Behavior of nozzles and acoustic liners in three-dimensional acoustic fields Quarterly report, 1 Dec. 1969 - 28 Feb. 1970

Frequency responses of supercritical nozzles and acoustic liner

Behavior of nozzles and acoustic liners in three-dimensional acoustic fields Quarterly report, 1 Sep. - 31 Dec. 1969

Theoretical studies and test facility installation for investigating behavior of rocket nozzles and acoustic liners in three dimensional acoustic field

Behavior of nozzles and acoustic liners in three-dimensional acoustic fields Quarterly report, 1 Jun. - 31 Aug. 1970

Updating computer program for determining nozzle admittances to eliminate double-root solution and to fit resultant admittance data curves by statistical mean

Behavior of nozzles and acoustic liners in three-dimensional acoustic fields Quarterly report, 1 Sep. - 31 Nov. 1970

Behavior of nozzles and acoustic liners in three dimensional acoustic field

Behavior of nozzles and acoustic liners in three-dimensional acoustic fields Quarterly report, 1 Mar. - 31 May 1969

Behavior of convergent-divergent nozzles and acoustic liners in three dimensional acoustic field

Measuring the Values for Time

Most economic models for time allocation ignore constraints on what people can actually do with their time. Economists recently have emphasized the importance of considering prior consumption commitments that constrain behavior. This research develops a new model for time valuation that uses time commitments to distinguish consumers' choice margins and the different values of time these imply. The model is estimated using a new survey that elicits revealed and stated preference data on household time allocation. The empirical results support the framework and find an increasing marginal opportunity cost of time as longer time blocks are used.

Behavior of nozzles and acoustic liners in three dimensional acoustic fields

Theoretical values of the admittances of various nozzles were computed and compared with the corresponding experimental values. The existing data reduction scheme was corrected and all available experimental data has been rechecked and corrected whenever necessary; the updated experimental admittance values are presented. An analysis associated with the frequency sensitivity of experimental admittance values was initiated and the analog-to-digital Data Reduction Program which has become operational is discussed. Fourteen nozzle tests were conducted during this report period

Should we believe the results of ultraviolet–millimetre galaxy spectral energy distribution modelling?

Galaxy spectral energy distribution (SED) modelling is a powerful tool, but constraining how well it is able to infer the true values for galaxy properties (e.g. the star formation rate) is difficult because independent determinations are often not available. However, galaxy simulations can provide a means of testing SED modelling techniques. Here, we present a numerical experiment in which we apply the SED modelling code MAGPHYS to ultraviolet–millimetre synthetic photometry generated from hydrodynamical simulations of an isolated disc galaxy and a major galaxy merger by performing three-dimensional dust radiative transfer. We compare the properties inferred from the SED modelling with the true values and find that MAGPHYS recovers most physical parameters of the simulated galaxies well. In particular, it recovers consistent parameters irrespective of the viewing angle, with smoothly varying results for neighbouring time steps of the simulation, even though each viewing angle and time step is modelled independently. The notable exception to this rule occurs when we use a Small Magellanic Cloud-type intrinsic dust extinction curve in the radiative transfer calculations. In this case, the two-component dust model used by MAGPHYS is unable to effectively correct for the attenuation of the simulated galaxies, which leads to potentially significant errors (although we obtain only marginally acceptable fits in this case). Overall, our results give confidence in the ability of SED modelling to infer physical properties of galaxies, albeit with some caveats

Panchromatic SED modelling of spatially-resolved galaxies

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2018 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We test the efficacy of the energy-balance spectral energy distribution (SED) fitting code MAGPHYS for recovering the spatially resolved properties of a simulated isolated disc galaxy, for which it was not designed. We perform 226 950 MAGPHYS SED fits to regions between 0.2 and 25 kpc in size across the galaxy's disc, viewed from three different sight-lines, to probe how well MAGPHYS can recover key galaxy properties based on 21 bands of UV-far-infrared model photometry. MAGPHYS yields statistically acceptable fits to >99 per cent of the pixels within the r-band effective radius and between 59 and 77 percent of pixels within 20 kpc of the nucleus. MAGPHYS is able to recover the distribution of stellar mass, star formation rate (SFR), specific SFR, dust luminosity, dust mass, and V-band attenuation reasonably well, especially when the pixel size is ≳1 kpc, whereas non-standard outputs (stellar metallicity and mass-weighted age) are recovered less well. Accurate recovery is more challenging in the smallest sub-regions of the disc (pixel scale ≲1 kpc), where the energy balance criterion becomes increasingly incorrect. Estimating integrated galaxy properties by summing the recovered pixel values, the true integrated values of all parameters considered except metallicity and age are well recovered at all spatial resolutions, ranging from 0.2 kpc to integrating across the disc, albeit with some evidence for resolution-dependent biases. These results must be considered when attempting to analyse the structure of real galaxies with actual observational data, for which the 'ground truth' is unknown.Peer reviewe