397 research outputs found

    Acoustic Emission Analysis Applet (AEAA) Software

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    NASA Glenn Research and NASA White Sands Test Facility have developed software supporting an automated pressure vessel structural health monitoring (SHM) system based on acoustic emissions (AE). The software, referred to as the Acoustic Emission Analysis Applet (AEAA), provides analysts with a tool that can interrogate data collected on Digital Wave Corp. and Physical Acoustics Corp. software using a wide spectrum of powerful filters and charts. This software can be made to work with any data once the data format is known. The applet will compute basic AE statistics, and statistics as a function of time and pressure (see figure). AEAA provides value added beyond the analysis provided by the respective vendors' analysis software. The software can handle data sets of unlimited size. A wide variety of government and commercial applications could benefit from this technology, notably requalification and usage tests for compressed gas and hydrogen-fueled vehicles. Future enhancements will add features similar to a "check engine" light on a vehicle. Once installed, the system will ultimately be used to alert International Space Station crewmembers to critical structural instabilities, but will have little impact to missions otherwise. Diagnostic information could then be transmitted to experienced technicians on the ground in a timely manner to determine whether pressure vessels have been impacted, are structurally unsound, or can be safely used to complete the mission

    State of the U.S. Ocean and Coastal Economies 2014

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    The nation\u27s coasts and oceans contribute much to the United States economy. For the past 14 years, the National Ocean Economics Program (NOEP), now a program of the Center for the Blue Economy at the Monterey Institute of International Studies, has compiled time-series data that track economic activities, demographics, ports and cargo volume and value, natural resource production and value, non-market values, and federal expenditures in the U.S. coastal zone both on land and in the water. A report on the ocean and coastal economies of the United States was released by NOEP in 2009 covering data through 2005. The present report is an update of that study covering the period 2007-2012. State summaries from this report are available on the NOEP website (www.oceaneconomics.org) under Publications

    Research and Development of Automated Eddy Current Testing for Composite Overwrapped Pressure Vessels

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    Eddy current testing (ET) was used to scan bare metallic liners used in the fabrication of composite overwrapped pressure vessels (COPVs) for flaws which could result in premature failure of the vessel. The main goal of the project was to make improvements in the areas of scan signal to noise ratio, sensitivity of flaw detection, and estimation of flaw dimensions. Scan settings were optimized resulting in an increased signal to noise ratio. Previously undiscovered flaw indications were observed and investigated. Threshold criteria were determined for the system software's flaw report and estimation of flaw dimensions were brought to an acceptable level of accuracy. Computer algorithms were written to import data for filtering and a numerical derivative filtering algorithm was evaluated

    Pesticide Ground Water Monitoring Project Phase VIII

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    During Phase VIII monitoring (March 24, 2000 to June 30, 2001 ), 86 samples were collected from 77 new wells and 9 samples were collected from wells with previous detectable herbicide

    Cypselurus from the Atlantic

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    8 p. : ill. ; 23 cm

    Use of Statistical Analysis of Acoustic Emission Data on Carbon-Epoxy COPV Materials-of-Construction for Enhanced Felicity Ratio Onset Determination

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    Broadband modal acoustic emission (AE) data were acquired during intermittent load hold tensile test profiles on Toray T1000G carbon fiber-reinforced epoxy (C/Ep) single tow specimens. A novel trend seeking statistical method to determine the onset of significant AE was developed, resulting in more linear decreases in the Felicity ratio (FR) with load, potentially leading to more accurate failure prediction. The method developed uses an exponentially weighted moving average (EWMA) control chart. Comparison of the EWMA with previously used FR onset methods, namely the discrete (n), mean (n (raised bar)), normalized (n%) and normalized mean (n(raised bar)%) methods, revealed the EWMA method yields more consistently linear FR versus load relationships between specimens. Other findings include a correlation between AE data richness and FR linearity based on the FR methods discussed in this paper, and evidence of premature failure at lower than expected loads. Application of the EWMA method should be extended to other composite materials and, eventually, composite components such as composite overwrapped pressure vessels. Furthermore, future experiments should attempt to uncover the factors responsible for infant mortality in C/Ep strands

    West Indian Cypselurus

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    9 p. : ill. ; 23 cm

    Lantern fishes from southern seas

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    p. 13-19 : ill. ; 24 cm.Includes bibliographical references

    Maine’s Winter Roads: Salt, Safety, Environment and Cost

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    This report summarizes key findings from a yearlong study of the issues and practices in winter maintenance of Maine’s roads
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