953 resultados para Controller designs


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The main objective of a steel strip rolling process is to produce high quality steel at a desired thickness.  Thickness reduction is the result of the speed difference between the incoming and the outgoing steel strip and the application of the large normal forces via the backup and the work rolls.  Gauge control of a cold rolled steel strip is achieved using the gaugemeter principle that works adequately for the input gauge changes and the strip hardness changes.  However, the compensation of some factors is problematic, for example, eccentricity of the backup rolls.  This cyclic eccentricity effect causes a gauge deviation, but more importantly, a signal is passed to the gap position control so to increase the eccentricity deviation.  Consequently, the required high product tolerances are severely limited by the presence of the roll eccentricity effects.
In this paper a direct model reference adaptive control (MRAC) scheme with dynamically constructed neural controller was used.  The aim here is to find the simplest controller structure capable of achieving an optimal performance.  The stability of the adaptive neural control scheme (i.e. the requirement of persistency of excitation and bounded learning rates) is addressed by using as the inputs to the reference model the plant's state variables.  In such a case, excitation is due to actual plant signals (states) affected by plant disturbances and noise.  In addition, a reference model in the form of a filter with a desired transfer function using Modulus Optimum design was used to ensure variance in the desired dynamic characteristics of the system.  The gradually decreasing learning rate employed by the neural controller in this paper is aimed at eliminating controller instability resulting from over-aggressive control.  The moving target problem (i.e. the difficulty of global neural networks to perfrom several separate computational tasks in closed -loop control) is addressed by the localized architecture of the controller.  The above control scheme and learning algorithm offers a method for automatic discovery of an efficient controller.
The resulting neural controller produces an excellent disturbance rejection in both cases of eccentricity and hardness disturbances, reducing the gauge deviation due to eccentricity disturbance from 33.36% to 4.57% on average, and the gauge deviation due to hardness disturbance from 12.59% to 2.08%.

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Background: Evidence on how to reduce the increasing prevalence of youth obesity is urgently needed in many countries.The Pacific OPIC Project (Obesity Prevention In Communities) is a series of linked studies in four countries (Fiji, Tonga, New Zealand, Australia) which is designed to address this important problem.
Objectives: The studies aim to: 1) determine the overall impact of comprehensive, community-based intervention programs on overweight/obesity prevalence in youth; 2) assess the feasibility of the specific intervention components and their impacts on eating and physical activity patterns; 3) understand the socio-cultural factors that promote obesity and how they can be infl uenced; 4) identify the effects of food-related policies in Fiji and Tonga and how they might be changed; 5) estimate the overall burden of childhood obesity (including loss of quality of life); 6) estimate the costs (and cost-effectiveness) of the intervention programs, and; 7) increase the capacity for obesity prevention research and action in Pacific populations.
Design: The community studies use quasi-experimental designs with impact and outcome assessments being measured in over 14,000 youth across the intervention and control communities in the four sites. The multi-strategy, multi-setting interventions will run for 3 years before fi nal follow up data are collected in 2008. The interventions are being informed by socio-cultural studies that will determine the family and societal infl uences on food intake, physical activity and body size perception.
Progress and conclusions: Baseline studies have been completed and interventions are underway. Despite the many challenges in implementing and evaluating community-based interventions, especially in the Pacifi c, the OPIC Project will provide rich evidence about what works and what does not work for obesity prevention in youth from European and Pacific backgrounds.

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This research details methods to improve upon current worst-case message response time analysis of CAN networks. Also, through the development of a CAN network model, and using modern simulation software, methods were shown to provide more realistic analyses of both sporadic and periodic messages on CAN networks prior to implementation.

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Peter Muller is one of the most unique Australian architects of the 20th century possessing a passion for organic architecture realised in several significant Australian and Indonesian design exemplars. His inquiry in the organic style of architecture stylistically mirrors that of Frank Lloyd Wright whom wrote to Muller expressing his pleasure in his successful pursuit of this style in Australia.3 This paper considers the position of moral rights under the Australian Copyright Act 19684 having regard to the Australian exemplars of Muller. It considers recent Australian debates about moral rights and projects that implicate several architectural and landscape architecture projects, the interpretations the legal fraternity are taking in approaching this topic, and positions the ideas, values, and attitudes of Muller in this context. Muller’s personal opinion is expressed providing an insight into the thoughts of one senior contemporary Australia architect as to 'their' architecture and ‘heritage’.

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