5,725 research outputs found
Comparative analysis on strains in asphalt pavement design using linear elastic and viscoelastic theories
In Colombia it is common to design pavements using the AASHTO 93 method and to complement it with an elastic analysis of the deformations that cause fatigue and rutting; this has repercussions on the behavior of the structure since it does not take into account the viscoelastic behavior of the asphalt mixtures, In this research, a comparison of three structures at different velocity ranges is made to compare the variation in fatigue and rutting concerning the traditional method of analysis in Colombia and to analyze the differences that may occur in linear elastic analysis and viscoelastic analysis of rutting and fatigue
Fiscal policy shocks in the euro area and the US : an empirical assessment
We analyse the impact of fiscal policy shocks in the euro area as a whole, using a newly available quarterly dataset of fiscal variables for the period 1981-2007. To allow for comparability with previous results on euro area countries and the US, we use a standard structural VAR framework, and study the impact of aggregated and disaggregated government spending and net taxes shocks. In addition, to frame euro area results, we apply the same methodology for the same sample period to US data. We also explore the sensitivity of the provided results to the inclusion of variables aiming at measuring "financial stress" (increases in risk) and "fiscal stress" (sustainability concerns). Analysing US and euro area data with a common methodology provides some interesting insights on the interpretation of fiscal policy shock
Consumers’ preferences and willingness to pay for fish products with health and environmental labels: Evidence from five european countries
Seafood products are important sources of protein and components of a healthy and sustainable diet. Understanding consumers’ preferences for fish products is crucial for increasing fish consumption. This article reports the consumer preferences and willingness to pay (WTP) for different fish species and attributes on representative samples in five European countries (n = 2509): France, Germany, Italy, Spain, and the UK. Consumer choices were investigated for fresh fish in a retail market under hypothetical situations arranged by a labelled choice experiment conducted for seven fish species: Cod, herring, seabass, seabream, salmon, trout, and pangasius. The results show the highest premiums for wild-caught fish than farm-raised alternatives. Ready-to-cook products are generally preferred to whole fish, whereas fish fillet preference is more species-specific. The results show positive premiums for a sustainability label and nutrition and health claims, with high heterogeneity across countries and species. With consumers’ preferences and WTP being largely country-and fish-dependent, businesses (fish companies, retailers, and others) should consider the specific market context and adapt their labelling strategies accordingly. Public authorities campaigns should inform consumers about the tangible benefits related with health and environmental labels
Non-imaging Optics for LED-Lighting
In this report, several methods are investigated to rapidly compute the light intensity function, either in the far field or on a finite-distance screen, of light emanating from a light fixture with a given shape. Different shapes are considered, namely polygonal and (piecewise) smooth. In the first case, analytic methods are sought to circumvent the use of Monte Carlo methods and ray-tracing with large sample size. In the second case, refinements of the Monte Carlo method (notably using a bootstrap procedure) are devised to minimize the number of samples needed for a good approximation of the intensity function
Non-imaging optics for LED-lighting
In this report, several methods are investigated to rapidly compute the light intensity function, either in the far field or on a finite-distance screen, of light emanating from a light fixture with a given shape. Different shapes are considered, namely polygonal and (piecewise) smooth. In the first case, analytic methods are sought to circumvent the use of Monte Carlo methods and ray-tracing with large sample size. In the second case, refinements of the Monte Carlo method (notably using a bootstrap procedure) are devised to minimize the number of samples needed for a good approximation of the intensity function
Nonradial and nonpolytropic astrophysical outflows IX. Modeling T Tauri jets with a low mass-accretion rate
Context: A large sample of T Tauri stars exhibits optical jets, approximately
half of which rotate slowly, only at ten per cent of their breakup velocity.
The disk-locking mechanism has been shown to be inefficient to explain this
observational fact.
Aims: We show that low mass accreting T Tauri stars may have a strong stellar
jet component that can effectively brake the star to the observed rotation
speed.
Methods: By means of a nonlinear separation of the variables in the full set
of the MHD equations we construct semi- analytical solutions describing the
dynamics and topology of the stellar component of the jet that emerges from the
corona of the star.
Results: We analyze two typical solutions with the same mass loss rate but
different magnetic lever arms and jet radii. The first solution with a long
lever arm and a wide jet radius effectively brakes the star and can be applied
to the visible jets of T Tauri stars, such as RY Tau. The second solution with
a shorter lever arm and a very narrow jet radius may explain why similar stars,
either Weak line T Tauri Stars (WTTS) or Classical T Tauri Stars (CTTS) do not
all have visible jets. For instance, RY Tau itself seems to have different
phases that probably depend on the activity of the star.
Conclusions: First, stellar jets seem to be able to brake pre-main sequence
stars with a low mass accreting rate. Second, jets may be visible only part
time owing to changes in their boundary conditions. We also suggest a possible
scenario for explaining the dichotomy between CTTS and WTTS, which rotate
faster and do not have visible jets
Bosonizing one-dimensional cold atomic gases
We present results for the long-distance asymptotics of correlation functions
of mesoscopic one-dimensional systems with periodic and open (Dirichlet)
boundary conditions, as well as at finite temperature in the thermodynamic
limit. The results are obtained using Haldane's harmonic-fluid approach (also
known as ``bosonization''), and are valid for both bosons and fermions, in
weakly and strongly interacting regimes. The harmonic-fluid approach and the
method to compute the correlation functions using conformal transformations are
explained in great detail. As an application relevant to one-dimensional
systems of cold atomic gases, we consider the model of bosons interacting with
a zero-range potential. The Luttinger-liquid parameters are obtained from the
exact solution by solving the Bethe-ansatz equations in finite-size systems.
The range of applicability of the approach is discussed, and the prefactor of
the one-body density matrix of bosons is fixed by finding an appropriate
parametrization of the weak-coupling result. The formula thus obtained is shown
to be accurate, when compared with recent diffusion Montecarlo calculations,
within less than 10%. The experimental implications of these results for Bragg
scattering experiments at low and high momenta are also discussed.Comment: 39 pages + 14 EPS figures; typos corrected, references update
Distrito de transferencia de tecnología - Pamplona : resumen operativo gerencial y programación
El resumen operativo gerencial es una herramienta eficaz para vincular la etapa de formulación de un proyecto con la ejecución del mismo. Se elabora en case a las directrices establecidas en el documento del proyecto y constituye un instrumento operativo ajustado alas condiciones imperantes en el área de influencia al momento de la ejecución, facilitando el seguimiento y la evaluación. Además presenta una visión de conjunto clara y cuantificada de los objetivos y metas que se persiguen, favoreciendo el logro de una adecuada gestión. También es útil para formular proyectos bien diseñados, realistas y evaluables simplificando el proceso de detectar errores de diseño. En este documento se presenta un resumen operativo gerencial y el plan de implementación de los proyectos que conforman el distrito de transferencia tecnológica - Pamplona. A saber: fortalecimiento al sistema de transferencia de tecnología; comercialización; alimentación y nutriciónInstituto Interamericano de Cooperación para la Agricultura - IIC
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