Floriana Esposito

Recent and ongoing remote observations indicate that sulfates are present in significant abundances at various locations on Mars. NASA's Mars Reconnaissance Orbiter Compact Reconnaissance Imaging Spectrometer for Mars (MRO-CRISM) will return hyperspectral data at high spatial resolution ( 20 m/pixel). Thus, the optical properties of sulfates, in general, are of interest to quantitative interpretation of existing and future remotely sensed data. Here we focus upon gypsum due to: 1) its applicability to Mars; 2) its availability in sample sizes suitable for study allowing various spectral measurements; 3) existence of several independent infrared optical constants applicable to evaluate our approach; and 4) a general lack of data regarding the optical constants for gypsum at wavelengths where observations are being obtained and planned (0.3-5 um). Diffuse reflectance spectra of multiple grain size fractions and two independent scattering calculation approaches were used to determine the imaginary index of refraction (k) from the measured reflectance of gypsum. The k's resulting from the two scattering calculations compare favorably, and in some regions are similar to k-values of gypsum reported in the literature. We find that in the regions of maximum k-values, the scattering theory results provide a poor determination compared to more traditional techniques. However, we find that the scattering results are more sensitive when determining k for weak spectral features that are absent when using more traditional techniques. In the 0.4-2.5 um region, we compare the results obtained from the diffuse reflectance to results obtained from direct transmission measurements of a gypsum crystal. We find a very good comparison to the k-values derived from transmission, except where gypsum becomes transparent. In the transparent region discrepancies may arise from: 1) difference in samples; 2) increased effective path length in the particulate samples; 3) light scattering during transmission measurement; and 4) some other experimental effects.

The problem of space debris in Earth orbit received a great interest since the last few years. The recent impulse on the activities in space has produced a considerable increase of knowledge on the debris population in the circum-terrestrial environment and a new one is expected in the next years. Hypervelocity impacts of artificial objects, sub-micron to centimeter sized, with a spacecraft constitute a potential risk to on-orbit hardware. In order to assess the risks of collision between orbital debris and spacecrafts, it is necessary to well characterise the debris population in the Earth orbit environment. In situ monitoring and modelling are complementary actions to be performed in order to reach this aim. A number of well defined spatial technologies have been proposed to be dedicated to the characterisation of dynamical, chemical and physical properties of orbital debris, mainly in the following directions: - impact detection and momentum measurement of slow and fast particles by means of piezoelectric sensors; - optical detection of micron sized particles at low speed, by means of light scattered from a laser curtain; - elemental analysis of fast particles based on ToF spectrometry on plasma produced after particle impact on a target; - transit and trajectory detection by means of charge induced on metallic grids; An important contribute comes also by the non destructive collection in aerogel of orbital debris and the characterisation of captured particles properties by means of laboratory analyses once the samples have been returned to Earth. In the present work we will report the activities performed in our laboratory concerning the development of techniques for in situ monitoring and for collection by aerogel of debris and meteoroids.

... Kok, The Netherlands Stefan Kramer, Germany Laks Lakshmanan, Canada Nada Lavrac, Slovenia Donato Malerba, Italy Giuseppe Manco, Italy ... Yannis Tzitzikas Jaideep S. Vaidya Pascal Vaillant Alexandros Valarakos Anneleen Van Assche Antonio Varlaro Guillaume Vauvert ...

A spectroradiometer has been developed for the characterisation of the atmospheric emission in the 100-1100 cm-1 spectral range with a resolution of 0.5 cm-1 and a signal-to-noise ratio of 100. This instrument has been studied in the framework of the REFIR (Radiation Explorer in the Far InfraRed) space project, which addresses the need for new data in a range not yet covered by any current or planned space mission for improving our knowledge of the distribution of the atmospheric components that modulate the Earh's emission, such as mid and upper tropospheric water vapour and clouds. The spectroradiometer is a based on a Fourier transform polarising interferometer with a new optical scheme that makes use of four polarising beam splitters and room-temperature pyroelectric detectors. It provides all the desired features including broad spectral coverage, two separated input ports and two output ports, optical compensation for tilt errors in the moving mirror unit, measurement of the overall input signal (both planes of polarization) on the same detector. This optical configuration maximizes the reliability of the spectrometer in particular for long lifetime space operations or for field campaigns and optimizes its performances with room temperature operations. The spectroradiometer is a compact instrument designed both for laboratory applications and for field campaings. In particular it has been designed for operations in high-altitude ground-based campaigns and on a stratospheric balloon platform. This work describes the design and fabrication of this instrument, the results of the spectroscopic characterisation performed in laboratory conditions and under vacuum, and possibly the first tests on atmospheric measurements scheduled for the beginning of 2004 in the South of Italy.

Dust is supposed to be present in several orbits around Mars. The sources of these hypothetical dust belts are expected to be the two Martian satellites Phobos and Deimos, due to their continuous hypervelocity bombardment by interplanetary micro-meteoroids. Due to the low escape speeds from the surfaces of the two tiny moons and high ejecta yields, it is expected that a great amount of dust is ejected in areocentric orbit, forming tenuous tori around the orbits of the moons. Time of permanence of dust in the tori depends on grains mass and shape. Different models have been proposed in order to describe the process of generation and stabilization of dust in the tori but several uncertainties do exist about numerical density and size distribution of dust grains. In situ measurements are thus needed, in order to shed light on the extraction, escape and trap processes of particles in the tori. The instrument DIAMOND (Direct In-situ Analyser and Monitor of Orbiting Natural Dust) has been designed for the detection and characterization of dust in the hypothetical tori of Mars. It has been accepted by the Russian space agency as part of the payload of the Russian Phobos-Soil mission to be launched in 2011. The project is now under evaluation by ASI.

... Napoli) Luisa SANSEVERINO (Centre Ricerche FIAT) M. Teresa PAZIENZA (Univ. ... Machine Learning A Monte Carlo Approach to Hard Relational Learning Problems 1 A. Serra, A. Giordano, Boosting as a Monte Carlo Algorithm 11 R. Esposito, L. Saitta Stepwise Induction of ...

Horn clause Logic is a powerful representation language exploited in Logic Programming as a computer programming framework and in Inductive Logic Programming as a formalism for expressing examples and learned theories in domains where relations among objects must be expressed to fully capture the relevant information. While the predicates that make up the description language are defined by the knowledge engineer and handled only syntactically by the interpreters, they sometimes express information that can be properly exploited only with reference to a taxonomic background knowledge in order to capture unexpressed and underlying relationships among the concepts described. This is typical when the representation predicates are not purposely engineered but rather derive from the particular words found in a text.

ABSTRACT The implementation of effective Semantic Web Services (SWS) platforms allowing the composition and, in general, the orchestration of services presents several problems. Some of them are intrinsic within the formalisms adopted to describe SWS, especially when trying to combine the dynamic aspect of SWS effects and the static nature of their ontological representation in Description Logic (DL). This paper proposes a mapping of OWL-S with a DL action formalism in order to evaluate executability and projection by means of the notion of Contexts.

12 Machine learning for information extraction from topographic maps Donato Malerba, Floriana Esposito, Antonietta Lanza and Francesco A. List 1 Introduction Geographical Information Systems (GIS) are computer systems for collecting, managing and analysing geographically ...

... The research group of Anroutsopoulos continues to manipulate this parameter. They compare it to a baseline value, the weighted error rate when no spam filter is present. This means thatno spam emails are recognized. The baseline weighted error rate is calculated as follows: ...

The impact sensor of the GIADA instrument, which is in the scientific payload of ESA Rosetta mission, is aimed at measuring dust grains momentum in comet 46/PWirta- nen, it is made up of an aluminum plate bounded along the edges, with five piezoelec- tric sensors, which are sensitive to flexural waves. Waves are produced on the plate as consequence of grains impacts on the surface. The finite elements analysis (FEA) enables to characterize the dynamical and static response of mechanical systems and to perform their modal analysis. In this study, the FEA code has been used to ana- lyze the sensor behavior and response by changing boundary conditions and the stress frequency composition. The plate sensitivity is analyzed and it is compared with the results obtained during GIADA Impact Sensor calibration.

ABSTRACT To provide wide-area network services, resources from different infrastructure providers are needed. Leveraging the consensus-based resource allocation literature, we propose a general distributed auction mechanism for the (NP-hard) slice embedding problem. Under reasonable assumptions on the bidding scheme, the proposed mechanism is proven to converge, and it is shown that the solutions guarantee a worst-case efficiency of (1 - 1/ε) relative to the optimal solution. Using extensive simulations, we confirm superior convergence properties and resource utilization when compared with existing distributed slice embedding solutions, and we show how by appropriate policy design, our mechanism can be instantiated to accommodate the embedding goals of different service and infrastructure providers, resulting in an attractive and flexible resource allocation solution for network virtualization.

We compare gypsum optical constants (n and k), derived via two radiative transfer models (rtms), to independent and previously reported values. The rtms provide estimates of n and k in regions of weak absorptions, where previous models are insensitive.

This study evaluated the influence of acute and chronic hypoxia (up to 40 days at 5,050 m) on the muscle strength, fast-to-slow fiber motor unit (MU) ratio, and MU activation strategy. These factors were studied by measuring the maximal voluntary contraction (MVC) of the elbow flexors and analyzing surface electromyogram (EMG) and soundmyogram (SMG) of the isometrically contracting biceps brachii. From the time and frequency domain analysis of EMG and SMG, the root mean square and mean frequency of the spectra were calculated. SMG and EMG were recorded during 4-s exercises in the 20-100% MVC range before departure; after 2, 15, and 40 days at high altitude; and after the return to sea level. MVC or root mean square and mean frequency at all levels of effort were not significantly different among all experimental conditions. In the present study where optimal living conditions (i.e., food, physical activity, and environmental temperature) were ensured, acute and chronic hypoxia (at least up to 40 days) did not affect the maximal force output or fast-to-slow fiber MU ratio and MU activation pattern during isometric exercise.