Stellar Diffuse X-ray Scattering

Directory
Dept. Office
Tech Office
Class Schedule
Planetarium
My BYU

News and Events

APOD: When Black Holes Collide
What happens when two black holes collide? This extreme scenario occurs in the centers of many merging galaxies and multiple star systems. The featured video shows a computer animation of the final stages of such a merger, while highlighting the gravitational lensing effects that would appear on a background starfield. The black regions indicate the event horizons of the dynamic duo, while a surrounding ring of shifting background stars indicates the position of their combined Einstein ring. All background stars not only have images visible outside of this Einstein ring, but also have one or more companion images visible on the inside. Eventually the two black holes coalesce. The end stages of such a merger is now known to produce a strong blast of gravitational radiation, providing a new way to see our universe. This Week is: Black Hole Week at NASA
Weather at the Eyring Science Center
Check current conditions and historical weather data at the ESC.
New Mill Becomes Part of the P&A Family
New self-enclosed mill to enhance machining capabilities
Catching up on Five Year
Thanking our retireed colleagues and welcoming new ones
Scott Sommerfeldt, ASA Vice President
Professor Receives Early Career Award
Physics professor Ben Frandsen recently received an Early Career Award from the United States Department of Energy

Selected Publications

Case study: Noise reduction of a vacuum-assisted toilet
BYU Authors: Michael T. Rose, B. Dagan Pielstick, Zach T. Jones, Scott D. Sommerfeldt, Kent L. Gee, and Scott Thomson, published in Noise Control Eng. J.

Flushing a vacuum-assisted toilet generates noise levels that can be disturbing both to users and those nearby. Peak radiated noise levels correlate with the time when the valve opens and closes, while the noise levels when the valve is com- pletely open are also relatively high. Significant noise ranges between 300 Hz and 3000 Hz. It was hypothesized that increasing the in-tube distance between the flush valve and the bowl in addition to increasing the bend radius of the tube would reduce radiated noise levels. These modifications resulted in a reduction of about 14 dB in the radiated noise during the valve opening and closing in ad- dition to a reduction of about 5 dB while the valve is completely opened. Inter- mediate results of varying the tube length and bend radius are presented to show their effects on the radiated sound levels. Two tube inserts were designed to fit (1) underneath and (2) behind the toilet in a compact manner. They were tested to show that they maintain noise control performance without modifying any other part of the toilet.

Spherical harmonic expansions of high-resolution musical instrument directivities
BYU Authors: Samuel David Bellows and Timothy Ward Leishman, published in Proc. Meet. Acoust.

Well-quantified directivity patterns of sound sources provide greater insights into their acoustical properties and the potential to simulate the propagation of their sounds in various settings. Moreover, clear descriptions of detailed spherically sampled directivities of highly complex and dynamic sound sources such as musical instruments have broad applications. Because spherical harmonics are a suitable basis set for representing functions on the sphere, this work reviews and compares methods for computing spherical harmonic expansion coefficients. It further presents distinct quadrature methods applicable to the five-degree polar and azimuthal sampling distribution commonly used in directivity measurements, and analysis regarding convergence and accuracy of the expansions. Finally, it presents selected results of spherical harmonic expansions of musical instruments.

Comparative analysis of noise from three Falcon 9 launches
BYU Authors: Logan T. Mathews, Kent L. Gee, Grant W. Hart, Reese D. Rasband, Daniel J. Novakovich, Francisco I. Irarrazabal, and Aaron B. Vaughn, published in J. Acoust. Soc. Korea

 This study investigates the far-field noise from three Falcon 9 vehicle launches from Vandenberg Air Force Base, CA, USA, as measured from the same location within the nearby community of Lompoc. The overall sound pressure levels for the three launches are shown to be similar, but some differences in the early launch period are thought to be weather-related. The peak directivity angle in overall level is approximately 65 deg, which is consistent with horizontally-fired, static rocket data. For the third launch, waveforms and spectra are analyzed for different events during the launch sequence. The measured spectral bandwidth decreases with time, but spectral levels remain above the ambient noise throughout the main-engine firing. Additionally, late-launch phenomena observed in the data appear to be correlated with main-engine cutoff and second-stage engine start.