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Noise Cancellation

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https://www.readbyqxmd.com/read/28098201/fiber-laser-based-ultrasound-sensor-for-photoacoustic-imaging
#1
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
#2
Miguel Arevalillo-Herraez, Maximo Cobos, Miguel Garcia Pineda
In this paper, we present an effective algorithm to reduce the number of wraps in a two-dimensional (2-D) phase signal provided as input. The technique is based on an accurate estimate of the fundamental frequency of a 2-D 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...
January 10, 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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
https://www.readbyqxmd.com/read/27906225/rf-subcarrier-assisted-four-state-continuous-variable-qkd-based-on-coherent-detection
#14
Zhen Qu, Ivan B Djordjevic, Mark A Neifeld
We theoretically investigate and experimentally demonstrate a RF-assisted four-state continuous-variable quantum key distribution (CV-QKD) system. Classical coherent detection is implemented with a simple digital phase noise cancelation scheme. In the proposed system, there is no need for frequency and phase locking between the quantum signals and the local oscillator laser. Moreover, in principle, there is no residual phase noise, and a mean excess noise of 0.0115 (in shot-noise units) can be acquired experimentally...
December 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27893403/real-time-robust-heart-rate-estimation-from-wrist-type-ppg-signals-using-multiple-reference-adaptive-noise-cancellation
#15
Sayeed Chowdhury, Rakib Hyder, Md Samzid Hafiz, Mohammad Ariful Haque
No abstract text is available yet for this article.
November 23, 2016: IEEE Journal of Biomedical and Health Informatics
https://www.readbyqxmd.com/read/27835830/a-feed-forward-adaptive-canceller-to-reduce-the-occlusion-effect-in-hearing-aids
#16
Renata Coelho Borges, Márcio Holsbach Costa
Hearing aids are essential devices for social integration of hearing impaired people in order to improve their auditory perception. Recent studies have reported significant dissatisfaction factors that tend to reduce their daily use. The occlusion effect is one important source of complaints. This phenomenon stems from the partial or complete closure of the ventilation opening of the ear-mould, usually performed to prevent feedback effects in high-gain devices. This work presents a new adaptive active-noise-control system to reduce the occlusion effect in small- or unvented hearing aids...
October 18, 2016: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/27834661/an-extended-bayesian-framework-for-atrial-and-ventricular-activity-separation-in-atrial-fibrillation
#17
Ebadollah Kheirati Roonizi, Roberto Sassi
An extended nonlinear Bayesian filtering framework is introduced for the analysis of Atrial Fibrillation (AF), in particular with single channel electrocardiographical (ECG) recordings. It is suitable for simultaneously tracking the fundamental frequency of atrial fibrillatory waves (f-waves), and separating signals, linked to atrial and ventricular activity, during AF. In this framework, high-power ECG components, i.e. Q, R, S and T waves, are modeled using sum of Gaussian functions. The atrial activity dynamical model is instead based on a trigonometrical function, with a fundamental frequency (the inverse of the dominant atrial cycle length), and its harmonics...
November 4, 2016: IEEE Journal of Biomedical and Health Informatics
https://www.readbyqxmd.com/read/27829731/dynamic-thermal-acoustic-response-for-human-bone-materials-at-different-energy-levels-a-diagnosis-approach
#18
Ashok Kumar Thella, James Rizkalla, Neeraj Rathi, Monika Kakani, Ahdy Helmy, Paul Salama, Maher E Rizkalla
BACKGROUND: The non-invasive diagnostic approaches have gained high attention in recent years, utilizing high technology sensor systems, including infrared, microwave devices, acoustic transducers, etc. The patient safety, high resolution images, and reliability are among the driving forces toward high technology approaches. The thermal and acoustic responses of the materials may reflect the important research parameters such as penetration depth, power consumption, and temperature change used for the practical models of the system...
March 2017: Journal of Orthopaedics
https://www.readbyqxmd.com/read/27771537/temporal-distortion-in-the-perception-of-actions-and-events
#19
Yoshiko Yabe, Hemangi Dave, Melvyn A Goodale
In everyday life, actions and sensory events occur in complex sequences, with events triggering actions that in turn give rise to additional events and so on. Earlier work has shown that a sensory event that is triggered by a voluntary action is perceived to have occurred earlier in time than an identical event that is not triggered by an action. In other words, events that are believed to be caused by our actions are drawn forward in time towards our actions. Similarly, when a sensory event triggers an action, that event is again drawn in time towards the action and is thus perceived to have occurred later than it really did...
October 20, 2016: Cognition
https://www.readbyqxmd.com/read/27698261/a-binaural-grouping-model-for-predicting-speech-intelligibility-in-multitalker-environments
#20
Jing Mi, H Steven Colburn
Spatially separating speech maskers from target speech often leads to a large intelligibility improvement. Modeling this phenomenon has long been of interest to binaural-hearing researchers for uncovering brain mechanisms and for improving signal-processing algorithms in hearing-assistive devices. Much of the previous binaural modeling work focused on the unmasking enabled by binaural cues at the periphery, and little quantitative modeling has been directed toward the grouping or source-separation benefits of binaural processing...
October 3, 2016: Trends in Hearing
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