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  • Other Sources  (121)
  • 2015-2019  (56)
  • 2010-2014  (65)
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  • 1
    Publication Date: 2019-07-27
    Description: A remaining useful life prediction methodology for electrolytic capacitors is presented. This methodology is based on the Kalman filter framework and an empirical degradation model. Electrolytic capacitors are used in several applications ranging from power supplies on critical avionics equipment to power drivers for electro-mechanical actuators. These devices are known for their comparatively low reliability and given their criticality in electronics subsystems they are a good candidate for component level prognostics and health management. Prognostics provides a way to assess remaining useful life of a capacitor based on its current state of health and its anticipated future usage and operational conditions. We present here also, experimental results of an accelerated aging test under electrical stresses. The data obtained in this test form the basis for a remaining life prediction algorithm where a model of the degradation process is suggested. This preliminary remaining life prediction algorithm serves as a demonstration of how prognostics methodologies could be used for electrolytic capacitors. In addition, the use degradation progression data from accelerated aging, provides an avenue for validation of applications of the Kalman filter based prognostics methods typically used for remaining useful life predictions in other applications.
    Keywords: Electronics and Electrical Engineering
    Type: ARC-E-DAA-TN3987 , Annual Conference of the PHM Society 2011; 25-29 Sept. 2011; Montreal/Canada; United States
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  • 2
    Publication Date: 2019-07-19
    Description: The Hurricane Imaging Radiometer (HIRAD) is a new airborne passive microwave synthetic aperture radiometer designed to provide wide swath images of ocean surface wind speed under heavy precipitation and, in particular, in tropical cyclones. It operates at 4, 5, 6 and 6.6 GHz and uses interferometric signal processing to synthesize a pushbroom imager in software from a low profile planar antenna with no mechanical scanning. HIRAD participated in NASA s Genesis and Rapid Intensification Processes (GRIP) mission during Fall 2010 as its first science field campaign. HIRAD produced images of upwelling brightness temperature over a aprox 70 km swath width with approx 3 km spatial resolution. From this, ocean surface wind speed and column averaged atmospheric liquid water content can be retrieved across the swath. The calibration and image reconstruction algorithms that were used to verify HIRAD functional performance during and immediately after GRIP were only preliminary and used a number of simplifying assumptions and approximations about the instrument design and performance. The development and performance of a more detailed and complete set of algorithms are reported here.
    Keywords: Instrumentation and Photography
    Type: M12-1543 , 32nd Annual International Geoscience & Remote Sensing Symposium (IGARSS); Jul 22, 2012 - Jul 27, 2012; Munich; Germany
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  • 3
    Publication Date: 2019-07-20
    Description: An increase in the efficiency of sampling from Boltzmann distributions would have a significant impact in deep learning and other machine learning applications. Recently, quantum annealers have been proposed as a potential candidate to speed up this task, but several limitations still bar these state-of-the-art technologies from being used effectively. One of the main limitations is that, while the device may indeed sample from a Boltzmann-like distribution, quantum dynamical arguments suggests it will do so with an instance-dependent effective temperature, different from the physical temperature of the device. Unless this unknown temperature can be unveiled, it might not be possible to effectively use a quantum annealer for Boltzmann sampling. In this talk, we present a strategy to overcome this challenge with a simple effective-temperature estimation algorithm. We provide a systematic study assessing the impact of the effective temperatures in the learning of a kind of restricted Boltzmann machine embedded on quantum hardware, which can serve as a building block for deep learning architectures. We also provide a comparison to k-step contrastive divergence (CD-k) with k up to 100. Although assuming a suitable fixed effective temperature also allows to outperform one step contrastive divergence (CD-1), only when using an instance-dependent effective temperature we find a performance close to that of CD-100 for the case studied here. We discuss generalizations of the algorithm to other more expressive generative models, beyond restricted Boltzmann machines.
    Keywords: Physics (General)
    Type: ARC-E-DAA-TN35141 , Workshop on Theory and Practice of Adiabatic Quantum Computers and Quantum Simulation; Aug 22, 2016 - Aug 26, 2016; Trieste; Italy
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  • 4
    Publication Date: 2019-07-20
    Description: Spacecraft carrying optical communication lasers can be treated as artificial stars, whose relative astrometry to Gaia reference stars provides spacecraft positions in the plane-of-sky for optical navigation. To be comparable to current Deep Space Network delta-Differential One-way Ranging measurements, thus sufficient for navigation, nanoradian optical astrometry is required. Here we describe our error budget, techniques for achieving nanoradian level ground-base astrometry, and preliminary results from a 1 m telescope. We discuss also how these spacecraft may serve as artificial reference stars for adaptive optics, high precision astrometry to detect exoplanets, and tying reference frames defined by radio and optical measurements.
    Keywords: Lunar and Planetary Science and Exploration; Lasers and Masers
    Type: JPL-CL-16-3153 , SPIE Astronomical Telescopes + Instrumentation 2016; Jun 26, 2016 - Jul 01, 2016; Edinburgh, Scotland; United Kingdom
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  • 5
    Publication Date: 2019-07-19
    Description: The Hurricane Imaging Radiometer (HIRAD) is an experimental C-band passive microwave radiometer designed to map the horizontal structure of surface wind speed fields in hurricanes. New data processing and customized retrieval approaches were developed after the 2015 Tropical Cyclone Intensity (TCI) experiment, which featured flights over Hurricanes Patricia, Joaquin, Marty, and the remnants of Tropical Storm Erika. These new approaches produced maps of surface wind speed that looked more realistic than those from previous campaigns. Dropsondes from the High Definition Sounding System (HDSS) that was flown with HIRAD on a WB-57 high altitude aircraft in TCI were used to assess the quality of the HIRAD wind speed retrievals. The root mean square difference between HIRAD-retrieved surface wind speeds and dropsonde-estimated surface wind speeds was 6.0 meters per second. The largest differences between HIRAD and dropsonde winds were from data points where storm motion during dropsonde descent compromised the validity of the comparisons. Accounting for this and for uncertainty in the dropsonde measurements themselves, we estimate the root mean square error for the HIRAD retrievals as around 4.7 meters per second. Prior to the 2015 TCI experiment, HIRAD had previously flown on the WB-57 for missions across Hurricanes Gonzalo (2014), Earl (2010), and Karl (2010). Configuration of the instrument was not identical to the 2015 flights, but the methods devised after the 2015 flights may be applied to that previous data in an attempt to improve retrievals from those cases.
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN48243 , Conference on Hurricanes and Tropical Meteorology; Apr 16, 2018 - Apr 20, 2018; Ponte Vedra, FL; United States
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  • 6
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN21161 , Interdepartmental Hurricane Conference; Mar 02, 2015 - Mar 05, 2015; Jacksonville, FL; United States
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  • 7
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: M14-3556 , Microwave Radiometry and Remote Sensing of the Environment (MicroRad 2014); Mar 24, 2014 - Mar 27, 2014; Pasadena, CA; United States
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  • 8
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: M14-3553 , HS3/HSRP Science Team Meeting; Apr 29, 2014 - May 01, 2014; Moffett Field, CA; United States
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  • 9
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Meteorology and Climatology; Instrumentation and Photography
    Type: M14-3552 , Conference on Hurricanes and Tropical Meteorology; Mar 30, 2014 - Apr 04, 2014; San Diego, CA; United States
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  • 10
    Publication Date: 2019-07-13
    Description: This paper discusses experimental setups for health monitoring and prognostics of electrolytic capacitors under nominal operation and accelerated aging conditions. Electrolytic capacitors have higher failure rates than other components in electronic systems like power drives, power converters etc. Our current work focuses on developing first-principles-based degradation models for electrolytic capacitors under varying electrical and thermal stress conditions. Prognostics and health management for electronic systems aims to predict the onset of faults, study causes for system degradation, and accurately compute remaining useful life. Accelerated life test methods are often used in prognostics research as a way to model multiple causes and assess the effects of the degradation process through time. It also allows for the identification and study of different failure mechanisms and their relationships under different operating conditions. Experiments are designed for aging of the capacitors such that the degradation pattern induced by the aging can be monitored and analyzed. Experimental setups and data collection methods are presented to demonstrate this approach.
    Keywords: Quality Assurance and Reliability; Electronics and Electrical Engineering
    Type: ARC-E-DAA-TN5745 , IEEE Autotestcon; Sep 10, 2012 - Sep 13, 2012; Anaheim, CA; United States
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