Assessing the scalability of multiphysics tools for modeling solidification and melting processes on parallel clusters

A comprehensive solution of solidification/melting processes requires the simultaneous representation of free surface fluid flow, heat transfer, phase change, nonlinear solid mechanics and, possibly, electromagnetics together with their interactions, in what is now known as multiphysics simulation. Such simulations are computationally intensive and the implementation of solution strategies for multiphysics calculations must embed their effective parallelization. For some years, together with our collaborators, we have been involved in the development of numerical software tools for multiphysics modeling on parallel cluster systems. This research has involved a combination of algorithmic procedures, parallel strategies and tools, plus the design of a computational modeling software environment and its deployment in a range of real world applications. One output from this research is the three-dimensional parallel multiphysics code, PHYSICA. In this paper we report on an assessment of its parallel scalability on a range of increasingly complex models drawn from actual industrial problems, on three contemporary parallel cluster systems.

Emergent self-organisation of wireless sensor networks

This paper describes a protocol for dynamically configuring wireless sensor nodes into logical clusters. The concept is to be able to inject an overlay configuration into an ad-hoc network of sensor nodes or similar devices, and have the network configure itself organically. The devices are arbitrarily deployed and have initially have no information whatsoever concerning physical location, topology, density or neighbourhood. The Emergent Cluster Overlay (ECO) protocol is totally self-configuring and has several novel features, including nodes self-determining their mobility based on patterns of neighbour discovery, and that the target cluster size is specified externally (by the sensor network application) and is not directly coupled to radio communication range or node packing density. Cluster head nodes are automatically assigned as part of the cluster configuration process, at no additional cost. ECO is ideally suited to applications of wireless sensor networks in which localized groups of sensors act cooperatively to provide a service. This includes situations where service dilution is used (dynamically identifying redundant nodes to conserve their resources).

On the application of variable frequency microwave technology for processing of individual surface mount components

Dual-section variable frequency microwave systems enable rapid, controllable heating of materials within an individual surface mount component in a chip-on=board assembly. The ability to process devices individually allows components with disparate processing requirements to be mounted on the same assembly. The temperature profile induced by the microwave system can be specifically tailored to the needs of the component, allowing optimisation and degree of cure whilst minimising thermomechanical stresses. This paper presents a review of dual-section microwave technology and its application to curing of thermosetting polymer materials in microelectronics applications. Curing processes using both conventional and microwave technologies are assessed and compared. Results indicate that dual-section microwave systems are able to cure individual surface mount packages in a significantly shorter time, at the expense of an increase in thermomechanical stresses and a greater variation in degree of cure.

Individual crisis episodes and cultural transition: finding the macrocosm in the microcosm

According to dialogical self theory (Hermans, 2001), individual identities reflect cultural and subcultural values, and appropriate voices and discourses from the social environment. Bronfenbrenner’s (1979) systemic theory of human development similarly postulates that individual and social development occur in a symbiotic and interdependent fashion. It would therefore be predicted that individual changes in identity reflect macrocosmic changes in cultural values and social structures. The current study investigated narratives of crisis transitions within adults aged 25-40, by way of interviews with 22 participants. An intensive qualitative analysis showed that the narratives of crisis could indeed be viewed as individual manifestations of contemporary cultural changes. National statistics and academic research have documented in the UK substantial cultural shifts over the last twenty years including the lessening popularity of marriage, the rise of freelance and portfolio careers and the growth of accepted alternative gender roles. In individual crises, changes made over the course of the episode were invariably in the same direction as these social changes; towards flexible work patterns, non-marital relationships and redefined gender identities. Before the crisis, participants described their identity as bound into an established discourse of conventionality, a traditional sense of masculinity or feminitity and a singular career role, while after the crisis alternative and fluid identities are explored, and identity is less defined by role and institution. These findings show that changes in the social macrocosm can be found in the individual microcosm, and therefore support dialogical self theory.