9,324 research outputs found
The separation test in vacuum of the Ariane 4 payload fairing
The separation tests performed during the qualification test program of the Ariane 4 Payload Fairing are described. This is the first fairing structure to be developed using carbon fiber technology. Two separation tests were performed under vacuum conditions. The primary objectives of these tests were to verify compliance with the vehicle imposed requirements and to establish the behavioral characteristics of the fairing structure itself
ECONOMIC MODELING OF FARM PRODUCTION AND CONSERVATION DECISIONS IN RESPONSE TO ALTERNATIVE RESOURCE AND ENVIRONMENTAL POLICIES
Environmental Economics and Policy, Farm Management,
Simple Phase Bias for Superconducting Circuits
A phase-bias tool, based on a trapped fluxoid in a ring, is proposed and
demonstrated. It can provide arbitrary phase values and is simple to fabricate.
The phase bias has been realized in two superconducting quantum interference
devices, where the critical current versus magnetic flux is shown to be shifted
by a \pi/2 and \pi.Comment: 5 pages, including 4 figures. Submitted to AP
Non-user benefits emanating from enhanced water flow to the Yala Protected Area Complex
Water is a multiple use resource. Increasing scarcity and competition from various sectors is an important dimension to be considered in its management. Understanding the value of water to different water uses is, therefore, necessary to assist decision-making in water allocation among sectors. Although water used in agriculture can be valued using production function approaches, such direct valuation methods are not available for the environmental uses of water. This paper uses non-market valuation methods to estimate the economic value of a committed flow through a unique ecosystem, the Yala Protected Area Complex (YPC). The Yala Protected Area Complex is an important wildlife refuge situated in south-eastern Sri Lanka. Its large land extent, undisturbed nature, and abundance and diversity of fauna contribute to its uniqueness. The fact that the YPC is also the most visited national park in Sri Lanka is partially a result of this uniqueness. However, maintenance of the park’s ecosystem depends on the flow of the Menik Ganga. This flow is regulated by the Veheragala Reservoir Project, and there is now discussion of reducing flow into the park by about half of the current level. The proposed plan ensures dry season flow into the YPC and, therefore, has been deemed acceptable. However, there is a possibility that farmers will demand further water releases during the dry season which could in turn endanger the planned downstream water releases. So there is a potential trade-off between environmental and irrigation uses of water. A willingness to pay (WTP) survey was conducted in ten districts in Sri Lanka during the fourth quarter of 2008 to estimate the WTP of the general population of the country towards maintaining this important environmental resource. In the hypothetical market presented, participants were told of the need for financial contributions from the general public to ensure the release of a minimum downstream flow commitment of 50 MCM. Participants were also informed of how this flow would enhance the ecosystem of the YPC. A single bound dichotomous choice contingent valuation approach was used as the elicitation format. Nonobligatory voluntary contributions were solicited towards a trust fund that could be used to ensure release of the required quantity of water downstream during dry months. According to the results of a binary logistic regression, income, age, and religious attachments are important factors affecting the decision to contribute to environmental flow maintenance to the YPC. Sixty-five percent of respondents were willing to pay something to ensure the maintenance of an adequate environmental flow in the YPC. The estimated mean WTP for water releases to enhance the YPC is Sri Lankan Rupees (SLR) 435 per year. Over the requested payment horizon of 10 years, the present value of aggregate WTP from the Sri Lankan population to enhance the ecosystem of the YPC is SLR 12 billion. This quantity greatly surpasses the present value of net benefits from rice farming estimated at SLR 0.64 billion, which would be generated if the same quantity of water was used for irrigation for 10 years (assuming current prices and input intensities). Thus, there is a clear opportunity for national welfare gain by ensuring adequate flow in YPC.Length: pp.37-47Water useMultiple useWildlifeHabitatsEcosystemsIrrigation waterWater allocation
The species of Sphaerolobium (Fabaceae) in Tasmania
Two species of the globe pea Sphaerolobium occur in Tasmania: Sphaerolobium minus Labill. and S. vimineum Sm. Information on their morphology, distribution and conservation status in the state is discussed based primarily upon Tasmanian Herbarium (HO) records. The leaf morphology of both species is described
Hawking radiation from "phase horizons" in laser filaments?
Belgiorno et al have reported on experiments aiming at the detection of (the
analogue of) Hawking radiation using laser filaments [F. Belgiorno et al, Phys.
Rev. Lett. 105, 203901 (2010)]. They sent intense focused Bessel pulses into a
non-linear dielectric medium in order to change its refractive index via the
Kerr effect and saw creation of photons orthogonal to the direction of travel
of the pluses. Since the refractive index change in the pulse generated a
"phase horizon" (where the phase velocity of these photons equals the pulse
speed), they concluded that they observed the analogue of Hawking radiation. We
study this scenario in a model with a phase horizon and a phase velocity very
similar to that of their experiment and find that the effective metric does not
quite correspond to a black hole. The photons created in this model are not due
to the analogue of black hole evaporation but have more similarities to
cosmological particle creation. Nevertheless, even this effect cannot explain
the observations -- unless the pulse has significant small scale structure in
both the longitudinal and transverse dimensions.Comment: 13 pages RevTeX, 2 figure
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