70 research outputs found
The HIBEAM program: search for neutron oscillations at the ESS
With the construction of the European Spallation Source, a remarkable
opportunity has emerged to conduct high sensitivity searches for neutron
oscillations, including a first search for thirty years for free neutrons
converting to antineutrons. Furthermore, searches can be made for transitions
of neutrons and antineutrons to sterile neutron states. The HIBEAM program
provides an increase in sensitivity of an order of magnitude compared to
previous work.
The HIBEAM program corresponds to baryon number violation by one and two
units. The observation of a process satisfying a Sakharov condition addresses
the open question of the origin of the matter-antimatter asymmetry in the
Universe. Sterile neutron states would belong to a `dark' sector of particles
which may explain dark matter. As electrically neutral, meta-stable objects
that can be copiously produced and studied, neutrons represent an attractive
portal to a `dark' sector.
This paper describes the capability, design, infrastructure, and potential of
the HIBEAM program. This includes a dedicated beamline, neutron optical system,
magnetic shielding and control, and detectors for neutrons and antineutrons.Comment: 41 pages, 12 figure
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Integrated coal preparation and CWF processing plant: Conceptual design and costing. Final technical report
At the request of the US Department of Energy (DOE), Pittsburgh Energy Technology Center, a study was conducted to provide DOE with a reliable, documented estimate of the cost of producing coal-water fuel (CWF). The approach to the project was to specify a plant capacity and location, identify and analyze a suitable coal, and develop a conceptual design for an integrated coal preparation and CWF processing plant. Using this information, a definitive costing study was then conducted, on the basis of which an economic and sensitivity analysis was performed utilizing a financial evaluation model to determine a price for CWF in 1992. The design output of the integrated plant is 200 tons of coal (dry basis) per hour. Operating at a capacity factor of 83 percent, the baseline design yields approximately 1.5 million tons per year of coal on a dry basis. This is approximately equivalent to the fuel required to continuously generate 500 MW of electric power. The CWF produced by the plant is intended as a replacement for heavy oil or gas in electric utility and large industrial boilers. The particle size distribution, particularly the top size, and the ash content of the coal in the CWF are specified at significantly lower levels than is commonly found in typical pulverized coal grinds. The particle top size is 125 microns (vs typically 300m{mu} for pulverized coal) and the coal ash content is 3.8 percent. The lower top size is intended to promote complete carbon burnout at less derating in boilers that are not designed for coal firing. The reduced mineral matter content will produce ash of very fine particle size during combustion, which leads to less impaction and reduced fouling of tubes in convective passages
Sociomateriality and information systems success and failure
The aim of this essay is to put forward a performative, sociomaterial perspective on Information Systems (IS) success and failure in organisations by focusing intently upon the discursive-material nature of IS development and use in practice. Through the application of Actor Network Theory (ANT) to the case of an IS that transacts insurance products we demonstrate the contribution of such a perspective to the understanding of how IS success and failure occur in practice. The manuscript puts our argument forward by first critiquing the existing perspectives on IS success and failure in the literature for their inadequate consideration of the materiality of IS, of its underling technologies and of the entanglement of the social and material aspects of IS development and use. From a sociomaterial perspective IS are not seen as objects that impact organisations one way or another, but instead as relational effects continually enacted in practice. As enactments in practice IS development and use produce realities of IS success and failure
Global Uncertainty Propagation and Sensitivity Analysis in the CH₃OCH₂ + O₂ System: Combining Experiment and Theory To Constrain Key Rate Coefficients in DME Combustion
Statistical rate theory calculations, in particular formulations of the chemical master equation, are widely used to calculate rate coefficients of interest in combustion environments as a function of temperature and pressure. However, despite the increasing accuracy of electronic structure calculations, small uncertainties in the input parameters for these master equation models can lead to relatively large uncertainties in the calculated rate coefficients. Master equation input parameters may be constrained further by using experimental data and the relationship between experiment and theory warrants further investigation. In this work, the CH₃OCH₂ + O₂ system, of relevance to the combustion of dimethyl ether (DME), is used as an example and the input parameters for master equation calculations on this system are refined through fitting to experimental data. Complementing these fitting calculations, global sensitivity analysis is used to explore which input parameters are constrained by which experimental conditions, and which parameters need to be further constrained to accurately predict key elementary rate coefficients. Finally, uncertainties in the calculated rate coefficients are obtained using both correlated and uncorrelated distributions of input parameters
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