1,242 research outputs found

    Optimal sliding scale regulation: An application to regional electricity distribution in England and Wales

    Get PDF
    This paper examines optimal price (i.e. ā€˜sliding scaleā€™) regulation of a monopoly when productivity and managerial effort are not observed. We show how to operationalise this model of incentive regulation and use actual data from electricity distribution in England and Wales to make welfare comparisons of sliding scale regulation with a stylised price cap regime and the First-Best (the full information case). Our method enables us to quantify technical uncertainty as faced by the electricity regulator in the 1990s and shows that there are significant welfare gains from a sliding scale relative to the stylised price cap regime.Sliding scale, regulation, electricity distribution

    Twentieth century light curves and the nucleus of comet P/Tempel 2

    Get PDF
    Observations of P/Tempel 2 from 1899 to 1988 corresponding to 13 apparitions are analyzed in order to estimate the perihelion asymmetry of the gas production curve for different periods of its evolution. Using the correlation found by Festou et al. (1990) between the perihelion asymmetries and the delay in perihelion passage due to the action of nongravitational forces, we estimate the mass of the comet to be M approximately equals 1.6 plus or minus 0.5 x 10(exp 14) kg. Assuming a volume of 500 cu km, based on nuclear observations, a density of 0.3 plus or minus 0.1 g/cu cm is obtained

    The Use of the Airborne Thermal/Visible Land Application Sensor (ATLAS) to Determine the Thermal Response Numbers for Urban Areas

    Get PDF
    Although satellite data are very useful for analysis of the urban heat island effect at a coarse scale, they do not lend themselves to developing a better understanding of which surfaces across the city contribute or drive the development of the urban heat island effect. Analysis of thermal energy responses for specific or discrete surfaces typical of the urban landscape (e.g., asphalt, building rooftops, vegetation) requires measurements at a very fine spatial scale (i.e., < 15m) to adequately resolve these surfaces and their attendant thermal energy regimes. Additionally, very fine scale spatial resolution thermal infrared data, such as that obtained from aircraft, are very useful for demonstrating to planning officials, policy makers, and the general populace the benefits of the urban forest. These benefits include mitigating the urban heat island effect, making cities more aesthetically pleasing and more habitable environments, and aid in overall cooling of the community. High spatial resolution thermal data are required to quantify how artificial surfaces within the city contribute to an increase in urban heating and the benefit of cool surfaces (e.g., surface coatings that reflect much of the incoming solar radiation as opposed to absorbing it thereby lowering urban temperatures). The TRN (thermal response number)(Luvall and Holbo 1989) is a technique using aircraft remotely sensed surface temperatures to quantify the thermal response of urban surfaces. The TRN was used to quantify the thermal response of various urban surface types ranging from completely vegetated surfaces to asphalt and concrete parking lots for several cities in the United States

    NASA Perspective and Modeling of Thermal Runaway Propagation Mitigation in Aerospace Batteries

    Get PDF
    NASA has traditionally sought to reduce the likelihood of a single cell thermal runaway (TR) in their aerospace batteries to an absolute minimum by employing rigorous screening program of the cells. There was generally a belief that TR propagation resulting in catastrophic failure of the battery was a forgone conclusion for densely packed aerospace lithium-ion batteries. As it turns out, this may not be the case. An increasing number of purportedly TR propagation-resistant batteries are appearing among NASA partners in the commercial sector and the Department of Defense. In the recent update of the battery safety standard (JSC 20793) to address this paradigm shift, the NASA community included requirements for assessing TR severity and identifying simple, low-cost severity reduction measures. Unfortunately, there are no best-practice guidelines for this work in the Agency, so the first project team attempting to meet these requirements would have an undue burden placed upon them. A NASA engineering Safety Center (NESC) team set out to perform pathfinding activities for meeting those requirements. This presentation will provide contextual background to this effort, as well as initial results in attempting to model and simulate TR heat transfer and propagation within battery designs

    Failure of conventional retrograde cystography to detect bladder ruptures in pelvic trauma

    Get PDF
    Conventional retrograde cystography is often used to investigate patients with suspected bladder ruptures in pelvic trauma. Clinical indicators suggestive of a rupture include haematuria and suprapubic tenderness and should increase the suspicion of bladder and urinary tract injury and prompt the clinician to undertake further investigations. Two patients with high-energy pelvic fractures had bladder ruptures detected intraoperatively despite normal preoperative retrograde cystogram. Both patients had significant clinical indicators suggestive of underlying bladder and urinary tract injury. In both cases, a routine conventional retrograde cystogram was performed but failed to identify the full extent of the bladder injury. A possible reason for misdiagnosis in these cases is the delay between injury and investigation due to tertiary referral of care

    Lunar Regolith Simulant User's Guide

    Get PDF
    Based on primary characteristics, currently or recently available lunar regolith simulants are discussed from the perspective of potential experimental uses. The characteristics used are inherent properties of the material rather than their responses to behavioral (geomechanical, physiochemical, etc.) tests. We define these inherent or primary properties to be particle composition, particle size distribution, particle shape distribution, and bulk density. Comparable information about lunar materials is also provided. It is strongly emphasized that anyone considering either choosing or using a simulant should contact one of the members of the simulant program listed at the end of this document

    A survey of geographical information systems applications for the Earth Science and Applications Division, Space Sciences Laboratory, Marshall Space Flight Center

    Get PDF
    The purpose of this document is to introduce Geographical Information System (GIS) terminology and summarize interviews conducted with scientists in the Earth Science and Applications Division (ESAD). There is a growing need in ESAD for GIS technology. With many different data sources available to the scientists comes the need to be able to process and view these data in an efficient manner. Since most of these data are stored in vastly different formats, specialized software and hardware are needed. Several ESAD scientists have been using a GIS, specifically the Man-computer Interactive Data Access System (MCIDAS). MCIDAS can solve many of the research problems that arise, but there are areas of research that need more powerful tools; one such example is the multispectral image analysis which is described in this document. Given the strong need for GIS in ESAD, we recommend that a requirements analysis and implementation plan be developed using this document as a basis for further investigation

    Beneficiation of Stillwater Complex Rock for the Production of Lunar Simulants

    Get PDF
    The availability of pure, high calcium plagioclase would be a significant asset in any attempt to manufacture high-quality lunar simulants. A suitable plagioclase product can be obtained from materials obtained from the Stillwater Complex of Montana. The access, geology, petrology, and mineralogy of the relevant rocks and the mill tailings are described here. This study demonstrates successful plagioclase recovery from mill tailings produced by the Stillwater Mine Company. Hydrogen peroxide was used to remove carboxymethyl cellulose from the tailing. The characteristics of the plagioclase products are shown and locked grains are identified as a limit to achievable purity. Based on the experimental results, flowsheets were developed showing how these resources could be processed and made into 'separates' of (1) high calcium plagioclase and (2) orthopyroxene/clinopyroxene with the thought that they would be combined later to make simulant

    Generation of Requirements for Simulant Measurements

    Get PDF
    This TM presents a formal, logical explanation of the parameters selected for the figure of merit (FoM) algorithm. The FoM algorithm is used to evaluate lunar regolith simulant. The objectives, requirements, assumptions, and analysis behind the parameters are provided. A requirement is derived to verify and validate simulant performance versus lunar regolith from NASA s objectives for lunar simulants. This requirement leads to a specification that comparative measurements be taken the same way on the regolith and the simulant. In turn, this leads to a set of nine criteria with which to evaluate comparative measurements. Many of the potential measurements of interest are not defensible under these criteria. For example, many geotechnical properties of interest were not explicitly measured during Apollo and they can only be measured in situ on the Moon. A 2005 workshop identified 32 properties of major interest to users. Virtually all of the properties are tightly constrained, though not predictable, if just four parameters are controlled. Three parameters (composition, size, and shape) are recognized as being definable at the particle level. The fourth parameter (density) is a bulk property. In recent work, a fifth parameter (spectroscopy) has been identified, which will need to be added to future releases of the FoM
    • ā€¦
    corecore