scholarly journals The Effects Of Pruning Type On Wind Loading Of Acer Rubrum

2006 ◽  
Vol 32 (1) ◽  
pp. 33-40
Author(s):  
E. Thomas Smiley ◽  
Brian Kane
Keyword(s):  
Center Of Pressure ◽  
Acer Rubrum ◽  
Bending Moment ◽  
Wind Load ◽  
Wind Loading ◽  
Load Reduction ◽  
Before And After

The wind load, bending moment, height, and weight were determined for 81 red maples (Acer rubrum) before and after pruning. Trees were thinned, reduced, lion tailed, or stripped of foliage. All three pruning treatments reduced wind load significantly compared to unpruned trees at all tested velocities (11, 16, and 20 m/sec [25, 35, and 45 mph]). Reduction in wind load increased with increasing velocity. Differences in wind-load reduction between reduction pruning and thinning were not significant at any velocity. The reduction in wind load was linearly related to the amount of weight removed by pruning treatments. Compared to the same trees prior to pruning, the center of pressure height was significantly lowered on thinned and reduced trees, while the center of pressure height did not change on lion-tailed trees.

scholarly journals Wind Load Reduction in Hollow Panel Arrayed Set

2016 ◽  
Vol 2016 ◽  
pp. 1-14
Author(s):  
Michalina Markousi ◽  
Dimitrios K. Fytanidis ◽  
Johannes V. Soulis
Keyword(s):  
Research Work ◽  
Flow Analysis ◽  
Flow Region ◽  
Maximum Load ◽  
Wind Load ◽  
Wind Loading ◽  
Load Reduction ◽  
Low Velocity ◽  
Approach Angle ◽  
Surface Areas

Reducing the wind loading of photovoltaic structures is crucial for their structural stability. In this study, two solar panel arrayed sets were numerically tested for load reduction purposes. All panel surface areas of the arrayed set are exposed to the wind similarly. The first set was comprised of conventional panels. The second one was fitted with square holes located right at the gravity center of each panel. Wind flow analysis on standalone arrayed set of panels at fixed inclination was carried out to calculate the wind loads at various flow velocities and directions. The panels which included holes reduced the velocity in the downwind flow region and extended the low velocity flow region when compared to the nonhole panels. The loading reduction, in the arrayed set of panels with holes ranged from 0.8% to 12.53%. The maximum load reduction occurred at 6.0 m/s upwind velocity and 120.0° approach angle. At 30.00 approach angle, wind load increased but marginally. Current research work findings suggest that the panel holes greatly affect the flow pattern and subsequently the wind load reduction. The computational analysis indicates that it is possible to considerably reduce the wind loading using panels with holes.

scholarly journals The Effects of Pruning on Drag and Bending Moment of Shade Trees

2008 ◽  
Vol 34 (4) ◽  
pp. 207-215
Author(s):  
Michael Pavlis ◽  
Brian Kane ◽  
J. Roger Harris ◽  
John Seiler
Keyword(s):  
Center Of Pressure ◽  
Bending Moment ◽  
National Standards ◽  
Shade Trees ◽  
White Oak ◽  
Practical Applications ◽  
Before And After ◽  
Quercus Bicolor ◽  
Swamp White Oak ◽  
Simulated Wind

Arborists assume that pruning can help reduce the risk of tree failure by reducing the pressure exerted on trunks by wind (drag-induced bending moment), but there are few studies that quantify this effect. We simulated wind by driving trees in the back of a pickup truck from 0 to 24.5 m/s (0 to 55 mph) and measured drag-induced bending moment as well as tree morphometric data for Freeman maple (Acer × freemanii), swamp white oak (Quercus bicolor Willd.), and shingle oak (Quercus imbricaria Michx.). Measurements were taken before and after application of one of three American National Standards Institute A300 pruning types (raising, reduction pruning, thinning). Reduction of drag-induced bending moment differed by pruning type, largely in accordance with the mass of foliage and twigs removed. The effectiveness of pruning types was also species-dependent because crown architecture affected how much mass each pruning type removed. In general, per unit of mass removed, reduction pruning more effectively reduced the drag-induced bending moment than thinning or raising. Reduction pruning reduced the center of pressure height and, presumably, increased crown porosity after pruning. Prediction of the reduction of drag-induced bending moment was not reliable based on reduction in crown area after pruning. We discuss the practical applications of our findings.

scholarly journals Transfer and generalization of learned manipulation between unimanual and bimanual tasks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Trevor Lee-Miller ◽  
Marco Santello ◽  
Andrew M. Gordon
Keyword(s):  
Learning Transfer ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Pressure Point ◽  
Torque Generation ◽  
Before And After ◽  
Object Center ◽  
High Level ◽  
Bimanual Grasping ◽  
Partial Learning

AbstractSuccessful object manipulation, such as preventing object roll, relies on the modulation of forces and centers of pressure (point of application of digits on each grasp surface) prior to lift onset to generate a compensatory torque. Whether or not generalization of learned manipulation can occur after adding or removing effectors is not known. We examined this by recruiting participants to perform lifts in unimanual and bimanual grasps and analyzed results before and after transfer. Our results show partial generalization of learned manipulation occurred when switching from a (1) unimanual to bimanual grasp regardless of object center of mass, and (2) bimanual to unimanual grasp when the center of mass was on the thumb side. Partial generalization was driven by the modulation of effectors’ center of pressure, in the appropriate direction but of insufficient magnitude, while load forces did not contribute to torque generation after transfer. In addition, we show that the combination of effector forces and centers of pressure in the generation of compensatory torque differ between unimanual and bimanual grasping. These findings highlight that (1) high-level representations of learned manipulation enable only partial learning transfer when adding or removing effectors, and (2) such partial generalization is mainly driven by modulation of effectors’ center of pressure.

Wind load reduction effects on inner buildings by exterior porous façades

2020 ◽  
Vol 183 ◽  
pp. 107148
Author(s):  
Yuan-Lung Lo ◽  
Yu-Ting Wu ◽  
Chung-Lin Fu ◽  
Ying-Chang Yu
Keyword(s):  
Wind Load ◽  
Load Reduction

Reliability of Force-Platform Measures of Postural Sway and Expertise-Related Differences

2011 ◽  
Vol 20 (4) ◽  
pp. 442-456 ◽  
Author(s):  
Zohreh Meshkati ◽  
Mehdi Namazizadeh ◽  
Mahyar Salavati ◽  
Masood Mazaheri
Keyword(s):  
Outcome Measures ◽  
Postural Sway ◽  
Center Of Pressure ◽  
Intraclass Correlation ◽  
Specific Property ◽  
Force Platform ◽  
Quiet Standing ◽  
Eyes Closed ◽  
Before And After ◽  
Eyes Open

Context:Although reliability is a population-specific property, few studies have investigated the measurement error associated with force-platform parameters in athletic populations.Objective:To investigate the skill-related differences between athletes and nonathletes in reliability of center-of-pressure (COP) summary measures under eyes-open (EO) and eyes-closed (EC) conditions.Design:Test–retest reliability study.Setting:COP was recorded during double-leg quiet standing on a Kistler force platform before and after a fatiguing treadmill exercise, with EO and EC.Participants:31 male participants including 15 athletes practiced in karate and 16 nonathletes.Main Outcome Measures:Standard deviation (SD) of amplitude, phase-plane portrait, SD of velocity, mean total velocity, and area were calculated from 30-s COP data. Intraclass correlation coefficient (ICC), standard error of measurement, and coefficient of variation (CV) were used as estimates of reliability and precision.Results:Higher ICCs were found for COP measures in the athlete (compared with the nonathlete) group, postfatigued (compared with prefatigued) condition, and EC (compared with EO) tests. CVs smaller than 15% were obtained for most of the COP measures. SD of velocity in the anteroposterior direction showed the highest reliability in most conditions.Conclusions:Tests with EC and to a lesser extent tests performed in the athlete group and in the postfatigued condition showed better reliability.

Model Tests and Numerical Simulation on Effect of Spudcan Penetration on P-Delta of an Adjacent Pile

2019 ◽  
Author(s):  
Jianhua Wang ◽  
Yifei Fan ◽  
Dong Guo
Keyword(s):  
Penetration Depth ◽  
Bending Moment ◽  
Fine Sand ◽  
Lateral Load ◽  
Model Tests ◽  
Constraint Condition ◽  
Pile Head ◽  
Load Direction ◽  
Position Change ◽  
Before And After

Abstract Model tests under 1g condition and numerical simulations of spudcan penetration in the silty fine sand were conducted to study effects of spudcan penetration on the p-delta effect of adjacent free-head and elastic-head piles subjected to lateral and vertical head loads. The p-delta factors were defined and determined based on the maximum pile shaft bending moments and pile head deflections before and after spudcan penetration, which were used to analyze the variations of the p-delta effect with the spudcan penetration depth. The conclusions were obtained as follows. The p-delta effect depends on the pile head constraint condition, the direction of the lateral pile head load and the spudcan penetration depth. For a free-head pile, the p-delta factors decrease with increasing the spudcan penetration depth. For an elastic-head pile, the p-delta factors also decrease during spudcan penetration and the decreases depend on the spudcan penetration depth and the lateral pile head load direction. The decrease associated with the lateral load direction facing back to the spudcan is larger than that associated with the lateral load direction facing to the spudcan. Therefore, the spudcan penetration does not increase the p-delta effect of adjacent piles subjected to lateral and vertical head loads. But the maximum bending moment and its occurring position change during spudcan penetration.

Experimental Study on the Characteristics of Bolted Pipe Flange Connection Under Bending Moment and Internal Pressure

2020 ◽  
Author(s):  
Xing Zheng ◽  
Toshiyuki Sawa ◽  
Mei Feng ◽  
Honggui Ding
Keyword(s):  
Experimental Study ◽  
Internal Pressure ◽  
Bending Moment ◽  
Wind Load ◽  
Force Distribution ◽  
Flange Connection ◽  
Special Cases ◽  
Minimum Residual ◽  
Spiral Wound

Abstract After a bolted gasketed pipe flange connection is assembled, the pipe flange connection is usually subjected to some additional loads such as bending moment, own weight, wind load and so on. These additional loads will lead to changing the axial bolt force distribution of the pipe flange connection and the distribution will become more and more scattered. As a result, the minimum residual axial bolt force will be much smaller and the minimum contact gasket stress will decrease, so a leakage is easy to occur in the connection. In special cases such as earthquakes, the bolted pipe flange connection is usually subjected to a high bending moment. Then sometimes leakage accidents occur. In order to promote the safety of the connections and to avoid them being broken under the earthquakes, in the present paper, the equivalent pressure and the assembly efficiency in the pipe flange connection of class 150 4″ are measured experimentally. The leak rates of the connection using spiral-wound gasket when a bending moment was applied or not applied were measured to elicit the equivalent pressure. Moreover, some tightening procedures such as JIS B 2251, ASME PCC-1 Legacy and GB/T 38343 were applied to tighten the pipe flange connection. The axial bolt force distribution, the assembly efficiency based on the target axial bolt force and the assembly efficiency based on tightness parameter of the connection when bending moment was applied or not applied were measured, and the results are compared. As a result, the equivalent pressure under a given bending moment is obtained, and a difference of the equivalent pressure between our results and Kellogg’s results is demonstrated. In addition, the new assembly efficiency based on the tightness parameter is also measured under a given bending moment as well as internal pressure. Using the equivalent pressure and the assembly efficiency obtained in the present paper, a new design will be possible for pipe flange connections under bending moment.

Reliability of bridge structures under wind loading: Consideration of uncertainties of wind load parameters

1990 ◽  
Vol 33 (1-2) ◽  
pp. 385-394 ◽  
Author(s):  
P.H.W. Prenninger ◽  
M. Matsumoto ◽  
N. Shiraishi ◽  
C. Izumi ◽  
Y. Tsukiyama
Keyword(s):  
Wind Load ◽  
Wind Loading ◽  
Bridge Structures

128 Experiment of a Wind Load Reduction Type of Soundproof Plate with Practical Size

2012 ◽  
Vol 2012.22 (0) ◽  
pp. 109-112
Author(s):  
Masanori HANSAKA ◽  
Daigo SATO ◽  
Shogo MAMADA ◽  
Nozomi TANIGUCHI ◽  
Masakazu KIYAMA
Keyword(s):  
Wind Load ◽  
Load Reduction

scholarly journals Wind Load Reduction for Light-weight Heliostats

2014 ◽  
Vol 49 ◽  
pp. 193-200 ◽  
Author(s):  
A. Pfahl ◽  
A. Brucks ◽  
C. Holze
Keyword(s):  
Wind Load ◽  
Load Reduction ◽  
Light Weight
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