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Noise Cancellation

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https://www.readbyqxmd.com/read/28227848/motion-noise-cancellation-in-seismocardiogram-of-ambulant-subjects-with-dual-sensors
#1
Chenxi Yang, Negar Tavassolian, Chenxi Yang, Negar Tavassolian, Negar Tavassolian, Chenxi Yang
This paper presents a dual-sensor method of extracting seismocardiographic (SCG) data from moving adult subjects using chest-worn wireless MEMS accelerometers. A digital signal processing (DSP) system including a normalized least means square (NLMS) adaptive filter is designed and tested in MATLAB. Data results from 10 subjects indicate a detection rate of 98.72% which outperforms our previously-proposed single-sensor scheme. Various sensor positons and possible failure mechanisms are also investigated to further evaluate the system performance...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226487/asynchronous-noise-removal-for-earbud-based-ppg-sensors
#2
Yohei Tomita, Yohei Tomita, Yohei Tomita
This paper addresses motion noise removal for an earbud-based reflective photoplethysmographic (PPG) sensor. This system can be worn comfortably on the ear for a long time. However, body movements such as walking and running cause signal degradation. To improve signal quality, I propose a novel asynchronous noise removal method using only the right and left PPG signals. It cancels not only uncorrelated noise components but also asynchronous noise components by simply introducing a weight function in the calculation process of a Wiener filter...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28179732/a-microfabricated-optically-pumped-magnetic-gradiometer
#3
D Sheng, A R Perry, S P Krzyzewski, S Geller, J Kitching, S Knappe
We report on the development of a microfabricated atomic magnetic gradiometer based on optical spectroscopy of alkali atoms in the vapor phase. The gradiometer, which operates in the spin-exchange relaxation free regime, has a length of 60 mm and cross sectional diameter of 12 mm, and consists of two chip-scale atomic magnetometers which are interrogated by a common laser light. The sensor can measure differences in magnetic fields, over a 20 mm baseline, of 10 fT/[Formula: see text] at frequencies above 20 Hz...
January 16, 2017: Applied Physics Letters
https://www.readbyqxmd.com/read/28177299/development-of-an-improved-wearable-device-for-core-body-temperature-monitoring-based-on-the-dual-heat-flux-principle
#4
Jingjie Feng, Congcong Zhou, Cheng He, Yuan Li, Xuesong Ye
In this paper, a miniaturized wearable core body temperature (CBT) monitoring system based on the dual heat flux (DHF) principle was developed. By interspersing calcium carbonate powder in PolyDimethylsiloxane (PDMS), a reformative heat transfer medium was produced to reduce the thermal equilibrium time. Besides, a least mean square (LMS) algorithm based active noise cancellation (ANC) method was adopted to diminish the impact of ambient temperature fluctuations. Theoretical analyses, finite element simulation, experiments on a hot plate and human volunteers were performed...
February 8, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28174614/weak-electric-fields-detectability-in-a-noisy-neural-network
#5
Jia Zhao, Bin Deng, Yingmei Qin, Cong Men, Jiang Wang, Xile Wei, Jianbing Sun
We investigate the detectability of weak electric field in a noisy neural network based on Izhikevich neuron model systematically. The neural network is composed of excitatory and inhibitory neurons with similar ratio as that in the mammalian neocortex, and the axonal conduction delays between neurons are also considered. It is found that the noise intensity can modulate the detectability of weak electric field. Stochastic resonance (SR) phenomenon induced by white noise is observed when the weak electric field is added to the network...
February 2017: Cognitive Neurodynamics
https://www.readbyqxmd.com/read/28158119/development-of-a-compact-optical-absolute-frequency-reference-for-space-with-10-sup-15-sup-instability
#6
Thilo Schuldt, Klaus Döringshoff, Evgeny V Kovalchuk, Anja Keetman, Julia Pahl, Achim Peters, Claus Braxmaier
We report on a compact and ruggedized setup for laser frequency stabilization employing Doppler-free spectroscopy of molecular iodine near 532 nm. Using a 30 cm long iodine cell in a triple-pass configuration in combination with noise-canceling detection and residual amplitude modulation control, a frequency instability of 6×10<sup>-15</sup> at 1 s integration time and a Flicker noise floor below 3×10<sup>-15</sup> for integration times between 100 and 1000 s was found. A specific assembly-integration technology was applied for the realization of the spectroscopy setup, ensuring high beam pointing stability and high thermal and mechanical rigidity...
February 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28125160/design-of-high-quality-chemical-xor-gates-with-noise-reduction
#7
Mackenna L Wood, Sergii Domanskyi, Vladimir Privman
We describe a chemical XOR gate design that realizes gate-response function with filtering properties. Such gate-response function is flat (has small gradients) at and in the vicinity of all the four binary-input logic points, resulting in analog noise suppression. The gate functioning involves cross-reaction of the inputs represented by pairs of chemicals to produce a practically zero output when both are present and nearly equal. This cross-reaction processing step is also designed to result in filtering at low output intensities by canceling out the inputs if one of the latter has low intensity as compared to the other...
January 26, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28098201/fiber-laser-based-ultrasound-sensor-for-photoacoustic-imaging
#8
Yizhi Liang, Long Jin, Lidai Wang, Xue Bai, Linghao Cheng, Bai-Ou Guan
Photoacoustic imaging, especially for intravascular and endoscopic applications, requires ultrasound probes with miniature size and high sensitivity. In this paper, we present a new photoacoustic sensor based on a small-sized fiber laser. Incident ultrasound waves exert pressures on the optical fiber laser and induce harmonic vibrations of the fiber, which is detected by the frequency shift of the beating signal between the two orthogonal polarization modes in the fiber laser. This ultrasound sensor presents a noise-equivalent pressure of 40 Pa over a 50-MHz bandwidth...
January 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28092543/a-robust-wrap-reduction-algorithm-for-fringe-projection-profilometry-and-applications-in-magnetic-resonance-imaging
#9
Miguel Arevalillo-Herraez, Maximo Cobos, Miguel Garcia-Pineda
In this paper, we present an effective algorithm to reduce the number of wraps in a 2D phase signal provided as input. The technique is based on an accurate estimate of the fundamental frequency of a 2D complex signal with the phase given by the input, and the removal of a dependent additive term from the phase map. Unlike existing methods based on the discrete Fourier transform (DFT), the frequency is computed by using noise-robust estimates that are not restricted to integer values. Then, to deal with the problem of a non-integer shift in the frequency domain, an equivalent operation is carried out on the original phase signal...
March 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28059760/volcanic-tremor-and-plume-height-hysteresis-from-pavlof-volcano-alaska
#10
David Fee, Matthew M Haney, Robin S Matoza, Alexa R Eaton, Peter Cervelli, David J Schneider, Alexandra M Iezzi
The March 2016 eruption of Pavlof Volcano, Alaska, produced an ash plume that caused the cancellation of more than 100 flights in North America. The eruption generated strong tremor that was recorded by seismic and remote low-frequency acoustic (infrasound) stations, including the EarthScope Transportable Array. The relationship between the tremor amplitudes and plume height changes considerably between the waxing and waning portions of the eruption. Similar hysteresis has been observed between seismic river noise and discharge during storms, suggesting that flow and erosional processes in both rivers and volcanoes can produce irreversible structural changes that are detectable in geophysical data...
January 6, 2017: Science
https://www.readbyqxmd.com/read/28055986/robust-heart-rate-estimation-using-wrist-type-photoplethysmographic-signals-during-physical-exercise-an-approach-based-on-adaptive-filtering
#11
Sibylle Fallet, Jean-Marc Vesin
Photoplethysmographic (PPG) signals are easily corrupted by motion artifacts when the subjects perform physical exercise. This paper introduces a two-step processing scheme to estimate heart rate (HR) from wrist-type PPG signals strongly corrupted by motion artifacts. Adaptive noise cancellation, using normalized least-mean-square algorithm, is first performed to attenuate motion artifacts and reconstruct multiple PPG waveforms from different combinations of corrupted PPG waveforms and accelerometer data. An adaptive band-pass filter is then used to track the common instantaneous frequency component (i...
January 5, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28047845/we-ab-207a-01-best-in-physics-imaging-high-resolution-cone-beam-ct-of-the-extremities-and-cancellous-bone-architecture-with-a-cmos-detector
#12
Q Cao, M Brehler, A Sisniega, E Marinetto, A Zyazin, I Peters, J Stayman, J Yorkston, J Siewerdsen, W Zbijewski
PURPOSE: Extremity cone-beam CT (CBCT) with an amorphous silicon (aSi) flat-panel detector (FPD) provides low-dose volumetric imaging with high spatial resolution. We investigate the performance of the newer complementary metal-oxide semiconductor (CMOS) detectors to enhance resolution of extremities CBCT to ∼0.1 mm, enabling morphological analysis of trabecular bone. Quantitative in-vivo imaging of bone microarchitecture could present an important advance for osteoporosis and osteoarthritis diagnosis and therapy assessment...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28040042/multichannel-active-noise-control-for-spatially-sparse-noise-fields
#13
Jihui Zhang, Thushara D Abhayapala, Prasanga N Samarasinghe, Wen Zhang, Shouda Jiang
Multi-channel active noise control (ANC) is currently an attractive solution for the attenuation of low-frequency noise fields, in three-dimensional space. This paper develops a controller for the case when the noise source components are sparsely distributed in space. The anti-noise signals are designed as in conventional ANC to minimize the residual errors but with an additional term containing an ℓl norm regularization applied to the signal magnitude. This results in that only secondary sources close to the noise sources are required to be active for cancellation of sparse noise fields...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28030519/incorporating-a-computerized-cognitive-battery-into-the-emergency-department-care-of-pediatric-mild-traumatic-brain-injuries-is-it-feasible
#14
Aneesh M Khetani, Brian L Brooks, Angelo Mikrogianakis, Karen M Barlow
OBJECTIVES: The use of computers to test cognitive function acutely after a concussion is becoming increasingly popular, especially after sport-related concussion. Although commonly performed in the community, it is not yet performed routinely in the emergency department (ED), where most injured children present. The challenges of performing computerized cognitive testing (CCT) in a busy ED are considerable. The aim of this study was to evaluate the feasibility of CCT in the pediatric ED after concussion...
December 28, 2016: Pediatric Emergency Care
https://www.readbyqxmd.com/read/28025906/accuracy-of-mobile-based-audiometry-in-the-evaluation-of-hearing-loss-in-quiet-and-noisy-environments
#15
Joe Saliba, Mahmoud Al-Reefi, Junie S Carriere, Neil Verma, Christiane Provencal, Jamie M Rappaport
Objectives (1) To compare the accuracy of 2 previously validated mobile-based hearing tests in determining pure tone thresholds and screening for hearing loss. (2) To determine the accuracy of mobile audiometry in noisy environments through noise reduction strategies. Study Design Prospective clinical study. Setting Tertiary hospital. Subjects and Methods Thirty-three adults with or without hearing loss were tested (mean age, 49.7 years; women, 42.4%). Air conduction thresholds measured as pure tone average and at individual frequencies were assessed by conventional audiogram and by 2 audiometric applications (consumer and professional) on a tablet device...
December 1, 2016: Otolaryngology—Head and Neck Surgery
https://www.readbyqxmd.com/read/27973486/multi-access-fiber-optic-radio-frequency-transfer-with-passive-phase-noise-compensation
#16
Hongwei Li, Guiling Wu, Jiapeng Zhang, Jianguo Shen, Jianping Chen
In this Letter, we propose and demonstrate a multi-access fiber-optic radio frequency dissemination with passive phase noise cancelation. A forward phase-conjugated signal is generated at the local site by frequency mixing between the standard signal and the round-trip probe signal. A stable frequency signal is achieved by frequency mixing the tapped forward phase-conjugated signal and the backward probe signal at an arbitrary point along the fiber link. Different wavelengths for forward and backward directions are employed to efficiently suppress the effect of backscattering...
December 15, 2016: Optics Letters
https://www.readbyqxmd.com/read/27927145/the-razor-s-edge-australian-rock-music-impairs-men-s-performance-when-pretending-to-be-a-surgeon
#17
Daisy Fancourt, Thomas Mw Burton, Aaron Williamon
OBJECTIVE: Over the past few decades there has been interest in the role of music in the operating theatre. However, despite many reported benefits, a number of potentially harmful effects of music have been identified. This study aimed to explore the effects of rock and classical music on surgical speed, accuracy and perceived distraction when performing multiorgan resection in the board game Operation. DESIGN: Single-blind, three-arm, randomised controlled trial...
December 12, 2016: Medical Journal of Australia
https://www.readbyqxmd.com/read/27917558/multivariate-sexual-selection-on-male-tegmina-in-wild-populations-of-sagebrush-crickets-cyphoderris-strepitans-orthoptera-haglidae
#18
G D Ower, J Hunt, S K Sakaluk
Although the strength and form of sexual selection on song in male crickets have been studied extensively, few studies have examined selection on the morphological structures that underlie variation in males' song, particularly in wild populations. Geometric morphometric techniques were used to measure sexual selection on the shape, size and symmetry of both top and bottom tegmina in wild populations of sagebrush crickets, a species in which nuptial feeding by females imposes an unambiguous phenotypic marker on males...
November 7, 2016: Journal of Evolutionary Biology
https://www.readbyqxmd.com/read/27914395/active-control-of-scattered-acoustic-fields-cancellation-reproduction-and-cloaking
#19
Jordan Cheer
The active control of sound fields has been widely applied in both active noise control and sound field reproduction, however, relatively few studies have focused on active acoustic cloaking. In order to build upon the knowledge and understanding in the areas of active noise control and sound field reproduction, this paper investigates the corresponding physical limitations and compares them to the active cloaking problem when the three strategies are employed in the presence of an acoustic scatterer. The three sound field control strategies have been formulated within a consistent framework, and this has enabled insight into the physical control mechanisms...
September 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27908076/experimental-observation-of-piezoelectric-effect-in-cancellous-bone-generated-by-ultrasound-irradiation
#20
A Hosokawa
In this study, piezoelectric cells (PE-cells) of cancellous bone were experimentally produced to receive an ultrasound wave. In the PE-cell, a bovine cancellous bone specimen, in which the pore spaces were saturated with air, was electrically shielded to prevent electromagnetic noise. As a result, the piezoelectric signal generated in the cancellous bone specimen by irradiating an ultrasound burst wave at 1.0 MHz could be clearly observed in water. The experimental results showed that the ultrasound sensitivity per unit area of cancellous bone was estimated to be below 1/100 and 1/100 000 of cortical bone and poly(vinylidene fluoride), respectively...
November 2016: Journal of the Acoustical Society of America
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