Journal articles: 'Intermediate pressure'

1

Bertioli, Michael. "Intermediate Range Pressure Measurement." Measurement and Control 20, no. 8 (October 1987): 33–36. http://dx.doi.org/10.1177/002029408702000806.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Zhao, Y. C., F. Porsch, and W. B. Holzapfel. "Intermediate 4fbonding structure for samarium under pressure." Physical Review B 50, no. 10 (September 1, 1994): 6603–8. http://dx.doi.org/10.1103/physrevb.50.6603.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Martínez-Boza, F. J., M. J. Martín-Alfonso, C. Gallegos, and M. Fernández. "High-Pressure Behavior of Intermediate Fuel Oils." Energy & Fuels 25, no. 11 (November 17, 2011): 5138–44. http://dx.doi.org/10.1021/ef200958v.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Christensen, N. E., D. L. Novikov, and M. Methfessel. "The intermediate high-pressure phase of silicon." Solid State Communications 110, no. 11 (May 1999): 615–19. http://dx.doi.org/10.1016/s0038-1098(99)00120-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Gao, Jie, Xuezheng Liu, Xudong Zhao, Weiliang Fu, Guoqiang Yue, and Qun Zheng. "Steady and unsteady numerical investigation of flow interaction between low-pressure turbine blade, intermediate turbine duct and power turbine vane." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 23 (January 10, 2018): 4312–31. http://dx.doi.org/10.1177/0954406217751819.

Full text

Abstract:

Flows in an intermediate turbine duct connecting low-pressure turbines and power turbines are very complex, affected by the upstream low-pressure turbine flow structures. Non-uniformities originating from the duct with struts also affect the power turbine inflow conditions, resulting in reduced efficiency. The present investigation is done to clarify the flow and loss mechanisms within the intermediate turbine duct and the power turbine. Steady and unsteady numerical investigations of the flow interaction between low-pressure turbine blade, intermediate turbine duct and power turbine vane were conducted. Effects of upstream low-pressure turbine blade on intermediate turbine duct flow fields and loss characteristics, and that of intermediate turbine duct with big and small struts on power turbine aerodynamics are explored. The generation and propagation of wake and secondary flows through the whole configuration are described. The fast Fourier transformation analyses of the flow in the low-pressure turbine blade, intermediate turbine duct and power turbine vane are also presented. Results from the steady and unsteady investigations show complex flow patterns resulted from blade–strut–vane flow interactions, which are not obtainable from intermediate turbine duct-only or power turbine-only simulations. The intermediate turbine duct has a great amplifying influence on the distorted inflow, and the inlet flow with upstream wakes and secondary flows introduces a high-loss area along the casing at intermediate turbine duct exit. Detailed results are presented and discussed for the flow physics and loss mechanisms as well as the unsteady flow evolution through the low-pressure turbine blade, intermediate turbine duct and power turbine vane.

APA, Harvard, Vancouver, ISO, and other styles

6

Panfilov, A. S., A. A. Lyogenkaya, and G. E. Grechnev. "Magnetic properties of YbB12. Pressure effects." Low Temperature Physics 50, no. 7 (July 1, 2024): 523–26. http://dx.doi.org/10.1063/10.0026247.

Full text

Abstract:

For one of the famous and widely investigated intermediate valence compound YbB12, the experimental studies of the pressure effect on magnetic susceptibility χ(P) were carried out under helium gas pressure P up to 2 kbar at fixed temperatures 78 and 300 K using a pendulum type magnetometer. The measurements show a slight increase in susceptibility under pressure, which is consistent in sign with similar literature data for other ytterbium compounds with intermediate valence of Yb ions. Based on a model analysis of experimental data, the pressure derivative of Yb valence in YbB12 was estimated for the first time, the value of which is in line with the general trend of the valence behavior under pressure in rare earth compounds exhibiting intermediate valence.

APA, Harvard, Vancouver, ISO, and other styles

7

Hakala, Jani P., and Neil M. Donahue. "Pressure-Dependent Criegee Intermediate Stabilization from Alkene Ozonolysis." Journal of Physical Chemistry A 120, no. 14 (April 4, 2016): 2173–78. http://dx.doi.org/10.1021/acs.jpca.6b01538.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Song, Yu, Hamid Hashemi, Jakob Munkholt Christensen, Chun Zou, Paul Marshall, and Peter Glarborg. "Ammonia oxidation at high pressure and intermediate temperatures." Fuel 181 (October 2016): 358–65. http://dx.doi.org/10.1016/j.fuel.2016.04.100.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Thomas, S. M., F. B. Santos, M. H. Christensen, T. Asaba, F. Ronning, J. D. Thompson, E. D. Bauer, R. M. Fernandes, G. Fabbris, and P. F. S. Rosa. "Evidence for a pressure-induced antiferromagnetic quantum critical point in intermediate-valence UTe2." Science Advances 6, no. 42 (October 2020): eabc8709. http://dx.doi.org/10.1126/sciadv.abc8709.

Full text

Abstract:

UTe2 is a recently discovered unconventional superconductor that has attracted much interest because of its potentially spin-triplet topological superconductivity. Our ac calorimetry, electrical resistivity, and x-ray absorption study of UTe2 under applied pressure reveals key insights on the superconducting and magnetic states surrounding pressure-induced quantum criticality at Pc1 = 1.3 GPa. First, our specific heat data at low pressures, combined with a phenomenological model, show that pressure alters the balance between two closely competing superconducting orders. Second, near 1.5 GPa, we detect two bulk transitions that trigger changes in the resistivity, which are consistent with antiferromagnetic order, rather than ferromagnetism. Third, the emergence of magnetism is accompanied by an increase in valence toward a U4+ (5f2) state, which indicates that UTe2 exhibits intermediate valence at ambient pressure. Our results suggest that antiferromagnetic fluctuations may play a more substantial role on the superconducting state of UTe2 than previously thought.

APA, Harvard, Vancouver, ISO, and other styles

10

Xu, Qingzong, Pei Wang, Qiang Du, Jun Liu, and Guang Liu. "Effects of axial length and integrated design on the aggressive intermediate turbine duct." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 233, no. 4 (September 4, 2018): 443–56. http://dx.doi.org/10.1177/0957650918797450.

Full text

Abstract:

With the increasing demand of high bypass ratio and thrust-to-weight ratio in civil aero-engine, the intermediate turbine duct between the high pressure and low pressure turbines of a modern gas turbine tends to shorter axial length, larger outlet-to-inlet area ratio and high pressure-to-low pressure radial offset. This paper experimentally and numerically investigated the three-dimensional flow characteristics of traditional (ITD1) and aggressive intermediate turbine duct (ITD2) at low Reynolds number. The baseline case of ITD1 is representative of a traditional intermediate turbine duct of aero-engine design with non-dimensional length of L/dR = 2.79 and middle angle of 20.12°. The detailed flow fields inside ITD1 and flow visualization were measured. Results showed the migration of boundary layer and a pair of counter-rotating vortexes were formed due to the radial migration of low momentum fluid. With the decreasing axial length of intermediate turbine duct, the radial and streamwise reverse pressure gradient in aggressive intermediate turbine duct (ITD2) were increased resulting in severe three-dimensional separation of boundary layer near casing surface and higher total pressure loss. The secondary flow and separation of boundary layer near the endwall were deeply analyzed to figure out the main source of high total pressure loss in the aggressive intermediate turbine duct (ITD2). Based on that, employing wide-chord guide vane to substitute “strut + guide vane”, this paper designed the super-aggressive intermediate turbine duct and realized the suppression of the three-dimensional separation and secondary flow.

APA, Harvard, Vancouver, ISO, and other styles

11

Kitahara, R., and K. Akasaka. "Close identity of a pressure-stabilized intermediate with a kinetic intermediate in protein folding." Proceedings of the National Academy of Sciences 100, no. 6 (March 10, 2003): 3167–72. http://dx.doi.org/10.1073/pnas.0630309100.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Qiong, Shen. "Elastoplastic Analysis of Surrounding Rocks of the Pressure Tunnel." Applied Mechanics and Materials 353-356 (August 2013): 1644–47. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.1644.

Full text

Abstract:

According to the triple shear unified yield criterion, the mechanical behavior of the pressure tunnel was put forward. The calculation formulas of the radius of plastic zone were deduced with considerations of the effects of the intermediate principal stress. The results show that the intermediate principal stress effect parameter b has influences on the radius of plastic zone. With the increase of the intermediate principal stress effect parameter b, the radius of plastic zone decreases. The radius of plastic zone is increased, because of the increase of the porous hydraulic pressure.

APA, Harvard, Vancouver, ISO, and other styles

13

Huang, Hao-Li, Wen Chao, and Jim Jr-Min Lin. "Kinetics of a Criegee intermediate that would survive high humidity and may oxidize atmospheric SO2." Proceedings of the National Academy of Sciences 112, no. 35 (August 17, 2015): 10857–62. http://dx.doi.org/10.1073/pnas.1513149112.

Full text

Abstract:

Criegee intermediates are thought to play a role in atmospheric chemistry, in particular, the oxidation of SO2, which produces SO3 and subsequently H2SO4, an important constituent of aerosols and acid rain. However, the impact of such oxidation reactions is affected by the reactions of Criegee intermediates with water vapor, because of high water concentrations in the troposphere. In this work, the kinetics of the reactions of dimethyl substituted Criegee intermediate (CH3)2COO with water vapor and with SO2 were directly measured via UV absorption of (CH3)2COO under near-atmospheric conditions. The results indicate that (i) the water reaction with (CH3)2COO is not fast enough (kH2O < 1.5 × 10−16 cm3s−1) to consume atmospheric (CH3)2COO significantly and (ii) (CH3)2COO reacts with SO2 at a near–gas-kinetic-limit rate (kSO2 = 1.3 × 10−10 cm3s−1). These observations imply a significant fraction of atmospheric (CH3)2COO may survive under humid conditions and react with SO2, very different from the case of the simplest Criegee intermediate CH2OO, in which the reaction with water dimer predominates in the CH2OO decay under typical tropospheric conditions. In addition, a significant pressure dependence was observed for the reaction of (CH3)2COO with SO2, suggesting the use of low pressure rate may underestimate the impact of this reaction. This work demonstrates that the reactivity of a Criegee intermediate toward water vapor strongly depends on its structure, which will influence the main decay pathways and steady-state concentrations for various Criegee intermediates in the atmosphere.

APA, Harvard, Vancouver, ISO, and other styles

14

Butori, Martina, Björn Eriksson, Carina Lagergren, Göran Lindbergh, and Rakel Lindstrom. "Evaluation of Hydrogen Crossover in Pemfcs at Intermediate Temperature (80 - 120 °C)." ECS Meeting Abstracts MA2023-02, no. 39 (December 22, 2023): 1909. http://dx.doi.org/10.1149/ma2023-02391909mtgabs.

Full text

Abstract:

Proton Exchange Membrane Fuel Cells (PEMFCs) are promising for heavy-duty vehicles (HDV) in the strive to make the transportation sector more sustainable. However, because of the small temperature gradient between the cell (typically run around 80°C) and the ambient temperature, these cells require a large cooling system. Raising the operating temperature to an intermediate temperature range (IT: 80 – 120 °C) would reduce the cooling system size required in HDVs and improve the tolerance towards contaminants, although higher temperature may accelerate degradation [1,2]. To be able to withstand IT operation, reinforcements and chemical modifications have been implemented in commercial PFSA polymers. Unfortunately, most of the data available for PEMFCs are referred to non-reinforced membranes and only few studies analysed the latter under realistic operating conditions. Among some possible issues regarding proton exchange membranes (PEMs), hydrogen crossover is an undesirable, but inevitable phenomenon. The membrane is not perfectly impermeable to hydrogen gas and this results in a safety concern, lower cell efficiency and can lead to faster cell degradation. This work investigates the influence of the reinforcement in a PEM on the hydrogen crossover. Specifically, Nafion HP (reinforced) and Nafion 211 (non-reinforced) are compared under different operating conditions. The purpose of the reinforcement is to improve thermo-mechanical stability, and its physical properties can differ from the rest of the membrane, which can influence hydrogen crossover. Using electrochemical methods, the hydrogen crossover is measured in-situ in a PEMFC with hydrogen on one side and inert gas on the other side. The measurements have been performed between 80 and 120 °C, at different cell relative humidity (RH) conditions (20-90 %) and multiple levels of pressure for both reinforced and non-reinforced membranes. Particular attention has been paid to the case in which the hydrogen side of the cell is more pressurized than the inert side, as this is most often the case in HDV applications. In such conditions, hydrogen permeation increases considerably as a result of the total pressure gradient over the membrane, although this factor is rarely considered in the literature [3]. By adapting the methodology established in our previous work [4], here the effects of the differential total pressure and hydrogen partial pressures are decoupled through a systematic dilution of the hydrogen gas stream. Special points are measured in which the hydrogen partial pressure is kept equal to the ambient case, while the total pressure on the hydrogen side is increased by adding the inert gas, as shown in Figure 1, plot I. Results show that the presence of a reinforcement affects the amount of hydrogen that crosses through the membrane, as seen in Figure 1. Moreover, among the different conditions tested, higher total pressures, especially on the hydrogen side of the cell, are affecting hydrogen crossover the most, while a more modest change is observed for different RH and cell temperatures. The observation that pressure is the most important factor for hydrogen crossover has noteworthy implications and should have an influence when deciding at which pressure the PEMFC is operated in transportation applications. Minimizing hydrogen crossover, while still ensuring adequate cell performance, should be a priority to improve the overall fuel consumption and the electric power obtained from the fuel cell. Figure 1: Hydrogen crossover due to concentration gradients and, in certain conditions, to a differential total pressure. Three different conditions are used to measure crossover, whose results are reported in the right figure: I) the total pressure on the hydrogen side is increased by diluting with inert gas, while the hydrogen partial pressure is kept constant, the inert side is unvaried; II) the total pressure is increased symmetrically on both sides, the hydrogen side is not diluted; III) the total pressure on the hydrogen side is increased and no dilution is employed. [1] Cullen et al., “New roads and challenges for fuel cells in heavy-duty transportation,” Nat. Energy, 2021, doi:10.1038/s41560-021-00775-z. [2] Akitomo et al., “Investigation of effects of high temperature and pressure on a polymer electrolyte fuel cell with polarization analysis and X-ray imaging of liquid water,” J. Power Sources, 2019, doi:10.1016/j.jpowsour.2019.04.115. [3] Kreitmeier et al., “Investigation of membrane degradation in polymer electrolyte fuel cells using local gas permeation analysis,” J. Power Sources, 2012, doi:10.1016/j.jpowsour.2012.03.071. [4] Butori et al., “The Effect of Oxygen Partial Pressure and Humidification in Proton Exchange Membrane Fuel Cells at Intermediate Temperature,” J. Power Sources, 2023, doi:10.1016/j.jpowsour.2023.232803. Figure 1

APA, Harvard, Vancouver, ISO, and other styles

15

Grzesik, Zbigniew, Anna Kaczmarska, and Stanisław Mrowec. "Nonstoichiometry and Chemical Diffusion in Co₃O₄ Cobalt Oxide." Solid State Phenomena 227 (January 2015): 421–24. http://dx.doi.org/10.4028/www.scientific.net/ssp.227.421.

Full text

Abstract:

Nonstoichiometry and chemical diffusion in Co3O4oxide have been studied as a function of temperature (973-1173 K) and oxygen pressure (30-105Pa), using thermogravimetric techniques. It has been found that at very low oxygen pressures, close to the dissociation pressure of the oxide, interstitial cations and quasi-free electrons are the predominant point defects, while at high pressures cation vacancies and electron holes predominate. This behaviour is reflected in complex dependence of the deviation from stoichiometry, y, in the Co3±yO4oxide on oxygen pressure. At low pressures, namely, deviation from stoichiometry decreases with increasing oxygen pressure, reaching virtually constant value in intermediate pressures and increases at highest pressure range. Finally, these data as well as the results of kinetic rate measurements of Co3±yO4formation have been utilized in calculating the chemical diffusion coefficient as a function of temperature.

APA, Harvard, Vancouver, ISO, and other styles

16

Xin, Yi, Maurizio Cereda, Stephen Kadlecek, Kiarash Emami, Hooman Hamedani, Ian Duncan, Jennia Rajaei, et al. "Hyperpolarized gas diffusion MRI of biphasic lung inflation in short- and long-term emphysema models." American Journal of Physiology-Lung Cellular and Molecular Physiology 313, no. 2 (August 1, 2017): L305—L312. http://dx.doi.org/10.1152/ajplung.00048.2017.

Full text

Abstract:

During lung inflation, airspace dimensions are affected nonlinearly by both alveolar expansion and recruitment, potentially confounding the identification of emphysematous lung by hyperpolarized helium-3 diffusion magnetic resonance imaging (HP MRI). This study aimed to characterize lung inflation over a broad range of inflation volume and pressure values in two different models of emphysema, as well as in normal lungs. Elastase-treated rats ( n = 7) and healthy controls ( n = 7) were imaged with HP MRI. Gradual inflation was achieved by incremental changes to both inflation volume and airway pressure. The apparent diffusion coefficient (ADC) was measured at each level of inflation and fitted to the corresponding airway pressures as the second-order response equation, with minimizing residue (χ2 < 0.001). A biphasic ADC response was detected, with an initial ADC increase followed by a decrease at airway pressures >18 cmH2O. Discrimination between treated and control rats was optimal when airway pressure was intermediate (between 10 and 11 cmH2O). Similar findings were confirmed in mice following long-term exposure to cigarette smoke, where optimal discrimination between treated and healthy mice occurred at a similar airway pressure as in the rats. We subsequently explored the evolution of ADC measured at the intermediate inflation level in mice after prolonged smoke exposure and found a significant increase ( P < 0.01) in ADC over time. Our results demonstrate that measuring ADC at intermediate inflation enhances the distinction between healthy and diseased lungs, thereby establishing a model that may improve the diagnostic accuracy of future HP gas diffusion studies.

APA, Harvard, Vancouver, ISO, and other styles

17

Mei, Guoxiong, Qiming Chen, and Linhui Song. "Model for predicting displacement-dependent lateral earth pressure." Canadian Geotechnical Journal 46, no. 8 (August 2009): 969–75. http://dx.doi.org/10.1139/t09-040.

Full text

Abstract:

A model for predicting displacement-dependent lateral earth pressure was proposed based on an earth pressure – displacement relationship commonly observed in practice. The proposed model is a monotonically increasing and bounded function, with an inflection point at the displacement of s = 0 at which the earth pressure changes from the intermediate active state (the state between active and at-rest) to the intermediate passive state (the state between at-rest and passive). The proposed model can predict the relationship between earth pressure and retaining structure movement for any condition intermediate to the active and passive states, which was verified by the experimental data reported in published literature. The predicted lateral earth pressure coefficients are in good agreement with the test results of model tests reported in the literature.

APA, Harvard, Vancouver, ISO, and other styles

18

Sharma, Manish, and Beena D. Baloni. "Review on the aerodynamics of intermediate compressor duct." Journal of Mechanical Engineering and Sciences 14, no. 4 (December 18, 2020): 7446–68. http://dx.doi.org/10.15282/jmes.14.4.2020.13.0587.

Full text

Abstract:

In a turbofan engine, the air is brought from the low to the high-pressure compressor through an intermediate compressor duct. Weight and design space limitations impel to its design as an S-shaped. Despite it, the intermediate duct has to guide the flow carefully to the high-pressure compressor without disturbances and flow separations hence, flow analysis within the duct has been attractive to the researchers ever since its inception. Consequently, a number of researchers and experimentalists from the aerospace industry could not keep themselves away from this research. Further demand for increasing by-pass ratio will change the shape and weight of the duct that uplift encourages them to continue research in this field. Innumerable studies related to S-shaped duct have proven that its performance depends on many factors like curvature, upstream compressor’s vortices, swirl, insertion of struts, geometrical aspects, Mach number and many more. The application of flow control devices, wall shape optimization techniques, and integrated concepts lead a better system performance and shorten the duct length. This review paper is an endeavor to encapsulate all the above aspects and finally, it can be concluded that the intermediate duct is a key component to keep the overall weight and specific fuel consumption low. The shape and curvature of the duct significantly affect the pressure distortion. The wall static pressure distribution along the inner wall significantly higher than that of the outer wall. Duct pressure loss enhances with the aggressive design of duct, incursion of struts, thick inlet boundary layer and higher swirl at the inlet. Thus, one should focus on research areas for better aerodynamic effects of the above parameters which give duct design with optimum pressure loss and non-uniformity within the duct.

APA, Harvard, Vancouver, ISO, and other styles

19

Xue, L., G. E. O. Widera, and Z. F. Sang. "Influence of Pad Reinforcement on the Limit and Burst Pressures of a Cylinder-Cylinder Intersection." Journal of Pressure Vessel Technology 125, no. 2 (May 1, 2003): 182–87. http://dx.doi.org/10.1115/1.1563629.

Full text

Abstract:

The purpose of the paper is to provide experimental results for the limit pressure of a vessel-nozzle intersection under internal pressure with and without an intermediate pad-reinforced opening d/D=0.526. Two different methods, double elastic-slope and tangent intersection, are employed to determine the experimental limit pressure. A comparison of the limit and burst pressures with and without pad reinforcement is carried out. The present test results indicate that the pad reinforcement significantly improves the limit and the bust pressures. It can thus be concluded that pad reinforcement is an effective reinforcement method.

APA, Harvard, Vancouver, ISO, and other styles

20

Spieth, Peter M., Alysson R. Carvalho, Andreas Güldner, Paolo Pelosi, Oleg Kirichuk, Thea Koch, and Marcelo Gama de Abreu. "Effects of Different Levels of Pressure Support Variability in Experimental Lung Injury." Anesthesiology 110, no. 2 (February 1, 2009): 342–50. http://dx.doi.org/10.1097/aln.0b013e318194d06e.

Full text

Abstract:

Background Noisy pressure support ventilation has been reported to improve respiratory function compared to conventional assisted mechanical ventilation. We aimed at determining the optimal level of pressure support variability during noisy pressure support ventilation. Methods Twelve pigs were anesthetized and mechanically ventilated. Acute lung injury was induced by surfactant depletion. At four levels of pressure support variability (coefficients of variation of pressure support equal to 7.5, 15, 30, and 45%, 30 min each, crossover design, special Latin squares sequence), we measured respiratory variables, gas exchange, hemodynamics, inspiratory effort, and comfort of breathing. The mean level of tidal volume was constant among variability levels. Results Compared to conventional pressure support ventilation, different levels of variability in pressure support improved the elastance of the respiratory system, peak airway pressure, oxygenation, and intrapulmonary shunt. Oxygenation and venous admixture benefited more from intermediate (30%) levels of variability, whereas elastance and peak airway pressure improved linearly with increasing variability. Heart rate as well as mean arterial and pulmonary arterial pressures decreased slightly at intermediate to high (30-45%) levels of variability in pressure support. Inspiratory effort and comfort of breathing were not importantly influenced by increased variability in pressure support. Conclusion In a surfactant depletion model of acute lung injury, variability of pressure support improves lung function. The variability level of 30% seems to represent a reasonable compromise to improve lung functional variables during noisy pressure support ventilation.

APA, Harvard, Vancouver, ISO, and other styles

21

Shen, Qinghao, Run Huang, Zili Xu, and Wei Hua. "Numerical 3D Modeling: Microwave Plasma Torch at Intermediate Pressure." Applied Sciences 10, no. 15 (August 4, 2020): 5393. http://dx.doi.org/10.3390/app10155393.

Full text

Abstract:

This study represents a self-consistent three-dimensional (3D) fluid plasma model coupled with Maxwell equations at an intermediate pressure between 1000 and 5000 Pa. The model was established using the finite element method to analyze the effects of time–space characteristics, which is the variation of plasma parameters with time and the 3D spatial distribution of plasma parameters in the plasma torch at various times. The numerical modeling was demonstrated in three different stages, where the growth of electron density is associated with time. From the distribution characteristics of molecular ions, it can be concluded that they are distributed mainly at the port of the quartz tube of the torch, which is larger than the center of the tube. The density ratio of molecular ion to electron is decreased because of the reduction of pressure and distance, which has been calculated from the port to the center of the quartz tube. The analysis of microwave plasma parameters indicated that intermediate pressure is useful for modeling and plasma source designing, especially for carbon dioxide conversion.

APA, Harvard, Vancouver, ISO, and other styles

22

Koryagin, Anatoliy V. "On Selecting the Intermediate Pressure in Two-stage Compressors." Vestnik MEI 4, no. 4 (2018): 78–80. http://dx.doi.org/10.24160/1993-6982-2018-4-78-80.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Rousse, G., S. Klotz, A. M. Saitta, J. Rodriguez-Carvajal, M. I. McMahon, M. Mezouar, and B. Couzinet. "Resolution of the intermediate high pressure phase of PbTe." Acta Crystallographica Section A Foundations of Crystallography 61, a1 (August 23, 2005): c464. http://dx.doi.org/10.1107/s0108767305080682.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Wang, Heshen, Runzhang Xu, Cai Liu, Le Wang, Zhan Zhang, Huimin Su, Shanmin Wang, et al. "Pressure-Dependent Intermediate Magnetic Phase in Thin Fe3GeTe2 Flakes." Journal of Physical Chemistry Letters 11, no. 17 (August 12, 2020): 7313–19. http://dx.doi.org/10.1021/acs.jpclett.0c01801.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Oomi, G., R. Kuwahara, T. Kagayama, and A. Jung. "Pressure-induced volume anomaly of intermediate valence compound Sm0.9La0.1S." Journal of Magnetism and Magnetic Materials 226-230 (May 2001): 1182–83. http://dx.doi.org/10.1016/s0304-8853(00)00727-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Sidorov, V. A., N. N. Stepanov, L. G. Khvostantsev, O. B. Tsiok, A. V. Golubkov, V. S. Oskotski, and I. A. Smirnov. "Intermediate valency state of samarium chalcogenides under high pressure." Semiconductor Science and Technology 4, no. 4 (April 1, 1989): 286–87. http://dx.doi.org/10.1088/0268-1242/4/4/031.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Watanuki, Tetsu, Daichi Kawana, Akihiko Machida, and AnPang Tsai. "Intermediate-Valence Quasicrystals of Yb-Based Alloys Under Pressure." Journal of the Physical Society of Japan 80, Suppl.A (January 2, 2011): SA087. http://dx.doi.org/10.1143/jpsjs.80sa.sa087.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Knjazeva, Maria, Yurii Bronwald, Daria Andronikova, Georgiy Lityagin, Alexey Bosak, Parisiadis Paraskevas, Krystian Roleder, et al. "Modulated Structures in PbHfO₃ Crystals at High-Pressure-High-Temperature Conditions." Defect and Diffusion Forum 386 (September 2018): 149–55. http://dx.doi.org/10.4028/www.scientific.net/ddf.386.149.

Full text

Abstract:

Lead hafnate single crystals were characterized using single crystal x-ray diffraction under simultaneous application of hydrostatic pressure and high temperatures. The information on the structure of two intermediate phases, situated between antiferroelectric and paraelectric phases in the pressure-temperature phase diagram, has been obtained. The lower-temperature intermediate phase is characterized by incommensurate displacive modulations in Pb sublattice. The higher-temperature intermediate phase is characterized by oxygen framework distortion, primarily in the form of anti-phase tilts of the oxygen octahedra, which is also present in the lower-temperature intermediate phase.

APA, Harvard, Vancouver, ISO, and other styles

29

Taylor, J. A., J. Acharya, T. C. Pearson, and R. P. H. Thompson. "Zinc improves the filterability of sickle erythrocytes at intermediate oxygen partial pressures." Clinical Science 81, no. 3 (September 1, 1991): 433–38. http://dx.doi.org/10.1042/cs0810433.

Full text

Abstract:

1. The deformability of erythrocytes from patients with sickle-cell anaemia was measured with a St George's blood filtrometer at a range of oxygen partial pressures and at four levels of zinc loading. 2. When incubated in buffered saline containing zinc and the chelator ethyl maltol, erythrocytes rapidly accumulated zinc and thus their oxygen affinity was increased. 3. Neither the oxygen partial pressure nor zinc loading affected the filtration of normal erythrocytes. 4. Deoxygenation of sickle erythrocytes greatly impaired filtration, although the initial filtration rate declined sharply at different oxygen partial pressures (between 70 and 35 mmHg) in different patients. 5. Low levels of zinc (0.03 ± 0.003 mol of zinc/mol of haemoglobin tetramer) were without effect on sickle cells, but at zinc/haemoglobin ratios of 0.6:1 and above, the sharp fall in filtration rate occurred at oxygen partial pressures 8–25 mmHg below the oxygen partial pressure that impaired filtration of untreated cells. 6. Hence, the deformability of sickle erythrocytes in vitro can be improved by increasing the intracellular content of zinc to 20-fold above normal. Further studies are now required to examine the stability of zinc in erythrocytes, the effects of high intracellular zinc concentrations on erythrocyte viability, and the toxicity of zinc released from zinc-laden cells.

APA, Harvard, Vancouver, ISO, and other styles

30

Slama, Vaclav, David Simurda, and Richard Lenhard. "Study on Losses in the Intermediate-Pressure Steam Turbine Inlet Chamber." MATEC Web of Conferences 369 (2022): 01002. http://dx.doi.org/10.1051/matecconf/202236901002.

Full text

Abstract:

Know-how about energy and pressure losses in all steam turbine parts is crucial to guarantee enhanced operational reliability and efficiency. This paper focuses on studying pressure losses in the intermediate-pressure turbine inlet chamber. Measurements were performed on a complex model consisting of the turbine inlet chamber, a compact valve assembly situated upstream, and nozzles located downstream. These intermediate-pressure turbine parts are larger due to the greater volumetric mass flow than the high-pressure turbine parts. However, their inner parts are proportionately smaller, which causes greater pressure losses. Measurements were carried out in the Aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences, where the model was installed in an in-draft wind tunnel. The results were complemented by numerical simulations performed in the Doosan Skoda Power company using ANSYS software tools. Pressure losses were evaluated using the total pressure loss coefficient and, as a result, can be predicted in similar turbine inlet chambers with the required accuracy.

APA, Harvard, Vancouver, ISO, and other styles

31

Lewin, Jan S., Reginald F. Baugh, and Shan R. Baker. "An Objective Method for Prediction of Tracheoesophageal Speech Production." Journal of Speech and Hearing Disorders 52, no. 3 (August 1987): 212–17. http://dx.doi.org/10.1044/jshd.5203.212.

Full text

Abstract:

Current methods of esophageal air insufflation testing to predict postoperative tracheoesophageal speech success lack procedural objectivity and rely on subjective interpretation of the voice production results. A range of intraesophageal pressure measurements was obtained prior to tracheoesophageal (TE) puncture in each of 27 laryngectomized patients in an attempt to predict TE speech outcome. Postoperatively, three levels of speech production were identified. Fluent speakers, nonfluent speakers, and nonspeakers demonstrated low, intermediate, and high intraesophageal pressures, respectively. Patients with intermediate and high preoperative pressures did not achieve fluent speech without myotomy. This technique offers a reliable, objective preoperative indication of expected TE speech fluency.

APA, Harvard, Vancouver, ISO, and other styles

32

Sun, Shanshan, Junhai Zhao, and Changguang Zhang. "Calculation of Silo Wall Pressure considering the Intermediate Stress Effect." Advances in Civil Engineering 2018 (September 18, 2018): 1–10. http://dx.doi.org/10.1155/2018/3673515.

Full text

Abstract:

The reasonable determination of wall pressure is critical for the design of silo structures. In this study, the primary objective is to present four novel wall pressure coefficients based on four true triaxial strength criteria in the quasiplane strain state. These four strength criteria are the Drucker-Prager (D-P) criterion, the Matsuoka-Nakai (M-N) criterion, the Lade-Duncan (L-D) criterion, and the unified strength theory (UST), and they all consider the effect of the intermediate stress yet to different extent. These coefficients have a wide application range and are readily used to predict the distribution of wall pressure for deep and squat silos. Comprehensive comparisons are made between the predictions from the wall pressure coefficients described herein and experimental data reported in the literature as well as the results from the European, American, and Chinese silo standards or the Rankine and the modified Coulomb theories. It is found that the effect of the intermediate stress on the wall pressure is very significant for both deep and squat silos; the wall pressure of the D-P criterion is underestimated, whereas that of the Mohr-Coulomb (M-C) criterion is overestimated; the L-D criterion is recommended to be adopted to calculate the soil wall pressure.

APA, Harvard, Vancouver, ISO, and other styles

33

Fedorova, M. A. "Elbel S., Hrnjak P. Performance optimization of two-stage compressor system using transcritical R744 / trans. from Engl. M. A. Fedorova." Omsk Scientific Bulletin. Series Aviation-Rocket and Power Engineering 5, no. 2 (2021): 66–77. http://dx.doi.org/10.25206/2588-0373-2021-5-2-66-77.

Full text

Abstract:

The use of transcritical R744 systems has become increasingly popular in recent years in a variety of different applications. For applications that span a wide temperature range between the heat source and heat sink, the use of two-stage compressor results in numerous advantages in terms of efficiency and compressor discharge temperature. This paper presents experimental data for a transcritical R744 compressor system operating at high heat rejection temperatures. A comprehensive system model was developed and validated with the experimental results. Based on this, the simulation tool was used to further optimize the system design specifically to accommodate the two-stage compression process. The optimum heat transfer area distribution has been determined to simultaneously ensure efficient intercooling at intermediate pressure and gas cooling at the high-pressure level. Simultaneously, the system was also optimized with respect to optimal intermediate pressure and the results show that for this particular system, the optimum intercooler pressure deviated substantially from the standard design approach that uses the geometric mean between suction and discharge pressures

APA, Harvard, Vancouver, ISO, and other styles

34

Wang, Yang. "The Influence of Upstream Flow Angle Variation on Intermediate Turbine Duct." Applied Mechanics and Materials 670-671 (October 2014): 705–8. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.705.

Full text

Abstract:

Intermediate turbine duct represent the flow path between the high pressure and low pressure turbine. Caused by the complex flow mechanism, the outlet flow condition of the high pressure turbine is easily changed. Since the upstream flow condition from the high pressure turbine has a significant effect on the internal flow field of intermediate turbine duct, the study in the upstream condition is of high value. Through numerical simulation, the influence of upstream flow angle variation on intermediate turbine duct is observed. It is found that the main influence of the flow angle variation is near the hub side of the duct, and the quantitative result shows that a larger flow angle has a positive effect on the flow field and can reduce loss.

APA, Harvard, Vancouver, ISO, and other styles

35

Matsumoto, Hiroyuki, Shusaku Inoue, and Tatsuo Ohmachi. "Dynamic Response of Bottom Water Pressure due to the 2011 Tohoku Earthquake." Journal of Disaster Research 7, sp (August 1, 2012): 468–75. http://dx.doi.org/10.20965/jdr.2012.p0468.

Full text

Abstract:

Water pressure changes have been recorded during the 2011 Tohoku earthquake (Mw9.0) by two oceanbottom pressure gauges of the JAMSTEC cabled observatory located approximately 400 km north of the tsunami source. In the present study, observed water pressure fluctuations have been interpreted by timefrequency processing analysis, followed by a comparison with those fluctuations of ocean-bottomseismometers. Acoustic resonance has been involved due to seismic waves even in the intermediate-field. The present study suggests that water pressure fluctuations during the 2011 Tohoku earthquake are dominated by oceanbottom acceleration and velocity for the intermediate frequency range and the high-frequency range, respectively, and its threshold roughly coincides with the fundamental acoustic resonant frequency. Water pressure amplitude is independent, in contrast, on bottom oscillations in the low-frequency range, for which the threshold is related to intermediate waves rather than shallow water waves.

APA, Harvard, Vancouver, ISO, and other styles

36

Deal, E. C., M. A. Haxhiu, M. P. Norcia, J. Mitra, and N. S. Cherniack. "Influence of the ventral surface of the medulla on tracheal responses to CO2." Journal of Applied Physiology 61, no. 3 (September 1, 1986): 1091–97. http://dx.doi.org/10.1152/jappl.1986.61.3.1091.

Full text

Abstract:

These studies investigated the role of the intermediate area of the ventral surface of the medulla (VMS) in the tracheal constriction produced by hypercapnia. Experiments were performed in chloralose-anesthetized, paralyzed, and artificially ventilated cats. Airway responses were assessed from pressure changes in a bypassed segment of the rostral cervical trachea. Hyperoxic hypercapnia increased tracheal pressure and phrenic nerve activity. Intravenous atropine pretreatment or vagotomy abolished the changes in tracheal pressure without affecting phrenic nerve discharge. Rapid cooling of the intermediate area reversed the tracheal constriction produced by hypercapnia. Graded cooling produced a progressive reduction in the changes in maximal tracheal pressure and phrenic nerve discharge responses caused by hypercapnia. Cooling the intermediate area to 20 degrees C significantly elevated the CO2 thresholds of both responses. These findings demonstrate that structures near the intermediate area of the VMS play a role in the neural cholinergic responses of the tracheal segment to CO2. It is possible that neurons or fibers in intermediate area influence the motor nuclei innervating the trachea. Alternatively, airway tone may be linked to respiratory motor activity so that medullary interventions that influence respiratory motor activity also alter bronchomotor tone.

APA, Harvard, Vancouver, ISO, and other styles

37

Lu, Zongyu, Jun Li, Wei Lian, Shiyuan Xie, Xuegang Wang, Hao Zhang, and Lin Song. "The Failure Mechanism and Countermeasures of Cement Sheath in Vertical Section of Well during Hydraulic Fracturing." Processes 11, no. 5 (May 8, 2023): 1425. http://dx.doi.org/10.3390/pr11051425.

Full text

Abstract:

The sustained casing pressure (SCP) phenomenon of shale gas and oil wells occurs frequently after fracturing; therefore, in order to assess the cement sheath’s integrity in the vertical well portion, the cement stones were subjected to a compression test under different temperatures and confining pressures to obtain the mechanical parameters of the cement sheath at different well depths. The integrity of the cement ring between the production casing and the intermediate casing was then investigated using the Moore–Coulomb criterion. We also took into account other elements including pump pressure, production casing wall thickness, and cement ring mechanical properties. The results show that (1) the compressive strength, Poisson’s ratio, and Young’s modulus of cement stone vary obviously under different confining pressures and temperature conditions, and the cement stone shows elastic–brittle failure characteristics at 20 °C. The compressive strength, Poisson’s ratio, and Young’s modulus increase with the confining pressure, but the Young’s modulus and compressive strength gradually decrease with the increase in temperature, while the stress–strain curves show obvious plastic failure characteristics at 80 °C and 130 °C. (2) The tangential tensile stress decreases and depth increases from the wellhead to the intermediate casing shoe, while the radial compressive stress of the cement sheath increases. The stress state of the cement sheath changes abruptly at the position of the casing shoe due to the change in casing layers, and under the intermediate casing shoe, the tangential tensile stress changes from tension to compression. When a conventional cementing slurry system is used, the integrity of the cement sheath above the intermediate casing shoe will fail during fracturing. (3) Reducing the pump pressure and increasing casing wall thickness can reduce the tangential and radial stresses of the cement sheath, but the integrity of cement sheath cannot be fully guaranteed. For the cement sheath’s sealing integrity, it is advantageous to decrease the Young’s modulus and raise its strength.

APA, Harvard, Vancouver, ISO, and other styles

38

Ikeuchi, Hidekazu, Shigeru Kunugi, Naoki Tanaka, and Reinhard Lange. "Observation of a Pressure-Induced Unfolding Intermediate of Thermolysin by Using Pressure-Jump Method." Polymer Journal 34, no. 8 (August 2002): 629–32. http://dx.doi.org/10.1295/polymj.34.629.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Goździk, Dawid, Bartosz FIKUS, and Jacek KIJEWSKI. "Preliminary Comparative Investigations on Ballistic Properties of Intermediate Cartridges." Problems of Mechatronics Armament Aviation Safety Engineering 11, no. 4 (December 30, 2020): 27–44. http://dx.doi.org/10.5604/01.3001.0014.5641.

Full text

Abstract:

The preliminary results of comparative investigations on intermediate cartridges were presented in this paper. The research focused mainly on the adopted assumptions and verification of research methods. Pressure ballistic test barrels, manufactured according to NATO EPVAT standards, were used for tests. The pressure courses of propellant gases in the barrel and the projectile velocity at four points of the bullet trajectory were measured. The pressure impulses, R100 parameter at 50 m and average bullet drag coefficient were calculated for each type of cartridge. The results allowed for a preliminary ballistic comparison of the most popular types of intermediate cartridges.

APA, Harvard, Vancouver, ISO, and other styles

40

de Paula, Osni Bastos, Marina Pervukhina, Dina Makarynska, and Boris Gurevich. "Modeling squirt dispersion and attenuation in fluid-saturated rocks using pressure dependency of dry ultrasonic velocities." GEOPHYSICS 77, no. 3 (May 1, 2012): WA157—WA168. http://dx.doi.org/10.1190/geo2011-0253.1.

Full text

Abstract:

Modeling dispersion and attenuation of elastic waves in fluid-saturated rocks due to squirt flow requires the knowledge of a number of geometrical parameters of the pore space, in particular, the characteristic aspect ratio of the pores. These parameters are usually inferred by fitting measurements on saturated rocks to model predictions. To eliminate such fitting and thus make the model more predictive, we propose to recover the geometrical parameters of the pore space from the pressure dependency of elastic moduli on dry samples. Our analysis showed that the pressure dependency of elastic properties of rocks (and their deviation from Gassmann’s prediction) at ultrasonic frequencies is controlled by the squirt flow between equant, stiff, and so-called intermediate pores (with aspect ratios between [Formula: see text]). Such intermediate porosity is expected to close at confining pressures of between 200 and 2000 MPa, and thus cannot be directly obtained from ultrasonic experiments performed at pressures below 50 MPa. However, the presence of this intermediate porosity is inferred from the significant linear trend in the pressure dependency of elastic properties of the dry rock and the difference between the bulk modulus of the dry rock computed for spherical pores and the measured modulus at 50 MPa. Moreover, we can infer the magnitude of the intermediate porosity and its characteristic aspect ratio. Substituting these parameters into the squirt model, we have computed elastic moduli and velocities of the water-saturated rock and compared these predictions against laboratory measurements of these velocities. The agreement is good for a number of clean sandstones, but not unexpectedly worse for a broad range of shaley sandstones. Our predictions showed that dispersion and attenuation caused by the squirt flow between compliant and stiff pores may occur in the seismic frequency band. Confirmation of this prediction requires laboratory measurements of elastic properties at these frequencies.

APA, Harvard, Vancouver, ISO, and other styles

41

Zhang, Yu, Yang Zhao, Jin Liu, Tian-Yi Meng, Sheng-Jun Shao, and Fang-Tao She. "An Experimental Study on the Deformation and Strength Characteristics of Q3 Loess under a Plain Strain Anisotropic Consolidation Condition." Advances in Civil Engineering 2021 (February 2, 2021): 1–13. http://dx.doi.org/10.1155/2021/8813707.

Full text

Abstract:

To study the strength, deformation characteristics, and intermediate principal stress of intact loess, vertical loading stress tests with different initial stress state k value were conducted under different confining pressures. Plane strain tests were carried out by the transformed true triaxial apparatus of Xi’an University of Technology. The study shows that loess tends to be in a plastic failure state in different confining pressures and k values, and the stress-strain relationship curve is of a hardening type. Results reveal that loess lateral and volume deformations have nonlinear relationships with its vertical deformation, and volume deformation shrinks in the process of shearing. The effect of confining pressure on soil deformation is greater than k value. The intermediate principal stress coefficient decreases with the increase of the confining pressure and transforms from increasing to decreasing with the increase of k value (ranging from 0.2 to 0.4). In brief, the loess failure strength is closely related to k value, confining stress, and spherical stress state. When k value increases, cohesion effect reduces, whereas internal friction angle increases linearly. The influence of k value on soil strength and deformation is closely related to confining pressure.

APA, Harvard, Vancouver, ISO, and other styles

42

Kremer, W., M. R. Arnold, N. Kachel, and H. R. Kalbitzer. "The use of high–sensitivity sapphire cells in high pressure NMR spectroscopy and its application to proteins." Spectroscopy 18, no. 2 (2004): 271–78. http://dx.doi.org/10.1155/2004/407619.

Full text

Abstract:

The application of high pressure in bioscience and biotechnology has become an intriguing field in un/refolding and misfolding processes of proteins. NMR spectroscopy is the only generally applicable method to monitor pressure–induced structural changes at the atomic level in solution. Up to now the application of most of the multidimensional NMR experiments is impossible due to the restricted volume of the high pressure glass cells which causes a poor signal–to–noise ratio. Here we present high strength single crystal sapphire cells which double the signal–to–noise ratio. This increased signal–to–noise ratio is necessary to perform, for example, phophorus NMR spectroscopy under variable pressures. To understand the effect of pressure on proteins, we need to know the pressure dependence of1H chemical shifts in random coil model tetrapeptides. The results allow distinguishing structural changes from the pressure dependence of the chemical shifts. In addition, the influence of pressure on the buffer system was investigated. Since high pressure was shown to populate intermediate amyloidogenic states of proteins the investigation of pressure effects on proteins involved in protein conformational disorders like Alzheimer's Disease (AD) and Transmissible Spongiform Encephalopathies (TSE) is of keen interest.1H–15N–TROSY–spectra were acquired to study the effects of pressure and temperature on chemical shifts and signal volumes of the human prion protein. These measurements show identical pressure sensitivity ofhuPrP(23–230) andhuPrP(121–230). First results suggest a folding intermediate for the human prion protein which can be populated by high hydrostatic pressure.

APA, Harvard, Vancouver, ISO, and other styles

43

Zhu, Xinyi, and Miaocheng Weng. "Study on the influence of intermediate airshafts on the aerodynamic effect of urban rapid rail transit." Journal of Physics: Conference Series 2730, no. 1 (June 1, 2024): 012029. http://dx.doi.org/10.1088/1742-6596/2730/1/012029.

Full text

Abstract:

Abstract This study explores how intermediate airshafts affect the aerodynamics of urban rapid transit trains in tunnels. It employs a three-dimensional turbulence model to simulate train-tunnel interactions, specifically examining airshafts’ impact on transient pressure variations along surfaces. The model’s accuracy and reliability are confirmed by comparing results with full-scale experimental data. The results show that airshafts effectively mitigate peak tunnel wall pressures, with the lowest peak overpressure observed at the airshaft location. With the airshaft-reflected expansion wave arriving ahead of the train, the pressure between the train front and tunnel wall decreases compared to scenarios without airshafts. Similar transient pressure changes at the tunnel entrance and rear half suggest the emergence of a “secondary compression wave” due to the train’s transit.

APA, Harvard, Vancouver, ISO, and other styles

44

Songjian, Li, Zheng Wei, Xu Wei, and Ling Hong. "Numerical calculation and experimental study on friction and lubrication of Stirling engine piston ring." E3S Web of Conferences 313 (2021): 02002. http://dx.doi.org/10.1051/e3sconf/202131302002.

Full text

Abstract:

To solve the practical problem of Stirling engine piston ring, numerical model on friction and lubrication were established based on average Reynolds equation theory. Numerical calculation results show: piston rings are in the mixed lubrication state which gas lubrication film and micro-convex body contact existing simultaneously; contact pressure is 2 orders of magnitude less than gas film pressure; contact pressure is approximately linearly related to mean gas pressure. Simulated test rig was built and experimental results show: high-pressure working gas leak to intermediate chamber through piston rings, and the pressure of intermediate chamber drops sharply at lowest pressure of circulation; piston ring wear increases when rotational speed or working pressure increase. The accuracy of numerical model was proved by experimental phenomena and test data.

APA, Harvard, Vancouver, ISO, and other styles

45

Bouaziz, Nahla, D. Lounissi, Lakdar Kairouani, and M. El Ganaoui. "Exergetic Analyses of a Particular Absorption Cooling System." Defect and Diffusion Forum 326-328 (April 2012): 641–46. http://dx.doi.org/10.4028/www.scientific.net/ddf.326-328.641.

Full text

Abstract:

The objective of this work is to present an exergy analysis of a novel absorption configuration using water-ammonia as working fluid. The proposed configuration operates at three pressure levels. The absorber is at an intermediate pressure (Pint). A thermodynamic model based on the mass energy and exergy balances is developed for this purpose. The parameters analyzed are the refrigeration systems performance (COP), the exergy efficiency, the global exergy destruction in the system, the exergy destruction and the irreversibility in different components. The effects of generator, absorber, condenser and evaporator on the performance of the system are examined. Numerical results highlight the great importance of the intermediate pressure on the performance of the system and specially on reducing the operating generator temperature. Consequently, the intermediate pressure is directly responsible on the adaptability of the proposed cooling absorption cycle to low enthalpy sources.

APA, Harvard, Vancouver, ISO, and other styles

46

Harshfield, Gregory A., Derrick A. Pulliam, Bruce S. Alpert, F. Bruder Stapleton, Elaine S. Willey, and Grant W. Somes. "Ambulatory Blood Pressure Patterns in Children and Adolescents: Influence of Renin-Sodium Profiles." Pediatrics 87, no. 1 (January 1, 1991): 94–100. http://dx.doi.org/10.1542/peds.87.1.94.

Full text

Abstract:

A renin-sodium nomogram for normotensive children and adolescents was developed at our institution. The ambulatory blood pressure patterns of subjects classified by the nomogram were then compared. A biracial sample of 159 children and adolescents were classified as having a low, intermediate, or high renin-sodium profile based on the relationship between their plasma renin activity and 24-hour urinary sodium excretion. Casual (106/58 vs 107/61 vs 106/62 mm Hg) and awake (116/69 vs 117/69 vs 116/70 mm Hg) blood pressure values were comparable among subjects with low, intermediate, and high renin-sodium profiles. Subjects with high renin-sodium profiles, however, had a smaller decline in systolic blood pressure with sleep than did subjects with low renin-sodium profiles (7 vs 11 mm Hg; P < .04), and higher diastolic blood pressure readings during sleep than subjects with intermediate renin-sodium profiles (65 vs 62 mm Hg; P < .05). Subjects with high renin-sodium profiles also had greater variance of diastolic blood pressure readings during sleep than either subjects with low renin-sodium profiles (P < .01) or those with intermediate renin-sodium profiles (P < .02). The blunted nocturnal decline and increased nocturnal variance of blood pressure among subjects with high renin-sodium profiles may be a marker or mechanism for the future development of essential hypertension.

APA, Harvard, Vancouver, ISO, and other styles

47

Gawraczyński, Jakub, Łukasz Wolański, Adam Grzelak, Zoran Mazej, Viktor Struzhkin, and Wojciech Grochala. "Phase Transitions and Amorphization of M2AgF4 (M = Na, K, Rb) Compounds at High Pressure." Crystals 12, no. 4 (March 25, 2022): 458. http://dx.doi.org/10.3390/cryst12040458.

Full text

Abstract:

We report the results of high-pressure Raman spectroscopy studies of alkali metal fluoroargentates (M2AgF4, where M = Na, K, Rb) combined with theoretical and X-ray diffraction studies for the K member of the series. Theoretical density functional calculations predict two structural phase transitions for K2AgF4: one from low-pressure monoclinic P21/c (beta) phase to intermediate-pressure tetragonal I42d structure at 6 GPa, and another to high-pressure triclinic P1 phase at 58 GPa. However, Raman spectroscopy and X-ray diffraction data indicate that both polymorphic forms of K2AgF4, as well as two other fluoroargentate phases studied here, undergo amorphization at pressures as low as several GPa.

APA, Harvard, Vancouver, ISO, and other styles

48

Sekhar, T. V. S., R. Sivakumar, and T. V. R. Ravi Kumar. "Drag and pressure fields for the MHD flow around a circular cylinder at intermediate Reynolds numbers." Journal of Applied Mathematics 2005, no. 3 (2005): 183–203. http://dx.doi.org/10.1155/jam.2005.183.

Full text

Abstract:

Steady incompressible flow around a circular cylinder in an external magnetic field that is aligned with fluid flow direction is studied forRe(Reynolds number) up to 40 and the interaction parameter in the range0≤N≤15(or0≤M≤30), whereMis the Hartmann number related toNby the relationM=2NRe, using finite difference method. The pressure-Poisson equation is solved to find pressure fields in the flow region. The multigrid method with defect correction technique is used to achieve the second-order accurate solution of complete nonlinear Navier-Stokes equations. It is found that the boundary layer separation at rear stagnation point forRe=10is suppressed completely whenN<1and it started growing again whenN≥9. ForRe=20and 40, the suppression is not complete and in addition to that the rear separation bubble started increasing whenN≥3. The drag coefficient decreases for low values ofN(<0.1)and then increases with increase ofN. The pressure drag coefficient, total drag coefficient, and pressure at rear stagnation point vary withN. It is also found that the upstream and downstream pressures on the surface of the cylinder increase for low values ofN(<0.1)and rear pressure inversion occurs with further increase ofN. These results are in agreement with experimental findings.

APA, Harvard, Vancouver, ISO, and other styles

49

Yi, Jie, Fang-Bao Tian, Anne Simmons, and Tracie Barber. "A Computational Analysis of the Influence of a Pressure Wire in Evaluating Coronary Stenosis." Fluids 6, no. 4 (April 20, 2021): 165. http://dx.doi.org/10.3390/fluids6040165.

Full text

Abstract:

Cardiovascular disease is one of the world’s leading causes of morbidity and mortality. Fractional flow reserve (FFR) was proposed in the 1990s to more accurately evaluate the functional severity of intermediate coronary stenosis, and it is currently the gold standard in cardiac catheterization laboratories where coronary pressure and flow are routinely obtained. The clinical measurement of FFR relies on a pressure wire for the recording of pressures; however, in computational fluid dynamics studies, an FFR is frequently predicted using a wire-absent model. We aim to investigate the influence of the physical presence of a 0.014-inch (≈0.36 mm) pressure wire in the calculation of virtual FFR. Ideal and patient-specific models were simulated with the absence and presence of a pressure wire. The computed FFR reduced from 0.96 to 0.93 after inserting a wire in a 3-mm non-stenosed (pipe) ideal model. In mild stenotic cases, the difference in FFR between the wire-absent and wire-included models was slight. The overestimation in severe case was large but is of less clinical significance because, in practice, this tight lesion does not require sophisticated measurement to be considered critical. However, an absence of the pressure wire in simulations could contribute to an over-evaluation for an intermediate coronary stenosis.

APA, Harvard, Vancouver, ISO, and other styles

50

Stathopoulos, Ted, Kai Wang, and Hanqing Wu. "Proposed new Canadian wind provisions for the design of gable roofs." Canadian Journal of Civil Engineering 27, no. 5 (October 1, 2000): 1059–72. http://dx.doi.org/10.1139/l00-023.

Full text

Abstract:

Wind pressure coefficients for gable roofs of low buildings are strongly dependent on roof angle, particularly for intermediate roof slopes (roof angle 10°-30°). This paper addresses the suitability of wind pressure coefficients specified in the National Building Code of Canada (NBCC) for gable roofs in the intermediate slope range. In a recent research study, a series of low building models with different roof slopes were tested in a boundary layer wind tunnel under simulated open country conditions. This was different from the original study in the 1970s, which produced the current wind provisions on the basis of a model tested only for a single roof slope (4:12) in this intermediate roof slope range. The results of the study suggest that a modification of the wind provisions of NBCC would be warranted to make them more representative of the true local and area-averaged wind loads imposed on gable roofs of intermediate slope.Key words: building, code, design, pressure, roof, standard, wind.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Intermediate pressure'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles