Hover Acoustic Characteristics of the XV-15 with Advanced Technology Blades

An experiment has been performed to investigate the far-field hover acoustic characteristics of the XV-15 aircraft with advanced technology blades (ATB). An extensive, high-quality, far-field acoustics data base was obtained for a rotor tip speed range of 645-771 ft/s. A 12-microphone, 500-ft radius semicircular array combined with two aircraft headings provided acoustic data over the full 360-deg azimuth about the aircraft with a resolution of 15 deg. Altitude variations provided data from near in-plane to 45 deg below the rotor tip path plane. Acoustic directivity characteristics in the lower hemisphere are explored through pressure time histories, narrow-band spectra, and contour plots. Directivity patterns were found to vary greatly with azimuth angle, especially in the forward quadrants. Sharp positive pressure pulses typical of blade-vortex interactions were found to propagate aft of the aircraft and were most intense at 45 deg below the rotor plane. Modest overall sound pressure levels were measured near in-plane indicating that thickness noise is not a major problem for this aircraft when operating in the hover mode with ATB. Rotor tip speed reductions reduced the average overall sound pressure level (dB (0.0002 dyne/cm(exp 2)) by nearly 8 dB in-plane, and 12.6 deg below the rotor plane

State and Local Legislation: More Hurdles for Unmanned Aerial Systems (UAS) Integration?

Congressional mandate for the integration of unmanned aerial systems (UAS) in the National Airspace System (NAS) to take place by 2015, significant interest in UAS investment, operations, and research has taken place Complex array of requirements and restrictions have been placed on UAS stakeholders by the Federal Aviation Administration (FAA) Limited Congressional legislative guidanc

The Role of Unmanned Aircraft Systems (UAS) in Disaster Response and Recovery Efforts: Historical, Current and Future

A wide range of legislation has been proposed or put into place that restricts the use of unmanned systems. These actions by legislators and regulators will stifle the growth of this technology and the associated surrounding industry. The largest obstacle to the proliferation of UAS in the U.S. is the FAA. The FAA has designated the location of six test sites that are anticipated to allow for less restrictive and formative research to assess the technologies that the FAA has claimed need to exist in order to integrate UAS into the NAS. Further complicating the adoption of UAS for beneficent causes is the plethora of local and state legislation and regulation. Whilst many state restrictions do have built-in caveats to potentially allow for disaster support utilizing UAS, not all are so explicit. All of these actions make the adoption ofUAS in disaster areas more complex and may sway associated agencies away from purchasing UAS for these uses in the future. This research outlines historical uses of UAS to provide basis for the adoption in disaster relief. Examples of past use of unmanned systems in exigent event response are provided including post-hurricane rescue, wild fire monitoring, and landslide disaster relief. An example of missed opportunities with UAS, the Boston Marathon bombing is also outlined. Current UAS usage in first response is explained including types of platforms and sensors that show promise in such operations. Future considerations for UAS adoption in disaster efforts are outlined

The post-common-envelope, binary central star of the planetary nebula Hen 2-11

We present a detailed photometric study of the central star system of the planetary nebula Hen 2-11, selected for study because of its low-ionisation filaments and bipolar morphology - traits which have been strongly linked with central star binarity. Photometric monitoring with NTT-EFOSC2 reveals a highly irradiated, double-eclipsing, post-common-envelope system with a period of 0.609 d. Modelling of the lightcurve indicates that the nebular progenitor is extremely hot, while the secondary in the system is probably a K-type main sequence star. The chemical composition of the nebula is analysed, showing Hen 2-11 to be a medium-excitation non-Type I nebula. A simple photoionisation model is constructed determining abundance ratios of C/O and N/O which would be consistent with the common-envelope cutting short the AGB evolution of the nebular progenitor. The detection of a post-common-envelope binary system at the heart of Hen 2-11 further strengthens the link between binary progeny and the formation of axisymmetric planetary nebulae with patterns of low-ionisation filaments, clearly demonstrating their use as morphological indicators of central star binarity.Comment: Accepted for publication in A&A. 9 pages, 5 figures, 4 table

Characterizing Shear Wave Contact Transducers by Immersion Scanning

Shear wave ultrasonic transducers for contact mode testing are commercially available. These packaged transducers usually contain a circular piezoelectric element and the mounting is such that the polarization direction of the shear vibration is defined by a line passing through the center of the transducer and the electrical connector. For measure ments in isotropic materials, the polarization direction is not important. For quantitative shear wave measurements in anisotropic materials such as composites1–3, it is important to know the polarization direction of the transducer with a good precision. Unfortunately, commercial shear wave transducers are usually not very accurate in their mounting; it is not uncommon to have +/- 10° of error in their polarization direction and much greater errors have also been encountered

Human Claustrum Activation During Pain

Chronic pain is one of the principal causes of disability in the world. Many if not all of us deal with or know of someone who deals with chronic pain. Interestingly, it appears that a mysterious part of the brain known as the claustrum has a hand in chronic pain. Although little is known about the actual function of the claustrum, it is hypothesized to synchronize cortical networks during tasks which have a cognitive load. Recent literature has indicated that during chronic pain conditions, neural network recruitment is modified. In addition, an analysis of an existing fMRI data set determined that chronic pain patients have altered claustrum activation as opposed to healthy controls. The purpose of this research was to determine the effect(s) of pain on claustrum activation in healthy controls using fMRI

Ariel - Volume 5 Number 5

Editors Mark Dembert J. D. Kanofsky Entertainment Robert Breckenridge Joe Conti Gary Kaskey Photographer Scot Kastner Overseas Editor Mike Sinason Circulation Jay Amsterdam Humorist Jim McCann Staff Ken Jaffe Bob Sklaroff Janet Welsh Dave Jacoby Phil Nimoityn Frank Chervane