Strategies for resolving security and interference issues in 802.11 wireless computer networking : a thesis presented in partial fulfilment of the requirements for the degree of Masters in Engineering in Computer Systems Engineering at Massey University, Palmerston North, New Zealand

This thesis presents the outcomes of the research and development of strategies to improve 802.11 wireless networking security, reduce interference, and investigation into the trends of home users in the city limits of Palmerston North, New Zealand. The main contributions of the research are several types of improvement strategies that reduce interference, add additional layers of security to 802.11, and reports on wireless trends. The thesis begins with an overview of the current 802.11 security protocols and related issues. The current state of the 802.11 security is presented along with an assessment of efficacy of 802.11. Lastly, the motivations for improving security and reducing interference are explained. The main improvement presented within the thesis is that of client filtering. The operation of filtering is explained. Using methods from other filtering protocols its shown that how an additional layer of security can be added to 802.11. Following this, more improvements are shown that can be used with or without client filtering. The use of smart aerials, wizards and frequency selective materials is discussed and the advantages and disadvantages of each are highlighted, as well as the aspects and issues of implementing the strategies on a home personal computer based platform are presented. This is followed by a description of the experiments conducted into attenuation and direction sensing. The results of the experiments are presented along with the discussion. Finally, conclusions about the improvements are detailed and the results shown, in addition to research conducted on the trends of 802.11 users to further highlight the need for this research

Insights into the pulmonary vascular complications of heart failure with preserved ejection fraction

Pulmonary hypertension in the setting of heart failure with preserved ejection fraction (PH-HFpEF) is a growing public health problem that is increasing in prevalence. While PH-HFpEF is defined by a high mean pulmonary artery pressure, high left ventricular end-diastolic pressure and a normal ejection fraction, some HFpEF patients develop PH in the presence of pulmonary vascular remodelling with a high transpulmonary pressure gradient or pulmonary vascular resistance. Ageing, increased left atrial pressure and stiffness, mitral regurgitation, as well as features of metabolic syndrome, which include obesity, diabetes and hypertension, are recognized as risk factors for PH-HFpEF. Qualitative studies have documented that patients with PH-HFpEF develop more severe symptoms than those with HFpEF and are associated with more significant exercise intolerance, frequent hospitalizations, right heart failure and reduced survival. Currently, there are no effective therapies for PH-HFpEF, although a number of candidate drugs are being evaluated, including soluble guanylate cyclase stimulators, phosphodiesterase type 5 inhibitors, sodium nitrite and endothelin receptor antagonists. In this review we attempt to provide an updated overview of recent findings pertaining to the pulmonary vascular complications in HFpEF in terms of clinical definitions, epidemiology and pathophysiology. Mechanisms leading to pulmonary vascular remodelling in HFpEF, a summary of pre-clinical models of HFpEF and PH-HFpEF, and new candidate therapeutic strategies for the treatment of PH-HFpEF are summarized

Back to Back Theatre’s ‘Ganesh versus the Third Reich’: Politics, representation and response

This panel considers the work of the Australian contemporary performance company Back to Back Theatre within the context of the conference theme of ‘cultural articulations’. We will address the ways in which religious objections to Ganesh versus the Third Reich were entwined with questions about the economic impact of these objections in attempts to censor and control the work. Helena Grehan’s paper will analyse the production Ganesh versus the Third Reich in terms of the ethical, political and social questions the work engenders. Peter Eckersall’s 'Theatre Love' The paper considers some of the possible ways that reading Back to Back’s theatre might respond to the current wave of a politics where opposition is an end in itself, whereas the idea of ‘taking sides’ requires a radical appreciation of the other. The third element is a roundtable discussion/interview with Bruce Gladwin (Director of Back to Back Theatre) and Alice Nash (Executive Producer Back to Back Theatre

Improved decision support for engine-in-the-loop experimental design optimization

Experimental optimization with hardware in the loop is a common procedure in engineering and has been the subject of intense development, particularly when it is applied to relatively complex combinatorial systems that are not completely understood, or where accurate modelling is not possible owing to the dimensions of the search space. A common source of difficulty arises because of the level of noise associated with experimental measurements, a combination of limited instrument precision, and extraneous factors. When a series of experiments is conducted to search for a combination of input parameters that results in a minimum or maximum response, under the imposition of noise, the underlying shape of the function being optimized can become very difficult to discern or even lost. A common methodology to support experimental search for optimal or suboptimal values is to use one of the many gradient descent methods. However, even sophisticated and proven methodologies, such as simulated annealing, can be significantly challenged in the presence of noise, since approximating the gradient at any point becomes highly unreliable. Often, experiments are accepted as a result of random noise which should be rejected, and vice versa. This is also true for other sampling techniques, including tabu and evolutionary algorithms. After the general introduction, this paper is divided into two main sections (sections 2 and 3), which are followed by the conclusion. Section 2 introduces a decision support methodology based upon response surfaces, which supplements experimental management based on a variable neighbourhood search and is shown to be highly effective in directing experiments in the presence of a significant signal-to-noise ratio and complex combinatorial functions. The methodology is developed on a three-dimensional surface with multiple local minima, a large basin of attraction, and a high signal-to-noise ratio. In section 2, the methodology is applied to an automotive combinatorial search in the laboratory, on a real-time engine-in-the-loop application. In this application, it is desired to find the maximum power output of an experimental single-cylinder spark ignition engine operating under a quasi-constant-volume operating regime. Under this regime, the piston is slowed at top dead centre to achieve combustion in close to constant volume conditions. As part of the further development of the engine to incorporate a linear generator to investigate free-piston operation, it is necessary to perform a series of experiments with combinatorial parameters. The objective is to identify the maximum power point in the least number of experiments in order to minimize costs. This test programme provides peak power data in order to achieve optimal electrical machine design. The decision support methodology is combined with standard optimization and search methods – namely gradient descent and simulated annealing – in order to study the reductions possible in experimental iterations. It is shown that the decision support methodology significantly reduces the number of experiments necessary to find the maximum power solution and thus offers a potentially significant cost saving to hardware-in-the-loop experi- mentation

Editorial

Editorial by Roger Gladwi

A decision support methodology for process in the loop optimisation

Experimental optimisation with hardware-in-the-loop is a common procedure in engineering, particularly in cases where accurate modelling is not possible. A common methodology to support experimental search is to use one of the many gradient descent methods. However, even sophisticated and proven methodologies such as Simulated Annealing (SA) can be significantly challenged in the presence of significant noise. This paper introduces a decision support methodology based upon Response Surfaces (RS), which supplements experimental management based on variable neighbourhood search, and is shown to be highly effective in directing experiments in the presence of significant signal to noise (S-N) ratio and complex combinatorial functions. The methodology is developed on a 3-dimensional surface with multiple local-minima and large basin of attraction, and high S-N ratio. Finally, the method is applied to a real-life automotive experimental application

On certain new integrable second order nonlinear differential equations and their connection with two dimensional Lotka-Volterra system

In this paper, we consider a second order nonlinear ordinary differential equation of the form $\ddot{x}+k_1\frac{\dot{x}^2}{x}+(k_2+k_3x)\dot{x}+k_4x^3+k_5x^2+k_6x=0$, where $k_i$'s, $i=1,2,...,6,$ are arbitrary parameters. By using the modified Prelle-Singer procedure, we identify five new integrable cases in this equation besides two known integrable cases, namely (i) $k_2=0, k_3=0$ and (ii) $k_1=0, k_2=0, k_5=0$. Among these five, four equations admit time dependent first integrals and the remaining one admits time independent first integral. From the time independent first integral, nonstandard Hamiltonian structure is deduced thereby proving the Liouville sense of integrability. In the case of time dependent integrals, we either explicitly integrate the system or transform to a time-independent case and deduce the underlying Hamiltonian structure. We also demonstrate that the above second order ordinary differential equation is intimately related to the two-dimensional Lotka-Volterra (LV) system. From the integrable parameters of above nonlinear equation and all the known integrable cases of the latter can be deduced thereby.Comment: Accepted for publication in J. Math. Phy

Editorial

The first issue of New Directions was issued in May 2003 and comprised 17 articles.In this this issue we present a series of 'reviews' of topics in physical sciences education and educational research written by 'expert' practitioners. The publication also includes 'communications' which arise from a general call for contributions from the physical sciences education community and invited reports from the funded projects working in the physical sciences education arena. In order to increase the provenance of the journalall submissions to New Directions are peer reviewed at both the initial and the final submission stages. Once again, the Editorial Team at the Physical Sciences Centre (Roger Gladwin, Tina Overton and Paul Chin) has been pleased to work with Derek Raine at Leicester University (now in association with πCETL, The Physics Innovations Centre for Excellence in Teaching and Learning) on this issue