3,559 research outputs found

    An introduction to the Princeton sailwing windmill

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    Specifically discussed is the sailwing windmill. The aerodynamic characteristics of the sailwing itself are presented in condensed form and its natural application to the wind machine is discussed. Past and present sailwing windmill configurations are shown and their relative merits are compared. A section on a future promising configuration is presented and its compatibility to advanced technology electrical machinery is briefly discussed. Also included is a short bibliography

    Socioeconomic impacts of the second stage of the Southern Nevada Water Project and its alternatives

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    This study evaluates the socioeconomic impacts of the Second Stage of the Southern Nevada Water Project of the United States Bureau of Reclamation, comparing that project with the alternatives of importing water from Nevada areas somewhat removed from the Las Vegas Valley and of leaving the water supply of the Valley basically as it is, the no project alternative. The study follows, with adaptations and extensions, the general methodology for socioeconomic impact studies as developed and still being evolved in successive socioeconomic analyses of Bureau of Reclamation water projects. The methodology recognizes that the complexity of modern society and water impacts requires that water project analyses extend beyond the dollar cost benefit approach, which usually is the most reliable guide to decision, to considerations of qualitative effects, which often are of dominant importance despite their difficulty of measurement. Such analysis requires the tools of economics, sociology, engineering, law, political science and other related fields. It also dictates a step-by-step process which insures comprehensive consideration of the direct and indirect impacts of water projects on all of the social sectors which command public interest and concern. Such a step-by-step process constitutes the six chapters of this report

    A Near-Infrared and Thermal Imager for Mapping Titan's Surface Features

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    Approximately 10% of the solar insolation reaches the surface of Titan through atmospheric spectral windows. We will discuss a filter based imaging system for a future Titan orbiter that will exploit these windows mapping surface features, cloud regions, polar storms. In the near-infrared (NIR), two filters (1.28 micrometer and 1.6 micrometer), strategically positioned between CH1 absorption bands, and InSb linear array pixels will explore the solar reflected radiation. We propose to map the mid, infrared (MIR) region with two filters: 9.76 micrometer and 5.88-to-6.06 micrometers with MCT linear arrays. The first will map MIR thermal emission variations due to surface albedo differences in the atmospheric window between gas phase CH3D and C2H4 opacity sources. The latter spans the crossover spectral region where observed radiation transitions from being dominated by thermal emission to solar reflected light component. The passively cooled linear arrays will be incorporated into the focal plane of a light-weight thin film stretched membrane 10 cm telescope. A rad-hard ASIC together with an FPGA will be used for detector pixel readout and detector linear array selection depending on if the field-of-view (FOV) is looking at the day- or night-side of Titan. The instantaneous FOV corresponds to 3.1, 15.6, and 31.2 mrad for the 1, 5, and 10 micrometer channels, respectively. For a 1500 km orbit, a 5 micrometer channel pixel represents a spatial resolution of 91 m, with a FOV that spans 23 kilometers, and Titan is mapped in a push-broom manner as determined by the orbital path. The system mass and power requirements are estimated to be 6 kg and 5 W, respectively. The package is proposed for a polar orbiter with a lifetime matching two Saturn seasons

    Update from the Analysis of High Resolution Propane Spectra and the Interpretation of Titan's Infrared Spectra

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    Titan has an extremely thick atmosphere dominated by nitrogen, but includes a range of trace species such as hydrocarbons and nitriles. One such hydrocarbon is propane (C3H8). Propane has 21 active IR bands covering broad regions of the mid-infrared. Therefore, its ubiquitous signature may potentially mask weaker signatures of other undetected species with important roles in Titan's chemistry. Cassini's Composite Infrared Spectrometer (CIRS) observations of Titan's atmosphere hint at the presence of such molecules. Unfortunately, C3H8 line atlases for the vibration bands V(sub 8), V(sub 21), V(sub 20), and V(sub 7) (869, 922, 1054, and 1157 per centimeter, respectively) are not currently available for subtracting the C3H8 signal to reveal, or constrain, the signature of underlying chemical species. Using spectra previously obtained by Jennings, D. E., et al. at the McMath-Pierce FTIR at Kitt Peak, AZ, as the source and automated analysis utilities developed for this application, we are compiling an atlas of spectroscopic parameters for propane that characterize the ro-vibrational transitions in the above bands. In this paper, we will discuss our efforts for inspecting and fitting the aforementioned bands, present updated results for spectroscopic parameters including absolute line intensities and transition frequencies in HITRAN and GEISA formats, and show how these optical constants will be used in searching for other trace chemical species in Titan's atmosphere. Our line atlas for the V(sub 21) band contains a total number of 2971 lines. The band integrated strength calculated for the V(sub 21) band is 1.003 per centimeter per (centimeter-atm)

    A trio of month long flares in the nova-like variable V704 And

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    We present the discovery of an unusual set of flares in the nova-like variable V704 And. Using data from AAVSO, ASAS-SN, and ZTF, of the nova-like variable V704 And, we have discovered a trio of brightening events that occurred during the high state. These events elevate the optical brightness of the source from āˆ¼13.5\sim13.5 magnitude to āˆ¼12.5\sim12.5 magnitude. The events last for roughly a month, and exhibit the unusual shape of a slow rise and faster decay. Just after the third event we obtained data from regular monitoring with Swift, although by this time the flares had ceased and the source returned to its pre-flare level of activity in the high-state. The Swift observations confirm that during the high-state the source is detectable in the X-rays, and provide simultaneous UV and optical fluxes. As the source is already in the high-state prior to the flares, and thus the disc is expected to already be in the high-viscosity state, we conclude that the driver of the variations must be changes in the mass transfer rate from the companion star and we discuss possible mechanisms for such short-timescale mass transfer variations to occur.Comment: 5 pages + appendix. Accepted for publication in A&A Letter

    New magnetic dipole transition of the oxygen molecule: BŹ¹Ā³Ī gā†Xā€ŠĀ³Ī£gā»(0,0)

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    Through the use of isotopically pure gas at a temperature of 77 K, a weak photoabsorption band of Ā¹ā¶Oā‚‚ is found near 1856 ƅ, underlying the stronger Schumannā€“Runge (SR) band BĀ³Ī£āˆ’uā†XĀ³Ī£āˆ’g(8,0). The location, structure, and intensity of this new band are consistent with expectation for the magnetic dipole transitionBā€²ā€ŠĀ³Ī gā†XĀ³Ī£āˆ’g(0,0), where the designation Bā€² is chosen to represent the IIā€ŠĀ³Ī g valence state. This electronic transition contributes to the ā€œexcess absorptionā€ underlying the SR bands [B. R. Lewis, S. T. Gibson, and E. H. Roberts, J. Chem. Phys. 115, 245 (2001)]

    An Atlas of Fishing and Some Related Activities in Ireland's Territorial Sea and Internal Marine Waters with Observations Concerning their Spatial Planning

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    This Atlas was initiated as part of Ireland's preparation for the Water Framework Directive (WFD) which, inter alia, required mapping the distribution of mobile fishing gears in coastal waters (inside 1 n mile outside the base lines). The Atlas subsequently expanded the geographical extent of the review out to 12 n miles. The history, descriptive terminology and extent of subdivisions of the territorial sea are provided. The Atlas is a collection of 1,885 polygons showing the distribution of fishing and fishery related activities, including aquaculture and mariculture within the Republic of Ireland's territorial sea and internal marine waters. The Atlas demonstrates that the greatest range and intensity of fishing and related activities are undertaken in the internal waters of the State. Hook and line fishing emerged as the most widely used metier and a combined array of mobile gears, ranging from pelagic otter trawls to hydraulic dredges, took second place. The total area occupied by fishing and fishing related activities was just under 125,000 km2. The principal metier groupings within 12 n miles were: hook and line occupying 57,000 km2 (45% of the total), mobile gears (towed enclosing nets and dredges) accounting for 27,530 km2 (22%). Passive nets (static tangle and gill nets and the now defunct salmon drift nets) made up 18,000 km2 (14%). Pots targeting crustaceans and molluscs occupied 13,250 km2 (11%). Aquaculture and mariculture occupied 172 km2, some 0.4% of the area within 12 n miles. To supplement the polygons, a table of metier and species combinations in internal and territorial waters opposite each county with a long shoreline is supplied. The table includes fisheries whose existence is known but not their extent. The consequences for benthic community structure of the use of a particular metier, the purpose of the exercise for the WFD, are considered. "Community" refers to fish or invertebrate species assemblages. Applications for the data are discussed in the context of a growing appreciation of the need to plan the use of inshore waters for fishery conservation and to accommodate a wide range of stakeholder interests and to embrace the ecosystem approach to maritime governance. Difficulties inherent in conserving fish species rather than biological communities are illustrated by reference to a case history. Data presented in the document were sourced from the tacit knowledge of stakeholders. Planning jurisdiction in the Republic of Ireland is described with reference to inshore waters. Recent thinking by fishery commentators is reviewed. Finally, current thinking on inshore spatial planning within the EU and particularly among our nearest neighbours is discussed and the possibility of implementing ICZM is briefly considered. This document is presented as Version 1 of a continuing exercise. Governmental departmental arrangements and collected data refer to the period up to 2006. The Atlas should be periodically revised as more information becomes available.Funder: Marine Institut

    Probing the potential landscape inside a two-dimensional electron-gas

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    We report direct observations of the scattering potentials in a two-dimensional electron-gas using electron-beam diffaction-experiments. The diffracting objects are local density-fluctuations caused by the spatial and charge-state distribution of the donors in the GaAs-(Al,Ga)As heterostructures. The scatterers can be manipulated externally by sample illumination, or by cooling the sample down under depleted conditions.Comment: 4 pages, 4 figure

    Spectroscopy of the Potential Profile in a Ballistic Quantum Constriction

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    We present a theory for the nonlinear current-voltage characteristics of a ballistic quantum constriction. Nonlinear features first develop because of above-barrier reflection from the potential profile, created by impurities in the vicinity of the constriction. The nonlinearity appears on a small voltage scale and makes it possible to determine distances between impurities as well as the magnitude of the impurity potentials.Comment: 3 pages, 4 figures (availiable upon request), REVTEX, Applied Physics Report 93-5

    Open Space ā€“ a collaborative process for facilitating Tourism IT partnerships

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    The success of IT projects depends on the success of the partnerships on which they are based. However past research by the author has identified a significant rate of failure in these partnerships, predominantly due to an overly technical mindset, leading to the question: ā€œhow do we ensure that, as technological solutions are implemented within tourism, due consideration is given to human-centred issues?ā€ The tourism partnership literature is explored for additional insights revealing that issues connected with power, participation and normative positions play a major role. The method, Open Space, is investigated for its ability to engage stakeholders in free and open debate. This paper reports on a one-day Open Space event sponsored by two major intermediaries in the UK travel industry who wanted to consult their business partners. Both the running of the event and its results reveal how Open Space has the potential to address some of the weaknesses associated with tourism partnerships
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