Metabolic Low-Frequency Oscillation and Abbreviated Protocol for Estimating REE by Indirect Calorimetry in Healthy Adults

2021 ◽  
Author(s):  
Yuan Wang ◽  
Ruide Liu ◽  
Rui Jin ◽  
Zijun He ◽  
Yanyan Chen ◽  
...  
Keyword(s):  
Indirect Calorimetry ◽  
Low Frequency ◽  
Resting Energy Expenditure ◽  
Measurement Time ◽  
Standard Protocol ◽  
Low Frequency Oscillation ◽  
Low Frequency Oscillations ◽  
Minute Interval ◽  
Metabolic Data ◽  
Time Required

Objectives: The aim of this study is to propose a new wave protocol to identify low-frequency oscillations for evaluating resting energy expenditure (REE) and compare its performance with the 5-minute interval abbreviated protocol and standard protocol. Research methods & procedures: Consecutive 20-minute indirect calorimetry (IC) was used to collect metabolic data from 23 women and 37 men (between 23 and 43 years old). Sliding window filter algorithms were used to eliminate noise. Three protocols were used to evaluate REE: averaging the data between two consecutive waves (wave protocol), averaging the second 5-minute intervals (interval protocol), and averaging the last 15-minute REE (standard protocol). Results: Based on 60 healthy participants' metabolic data, compared with the interval protocol, the wave protocol showed better consistency with the standard protocol. The mean bias (limits of agreement) using the wave protocol was 0.3458% (-7.817% to 8.509%), and that using the interval protocol was -1.720% (-16.06% to 12.62%). The time required to evaluate REE with the wave protocol and interval protocol was measured. The measurement time for the interval protocol was 10 minutes, while the average measurement time for the wave protocol was 9.75 minutes. Conclusions: We recommend the wave protocol for estimating REE in healthy people. This abbreviated protocol can identify low-frequency oscillations and consider individual differences to more accurately reflect the baseline REE compared to the interval protocol. Compared with the standard protocol, the measurement time of the wave protocol was reduced by nearly half (from 20 minutes (standard protocol) to 9.75 minutes).

Oppositional Differential Search Algorithm for the Optimal Tuning of Both Single Input and Dual Input Power System Stabilizer

2021 ◽  
pp. 256-282
Author(s):  
Sourav Paul ◽  
Provas Kumar Roy
Keyword(s):  
Power System ◽  
Search Algorithm ◽  
Low Frequency ◽  
Input Power ◽  
Power System Stabilizer ◽  
Low Frequency Oscillation ◽  
Interconnected Power System ◽  
Low Frequency Oscillations ◽  
Single Input ◽  
System Stabilizer

Low frequency oscillation has been a major threat in large interconnected power system. These low frequency oscillations curtain the power transfer capability of the line. Power system stabilizer (PSS) helps in diminishing these low frequency oscillations by providing auxiliary control signal to the generator excitation input, thereby restoring stability of the system. In this chapter, the authors have incorporated the concept of oppositional based learning (OBL) along with differential search algorithm (DSA) to solve PSS problem. The proposed technique has been implemented on both single input and dual input PSS, and comparative study has been done to show the supremacy of the proposed techniques. The convergence characteristics as well authenticate the sovereignty of the considered algorithms.

scholarly journals A Mechanism of the Interdecadal Changes of the Global Low-Frequency Oscillation

Atmosphere ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 292
Author(s):  
Ruowen Yang ◽  
Quanliang Chen ◽  
Yuyun Liu ◽  
Lin Wang
Keyword(s):  
Intraseasonal Oscillation ◽  
Low Frequency ◽  
Basic Flow ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Reanalysis Dataset ◽  
Atmospheric Research ◽  
Low Frequency Oscillations ◽  
Environmental Prediction ◽  
Interdecadal Changes

Based on the National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis dataset from 1948 to 2009, this study reveals that global low-frequency oscillation features two major temporal bands. One is a quasi-60-day period known as the intraseasonal oscillation (ISO), and the other is a quasi-15-day period known as the quasi-biweekly oscillation (QBWO). After the mid-1970s, both the ISO and QBWO become intensified and more active, and these changes are equivalently barotropic. The primitive barotropic equations are adopted to study the involved mechanism. It reveals that the e-folding time of the least stable modes of both the ISO and QWBO becomes shorter if the model is solved under the atmospheric basic state after the mid-1970s than if solved under the basic state before the mid-1970s. This result suggests that the atmospheric basic flow after the mid-1970s facilitates a more rapid growth of the ISO and QBWO, and thereby an intensification of the low-frequency oscillations at the two bands.

Simulation of Grid Low Frequency Oscillation Based on MATLAB

2014 ◽  
Vol 536-537 ◽  
pp. 1532-1536
Author(s):  
Xin Ke Gou ◽  
Bin Qian ◽  
Run Qing Bai
Keyword(s):  
Power System ◽  
Simulation Model ◽  
Low Frequency ◽  
Power System Stabilizer ◽  
Actual Situation ◽  
Power System Simulation ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Low Frequency Oscillations ◽  
System Stabilizer

This paper describes the generation of low frequency oscillations and suppression methods briefly. Observing a phenomenon of low frequency oscillation of Gansu Grid Power and analysis its actual situation. Therefore, we need establish simplified simulation model in MATLAB environment, then do the simulation with the dual power system simulation model which add to power system stabilizer. Simulation results show that: PSS can solve the problem of low frequency oscillations in a region of Gansu steel caused rapid and effective.

Improvement Model Damping Low Frequency Oscillations Presence UPFC by Cuckoo Optimization Algorithm

2016 ◽  
Vol 3 (1) ◽  
pp. 67
Author(s):  
M. Yousefi Anarkooli ◽  
H. Afrakhteh
Keyword(s):  
Optimization Algorithm ◽  
Power Flow ◽  
Low Frequency ◽  
Control Voltage ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Software Environment ◽  
Cuckoo Optimization Algorithm ◽  
Low Frequency Oscillations ◽  
Oscillation Damping

<p>Low frequency oscillation (LFO) is a negative phenomenon repeated for the power system increases the risk of instability. In recent years, power systems stabilizer (PSS) for damping low frequency oscillations is used. With FACTS devices such as integrated power flow controller (UPFC) can control power flow and  transient   stability increase.  So, UPFC low   frequency oscillation damping can be used instead of PSS. UPFC through direct control voltage and low frequency oscillation damping can be improved. In this study, a single linear model of synchronous machine connected to an infinite bus Heffron-Philips in the presence of UPFC to improve low frequency oscillation damping is used. The selection of the output feedback parameters for the UPFC controllers is converted to an optimization problem which is solved by cuckoo optimization algorithm (COA). COA, as a new evolutionary optimization algorithm, is used in multiple applications. This optimization algorithm has a strong ability to find the most optimistic results for dynamic stability improvement. The controller UPFC and damping in MATLAB software environment is designed and simulated. The simulation was performed for a variety of loads and for various loads and more effective UPFC controller electromechanical oscillation damping compared to other algorithm types is shown.</p>

scholarly journals A Robust Direct Parameter Identification of Exponentially Damped Low-Frequency Oscillation in Power Systems

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Zhaobi Chu ◽  
Yuanyuan Pan ◽  
Haiyan Tang ◽  
Min Zhu ◽  
Xueping Dong
Keyword(s):  
Power Systems ◽  
Parameter Identification ◽  
Integral Manifold ◽  
Low Frequency ◽  
Design Parameters ◽  
Damping Factor ◽  
Low Frequency Oscillation ◽  
Use Of Time ◽  
Low Frequency Oscillations ◽  
Wide Range

Low-frequency oscillations in power systems can be modeled as an exponentially damped sinusoid (EDS) signal. Its frequency, damping factor, and amplitude are identified by the robust algorithm proposed in this paper. Under the condition of no noise, the exponentially convergent property of the proposed identification is proved by the use of time scale change, variable transformation, slow integral manifold, averaging method, and Lyapunov stability theorem in sequence. Under the condition of bounded additive noise, the antinoise performance of the identification of each parameter is investigated by the perturbed system theorem and error synthesis principle. The robustness of the proposed method is embodied in the following aspects: the exponential convergence for EDS signal with a wide range of frequency, especially with a rather low frequency; the boundary values of identification errors resulting from high-frequency sinusoidal noise of both frequency and damping factor can be adjusted by tuning the design parameters; and the different effects of the four design parameters on tracking performance and antinoise performance of each parameter identification. Simulation results demonstrate the performance of the algorithm and validate the conclusions.

Renal SNA as the primary mediator of slow oscillations in blood pressure during hemorrhage

2000 ◽  
Vol 279 (3) ◽  
pp. H1299-H1306 ◽  
Author(s):  
Simon C. Malpas ◽  
Don E. Burgess
Keyword(s):  
Blood Pressure ◽  
Time Delays ◽  
Feedback Loop ◽  
Sympathetic Nerve Activity ◽  
Low Frequency ◽  
Strong Increase ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Low Frequency Oscillations ◽  
Mayer Wave

Blood pressure contains a distinct low-frequency oscillation often termed the Mayer wave. This oscillation is caused by the action of the sympathetic nervous system on the vasculature and results from time delays in the baroreflex feedback loop for the control of sympathetic nerve activity (SNA) in response to changes in blood pressure. In this study, we used bilateral renal denervation to test the hypothesis that it is SNA to the kidney that contributes a large portion of the vascular resistance associated with changes in the strength of the slow oscillation in blood pressure. In conscious rabbits, SNA and blood pressure were measured during hemorrhage (blood withdrawal at 1.35 ml · min−1 · kg−1 for 20 min). Spectral analysis identified a strong increase in power at 0.3 Hz in SNA and blood pressure in the initial compensatory phase of hemorrhage before blood pressure started to fall. However, in a separate group of renal denervated rabbits, although the power of the 0.3-Hz oscillation under control conditions in blood pressure was similar, it was not altered during hemorrhage. Wavelet analysis revealed the development of low-frequency oscillations at 0.1 Hz in both intact and denervated animals. In conclusion, we propose that changes in the strength of the oscillation at 0.3 Hz in arterial pressure during hemorrhage are primarily mediated by sympathetic activity directed to the kidney.

ANALYSIS OF STAND RESEARCH RESULTS OF AXIAL DYNAMIC FORCE IN DRILLING BY THREE ROLLER CONE BIT

2019 ◽  
pp. 81-93
Author(s):  
В. М. Мойсишин ◽  
M. V. Lyskanych ◽  
R. A. Zhovniruk ◽  
Ye. P. Majkovych
Keyword(s):  
Low Frequency ◽  
Maximum Energy ◽  
Dynamic Force ◽  
Low Frequency Oscillation ◽  
Drilling Tool ◽  
Rock Destruction ◽  
Frequency Components ◽  
Harmonic Components ◽  
Experimental Values ◽  
Harmful Effects

The purpose of the proposed article is to establish the causes of oscillations of drilling tool and the basic laws of the distribution of the total energy of the process of changing the axial dynamic force over frequencies of spectrum. Variable factors during experiments on the classical plan were the rigidity of drilling tool and the hardness of the rock. According to the results of research, the main power of the process of change of axial dynamic force during drilling of three roller cone bits is in the frequency range 0-32 Hz in which three harmonic frequency components are allocated which correspond to the theoretical values of low-frequency and gear oscillations of the chisel and proper oscillations of the bit. The experimental values of frequencies of harmonic components of energy and normalized spectrum as well as the magnitude of the dispersion of the axial dynamic force and its normalized values at these frequencies are presented. It has been found that with decreasing rigidity of the drilling tool maximum energy of axial dynamic force moves from the low-frequency oscillation region to the tooth oscillation area, intensifying the process of rock destruction and, at the same time, protecting the tool from the harmful effects of the vibrations of the bit. Reducing the rigidity of the drilling tool protects the bit from the harmful effects of the vibrations generated by the stand. The energy reductions in these fluctuations range from 47 to 77%.

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