2,883 research outputs found

    Application of magnitude estimation scaling to the assessment of subjective loudness response to simulated sonic booms

    Get PDF
    A laboratory study was conducted for the following reasons: (1) to investigate the application of magnitude estimation scaling for evaluating the subjective loudness of sonic booms; and (2) to compare the relative merits of magnitude estimation and numerical category scaling for sonic boom loudness evaluation. The study was conducted in the NASA LeRC's sonic boom simulator and used a total of 80 test subjects (48 for magnitude estimation and 32 for numerical category scaling). Results demonstrated that magnitude estimation was a practical and effective method for quantifying subjective loudness of sonic booms. When using magnitude estimation, the subjects made valid and consistent ratio judgments of sonic boom loudness irrespective of the frequency of presentation of the standard stimulus. Presentation of the standard as every fourth stimulus was preferred by the subjects and is recommended as the standard presentation frequency to be used in future tests

    Benchmarking Customer Service Practices of Air Cargo Carriers: A Case Study Approach

    Get PDF
    This study used the benchmarking process incorporated in a case study approach to determine what the Air Force could learn from the commercial air cargo carriers in regard to customer service practices. The air cargo industry leaders were determined through a previous study to be United Parcel Service, Federal Express, Emery Air Freight, Airborne Freight, DHL Airways, and Burlington Air Express. In addition, the 437th Aerial Port Squadron APS at Charleston AFB South Carolina was the Air Force representative in the benchmarking study. Interviews with air cargo managers were conducted at each carrier’s main hub and at Charleston AFB. The interview process resulted in the conclusion that most of the customer service practices in the commercial air cargo industry and the Air Force aerial port are similar. The Air Force is superior in customer service report dissemination, but is deficient in customer awareness and in-transit cargo visibility. Recommendations include employee appraisal modification, 360-degree review usage, focus group utilization, and frequent AMC executive and APS management communication

    Theory of imaging a photonic crystal with transmission near-field optical microscopy

    Full text link
    While near-field scanning optical microscopy (NSOM) can provide optical images with resolution much better than the diffraction limit, analysis and interpretation of these images is often difficult. We present a theory of imaging with transmission NSOM that includes the effects of tip field, tip/sample coupling, light propagation through the sample and light collection. We apply this theory to analyze experimental NSOM images of a nanochannel glass (NCG) array obtained in transmission mode. The NCG is a triangular array of dielectric rods in a dielectric glass matrix with a two-dimensional photonic band structure. We determine the modes for the NCG photonic crystal and simulate the observed data. The calculations show large contrast at low numerical aperture (NA) of the collection optics and detailed structure at high NA consistent with the observed images. We present calculations as a function of NA to identify how the NCG photonic modes contribute to and determine the spatial structure in these images. Calculations are presented as a function of tip/sample position, sample index contrast and geometry, and aperture size to identify the factors that determine image formation with transmission NSOM in this experiment.Comment: 28 pages of ReVTex, 14 ps figures, submitted to Phys. Rev.

    Experiments with a Slow Neutron Velocity Spectrometer II

    Get PDF
    The apparatus previously used for the determination of neutron energy by time of flight method has been completely rebuilt with a view to increasing the accuracy of measurement as well as the high energy limit. The repetition frequency is obtained from a series of relaxation oscillators and a 50-kc oscillator and frequencies of 100, 200, 500, 1000, and 2500 c.p.s. are available. Four detector channels have been built so that neutrons in four different time of flight groups can be counted simultaneously. When used with the highest repetition frequency, this decreases the time to obtain data by a factor of 24 and has thus made the present experiments feasible with the small Cornell cyclotron. The study of the transmission of Ag with a 1.35-g/cm^2 absorber shows a single strong resonance at 5.8 ev. A re-examination of In with considerably higher resolution than was previously used shows a single resonance at about 1.35 ev. The effective mean life of neutrons in several different sources was examined and a thin paraffin source with Cd backing devised for measurements in the thermal region. The absorption of B has been examined and found to be proportional to 1/v within the limits of error of the experiment, from 0.028 to 50 ev. An experiment to determine the B cross section of the Cd stopped neutrons gave 540×10^(−24) cm^2. The B absorption curve shows that the cross section of thermal neutrons (0.025 ev) is 708×10^(−24) cm^2. It is concluded that the effective energy of the Cd stopped neutrons is not that of kT at thermal energy, for the geometry used, but is 0.041 ev. This conclusion is confirmed by the measured resonances in Ag and In which are higher than the values obtained by the boron absorption method. Correction of these values, as measured by Horvath and Salant (reference 4) for the effective energy of the Cd stopped neutrons, leads to 1.32 ev for In and 5.2 ev for Ag, in agreement with the present results. It is concluded that resonances measured by the boron absorption method are in error by an amount which depends upon the geometry of the experiment, and are probably too low by a factor of 0.041/0.025 = 1.64

    Weight Management Program for Fire Fighters: Feasibility Pilot

    Get PDF
    Please view abstract in the attached PDF fil

    Inelastic scattering of broadband electron wave packets driven by an intense mid-infrared laser field

    Full text link
    Intense, 100 fs laser pulses at 3.2 and 3.6 um are used to generate, by multi-photon ionization, broadband wave packets with up to 400 eV of kinetic energy and charge states up to Xe+6. The multiple ionization pathways are well described by a white electron wave packet and field-free inelastic cross sections, averaged over the intensity-dependent energy distribution for (e,ne) electron impact ionization. The analysis also suggests a contribution from a 4d core excitation in xenon

    Factors associated with the decision to investigate child protective services referrals: a systematic review

    Get PDF
    Background: Limited resources for child protection create challenging decision situations for child protective services (CPS) workers at the point of intake. A body of research has examined the factors associated with worker decisions and processes using a variety of methodological approaches to gain knowledge on decision-making. However, few attempts have been made to systematically review this literature. Objective: As part of a larger project on decision-making at intake, this systematic review addressed the question of the factors associated with worker decisions to investigate alleged maltreatment referrals. Methods: Quantitative studies that examined factors associated with screening decisions in CPS practice settings were included in the review. Database and other search methods were used to identify research published in English over a 35-year period (1980-2015). Findings: Of 1,147 identified sources, 18 studies were selected for full data extraction. The studies were conducted in the U.S., Canada, and Sweden and varied in methodological quality. Most studies examined case factors with few studies examining other domains. Conclusions: To inform CPS policy and practice, additional research is needed to examine the relationships between decision-making factors and case outcomes. Greater attention needs to be given to the organizational and external factors that influence decision-making

    In-beam gamma-ray spectroscopy of 35Mg and 33Na

    Full text link
    Excited states in the very neutron-rich nuclei 35Mg and 33Na were populated in the fragmentation of a 38Si projectile beam on a Be target at 83 MeV/u beam energy. We report on the first observation of gamma-ray transitions in 35Mg, the odd-N neighbor of 34Mg and 36Mg, which are known to be part of the "Island of Inversion" around N = 20. The results are discussed in the framework of large- scale shell-model calculations. For the A = 3Z nucleus 33Na, a new gamma-ray transition was observed that is suggested to complete the gamma-ray cascade 7/2+ --> 5/2+ --> 3/2+ gs connecting three neutron 2p-2h intruder states that are predicted to form a close-to-ideal K = 3/2 rotational band in the strong-coupling limit.Comment: Accepted for publication Phys. Rev. C. March 16, 2011: Replaced figures 3 and 5. We thank Alfredo Poves for pointing out a problem with the two figure
    • …
    corecore