An experimental study of bellows-type fluidic soft bending actuators under external water pressure

Affected by the coupling of excavation disturbance and ground stress, the heterogeneity of surrounding rock is very common. Presently, treating the permeability coefficient as a fixed value will reduce the prediction accuracy of the water inflow and the external water pressure of the structure, leading to distortion of the prediction results. Aiming at this problem, this paper calculates and analyzes tunnel water inflow when considering the heterogeneity of permeability coefficient of surrounding rock using a theoretical analysis method, and compares with field data, and verifies the rationality of the formula. The research shows that, when the influence of excavation disturbance and ground stress on the permeability coefficient of surrounding rock is ignored, the calculated value of the external water force of the tunnel structure is too small, and the durability and stability of the tunnel are reduced, which is detrimental to the safety of the structure. Considering the heterogeneity of surrounding rock, the calculation error of water inflow can be reduced from 27.3% to 13.2%, which improves the accuracy of water inflow prediction to a certain extent.

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Control of arterial pressure in aquatic sea snakes

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1983.244.1.r66 ◽

1983 ◽

Vol 244 (1) ◽

pp. R66-R73 ◽

Cited By ~ 3

Author(s):

H. B. Lillywhite ◽

F. H. Pough

Keyword(s):

Arterial Pressure ◽

Blood Volume ◽

Water Pressure ◽

Cardiovascular Responses ◽

Physiological Regulation ◽

Sea Snakes ◽

Head Up Tilt ◽

External Water Pressure ◽

External Water ◽

Head Level

Cardiovascular responses to head-up tilt, acutely graded hemorrhage, and pharmacologic stimulation by principal autonomic drugs were studied in four species of marine snakes, principally Aipysurus laevis (family Hydrophiidae). Arterial pressure varied inversely with tilt angle and blood volume deficit in conscious snakes outside of water, indicating that physiological regulation was poor or lacking. Calculated arterial pressures at head level typically diminished to zero in A. laevis tilted to angles greater than or equal to 30 degrees. Arterial pressure (corrected for external water pressure) did not change when these snakes were tilted in seawater. Changes of arterial pressure induced by tilt, blood loss, or autonomic drugs elicited reflex adjustments in heart activity, but the magnitude of these responses was less than that observed in terrestrial species of snake. It is concluded that baroreflexes are present but comparatively ineffective in sea snakes. Snakes tolerated large losses of blood volume, and extravascular fluids were absorbed into the circulation during hemorrhage; both hemorrhage and estimated hemodilution volumes exceeded 100% of the initial blood volume in Acalyptophis peronii. Thus, in marine snakes major fluid shifts between nonvascular and vascular compartments significantly compensate hypovolemia but, because of minor autonomic adjustments, do not result in a well-regulated arterial pressure.

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A multicentered comparison of measurements obtained with microtip and external water pressure transducers

International Urogynecology Journal ◽

10.1007/s00192-005-0027-0 ◽

2005 ◽

Vol 17 (4) ◽

pp. 400-406 ◽

Cited By ~ 12

Author(s):

Andrew F. Hundley ◽

Morton B. Brown ◽

Linda Brubaker ◽

Geoffrey W. Cundiff ◽

Karl Kreder ◽

...

Keyword(s):

Water Pressure ◽

Pressure Transducers ◽

External Water Pressure ◽

External Water

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Instruments and Methods High Pressure Coupling for Pipe in Deep Water Filled Bore Holes

Journal of Glaciology ◽

10.3189/s0022143000028380 ◽

1963 ◽

Vol 4 (36) ◽

pp. 809-812

Author(s):

R. L. Shreve

Keyword(s):

High Pressure ◽

Water Pressure ◽

The Other ◽

Internal Diameter ◽

External Diameter ◽

Synthetic Rubber ◽

External Water Pressure ◽

External Water ◽

One Year ◽

Aluminum Pipe

AbstractIn August 1961 an aluminum pipe (3.5 cm. internal diameter, 4.2 cm. external diameter) having 92 specially modified socket couplings (5.0 cm. external diameter) sealed with a quick-polymerizing synthetic rubber was sunk 226 m. in a vertical water-filled bore hole in Blue Glacier, Washington. U.S.A. The geometry of threads and mating surfaces of pipe and coupling was designed to cause increasing external water pressure to tighten the seal. One joint at a depth of 66 m. immediately developed an extremely slow leak (probably because of faulty cleaning), but the other 91 joints apparently were sound, as the pipe was free of water to a depth of at least 157 m. when resurveyed after one year.

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Vibration of a thin-walled shell under external water pressure using ANSYS

Pressure Vessels ◽

10.1533/9780857092496.393 ◽

2011 ◽

pp. 393-418

Author(s):

Carl T.F. Ross

Keyword(s):

Water Pressure ◽

External Water Pressure ◽

Thin Walled ◽

External Water

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Non-Linear General Instability of Ring-Stiffened Cones under External Water Pressure

Proceedings of the Thirteenth International Conference on Civil, Structural and Environmental Engineering Computing ◽

10.4203/ccp.96.193 ◽

2011 ◽

Author(s):

C.T.F. Ross ◽

C. Kubelt ◽

I. McLaughlin ◽

A. Etheridge ◽

K. Turner ◽

...

Keyword(s):

Water Pressure ◽

Non Linear ◽

External Water Pressure ◽

External Water

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Interstitial and intravascular pressures in conscious dogs during head-out water immersion

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1989.257.2.r358 ◽

1989 ◽

Vol 257 (2) ◽

pp. R358-R364

Author(s):

K. Miki ◽

M. R. Klocke ◽

S. K. Hong ◽

J. A. Krasney

Keyword(s):

Hydrostatic Pressure ◽

Interstitial Fluid ◽

Water Pressure ◽

Water Immersion ◽

Ulnar Artery ◽

Conscious Dogs ◽

External Reference ◽

External Water Pressure ◽

External Water ◽

Peripheral Arterial

Water immersion (WI) causes an increase in plasma volume in humans and dogs. To determine the mechanism for this fluid movement, the transmission of external water hydrostatic pressure to the interstitial and vascular compartments was studied in six conscious dogs. Systemic arterial, central venous, peripheral arterial (ulnar artery) and venous (cephalic vein), pleural, intra-abdominal, and interstitial fluid hydrostatic (by Guyton's capsule and wick catheter method) pressures and external reference water pressure were measured at three different levels of WI: 1) extremities only, 2) midchest, and 3) midcervical levels at 37 degrees C. There was a significant linear relationship between interstitial fluid hydrostatic pressure (X) and external water pressure (Y): (Y = 0.86X + 1.4, r = 0.93 by Guyton's capsule; Y = 0.85X + 2.4, r = 0.93 by wick catheter. However, vascular pressures did not change when dogs were immersed at the level of the extremities. These pressures increased only during WI at the midchest and midcervical levels. Therefore the pressure gradient that develops between the interstitial and intravascular compartments is probably the major reason for the transcapillary fluid shift during WI.

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