The relationship between residential proximity to extremely low frequency power transmission lines and adverse birth outcomes

2010 ◽  
Vol 65 (1) ◽  
pp. 83-85 ◽  
Author(s):  
N. Auger ◽  
D. Joseph ◽  
M. Goneau ◽  
M. Daniel
Keyword(s):  
Transmission Lines ◽  
Power Transmission ◽  
Low Frequency ◽  
Adverse Birth Outcomes ◽  
Power Transmission Lines ◽  
Residential Proximity ◽  
Extremely Low Frequency ◽  
Low Frequency Power ◽  
The Relationship ◽  
Frequency Power

Increase in electromyogram low-frequency power in nonfatigued contracting skeletal muscle

1986 ◽  
Vol 61 (3) ◽  
pp. 1012-1017 ◽  
Author(s):  
A. R. Bazzy ◽  
J. B. Korten ◽  
G. G. Haddad
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Biceps Brachii ◽  
Low Frequency ◽  
Biceps Brachii Muscle ◽  
Power Spectral ◽  
Loaded Breathing ◽  
Low Frequency Power ◽  
The Relationship ◽  
Frequency Power

We studied the relationship between changing elbow joint angle and the power spectral density of the biceps brachii muscle electromyogram (EMG) during submaximal isometric contractions. For this purpose, we recorded the EMG of the biceps brachii muscle with surface electrodes in 13 subjects. Each subject held a 2.8-kg weight and contracted the biceps isometrically for 30 s at one of two lengths. The length of the muscle was changed by flexing the forearm toward the upper arm to form an angle of 135 degrees (L1) or 45 degrees (L2). We found that the mean centroid frequency (fc) of the EMG power spectral density was 26% lower at L1 than at L2 (P less than 0.01). For each subject there was no significant change in fc during the isometric contraction at either angle. In addition, in nine subjects who sustained fatiguing contractions of the biceps with a 6-kg load, fc decreased by 15% (P less than 0.025). These data suggest that a change in the length at which a muscle contracts isometrically can alter or induce indirectly an alteration in the frequency content of its EMG. This finding may have important implications for the assessment of respiratory muscle EMG especially during loaded breathing.

scholarly journals The Effect of Massage Therapy on Autonomic Activity in Critically Ill Children

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ling Guan ◽  
Jean-Paul Collet ◽  
Nataliya Yuskiv ◽  
Peter Skippen ◽  
Rollin Brant ◽  
...  
Keyword(s):  
Low Frequency ◽  
Pediatric Intensive Care ◽  
Frequency Domain Analysis ◽  
Clinical Severity ◽  
Critically Ill Children ◽  
Percentage Increase ◽  
Low Frequency Power ◽  
Study Intervention ◽  
The Relationship ◽  
Frequency Power

Objectives. Our main objective was to describe the effect of foot and hand (F&H) massage on the autonomic nervous system (ANS) activity in children hospitalized in a pediatric intensive care unit (PICU); the secondary objectives were to assess the relationship between ANS function and the clinical severity and to explore the effects of repeated massage sessions on the ANS.Methods. Design was a descriptive experimental study. Intervention was single or six session(s) of F&H massage. ANS function was assessed through the frequency-domain analysis of heart rate variability. Main metrics included high and low frequency power (HF and LF), HF + LF, and LF/HF ratio.Results. Eighteen children participated in the study. A strong Spearman’s correlation (ρ=-0.77) was observed between HF + LF and clinical severity. During massage, the parasympathetic activity (measured by HF) increased significantly from baseline (P=0.04) with a mean percentage increase of 75% (95% CI: 20%∼130%). LF increased by 56% (95% CI: 20%∼92%) (P=0.026). Repeated sessions were associated with a persistent effect on HF and LF which peaked at the second session and remained stable thereafter.Conclusions. HF + LF is positively correlated with clinical severity. F&H massage can improve the ANS activity and the effect persists when repeated sessions are offered.

scholarly journals CALCULATION OF POWER LINE FIELDS BETWEEN CIRCULAR CONDUCTORS

2012 ◽  
Vol 04 (01) ◽  
pp. 1250025
Author(s):  
ANDREW SEAGAR ◽  
SALAKCHIT NILBOWORN
Keyword(s):  
Electric Field ◽  
Transmission Lines ◽  
Power Transmission ◽  
Circular Cross Section ◽  
Low Frequency ◽  
Test Cases ◽  
Power Transmission Lines ◽  
System Matrix ◽  
High Voltage Direct Current ◽  
Frequency Components

It is important to calculate the electric field at the surface of high voltage direct current power transmission lines, since it is this field which governs the onset of corona discharge and the power loss arising therefrom. A method is presented here to calculate the electric field based on an implementation of the boundary element method for conductors of strictly circular cross section. Given the circular geometry it is possible to resolve all integrals involved analytically. A Galerkin approach is adopted, giving the solution in the spatial frequency domain. That allows a controlled truncation of the system matrix by choice of which frequency components to keep. It transpires that the low frequency components are the most important ones. Two test cases are used to quantify the accuracy of the solution with respect to truncation and distance from the surface. It is found that the accuracy increases with distance from the surface, but for all distances can be controlled by choosing an appropriate level of truncation.

Study on Dynamic Simulation of 4-Bundle Ice-Coated Conductor Galloping Based on 3-D Model

2011 ◽  
Vol 105-107 ◽  
pp. 474-477
Author(s):  
Shi Jing Wu ◽  
Zeng Lei Zhang ◽  
Zhen Hao Liu ◽  
Ji Cai Hu
Keyword(s):  
Transmission Lines ◽  
Power Transmission ◽  
Low Frequency ◽  
Element Model ◽  
Wake Flow ◽  
Power Transmission Lines ◽  
Ansys Software ◽  
Frequency Coupling ◽  
D Model ◽  
The Finite Element Model

Galloping of power transmission lines is a low frequency self-oscillation with large amplitude. The aerodynamic effect on each sub-conductor of 4-bundle conductor is different due to wake-flow-influence. In order to explore the reasons leading to galloping, a 3-D model for power transmission line is built. A two-node quadratic beam element in 3-D and a structure mass element are applied to establish the finite element model of iced 4-bundle conductor in ANSYS software. Then dynamic transient response calculations are made on this model. According to the results, difference in vibration of sub-conductors and frequency coupling of torsional and transverse vibration can be confirmed. The simulation results illustrate the wake-flow-influence effect and the coupled motions effect on galloping of 4-bundle conductor.

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