Influence of Curve Sharpness on Torsional Loading of the Tibia in Running

2002 ◽  
Vol 18 (3) ◽  
pp. 218-230 ◽  
Author(s):  
Ryuji Kawamoto ◽  
Yusuke Ishige ◽  
Koji Watarai ◽  
Senshi Fukashiro
Keyword(s):  
High Speed ◽  
Mean Value ◽  
Rigid Bodies ◽  
Rate Of Change ◽  
Quasi Equilibrium ◽  
Running Injuries ◽  
Curved Track ◽  
The Mean ◽  
Free Body ◽  
As Stress

The purpose of this study was to test quantitatively the hypothesis that, as runners run along a more sharply curved track, greater torsional moments act on their tibiae. Six male participants were asked to run along a straight track and along counterclockwise curved tracks with turn radii of 15 m (gentle) and 5 m (sharp) at 3.5 m s–1. Data were collected using two high-speed cameras and force platforms. Each participant’s left (corresponding to the inside of the curves) foot and tibia were modeled as a system of coupled rigid bodies. For analysis, net axial moments acting on both ends of the tibia were calculated using free-body analysis. The torsional moment acting on the tibia was determined from the quasi-equilibrium balance of the tibial axial moments based on the assumption that the rate of change of the angular momentum about the tibial axis was negligible. The results showed that the torsional moments, which were in the direction of external rotational loading of the proximal tibiae, increased as the track curvature became sharper. Furthermore, the mean value of the maximum torsional moments, while running on a sharply curved track (28.5 Nm), was significantly higher than the values obtained while running on a straight track (11.0 Nm, p < .01) and on a gently curved track (12.2 Nm, p < .01). In conclusion, the present study has quantitatively confirmed that as runners run along a more sharply curved track, greater torsional moments act on their tibiae. The findings imply that athletes prone to tibial running injuries such as stress fractures should avoid repetitive running on sharply curved paths.

Determination of oxygenated, mixed venous blood CO2 tension by a breath-holding method

1960 ◽  
Vol 15 (2) ◽  
pp. 225-228 ◽  
Author(s):  
John H. Knowles ◽  
William Newman ◽  
Wallace O. Fenn
Keyword(s):  
Venous Blood ◽  
Mean Value ◽  
Rate Of Change ◽  
Breath Holding ◽  
Mixed Venous Blood ◽  
Clinical Method ◽  
Straight Line ◽  
Zero Rate ◽  
The Mean

At the end of a normal expiration the subject inhaled a given volume of gas mixtures containing different concentrations of CO2 in O2 from 5 to 17%. These were held in the lung for 3 and then again for 12 seconds and were then expired and analyzed. Analyses were made with an infrared analyzer and times were obtained from the graphical record. If the rate of change of CO2 tension is plotted against the mean CO2 tension a straight line results which passes through zero rate at the tension which equals the tension of CO2 in the mixed oxygenated venous blood. From the slope of this straight line it is possible to calculate the cardiac output if the lung volume and slope of the CO2 dissociation curve of the blood are known. Data are presented from 37 experiments on 10 subjects. The method is believed to be theoretically sound but has not been validated as a practical clinical method. Occasional erratic points were obtained, especially in untrained subjects. The standard error of the mean value for venous CO2 tension was 1.9 mm Hg. Submitted on July 13, 1959

Random response of dielectric elastomer balloon to electrical or mechanical perturbation

2016 ◽  
Vol 28 (2) ◽  
pp. 195-203 ◽  
Author(s):  
Xiaoling Jin ◽  
Zhilong Huang
Keyword(s):  
Joint Probability ◽  
Stochastic Averaging ◽  
Stretch Ratio ◽  
Dielectric Elastomer ◽  
Mean Value ◽  
Rate Of Change ◽  
Random Response ◽  
First Case ◽  
Special Cases ◽  
The Mean

Random response of dielectric elastomer balloon disturbed by electrical or mechanical fluctuation is analytically investigated in this article. The stochastic differential equation governing the oscillating behavior around the stable equilibrium position is first derived by introducing the translation transformation. The stationary joint probability density about the disturbing stretch ratio and its rate of change is analytically established by adopting the stochastic averaging of energy envelope; the statistics quantities, such as the mean value and the standard deviation of the disturbing stretch ratio, are then subsequently calculated. Two special cases, the first case with only voltage fluctuation and the second one with only pressure variation, are discussed in detail, and the random response properties are summarized. The accuracy of the analytical solution is verified by comparing with the Monte Carlo simulation for the perturbation with weak intensity, and the valid ranges for the mean voltage and pressure are illustrated. This work provides an effective technique to evaluate the detection precision of new type of sensors based on the dielectric elastomer.

scholarly journals Derivation of Motor Mean Phase Currents in PMSM Drives Operating with Low Switching-to-Fundamental Frequency Ratio

2019 ◽  
Vol 4 (1) ◽  
pp. 95-102
Author(s):  
Leszek Jarzebowicz
Keyword(s):  
Fundamental Frequency ◽  
Frequency Ratio ◽  
High Speed ◽  
Pulse Width Modulation ◽  
Permanent Magnet Synchronous Motor ◽  
Sampling Technique ◽  
Mean Value ◽  
High Rate ◽  
Linear Current ◽  
The Mean

AbstractPulse width modulation (PWM) of inverter output voltage causes the waveforms of motor phase currents to consist of distinctive ripples. In order to provide suitable feedback for the motor current controllers, the mean value must be extracted from the currents’ waveforms in every PWM cycle. A common solution to derive the mean phase currents is to sample their value at the midpoint of a symmetrical PWM cycle. Using an assumption of linear current changes in steady PWM subintervals, this midpoint sample corresponds to the mean current in the PWM cycle. This way no hardware filtering or high-rate current sampling is required. Nevertheless, the assumption of linear current changes has been recently reported as over simplistic in permanent magnet synchronous motor (PMSM) drives operating with low switching-to-fundamental frequency ratio (SFFR). This, in turn, causes substantial errors in the representation of the mean phase currents by the midpoint sample. This paper proposes a solution for deriving mean phase currents in low SFFR PMSM drives, which does not rely on the linear current change assumption. The method is based on sampling the currents at the start point of a PWM cycle and correcting the sampled value using a model-based formula that reproduces the current waveforms. Effectiveness of the method is verified by simulation for an exemplary setup of high-speed PMSM drive. The results show that the proposed method decreases the error of determining the mean phase currents approximately 10 times when compared to the classical midpoint sampling technique.

A Study on Sustainability of Contemporary Cropping Systems in Bam

2020 ◽  
Vol 7 (10) ◽  
pp. 78-88
Author(s):  
Fatemeh Zarei ◽  
Somaye Baniasadi
Keyword(s):  
Sustainable Agriculture ◽  
Social Participation ◽  
Market Access ◽  
Cropping Systems ◽  
Cropping System ◽  
Mean Value ◽  
Rate Of Change ◽  
Palm Trees ◽  
Agricultural Knowledge ◽  
The Mean

The study was conducted in Bam in 2019 to develop an index to quantify sustainability of cropping systems in the region. The studied cropping systems included single-cropping systems (palm trees) and multi-cropping systems (citrus, palm trees and alfalfa). The studied indices included economic, social, agricultural indices, as well as, personal features, market access, features of communication, education-extension activities, sustainable agricultural knowledge, attitude towards sustainable agriculture, and obstacles facing sustainable agriculture. The results indicated that the amount of sustainability index was lower than the mean value in 0.56% of the farms and this index was higher than the mean value in 0.44% of the others. Comparison of the mean value of sustainability indices in the studied cropping systems indicated that the mean indices of the type of cropping system, attitude towards sustainable agriculture and extension training activities in multi-cropping systems were more than single crops. The mean indices in social participation and the obstacles facing sustainable agriculture in single cropping systems was more than the multi-cropping ones. Some indices including social participation, sustainable agricultural knowledge and education-extension activities in multivariate regression model  remained in the final model as variables that had the largest contribution in the rate of change in the dependent variable (sustainability) and explained = 60% of the changes in the dependent variable. The study showed that the sustainability of multi-cropping systems was more than the single-cropping ones.

scholarly journals On the Boundary between Nonlinear Jump Phenomenon and Linear Response of Hypoid Gear Dynamics

2011 ◽  
Vol 2011 ◽  
pp. 1-13
Author(s):  
Jun Wang ◽  
Teik C. Lim
Keyword(s):  
Linear Response ◽  
High Speed ◽  
Mean Value ◽  
Dynamic Mesh ◽  
Jump Discontinuity ◽  
Hypoid Gear ◽  
Jump Phenomenon ◽  
The Mean ◽  
Primary Focus ◽  
Point Line

A nonlinear time-varying (NLTV) dynamic model of a hypoid gear pair system with time-dependent mesh point, line-of-action vector, mesh stiffness, mesh damping, and backlash nonlinearity is formulated to analyze the transitional phase between nonlinear jump phenomenon and linear response. It is found that the classical jump discontinuity will occur if the dynamic mesh force exceeds the mean value of tooth mesh force. On the other hand, the propensity for the gear response to jump disappears when the dynamic mesh force is lower than the mean mesh force. Furthermore, the dynamic analysis is able to distinguish the specific tooth impact types from analyzing the behaviors of the dynamic mesh force. The proposed theory is general and also applicable to high-speed spur, helical and spiral bevel gears even though those types of gears are not the primary focus of this paper.

scholarly journals Two Classes of Fast Solar Wind Streams: Their Origin and Influence on the Galactic Cosmic Ray Intensity

1980 ◽  
Vol 91 ◽  
pp. 399-401
Author(s):  
N. Iucci ◽  
M. Parisi ◽  
M. Storini ◽  
G. Villoresi
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Cosmic Ray ◽  
Mean Value ◽  
Proton Density ◽  
Fast Solar Wind ◽  
Cosmic Ray Intensity ◽  
Proton Temperature ◽  
The Mean ◽  
Galactic Cosmic Ray

The analysis of solar wind (bulk velocity v, proton density n, proton temperature T) and magnetic field (B) data in the years 1964-1974 makes possible to identify two main classes of high-speed streams (ΔV = (vm - vo)≥ 100 km/sec, vm being the maximum daily mean speed and vo the mean value between the speeds immediately preceding and following the stream; duration Δt ≥ 2 days):

Hydrodynamics of swimming in the water boatman, Cenocorixa bifida

1986 ◽  
Vol 64 (8) ◽  
pp. 1606-1613 ◽  
Author(s):  
R. W. Blake
Keyword(s):  
High Speed ◽  
Forward Direction ◽  
Added Mass ◽  
Mean Value ◽  
The Body ◽  
Power Stroke ◽  
Mass Force ◽  
Mean Power ◽  
Recovery Stroke ◽  
The Mean

Locomotion of a small water boatman (Cenocorixa bifida, Corixidae) was investigated employing high-speed cinematography and hydromechanical modelling based on a blade-element approach. The animal is propelled by the synchronous rowing action of its hind legs. The propulsive cycle consists of a power stroke and a recovery stroke phase. Force, impulse, power, and hydromechanical efficiency were calculated for a representative power stroke during which the mean body velocity was about 8 cms−1. A distinction is made between quasi-steady resistive and unsteady inertial (added mass) forces. The mean and maximum resistive thrust forces were calculated to be about 2.4 × 10−5 and 5.7 × 10−5 N per limb, respectively. By equating the total impulse of the power stroke for both legs (2.4 × 10−6 N s) with that of the drag force acting on the body over the same period, a drag coefficient of approximately 1.07 is inferred for the body. This value is comparable to those obtained for certain insects that operate at similar Reynolds numbers to C. bifida. The unsteady added mass force that acts in the forward direction is positive (propulsive) over most of the stroke with a mean value of about 1.17 × 10−5 N per limb, corresponding to an impulse of approximately 5.9 × 10−7Ns. The total propulsive mean force and impulse acting in the forward direction amount to about 3.6 × 10−5N and 1.8 × 10−6N s per limb, respectively, so the impulse of the forwardly directed added mass force amounts to about half that of the resistive thrust force. The total work and mean power associated with generating the resistive thrust were calculated to be about 6.7 × 10−7 J and 1.33 × 10−5 W per limb, respectively. Dividing the mean body drag power (1.4 × 10−5 W) by the total mean resistive power from both legs gave a hydromechanical efficiency of 0.52. When the mean inertial power associated with moving the body (2.3 × 10−6 W) and the added mass power required to accelerate and decelerate the legs (1.95 × 10−5 W per limb) are taken into account, the power stroke propulsive efficiency falls to 0.42. Taking the energy required to power the recovery stroke into account gives an overall propulsive cycle efficiency of about 0.40. This value is about twice that calculated in a previous study for drag-based pectoral fin rowing in the angelfish and reasons for this are suggested.

Design and Analysis of an Energy-Efficient High-Speed CMOS Double-Tail Dynamic Comparator with Reduced Kickback Noise Effect

2019 ◽  
Vol 28 (09) ◽  
pp. 1950157 ◽  
Author(s):  
Avaneesh K. Dubey ◽  
R. K. Nagaria
Keyword(s):  
Energy Efficient ◽  
High Speed ◽  
Input Voltage ◽  
Mean Value ◽  
Cmos Process ◽  
Total Delay ◽  
Dynamic Comparator ◽  
Amplifier Stage ◽  
The Mean ◽  
Design Style

This paper presents a novel high-speed and highly energy-efficient double-tail dynamic comparator. In order to achieve high speed, a hybrid design style is adopted for pre-amplifier stage and a new design is proposed for latch stage, which enhances the speed and reduces the effect of kickback noise. The latch stage delay and energy efficiency of the proposed design are optimized with respect to the width of each transistor. To verify the outcomes, the proposed comparator is simulated using 45[Formula: see text]nm and 180[Formula: see text]nm CMOS process. Monte Carlo simulation is also done for each parameter. The 45[Formula: see text]nm result shows that the comparator has the total delay as low as 104.3[Formula: see text]ps and consumes only 0.288[Formula: see text]fJ of energy per conversion from a 0.8[Formula: see text]V supply. The mean value of input voltage error due to kickback noise is found as 306[Formula: see text]nV.

Long-period modulated superstructures in Pd-12.5 at.%Ce and Pd-15 at.%Ce alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 164-165
Author(s):  
Noriyuki Kuwano ◽  
Masaru Itakura ◽  
Kensuke Oki
Keyword(s):  
Electron Microscopy ◽  
Mean Value ◽  
Heavy Elements ◽  
Arc Furnace ◽  
X Ray ◽  
Long Period ◽  
Ultra High Purity ◽  
Heat Treated ◽  
Atomic Scattering ◽  
The Mean

Pd-Ce alloys exhibit various anomalies in physical properties due to mixed valences of Ce, and the anomalies are thought to be strongly related with the crystal structures. Since Pd and Ce are both heavy elements, relative magnitudes of (fcc-fpd) are so small compared with <f> that superlattice reflections, even if any, sometimes cannot be detected in conventional x-ray powder patterns, where fee and fpd are atomic scattering factors of Ce and Pd, and <f> the mean value in the crystal. However, superlattices in Pd-Ce alloys can be analyzed by electron microscopy, thanks to the high detectability of electron diffraction. In this work, we investigated modulated superstructures in alloys with 12.5 and 15.0 at.%Ce.Ingots of Pd-Ce alloys were prepared in an arc furnace under atmosphere of ultra high purity argon. The disc specimens cut out from the ingots were heat-treated in vacuum and electrothinned to electron transparency by a jet method.

Articulatory Behavior Pre and Post Full-Mouth Tooth Extraction and Alveoloplasty

1980 ◽  
Vol 23 (3) ◽  
pp. 630-645 ◽  
Author(s):  
Gerald Zimmermann ◽  
J.A. Scott Kelso ◽  
Larry Lander
Keyword(s):  
Control Subject ◽  
High Speed ◽  
Tooth Extraction ◽  
Kinematic Parameters ◽  
Experimental Conditions ◽  
Mean Values ◽  
Articulatory Movements ◽  
The Mean ◽  
Experimental Subjects ◽  
Normal Speech

High speed cinefluorography was used to track articulatory movements preceding and following full-mouth tooth extraction and alveoloplasty in two subjects. Films also were made of a control subject on two separate days. The purpose of the study was to determine the effects of dramatically altering the structural dimensions of the oral cavity on the kinematic parameters of speech. The results showed that the experimental subjects performed differently pre and postoperatively though the changes were in different directions for the two subjects. Differences in both means and variabilities of kinematic parameters were larger between days for the experimental (operated) subjects than for the control subject. The results for the Control subject also showed significant differences in the mean values of kinematic variables between days though these day-to-day differences could not account for the effects found pre- and postoperatively. The results of the kinematic analysis, particularly the finding that transition time was most stable over the experimental conditions for the operated subjects, are used to speculate about the coordination of normal speech.

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