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This paper presents two mechanisms for load cell calibrations. The first technique was to use deadweight to generate the required reference load (Applied load). The second method was to use a pressure piston gauge to generate the required calibration force. In both mechanisms, the setup and procedures are described. For verification the results of these methods were compared with international metrology institute calibration results. It was found that deadweight method is the most accurate and the piston gauge is the most realistic at high force values. [ABSTRACT FROM AUTHOR]

The bimodal transport in the plasma sheet consists of sunward large-scale, coherent, and slow motion of charged particles in the closed-field-line region as well as meso-scale, localized, and transient fast flow bursts. It has been found that these earthward moving bursty bulk flows, also called "bubbles," play a crucial role not only in the transporting mass and energy, but also in resolving the pressure-balance crisis with their integrated effects. In this study, we examine how bubbles can affect the average configuration of the middle and inner plasma sheet using the Inertialized Rice Convection Model (RCM-I). Bubbles are sporadically imposed at 22 Re on the nightside plasma sheet, with optimized parameters that constrain their statistical properties. The consequence of the injection of these series of bubbles is evaluated by comparing against observed statistical results, including plasma moments and magnetic field configuration. Our findings confirm that bursty bulk flows are indispensable elements in the magnetotail plasma sheet. [ABSTRACT FROM AUTHOR]

In this study we use high‐quality convection data from the Electron Drift Instrument on board Cluster to investigate how near‐Earth tail activity affects the average convection pattern in the magnetotail lobes when the interplanetary magnetic field has a dominating east‐west (By) component. Two different proxies have been used to represent different levels of reconnection in the near‐Earth tail: The value of the AL index and the substorm phases identified by the Substorm Onsets and Phases from Indices of the Electrojet algorithm. We find that the convection changes from a dominantly YGSM direction, but opposite in the two hemispheres, to a flow oriented more toward the plasma sheet, as the north‐south component of the convection increases when reconnection enhances in the near Earth tail. This result is consistent with recent observations of the convection in the ionosphere, which suggest that the nightside convection pattern becomes more north‐south symmetric when tail reconnection increases. This is also supported by simultaneous auroral observations from the two hemispheres, which shows that conjugate auroral features become more symmetric during substorm expansion phase. The reduced asymmetry implies that the asymmetric pressure balance in the lobes is altered during periods with strong reconnection in the near‐Earth tail. Key Points: Average lobe convection when IMF By≠0 is more north‐south aligned for high |AL| compared to low |AL|Average lobe convection when IMF By≠0 is more north‐south aligned during substorms compared to nonsubstorm intervalsThe more north‐south aligned convection implies that enhanced near‐Earth tail reconnection alters the average lobe convection [ABSTRACT FROM AUTHOR]

We describe a new method of constructing an equilibrium magnetopause surface based on the pressure balance between external and internal pressure sources. Details are given for every step of the procedure, including the initial pressure balance condition (which determines magnetopause morphology), the related underlying assumptions, and the final optimized magnetopause surface. Our method produces a final equilibrium magnetopause surface that satisfies the local balance between the solar wind dynamic pressure and planetary magnetic pressure with an error no greater than 1%. We also discuss the contribution of hot plasma pressure and equatorial ring currents and their effects on magnetopause morphology. For each optimized magnetopause boundary, we give coefficients for fitted polynomial approximations to allow simple and accurate reproductions for practical applications. We specifically discuss the potential application to the modeling of Saturn's magnetopause and describe how the equilibrium magnetopause model can be used to estimate the compressibility of the boundary. Key Points: We construct a reference model of a planetary magnetopause based on pressure equilibriumWe explain how the model provides realistic boundary features produced by the assumed structure of the magnetic field inside the boundaryWe describe cases of a pure dipole field, pure dipole field plus plasma pressure, and dipole plus plasma pressure and ring currents [ABSTRACT FROM AUTHOR]

Spontaneous combustion of coal is one of the major hazards threatening production safety during longwall mining. Mining-induced voids, which provide passages for air leakage, are the key factor triggering spontaneous combustion of coal in longwall goafs. In this study, a comprehensive method, which combined pressure balance, grouting injection, and filling fissures, was proposed to prevent spontaneous combustion of coal in longwall goafs with complex air leakage. Field engineering practice was carried out in Sitai Coal Mine in China. The results demonstrated that with the application of the proposed method, in the working face, the concentration of CO was decreased from 31ppm to 0 and the air leakage quantity was decreased from 261 to below 80 m3min-1. The gas samples analysis from the gob areas also indicated that concentrations of O2 and CO were successively decreased, indicating that the risk of spontaneous combustion of coal in goafs was eliminated. The above mentioned analysis indicates that, the method proposed in this study is useful and efficient. Successful application of this technology could provide reference for the treatment of other coal mines. [ABSTRACT FROM AUTHOR]

Collisionless shocks are ubiquitous throughout the known universe. They mainly convert the energy of the directed ion flow into heating. Upon crossing the shock front, the ion distribution becomes nongyrotropic. Relaxation to gyrotropy then occurs mainly via kinematic collisionless gyrophase mixing and interaction with waves. The theory of collisionless relaxation predicts that the downstream pressure of each ion species varies quasi‐periodically with the distance from the shock transition layer and the amplitude of the variations gradually decrease. The oscillations due to each species have their own spatial period and damping scale. Pressure balance requires that the variations in the total plasma pressure should cause anticorrelating variations in the magnetic pressure. This process should occur at all Mach numbers, but its observation is difficult at moderate‐/high‐Mach numbers. In contrast, such magnetic oscillations have been observed at low Mach number cases of the Venusian bow shock and interplanetary shocks. In this paper, simultaneous in situ magnetic field and plasma measurements from the THEMIS‐B and THEMIS‐C spacecraft are used to study, for the first time, the anticorrelated total ion and magnetic pressure spatial variations at low‐Mach number shocks. It is found that kinematic collisionless relaxation is the dominant process in the formation of the downstream ion distribution and in shaping the downstream magnetic profile of the observed shocks, confirming fundamental theoretical results. Comparison with the results from numerical models allows the role of the different ion species to be investigated and confirms the role heavy ions play in forming the downstream magnetic profile. Key Points: The first correlative analysis of simultaneous measurements of the magnetic field and plasma at shocks near to the Earth is presentedThe first direct observational confirmation of kinematic collisionless relaxation is presentedA clear separation of the contribution of protons and of alpha particles is found [ABSTRACT FROM AUTHOR]

The behavioural properties of excavated ground have significant influence on the excavation process performed by an Earth Pressure Balance Machine (EPBM), as they are among the main factors responsible for maintaining the pressure ahead of the face, which affects face stability. Therefore, understanding the characteristics of the excavated material along with its flow behaviour is essential for a successful EPB tunnel drive. In scenarios involving the excavation of fine-grained soils containing clay minerals, the consistency index has been widely used as a guideline to define the ideal state of the excavated material. However, there are certain restrictions for the use of this index, the first of which are the Atterberg limits. These limits become more restrictive when mixed soils are involved. This study presents a brief review of the application of the consistency index and Atterberg limits in order to predict the performance of an EPB excavation. This study presents the results of a laboratory testing campaign with artificially mixed clay-sand soils by using a flow table as a preliminary flow assessment of cohesive soils. [ABSTRACT FROM AUTHOR]

By utilizing the improved split Hopkinson pressure bar (SHPB) test device, uniaxial, constant-speed cyclic, and variable-speed cyclic impact compression tests were conducted on weakly weathered granite samples. By combining nuclear magnetic resonance (NMR) and triaxial seepage tests, this study investigated the change laws in the mechanical properties, porosity evolution, and permeability coefficients of the samples under cyclic impacts. The results showed that in constant-speed cyclic impacts with increasing impact times, deformation modulus decreased, whilst porosity firstly decreased and then increased. Furthermore, dynamic peak strength firstly increased and then decreased whereas peak strain constantly increased before failure of the samples. In the variable-speed cyclic impacts, as impact times increased, deformation modulus firstly increased and then declined with damage occurring after four impact times. The compaction process weakened and even disappeared with increasing initial porosity. Three types of pores were found in the samples that changed in multiscale under cyclic loading. In general, small pores extended to medium- and large-sized pores. After three variable-speed cyclic impacts, the porosity of the samples was larger than the initial porosity and the permeability coefficient was greater than its initial value. The results demonstrate that the purpose of enhancing permeability and keeping the ore body stable can be achieved by conducting three variable-speed cyclic impacts on the samples. [ABSTRACT FROM AUTHOR]

In this study, failure analysis of piston which belongs to primary standard pressure balance unit is investigated. The strength analyses of the piston were carried out analytically, considering the work-loading conditions. All the analyses were conducted in line with the fundamental strength theories using the finite element method. The material analyses were performed by EDX spectrometer, and fracture surfaces were investigated under scanning electron microscope. Findings revealed that the piston was designed appropriately and the material selection for compression loading was made correctly. Results also showed that fracture could have occurred under small bending, torsion or the combined bending/torsion loadings. Viewed together, although the piston manufactured from WC-Co was designed appropriately for compression loading, the fracture occurred due to external torsion loading. [ABSTRACT FROM AUTHOR]

Highlights • First study of step-by-step methodology in design of LSCFB through CFD approach. • First study on the operational stability/instability analysis through CFD approach in LSCFB. • Helpful for analysis of geometrical and operating design variables for application. Abstract In this work, a systematic step-by-step methodology has been developed to identify the type of instabilities arise in achieving the continuous solids circulation achieved between riser and downcomer, and in establishing the proper pressure balance among the various units of a liquid–solid circulating fluidized bed (LSCFB) using transient three dimensional computational fluid dynamic (CFD) simulations. Different type of instabilities has been identified and systematically eliminated by choosing the appropriate measure in-terms of the geometry of a LSCFB. This resulted in studying five variant designs of LSCFB studies using CFD. The Eulerian–Eulerian approach is used to simulate the two-phase flow in LSCFB system. The hydrodynamic behavior of the system is studied in terms of the pressure drop, solids holdup at various locations as well as the axial solids hold up distribution. The steady state in the system has been characterized by the solids volume fraction and the pressure balance loop across the closed loop LSCFB. The effect of solids inventory, primary and auxiliary liquid flow, and viscosity of liquid on average solids holdup has been studied with the final LSCFB design. [ABSTRACT FROM AUTHOR]

Many things, such as tilt effect of the piston and cylinder assembly (PCA), temperature, air buoyancy, etc., significantly affect pressure measurement results when using a pressure balance in a high-pressure measurement environment. These effects can not only increase the uncertainty of the effective area determination but also cause problems in the performance of the pressure balance. Among the above effects, the tilt of the PCA is one of the significant uncertainty sources to be considered in the calibration. In the case of two pressure balances that have exchangeable PCAs, most uncertainty sources could be eliminated by exchanging two PCAs and averaging two calibration results because symmetric behaviors can be theoretically obtained. To investigate the above effects, an oil-operated pressure balance was used to calibrate another identical pressure balance with an exchangeable PCA up to 500 MPa. Before the calibration, the vertical condition of the PCA close to the gravitational axis was determined using a precise pressure gauge by calibrating it according to the tilt angle of the pressure balance. In the case of a marginal tilt angle of the PCA, the calibration results of a cross-float method before and after exchanging two PCAs, had symmetric behaviors, but they did not follow a cosine effect. The results could be dependent on pressure, piston materials, and PCA adoption methods. In conclusion, the distortion coefficient could be changed due to the tilt since the central piston axis is not coincident with one of the cylinder anymore. [ABSTRACT FROM AUTHOR]

Some salts have been recently shown to decrease the sum frequency generation (SFG) intensity of the hydrogen-bonded water molecules, but a quantitative explanation is still awaited. Here, we report a similar trend for the chloride salts of monovalent cations, that is, LiCl, NaCl, and CsCl, at low concentrations. Specifically, we revealed not only the specific adsorption of cations at the water surface but also the concentration-dependent effect of ions on the SFG response of the interfacial water molecules. Our thin-film pressure balance (TFPB) measurements (stabilized by 10 mM of methyl isobutyl carbinol) enabled the determination of the surface potential that governs the surface electric field affecting interfacial water dipoles. The use of the special alcohol also enabled us to identify a remarkable specific screening effect of cations on the surface potential. We explained the concentration dependency by considering the direct ion-water interactions and water reorientation under the influence of surface electric field as the two main contributors to the overall SFG signal of the hydrogen-bonded water molecules. Although the former was dominant only at the low-concentration range, the effect of the latter intensified with increasing salt concentration, leading to the recovery of the band intensity at medium concentrations. We discussed the likelihood of a correlation between the effect of ions on reorientation dynamics of water molecules and the broad-band intensity drop in the SFG spectra of salt solutions. We proposed a mechanism for the cation-specific effect through the formation of an ionic capacitance at the solution surface. It explains how cations could impart the ion specificity while they are traditionally believed to be repelled from the interfacial region. The electrical potential of this capacitance varies with the charge separation and ion density at the interface. The charge separation being controlled by the polarizability difference between anions and cations was identified using the SFG response of the interfacial water molecules as an indirect probe. The ion density being affected by the absolute polarizability of ions was tracked through the measurement of the surface potentials and Debye-Hückel lengths using the TFPB technique. [ABSTRACT FROM AUTHOR]

Particle separation in microfluidic devices is a common problematic for sample preparation in biology. Deterministic lateral displacement (DLD) is efficiently implemented as a size-based fractionation technique to separate two populations of particles around a specific size. However, real biological samples contain components of many different sizes and a single DLD separation step is not sufficient to purify these complex samples. When connecting several DLD modules in series, pressure balancing at the DLD outlets of each step becomes critical to ensure an optimal separation efficiency. A generic microfluidic platform is presented in this paper to optimize pressure balancing, when DLD separation is connected either to another DLD module or to a different microfluidic function. This is made possible by generating droplets at T-junctions connected to the DLD outlets. Droplets act as pressure controllers, which perform at the same time the encapsulation of DLD sorted particles and the balance of output pressures. The optimized pressures to apply on DLD modules and on T-junctions are determined by a general model that ensures the equilibrium of the entire platform. The proposed separation platform is completely modular and reconfigurable since the same predictive model applies to any cascaded DLD modules of the droplet-based cartridge. [ABSTRACT FROM AUTHOR]

Aims. The origins and generation mechanisms of the slow solar wind are still unclear. Part of the slow solar wind is populated by number density structures, discrete patches of increased number density that are frozen in to and move with the bulk solar wind. In this paper we aimed to provide the first in-situ statistical study of number density structures in the inner heliosphere. Methods. We reprocessed in-situ ion distribution functions measured by Helios in the inner heliosphere to provide a new reliable set of proton plasma moments for the entire mission. From this new data set we looked for number density structures measured within 0.5AU of the Sun and studied their properties. Results. We identified 140 discrete areas of enhanced number density. The structures occurred exclusively in the slow solar wind and spanned a wide range of length scales from 50Mm to 2000 Mm, which includes smaller scales than have been previously observed. They were also consistently denser and hotter that the surrounding plasma, but had lower magnetic field strengths, and therefore remained in pressure balance. Conclusions. Our observations show that these structures are present in the slow solar wind at a wide range of scales, some of which are too small to be detected by remote sensing instruments. These structures are rare, accounting for only 1% of the slow solar wind measured by Helios, and are not a significant contribution to the mass flux of the solar wind. [ABSTRACT FROM AUTHOR]

To guarantee effective EPB TBM face support and performance, it is necessary to understand the mechanical behavior of foam-conditioned soil under realistic pressure conditions. This paper investigates the behavior of foam-conditioned soil under applied total pressures of up to 5 bar. The study examines the effect of total stress, effective stress, and key soil parameter void ratio on the behavior of foam-conditioned soil. Shear strength and compression tests were carried out in a field-portable pressurized test chamber on two granular soils with a variety of foam parameters. The results demonstrate that void ratio and effective stress are the main factors that influence the performance of foam-conditioned soil. It was determined that a certain ratio of void ratio to maximum void ratio was required to prevent the development of appreciable effective stress and, thus, high shear strength and low compressibility. [ABSTRACT FROM AUTHOR]

Polymer-based micro/nano fluidic devices are becoming increasingly important to biological applications and fluidic control. In this paper, we propose a self-enclosure method for the fabrication of large-area nanochannels without external force by using a capillary-pressure balance mechanism. The melt polymer coated on the nanogrooves fills into the trenches inevitably and the air in the trenches is not excluded but compressed, which leads to an equilibrium state between pressure of the trapped air and capillary force of melt polymer eventually, resulting in the channels' formation. A pressure balance model was proposed to elucidate the unique self-sealing phenomenon and the criteria for the design and construction of sealed channels was discussed. According to the bonding mechanism investigated using the volume of fluid (VOF) simulation and experiments, we can control the dimension of sealed channels by varying the baking condition. This fabrication technique has great potential for low-cost and mass production of polymeric-based micro/nano fluidic devices. [ABSTRACT FROM AUTHOR]

In support of our planar pulsed inductive plasma thruster research, a fast electromagnetic inductive valve for a gas propellant injection system has been built and tested. A new and important design feature is the use of a conical diaphragm as the action part, which greatly contributes to the virtue of simplicity for adopting the resultant force of the diaphragm deformation as the closing force. An optical transmission technique is adopted to measure the opening and closing characters of the valve while the gas throughput is determined by measuring the pressure change per pulse in a test chamber with a capacitance manometer. The experimental results revealed that the delay time before the valve reaction is less than 40 μs, and the valve pulse width is no longer than 160 μs full width at half maximum. The valve delivers 0-2.5 mg of argon gas per pulse varied by adjusting the drive voltage and gas pressure. [ABSTRACT FROM AUTHOR]

Recent experimental and theoretical findings [Shinohara et al., Phys. Plasmas 23, 122108 (2016)] regarding the pressure balance between a cylindrical plasma, an axial magnetic field, and neutral gas are explored further theoretically. The length of the cylinder is assumed much larger than its radius, so that axial losses are small and cross-field transport is dominant. Conditions for either magnetic pressure or neutral pressure balancing the plasma pressure and an associated coupling parameter, which were identified in the above-mentioned recent study, are examined further. In addition, a second coupling parameter is identified which determines which is larger, the relative change in the magnetic field or the relative change in neutral density. An unexpected nonmonotonic variation of the plasma density with the plasma particle flux is demonstrated. It is shown that for plasma beta close to unity, as plasma generation and plasma particle flux increase, the plasma density surprisingly decreases. This decrease follows a decrease in plasma confinement due to an increased plasma diamagnetism. The effect of the magnetic field on neutral depletion is examined. It is shown that an increase in the magnetic field as the plasma density is kept constant results in a decrease in neutral depletion, while an increase in the magnetic field as the plasma particle flux is kept constant results in constant neutral depletion. [ABSTRACT FROM AUTHOR]

Fluid-mineral interaction has an irreversible impact on the fracture permeability evolution in the life span of deep geological reservoirs. To investigate the impact, a preliminary study on water-granite interaction in an undeformable fracture under confining pressure is conducted. A 1-D flow and reactive transport model is therefore developed and validated against the experimental data in Yasuhara et al. (Appl Geochem 26(12):2074-2088, 2011). The model takes free-face dissolution on pore walls as well as enhanced dissolution at asperity contacts into account, together with a nested well-equipped geochemical system. The simulation is implemented by FEM-based simulator OpenGeoSys with a plugin module of IPhreeqc for speciation calculation. After calibration, the predictions of effluent element concentrations are in good agreement with the measurements. The study indicates the high effluent concentrations arise from enhanced mineral dissolution at asperity contacts. Pressure solution at anorthite contacts may not take effect under experimental conditions because of the high-level energy barrier to interpenetration, and Al-bearing secondary minerals such as gibbsite may be formed in the current near-equilibrium aqueous system. The sensitivity analysis suggests that contact area ratio is a paramount parameter in determining the surface reactivity and reactive surface area at contacts. [ABSTRACT FROM AUTHOR]

A three-dimensional adaptive magnetohydrodynamic (MHD) model, SWMF, is used to simulate the interaction between the solar wind and magnetosphere for a particular event on 5 June 1998, and the simulated results of this event is used to investigate the balances of the dynamic, thermal and magnetic pressure along the Sun-Earth line for the different conditions of interplanetary magnetic field (IMF). The conclusions are as follows: (1) outside the magnetopause, the total and thermal pressures are clearly correlated with upstream solar wind dynamic pressure and increase with the solar wind dynamic pressure. In contrast, the magnetic pressure decreases with the increasing intensity of the southward IMF due to the magnetic reconnection and is enhanced with the increasing intensity of the northward IMF due to the magnetic accumulation. It is similar to the variation inside the magnetopause; (2) the solar wind pressure coefficient is larger for the northward IMF than that for the southward IMF, but it has no obvious dependence on the upstream solar wind dynamic pressure; (3) the magnetic field compression ratio just inside the magnetopause is larger and more stable in northward IMF than in southward IMF; and (4) along the Sun-Earth line, the thermal pressure is dominant on the magnetopause in southward IMF, while the magnetic pressure is dominant on the magnetopause in northward IMF. The magnetic reconnection easily occurs for southward IMF, and results in magnetic pressure decreasing just inside the magnetopause. This factor plays a crucial role in the earthward displacement of the Earth's magnetopause for southward IMF. And the increasing of thermal pressure just outside the magnetopause also has contribution to this displacement, especially for lower IMF. [ABSTRACT FROM AUTHOR]

We developed a high gas pressure calibration system that uses a liquid-lubricated (LL) pressure balance as a standard for pressures up to 100 MPa. The LL pressure balance can generate gas or hydraulic pressure by changing the pressure medium. We first evaluate characteristics of the LL piston–cylinder (PC), such as its effective area and fall rate. The effective area of the LL PC is evaluated through comparison with a hydraulic pressure balance. When the LL PC uses a gas, the fall rate is affected by gas dissolution into liquid in the LL PC reservoir. The results of calibrating a pressure gauge under the developed system are consistent with those by an existing hydraulic pressure calibration system. [ABSTRACT FROM AUTHOR]

This paper is a review of our work with Scheludko–Exerowa thin liquid film—pressure balance technique TLF-PBT, the first systematic application of the technique to petroleum systems. New insights were gained in understanding the behavior of petroleum emulsions. We have observed new phenomena in foam films stabilized with sodium naphthenates: long range foam film stratifications and step-wise film thickening at constant capillary pressure. Our modification of TLF-PBT cell allows probing water-in-oil emulsion films with electrical signal, a new technique to study water-in-oil emulsions. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the upper esophageal sphincter (UES) motility in patients with gastroesophageal reflux disease (GERD) as compared to healthy volunteers. We retrospectively studied the HRM tests of 44 patients (median age: 61 years, 54% females) under evaluation for GERD. The manometric UES parameters of these patients were compared to 40 healthy volunteers (median age: 27 years, 50% females). Almost half of the patients had a short and hypotonic UES. Patients with extraesophageal symptoms had a higher proportion of hypotonic UES as compared to patients with esophageal symptoms. Reflux pattern did not influence manometric parameters. Proximal reflux (any number of episodes) was present in 37(84%) patients (median number of proximal episodes = 6).Manometric parameters are similar in the presence or absence of proximal reflux. There is not a correlation between the UES length and UES basal pressure. In conclusion, our results show that: (1) the manometric profile of the UES in patients with GERD is characterized by a short and hypotonic UES in half of the patients; (2) this profile is more pronounced in patients with extraesophageal symptoms; and (3) neither the presence of proximal reflux nor reflux pattern bring a different manometric profile. [ABSTRACT FROM AUTHOR]

Studies were conducted for soil improvement in earth pressure balance (EPB) shield tunneling in sandy cobble strata based on the construction of the Chengdu Metro project in China. The results indicate choice of improver and optimal soil proportions. For mid-density sandy cobble with 8% water content, a slurry injection ratio greater than 25% meets the construction requirements. A mixture of slurry and foam achieves construction efficiency and flow plasticity of soil for a slurry injection ratio of 15% and foam injection ratio of 80-100%. For dense sandy cobble, water content of 7.5-10% and foam injection ratio of approximately 40% - or a slurry injection ratio higher than 10% and foam injection ratio of approximately 30% is desirable. A foaming agent with water is a good improver for mid-density sandy cobble strata tunneling; i.e., soil water content of 8.6-11% and foam injection ratio of 60-100%. For dense sandy cobble strata, a mixture of slurry and foam is suggested as the improver; foam injection ratio of 40-80% and a slurry injection ratio of approximately 10%. [ABSTRACT FROM AUTHOR]

In this paper, a three-dimensional numerical model to study the static and dynamic behaviour of ultra-high performance steel fibre reinforced concrete is developed. Ultra-high performance steel fibre reinforced concrete is assumed to be a two-phase model consisting of concrete matrix and steel fibres. The concrete matrix is modelled with homogeneous material and the straight round steel fibres are assumed to be dispersed with random locations and orientations in the matrix. The interfacial transition zone (ITZ) effect is studied based on the single fibre pull-out tests, and parameters describing the fibre-matrix one dimensional bond-slip behaviour are obtained and discussed based on both experimental and theoretical results. After the three-dimensional model is validated with static split tensile tests, split Hopkinson pressure bar (SHPB) split tensile tests are numerically modelled and the stress-time history is interpreted in the mesoscale level. The proposed model qualitatively and quantitatively predicts the material static and dynamic behaviours, and also gives insights on the fibre reinforcement effect in the concrete matrix. [ABSTRACT FROM AUTHOR]

Traditionally in the field of pressure metrology uncertainty quantification was performed with the use of the Guide to the Uncertainty in Measurement (GUM); however, with the introduction of the GUM Supplement 1 (GS1) the use of Monte Carlo simulations has become an accepted practice for uncertainty analysis in metrology for mathematical models in which the underlying assumptions of the GUM are not valid. Consequently the use of quantile functions was developed as a means to easily summarize and report on uncertainty numerical results that were based on Monte Carlo simulations. In this paper, we considered the case of a piston-cylinder operated pressure balance where the effective area is modelled in terms of a combination of explicit/implicit and linear/non-linear models, and how quantile functions may be applied to analyse results and compare uncertainties from a mixture of GUM and GS1 methodologies. [ABSTRACT FROM AUTHOR]

500MPa pressure is considered as the common maximum pressure in most of the National Metrology Institutes worldwide; however, validation of the uncertainty in that range required a lot of work. NIS when recognized on, 2008 guaranteed big uncertainty value above 200MPa due to the absence of international comparison at that time. This paper summarizes the results of a validation of 500MPa range of hydraulic gauge pressure measurements carried out at NIS. The study covers the calibration through direct comparison and through using of a pressure sensor. The paper summarized the technical work carried out at the results of measurements and the effect of these results on NIS Calibration Measurements Capability. The validation also includes the comparison between the obtained results and pervious calibration of the same piston-cylinder assembly that calibrated against the NIST primary standard. [ABSTRACT FROM AUTHOR]

While swelling and shrinking of multiple emulsions – depending on existing pressure gradients – has been well reported in the literature, little research has been carried out covering the osmotic equilibration between pressure systems caused by interfacial phenomena and phase fractions for multiple emulsions in which either one or both disperse phases exhibit a phase fraction above the maximum packing limit without any deformation of the droplets. In this paper, a model for determining the theoretical equilibrium state regarding osmotic regulation is presented, as well as a new experimental method to determine the disperse phase fraction. This method is employed to compare the measured phase fractions to the theoretical predictions. Using both experimental and theoretical approaches, a direct method is proposed to define the disperse phase fraction and the encapsulation efficiency, yielding potential for a knowledge driven improvement of the production of multiple emulsions. [ABSTRACT FROM AUTHOR]

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The classical Buckley-Leverett theory applies to 1D linear flow of two immiscible phases under the fundamental assumption that the flow rate (or total volumetric flux) is constant as a function of time. One phase is injected into the medium at a constant rate, thereby displacing the other phase. If the displacing phase is instead injected at constant pressure and the outlet pressure is also constant, the problem is still well-defined; however, the classical Buckley-Leverett theory does not apply. This is because the injected phase and the in-situ phase have different properties such as viscosities. If the boundary pressures are kept constant, the flow rate will, therefore, vary over time. The main result of this paper is to show that the solution of the displacement problem can be obtained from the constant-rate solution through an analytical determination of the flow rate as a function of time, given constant- pressure boundaries. The theory developed in this paper also provides an analytical solution for the location of the displacement front at any given time, the time for frontal breakthrough at the outlet end, and the pressure distribution as a function of time inside the medium. It is demonstrated through computed examples that the constant-flow-rate solution, in general, cannot be used to approximate the corresponding solution for constant-pressure boundaries because the variation in the flow rate is very significant. A standard numerical method has also been applied and compared with the analytical solutions, demonstrating that fine numerical-simulation grids are required for acceptable comparison with the analytical solution. [ABSTRACT FROM AUTHOR]

When steam with high velocity is injected into quiescent subcooled water through a sonic nozzle, the phenomenon that the total pressure along central axis at the tail of steam plume can be larger than the total pressure of steam inlet was observed in some experiments, but the reason is not clear till now because of the restriction of experimental method. It is very hard to obtain the static pressure, the velocity of water and steam, as well as the dynamic pressure of steam and water. To reveal the reason, three-dimensional steady simulation was carried out to study stable steam jet in subcooled water. A thermal equilibrium phase change model was inserted into Fluent as a user defined function (UDF) to model the DCC process. After the simulation model being validated, the effect of steam mass flux and water temperature on the shape of steam plume was studied, and the thermal hydraulic behavior along axial direction was investigated. Then the phenomenon that the total pressure at the tail of steam plume can be larger than that of steam inlet was also observed in the simulation result. It was found that the axial locations where the total pressure and the dynamic pressure of water reached the peak were the same, and the locations were all located at the tail of steam plume. The inference that the dynamic pressure of water resulted in the total pressure at the tail of steam plume larger than that of steam inlet was made. The inference was still valid under different steam pressures and water temperatures. Then the reason why the dynamic pressure of water was the largest at the tail of steam plume was also investigated. [ABSTRACT FROM AUTHOR]

Study Aim: To investigate differences in the center of pressure (COP) during gait and single leg stance between subjects with persistent complaints (PC) and without persistent complaints (NPC) after a lateral ankle sprain.Methods: 44 patients who consulted the general practitioner, 6-12 months prior to inclusion, with a lateral ankle sprain were included for the current study purpose. Using a 7-point Likert scale patients were divided into the PC or NPC group. All subjects filled out an online questionnaire, walked along a walkway and performed a single leg stance, both on the RSscan. Primary outcomes included the COP displacement, range and percentage used in mediolateral and anterioposterior direction.Results: There was a trend (p<0.05) towards a more medially COP trajectory during walking at 34-46% and 83-96% and more anteriorly at 21-31% and 91-100% of the stance phase in the PC group compared to NPC group. Additionally, the COP was more laterally located in the sprained leg compared to the non-sprained leg in the PC group in the loading response phase (p<0.05). An interaction was found for the percentage of anterior-posterior range used in single leg stance without vision.Conclusion: The COP trajectory discriminates between patients with PC and NPC. This indicates that roll off during gait might play an important role in the recovery of patients after a lateral ankle sprain and could be used to monitor treatment. [ABSTRACT FROM AUTHOR]

In order to research the pipeline vibration and prevent the fatigue failure of pipeline, the calculation model and methods for vibration characteristics analysis of pipeline under the action of the gas pressure pulsation and pipeline coupling are presented in this paper. According to the pipeline structure, the pipeline model with different pipe diameters is established. Based on the model and combined with the structure parameters of pipeline, the calculation methods of gas column natural frequency, gas pressure pulsation, and exciting force are built. By these ways, the relationships between the gas column natural frequency and orders, the gas pressure pulsation and orders, and the exciting force and aspect ratio are acquired. Besides, the variable relationships of vibration displacement and velocity of pipeline can be obtained. Comparing the calculated results with the field test values, the calculated results are in agreement with the test values, and the correctness of the calculation model and method is verified. The results show that taking the pressure pulsating and pipe coupling effect account into the vibration analysis of different pipe diameters, which can truly reflect the vibration characteristics of pipeline and possess important reference value for preventing fatigue failure and reducing the vibration of the pipeline. [ABSTRACT FROM AUTHOR]

The impingement of a gas jet on a liquid surface in the stable-state regime is analyzed theoretically. We consider the case of the perpendicular jet action. It is found that for describing analytically the processes occurring in this case, it is necessary to employ the balance equation for forces at the interface and not the balance equation for pressures at the lowest point of cavity, which was used in most available publications. Recommendations for experimental studies of a gas jet impinging on a liquid surface are formulated. We report on the results of experiments confirming the correctness of our theoretical analysis and making it possible to determine the empirical value of the shape factor. The experiments were carried out with air and epoxy resin. The cavity formed on the liquid surface had radius R = 1-8 mm and depth h = 0.2-12.5 mm. [ABSTRACT FROM AUTHOR]

For CO2 sequestration and utilization in the shallow reservoirs, reservoir pressure changes are due to the injection rate changing, a leakage event, and brine withdrawal for reservoir pressure balance. The amounts of exsolved CO2 which are influenced by the pressure reduction and the subsequent secondary imbibition process have a significant effect on the stability and capacity of CO2 sequestration and utilization. In this study, exsolution behavior of the CO2 has been studied experimentally using a core flooding system in combination with NMR/MRI equipment. Three series of pressure variation profiles, including depletion followed by imbibitions without or with repressurization and repetitive depletion and repressurization/imbibition cycles, were designed to investigate the exsolution responses for these complex pressure variation profiles. We found that the exsolved CO2 phase preferentially occupies the larger pores and exhibits a uniform spatial distribution. The mobility of CO2 is low during the imbibition process, and the residual trapping ratio is extraordinarily high. During the cyclic pressure variation process, the first cycle has the largest contribution to the amount of exsolved CO2. The low CO2 mobility implies a certain degree of self-sealing during a possible reservoir depletion. [ABSTRACT FROM AUTHOR]

Isobaric heat capacity of pressurized liquid trans-1,3,3,3-tetrafluoropropene [R1234ze(E)] was measured by scanning calorimetry. The experimental system basically consists of a Calvet calorimeter (Setaram C80) and a pressure balance unit. A total of 95 data points were obtained at temperatures from 310.15 to 365.15 K and pressures up to 5.5 MPa. An empirical equation was used to correlate the experimental data with an average absolute percentage deviation of 0.18 %. Besides, a comparison was carried out between present data and literature data and three latest fundamental equations of state. Finally, saturated liquid heat capacity of R1234ze(E) was also investigated in this paper. [ABSTRACT FROM AUTHOR]

In this paper, a super-large diameter earth pressure balance (EPB) shield tunnel crossing below an operating airport in a soft soil region is introduced to investigate the environmental effect of EPB shield tunneling. The new tunnel with a length of 1,862.7 m was constructed using the EPB shield machine with a diameter of 14.27 m. Field tests of 100 tunnel segments tunneling were conducted prior to the construction of the airport area. The distribution of pore water pressure and soil pressure on the excavation surface of the super-large diameter EPB shield and its relationship with the construction parameters are studied. In addition, the influence of the shield construction parameters on the ground movements is investigated by monitoring the surface settlement. The construction control criteria of EPB shield tunneling under the airport is then recommended, including the chamber earth pressure setting, synchronous grouting, advance speed, and stopping excavation. Application and practice show that the large EPB shield tunnel was excavated through the airport smoothly, which means that the proposed control methods contributed to a successful construction. [ABSTRACT FROM AUTHOR]

Based on simulation, the summer upper-ocean cross-isobath's flow on the Northern South China Sea has been analyzed. East to Xisha water, the cross-isobaths flow mainly onshore, including little offshore flows. On Xisha water, the sea water flows onshore on the north side and is reversed on the other side. The momentum balance shows that the along-isobath's barotropic pressure gradient determines the distribution of the cross-isobath flow. Theoretical analysis shows that the along-isobath's density gradient and the windstress curl are two important factors that determine the along-isobath's sea surface height gradient, which is the main contributor to the barotropic pressure gradient. Numerical experiments demonstrate that the temperature distribution dominates the along-isobath's density gradient and determines the along-isobath's sea surface height gradient. [ABSTRACT FROM PUBLISHER]

An example of the application of the Black Foam Film (BFF) Method and the Wetting Film Method, using the Microinterferomertric and the Pressure Balance Techniques, for characterization interfacial properties of the animal derived therapeutic pulmonary surfactant preparations (TSP), is presented. BFF thickness, probability of black film formation, and disjoining pressure for foam films from TSP aqueous solutions are measured as well as the wetting properties of TSP solutions on solid surfaces with different hydrophobicity have been studied. Interfacial characteristics such as minimal surfactant concentration to obtain black film (critical concentration) and concentration at which a black film is 100% obtained (threshold concentration) are determined. An evaluation of the four widely used TSP – Curosurf, Infasurf, Survanta, and Alveofact – by these methods has been carried out. Thus the methods of the thin liquid films are useful tools for studying the interfacial properties of TSP solutions, as well as for their improvement. [ABSTRACT FROM AUTHOR]

A numerical–experimental analysis on a new generation of hydraulically controlled servo solenoid injectors for Euro 6 Diesel engine applications has been carried out. The main innovation of these high-pressure injectors is the replacement of the standard pilot-valve configuration with a pressure-balanced layout. The new setup is aimed at reducing clearance leakages and at improving the dynamic response of the needle to the electrical command. A previously developed advanced one-dimensional code for the simulation of Common Rail injection systems has been adapted to simulate the innovative injectors. In particular, electromagnetic, hydraulic and mechanical submodels have been set up for the pressure-balanced pilot-valve simulation. The validated numerical model of the injector has been applied to investigate the mechanics of the pressure-balanced pilot-valve and the sensitivity of the dynamic response of the needle to some of the innovative pilot-valve layout design parameters. Furthermore, the developed simulation tool has been used to examine the real impact that the replacement of the standard pilot-valve layout with a pressure-balanced one could have on the injected flow-rate performance. The comparative investigation between the standard and the innovative pilot-valve has been completed with an analysis of their experimental static leakages. A comparison has also been made with static leakages measured for hydraulically-controlled servo piezoelectric injectors. Finally, a simple and accurate thermodynamic flow model has been developed to predict static leakages in indirect-acting solenoid and piezoelectric injectors. This model has pointed out the significant dependence of static leakages on temperature and pressure. [ABSTRACT FROM AUTHOR]

The paper presents the construction and operation of a video sensor developed for video-manometer. In the publication the use of video-manometer for measuring gas pressure is presented. A characteristic feature of the device is pressure measurement based on diaphragm deformation and digital image processing. Presented measuring technique eliminates restrictions in the construction of the measuring apparatus arising from non-linear nature of diaphragm deformation. It also allows performing measurements of gas pressure, also of explosive gas, providing galvanic isolation between the factor measured and the measuring device. The paper presents the results of video-manometer calibration and measurements taken during the laboratory tests. It has been shown that the developed video-manometer, that is equipped with a flat silicone diaphragm, allows measuring the gas pressure in the range of 0 - 100 mbar with an error less than 2%. In the experiments the CO2 pressure was measured. [ABSTRACT FROM AUTHOR]

In order to calculate the decompression time of the hypoharic rapid decompression chamber and obtain the reasonable volume parameter, the equilibrium equation of airflow is deduced and reveals the relationship among the time of barometric pressure balance and pipeline conductance, initial pressure, initial pressure difference and chamber volume. With software FLUENT to make a dynamic simulation on the airflow balance process of decompression chamber during the decompressing. Compared with the experiment datum and calculating results of the two methods, it shows the validity of the two models. [ABSTRACT FROM AUTHOR]

Twin tunnels are frequently used to address the increasing transportation demands in large cities. To ensure the safety of twin tunnels in close proximity, it is often necessary to take protective measures that have not been well studied. Field monitoring was conducted for a project of twin earth pressure balance shield (EPBS) tunnels in typical soft ground. The preceding tunnel was reinforced by various measures, including trailer bracing, compensation grouting, artificial freezing and scaffold bracing. The entire deformation of the reinforced tunnel was recorded during the succeeding tunnelling process. A three dimensional finite-element method (FEM) model was established to simulate the entire process of twin EPBS tunnelling, particularly the reinforcement measures. The computed deformations of the reinforced tunnel were consistent with the measured data. Furthermore, the stress history and pore pressure of the surrounding soil were analysed to investigate the deformation mechanism of the tunnel. Both the measured and computed results indicate that although the face pressure of the succeeding tunnel was smaller than the earth pressure at rest, the preceding tunnel could still experience an inward horizontal convergence and a deflection away from the succeeding tunnel. These distortion modes were caused by the squeezing effect of the horizontal soil arch in front of the succeeding tunnel face. Finally, convergence and deflection indices were proposed to quantify and assess the effectiveness of the reinforcement measures. The trailer bracing, as an “in-tunnel” reinforcement technique, was found to be the most effective method for controlling tunnel convergence. However, artificial freezing as an “out-tunnel” reinforcement technique led to the largest reductions in tunnel deflection. A combination of both “in-tunnel” and “out-tunnel” reinforcements was recommended. [ABSTRACT FROM AUTHOR]

The flow of muck and cuttings in the face, cutterhead, cutting chamber, and screw conveyor determines the pressure profile of the excavated soil as well as its impact on the wear of the related components in a soft ground tunneling machine. This paper discusses the use of Computational Fluid Dynamic (CFD) to simulate the flow characteristic of the conditioned soil in the screw conveyor of Earth Pressure Balance (EPB) tunnel boring machine. In this simulation, conditioned soil assumed to behavior as a Bingham plastic fluid. Back analysis method in conjunction with CFD modeling is used to calculate the rheological properties of soil from a set of known screw conveyor torque read outs from a machine operating in Seattle, WA. The error of the torque values between the simulation results and actual field data is in the range of 0.1–6.2%. This illustrate that the CFD method can simulate the soil movement in the screw conveyor of EPB machines. The results also indicates that the same approach can be used to optimize the machine design to minimize torque and wear as well as optimizing machine operating parameters during the tunneling operation to improve productivity and have a better control of the face pressure. [ABSTRACT FROM AUTHOR]

Equilibrium reconstruction consists in identifying, from experimental measurements, a distribution of the plasma current density that satisfies the pressure balance constraint. The LIUQE code adopts a computationally efficient method to solve this problem, based on an iterative solution of the Poisson equation coupled with a linear parametrisation of the plasma current density. This algorithm is unstable against vertical gross motion of the plasma column for elongated shapes and its application to highly shaped plasmas on TCV requires a particular treatment of this instability. TCV's continuous vacuum vessel has a low resistance designed to enhance passive stabilisation of the vertical position. The eddy currents in the vacuum vessel have a sizeable influence on the equilibrium reconstruction and must be taken into account. A real time version of LIUQE has been implemented on TCV's distributed digital control system with a cycle time shorter than 200 μs for a full spatial grid of 28 by 65, using all 133 experimental measurements and including the flux surface average of quantities necessary for the real time solution of 1.5 D transport equations. This performance was achieved through a thoughtful choice of numerical methods and code optimisation techniques at every step of the algorithm, and was coded in Matlab and Simulink for the off-line and real time version respectively. [ABSTRACT FROM AUTHOR]

The equilibrium magnetopause location on the dayside is determined by the balance of pressure forces. In this paper we use a physics-based global magnetohydrodynamic (MHD) to examine contributions of different terms to this balance. We calculate the total pressure, as well as thermal and magnetic pressures just inside and just outside the magnetopause. Our results show that (1) the total pressure just outside the magnetopause is enhanced with the increasing of B Z in both northward and southward interplanetary magnetic field (IMF). For southward IMF the thermal pressure is dominant in the total pressure while the magnetic pressure is dominant for northward IMF when B Z is not small ( B Z > 5 nT ) . For southward IMF larger solar wind dynamic pressure further enhances thermal pressure near the magnetopause while for northward IMF the dynamic pressure is more effectively converted to the magnetic pressure; (2) the thermal pressure just outside the magnetopause is significantly enhanced with the increasing southward IMF as compared to the northward IMF case. However, this enhanced thermal pressure is not the only reason for the well-known earthward displacement of the magnetopause under southward IMF conditions. The dayside magnetic reconnection for southward IMF dramatically decreases magnetic pressure just inside the magnetopause. The combination of these two factors explains the Earthward motion of the magnetopause for southward IMF. [ABSTRACT FROM AUTHOR]

In the application of Split Hokinson Pressure Bar (SHPB) techniques, test bars made of viscoelastic materials are frequently used for their low impedance to test soft materials. Wave propagations in such bars are susceptible to dispersions caused by the viscoelastic effects of the bar material along with the lateral inertia of the bar particularly when large diameters are used. Thus, the time shifting of the strain signals from the recording gauges on the bars to the bar-specimen interface requires corrections based on both the material properties and the diameter of the bar. Most of the methods available in the open literature, for viscoelastic material identification using wave propagation tests, are based on one-dimensional wave propagation theory in which signal dispersions due to the lateral inertia are ignored and hence are appropriate for the bars with small diameters. A method of parametric identification is proposed in the current study, using the frequency domain information, for the viscoelastic properties of a relatively large diameter bar made from polymethyl methacrylate (PMMA). A three-dimensional wave propagation analysis is employed using recorded strain data at a single location on the PMMA bar. It is found that the proposed parametric identification procedure, compared with the results of a non-parametric identification, helps to rectify the uncertainties in the identified material characteristics in the form of a highly oscillatory trend caused by the noise in the recorded signals and by the data reduction procedures. Strain signals predicted using the identified material parameters by the proposed method correlate well with the measured experimental strains, indicating accuracy in the identified parameters and the presented procedure. [ABSTRACT FROM AUTHOR]