Constructing quasi-linear V̇o2 responses from nonlinear parameters

2016 ◽  
Vol 120 (2) ◽  
pp. 121-129 ◽  
Author(s):  
Samuel L. Wilcox ◽  
Ryan M. Broxterman ◽  
Thomas J. Barstow
Keyword(s):  
Control System ◽  
Time Constant ◽  
Incremental Exercise ◽  
Integrative Model ◽  
Ramp Rate ◽  
Apparent Contradiction ◽  
Nonlinear Parameters ◽  
Mean Response Time ◽  
Parameter Values ◽  
Kinetics Parameter

Oxygen uptake (V̇o2) kinetics have been shown to be governed by a nonlinear control system across a range of work rates. However, the linearity of the V̇o2 response to ramp incremental exercise would appear to be the result of a linear control system. This apparent contradiction could represent a balancing of changing V̇o2 kinetics parameter values across a range of work rates. To test this, six healthy men completed bouts of ramp incremental exercise at 15, 30, and 60 W/min (15R, 30R, 60R, respectively) and four bouts of an extended-step incremental exercise. V̇o2 parameter values were derived from the step exercise using two monoexponential models: one starting at time zero and encompassing the entire stage (MONO), and the other truncated to the first 5 min and allowing a time delay (5TD). The resulting parameter values were applied to an integrative model to estimate the ramp responses. As work rate increased, gain values increased ( P < 0.001 for MONO and 5TD), as did mean response time (or time constant) values (MONO: P < 0.001; 5TD: P = 0.003). Up to maximal V̇o2 (V̇o2 max), the gains of the estimated ramp responses from both models were not different from the gains of the actual observed V̇o2 responses for 15R and 30R (15R: 11.3 ± 1.2, 11.7 ± 0.7, 10.9 ± 0.3; 30R: 10.5 ± 0.8, 11.0 ± 0.5, 10.7 ± 0.3 ml O2·min−1·W−1, for actual, MONO, 5TD, respectively) but were significantly greater for 60R (8.7 ± 1.0, 9.9 ± 0.4, 10.3 ± 0.3 ml O2·min−1·W−1 for actual, MONO, 5TD, respectively). Up to 80%V̇o2 max gain values were not significantly different for any ramp rate ( P > 0.05 for all). We conclude that the apparent linearity of the V̇o2 response to ramp incremental exercise is consequent to a balancing of increasing time constant and gain parameter values.

Simulation and Parameter Optimization for Vibration Control System of MLRS Launcher

2014 ◽  
Vol 668-669 ◽  
pp. 526-531
Author(s):  
Xian Zhao ◽  
De Qing Luo
Keyword(s):  
Control System ◽  
Control Mechanism ◽  
Vibration Suppression ◽  
Structural Parameters ◽  
Pulse Frequency ◽  
Structure Parameter ◽  
Pulse Control ◽  
Lateral Direction ◽  
Parameter Values ◽  
Rocket System

Vibration suppression of the launcher is an important way to improve the firing accuracy of Multiple Launch Rocket System (MLRS). In order to get a better control result from the course that pulse control mechanism generates pulses to restrain the vibration of MLRS launcher, this paper analyzed the process that pulse thruster control the vibration of launcher under the modulation of pulse width and pulse frequency (PWPF) modulator. And the simulation model of the control system is established through the SIMULINK software in MATLAB. Under repeated modifications of the structural parameters of PWPF modulator, the influence laws of these parameters are found out, and the best structure parameter values are obtained. The final simulation result shows that the vibration in the pitch and lateral direction is greatly reduced. It is a big help to improve the firing accuracy of MLRS.

scholarly journals Establishing the V̇o2 versus constant-work-rate relationship from ramp-incremental exercise: simple strategies for an unsolved problem

2019 ◽  
Vol 127 (6) ◽  
pp. 1519-1527 ◽  
Author(s):  
Danilo Iannetta ◽  
Rafael de Almeida Azevedo ◽  
Daniel A. Keir ◽  
Juan M. Murias
Keyword(s):  
Lactate Threshold ◽  
Unsolved Problem ◽  
Critical Power ◽  
Work Rate ◽  
Incremental Exercise ◽  
Mean Response Time ◽  
Constant Work Rate ◽  
Ramp Exercise ◽  
The Mean ◽  
Highly Correlated

The dissociation between constant work rate of O2 uptake (V̇o2) and ramp V̇o2 at a given work rate might be mitigated during slowly increasing ramp protocols. This study characterized the V̇o2 dynamics in response to five different ramp protocols and constant-work-rate trials at the maximal metabolic steady state (MMSS) to characterize 1) the V̇o2 gain (G) in the moderate, heavy, and severe domains, 2) the mean response time of V̇o2 (MRT), and 3) the work rates at lactate threshold (LT) and respiratory compensation point (RCP). Eleven young individuals performed five ramp tests (5, 10, 15, 25, and 30 W/min), four to five time-to-exhaustions for critical power estimation, and two to three constant-work-rate trials for confirmation of the work rate at MMSS. G was greatest during the slowest ramp and progressively decreased with increasing ramp slopes (from ~12 to ~8 ml·min−1·W−1, P < 0.05). The MRT was smallest during the slowest ramp slopes and progressively increased with faster ramp slopes (1 ± 1, 2 ± 1, 5 ± 3, and 10 ± 4, 15 ± 6 W, P < 0.05). After “left shifting” the ramp V̇o2 by the MRT, the work rate at LT was constant regardless of the ramp slope (~150 W, P > 0.05). The work rate at MMSS was 215 ± 55 W and was similar and highly correlated with the work rate at RCP during the 5 W/min ramp ( P > 0.05, r = 0.99; Lin’s concordance coefficient = 0.99; bias = −3 W; root mean square error = 6 W). Findings showed that the dynamics of V̇o2 (i.e., G) during ramp exercise explain the apparent dichotomy existing with constant-work-rate exercise. When these dynamics are appropriately “resolved”, LT is constant regardless of the ramp slope of choice, and RCP and MMSS display minimal variations between each other. NEW & NOTEWORTHY This study demonstrates that the dynamics of V̇o2 during ramp-incremental exercise are dependent on the characteristics of the increments in work rate, such that during slow-incrementing ramp protocols the magnitude of the dissociation between ramp V̇o2 and constant V̇o2 at a given work rate is reduced. Accurately accounting for these dynamics ensures correct characterizations of the V̇o2 kinetics at ramp onset and allows appropriate comparisons between ramp and constant-work-rate exercise-derived indexes of exercise intensity.

Research on the Relationship between Speed Control System and Electromechanical Oscillations

2015 ◽  
Vol 710 ◽  
pp. 47-52 ◽  
Author(s):  
Ya Qing Zhu ◽  
Min Zhong ◽  
Yu Jia Ma ◽  
Feng Ping Pan ◽  
Ling Ling Shi ◽  
...  
Keyword(s):  
Control System ◽  
Steam Turbine ◽  
Time Constant ◽  
Response Rate ◽  
Speed Control ◽  
Servo Motor ◽  
Speed Control System ◽  
Hydraulic Servo ◽  
The Impact ◽  
The Relationship

The system damping of electric power systems is influenced by factors of many aspects. In this paper, we analyzed the impact of speed control system on the damping of the whole system in consideration of the Pole-Zero Analysis. The result shows that simple speed control would damp the oscillation, while the power-frequency control would excite the oscillation. Furthermore, the effect of steam turbine response rate on the system damping is analyzed. The time constant of hydraulic servo-motor would determine the response rate of the steam turbine, and as a result, an inflection point exists on the curve which describes the relationship between hydraulic servo-motor time constant and system damping. The result demonstrates that the characteristics of system damping can be used in parameter debugging of steam turbine.

Measurements and analysis of time constant of the KRISS dynamic flow control system

Measurement ◽  
2012 ◽  
Vol 45 (10) ◽  
pp. 2456-2458 ◽  
Author(s):  
S.S. Hong ◽  
Wakil Khan ◽  
J.Y. Lim ◽  
Y.H. Shin ◽  
J.W. Chung ◽  
...  
Keyword(s):  
Control System ◽  
Flow Control ◽  
Time Constant ◽  
Dynamic Flow ◽  
Flow Control System

Improved Algorithm for Set Inversion With Application to a Jet Engine Control System

2004 ◽  
Vol 127 (1) ◽  
pp. 163-166
Author(s):  
P. S. V. Nataraj ◽  
A. K. Prakash ◽  
S. Srivastava
Keyword(s):  
Control System ◽  
Robust Stability ◽  
Interval Analysis ◽  
Speed Control ◽  
System Stability ◽  
Engine Control ◽  
Control Loop ◽  
Jet Engine ◽  
Engine Control System ◽  
Parameter Values

We present an algorithm to characterize the set S={x∊Rl:f(x)>0}=f−1(]0,∞[m) in the framework of set inversion using interval analysis. The proposed algorithm improves on the algorithm of Jaulin et al. (Jaulin, L., Kieffer, M., Didrit, O., and Walter, E., 2001, Applied Interval Analysis, Springer, London). The improvements exploit the powerful tool of monotonicity. We test and compare the performance of the proposed algorithm with that of Jaulin et al. in characterizing the domain of robust stability for the speed control loop of a jet engine. The results of testing show that the proposed algorithm encloses S more accurately, meaning that it gives a larger region of compensator parameter values for which the system stability is guaranteed and a smaller region of the same for which the system stability is indeterminate.

scholarly journals Oxygen Uptake Kinetics in Endurance Trained Youth and Adult Cyclists

2021 ◽  
pp. 398-403
Author(s):  
Bernhard Prinz ◽  
Manfred Zöger ◽  
Harald Tschan ◽  
Alfred Nimmerichter
Keyword(s):  
Oxygen Uptake ◽  
Time Constant ◽  
Oxygen Uptake Kinetics ◽  
Primary Response ◽  
Uptake Kinetics ◽  
Repeated Measure ◽  
Adult Age ◽  
Mean Response Time ◽  
Training History ◽  
Rate Intensity

Previous studies reported faster pulmonary oxygen uptake kinetics at the onset of exercise in untrained youth compared with adults. Whether or not these differences are identical for trained groups have not been examined. The purpose of this study was to compare ̇VO2 kinetics of youth and adult cyclists at moderate and heavy-intensity exercise. Thirteen adult (age: 23.2 ± 4.8 years; ̇VO2peak 68.4 ± 6.8 mL·min-1.kg-1) and thirteen youth cyclists (age: 14.3 ± 1.5 years; ̇VO2peak 61.7 ± 4.3 mL·min-1.kg-1) completed a series of 6-min square wave exercises at moderate and heavy-intensity exercise at 90 rev·min-1. A two-way repeated-measure ANOVA was conducted to identify differences between groups and intensities. The time constant, time delay and the mean response time were not significantly different between youth and adult cyclists (p > 0.05). We found significant differences between intensities, with a faster time constant during moderate than heavy-intensity exercise in youth (24.1 ± 7.0 s vs. 31.8 ± 5.6 s; p = 0.004) and adults (22.7 ± 5.6 s vs. 28.6 ± 5.7 s; p < 0.001). The present data suggest that the effect of training history in adult cyclists compensate for the superior primary response of the oxygen uptake kinetics typically seen in youth compared to adults. Furthermore, the ̇VO2 response is dependent of work rate intensity in trained youth and adult cyclists.

scholarly journals Intracranial pressure dynamics in patients with acute brain damage

1997 ◽  
Vol 82 (4) ◽  
pp. 1270-1282 ◽  
Author(s):  
M. Ursino ◽  
C. A. Lodi ◽  
S. Rossi ◽  
N. Stocchetti
Keyword(s):  
Intracranial Pressure ◽  
Brain Damage ◽  
Blood Volume ◽  
Time Constant ◽  
Cerebral Blood Volume ◽  
Volume Index ◽  
Parameter Estimates ◽  
Time Pattern ◽  
Pressure Dynamics ◽  
Parameter Values

Ursino, M., C. A. Lodi, S. Rossi, and N. Stocchetti.Intracranial pressure dynamics in patients with acute brain damage. J. Appl. Physiol. 82(4): 1270–1282, 1997.—The time pattern of intracranial pressure (ICP) during pressure-volume index (PVI) tests was analyzed in 20 patients with severe acute brain damage by means of a simple mathematical model. In most cases, a satisfactory fitting between model response and patient data was achieved by adjusting only four parameters: the cerebrospinal fluid (CSF) outflow resistance, the intracranial elastance coefficient, and the gain and time constant of cerebral autoregulation. The correlation between the parameter estimates was also analyzed to elucidate the main mechanisms responsible for ICP changes in each patient. Starting from information on the estimated parameter values and their correlation, the patients were classified into two main classes: those with weak autoregulation (8 of 20 patients) and those with strong autoregulation (12 of 20 patients). In the first group of patients, ICP mainly reflects CSF circulation and passive cerebral blood volume changes. In the second group, ICP exhibits paradoxical responses attributable to active changes in cerebral blood volume. Moreover, in two patients of the second group, the time constant of autoregulation is significantly increased (>40 s). The correlation between the parameter estimates was significantly different in the two groups of patients, suggesting the existence of different mechanisms responsible for ICP changes. Moreover, analysis of the correlation between the parameter estimates might give information on the directions of parameter changes that have a greater impact on ICP.

Sub-Nanometer Resolution Positioning Device Driven by New Type of Linear Motor with Linear Ball Guideways – Considering Time Lag of Electric Control System –

2011 ◽  
Vol 5 (6) ◽  
pp. 832-841 ◽  
Author(s):  
Toshiharu Tanaka ◽  
◽  
Jiro Otsuka ◽  
Ikuro Masuda ◽  
Yasuaki Aoyama ◽  
...  
Keyword(s):  
Control System ◽  
Time Constant ◽  
Current System ◽  
Time Lag ◽  
Linear Motor ◽  
Current Control ◽  
Nonlinear Spring ◽  
Electric Control ◽  
Positioning Device ◽  
New Type

We have developed an ultra-precision positioning device that has the following characteristics: 1) The 210 mm strokes stage is driven by a new type of linear motor called “Tunnel Actuator (TA).” 2) The stage has very rigid structure so as not to cause vibration and to achieve high resolution for its feed-back system. 3) The stage is supported by linear ball guideways that have nonlinear spring behavior in the small stroke range. 4) Much attention has been paid to the time lag of the electric control system in the PID control using a linear encoder of 0.034 nm resolution for the feed-back system. The electric control system compensates for the disturbance of induced electromotive voltage that is generated in proportion to the stage velocity. We have studied how the equivalent time constant T of the control system affects the stage displacement deviation Δx when the command of stage displacement xr is kept at zero. The following results have been obtained: 1)With a decrease in time constant T of the current control system, the change in the motor current Io becomes smaller, and, at the same time, the change in stage deviation Δx becomes smaller. 2) At the smallest time constant T of the current system, a displacement resolution of 0.2 nm has been obtained under the nonlinear spring behavior of linear ball guideways. 3) There is a possibility of obtaining a displacement resolution of less than 0.1 nm with a further decrease in T.

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