15,884 research outputs found

    Local Ferroelectricity in SrTiO_3 Thin Films

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    The temperature-dependent polarization of SrTiO_3 thin films is investigated using confocal scanning optical microscopy. A homogeneous out-of-plane and inhomogeneous in-plane ferroelectric phase are identified from images of the linear electrooptic response. Both hysteretic and non-hysteretic behavior are observed under a dc bias field. Unlike classical transitions in bulk ferroelectrics, local ferroelectricity is observed at temperatures far above the dielectric permittivity maximum. The results demonstrate the utility of local probe experiments in understanding inhomogeneous ferroelectrics.Comment: 8 pages, 3 figures, accepted for publication in PR

    Laser Doppler technology applied to atmospheric environmental operating problems

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    Carbon dioxide laser Doppler ground wind data were very favorably compared with data from standard anemometers. As a result of these measurements, two breadboard systems were developed for taking research data: a continuous wave velocimeter and a pulsed Doppler system. The scanning continuous wave laser Doppler velocimeter developed for detecting, tracking and measuring aircraft wake vortices was successfully tested at an airport where it located vortices to an accuracy of 3 meters at a range of 150 meters. The airborne pulsed laser Doppler system was developed to detect and measure clear air turbulence (CAT). This system was tested aboard an aircraft, but jet stream CAT was not encountered. However, low altitude turbulence in cumulus clouds near a mountain range was detected by the system and encountered by the aircraft at the predicted time

    The Mature Market: Underlying Dimensions and Group Differences of a Potential Market for the Hotel Industry

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    The mature market, defined as age 55 and up and consisting of approximately 64 million Americans, is expected to increase. Studies show that this group travels more frequently, travels greater distances, and stays longer. The authors seek to determine if underlying dimensions exist for the mature individual with regard to the selection criteria for lodging when traveling for pleasure, and to determine if differences exist between various demographic subsegments of this market with regard to these underlying dimensions

    Laser Doppler dust devil measurements

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    A scanning laser doppler velocimeter (SLDV) system was used to detect, track, and measure the velocity flow field of naturally occurring tornado-like flows (dust devils) in the atmosphere. A general description of the dust devil phenomenon is given along with a description of the test program, measurement system, and data processing techniques used to collect information on the dust devil flow field. The general meteorological conditions occurring during the test program are also described, and the information collected on two selected dust devils are discussed in detail to show the type of information which can be obtained with a SLDV system. The results from these measurements agree well with those of other investigators and illustrate the potential for the SLDV in future endeavors

    The preparation of corn for dairy cows

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    The corn crop of Iowa exceeds in acreage, yield and value all other grain crops combined. In this state, as well as in other sections of the corn belt, corn must be relied upon as the basis of the concentrate allowance for dairy cattle, as it generally is one of the most economical sources of energy. The extent to which it is used renders it essential that the feeding of it be carefully studied, as what are apparently small economies attain large proportions when considered in the aggregate. The preparation of corn for other types of farm livestock has been studied to some extent, but the influence of the various preparations of corn on the total yield and economy of production of milk and butterfat has received little attention. The work reported here is but a part of a series of investigations being conducted on the influence of the method of preparation of corn on the production of milk, and is a comparison of ear corn, corn-and-cob meal, and corn meal

    Pulsed Doppler lidar for the detection of turbulence in clear air

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    A pulsed C02 Doppler lidar system is described and demonstration tests in ground-based and airborne flight operations are discussed. As a ground-based system, it can detect wind shears in thunderstorm gust fronts to a range of 6 km. When in the airborne configuration, the lidar can detect clear air turbulence in advance of the aircraft encountering clear air turbulence. The data provided by the lidar included turbulence location and intensity with intensity being indicated by the measured spectral width which is proportional to the wind gust velocity
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