397 research outputs found

    How integrative modelling can break down disciplinary silos

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    This paper has been published in a peer-reviewed journal as: Kragt, M.E., Robson, B.J. & Macleod, C.J.A. (2013) Modellers’ roles in structuring integrative research projects. Environmental Modelling & Software, 39(1): 322-330. DOI: 10.1016/j.envsoft.2012.06.015Environmental modelling, Interdisciplinary research, Transdisciplinarity, Integration, Research Methods/ Statistical Methods, Q57, Y80, Z19,

    Antenna Arrangement Verification for Low Sidelobe Levels

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    Space-to-earth Wireless Power Transfer (WPT) in large scale will not be allowed unless the side lobe levels (SLL) can be reduced many orders of magnitude lower than the current technology allows. In particular, high SLL could potentially interfere with aircraft communications around the beam, while the area inside the beam would necessarily be a no-fly zone, similar as over nuclear power plants. To overcome this, the transmitting antenna must be cleverly designed and controlled. In this work, independent validation of the layout, spacing, and envelope arrangement of a design first proposed in 2016 is performed and presented. This design involves a hexagonal design with a triangular antenna element arrangement and a spacing of 0.8 wavelengths using the Dolph-Chebychev beam profile. While this has been shown to produce -240 dB SLL in the AWR Design Environment already, it will now be analyzed using the MATLAB Phased Array System Toolbox. The design will also be investigated on a smaller scale, with the potential for use in other applications, including the powering of low orbit weather balloons or unmanned aerial vehicles (UAVs). The possibility of very low SLL would be transformational in these and other WPT applications, including space solar power, and could greatly benefit humanity and the environment

    Gender Roles and Behavior in Social Dilemmas: Are there Sex Differences in Cooperation and in its Justification?

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    10 pagesData from two experimental social dilemmas-a set of 66 nine-person dilemmas and a set of 64 seven-person dilemmas-were used to examine sex differences in cooperation. Women were only slightly more likely than men to cooperate with others, and variables related to the experimental setting were much more important influences on behavior than sex. Whether or not the women cooperated, they were more likely than men to justify their behavior as being altruistic and principled, to believe that they were more oriented toward harmonious group relations, and to be less nervous and upset at the end of the experiment. It is suggested that those who speculate on sex differences in cooperation may have overstated these differences and that the relationship between self-schema and behavior may vary depending on the extent to which the attributes studied relate to gender identity

    Spacetenna Flatness and Error Correction

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    Wireless Power Transfer (WPT) from space-to-earth at a large scale will not be possible until the Side Lobe Levels (SLL) are reduced many orders of magnitude from the current technology available today. To accomplish this, careful design of the transmitting antenna (spacetenna) is imperative. Any module failures or errors in connectivity, including askew angles between adjacent sandwich modules, reduce the effectiveness of the antenna design and thereby increase SLL. This work examines two interrelated issues; error detection and repair, and spacetenna flatness correction. Multiple different designs of sandwich module mechanical connections, wiring, and control are examined. The results of the analysis and best options are presented in order to facilitate for ultra-low SLL for use in Space Solar Power for the benefit of humanity and the environment

    "Ethnic disparities in the prevalence of Molar-Incisor-Hypomineralisation (MIH) and caries among 6-12-year-old children in Catalonia, Spain"

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    AIM: To study the prevalence of MIH and caries in 6- and 12-year-old schoolchildren and their association with ethnic disparities and other relevant factors. BACKGROUND: In recent years, there has been uneven improvement in school children's oral health, highlighting inequalities in access to dental care and health outcomes, particularly among ethnic minorities. The most prevalent oral disease in childhood, caries, is preventable, as its risk factors are well known. However, MIH, a common condition affecting the enamel of permanent incisors and/or molars, has no established aetiology or preventive measures. METHODS: A cross-sectional study among schoolchildren was conducted in 725 children from Masnou (Barcelona, 2013) and in 577 children from Sant Andreu de Llavaneres (Barcelona, 2018-2020). Data collection was carried out by means of clinical examination and a selfreferenced questionnaire. Oral health outcomes included: presence of dental caries, presence of MIH, hypomineralised second primary molars (HSPM). All variables were analysed according to ethnic disparities and other variables such as socioeconomics, diet, hygiene habits, plaque and access to dental services. We performed multivariate Poisson regression models with robust variance to examine ethnic disparities in MIH and caries. CONCLUSION: This cross-sectional study based in Catalonia, Spain showed that there are ethnic disparities in caries as observed with other child's diseases; however, they do not seem to follow the same pattern for MIH. More studies are needed (i) to explore how MIH behaves among populations in terms of inequality; (ii) to study the aetiological factors of MIH; and (iii) to identify potential factors associated with MIH and caries that have not been studied and that may contribute to the observed ethnic disparities.</p

    Performance Estimates for a Fuel-Free Stationary Platform in the Stratosphere

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    High-altitude pseudo-satellites (HAPS) may be kept aloft indefinitely with station-keeping provided by plasma air thrusters (PAT) using wireless power transfer (WPT) from a terrestrial phased array antenna (PAA). One example is the patented “Sitallite” superpressure balloon with a rectifying antenna (rectenna) covering its underside, with thrusters around the periphery. Such a stationary platform can provide continuous observation and communications capabilities covering vast areas for a fraction of the cost required for an orbiting satellite. This work builds upon the design and safety study published elsewhere to provide performance estimates for a long-duration, persistent HAPS powered by electronically-steerable microwave beams. Newly-derived efficiency equations are used to provide accurate estimates of free-space WPT transfer efficiency based on the dimensions of the ground-based PAA and the rectenna. Calculations of air drag for a spheroidal bouyant shape are used to derive PAT power requirements, and these, together with power conversion circuitry, are used to size the overall system. Accurate estimates of cost are derived. These performance estimates can be used to help make economic and logistic decisions, as a fuel-free HAPS with PAT and powered by WPT can be lofted in less time, and with lower risk, than an orbital satellite of comparable capabilities

    Wireless Power Transfer to Sitallite Stratospheric Platform

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    The following topics are dealt with: artificial satellites; ionospheric electromagnetic wave propagation; Global Positioning System; satellite navigation; ionospheric techniques; radiowave propagation; space vehicle electronics; ionospheric disturbances; total electron content (atmosphere); and magnetic storms
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