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Noise Cancellation

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https://www.readbyqxmd.com/read/28461900/common-mode-noise-cancellation-circuit-for-wearable-ecg
#1
Mutsumi Noro, Daisuke Anzai, Jianqing Wang
Wearable electrocardiogram (ECG) is attracting much attention for monitoring heart diseases in healthcare and medical applications. However, an imbalance usually exists between the contact resistances of sensing electrodes, so that a common mode noise caused by external electromagnetic field can be converted into the ECG detection circuit as a differential mode interference voltage. In this study, after explaining the mechanism of how the common mode noise is converted to a differential mode interference voltage, the authors propose a circuit with cadmium sulphide photo-resistors for cancelling the imbalance between the contact resistances and confirm its validity by simulation experiment...
April 2017: Healthcare Technology Letters
https://www.readbyqxmd.com/read/28459813/slow-diffusive-dynamics-in-a-chaotic-balanced-neural-network
#2
Nimrod Shaham, Yoram Burak
It has been proposed that neural noise in the cortex arises from chaotic dynamics in the balanced state: in this model of cortical dynamics, the excitatory and inhibitory inputs to each neuron approximately cancel, and activity is driven by fluctuations of the synaptic inputs around their mean. It remains unclear whether neural networks in the balanced state can perform tasks that are highly sensitive to noise, such as storage of continuous parameters in working memory, while also accounting for the irregular behavior of single neurons...
May 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28454173/on-the-cancellation-of-oam-beams-propagating-through-convective-turbulence
#3
Gustavo Funes, Jaime Anguita
By means of an experimental setup, we study the time evolution of orbital angular momentum (OAM) crosstalk after a 5 m propagation path with a turbulence perturbation generated by a flat heater. This convective turbulence could simulate the beam passing over hot concrete or building roofs. We study the consequences of using a wide range of transmission OAM states. We also explore the effect of misalignment, and we propose two new different techniques for analyzing the vortex cancellation. Even though results are inconsistent with theoretical predictions, especially for low turbulence regimes, we state that signal-to-noise ratio is the key factor to understanding this discrepancy...
May 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28394290/combining-dcqgmp-based-sparse-decomposition-and-mpdr-beamformer-for-multi-type-interferences-mitigation-for-gnss-receivers
#4
Qiang Guo, Liangang Qi
In the coexistence of multiple types of interfering signals, the performance of interference suppression methods based on time and frequency domains is degraded seriously, and the technique using an antenna array requires a large enough size and huge hardware costs. To combat multi-type interferences better for GNSS receivers, this paper proposes a cascaded multi-type interferences mitigation method combining improved double chain quantum genetic matching pursuit (DCQGMP)-based sparse decomposition and an MPDR beamformer...
April 10, 2017: Sensors
https://www.readbyqxmd.com/read/28392978/a-380pw-dual-mode-optical-wake-up-receiver-with-ambient-noise-cancellation
#5
Wootaek Lim, Taekwang Jang, Inhee Lee, Hun-Seok Kim, Dennis Sylvester, David Blaauw
We present a sub-nW optical wake-up receiver for wireless sensor nodes. The wake-up receiver supports dual mode operation for both ultra-low standby power and high data rates, while canceling ambient in-band noise. In 0.18µm CMOS the receiver consumes 380pW in always-on wake-up mode and 28.1µW in fast RX mode at 250kbps.
June 2016: Symposium on VLSI Circuits: [proceedings]. Symposium on VLSI Circuits
https://www.readbyqxmd.com/read/28380909/high-speed-free-space-optical-continuous-variable-quantum-key-distribution-enabled-by-three-dimensional-multiplexing
#6
Zhen Qu, Ivan B Djordjevic
A high-speed four-state continuous-variable quantum key distribution (CV-QKD) system, enabled by wavelength-division multiplexing, polarization multiplexing, and orbital angular momentum (OAM) multiplexing, is studied in the presence of atmospheric turbulence. The atmospheric turbulence channel is emulated by two spatial light modulators (SLMs) on which two randomly generated azimuthal phase patterns yielding Andrews' spectrum are recorded. The phase noise is mitigated by the phase noise cancellation (PNC) stage, and channel transmittance can be monitored directly by the D...
April 3, 2017: Optics Express
https://www.readbyqxmd.com/read/28372134/vortex-sound-radiation-in-a-flow-duct-with-a-dipole-source-and-a-flexible-wall-of-finite-length
#7
Y K Chiang, Y S Choy, S K Tang
The noise attenuation of fan-ducted noise at low blade-passage frequency remains a challenge. The present study investigates the noise reduction mechanism of a tensioned membrane housing device that directly controls the sound radiation from the doublet which is enclosed in an infinitely long duct with a point vortex. The time dependent sound radiation mechanism and the vibro-acoustics coupling mechanism of the systems are studied by adopting the potential theory and matched asymptotic expansion technique. The silencing performance of such a passive approach depends on the amplitude and phase of the sound field created by the doublet and the acoustic pressure induced by the membrane oscillation in order to achieve sound cancellation...
March 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28372093/generalized-sidelobe-canceller-beamforming-method-for-ultrasound-imaging
#8
Ping Wang, Na Li, Han-Wu Luo, Yong-Kun Zhu, Shi-Gang Cui
A modified generalized sidelobe canceller (IGSC) algorithm is proposed to enhance the resolution and robustness against the noise of the traditional generalized sidelobe canceller (GSC) and coherence factor combined method (GSC-CF). In the GSC algorithm, weighting vector is divided into adaptive and non-adaptive parts, while the non-adaptive part does not block all the desired signal. A modified steer vector of the IGSC algorithm is generated by the projection of the non-adaptive vector on the signal space constructed by the covariance matrix of received data...
March 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28291479/does-combat-hearing-preservation-equipment-affect-balance
#9
Art Ambrosio, Ali N Hoffer, Michael Hoffer
OBJECTIVES: (1) To investigate whether the occlusion effect and hearing attenuation produced by 3M Combat Arms Ear Plugs (CAEP) affects balance when compared to no hearing protection and (2) to investigate whether the occlusion effect and noise-canceling capabilities of the Nacre QuietPro system affects balance when compared to no hearing protection. METHODS: This prospective study collected pilot data for investigation of mechanisms of balance. 20 subjects with normal hearing and no vestibular dysfunction were tested with blackened goggles in three conditions-no hearing protection, CAEP, and with the Nacre QuietPro...
March 2017: Military Medicine
https://www.readbyqxmd.com/read/28269592/motion-noise-cancellation-in-seismocardiogram-of-ambulant-subjects-with-dual-sensors
#10
Chenxi Yang, Negar Tavassolian
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/28268326/asynchronous-noise-removal-for-earbud-based-ppg-sensors
#11
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/28254082/ecg-artifact-cancellation-in-surface-emg-signals-by-fractional-order-calculus-application
#12
Nadica Miljković, Nenad Popović, Olivera Djordjević, Ljubica Konstantinović, Tomislav B Šekara
BACKGROUND AND OBJECTIVE: New aspects for automatic electrocardiography artifact removal from surface electromyography signals by application of fractional order calculus in combination with linear and nonlinear moving window filters are explored. Surface electromyography recordings of skeletal trunk muscles are commonly contaminated with spike shaped artifacts. This artifact originates from electrical heart activity, recorded by electrocardiography, commonly present in the surface electromyography signals recorded in heart proximity...
March 2017: Computer Methods and Programs in Biomedicine
https://www.readbyqxmd.com/read/28245585/a-novel-technique-for-fetal-ecg-extraction-using-single-channel-abdominal-recording
#13
Nannan Zhang, Jinyong Zhang, Hui Li, Omisore Olatunji Mumini, Oluwarotimi Williams Samuel, Kamen Ivanov, Lei Wang
Non-invasive fetal electrocardiograms (FECGs) are an alternative method to standard means of fetal monitoring which permit long-term continual monitoring. However, in abdominal recording, the FECG amplitude is weak in the temporal domain and overlaps with the maternal electrocardiogram (MECG) in the spectral domain. Research in the area of non-invasive separations of FECG from abdominal electrocardiograms (AECGs) is in its infancy and several studies are currently focusing on this area. An adaptive noise canceller (ANC) is commonly used for cancelling interference in cases where the reference signal only correlates with an interference signal, and not with a signal of interest...
February 24, 2017: Sensors
https://www.readbyqxmd.com/read/28236262/comparing-effects-between-music-intervention-and-aromatherapy-on-anxiety-of-patients-undergoing-mechanical-ventilation-in-the-intensive-care-unit-a-randomized-controlled-trial
#14
Chiu-Hsiang Lee, Chiung-Ling Lai, Yi-Hui Sung, Mei Yu Lai, Chung-Ying Lin, Long-Yau Lin
PURPOSE: Using patient-reported outcomes and physiological indicators to test the effects of music intervention and aromatherapy on reducing anxiety for intensive care unit (ICU) patients undergoing mechanical ventilation. METHODS: Patients with ICU admission duration >24 h were randomly assigned to a Music intervention group (n = 41), Aromatherapy group (n = 47), or Control group (rest only; n = 44). Each patient in the Music group listened to music; each patient in the Aromatherapy group received lavender essential oil massage on his/her back for 5 min; each patient in the Control group wore noise-canceling headphones...
February 24, 2017: Quality of Life Research
https://www.readbyqxmd.com/read/28227848/motion-noise-cancellation-in-seismocardiogram-of-ambulant-subjects-with-dual-sensors
#15
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
#16
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
#17
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
#18
Jingjie Feng, Congcong Zhou, Cheng He, Yuan Li, Xuesong Ye
OBJECTIVE: In this paper, a miniaturized wearable core body temperature (CBT) monitoring system based on the dual heat flux (DHF) principle was developed. APPROACH: 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...
February 8, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28174614/weak-electric-fields-detectability-in-a-noisy-neural-network
#19
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
#20
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
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