75,664 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
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
Replication Regulates Volume Weighting in Quantum Cosmology
Probabilities for observations in cosmology are conditioned both on the
universe's quantum state and on local data specifying the observational
situation. We show the quantum state defines a measure for prediction through
such conditional probabilities that is well behaved for spatially large or
infinite universes when the probabilities that our data is replicated are taken
into account. In histories where our data are rare volume weighting connects
top-down probabilities conditioned on both the data and the quantum state to
the bottom-up probabilities conditioned on the quantum state alone. We apply
these principles to a calculation of the number of inflationary e-folds in a
homogeneous, isotropic minisuperspace model with a single scalar field moving
in a quadratic potential. We find that volume weighting is justified and the
top-down probabilities favor a large number of e-folds.Comment: 13 pages, 3 figures; v2: correction case of data on multiple
surfaces, clarification objectivit
Quantum Transitions Between Classical Histories: Bouncing Cosmologies
In a quantum theory of gravity spacetime behaves classically when quantum
probabilities are high for histories of geometry and field that are correlated
in time by the Einstein equation. Probabilities follow from the quantum state.
This quantum perspective on classicality has important implications: (a)
Classical histories are generally available only in limited patches of the
configuration space on which the state lives. (b) In a given patch states
generally predict relative probabilities for an ensemble of possible classical
histories. (c) In between patches classical predictability breaks down and is
replaced by quantum evolution connecting classical histories in different
patches. (d) Classical predictability can break down on scales well below the
Planck scale, and with no breakdown in the classical equations of motion. We
support and illustrate (a)-(d) by calculating the quantum transition across the
de Sitter like throat connecting asymptotically classical, inflating histories
in the no-boundary quantum state. This supplies probabilities for how a
classical history on one side transitions and branches into a range of
classical histories on the opposite side. We also comment on the implications
of (a)-(d) for the dynamics of black holes and eternal inflation.Comment: 37 pages, 5 figures, minor corrections, results not change
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