9,272 research outputs found

    The Influence of Rebate Programs on the Demand for Water Heaters: The Case of New South Wales

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    In the past decade the Australian Federal government and state governments have established a wide range of programs to cut greenhouse gas emissions from all sectors. This paper examines the role of hot water system rebate programs in shifting the existing stock of electric water heaters toward more climate friendly versions using two unique data sets from New South Wales homeowners. The first data set is based on a survey of households who recently purchased a water heater and exploits a natural experiment created by the rebate program to quantify its effects. The other data set is based on a set of stated preference questions asked of households who own an older water heater and will in the reasonably near future face a replacement decision. We find that recent rebate programs significantly increased the share of solar/heat pump systems. For households without access to natural gas, this increased share comes directly from inefficient electric water heaters. For households with access to natural gas, older existing electric water heaters would likely have been replaced with gas water heaters in the absence of the rebate programs. The rebate program appears to be much less effective when water heaters are replaced on an emergency basis. Data from discrete choice experiments was analysed using several flexible choice models. A newly proposed model that combines a latent class approach with a random coefficients approach clearly dominates the other models in terms of statistical fit. Predictions based on this model estimate are reasonably consistent with actual purchase data. Results from it point to considerable heterogeneity with respect to household preferences toward different types of water heaters and with respect to the discount rates they hold.Climate change mitigation, Energy conservation programs, Natural experiments, Discrete choice experiments, Environmental Economics and Policy, Resource /Energy Economics and Policy,

    Investigation of semiconductor clad optical waveguides

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    A variety of techniques have been proposed for fabricating integrated optical devices using semiconductors, lithium niobate, and glasses as waveguides and substrates. The use of glass waveguides and their interaction with thin semiconductor cladding layers was studied. Though the interactions of these multilayer waveguide structures have been analyzed here using glass, they may be applicable to other types of materials as well. The primary reason for using glass is that it provides a simple, inexpensive way to construct waveguides and devices

    Static internal performance of ventral and rear nozzle concepts for short-takeoff and vertical-landing aircraft

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    The internal performance of two exhaust system concepts applicable to single-engine short-take-off and vertical-landing tactical fighter configurations was investigated. These concepts involved blocking (or partially blocking) tailpipe flow to the rear (cruise) nozzle and diverting it through an opening to a ventral nozzle exit for vertical thrust. A set of variable angle vanes at the ventral nozzle exit were used to vary ventral nozzle thrust angle between 45 and 110 deg relative to the positive axial force direction. In the vertical flight mode the rear nozzle (or tailpipe flow to it) was completely blocked. In the transition flight mode flow in the tailpipe was split between the rear and ventral nozzles and the flow was vectored at both exits for aircraft control purposes through this flight regime. In the cruise flight mode the ventral nozzle was sealed and all flow exited through the rear nozzle

    Upper Surface Nacelle Influence on SCAR Aerodynamic Characteristics at Transonic Speeds

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    The arrow-wing transport configuration with detached engines located over the wing to produce upper surface exhaust flow effects was tested at angles of attack from -4 deg to 8 deg and jet total-pressure ratios from 1 (Jet off) to approximately 10. Wing tip leading edge flap deflections of -10 deg to 10 deg were tested with the wing-body configuration only (no nacelles). Tests were made with various nacelle chordwise, spanwise, and vertical height locations over the Mach number, angle of attack, and jet total-pressure ratio ranges. Deflecting the wing tip leading edge flap from 0 deg to -10 deg increased maximum lift to drag ratio by 1.0 at subsonic speeds. Installation of upper surface nacelles (no wing/nacelle pylons) increased the wing-body pitching moment at all Mach numbers and decreased the drag of the wing-body configuration at subsonic Mach numbers. Jet exhaust interference effects were negligible

    Effect of tail size reductions on longitudinal aerodynamic characteristics of a three surface F-15 model with nonaxisymmetric nozzles

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    An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the effects of horizontal and vertical tail size reductions on the longitudinal aerodynamic characteristics of a modified F-15 model with canards and 2-D convergent-divergent nozzles. Quantifying the drag decrease at low angles of attack produced by tail size reductions was the primary focus. The model was tested at Mach numbers of 0.40, 0.90, and 1.20 over an angle of attack of -2 degree to 10 degree. The nozzle exhaust flow was simulated using high pressure air at nozzle pressure ratios varying from 1.0 (jet off) to 7.5. Data were obtained on the baseline configuration with and without tails as well as with reduced horizontal and/or vertical tail sizes that were 75, 50, and 25 percent of the baseline tail areas
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