Decentralized Constraint Satisfaction

We show that several important resource allocation problems in wireless networks fit within the common framework of Constraint Satisfaction Problems (CSPs). Inspired by the requirements of these applications, where variables are located at distinct network devices that may not be able to communicate but may interfere, we define natural criteria that a CSP solver must possess in order to be practical. We term these algorithms decentralized CSP solvers. The best known CSP solvers were designed for centralized problems and do not meet these criteria. We introduce a stochastic decentralized CSP solver and prove that it will find a solution in almost surely finite time, should one exist, also showing it has many practically desirable properties. We benchmark the algorithm's performance on a well-studied class of CSPs, random k-SAT, illustrating that the time the algorithm takes to find a satisfying assignment is competitive with stochastic centralized solvers on problems with order a thousand variables despite its decentralized nature. We demonstrate the solver's practical utility for the problems that motivated its introduction by using it to find a non-interfering channel allocation for a network formed from data from downtown Manhattan

Development and fabrication of an advanced liquid cooling garment

The elastomeric film fin/tube concept which was developed is a composite of polyurethane film, fine expanded silver mesh, a serpentine pattern polyurethane transport tubing and an integral comfort liner, all bonded via adhesive application and vacuum-bagged for final cure. As demonstrated by thermal analysis, the composite garment material is capable of removing a 293 watt (1000 BTU/hr) metabolic load through a head and torso cooling area of .46 sq m (5 sq ft) with tube spacing of slightly under one inch. A total of 60 test elements, each .15m x .15m (6 in. x 6 in.) were fabricated in support of the liquid cooling garment concept development. In parallel with the fabrication of these elements a continuing series of laboratory tests to support the fabrication techniques was carried out. The elements and supporting tests are described

An ethnographic investigation of the relevance of shop floor culture to effective safety communication in an Australian minerals refinery

Many organisations which aim to achieve excellent workplace safety choose \u27culture change\u27 as the means to achieve this. They make use of employee communication media to help re-form the values, beliefs, norms and behaviours which are generally thought to comprise culture. However, culture is a complex and profound phenomenon. Successful communication between two culturally separate groups requires each to achieve an understanding of the other, no less so in workplaces than in societies composed of different cultures.Yet even employers who believe in communicating fully with their workforces find it difficult to convey viewpoints other than their own. Their communication tends therefore to be one-directional, asymmetrical and controlling, typified by the ubiquitous staff newsletter containing articles about people\u27s contribution to corporate goals. The messages contained in such media have little or none of their desired effect because they tend to be re-interpreted via the cultural forces of the workers to whom the messages are directed.This study investigated a large industrial minerals refinery to analyse the working lives of shop floor employees and the effectiveness of various communication channels. It focused on one group to whom safety messages were communicated, the shop floor `crews\u27, and examined how the organisation\u27s hierarchy, rules, and informal organisation mediated this communication

IDENTIFYING SOURCES OF THE TRAGEDY OF THE COMMONS IN ROOT COMPETITION: A SPATIALLY EXPLICIT SIMULATION MODEL AND PLANTS GROWN IN TRANSPARENT GROWTH MEDIUM

Existing research shows that plants produce less root when growing alone than when growing in competition with other plants. When plants under root competition over-allocate resources to roots at the cost of reproduction, it represents a Tragedy of the Commons. I constructed simulation models to determine the circumstances likely to give rise to a Tragedy of the Commons, and explore mechanisms by which plants may solve it. I grew plants in nutrient-rich transparent gel, allowing me to quantify root growth and development without destructive sampling. My plants responded positively to additional space and the presence of a competitor at full nutrient treatment levels, and negatively to those same conditions between low phosphorus treatment levels, demonstrating nutrient mediation of the direction of plant response to an added competitor with additional space. This effect may feature self / non-self recognition by roots. Since the hard barrier in these studies blocks nutrients, roots, and root signaling compounds from passing between the plants in the barrier treatment level, existing studies cannot tease apart the effects on plant development of these individual factors. I add a semi-permeable membrane treatment level, which allows nutrients and signaling compounds to pass while preventing root growth between sides

The influence of free-stream turbulence on separation of turbulent boundary layers in incompressible, two-dimensional flow

Experiments were conducted to determine if free-stream turbulence scale affects separation of turbulent boundary layers. In consideration of possible interrelation between scale and intensity of turbulence, the latter characteristic also was varied and its role was evaluated. Flow over a 2-dimensional airfoil in a subsonic wind tunnel was studied with the aid of hot-wire anemometry, liquid-film flow visualization, a Preston tube, and static pressure measurements. Profiles of velocity, relative turbulence intensity, and integral scale in the boundary layer were measured. Detachment boundary was determined for various angles of attack and free-stream turbulence. The free-stream turbulence intensity and scale were found to spread into the entire turbulent boundary layer, but the effect decreased as the airfoil surface was approached. When the changes in stream turbulence were such that the boundary layer velocity profiles were unchanged, detachment location was not significantly affected by the variations of intensity and scale. Pressure distribution remained the key factor in determining detachment location

Single-molecule Studies Of p53 Sliding Along DNA

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An Adaptive Capacity Guide Book: assessing, building and evaluating the capacity of communities to adapt in a changing climate

A capacity to adapt to change is essential for managing Australia’s natural resources. The individuals, communities and organisations who manage our natural resources all have an innate capacity to adapt to change. Changes in climate, markets and technology have shaped the way we adapt the management of natural resources in urban, rural and coastal landscapes. Some of these changes are predictable and easy to manage. Others are expected, but their timing and magnitude are uncertain. Whatever the future holds, this guide can be used to build our capacity to meet future change with confidence

Modelling 802.11 Wireless Links

Analysis of the 802.11 CSMA/CA mechanism has received considerable attention recently. Bianchi [3] presents an analytic model under a saturated traffic assumption. Bianchi’s model is accurate, but typical network conditions are nonsaturated heterogenous. We present an extension of his model to a non-saturated environment. The model’s predictions, validated against simulation, accurately capture many interesting features of non-saturated operation. For example, the model predicts that peak throughput occurs prior to saturation. Our model also allows stations to have different traffic arrival rates, enabling us to address the question of fairness between competing flows

Modelling 802.11 Wireless Links

Analysis of the 802.11 CSMA/CA mechanism has received considerable attention recently. Bianchi [3] presents an analytic model under a saturated traffic assumption. Bianchi’s model is accurate, but typical network conditions are nonsaturated heterogenous. We present an extension of his model to a non-saturated environment. The model’s predictions, validated against simulation, accurately capture many interesting features of non-saturated operation. For example, the model predicts that peak throughput occurs prior to saturation. Our model also allows stations to have different traffic arrival rates, enabling us to address the question of fairness between competing flows

Divide and conquer identification using Gaussian process priors

We investigate the reconstruction of nonlinear systems from locally identified linear models. It is well known that the equilibrium linearisations of a system do not uniquely specify the global dynamics. Information about the dynamics near to equilibrium provided by the equilibrium linearisations is therefore combined with other information about the dynamics away from equilibrium provided by suitable measured data. That is, a hybrid local/global modelling approach is considered. A non-parametric Gaussian process prior approach is proposed for combining in a consistent manner these two distinct types of data. This approach seems to provide a framework that is both elegant and powerful, and which is potentially in good accord with engineering practice