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Kettenbeil, C., Z. Lovinger, S. Ravindran, M. Mello und G. Ravichandran. „Pressure-Shear Plate Impact Experiments at High Pressures“. Journal of Dynamic Behavior of Materials 6, Nr. 4 (17.06.2020): 489–501. http://dx.doi.org/10.1007/s40870-020-00250-y.
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Macdermid, Paul W., Matthew C. Miller, Fiona M. Macdermid und Philip W. Fink. „Tyre Volume and Pressure Effects on Impact Attenuation during Mountain Bike Riding“. Shock and Vibration 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/191075.
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Exposure to impacts and vibrations has been shown to be detrimental to cross country mountain bike performance and health. Therefore, any strategy aimed at attenuating such exposure is useful to participants and/or industry. The purpose of this study was to assess the influence of tyre size and tyre inflation pressure on exposure to impacts. Participants completed nine trials of a technical section (controlled for initial speed and route taken) including nine separate conditions involving three tyre sizes and three tyre inflation pressures normalised per tyre. Performance was determined by time to negotiate the technical section while triaxial accelerometers recorded accelerations (128 Hz) to quantify impact exposure and the subsequent effects on soft tissue response. Increases in tyre size within the range used improved performanceP<0.0001while changes to tyre inflation pressure had no effectP=0.6870on performance. Larger tyre sizes and lower tyre inflation pressures significantlyP<0.0001reduced exposure to impacts which could be augmented or negated due to an interaction between tyre size and inflation pressureP<0.0001. It is recommended that mountain bikers use larger tyres, inflated to the moderate pressures used within this study, in order to increase performance and reduce the risk of overuse injuries.
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Wheeler, Abigail, Shanti Farrington, Fay Sweeting, Amy Brown und Andrew Mayers. „Perceived Pressures and Mental Health of Breastfeeding Mothers: A Qualitative Descriptive Study“. Healthcare 12, Nr. 17 (08.09.2024): 1794. http://dx.doi.org/10.3390/healthcare12171794.
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When a mother is supported to breastfeed, the benefits for her mental health are significant. However, if pressured or unsupported, the opposite is true. This research examines mothers’ breastfeeding experiences, exploring how perceived pressure can impact perinatal mental health. A sample of 501 respondents to a research questionnaire was explored using Reflexive Thematic Analysis. Three main themes identified were perceived pressure to breastfeed, perceived pressure not to breastfeed and mental health impact. The main findings were that mothers received conflicting advice from healthcare professionals, and pressures to feed in a certain way came from their support networks, as well as from their internal beliefs. Perceived pressures negatively impacted maternal mental health, while positive breastfeeding experiences benefitted mental health outcomes.
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Cooker, Mark J., und D. H. Peregrine. „Pressure-impulse theory for liquid impact problems“. Journal of Fluid Mechanics 297 (25.08.1995): 193–214. http://dx.doi.org/10.1017/s0022112095003053.
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A mathematical model is presented for the high pressures and sudden velocity changes which may occur in the impact between a region of incompressible liquid and either a solid surface or a second liquid region. The theory rests upon the well-known idea of pressure impulse, for the sudden initiation of fluid motion in incompressible fluids. We consider the impulsive pressure field which occurs when a moving fluid region collides with a fixed target, such as when an ocean wave strikes a sea wall. The boundary conditions are given for modelling liquid-solid and liquid-liquid impact problems. For a given fluid domain, and a given velocity field just before impact, the theory gives information on the peak pressure distribution, and the velocity after impact. Solutions for problems in simple domains are presented, which give insight into the peak pressures exerted by a wave breaking against a sea wall, and a wave impacting in a confined space. An example of liquid-liquid impact is also examined. Results of particular interest include a relative insensitivity to the shape of the incident wave, and an increased pressure impulse when impact occurs in a confined space. The theory predicts that energy is lost from the bulk fluid motion and we suggest that this energy can be transferred to a thin jet of liquid which is projected away from the impact region.
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Bredmose, H., G. N. Bullock und A. J. Hogg. „Violent breaking wave impacts. Part 3. Effects of scale and aeration“. Journal of Fluid Mechanics 765 (16.01.2015): 82–113. http://dx.doi.org/10.1017/jfm.2014.692.
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AbstractThe effects of scale and aeration on violent breaking wave impacts with trapped and entrained air are investigated both analytically and numerically. By dimensional analysis we show that the impact pressures for Froude scaled conditions prior to the impact depend on the scale and aeration level. The Bagnold–Mitsuyasu scaling law for the compression of an air pocket by a piston of incompressible water is rederived and generalised to 3D air pockets of arbitrary shape. Numerical results for wall pressure, force and impulse are then presented for a flip-through impact, a low-aeration impact and a high-aeration impact, for nine scales and five levels of initial aeration. Two of these impact types trap a pocket of air at the wall. Among the findings of the paper is that for fixed initial aeration, impact pressures from the flip-through impact broadly follow Froude scaling. This is also the case for the two impact types with trapped air pockets for impact pressures below 318 kPa, while impact pressures above this value broadly follow the Bagnold–Mitsuyasu scaling law with full-scale pressures greater than those predicted by the Froude law. For all impact types, the effect of aeration is found to reduce the maximum impact pressure, maximum force and impulse. Good agreement with the asymptotic model of Peregrine & Thais (J. Fluid Mech., vol. 325, 1996, pp. 377–397) is found for the flip-through impact pressure and a fair agreement is found for the low- and high-aeration impacts. Based on the numerical results, a modified scaling curve that combines Froude scaling and the Bagnold–Mitsuyasu law is suggested. The practical implications of the findings are discussed and attention is drawn to the limitations of physical model tests.
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Stagonas, Dimitris, Andrea Marzeddu, Francesc Xavier Gironella I. Cobos, Agustin Sánchez-Arcilla Conejo und Gerald Muller. „Measuring wave impact induced pressures with a pressure mapping system“. Coastal Engineering 112 (Juni 2016): 44–56. http://dx.doi.org/10.1016/j.coastaleng.2016.03.003.
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Wong, P. L., S. Lingard und A. Cameron. „The High Pressure Impact Microviscometer“. Tribology Transactions 35, Nr. 3 (Januar 1992): 500–508. http://dx.doi.org/10.1080/10402009208982148.
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Trachsel, Tina, Christian Balmer, Håkan Wåhlander, Roland Weber, Hitendu Dave, Andrea Poretti, Oliver Kretschmar und Anna Cavigelli-Brunner. „Does superior caval vein pressure impact head growth in Fontan circulation?“ Cardiology in the Young 26, Nr. 7 (15.01.2016): 1327–32. http://dx.doi.org/10.1017/s1047951115002528.
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AbstractBackgroundPatients with bidirectional cavopulmonary anastomosis have unphysiologically high superior caval vein pressure as it equals pulmonary artery pressure. Elevated superior caval vein pressure may cause communicating hydrocephalus and macrocephaly. This study analysed whether there exists an association between head circumference and superior caval vein pressure in patients with single ventricle physiology.MethodsWe carried out a retrospective analysis of infants undergoing Fontan completion at our institution from 2007 to 2013. Superior caval vein pressures were measured during routine catheterisation before bidirectional cavopulmonary anastomosis and Fontan completion as well as head circumference, adjusted to longitudinal age-dependent percentiles.ResultsWe included 74 infants in our study. Median ages at bidirectional cavopulmonary anastomosis and Fontan were 4.8 (1.6–12) and 27.9 (7–40.6) months, respectively. Head circumference showed significant growth from bidirectional cavopulmonary anastomosis until Fontan completion (7th (0–100th) versus 20th (0–100th) percentile). There was no correlation between superior caval vein pressure and head circumference before Fontan (R2=0.001). Children with lower differences in superior caval vein pressures between pre-bidirectional cavopulmonary anastomosis and pre-Fontan catheterisations showed increased growth of head circumference (R2=0.19).ConclusionsPatients with moderately elevated superior caval vein pressure associated with single ventricle physiology did not have a tendency to develop macrocephaly. There is no correlation between superior caval vein pressure before Fontan and head circumference, but between bidirectional cavopulmonary anastomosis and Fontan head circumference increases significantly. This may be explained by catch-up growth of head circumference in patients with more favourable haemodynamics and concomitant venous pressures in the lower range. Further studies with focus on high superior caval vein pressures are needed to exclude or prove a correlation.
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Ye, Z., und A. M. Birk. „Fluid Pressures in Partially Liquid-Filled Horizontal Cylindrical Vessels Undergoing Impact Acceleration“. Journal of Pressure Vessel Technology 116, Nr. 4 (01.11.1994): 449–58. http://dx.doi.org/10.1115/1.2929615.
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An experimental investigation has been carried out to study the fluid pressures in partially liquid-filled vessels when they are suddenly accelerated by impact along the longitudinal axis. The experiments were conducted with three horizontal cylindrical tanks of different length-to-diameter ratios of L/D = 6.0, 3.5, 2.0. The tanks were filled with water at ambient pressure and temperature and were accelerated using a large steel impact hammer. Internal tank wall pressures caused by the acceleration were measured with transient pressure transducers. Six types of pressure-time histories have been observed and results indicated that the pressure profile changes with fill level and transducer location. The peak pressures on the end of the tank are strongly affected by the fill level and the tank length-to-diameter ratio L/D. A modal change in the behavior of liquid movement has been found around fill level h/D = 0.95. For fill levels h/D above 0.95, the pressure in the tanks acted like either a water hammer or an accelerated fluid column, depending on the duration of the impact relative to the pressure wave transit time. For the fill levels with h/D below 0.95, liquid sloshing activity was involved and the pressure at the end of the tank was a function of the liquid dynamic pressure. This modal change also caused the location of maximum peak pressure to move from the impact end of the tank to the tank top. In some cases the pressure on the tank top was two times larger than that at the tank impact end. The maximum pressure observed from the tests was on the top of the tank. This modal change may have some significance in some transportation applications.
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Tukhtabayev, M., und A. Madraximov. „Assessment of the impact of agricultural tractor wheels on soil compaction“. IOP Conference Series: Earth and Environmental Science 1390, Nr. 1 (01.08.2024): 012005. http://dx.doi.org/10.1088/1755-1315/1390/1/012005.
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Abstract This article presents the results of an experimental study on the impact of leading wheel tires 15.5R38 and 16.9R38 on soil. Specifically, the study analyzed the influence of vertical load on the maximum tire pressure (MTA) and internal air pressure on soil. The variations in maximum soil pressures of 15.5R38 and 16.9R38 tires at different internal air pressures depending on corresponding loads were investigated. The characteristics of changes in permissible pressure and loading of tires on soil are graphically depicted, and the permissible standards for their use in agricultural work are determined. Recommendations are provided for using tires at the minimum and maximum permissible internal air pressures. Using values smaller than the recommended values can lead to a decrease in the useful life of the tire.
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Al Khaburi, J., E. A. Nelson, J. Hutchinson und A. A. Dehghani-Sanij. „Impact of multilayered compression bandages on sub-bandage interface pressure: a model“. Phlebology: The Journal of Venous Disease 26, Nr. 2 (März 2011): 75–83. http://dx.doi.org/10.1258/phleb.2010.009081.
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Background Multi-component medical compression bandages are widely used to treat venous leg ulcers. The sub-bandage interface pressures induced by individual components of the multi-component compression bandage systems are not always simply additive. Current models to explain compression bandage performance do not take account of the increase in leg circumference when each bandage is applied, and this may account for the difference between predicted and actual pressures. Objective To calculate the interface pressure when a multi-component compression bandage system is applied to a leg. Method Use thick wall cylinder theory to estimate the sub-bandage pressure over the leg when a multi-component compression bandage is applied to a leg. Results A mathematical model was developed based on thick cylinder theory to include bandage thickness in the calculation of the interface pressure in multi-component compression systems. In multi-component compression systems, the interface pressure corresponds to the sum of the pressures applied by individual bandage layers. However, the change in the limb diameter caused by additional bandage layers should be considered in the calculation. Adding the interface pressure produced by single components without considering the bandage thickness will result in an overestimate of the overall interface pressure produced by the multi-component compression systems. At the ankle (circumference 25 cm) this error can be 19.2% or even more in the case of four components bandaging systems. Conclusion Bandage thickness should be considered when calculating the pressure applied using multi-component compression systems.
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Cao, Xiaoming, Jing Yao, Tong Sha und Yu Song. „Pressure-Relief Impact Control of Open Circuit Hydraulic Pump-Controlled Forging Press System“. Processes 7, Nr. 9 (19.09.2019): 638. http://dx.doi.org/10.3390/pr7090638.
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Taking the open circuit hydraulic pump-controlled forging press system as the research object, according to the problems of pressure-relief impact of this system, the pressure-relief rules, mathematic models of the energy release rules, and the flow release rules were established, and the pressure-relief performance in different stages of each pressure-relief curve was analyzed. Based on the different requirements of the pressure gradient decrease, the combined pressure-relief curve (CPRC) was proposed to realize variable-pump eccentric magnitude planning. An experimental study on the pressure-relief process with CPRC was carried out. The results show that the pressure fluctuation of the pressure-relief pipe was reduced and the suppression effect of pressure-relief impact was better than that of the single regular pressure-relief curve. When the initial pressures were 10 MPa and 15 MPa, the pressure impact of the pressure-relief tube decreased by 45.45% and 37.5%, respectively, which realized the smooth pressure relief of the main cylinder.
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Matthujak, Anirut, Chaidet Kasamnimitporn, Wuttichai Sittiwong und Kulachate Pianthong. „Effect of Stand-Off Distance on Impact Pressure of High-Speed Water Jet Injected in Water“. Applied Mechanics and Materials 52-54 (März 2011): 1873–78. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.1873.
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This study is to measure the impact pressure of high-speed water jet injected in water at the stand-off distance from the nozzle exit. The high-speed water jets are generated by the impact of a projectile, which known as impact acceleration method, launched by Horizontal Single Stage Power Gun. The maximum averaged jet velocity of about 374.24 m/s in water was generated in this experiment. The impact pressure of high-speed water jet in water at the stand-off distance 15, 20, 30 and 40 mm from the nozzle exit was measured by the PVDF pressure sensor. Moreover, the impact phenomena of the jet were visualized by a high-speed video camera with shadowgraph optical arrangement. From the pressure sensor, two peak over-pressures are always observed in this experiment. From visualization, it was found that the two peak over-pressures of 24 GPa and 35 GPa at x = 15 mm were generated by the jet and the bubble impact, respectively. The peak over-pressure decreases exponentially as the stand-off distance between the PVDF pressure sensor to the nozzle exit increases. Moreover, the jet and the bubble impact on the PVDF pressure sensor, shock waves, and bubble deformation were obviously observed in this study.
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Baines, Annelie, Lee S. Cunningham und Benedict D. Rogers. „Shore-Side Downfall Pressures Due to Waves Impacting a Vertical Seawall: An Experimental Study“. Journal of Marine Science and Engineering 12, Nr. 12 (25.11.2024): 2149. http://dx.doi.org/10.3390/jmse12122149.
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As part of an investigation into downfall impacts from violent overtopping waves, experimental data are presented for the impact pressures and forces generated by regular and focused waves breaking onto a vertical wall and impacting a landward horizontal deck at a scale of 1:38. Particular attention is given to the wave-by-wave uprush and impact downfall events. By selecting regular and focused wave conditions that produce impacts, new trends are identified for violent downfall phenomena that could easily be underestimated in current practice. The characteristics of the downfall impacts are investigated and three different types of downfall impact are identified and discussed. Using a Wavelet Filter to denoise the signal from pressure probes without losing the peak impact pressures or introducing a phase shift, the distinctive features and dynamic behaviours of the white-water impacts are considered, and it is shown that downfall pressure magnitudes of 30–40 ρgH are regularly achieved. Dynamic impulse times of the events are also presented with higher-impact events generally relating to shorter impulse times, highlighting the dynamic character of these impacts. The largest downfall pressures are found to occur further from the vertical wall than previously measured. Importantly, the spray travelling furthest from the point of the initial wave impact on the vertical wall causes some of the largest downfall pressures on the deck. The paper concludes that, while the dataset is small, there are strong indications that the effects of these types of impacts are structurally significant and present a risk to infrastructure located landward of seawalls.
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Venis, W. A. „DETERMINATION OF THE WAVE ATTACK ANTICIPATED UPON A STRUCTURE FROM LABORATORY AND FIELD OBSERVATIONS“. Coastal Engineering Proceedings 1, Nr. 7 (29.01.2011): 37. http://dx.doi.org/10.9753/icce.v7.37.
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Model tests have been carried out to obtain an insight into the magnitude of the wave-pressures in various situations. These tests showed, that sharp high pressure peaks occur in addition to the pressures caused by the reflecting of the waves, which pressures are quasi-static. As the structure can be compared with a multiple mass-spring system these pressure-peaks may cause the whole construction to vibrate. Wave-attack therefore can be expressed in terms of impact. Moreover, calculations revealed that the impact pressures were critical factors in determining the strength of the structure.
So many model tests were carried out to determine the design and location of the sluices. These tests involved numerous water-levels discharges and waves. Regarding the pressure-peaks a comparative study was made in the model, which led to the structure being designed in such a way that the occurrence of critical impacts was reduced to an acceptable minimum. As it was impossible to avoid the occurrence of impact pressures entirely it remained necessary to determine a basic load for the structure that takes care of the impact pressures. As it has not yet appeared possible physically to determine a theoretical maximum for the impact pressures, it has to be borne in mind that there is a probability that each pressure measured will be exceeded. So this paper describes, how the cumulative frequency curve of the impacts for the case mentioned in 1.1 sub a, which served as a basis for determining the basic load was arrived at by a certain combination of laboratory and field observations. The data used for this purpose were a. Results of wave-impact measurements on a model of the sluices. This model, built in accordance with the results of the comparative study, was situated in the wind-flume of the "de Voorst" hydraulic laboratory. b. Wave height measurements in the Haringvliet during 1957 and 1958. c. Wind-speed measurements on board the lightship Qoeree, likewise during 1957 and 1958. d. Tidal registrations at Hellevoetsluis from 1920 to 1960. e. Wind-force data from the Hook of Holland, likewise from 1920 to 1960.
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Haut, R. C., T. M. Ide und C. E. De Camp. „Mechanical Responses of the Rabbit Patello-Femoral Joint to Blunt Impact“. Journal of Biomechanical Engineering 117, Nr. 4 (01.11.1995): 402–8. http://dx.doi.org/10.1115/1.2794199.
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Various studies suggest impact trauma may initially soften cartilage, damage subchondral bone, or a combination thereof. The initial damages are commonly thought due to excessive contact pressures generated on cartilage and the underlying bone. The objective of this research was to develop a small animal model for studying post-traumatic OA and to correlate contact pressures with tissue damage. Blunt insult was graded by dropping a rigid mass onto the hyperflexed hind limb of rabbits. Contact pressure in the patello-femoral joint was measured with pressure sensitive film. One, 3, 6, and 14 days later the animals were euthanized. Damage to cartilage and the underlying bone was assessed visually and in microscopic sections. Indentation experiments were performed on the patellar cartilage with a rigid, flat probe. Contact pressures were nonuniform over the articular surfaces and a high frequency of surface fissures were generated on the lateral facet in severe insults. The appearance of surface fissures correlated better with the magnitude of contact pressure gradients in the damage zone than the magnitude of contact pressures on the facet, per se. Blunt trauma causing surface fissures resulted in a measurable degree of softening in the patellar cartilage, especially close to the defects. Surgical intervention of the joint to insert pressure sensitive film, however, also resulted in significant softening of the cartilage.
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BREDMOSE, H., D. H. PEREGRINE und G. N. BULLOCK. „Violent breaking wave impacts. Part 2: modelling the effect of air“. Journal of Fluid Mechanics 641 (25.11.2009): 389–430. http://dx.doi.org/10.1017/s0022112009991571.
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When an ocean wave breaks against a steep-fronted breakwater, sea wall or a similar marine structure, its impact on the structure can be very violent. This paper describes the theoretical studies that, together with field and laboratory investigations, have been carried out in order to gain a better understanding of the processes involved. The wave's approach towards a structure is modelled with classical irrotational flow to obtain the different types of impact profiles that may or may not lead to air entrapment. The subsequent impact is modelled with a novel compressible-flow model for a homogeneous mixture of incompressible liquid and ideal gas. This enables a numerical description of both trapped air pockets and the propagation of pressure shock waves through the aerated water. An exact Riemann solver is developed to permit a finite-volume solution to the flow model with smallest possible local error.The high pressures measured during wave impacts on a breakwater are reproduced and it is shown that trapped air can be compressed to a pressure of several atmospheres. Pressure shock waves, reflected off nearby surfaces such as the seabed, can lead to pressures comparable with those of the impact. Typical examples of pressure-time histories, force and impulse are presented and discussed in terms of their practical implications. The numerical model proposed is relevant for a variety of flows where air effects are important. Further applications, including extended studies of wave impacts, are discussed.
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Adapa, Nikhil, und Kanu S. Goyal. „Impact of Casting and Splinting Manipulations on Below-Dressing Pressures: An Experimental Model“. HAND 14, Nr. 1 (06.09.2018): 48–55. http://dx.doi.org/10.1177/1558944718799391.
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Background: We tested how different applications of casts and splints affect underlying below-dressing pressures and how these dressings respond to swelling. Methods: A 3-in polyvinyl chloride pipe with an attached 100 mL saline bag to the outer surface was used to simulate a human forearm. A pressure transducer was attached to the bag and connected to a monitor providing continuous pressure measurements. Either a circumferential fiberglass cast or single-sided plaster splint was applied around the bag. To simulate the dressing’s compliance to soft tissue swelling, change in pressure was measured after 25 mL of saline was injected into the bag. Compliance was determined by calculating change in volume over change in pressure as volume was added. Results: In our 150 mL model, cast bivalving reduced pressure up to 28%, and splitting the cotton padding of a splint reduced pressures up to 33%. The mean compliance (ability to accommodate swelling) across all volume intervals was 182% greater in a bivalved cast versus a cast and 21% greater in a cotton-split splint versus a splint. Below-dressing pressure of a tightly wrapped elastic bandage was up to 2.76× greater than a medium tension bandage and up to 6.44× greater than a loosely applied bandage. A splint with real cotton padding had a 28% greater pressure than a splint with synthetic soft-roll padding. Conclusions: Splitting a dressing, utilizing synthetic cotton padding, and applying an elastic bandage cautiously can help reduce surface pressures and allow the construct to be more accommodating to soft tissue swelling.
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Li, Peng, Yan Liu, Jie Zhang, Zhihong Dong, Xinghui Wu, Shengjun Miao und Meifeng Cai. „Dynamic Failure Mechanism and Fractal Features of Fractured Rocks Under Quasi-Triaxial Static Pressures and Repeated Impact Loading“. Fractal and Fractional 9, Nr. 2 (23.01.2025): 71. https://doi.org/10.3390/fractalfract9020071.
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Mastering the dynamic mechanical behaviors of pre-stressed fractured rocks under repeated impact loads is crucial for safety management in rock engineering. To achieve this, repeated impact loading experiments were performed on produced fractured samples exposed to varying pre-applied axial and confining pressures using a split Hopkinson pressure bar test system in combination with a nuclear magnetic resonance imaging system, and the dynamic failure mechanism and fractal features were investigated. The results indicate that the dynamic stress–strain curves exemplify typical class II curves, and the strain rebound progressively diminishes with growing impact times. The impact times, axial pressure, and confining pressure all significantly affect the dynamic peak strength, average dynamic strength, dynamic deformation modulus, average dynamic deformation modulus, maximum strain, and impact resistance performance. Moreover, under low confining pressures, numerous shear cracks and tensile cracks develop, which are interconnected and converge to form large-scale macroscopic fracture surfaces. In contrast, specimens under a high confining pressure primarily experience tensile failure, accompanied by localized small-scale shear failure. Under low axial pressure, some shear cracks and tensile cracks emerge, while at high axial pressure, anti-wing cracks and secondary coplanar cracks occur, characterized predominantly by shear failure. In addition, as the confining pressure grows from 8 to 20 MPa, the fractal dimensions are 2.44, 2.32, 2.23, and 2.12, respectively. When the axial pressures are 8, 14, and 20 MPa, the fractal dimensions are 2.44, 2.46, and 2.52, respectively. Overall, the degree of fragmentation of the sample decreases with growing confining pressure and grows with rising axial pressure.
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Ke, Dandan, und Thitinant Wareewanich. „Institutional pressure and corporate green innovation—the influence of knowledge management process“. Edelweiss Applied Science and Technology 8, Nr. 6 (10.10.2024): 1240–57. http://dx.doi.org/10.55214/25768484.v8i6.2234.
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Using a multiple linear regression model constructed on data from construction firms in a province in eastern China, we investigated the impact of three types of institutional pressures from outside the firm on corporate green innovation and how the three knowledge management processes affect the relationship between them. We found that all three institutional pressures significantly positively impact corporate green innovation, with normative pressure having the most significant impact on corporate green innovation, followed by coercive pressure. The results also indicate that all three institutional pressures have an important mediating effect on green innovation through knowledge integration. Knowledge acquisition and knowledge sharing do not moderate the relationship between imitative pressure and green innovation. Thus, the findings emphasize the importance of institutional pressure and its role through knowledge integration for firms to achieve green innovation. The findings also emphasize the need to differentiate between similarities and differences between organizations to understand the impact of knowledge sharing on the relationship between institutional pressure and green innovation, thus increasing research on the conditions under which knowledge sharing contributes to green innovation in firms.
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Townsend, Jim, und M. Affan Badar. „Impact of condition monitoring on reciprocating compressor efficiency“. Journal of Quality in Maintenance Engineering 24, Nr. 4 (08.10.2018): 529–43. http://dx.doi.org/10.1108/jqme-06-2017-0040.
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Purpose Reciprocating compressors offer an efficient method of compressing almost any gas composition in a wide range of pressures and have numerous applications. Condition monitoring of critical rotating machinery is widely accepted by operators of centrifugal compressors. However, condition monitoring of reciprocating machinery has not received the same degree of acceptance. An earlier study (Townsend et al., 2016) was conducted on temperature monitoring. The purpose of this paper is to examine the impact of continuous pressure monitoring on electric-driven compressors. Design/methodology/approach This research analyzes the impact of continuous pressure monitoring on a fleet of 14 compressors transporting CO2 for enhanced oil recovery. The reliability and efficiency data on 14 reciprocating compressors over a three-year period were analyzed for failures detectable by the condition monitoring technology. The engineering economic analysis is presented to determine the impact this technology will have on the productivity of the compressors. Findings The study considers utilizing condition monitoring technology to analyze the pressure of the swept volume of the compressor cylinders. The results of the study indicate that continuous pressure monitoring technology has a strong impact on the productivity of the compressor fleet. The internal rate of return not only exceeds the operators hurdle rate, but the payback period is also dramatic. Pressure monitoring was found to be economically better than temperature monitoring. Originality/value The study reveals the economic benefits of implementing condition monitoring in the form of continuous pressure monitoring on reciprocating compressors.
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Yan, Shuncheng, Ruitian Zhang, Shaofeng Zhang und Xinwen Ma. „Methane Cluster Fragmentation by Fast Electron Impact“. Atoms 11, Nr. 2 (10.02.2023): 35. http://dx.doi.org/10.3390/atoms11020035.
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We investigate the fragmentation of the CH4 cluster by fast electron impact at stagnation pressures from 0.5 bar to 16 bar. By measuring the time of flight spectrum (TOF), two types of ions, including (CH4)n−1CH5+ and (CH4)n−2(C2Hm)+, are observed. In the 1D TOF spectrum, it is shown that for the stagnation pressure larger than 4 bar, the former ion is predominant for each n, similar to the previous experimental result. However, as the pressure decreases to 0.5 or 2 bar, the contribution of the C2Hm+ ion is dominant over that of the CH4CH5+ ion. In the 2D coincident TOF spectrum, the above two patterns of ions are also distinguished, and the enhancement of C2Hm+ is observed at 4 bar pressure. The phenomena appearing in 2D and 1D TOF spectra imply that the C2Hm+ ion prefers to survive in a smaller cluster, while the stabilization of the protonated ion needs a more massive cluster environment.
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Morizio, Paige L., Sara R. Britnell und Andreina A. Ottman. „Impact of national valsartan recalls on Veterans’ outcomes“. Therapeutic Advances in Drug Safety 12 (Januar 2021): 204209862110161. http://dx.doi.org/10.1177/20420986211016173.
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Background and Aims: Chemical impurities discovered in angiotensin receptor blocker (ARB) products in late 2018–2019 resulted in recalls of various products and has likely had downstream effects for patients and prescribers. The purpose of this study is to determine how the valsartan recall impacted clinical endpoints and prescribing of antihypertensives. Methods: This was a retrospective, single-center, cohort study including patients receiving recalled valsartan with essential hypertension who were mailed a recall letter on 12 March 2019. Mean blood pressure endpoints were collected 6 months before (pre-recall) and after the recall letter was mailed (post-recall). Antihypertensive medication changes and titrations were also characterized post-recall. Results: A total of 300 patients meeting eligibility criteria were included. There was no statistically significant difference in mean systolic blood pressure (SBP) or diastolic blood pressure (DBP) when pre- and post-recall blood pressures were compared (SBP: 137.2 mmHg versus 135.8 mmHg, p = 0.125; DBP: 78.6 mmHg versus 78.5 mmHg, p = 0.900). In addition, the percentage of patients with controlled blood pressure readings was similar in the pre- and post-recall timeframes (28% versus 27%, p = 0.72). A total of 33 medication changes involving valsartan occurred, with approximately one-third being changed to another ARB ( n = 11) or drug class ( n = 12). In total, 11 valsartan medication changes were specifically documented to be related to the valsartan recall. Conclusion: The results of this study indicate the valsartan recalls that occurred in 2019 did not significantly impact the clinical outcomes of the studied population. Plain Language Summary Impact of a medication recall on Veterans’ outcomes Background: Chemical impurities discovered in a class of blood pressure medications known as angiotensin receptor blockers (ARBs) occurred in late 2018–2019. This resulted in recalls of various products and has likely had downstream effects for patients and prescribers. Objective: The purpose of this study is to determine how the recall of valsartan, which is a medication in the ARB class, impacted clinical endpoints and prescribing of medications for blood pressure. Methods: This was a retrospective, single-center, cohort study including patients receiving recalled valsartan with high blood pressure who were mailed a recall letter on 12 March 2019. Blood pressure endpoints were collected 6 months before (pre-recall) and after the recall letter was mailed (post-recall). Medication changes and titrations were also characterized post-recall. Results: Three hundred patients meeting eligibility criteria were included. There was no difference found in systolic blood pressure (SBP) or diastolic blood pressure (DBP) when pre- and post-recall blood pressures were compared (SBP: 137.2 mmHg versus 135.8 mmHg; DBP: 78.6 mmHg versus 78.5 mmHg). In addition, the percent of patients with controlled blood pressure readings was similar in the pre- and post-recall timeframes (28% versus 27%). A total of 33 medication changes involving valsartan occurred, with approximately one-third being changed to another ARB ( n = 11) or drug class ( n = 12). Eleven valsartan medication changes were specifically documented to be related to the valsartan recall. Conclusions: The results of this study indicate the valsartan recalls that occurred in 2019 did not significantly impact the clinical outcomes of the studied population.
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Marsman, L. A., J. I. D. Vlasblom und M. F. Minnema. „Operational pressure and the SHP framework: Connecting the dots for safety“. Journal of Physics: Conference Series 2716, Nr. 1 (01.03.2024): 012071. http://dx.doi.org/10.1088/1742-6596/2716/1/012071.
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Abstract Operational pressure refers to pressure, whether induced or self-induced, that can affect the (flight) operation and may also impact safety. It is a hot topic in many sectors, being an important reason for multiple personnel strikes - the aviation sector is no exception here. Given the rapid evolution of these different operational pressures as the world adapts, continuous attention will be necessary for addressing the concept of operational pressure and discovering new mitigation strategies. Therefore, this paper delves deeper into both current and future factors influencing operational pressure, as well as mentioning some potential mitigating measures. Moreover, the case of operational pressure is structured and visualised using NLR’s Safety & Human Performance (SHP) framework. The result provides a structured overview of the impacts of different operational pressures on safety, which can aid in developing mitigations to lessen the effect of such pressures.
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Fisher, Kevin. „Managing Pressure To Mitigate Environmental Impact“. Journal of Petroleum Technology 72, Nr. 09 (01.09.2020): 43–45. http://dx.doi.org/10.2118/0920-0043-jpt.
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Ledger, S. N. „IMPACT AND PRESSURE RESISTANCE OF MANGOES“. Acta Horticulturae, Nr. 291 (Juni 1991): 508–18. http://dx.doi.org/10.17660/actahortic.1991.291.58.
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MULLER, G. „WAVE IMPACT PRESSURE PROPAGATION INTO CRACKS.“ Proceedings of the Institution of Civil Engineers - Water Maritime and Energy 124, Nr. 2 (Juni 1997): 79–85. http://dx.doi.org/10.1680/iwtme.1997.29770.
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Nseir, Saad. „Does polyurethane impact endotracheal cuff pressure?“ Critical Care Medicine 36, Nr. 7 (Juli 2008): 2219. http://dx.doi.org/10.1097/ccm.0b013e31817c47d9.
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Lucangelo, Umberto, Vittorio Antonaglia, Walter A. Zin und Massimo Borelli. „Does polyurethane impact endotracheal cuff pressure?“ Critical Care Medicine 36, Nr. 7 (Juli 2008): 2219–20. http://dx.doi.org/10.1097/ccm.0b013e31817c491f.
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YAMASHITA, Minoru, Takahisa NATSUME und Makoto NIKAWA. „Impact Blanking by Impulsive Fluid Pressure“. Proceedings of the Materials and processing conference 2016.24 (2016): 212. http://dx.doi.org/10.1299/jsmemp.2016.24.212.
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IMAI, Takayuki, Satoshi KOBAYASHI, Shuichi WAKAYAMA, Noriyuki KIUCHI, Yoshio SOHDA und Takayuki MATSUMOTO. „The Effect of Impact Damage on Internal Pressure in Impact-Resistant FW-FRP Composite Pressure Vessels“. Proceedings of the 1992 Annual Meeting of JSME/MMD 2003 (2003): 147–48. http://dx.doi.org/10.1299/jsmezairiki.2003.0_147.
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Hao, Xue Di, Chen Xin, Xin Cheng und Miao Wu. „Measurement of Axial Impact Force of Pipeline Transporting Thick Pastes“. Advanced Materials Research 490-495 (März 2012): 974–78. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.974.
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Due to alternating work mode of twin-cylinder of solid pump during high pressure pipeline transporting thick pastes, largde axial impact force is exerted on the pipeline, which makes pipe clamps, supports and bolts of flange damage to failure. By using twin dynamic force transducers and designing coresponding installation components for the transducers, impact forces at different flow rates, positions of the pipeline and transportation pressures were measured. Conclusions can be drawn as following: impact force increases with increasing flow rate, and decreases with increasing distance from the outlet of pump. The increased amount of impact force with increasing flow rate is larger under larger transportation pressure than that under samller transportation pressure. It is better to transport thick pastes at low system pressure, and to install more pipe clamps in the front part, and reverse in the back part of pipeline.
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Jaber Kadhim, Mohammed, und Dr Mohammed Ali Hassan. „EFFECTS MODERATING ROLE OF INFORMATION TECHNOLOGY IN THE AUDIT PROFESSION“. INTERNATIONAL JOURNAL OF RESEARCH IN SOCIAL SCIENCES & HUMANITIES 12, Nr. 04 (2022): 457–78. http://dx.doi.org/10.37648/ijrssh.v12i04.025.
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By examining the impact of auditor competence, time budget pressure, and audit complexity using information technology as a modifier of the assumed relationships, this study examines the impact of auditor competence, time budget pressure, and audit complexity on the audit profession. This study included 232 auditors working for professional audit firms in Iraq, with samples taken using the purposeful sampling method from up to 171 people. In addition, a questionnaire was distributed to research participants as the data source for this study. The data in this study were analyzed using the structural equation model (SEM) and partial least squares (PLS) with the Smart analysis tool PLS-SEM 4.0. Audit quality is positively impacted by auditor efficiency and time budget pressure, whereas audit complexity negatively impacts audit quality. Furthermore, understanding information systems can mitigate the impact of competence on the audit profession. In contrast, understanding information systems cannot mitigate the impact of time budget pressures and audit complexity.
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Webb, Jo-Anne, und Ambreen Chohan. „Impact of a new clinical mattress solution on interface pressure and comfort during supine lying“. Journal of Wound Care 32, Nr. 8 (02.08.2023): 513–18. http://dx.doi.org/10.12968/jowc.2023.32.8.513.
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Objective: Effective pressure management for individuals is critical for hospital and community-based care, to prevent the occurrence of pressure ulcers. This study explores the impact of a new mattress and topper solution on interface pressure and comfort during supine lying. Method: In this quantitative, healthy cohort study, patient–surface interface pressures were calculated for three mattresses (a standard hospital mattress, a new mattress solution (Levitex Foams Ltd., UK) and a dynamic air flow mattress) with and without an innovative topper solution (Levitex Foams Ltd., UK). Subjective comfort, contact surface area, peak and mean pressure and peak pressure index (head, sacrum, heels) were calculated for all mattress conditions for a 21-minute period. Results: A total of 27 healthy volunteers took part in this study. The new mattress solution decreased peak pressure significantly compared with the hospital and air mattresses (p<0.04). Lower peak pressures were observed for the hospital mattress compared with the dynamic air flow mattress. The new mattress solution improved comfort and significantly lowered (>30%; p≤0.005) heel and head pressure compared with the other surfaces. Both hospital and air mattresses significantly reduced pressure and improved comfort with the addition of the new topper solution (p<0.05). Conclusion: The new mattress solution used in this study offers a potentially improved pressure management solution for individuals. Implementation of the topper may also help to improve pressure management when used with existing standard or dynamic air flow mattresses.
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Tonneijck-Srpová, L., E. Venturini, K. N. P. Humblet-Hua und M. E. Bruins. „Impact of processing on enzymatic browning and texturization of yellow mealworms“. Journal of Insects as Food and Feed 5, Nr. 4 (25.10.2019): 267–77. http://dx.doi.org/10.3920/jiff2018.0025.
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The potential of Tenebrio molitor as an alternative protein source for food applications was investigated by using several conventional (blanching and freeze drying) and non-conventional (high pressure) processing techniques. Some of the challenges in product development are the browning effect of minced mealworms and the texturizing capacity after mincing. Both blanching and high pressure processing at 400 and 500 MPa proved to be effective in inactivating enzymes responsible for browning. However, the inactivation process was accompanied by a significant decrease in texturizing properties of the minced mealworms, especially when blanching was applied. Also when applying pressure, the texture changed from stronger (samples treated at lower pressures) to weaker (samples treated at higher pressures). Minced fresh or freeze dried mealworms provided textures with a reasonable strength and elasticity, but browning still occurred. Nevertheless, this browning could be slowed down by applying air tight packaging to prevent oxidation.
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Kim, Dong Hwi, Eun Soo Kim, Sung-chul Shin und Sun Hong Kwon. „Sources of the Measurement Error of the Impact Pressure in Sloshing Experiments“. Journal of Marine Science and Engineering 7, Nr. 7 (03.07.2019): 207. http://dx.doi.org/10.3390/jmse7070207.
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Sloshing experiments have increasingly received academic attention. Understanding the measurement errors in the sloshing impact pressures is an important parts of the sloshing experiments since these errors, which arise from experimental conditions, affect the subsequent results. As part of the research on the sources of the measurement errors, focused on the effects of surface conditions of pressure sensors on the measurement of impact pressures. Thirty-six integrated circuit piezoelectric pressure sensors were placed on the upper surfaces of a two-dimensional tank to measure the sloshing impact pressures under surge or pitch motions. For each motion, the experimental conditions were divided in two based on whether the surfaces of the sensors were dry or wet. The peak pressures of each test were measured as twenty repeated experiments to ensure reliability. The flow in the tank was visualized using a high-speed camera to observe and analyze macroscopic and microscopic phenomena along the sensor surface. Thermal shock effects were confirmed by varying the experimental temperature and that of the sensor surface. The effects of the wet surface and droplets formed on the sensor surface on pressure measurements are discussed.
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Zhao, Di, Fuqiang Deng und Lingxin Zhang. „Numerical investigation on the impact pressure induced by a cavitation bubble collapsing near a solid wall“. Physics of Fluids 35, Nr. 4 (April 2023): 043315. http://dx.doi.org/10.1063/5.0145499.
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Cavitation erosion often occurs on the surface of many underwater applications, which can cause severe damage to materials and reduce their performance. Since the cause of erosion is the impact pressure induced by the collapse of an individual cavitation bubble near the wall, to make a better prediction and prevent the damage potential, in this paper, we carry out systematic investigations on the impact characteristics by direct numerical simulation using a vapor bubble model. The volume of fluid (VOF) method is adopted to capture the interface between the two phases. The numerical results show that pressure wave and jet are two primary inducements of the impacts on the wall. The reason for the pressure wave impacts is the pressure wave emission after the collapse of the bubble's main part. And the reason for the jet impact is the stagnation pressure in front of the jet. After a parametric study of the two impacts with respect to the initial radius, driving pressure, and stand-off distance, the predicting equations for the pressure wave impact and jet impact are proposed at γ ≥ 1.74. When γ < 1.74, the impact pattern becomes complex due to the arrival time of the two impacts and the collapse of the vapor fragments right on the wall.
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Ahn, Chang-Kyun, und Seok-Won Lee. „Ground subsidence due to the backfill pressure in tunnel boring machine“. Proceedings of the International Association of Hydrological Sciences 382 (22.04.2020): 19–24. http://dx.doi.org/10.5194/piahs-382-19-2020.
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Abstract. In shield tunnel boring machine constructions, backfill pressure affects surface settlement and the stability of other underground structures nearby. Therefore, it is essential to pre-calculate backfill pressure in the design stage. This study examines and compares the seven internationally known backfill pressure calculation theories and calculates and analyzes the backfill pressures in six virtual ground conditions. The calculated backfill pressure increased as the ground cover increased, but the increase rate decreased. Also, this study performs a numerical analysis to identify the impact on ground settlement and tunnel crown settlement. In the end, settlement was more impacted by face pressure than backfill pressure in the unsaturated and saturated ground conditions. Also, as the ground cover increased, the impact of backfill pressure decreased, and as the applied face pressure decreased, the impact of backfill pressure increased.
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OGAWA, Kinya. „Impact. Visualization of Impact Force by Using Pressure Sensitive Paper.“ Journal of the Society of Materials Science, Japan 47, Nr. 1 (1998): 20–25. http://dx.doi.org/10.2472/jsms.47.20.
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Shi, H. H., J. E. Field und C. S. J. Pickles. „High Speed Liquid Impact Onto Wetted Solid Surfaces“. Journal of Fluids Engineering 116, Nr. 2 (01.06.1994): 345–48. http://dx.doi.org/10.1115/1.2910278.
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The mechanics of impact by a high-speed liquid jet onto a solid surface covered by a liquid layer is described. After the liquid jet contacts the liquid layer, a shock wave is generated, which moves toward the solid surface. The shock wave is followed by the liquid jet penetrating through the layer. The influence of the liquid layer on the side jetting and stress waves is studied. Damage sites on soda-lime glass, PMMA (polymethylmethacrylate) and aluminium show the role of shear failure and cracking and provide evidence for analyzing the impact pressure on the wetted solids and the spatial pressure distribution. The liquid layer reduces the high edge impact pressures, which occur on dry targets. On wetted targets, the pressure is distributed more uniformly. Despite the cushioning effect of liquid layers, in some cases, a liquid can enhance material damage during impact due to penetration and stressing of surface cracks.
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M, Muthukumar, Karthikeyan P, Mathews Eldho, Nagarathinam P, Panneer Selvam.E.P und Prasanna R. „IMPACT OF PRESSURE ON THE PERFORMANCE OF PROTON EXCHANGE MEMBRANE FUEL CELL“. JOURNAL OF ADVANCES IN CHEMISTRY 13, Nr. 9 (22.02.2017): 6462–67. http://dx.doi.org/10.24297/jac.v13i9.5739.
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The Proton Exchange Membrane (PEM) fuel cell performance not only depends on temperature but also depends on the operating pressure, which will increase the performance of the PEM fuel cell. The PEM fuel cell with serpentine flow field was modeled using Solidworks software and analyzed using ANSYS software. By analysis of three different pressures on the PEM fuel cell, and came to know that the optimum pressure gives the best performance. The peak power density occurs in the constant temperature of 323 K with the pressure of 2 bar.
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Juraschek, Stephen P., Anthony Ishak, Kenneth J. Mukamal, Marc L. Cohen und Jennifer L. Beach. „Impact of Clinic-Based Blood Pressure Approaches on Blood Pressure Measurement“. American Journal of Hypertension 33, Nr. 1 (23.08.2019): 26–30. http://dx.doi.org/10.1093/ajh/hpz118.
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Abstract BACKGROUND Clinic-based blood pressure (BP) is a closely-tracked metric of health care quality, but is prone to inaccuracy and measurement imprecision. Recent guidelines have advocated for automated office blood pressure (AOBP) devices to improve clinic-based BP assessments. METHODS Patients from a single hypertension clinic underwent a 3-day evaluation that included a 24-hour ambulatory blood pressure monitoring (ABPM), 2 manual clinic-based BP measurements (over 2 visits), and an unattended AOBP measurement (single visit). All measurements were compared to the average wake-time systolic BP (SBP) and diastolic BP (DBP) from ABPM. RESULTS Among 103 patients (mean age 57.3 ± 14.8 years, 51% women, 29% black) the average wake-time SBP was 131.3 ± 12.3 mm Hg and DBP was 78.3 ± 9.2 mm Hg. The average of 2 manual BPs was significantly higher than wake-time ABPM with mean differences of 5.5 mm Hg (P < 0.001) for SBP and 2.7 mm Hg (P = 0.002) for DBP. In contrast, the averages of the last 2 AOBP measurements did not significantly differ from ABPM with mean differences of 1.6 mm Hg (P = 0.21) for SBP and −0.5 mm Hg (P = 0.62) for DBP. The estimated prevalence of SBP ≥ 140 or DBP ≥ 90 mm Hg based on wake-time ABPM was 27.2% vs. 49.5% based on the average of 2 manual measurements (difference 22.3%; P < 0.001) and 31.1% based on the average of the last 2 AOBP measurements (difference 3.9%; P = 0.57). CONCLUSIONS A single visit, unattended AOBP more precisely estimated BP and the prevalence of stage 2 and uncontrolled hypertension than even the average of 2 manual clinic visits, supporting guideline recommendations to use AOBP for clinic-based BP measurements.
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Chen, Han, David K. Menon und Brian P. Kavanagh. „Impact of Altered Airway Pressure on Intracranial Pressure, Perfusion, and Oxygenation“. Critical Care Medicine 47, Nr. 2 (Februar 2019): 254–63. http://dx.doi.org/10.1097/ccm.0000000000003558.
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Macintyre, Lisa, Monali Dahale und Michelle Rae. „Impact of Moisture on the Pressure Delivering Potential of Pressure Garments“. Journal of Burn Care & Research 37, Nr. 4 (2016): e365-e373. http://dx.doi.org/10.1097/bcr.0000000000000272.
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Wakita, S., H. Genda, K. Kurosawa und T. M. Davison. „Enhancement of Impact Heating in Pressure‐Strengthened Rocks in Oblique Impacts“. Geophysical Research Letters 46, Nr. 23 (12.12.2019): 13678–86. http://dx.doi.org/10.1029/2019gl085174.
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Tong, Jianxiang, Hengyang Wang, Yuyi Wang, Ya Zhang und Xiaohe Huang. „Study on the impact of confining pressure on gas permeability of tight sandstone cores“. Journal of Physics: Conference Series 2076, Nr. 1 (01.11.2021): 012006. http://dx.doi.org/10.1088/1742-6596/2076/1/012006.
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Abstract Taking the tight sandstone core of Shengli Oilfield as the experimental sample, this paper studies the permeability variation of the tight sandstone under different confining pressures. The experimental results show that when the pore pressure is constant, the measured gas permeability of core decreases with the increase of confining pressure. Power function is more reasonable to describe the influence of confining pressure on permeability of tight sandstone between power function and exponential function. Analyze the impact of confining pressure on gas permeability of tight sandstone cores by using permeability change rate coefficient D and coefficient S.
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Helexa, M. „Monitoring the impact of tyre inflation pressure on tensile properties of forest tractors“. Research in Agricultural Engineering 60, No. 4 (27.11.2014): 127–33. http://dx.doi.org/10.17221/49/2013-rae.
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The article discusses monitoring of the impact of tyre inflation pressure on tensile properties of forest tractors. The <br />LKT 81 T forest tractor, manufactured byZŤS TEES, Martin (Slovak Republic) and widely used in Slovakia, was specifically chosen as the mechanised vehicle to be monitored. Tensile properties were examined using standard tensile tests, with a Tatra freight vehicle serving as the load vehicle. Actual measurements were performed on a concrete surface and on soil characterised as gravelly loam whose average moisture was 38%. The statistical methods used to verify the impact of significance from changes in tyre inflation pressure on selected tensile indicators were multi-factor analysis of variance (ANOVA) and Student’s t-test. Even though statistical analysis failed to directly confirm significance in the impact of changes of tyre inflation pressure on selected load indicators for a forest tractor fitted with standard tyres, positive changes can be discerned in measured dependencies. The article concludes with a discussion of the results obtained and their possible application in operational practice.
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Lembo, Silvia, Georg Niedrist, Bouchra El Omari, Paul Illmer, Nadine Praeg, Andreas Meul und Matteo Dainese. „Short-term impact of low air pressure on plants’ functional traits“. PLOS ONE 20, Nr. 1 (15.01.2025): e0317590. https://doi.org/10.1371/journal.pone.0317590.
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Lower atmospheric pressure affects biologically relevant physical parameters such as gas partial pressure and concentration, leading to increased water vapor diffusivity and greater soil water content loss through evapotranspiration. This might impact plant photosynthetic activity, resource allocation, water relations, and growth. However, the direct impact of low air pressure on plant physiology is largely unknown. This study examined the effects of low air pressure, alone and combined with two water inputs, on different functional traits of three plant species transplanted from montane grasslands at 1,500 m a.s.l. during the first four weeks of their early phenological stage: Trifolium pratense, Hieracium pilosella, and Brachypodium rupestre. Using the terraXcube Ecotron facility which can simulate different climatic conditions, we isolated the effect of air pressure from those of other, related environmental factors (temperature, humidity, and solar radiation) by simulating three different elevations with corresponding air pressures: 1,500 m a.s.l. (85 kPa, control scenario), 2,500 m a.s.l. (75 kPa), and 4,000 m a.s.l. (62 kPa) and we used two different water regimes to observe the combined effect of low air pressure and the impact of varying water inputs on plants. In T. pratense and H. pilosella, we observed an increase in stomatal conductance but a reduction in aboveground biomass at the lowest pressure compared to the control scenario after four weeks of incubation. Contrastingly, B. rupestre showed an interactive effect of air pressure and water treatment on chlorophyll and biomass nitrogen content, which were reduced under higher soil water conditions at 85kPa. This study serves as an initial step in isolating the specific impact of air pressure on plant physiology, demonstrating the potential of the facility for future research. The mixed response patterns across species highlight that atmospheric pressure could be a driving factor to consider when assessing plant responses along elevational gradient.
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Nishi, Masatoshi, Shigeru Tanaka, Akihisa Mori, Matej Vesenjak, Zoran Ren und Kazuyuki Hokamoto. „Mechanism Elucidation of High-Pressure Generation in Cellular Metal at High-Velocity Impact“. Metals 12, Nr. 1 (09.01.2022): 128. http://dx.doi.org/10.3390/met12010128.
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Cellular metals exhibit diverse properties, depending on their geometries and base materials. This study investigated the mechanism of high-pressure generation during the high-velocity impact of unidirectional cellular (UniPore) materials. Cubic UniPore copper samples were mounted on a projectile and subjected to impact loading using a powder gun to induce direct impact of samples. The specimens exhibited a unique phenomenon of high-pressure generation near the pores during compression. We elucidate the mechanism of the high-pressure phenomenon and discuss the pore geometries that contribute to the generation of high pressures.
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Saouane, Sofiane, Wolfgang Morgenroth, Hanns-Peter Liermann, Carsten Paulmann und Francesca Fabbiani. „The impact of pressure on β-Cyclodextrin·acetaminophen inclusion complexes“. Acta Crystallographica Section A Foundations and Advances 70, a1 (05.08.2014): C264. http://dx.doi.org/10.1107/s2053273314097356.
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Cyclodextrins (CDs) have attracted considerable interest as model systems in supramolecular host-guest chemistry. They are described as hollow truncated cones with a hydrophilic outer surface and a nonpolar inner cavity suitable for small molecules' encapsulation.[1] By virtue of their character, CDs are used as excipients to improve the aqueous solubility of active pharmaceutical ingredients (APIs). High-pressure crystallisation techniques have been established as a suitable tool for exploring the phenomenon of polymorphism and solvate formation of pharmaceutical compounds throughout numerous examples reported in the literature.[2] Thus, exploring the inclusion-complex formation and the polymorphic behaviour of CDs with APIs at high pressure would be an interesting extension of the technique. The present work describes the attempt of an in-situ crystallisation of β-CD·acetaminophen inclusion complex and compression studies of the known β-CD·acetaminophen complex[3] in different crystallisation media at pressures up to 1.0 GPa. A new high-pressure crystal form observed at 0.8 GPa as well as unexpected results are presented herein. The crystals have been characterised by means of polarised optical microscopy, Raman spectroscopy and single-crystal X-ray diffraction using both home and synchrotron sources.