17,364 research outputs found
Liverpool Central School District and Liverpool Association of Middle Managers
In the matter of the fact-finding between the Liverpool Central School District, employer, and the Liverpool Association of Middle Managers, union. PERB case no. M2010-362. Before: Peter A. Korn, fact finder
On transcendental numbers: new results and a little history
Attempting to create a general framework for studying new results on
transcendental numbers, this paper begins with a survey on transcendental
numbers and transcendence, it then presents several properties of the
transcendental numbers and , and then it gives the proofs of new
inequalities and identities for transcendental numbers. Also, in relationship
with these topics, we study some implications for the theory of the Yang-Baxter
equations, and we propose some open problems.Comment: 8 page
Long-period intensity pulsations in the solar corona during activity cycle 23
We report on the detection (10 \sigma) of 917 events of long-period (3 to 16
hours) intensity pulsations in the 19.5 nm passband of the SOHO Extreme
ultraviolet Imaging Telescope. The data set spans from January 1997 to July
2010, i.e the entire solar cycle 23 and the beginning of cycle 24. The events
can last for up to six days and have relative amplitudes up to 100%. About half
of the events (54%) are found to happen in active regions, and 50% of these
have been visually associated with coronal loops. The remaining 46% are
localized in the quiet Sun. We performed a comprehensive analysis of the
possible instrumental artifacts and we conclude that the observed signal is of
solar origin. We discuss several scenarios which could explain the main
characteristics of the active region events. The long periods and the
amplitudes observed rule out any explanation in terms of magnetohydrodynamic
waves. Thermal nonequilibrium could produce the right periods, but it fails to
explain all the observed properties of coronal loops and the spatial coherence
of the events. We propose that moderate temporal variations of the heating term
in the energy equation, so as to avoid a thermal nonequilibrium state, could be
sufficient to explain those long-period intensity pulsations. The large number
of detections suggests that these pulsations are common in active regions. This
would imply that the measurement of their properties could provide new
constraints on the heating mechanisms of coronal loops.Comment: 10 pages, 4 figure
Statistical approach to optimization of the transesterification reaction from sorrel (hibiscus sabdariffa) oil
In an effort to optimize the reaction conditions of biodiesel production from Sorrel seed oil, Response
Surface Methodology (RSM) was applied and the effects of reaction temperature, catalyst amount,
reaction time and methanol/oil molar ratio, and their reciprocal interactions were ascertained. A total
of 30 experimental runs were designed by Central Composite Rotatable Design (CCRD) and carried
out. A quadratic polynomial was obtained for predicting the Transesterification process and the
ANOVA test showed the model to be significant (p<0.05). The validity of the predicted model was
confirmed by carrying out three independent replicates experiments. The actual maximum biodiesel
yield obtained was 99.23% (w/w) at methanol/oil molar ratio 6.21, catalyst amount 1.03 (% wt.),
reaction temperature 51 oC, and reaction time 63 min. The fuel properties of Hibiscus sabdariffa
methylester (HSME) produced were found to be within the ASTM D6751 and DIN EN 14214 biodiesel
standards. The fatty acid profile of the HSME revealed that the dominant fatty acids were oleic
(58.34%), arachidic (1.55%), palmitic (18.28%) and linoleic (21.19%). Emission assessment revealed
70% reduction of CO at B80, 80% reduction of NO concentration at B40
A study of industrial hydrogen and syngas supply systems
The potential and incentives required for supplying hydrogen and syngas feedstocks to the U.S. chemical industry from coal gasification systems were evaluated. Future hydrogen and syngas demand for chemical manufacture was estimated by geographic area and projected economics for hydrogen and syngas manufacture was estimated with geographic area of manufacture and plant size as parameters. Natural gas, oil and coal feedstocks were considered. Problem areas presently affecting the commercial feasibility of coal gasification discussed include the impact of potential process improvements, factors involved in financing coal gasification plants, regulatory barriers affecting coal gasification, coal mining/transportation, air quality regulations, and competitive feedstock pricing barriers. The potential for making coal gasification the least costly H2 and syngas supply option. Options to stimulate coal gasification system development are discussed
Coherent pairing states for the Hubbard model
We consider the Hubbard model and its extensions on bipartite lattices. We
define a dynamical group based on the -pairing operators introduced by
C.N.Yang, and define coherent pairing states, which are combinations of
eigenfunctions of -operators. These states permit exact calculations of
numerous physical properties of the system, including energy, various
fluctuations and correlation functions, including pairing ODLRO to all orders.
This approach is complementary to BCS, in that these are superconducting
coherent states associated with the exact model, although they are not
eigenstates of the Hamiltonian.Comment: 5 pages, RevTe
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