An extension of classical theory of connection networks is defined and studied. This extension models systems in which multiple connections of differing data rates share the links within a network. We determine conditions under which the Clos and Cantor networks are strictly nonblocking for multirate traffic. We also determine conditions under which the Benes Network and variants of the Cantor and Clos networks are rearrangeable. We find that strictly nonblocking operation can be obtained for multirate traffic with essentially the same complexity as in the classical context.

The practice of regular physical exercise is a protective factor against noncommunicable diseases and premature mortality. In spite of that, large part of the population does not meet physical activity guidelines and many individuals live a sedentary life. Recent technological progresses and the widespread adoption of mobile technology, such as smartphone and wearables, have opened the way to the development of digital behaviour change interventions targeting physical activity promotion. Such interventions would greatly benefit from the inclusion of computational models framed on behaviour change theories and model-based reasoning. However, research on these topics is still at its infancy. The current paper presents a smartphone application and wearable device system called Muoviti! that targets physical activity promotion among adults not meeting the recommended physical activity guidelines. Specifically, we propose a computational model of behaviour change, grounded on the social cognitive theory of self-efficacy. The purpose of the computational model is to dynamically integrate information referring to individuals’ self-efficacy beliefs and physical activity behaviour in order to define exercising goals that adapt to individuals’ changes over time. The paper presents (i) the theoretical constructs that informed the development of the computational model, (ii) an overview of Muoviti! describing the system dynamics, the graphical user interface, the adopted measures and the intervention design, and (iii) the computational model based on Dynamic Decision Network. We conclude by presenting early results from an experimental study.

The Clos networks are a class of multistage switching network topologies that provide alternate paths between inputs and outputs, making it possible to minimize or eliminate the blocking that can otherwise occur in such networks. In his seminal paper in the Bell System Technical Journal in 1953, Charles Clos showed how these networks could be configured to make them nonblocking and effectively launched the systematic study of switching system performance, a field that has developed a rich technical literature and which continues to be very active and of continuing practical importance. This paper describes how Clos' results have been generalized to systems that support connections with varying bandwidth requirements. These generalizations have extended the application of Clos networks well beyond their original technological context and have led to a number of interesting new results, especially in connection with systems that support multicast communication.

Abstract. This paper examines a network architecture designed to offer interactive video services to residential subscribers. Its main feature consists in the possibility of storing heavily requested material in video "cache" locations at the local switch level. Various policies for the management of the resulting hierarchical storage system are defined and their effectiveness, in terms of success ratio of the local accesses, is evaluated via simulation. A simple evaluation of the cost trade-off between distributing video programs in local memories and keeping them in a centralized video server is carried out as well, considering both leased line and switched line solutions for long distance transmission. The difference due to the non stationary behaviour of the user requests is also evaluated.

| This paper generalizes known results for nonblocking distribution networks (also known as generalized connection networks) to the multirate environment, where di erent user connections share a switch's internal data paths in arbitrary fractions of the total capacity. In particular, we derive conditions under which networks due to Ofman and Thompson, Pippenger, and Turner lead to multirate distribution networks. Our results include both rearrangeable and wide-sense nonblocking n e t works. The complexity of the rearrangeable multirate networks exceeds that of the corresponding space division network by a log log factor while the complexity of the wide sense nonblocking networks is within a factor of two of the corresponding space division networks.