A case for cross layer design: the impact of physical layer properties on routing protocol performance in MANETs

In this work we evaluate the performance of routing protocols for mobile ad hoc networks using different physical layer models. The results obtained show that the performance results obtained using idealized models such as the free space propagation model vary significantly when propagation effects such as path loss and shadowing are considered. This difference in performance indicates that optimization is required in the protocol development space that takes into account channel state information (CSI). Such an optimization requires a cross layer approach to be adopted and a framework for protocol performance evaluation to be established. We believe that this work would serve as a first step in this direction. We provide comparative performance results through network simulations.

Semi-hyperbolic mappings in Banach spaces

The definition of semi-hyperbolic dynamical systems generated by Lipschitz continuous and not necessarily invertible mappings in Banach spaces is presented in this thesis. Like hyperbolic mappings, they involve a splitting into stable and unstable spaces, but a slight leakage from the strict invariance of the spaces is possible and the unstable subspaces are assumed to be finite dimensional. Bi-shadowing is a combination of the concepts of shadowing and inverse shadowing and is usually used to compare pseudo-trajectories calculated by a computer with the true trajectories. In this thesis, the concept of bi-shadowing in a Banach space is defined and proved for semi-hyperbolic dynamical systems generated by Lipschitz mappings. As an application to the concept of bishadowing, linear delay differential equations are shown to be bi-shadowing with respect to pseudo-trajectories generated by nonlinear small perturbations of the linear delay equation. This shows robustness of solutions of the linear delay equation with respect to small nonlinear perturbations. Complicated dynamical behaviour is often a consequence of the expansivity of a dynamical system. Semi-hyperbolic dynamical systems generated by Lipschitz mappings on a Banach space are shown to be exponentially expansive, and explicit rates of expansion are determined. The result is applied to a nonsmooth noninvertible system generated by delay differential equation. It is shown that semi-hyperbolic mappings are locally φ-contracting, where -0 is the Hausdorff measure of noncompactness, and that a linear operator is semi-hyperbolic if and only if it is φ-contracting and has no spectral values on the unit circle. The definition of φ-bi-shadowing is given and it is shown that semi-hyperbolic mappings in Banach spaces are φ-bi-shadowing with respect to locally condensing continuous comparison mappings. The result is applied to linear delay differential equations of neutral type with nonsmooth perturbations. Finally, it is shown that a small delay perturbation of an ordinary differential equation with a homoclinic trajectory is ‘chaotic’.

The performing frame

This project explores the ways that creative practices—improvised movement, choreographed dance, and digital video—produce new knowledge about the sociability of public space. In other words, it uses various theoretical concepts and practical strategies to document and analyse the ways people inhabit and sometimes subvert public spaces — such as plazas, malls and piazzas — as part of their everyday experience. Drawing on concepts developed within the fields of performance theory, spatial history, cultural geography and social theory, the project will build a methodological toolbox for understanding the relationships between the diverse groups that use public spaces in Melbourne, Australia. This ‘toolbox’ will subsequently be used to understand analogous public spaces in other parts of the world to generate comparative data about spatial sociability. The research will enable an innovative way of mapping social, civic and political relations in space through a series of creative interventions, and will reveal the politics of everyday movement while exposing tensions between the spaces of public culture — those framed and legitimated by state institutions — and what Michael Warner calls ‘Counter-Publics.’ That is, those oppositional groups who actively seek to use public space in subversive or unauthorised ways.

This project documents a series of performative interventions designed to harness the untapped potential of various forms of street performance genres to function as tools that can produce new ways of understanding the politics of movement in public space. These ‘interventions’ will be generated through a series of practical performance and movement workshops that will draw on street theatre techniques, contact improvisation, Laban movement analysis and contemporary dance choreography. The project will focus on a series of dyadic relationships: self and other, inside and outside, centre and periphery that are relevant to human interaction in public space.
Street performers — musicians, acrobats, jugglers, magicians, mimes and so on — seek public spaces with high volumes of pedestrian traffic in order to maximise their ability to draw an audience and make a living. These performers who create temporary performance zones alter the flow and intensity of movement around them, thereby transforming the plazas, piazzas, town squares and subways favoured by buskers. Some of these performers interact with their audience more than others, and are potentially capable of telling us something about the politics of space. The practice of ‘shadowing’ the movements of passers-by is an increasingly popular form of public entertainment around the world.