Water Sensation During Passive Propulsion for Expert and Nonexpert Swimmers

2017 ◽  
Vol 124 (3) ◽  
pp. 662-673 ◽  
Author(s):  
Kenta Kusanagi ◽  
Daisuke Sato ◽  
Yasuhiro Hashimoto ◽  
Norimasa Yamada
Keyword(s):  
Skin Resistance ◽  
National Level ◽  
Absolute Error ◽  
Transformation Method ◽  
Two Dimensional ◽  
Eyes Closed ◽  
Video Recordings ◽  
Linear Transformation Method ◽  
The Mean ◽  
The Difference

This study determined whether expert swimmers, compared with nonexperts, have superior movement perception and physical sensations of propulsion in water. Expert (national level competitors, n = 10) and nonexpert (able to swim 50 m in > 3 styles, n = 10) swimmers estimated distance traveled in water with their eyes closed. Both groups indicated their subjective physical sensations in the water. For each of two trials, two-dimensional coordinates were obtained from video recordings using the two-dimensional direct linear transformation method for calculating changes in speed. The mean absolute error of the difference between the actual and estimated distance traveled in the water was significantly lower for expert swimmers (0.90 ± 0.71 meters) compared with nonexpert swimmers (3.85 ± 0.84 m). Expert swimmers described the sensation of propulsion in water in cutaneous terms as the “sense of flow” and sensation of “skin resistance.” Therefore, expert swimmers appear to have a superior sense of distance during their movement in the water compared with that of nonexpert swimmers. In addition, expert swimmers may have a better perception of movement in water. We propose that expert swimmers integrate sensations and proprioceptive senses, enabling them to better perceive and estimate distance moved through water.

scholarly journals Analysis and Development of Seawater Density Measurement Algorithms Using Arduino Uno and YL-69 Sensor

2020 ◽  
Vol 4 (5) ◽  
pp. 951-956
Author(s):  
Miftahul Walid ◽  
Hozairi ◽  
Madukil Makruf
Keyword(s):  
Sea Water ◽  
Density Measurement ◽  
Absolute Error ◽  
Error Level ◽  
Value Range ◽  
Density Values ◽  
The Mean ◽  
Arduino Uno ◽  
The Difference ◽  
Predicted Values

In this research, an analysis was carried out to develop a measuring instrument for seawater density in salt production using a microcontroller (Arduino Uno) and YL-69 sensor, this sensor was commonly used to measure soil moisture. The experimental method was used in this research to produce initial data in the form of resistance and seawater density values, then calculations are carried out using statistical methods to find equations and produce a constant variable that connects the resistance and seawater density values. The equation was used to compile the algorithm into Arduino Uno. As for the results of this research,  From six experiments conducted, two experiments produced the same sea water density value between the actual and the predicted, namely the 2nd and 5th experiments, while for other experiments there was a difference between the actual and predicted values, however, it was not too significant, the difference occurs between the value range 0 ~ 1, to determine the level of error, use the Mean Square Error (MSE) with an error level of = 0.5 and Mean Absolute Error (MAE) with an error level of = 0.6. The contribution of this research is an algorithm that can predict the density value (baume) based on the resistance value obtained from the YL 69 sensor.

scholarly journals Analysis of incapacitation during +Gz induced loss of consciousness

2021 ◽  
Vol 65 ◽  
pp. 91-96
Author(s):  
MD Sharma ◽  
P Biswal ◽  
N Taneja ◽  
A Agarwal
Keyword(s):  
Air Force ◽  
High Performance ◽  
Age Groups ◽  
Rapid Onset ◽  
Loss Of Consciousness ◽  
Video Recordings ◽  
Operational Capabilities ◽  
Significant Difference ◽  
The Mean ◽  
The Difference

Introduction: Occurrence of G induced loss of consciousness (G-LOC) during centrifuge training is a known entity. The Indian Air Force is currently undertaking high G training of its fighter pilots in High Performance Human Centrifuge (HPHC) which has significantly higher operational capabilities. The study aimed to analyse the incapacitation periods and myoclonic jerks associated with G-LOC occurring during HPHC training. Material and Methods: Records of episodes of 161 G-LOC during closed loop Rapid Onset Rates (ROR) runs over a period of 7 years from 2011 to 2017 were analyzed. The video recordings of these G-LOC episodes were assessed in terms of the participant demographics, +Gz onset rates, incapacitation periods, and presence or absence of myoclonic jerks during the G-LOC episodes. Descriptive statistics was applied to analyze the incapacitation periods and the duration of the myoclonic flail movements. Single tailed t-test was used to analyze the difference between the incapacitation periods of the aircrew who suffered myoclonic flail movements and those who did not. One-way ANOVA was carried out to assess the differences in incapacitation periods, if any, between aircrew of different age groups. Significance was set at P < 0.05. Results: Of these 161 episodes of G-LOC, 43.5% were seen in trainee aircrew. The mean Absolute Incapacitation Period (AIP), Relative Incapacitation Period (RIP) and Total Incapacitation Period (TIP) was 6.9 ± 2.3 s, 12.2 ± 4.7 s, and 19.1 ± 5.5 respectively. Age and flying experience did not show any significant effect with any of the incapacitation periods (p>0.05). The TIP correlated better with the RIP than with the AIP (Pearson’s correlation values of 0.9 and 0.52 respectively). Myoclonic flail movements were witnessed in 25.5% of G-LOC episodes with an average duration of 5.3 s and more than 50% occurring at ≥8Gz. The mean duration of RIP was significantly higher (P=0.03) when G-LOC was associated with myoclonic flail movements, whereas, the duration of AIP did not show any significant difference. Conclusion: The shorter incapacitation periods observed in the study compared to that reported in most of the previous studies could be attributed to the faster Gz offset rates of the present HPHC. Episodes of G-LOC having myoclonic movements were found to have higher relative incapacitation periods. Even though these movements were associated with G-LOC occurring at higher Gz levels, the durations were independent of the Gz levels.

Comparison of Film and Video Techniques for Three-Dimensional DLT Repredictions

1989 ◽  
Vol 5 (4) ◽  
pp. 457-460 ◽  
Author(s):  
Patrick W. Kennedy ◽  
David L. Wright ◽  
Gerald A. Smith
Keyword(s):  
Video Recording ◽  
Three Dimensional ◽  
Transformation Method ◽  
Control Points ◽  
Video Recordings ◽  
Practical Standpoint ◽  
Spatial Coordinates ◽  
Linear Transformation Method ◽  
Three Dimensional Coordinate ◽  
Film And Video

The precision of the kinematic values depends upon the methods of recording a subject’s motion. With the introduction of video recording techniques, questions have arisen concerning the accuracy of video compared with that of 16-mm film. Accordingly, the purpose of this study was to compare the accuracy of the two techniques for point reprediction using the Direct Linear Transformation method. Range poles, serving as boundaries of a cube with 20 known spatial coordinates, were filmed and videotaped. The 20 control points on the film and video recordings were digitized by three individuals. Nine sets of digitized points (three digitizers × three trials) for both film and video were compared with the actual three-dimensional coordinate values. Resultant mean errors were statistically significantly different (p<.05), 4.8 mm and 5.8 mm for film and video, respectively. However, from a practical standpoint the video error was only .29% of the calibrated field compared to .24% for film. Thus it is concluded that video techniques are comparable in accuracy to 16-mm filming methods.

Implementation of a Mixing Length Turbulence Formulation Into the Dynamic Wake Meandering Model

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Rolf-Erik Keck ◽  
Dick Veldkamp ◽  
Helge Aagaard Madsen ◽  
Gunner Larsen
Keyword(s):  
Cross Section ◽  
Turbulent Mixing ◽  
Eddy Viscosity ◽  
High Fidelity ◽  
Mixing Length ◽  
Two Dimensional ◽  
Wake Region ◽  
Mean Velocity ◽  
The Mean ◽  
The Difference

The work presented in this paper focuses on improving the description of wake evolution due to turbulent mixing in the dynamic wake meandering (DWM) model. From wake investigations performed with high-fidelity actuator line simulations carried out in ELLIPSYS3D, it is seen that the current DWM description, where the eddy viscosity is assumed to be constant in each cross-section of the wake, is insufficient. Instead, a two-dimensional eddy viscosity formulation is proposed to model the shear layer generated turbulence in the wake, based on the classical mixing length model. The performance of the modified DWM model is verified by comparing the mean wake velocity distribution with a set of ELLIPSYS3D actuator line calculations. The standard error (defined as the standard deviation of the difference between the mean velocity field of the DWM and the actuator line model), in the wake region extending from 3 to 12 diameters behind the rotor, is reduced by 27% by using the new eddy viscosity formulation.

A comparison of the classification systems of luminous stars in the northern Milky Way II and IV, for stars assigned two-dimensional spectral types from objective-prism plates

1966 ◽  
Vol 24 ◽  
pp. 70-73
Author(s):  
C. B. Stephenson
Keyword(s):  
Milky Way ◽  
Classification Systems ◽  
Two Dimensional ◽  
Joint Project ◽  
Ob Stars ◽  
Luminosity Class ◽  
Objective Prism ◽  
The Mean ◽  
The Difference ◽  
Hydrogen Lines

For some years a survey for early-type luminous stars in the northern Milky Way has been underway at the Warner and Swasey Observatory and the Hamburg Observatory, as a joint project by the two institutions (1). With the aid of ultraviolet-transmitting objective prisms (Schott UBK7 glass), it has been possible at both institutions to recognize OB stars at a dispersion of about 600Å/mm. Moreover, the appearance of the Balmer discontinuity at low dispersion affords a valuable aid to two-dimensional classification of stars of late B to late F types (2, 3). These two-dimensional classifications, which are based essentially upon the appearance of the continuum (especially the Balmer discontinuity), the hydrogen lines, the K line, and the G band, are assigned in the MK classification nomenclature since they are well correlated with classifications made by means of the real MK classification criteria. The quality of the correlation depends upon location in the HR diagram, but the random probable error appears to be upward of one MK luminosity class and about a quarter of a full letter division in temperature class, except that luminosity class IV is nowhere well distinguished from class V, and class Iab is not really well distinguished from Ia and Ib.The present Cleveland system of assigning two-dimensional spectral types to stars from ultraviolet-included objective-prism plates tends to assign lower luminosities than those of the LS II (–LS I?) system. This fact alone accounts for certainly most of the difference between the numbers of stars assigned two-dimensional spectral types in LS II and in LS IV. The origin of this systematic difference of over a luminosity class is not well explained, but the difference is hardly alarming. The numbers of OB stars in the two catalogues are quite comparable and this is consistent with the fact that no classification system difference for OB stars is known to exist between these two catalogues.Slit spectrograms so far available support the belief that LS IV agrees better in the mean with the MK system than does LS II, though LS IV may also be slightly overluminous in the mean. There is one factor always tending to confuse the transformation from this objective-prism system to MK spectral types: stars having abnormally strong Balmer discontinuities will usually be included in our catalogues with some kind of MK classification, While those with abnormally weak Balmer discontinuities will more often be excluded or assigned to the OB group. This problem is by no means so serious as to detract significantly from the desirability of making objective-prism surveys that pay special heed to the Balmer discontinuity.

Comparison of 13 formulas for IOL power calculation with measurements from partial coherence interferometry

2020 ◽  
pp. bjophthalmol-2020-316193
Author(s):  
Giacomo Savini ◽  
Marco Di Maita ◽  
Kenneth J Hoffer ◽  
Kristian Næser ◽  
Domenico Schiano-Lomoriello ◽  
...  
Keyword(s):  
Anterior Chamber Depth ◽  
Case Series ◽  
Absolute Error ◽  
Partial Coherence ◽  
Power Calculation ◽  
Partial Coherence Interferometry ◽  
Iol Power Calculation ◽  
Iol Power ◽  
The Mean ◽  
The Difference

Background/aimsTo compare the accuracy of 13 formulas for intraocular lens (IOL) power calculation in cataract surgery.MethodsIn this retrospective interventional case series, optical biometry measurements were entered into these formulas: Barrett Universal II (BUII) with and without anterior chamber depth (ACD) as a predictor, EVO 2.0 with and without ACD as a predictor, Haigis, Hoffer Q, Holladay 1, Holladay 2AL, Kane, Næser 2, Pearl-DGS, RBF 2.0, SRK/T, T2 and VRF. The mean prediction error (PE), median absolute error (MedAE), mean absolute error and percentage of eyes with a PE within ±0.25, ±0.50, ±0.75 and ±1.00 diopters (D) were calculated.ResultsTwo hundred consecutive eyes were enrolled. With all formulas, the mean PE was zero. The BUII with no ACD had the lowest standard deviation (±0.343 D), followed by the T2 (0.347 D), Kane (0.348 D), EVO 2.0 with no ACD (0.348 D) and BUII with ACD (0.353 D) formulas. The difference among the MedAEs of all formulas was statistically significant (p<0.0001); the lowest values were achieved with the Kane (0.214 D), RBF 2.0 (0.215 D), BUII with and without ACD (0.218 D) and SRK/T (0.223 D). A percentage ranging from 80% to 88.5% of eyes showed a PE within ±0.50 D and all formulas achieved more than 50% of eyes with a PE within ±0.25 D.ConclusionAll investigated formulas achieved good results; there was a tendency towards better outcomes with newer formulas. Traditional formulas can still be considered an accurate option.

scholarly journals Wake Decay: Effect of Freestream Swirl

1997 ◽  
Author(s):  
J. M. Brookfield ◽  
I. A. Waitz ◽  
J. Sell
Keyword(s):  
Three Dimensional ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Mixing Rate ◽  
Rotating Blade ◽  
Blade Row ◽  
The Mean ◽  
The Difference ◽  
Fan Blade

A study of the effects of freestream swirl on the decay characteristics of wakes shed from a rotating blade row is presented. The freestream swirl behind the rotor causes the wakes to skew tangentially, stretching the wakes as they are convected from the rotor to the stator. The effect of stretching on wake decay is illustrated using a simplified two-dimensional model. The model is described and the results are compared to 1) measurements from a two-dimensional cascade facility where no stretching or skewing of the wakes occurs, 2) solutions obtained using a three-dimensional, Reynolds-averaged Navier-Stokes solver, and 3) experimental wake measurements taken behind a low hub-to-tip ratio fan. For typical fan geometries with hub-to-tip ratios of approximately 0.5 and rotor-stator spacings of one to two rotor chord lengths, the wake can be stretched by over 50 percent. The stretching increases the mixing rate which leads to a reduction in the mean wake velocity deficit of approximately thirty percent and a widening of the wake of about fifteen percent. These effects account for much of the difference seen between cascade wake measurements and those taken behind rotating fan blade rows. It is therefore important to include such effects when using cascade data for prediction of fluid mechanic, acoustic, or structural phenomena associated with fan wakes. Finally, the study also suggests a potential for small (< 3 dB) reductions in wake-stator interaction noise through tailoring the fan loading distribution to produce particular span wise wake decay characteristics.

scholarly journals Correcting for Gaussian Aerial Smoothing

1955 ◽  
Vol 8 (1) ◽  
pp. 54 ◽  
Author(s):  
RN Bracewell
Keyword(s):  
Two Dimensional ◽  
The Mean ◽  
Standard Deviations ◽  
The Difference

Let a. two-dimensional survey with a Gaussian aerial beam establish values at intervals of standard deviations. Then the correction for aerial smoothing is simply calculated as the difference between the value to be corrected and the mean of the neighbouring four values.

scholarly journals Air quality over Europe: modeling gaseous and particulate pollutants and the effect of precursor emissions

2013 ◽  
Vol 13 (3) ◽  
pp. 6681-6705
Author(s):  
E. Tagaris ◽  
R. E. P. Sotiropoulou ◽  
N. Gounaris ◽  
S. Andronopoulos ◽  
D. Vlachogiannis
Keyword(s):  
Air Quality ◽  
Western Europe ◽  
Model Performance ◽  
Absolute Error ◽  
Low Concentrations ◽  
Particulate Pollutants ◽  
The Mean ◽  
The Difference ◽  
Eastern And Western Europe ◽  
Pm2.5 Emissions

Abstract. Air quality over Europe using Models-3 (i.e. CMAQ, MM5, SMOKE) modeling system is performed for winter (i.e. January, 2006) and summer (i.e. July, 2006) months with the 2006 TNO gridded anthropogenic emissions database. Higher ozone concentrations are illustrated in southern Europe while higher NO2 concentrations are simulated over western Europe. Elevated SO2 concentrations are simulated over eastern Europe while elevated PM2.5 levels are simulated over eastern and western Europe. Results suggest that NO2 and PM2.5 are underpredicted, SO2 is overpredicted while Max8hrO3 is overpredicted for low concentrations and is underpredicted for the higher ones. Speciated PM2.5 components suggest that NO3 is dominant during winter in western Europe and in a few eastern countries due to the high NO2 concentrations. During summer NO3 is dominant only in regions with elevated NH3 emissions. For the rest of the domain SO4 is dominant. Low OC concentrations are simulated mainly due to the uncertain representation of SOA formation. The difference between observed and predicted concentrations for each country is assessed for the gaseous and particulate pollutants. The simultaneous precursor emissions change applying scaling factors on NOx, SO2 and PM2.5 emissions based on the observed/predicted ratio for each country seems to statistically enhance model performance (in gaseous pollutants the improvement in root mean square is up to 5.6 ppbV, in the index of agreement is up to 0.3 and in the mean absolute error is up to 4.2 ppbV while the related values in PM2.5 are 4.5 μg m−3, 0.2 and 3.5 μg m−3, respectively).

scholarly journals A two-dimensional partially coherent geometric model of a distributed radar object

2020 ◽  
pp. 28-36
Author(s):  
Aleksey Kiselev ◽  
Keyword(s):  
Distribution Function ◽  
Correlation Matrix ◽  
Numerical Experiments ◽  
Geometric Model ◽  
Transformation Method ◽  
Two Dimensional ◽  
Noise Distribution ◽  
Linear Transformation Method ◽  
The Given ◽  
Matching Moments

The possibility of the substitution of a two-dimensional distributed radar object by a 4-point partly coherent model is considered. As a criterion of adequacy we accepted the coincidence of the angle noise distribution function for the model and the substituted object. It is shown that the proposed four-point configuration can be represented as two orthogonal equivalent two-point models. Relations are obtained for calculating the parameters (power ratios of the signals and coefficients of the correlation matrix) of the signals of the four-point model through the parameters of the signals of the equivalent two-point models. The signal parameters of the equivalent two-point models can be calculated for the given parameters of the joint distribution of azimuthal and elevation noises. These relations obtained for the two-dimensional model are the result of this work. The results obtained were tested using numerical experiments for the test values of the parameters of the angle noise distribution function. To generate samples of signals whose correlation matrix has the required form the linear transformation method was used. The parameters of the distribution function of the simulated angle noise were estimated by the method of matching moments. The results of numerical experiments confirm the reliability of the obtained ratios. They can be used in mathematical and simulation modeling of distributed radar objects.

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