Dynamic binding in mobile applications

By separating binding concerns from application logic, the Colomba approach exploits metadata to let mobile applications adapt to dynamic environments. Colomba separates service logic from binding management. This permits developers to code, change, and reuse service components and binding strategies independently of each other. Administrators can express binding strategies at a high level of abstraction in terms of declarative policies. In particular, Colomba supports a dynamic binding management that requires: Context awareness is the knowledge of application-specific attributes, such as user preferences, level of trust, subscribed services, and access device characteristics. Users can refer to a set of resources determined by context information. Location awareness is the knowledge of the physical position of the user or device connection to the network infrastructure. Available resources depend on location information.     

Microstructural Effects in Face-Centered-Cubic Alloys after Small Charge Explosions

Effects on metal targets after an explosion include the following: fracture, plastic deformation, surface modifications, and microstructural crystallographic alterations with ensuing mechanical properties changes. In the case of small charge explosions, macroscopic effects are restricted to small charge-to-target distances, whereas crystal alterations can still be observed at moderate distances. Microstructural variations, induced on gold-alloy disk samples, as compared to previous results on AISI 304Cu steel samples, are illustrated. The samples were subjected to blast-wave overpressures in the range of 0.5 to 195 MPa. Minimum distances and peak pressures, which could still yield observable alterations, were especially investigated. Blast-related microstructural features were observed on the explosion-exposed surface and on perpendicular cross sections. Analyses using X-ray diffraction (XRD) were performed to identify modifications of phase, texture, dislocation density, and frequency of mechanical twins, before and after the explosions. Optical metallography (OM) and scanning electron microscopy (SEM) observations evidenced partial surface melting, zones with recrystallization phenomena, and crystal plastic deformation marks. The latter marks are attributed to mechanical twinning in the stainless steel and to cross-slip (prevalent) and mechanical twinning (possibly) in the gold alloy. This article is based on a presentation given in the symposium “Dynamic Behavior of Materials,” which occurred February 26–March 1, 2007, during the TMS Annual Meeting in Orlando, FL, under the auspices of the TMS Structural Materials Division and the TMS/ASM Mechanical Behavior of Materials Committee.

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Prototype Platforms for Distributed Agreements

We present a prototype application for coordinating distributed agreements in multi-parties negotiations, where participants can dynamically join ongoing negotiations and where participants know only those parties they have interacted with. Our prototype is tailored to Ad-Hoc network scenarios involving the assignment of tasks for a rescue team operating over disaster areas. Our application is based on asynchronous communication and it exploits the d2pc protocol for committing or aborting a negotiation. Parties have been developed both in Jocaml+Perl and Polyphonic C. The implementation of the commit protocol allows components of both types to participate within the same negotiation.     

First electron availability and partial discharge generation in insulation cavities: effect of light irradiation

An experimental investigation of the behavior of partial discharges occurring in insulation cavities as a function of light irradiation conditions is presented in this paper. Partial discharge inception voltage (PDIV) measurements were performed for different irradiation conditions of the test objects (visible light, of variable intensity, ultra violet (UV) light or absence of irradiation), defect geometry and conductivity of insulating material. It is shown that changes of such factors involve considerable alteration of partial discharge inception features, in terms of both inception voltage and delay time. Depending on applied field, defect geometry, insulating material characteristics and irradiation condition, in fact, partial discharge inception voltage may be influenced prevailingly by background radiation, as generally stated in literature, or by field-assisted electron detrapping from material-cavity interface.     

High temperature metal hydrides for energy systems Part A: Numerical model validation and calibration

Metal hydrides have become more and more significant both as hydrogen storage devices and as basic elements in energy conversion systems. Magnesium hydride (MgH₂) shows very interesting characteristics – i.e. high enthalpy of reaction and hydrogen gravimetric density – making it capable of being employed in the field of energy production. So there is interest in investigating the behaviour of this kind of hydride, placed in an energy system. In order to examine MgH₂ in depth, its main kinetic parameters must be found and this can be accomplished by means of the calibration of a model previously realised by author Marco Gambini in his 1989–1994 works.In the light of this, an assessment of the activation energies (E_a = 72,200 kJ/kmol, E_d = 89,000 kJ/kmol) and kinetic constants (k_0a = 15,000 s^?1, k_0d = 198,500 s^?1) in both absorption and desorption phase of magnesium hydride has been provided. Thanks to these values, the behaviour of MgH₂ can be modelled, making the performance of a magnesium hydride-based energy system estimable.     

Evaluation of compatibility of methacrylic copolymers by capillary viscometry

The estimation of the compatibility of different pairs of polymers can be based on capillary viscometry data for ternary polymer‐polymer‐solvent systems using mathematical models based on the slope of the Huggins equation (Δb) and Huggins constant (Δk′). In this study, the compatibility of binary mixtures of six types of methacrylic copolymers with similar molecular weights but different functional groups [one characterized by amine groups (EuE), two by ammonium groups (EuRL EuRS), two by carboxylic groups (EuL EuS), and one without charge (EuNE)] was evaluated using these methods. On the basis of Huggins and Kraemer constants, acetone and tetrahydrofurane were selected as good solvents for the programmed blends. Cationic copolymers mixed with anionic copolymers showed the formation of visible aggregates. The study performed on the other blends showed that EuRL and EuRS could be considered compatible with EuE; EuNE was incompatible with both EuL and EuE, EuL and EuS were incompatible between them. EuRL and EuRS could be considered compatible even if the weight ratio seems to influence the behavior of the two copolymers. The Δk′ approach seems to be more robust than the Δb model. The compatibility of different pairs of methacrylic copolymers with similar molecular weights could be evaluated using capillary viscometry. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1662–1668, 2000     

Effect of nitrate fertilization and saline stress on the contents of active constituents of Echinacea angustifolia DC

In this study, the effect of nitrogen form (nitrate and ammonium in the molar ratio of 1:1 or 1:0), supplied to the plant or NaCl salinity (up to a concentration of 50 mol m⁻³) of the feeding solution, on the content of selected caffeic acid derivatives and the activities of phenylalanine ammonia lyase (PAL; EC. 4.3.1.5) and shikimate dehydrogenase (SKDH; EC 1.1.1.25) were investigated in the leaves and the roots of Echinacea angustifolia DC, grown hydroponically. Two experiments were conducted under glasshouse conditions with seedlings transplanted in aerated stagnant nutrient solution (floating raft system) four weeks after emergence. The nitrate/ammonium ratio in the nutrient solution did not affect plant growth or dry matter partitioning, but it influenced the concentration of determined metabolites; in particular, the root concentrations of chlorogenic acid, echinacoside and caffeic acid were significantly higher in the plants grown with nitrate as sole source of nitrogen. NaCl salinity reduced plant growth, by reducing the biomass allocated to the inflorescences, and enhanced the accumulation of chlorogenic acid and cichoric acids, at least in the roots.     

Temporal representation and reasoning in artificial intelligence: Issues and approaches

Time is one of the most relevant topics in AI. It plays a major role in several areas, ranging from logical foundations to applications of knowledge‐based systems. In this paper, we survey a wide range of research in temporal representation and reasoning, without committing ourselves to the point of view of any specific application. The organization of the paper follows the commonly recognized division of the field in two main subfields: reasoning about actions and change, and reasoning about temporal constraints. We give an overview of the basic issues, approaches, and results in these two areas, and outline relevant recent developments. Furthermore, we briefly analyze the major emerging trends in temporal representation and reasoning as well as the relationships with other well‐established areas, such as temporal databases and logic programming. This revised version was published online in June 2006 with corrections to the Cover Date.     

Refractive index tailoring in congruent Lithium Niobate by ion implantation

Refractive index profiles of ion-implanted Lithium Niobate waveguides are investigated. Z⁺ and z⁻ congruent Lithium Niobate samples have been implanted with C³⁺ ions at a fluence of 4 × 10¹⁴ ions/cm². Dark m-lines measurements have been performed on ordinary (n_o) and extraordinary (n_e) indexes for three different wavelengths (532 nm, 632.8 nm, 818 nm) before and after the annealing process. A reconstruction of refractive index profiles by Reflectivity Calculation Method (RCM) is presented and commented. The literature data for nuclear damage regime have been collected and critically examined. n_o and n_e curves as function of the density of energy released in nuclear collisions, E_d, describing the effects of ion implantation on LN refractive indexes has been obtained on the basis of literature data. n_o depth profile, predicted according to n_o(E_d) curve, is in good agreement with the RCM reconstructed one. In the case of n_e, a satisfactory agreement has been reached only slightly modifying the n_e(E_d) curve and considering an alternative RCM profile structure.