9 research outputs found

    Implementation of a Positioning and Telemetry Buoy to Determine Chart Datum for Hydrographic Survey Applications

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    The Naval Oceanographic Office (NAVOCEANO) and the U. S. Navy’s Fleet Survey Team (FST) conduct worldwide hydrographic surveys in accordance with International Hydrographic Organization (IHO) S-44 standards. The current concept of operations (CONOPS) requires that tide gauges be installed in-shore to define the local vertical chart datum. This requires clearances and permissions from national and local authorities as well as landowners in order to establish and access these shore stations. Substantial effort to establish and maintain security for shore parties and equipment left behind is also required. The recent implementation of real-time Global Differential GPS (GDGPS) point positioning technology presents an opportunity to change and greatly simplify the current CONOPS. Reprinted with permission from The Institute of Navigation (http://ion.org/) and The Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation, (pp. 801-804). Fairfax, VA: The Institute of Navigation

    A Case Study of Laser Wind Sensor Performance Validation by Comparison to an Existing Gage

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    A case study concerning validation of wind speed measurements made by a laser wind sensor mounted on a 190 square foot floating platform in Muskegon Lake through comparison with measurements made by pre-existing cup anemometers mounted on a met tower on the shore line is presented. The comparison strategy is to examine the difference in measurements over time using the paired-t statistical method to identify intervals when the measurements were equivalent and to provide explanatory information for the intervals when the measurements were not equivalent. The data was partitioned into three sets: not windy (average wind speed measured by the cup anemometers ≤ 6.7m/s) windy but no enhanced turbulence (average wind speed measured by the cup anemometers \u3e 6.7m/s), and windy with enhanced turbulence associated with storm periods. For the not windy data set, the difference in the average wind speeds was equal in absolute value to the precision of the gages and not statistically significant. Similar results were obtained for the windy with no enhanced turbulence data set and the average difference was not statistically significant (α=0.01). The windy with enhanced turbulence data set showed significant differences between the buoy mounted laser wind sensor and the on-shore mast mounted cup anemometers. The sign of the average difference depended on the direction of the winds. Overall, validation evidence is obtained in the absence of enhanced turbulence. In addition, differences in wind speed during enhanced turbulence were isolated in time, studied and explained

    Prospective Study of Infection, Colonization and Carriage of Methicillin-Resistant Staphylococcus Aureus in an Outbreak Affecting 990 Patients

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    In the three years between November 1989 and October 1992, an outbreak of methicillin-resistantStaphylococcus aureus (MRSA) affected 990 patients at a university hospital. The distribution of patients with carriage, colonization or infection was investigated prospectively. Nosocomial acquisition was confirmed in at least 928 patients, 525 of whom were identified from clinical specimens as being infected (n=418) or colonized (n=107) by MRSA. An additional 403 patients were identified from screening specimens, of whom 58 subsequently became infected and 18 colonized. Screening of the nose, throat and perineum detected 98 % of all carriers. Of the 580 infections in 476 patients, surgical wound, urinary tract and skin infections accounted for 58 % of the infections. Of the 476 infected patients, death was attributable to MRSA infection in 13 %. Colonization with MRSA was found in 127 patients and 42 % of 165 colonized sites were the skin. Auto-infection from nasal carriage or cross-infection, probably via staff hands, seemed to be the most common mode of acquisition of MRSA infections

    Laser Wind Sensor Performance Validation with an Existing Gage

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    A new approach to laser wind sensor measurement validation is described and demonstrated. The new approach relies on the paired-t statistical method to generate a time series of differences between two sets of measurements. This series of differences is studied to help identify and explain time intervals of operationally significant differences, which is not possible with the traditional approach of relying on the squared coefficient of variation as the primary metric. The new approach includes estimating a confidence interval for the mean difference and establishing a level of meaningful difference for the mean difference, and partitioning the data set based on wind speed. To demonstrate the utility of the new approach, measurements made by a laser wind sensor mounted on a floating buoy are compared first with those made by a second laser wind sensor mounted on a nearby small island for which the co-efficient of variation is high (\u3e 99%). It was found that time intervals when high differences in wind speed occurred corresponded to high differences in wind direction supporting a hypothesis that the two laser wind sensor units are not always observing the same wind resource. Furthermore, the average difference for the 100m range gate is positive, statistically significant (α=0.01) and slightly larger than the precision of the gages, 0.1m/s. One possible cause of this difference is that the surface roughness over land is slowing the wind at 100m slightly. A second comparison was made with previously existing cup anemometers mounted on a metrological mast located on-shore. The cup anemometers are about 8m lower than the center of the lowest range gate on the laser wind sensor. The data was partitioned into three sets: not windy (average wind speed at the cup anemometers ≤ 6.7m/s) windy but no enhanced turbulence (average wind speed at the cup anemometers \u3e 6.7m/s), and windy with enhanced turbulence. Periods of enhanced turbulence are associated with the passage of a cold frontal boundary. The paired-t analysis for the not windy data set showed a difference in the average wind speeds of -0.096m/s, less in absolute value than the precision of the gages. The negative sign indicates slower wind speed over land as well as at a lower height, which is expected. Similar results were obtained for the windy with no enhanced turbulence data set. In addition, the average difference was not statistically significant (α=0.01). The windy with enhanced turbulence data set showed significant differences between the buoy mounted laser wind sensor and the on-shore mast mounted cup anemometers. The sign of the average difference depended on the direction of the winds in the periods of enhanced turbulence. Mean turbulent kinetic energy was measured to be greater when air flow into Muskegon Lake was predominantly from over land versus when air flow was predominantly from Lake Michigan. The higher mean turbulent kinetic energy for flow originating over land would likely be due to greater surface roughness experienced by the overland flow. Overall, the value of the new approach in obtaining validation evidence has been demonstrated. In this case, validation evidence is obtained in periods of no enhanced turbulence. Differences in wind speed during periods of enhanced turbulence are isolated in time, studied and are correlated in time with differences in wind direction

    Evaluation of MBari puck protocol for interoperable ocean observatories

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    IEEE-1451[1] and OGC Sensor Web Enablement (OGC SWE)[2] define standard protocols to operate instruments, including methods to calibrate, configure, trigger data acquisition, and retrieve instrument data based on specified temporal and geospatial criteria. These standards also provide standard ways to describe instrument capabilities, properties, and data structures produced by the instrument. These standard operational protocols and descriptions enable observing systems to manage very diverse instruments as well as to acquire, process, and interpret their data in a uniform and automated manner. We refer to this property as “instrument interoperability”. This paper describes integration and evaluation of MBARI PUCK protocol [3] within different observatories including OBSEA [4,5] in Spain, the ESONET test-bed in Germany, and the SmartBay observatory in Canada.Peer Reviewe

    Evaluation of MBari puck protocol for interoperable ocean observatories

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    IEEE-1451[1] and OGC Sensor Web Enablement (OGC SWE)[2] define standard protocols to operate instruments, including methods to calibrate, configure, trigger data acquisition, and retrieve instrument data based on specified temporal and geospatial criteria. These standards also provide standard ways to describe instrument capabilities, properties, and data structures produced by the instrument. These standard operational protocols and descriptions enable observing systems to manage very diverse instruments as well as to acquire, process, and interpret their data in a uniform and automated manner. We refer to this property as “instrument interoperability”. This paper describes integration and evaluation of MBARI PUCK protocol [3] within different observatories including OBSEA [4,5] in Spain, the ESONET test-bed in Germany, and the SmartBay observatory in Canada

    Evaluation of MBARI PUCK protocol for interoperable ocean observatories

    No full text
    IEEE-1451[1] and OGC Sensor Web Enablement (OGC SWE)[2] define standard protocols to operate instruments, including methods to calibrate, configure, trigger data acquisition, and retrieve instrument data based on specified temporal and geospatial criteria. These standards also provide standard ways to describe instrument capabilities, properties, and data structures produced by the instrument. These standard operational protocols and descriptions enable observing systems to manage very diverse instruments as well as to acquire, process, and interpret their data in a uniform and automated manner. We refer to this property as “instrument interoperability”. This paper describes integration and evaluation of MBARI PUCK protocol [3] within different observatories including OBSEA [4,5] in Spain, the ESONET test-bed in Germany, and the SmartBay observatory in Canada.Peer Reviewe
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