Pressure Medium Research Articles

Comparison of prognosis of patients with endometrial cancer after hysteroscopy versus dilatation and curettage: A multicenter retrospective study.

Hysteroscopy is a useful procedure for diagnosing endometrial cancer. There is controversy regarding whether hysteroscopy affects the prognosis of endometrial cancer by prompting cancer cell into intraperitoneal dissemination. Our purpose was to confirm whether hysteroscopy could be a risk factor of the tumor stage, recurrence and survival rate of endometrial cancer. This multicenter retrospective study included all consecutive patients who had endometrial carcinoma diagnosed preoperatively with hysteroscopy and directed endometrial biopsy (HSC, group A) and dilatation and curettage (D&C, group B) between February 2014 and December 2018 at the Fujian Provincial, China. We compared the demographic feature, clinical characteristics and prognosis between the two groups. A total of 429 patients were included in the study (Group A, n = 77; Group B, n = 352). There was no significant difference between their baseline characteristics [including age, BMI, histological type and International Federation of Gynecology and Obstetrics (FIGO) stage]. By comparing several pathological conditions that may affect prognosis, there were no significant differences between the two groups in the peritoneal cytology, depth of myometrial invasion, the positivity of lymph nodes, lymphovascular space invasion and paraaortic lymph node dissection. Finally, no significant difference was found between the two groups in overall survival (OS) (P = 0.189) or recurrence free survival (RFS) (P = 0.787). Under certain inflation pressure and distension medium, hysteroscopic examination and lesion biopsy ensure the safety and have no adverse effects on prognosis compared to conventional curettage.

Note on a Novel Model for Capillary Pressure in Porous Media

Note on a Novel Model for Capillary Pressure in Porous Media

Compressibility and Structural Transformations of Aluminogermanate Imogolite Nanotubes under Hydrostatic Pressure

We present in situ pressure experiments on aluminogermanate nanotubes studied by X-ray scattering and absorption spectroscopy measurements. Structural transformations under hydrostatic pressure below 10 GPa are investigated as a function of the morphology, organization, or functionalization of the nanotubes. Radial deformations, ovalization for isolated nanotubes, and hexagonalization when they are bundled are evidenced. Radial collapse of single-walled nanotubes is shown to occur, in contrast to the double-walled nanotubes. The effect of the transmitting pressure medium used on the collapse onset pressure value is demonstrated. Axial Young's moduli are determined for isolated (400 GPa) and bundled (600 GPa) single-walled nanotubes, double-walled nanotubes (440 GPa), and methylated single-walled nanotubes (200 GPa).

Nanostructuring and stabilization of metastable rock-salt ZnO: impact of high-pressure media and compression geometry

Record thermal stability (800 K) and Vickers hardness (7 GPa) of the rock-salt high-pressure phase of ZnO have been achieved for single-phase nanostructured bulk by using the combination of appropriate compression conditions and pressure medium.

Influence of the microfin tube structure on the thermal-hydraulic performance of mixed supercritical CO2/R32

This research establishes 5 mm 3-D flow and heat transfer microfin tube theoretical models with three different geometric structures. Using these models, the thermal-hydraulic performances of supercritical CO2/R32 in microfin tubes with different structures at various working conditions were investigated. The influences of each of three factors (pressure, mass-flow, and microfin tube structures) on the thermal-hydraulic performance of CO2/R32 were evaluated, respectively. Furthermore, orthogonal tests were undertaken to obtain the optimized combination of overall thermal-hydraulic performance. Results indicate that: the more the temperature of working media approximates to the critical temperature, the bigger the local convective heat transfer coefficient (CHTC). Compared to non-critical temperatures, the CHTC at critical temperature shows an eight-fold increase. The closer the pressure of the mixed working media is to the critical pressure, the greater the maximum CHTC and the lower the temperature corresponding to the peak point, among which, the maximum CHTC under 7.5 MPa is three times as large as that at 8.5 MPa. The CHTC increases with increasing mass velocity, generally showing a linear relationship. Through calculating the most optimal combination of thermal-hydraulic performance evaluation using orthogonal tests, the maximum CHTC is determined to be 96 kW/m2K.

ВИЗНАЧЕННЯ ТИСКУ У КАМЕРІ ГАЗИФІКАЦІЇ ГАЗОГЕНЕРАТОРА

The purpose of the work: determination of patterns of pressure changes in the gasification chamber of the gas generator. Methodology of the work: a comprehensive approach, which includes theoretical studies of the processes of changing the thermodynamic parameters of the gas phase in the working chamber of the gas generator, a calculation and analytical method for determining the pressure of the working medium, depending on the temperature and its composition in the gas generator. Results: patterns of pressure changes in the working chamber of the gas generator at different operating modes were obtained. Scientific innovation: modeling and calculation of pressure indicators of the working medium in the working chamber of the gas generator, depending on the environmental factors: temperature and composition of the working medium, humidity of solid fuel, were carried out. It is taken into account that the gaseous phase is a real gas, according to the Van der Waals equation. An algorithm for calculating pressure based on data on quantitative indicators of gases in the mixture is proposed. The regularities of the behavior of the gas medium in the range of operating temperatures of the gas generator have been established. Practical significance: the obtained results made it possible to determine the pressure in the working chamber of the gas generator under different modes of its operation and to develop appropriate design solutions for the corresponding nodes (housing, sealing devices, etc.) of gas generators of narrow standard sizes. Key words: gas generator, combustion chamber, pressure, ideal gas, non-ideal gas, gas-air mixture, temperature.

Application of methods for modeling hydraulic and non-isothermal steady states of gas transmission systems

In the article, for the first time, an attempt was made to justify the effectiveness of the application of new generalized methods of the theory of hydraulic circuits for modeling stationary modes of operation of gas transmission systems of complex structure and configuration. A classification of the main models of a steady gas flow is given for individual elements of the system, including traditional ones, those implicitly specified in terms of flow rate and dependent on the pressure of the working medium. Generalized flow distribution models are proposed that take into account all these cases. Conditions for the applicability of generalized methods that ensure the existence and uniqueness of the solution to the flow distribution problem are considered. The characteristics of these methods and final algorithms are given, which provide confident convergence and require less computational costs compared to existing methods. Numerical examples illustrating such possibilities are given.

The Influence of Social Media in Sports Marketing

Aim of the Study: This study aims to assess the influence of social media on the sports marketing industry. Global surge in social media marketing has influenced sports marketing as well. Coca Cola is one such company. Coca cola has switched its maximum marketing campaigns to digital. The sports market is currently under the severe pressure of social media. Traditional methods of advertising such as print, radio, and television have all but vanished from the market in recent decades. This study focuses on how marketing has changed through time, moving from conventional to digital methods. Methodology: Current study has used survey method and for this purpose a questionnaire about Pakistani consumers' viewing and engagement preferences for sports sponsor brand commercials on traditional and social media was developed and responses from sample of (N=802) were recoded. Findings: The results of the surveys and the data collected point that, at least in Pakistan, traditional media still has strong influence on marketing sector. For sports brands, social media marketing is a useful addition to conventional marketing. Conclusion: This study concluded that sports brands don't have to completely abandon traditional marketing strategies; instead, they could embrace social media as a supplement to their traditional media marketing tactics.

Machine learning-based models for predicting gas breakthrough pressure of porous media with low/ultra-low permeability.

Gas breakthrough pressure is a significant parameter for the gas exploration and safety evaluation of engineering barrier systems in the carbon dioxide storage, remediation of contaminated sites, and deep geological repository for disposal of high-level nuclear waste, etc. Test for determining gas breakthrough pressure is very difficult and time-consuming, due to the low/ultra-low conductivity of the specimen. It is also difficult to get a comprehensive and high-precision model based on limited results obtained through individual experiments, as the measurements of gas breakthrough pressure were influenced by many factors. In this study, a collected database was built that covered a lot of former test data, and then, two models were developed by the random forest (RF) algorithm and multiexpression programming (MEP) method. The MEP model constructed with explicit expressions for the gas breakthrough pressure overcame the drawbacks of common "black box" models. Meanwhile, five significant indicators were selected from ten common features using the permutation importance algorithm. The RF model was interpreted by the Shapley value and the PDP/ICE plots, while the MEP model was analyzed through the proposed explicit expression, showing strong consistence with that in former studies. Finally, robustness analysis was conducted, and stability of the proposed two models was verified.

Modal analysis of a hydrogen-damaged pipe as shell inhomogeneous on thickness

Hydrogen corrosion of main gas and oil pipelines often leads to accidents. It is necessary to assess the life of hydrogen-weakened pipes. An inner layer with deteriorated mechanical characteristics is formed in them under pressure of hydrogen-containing medium. In the paper the calculation of free vibrations of such a tube taking into account the degradation of its material is performed. The tube is modeled as a bilayer cylindrical shell according to the classical theory. Influence of hydrogen-impacted layer is taken into account when calculating stiffnesses and displacement of neutral line of the shell. Three variants of averaging of parameters determining the stiffness of the shell are considered, numerical experiments are carried out and the natural frequencies of the shell are found. Comparison with calculations using the method of finite elements in the ANSYS software made it possible to estimate the degree of applicability of each version of averaging. The method of averaging Young's modulus over the thickness of the shell does not "feel" asymmetry of layers relative to the neutral line. The method of adding a correction for the neutral line radius of the shell works satisfactorily for axisymmetric and beam modes. The next more accurate approximation is to average the shell stiffnesses over its thickness with the reduced radius. This method allows us to obtain satisfactory results in a wide enough frequency range and for the modes related to the deformation of the shell cross section. A method for the principle reconstruction of the parameters characterizing the stiffness of the shell using three experimentally obtained fixed frequencies has been proposed. On the basis of these studies formulas are proposed which allow to reconstruct parameters of weakening of pipe material, as a result of hydrogen corrosion, both in thickness and in time from the frequency characteristics of the pipe.

Influence of pressure-induced formation of dihydrogen bonds on lattice parameters, volume, and vibrational modes of ammonia borane.

The high-pressure phase of ammonia borane (NH3BH3) observed at ∼1.2GPa has been reported to result in pressure-induced formation of dihydrogen bonds at ∼4GPa. In this study, we performed high-pressure x-ray diffraction measurements on the high-pressure phase (up to ∼10.2GPa) using a He hydrostatic pressure medium to examine the influence of the formation of dihydrogen bonds on the lattice parameters and unit cell volume of NH3BH3. We observed a unique behavior in the pressure dependence of lattice parameters close to the pressure at which the dihydrogen bond was formed. The lattice parameters demonstrated hysteresis curves under compression and decompression conditions but the unit cell volume did not. Moreover, the pressure dependence of the unit cell volume could not be expressed using a single Birch-Murnaghan equation within an acceptable margin of error, thus suggesting a change in bulk modulus under compression. These results are considered to have originated from the pressure-induced formation of dihydrogen bonds. Moreover, high-pressure Raman scattering measurements and a simulation using density functional theory calculations revealed the vibrational modes of the high-pressure phase of NH3BH3. The results demonstrated that librational modes were enhanced by forming dihydrogen bonds. Moreover, the intramolecular stretching modes of BN, BH, and NH monotonically shifted with pressure, while the symmetrical in-plane bending modes of BH3 and NH3 split irrespective of the formation of dihydrogen bonds.

Acoustic Response of a Vibrating Elongated Cylinder in a Hydrodynamic Turbulent Flow

The present paper contains the results of the numerical analysis of the interaction between a Newtonian incompressible turbulent flow and a linear elastic slender body, together with the influence of the fluid–structure interaction (FSI) on the noise generation and propagation. The purpose is to evaluate the differences in term of acoustic pressure between the case where the solid body is rigid (infinite stiffness) and the case where it is elastic (finite stiffness). A partitioned and implicit algorithm with the arbitrary Lagrangian–Eulerian method (ALE) is used for the interaction between the fluid and solid. For the evaluation of the turbulent fluid motion, we use a large eddy simulation (LES) with the Smagorinsky subgrid scale model. The equation for the solid is solved through the Lagrangian description of the momentum equation and the second Piola–Kirchoff stress tensor. In addition, the acoustic analogy of Lighthill is used to characterize the acoustic source (the slender body) by directly using the fluid dynamic fields. In particular, we use the Ffowcs Williams and Hawkings (FW-H) equation for the evaluation of the acoustic pressure in the fluid medium. As a first numerical experiment, we analyze a square cylinder immersed in a turbulent flow characterized by two different values of stiffness: one infinite (rigid case) and one finite (elastic case). In the latter case, the body stiffness and mean flow velocity are such that they induce the lock-in phenomenon. Finally, we evaluate the differences in terms of acoustic pressure between the two different cases.

Energy efficiency of bio-coal derived from hydrothermal carbonized biomass: Assessment as sustainable solid fuel for municipal biopower plant

The utilization of conventional biomass to generate electricity in the biomass thermal power plant is still inefficient due to high content of moisture, high impurity, and low heating value. To explore this limitation, in this research, hydrothermal carbonization (HTC) was selected as a sustainable process for producing green solid fuel or bio-coal with a rich of carbon content from palm shell and bamboo, remarkably as model biomass raw materials. The effect of biomass to water weight ratio (1:1 to 1:10), reaction temperatures (160 – 250 °C), and reaction times (1 – 6 h) were performed under autogenous pressure of promising aqueous media. The effect of organic and inorganic acid adding in the HTC of palm shell and bamboo was discussed. The obtained bio-coal was further well characterized with proximate and ultimate analysis and fuel properties. From the results, increasing reaction temperature and adding of acids led to increase carbon content, resulting to increase HHV of bio-coal. Effects of feedstocks (palm shell and bamboo), temperature, and types of acids revealed significantly results on the bio-coal yield accompanied with carbon content, the higher heating value (HHV), energy densification, and energy yield. The addition of inorganic acid in the HTC of biomass with high cellulose content provided higher HHV improvement than that of stony biomass. The highest HHV of 27.9 MJ/kg was obtained in bio-coal derived from palm shell feedstock with 1:1 water ratio and hydrothermally at 250 °C for 6 h. Surprisingly, this HHV is comparable to high-volatile bituminous coal. Moreover, an evaluating assessment for the utilization of this bio-coal instead of biomass feedstock to generate electricity in the thermal power plant with size of 9.9 MW capacity could reduce 34.4 % of fuel storage size, save nearly 29,709.36 USD/year in transportation costs and diminish CO2 emission during burning by approximately 56,732 tons/25 years.

Effects of DC Polarity and Field Uniformity on Breakdown of SF₆ and C₃F₇CN/CO₂ Mixture

To address the issues of greenhouse gases and resultant global warming, there is an urgency to find an electronegative gas to replace SF6 in global power system networks. This article provides an experimental study of various factors on DC breakdown of electronegative gases. Rod-plane geometries with a range of rod diameters (3.5–12.5 mm) and electrode separations (5–55 mm) are used to provide different degrees of field uniformity. SF6 and a 20% C3F7CN / 80% CO2 mixture are tested under pressures ranging between 1 and 5 bar. Breakdown voltages (BDVs) under both polarities rise linearly with gap distance in quasi-uniform fields with the positive being higher. Increasingly nonuniform fields lead to saturation in the case of positive BDV, while in the negative polarity case, the BDV increases linearly. As a result, the two polarities’ BDV magnitudes crossover as field nonuniformity increases. The value at which the negative value exceeds the positive is dependent on the field uniformity, pressure, and gas medium. A simulation based on the streamer criterion model provides a good agreement with experimental results for positive DC breakdown in the range of 2–5 bar. In terms of the insulation characteristics, 20% C3F7CN / 80% CO2 could provide a valuable alternative to SF6 in high-voltage plant for outdoor applications in hot-climate countries and indoor applications in cold-climate countries.

Comparative study of the HP‐HTbehavior of a layered silicate apophyllite in water and paraffin oil

AbstractThe interaction of porous minerals with liquids, especially water, is involved in many technological and geochemical processes. Apophyllite (K,Na)Ca4[Si8O20](F,OH).8H2O, exhibiting mixed properties of layered and framework microporous silicates, is a promising object to model the interaction of a fluid with porous material. It was studied by the in situ Raman spectroscopy at simultaneously high pressure (HP) and high temperature (HT) up to 225°C and 9 GPa in order to clarify the effect of the composition of the pressure medium and the temperature on its HPbehavior. Penetrating (water) and nonpenetrating (paraffin oil) media were used. Independently of the compressing medium, at HT, the lattice vibrational modes of apophyllite demonstrate regular pressure shifts. Almost uniform shift rates imply little differentiation between the compression of silicate layers and interlayer ion‐molecular assemblage. Similar HPbehavior of apophyllite in penetrating and nonpenetrating media indicates no pressure‐induced overhydration within 1–9 GPa. Thereby, the significance of such structural factors, as a limited H2O mobility and relatively strong contacts between silicate layers, determining low structure tolerance towards the penetration of additional molecules, is emphasized. The elevated temperature does not affect the mobility of the interlayer H2O molecules to allow the pressure‐induced intercalation in apophyllite.

Influence of the outflow initial parameters on the transverse dimensions of underxpanded argon jets in presence of condensation

The influence of the outflow initial parameters (stagnation pressure P0 and temperature T0, as well as the residual pressure in the background medium P∞) on the radii in the maximum cross sections of the «traditional» initial jet and the concurrent cluster flow («cluster wake») recently discovered by the authors is considered. The empirical dependencies proposed in the well-known studies of the gas dynamics of supersonic jets are verified, amendment models that take into account the features of the outflow of gases from a supersonic nozzle under condensation conditions are presented, assumptions about the reasons for the similarity of a «traditional» jet and an external «cluster wake» are made, limitations on the conditions for «cluster wake» formation are discussed.

Magnetic fields and relativistic electrons fill entire galaxy cluster

The hot plasma within merging galaxy clusters is predicted to be filled with shocks and turbulence that may convert part of their kinetic energy into relativistic electrons and magnetic fields generating synchrotron radiation. Analyzing Low Frequency Array (LOFAR) observations of the galaxy cluster Abell 2255, we show evidence of radio synchrotron emission distributed over very large scales of at least 5 megaparsec. The pervasive radio emission witnesses that shocks and turbulence efficiently transfer kinetic energy into relativistic particles and magnetic fields in a region that extends up to the cluster outskirts. The strength of the emission requires a magnetic field energy density at least 100 times higher than expected from a simple compression of primordial fields, presumably implying that dynamo operates efficiently also in the cluster periphery. It also suggests that nonthermal components may contribute substantially to the pressure of the intracluster medium in the cluster periphery.

Acid-based organosolv lignin extraction from wheat straw: Kinetic and structural analysis

Optimizing the pretreatment of lignocellulosic biomass is essential to obtain high purity fractions, and particularly a lignin polymer which can be easily used for further high-value applications. To better understand the changes in the chemical structure of lignin during its extraction and its kinetics, wheat straw was pretreated at mild conditions (105 °C, atmospheric pressure) in an organic acid-based organosolv medium. Lignin, collected for extraction times 0 to 3h30, was analyzed by different techniques (GPC, GC-FID and 31 P NMR) to determine its chemical structure and to quantify the modifications which could occur during the organosolv pretreatment (phenolic and total hydroxyl groups content, molecular weight, fragments condensation, esterification). The kinetics of lignin extraction was successfully assessed with the potential degree of delignification model. • Pretreatment of wheat straw in an acetic and formic acid based organosolv medium. • Providing new insights of organosolv lignin extraction mechanisms at atmospheric pressure. • Chemical characterization of lignin fragments over time. • Successful application of potential degree of delignification kinetic model.

Shale oil occurrence and slit medium coupling based on a molecular dynamics simulation

Although the state of occurrence and characteristics of shale oil form the basis for studying the mobility of shale oil, studies on the state of occurrence and characteristics of shale oil, as well as factors affecting its mobility, are presently lacking. Molecular dynamics simulation is a very effective method for studying the state of occurrence of shale oil and the factors affecting its mobility. We used molecular dynamics (MD) simulation to study the adsorption behavior and distribution of shale oil within a nanoscale slit medium. Results show that fluid density is not uniform throughout the slit and that its oscillation from the solid wall surface to the central plane is attenuated, indicating distinct adsorbed layers and bulk-phase fluid. We studied the effects of slit aperture, temperature, pressure, oil composition, and slit medium on the volumes and densities of the adsorbed layers. We found that (a) there were multiple adsorbed layers of liquid hydrocarbons, (b) the number of adsorbed layers depended largely on the slit medium, slit size, and oil composition, (c) the adsorption propensity of heavier hydrocarbons were more pronounced, and (d) the adsorption capacity of the slit medium differed for different types of hydrocarbon molecules.

A Closed-Form Equation for Capillary Pressure in Porous Media for All Wettabilities

A saturation–capillary pressure relationship is proposed that is applicable for all wettabilities, including mixed-wet and oil-wet or hydrophobic media. This formulation is more flexible than existing correlations that only match water-wet data, while also allowing saturation to be written as a closed-form function of capillary pressure: we can determine capillary pressure explicitly from saturation, and vice versa. We propose Pc=A+Btanπ2-πSeCfor0≤Se≤1,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P_{{\ ext{c}}} = A + B\ an \\left( {\\frac{\\pi }{2} - \\pi S_{e}^{C} } \\right)\\,{\ ext{for}}\\,0 \\le S_{{\ ext{e}}} \\le 1,$$\\end{document}where S_{{text{e}}} is the normalized saturation. A indicates the wettability: A>0 is a water-wet medium, A<0 is hydrophobic while small A suggests mixed wettability. B represents the average curvature and pore-size distribution which can be much lower in mixed-wet compared to water-wet media with the same pore structure if the menisci are approximately minimal surfaces. C is an exponent that controls the inflection point in the capillary pressure and the asymptotic behaviour near end points. We match the model accurately to 29 datasets in the literature for water-wet, mixed-wet and hydrophobic media, including rocks, soils, bead and sand packs and fibrous materials with over four orders of magnitude difference in permeability and porosities from 20% to nearly 90%. We apply Leverett J-function scaling to make the expression for capillary pressure dimensionless and discuss the behaviour of analytical solutions for spontaneous imbibition.