A virtual environment for decision support in ship damage control.

Safety is one of the main concerns in maritime activity. Although the safety of a ship may be determined by many uncontrollable factors (such as weather or human error), efficient and continuous monitoring of shipboard systems and the current safety status is crucial to avoid or at least minimize the effects. Most modern ships have a Damage Control Center onboard where the crew monitors ship systems and structures and coordinates emergency teams. The Damage Control Center has information about the compartments, tanks and ducts arrangements, stability diagrams, evacuation plans, and so on. The paper describes that the virtual ship is a virtual environment that supports emergency planning decisions in a ship's Damage Control Center. The model considers what could occur when fluids disseminate through a ship's compartments, such as flooding, fire, or contamination.     

Evolution of neural networks for classification and regression

Although Artificial Neural Networks (ANNs) are importantdata mining techniques, the search for the optimal ANN is a challenging task: the ANN should learn the input–output mapping without overfitting the data and training algorithms may get trapped in local minima. The use of Evolutionary Computation (EC) is a promising alternative for ANN optimization. This work presents two hybrid EC/ANN algorithms: the first evolves neural topologies while the latter performs simultaneous optimization of architectures and weights. Sixteen real-world tasks were used to test these strategies. Competitive results were achieved when compared with a heuristic model selection and other Data Mining algorithms.     

Contracting agents: legal personality and representation

The combined use of computers and telecommunications and the latest evolution in the field of Artificial Intelligence brought along new ways of contracting and of expressing will and declarations. The question is, how far we can go in considering computer intelligence and autonomy, how can we legally deal with a new form of electronic behaviour capable of autonomous action? In the field of contracting, through Intelligent Electronic Agents, there is an imperious need of analysing the question of expression of consent, and two main possibilities have been proposed: considering electronic devices as mere machines or tools, or considering electronic devices as legal persons. Another possibility that has been frequently mentioned consists in the application of the rules of agency to electronic transactions. Meanwhile, the question remains: would it possible, under a Civil Law framework, to apply the notions of “legal personhood” and “representation” to electronic agents? It is obvious that existing legal norms are not fit for such an endeavouring challenge. Yet, the virtual world exists and it requires a new but realistic legal approach on software agents, in order to enhance the use of electronic commerce in a global world.     

DW-RBAC: A formal security model of delegation and revocation in workflow systems

One reason workflow systems have been criticized as being inflexible is that they lack support for delegation. This paper shows how delegation can be introduced in a workflow system by extending the role-based access control (RBAC) model. The current RBAC model is a security mechanism to implement access control in organizations by allowing users to be assigned to roles and privileges to be associated with the roles. Thus, users can perform tasks based on the privileges possessed by their own role or roles they inherit by virtue of their organizational position. However, there is no easy way to handle delegations within this model. This paper tries to treat the issues surrounding delegation in workflow systems in a comprehensive way. We show how delegations can be incorporated into the RBAC model in a simple and straightforward manner. The new extended model is called RBAC with delegation in a workflow context (DW-RBAC). It allows for delegations to be specified from a user to another user, and later revoked when the delegation is no longer required. The implications of such specifications and their subsequent revocations are examined. Several formal definitions for assertion, acceptance, execution and revocation are provided, and proofs are given for the important properties of our delegation framework.     

Nonhydrolytic sol-gel synthesis and characterization of YAG

Yttrium–aluminum oxides are interesting compounds, which are widely used as hosts for lasers and phosphors due to their stable physical and chemical properties. The manufacture of YAG has been investigated thoroughly. YAG powders are traditionally synthesized through the reaction of aluminum and yttrium powders at high temperatures. The work reported here involved an investigation into the preparation of YAG by a nonhydrolytic sol-gel route and the influence of heating time at low temperatures to obtain YAG from inorganic precursors (yttrium and aluminum chloride). AlCl₃, YCl₃ and ethanol were reflux reacted under an argon atmosphere. Europium III chloride was added as a structural probe. The powder was treated at 800 °C for 1, 2, 4, 8 and 16 h. The YAG structure was analyzed by X-ray diffraction (XRD), nuclear magnetic resonance (NMR), thermal analysis (TA) and photoluminescence (PL). The XRD revealed only peaks corresponding to the YAG phase. PL data showed that the YAG phase was formed in 2 min with samples pretreated at 50 °C. For the samples pretreated at 800 °C, the YAG phase appeared in 30 s. The excitation spectra presented a maximum of 394 nm corresponding to the ⁵L₆ level, while the emission spectra of Eu III ions showed characteristic transition bands arising from the ⁵D₀ → ⁷F _J (J = 1, 2, 3, 4) manifolds at maximum excitation. The magnetic dipole ⁵D₀ → ⁷F₁ transition exhibited greater intensity than the electric dipole ⁵D₀ → ⁷F₂ transition. This methodology proved efficient for obtaining YAG phase.     

Piezoelectric properties of Bi4Ti3O12 thin films annealed in different atmospheres

Bismuth titanate (Bi₄Ti₃O₁₂—BIT) films were evaluated for use as lead-free piezoelectric thin-films in micro-electromechanical systems. The films were grown by the polymeric precursor method on Pt/Ti/SiO₂/Si (1 0 0) (Pt) bottom electrodes at 700 °C for 2 h in static air and oxygen atmospheres. The domain structure was investigated by piezoresponse force microscopy (PFM). Annealing in static air leads to better ferroelectric properties, higher remanent polarization, lower drive voltages and higher piezoelectric coefficient. On the other hand, oxygen atmosphere favors the imprint phenomenon and reduces the piezoelectric coefficient dramatically. Impedance data, represented by means of Nyquist diagrams, show a dramatic increase in the resistivity for the films annealed in static air atmopshere.     

Enhancement of critical current density of YBa2Cu3O7 − δ thin films by self-assembly of Y2O3 nanoparticulates

YBa₂Cu₃O_7 − δ (YBCO) thin films, possessing high critical current density (J_c), have been synthesized by embedding a homogeneous array of Y₂O₃ non-superconducting nanoclusters/nanoparticles using a pulsed laser deposition technique. The size, interparticle spacing, and density of Y₂O₃ nanoparticles in YBCO thin films were tailored by varying the number of laser pulses in order to determine the optimum size for effective immobilization of vortices. Scanning transmission electron microscopy with atomic number contrast and X-ray diffraction techniques were used to determine the size and structure of the nanoparticles. Both techniques indicate that the Y₂O₃ particles are epitaxial with respect to the surrounding YBCO matrix. The information about pinning of vortices by the nanoparticles was obtained by investigating the behavior of critical current density as a function of temperature and applied field, which in turn determines the vortex density in the sample. The superconducting transition temperature (T_c) of YBCO films with the inclusion of nanoparticles was observed to remain almost the same or decrease marginally (1-2 K) with respect to T_c of pure YBCO films deposited under identical conditions. However, J_cs of YBCO films embedded with self-assembled nanoparticles were found to be significantly higher than that of pure YBCO films. The J_c enhancement was up to five times in high magnetic field, which is a key requirement for practical application of high-T_c materials.     

Solvent‐Mediated Plasmon Tuning in a Gold‐Nanoparticle–Poly(Ionic Liquid) Composite

The design, synthesis, and characterization of a hierarchically ordered composite whose structure and optical properties can be reversibly switched by adjustment of solvent conditions are described. Solvent‐induced swelling and de‐swelling is shown to provide control over the internal packing arrangement and hence, optical properties of in situ synthesized metal nanoparticles. Specifically, a gold‐nanoparticle‐containing ionic‐liquid‐derived polymer is synthesized in a single step by UV irradiation of a metal‐ion‐precursor‐doped, self‐assembled ionic liquid gel, 1‐decyl‐3‐vinylimidazolium chloride. Small‐angle X‐ray scattering (SAXS) studies indicate that in the de‐swollen state, the freestanding polymer adopts a perforated lamellar structure. Optical spectroscopy of the dried composite reveals plasmon resonances positioned in the near‐IR. Strong particle–particle interactions arise from matrix‐promoted formation of aggregated 1D clusters or chains of gold nanoparticles. Upon swelling in alcohol, the composite undergoes a structural conversion to a disordered structure, which is accompanied by a color change from purple to pale pink and a shift in the surface plasmon resonance to 527 nm, consistent with isolated, non‐interacting particles. These results demonstrate the far‐field tuning of the plasmonic spectrum of gold nanoparticles by solvent‐mediated changes in its encapsulating matrix, offering a straightforward, low‐cost strategy for the fabrication of nanophotonic materials.     

Lessons learned from the testing of RC frames with masonry infills and proposals for new solutions / Untersuchungen an mit Mauerwerk ausgefachten Stahlbetonrahmen und neue Lösungsvorschläge

Past experience has shown that inadequate design of unreinforced masonry walls (URM) or inadequate selection of materials can lead to significant economic losses and fatalities in the case of a strong earthquake. In this context, this paper presents the experimental research that has been carried out with the aim of gaining a better insight into the traditional masonry infill walls commonly built in Portugal. The experimental research includes: (1) shaking table tests on reduced‐scale reinforced concrete (RC) buildings with masonry infills with distinct typologies, from traditional solutions to those with enhanced properties and solutions to improve the seismic behaviour; (2) in‐plane static cyclic tests on a representative one‐storey, one‐bay RC frame with masonry infills with distinct typologies but similar to the ones tested in the RC building models. It was concluded that the typology of masonry walls influences the global behaviour of RC buildings, particularly when there is no connection between masonry infill and RC frame. An appropriate design is necessary to prevent an unforeseen failure mechanism due to shear stresses in the RC columns induced by the infill. The in‐plane cyclic tests showed that render plays a central role in the lateral strength and stiffness. Additionally, it was observed that bed joint reinforcement and reinforced render are important measures for controlling damage but do not significantly influence the in‐plane lateral strength and stiffness.