Calibration Techniques

Sleep apnea is a sleep disorder in which breathing is briefly and repeatedly interrupted. Polysomnography (PSG) is the standard clinical test for diagnosing sleep apnea. However, it is expensive and time-consuming which requires hospital visits, specialized wearable sensors, professional installations, and long waiting lists. To address this problem, we design a smartwatch-based system called ApneaDetector, which exploits the built-in sensors in smartwatches to detect sleep apnea. Through a clinical study, we identify features of sleep apnea captured by smartwatch, which can be leveraged by machine learning techniques for sleep apnea detection. However, there are many technical challenges such as how to extract various special patterns from the noisy and multi-axis sensing data. To address these challenges, we propose signal denoising and data calibration techniques to process the noisy data while preserving the peaks and troughs which reflect the possible apnea events. We identify the characteristics of sleep apnea such as signal spikes which can be captured by smartwatch, and propose methods to extract proper features to train machine learning models for apnea detection. Through extensive experimental evaluations, we demonstrate that our system can detect apnea events with high precision (0.9674), recall (0.9625), and F1-score (0.9649).

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Reference fields and calibration techniques for Rn-220 measuring instruments

International Congress Series ◽

10.1016/j.ics.2004.09.020 ◽

2005 ◽

Vol 1276 ◽

pp. 85-88

Author(s):

E. Gargioni ◽

D. Arnold

Keyword(s):

Measuring Instruments ◽

Calibration Techniques ◽

Reference Fields

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The Low-Frequency Array (LOFAR): Opening a New Window on the Universe

Symposium - International Astronomical Union ◽

10.1017/s0074180900169591 ◽

2002 ◽

Vol 199 ◽

pp. 474-483

Author(s):

Namir E. Kassim ◽

T. Joseph W. Lazio ◽

William C. Erickson ◽

Patrick C. Crane ◽

R. A. Perley ◽

...

Keyword(s):

Angular Resolution ◽

Broad Band ◽

Low Frequency ◽

Electromagnetic Spectrum ◽

Interferometric Imaging ◽

Very Large Array ◽

Long Wavelength ◽

Calibration Techniques ◽

Long Baselines ◽

The Universe

Decametric wavelength imaging has been largely neglected in the quest for higher angular resolution because ionospheric structure limited interferometric imaging to short (< 5 km) baselines. The long wavelength (LW, 2—20 m or 15—150 MHz) portion of the electromagnetic spectrum thus remains poorly explored. The NRL-NRAO 74 MHz Very Large Array has demonstrated that self-calibration techniques can remove ionospheric distortions over arbitrarily long baselines. This has inspired the Low Frequency Array (LOFAR)—-a fully electronic, broad-band (15—150 MHz)antenna array which will provide an improvement of 2—3 orders of magnitude in resolution and sensitivity over the state of the art.

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Polarization calibration techniques and scheduling for the Daniel K. Inouye Solar Telescope

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315004603 ◽

2014 ◽

Vol 10 (S305) ◽

pp. 102-107

Author(s):

David F. Elmore

Keyword(s):

Advanced Technology ◽

Optical Coatings ◽

Calibration Error ◽

Solar Telescope ◽

Critical Importance ◽

Common Path ◽

Solar Research ◽

Telescope Optics ◽

The Individual ◽

Calibration Techniques

AbstractThe Daniel K. Inouye Solar Telescope (DKIST), formerly Advanced Technology Solar Telescope when it begins operation in 2019 will be by a significant margin Earth's largest solar research telescope. Science priorities dictate an initial suite of instruments that includes four spectro-polarimeters. Accurate polarization calibration of the individual instruments and of the telescope optics shared by those instruments is of critical importance. The telescope and instruments have been examined end-to-end for sources of polarization calibration error, allowable contributions from each of the sources quantified, and techniques identified for calibrating each of the contributors. Efficient use of telescope observing time leads to a requirement of sharing polarization calibrations of common path telescope components among the spectro-polarimeters and for those calibrations to be repeated only as often as dictated by degradation of optical coatings and instrument reconfigurations. As a consequence the polarization calibration of the DKIST is a facility function that requires facility wide techniques.

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