1,454 research outputs found

    Cost Escalation in Nuclear Power

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    This report is concerned with the escalation of capital costs of nuclear central station power plants between the early 1960s and the present. The report presents an historical overview of the development of the nuclear power industry and cost escalation in the industry, using existing data on orders and capital costs. New data are presented on regulatory delays in the licensing process, derived from a concurrent study being carried on in the Social Science group at Caltech. The conclusions of the study are that nuclear capital costs have escalated more rapidly than the GNP deflator or the construction industry price index. Prior to 1970, cost increases are related to bottleneck problems in the nuclear construction and supplying industries and the regulatory process; intervenors play only a minor role in cost escalation. After 1970, generic changes introduced into the licensing process by intervenors (including environmental impact reviews, antitrust reviews, more stringent safety standards) dominate the cost escalation picture, with bottlenecks of secondary importance. Recent increases in the time from application for a construction permit to commercial operation are related not only to intervenor actions, but also to suspensions, cancellations or postponements of construction by utilities due to unfavorable demand or financing conditions

    Accounting for Selective Grazing in the Stocking Rate Decision

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    We describe the development and use of a simple, generic method for predicting botanical composition of herbivore diets, thereby allowing resource managers to consider selective foraging when setting stocking rates. For a particular season and herbivore, we found that forage species fall into one of 3 selection categories: preferred (consistently selected for), undesirable (consistently selected against), and variable (inconsistent selection pattern). Our studies showed that, for most situations, dietary composition is adequately predicted from regression relationships with the field proportions of preferred and undesirable species. We demonstrate how this method can help address issues such as the conservation of preferred forage species and the effect of multispecies grazing on carrying capacity

    Wetland mapping from digitized aerial photography

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    Computer assisted interpretation of small scale aerial imagery was found to be a cost effective and accurate method of mapping complex vegetation patterns if high resolution information is desired. This type of technique is suited for problems such as monitoring changes in species composition due to environmental factors and is a feasible method of monitoring and mapping large areas of wetlands. The technique has the added advantage of being in a computer compatible form which can be transformed into any georeference system of interest

    Factor Bias and Innovations: A Microeconomic Approach

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    This paper contains a microeconomic analysis of the influence of change in relative prices on the direction of inventive activity. A control-theory model of a firm which produces final output and also performs research and development is developed. It is assumed that the output of R & D is factor-augmenting technical change. An innovation possibility frontier for the firm is defined and conditions are found under which it is convex. The major theorems relate the change in innovation in response to changing factor prices to the elasticity of substitution in producing final output and to the nature of the production functions for innovation. Two special cases are examined in detail. When current innovation possibilities are appropriately independent of past innovations, the rate of factor augmentation is the same for all factors where relative prices are constant at any level. Comparing time paths with different, constant relative prices gives conditions under which an increase in the price of a factor directs innovation into lines which economize on that factor. A summary of earlier results on similar subjects is included

    Ignition of thermally sensitive explosives between a contact surface and a shock

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    The dynamics of ignition between a contact surface and a shock wave is investigated using a one-step reaction model with Arrhenius kinetics. Both large activation energy asymptotics and high-resolution finite activation energy numerical simulations are employed. Emphasis is on comparing and contrasting the solutions with those of the ignition process between a piston and a shock, considered previously. The large activation energy asymptotic solutions are found to be qualitatively different from the piston driven shock case, in that thermal runaway first occurs ahead of the contact surface, and both forward and backward moving reaction waves emerge. These waves take the form of quasi-steady weak detonations that may later transition into strong detonation waves. For the finite activation energies considered in the numerical simulations, the results are qualitatively different to the asymptotic predictions in that no backward weak detonation wave forms, and there is only a weak dependence of the evolutionary events on the acoustic impedance of the contact surface. The above conclusions are relevant to gas phase equation of state models. However, when a large polytropic index more representative of condensed phase explosives is used, the large activation energy asymptotic and finite activation energy numerical results are found to be in quantitative agreement

    Intraoperative detection of blood vessels with an imaging needle during neurosurgery in humans

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    Intracranial hemorrhage can be a devastating complication associated with needle biopsies of the brain. Hemorrhage can occur to vessels located adjacent to the biopsy needle as tissue is aspirated into the needle and removed. No intraoperative technology exists to reliably identify blood vessels that are at risk of damage. To address this problem, we developed an “imaging needle” that can visualize nearby blood vessels in real time. The imaging needle contains a miniaturized optical coherence tomography probe that allows differentiation of blood flow and tissue. In 11 patients, we were able to intraoperatively detect blood vessels (diameter, \u3e500 μm) with a sensitivity of 91.2% and a specificity of 97.7%. This is the first reported use of an optical coherence tomography needle probe in human brain in vivo. These results suggest that imaging needles may serve as a valuable tool in a range of neurosurgical needle interventions

    Numerical experiments on short-term meteorological effects on solar variability

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    A set of numerical experiments was conducted to test the short-range sensitivity of a large atmospheric general circulation model to changes in solar constant and ozone amount. On the basis of the results of 12-day sets of integrations with very large variations in these parameters, it is concluded that realistic variations would produce insignificant meteorological effects. Any causal relationships between solar variability and weather, for time scales of two weeks or less, rely upon changes in parameters other than solar constant or ozone amounts, or upon mechanisms not yet incorporated in the model

    Grain boundaries in polycrystalline materials for energy applications: First principles modeling and electron microscopy

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    \ua9 2024 Author(s). Polycrystalline materials are ubiquitous in technology, and grain boundaries have long been known to affect materials properties and performance. First principles materials modeling and electron microscopy methods are powerful and highly complementary for investigating the atomic scale structure and properties of grain boundaries. In this review, we provide an introduction to key concepts and approaches for investigating grain boundaries using these methods. We also provide a number of case studies providing examples of their application to understand the impact of grain boundaries for a range of energy materials. Most of the materials presented are of interest for photovoltaic and photoelectrochemical applications and so we include a more in depth discussion of how modeling and electron microscopy can be employed to understand the impact of grain boundaries on the behavior of photoexcited electrons and holes (including carrier transport and recombination). However, we also include discussion of materials relevant to rechargeable batteries as another important class of materials for energy applications. We conclude the review with a discussion of outstanding challenges in the field and the exciting prospects for progress in the coming years
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