2,566 research outputs found

    IT Data Mining Tool Uses in Aerospace

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    Data mining has a broad spectrum of uses throughout the realms of aerospace and information technology. Each of these areas has useful methods for processing, distributing, and storing its corresponding data. This paper focuses on ways to leverage the data mining tools and resources used in NASA's information technology area to meet the similar data mining needs of aviation and aerospace domains. This paper details the searching, alerting, reporting, and application functionalities of the Splunk system, used by NASA's Security Operations Center (SOC), and their potential shared solutions to address aircraft and spacecraft flight and ground systems data mining requirements. This paper also touches on capacity and security requirements when addressing sizeable amounts of data across a large data infrastructure

    Self-Healing First-Order Distributed Optimization with Packet Loss

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    We describe SH-SVL, a parameterized family of first-order distributed optimization algorithms that enable a network of agents to collaboratively calculate a decision variable that minimizes the sum of cost functions at each agent. These algorithms are self-healing in that their convergence to the correct optimizer can be guaranteed even if they are initialized randomly, agents join or leave the network, or local cost functions change. We also present simulation evidence that our algorithms are self-healing in the case of dropped communication packets. Our algorithms are the first single-Laplacian methods for distributed convex optimization to exhibit all of these characteristics. We achieve self-healing by sacrificing internal stability, a fundamental trade-off for single-Laplacian methods.Comment: arXiv admin note: substantial text overlap with arXiv:2104.0195

    Self-Healing First-Order Distributed Optimization

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    In this paper we describe a parameterized family of first-order distributed optimization algorithms that enable a network of agents to collaboratively calculate a decision variable that minimizes the sum of cost functions at each agent. These algorithms are self-healing in that their correctness is guaranteed even if they are initialized randomly, agents drop in or out of the network, local cost functions change, or communication packets are dropped. Our algorithms are the first single-Laplacian methods to exhibit all of these characteristics. We achieve self-healing by sacrificing internal stability, a fundamental trade-off for single-Laplacian methods.Comment: Corrected equation (40) by changing "min" to "max", results unaffecte

    Human-Multirobot Collaborative Mobile Manipulation: the Omnid Mocobots

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    The Omnid human-collaborative mobile manipulators are an experimental platform for testing control architectures for autonomous and human-collaborative multirobot mobile manipulation. An Omnid consists of a mecanum-wheel omnidirectional mobile base and a series-elastic Delta-type parallel manipulator, and it is a specific implementation of a broader class of mobile collaborative robots ("mocobots") suitable for safe human co-manipulation of delicate, flexible, and articulated payloads. Key features of mocobots include passive compliance, for the safety of the human and the payload, and high-fidelity end-effector force control independent of the potentially imprecise motions of the mobile base. We describe general considerations for the design of teams of mocobots; the design of the Omnids in light of these considerations; manipulator and mobile base controllers to achieve useful multirobot collaborative behaviors; and initial experiments in human-multirobot collaborative mobile manipulation of large, unwieldy payloads. For these experiments, the only communication among the humans and Omnids is mechanical, through the payload.Comment: 8 pages, 10 figures. Videos available at https://www.youtube.com/watch?v=SEuFfONryL0. Submitted to IEEE Robotics and Automation Letters (RA-L

    Isometric handgrip (IHG) training-induced reductions in resting blood pressure: Reactivity to a 2-minute handgrip task identifies responders and non-responders in young normotensive individuals

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    In people with hypertension, systolic blood pressure (SBP) reactivity to an isometric handgrip task (IHGT), but not a cold pressure task (CPT), is predictive of IHG training-induced reductions in resting SBP. To investigate whether these findings could be extended to include young normotensives, resting BP and BP reactivity to an IHGT (2-minute sustained contraction at 30% maximal voluntary contraction, MVC) and a CPT (2-minute hand immersion in a cold water bath) were measured prior to and following 10 weeks of IHG training (4, 2-minute IHG contractions at 30% MVC, using alternating hands, interspersed with 1-minute rest periods, 3X/week) in 7 normotensive individuals (3 females, 4 males; age=25 ± 5.7 years). BP reactivity was derived by calculating the difference between peak stress BP and mean baseline resting BP. Significant training-induced reductions in resting SBP (p<0.001) were strongly correlated with pre-training SBP reactivity to the IHGT (r=-0.8, p=0.03), but not the CPT (r= 0.2, p=0.6). These preliminary findings suggest that SBP reactivity to a short and simple handgrip task can be used as a predictive tool to identify who will respond best to IHG training. It might be possible to further explore how the IHG training stimulus could be optimized in non-responders, to ensure that they too, experience reductions in resting BP

    A Scientific Basis for Erosion and Sedimentation Standards in the Blue Ridge Physiographic Province

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    Proceedings of the 1999 Georgia Water Resources Conference, March 30 and 31, Athens, Georgia.Excessive sedimentation is a threat to riverine ecosystems in the southern Appalachians. We sampled fish and suspended sediments in ten tributaries of the Etowah and Little Tennessee rivers. Sampling sites varied in the extent of sedimentation and could be separated into low and high turbidity streams. Based on differences in fish assemblages in these two stream types, the following standards would protect fishes in the Blue Ridge physiographic province: Turbidity values in stream water sampled during base flow conditions should not exceed 15 NTU, and turbidity should exceed 10 NTU in only one out of five stream water samples collected during base flow conditions. Base flow turbidity values in excess of these indicate excess sedimentation that threatens the integrity of southern Appalachian fish assemblagesSponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, The University of Georgia, Georgia State University, Georgia Institute of TechnologyThis book was published by the Institute of Ecology, The University of Georgia, Athens, Georgia 30602-2202 with partial funding provided by the U.S. Department of Interior, geological Survey, through the Georgia Water Research Insttitute as authorized by the Water Research Institutes Authorization Act of 1990 (P.L. 101-397). The views and statements advanced in this publication are solely those of the authors and do not represent official views or policies of the University of Georgia or the U.S. Geological Survey or the conference sponsors

    Validity, cut-points, and minimally important differences for two hot flash-related daily interference scales

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    OBJECTIVES: To conduct psychometric analyses to condense the Hot Flash-Related Daily Interference Scale (HFRDIS) into a shorter form termed the Hot Flash Interference (HFI) scale; evaluate cut-points for both scales; and establish minimally important differences (MIDs) for both scales. METHODS: We analyzed baseline and postrandomization patient-reported data pooled across three randomized trials aimed at reducing vasomotor symptoms (VMS) in 899 midlife women. Trials were conducted across five MsFLASH clinical sites between July 2009 and October 2012. We eliminated HFRDIS items based on experts' content validity ratings and confirmatory factor analysis, and evaluated cut-points and established MIDs by mapping HFRDIS and HFI to other measures. RESULTS: The three-item HFI (interference with sleep, mood, and concentration) demonstrated strong internal consistency (alphas of 0.830 and 0.856), showed good fit to the unidimensional "hot flash interference factor," and strong convergent validity with HFRDIS scores, diary VMS, and menopausal quality of life. For both scales, cut-points of mild (0-3.9), moderate (4-6.9), and severe (7-10) interference were associated with increasing diary VMS ratings, sleep, and anxiety. The average MID was 1.66 for the HFRDIS and 2.34 for the HFI. CONCLUSIONS: The HFI is a brief assessment of VMS interference and will be useful in busy clinics to standardize VMS assessment or in research studies where response burden may be an issue. The scale cut-points and MIDs should prove useful in targeting those most in need of treatment, monitoring treatment response, and interpreting existing and future research findings
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