1,852 research outputs found
A methodology for the evaluation of program cost and schedule risk for the SEASAT program
An interactive computerized project management software package (RISKNET) is designed to analyze the effect of the risk involved in each specific activity on the results of the total SEASAT-A program. Both the time and the cost of each distinct activity can be modeled with an uncertainty interval so as to provide the project manager with not only the expected time and cost for the completion of the total program, but also with the expected range of costs corresponding to any desired level of significance. The nature of the SEASAT-A program is described. The capabilities of RISKNET and the implementation plan of a RISKNET analysis for the development of SEASAT-A are presented
Critical scaling for yield is independent from distance to isostaticity
Using discrete element simulations, we demonstrate that critical behavior for
yielding in soft disk and sphere packings is independent of distance to
isostaticity over a wide range of dimensionless pressures. Jammed states are
explored via quasistatic shear at fixed pressure, and the statistics of the
dimensionless shear stress of these states obey a scaling description
with diverging length scale . The critical
scaling functions and values of the scaling exponents are nearly independent of
distance to isostaticity despite the large range of pressures studied. Our
results demonstrate that yielding of jammed systems represents a distinct
nonequilibrium critical transition from the isostatic critical transition which
has been demonstrated by previous studies. Our results may also be useful in
deriving nonlocal rheological descriptions of granular materials, foams,
emulsions, and other soft particulate materials
Weakness of Will: Holton's View and a Criticism
I presented an adjusted account of Richard Holton's understanding of weakness of will. The account I uphold is similar to Holton's account in as much as it relies on resolutions and unreasonable revisions to them. However, I offer an additional criterion to evaluating an agent for weakness of will: an agent is weak-willed if the agent unreasonably fails to form a resolution. Unreasonably failing to form a resolution turns out to be failing to form a resolution when an agent judges the action as the best thing to do and the agent believing that if the resolution was formed, the agent would follow through.No embargoAcademic Major: Philosoph
Novel main group metallacarboranes and their adducts - a synthetic and structural study
This thesis describes the synthesis and characterisation of a number of novel main group
metallacarboranes and the adducts that they form when treated with Lewis bases. The
structures of these species are discussed in detail, focussing in particular on the
orientation and inclination of the Lewis base and the slippage of the metal atom.
Chapter 1 outlines the most significant literature in the fields of boranes, carboranes
and metallacarboranes, providing the reader with an overview of these topics. The area
of main group metallacarboranes is covered in significant detail, as the running theme of
this thesis is the investigation of the role of main group metals in supraicosahedral
heteroboranes.
Chapter 2 details the syntheses and characterisations of icosahedral main group
metallacarboranes, as well as the adducts these species form with bipy. The significant
structural features of these adducts and the different factors that contribute to them are
discussed.
Chapter 3 features the preparation of a series of adducts formed with the 13-vertex
stannacarborane 1,6-Me2-4,1,6-closo-SnC2B10H10, accompanied by a systematic
structural study of these compounds.
Chapter 4 reports the synthesis and crystallographic characterisation of 1,2-μ-(CH2)3-
4,1,2-closo-SnC2B10H10 and its adducts with a series of Lewis bases. An examination
into the structural differences found in this carbons-adjacent system compared to the
4,1,6-SnC2B10 carbons-apart system is presented.
Chapter 5 presents two new isomer types within the supraicosahedral main group
metallacarborane system. The synthesis and characterisation of the first 4,1,10-closo-
SnC2B10 species is described, together with its thermal isomerisation to the 4,1,12-
analogue. The importance and relevance of these results is fully discussed. This
chapter also includes evidence for the formation of a novel supraicosahedral mixed
metal species, with both a transition metal and a p-block metal incorporated into the
cage framework.
Chapter 6 gives full details of the experimental procedures undertaken and also
provides spectroscopic and analytical data for all the new compounds reported herein.
Appendix 1 provides details of the crystal structure determinations of compounds
synthesised. Appendix 2 (provided on compact disk) gives the appropriate files in RTF
and CIF format
Congestion Pricing: Long-Term Economic and Land-Use Effects
We employ a spatially disaggregated general equilibrium model of a regional economy that incorporates decisions of residents, firms, and developers integrated with a spatially disaggregated strategic transportation planning (START) model that features mode, time period, and route choice to evaluate economic effects of congestion pricing. First, we evaluate the long-run effects of a road-pricing policy based on the integrated model of land use, strategic transport, and regional economy (LUSTRE) and compare them with the short-term effects obtained from the START model alone. We then look at distributional effects of the policy in question and point out differences and similarities in the short run versus the long run. Finally, we analyze the mechanisms at the source of the economic and land-use effects induced by the road-pricing policy.traffic congestion, welfare analysis, CGE modeling, cordon tolls, distributional effects
Long-Term Consequences of Congestion Pricing: A Small Cordon in the Hand Is Worth Two in the Bush
We evaluate and compare the long-term economic effects of three cordon-based road pricing schemes applied to the Washington, DC, metropolitan area. To conduct this analysis, we employ a spatially disaggregated general equilibrium model of a regional economy that incorporates the decisions of residents, firms, and developers, integrated with a spatially disaggregated strategic transportation planning model that features mode, time period, and route choice. We find that all cordon pricing schemes increase welfare of the residents, as well as lead to GDP growth. At the optimum, the larger cordon and a double cordon lead to higher benefits than the small cordon encompassing downtown core. Nevertheless, the small cordon seems to be a safer bet because when the toll charge is set suboptimally, the net benefits from the small cordon compared to the optimum change negligibly, while the net benefits from the larger cordon decline sharply as the charge deviates from the optimal level.traffic congestion, cordon tolls, land use, welfare analysis, road pricing, general equilibrium, simulation, Washington DC
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