4,190 research outputs found

    Sustainable operations and maintenance of water supplies: a conceptual model for engineers and development workers : a thesis submitted in partial fulfilment of the requirement for the degree of Master of Philosophy in Development Studies and Agricultural Engineering at Massey University

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    There have been major problems with the sustainability of many water supply projects in the Developing World. One major area that influences this sustainability is the ongoing operation and maintenance of the water supply. A number of different surveys have shown that within 12 months of a water project being constructed and handed over to the community or government water dept. between 30-70% are not functioning at all or are not producing their original design supply. The purpose of the research was to produce a conceptual model that could be used by development agencies and engineers to increase the sustainability of water supplies. A review of the literature revealed that the major factors influencing sustainable operation and maintenance of water supplies were, technology, infrastructure for parts, training of both agency and community in maintenance of the water supply, the source of funding for O & M, design, ownership and responsibility, and management. These factors were incorporated into a conceptual model, each factor fitting into one or more of the different stages of a water supply project, namely: 1. Planning; 2. Design; 3. Construction; 4. Transfer Ceremony; and 5. Operations. There were up to four major groups of people involved in this process, namely, an International Development Agency, a Government Water Dept., a Community Water Committee, and a Community or Users. Surveys were conducted in Ethiopia, looking at both urban and rural water projects. The results were used to substantiate the model and/or to revise the model. It was concluded from the survey that the following were influential upon sustainable operation and maintenance in Ethiopia: Community ownership does not equate to community responsibility for O & M; Training of the individual or group responsible for O & M is essential; A lack of infrastructure leds to O & M problems; And, community involvement in all stages of the water supply project is essential. The revised conceptual model presents the processes and factors needed to instigate sustainable O & M of water supply projects in developing countries

    Thalamocortical Oscillations in Sleep and Anaesthesia

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    The last 20 years have seen a substantial advancement in the understanding of the molecular targets of general anaesthetics however the neural mechanisms involved in causing loss of consciousness remain poorly understood. Thalamocortical oscillations are present in natural sleep and are induced by many general anaesthetics suggesting that modulation of this reciprocal system may be involved in the regulation of consciousness. Dynamic changes of thalamocortical oscillations in natural sleep and anaesthesia were investigated in rats chronically implanted with skull screw and depth electrodes in the cortex and thalamus. The hypothesis that discrete areas within the thalamus are responsible for regulation of arousal was tested. The anaesthetics propofol and dexmedetomidine but not midazolam produced switches in delta frequency at loss of righting reflex (LORR). This switch in frequency mirrored that seen within non-rapid eye movement sleep (NREM), whereas the onset of NREM was characterized by a switch from theta to delta in the EEG. Depth recordings during NREM indicated that the switch into a NREM state occurred in the central medial thalamus (CMT) significantly before the cingulate, barrel cortex and ventrobasal nucleus (VB), and that the CMT switch corresponded to the switch seen in the global EEG. Dexmedetomidine hypnosis showed a delta frequency shift that occurred simultaneously within the thalamus and cortex, and furthermore that the thalamus exhibited phase advancement over the cortex at the point of LORR. In conclusion, globalised changes within the thalamocortical system occur for propofol and dexmedetomidine LORR in the rat. This change represents a transition within drug free NREM and may implicate a common pathway responsible for a decrease in arousal. Furthermore, the phase advancement of the intralaminar thalamus over the cortex at LORR suggests a crucial role for this part of the thalamocortical system for regulating consciousness

    Lessons learned in the development of the STOL intelligent tutoring system

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    Lessons learned during the development of the NASA Systems Test and Operations Language (STOL) Intelligent Tutoring System (ITS), being developed at NASA Goddard Space Flight Center are presented. The purpose of the intelligent tutor is to train STOL users by adapting tutoring based on inferred student strengths and weaknesses. This system has been under development for over one year and numerous lessons learned have emerged. These observations are presented in three sections, as follows. The first section addresses the methodology employed in the development of the STOL ITS and briefly presents the ITS architecture. The second presents lessons learned, in the areas of: intelligent tutor development; documentation and reporting; cost and schedule control; and tools and shells effectiveness. The third section presents recommendations which may be considered by other ITS developers, addressing: access, use and selection of subject matter experts; steps involved in ITS development; use of ITS interface design prototypes as part of knowledge engineering; and tools and shells effectiveness

    Bulk Sales Laws: A Study in Economic Adjustment

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    From 'tree' based Bayesian networks to mutual information classifiers : deriving a singly connected network classifier using an information theory based technique

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    For reasoning under uncertainty the Bayesian network has become the representation of choice. However, except where models are considered 'simple' the task of construction and inference are provably NP-hard. For modelling larger 'real' world problems this computational complexity has been addressed by methods that approximate the model. The Naive Bayes classifier, which has strong assumptions of independence among features, is a common approach, whilst the class of trees is another less extreme example. In this thesis we propose the use of an information theory based technique as a mechanism for inference in Singly Connected Networks. We call this a Mutual Information Measure classifier, as it corresponds to the restricted class of trees built from mutual information. We show that the new approach provides for both an efficient and localised method of classification, with performance accuracies comparable with the less restricted general Bayesian networks. To improve the performance of the classifier, we additionally investigate the possibility of expanding the class Markov blanket by use of a Wrapper approach and further show that the performance can be improved by focusing on the class Markov blanket and that the improvement is not at the expense of increased complexity. Finally, the two methods are applied to the task of diagnosing the 'real' world medical domain, Acute Abdominal Pain. Known to be both a different and challenging domain to classify, the objective was to investigate the optiniality claims, in respect of the Naive Bayes classifier, that some researchers have argued, for classifying in this domain. Despite some loss of representation capabilities we show that the Mutual Information Measure classifier can be effectively applied to the domain and also provides a recognisable qualitative structure without violating 'real' world assertions. In respect of its 'selective' variant we further show that the improvement achieves a comparable predictive accuracy to the Naive Bayes classifier and that the Naive Bayes classifier's 'overall' performance is largely due the contribution of the majority group Non-Specific Abdominal Pain, a group of exclusion

    Summer Movements of Bigmouth Buffalo in Lake Poinsett, South Dakota

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    Movements of bigmouth buffalo in Lake Poinsett, South Dakota were studied from 1 June to 31 August, 1968. Bigmouth buffalo were individually marked with Styrofoam floats and tracked visually during daylight hours. Buffalo at a relatively constant, slow rate averaging .346 km/hr (0.05 km/hr to 1.4 km/hr). Two study indicated that bigmouth buffalo in Lake Poinsett had no home range or homing tendency and inhabited all vertical strata. Bigmouth buffalo schools in Lake Poinsett exhibited a free interchange of individuals. An evaluation of large mesh gill nets as a commercial fishery tool indicated that 10.0 cm bar measure gill nets were most effective for harvesting bigmouth buffalo in Lake Poinsett
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