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Novel pressure field assisted non-hydrolytic sol-gel method is developed for the in-situ synthesis of novel seed-pulp-structured C@ZrSiO 4 pigments. The obtained pigments, which are composed of in-situ carbon derived from leaving organic groups as core and zircon as shell, were characterized via DSC-TG, XRD, FT-IR, Raman, XPS, SEM, TEM, UV–Vis, and automatic colorimeters. It was found that the pressure field promotes the non-hydrolytic sol-gel heterogeneous polycondensation reaction and the direct transformation of reaction groups into in-situ spherical carbon. Meanwhile, the in-situ spherical carbon was enclosed by heterogeneous condensation bonds wrap and formed a dense structure. The as-prepared pigments exhibited excellent color rendering performance (L* = 21.07, a* = 0.48, b* = 0.75) and thermal stability. [ABSTRACT FROM AUTHOR]

A four-dimensional differential Euler-Lagrange equation for continuously distributed materials is derived based on the principle of least action, and instead of Lagrangian, this equation contains the Lagrangian density. This makes it possible to determine the density of generalized fourmomentum in covariant form as derivative of the Lagrangian density with respect to four-velocity of typical particles of a system taken with opposite sign, and then calculate the generalized fourmomentum itself. It is shown that the generalized four-momentum of all typical particles of a system is an integral four-vector and therefore should be considered as a special type of fourvectors. The presented expression for generalized four-momentum exactly corresponds to the Legendre transformation connecting the Lagrangian and Hamiltonian. The obtained formulas are used to calculate generalized four-momentum of stationary and moving relativistic uniform systems for the Lagrangian with particles and vector fields, including electromagnetic and gravitational fields, acceleration field and pressure field. It turns out that the generalized fourmomentum of a moving system depends on the total mass of particles, on the Lorentz factor and on the velocity of the system's center of momentum. Besides, an additional contribution is made by the scalar potentials of the acceleration field and the pressure field at the center of system. The direction of the generalized four-momentum coincides with the direction of four-velocity of the system under consideration, while the generalized four-momentum is part of the relativistic fourmomentum of the system. [ABSTRACT FROM AUTHOR]

Switching wells in high-temperature and high-pressure gas wells will affect parameters such as the temperature and pressure of the fluid in the wellbore. Dynamic monitoring of temperature and pressure is difficult, and wellbore temperature, pressure, and fluid physical parameters are coupled to each other. Obtaining them separately will lead to large calculation errors. In order to improve the prediction accuracy of temperature and pressure in high-temperature and high-pressure gas wells, Based on the temperature–pressure coupling algorithm, this study compares the advantages and disadvantages of nine classic algorithms based on the temperature–pressure coupling algorithm, considers the impact of high temperature and high pressure on the temperature and pressure of the gas wellbore fluid, and establishes an unsteady temperature–pressure coupling model for high-temperature and high-pressure gas wells under on–off well conditions. Comparing with the measured data, it is proved that the prediction accuracy of the unsteady temperature–pressure coupling model of high-temperature and high-pressure gas wells meets the construction requirements of switch wells. The established model is used to simulate the temperature and pressure distribution of two high-temperature and high-pressure gas wells under switching conditions. The analysis shows that the distribution of wellbore temperature and pressure under the switch on and off conditions is affected by the gas–water ratio, heat transfer coefficient, tube size, and gas well production. Among them, the gas–water ratio increased by 1.5 times, the wellhead temperature increased by 25%, and the wellhead pressure decreased is 7.68%; When the heat transfer coefficient is increased by 1.5 times, the wellhead temperature drops to 34.38% and the wellhead pressure drops to 2.29%. When the tube size is increased by 1.125 times, the wellhead temperature is reduced by 44.20% and the pressure is increased by 6.09%. When the production of gas well is doubled, the wellhead temperature increases by 40.79% and the wellhead pressure decreases by 2.29%. The results can be used as a basis for the construction of high-temperature and high-pressure gas wells. [ABSTRACT FROM AUTHOR]

Prepared dishes are increasingly popular convenience food that can be eaten directly from hygienic packaging by heating. Physics field (PF) is food processing method built with physical processing technology, which has the characteristics of high efficiency and environmental safety. This review focuses on summarizing the application of PFs in prepared dishes, evaluating and comparing PFs through quality changes during processing and storage of prepared dishes. Currently, improving the quality and extending the shelf life of prepared dishes through thermal and non-thermal processing are the main modes of action of PFs. Most PFs show good potential in handing prepared dishes, but may also react poorly to some prepared dishes. In addition, the difficulty of precise control of processing conditions has led to research mostly at the laboratory stage, but as physical technology continues to break through, more PFs and multi-physical field will be promoted for commercial use in the future. This review contributes to a deeper understanding of the effect of PFs on prepared dishes, and provides theoretical reference and practical basis for future processing research in the development of various enhanced PFs. Prepared dishes are classified according to the degree of processing. Physical fields are classified and described according to different physical methods. The application of efficient physical fields to prepared dishes is described. The application of efficient physical fields and its combination in food processing is prospected. [ABSTRACT FROM AUTHOR]

In order to reveal the physical properties of CO2 under actual formation conditions, this paper establishes a mathematical model of the temperature field and pressure field in the wellbore under CO2 injection conditions, optimizes the state equation of CO2 physical-property parameters, calculates the change trend of CO2 density, viscosity, and compression factor along the wellbore, and obtains the influence law of CO2 corrosion on the casing and interface. The viscosity showed a downward trend along the well depth; the compression factor showed an upward trend. The surfaces of the three casings were smooth and flat without obvious defects, the cement structure was dense, and there was no obvious pore structure. After corrosion, with the increase of Cr content, the change of interfacial corrosion decreases. The morphology of the Q125 and 3Cr interface is loose after corrosion, while there is no obvious change in the 13Cr interface. With the prolongation of corrosion time, low wellbore internal pressure easily causes casing yield, and high wellbore internal pressure easily causes cement-sheath compression failure. The circumferential stress of the casing increases with the corrosion time extension, and the radial stress of the casing and cement sheath decreases first and then increases with the corrosion time. The compressive strength of the cement sheath does not exceed the compressive strength. [ABSTRACT FROM AUTHOR]

IntroductionEnsuring hemodynamic stability with adequate perfusion to vital organs is critical to the safe conduct of anesthesia. Recent advances in hemodynamic monitoring technologies allow pressure, flow, and resistance to be measured continuously; however, there is limited evidence to suggest that these technologies alter clinical management or improve patient outcomes significantly. This may be because the fundamental hemodynamic model, established by Starling and Guyton, fails to offer the granular level of insight needed to guide clinical management.MethodsWe collected hemodynamic data from 950 patients who underwent major surgery with advanced hemodynamic monitoring (AHM) that provided continuously derived cardiac output and vascular resistance measurements. These measurements were based on the hemodynamic model of Starling and Guyton. Additionally, investigational monitoring software was developed to visualize a different hemodynamic model, termed the “pressure field” model. This model expresses the pulsatile, beat-to-beat relationship between ventricular performance (measured by stroke volume) and vascular tone (indicated by systemic elastance).ResultsWithin this dataset were several patients who experienced major hemorrhage. Case studies of these patients demonstrate that abnormal pressure and flow regulation patterns are observed through the lens of the pressure field model, but these patterns are typically not visible through the lens of the traditional Starling and Guyton model (cardiac output and systemic vascular resistance, which involve averaging hemodynamic performance over successive cardiac cycles). Furthermore, “before and after” case studies using our investigational pressure field monitoring software suggest that the traditional Starling and Guyton hemodynamic model has limited utility in managing hemorrhage.DiscussionWe propose that the pressure field model may allow hemorrhage to be managed more effectively via improved monitoring granularity [the beat-by-beat visualization of the stroke volume-systemic elastance relationship, rather than the use of the composite metrics of cardiac output (heart rate × stroke volume) and systemic vascular resistance]. Further research into the utility of the pressure field model is warranted.

Abstract Managed pressure cementing (MPC) is a new technology based on managed pressure drilling, which has a greater advantage in facing narrow density window formations. However, the existing pressure prediction models during MPC injection stage consider fewer factors and have lower accuracy. To this end, combined with the characteristics of the injection stage, a predictive model of the distribution of annular fluid type was first proposed. Then, based on the experimental results, fluid density and rheology as a function of temperature and pressure were fitted. The governing equation of temperature‐pressure field was established. Eventually the fluid performance parameters–temperature–pressure coupling prediction model was developed in this paper. By comparing the predicted pump pressure with the measured pump pressure, the maximum relative error is not more than 10%. Using this model, the fluid type distribution, temperature field distribution, and pressure field distribution were investigated. The results indicated that the distribution of fluid types in the wellbore presented a complex variation, with up to 10 fluids in the casing and up to five fluids in the annulus. The trend of temperature field is complex, with three turning points. The larger the formation temperature gradient, the higher the fluid temperature in the annulus. The influence law of fluid heat conduction coefficient is reversed at 6750 m. Decreasing drilling fluid density will trigger gas channeling, while increasing drilling fluid density will increase the risk of fracturing formation, and safe operation can be realized by MPC. The variation of the static pressure in the casing is more complicated than in the annulus and the annular circulation pressure in the eccentric casing is smaller than that of the concentric casing, which is due to the smaller annular friction pressure. This study can provide a theoretical basis for the prediction of hydrodynamic parameters during the MPC injection stage.

AbstractNon-physiological blood flow conditions in axial blood pumps lead to some complications, including hemolysis, platelet activation, thrombosis, and embolism. The high speed of the axial blood pump destroys large amounts of erythrocytes, thereby causing hemolysis and thrombosis. Thus, this study aims to reduce the vortices and reflux in the flow field by optimizing the axial blood pump. The axial blood pump and arterial flow field were modeled by the finite element method. The blood was assumed to be incompressible, turbulent, and Newtonian. The SST k–ω turbulence model was used. The frozen rotor method was also used to calculate the snapshot of motion. Many vortices and reflux exist in the flow field of the blood pump without optimization. The improved flow field had almost no vortex and reflux, thereby reducing the exposure time of blood. The optimized blood pump had little influence on the pressure field and shear stress field. The optimized blood pump mainly reduced the vortex, reflux, and the risk of thrombosis in the flow field. The flow field characteristics of an axial blood pump were studied, and the results showed the risk of thrombosis and hemolysis in the blood pump. In accordance with the relationship between the blade shape and the flow field, the blade of the blood pump was optimized, reducing the vortex and reflux of the flow field, as well as the risk of thrombosis. [ABSTRACT FROM AUTHOR]

As unconventional oil and gas receive more and more attention, scholars pay more and more attention to waterless fracturing technology. Among them, carbon dioxide fracturing technology, as the main representative of waterless fracturing technology, has unique advantages and broad application prospects in the development of unconventional oil and gas reservoirs. However, when using carbon dioxide fracturing fluid for construction, carbon dioxide is greatly affected by temperature and pressure, so it is necessary to simulate the temperature and pressure in the wellbore during carbon dioxide fracturing construction. In this article, the basic physical properties of carbon dioxide under different temperatures and pressures are analyzed, and the changes of wellbore temperature and pressure during carbon dioxide fracturing are studied based on the generalized heat conduction theory. The results show that the faster the injection rate of CO2 fracturing fluid at the wellhead, the lower the bottom hole temperature and the higher the bottom hole pressure. However, the higher the wellhead injection temperature, the higher the bottom hole temperature, and the lower the bottom hole pressure. [ABSTRACT FROM AUTHOR]

Managed pressure cementing (MPC) is a new technology based on managed pressure drilling, which has a greater advantage in facing narrow density window formations. However, the existing pressure prediction models during MPC injection stage consider fewer factors and have lower accuracy. To this end, combined with the characteristics of the injection stage, a predictive model of the distribution of annular fluid type was first proposed. Then, based on the experimental results, fluid density and rheology as a function of temperature and pressure were fitted. The governing equation of temperature‐pressure field was established. Eventually the fluid performance parameters–temperature–pressure coupling prediction model was developed in this paper. By comparing the predicted pump pressure with the measured pump pressure, the maximum relative error is not more than 10%. Using this model, the fluid type distribution, temperature field distribution, and pressure field distribution were investigated. The results indicated that the distribution of fluid types in the wellbore presented a complex variation, with up to 10 fluids in the casing and up to five fluids in the annulus. The trend of temperature field is complex, with three turning points. The larger the formation temperature gradient, the higher the fluid temperature in the annulus. The influence law of fluid heat conduction coefficient is reversed at 6750 m. Decreasing drilling fluid density will trigger gas channeling, while increasing drilling fluid density will increase the risk of fracturing formation, and safe operation can be realized by MPC. The variation of the static pressure in the casing is more complicated than in the annulus and the annular circulation pressure in the eccentric casing is smaller than that of the concentric casing, which is due to the smaller annular friction pressure. This study can provide a theoretical basis for the prediction of hydrodynamic parameters during the MPC injection stage. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The volume of the discharge chamber has a great influence on the pressure field in the water filling it and on the efficiency of many technological processes; therefore, the study of the relationship between the volume of the chamber and the pressure in it is an urgent task. However, at present, the role of the volume of the discharge chamber in the formation of the pressure field in it has been insufficiently studied. The purpose of this work is to fill the gap. The study was carried out on the basis of a previously developed mathematical model of an electric discharge in water, the adequacy of which was substantiated via a comparison of the simulation results with experimental data. It is determined that the closed volume of the discharge chamber with rigid walls significantly affects the formation of the pressure field in the water filling it. In this case, the interaction of waves reflected from the walls of the discharge chamber with the surface of the discharge channel in water and the vapor-gas cavity is of decisive importance. The reflected waves determine the period and amplitude of the pulsation of the discharge channel and the vapor-gas cavity, thereby influencing the electrical characteristics of the discharge. This influence increases with decreasing the chamber volume. [ABSTRACT FROM AUTHOR]

A study has been made of the pressure and velocity fields of filtration flows appearing in extracting hydrocarbons from sands penetrated imperfectly. The problem on the pressure field has been presented in which account is taken of two factors of imperfection of perforation: the first is in the presence of a virgin portion in the perforation interval, and the second is caused by the noncoincidence of the perforation interval with the boundaries of a permeable saturated stratum. A finite-difference program has been created for calculating velocity and pressure fields in a stratum with imperfect penetration. Numerical experiment demonstrates that the inflow from imperfectly penetrated layers of a homogeneous isotropic stratum is not uniform, and the modulus of the horizontal velocity components peaks on the boundaries of penetrated layers. [ABSTRACT FROM AUTHOR]

In order to study the effect of pressure field characteristics on the lubrication and sealing of a heavy-haul locomotive gearbox, a simulation model of the gearbox internal pressure field is established by considering the sealing structure at the vent based on the computational fluid dynamics and the lattice Boltzmann method. Then the simulated results extracted at the vent are compared with the test data to verify the correctness of the simulation model. At last, the influence law of different factors on the gearbox internal pressure field is studied with this validated simulation model. The results show that the gear speed and gear steering have a great effect on the internal pressure field of the gearbox. The absolute values of the mean pressure difference or the mean values of the pressure at all the monitoring points are positively and nonlinearly correlated with the gear speed. The change of the gear steering will change the pressure difference between the upper and lower points of the gear meshing area. The pressure difference is larger when the gear rotates forward, and the gear steering also has a great impact on the pressure of other monitoring points. However, the immersion depth of the driven gear and the lubricating oil temperature (dynamic viscosity) have little effect on the gearbox internal pressure field. It can provide a theoretical basis for the operation and maintenance of the locomotive and the rational allocation of the lubricating oil.

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A mathematical model of pressure and velocity fields resulting from the inflow of hydrocarbons to a well of finite radius from partially penetrated reservoir beds has been presented. It is assumed that two-dimensional flow initiated by an assigned depression in an imperfectly penetrated stratum is axisymmetric. A mathematical formulation of the problem in cylindrical geometry on the pressure field in an isolated isotropic homogeneous stratum whose boundaries do not coincide with the boundary points of a perforation interval has been given. A finite-diff erence model has been described on whose basis a program was made up for calculation of pressure and velocity fields in the stratum and computational experiments were consducted which allowed identifying new regularities of flow of practical importance that arise in actual oil and gas reservoirs. Space–time dependences of the pressure field in an oil and gas stratum and of the radial components and modulus of filtration velocity of hydrocarbons have been shown, which illustrate the distinctive features of two-dimensional flow with imperfect penetration of the stratum and basic differences from the well-studied case of plane radial onedimensional flow to the well of finite radius. Based on an analysis of the contour lines, new physical regularities of the flow have been identified that are associated with incomplete perforation of the thickness of the reservoir bed. By the numerical experiments, it has been established that in axisymmetric flow in the stratum, vertical flows inevitably arise which vanish at exit from the stratum into the well. It has been confirmed that in homogeneous incompletely penetrated reservoirs, intralayer crossflows arise in the near wellbore zone, and the radial component of filtration velocity in two-dimensional axisymmetric flow in the imperfectly homogeneous isotropic stratum depends on the vertical coordinate. This means that the inflow to the well is not uniformly distributed over the stratum thickness, and the modulus of the horizontal velocity component in all the curves peaks on the boundaries of the perforation interval. In the case of two-dimensional flow at the center of the perforation interval equally distant from the upper and lower boundaries of the oil and gas stratum, a minimum specific inflow is observed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The centrifugal screw-type pump is a type of pump which, due to its hydraulic and mechanical properties, is used in several areas of the industry (e.g., for sludge and rainwater disposal). To avoid impeller passage clogging, the 3D impeller geometry is designed as a helically curved blade added to a conical hub. The passability through the fluid canal of the modelled impeller is 100 mm. In this paper, the magnitude of the radial force on an impeller blade is investigated as a function of the flow rate. The digital model was designed in Catia V5 and calculated using the commercial Ansys CFX software. A numerical computational fluid dynamics (CFD) method was used to investigate the performance characteristics of the pump, specifically discussing internal flow conditions such as velocity, pressure and the radial force mentioned above.

The authors have proposed an analytical-numerical model of filtration in a producing stratum with a horizontal fracture, that is based on the solution of a quasi-stationary problem on the filtration pressure field in a dominantvertical-permeability anisotropic porous medium divided by a disk hydrofracturing region. On the boundaries separating the fracture from the surrounding rocks, piezoconductivity equations were supplemented with conjugation conditions. The problem has been solved in a zero asymptotic approximation in the Laplace–Carson transform space. Inversion of the formulas was performed with the Iseger numerical algorithm. Results of the computational experiment have been given. It has been shown that the greatest influence of the location of the fracture on the pressure field is observed in the case where it is on one boundary of the producing bed, and from an instant of time, the location of the fissure ceases to exert an influence on the pressure field in the fracture. On the calculated pressure curves, stabilization is observed which is analogous to the existing logarithmic model for the case of a homogeneous stratum. The authors have investigated the space-time dependence of the pressure perturbation across the thickness of the bed in which hydraulic fracturing was implemented. It has been shown that the pressure difference between each point of the vertical cross section and the bottom (top) grows at small values of time. Subsequently, the pressure difference peaks and the growth is replaced by a drop. A regularity has been noted that implies that the rate of growth in the pressure difference between the fracture and the stratum′s bottom is much higher than that of drop. [ABSTRACT FROM AUTHOR]

The pressure fields generated by two simultaneous discharges have not been investigated on any notable scale for the electrohydraulic impulse forming method. In this study, the synchronicity of two discharges is ensured by the sequential connection of two wires mounted in two spark gaps in a common volume of liquid. The objective is to experimentally confirm the equilibrium of the energies evolved in two spark gaps by means of pressure measurements. In addition, multipoint membrane pressure gauges demonstrated the feasibility of easily recording detailed pressure maps. Based on the membrane deformation mechanism and material strengthening under static and impulse conditions, the processing procedure is further developed so as to achieve better accuracy in the determination of pressure field parameters. The practical equality of the pressure fields on the left and right halves of the flat-loaded area confirms the equality of energies evolved in the two spark gaps. The direct shock waves create zones with the most intensive loading. These results provide a basis for the development of new electrohydraulic technologies involving the application of two simultaneous discharges with equal energy and pressure parameters. [ABSTRACT FROM AUTHOR]

The pressure field distribution of a ballistic shock wave (BSW) therapy device is a crucial factor for clarifying its treatment mechanism. We developed a lattice Boltzmann model (LBM) to describe the propagation of BSW. Based on the assumption that the propagation of BSW causes weak compressible flow, our simulaton was performed by coupling Tait equation of state. For a two-dimensional LBM, we used the density initial condition for initial turbulent region near the applicator. We first compared our simulation results with previous experimental measurements. Then we predicted the temporal and spatial distribution of pressure field. The pressure field of ballistic shock wave has a primary compressive region followed by a primary expansive region with the other disturbances. A secondary pressure pulse consists of a positive phase followed by a negative phase. Our results agree well with previous experimental data and provide additional data on the pressure field of BSW. Our model encourages further investigation to clear the biological mechanism of BSW therapy and to design more effective device. [ABSTRACT FROM AUTHOR]

The centrifugal screw-type pump is a type of pump which, due to its hydraulic and mechanical properties, is used in several areas of the industry (e.g., for sludge and rainwater disposal). To avoid impeller passage clogging, the 3D impeller geometry is designed as a helically curved blade added to a conical hub. The passability through the fluid canal of the modelled impeller is 100 mm. In this paper, the magnitude of the radial force on an impeller blade is investigated as a function of the flow rate. The digital model was designed in Catia V5 and calculated using the commercial Ansys CFX software. A numerical computational fluid dynamics (CFD) method was used to investigate the performance characteristics of the pump, specifically discussing internal flow conditions such as velocity, pressure and the radial force mentioned above. [ABSTRACT FROM AUTHOR]

The use of hyperbolic paraboloid roofing (HPRs) is increasingly common in contemporary architecture, especially for buildings with large spans, making use of tensile structures or light shells. These structures are very sensitive to wind loads because of their light weight. In particular, they tend to oscillate under wind action, generating complex pressure distributions and cable instability. Therefore, for this shape structure, the investigation of wind-pressure coefficients correlations plays a relevant role in the design of structural elements. Therefore, based on wind tunnel tests, this paper investigates the behavior of four rectangular low-rise building models with HPR when immersed in a turbulent boundary layer flow. The test results were synthesized in correlation maps of the pressure coefficients. The results were evaluated as functions of different model heights and curvatures, and considering three different angles of wind incidence (0°, 45°, and 90°). [ABSTRACT FROM AUTHOR]

• The role of efficient physical field in processing of flowers was reviewed. • The principles, advantages and limitations of various technologies were summarized. • Physical field processing minimizes the impact on the quality of edible flowers. • Hybrid techniques overcome the limitations of a single technique. • The industrialized application of physical fields needs to be further enhanced. Edible flowers are an exotic part of the human diet due to their distinct sensorial properties and health benefits. Due to consumers demand edible flowers and their products with natural freshness and high nutritional value, there is increasing research on the application of green and efficient edible flower processing technologies. This paper reviews the application of a number of physical fields including ultrasound, microwave, infrared, ultraviolet, ionizing radiation, pulse electric field, high hydrostatic pressure, and reduced pressure aiming to improve the processing and product quality of edible flowers. The mechanism of action, influencing factors, and status on application of each physical energy field are critically evaluated. In addition, the advantages and disadvantages of each of these energy fields are evaluated, and trends on their future prospects are highlighted. Future research is expected to focus on gaining greater understanding of the mechanism action of physical field-based technologies when applied to processing of edible flowers and to provide the basis for broaden the application of physical field-based technologies in industrial realm. [ABSTRACT FROM AUTHOR]

A co-current gas-liquid vortex separator (C-GLVS) with a built-in closure hood is proposed to improve the separation efficiency. The internal flow field and separation performance are investigated with respect to different operating conditions by cold modeling experiments. The C-GLVS is divided into three zones, i.e., the separating zone, the discharging zone, and the settling zone. The lowest static pressure and the highest tangential velocity are observed in the separating zone. Furthermore, A swirling gas stream (r/R = 0.75–1) around the bottom of the closure hood prevents the droplets entrainment flowing upward from the wall area, which is believed to be benefit to gas-liquid separation. Experimental results also show that the introduction of the closure hood enables the gas-liquid separation efficiency of C-GLVS to achieve 98.6%, which is about 22.76% higher than that of GLVS. The pressure drop of the gas discharging accounts for about 60% of the total pressure drop. [Display omitted] • Flow field and separation performance of a co-current gas-liquid vortex separator (C-GLVS) are experimentally investigated. • Gas flow trajectory inside C-GLVS is plotted. • The introduction of a closure hood eliminates small droplets escaping in GLVS and improves the separation efficiency. • Effect of the percentage of segmented pressure drop in C-GLVS is investigated. [ABSTRACT FROM AUTHOR]

The remaining oil distribution in heavy oil reservoir with the unconsolidated sandstone before and after infilling of the inverted nine-spot well pattern was complicated. To better understand the variation of flow field and remaining oil distribution of inverted nine-sport pattern and infill well pattern, the physical experiments were examined using a three-dimensional physical model. The physical simulation experiment of water displacing oil was conducted with the self-developed high pressure–temperature experiment device. For inverted nine-sport pattern, the remaining oil was distributed in the area between injection-production wells and edge region on a flat surface. In vertical, the remaining oil was distributed in the top area of composite reverse and positive rhythm reservoir and in the middle area of composite positive and reverse rhythm reservoir. For infill well pattern, the remaining oil was distributed in the area between production wells on a flat surface. In vertical, the remaining oil was distributed in the area of poor physical property with weak water flooding. Simultaneously, the enhanced recovery efficiency was about 11% by transforming the inverted nine-sport pattern into row injection-production well pattern and the final recovery efficiency was 27.27%. The results can provide reference for tapping the remaining oil and recovery calibration of unconsolidated sand heavy oil reservoir. [ABSTRACT FROM AUTHOR]

This paper studied the air film pressure field (AFPF) characteristics of aerostatic thrust bearing, in which we proposed the measurement equipment for the 2D AFPF and successfully verified the theoretical simulation results. The experimental results agreed well with the theoretical results. However, in the area between the distribution circle of orifice to the air film outlet boundary, the experimental air film pressure (AFP) was slightly higher than the theoretical one. While for the area between the distribution circle of orifice and the center of the bearing, it showed the opposite law. Besides, the increase ratio of the AFP was close to that of the external load with its increase. [ABSTRACT FROM AUTHOR]

Copyright of Advanced Textile Technology is the property of Zhejiang Sci-Tech University Magazines and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Acquisition of an instantaneous pressure field in a flow field is essential for experimental fluid dynamics research because pressure is associated with various flow phenomena. Machine learning has performed well in various fluid mechanics studies in recent years due to its nonlinearity. In this paper, we use the machine learning method to predict the pressure fields from incomplete velocity fields while reconstructing the missing velocity information, as exemplified by the stationary circular cylinder flow and circular cylinder undergoing forced oscillating problems, in which the incompleteness of the velocity field is caused by the optical path occlusion in experiments. We propose a network model based on convolutional neural networks. The experimental results show that the error of machine learning methods is around 4%, and even if the resolution of the training set is reduced, it does not affect the prediction accuracy of the network. For statistical averaging of prediction results, the network has high accuracy in predicting first-order quantities, but its ability to predict second-order quantities is limited. We also explore the effects of the amount of noise on the performance of networks. When applying the model to the forced oscillating cylinder problem, we use transfer learning to train the network given the similarity of the two problems, and the training error yields faster convergence and more minor convergence results. In addition to this, we use flow field data with a single vibration frequency to construct a single dataset, and flow field data with multiple vibration frequencies to construct a mixed dataset, and study the effect of different datasets on the prediction accuracy, which shows that it is difficult for neural networks to achieve both accuracy and generalization. • A deep neural network was constructed to predict the pressure field directly from the velocity field. • The model can reconstruct the missing velocity information while predicting the pressure field. • The model can be transferred from a circular cylinder flow to a forced oscillating circular cylinder flow. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing is the most prominently used technique for increasing well productivity in shale oil reservoirs. Therefore, studying the method for optimizing fracture parameters is essential in the development of shale oil. This study established a mathematical model of non-Darcy flow in the fractured horizontal well section of a shale oil reservoir which considered the influence of the threshold pressure gradient. The finite element method was used to solve the problem, and the calculation method of pressure field and productivity was given. This model is used to study the optimal number of clusters, optimal cluster spacing, optimal fracture length, and optimal fracture conductivity in a horizontal well section. Simulation shows that the optimal number of clusters in a horizontal well section is five when the permeability is 0.02 × 10–3 μm2–∼0.10 × 10–3 μm2, and the optimal number is four when the permeability range is 0.15 × 10–3 μm2–∼0.30 × 10–3 μm2. With the increase in the number of clusters, the stimulation effect is more sufficient, the interference effect between fractures is enhanced, and the loss of stratum energy is accelerated. The optimal cluster spacing is 30 m. Several cases of non-uniform cluster spacing have little effect on the stimulation effect. The cluster number and the sum of the cluster spacing are the determinant factors affecting the stimulation effect. The optimal fracture half-length is 140 m. Several cases of the non-uniform fracture length have little effect on the stimulation effect. The cluster number and the sum of the length of the fracture are the determinant factors affecting the stimulation effect. The optimal conductivity is 20 D•cm. At last, it proposed a fracture parameter optimization method considering the stratum energy loss and productivity.

The shallow thick coal seam in the western mine area in China usually adopts the extraction ventilation method. The surface air leakage makes the wind flow disorderly, and the oxygen of the air penetrates the goaf and interacts with the residual coal in goaf to oxidize the coal. Therefore, the coal spontaneous combustion is likely to occur, and the harmful gas such as carbon monoxide exceeds the standard, causing seriously effects on the normal mining of the mine. At present, field measurements, theoretical analysis and experimental research methods are generally used to analyze the gas concentration field and temperature field of coal spontaneous combustion in goaf caused by surface air leakage. However, the spontaneous combustion experiment of surface air leakage is relatively complex. It is difficult to use theoretical analysis and experimental research methods to obtain the influence law of surface air leakage on coal spontaneous combustion in goaf from a three-dimensional perspective.In order to solve the above problems, according to the characteristics of shallow thick coal seam in northwest China, a three-dimensional numerical calculation model is established. Combined numerical simulation and field measurement methods are used to analyze the distribution of 'three zones' in the surface air leakage goaf area of shallow thick coal seam. The methods also analyze the distribution law of O2 concentration field, CO concentration field, temperature field and pressure field in goaf under different working conditions. Moreover, the field validation is carried out by the ZD5 coal mine fire multi-parameter monitoring device. The results show that the distribution of the 'three zones' and the O2 concentration field in goaf are greatly affected by the surface air leakage. It is found that O2 is easily accumulated at the top of the goaf, which changes the gas flow field distribution in goaf. The concentration range of high volume fraction O2 (volume fraction 18%-23%) in goaf is 0-270 m along the strike direction of the goaf and 3-20 m along the vertical direction of the goaf. In particular, O2 is sufficient in the range of 0-80 m along the strike direction of the goaf and 3-8 m along the vertical direction of the goaf. In this area, there is a certain amount of residual coal and heat is not easily dissipated, raising the risk of coal spontaneous combustion. The pressure at the corner of return air roadway in goaf is the smallest, -10 Pa, the pressure at the return air roadway outlet is the lowest, and the pressure at the air inlet is the highest. The pressure gradually increases along the inclined direction, the vertical direction and the strike direction. The temperature distribution is similar to the CO distribution in goaf. The goaf floor is little affected by the air leakage from the surface, but largely affected by the corner of the intake air roadway of the working face. The heat accumulation and CO accumulation are basically the same as the situation of no air leakage. From the middle of the goaf, the temperature and CO are mainly affected by the surface air leakage, presenting an 'O' ring distribution. At the top of the goaf,the temperature and CO reach maximum values at the junction of each fracture zone and the goaf, then decrease along both sides. The maximum value appears at the junction of the deepest fracture zone and the goaf.

The utilization of nitrogen for enhanced coalbed methane technique offers a promising solution to tackle the greenhouse effect, energy crisis, and coal mine accidents. In this research, a gas flooding experiment utilizing COMSOL 6.1 software was performed. The outcomes demonstrated that the concentration of gas, rate of gas flow, and permeability at a specific moment were directly proportional to the pressure of gas injection. Nonetheless, the pressure of nitrogen decreased as the distance of gas injection increased. Throughout the simulation, the coal displayed two distinct stages of elasticity and plasticity, with the gradual increment of equivalent stress due to continuous gas injection. Damages occurred in the localized circumferential region of the coal when the maximum tensile stress surpassed 3.5 MPa, which led to the formation of new fractures and facilitated gas leakage. The study uncovered the mechanism of nitrogen injection-enhanced coalbed methane under varying gas injection pressures. Injecting nitrogen into the coal can increase the concentration difference and pressure gradient, resulting in a noticeable equivalent force effect. This enhances methane self-desorption that causes the coal matrix to shrink, and increases the permeability. Conversely, when the pressure at the outlet decreases to atmospheric pressure, the gas driving energy decreases, leading to a reduction in the permeability. The interconnection between pressure, seepage, and stress deformation fields is elucidated. These research discoveries can serve as a valuable resource for practical ventures. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Processing of Materials / Elektronnaya Obrabotka Materialov is the property of Institute of Applied Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The pressure field in the limited volume discharge chambers with deformable walls markedly affects the technological process efficiency of sheet alloys' deformation; therefore, its determination is of great importance. Resulting from the electrical discharge in liquid, which fills the discharge chamber, a cavity is formed in the latter with a higher compressibility than that of the liquid in the chamber. Its pulsations create the field of pressure in the discharge chamber. At present, the role of the gas-vapor cavity is studied slightly as to the formation of the field of pressure in the discharge chamber with a deformable wall. Its definition is the aim of this work. The research is based on the earlier developed mathematical model of the electric discharge in water, which is supplemented in this work with correlations that significantly enhance the calculation precision of the discharge channel resistance and the energy released in it. It was determined that the pulsations of the gas-vapor cavity ensure pressure oscillations in it in a counter-phase with an average pressure in the liquid. They decay slowly in the discharge chamber with rigid walls, whereas the presence of the deformable wall makes the decay of the pressure oscillation to be rapid. In the mathematical model developed earlier, a change in the plasma optical transparency and its substantial effect on the pressure in the cavity as well as the pressure field in the liquid were taken into account. [ABSTRACT FROM AUTHOR]

In this study, a particle image velocimetry (PIV)-based pressure estimation method was investigated, with application to the wave-in-deck loading phenomenon. An experimental study was performed in a two-dimensional wave tank using a fixed deck structure under a focused wave, obtaining local pressures by pressure sensors, global loads by load cells, and instantaneous velocity fields using the PIV measurement technique. The PIV-based pressure estimation method was applied using the Euler equation as the governing equation, and the proper time step for the wave impact pressure was studied using the normalized root-mean-square deviation. The pressure estimation method showed good agreement for the local impact pressure in comparison with the measured pressure by the pressure sensors. However, some differences were observed in the peak pressure due to the limitations of the Euler equation and the sampling rate of the measurement system. Using the estimation method, the pressure fields during wave-in-deck loading were determined in the study, with an analysis of the mechanism of impact and negative pressure occurrence.

As one of the key components of the common rail system, the accuracy of pressure field and velocity field analysis of the common rail pipe is related to the service reliability. In order to obtain the velocity and pressure distribution that difficult to be measured in the experiment, this paper considers using three-dimensional modeling and establishing the three-dimensional model of oil flow in the common rail pipe based on the fluid simulation software, and then obtains the velocity field and pressure field distribution of the common rail pipe through numerical simulation. The cone angle at the nozzle structure of common rail pipe is compared and analyzed. Meanwhile the most appropriate cone angle's processing angle among the commonly used processing cone angles is obtained, which improves the rationality of common rail pipe structure processing. It is great significance to the subsequent rail pressure stabilization analysis of common rail pipe. [ABSTRACT FROM AUTHOR]

In this study, an equation is derived to explicitly solve the pressure Poisson equation (PPE) in the moving particle semiimplicit method. In the derivation, the PPE is discretized by an improved Laplacian model and the incompressible condition is satisfied by establishing a direct relationship between pressure and the known flow information. An improved gradient model is adopted in the method while a repulsive force is used to handle particle clustering. To validate the method, a hydrostatic problem, the impact of two rectangular fluid patches and dam‐breaking flows are simulated. The numerical results are compared with analytical solutions and experimental measurements in terms of free surface, pressure, and velocity. Good agreements in the comparisons are achieved, showing that the method can calculate smooth pressure field and accurate pressure and velocity distributions. [ABSTRACT FROM AUTHOR]

Considering the complicated interactions between temperature, pressure and hydration reaction of cement, a coupled model of temperature and pressure based on hydration kinetics during deep-water well cementing was established. The differential method was used to do the coupled numerical calculation, and the calculation results were compared with experimental and field data to verify the accuracy of the model. When the interactions between temperature, pressure and hydration reaction are considered, the calculation accuracy of the model proposed is within 5.6%, which can meet the engineering requirements. A series of numerical simulation was conducted to find out the variation pattern of temperature, pressure and hydration degree during the cement curing. The research results show that cement temperature increases dramatically as a result of the heat of cement hydration. With the development of cement gel strength, the pore pressure of cement slurry decreases gradually to even lower than the formation pressure, causing gas channeling; the transient temperature and pressure have an impact on the rate of cement hydration reaction, so cement slurry in the deeper part of wellbore has a higher rate of hydration rate as a result of the high temperature and pressure. For well cementing in deep water regions, the low temperature around seabed would slow the rate of cement hydration and thus prolong the cementing cycle.

The use of hyperbolic paraboloid roofing (HPRs) is increasingly common in contemporary architecture, especially for buildings with large spans, making use of tensile structures or light shells. These structures are very sensitive to wind loads because of their light weight. In particular, they tend to oscillate under wind action, generating complex pressure distributions and cable instability. Therefore, for this shape structure, the investigation of wind-pressure coefficients correlations plays a relevant role in the design of structural elements. Therefore, based on wind tunnel tests, this paper investigates the behavior of four rectangular low-rise building models with HPR when immersed in a turbulent boundary layer flow. The test results were synthesized in correlation maps of the pressure coefficients. The results were evaluated as functions of different model heights and curvatures, and considering three different angles of wind incidence (0°, 45°, and 90°).

The scalar and vector potentials of the acceleration field and the pressure field are calculated for the first time for a rotating relativistic uniform system, and the dependence of the potentials on the angular velocity is found. These potentials are compared with the potentials for the non-rotating uniform system that have been found previously. The rotation leads to the appearance of vector potentials, which at each point turn out to be directed along the corresponding linear velocity of rotation. The calculation shows that for rotating stellar objects the contribution to the fields' vector potentials from the proper random motion of particles is small compared to the contribution from rotation and may not be taken into account. From the expression for the pressure field potential, a relativistic formula follows that relates the pressure, mass density, and mean square velocity of the particles. This formula in the limit of low speeds corresponds to the expression for the pressure in molecular kinetic theory. When calculating the potentials, a new method is used that takes into account the potentials of two different bodies, a cylinder and a sphere, for solving the wave equation of rotating system. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Processing of Materials / Elektronnaya Obrabotka Materialov is the property of Institute of Applied Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)