4,087 research outputs found
Real-world comparison of probe vehicle emissions and fuel consumption using diesel and 5 % biodiesel (B5) blend.
An instrumented EURO I Ford Mondeo was used to perform a real-world comparison of vehicle exhaust (carbon dioxide, carbon monoxide, hydrocarbons and oxides of nitrogen) emissions and fuel consumption for diesel and 5% biodiesel in diesel blend (B5) fuels. Data were collected on multiple replicates of three standardised on-road journeys: (1) A simple urban route; (2) A combined urban/inter-urban route; and, (3) An urban route subject to significant traffic management. At the total journey measurement level, data collected here indicate that replacing diesel with a B5 substitute could result in significant increases in both NOx emissions (8-13%) and fuel consumption (7-8%). However, statistical analysis of probe vehicle data demonstrated the limitations of comparisons based on such total journey measurements, i.e., methods analogous to those used in conventional dynamometer/drive cycle fuel comparison studies. Here, methods based on the comparison of speed/acceleration emissions and fuel consumption maps are presented. Significant variations across the speed/acceleration surface indicated that direct emission and fuel consumption impacts were highly dependent on the journey/drive cycle employed. The emission and fuel consumption maps were used both as descriptive tools to characterise impacts and predictive tools to estimate journey-specific emission and fuel consumption effects
Realizability of the Lorentzian (n,1)-Simplex
In a previous article [JHEP 1111 (2011) 072; arXiv:1108.4965] we have
developed a Lorentzian version of the Quantum Regge Calculus in which the
significant differences between simplices in Lorentzian signature and Euclidean
signature are crucial. In this article we extend a central result used in the
previous article, regarding the realizability of Lorentzian triangles, to
arbitrary dimension. This technical step will be crucial for developing the
Lorentzian model in the case of most physical interest: 3+1 dimensions.
We first state (and derive in an appendix) the realizability conditions on
the edge-lengths of a Lorentzian n-simplex in total dimension n=d+1, where d is
the number of space-like dimensions. We then show that in any dimension there
is a certain type of simplex which has all of its time-like edge lengths
completely unconstrained by any sort of triangle inequality. This result is the
d+1 dimensional analogue of the 1+1 dimensional case of the Lorentzian
triangle.Comment: V1: 15 pages, 2 figures. V2: Minor clarifications added to
Introduction and Discussion sections. 1 reference updated. This version
accepted for publication in JHEP. V3: minor updates and clarifications, this
version closely corresponds to the version published in JHE
The a-number of hyperelliptic curves
It is known that for a smooth hyperelliptic curve to have a large -number,
the genus must be small relative to the characteristic of the field, ,
over which the curve is defined. It was proven by Elkin that for a genus
hyperelliptic curve to have , the genus is bounded by
. In this paper, we show that this bound can be lowered to . The method of proof is to force the Cartier-Manin matrix to have rank one
and examine what restrictions that places on the affine equation defining the
hyperelliptic curve. We then use this bound to summarize what is known about
the existence of such curves when and .Comment: 7 pages. v2: revised and improved the proof of the main theorem based
on suggestions from the referee. To appear in the proceedings volume of Women
in Numbers Europe-
FDI Accounting in India and China: A Need for Harmonization
The objective of this paper is to initiate discussions on standardizing the method for measuring Foreign Direct Investment (FDI) across countries. It is important to use consistent method so that there is a faithful representation of a country\u27s investment climate and the information is relevant for the purpose of foreign investors. India and China measures Foreign Direct Investment (FDJ) using two different methods. India measures FDI on the basis of equity investments, whereas China includes certain items which do not strictly fall under the purview of FDI. Inclusion of items other than equity increases the reported FDI in China. It is presumed that overall higher reported FDI makes China appear more attractive than India. Our findings suggest that once adjustments for the definitionsare made, difference between the FDI in China and India decreases substantially
Soil‐Atmosphere Exchange and Mitigation of Nitrous Oxide and Methane Emissions in New Zealand\u27s Terrestrial Biosphere
Complete quantization of a diffeomorphism invariant field theory
In order to test the canonical quantization programme for general relativity
we introduce a reduced model for a real sector of complexified Ashtekar gravity
which captures important properties of the full theory. While it does not
correspond to a subset of Einstein's gravity it has the advantage that the
programme of canonical quantization can be carried out completely and
explicitly, both, via the reduced phase space approach or along the lines of
the algebraic quantization programme. This model stands in close correspondence
to the frequently treated cylindrically symmetric waves. In contrast to other
models that have been looked at up to now in terms of the new variables the
reduced phase space is infinite dimensional while the scalar constraint is
genuinely bilinear in the momenta. The infinite number of Dirac observables can
be expressed in compact and explicit form in terms of the original phase space
variables. They turn out, as expected, to be non-local and form naturally a set
of countable cardinality.Comment: 32p, LATE
Modelling Nitrous Oxide Emissions from Grazed Grasslands in New Zealand
Spatial and temporal variability are major difficulties when quantifying annual N2O fluxes at the field scale. New Zealand currently relies on the IPCC default methodology (National Inventory Report, 2004). This methodology is too simplistic and generalised as it ignores all site-specific controls, but is also not sufficiently flexible to allow mitigation options to be assessed. Therefore, a more robust, process-based approach is required to quantify N2O emissions more accurately at the field level. Denitrification-decomposition (DNDC) is a process-based model originally developed (Li et al., 1992) to quantify agricultural nitrous oxide (N2O) emissions across climatic zones, soil types, and management regimes. This has been modified to represent New Zealand grazed grassland systems (Saggar et al., 2004). More recent modifications include measured biomass C and N parameters in perennial pasture and compaction impacts on the soil water dynamics. Further validation tests have been conducted against observed soil moisture and gas fluxes. Here we i) assess the ability of a modified DNDC model NZ-DNDC to simulate N2O emissions; ii) compare the measured, modelled and IPCCestimated N2O emissions from dairy- and sheep-grazed pastures; and iii) give preliminary results for upscaling the model to provide preliminary regional emissions estimates
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