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Noise Cancellation

Hui Liu, Gregory Gredat, Syamsundar De, Ihsan Fsaifes, Aliou Ly, Rémy Vatré, Ghaya Baili, Sophie Bouchoule, Fabienne Goldfarb, Fabien Bretenaker
An ultra-low intensity and beatnote phase noise dual-frequency vertical-external-cavity surface-emitting laser is built at telecom wavelength. The pump laser is realized by polarization combining two single-mode fibered laser diodes in a single-mode fiber, leading to a 100% in-phase correlation of the pump noises for the two modes. The relative intensity noise is lower than -140  dB/Hz, and the beatnote phase noise is suppressed by 30 dB, getting close to the spontaneous emission limit. The role of the imperfect cancellation of the thermal effect resulting from unbalanced pumping of the two modes in the residual phase noise is evidenced...
April 15, 2018: Optics Letters
B Rauf, M C Vélez López, P Thoumany, M Pizzocaro, D Calonico
The distribution of ultra-narrow linewidth laser radiation is an integral part of many challenging metrological applications. Changes in the optical pathlength induced by environmental disturbances compromise the stability and accuracy of optical fibre networks distributing the laser light and call for active phase noise cancellation. Here we present a laboratory scale optical (at 578 nm) fibre network featuring all polarisation maintaining fibres in a setup with low optical powers available and tracking voltage-controlled oscillators implemented...
March 2018: Review of Scientific Instruments
Xiaofeng Yi, Jian Zhang, Tiehu Fan, Baofeng Tian, Chuandong Jiang
Magnetic resonance sounding (MRS) is a novel geophysical method to detect groundwater directly. By applying this method to underground projects in mines and tunnels, warning information can be provided on water bodies that are hidden in front prior to excavation and thus reduce the risk of casualties and accidents. However, unlike its application to ground surfaces, the application of MRS to underground environments is constrained by the narrow space, quite weak MRS signal, and complex electromagnetic interferences with high intensities in mines...
March 13, 2018: Sensors
Jokhakar Jignesh, Arthur Lowery, Bill Corcoran
We propose optical injection locking (OIL) to enable compensation of the inter-channel nonlinear phase noise, which is dominated by cross-phase modulation (XPM). In this paper, injection locking is used to create a local oscillator for a homodyne receiver from a residual carrier. The locking is fast enough to follow XPM-phase distortion, but slow enough to reject the signal bands, which are spaced slightly away from the pilot. The homodyne receiver thus partially cancels XPM, as it is common to the signals and the pilot...
March 5, 2018: Optics Express
Kevin Audo, Mehdi Alouini
An absorption mechanism based on second-harmonic generation (SHG) is successfully implemented as a buffer reservoir in a solid-state Er,Yb:Glass laser emitting at the telecom wavelength. We show that a slight absorption mechanism based on SHG rate conversion of 0.016% using a beta barium borate crystal enables the canceling out of the excess intensity noise at the relaxation oscillation frequency, i.e., 35 dB reduction, as well as canceling the amplified spontaneous emission beating at the free spectral range resonances of the laser lying in the gigahertz range...
March 1, 2018: Applied Optics
Mohammad Tariqul Islam, Sk Tanvir Ahmed, Ishmam Zabir, Celia Shahnaz, Shaikh Anowarul Fattah
Photoplethysmographic (PPG) signal is getting popularity for monitoring heart rate in wearable devices because of simplicity of construction and low cost of the sensor. The task becomes very difficult due to the presence of various motion artefacts. In this study, an algorithm based on cascade and parallel combination (CPC) of adaptive filters is proposed in order to reduce the effect of motion artefacts. First, preliminary noise reduction is performed by averaging two channel PPG signals. Next in order to reduce the effect of motion artefacts, a cascaded filter structure consisting of three cascaded adaptive filter blocks is developed where three-channel accelerometer signals are used as references to motion artefacts...
February 2018: Healthcare Technology Letters
André Guedes, Rita Macedo, Gerardo Jaramillo, Susana Cardoso, Paulo P Freitas, David A Horsley
Advances in the magnetic sensing technology have been driven by the increasing demand for the capability of measuring ultrasensitive magnetic fields. Among other emerging applications, the detection of magnetic fields in the picotesla range is crucial for biomedical applications. In this work Picosense reports a millimeter-scale, low-power hybrid magnetoresistive-piezoelectric magnetometer with subnanotesla sensitivity at low frequency. Through an innovative noise-cancelation mechanism, the 1/f noise in the MR sensors is surpassed by the mechanical modulation of the external magnetic fields in the high frequency regime...
March 6, 2018: Sensors
Elizabeth A Kelly, Michael E Stadler, Steven Nelson, Christina L Runge, David R Friedland
OBJECTIVE: To determine the feasibility of audiometric screening with tablet-based applications in typical clinic locations: examination room and clinic waiting area. STUDY DESIGN: A randomized prospective study. SETTING: Tertiary referral center. PATIENTS: Participants included 107 adult patients referred for audiometric testing to assess hearing loss. INTERVENTION: Each patient completed standard audiometry testing and one of three tablet-based audiometric applications that included pure-tone air conduction testing...
February 28, 2018: Otology & Neurotology
Wei Du, Jun Jia, J F Chen, Z Y Ou, Weiping Zhang
Absolute sensitivity is measured for the phase measurement in an SU(1,1) type interferometer, and the results are compared to that of a Mach-Zehnder interferometer operated under the condition of the same intra-interferometer intensity. The interferometer is phase locked to a point with the largest quantum noise cancellation, and a simulated phase modulation is added in one arm of the SU(1,1) interferometer. Both the signal and noise level are estimated at the same frequency range, and we obtained 3 dB improvement in sensitivity for the SU(1,1) interferometer over the Mach-Zehnder interferometer...
March 1, 2018: Optics Letters
Daniel Hamacher, Franziska Schley, Karsten Hollander, Astrid Zech
Auditory information affects sensorimotor control of gait. Noise or active noise cancelling alters the perception of movement related sounds and, probably, gait stability. The aim of the current study was to evaluate the effects of noise cancelling on gait stability. Twenty-five healthy older subjects (70 ± 6 years) were included into a randomized cross-over study. Gait stability (largest Lyapunov exponent) in normal overground walking was determined for the following hearing conditions: no manipulation and active noise cancelling...
February 24, 2018: Human Movement Science
Phoebe E Riley, Douglas S Ruhl, Macario Camacho, Anthony M Tolisano
Objective The cochlear implant (CI) improves quality of life for people who are severely and profoundly deafened, allowing implantees to perceive speech at levels similar to those of individuals with normal hearing. However, patients with CIs generally report a reduced appreciation of music after implantation. We aimed to systematically review the English-language literature for studies evaluating music enjoyment and perception among adult patients with CIs. Data Sources A systematic review of PubMed/MEDLINE, Scopus, Embase, and the Cochrane Library...
February 1, 2018: Otolaryngology—Head and Neck Surgery
Jie Yang, Zhiguo Gui, Liyuan Zhang, Pengcheng Zhang
PURPOSE: To reduce computation and decrease planning time with little or no loss in plan quality compared to the column-generation-based (cg) method, a simple method of aperture generation based on threshold segmentation (agts) is proposed. METHODS: The proposed agts strategy consists of two steps. First, a fuzzy controller is used for noise cancellation; then, new apertures are added using the threshold segmentation algorithm. We tested the proposed method on seven prostate tumor cases using the computational environment for radiotherapy research algorithms for the dose calculations and compared the results with those obtained by generating the plan aperture using the cg method...
February 19, 2018: Medical Physics
Sevgi Gokce Kafali, Tolga Çukur, Emine Ulku Saritas
PURPOSE: DWI suffers from low SNR when compared to anatomical MRI. To maintain reasonable SNR at relatively high spatial resolution, multiple acquisitions must be averaged. However, subject motion or involuntary physiological motion during diffusion-sensitizing gradients cause phase offsets among acquisitions. When the motion is localized to a small region, these phase offsets become particularly problematic. Complex averaging of acquisitions lead to cancellations from these phase offsets, whereas magnitude averaging results in noise amplification...
February 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Ping Gong, Pengfei Song, Shigao Chen
Contrast-enhanced ultrasound (CEUS) imaging has great potential for use in new ultrasound clinical applications such as myocardial perfusion imaging and abdominal lesion characterization. In CEUS imaging, contrast agents (i.e., microbubbles) are used to improve contrast between blood and tissue because of their high nonlinearity under low ultrasound pressure. However, the quality of CEUS imaging sometimes suffers from a low signal-to-noise ratio (SNR) in deeper imaging regions when a low mechanical index (MI) is used to avoid microbubble disruption, especially for imaging at off-resonance transmit frequencies...
February 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Fintan Costello, Paul Watts
We describe a computational model of two central aspects of people's probabilistic reasoning: descriptive probability estimation and inferential probability judgment. This model assumes that people's reasoning follows standard frequentist probability theory, but it is subject to random noise. This random noise has a regressive effect in descriptive probability estimation, moving probability estimates away from normative probabilities and toward the center of the probability scale. This random noise has an anti-regressive effect in inferential judgement, however...
January 2018: Topics in Cognitive Science
Poongundran Selvaprabhu, Sunil Chinnadurai, Md Abdul Latif Sarker, Moon Ho Lee
In this paper, we characterise the joint interference alignment (IA) and power allocation strategies for a K-user multicell multiple-input multiple-output (MIMO) Gaussian interference channel. We consider a MIMO interference channel with blind-IA through staggered antenna switching on the receiver. We explore the power allocation and feasibility condition for cooperative cell-edge (CE) mobile users (MUs) by assuming that the channel state information is unknown. The new insight behind the transmission strategy of the proposed scheme is premeditated (randomly generated transmission strategy) and partial cooperative CE MUs, where the transmitter is equipped with a conventional antenna, the receiver is equipped with a reconfigurable multimode antenna (staggered antenna switching pattern), and the receiver switches between preset T modes...
January 28, 2018: Sensors
Mert Ergeneci, Kaan Gokcesu, Erhan Ertan, Panagiotis Kosmas
Wearable technology has gained increasing popularity in the applications of healthcare, sports science, and biomedical engineering in recent years. Because of its convenient nature, the wearable technology is particularly useful in the acquisition of the physiological signals. Specifically, the (surface electromyography) sEMG systems, which measure the muscle activation potentials, greatly benefit from this technology in both clinical and industrial applications. However, the current wearable sEMG systems have several drawbacks including inefficient noise cancellation, insufficient measurement quality, and difficult integration to customized applications...
February 2018: IEEE Transactions on Biomedical Circuits and Systems
Torsten Rahne, Robert Köppke, Michael Nehring, Stefan K Plontke, Hans-Georg Fischer
Multidimensional food perception is based mainly on gustatory and olfactory function. Recent research has demonstrated that hypobaric pressure impairs gustatory function and that background noise or distracting auditory stimulation impairs olfactory function. Using a hypobaric chamber, the odor identification, discrimination, and thresholds as well as taste identification and threshold scores were measured in 16 healthy male volunteers under normal and hypobaric (6380 ft) conditions using clinically validated tests...
2018: PloS One
Christopher F Hauth, Thomas Brand
In studies investigating binaural processing in human listeners, relatively long and task-dependent time constants of a binaural window ranging from 10 ms to 250 ms have been observed. Such time constants are often thought to reflect "binaural sluggishness." In this study, the effect of binaural sluggishness on binaural unmasking of speech in stationary speech-shaped noise is investigated in 10 listeners with normal hearing. In order to design a masking signal with temporally varying binaural cues, the interaural phase difference of the noise was modulated sinusoidally with frequencies ranging from 0...
January 2018: Trends in Hearing
Kazuyuki Hiraoka, Toshihiko Hamada, Gen Hori
The largest family of density-ratio based estimators is obtained for unnormalized statistical models under the assumption of properness. They do not require normalization of the probability density function (PDF) because they are based on the density ratio of the same PDF at different points; therefore, the multiplicative normalization constant cancels out. In contrast with most existing work, a single necessary and sufficient condition is given here, rather than merely sufficient conditions for proper criteria for estimation...
February 2018: Neural Networks: the Official Journal of the International Neural Network Society
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