QoS Guarantees in Heterogeneous Systems Consisting of IP Core Networks with Satellite Access

This paper aims at investigating the issue of differentiated QoS provision to services over a heterogeneous terrestrial-satellite infrastructure. In particular, the implementation of a dynamic mapping of the main service classes offered by IP IntServ and DiffServ models over satellite bearer services is investigated.Objective of the research is to enable mobile subscribers to access broadband services offered within a fixed IP core network, through satellite links. This has to be performed while still guaranteeing the same Quality of Service (QoS) offered by the IP IntServ and DiffServ models over the terrestrial segment. In such an environment, the considered traffics derive from multimedia applications and are characterised by real-time and non-real-time constraints as well as variable (VBR) and constant (CBR) bit-rate profiles.     

Fault-Tolerant Support for Reliable Multicast in Mobile Wireless Systems: Design and Evaluation

In this paper we present a protocol for reliable multicast within a group of mobile hosts that communicate with a wired infrastructure by means of wireless technology. The protocol assumes that the wireless coverage may be incomplete and message losses could occur even within cells, due to physical obstructions or to the high error rate of the wireless technology, for example. A novel feature of our proposal is that it tolerates failures in the wired infrastructure, i.e., crashes of stationary hosts and partitions of wired links. In particular, upon such failures mobile hosts simply observe that the covered area has shrunk. The covered area will enlarge back to its original extension when the failure recovers. We evaluate our protocol by means of an extensive simulation analysis. The main findings of our analysis are: the protocol exhibits very good scalability properties; the performance degradation induced by fault-tolerance is moderate.     

Differences in X-ray absorption due to cadmium treatment in Saponaria officinalis leaves

A method for detecting cadmium uptake in leaves of Saponaria officinalis doped with a solution of cadmium acetate is described. The technique based on the exposure of dried leaves to X-rays of a wavelength close to that of the metal K-edge could be useful for phytoremediation studies as it could reveal the bioaccumulation in plants due to the treatment either in vivo or in vitro with heavy metals. X-ray microradiography measurements are in agreement with those from peroxidase enzyme assay utilized to follow the oxidative damage induced by heavy metals. At present, as we will see in this report, microradiography has still poorer sensitivity in comparison with enzyme assay, but it has the advantage of being faster, not destructive, and usable even at very high doping levels, where the enzyme assay technique results are fully saturated. Further analysis of the optical density values could lead to a quantitative measurement of the heavy metal in the sample. Thus, the technology developed in this article could be useful for tracing the intake in phytoremediation studies.     

Ellipsoidal bounds for uncertain linear equations and dynamical systems

In this paper, we discuss semidefinite relaxation techniques for computing minimal size ellipsoids that bound the solution set of a system of uncertain linear equations. The proposed technique is based on the combination of a quadratic embedding of the uncertainty, and the -procedure. This formulation leads to convex optimization problems that can be essentially solved in O(n³)—n being the size of unknown vector—by means of suitable interior point barrier methods, as well as to closed form results in some particular cases. We further show that the uncertain linear equations paradigm can be directly applied to various state-bounding problems for dynamical systems subject to set-valued noise and model uncertainty.     

Moulds isolated from Istrian dried ham at the pre-ripening and ripening level

The aim of this study is to define the mould strains growing on the surface during the pre-ripening and the ripening phases of Istrian ham, and their toxic potential. The mould microflora was predominantly represented by five genera, which were isolated on the ham surfaces of three different producers investigated. The identified species were similar in the both tested periods, demonstrating that the contamination came mainly from the air and the ripening chambers (seasoning rooms), rather than the raw meat. Eurotium spp., Aspergillus spp. and Penicillium spp. were the main strains isolated. The presence and growth of the different strains depended on the temperature of ripening and the relative humidity in the ripening chambers, since the hams were home made products and not matured in controlled conditions. The toxic potential of isolated strains was also investigated. None of the tested moulds can produce mycotoxins and for this reason the Istrian hams do not represent a health hazard.     

MASHA: A multi-agent system handling user and device adaptivity of Web sites

A user that navigates on the Web using different devices should be characterized by a global profile, which represents his behaviour when using all these devices. Then, the user’s profile could be usefully exploited when interacting with a site agent that is able to provide useful recommendations on the basis of the user’s interests, on one hand, and to adapt the site presentation to the device currently exploited by the user, on the other hand. However, it is not suitable to construct such a global profile by a software running on the exploited device since this device (e.g., a mobile phone or a palmtop) may have limited resources. Therefore, in this paper, we propose a multi-agent architecture, called MASHA, handling user and device adaptivity of Web sites, in which each device is provided with a client agent that autonomously collects information about the user’s behaviour associated to just that device. However, the user profile contained in this client is continuously updated with information coming from a unique server agent, associated with the user. Such information is collected by the server agent from the different devices exploited by the user, and represents a global user profile. The third component of this architecture, called adapter agent, is capable to generate a personalized representation of the Web site, containing some useful recommendations derived by both an analysis of the user profile and the suggestions coming from other users exploiting the same device.     

Decoherence in Holonomic Quantum Computation

Geometric phases are an interesting field of research in quantum mechanics. Recently both abelian and nonabelian geometric phases have been proposed as a useful resource for the experimental implementation of quantum computation. In this paper we focus on a particular physical model and study the effect of a bosonic bath on a class of holonomic transformations. We write a general master equation for time-dependent Hamiltonians and derive analytical and numerical solutions for the system considered. The fidelity is analyzed in the adiabatic and nonadiabatic regime. We also determine an optimal finite operation time for this class of gates.     

Development and application of triglyceride-based polymers and composites

Triglyceride oils derived from plants have been used to synthesize several different monomers for use in structural applications. These monomers have been found to form polymers with a wide range of physical properties. They exhibit tensile moduli in the 1–2 GPa range and glass transition temperatures in the range 70–120 °C, depending on the particular monomer and the resin composition. Composite materials were manufactured utilizing these resins and produced a variety of durable and strong materials. At low glass fiber content (35 wt %), composites produced from acrylated epoxidized soybean oil by resin transfer molding displayed a tensile modulus of 5.2 GPa, a flexural modulus of 9 GPa, a tensile strength of 129 MPa, and flexural strength of 206 MPa. At higher fiber contents (50 wt %) composites produced from acrylated epoxidized soybean oil displayed tensile and compression moduli of 24.8 GPa each, and tensile and compressive strengths of 463.2 and 302.6 MPa, respectively. In addition to glass fibers, natural fibers such as flax and hemp were used. Hemp composites of 20% fiber content displayed a tensile strength of 35 MPa and a tensile modulus of 4.4 GPa. The flexural modulus was ∼2.6 GPa and the flexural strength was in the range 35.7–51.3 MPa, depending on the test conditions. The flax composite materials had tensile and flexural strengths in the ranges 20–30 and 45–65 MPa, respectively. The properties exhibited by both the natural- and synthetic fiber-reinforced composites can be combined through the production of “hybrid” composites. These materials combine the low cost of natural fibers with the high performance of synthetic fibers. Their properties lie between those displayed by the all-glass and all-natural composites. Characterization of the polymer properties also presents opportunities for improvement through genetic engineering technology. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 703–723, 2001     

Local Viscosity of Si-O-C-N Nanoscale Amorphous Phases at Ceramic Grain Boundaries

Internal friction characterization has been used to quantitatively assess the viscosity characteristics of Si-O-C-N glasses segregated to nanometer-sized grain boundaries of polycrystalline Si₃N₄ and SiC ceramics. A relaxation peak of internal friction, which arises with rising temperature from the viscous sliding of glassy grain boundaries, was systematically collected and analyzed with respect to its shift upon changing the oscillation frequency. As a result of such an analysis, both activation energy for viscous grain-boundary flow and inherent viscosity of the intergranular glass film could be quantitatively evaluated. Two main features are shown: (i) the presence of N and/or C greatly affects the viscosity characteristics of SiO₂ phases at Si₃N₄ and SiC grain boundaries; and (ii) the internal friction method has potential as a unique experimental tool for understanding the local properties of nanoscale amorphous phases in new ceramic materials.