Journal articles: 'Hydrostatic circuit'

1

Dong, Bi Zheng, and Deng Hua Li. "Design and Implementation of Digital Piezoelectric Constant Testing System." Applied Mechanics and Materials 668-669 (October 2014): 911–15. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.911.

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Digital piezoelectric constant testing system was designed in this paper, which was based on hydrostatic test method. The system is composed of hydrostatic device, charge amplifier circuit, peak holding circuit, A/D calibration circuit, data processing by DSP. Pressure-release value is obtained by digital pressure transmitter on the hydrostatic device. Combining with mean filtering and A/D calibration, DSP can sample accurate voltage signal. Considering the difference between the equivalent circuit of charge amplifier and its practical circuit, the calculated hydrostatic piezoelectric constant is in better agreement with the theoretical value. The experiment results show that the accuracy of testing system is less than 4%.

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Koury Costa, Gustavo, and Nariman Sepehri. "A Critical Analysis of Flow-Compensated Hydrostatic Single Rod Actuators: Simulation Study." Actuators 9, no. 3 (July 22, 2020): 58. http://dx.doi.org/10.3390/act9030058.

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It is well established that the differential cylinder area in pump-controlled single-rod actuators creates the need of correctly switching the connections between the main circuit lines and a charge circuit, in order to provide means for equalising the flows into and out of the pump and the actuator. Many attempts to automatically switch the charge circuit connections to either cap- and rod-sides of the hydraulic cylinder have been made through the years. However, in many of these attempts, strong oscillations in the cylinder motion were observed when operational quadrants were changed under some particular velocity and force conditions. In this paper, we perform a thorough numerical analysis for some representative pump-controlled single-rod actuators. The goal is to understand the causes of undesirable behaviour of several circuits under certain operating situations. We show through comprehensive simulations that all but one circuit design produces undesirable oscillatory results under these circumstances. This paper is built upon and complements a previously published paper by the same authors on this important subject.

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Petranský, I., and M. Bolla. "Testing stand for life tests of hydrostatic pumps with a polluted fluid." Research in Agricultural Engineering 49, No. 4 (February 8, 2012): 151–56. http://dx.doi.org/10.17221/4966-rae.

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Testing of the lifetime of hydrostatic transmissions can be done on special testing stands. Some testing stands use a pressure valve connected at the outlet of a pump. When using this design of stands, it is important to keep clear the operating fluid by filters and it is not possible to observe the influence of fluid pollution on the lifetime. The article presents a design of an electro-hydraulic testing stand with computer control system for accelerated lifetime tests of hydrostatic pumps under laboratory conditions when using a polluted operating fluid. A pump, which is mechanically connected with a hydrostatic motor, through a clutch, is an interface between the hydrostatic circuit of the tested pump and the hydrostatic circuit of the loading simulator. At lifetime testing, this interface makes it possible to use the polluted fluid in the hydraulic circuit of the tested pump, and thereby observe its influence. Instead of a polluted fluid, it is possible to use biodegradable oil and observe its influence on the lifetime of a pump. When using the same hydraulic fluid in both systems of the stand, it is possible to test two pumps at the same time.

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Koury Costa, Gustavo, and Nariman Sepehri. "A Critical Analysis of Valve-Compensated Hydrostatic Actuators: Qualitative Investigation." Actuators 8, no. 3 (July 30, 2019): 59. http://dx.doi.org/10.3390/act8030059.

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Hydrostatic actuation has gained interest from both academia and industry due to the unquestionable energetic advantages when compared to valve-controlled actuators; the main feature being the absence of throttling losses due to the direct control of the cylinder by the pump. However, the fact that the great majority of applications are based on single-rod cylinders has been both a challenge and a source of inspiration for a variety of different circuit designs. In an attempt to compensate for the uneven flows coming in and out of differential cylinders, several solutions have been proposed, including the use of hydraulic transformers, individual pumps connected to the cylinder ports or pumps with unmatched input and output flows. The simplest approach, however, seems to be the use of compensation valves in the circuit, which is the focus of this paper. Here, we analyse some representative circuits proposed along the years in a direct and elucidative manner, showing that the definitive solution to the single-rod actuator control problem has been established, paving the road for introducing stable and trustworthy circuits, which can be commercially used in the near future.

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Mandal, S. K., K. Dasgupta, S. Pan, and A. Chattopadhyay. "Theoretical and experimental studies on the steady-state performance of low-speed high-torque hydrostatic drives. Part 2: Experimental investigation." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 223, no. 11 (July 6, 2009): 2675–85. http://dx.doi.org/10.1243/09544062jmes1203.

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The performance investigations of an open-circuit and a closed-circuit low-speed high-torque hydrostatic drive are presented. The modelling of both drives and determination of their loss coefficients are presented in Part 1 of this article (pg. 2663 of this issue). This study determines and analyses the overall efficiency and slip characteristics of the hydrostatic drives using the expressions describing the characteristics of their loss coefficients. The effects of critical control parameters of the pumps and the motor are investigated on the basis of their steady-state performance. This investigation is based on the performance of the hydrostatic transmission drives at different torque levels.

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TROPP, Michal, and Ronald BASTOVANSKY. "APPLICATION OF HYDRAULIC CIRCUIT IN MECHATRONIC SYSTEMS." Journal of Technology and Exploitation in Mechanical Engineering 2, no. 1 (December 26, 2016): 5–10. http://dx.doi.org/10.35784/jteme.404.

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This paper focuses on the calculations of basic variables of the hydrostatic circuits in the mechatronic systems. These calculations are important for machines used for forming materials by means of great forces, e.g. hydraulic press. Due to differences in equipment design, lack of a universal method of calculation is noticeable. It is necessary to determine the coefficients required for the calculations in an experimental way.

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Cai, Bao Ping, Yong Hong Liu, Yan Ting Zhang, Jiang Tao Ma, Yun Wei Zhang, Yu Juan Zhuang, Pei Wei Lu, and Yu Gui Luo. "Development of Test System for Subsea Tree Equipment." Applied Mechanics and Materials 440 (October 2013): 222–27. http://dx.doi.org/10.4028/www.scientific.net/amm.440.222.

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A test system for subsea tree equipment is developed for tree function testing after repair. The test system mainly consists of hydraulic unit and electric unit. The hydraulic unit is developed by revamping an old hydraulic power unit, which consist of six components, including reservoir, flush/fill pump circuit, high pressure hydraulic pump circuits, accumulator group, hydraulic supply circuits and fluid return circuit. The electric unit for subsea tree is developed by using NI Compact DAQ system, In order to control the hydraulic unit and acquire the pressure signals easily. The test procedures for flowloops, valve, and hydrostatic hydraulic pressure cycling are proposed based on the factory acceptance testing of subsea tree. A test for a repaired subsea tree is performed by using the developed test system. The results show that the repaired subsea tree is good enough after repair, and verify that the developed test system works well.

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Wang, Edward C. Y., Jey-Myung Lee, John P. Johnson, Thomas R. Kleyman, Robert Bridges, and Gerard Apodaca. "Hydrostatic pressure-regulated ion transport in bladder uroepithelium." American Journal of Physiology-Renal Physiology 285, no. 4 (October 2003): F651—F663. http://dx.doi.org/10.1152/ajprenal.00403.2002.

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The effect of hydrostatic pressure on ion transport in the bladder uroepithelium was investigated. Isolated rabbit uroepithelium was mounted in modified Ussing chambers and mechanically stimulated by applying hydrostatic pressure across the mucosa. Increased hydrostatic pressure led to increased mucosal-to-serosal Na+ absorption across the uroepithelium via the amiloride-sensitive epithelial Na+ channel. In addition to this previously characterized pathway for Na+ absorption, hydrostatic pressure also induced the secretion of Cl– and K+ into the mucosal bathing solution under short-circuit conditions, which was confirmed by a net serosal-to-mucosal flux of 36Cl– and 86Rb+. K+ secretion was likely via a stretch-activated nonselective cation channel sensitive to 100 μM amiloride, 10 mM tetraethylammonium, 3 mM Ba2+, and 1 mM Gd3+. Hydrostatic pressure-induced ion transport in the uroepithelium may play important roles in electrolyte homeostasis, volume regulation, and mechanosensory transduction.

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Liu, Huanlong, Dafa Li, Guanpeng Chen, Chixin Xie, Jiawei Wang, and Lei Feng. "Research on power coupling characteristics and acceleration strategy of electro-hydrostatic hydraulic hybrid power system." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 235, no. 8 (January 25, 2021): 1445–59. http://dx.doi.org/10.1177/0959651820987729.

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Aiming at the adverse effect of the peak power of the electric motor of the battery-powered rail vehicles on the battery life and the driving range when starting or accelerating, a new type of electro-hydrostatic hydraulic hybrid powertrain is designed. This article proposes a novel power form that assists the vehicle to start or accelerate through two power coupling methods: torque coupling circuit and flow rate coupling circuit which have good power performance and energy-saving performance. A mathematical model for power coupling of hybrid power system is constructed, and the effects of key parameters of the system and different power coupling ratios on electric power consumption and power coupling characteristics are studied. Based on the simulation and test platform, the power coupling characteristics of the electro-hydrostatic hydraulic hybrid powertrain are simulated and experimentally researched. The results show that compared with the traditional electro-hydrostatic series system, the novel electro-hydrostatic hydraulic hybrid powertrain can effectively avoid the impact of electric motor power and reduce the power consumption. Based on the characteristics of power coupling, the acceleration strategy of minimum peak power is studied to control the key components of the power coupling process. Simulation and experimental results show that under the control of the new acceleration strategy, the electro-hydrostatic hydraulic hybrid powertrain has good electro-hydraulic power coupling characteristics. The electric power of the power system is greatly reduced during acceleration, which has better energy-saving characteristics and value for engineering applications.

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Drabant, Š., M. Bolla, A. Žikla, I. Petranský, and J. Ďuďák. "Testing device with opened hydrostatic circuit for dynamic loading of the tractor engine by power take off shaft." Research in Agricultural Engineering 51, No. 3 (February 7, 2012): 91–98. http://dx.doi.org/10.17221/4909-rae.

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The developed loading device with opened hydrostatic circuit for measurement of speed and dynamic characteristics of the tractor engine by power take off is presented. This loading device may also be used as a portable type for field measurement. At present for development of these loading devices controlled hydrogenerators and electro-hydraulic proportional pressure valves directed by computer may by used to adjust geometrical volume of the hydrogenerator from zero to maximum value. There is a possibility to built these devices which consist of one hydrogenerator and one by-pass valve for the maximum power of internal combustion engine 420 kW which is sufficient from the point of view of practical need. Thus optional loading regime may be used according to the tractor engine horsepower to achieve the required accuracy of measurement.

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11

Stan, Gheorghe. "Floating Hydrostatic Bearings for Numerically Controlled Machine Tools." Applied Mechanics and Materials 809-810 (November 2015): 730–35. http://dx.doi.org/10.4028/www.scientific.net/amm.809-810.730.

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The use of hydrostatic guideways in CNC machine-tools is very common as a result of their low friction coefficient. The major problem of hydrostatic guideways represents the recovery of the fluid used in guideways, where the fluid should be protected against mechanical impurities and then led towards the hydraulic aggregate. The floating support described in this paper resolves the collection of fluid by using a closed circuit, without exposing the fluid to mehanical impurities and to a gravitational collecting.

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Escobar, E., C. Ibarra, E. Todisco, and M. Parisi. "Water and ion handling in the rat cecum." American Journal of Physiology-Gastrointestinal and Liver Physiology 259, no. 5 (November 1, 1990): G786—G791. http://dx.doi.org/10.1152/ajpgi.1990.259.5.g786.

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The minute-by-minute net water movement (Jw) in the rat cecum was correlated with the transepithelial potential difference (PD), short-circuit current (Isc), and the unidirectional Na+, Cl-, and Rb+ fluxes, with the following results. 1) Jw was a linear function of the applied hydrostatic or osmotic transepithelial gradients (hydrostatic permeability coefficiency = 0.164 +/- 0.018 cm/s, n = 13; osmotic permeability coefficient = 0.0014 +/- 0.0002 cm/s, n = 6). 2) A fraction of this absorptive Jw (0.17 +/- 0.03 microliter.min-1.cm-2, n = 13) was independent of the presence of any osmotic, hydrostatic, or chemical gradient. 3) This fraction was Na+ dependent, associated with an amiloride-insensitive PD and net Na+ (2.37 +/- 0.68 mu eq.h-1.cm-2, n = 6) and Cl- influxes (3.45 +/- 1.46 mu eq.h-1.cm-2, n = 6), measured under short-circuit conditions. No net Rb+ movement was detected. 4) The absorptive Jw increased when HCO3- was replaced by tris(hydroxymethyl)aminomethane (Tris+) buffer or Cl- by SO4(2-). A good agreement between the observed and the expected Jw (assuming isosmotic reabsorption) was observed in the absence of HCO3-. 5) The presence of an osmotic but not a hydrostatic transepithelial gradient generated a transepithelial PD. These results show that water movement across the rat cecum in vitro is the result of a combination of hydrostatic-, osmotic-, and transport-associated transfers. Concerning this last driving force, the observed results indicate that the transport-related Jw results from the addition of an absorptive Jw, coupled to a nonelectrogenic NaCl entry, plus a secretory Jw probably coupled to HCO3- secretion.

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13

Kumar, Ajit, K. Dasgupta, and J. Das. "Analysis of decay characteristics of an accumulator in an open-circuit hydrostatic system with pump loading." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 231, no. 4 (April 2017): 312–26. http://dx.doi.org/10.1177/0959651817700780.

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The effects of the decay characteristics of a hydraulic accumulator on the responses of the hydrostatic drive system used in mining vehicles are studied in this article. The system considered for the analysis basically consists of a hydraulic pump, hydro-motor, accumulator and a loading circuit. The studies have been carried out with respect to two different sizes of accumulators. The system model has been made in MATLAB/Simulink® environment. The simulation test results are obtained with respect to the hydro-motor speeds and the system pressure at different resistive loads and capacities of the accumulator and they are verified with the experimental test data. Using the validated model, the parametric studies are also made on the speed responses of the hydrostatic drive for different precharge pressures of the accumulator and inertial load on the motor shaft. The studies made in this article may be useful for the selection of proper capacity of accumulators incorporated in the hydrostatic drive system in mining vehicles.

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Vardhan, Alok, K. Dasgupta, N. Kumar, and Santosh Kr Mishra. "Steady-state performance investigation of open-circuit hydrostatic drives used in the rotary head of drill machine." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 233, no. 1 (October 31, 2017): 3–20. http://dx.doi.org/10.1177/0954408917738973.

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This paper highlights the steady-state performance of open-circuit hydrostatic drives for the rotary head of drill machine through modeling and experiment. In this respect, two alternative drive systems are considered. A drive system that consists of a variable displacement pump and two high-speed low-torque hydro-motors with a gear reducer unit and the other one consists of an identical pump and a low-speed high-torque hydro-motor. The steady-state model of the proposed drive arrangements is made by bondgraph simulation technique, where the relationship of the various losses of the components are obtained as a function of operating parameters and are identified experimentally. Using them, the slip and torque loss along with the overall efficiency of the drives are characterized. The performances of the hydrostatic drives are compared for the usual operating speed range of the drill machine used in mining operation. The studies made also identify the operating range of the proposed hydrostatic drives with reasonable efficiency.

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Mandal, S. K., K. Dasgupta, S. Pan, and A. Chattopadhyay. "Theoretical and experimental studies on the steady-state performance of low-speed high-torque hydrostatic drives. Part 1: Modelling." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 223, no. 11 (July 6, 2009): 2663–74. http://dx.doi.org/10.1243/09544062jmes1202.

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In this article the steady-state models of an open-circuit and a closed-circuit hydrostatic transmission (HST) drive have been developed to study their performances. A low-speed high-torque multi-stroke cam plate type radial piston motor is considered for both HST drives. Bondgraph simulation technique has been used to model the drives. The multi-bondgraph representation of the HST drives is presented; it takes into account the compression and expansion phases, which occur sequentially in the hydraulic motor. A reduced bondgraph model of the drives has been proposed, where various losses are lumped into suitable resistive elements. The relationships of the loss coefficients with other state variables, obtained from the reduced model, are identified through experimental investigation. The loss coefficients are found to have a non-linear relationship with the load torque and the supply flowrate. Using the characteristics of these loss coefficients, the steady-state performances of the hydrostatic drives are studied in Part 2 of this article (pg. 2675 of this issue).

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Choe, JoonWon, Jesus Noel Calat, and Guo-Quan Lu. "Constrained-film sintering of a gold circuit paste." Journal of Materials Research 10, no. 4 (April 1995): 986–94. http://dx.doi.org/10.1557/jmr.1995.0986.

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We studied the constrained-film sintering of a gold circuit paste used in microelectronic packaging applications. Optical techniques were developed to determine the shrinkage profiles of constrained and free films and stresses generated during sintering in the constrained films. Constrained films approximately 60 μm thick were made by multiple screen-printing of the gold paste on rigid alumina substrates, while the free films were obtained by peeling off portions of the gold films from the substrate after binder burnout. Constrained films for stress measurement were made by multiple screen-printing on an oxidized 25 μm thick silicon substrate. Sintering runs were done in a hot stage at temperatures between 650 °C and 900 °C. The densification rates were much lower in the constrained films than those in the free films. The in-plane tensile stresses in the constrained films, determined by wafer curvature measurement, rose rapidly to a maximum level of 510 kPa during the initial stage of sintering and then gradually decreased. The reduction in the sintering potential due to the hydrostatic stress is not large enough to completely account for the retarded densification in constrained films. SEM micrographs of the film microstructures after sintering showed no-significant difference in grain growth kinetics between the constrained and free films. However, the activation energy for densification was found to be very different between the two types of films, 90.1 ± 4.3 kJ/mole for the free film and 188.8 ± 6.7 kJ/mole for the constrained film. We suggest that the retarded densification kinetics in the constrained gold films is due to (i) the reduction in the sintering potential by the hydrostatic stress and (ii) a change in the dominant sintering mechanism from grain-boundary diffusion in the free films to lattice diffusion in the constrained films.

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Yoshimoto, S., Y. Anno, M. Tamura, Y. Kakiuchi, and K. Kimura. "Axial Load Capacity of Water-Lubricated Hydrostatic Conical Bearings With Spiral Grooves (On the Case of Rigid Surface Bearings)." Journal of Tribology 118, no. 4 (October 1, 1996): 893–99. http://dx.doi.org/10.1115/1.2831625.

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This paper describes the static characteristics of water-lubricated hydrostatic conical bearings with spiral grooves. Hydrostatic conical bearings treated here have been designed for high speed spindles and are intended to apply to spindles for drilling small holes of printed circuit-boards. Pressurized water is first fed to the inside of the rotating shaft and supplied to spiral grooves on the shaft surface through feeding holes. Therefore, water pressure is greatly increased at outlets of feeding holes due to the centrifugal force by shaft rotation. Furthermore, water pressure is also increased by the viscous pump effect of spiral grooves. Water pressures in the bearings under concentric condition are numerically obtained by using the finite element method and calculated results are compared with experimental ones. It is consequently found that this water-lubricated hydrostatic conical bearings with spiral grooves are very suitable for precision high speed spindles.

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Vedachalam, Narayanaswamy, Arunachalam Umapathy, Sethuram Muthukrishna Babu, Kandan Venketesan, Nanda Kumar Suresh Kumar, and Malayath Aravindakshan Atmanand. "Performance of Electromagnetic Oil Circuit Breakers Under Hyperbaric Conditions." Marine Technology Society Journal 53, no. 1 (January 1, 2019): 74–82. http://dx.doi.org/10.4031/mtsj.53.1.8.

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AbstractUnderstanding the influence of ambient hydrostatic pressure in the electric circuit breaking performance of pressure-compensated (PC) electromagnetically actuated oil circuit breakers is essential for the design of reliable deep ocean power systems. Experiments are conducted using an industry-standard 300-V direct current PC power contactor in a hyperbaric chamber. It is identified that at 150-bar pressure, the circuit breaking duration and arc energy reduce fivefold and threefold, respectively, compared to their performance at 1-bar conditions. At pressures greater than 200 bar, the circuit breaker opening duration increases due to the increase in the viscosity of the dielectric PC oil. This leads to increased arc energy and formation of larger carbon conglomerations due to the breakdown of dielectric oil. During the hyperbaric experiments, the pressure-induced viscosity increase was offset by increasing the oil temperature.

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Kumar, N., and K. Dasgupta. "Steady-state performance investigation of hydrostatic summation drive using bent-axis hydraulic motor." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 17 (November 17, 2014): 3234–51. http://dx.doi.org/10.1177/0954406214559410.

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This article investigates the steady-state performance of a closed-circuit hydrostatic summation drive used in heavy earth moving machine through modelling and experiment. The proposed drive basically consists of variable displacement pump and bent-axis motor. The performance studies of the drive have been made for its two different modes of operation: using single motor and two motors. Bondgraph simulation technique is used to model the drive, where various losses are lumped into suitable resistive elements. The relationships of the losses with the state variables obtained from the model are identified through experiments. The dependencies of the loss characteristics on the load torque and the pump displacement ratio are studied. The model has been verified experimentally. The performances of the hydrostatic drives are studied at different torque levels with respect to its slip, torque-loss and overall efficiency, using the expressions describing the characteristics of the loss-coefficients. The investigation also identifies the operating range of the proposed hydrostatic drives with reasonable efficiency.

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Kumar, N., K. Dasgupta, and SK Ghoshal. "Dynamic analysis of a closed-circuit hydrostatic summation drive using bent axis motors." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 229, no. 8 (May 15, 2015): 761–77. http://dx.doi.org/10.1177/0959651815583197.

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Pascu, Marius, and Gheorghe Stan. "Experimental Research Regarding the Influence of Hydraulic Resistances on the Hydrostatic Guideways Stiffness." Applied Mechanics and Materials 657 (October 2014): 475–79. http://dx.doi.org/10.4028/www.scientific.net/amm.657.475.

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A very important factor for the hydrostatic guideways is given by the presence of the restrictor on the supply circuit, whose hydraulic resistance may have important effects on the lubricant film behaviour and implicitly, on the static and dynamic stiffness of the system. This paper presents a new method of experimental research regarding the hydrostatic guideway stiffness, depending on the hydraulic resistances values which supply each pocket. During the experiments which approach the influence of the hydraulic resistances values of the restrictors on the hydrostatic guideway stiffness, a centered constant loads of 20, 50 and 100 [daN] was used. The experiments were carried out on an experimental setup composed of an open hydrostatic guideway, having the pocket dimensions of 150x88 [m, supplied with liquid under pressure through means of a pack of adjustable restrictors. The obtained experimental results are presented in both tabular and graphical form and constitute an experimental database which can be used by the machine tools designers and manufacturers. The paper contains recommendations regarding the usage of hydraulic resistances values depending on the machine tool type and size. Also, from the obtained results, recommendations can be made with regard to the type of restrictors to be used, so that the lubricant filtration grade is comprised between admissible values.

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Guo, Xiaofan, and Andrea Vacca. "Advanced Design and Optimal Sizing of Hydrostatic Transmission Systems." Actuators 10, no. 9 (September 21, 2021): 243. http://dx.doi.org/10.3390/act10090243.

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This paper presents a novel method for designing and sizing high-efficient hydrostatic transmissions (HTs) for heavy duty propulsion applications such as agricultural and construction machinery. The proposed method consists in providing cost effective HT architectures that maximizes efficiency at the most frequent operating conditions of the transmission, as opposed to the traditional HT design methods based on the most demanding requirements of the system. The sizing method is based on a genetic optimization algorithm for calculating the optimal displacement of the main units of the HT to maximizes the efficiency in the most frequent operating conditions of the vehicle. A simulation model for HTs is built in MATLAB/Simulink® environment to test three different circuit alternatives for basic HTs. Considering a particular 250 kW heavy-duty application for which drive cycle data were available, this study shows great improvement in energy efficiency (14%) and power saving (20.1%) at frequent operating conditions while still achieving the corner power condition.

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Moreno-Uribe, Andrés M., Alexandre Q. Bracarense, and Ezequiel C. P. Pessoa. "The Effect of Polarity and Hydrostatic Pressure on Operational Characteristics of Rutile Electrode in Underwater Welding." Materials 13, no. 21 (November 6, 2020): 5001. http://dx.doi.org/10.3390/ma13215001.

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In order to provide a better understanding of the phenomena that define the weld bead penetration and melting rate of consumables in underwater welding, welds were developed with a rutile electrode in air welding conditions and at the simulated depths of 5 and 10 m with the use of a hyperbaric chamber and a gravity feeding system. In this way, voltage and current signals were acquired. Data processing involved the welding voltage, determination of the sum of the anodic and cathodic drops, calculation of the short-circuit factor, and determination of the melting rate. Cross-sectional samples were also taken from the weld bead to assess bead geometry. As a result, the collected data show that the generation of energy in the arc–electrode connection in direct polarity (direct current electrode negative-DCEN) is affected by the hydrostatic pressure, causing a loss of fusion efficiency, a drop of operating voltage, decreased arc length, and increased number of short-circuit events. The combination of these characteristics kept the weld bead geometry unchanged, compared to dry weld conditions. With the positive electrode (direct current electrode positive-DCEP), radial losses were derived from greater arc lengths resulting from increasing hydrostatic pressure, which led to a decrease in weld penetration.

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Hasan, Md Ehtesham, Sanjoy K. Ghoshal, and K. Dasgupta. "Speed Control of a Hydraulic Motor." Applied Mechanics and Materials 592-594 (July 2014): 2239–43. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.2239.

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In this article a negative feedback Proportional Integral (PI) control of pump displacement is presented to attain desired speed of hydromotor in the loading circuit of a pedagogical open loop Hydrostatic transmission system (HST) under varying load condition. By using the state equations derived from model, a novel system inversion procedure is proposed to obtain the required pump displacement. The control strategy through system inversion is validated through bond graph model simulation.

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Montesdeoca, D., P. J. Carrington, I. P. Marko, M. C. Wagener, S. J. Sweeney, and A. Krier. "Open circuit voltage increase of GaSb/GaAs quantum ring solar cells under high hydrostatic pressure." Solar Energy Materials and Solar Cells 187 (December 2018): 227–32. http://dx.doi.org/10.1016/j.solmat.2018.07.028.

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Chen, Wanqiang, Zhaorui Xu, Yeqi Wu, Yehui Zhao, Guangming Wang, and Maohua Xiao. "Analysis of the shift quality of a hydrostatic power split continuously variable cotton picker." Mechanical Sciences 12, no. 1 (June 1, 2021): 589–601. http://dx.doi.org/10.5194/ms-12-589-2021.

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Abstract. In order to improve the ride comfort of a continuously variable cotton picker, the shift quality of the cotton picker is analysed. Firstly, the transmission principle of the hydrostatic power split continuously variable transmission (CVT) with a single planetary gear set is introduced; secondly, the shift dynamic model of the power train is constructed, and the key models are verified by experiments; finally, the influence law and mechanism of various factors in the shift qualities of a cotton picker are analysed. The results show that the increase in main circuit pressure will reduce the shift quality of the cotton picker; the influence of clutch-charging flow and acceleration rate on the shift quality of the cotton picker can be ignored; with the action time of the clutch delayed in a certain range, the shift impact first decreases slightly, then increases, and finally decreases; the increase in the cotton box weight can slightly improve the shift quality of the cotton picker but is at the cost of consuming more clutch-sliding energy. If different factors are evaluated together, the value of the main circuit pressure and charging flow should not be too large or too small. At the same time, the action time of a clutch to be disengaged should be delayed, and the action time of a clutch to be engaged should be advanced. The conclusions of this study can provide theoretical support for the controller development of a continuously variable cotton picker.

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Gečys, S., S. Gudžius, L. Markevičius, and A. Morkvėnas. "Critical Slip in Maximum Electromagnetic Power of a Motor for Borehole Prospecting Mechatronic Devices." Solid State Phenomena 113 (June 2006): 55–60. http://dx.doi.org/10.4028/www.scientific.net/ssp.113.55.

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The extraordinary conditions for borehole motors such as: wide operating medium temperature change interval from –20oC up to +250oC, hydrostatic pressure changes from atmospheric up to 210 MPa, operating medium – dielectric liquid, limited power source, long geophysical, cable of up to 10,000 m non-constant load, due to the operating cycle have influence on their reliable operating, maximum power transmission, and change of characteristics. In this particular case, it is important to know the maximum electromagnetic power, which may be created by the motor. The critical slip and maximum electromagnetic power of the induction motor with a solid rotor supplied from a limited power-source and through the complex circuit, taking into account the parameters of the motor and supply circuit, as well as the operating peculiarities, have been derived. The study of computed characteristics of the borehole motor, taking into account the above-mentioned conditions, show that the motor supplied from a limited power-supply source and through the complex circuit should be investigated inseparably from the whole system.

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Bastarache, Julie A., J. Brennan McNeil, Erin J. Plosa, Jennifer S. Sucre, V. Eric Kerchberger, Luke E. Habegger, Elizabeth Weddle, et al. "Standardization of methods for sampling the distal airspace in mechanically ventilated patients using heat moisture exchange filter fluid." American Journal of Physiology-Lung Cellular and Molecular Physiology 320, no. 5 (May 1, 2021): L785—L790. http://dx.doi.org/10.1152/ajplung.00595.2020.

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Noninvasive sampling of the distal airspace in patients with acute respiratory distress syndrome (ARDS) has long eluded clinical and translational researchers. We recently reported that fluid collected from heat moisture exchange (HME) filters closely mirrors fluid directly aspirated from the distal airspace. In the current study, we sought to determine fluid yield from different HME types, optimal HME circuit dwell time, and reliability of HME fluid in reflecting the distal airspace. We studied fluid yield from four different filter types by loading increasing volumes of saline and measuring volumes of fluid recovered. We collected filters after 1, 2, and 4 h of dwell time for measurement of fluid volume and total protein from 13 subjects. After identifying 4 h as the optimal dwell time, we measured total protein and IgM in HME fluid from 42 subjects with ARDS and nine with hydrostatic pulmonary edema (HYDRO). We found that the fluid yield varies greatly by filter type. With timed sample collection, fluid recovery increased with increasing circuit dwell time with a median volume of 2.0 mL [interquartile range (IQR) 1.2–2.7] after 4 h. Total protein was higher in the 42 subjects with ARDS compared with nine with HYDRO [median 708 µg/mL (IQR 244–2017) vs. 364 µg/mL (IQR 136–578), P = 0.047], confirming that total protein concentration in HME is higher in ARDS compared with hydrostatic edema. These studies establish a standardized HME fluid collection protocol and confirm that HME fluid analysis is a novel noninvasive tool for the study of the distal airspace in ARDS.

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Uemura, Satoshi, Takahiro Mochizuki, Kengo Amemiya, Goyu Kurosaka, Miho Yazawa, Keiko Nakamoto, Yu Ishikawa, Shingo Izawa, and Fumiyoshi Abe. "Amino acid homeostatic control by TORC1 in Saccharomyces cerevisiae under high hydrostatic pressure." Journal of Cell Science 133, no. 17 (August 14, 2020): jcs245555. http://dx.doi.org/10.1242/jcs.245555.

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ABSTRACTMechanical stresses, including high hydrostatic pressure, elicit diverse physiological effects on organisms. Gtr1, Gtr2, Ego1 (also known as Meh1) and Ego3 (also known as Slm4), central regulators of the TOR complex 1 (TORC1) nutrient signaling pathway, are required for the growth of Saccharomyces cerevisiae cells under high pressure. Here, we showed that a pressure of 25 MPa (∼250 kg/cm2) stimulates TORC1 to promote phosphorylation of Sch9, which depends on the EGO complex (EGOC) and Pib2. Incubation of cells at this pressure aberrantly increased glutamine and alanine levels in the ego1Δ, gtr1Δ, tor1Δ and pib2Δ mutants, whereas the polysome profiles were unaffected. Moreover, we found that glutamine levels were reduced by combined deletions of EGO1, GTR1, TOR1 and PIB2 with GLN3. These results suggest that high pressure leads to the intracellular accumulation of amino acids. Subsequently, Pib2 loaded with glutamine stimulates the EGOC–TORC1 complex to inactivate Gln3, downregulating glutamine synthesis. Our findings illustrate the regulatory circuit that maintains intracellular amino acid homeostasis and suggest critical roles for the EGOC–TORC1 and Pib2–TORC1 complexes in the growth of yeast under high hydrostatic pressure.

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Przybysz, Mirosław, Marian Janusz Łopatka, Marcin Małek, and Arkadiusz Rubiec. "Influence of Flow Divider on Overall Efficiency of a Hydrostatic Drivetrain of a Skid-Steer All-Wheel Drive Multiple-Axle Vehicle." Energies 14, no. 12 (June 15, 2021): 3560. http://dx.doi.org/10.3390/en14123560.

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The efficiency of a skid-steer, all-wheel drive, multiple-axle vehicle with a hydrostatic drivetrain equipped with low-speed motors when it operates on soft terrain was studied. A flow divider enables a single pump to simultaneously power more than one motor circuit with different pressures in each. It prevents kinematic discrepancy and improves vehicle mobility. There are two types of flow divider: spool type and gear type, where each type has its own set of performance characteristics, such as flow range, pressure drop, accuracy and application parameters. In the present work, the influence of the characteristics of both types of flow divider on overall vehicle driveline efficacy is described.

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31

Manring, N. D. "The Torque on the Input Shaft of an Axial-Piston Swash-Plate Type Hydrostatic Pump." Journal of Dynamic Systems, Measurement, and Control 120, no. 1 (March 1, 1998): 57–62. http://dx.doi.org/10.1115/1.2801322.

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Traditionally, the theoretical torque on the input shaft of a hydrostatic pump has been determined using a macroscopic “power-in, power-out” approach that neglects the time-varying aspects of this quantity and the compressibility of the hydraulic fluid within the circuit. In contrast to the traditional approach, this research analyzes and sums the basic forces within the machine to compute the instantaneous torque exerted on the shaft. It is shown that the instantaneous torque repeatedly varies by 1.5 percent of its maximum value and that resonant frequencies of the pump occur at even multiples of the “piston-pass” frequency. Furthermore, an integral average of the instantaneous torque is performed and shown to deviate by a maximum of 3 percent from the traditional method of computing this quantity.

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32

Paszota, Zygmunt. "Graphical presentation of the power of energy losses and power developed in the elements of hydrostatic drive and control system.: Part II Rotational hydraulic motor speed parallel throttling control and volumetric control systems." Polish Maritime Research 15, no. 4 (January 1, 2008): 21–29. http://dx.doi.org/10.2478/v10012-007-0093-y.

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Graphical presentation of the power of energy losses and power developed in the elements of hydrostatic drive and control system.: Part II Rotational hydraulic motor speed parallel throttling control and volumetric control systems Paper presents graphical interpretation of the power of energy losses in the hydrostatic drive and control system elements and also of the power developed by those elements. An individual system fed by a constant capacity pump, where rotational hydraulic motor speed control is effected by a parallel throttling control system, is analyzed and also a system with the rotational hydraulic motor speed volumetric control by a variable capacity pump, an individual system with a rotational hydraulic motor volumetric speed control by means of a simultaneous change of the pump capacity per one revolution and change of the motor capacity per one revolution, the system operating at the constant pressure in the pump discharge conduit equal to the nominal pressure of the system: pP2 = pn and central system (with situated in parallel and simultaneously operating motors) with volumetric speed control of each rotational hydraulic motor by a motor secondary circuit assembly, the system fed by a pump with variable capacity per one shaft revolution fitted with pressure regulator pP2 = pn.

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33

Ehrén, H., B. Frenckner, and K. Palmér. "In-vitro evaluation of neonatal ECMO cannulae with regard to flow characteristics." Perfusion 5, no. 1 (January 1990): 45–51. http://dx.doi.org/10.1177/026765919000500106.

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One of the crucial points in a neonatal ECMO circuit is to obtain adequate venous drainage from the cannula in the right jugular vein, as the vessel diameter limits the size of cannula that can be used. For this reason the design of the cannula is of utmost importance. The aim of this paper was to compare different commercially available ECMO cannulae, and to try to find the cannula which had the best flow characteristics. Venous cannulae were evaluated with regard to maximum drainage capacity at different hydrostatic levels. For arterial use, pressure drop over the cannulae at different flow rates was measured. Of the cannulae studied, those from Biomedicus and Elecath had the best flow characteristics for both venous and arterial use.

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Pandey, Ajit Kumar, Alok Vardhan, and K. Dasgupta. "Theoretical and experimental studies of the steady-state performance of a primary and secondary-controlled closed-circuit hydrostatic drive." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 233, no. 5 (January 16, 2019): 1024–35. http://dx.doi.org/10.1177/0954408918821779.

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In this article, performance of a closed-circuit hydrostatic drive in primary and secondary mode of operations has been studied through theory and experiment. This drive consists of a variable displacement pump that supplies pressurized fluid to a variable displacement hydro-motor of bent axis design. Bond graph simulation method is adopted for system modeling. In the model, the losses of the drive are accounted by suitable resistive elements, and their characteristics are identified through experiments. The predicted drive’s performances are studied with respect to the overall efficiency, torque loss (%), and slip at different torque levels which are also validated experimentally. The investigation made in the article identifies the efficient zone of operation of the drive which will be useful to the practicing engineers to select such a drive used in heavy constructional equipment. From the steady-state performance of the pump and the motor, their critical control parameters are identified. The studies may be useful for the design of the suitable control strategy to obtain the optimum performance of the drives.

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Ehlers, Niels, and Dirch Ehlers. "EFFECTS OF HYDROSTATIC AND COLLOID-OSMOTIC PRESSURE ON ELECTRICAL POTENTIAL AND SHORT-CIRCUIT CURRENT ACROSS THE EXPLANTED RABBIT CORNEA." Acta Ophthalmologica 46, no. 4 (May 27, 2009): 767–78. http://dx.doi.org/10.1111/j.1755-3768.1968.tb02875.x.

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36

Islahudin, Islahudin, Fatoni Riadi, Rosdaniah Rosdaniah, and Yustina Yuyun Yustina Yuyun. "RANCANG BANGUN SENSOR TEKANAN BERBASIS KOIL DATAR UNTUK MENGUKUR TEKANAN HIDROSTATIS AIR BENDUNGAN RAWAN BANJIR DI WILAYAH LOMBOK NUSA TENGGARA BARAT." ORBITA: Jurnal Kajian, Inovasi dan Aplikasi Pendidikan Fisika 5, no. 1 (June 9, 2019): 1. http://dx.doi.org/10.31764/orbita.v5i1.893.

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Abstrak :Penelitian ini tentang rancang bangun sensor tekanan berbasis koil datar untuk mengukur tekanan hidrostatis air bendungan rawan banjir di wilayah Lombok Nusa Tenggara Barat. Adapun tujuan khusus daripenelitian ini adalah 1) membuat rangkaian pengolah sinyal dari sensor tekanan berbasis koil datar, 2) menentukan besarnya tekanan hidrostatis pada beberapa kedalaman air di bendungan rawan banjir. Jenis penelitian ini adalah eksperimen. Metode penelitian meliputi tahapan yaitu desain elemen sensor koil datar, desain kalibrasi jarak, merancang koil datar, merancang rangkaian digital dan pengiriman data. Variabel yang diukur adalah tegangan keluaran sensor getaran koil datar. Jarak logam pengganggu terhadap koil datar akan berubah setelah rumahan sensor dicelupkan ke dalam air dengan kedalaman h. Semakin besarkedalaman h maka logam pengganggu akan semakin mendekati elemen koil datar. Sensor koil datar diukur responnya terhadap perubahan jarak dari logam pengganggu, kemudian dicatat hasilnya dan dianalisismenggunakan analisis regresi linier pada Ms. Excel. Berdasarkan hasil analisis data diperoleh hasil berupa persamaan Vout dan PH yaitu Vout = 0.000PH – 60.60. Persamaan ini merupakan persamaan akhir yangmenyatakan hubungan linier antara Vout dan PH. Artinya jika kedalaman diubah-ubah secara sembarang maka setiap saat akan diketahui juga nilai tekanan hidrostatis yang ditandai dengan adanya perubahantegangan keluaran pada sensor. Abstract : This research is about the design of flat coil-based pressure sensors to measure hydrostatic pressure of flood-prone water in the Lombok region of West Nusa Tenggara. The purpose of this study is 1) to make a signal processing circuit from a flat coil based pressure sensor, 2) to determine the amount of hydrostatic pressure at some depth of water in a flood-prone dam. This type of research is an experiment. The researchmethods include stages namely the design of flat coil sensor elements, distance calibration design, flat coil design, digital circuit design and data transmission. The measured variable is the flat coil vibration sensoroutput voltage. The distance of the metal to the flat coil will change after the sensor housing is immersed in water with depth h. The greater the depth of h, the more metal will approach the flat coil element. The flat coilsensor is measured in response to changes in distance from the metal, then the results are recorded and analyzed using linear regression analysis on Ms. Excel. Based on the results of data analysis, the results arein the form of Vout and PH equations, namely Vout = 0.000PH - 60.60. This equation is the final equation which states the linear relationship between Vout and PH. This means that if the depth is changed arbitrarily, at anytime it will be known also the value of the hydrostatic pressure which is indicated by the change in the output voltage on the sensor.

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Choukroun, M. L., and P. Varene. "Adjustments in oxygen transport during head-out immersion in water at different temperatures." Journal of Applied Physiology 68, no. 4 (April 1, 1990): 1475–80. http://dx.doi.org/10.1152/jappl.1990.68.4.1475.

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Respiratory gas exchange was investigated in human subjects immersed up to the shoulders in water at different temperatures (Tw = 25, 34, and 40 degrees C). Cardiac output (Qc) and pulmonary tissue volume (Vti) were measured by a rebreathing technique with the inert gas Freon 22, and O2 consumption (VO2) was determined by the closed-circuit technique. Arterial blood gases (PaO2, PaCO2) were analyzed by a micromethod, and alveolar gas (PAO2) was analyzed during quiet breathing with a mass spectrometer. The findings were as follows. 1) Immersion in a cold bath had no significant effect on Qc compared with the value measured at Tw = 34 degrees C, whereas immersion in a hot bath led to a considerable increase in Qc. Vti was not affected by immersion at any of the temperatures tested. 2) A large rise in metabolic rate VO2 was only observed at Tw = 25 degrees C (P less than 0.001). 3) Arterial blood gases were not significantly affected by immersion, whatever the water temperature. 4) O2 transport during immersion is affected by two main factors: hydrostatic pressure and temperature. Above neutral temperature, O2 transport is improved because of the marked increase in Qc resulting from the combined actions of hydrostatic counter pressure and body heating. Below neutral temperature, O2 transport is altered; an increase in O2 extraction of the tissue is even calculated.

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38

Joswig, Luca, Michael J. Vellekoop, and Frieder Lucklum. "Miniature 3D-Printed Centrifugal Pump with Non-Contact Electromagnetic Actuation." Micromachines 10, no. 10 (September 21, 2019): 631. http://dx.doi.org/10.3390/mi10100631.

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We present a miniature 3D-printed dynamic pump using the centrifugal operating principle. Dynamic pumps typically yield higher flow rates than displacement pumps at reasonable output pressure. Realizing smaller devices suitable for millifluidic and microfluidic applications brings challenges in terms of design, fabrication and actuation. By using microstereolithography printing we have reduced the overall size to an effective pumping volume of 2.58 mL. The free-moving rotor consists of an impeller and permanent magnets embedded during the printing process, which allow for non-contact electromagnetic actuation. The pump is driven by periodically switching the current through stator coils, controlled by a custom built circuit using a Hall effect sensor. It achieves a maximum flow rate of 124 mL/min and a hydrostatic pressure of up to 2400 Pa.

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Casoli, Paolo, Fabio Scolari, Tatiana Minav, and Massimo Rundo. "Comparative Energy Analysis of a Load Sensing System and a Zonal Hydraulics for a 9-Tonne Excavator." Actuators 9, no. 2 (May 20, 2020): 39. http://dx.doi.org/10.3390/act9020039.

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With the rising demand for energy efficiency, displacement-controlled or so-called pump-controlled systems have become an attractive research topic for applications in construction machinery and other off-road vehicles. Pump-controlled systems can be implemented with electro-hydrostatic actuators as electro-hydraulic zones, which are located next to the end actuator as a replacement for the traditional valve-controlled hydraulic actuation systems. In this paper a 9-tonne class excavator is utilized as a study case. A mathematical model of the conventional machine, validated with tests carried out on both the excavator and the single hydraulic components, was previously developed within the Simcenter AMESim© environment. This mathematical model was modified with electric components for simulating a zonal hydraulics excavator and compared with a conventional load sensing (LS) machine. The energy efficiencies of both the LS circuit and the new solution were evaluated for typical duty cycles, pointing out the obtainable energy efficiency improvements, which were mainly due to the absence of the directional valves and pressure compensators. The results also point out the effect of the pipe losses when the circuit layout requires the pipe for connecting the pump with the actuator; moreover, the effect of a diesel engine downsizing on the energy saving was evaluated.

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40

Kleinekofort, W. "Improved Measurement of Vascular Access Pressure." Journal of Vascular Access 3, no. 2 (April 2002): 58–63. http://dx.doi.org/10.1177/112972980200300203.

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Vascular access stenosis and thrombosis is one of the key problems for hemodialysis patients. Prospective monitoring of static venous dialysis pressures can be applied to detect outflow stenoses in a vascular access. However, the location of stenoses within the access may influence the diagnostic value of venous pressure measurements. Whereas a decrease in access flow occurs with all types of stenosis, strictures within the arterial anastomosis or between arterial and venous dialysis needle cannot be detected with venous pressure measurements alone. A new approach is discussed, which bases on the improved measurement of static venous and arterial extracorporeal pressures. Extracorporeal pressure at zero blood flow depends on both the position of the heart relative to the extracorporeal blood circuit and the vertical offset between access site and fluid level in the bloodline. After hydrostatic correction of each pressure signal the normalized arterial and venous intra-access pressure ratio AP/MAP can be calculated. A venous stenosis leads to an increase in both arterial and venous pressure ratio. In case of access stenosis between arterial and venous needle the ratio of venous pressure to mean arterial pressure is normal, and only the arterial pressure ratio is elevated. In summary, a combination of arterial and venous pressure measurement is more sensitive and allows differentiation between mid-access and venous stenosis. Hydrostatic correction of the dialysis pressure signal is inevitable. To minimize the rate of access thrombosis, venous and arterial intra-access pressure should be considered when evaluating dialysis pressures as part of any access monitoring program.

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JIANG, DONGDONG, YUJUN FENG, JINMEI DU, and YAN GU. "EFFECTS OF SHOCK PRESSURE AND SELF-GENERATED ELECTRIC FIELD ON SHOCK-INDUCED FERROELECTRIC TO ANTIFERROELECTRIC PHASE TRANSITION IN LEAD ZIRCONATE STANNATE TITANATE FERROELECTRIC CERAMICS." Journal of Advanced Dielectrics 02, no. 04 (October 2012): 1250026. http://dx.doi.org/10.1142/s2010135x12500269.

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Kinetics of the ferroelectric (FE) to antiferroelectric (AFE) phase transformation under shock wave compression is critical to design the shock-activated power supply and can be characterized in terms of both a transition rate and a limiting degree of transition. By measuring the depoling currents under the short-circuit and high-impedance conditions, we investigated the influence of shock pressure and self-generated electric field on the phase transition kinetics of tin-modified lead zirconate titanate ceramics (Pb0.99Nb0.02[(Zr0.90Sn0.10)0.96Ti0.04]0.98O3) in the pressure range from 0.23 to 4.50 GPa. Experimental results indicate that the shock pressure promotes the FE-to-AFE phase transition. And the self-generated electric field does not appear to have a significant effect on the depoling currents at high shock pressures, but has a strong effect at low pressures. At 0.61 GPa and 1.03 GPa, transition rate and degree diminish with increasing the electric field, illustrating that the self-generated electric field suppresses the FE-to-AFE phase transition. These observations are found to be generally consistent with results under the hydrostatic compression. Fundamental issues are discussed from the perspective of the soft mode theory.

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Hancock, B. J., K. P. Landolfo, M. Hoppensack, and L. Oppenheimer. "Slow phase of transvascular fluid flux reviewed." Journal of Applied Physiology 69, no. 2 (August 1, 1990): 456–64. http://dx.doi.org/10.1152/jappl.1990.69.2.456.

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In six circuit experiments using a clinical hemofiltration device, we validated a colorimetric technique to measure transvascular volume exchange (VE). In 12 isolated excised canine left lower lobes, continuous colorimetric measurements of VE correlated well with calculations of VE from changes in microhematocrit obtained simultaneously. We introduced step increases in microvascular hydrostatic pressure (Pc) of 9 +/- 4.8 (SD) cmH2O and followed the time course of weight and continuous hematocrit changes measured colorimetrically for 40 min, after which Pc was returned to base line, while measurements were continuously obtained. This procedure was repeated for an additional 30 min. VE was calculated from the hematocrit signals and compared with the time course of the weight signal. After increases in Pc, followed by a rapid weight gain, weight signals followed a slow exponential time course, whereas the calculated VE changed linearly. VE reflected approximately 60% of the slow weight gain. When Pc was decreased, weight signals decreased exponentially, whereas VE continued to increase linearly at a slower rate. These results suggest that a significant component of the slow weight signal represents slow vascular volume changes. Contrary to what the weight signal suggested, edema was never reabsorbed over the range of Pc measured.

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Parker, James C., John R. Pelton, and Martin E. Dougherty. "A versatile shotgun source for engineering and groundwater seismic surveys." GEOPHYSICS 58, no. 10 (October 1993): 1511–16. http://dx.doi.org/10.1190/1.1443366.

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We describe an electrical seismic gun that is capable of firing 8-gauge blank black powder shells in a water‐filled borehole under relatively high hydrostatic pressures. The new seismic gun is a modified version of the electrical shotgun source for engineering seismic surveys introduced by Pullan and MacAulay (1987). Our modifications seal the firing circuit and 8-gauge shell against water entry so underwater detonation will occur reliably at depths to at least 80 m (0.9 MPa atmospheric pressure). Source energy is controlled by varying the size of the black powder load in the shell from 50 grains to 500 grains (10 kJ to 100 kJ). Although our seismic gun may be used in any seismic application suitable for modest explosive charges, it was initially developed as a versatile source for use in seismic investigations of the shallow subsurface (primarily engineering and groundwater studies). As of this writing, the gun has been used for optimum offset and CMP high‐resolution seismic reflection profiling, engineering refraction surveys, fixed‐source and variable‐source noise tests, and vertical traveltime measurements in water wells. Other potential uses include VSP and borehole‐to‐surface or borehole‐to‐borehole seismic tomography.

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Máchal, Pavel, Zdenko Tkáč, Ján Kosiba, Juraj Jablonický, Ľubomír Hujo, Marián Kučera, and Juraj Tulik. "Design of a laboratory hydraulic device for testing of hydraulic pumps." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 61, no. 5 (2013): 1313–19. http://dx.doi.org/10.11118/actaun201361051313.

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The present contribution deals with solves problem of research of testing device to monitor of hydrostatic pumps durability about dynamic loading under laboratory conditions. When carrying out the design of testing device are based on load characteristics of tractor hydraulic circuit, the individual characteristics of hydraulic components and performed calculations. Load characteristics on the tractors CASE IH Magnum 310, JOHN DEERE 8100, ZETOR FORTERRA 114 41 and Fendt 926 Vario were measured. Design of a hydraulic laboratory device is based on the need for testing new types of hydraulic pumps or various types of hydraulic fluids. When creating of hydraulic device we focused on testing hydraulic pumps used in agricultural and forestry tractors. Proportional pressure control valve is an active member of the hydraulic device, which provides change of a continuous control signal into relative pressure of operating fluid. The advantage of a designed hydraulic system is possibility of simulation of dynamic operating loading, which is obtained by measurement under real conditions, and thereby creates laboratory conditions as close to real conditions as possible. The laboratory device is constructed at the Department of Transport and Handling, Faculty of Engineering, Slovak University of Agriculture in Nitra.

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Barak, J., S. Einav, A. Tadmor, B. Vidne, and W. G. Austen. "The Effect of Colloid Osmotic Pressure on the Survival of Sheep following Cardiac Surgery." International Journal of Artificial Organs 12, no. 1 (January 1989): 47–50. http://dx.doi.org/10.1177/039139888901200108.

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The occurrence of late complications in implanted cardiac prosthetic valves has emphasized the need for the development of an animal model in which these complications are reproducible. Sheep constitute an excellent model for chronical and pathological studies of prosthetic devices. In our experience, survival of sheep following implantation of prosthetic valves is closely related to postoperative serum colloid osmotic pressure (C.O.P.). The normal range as measured in 28 healthy sheep was 16.67 ± 0.55 mm Hg. A protocol was developed to maintain the colloid hydrostatic pressure gradient (C.H.P.G.) as close as possible to the normal physiological range, and to delay the extubation until the C.O.P. was within this range, and the C.H.P.G. > 7mm Hg. Using the above protocol, a new tri-leaflet Polyurethane valve was inserted into eight, five to seven month old sheep in place of the mitral and tricuspidal valves. One hour after terminating the extacorporeal circuit, the C.O.P. was measured at 13.10 ± 0.96; but within five to six hours, it rose to 17.1 ± 1.1. During the same period, the C.H.P.G. increased from 3.02 ± 0.96 to 7.6 ± 0.50 mm Hg. The postoperative period was uneventful, and all animals survived. We have thus concluded that the routine measurement and monitoring of C.O.P. constitutes a guide of great clinical importance.

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Monastyrskyi, Vitalii, Serhii Monastyrskyi, and Borys Mostovyi. "Effect of water medium upon the process of ore disintegration in wet self-grinding mills." E3S Web of Conferences 109 (2019): 00058. http://dx.doi.org/10.1051/e3sconf/201910900058.

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This article presents the results of theoretical and experimental studies on the processes of destruction ore in wet self-grinding mills under the influence of the aquatic environment on it. The equivalent circuit for determining the stress-strain state of a large piece (ball) exposed to the load at an angle of repose of the material in motion are justified. A uniformly distributed pressure acts on the body of arbitrary shape, depending on the hydrostatic pressure of the pulp inside the drum and the force of hydrodynamic resistance). It is assumed that a large piece has the shape of a sphere with a uniform structure, but in some of its parts there are cavities filled with an incompressible fluid. Under the action of these forces inside the cavity wedging effects of water occur, the effect of which on the strength ores depends on the expansion force and the angle of the micro crack. The experimental researches are done under laboratory and industrial conditions. It was established that the disintegration of kimberlitic ore in MMC is significantly influenced by the characteristics of the aquatic environment pH and Eh, the values of which vary from 3.2 to 7.0 and from -500 to +1020 mV.

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Li, M., S. K. Hong, J. M. Goldinger, and M. E. Duffey. "Interaction of heptanol and pressure on sodium and chloride transport by toad skin." Journal of Applied Physiology 69, no. 5 (November 1, 1990): 1883–92. http://dx.doi.org/10.1152/jappl.1990.69.5.1883.

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We examined the interaction of heptanol and hydrostatic pressure on Na+ and Cl- transport in isolated toad skin. In the presence of Cl-, heptanol decreased short-circuit current (Isc) and total transepithelial resistance (Rt). However, in the absence of Cl- in the mucosal bath, heptanol increased Rt, although it retained the same inhibitory effect on Isc. When transepithelial active Na+ transport was blocked by amiloride, heptanol had no effect on Isc whether or not Cl- was present, whereas it decreased the shunt resistance (Rs) only in the presence of Cl- in the mucosal bath. Moreover, this effect of heptanol on Rs was significantly smaller in the presence of diphenylamine-2-carboxylate (DPC), a known Cl- channel blocker. Pressure also decreased Isc through inhibition of active Na+ transport, but it increased Rs. When heptanol and pressure were applied together, their inhibitory effects on Isc were additive, but their effects on Rs were antagonistic. Furthermore, when a transepithelial Cl- current was produced by reducing the Cl- concentration of the serosal bath, heptanol stimulated this current, which was reversibly inhibited by pressure or DPC addition to the mucosal bath. When the heptanol-stimulated Cl- current was first inhibited by pressure, subsequent DPC addition had less or no effect. These results suggest that one site of an antagonistic interaction of heptanol and pressure in toad skin is an apical membrane Cl- conductance.

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Gawenis, Lara R., Kathryn T. Boyle, Bradley A. Palmer, Nancy M. Walker, and Lane L. Clarke. "Lateral intercellular space volume as a determinant of CFTR-mediated anion secretion across small intestinal mucosa." American Journal of Physiology-Gastrointestinal and Liver Physiology 286, no. 6 (June 2004): G1015—G1023. http://dx.doi.org/10.1152/ajpgi.00468.2003.

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Studies of full-thickness, small intestinal preparations have shown that maximal anion secretion [indexed by short-circuit current ( Isc)] during intracellular cAMP (cAMPi) stimulation is transient and followed by a decline toward baseline. Declining Isc is preceded by decreases in transepithelial conductance (Gt), which in the small intestine reflects the lateral intercellular space (LIS) volume of the paracellular pathway. We hypothesized that decreases in LIS volume limit the magnitude and duration of cAMPi-stimulated anion secretion. Experimental manipulations to increase the patency of the LIS (assessed by Gt and electron microscopy) were investigated for an effect on the magnitude of cAMPi-stimulated anion secretion (assessed by the Isc and isotopic fluxes) across murine small intestine. In control studies, changes of Gt after cAMPi stimulation were associated with a morphological “collapse” of the LIS, which did not occur in intestine of CFTR-null mice. Removal of the outer intestinal musculature, exposure to a serosal hypertonic solution, or increased serosal hydrostatic pressure minimized reductions in Gt and increased the cAMPi-stimulated Isc response. Increased Isc primarily resulted from increased Cl− secretion that was largely bumetanide sensitive. However, bumetanide-insensitive Isc was also increased, and similar increases occurred in the Na+-K+-2Cl− cotransporter (NKCC1)-null intestine, indicating that activities of non-NKCC1 anion uptake proteins are also affected by LIS volume. Thus LIS patency is an important determinant of the magnitude and duration of CFTR-mediated anion secretion in murine small intestine. Decreases in LIS volume may limit the pool of available anions to basolateral transporters involved in transepithelial secretion.

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Marinaro, Gianluca, Zhuangying Xu, Zhengpu Chen, Chenxi Li, Yizhou Mao, and Andrea Vacca. "The PurdueTracer: An Energy-Efficient Human-Powered Hydraulic Bicycle with Flexible Operation and Software Aids." Energies 11, no. 2 (January 31, 2018): 305. http://dx.doi.org/10.3390/en11020305.

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Hydrostatic transmissions (HT) are widely applied to heavy-duty mobile applications because of the advantages of layout flexibility, power to weight ratio, and ease of control. Though applications of fluid power in light-duty vehicles face challenges, including the unavailability of off-the-shelf components suitable to the power scale, there are potential advantages for HTs in human-powered vehicles, such as bicycles, the most important one being the energy-saving advantage achievable through regenerative braking in a hybrid HT. This paper describes an innovative design for a hydraulic hybrid bicycle, i.e., the PurdueTracer. The PurdueTracer is an energy-efficient human-powered hydraulic bicycle with flexible operation and software aids. An open-circuit hydraulic hybrid transmission allows PurdueTracer to operate in four modes: Pedaling, Charging, Boost, and Regeneration, to satisfy users’ need for different riding occasions. An aluminum chassis that also functions as a system reservoir was customized for the PurdueTracer to optimize the durability, riding comfort, and space for components. The selection of the hydraulic components was performed by creating a model of the bicycle in AMESim simulation software and conducting a numerical optimization based on the model. The electronic system equipped users with informative feedback showing the bicycle performance, intuitive execution of functions, and comprehensive guidance for operation. This paper describes the design approach and the main results of the PurdueTracer, which also won the 2017 National Fluid Power Association Fluid Power Vehicle Challenge. This championship serves to prove the excellence of this vehicle in terms of effectiveness, efficiency, durability, and novelty.

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Valentina Lungu, Magdalena. "Tungsten-Copper Composites for Arcing Contact Applications." Material Science Research India 17, no. 3 (July 22, 2020): 214–29. http://dx.doi.org/10.13005/msri/170304.

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The study presents the research findings on electrical contact materials based on tungsten-copper (W-Cu) composites containing 72 ± 3 wt.% W, rest Cu, and up to 1.5 wt.% Ni. Cylindrical sintered parts with 57 ± 0.5 mm in diameter and 12 ± 0.5 mm in height were manufactured by pressing, sintering, and liquid infiltration route, then were mechanically polished and processed as complex shape protection rings used as arcing contacts in high voltage circuit breakers (HVCBs). The surface elemental composition of the sintered parts was determined by wavelength dispersive X-ray fluorescence spectrometry. The density was determined by hydrostatic weighing in ethanol. The arithmetic mean surface roughness was measured by contact profilometry. The microstructure was studied by scanning electron microscopy. The electrical conductivity was measured by eddy current method. The thermal diffusivity and specific heat were determined by laser flash analysis. Instrumented indentation testing and two computational methods (Oliver & Pharr, and Martens hardness) were employed to study the mechanical properties under quadratic loading and continuous multi cycle (CMC) indentation mode. The functional behavior of the arcing contacts was assessed in terms of static and dynamic contact resistance in operation in minimum oil HVCBs of 110 kV. The properties investigation revealed highly dense contact parts with homogeneous microstructure, Vickers hardness of 260-374, elastic modulus of 185-311 GPa, as well as good electrical and thermal conductivity. The arcing contacts proved a good functional behavior. in service, too. The results endorse the developed sintered contact materials for implementation in practical applications.

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Journal articles on the topic 'Hydrostatic circuit'

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