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The hybrid-{T}refftz displacement element is applied to the elastodynamic analysis of bounded and unbounded media in the frequency domain. The displacements are approximated in the domain of the element using local solutions of the wave equation, the Neumann conditions are enforced directly and the surface forces are approximated on the Dirichlet and inter-element boundaries of the finite element mesh. Two alternative elements are developed to model unbounded media, namely a finite element with absorbing boundaries and an unbounded element that satisfies explicitly the Sommerfeld condition. The finite element equations are derived from the fundamental relations of elastodynamics written in the frequency domain. The numerical implementation of these equations is discussed and numerical tests are presented to assess the performance of the formulation.

The design and development of a transparent, easy to use and affordable ICT infrastructure is a key pre-requisite for the effective large-scale implementation of the collaborative network organizations such as virtual organizations, professional virtual communities, e-science communities, etc. This chapter introduces an overview of the main classes of infrastructures required by different types of virtual organizations and summarizes the main approaches followed by a number of research projects in the area.

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{A stochastic variational principle for the classical Burgers equation is established. A solution of this equation can be considered as the velocity field of a stochastic process which is a minimum of an energy functional. A family of stochastic constants of the motion, determined in terms of the probability distribution of that process, yields the complete list of symmetries of the Burgers equation.}

Monitoring systems have traditionally been developed with rigid objectives and functionalities, and tied to specific languages, libraries and run-time environments. There is a need for more flexible monitoring systems which can be easily adapted to distinct requirements. On-line monitoring has been considered as increasingly important for observation and control of a distributed application. In this paper we discuss monitoring interfaces and architectures which support more extensible monitoring and control services. We describe our work on the development of a distributed monitoring infrastructure, and illustrate how it eases the implementation of a complex distributed debugging architecture. We also discuss several issues concerning support for tool interoperability and illustrate how the cooperation among multiple concurrent tools can ease the task of distributed debugging.

The introduction of new courses on virtual organizations at the engineering education level is an important element for the broad acceptance of this new paradigm. This article summarizes the experience with an initiative of teaching Virtual Enterprises / Virtual Organizations subjects to Electrical and Computer Engineering students. The course structure, both in its lecture and lab work components, is described. Finally, some lessons learned with two editions of this course are presented.