Extraction of the Mayer wave component in blood pressure from the instantaneous phase difference between electrocardiograms and photoplethysmograms

2010 ◽  
Vol 15 (4) ◽  
pp. 522-525
Author(s):  
Norihiro Sugita ◽  
Makoto Yoshizawa ◽  
Masayuki Murakoshi ◽  
Makoto Abe ◽  
Noriyasu Homma ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Phase Difference ◽  
Wave Component ◽  
Instantaneous Phase ◽  
Mayer Wave

Two Tandem Cylinders With Passive Turbulence Control in Flow-Induced Vibration: Relation of Oscillation Patterns to Frequency Response

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Kai Lan ◽  
Hai Sun ◽  
Michael M. Bernitsas
Keyword(s):  
Frequency Response ◽  
Phase Difference ◽  
Volume Ratio ◽  
Flow Induced Vibration ◽  
Frequency Spectra ◽  
Turbulence Control ◽  
Instantaneous Phase ◽  
Tandem Cylinders ◽  
Flow Induced Vibrations ◽  
The University

Flow-induced vibrations (FIV) are conventionally destructive and should be suppressed. Since 2006, the Marine Renewable Energy Laboratory (MRELab) of the University of Michigan has been studying FIV of multiple cylinders to enhance their response for harnessing hydrokinetic power from ocean, river, and tidal currents. Interactions between multiple cylinders in FIV enable high power-to-volume ratio in a converter consisting of multiple oscillators. This paper investigates experimentally the relation between oscillation patterns and frequency response of two cylinders in tandem. All experiments are conducted in the recirculating channel of the MRELab for 30,000 < Re < 120,000. Phase analysis reveals three dominant patterns of oscillation of two tandem cylinders by calculating the instantaneous phase difference between the two cylinders. This phase difference characterizes each major pattern. Pattern A is characterized by small lead or lag of one cylinder over the other. In pattern B, there is nearly 180 deg out of phase oscillations between the cylinders. In pattern C, the instantaneous phase difference changes continuously from −180 deg to +180 deg. Using frequency spectra and amplitude response, oscillation characteristics of each cylinder are revealed in vortex-induced vibration (VIV) and galloping. Pattern A occurs mostly in galloping when the first cylinder has higher stiffness. Pattern B occurs seldom and typically in the initial VIV branch and transition from VIV to galloping. Pattern C occurs in the upper and lower VIV branches; and in galloping when the lead cylinder has lower stiffness.

scholarly journals Noninvasive blood pressure estimation with peak delay of different pulse waves

2019 ◽  
Vol 15 (3) ◽  
pp. 155014771983787 ◽  
Author(s):  
Yibin Li ◽  
Shengnan Li ◽  
Houbing Song ◽  
Bin Shao ◽  
Xiao Yang ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Smooth Muscle ◽  
Phase Difference ◽  
Blood Pressure Monitoring ◽  
Study Phase ◽  
Noninvasive Blood Pressure ◽  
Hemodynamic Model ◽  
Pulse Waves ◽  
Pressure Estimation ◽  
Blood Pressure Estimation

In this article, we discuss the validity of noninvasive continuous blood pressure estimation with two different types of peripheral pulse waves. Artery-blocking experiment shows that phase difference of two pulse waves at the same location is well related with blood pressure and blood flow fluctuation. Exercise-recovery experiment resulting from 16 subjects shows that phase difference varies with blood pressure with the correlation from 0.63 to 0.88 when blood pressure changes rapidly. Simulations based on a classic hemodynamic model verify the relationship between phase difference and blood pressure. However, phase difference is strongly correlated with smooth muscle state of the arterial wall as well. If smooth muscle information can be obtained by further study, phase difference can act as a promising approach to portable and wearable device for real-time blood pressure monitoring.

Detection of Karst Cavity Beneath Cast-in-place Pile Using Instantaneous Phase Difference of Two Receiver Recordings

Geophysics ◽  
2020 ◽  
pp. 1-50
Author(s):  
Liu Liu ◽  
Zhenming Shi ◽  
Georgios Tsoflias ◽  
Ming Peng ◽  
Chengcheng Liu ◽  
...  
Keyword(s):  
Surface Waves ◽  
Phase Difference ◽  
Analysis Method ◽  
Dominant Wavelength ◽  
P Waves ◽  
Instantaneous Phase ◽  
Numerical Tests ◽  
Field Investigations ◽  
The Stability

Karst cavities beneath bored cast in situ piles are hazardous to the stability of infrastructure projects. Therefore, it is important to detect karst cavities during the construction of piles. Downward looking sonar deployed at the bottom of a pile hole can be used to detect cavities, however, interference of multiple reflected surface waves from the walls of the pile hole masks the weak cavity reflections. We introduce a sonar method that exploits the instantaneous phase difference between signals recorded at two receivers to detect karst cavities beneath piles. The receiver separation is set to half the dominant wavelength of surface waves propagating along the pile hole. We define Instantaneous Phase Difference Intensity (IPDI) as an index that measures the similarity of instantaneous phase between the signals at the two receivers. Higher IPDI signifies that the two signals have similar instantaneous phase at that time, which implies the arrival of a reflection from a cavity. Reflected surface wave arrivals exhibit low IPDI by design of the receiver geometry. Thus, the first break of reflected P-waves from the roof and floor of a cavity can be identified. We evaluate the effectiveness of the IPDI based analysis method using numerical tests simulating varying depth, azimuth and size of karst cavities. A prototype using the IPDI analysis demonstrates the application of the new pile hole sonar method at two field investigations. Advance drilling, borehole optical image logs and cross-hole tomography verify the IPDI detection results. We conclude that the two-receiver sonar instrumentation along with the IPDI analysis are effective for detecting cavities beneath piles.

scholarly journals A Hilbert–Huang Transform-Based Adaptive Fault Detection and Classification Method for Microgrids

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5040
Author(s):  
Yijin Li ◽  
Jianhua Lin ◽  
Geng Niu ◽  
Ming Wu ◽  
Xuteng Wei
Keyword(s):  
Fault Detection ◽  
Phase Difference ◽  
High Frequency ◽  
Frequency Component ◽  
High Frequency Component ◽  
Hilbert Huang Transform ◽  
Instantaneous Phase ◽  
Fault Type ◽  
Fault Detection And Classification ◽  
Fault Characteristic

Fault detection in microgrids is of great significance for power systems’ safety and stability. Due to the high penetration of distributed generations, fault characteristics become different from those of traditional fault detection. Thus, we propose a new fault detection and classification method for microgrids. Only current information is needed for the method. Hilbert–Huang Transform and sliding window strategy are used in fault characteristic extraction. The instantaneous phase difference of current high-frequency component is obtained as the fault characteristic. A self-adaptive threshold is set to increase the detection sensitivity. A fault can be detected by comparing the fault characteristic and the threshold. Furthermore, the fault type is identified by the utilization of zero-sequence current. Simulations for both section and system have been completed. The instantaneous phase difference of the current high-frequency component is an effective fault characteristic for detecting ten kinds of faults. Using the proposed method, the maximum fault detection time is 13.8 ms and the maximum fault type identification time is 14.8 ms. No misjudgement happens under non-fault disturbance conditions. The simulations indicate that the proposed method can achieve fault detection and classification rapidly, accurately, and reliably.

Repeatability study of seismic source signatures

Geophysics ◽  
2001 ◽  
Vol 66 (6) ◽  
pp. 1811-1817 ◽  
Author(s):  
Bibi C. Aritman
Keyword(s):  
Phase Difference ◽  
Seismic Source ◽  
Seismic Survey ◽  
Surface Source ◽  
Near Surface ◽  
Seismic Surveys ◽  
Instantaneous Phase ◽  
Reservoir Monitoring ◽  
The Difference

This study discusses the repeatability of source signature using the instantaneous phase, as derived from the complex trace attributes. The study is part of a very large 2‐D seismic survey using sources of vibroseis and surface dynamite. The field procedure consisted of recording the production record, retaining the positions, then repeat‐recording the same shake or shot. The instantaneous phase was found to be the best measure for the difference between the first and the repeat records. In addition to the instantaneous phase, other analyses were used to evaluate changes in source signature. Results were tabulated for statistical comparisons and graded for quality. Excluding erroneous cases, the remainder of poor repeatabilities were studied. The analyses of near‐offset data seem to indicate that nonrepeatability of source signature relates mostly to changes in absorption and cohesion induced by elastic saturation at the near surface. In general, by time shifting and phase rotating the repeat record, the difference in instantaneous phase tends to diminish. The new idea of using instantaneous phase difference plots to evaluate repeatability offers improved evaluation of source signatures and can also be used to detect time‐lapsed changes in reservoir monitoring. By evaluating repeatability and avoiding elastic saturation near the surface, source signatures can be made more consistent, thus increasing the resolution of stacked data for 2‐D, 3‐D, and 4‐D seismic surveys.

scholarly journals Dynamic cerebral autoregulation estimates derived from near infrared spectroscopy and transcranial Doppler are similar after correction for transit time and blood flow and blood volume oscillations

2018 ◽  
Vol 40 (1) ◽  
pp. 135-149 ◽  
Author(s):  
Jan Willem J Elting ◽  
Jeanette Tas ◽  
Marcel JH Aries ◽  
Marek Czosnyka ◽  
Natasha M Maurits
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Transit Time ◽  
Phase Difference ◽  
Cerebral Autoregulation ◽  
Cerebral Blood Flow Velocity ◽  
Intraclass Correlation ◽  
Arterial Blood ◽  
Dynamic Cerebral Autoregulation

We analysed mean arterial blood pressure, cerebral blood flow velocity, oxygenated haemoglobin and deoxygenated haemoglobin signals to estimate dynamic cerebral autoregulation. We compared macrovascular (mean arterial blood pressure-cerebral blood flow velocity) and microvascular (oxygenated haemoglobin-deoxygenated haemoglobin) dynamic cerebral autoregulation estimates during three different conditions: rest, mild hypocapnia and hypercapnia. Microvascular dynamic cerebral autoregulation estimates were created by introducing the constant time lag plus constant phase shift model, which enables correction for transit time, blood flow and blood volume oscillations (TT-BF/BV correction). After TT-BF/BV correction, a significant agreement between mean arterial blood pressure-cerebral blood flow velocity and oxygenated haemoglobin-deoxygenated haemoglobin phase differences in the low frequency band was found during rest (left: intraclass correlation=0.6, median phase difference 29.5° vs. 30.7°, right: intraclass correlation=0.56, median phase difference 32.6° vs. 39.8°) and mild hypocapnia (left: intraclass correlation=0.73, median phase difference 48.6° vs. 43.3°, right: intraclass correlation=0.70, median phase difference 52.1° vs. 61.8°). During hypercapnia, the mean transit time decreased and blood volume oscillations became much more prominent, except for very low frequencies. The transit time related to blood flow oscillations was remarkably stable during all conditions. We conclude that non-invasive microvascular dynamic cerebral autoregulation estimates are similar to macrovascular dynamic cerebral autoregulation estimates, after TT-BF/BV correction is applied. These findings may increase the feasibility of non-invasive continuous autoregulation monitoring and guided therapy in clinical situations.

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