Pressure Phase Research Articles

Experimental study on transient characteristics and thermal stratification of high−pressure CO2 leakage under different initial density

Accidental leakage is one of the major safety issues in the carbon capture and storage project (CCS), which may pose a significant danger to pipelines, containers and surrounding crowd. It is necessary to study the leakage behavior of high−pressure CO2, providing data support for the risk assessment of CO2 leakage. In this paper, the accidental leakage of high−pressure CO2 is simulated by releasing CO2 from a storage tank, aiming to understand the transient characteristics and thermal stratification inside the tank of CO2 leakage process. The initial CO2 is at different initial density of 600∼1000 kg/m3 and at almost the same initial pressure of 10.8±0.4 MPa. Firstly, the outlet transient characteristics and temperature evolution inside the tank are presented. Then, the variation of P−T curves and phase evolution are analyzed in detail. Finally, the leakage behavior under different initial density is described. The results show that the leakage process can be clearly divided into three stages based on the outlet pressure. The outlet pressure evolution, phase evolution and temperature distribution inside the tank are very different in these three stages. This research is of great significance for leakage risk prediction, early leakage detection and leakage hazard control.

Ankle Fracture Gait Training Through Musical Feedback: Case Study

BACKGROUND: Trimalleolar ankle fractures often result in mobility and gait impairments. To date, there is little consensus on the rehabilitation regimen. Biofeedback is an emerging approach that improves gait in different populations; here, we utilized novel customized musical biofeedback to retrain gait following trimalleolar ankle fracture. CASE PRESENTATION: A 56-year-old male sustained a right trimalleolar ankle fracture and underwent surgical fixation, followed by immobilization, progressive weight bearing, and a regular physical therapy regimen. Additional gait training sessions were provided with musical feedback from pressure-sensing insoles to provide accurate cues to encourage medialized load pressure and prevent avoidance behavior. OUTCOME AND FOLLOW-UP: Mobility, functionality, stance phase, stride length, total force distribution, and plantar pressure improved after training. DISCUSSION: This is the first study on gait training after ankle fracture using customized pressure-based biofeedback with music to normalize plantar pressure and push-off phase.

How Much Hatchery-Reared Brown Trout Move in a Large, Deep Subalpine Lake? An Acoustic Telemetry Study

Fish movement into large, deep lakes has been rarely investigated due to the complexity and extent of such ecosystems. Among the different monitoring methods available, acoustic telemetry enables the study of the spatial ecology and behavior of aquatic organisms in lentic environments. In this study, the movement of 69 hatchery-reared adult brown trout (size 43–61 cm) marked with acoustic transmitters was monitored in the large and deep subalpine Lake Lugano (Switzerland and Italy). Trout were tracked for six consecutive months by seven acoustic receivers (March–August 2022), positioned in a non-overlapping array. Trout movement was reconstructed using R packages specific for acoustic telemetry (actel and RSP), which also allowed us to translate tracking information into utilization distribution (UD) areas for each fish. The effects of different environmental variables (rainfall, water discharge of the two main tributaries of Lake Lugano, atmospheric pressure, cloud coverage, and moon phases) on trout movement were tested, but none of these variables seemed to significantly correlate with fish movement. After release, most of the tagged fish exhibited reiterative movements during the initial month, with some maintaining this behavior throughout the entire study period. This spatial behavior can be particularly evident in hatchery-reared fish due to their aggressive and bold attitude. The association of these behavioral traits, shaped by domestication, could expose hatchery-reared fish to high risks and post-release mortality in the wild. Indeed, within a few months after the release, most of the tagged fish were no longer detected by the acoustic receivers. In addition, 26% of the total tagged fish were caught by recreational or professional fishermen.

Structural Phase Transitions of Mg2NiH4 Induced by NiH4 Molecular Ion Distortion and Metal Lattice Deformation under High Pressures.

Experimental observations indicate that pressure treatments transform the monoclinic and orthorhombic low-temperature phases of Mg2NiH4 into an unresolved pseudocubic phase even at room temperatures, resembling the temperature-induced phase transformation of the material. This pressure-induced phase transformation is anticipated to involve deformations of the tetrahedrally bonded NiH4 molecular ion and the metal lattice. However, the precise mechanism underlying this transformation remains unclear. To elucidate this behavior, this study adopted first-principles density functional theory calculations to investigate the effect of applied pressure on the observed phase transition. The results revealed that the phase transition from the low-temperature phases to the pseudocubic phase occurs at approximately 8-9 GPa. Furthermore, at this pressure, the metal lattice deforms into an antifluorite-like structure, and the NiH4 molecular ion undergoes substantial distortion, resulting in the alignment of hydrogen atoms along the crystal axes of the metal lattice. Furthermore, through a comprehensive structural exploration, we successfully identified several tetragonal and orthorhombic models that are energetically more stable than the low-temperature phases at low pressures. These models are potential candidates for elucidating the pseudocubic phase observed in experiments. Overall, our findings are anticipated to enhance the current understanding of the structural changes occurring during pressure and temperature-induced phase transitions.

66 - Relative phase of abdominal pressure and urine flow rate could diagnose male bladder outflow obstruction

66 - Relative phase of abdominal pressure and urine flow rate could diagnose male bladder outflow obstruction

Kinetics of methane hydrate formation in a 1200 ml unstirred reactor for natural gas storage

Solidified natural gas (SNG) technology via clathrate hydrates, enhanced by promoters such as tetrahydrofuran (THF), promises large-scale natural gas storage due to its high volumetric capacity and mild storage conditions. Despite its potential for industrial scale-up, limited research exists on methane hydrate formation behaviors in large reactors (>1000 cm3), which is crucial for evaluating practical storage performance. In this study, methane hydrate formation kinetics were investigated in a scaled-up unstirred reactor (1200 cm3) at 288.15 K and 283.15 K, and 5.0 MPa. Methane uptake, system pressure, gas and liquid phase temperatures, and hydrate morphologies were analyzed to describe the dynamic hydrate formation process. Results reveal three effects of increased reactor size in contrast to smaller reactors: (i) heterogeneous distribution of THF-rich and methane-rich hydrates; (ii) hydrate bulk show a hollow inner structure with a cavity due to the wall-climbing behavior of hydrate growth; (iii) optimal THF concentration no longer always agrees with stoichiometric 5.56 mol%, which is case-dependent. These effects are attributed to higher diffusion resistances for methane molecules and more intensive heat accumulation. These findings provide some insight into the kinetics of methane hydrate formation in industrial reactors, which is critical for the commercialization of SNG technology.

Pressure-induced structural transition and superconductivity in hard compound IrB4

The recent discovery of MoB2 with a superconducting transition temperature (Tc) of up to 32 K at 100 GPa provides new insights into the metallization and subsequently high-Tc superconductivity of diborides, highlighting the potential of transition metals in these compounds. We herein re-evaluated the structure, mechanical, and superconducting properties of IrB4 under pressure up to 300 GPa using first-principles. Our calculations reveal that a new P21/c phase exhibiting a hardness of 15.75 GPa surpasses the stability of the C2/m structure identified through the particle swarm optimization at ambient pressure. Upon compressing, the P21/c phase transforms into an MgB2-type structure with a space group of P63/mmc at 62.5 GPa and then into the orthorhombic Cmca phase above 109 GPa. Unlike semiconductor behavior of the atmospheric pressure phase, the two high-pressure structures are metallic and superconducting, with Tc values of 29.90 for P63/mmc at 62.5 GPa and 13.45 K for Cmca at 125 GPa. Analysis of the electronic structure and electron–phonon coupling (EPC) reveals that the high Tc, similar to MgB2-type MoB2, stems from the Van Hove Singularities (VHS) near the Fermi level donated by transition metal Ir. The effect further enhances the EPC based on the boron contribution. More interestingly, pressure has little impacts on the position of the VHS. These findings provide a new platform for designing advanced high-Tc superconductors.

Monoclinic distortion and magnetic transitions in FeO under pressure and temperature

Fe1-xO, although chemically simple, possesses a complex structural and magnetic phase diagram. The crystal structures of Fe1-xO and its magnetic properties at extreme conditions are still a matter of debate. Here, we performed a systematic investigation on Fe0.94O up to 94 GPa and 1700 K using synchrotron X-ray diffraction and synchrotron Mössbauer source spectroscopy. We observe a transition of Fe0.94O to the monoclinic phases above 40 GPa and at high temperatures and use the group theory analysis of the observed phases to discuss their properties and their relation to the ambient pressure phases. The Mössbauer spectra of the rhombohedral and the room temperature monoclinic phase contain a component attributed to Fe2.5+, caused by the electron exchange between the Fe3+ defect and neighboring Fe2+ atoms. Our results present a structural and magnetic transitional pressure-temperature diagram of Fe1-xO and show the complex physicochemical properties of simple Fe1-xO binary oxide under extreme conditions.

Pressure-induced structural, electronic, and superconducting phase transitions in TaSe3

Abstract TaSe3 has garnered significant research interests due to its unique quasi-one-dimensional crystal structure, which gives rise to distinctive properties. Using crystal structure search and first-principles calculations, we systematically investigated the pressure-induced structural and electronic phase transitions of quasi-one-dimensional TaSe3 up to 100 GPa. In addition to the ambient pressure phase (P21/m-I), we identified three high-pressure phases: P21/m-II, Pnma, and Pmma. For the P21/m-I phase, the inclusion of spin–orbit coupling (SOC) results in significant SOC splitting and changes in the band inversion characteristics. Furthermore, band structure calculations for the three high-pressure phases indicate metallic natures, and the electron localization function suggests ionic bonding between Ta and Se atoms. Our electron–phonon coupling calculations reveal a superconducting critical temperature of approximately 6.4 K for the Pmma phase at 100 GPa. This study provides valuable insights into the high-pressure electronic behavior of quasi-one-dimensional TaSe3.

Self-excited force characteristics and flow mechanisms of a 5:1 rectangular cylinder in torsional vortex-induced vibration and flutter

In this paper, the self-excited force characteristics, flow rules and vibration mechanisms of a 5:1 rectangular cylinder in torsional vortex-induced vibration (VIV) and flutter were investigated through wind tunnel tests and numerical simulations. The nonlinearity of the self-excited lifting moment is not monotonous but exhibits a peak within a specific reduced wind speed and amplitude range. The amplitude-dependent characteristics of dimensionless work and aerodynamic damping are the primary reasons for non-divergent vibration, which is mainly influenced by the amplitude-dependent phase difference. The reduced wind speed significantly affects the formation zone length and convection speed of the leading-edge vortex, thereby determining the distribution of surface pressure phase difference and dimensionless work. As the reduced wind speed increases, there is a positive and negative alternation in dimensionless work, leading to the occurrence of torsional VIV and flutter. While the torsional amplitude does not affect the distribution of phase difference, it merely influences the formation zone length, resulting in amplitude-dependent dimensionless work and accounting for the non-divergent vibration. The characteristics of vortex convection, pressure phase variation and dimensionless work of the 5:1 rectangular cylinder in torsional VIV and flutter follow similar rules, indicating that the two vibration forms share the same inherent essence.

Novel Approach to Analyzing Friction Losses by Modeling the Microflow of Lubricating Oil between the Piston Rings and Cylinder in Internal Combustion Engines

This work focuses on the evolution of lubrication wedge shaping in internal combustion piston engines, taking into account liquid microflows on curved surfaces and coating microgeometries. It introduces a new approach to the analysis of friction losses by simulating the microflow of lubricating oil between the surfaces of piston rings cooperating with the cylinder surface. The models used take into account three types of microgeometry and material expansion. Key results indicate that microirregularities with a stereometry of 0.1–0.2 µm significantly influence the distribution of oil film thickness in the phase of maximum working pressure, which is critical for the functioning of the seal ring. The innovation of the work consists of demonstrating that, despite small changes in the friction force and power in the piston rings, changes in the minimum values of the oil film thickness are significant. The work highlights the failure to take into account microgeometry parameters in friction models, which leads to significant errors in the simulation results, especially in terms of oil film continuity and the contribution of mixed friction. The simulations also indicate that advanced geometric models with high mesh resolution are necessary only for the assessment of changes in oil film thickness during the highest pressure increase in the combustion chamber and taking into account various mixed friction conditions. The results suggest significant progress in engine design and performance, confirming the importance of advanced fluid and mixed friction models in piston engine lubrication research.

Investigating the effect of external surface layer on high pressure phase evolution in a single crystal: A mechanics-based phase field study

Investigating the effect of external surface layer on high pressure phase evolution in a single crystal: A mechanics-based phase field study

Understanding Pressure Effects on Structural, Optical, and Magnetic Properties of CsMnF4 and Other 3dn Compounds.

The pressure dependence of structural, optical, and magnetic properties of the layered compound CsMnF4 are explored through first-principles calculations. The structure at ambient pressure does not arise from a Jahn-Teller effect but from an orthorhombic instability on MnF63- units in the tetragonal parent phase, while there is a P4/n → P4 structural phase transition at P = 40 GPa discarding a spin crossover transition from S = 2 to S = 1. The present results reasonably explain the evolution of spin-allowed d-d transitions under pressure, showing that the first transition undergoes a red-shift under pressure following the orthorhombic distortion in the layer plane. The energy of such a transition at zero pressure is nearly twice that observed in Na3MnF6 due to the internal electric field and the orthorhombic distortion also involved in K2CuF4. The reasons for the lack of orthorhombic distortion in K2MF4 (M = Ni, Mn) or CsFeF4 are also discussed in detail. The present calculations confirm the ferromagnetic ordering of layers in CsMnF4 at zero pressure and predict a shift to an antiferromagnetic phase for pressures above 15 GPa consistent with the reduction of the orthorhombicity of the MnF63- units. This study underlines the usefulness of first-principles calculations for a right interpretation of experimental findings.

Ocular Perfusion Pressure in Primary Open Angle

Purpose: To determine thecorrelation of Mean Ocular Perfusion Pressure (MOPP) with Mean Arterial Pressure (MAP) in primary open angle glaucoma (POAG)and normal tension glaucoma. Study Design: Cross sectional study. Place and Duration of Study: Khyber Teaching hospital, Peshawar from July, 2017 to December, 2019. Methods: A total of 375 patients with POAG were admitted in the hospital. Patients with variable blood pressure (BP) on admission or history of blood pressure or using anti-hypertensive drugs were selected. Patients with secondary Glaucoma, Primary Angle closure Glaucoma, patients with Diabetes mellitus and age below 40 years were excluded. Finally,200 patients were recruited by convenience sampling. Forty-eight hours monitoring of MAP and Intra ocular pressure (IOP) phasing were done. MAP, MOPP and peak IOP were charted. Results: MAP and MOPP variabilitywas observed in 53% of patients with POAG. The Pearson co-relation coefficient for those patients in which intervention had yet not been done was -0.460 suggesting a moderate negative correlation between MOPP and IOP (p value <0.01). In IOP controlled patients, the coefficient was -0.346 (p<0.01). Theresults showed a negative correlation between the two values in both data sets. The correlation co-efficient for MAP and IOP in both pre-admission and controlled IOP patients showed strong positive correlation (0.816 and 0.854 respectively for two tailed tests with 0.01 significance). Conclusion: MOPP, MAP and IOP are correlated and their determination is important in all Primary Open Angle Glaucoma particularly in Normal Tension Glaucoma.

Sensitivity of creep parameters to pressure fluctuation of transient flow in viscoelastic pipes

ABSTRACT A stepwise method is one of the efficient approaches in the calibration of transient flow in viscoelastic pipes. However, there is the lack of comprehensive research on the calibration method for retarded time and creep compliance. Therefore, the sensitivity of the order of magnitude of the creep parameters in the presence of interactions to transient flow pressure damping and phase in the case of the two-element Kelvin–Voigt model is investigated. Also, the calibration methods of retarded time and creep compliance in the stepwise method of transient flow parameter calibration for viscoelastic pipes are proposed. The results indicate that the creep compliances do not affect the phase of the pressure fluctuations when the selected retarded times are greater than the order of magnitude 10−1. For the first Kelvin–Voigt element, when the order of magnitude of the retarded time exceeds 10−2, an increase in creep compliance results in an increase in the degree of damping of pressure fluctuations. When the order of magnitude of the retarded time is less than 10−2, the rule is reversed. For the second Kelvin–Voigt element, an increase in creep compliance results in an increase in the degree of damping of transient flow pressure fluctuations independent of the retarded time.

Современное состояние исследований сверхпроводящей и электронной подсистемы стехиометрических ферропниктидов семейства 1144

Due to multiple-band structure, an interplay between superconducting and magnetic subsystems, the members of the 1144 iron-pnictide family show a number of unique properties not typical to other ferropnictide families. Nonetheless, a quick degradation in open air causes a lack of experimental probes of such extraordinary compounds. In the review, we briefly consider the crystal structure, doping and pressure phase diagram, band-structure features, as well as summarize the available experimental data on the gap structure of the 1144 family pnictides. We compare the properties of the 1144 materials with those of a sister 122 family compounds.

Materials removal mechanism for ultra-precise cutting of single-crystal silicon with natural single-crystal diamond tools by experiment and atomic simulation

The influence of tool rake angle and cutting speed on the ultra-precision cutting of single crystal silicon with natural single crystal diamond tools is studied by experiment and molecular dynamics (MD) simulations. The findings demonstrate that the 0° rake angle tool attains superior surface quality, reduced cutting force and friction coefficient in comparison to the −10° and − 20° rake angle tools. Moreover, the MD results reveal that a smaller negative rake angle tool can decrease the formation of high pressure phase atoms and other defects. In addition, the PV, RMS and Ra surface roughness parameters decrease as the machine spindle speed increases. Additionally, higher cutting speeds improve the surface morphology of the machined workpiece and produce fewer defective atoms.

High pressure phase transition and its influence on structural, mechanical properties and elastic anisotropy of [formula omitted]: An ab-initio study

Lithium carbide (Li2C2), a promising tritium breeding material with potential applications in magnetic confinement-based fusion reactor blankets, has drawn significant attention due to its recent utilization in lithium-ion batteries. In the current study, we employed first-principles calculations with van der Waals (vdW) force correction to explore the structural and mechanical properties of Immm and Pnma phases of Li2C2 subjected to external hydrostatic pressure. It is demonstrated that inclusion of vdW effects accurately predicts Immm→Pnma phase transition at 16 GPa, aligning closely with experimental transition pressure. In contrast, PBE-GGA calculations underestimate the same by about 21%. Current paper is the first comprehensive study of pressure evolution of mechanical properties and strength determining parameters of Li2C2. Interestingly, this inherently brittle material exhibits ductile characteristics beyond 7.5 GPa. The paper also offers a quantitative comparison of its strength parameters with other prominent tritium breeding materials. Finally, the strong directional dependence due to the presence of C2 dimer is investigated by analyzing the pressure variation of elastic anisotropy. The study has its relevance in assessing structural integrity of Li2C2 during inadvertent buildup of tritium and helium that would generate stress in the solid breeder.

Effect of flywheels in pump stations for reducing the volume of air chambers

ABSTRACT The most common and destructive event of unsteady flow in pipes is water hammer. This phenomenon is caused by a sudden change in boundary conditions in pressurized pipes. Unsteady flow in pipelines can lead to a significant increase or decrease in pressure. This pressure generation may cause cavitation, bursting of pipes, and failure of the whole system. One type of equipment that can control both positive and negative pressure phases is a pressurized tank. Implementing such a pressure tank can impose increased costs. In order to reduce the design costs, the combination of a flywheel with the pressure tank can be used. In this study, a transmission pipeline from Zarineh River to Tabriz city is numerically simulated, and the effect of increasing the inertia of the flywheel on the reduction of the pressurized tank volume is investigated. The results show that increasing the flywheel inertia from 125 to 165 Nm2 can reduce the pressurized tank volume from 90 to 75 m3.

The pressure-volume relationship in an ideal Stirling refrigerator

Hysteresis losses in the heat transfer between compressing or expanding gas and the adjacent wall is said to play an important role in Stirling machines, where it increases the amount of required p-V work. Previous studies have linked hysteresis loss with the pressure phase shift. In the context of this research, the effect of the pressure phase shift on the net p-V work in a single space is examined.A Sage model of a single space piston-cylinder device is used to investigate the underlying mechanisms of the pressure phase shift. The Sage model is validated using an experimental piston seal rig. In addition, the time dependence of heat transfer is discussed along with how it affects the pressure phase shift, using an iterative model. The Schmidt equations were manipulated to determine the phase shift between pressure and volumetric oscillation in an ideal Stirling refrigerator.The results of this investigation are surprising. It was found that even in the case of an idealized Stirling refrigerator, the phase shift between pressure and volume is non-zero in order to produce a refrigeration effect.