Improving the Reliability of a Domestic Refrigerator Compressor Subjected to Repetitive Loading

As a reliability quantitative specification, parametric accelerated life testing was used to assess the reliability of a newly designed compressor of a commercial refrigerator subjected to repetitive stresses. A generalized life-stress failure model and new sample size equation with a new load concept were derived starting with the basic refrigeration cycle. The sample size equation with the acceleration factor also enabled the parametric accelerated life testing to quickly evaluate the expected lifetime. The design of this testing should help an engineer uncover the design parameters affecting reliability during the design process of the compressor system. Consequently, it should help companies improve product reliability and avoid recalls due to the product failures in the field. A newly designed compressor in a commercial refrigerator was used as a test case

Comparing and calibrating black hole mass estimators for distant active galactic nuclei

Black hole mass is a fundamental property of active galactic nuclei (AGNs). In the distant universe, black hole mass is commonly estimated using the MgII, Hbeta, or Halpha emission line widths and the optical/UV continuum or line luminosities, as proxies for the characteristic velocity and size of the broad-line region. Although they all have a common calibration in the local universe, a number of different recipes are currently used in the literature. It is important to verify the relative accuracy and consistency of the recipes, as systematic changes could mimic evolutionary trends when comparing various samples. At z=0.36, all three lines can be observed at optical wavelengths, providing a unique opportunity to compare different empirical recipes. We use spectra from the Keck Telescope and the Sloan Digital Sky Survey to compare black hole mass estimators for a sample of nineteen AGNs at this redshift. We compare popular recipes available from the literature, finding that mass estimates can differ up to 0.38+-0.05 dex in the mean (or 0.13+-0.05 dex, if the same virial coefficient is adopted). Finally, we provide a set of 30 internally self consistent recipes for determining black hole mass from a variety of observables. The intrinsic scatter between cross-calibrated recipes is in the range 0.1-0.3 dex. This should be considered as a lower limit to the uncertainty of the black hole mass estimators.Comment: ApJ in press, 11 pages, 10 figure

Predicting Auction Price of Vehicle License Plate with Deep Residual Learning

Due to superstition, license plates with desirable combinations of characters are highly sought after in China, fetching prices that can reach into the millions in government-held auctions. Despite the high stakes involved, there has been essentially no attempt to provide price estimates for license plates. We present an end-to-end neural network model that simultaneously predict the auction price, gives the distribution of prices and produces latent feature vectors. While both types of neural network architectures we consider outperform simpler machine learning methods, convolutional networks outperform recurrent networks for comparable training time or model complexity. The resulting model powers our online price estimator and search engine

Stronger Constraints on the Evolution of the MBH−σ∗M_{\rm{BH}}-\sigma_* Relation up to z∼0.6z\sim0.6

We revisit the possibility of redshift evolution in the $M_{\rm{BH}}-\sigma_*$ relation with a sample of 22 Seyfert 1 galaxies with black holes (BHs) in the mass range $10^{6.3}-10^{8.3}~M_\odot$ and redshift range $0.03<z<0.57$ with spectra obtained from spatially resolved Keck/Low-Resolution Imaging Spectrometer observations. Stellar velocity dispersions were measured directly from the Mg Ib region, taking into consideration the effect of Fe II contamination, active galactic nucleus (AGN) dilution, and host-galaxy morphology on our measurements. BH masses are estimated using the H$\beta$ line width, and the luminosity at 5100 \overset{\lower.5em\circ}{\mathrm{A}} is estimated from surface brightness decomposition of the AGN from the host galaxy using high-resolution imaging from the Hubble Space Telescope. Additionally, we investigate the use of the [O III]$\lambda5007$ emission line width as a surrogate for stellar velocity dispersion, finding better correlation once corrected for Fe II contamination and any possible blueshifted wing components. Our selection criteria allowed us to probe lower-luminosity AGNs and lower-mass BHs in the non-local universe than those measured in previous single-epoch studies. We find that any offset in the $M_{\rm{BH}}-\sigma_*$ relation up to $z\sim0.6$ is consistent with the scatter of local BH masses, and address the sources of biases and uncertainties that contribute to this scatter.Comment: Accepted 14 May 2019 for publication in ApJ. 42 pages, 12 figures, 4 tables. Corrected for typographical error

Data report of oblique reflection-refraction radio-sonobuoy profiles on the African Atlantic continental margin : (R/V Atlantis II cruises 67 and 75)

Two hundred sixty-four unreversed oblique reflection-refraction profiles using expendable radio-sonobuoys were obtained during two geophysical cruises to the Atlantic continental margin of Africa. This data report gives the profile locations, a summary of the data collection and analysis, and 780 interval reflection and refraction velocities and thicknesses that were determined.Prepared for the International Decade of Ocean Exploration, National Science Foundation Grant GX-28193 for the Eastern Atlantic Continental Margin program