEFT2 was constructed in 2004 as part of the Engineering and Physical Sciences Research
Council LINK FIT project, ITeLS, funded by the Department for Transport (DfT). We
acknowledge here the help and useful comments from many persons associated with that
project. Besides mode split effects, LEFT2 allows scenarios to alter the total size of the (road
plus rail) market. Its purpose is to provide instantaneous ballpark estimates of road and rail
freight tonne kilometres under various ‘scenarios’. At its base is a desire that the scenarios
should not affect the sum of tonnes moved by both road and rail modes. This was because we
felt that our scenarios should be viewed as having a neutral macroeconomic effect. For
example, if taxes on lorry usage were increased, we would expect other taxes to be lower
than otherwise (or government spending to increase) so that total demand in the economy
would not change. Consumers might buy their goods from closer sources than hitherto, but
they would not be expected to consume less in total. For example, if prices of some goods
rose slightly due to higher road user charges, the consumer would have more to spend due to
offsetting reduced income tax (or whatever) and much the same total quantity would be
bought. Similarly, industrialists as a whole might find input prices increasing slightly, but
will find they can charge slightly more for their outputs.
In summary, LEFT2 provides an instantaneous estimate of the effect of macroeconomically
neutral scenarios on mode split (road, trainload and wagonload), average length of haul and
total market size.
LEFT2 does not load the traffic onto vehicles, and so does not produce magnitudes of HGV
vehicle kilometres, for instance. Consequently it does not produce estimates of emissions or
other nuisances. It is hoped that a future version of LEFT can incorporate these elements and
revisit the other matters that have had to be ‘parked’ for the present. LEFT2 gives a quick
idea of the magnitudes of the effects of any policies that might be considered and should help
to provide a first sift where many policies are being considered.
This report describes the basic LEFT Methodology in Section 2. Emphasis is given to that
methodology actually embodied in LEFT2, but there is also some discussion of rejected
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methodologies, and some that have had to be held over for later versions of LEFT. Section 3
presents additional data that was needed by the LEFT2 model. Section 4 describes the
scenarios chosen for testing in the ITeLS project, while section 5 gives the first results from
using the LEFT2 model, for those scenarios
The Emergence of Correlations in Studies of Global Economic Inter-dependence and Contagion
We construct a simple firm-based automata model for global economic inter-dependence of countries using modern notions of self-organized criticality and recently developed dynamical-renormalization-group methods (e.g., L. Pietronero et al., Phys. Rev. Lett., 72(11):1690 (1994); J. Hasty and K. Wiesenfeld, Phys. Rev. Lett., 81(8):1722, (1998)). We demonstrate how extremely strong statistical correlations can naturally develop between two countries even if the financial interconnections between those countries remain very weak. Potential policy implications of this result are also discussed.
Transmission of PhC coupled-resonator waveguide (PhCCRW) structure enhanced via mode matching
A method for increasing the coupling efficiency between ridge optical waveguides and PhCCRWs is described. This increase is achieved via W1 channel waveguide sections, formed within a two-dimensional triangular lattice photonic crystal using mode-matching. The mode-matching is achieved by low quality-factor modified cavities added to both the input and output ports of the PhCCRW. A three dimensional finite-difference time-domain method has been used to simulate light propagation through the modified PhCCRW. We have fabricated PhCCRWs working at 1.5µm in silicon-on-insulator material. Measurements and simulations show that the overall transmission is improved by a factor of two
de-Broglie Wave-Front Engineering
We propose a simple method for the deterministic generation of an arbitrary
continuous quantum state of the center-of-mass of an atom. The method's spatial
resolution gradually increases with the interaction time with no apparent
fundamental limitations. Such de-Broglie Wave-Front Engineering of the atomic
density can find applications in Atom Lithography, and we discuss possible
implementations of our scheme in atomic beam experiments.Comment: The figures' quality was improved, the text remains intact. 5 pages,
3 figures; submitted to PR
Initial beam-profiling tests with the NML prototype station at the Fermilab A0 Photoinjector
The beam-profile diagnostics station prototype for the superconducting rf
electron linac being constructed at Fermilab at the New Muon Lab has been
tested. The station uses intercepting radiation converter screens for the
low-power beam mode: either a 100-\mu m thick YAG:Ce single crystal
scintillator or a 1-\mu m thin Al optical transition radiation (OTR) foil. The
screens are oriented with the surface perpendicular to the beam direction. A
downstream mirror with its surface at 45 degrees to the beam direction is used
to direct the radiation into the optical transport. The optical system has
better than 20 (10) \mu m rms spatial resolution when covering a vertical field
of view of 18 (5) mm. The initial tests were performed at the A0 Photoinjector
at a beam energy of ~15 MeV and with micropulse charges from 25 to 500 pC for
beam sizes of 45 to 250 microns. Example results will be presented.Comment: 3 pp. Particle Accelerator, 24th Conference (PAC'11) 2011. 28 Mar - 1
Apr 2011. New York, US
Effect of exogenous melatonin on antioxidant defense system and osmo-regulatory solutes of drought-stressed Morinda citrifolia
Morinda citrifolia is a small tropical tree that contains active natural metabolites in its leaves, stem, roots, and fruits. Despite these properties, drought stress has always been one of the limiting factors affecting its growth and productivity. This study investigated the role of melatonin in the regeneration of M. citrifolia in vitro under simulated drought stress. Nodal cuttings of six-month-old M. citrifolia were inoculated into Murashige and Skoog (MS) media supplemented with 2, 4-dichlorophenoxy-acetic acid (0.5 mg/L), indole acetic acid (0.5 mg/L) and varying concentrations of melatonin (0 μM, 50 μM and 100 μM) and polyethylene glycol (PEG) 6000 (0%, 20% and 40%). M. citrifolia experienced a significant increase in plant growth, stabilized chlorophyll contents, superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities under drought stress possibly because it is a drought-tolerant plant. However, melatonin was involved in the accumulation of proline and ascorbic acid at 20% PEG. Osmoregulation of solutes stimulated and stabilized the production of catalase, GPx, and SOD activities. Upregulation of glutathione S-transferase augmented the biosynthesis of glutathione during drought stress. Also, a high accumulation of carotenoid function as photo-protectants and shields chlorophyll contents from drought-induced reactive oxygen species. Consequently, 40% of hydrogen peroxide was detoxified and plant growth was boosted. Therefore, melatonin acts as a stimulant of carotenoid, compatible solutes, enzymatic and non-enzymatic anti-oxidant defensive system, protects plants against oxidative injury, and boosted the growth of Morinda. citrifolia in vitro under drought stress
Determination of work index of graphite from Samanburkono (Nigeria) using modified bond's method
This report covers the work index determination of Saman-Burkono graphite. The test sample was obtained from Saman-Burkono in Ningi Local Government Area of Bauchi state, while reference material (coal) was sourced from Okaba coal mine, Ankpa Local Government Area of Kogi State. A known weight of graphite sample and coal were crushed, pulverized and ground using the laboratory milling machine. The two samples were grinded with two cells of diameter 3.5cm and 222g weight. The analysis of the feed size fort the two samples was found graphically to be 180μm and 175μm, and ball mill discharge was 130μm and 140μm respectively. The work index of a coal as reference material was 7.65 kWh/ short ton, this was used to calculate the work index of the graphite which was found to be 11.047 kWh/short ton, being the required energy to comminute one ton of graphite.Keywords: Comminution, Graphite, Saman-Burkono, Nigeria, Modified Bonds metho
Multipole (E1, M1, E2, M2, E3, M3) transition wavelengths and rates between 3l5l' excited and ground states in nickel-like ions
A relativistic many-body method is developed to calculate energy and
transition rates for multipole transitions in many-electron ions. This method
is based on relativistic many-body perturbation theory (RMBPT), agrees with
MCDF calculations in lowest-order, includes all second-order correlation
corrections and includes corrections from negative energy states. Reduced
matrix elements, oscillator strengths, and transition rates are calculated for
electric-multipole (dipole (E1), quadrupole (E2), and octupole (E3)) and
magnetic-multipole (dipole (M1), quadrupole (M2), and octupole (M3))
transitions between 3l5l' excited and ground states in Ni-like ions with
nuclear charges ranging from Z = 30 to 100. The calculations start from a
1s22s22p63s23p63d10} Dirac-Fock potential. First-order perturbation theory is
used to obtain intermediate-coupling coefficients, and second-order RMBPT is
used to determine the matrix elements. A detailed discussion of the various
contributions to the dipole matrix elements and energy levels is given for
nickellike tungsten (Z = 74). The contributions from negative-energy states are
included in the second-order E1, M1, E2 M2, E3, and M3 matrix elements. The
resulting transition energies and transition rates are compared with
experimental values and with results from other recent calculations. These
atomic data are important in modeling of M-shell radiation spectra of heavy
ions generated in electron beam ion trap experiments and in M-shell diagnostics
of plasmas.Comment: 21 pages, 8 figures, 11 table
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