On the Dynamics and Acoustics of Cloud Cavitation on an Oscillating Hydrofoil

Observations have been made of the growth and collapse of surface and cloud cavitation on a finite aspect ratio hydrofoil oscillating in pitch. The cavitation was recorded using both still and high-speed motion picture photography, and the variations with cavitation number and reduced frequency of oscillation were investigated. The noise generated by the cavity collapse was also measured and analyzed. The acoustic signals associated with individual cavity collapse events have been synchronized with the motion pictures, providing insights into the correspondence between the flow structures involved in the cavity collapse process and the sound generated by them

What is Causing This Man\u27s Rectal Pain and Urinary Retention?

Case: A 23-year-old man presented to an urgent care office with a 2-week history of rectal pain and scant rectal bleeding. In the few days leading up to his presentation, he also had a fever of 101° F (38.3° C), inguinal lymphadenopathy, and urinary retention

Prospectus, November 11, 2009

https://spark.parkland.edu/prospectus_2009/1030/thumbnail.jp

Prospectus, October 14, 2009

https://spark.parkland.edu/prospectus_2009/1027/thumbnail.jp

Responsivity boosting in FIR TiN LEKIDs using phonon recycling: simulations and array design

To characterize further the cosmic star formation history at high redshifts, a large-area survey by a cryogenic 4-6 meter class telescope with a focal plane populated by tens of thousands of far-infrared (FIR, 30-300 μm) detectors with broadband detector noise equivalent powers (NEPs) on the order of 3×10^(-9) W/√ Hz is needed. Ideal detectors for such a surveyor do not yet exist. As a demonstration of one technique for approaching the ultra-low NEPs required by this surveyor, we present the design of an array of 96 350 µm KIDs that utilize phonon recycling to boost responsivity. Our KID array is fabricated with TiN deposited on a silicon-on-insulator (SOI) wafer, which is a 2 μm thick layer of silicon bonded to a thicker slab of silicon by a thin oxide layer. The backside thick slab is etched away underneath the absorbers so that the inductors are suspended on just the 2 μm membrane. The intent is that quasiparticle recombination phonons are trapped in the thin membrane, thereby increasing their likelihood of being re-absorbed by the KID to break additional Cooper pairs and boost responsivity. We also present a Monte-Carlo simulation that predicts the amount of signal boost expected from phonon recycling given different detector geometries and illumination strategies. For our current array geometry, the simulation predicts a measurable 50% boost in responsivity

Prospectus, October 28, 2009

https://spark.parkland.edu/prospectus_2009/1029/thumbnail.jp

Prospectus, November 18, 2009

https://spark.parkland.edu/prospectus_2009/1031/thumbnail.jp

Design considerations for a background limited 350 micron pixel array using lumped element superconducting microresonators

Future submillimeter telescopes will demand arrays with ~ 10^6 pixels to fill the focal plane. MAKO is a 350 µm camera being developed to demonstrate the use of superconducting microresonators to meet the high multiplexing factors required for scaling to large-format arrays while offering background-limited single-pixel sensitivity. Candidate pixel designs must simultaneously meet many requirements. To achieve the desired noise equivalent powers it must efficiently absorb radiation, feature a high responsivity, and exhibit low intrinsic device noise. Additionally, the use of high resonator quality factors of order ~ 10^5 and resonant frequencies of order f_(res) ≈ 100 MHz are desirable in order to reduce the per-pixel bandwidth to a minimum set by telescope scan speeds. This allows a maximum number of pixels to be multiplexed in a fixed electronic bandwidth. Here we present measurement results of the first MAKO prototype array which meets these design requirements while demonstrating sufficient sensitivity for background-limited operation at ground-based, far-infrared telescopes

Development of at silicon-based mesh-lens arrays for millimeter and sub millimeter wave astronomy

The high sensitivity requirements set by future cosmic microwave background instruments are pushing the current technologies to produce highly performant focal plane arrays with thousands of detectors. The coupling of the detectors to the telescope optics is a challenging task. Current implemented solutions include phased-array antenna-coupled detectors, platelet horn arrays, and lenslet-coupled planar antennas. There are also recent developments of flat graded-index lenses based on etched silicon. However, there are strong requirements in terms of electromagnetic performance, such as coupling efficiency and bandwidth, as well as requirements in terms of easy manufacturing and scalability, and it is very challenging to meet all these requirements with one of the above solutions. Here, we present a novel approach for producing flat metal-mesh lenslet arrays based on devices previously realized using the mesh-filter technology. We have now adapted the polypropylene-based mesh lens design to silicon substrates, thus providing a good mechanical match to the silicon-based detector arrays. The measured performance of prototype pixels operating at millimeter wavelengths is presented