603 research outputs found
Preliminary Neutral Current Results from Caltech-Fermilab
No full textThe Caltech-Fermilab experiment is completing the analysis of neutral current data taken about one year ago. This experiment was carried out about a year ago by the following people: B. Barish, K. W. Brown, A. Bodek, D. Buchholz, E. Fisk, G. Krafczyk, F. Merritt, F. Sciulli, L. Stutte, and H. Suter. The final results should be forthcoming in the next few weeks. This communication is a status report on that analysis
Primary-school class composition and the development of social capital
No full textWe study the development of social capital through adult civic engagement, in relation to social capital exposure having occurred during childhood based on experiences outside the family at primary school. We assume that the types of classmates in attendance at a child's school would have influenced her/his social capital. To identify the types of classmates, we take advantage of the heterogeneity in the ability levels of British primary-school classes during the 1960s. At that time, some schools were practicing a method of streaming, whereas others were not. Using British National Child Development data, we construct a single score of civic engagement and evaluate the effect on adult civic engagement of attending homogeneous-ability classes versus nonhomogeneous-ability classes and being in high-, average- or low-ability classes when enrolled in streamed schools. Our results show that children who were grouped in homogeneous-ability classes developed a lower interest in civic engagement than their peers who attended mixed-ability classes (nonstreamed schools). Moreover, among children who attended streamed schools, a lower attitude toward civic engagement was observed among low-ability students. Thus, streaming appears to be detrimental to social capital development, especially for low-ability individuals
Vegetable oils as fuels in Diesel engine. Engine performance and emissions
No full textThe EU new energy strategy represents a challenge and a boost for industries and researchers pushing them to find new solutions to supply the energy demand complying with new environmental requests. The transport sector is one of the most addicted to oil product and then pollutant. A new bio-fuels generation is being studied, but the use of the ones already available should be increased. The use of vegetable oils (VO) and waste cooking oils (WCO) could represent interesting alternative fuels for Diesel engines in some specific applications (i.e., public transportation, hybrid or marine propulsion, etc.). Moreover, VO can be produced almost everywhere in the world in relatively small plants, and WCO would represent the use of a waste material which otherwise should be disposed. However, operating a Diesel engine (DE) with a different fuel might results in some problems. Indeed VO and WCO have different characteristics compared to Diesel fuel (i.e, a smaller heating value, a larger density and viscosity), and this can affect the operation of a DE. In particular the DE is expected to have some problem at the injection system and power loss. In this work different vegetable oils (both straight and waste) are used to fuel a DE in automotive configuration and study its behavior. Tests are performed using a turbocharged, four stroke, four cylinders, water cooled, common-rail multijet DE. The influence of fuel used on engine power, specific consumption, efficiency, and exhaust opacity, are compared with those obtained fuelling with Diesel fuel. © 2014 The Authors. Published by Elsevier Ltd
Straight vegetable oil as fuel in an internal combustion engine for power and heat production
No full textTemporary contracts and young workers’ job satisfaction in Italy
No full textThe Italian process of flexibilization of the labour market has created a dual market populated by protected permanent employees and unprotected temporary workers. The latter comprises not only temporary employment relationships but also autonomous collaborations used by firms as low-cost de facto temporary employment relationships. Little is known about the quality of these temporary jobs, particularly widespread among young workers. We estimate a regression model of perceived overall job satisfaction of young workers, based on the ISFOL-PLUS 2006-2008-2010 panel. We control for the various temporary contracts and for perceived satisfactions in nine aspects of the job. We find that lack of job stability is the most serious cause of lower satisfaction for both temporary employees and autonomous collaborators. But while temporary employees compensate concerns of job stability with other job aspects, attaining satisfaction levels comparable to those of permanent employees, autonomous collaborators do not and are thus significantly the least satisfied
Modeling of rain drop erosion in a multi-MW wind turbine
No full textThe actual strategy in offshore wind energy development is
oriented to the progressive increase of the characteristic turbine
diameter as such of the per unit power. Among many pioneering
technological and aerodynamic issues linked to this design trend,
the wind velocity at the blade tip region reaches very high values
in normal operating conditions (typically between 90 to 110
m/s). In this range of velocity, the rain erosion phenomenon can
have a relevant effect on the overall turbine performance in terms
of power and energy production (up to 20% loss in case of deeply
eroded leading edge). Therefore, as a customary approach
erosion related issues are accounted for in the scheduling of the
wind turbine maintenance. When off-shore, on the other hand,
the criticalities inherent to the cost of maintenance and operation
monitoring suggest the rain erosion concerns to be tackled at the
turbine design stage. In so doing, the use of computational tools
to study the erosion phenomenon of wind turbines under severe
meteorological conditions could define the base-line approach in
the wind turbine blades design and verification.
In this work, the authors present a report on numerical
prediction of erosion on a 6 MW HAWT (horizontal axis wind
turbine). Two different blade geometries of different
aerodynamic loading, have been studied in a view to explore
their sensitivity to rain erosion.
The fully 3D simulations are carried out using an Euler-
Lagrangian approach. Flow field simulations are carried out with
the open-source code OpenFOAM, based on a finite volume
approach, using Multiple Reference Frame methodology.
Reynolds Averaged Navier-Stokes equations for incompressible
steady flow were solved with a k-ε turbulence
Design of next generation snow gun fans
No full textMost of the skiing resorts normally use snow guns to ensure a suitable amount of artificial snow on ski tracks. The main component of a snow gun are a fan used to move the air and an atomizer to inject droplets of water in the main flow. Issues with these devices are (i) power requirements, between 10 and 30 kW for a single device (a complete track needing up to 100 snow guns) and (ii) acoustic emissions, typically above 80 dB due to the rotational speed comprised between 1500 and 3600 rpm. The paper describes the development of a family of next-generation snow gun to cover a wide range of applications. The design process is based on a methodology that combines Eulerian analysis, RANS computations and experiments
Nucleon Structure Functions from ν_µ-Fe Interactions and a Study of the Valence Quark Distribution
No full textData were taken in 1979-80 by the CCFRR high energy neutrino experiment at Fermilab. A total of 150,000 neutrino and 23,000 antineutrino charged current events in the approximate energy range 25 < Ev < 250 GeV are measured and analyzed. The structure functions F2 and xF3 are extracted for three assumptions about σL/σT: R = 0., R = 0.1 and R = a QCD based expression. Systematic errors are estimated and their significance is discussed. Comparisons or the X and Q2 behaviour or the structure functions with results from other experiments are made.
We find that statistical errors currently dominate our knowledge of the valence quark distribution, which is studied in this thesis. xF3 from different experiments has, within errors and apart from level differences, the same dependence on x and Q2, except for the HPWF results. The CDHS F2 shows a clear fall-off at low-x from the CCFRR and EMC results, again apart from level differences which are calculable from cross-sections.
The result for the the GLS rule is found to be 2.83 ± .15 ± .09 ± .10 where the first error is statistical, the second is an overall level error and the third covers the rest of the systematic errors. QCD studies of xF3 to leading and second order have been done. The QCD evolution of xF3, which is independent of R and the strange sea, does not depend on the gluon distribution and fits yield
ʌLO = 88+163-78 +113-70MeV
The systematic errors are smaller than the statistical errors. Second order fits give somewhat different values of ʌ, although αs (at Q20 = 12.6 GeV2) is not so different.
A fit using the better determined F2 in place of xF3 for x > 0.4 i.e., q = 0 in that region, gives
ʌLO = 266+114-104 +85-79MeV
Again, the statistical errors are larger than the systematic errors. An attempt to measure R was made and the measurements are described. Utilizing the inequality q(x) ≥ 0 we find that in the region x > .4 R is less than 0.55 at the 90% confidence level.</p
Correlazione tra aumentata secrezione di cortisolo e marker di infiammazione nei pazienti con sindromi coronariche acute
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