16,081 research outputs found

    Delta nitrogen tetroxide fueling operations

    Get PDF
    The development of the Delta second stage nitrogen tetroxide fueling system is briefly summarized. The nitrogen tetroxide fueling system and the equipment used to protect the spacecraft environment from the toxic nitrogen tetroxide fumes are described. Topics covered include: the nitrogen tetroxide transfer system; loading operations; safety precautions; and chemical treatment of all toxic vapors

    Ultrasonic detection of flaws in fusion butt welds

    Get PDF
    Reliable and accurate Delta technique, a nondestructive ultrasonics method, uses redirection of energy to detect randomly oriented imperfections in fusion butt welds. Data on flaws can be read from either an oscilloscope or a printout

    Cognitively Engineering a Virtual Collaboration Environment for Crisis Response

    Get PDF
    Crisis response situations require collaboration across many different organizations with different backgrounds, training, procedures, and goals. The Indian Ocean Tsunami in 2004 and the Hurricane Katrina relief efforts in 2005 emphasized the importance of effective communication and collaboration. In the former, the Multinational Planning Augmentation Team (MPAT) supported brokering of requests for assistance with offers of help from rapidly deployed military and humanitarian assistance facilities. In the aftermath of Hurricane Katrina, the National Guard Soldiers and active component Army Soldiers assisted other state, federal, and non-government organizations with varying degrees of efficiency and expediency. Compounding the challenges associated with collaboration during crisis situations is the distributed nature of the supporting organizations and the lack of a designated leader across these military, government, nongovernment organizations. The Army Research Laboratory is collaborating with the University of Edinburgh, University o

    The Influence of ZnO Layer Thickness on the Performance and Electrical Bias Stress Instality in ZnO Thin Film Transistors

    Get PDF
    University of Buea supported the first author during the writing of this manuscript Open access articleThin Film Transistors (TFTs) are the active elements for future large area electronic applications, in which low cost, low temperature processes and optical transparency are required. Zinc oxide (ZnO) thin film transistors (TFTs) on SiO2/n+-Si substrate are fabricated with the channel thicknesses ranging from 20 nm to 60 nm. It is found that both the performance and gate bias stress related instabilities of the ZnO TFTs fabricated were influenced by the thickness of ZnO active channel layer. The effective mobility was found to improve with increasing ZnO thickness by up to an order in magnitude within the thickness range investigated (20 – 60 nm). However, thinner films were found to exhibit greater stability in threshold voltage and turn-on voltage shifts with respect to both positive and negative gate bias stress. It was also observed that both the turn on voltage (Von) and the threshold voltage (VT) decrease with increasing channel thickness. Moreover, the variations in subthreshold slope (S) with ZnO thickness as well as variations in VT and Von suggest a possible dependence of trap states in the ZnO on the ZnO thickness. This is further correlated by the dependence of VT and Von instabilities with gate bias stress

    A review and evaluation of the Langley Research Center's scientific and technical information program. Results of phase 1: Knowledge and attitudes survey, LaRC research personnel

    Get PDF
    The effectiveness of the Langley STI program was assessed using feedback obtained from Langley engineers and scientists. A survey research procedure was conducted in two stages. Personal interviews with 64 randomly selected Langley engineers and scientists were used to obtain information for questionnaire development. Data were then collected by means of the questionnaire which covered various aspects of the Langley STI program, utilized both open and closed ended questions and was pretested for finalization. The questions were organized around the six objectives for Phase 1. The completed questionnaires were analyzed. From the analysis of the data, recommendations were made for improving the Langley STI program

    Upper Pennsylvanian Coals and Associated Rocks – Depositional Environments, Sedimentation, Paleontology and Paleobotany, Upper Ohio River Valley

    Get PDF
    Author Institution: Department of Geological Sciences, Michigan State Universit

    Spatiotemporal dynamics of quantum jumps with Rydberg atoms

    Get PDF
    We study the nonequilibrium dynamics of quantum jumps in a one-dimensional chain of atoms. Each atom is driven on a strong transition to a short-lived state and on a weak transition to a metastable state. We choose the metastable state to be a Rydberg state so that when an atom jumps to the Rydberg state, it inhibits or enhances jumps in the neighboring atoms. This leads to rich spatiotemporal dynamics that are visible in the fluorescence of the strong transition.Comment: 10 page

    Hydrazine monitoring in spacecraft

    Get PDF
    Hydrazine (HZ) and monomethyl hydrazine (MMH) are highly toxic compounds used as fuels in the Space Shuttle Orbiter Main Engines and in its maneuvering and reaction control system. Satellite refueling during a mission may also result in release of hydrazines. During extravehicular activities, the potential exists for hydrazines to contaminate the suit and to be brought into the internal atmosphere inadvertantly. Because of the high toxicity of hydrazines, a very sensitive, reliable, interference-free, and real-time method of measurement is required. A portable ion mobility spectrometer (IMS) has exhibited a low ppb detection limit for hydrazines suggesting a promising technology for the detection of hydrazines in spacecraft air. The Hydrazine Monitor is a modified airborne vapor monitor (AVM) with a custom-built datalogger. This off-the-shelf IMS was developed for the detection of chemical warfare agents on the battlefield. After early evaluations of the AVM for hydrazine measurements showed a serious interference from ammonia, the AVM was modified to measure HZ and MMH in the ppb concentration range without interference from ammonia in the low ppm range. A description of the Hydrazine Monitor and how it functions is presented

    THE ECONOMICS OF ILLEGAL FISHING: A BEHAVIORAL MODEL

    Get PDF
    This paper analyzes the microeconomic behavior of fishers responding to imperfectly enforced regulations through illegal fishing and efforts to avoid detection. An intraseasonal optimization model is analyzed to determine optimal (profit-maximizing) harvesting strategies at the individual fisher level in response to input controls (such as gear or labor usage) or output controls (individual harvest quotas). For each regulatory option, the analysis explores: (a) the manner by which enforcement affects individual decisions concerning fishing and avoidance activity, (b) the level of enforcement necessary to achieve specified conservation goals, and (c) the role of various behavioral parameters in determining fisher decisions. It is shown, in particular, that the nature of avoidance behavior plays a crucial role in determining fisher response to regulations. Broad implications of illegal behavior on the sustainability of fishery systems are also discussed.Resource /Energy Economics and Policy,

    Age Verification in the 21st Century: Swiping Away Your Privacy, 23 J. Marshall J. Computer & Info. L. 363 (2005)

    Get PDF
    Today a lot of private businesses have adopted the practice of driver\u27s license swiping where proof of age or security issues arise. This practice has beneficial uses for both private entities, in identifying underage persons and those with fake identification, and law enforcement. However, the problem arise when the private sector, businesses are not using the information to merely identify underage customers or those with fake identification but store the information encoded on the barcode in a computer database. No federal laws and very few state laws regulate the collection and use of this information while the private sector is not following the basic guidelines to make people aware that their information is being collected electronically and to alert them to how it is being used. This comment argues that United States citizens have a right to privacy with regard to the information contained on their identification cards. First, the background of how personal information is being stored on Driver’s license is presented and a more detailed description of how swiping technology works follows. Next the author examines the state and federal regulations currently existing to govern this practice of driver\u27s license swiping. The Fair Information Practice Principles are also being presented and a brief history of their application is given. Then, all the current applications of swiping, including law enforcement and private enterprise use is examined and a more detailed analysis of the potential costs and benefits of scanning and data retention is given to determine whether the practice should continue to be unregulated in private enterprises. It is argued that a person should have the right to purchase something that is legal without having to exchange his or her sensitive information for this item and that people should be aware that their information is being collected and receive notice as to how it could be used. In conclusion, it is suggested that legislation be put in place to regulate the practice of scanning and storing patron\u27s personal information since it is almost inevitable that once the practice of swiping becomes widespread among private enterprises that must check for proof of age, this information may fall into the wrong person\u27s hands
    • …
    corecore