9,160 research outputs found

    Solid state sandwich concept: Designs, considerations and issues

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    Progress in analysis and design of solid state approaches to the solar power satellite microwave power transmission system is reviewed with special emphasis on the Sandwich concept and the issues of maintenance of low junction temperatures for amplifiers to assure acceptable lifetime. Ten specific issues or considerations are discussed and their resolution or status is presented

    Initial MPTS study results: Design considerations and issues

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    One of the key issues identified during investigations of microwave power transmission systems from 1965 to 1976 was the need to assure that the billions of diodes on ground-based rectennas are sufficiently reliable to support long life times of approximately 30 years. Major systems studies conducted focused on waveguides; radio frequency interference and biological considerations; the relationship between performance, weight, and cost; risk assessment; crossed field directional amplifier noise; a 48 kW klystron; effects of the environment on propagation and phase control; rectenna technology; a rationale for the ground power density region; alternate technologies for orbital assembly; ionospheric effects and phase control; and reception conversion (rf to dc collector/converter)

    Evolutionary Markovian Strategies in 2 x 2 Spatial Games

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    Evolutionary spatial 2 x 2 games between heterogeneous agents are analyzed using different variants of cellular automata (CA). Agents play repeatedly against their nearest neighbors 2 x 2 games specified by a rescaled payoff matrix with two parameteres. Each agent is governed by a binary Markovian strategy (BMS) specified by 4 conditional probabilities [p_R, p_S, p_T, p_P] that take values 0 or 1. The initial configuration consists in a random assignment of "strategists" among the 2^4= 16 possible BMS. The system then evolves within strategy space according to the simple standard rule: each agent copies the strategy of the neighbor who got the highest payoff. Besides on the payoff matrix, the dominant strategy -and the degree of cooperation- depend on i) the type of the neighborhood (von Neumann or Moore); ii) the way the cooperation state is actualized (deterministically or stochastichally); and iii) the amount of noise measured by a parameter epsilon. However a robust winner strategy is [1,0,1,1].Comment: 18 pages, 8 figures (7 of these figures contain 4 encapsulapted poscript files each

    Micropulsations in the electric field near the plasmapause, observed by ISEE-1

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    The occurrence of micropulsations near and inside the plasmapause was surveyed. The observed pulsations, classified as Pc3 and Pi2, are discussed. In addition one single event of Pc1 was observed. The frequencies in the Pc3 and Pi2 bands, the amplitude ranges, and the direction of rotation for the electric field vector are reported

    California Methanol Assessment; Volume II, Technical Report

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    A joint effort by the Jet Propulsion Laboratory and the California Institute of Technology Division of Chemistry and Chemical Engineering has brought together sponsors from both the public and private sectors for an analysis of the prospects for methanol use as a fuel in California, primarily for the transportation and stationary application sectors. Increasing optimism in 1982 for a slower rise in oil prices and a more realistic understanding of the costs of methanol production have had a negative effect on methanol viability in the near term (before the year 2000). Methanol was determined to have some promise in the transportation sector, but is not forecasted for large-scale use until beyond the year 2000. Similarly, while alternative use of methanol can have a positive effect on air quality (reducing NOx, SOx, and other emissions), a best case estimate is for less than 4% reduction in peak ozone by 2000 at realistic neat methanol vehicle adoption rates. Methanol is not likely to be a viable fuel in the stationary application sector because it cannot compete economically with conventional fuels except in very limited cases. On the production end, it was determined that methanol produced from natural gas will continue to dominate supply options through the year 2000, and the present and planned industry capacity is somewhat in excess of all projected needs. Nonsubsidized coal-based methanol cannot compete with conventional feedstocks using current technology, but coal-based methanol has promise in the long term (after the year 2000), providing that industry is willing to take the technical and market risks and that government agencies will help facilitate the environment for methanol. Given that the prospects for viable major markets (stationary applications and neat fuel in passenger cars) are unlikely in the 1980s and early 1990s, the next steps for methanol are in further experimentation and research of production and utilization technologies, expanded use as an octane enhancer, and selected fleet implementation. In the view of the study, it is not advantageous at this time to establish policies within California that attempt to expand methanol use rapidly as a neat fuel for passenger cars or to induce electric utility use of methanol on a widespread basis

    Evolutionary Stability of Ecological Hierarchy

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    A self-similar hierarchical solution that is both dynamically and evolutionarily stable is found to the multi dimensional Lotka-Volterra equation with a single chain of prey-predator relations. This gives a simple and natural explanation to the key features of hierarchical ecosystems, such as its ubiquity, pyramidal population distribution, and higher aggressiveness among higher trophic levels. pacs{87.23.Kg, 89.75.Da, 05.45.-a} keywords{Lotka-Volterra equation, Trophic pyramid, Self-similarity}Comment: 4 Pages RevTeX4, 1 Fig, 1 Table, shortened by publishers reques

    IMPLICATIONS OF THE TAX REFORM ACT OF 1976 FOR FARM ESTATE PLANNING

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    An intergeneration transfer simulation model is used to project estate transfer costs and the value of transfers to the heirs before and after the tax reform act of 1976. Lower Federal estate taxes result for estates that qualify for the special use valuation of farmland provision of the new law. Replacing the 60,000estateexemptionwiththe60,000 estate exemption with the 47,000 estate tax credit and revising the tax rate schedule increases Federal estate taxes when the taxable estate is between 1.175millionand1.175 million and 9.353 million. The new carryover basis rules for estate assets acquired from decedents dying after 1979 also increase transfer costs.Agricultural Finance,

    Making training more cognitively effective: making videos interactive

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    The cost of health and safety (H&S) failures to the UK industry is currently estimated at up to £6.5 billion per annum, with the construction sector suffering unacceptably high levels of work-related incidents. Better H&S education across all skill levels in the industry is seen as an integral part of any solution. Traditional lecture-based courses often fail to recreate the dynamic realities of managing H&S on site and therefore do not sufficiently create deeper cognitive learning (which results in remembering and using what was learned). The use of videos is a move forward, but passively observing a video is not cognitively engaging and challenging, and therefore learning is not as effective as it can be. This paper describes the development of an interactive video in which learners take an active role. While observing the video, they are required to engage, participate, respond and be actively involved. The potential for this approach to be used in conjunction with more traditional approaches to H&S was explored using a group of 2nd-year undergraduate civil engineering students. The formative results suggested that the learning experience could be enhanced using interactive videos. Nevertheless, most of the learners believed that a blended approach would be most effective

    A Web of Connections: The Role of Social Capital and Trust in the Formation of Virtual Organizations

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    Many community based agencies engage in collaboration in order to solve community problems no one organization can accomplish on its own. One such form of collaboration is the virtual organization. A virtual organization is an organization that relies on multi-party, co-operative agreements between structural, temporal, and sometimes geographic boundaries. Looking narrowly at virtual organizations on the community level is one approach which allows for better understanding of why and how community based collaboration takes place. The objective of this research is to examine the extent to which virtual organizations are utilized by community agencies while simultaneously understanding the role both social capital and trust play in the formation of these organizations. By surveying human service agencies in Bloomington-Normal, Illinois, both qualitative and quantitative data were collected on virtual organizations that exist in this community. Both social capital and trust appear to be two of the driving forces in the formation of virtual organizations across social service agencies. This research seeks to better understand virtual organizations as well as the associated successes and failures
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