Gianni Jacucci

Modeling of particles impacting on a rigid substrate under plasma spraying conditions

Finite-element methods have been applied for the spreading process of a ceramic liquid droplet impacting on a flat cold surface under plasma spraying conditions. The goals of the present investigation are to predict the geometrical form of the splat as a function of process parameters, such as initial temperature and velocity, and to follow the thermal field developing in the droplet up to solidification. A nonlinear finite-element procedure has been extended to model the complex physical phenomena involved in the impact process. The dynamic motion of the viscous melt in the drops as constrained by elastic surface tensions and in interaction with the developing contact with the target has been coupled to transient thermal phenomena to account for the solidification of the material. A model is used to study the impact of spherical particles of liquid ceramic of given temperature and velocity on a flat, cool rigid surface. The deformation of the splat geometry as well as the evolution of the thermal field within the splat are followed up to the final state and require adaptive discretization techniques. The proposed model can be used to correlate flattening degrees with the initial process parameters.

Computer simulation of plasma-sprayed coatings. I, Coating deposition model

Abstract This paper develops a model for the deposition process of a thermal barrier plasma-sprayed coating. This takes experimental data for the plasma temperature and enthalpy content and the velocity, temperature and size distributions of the particles. The model uses a set of physically based rules to construct the coating. Simulations obtained using this model are compared with available experimental data. The results from the model are used in the next (companion) paper to calculate the effective elastic and thermal properties of the coating and hence to calculate the stresses within the coating for some simple configurations.

Modeling the deposition process of thermal barrier coatings

Thermal barrier coatings produced by plasma spraying have a characteristic microstructure of lamellae, pores, and cracks. The lamellae form when particles splash onto the substrate. As the coating grows, the lamellae pile on top of one another, producing an interlocking structure. In most cases the growth is rapid and chaotic, resulting in a microstructure characterized by pores and cracks. This paper presents an improved model for the deposition process of thermal barrier coatings. The task of modeling the coating growth is divided into two parts. First, a description of the particle on arrival at the film is given based on the available theoretical, numerical, and experimental findings. Second, a set of physically based rules for combining these events to obtain the film is defined and discussed. The splats run along the surface and are permitted to curl up (producing pores) or to interlock. The computer model uses a mesh to combine these processes and build the coating. The proposed model can be used to predict microstructures and hence to correlate the properties of these coatings with the parameters of the process used to make them.

Cooperative Knowledge Processing for Engineering Design

Cooperative working environments and their development are becoming increasingly important and ever more frequent in different industrial sectors and this book provides a scientific approach for managing Team Engineering. Meta-cognitive knowledge and networks are identified as the key resources enabling engineering teams to work effectively and to reduce engineering time and this book illustrates how computer support can aid cooperative work within the context of practical methodologies and examples. The fields covered in the book include: State-of-the-art research in cooperative learning tools; Practical examples and methodologies illustrating the implementation of cooperative networks; and An interdisciplinary approach to team engineering. This valuable new book is sponsored by the International Federation for Information Processing (IFIP) and will be essential reading for researchers, engineers, technical managers involved in the development of advanced applications for engineering and manufacturing, and software design and engineering.

Dispersion of surface phonons in a xenon monolayer physisorbed on the graphite basal plane

Abstract Molecular dynamics calculations have been used to study the effect of temperature on the dispersion of surface phonons in a registered xenon monolayer physisorbed on the graphite basal plane.

Linear and nonlinear response in computer simulation experiments

Computer simulation experiments on transport properties using perturbation of mechanical trajectories are critically discussed in the light of Van Kampens “case against linear response theory” and of the numerical experiments in the nonlinear region of Visscher, and more recently of Evans.

Mentoring Small Destinations into Destination Management towards Electronic Marketing

The paper reports on fieldwork concerning destination management: the build up of a virtual organisation for a tourist destination, the choice of a destination marketing strategy, the creation of a destination management system. The work belongs to the research domain on Information Systems, involving IT aspects as well as aspects of people development, organisation and management, and of marketing and business. The solid structure of an enterprise organisation is here replaced by the weak-link structure of a local community. The character of the present work is that of a case study, and the research methodology employed follows the guidelines of Action Research [1] [7]. In some respects, it is akin to Participatory Design in the field of software development. The present work builds up on earlier research work on destination management and destination management systems in the ICT community [3] [4] [11] [18] [20]. The point of view here focuses on tourist destinations (TDs), intended as homogeneous territorial domains, identifiable each with its own name, personality, and offer of a tourist product. We have helped a small TD to get started in adapting to the new situation and to induce change, and we trained ourselves on how to help to induce change successfully.

Engineering Plasma Spray Films By Knowledge Based Simulations

The FABERCOAT Decision Support System (DSS) is a design tool for the production of plasma-sprayed coatings developed in a CEC project among European universities, laboratories and manufacturing industries. The FABERCOAT system utilises a genetic algorithm to find a set of spray settings which can be used to achieve one particular set of desired final (and measurable) properties of the coating. At present, these desired outcomes are based on specific industrial requirements based on total porosity demands and most frequent porosity aspect ratio. The FABERCOAT system includes a model for the plasma spray manufacturing process developed and validated within the CEC project. The model has been used to “harvest” the information gained in the extensive production and characterisation programme of the CEC project and has provided an innovative way of feeding back this information to the end-users.

Genetic Algorithms (GAs) in the Role of Intelligent Regional Adaptation Agents for Agricultural Decision Support Systems

An AI adaptation methodology designed to assist in transporting agricultural models between regions is presented. A methodology to perform model adaptation (viz. localization) is frequently necessary when models are transported because models developed in one region often do not produce valid results when used in a different region. In this methodology, a GA plays the role of the adaptation agent. By linking a GA to an agricultural model, the model become more robust because it is able to adapt to the region in which the model is being used. This methodology has been implemented within a decision support system (DSS) developed within an EC project called SYBIL. The DSS helps farmers predict when diseases and funguses will attack their plants, so they can make intelligent decisions on preventing these attacks. Preliminary testing within this environment indicates this adaptation methodology has the ability to allow agricultural models developed in one area to be effectively utilized in other regions.

Designing the Accountability of Enterprise Architectures

Designing enterprise architectures for accountability is to reason about options. Instead of taking enterprise architectures as products, the paper seeks to comprehend how they are produced. Considering enterprise architecture as an entangled category of sociological, political and democratic challenges provide an opportunity to determine the political topos of enterprise architectures.