1,197 research outputs found
Electric Waterborne Public Transportation in Venice: a Case Study
The paper reports the results of a study for moving the present diesel-based watercraft propulsion technology used for public transportation in Venice city and lagoon to a more efficient and smart electric propulsion technology, in view of its adopted in a near future. Energy generation and storage systems, electrical machines and drives, as well as economic, environmental and social issues are presented and discussed. Some alternative solutions based on hybrid diesel engine and electric and full electric powertrains are compared in terms of weights, costs and payback times. Previews researches on ship propulsion and electric energy storage developed by the University of Padua and preliminary experiences on electric boats carried out in Venice lagoon by the municipal transportation company ACTV and other stakeholders are the starting point for this study. Results can be transferred to other waterborne mobility systems
Learning activation functions from data using cubic spline interpolation
Neural networks require a careful design in order to perform properly on a
given task. In particular, selecting a good activation function (possibly in a
data-dependent fashion) is a crucial step, which remains an open problem in the
research community. Despite a large amount of investigations, most current
implementations simply select one fixed function from a small set of
candidates, which is not adapted during training, and is shared among all
neurons throughout the different layers. However, neither two of these
assumptions can be supposed optimal in practice. In this paper, we present a
principled way to have data-dependent adaptation of the activation functions,
which is performed independently for each neuron. This is achieved by
leveraging over past and present advances on cubic spline interpolation,
allowing for local adaptation of the functions around their regions of use. The
resulting algorithm is relatively cheap to implement, and overfitting is
counterbalanced by the inclusion of a novel damping criterion, which penalizes
unwanted oscillations from a predefined shape. Experimental results validate
the proposal over two well-known benchmarks.Comment: Submitted to the 27th Italian Workshop on Neural Networks (WIRN 2017
Physical-Mechanical Modifications of Eggs for Food-Processing During Storage
Abstract Physical-mechanical properties of egg constituents and their modifications during storage and poststorage greatly influence the efficiency of food processing, such as the separation of white and yolk by mechanical shelling. Thick albumen height, Haugh unit, yolk index and vitelline membrane-yolk system strength of eggs from Hy-Line White and Lohmann Brown hens were analyzed during 7 mo of storage at 0°C performing 3 poststorage treatments: i) immediately after refrigeration, T1; ii) after a further 6 h at 18°C after refrigeration, T2; and iii) after a week at 18°C after refrigeration, T3. For all qualitative parameters considered, this last poststorage treatment appeared to be the factor that produced the highest decrements; with respect to the first poststorage treatment, a further week at 18°C after refrigeration can involve mean decreases of about 19, 14, 14, and 16% in thick albumen height, Haugh unit, yolk index, and vitelline membrane-yolk system strength (in terms of maximum force), respectively. During about 7 mo of storage at 0°C, the latter parameter decreases, on average, by 10%. Increasing the storage time, physical-mechanical behavior was sometimes divergent from the observed trends
A validated dynamical model of a kW-class Vanadium Redox Flow Battery
The development of redox flow batteries depends on the research on new materials as well as on the technological development, but also on appropriate models which allow to simulate their performance in operative conditions. Very few investigations are reported in the literature concerning the technology, modeling and simulation of large-scale Vanadium Redox Flow Battery systems, built around multi-cell stacks. This paper regards the modeling of an industrial-sized 9 kW test facility. In particular, a complete dynamic model is presented, that takes into account all thermal effects occurring inside the stack, resulting in a complex non-linear coupled formulation, that allows to simulate the battery operation in any realistic conditions. The model is able to simulate the thermal behavior both in standby, i.e. without power and reactant flow, as well as in load operation, i.e. in charge and discharge. The numerical implementation of the model is described in detail. The model validation is also described, consisting in comparing computed data with experimental measurements taken on the available test facility
A new dataset and empirical relationships between magnitude/intensity and epicentral distance for liquefaction in central-eastern Sicily
Strong earthquakes can trigger several phenomena inducing soil deformation, such as liquefaction, ground fracturing
and landslides, which can often cause more damage than the seismic shaking itself. A research performed
on numerous historical accounts reporting descriptions of seismogeological effects in central-eastern Sicily, allowed
the authors to update the previous liquefaction datasets. 75 liquefaction-induced phenomena observed in
26 sites, triggered by 14 earthquakes, have been used to define relationships between intensity/magnitude values
and epicentral distance from the liquefied sites. The proposed upper bound-curves, at regional scale for central-
eastern Sicily, are realized by using the updating liquefaction dataset and also the new CPTI04 Italian earthquake
parametric catalogue. These relationships can be useful in hazard assessment to evaluate the minimum energy
of an earthquake inducing liquefactions
The Thermodynamic Uncertainty Theorem
Thermodynamic uncertainty relations (TURs) express a fundamental tradeoff
between the precision (inverse scaled variance) of any thermodynamic current by
functionals of the average entropy production. Relying on purely variational
arguments, we significantly extend these inequalities by incorporating and
analyzing the impact of higher statistical cumulants of entropy production
within a general framework of time-symmetrically controlled computation. This
allows us to derive an exact expression for the current that achieves the
minimum scaled variance, for which the TUR bound tightens to an equality that
we name Thermodynamic Uncertainty Theorem (TUT). Importantly, both the minimum
scaled variance current and the TUT are functionals of the stochastic entropy
production, thus retaining the impact of its higher moments. In particular, our
results show that, beyond the average, the entropy production distribution's
higher moments have a significant effect on any current's precision. This is
made explicit via a thorough numerical analysis of swap and reset computations
that quantitatively compares the TUT against previous generalized TURs. Our
results demonstrate how to interpolate between previously-established bounds
and how to identify the most relevant TUR bounds in different nonequilibrium
regimes
Near-infrared Spectral Features in Single-aged Stellar Populations
Synthetic spectra for single-aged stellar populations of metallicities [M/H]
= -0.5, 0.0 and +0.5, ages = 3 to 17 Gyrs, and initial mass function exponents
x = 0.1 to 2.0 were built in the wavelength range 6000-10200 Angstrons. For
such we have employed the grid of synthetic spectra described in Schiavon &
Barbuy (1999), computed for the stellar parameters 2500 <= Teff <= 6000 K, -0.5
<= log g <= 5.0, [M/H] = -0.5, 0.0 and +0.5, and [alpha/Fe] = 0.0, together
with the isochrones by Bertelli et al. (1994) and Baraffe et al. (1998). The
behavior of the features NaI8190, CaII8662, TiO6600 and FeH9900 in the
integrated spectra of single stellar populations were studied in terms of
metallicity, initial mass function and age variations. The main conclusions are
that the NaI doublet is an IMF-sensitive feature, which is however sensitive
also to metallicity and age, whereas TiO, CaII and FeH are very sensitive to
metallicity and essentially insensitive to IMF and age.Comment: 13 pages + 7 figures, ApJ accepte
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