Engineering Physics Commons^™

Trumpet Directivity From A Rotating Semicircular Array, Samuel D. Bellows, Joseph E. Avila, Timothy W. Leishman

Directivity

The directivity function of a played musical instrument describes the angular dependence of its acoustic radiation and diffraction about the instrument, musician, and musician’s chair. Directivity influences sound in rehearsal, performance, and recording environments and signals in audio systems. Because high-resolution, spherically comprehensive measurements of played musical instruments have been unavailable in the past, the authors have undertaken research to produce and share such data for studies of musical instruments, simulations of acoustical environments, optimizations of microphone placements, and other applications. The authors acquired the data from repeated chromatic scales produced by a trumpet played at mezzo-forte in an anechoic …

Gamelan Gong Directivity Dataset, Samuel D. Bellows, Dallin T. Harwood, Kent L. Gee, Micah R. Shepherd

Directivity

No abstract provided.

Comparing Radiation Shielding Potential Of Liquid Propellants To Water For Application In Space, John Czaplewski

Master's Theses

The radiation environment in space is a threat that engineers and astronauts need to mitigate as exploration into the solar system expands. Passive shielding involves placing as much material between critical components and the radiation environment as possible. However, with mass and size budgets, it is important to select efficient materials to provide shielding. Currently, NASA and other space agencies plan on using water as a shield against radiation since it is already necessary for human missions. Water has been tested thoroughly and has been proven to be effective. Liquid propellants are needed for every mission and also share similar …

Using Ai For Management Of Field Emission In Srf Linacs, A. Carpenter, P. Degtiarenko, R. Suleiman, C. Tennant, D. Turner, L. S. Vidyaratne, Khan Iftekharuddin, Md. Monibor Rahman

Electrical & Computer Engineering Faculty Publications

Field emission control, mitigation, and reduction is critical for reliable operation of high gradient superconducting radio-frequency (SRF) accelerators. With the SRF cavities at high gradients, the field emission of electrons from cavity walls can occur and will impact the operational gradient, radiological environment via activated components, and reliability of CEBAF’s two linacs. A new effort has started to minimize field emission in the CEBAF linacs by re-distributing cavity gradients. To measure radiation levels, newly designed neutron and gamma radiation dose rate monitors have been installed in both linacs. Artificial intelligence (AI) techniques will be used to identify cavities with high …

Estimates Of Damped Equilibrium Energy Spread And Emittance In A Dual Energy Storage Ring, B. Dhital, Y. S. Derbenev, D. Douglas, A. Hutton, G. A. Krafft, F. Lin, V.S. Morozov, Y. Zhang

Physics Faculty Publications

A dual energy storage ring design consists of two loops at markedly different energies. As in a single-energy storage ring, the linear optics in the ring design may be used to determine the damped equilibrium emittance and energy spread. Because the individual radiation events in the two rings are different and independent, we can provide analytical estimates of the damping times in a dual energy storage ring. Using the damping times, the values of damped energy spread, and emittance can be determined for a range of parameters related to lattice design and rings energies. We present analytical calculations along with …

Average Speech Directivity, Samuel D. Bellows, Claire M. Pincock, Jennifer K. Whiting, Timothy W. Leishman

Directivity

Speech directivity describes the angular dependence of acoustic radiation from a talker’s mouth and nostrils and diffraction about his or her body and chair (if seated). It is an essential physical aspect of communication affecting sounds and signals in acoustical environments, audio, and telecommunication systems. Because high-resolution, spherically comprehensive measurements of live, phonetically balanced speech have been unavailable in the past, the authors have undertaken research to produce and share such data for simulations of acoustical environments, optimizations of microphone placements, speech studies, and other applications. The measurements included three male and three female talkers who repeated phonetically balanced passages …

Targeted Germanium Ion Irradiation Of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistors, Melanie E. Mace

Theses and Dissertations

Microscale beams of germanium ions were used to target different locations of aluminum galliumnitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs) to determine location dependent radiation effects. 1.7 MeV Ge ions were targeted at the gap between the gate and the drain to observe displacement damage effects while 47 MeV Ge ions were targeted at the gate to observe ionization damage effects. Electrical data was taken pre, during, and post irradiation. To separate transient from permanent degradation, the devices were characterized after a room temperature anneal for at least 30 days. Optical images were also analyzed pre and post irradiation. …

Integrated Environment And Proximity Sensing For Uav Applications, Shawn S. Brackett

Electronic Theses and Dissertations

As Unmanned Aerial Vehicle (UAV), or “drone” applications expand, new methods for sensing, navigating and avoiding obstacles need to be developed. The project applies an Extended Kalman Filter (EKF) to a simulated quadcopter vehicle though Matlab in order to estimate not only the vehicle state but the world state around the vehicle. The EKF integrates multiple sensor readings from range sensors, IMU sensors, and radiation sensors and combines this information to optimize state estimates. The result is an estimated world map to be used in vehicle navigation and obstacle avoidance.

The simulation handles the physics behind the vehicle flight. As …

Cryogenic Test Of A 750 Mhz Superconducting Rf Dipole Crabbing Cavity, A. Castilla, Hyekyoung Park, J. R. Delayen

Physics Faculty Publications

A superconducting rf dipole cavity has been designed to address the challenges of a high repetition rate (750 MHz), high current for both electron/ion species (0.5/3 A per bunch), and large crossing angle (50 mrad) at the interaction points (IPs) crabbing system for the Medium Energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The cavity prototype built at Niowave, Inc. has been tested at the Jefferson Lab facilities. In this work we present a detailed analysis of the prototype cavity performance at 4 K and 2 K, corroborating the absence of hard multipacting barriers that could limit the desired transverse …

Integration Of A Worldwide Atmospheric Based Model With A Live Virtual Constructive Simulation Environment, David B. Simmons

Theses and Dissertations

Yearly DoD spends millions of dollars on Modeling and Simulation tools in order to accomplish two fundamental tasks: make better decisions and develop better skills. Simulators that are based on realistic models enable the USAF to properly train, educate, and employ military forces. LEEDR is an atmospheric model based on worldwide historic weather data that is able to predict the extinction, absorption, and scattering of radiation across a broad range of the electromagnetic spectrum. Through this study LEEDR models the propagation of 1.0642 micron laser radiation at worldwide locations and through various environmental conditions. This modeled laser transmission output, based …

Advances In Space Radiation Shielding Codes, John W. Wilson, Ram K. Tripathi, Garry D. Qualls, Francis A. Cucinotta, Richard E. Prael, John W. Norbury, John H. Heinbockel, John Tweed, Giovanni De Angelis

Mathematics & Statistics Faculty Publications

Early space radiation shield code development relied on Monte Carlo methods and made important contributions to the space program. Monte Carlo methods have resorted to restricted one-dimensional problems leading to imperfect representation of appropriate boundary conditions. Even so, intensive computational requirements resulted and shield evaluation was made near the end of the design process. Resolving shielding issues usually had a negative impact on the design. Improved spacecraft shield design requires early entry of radiation constraints into the design process to maximize performance and minimize costs. As a result, we have been investigating high-speed computational procedures to allow shield analysis from …