610 research outputs found
PCSYS: The optimal design integration system picture drawing system with hidden line algorithm capability for aerospace vehicle configurations
A vehicle geometric definition based upon quadrilateral surface elements to produce realistic pictures of an aerospace vehicle. The PCSYS programs can be used to visually check geometric data input, monitor geometric perturbations, and to visualize the complex spatial inter-relationships between the internal and external vehicle components. PCSYS has two major component programs. The between program, IMAGE, draws a complex aerospace vehicle pictorial representation based on either an approximate but rapid hidden line algorithm or without any hidden line algorithm. The second program, HIDDEN, draws a vehicle representation using an accurate but time consuming hidden line algorithm
Comparative Energy and Cost Analysis between Conventional HVAC Systems and Geothermal Heat Pump Systems
To sustain the United States current affluence and strength, the U.S. Government has encouraged energy conservation through executive orders, federal and local laws, and consumer education. A substantial reduction in U.S. energy consumption could be realized by using geothermal heat pumps to heat and cool buildings throughout the U.S., though initial installation cost are a deterrent. This thesis uses Monte Carlo simulation to predict energy consumption, life cycle cost and payback period for the vertical closed-loop ground source heat pump (GSHP) relative to conventional heating ventilation and air conditioning (HVAC) systems: air-source heat pumps (ASHP), air-cooled air conditioning with either natural gas, fuel oil, or liquid petroleum gas furnaces, or with electrical resistance heating. The Monte Carlo simulation is performed for a standard commercial office building within each of the 48 continental states. Regardless of the conventional HVAC system chosen, the simulation shows that for each state the GSHP has the highest probability of using less energy and having a lower operating and life cycle cost than conventional HVAC systems; however, initial installation cost are typically twice that of conventional HVAC systems and payback periods vary greatly depending on site conditions. The average 50th percentile GSHP payback period in the U.S. was 7.5 years compared against the ASHP and 9.2 years compared against the air-cooled air conditioning with natural gas furnace. However, these values vary greatly depending on location and are most sensitivity to ground thermal conductivity, utility prices, and HVAC efficiency ratings. Under the right conditions, payback for geothermal heat pumps can be much shorter and the model developed in this research can help predict energy savings and payback periods for a given site
Extracting Radial Velocities of A- and B-type Stars from Echelle Spectrograph Calibration Spectra
We present a technique to extract radial velocity measurements from echelle
spectrograph observations of rapidly rotating stars ( km
s). This type of measurement is difficult because the line widths of
such stars are often comparable to the width of a single echelle order. To
compensate for the scarcity of lines and Doppler information content, we have
developed a process that forward-models the observations, fitting the radial
velocity shift of the star for all echelle orders simultaneously with the
echelle blaze function. We use our technique to extract radial velocity
measurements from a sample of rapidly rotating A- and B-type stars used as
calibrator stars observed by the California Planet Survey observations. We
measure absolute radial velocities with a precision ranging from 0.5-2.0 km
s per epoch for more than 100 A- and B-type stars. In our sample of 10
well-sampled stars with radial velocity scatter in excess of their measurement
uncertainties, three of these are single-lined binaries with long observational
baselines. From this subsample, we present detections of two previously unknown
spectroscopic binaries and one known astrometric system. Our technique will be
useful in measuring or placing upper limits on the masses of sub-stellar
companions discovered by wide-field transit surveys, and conducting future
spectroscopic binarity surveys and Galactic space-motion studies of massive
and/or young, rapidly-rotating stars.Comment: Accepted to ApJ
Kepler-445, Kepler-446 And The Occurrence Of Compact Multiples Orbiting Mid-M Dwarf Stars
We confirm and characterize the exoplanetary systems Kepler-445 and Kepler-446: two mid-M dwarf stars, each with multiple, small, short-period transiting planets. Kepler-445 is a metal-rich ([ Fe/H] = + 0.25 0.10) M4 dwarf with three transiting planets, and Kepler-446 is a metal-poor ([ Fe/H] = -0.30 0.10) M4 dwarf also with three transiting planets. Kepler-445c is similar toGJ 1214b: both in planetary radius and the properties of the host star. The Kepler-446 system is similar to the Kepler-42 system: both are metal-poor with large galactic space velocities and three short-period, likely rocky transiting planets that were initially assigned erroneously large planet-to-star radius ratios. We independently determined stellar parameters from spectroscopy and searched for and fitted the transit light curves for the planets, imposing a strict prior on stellar density in order to remove correlations between the fitted impact parameter and planet-to-star radius ratio for short-duration transits. Combining Kepler-445, Kepler-446, and Kepler-42, and isolating all mid-M dwarf stars observed by Kepler with the precision necessary to detect similar systems, we calculate that 21+ 7 -5 % of mid-M dwarf stars host compact multiples ( multiple planets with periods of less than 10 days) for a wide range of metallicities. We suggest that the inferred planet masses for these systems support highly efficient accretion of protoplanetary disk metals by mid-M dwarf protoplanets.NSF DGE1144152, AST-1005313NASA NAS5-26555NASA Office of Space Science NNX13AC07GAstronom
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