8,098 research outputs found

    Sensors for ceramic components in advanced propulsion systems: Summary of literature survey and concept analysis, task 3 report

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    The results of a literature survey and concept analysis related to sensing techniques for measuring of surface temperature, strain, and heat flux for (non-specific) ceramic materials exposed to elevated temperatures (to 2200 K) are summarized. Concepts capable of functioning in a gas turbine hot section environment are favored but others are reviewed also. Recommendation are made for sensor development in each of the three areas

    The multiple-function multi-input/multi-output digital controller system for the AFW wind-tunnel model

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    A real time multiple-function digital controller system was developed for the Active Flexible Wing (AFW) Program. The digital controller system (DCS) allowed simultaneous execution of two control laws: flutter suppression and either roll trim or a rolling maneuver load control. The DCS operated within, but independently of, a slower host operating system environment, at regulated speeds up to 200 Hz. It also coordinated the acquisition, storage, and transfer of data for near real time controller performance evaluation and both open- and closed-loop plant estimation. It synchronized the operation of four different processing units, allowing flexibility in the number, form, functionality, and order of control laws, and variability in the selection of the sensors and actuators employed. Most importantly, the DCS allowed for the successful demonstration of active flutter suppression to conditions approximately 26 percent (in dynamic pressure) above the open-loop boundary in cases when the model was fixed in roll and up to 23 percent when it was free to roll. Aggressive roll maneuvers with load control were achieved above the flutter boundary. The purpose here is to present the development, validation, and wind tunnel testing of this multiple-function digital controller system

    Laser ion source for particle accelerators

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    There is an interest in accelerating atomic nuclei to produce particle beams for medical therapy, atomic and nuclear physics, inertial confinement fusion and particle physics. Laser Ion Sources, in which ions are extracted from plasma created when a high power density laser beam pulse strikes a solid surface in a vacuum, are not in common use. However, some new developments in which heavy ions have been accelerated show that such sources have the potential to provide the beams required for high-energy accelerator systems

    On-line analysis capabilities developed to support the AFW wind-tunnel tests

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    A variety of on-line analysis tools were developed to support two active flexible wing (AFW) wind-tunnel tests. These tools were developed to verify control law execution, to satisfy analysis requirements of the control law designers, to provide measures of system stability in a real-time environment, and to provide project managers with a quantitative measure of controller performance. Descriptions and purposes of the developed capabilities are presented along with examples. Procedures for saving and transferring data for near real-time analysis, and descriptions of the corresponding data interface programs are also presented. The on-line analysis tools worked well before, during, and after the wind tunnel test and proved to be a vital and important part of the entire test effort

    Multiple-function multi-input/multi-output digital control and on-line analysis

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    The design and capabilities of two digital controller systems for aeroelastic wind-tunnel models are described. The first allowed control of flutter while performing roll maneuvers with wing load control as well as coordinating the acquisition, storage, and transfer of data for on-line analysis. This system, which employs several digital signal multi-processor (DSP) boards programmed in high-level software languages, is housed in a SUN Workstation environment. A second DCS provides a measure of wind-tunnel safety by functioning as a trip system during testing in the case of high model dynamic response or in case the first DCS fails. The second DCS uses National Instruments LabVIEW Software and Hardware within a Macintosh environment

    Post-disciplinary Responses to Positivism’s Punitiveness

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    This article posits a post-disciplinary framework to offer an alternative to the epistemological premise of positivist criminology. We seek to destabilise the punitive, deficit analysis of Indigenous people by Western, positivist Criminology. Instead, we look towards Indigenous strengths and resilience to counter deficit narratives about Indigenous people that have served to over-criminalise and over-incarcerate Indigenous peoples since colonisation. In doing so, we argue that positivist disciplinary knowledge is complicit in undermining Indigenous knowledges. We provide a case study that contrasts an institutional approach to researching ‘grog trials’ with the approach of the Tangentyere Research Hub, our ongoing research partner in Alice Springs (Central Australia). Our case study demonstrates the benefits of Tangentyere’s reliance on local Indigenous knowledges and perspectives, rather than disciplinary assumptions, for empowering, strengthening and supporting Indigenous communities and self-governance. In attempting to decolonise criminology, we advance a postdisciplinary approach that highlights questions of Indigenous wellbeing and its relationship with Indigenous self-determination over inquiries into Indigenous crime and the punitive role of the state

    Electrostatic quadrupoles

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    The equations of motion of the charged particle under the action of electric forces in the simple Electrostatic Quadrupole (ESQ) and in the Helical Electrostatic Quadrupole (HESQ) are solved. The HESQ electric field is realized by the four pole tips forming concentric helices of pitch b. The transformation matrices for ESQ and HESQ are found as the basic elements for designing more complex optical systems
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