3,487 research outputs found

    Passive Acoustic Detection of Wind Turbine In-Flow Conditions for Active Control and Optimization

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    Wind is a significant source of energy; however, the human capability to produce electrical energy still has many hurdles to overcome. One of these is the unpredictability of the winds in the atmospheric boundary layer (ABL). The ABL is highly turbulent in both stable and unstable conditions (based on the vertical temperature profile) and the resulting fluctuations can have a dramatic impact on wind turbine operation. Any method by which these fluctuations could be observed, estimated, or predicted could provide a benefit to the wind energy industry as a whole. Based on the fundamental coupling of velocity fluctuations to pressure fluctuations in the nearly incompressible flow in the ABL, This work hypothesizes that a ground-based array of infrasonic pressure transducers could be employed to estimate the vertical wind profile over a height relevant for wind turbines. To analyze this hypothesis, experiments and field deployments were conducted. Wind tunnel experiments were performed for a thick turbulent boundary layer over a neutral or heated surface. Surface pressure and velocity probe measurements were acquired simultaneously. Two field deployments yielded surface pressure data from a 49 element array. The second deployment at the Reese Technology Center in Lubbock, TX, also included data from a smaller aperture, 96-element array and a 200-meter tall meteorological tower. Analysis of the data successfully demonstrated the ability to estimate the vertical velocity profile using coherence data from the pressure array. Also, dynamical systems analysis methods were successful in identifying and tracking a gust type event. In addition to the passive acoustic profiling method, this program also investigated a rapid response Doppler SODAR system, the optimization of wind turbine blades for enhanced power with reduced aeroacoustic noise production, and the implementation of a wireless health monitoring system for the wind turbine blades. Each of these other objectives was met successfully. The use of phase unwrapping applied to SODAR data was found to yield reasonable results for per-pulse measurements. A health monitoring system design analysis was able to demonstrate the ability to use a very small number of sensors to monitor blade health based on the blade's overall structural modes. Most notable was the development of a multi-objective optimization methodology that successfully yielded an aerodynamic blade design that produces greater power output with reduced aerodynamic loading noise. This optimization method could be significant for future design work

    Conceptualizing control in everyday music listening: defining dominance

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    Mehrabian and Russell’s Pleasure-Arousal-Dominance model states that people’s interactions and interpretation of their surroundings result from variations in three factors – pleasure, arousal, and dominance. Applied to music, pleasure has been operationalized as how much a person likes the music heard, arousal as how arousing the person considers the music to be, and dominance as the person’s control over the music heard. However, conceptualizing dominance broadly as control means that the construct is not well defined. This research aimed to define the elements related to a listener’s desire for control over music encountered in everyday life. Participants residing in Australia and USA (N ¼ 590) completed an online questionnaire. An exploratory factor analysis of the quantitative items identified five components defining control over music listening: “being personally in charge”, “selection by other people”, “contextual control”, “playback variety”, and “no need for control”. A thematic analysis of open-ended responses indicated additional facets of control including mood regulation, emotional investment, and identity. While the quantitative findings reaffirm previous research, the qualitative findings indicate previous conceptualizations of the control dimension have been limited. These results contribute to our understanding of the model’s dominance component with regard to explaining everyday music listening

    Turing Patterns and Biological Explanation

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    Turing patterns are a class of minimal mathematical models that have been used to discover and conceptualize certain abstract features of early biological development. This paper examines a range of these minimal models in order to articulate and elaborate a philosophical analysis of their epistemic uses. It is argued that minimal mathematical models aid in structuring the epistemic practices of biology by providing precise descriptions of the quantitative relations between various features of the complex systems, generating novel predictions that can be compared with experimental data, promoting theory exploration, and acting as constitutive parts of empirically adequate explanations of naturally occurring phenomena, such as biological pattern formation. Focusing on the roles that minimal model explanations play in science motivates the adoption of a broader diachronic view of scientific explanation

    Smart Knowledge Capture for Developing Adaptive Management Systems

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    In this paper we describe how a welldesigned Spatial Decision Support System (SDSS) may facilitate initial (immediate) decision making, while establishing a robust foundation and framework for improving effectiveness over time as new data and knowledge becomes available. \u27Smart Knowledge Capture\u27 is a set of methods for rapidly developing a strong SDSS for adaptive management. We review some of the MIS tools used in Smart Knowledge Capture: multicriteria decision analysis (MCDA) tools, online surveys, online knowledge portals, ontology systems, and describe the architecture of an SDSS that stores and utilizes this knowledge. We illustrate these concepts using our recent work supporting the development of a revised desert tortoise recovery plan

    Fast non-iterative algorithm for 3D point-cloud holography

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    Recently developed iterative and deep learning-based approaches to computer-generated holography (CGH) have been shown to achieve high-quality photorealistic 3D images with spatial light modulators. However, such approaches remain overly cumbersome for patterning sparse collections of target points across a photoresponsive volume in applications including biological microscopy and material processing. Specifically, in addition to requiring heavy computation that cannot accommodate real-time operation in mobile or hardware-light settings, existing sampling-dependent 3D CGH methods preclude the ability to place target points with arbitrary precision, limiting accessible depths to a handful of planes. Accordingly, we present a non-iterative point cloud holography algorithm that employs fast deterministic calculations in order to efficiently allocate patches of SLM pixels to different target points in the 3D volume and spread the patterning of all points across multiple time frames. Compared to a matched-performance implementation of the iterative Gerchberg-Saxton algorithm, our algorithm's relative computation speed advantage was found to increase with SLM pixel count, exceeding 100,000x at 512x512 array format.Comment: 22 pages, 11 figures, manuscript and supplemen

    Buprenorphine versus morphine in paediatric acute pain: A systematic review and meta-analysis

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    Introduction: In lab-based studies, buprenorphine appears to have a ceiling effect on respiratory depression but not on analgesia. There is increasing evidence in adult patients that buprenorphine has no ceiling effect on analgesia or side effects. The aim of this study was to investigate the efficacy and adverse effects of buprenorphine versus morphine in paediatric acute pain. Methods: A systematic review of five databases was performed until May 2018. Only randomised controlled trials were eligible for inclusion. The outcomes of interest included pain, respiratory depression, nausea, sedation, dizziness, and pruritus. Results: Four randomized controlled trials (n = 195) were included. The only outcome measuring analgesic efficacy was time to breakthrough analgesia. Buprenorphine had a significant increase in time to breakthrough analgesia by 114.98 minutes compared to morphine (95% CI = 42.94 to 187.01; I2 = 0; p = 0.002). There was no significant difference in the rates of adverse effects. Conclusions: Buprenorphine provided a longer duration of analgesia than morphine. This in combination with its unique sublingual preparation could prove particularly advantageous in the paediatric population. The studies included are likely underpowered to detect differences in the incidence of adverse effects; therefore, the same precautions should be taken as with any other opioid

    Pregabalin effects on neural response to emotional faces

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    Pregabalin has shown promise in the treatment of anxiety disorders. Previous functional magnetic resonance imaging (fMRI) studies indicate agents used to treat anxiety, e.g., SSRIs and benzodiazepines, attenuate amygdala, insula, and medial prefrontal cortex (mPFC) activation during emotional processing. Our prior study has shown that during anticipation of an emotional stimulus, pregabalin attenuates amygdala and insula activation but increases medial PFC activation. In this study, we examined whether, similar to SSRIs and benzodiazepines, pregabalin attenuates amygdala, insula, and medial PFC during emotional face processing. Sixteen healthy volunteers underwent a double-blind within-subjects fMRI study investigating effects of placebo, 50 mg, and 200 mg pregabalin on neural activation during an emotional face-matching task. Linear mixed model analysis revealed that pregabalin dose-dependently attenuated left amygdala activation during fearful face-matching and left anterior insula activation during angry face-matching. The 50 mg dose exhibited more robust effects than the 200 mg dose in the right anterior insula and ventral ACC. Thus, pregabalin shares some similarity to SSRIs and benzodiazepines in attenuating anger and fear-related insula and amygdala activation during emotional face processing. However, there is evidence that a subclinical 50 mg dose of pregabalin produced more robust and widespread effects on neural responses in this paradigm than the more clinically relevant 200 mg dose. Taken together, pregabalin has a slightly different effect on brain activation as it relates to anticipation and emotional face processing, which may account for its unique characteristic as an agent for the treatment of anxiety disorders
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