scholarly journals On Pre-Stressed Hull Structures

2021 ◽  
Vol 10 (2) ◽  
pp. 47-52
Author(s):  
Victor A. Dubrovsky ◽  
Keyword(s):  
External Load ◽  
Water Structure ◽  
Load Estimation ◽  
Stress Control ◽  
Minimal Weight ◽  
Novel Method ◽  
Total Structure ◽  
External Loads

“Wave-piercing” super-planing trimaran with air-born unloading, WPT, is developing of “wave-piercing” catamaran, WPC, for twice bigger achievable speeds. As all fast vessels, WPT needs for minimal weight of hull structures. Using of pre-stressed structures is a novel method of hull weight decreasing. An example of such structure of WPT begins from external load estimation. And the scheme of pre-stressed structure is selected: two pairs of steel ropes along and across the WPT above-water structure. Than method of pre-strength is selected: constant or varied forces. Varied external loads define the need of varied pre-stress control. Estimation of the corresponded system weight: total structure of above-water platform can be decreased at about 20%. The method can be applied for airplane wings too.

scholarly journals Associations between Well-Being State and Match External and Internal Load in Amateur Referees

2021 ◽  
Vol 18 (6) ◽  
pp. 3322
Author(s):  
Eñaut Ozaeta ◽  
Javier Yanci ◽  
Carlo Castagna ◽  
Estibaliz Romaratezabala ◽  
Daniel Castillo
Keyword(s):  
External Load ◽  
Contact Time ◽  
Well Being ◽  
Ground Contact ◽  
Internal Load ◽  
Match Play ◽  
Power Meter ◽  
Ground Contact Time ◽  
Training Impulse ◽  
External Loads

The main aim of this paper was to examine the association between prematch well-being status with match internal and external load in field (FR) and assistant (AR) soccer referees. Twenty-three FR and 46 AR participated in this study. The well-being state was assessed using the Hooper Scale and the match external and internal loads were monitored with Stryd Power Meter and heart monitors. While no significant differences were found in Hooper indices between match officials, FR registered higher external loads (p < 0.01; ES: 0.75 to 5.78), spent more time in zone 4 and zone 5, and recorded a greater training impulse (TRIMP) value (p < 0.01; ES: 1.35 to 1.62) than AR. Generally, no associations were found between the well-being variables and external loads for FR and AR. Additionally, no associations were found between the Hooper indices and internal loads for FR and AR. However, several relationships with different magnitudes were found between internal and external match loads, for FR, between power and speed with time spent in zone 2 (p < 0.05; r = −0.43), ground contact time with zone 2 and zone 3 (p < 0.05; r = 0.50 to 0.60) and power, speed, cadence and ground contact time correlated with time spent in zone 5 and TRIMP (p < 0.05 to 0.01; r = 0.42 to 0.64). Additionally, for AR, a relationship between speed and time in zone 1 was found (p < 0.05; r = −0.30; CL = 0.22). These results suggest that initial well-being state is not related to match officials’ performances during match play. In addition, the Stryd Power Meter can be a useful device to calculate the external load on soccer match officials.

scholarly journals Comparison between Continuous and Fractionated Game Format on Internal and External Load in Small-Sided Games in Soccer

2020 ◽  
Vol 17 (2) ◽  
pp. 405 ◽  
Author(s):  
Luís Branquinho ◽  
Ricardo Ferraz ◽  
Bruno Travassos ◽  
Mário C. Marques
Keyword(s):  
Confidence Intervals ◽  
External Load ◽  
Continuous Method ◽  
Soccer Players ◽  
Professional Soccer ◽  
Game Format ◽  
Physical Impact ◽  
Mean Differences ◽  
External Loads

This study aimed to identify the effects of continuous and fractionated game formats on internal and external load in small-sided games in soccer. Twenty male professional soccer players participated in the study performing the same exercise (5 vs. 5 players) continuously (1 × 24 min) and in a repeated/fractioned manner (2 × 12 min, 4 × 6 min, and 6 × 4 min). A comparison between playing conditions was assessed by means of standardized mean differences calculated with combined variance and respective confidence intervals of 90%. The limits for the statistics were 0.2, trivial; 0.6, small; 1.2, moderate; 2.0, large; and >2.0, very large. The results indicate that the use of the continuous method seems to present the tendency of less physical impact on the internal and external loads compared to the fractionated method. In addition, the higher number of exercise repetitions in the fractionated method was found to increase the external load compared to the continuous method. This study showed that application of small-sided games by the fractionated method tends to result in higher training loads.

Secondary Stresses in Airship Hull Structures

1927 ◽  
Vol 31 (204) ◽  
pp. 1073-1109
Author(s):  
J. F. Baker
Keyword(s):  
Cross Section ◽  
External Load ◽  
Structural Engineering ◽  
Secondary Stress ◽  
Rigorous Definition ◽  
The Cross ◽  
Definition Of ◽  
Redundant Structure ◽  
Ball Joints ◽  
External Loads

In no branch of structural engineering is there a rigorous definition of the term “secondary stress.”If the primary stresses in a structure are determined, that is, the stresses in the members due to an external load system, assuming that all the members are joined together by perfect pin- or ball-joints, then the secondary stresses are in general taken to be the additional stresses due to the rigidity of the actual joints used in practice.In such a highly redundant structure as an airship hull the labour involved, in determining even the primary stresses, precludes the use of the normal methods of stressing. It is usual to make use of generalised methods which give approximate results. These generalised methods imply that the external loads are applied to the structure in a certain distribution. Though this is rarely achieved, yet the results obtained are in most cases sufficiently accurate if suitable bracing is supplied to redistribute the external loads over the cross-section; the effect of the initial wrong distribution being then merely local.

External and internal Load and their Effects on Professional Volleyball Training

2020 ◽  
Vol 41 (07) ◽  
pp. 468-474
Author(s):  
Ricardo Franco Lima ◽  
Ana Silva ◽  
José Afonso ◽  
Henrique Castro ◽  
Filipe Manuel Clemente
Keyword(s):  
External Load ◽  
Inertial Measurement Unit ◽  
Perceived Exertion ◽  
Measurement Unit ◽  
Internal Load ◽  
Monitoring Process ◽  
Accurate Perception ◽  
Positive Correlations ◽  
The Impact ◽  
External Loads

AbstractThe purpose of this study was twofold: (i) characterize the external and internal training load of professional volleyball players with a focus on intra-week changes and (ii) test the relationships between internal and external load measures. Eight male professional players (age: 23.0±5.22 yo; body mass: 84.5 ± 7.58 kg; height: 193.0±9.71 cm; BMI: 22.0±0.02 kg/m2) were monitored daily over 15 weeks. The monitoring process included both internal (rate of perceived exertion [RPE] and session-RPE [s-RPE]) and external load variables, which were measured by an inertial measurement unit. Results revealed that, within-week variations revealed that RPE was significantly higher during MD-2 (d=0.59) and MD-3 (d=0.56) than MD-1. A significantly higher number of jumps was observed on MD-2 than MD-1 (d=0.69). Considering the relationships between internal and external load measures, small positive correlations were found between RPE and the number of jumps (r=0.17) and between s-RPE and the number of jumps (r=0.49). In conclusion, a tapering strategy was observed on the day before a match, as internal and external loads decreased. Both internal and external load measures are necessary to provide an accurate perception of the impact of training stimuli on players.

Force feedback by external load estimation from cylinder pressures of hydraulically-driven multiple DOF robot

2017 ◽  
Vol 2017 (0) ◽  
pp. 2A1-P06 ◽  
Author(s):  
Taiki OKADA ◽  
Yasuyoshi YOKOKOHJI ◽  
Yuichi TAZAKI ◽  
Hiroshi YOSHINADA ◽  
Shinya NAKAMURA ◽  
...  
Keyword(s):  
External Load ◽  
Force Feedback ◽  
Load Estimation

Experimental Validation of Leakage Detection in a Fluid Power Pitch System Using a State Augmented EKF-Approach

2020 ◽  
Author(s):  
Magnus F. Asmussen ◽  
Henrik C. Pedersen ◽  
Jesper Liniger
Keyword(s):  
Wind Turbine ◽  
Working Conditions ◽  
External Load ◽  
Estimation Error ◽  
Leakage Detection ◽  
Power Regulation ◽  
Pitch System ◽  
External Loads ◽  
Crucial Part ◽  
Different Levels

Abstract The pitch system is a crucial part of today’s wind turbines and is used for power regulation when operating above rated wind speed. According to studies the pitch system is responsible for up to 20% of the total downtime of a wind turbine. As an attempt of increasing the reliability and availability attention has come to fault detection and condition monitoring of such systems. This paper presents a State Augmented Extended Kalman Filter, SAEKF, for detecting both internal and external rod leakage. Furthermore, an external load torque is included in the filter to improve the performance in the presence of external load. The SAEKF is tested experimentally for different levels of both internal and external rod leakage under working conditions similar to the ones experienced for a pitch system located in a wind turbine. The working conditions include unkown fast varying external loads. The experiments show that the SAEKF is capable of detecting internal and external leakage down to 0.10 l/min and 0.34 l/min, respectively. The internal leakage is detected with a estimation error of maximum 0.04 l/min while the external leakage estimation error is going up to 0.43 l/min for high levels of external leakage.

Influence of External Loads on Thin Film Cracking

2004 ◽  
Author(s):  
Srinath S. Chakravarthy ◽  
Eric H. Jordan ◽  
Wilson K. S. Chiu
Keyword(s):  
Thin Film ◽  
External Load ◽  
Crack Arrest ◽  
External Loading ◽  
Element Analysis ◽  
Film Cracking ◽  
Two Parameters ◽  
Improved Accuracy ◽  
External Loads

Cracking in thin films under the combined influence of residual stress and an external load is examined. An improved accuracy version of the existing solution for substrate cracking absent the external load is provided. A superposition scheme that uses the solution for substrate cracking and other existing published solutions is presented for the determination of the energy release rate. The superposition scheme is validated using finite element analysis, and conditions under which the superposition scheme is valid are discussed. Crack arrest is examined and two parameters that determine the possibility of crack arrest are identified. The influence of external loading on channelling behavior in the substrate is discussed.

Stabilization of External Loads in High-Speed Flight Using an Active Cargo Hook

2020 ◽  
Vol 65 (2) ◽  
pp. 1-12
Author(s):  
Jacob Enciu ◽  
Ajay Singh ◽  
Joseph F. Horn
Keyword(s):  
External Load ◽  
High Speed ◽  
Multiple Equilibria ◽  
Coupled System ◽  
System Stability ◽  
Linear Quadratic ◽  
Tunnel Model ◽  
Full State ◽  
Full State Feedback ◽  
External Loads

The use of an active cargo hook for stabilizing external loads during high-speed flight is demonstrated in simulation. A CONEX cargo container with two rear-mounted stabilization fins is used as the subject load. Significant nonlinearities in the dynamics of the external load result in multiple equilibria and limit cycle oscillations. A full-state feedback linear quadratic controller is developed assuming an isolated load in a wind tunnel model and shown to be successful in stabilizing the originally unstable load at a target airspeed of 100 kt. The design is then completed to cover the target carriage envelope from hover to high-speed flight. Simulations of a coupled system incorporating a UH-60 Black Hawk helicopter with an actuated cargo hook and the external load show that the controller is successful in providing system stability throughout the target flight speed envelope.

scholarly journals The Radial Distribution Functions of Water as Derived from Radiation Total Scattering Experiments: Is There Anything We Can Say for Sure?

2013 ◽  
Vol 2013 ◽  
pp. 1-67 ◽  
Author(s):  
A. K. Soper
Keyword(s):  
Radial Distribution ◽  
Water Structure ◽  
Distribution Functions ◽  
Scattering Data ◽  
Radial Distribution Functions ◽  
Radiation Scattering ◽  
Neutron Data ◽  
Simulation Tools ◽  
Novel Method

The present paper reviews the investigation of ambient water structure and focusses in particular on the determination of the radial distribution functions of water from total experimental radiation scattering experiments. A novel method for removing the inelastic scattering from neutron data is introduced, and the effect of Compton scattering on X-ray data is discussed. In addition the extent to which quantum effects can be discerned between heavy and light water is analysed against these more recent data. It is concluded that, with the help of modern data analysis and computer simulation tools to interrogate the scattering data, a considerable degree of consistency can be obtained between recent and past scattering experiments on water. That consistency also gives a realistic estimate of the likely uncertainties in the extracted radial distribution functions, as well as offering a benchmark against which future experiments can be judged.

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