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Equations of plasticity of a porous body proposed by different authors and obtained under the condition that the yield surface of a porous body has the shape of an ellipsoid of revolution are considered in this paper. Such equations have two independent parameters which are the functions of relative density. Various theoretical dependences of these parameters on the relative density and, as a result, various equations for describing the die-compaction of powders are presented. It is shown that the correction of two density-dependent parameters, taking into account the initial density, makes it possible to significantly increase the accuracy of approximation of experimental data on the powder compaction process (PCP) of various powders. Among the considered "continuum" equations of powder die-compaction, the PCP to a density of 0.95 is the most accurately described by the equation in which the corrected Skorokhod's theoretical density functions are used and which contains one constant as a result. Another equation which contains four constants allows one to accurately (R2 > 0.9990–0.9999) describe the PCP to a density of >0.95. This equation is obtained by replacing one of two independent parameters in the traditional continuum equation with the lateral pressure coefficient followed by substituting, instead of those parameters, their dependencies on the density in the form of power function. The adequacy of the PCP description by this equation was verified by approximating experimental data on the die-compaction of iron powders to a relative density greater than 0.95, as well as highly plastic powders with a final density of ~1.0. [ABSTRACT FROM AUTHOR]

Equations of plasticity of a porous body proposed by different authors and obtained under the condition that the yield surface of a porous body has the shape of an ellipsoid of revolution are considered in this paper. Such equations have two independent parameters which are the functions of relative density. Various theoretical dependences of these parameters on the relative density and, as a result, various equations for describing the die-compaction of powders are presented. It is shown that the correction of two density-dependent parameters, taking into account the initial density, makes it possible to significantly increase the accuracy of approximation of experimental data on the powder compaction process (PCP) of various powders. Among the considered “continuum” equations of powder die-compaction, the PCP to a density of 0.95 is the most accurately described by the equation in which the corrected Skorokhod’s theoretical density functions are used and which contains one constant as a result. Another equation which contains four constants allows one to accurately (R2 > 0.9990–0.9999) describe the PCP to a density of >0.95. This equation is obtained by replacing one of two independent parameters in the traditional continuum equation with the lateral pressure coefficient followed by substituting, instead of those parameters, their dependencies on the density in the form of power function. The adequacy of the PCP description by this equation was verified by approximating experimental data on the die-compaction of iron powders to a relative density greater than 0.95, as well as highly plastic powders with a final density of ~1.0.

The technological process of vegetable oil production requires significant energy costs, while the introduction of new technologies requires investment, which is a challenge for small and medium-sized enterprises in the current environment. This makes it important to introduce energy-efficient equipment in the conditions of these enterprises, which does not require significant investments. The article was concerned with improving the technological process of pressing oilseeds by introducing an energy-efficient oil press into the technological process and studying its structural and kinematic characteristics. In the context of the study, the determination of the physical and mechanical properties of raw materials, methods of theoretical mechanics and solid mechanics, calculation of structural elements of technological equipment for processing oilseeds were used. The necessity and expediency of theoretical analysis and experimental research are substantiated. The main regularities of oil separation from the crushed mass are determined. The study of physical and mechanical characteristics, size and weight parameters of seeds and crushed mass allowed to substantiate the main kinematic and design parameters of the screw press. The principle of operation of an energy-efficient screw oil press is described. The design of the press is improved by a steam sprayer installed in the receiving hopper under the threaded rollers, which is equipped with a steam generator, which makes it possible to carry out moisture-thermal treatment with steam within one device. The proposed constructive solution includes: determination of the coefficient of friction of seeds on an inclined plane, study of the components of the crushed mass obtained with the help of an energy-efficient oil press, and theoretical aspects of oilseed pressing. A study of the design and operating parameters of the screw press has been carried out, namely: determination of the screw press productivity, use of an energy-efficient press for oil separation makes it possible to improve the quality of the technological process, determination of the press power consumption and its efficiency. It has been concluded that the improved design solution of the press meets the modern requirements for oil production machines. The use of the proposed constructive solution will reduce oil losses during pressing, which will significantly increase the efficiency of the process, reduce operating costs and promote the development of oil production in small and medium-sized oilseed enterprises. [ABSTRACT FROM AUTHOR]

This article presents the world energy situation, the importance of energy transition, and it further designates hydrogen as a potential replacement for natural gas. Moreover, the paper specifies that the energy transition will be carried out gradually, sustained by conventional resources. Hydrogen can be mixed with natural gasses in current networks, but additional risks must be considered. These risks prove to be minimal in the distribution sector if the hydrogen fraction is kept within acceptable limits, and if optimal operation and safety measures are enforced. The behavior of the hydrogen-natural gas mixture, also called HENG, is studied based on distinguishing the physical and chemical properties of hydrogen and natural gas. In order to analyze the true behavior of the mixture in a distribution network, a numerical simulation was undertaken, whose analysis shows that there is a tight connection between the concentration of hydrogen in the system, consumption, and linepack, and the operational limits of the network must be established based on these data. Knowing the behavior, strategies and regulations can be drafted in order to safely exploit natural gas-hydrogen distribution networks. However, every distribution network has its own particularities, which is why additional studies both at theoretical as well as practical level, performed on real distribution networks, are needed. [ABSTRACT FROM AUTHOR]

It is possible to calculate the oil film thickness and the pressure distribution on the Hertzian contact surface of bearings, gears, traction drives, etc. by the EHL theory by Dowson et al.. For these calculations, it is important to determine the high pressure viscosity and high pressure density of lubricant. In a previous report, I constructed a theory of the relationship between viscosity, temperature and pressure. And the van der Waals type viscosity equation was derived. Similarly, in this study, I constructed a theory of the relationship between density, temperature and pressure. As a result, it was found from the dimensional analysis that 1/3 power of density (line density) was negatively proportional to temperature. This linear equation was found to be a van der Waals type line density equation which consists of three eigen constants: absolute zero line density ρt=01/3, line density constant 1/G and pressure constant H/G. Furthermore, the pressure constant H/G of the line density equation is equivalent to the PR of the liquid state equation and the pressure constant C/B of the van der Waals type viscosity equation. And I report the results of estimating the high pressure density of various lubricants by the line density equation.

The well-known equations for the powder compaction process (PCP) in a rigid die published from the beginning of the last century until today were considered in this review. Most of the considered equations are converted into the dependences of densification pressure on the powder’s relative density. The equations were analyzed and their ability to describe PCP was assessed by defining the coefficient of determination when approximating experimental data on the compaction of various powders. It was shown that most of the equations contain two constants the values of which are determined by fitting the mathematical dependence to the experimental curve. Such equations are able to describe PCP with high accuracy for the compaction of powders up to a relative density of 0.9–0.95. It was also shown that different equations can describe PCP in the density range from the initial density to 0.9 with the same high accuracy, but when the process of compaction is extrapolated to higher values of density, the curves diverge. This indicates the importance of equations that can unambiguously describe PCP to a relative density equal to or close to 1.0. For an adequate description of PCP for relative density greater than 0.95, equations containing three or four constants have proven useful.

Based on the generalization of M. Yu. Balshin’s well-known equations in the framework of a discrete model of powder compaction process (PCP), two new die-compaction equations for powders have been derived that show the dependence of the compaction pressure p on the relative density ρ of the powder sample. The first equation, p=w(1−ρ0)(n−m)·(ρ−ρ0)n(1−ρ)m, contains, in addition to the initial density ρ0 of the powder in die, three constant parameters—w, n and m. The second equation in the form p=H1−ρ0b−c·ρ−ρ0b1−ρ0c−aρ−ρ0c also takes into account the initial density of the powder and contains four constant parameters H, a, b, and c. The values of the constant parameters in both equations are determined by fitting the theoretical curve according to these equations to the experimental powder compaction curve. The adequacy of the PCP description with these equations has been verified by approximating experimental data on the compaction of various powders, including usual metal powders such as iron, copper, and nickel, highly plastic powders such as tin and lead, a mixture of plastic powder (Ni) with non-plastic powder (Al2O3), nickel-plated alumina powder, as well as powder of a brittle compound, in particular titanium carbide TiC. The proposed equations make it possible to describe PCP with high accuracy, at which the coefficient of determination R2 reaches values from 0.9900 to 0.9999. The four-constant equation provides a very accurate description of PCP from start to finish when the density of the samples stops increasing once the pressure increases to an extremely high level, despite the presence of porosity.

A semi-empirical equation of state for bismuth has been developed taking into account five solid phases, the liquid phase, evaporation, and thermal ionization. The results of model calculations are in satisfactory agreement with data from static and dynamic experiments in the pressure range from atmospheric to 1 TPa and at temperatures from room temperature to 105 K. [ABSTRACT FROM AUTHOR]

Honey has great benefits to humans, both as medicine and food. It contains glucose, fructose and water in addition to small quantities of proteins, minerals, organic acids, and vitamins. Vacuum cooling is a rapid cooling technique based on the principle of evaporation, which lowers the boiling point of water based on the vacuum pressure inside a cooler room. A prototype vacuum-cooling jet water system was used to process the honey. Raw honey obtained from the forests of Riau was used in the present study. This study aimed to determine the effect of jet water vacuum cooling with variations in volume (V/V), capacity (12.5%, 25%, and 50%) on the quality of honey (Apis dorsata Fabricus) to accelerate the cooling process and preserve product quality. The cooling mechanical analysis parameters reviewed included the processing time and the lowest maximum pressure. The parameters of the quality of honey observed included moisture content, viscosity, density and total dissolved solids. As a result, the vacuum cooling process can suppress damage to the quality of honey owing to the heating process. At the cooling time and lowest maximum pressure value, the mechanical aspects of the water jet system vacuum cooling process showed the maximum results. The water contents of 12.5% (V/V), 25% (V/V) and 50% (V/V) filling were 13.69%, 12.89%, and 14.25%, respectively. The viscosities at 12.5% (V/V), 25% (V/V) and 50% (V/V) filling were 2.604 Pa.s, 2.355 Pa.s, and 1.644 Pa.s, respectively. Density with 12.5% (V/V), 25% (V/V) and 50% (V/V) filling were 1.52 g/cm3, 1.53 g/cm3 and 1.50 g/cm3, respectively. Total dissolved solid values of honey with 12.5 % (V/V), 25 % (V/V), and 50 % (V/V) fillings were 78.16%, 78.16% and 77.66%, respectively. Water jet vacuum cooling with a 25% chamber volume capacity accelerates honey with the best total dissolved solids, density and moisture content. Vacuum cooling can be used to improve product quality, shorten handling time, extend product shelf life and improve security. [ABSTRACT FROM AUTHOR]

Based on the generalization of M. Yu. Balshin's well-known equations in the framework of a discrete model of powder compaction process (PCP), two new die-compaction equations for powders have been derived that show the dependence of the compaction pressure p on the relative density ρ of the powder sample. The first equation, p = w (1 − ρ 0) (n − m) · (ρ − ρ 0) n (1 − ρ) m , contains, in addition to the initial density ρ0 of the powder in die, three constant parameters—w, n and m. The second equation in the form p = H 1 − ρ 0 b − c · ρ − ρ 0 b 1 − ρ 0 c − a ρ − ρ 0 c also takes into account the initial density of the powder and contains four constant parameters H, a, b, and c. The values of the constant parameters in both equations are determined by fitting the theoretical curve according to these equations to the experimental powder compaction curve. The adequacy of the PCP description with these equations has been verified by approximating experimental data on the compaction of various powders, including usual metal powders such as iron, copper, and nickel, highly plastic powders such as tin and lead, a mixture of plastic powder (Ni) with non-plastic powder (Al2O3), nickel-plated alumina powder, as well as powder of a brittle compound, in particular titanium carbide TiC. The proposed equations make it possible to describe PCP with high accuracy, at which the coefficient of determination R2 reaches values from 0.9900 to 0.9999. The four-constant equation provides a very accurate description of PCP from start to finish when the density of the samples stops increasing once the pressure increases to an extremely high level, despite the presence of porosity. [ABSTRACT FROM AUTHOR]

The well-known equations for the powder compaction process (PCP) in a rigid die published from the beginning of the last century until today were considered in this review. Most of the considered equations are converted into the dependences of densification pressure on the powder's relative density. The equations were analyzed and their ability to describe PCP was assessed by defining the coefficient of determination when approximating experimental data on the compaction of various powders. It was shown that most of the equations contain two constants the values of which are determined by fitting the mathematical dependence to the experimental curve. Such equations are able to describe PCP with high accuracy for the compaction of powders up to a relative density of 0.9–0.95. It was also shown that different equations can describe PCP in the density range from the initial density to 0.9 with the same high accuracy, but when the process of compaction is extrapolated to higher values of density, the curves diverge. This indicates the importance of equations that can unambiguously describe PCP to a relative density equal to or close to 1.0. For an adequate description of PCP for relative density greater than 0.95, equations containing three or four constants have proven useful. [ABSTRACT FROM AUTHOR]

The density of β-cyanopropionaldehyde, in a wide range of temperature and pressure was determined. Also, the heat capacity of that aldehyde at constant pressure and different temperatures was experimentally measured. The research has been cleared by different formulas. [ABSTRACT FROM AUTHOR]

The bending oscillation frequencies of a carbon nanotube (CNT) are determined using the semi-momentless theory. An expression for the distributed lateral load on CNT is derived under the assumption of its cylindrical bending. CNT surfaces come into contact with media of varying densities and pressures. The medium can be compressible during surface deformation and incompressible. The influence of average pressure and changes in the curvature of the middle surface, as well as the added mass of the gaseous medium, on the bending is determined. [ABSTRACT FROM AUTHOR]

This paper presents the developed mathematical model that describes the influence of pressure and velocity factors on changes in the product of the external friction and lateral pressure coefficients during the pressing of powdered materials in a closed die. As the pressing velocities in a closed die are rather low, this model considers the influence of only the velocity of slipping motion on the deformation component in shear strength calculations. Processing of experimental data was performed according to the least squares method using a third-order linear regression model. The results of the correlation analysis indicate a strong interaction between the product of the external friction and lateral pressure coefficients with pressing modes (pressure and velocity), as well as the independence of the velocity and pressure factors. [ABSTRACT FROM AUTHOR]

The measurement of seed cotton moisture regain (MR) during harvesting operations is an open and challenging problem. In this study, a new method for resistive sensing of seed cotton MR measurement based on pressure compensation is proposed. First, an experimental platform was designed. After that, the change of cotton bale parameters during the cotton picker packaging process was simulated through the experimental platform, and the correlations among the compression volume, compression density, contact pressure, and conductivity of seed cotton were analyzed. Then, support vector regression (SVR), random forest (RF), and a backpropagation neural network (BPNN) were employed to build seed cotton MR prediction models. Finally, the performance of the method was evaluated through the experimental platform test. The results showed that there was a weak correlation between contact pressure and compression volume, while there was a significant correlation (p < 0.01) between contact pressure and compression density. Moreover, the nonlinear mathematical models exhibited better fitting performance than the linear mathematical models in describing the relationships among compression density, contact pressure, and conductivity. The comparative analysis results of the three MR prediction models showed that the BPNN algorithm had the highest prediction accuracy, with a coefficient of determination (R2) of 0.986 and a root mean square error (RMSE) of 0.204%. The mean RMSE and mean coefficient of variation (CV) of the performance evaluation test results were 0.20% and 2.22%, respectively. Therefore, the method proposed in this study is reliable. In addition, the study will provide a technical reference for the accurate and rapid measurement of seed cotton MR during harvesting operations. [ABSTRACT FROM AUTHOR]

Risk assessment of hydrogen energy technologies is a necessary condition for the arrival of a hydrogen energy economy society. Currently, most methods for detecting hydrogen leaks use a single concentration or pressure sensor. Structural visualization and parametric diagnosis of complex flow fields cannot be solved simultaneously by a single detection method. The main objective of this work is to propose an advanced optical detection method to simultaneously monitor the outlet pressure and density field distribution during hydrogen leakage. For the detection of the density field distribution, we use double propagation of the laser beam in the hydrogen jet to improve the phase sensitivity and relay imaging of the object between each pass to maintain spatial resolution. Error analysis shows that the error of our proposed method is 2.47 %, which is within the error tolerance. The sensitivity analysis shows that our detection sensitivity is twice that of the conventional Mach-Zehnder interferometer. For the detection of outlet pressure, we propose a mathematical model in which the half-length axis of the laser spot is linearly related to the outlet pressure and use the deformation of the laser beam in the hydrogen jet to detect the outlet pressure. The results show that the hydrogen jet can be regarded as a gas-phase lens when detecting the outlet pressure, and the deformation of the laser beam profile in the horizontal direction increases linearly with the increase of the jet pressure. The results of the study can provide a reference for the detection of accidental hydrogen leakage and the improvement of hydrogen safety regulations. [ABSTRACT FROM AUTHOR]

Utilizing the Turbo C programming language, the atmospheric earth model is created from sea level to 86 km. This model has been used to determine atmospheric Earth parameters in this study. Analytical derivations of these parameters are made using the balancing forces theory and the hydrostatic equation. The effects of altitude on density, pressure, temperature, gravitational acceleration, sound speed, scale height, and molecular weight are examined. The mass of the atmosphere is equal to about 50% between sea level and 5.5 km. g is equal to 9.65 m/s² at 50 km altitude, which is 9% lower than 9.8 m/s² at sea level. However, at 86 km altitude, g is close to 9.51 m/s², which is close to 15% smaller than 9.8 m/s². These results have been compared with an international standard atmosphere. The presumed atmosphere model differs significantly from the actual atmosphere because weather fluctuations are not taken into consideration in this model. [ABSTRACT FROM AUTHOR]

The objective of this investigation is to find out the effect of the woven glass fiber reinforced polymer (GFRP) laminates with different glass fiber densities, such as 610 GSM and 210 GSM, and manufactured by the hand layup technique, supported by compression molding on mechanical properties and abrasive water jet (AWJ) drilling responses. During the investigation, the woven GFRP with a fiber density of 610 GSM has been found to display greater flexural strength, interlaminar strength (ILSS), and tensile strength as compared to the woven GFRP with a fiber density of 210 GSM. The woven GFRP with a fiber density of 610 GSM has also displayed reduced drilling damage in the surface region and less delamination compared to the woven GFRP with a fiber density of 210 GSM. The results of both types of composites prove that the TR and JP considerably impact the delamination extent (DE) and surface roughness (SR). A decrease in the TR and an increase in the JP are primarily responsible for optimizing the desired machining performances. Finally, a FESEM analysis has been done to examine the machined surfaces' morphology. [ABSTRACT FROM AUTHOR]

This study assesses quad-band metamaterial perfect absorbers (MPAs) based on a double X-shaped ring resonator for electromagnetic interference (EMI) shielding applications. EMI shielding applications are primarily concerned with the shielding effectiveness values where the resonance is uniformly or non-sequentially modulated depending on the reflection and absorption behaviour. The proposed unit cell consists of double X-shaped ring resonators, a dielectric substrate of Rogers RT5870 with 1.575 mm thickness, a sensing layer, and a copper ground layer. The presented MPA yielded maximum absorptions of 99.9%, 99.9%, 99.9%, and 99.8% at 4.87 GHz, 7.49 GHz, 11.78 GHz, and 13.09 GHz resonance frequencies for the transverse electric (TE) and transverse magnetic (TM) modes at a normal polarisation angle. When the electromagnetic (EM) field with the surface current flow was investigated, the mechanisms of quad-band perfect absorption were revealed. Moreover, the theoretical analysis indicated that the MPA provides a shielding effectiveness of more than 45 dB across all bands in both TE and TM modes. An analogous circuit demonstrated that it could yield superior MPAs using the ADS software. Based on the findings, the suggested MPA is anticipated to be valuable for EMI shielding purposes. [ABSTRACT FROM AUTHOR]

Brazilian regulation requires the test methods for analysing the shrinkage factor, and the solubility ratio in crude oils must be estimated under the measurement conditions for appropriation. Since these physicochemical parameters depend upon the density, a Brazilian oil company proposed an adapted and more user-friendly methodology for adjusting the digital density meter under high pressure and temperature conditions. This study aimed to evaluate the metrological compatibility of this proposal by comparing it with the fit model presented by a manufacturer of a digital densimeter and with the tabulated reference values of fluid density. Since the density data behaviour presented non-normal distributions, the Wilcoxon signed-rank test showed metrological compatibility between the approaches studied in the pressure range from 0 psi to 1200 psi (8.273709 MPa) and the temperature range from 5 °C to 70 °C. [ABSTRACT FROM AUTHOR]

In this model, we use the C++ programming language to develop a program that calculates the atmospheric earth model from the surface to 250 kilometers. The balance forces theory is used to derive the pressure equation. The hydrostatic equation is utilized to calculate these parameters analytically. Variations of the parameters with altitude (density, pressure, temperature, and molecular weight) are investigated intensively. The equations for gravitational acceleration, sound speed, and scale height are also obtained. This model is used to investigate the effects of the earth's atmosphere on the space shuttle and the moving bodies inside it. [ABSTRACT FROM AUTHOR]

The productivity of the feed preparation line and its technical and economic efficiency are affected by the design and technological parameters of the equipment. The geometry of the expander screw and its operating modes are no exception. To reduce the specific energy consumption of the expander, it is necessary to establish its rational design and operating parameters. This can be done using analytical calculation methods that consider the mechanisms of movement and destruction of solid substances. Modelling using the discrete element method is becoming increasingly common to describe the movement of solid components in granulators, extruders, or expanders. The purpose of the study is to improve the physical and mathematical apparatus of movement of solid feed components in the screw channel of the feed expander and develop a method for its numerical modelling. Numerical modelling was performed using a model of the movement of a multiphase Euler mixture with a split flow in three-dimensional space. In this case, the motion was subject to an admissible two-layer k-ε model of turbulence and the multiphase equation of state. The physical and mathematical apparatus for the movement of solid feed components in the screw channel of the feed expander was improved, which is the basis for the numerical modelling technique in the Star-CCM+ software suite, based on the fact that the conglomerate of feed components is represented as a package of spherical particles. In this case, the pressure force must be compensated by the total force of contact interaction of particles with each other and the wall. Preliminary numerical modelling of the process of expanded feed preparation was performed in the Star-CCM+ software suite. The practical significance lies in the fact that the improved physical and mathematical apparatus and the developed method of numerical modelling of the feed expander operation process allow substantiating its design and regime parameters to ensure low specific energy consumption without losing the quality of the technological process

Based on the assumption about the initial deformed shape of the cross section of the pipeline, cylindrical shell, carbon nanotube (CNT) without initial stresses, the critical pressures inside and outside these structural elements are determined. The static interaction of instabilities under the action of the above factors is studied. [ABSTRACT FROM AUTHOR]

The previously developed wide-range multiphase equation of state for Fe was used to calculate the shock pressure leading to vaporization of iron under isentropic unloading to 10-4 GPa (1 atm). Calculations were made for three initial states of the material: pressure 1 atm and temperature 298 K ("cold" initial state), 1 GPa and 1500 K ("warm" state), and 40 GPa and 4000 K ("hot" state). The shock pressure is 359, 261, and 132 GPa, respectively. These values are generally lower than the estimates by other authors. Arguments in support of the obtained values are provided. [ABSTRACT FROM AUTHOR]

The measurement of seed cotton moisture regain (MR) during harvesting operations is an open and challenging problem. In this study, a new method for resistive sensing of seed cotton MR measurement based on pressure compensation is proposed. First, an experimental platform was designed. After that, the change of cotton bale parameters during the cotton picker packaging process was simulated through the experimental platform, and the correlations among the compression volume, compression density, contact pressure, and conductivity of seed cotton were analyzed. Then, support vector regression (SVR), random forest (RF), and a backpropagation neural network (BPNN) were employed to build seed cotton MR prediction models. Finally, the performance of the method was evaluated through the experimental platform test. The results showed that there was a weak correlation between contact pressure and compression volume, while there was a significant correlation (p < 0.01) between contact pressure and compression density. Moreover, the nonlinear mathematical models exhibited better fitting performance than the linear mathematical models in describing the relationships among compression density, contact pressure, and conductivity. The comparative analysis results of the three MR prediction models showed that the BPNN algorithm had the highest prediction accuracy, with a coefficient of determination (R2) of 0.986 and a root mean square error (RMSE) of 0.204%. The mean RMSE and mean coefficient of variation (CV) of the performance evaluation test results were 0.20% and 2.22%, respectively. Therefore, the method proposed in this study is reliable. In addition, the study will provide a technical reference for the accurate and rapid measurement of seed cotton MR during harvesting operations.

In hydrogenation and dehydrogenation processes of liquid organic hydrogen carriers (LOHCs), molecular hydrogen (H 2) is present, but its influence on the thermophysical properties of the LOHC compounds is still hardly known. This study provides experimental results from surface light scattering and predictions from molecular dynamics simulations on the influence of dissolved H 2 on the liquid viscosity, interfacial tension, and liquid density of the LOHC system based on diphenylmethane at varying degree of hydrogenation, process-relevant temperatures up to 573 K, and pressures up to 7 MPa. First-time measurements of the viscosity of bicyclic hydrocarbon compounds in the presence of dissolved H 2 at saturation conditions reveal a negligible effect of pressure. The interfacial tension decreases independently of the LOHC composition by about 6% at 7 MPa. The simulations can adequately represent the effect of H 2 on the interfacial tension and evidence a weak enrichment of H 2 at the interface. [Display omitted] • Experimental and simulation data on thermophysical properties up to 523 K and 7 MPa. • Negligible effect of dissolved hydrogen on viscosity of diphenylmethane-based LOHCs. • Decreasing interfacial tension with increasing hydrogen pressure by up to 6%. • Surface enrichment of hydrogen molecules in LOHCs evidenced by simulations. • Simulations can describe the influence of H 2 on the interfacial tension and density. [ABSTRACT FROM AUTHOR]

Water phase-change is of importance to many applications including energy conversion, thermal management of electronics, and medical therapies. Augmenting the rate of phase-change by application of an electric field is of interest in many situations and may lead to increased effectiveness of energy transfer. Thus, it is important to develop a better understanding of the effect of an electric field on the thermodynamic properties of water. In this work, molecular dynamics (MD) was utilized to assess two distinct water models, the TIP4P-Ew and the SWM4-NDP, for predicting the effect of an electric field on the density and the enthalpy of vaporization of water. Both water models possess rigid molecular geometry. However, the SWM4-NDP model has a negatively charged Drude particle (the "NDP") attached to the oxygen site in the water molecule, making the SWM4-NDP model polarizable. The objective is to understand if the polarizability of the water model has a significant effect when predicting the two properties of interest. Applying an electric field in MD simulations with each water model resulted in increased values for both the density and enthalpy of vaporization. The magnitude of these increases is comparable between water models and grows with applied field strength. Corresponding electrostriction pressure attributed to the applied field is well below values predicted by analytical models. [ABSTRACT FROM AUTHOR]

Using the previously established dependence of the excess viscosity on the internal energy density, a simple low-parameter equation was obtained to describe the krypton viscosity coefficient in a wide range of state parameters. It was shown that the proposed low-parameter equation for calculating the viscosity coefficient of liquid and gas allows for reliable extrapolation beyond the limits of the studied area. [ABSTRACT FROM AUTHOR]

The article focuses on the study of medium density sand and sandy loam density changes during water-cement solute injection and pressiometer expansion. Cement mortar injection is performed into boreholes under small pressure of up to 300 KPa resulting in radial well expansion. This expansion process also takes place during pressiometer studies. A cavity of compacted soil is formed around the expended boreholes in radial direction; the anchor and pile load determine field studies of the load, which they can perceive along lateral surface. It is worth noting that they frequently do not coincide with the calculated values. Following field anchor excavations, it was observed that root shearing can occur both directly at the contact between the cement root and the soil and at some distance from it. Subsequent laboratory studies revealed that when the soil is pressed, its density can change along a sinusoid, comprising pressed zones and decompaction zones. This gives rise to the displacement of the shear zone at the contact between the root and the soil. [ABSTRACT FROM AUTHOR]

An experimental methodology for determining the product of the external friction coefficient and the lateral pressure coefficient depending on the compacting pressure is proposed. The results of powder materials testing show that the values of the product of the external friction coefficient and the lateral pressure coefficient have strong correlation with the compacting pressure in the pressure range of 30-350 MPa. The hypothesis about the external friction coefficient and the lateral pressure coefficient product constancy (when the compacting pressure changes) has not been experimentally confirmed; however, it can be implemented for some powder materials in a limited compacting pressure range. [ABSTRACT FROM AUTHOR]

The productivity of the feed preparation line and its technical and economic efficiency are affected by the design and technological parameters of the equipment. The geometry of the expander screw and its operating modes are no exception. To reduce the specific energy consumption of the expander, it is necessary to establish its rational design and operating parameters. This can be done using analytical calculation methods that consider the mechanisms of movement and destruction of solid substances. Modelling using the discrete element method is becoming increasingly common to describe the movement of solid components in granulators, extruders, or expanders. The purpose of the study is to improve the physical and mathematical apparatus of movement of solid feed components in the screw channel of the feed expander and develop a method for its numerical modelling. Numerical modelling was performed using a model of the movement of a multiphase Euler mixture with a split flow in three-dimensional space. In this case, the motion was subject to an admissible two-layer k-ε model of turbulence and the multiphase equation of state. The physical and mathematical apparatus for the movement of solid feed components in the screw channel of the feed expander was improved, which is the basis for the numerical modelling technique in the Star-CCM+ software suite, based on the fact that the conglomerate of feed components is represented as a package of spherical particles. In this case, the pressure force must be compensated by the total force of contact interaction of particles with each other and the wall. Preliminary numerical modelling of the process of expanded feed preparation was performed in the Star-CCM+ software suite. The practical significance lies in the fact that the improved physical and mathematical apparatus and the developed method of numerical modelling of the feed expander operation process allow substantiating its design and regime parameters to ensure low specific energy consumption without losing the quality of the technological process [ABSTRACT FROM AUTHOR]

The lowest frequency of bending vibrations of a plate in contact with a liquid or gas is determined. The derivation of the expression for the distributed transverse load on the plate is given under the assumption of its cylindrical bending. The plate surfaces are in contact with a medium of different density and pressure. The medium can be compressible during surface deformation and incompressible. The influence on the bending of the interaction of the average pressure and changes in the curvature of the middle surface, as well as the added mass of the gaseous medium, is determined. [ABSTRACT FROM AUTHOR]

Temperature (T), pressure (p), and density (ρ) are fundamental variables describing the atmospheric behavior. This study investigates the interdependence of these variables near Earth's surface in real-world conditions, by evaluating data from different European weather stations. It has been found that the correlation between pressure and temperature is strongly related to the dynamics of the PBL that facilitates a two-group classification. The first group includes all the stations in the plain or in the valley-floor and exhibits a weak correlation, R(p,T). 2D density plots representing hourly pressure against temperature have a distinctive triangular shape at these stations. Regardless of location, the upper boundary of this triangle consistently fits a linear equation with a constant slope and an intercept that scales with the average pressure of the station. This finding holds promising implications for enhancing the quality check of pressure and temperature data, enabling the identification of implausible measurements using a unified equation. In contrast, the second group includes stations with a strongly positive correlation R(p,T) and a more linear density plot; it includes all stations near a mountain-top. Their correlations exhibit identical features when compared to radiosounding data extracted at corresponding heights. The study concludes that: i) the first group of stations is significantly influenced by non-hydrostatic processes such as turbulence, friction and surface radiative heating/cooling in the PBL, resulting in weakly negative R(p,T) for shorter timescales that become null over longer durations; ii) the second group of stations has R(p,T) characteristics similar to the free atmosphere, predominantly regulated by hydrostatic balance and the advection of sensible heat. • R(p,T) depends on altitude, latitude, timescale and PBL development. • Density and temperature are always strongly negatively correlated. • p-T densityplots have a peculiar triangular shape for plain/valley stations. • For these stations a linear equation fits the upper bound of the triangle. • Mountain-top stations have strong positive R(p,T) like soundings in free troposphere. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of the displacing ability of porous media in extraction of hydrocarbons from the latter. Using the laws of mass and momentum conservation, the expression for the coefficient characterizing the displacing ability of the medium in the resilient mode of deposit exploitation has been refined. It is shown that the found expression differs from the classical concepts, as well as from the value of the compressibility coefficient of the porous medium in the filtration approximation. It has been established that, in the general case, the compressibility of a porous medium includes terms that depend not only on the macroscopic characteristics, but also on the microstructure of the porous medium. Criteria are determined, under which the elastic properties of the medium do not depend on its microstructure: when the densities of the liquid and of the skeletal material are equal and when the porosity is independent of pressure, then the pore structure does not affect the compressibility of the porous medium. Various physical conditions of the process are identified, when it is necessary to introduce special concepts of compressibility. It is shown that when the porosity decreases to zero, the value of the coefficient characterizing the displacing ability of the medium reaches the values that significantly exceed the compressibility of the liquid. At the same time, as the porosity tends to unity, this coefficient tends to the value of liquid compressibility. This behavior of the coefficient indicates the existence of a physical effect consisting in the predominant contribution of skeletal material deformation to the displacement process in the areas of the reservoir of oil and gas with a reduced porosity. [ABSTRACT FROM AUTHOR]

Buoyant shear layers encountered in many engineering and environmental applications have been studied by researchers for decades. Often, these flows have high Reynolds and Richardson numbers, which leads to significant/intractable space-time resolution requirements for direct numerical simulation (DNS) or large eddy simulation (LES). On the other hand, many of the important physical mechanisms, such as stress anisotropy, wake stabilization, and regime transition, inherently render eddy viscosity-based Reynolds-averaged Navier-Stokes (RANS) modeling inappropriate. Accordingly, we pursue second-moment closure (SMC), i.e., full Reynolds stress/flux/variance modeling, for moderate Reynolds number nonstratified, and stratified shear layers for which DNS is possible. A range of submodel complexity is pursued for the diffusion of stresses, density fluxes and variance, pressure strain and scrambling, and dissipation. These submodels are evaluated in terms of how well they are represented by DNS in comparison to the exact Reynolds-averaged terms, and how well they impact the accuracy of full RANS closure. For the nonstratified case, SMC model predicts the shear layer growth rate and Reynolds shear stress profiles accurately. Stress anisotropy and budgets are captured only qualitatively. Comparing DNS of exact and modeled terms, inconsistencies in model performance and assumptions are observed, including inaccurate prediction of individual statistics, non-negligible pressure diffusion, and dissipation anisotropy. For the stratified case, shear layer and gradient Richardson number growth rates, and stress, flux and variance decay rates, are captured with less accuracy than corresponding flow parameters in the nonstratified case. These studies lead to several recommendations for model improvement. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the combined effects of moisture content (MC) and pressure on the changes in bulk density of triticale grain under compaction at conditions typical of those seen in storage structures and to develop mathematical models to describe the compression behavior. Triticale compaction was measured at three MCs (8%, 12%, and 16% wet basis) and four compaction pressures (7, 14, 34, and 55 kPa) using a square metal box based on the design used in an earlier study by Thompson and Ross. Data from the compaction tests were used to calculate bulk densities for the three MCs and four pressures. Bulk densities were found to be significantly (p < 0.0001) dependent on both MC and pressure. Bulk densities varied with increasing MC, as has been observed in similar studies for other agricultural grains such as rye and wheat. These results provide guidance for estimating the bulk density of triticale in bins and other storage structures. The Verhulst logistic equation was found to best describe the changes in bulk density of triticale caused by rearrangement of the grain kernels at lower pressures for the three MCs. At higher pressures, the grain was observed to be more compliant, and Hooke's law was used to accurately describe the observed changes. Data from the compaction tests were used to estimate the model parameters, with a correlation coefficient (R2) of 0.986. The model was then used in WPACKING to compare the results of this study to pack factor predictions for triticale and wheat. WPACKING is a computer program that is the basis for ASABE Standard S413. The results of this comparison showed that this method can be used with the methods of ASABE Standard S413 to predict the quantity of triticale grain stored in bins. [ABSTRACT FROM AUTHOR]

The aim of the study is to determine the basic geometric dimensions and design parameters of the spray hopper, to obtain a mathematical model of the distribution and deposition of particle flow. The authors conducted experimental modeling of the flow, determining the concentration of particles and their deposition of the substrate, determined the influence of the geometric solution of the installation hopper on the main aerodynamic characteristic. The results of the work enable to quickly determine the distribution of particles in the flow, the density of the fluid, and other indicators affecting the characteristics of multilayer thermal insulation materials. Объектом исследования является конструкция бункера, который входит в состав аэродинамического устройства. Целью исследования является определение основных конструктивных параметров бункера напыления, факторов влияния на стабильность процесса формирования материалов, получения математической модели аэродинамического на- несения мелкодисперсных частиц на подложку. Авторами проведено экспериментальное моделирование аэродинамического процесса напыления, установлены зависимости основных аэродинамических характеристик от конструктивного решения бункера установки, оптимальных технических параметров, обеспечивающих максимальную поверхностную плотность многослойного текстильного материала. Результаты работы позволяют оперативно определить аэродинамические свойства потока, влияющие на характеристики многослойных теплоизоляционных материалов, текстильных композиционных материалов.

Due to the absence of experimental data for constructing the phase diagram of a liquid and gaseous mixture of hydrogen and oxygen, it is determined by modeling. The model diagrams previously predicted (Deiters et al., 1993) by two methods (I and II) at pressures up to 100 MPa and a temperature up to 100 K have significant differences, which are considered by the authors as an approximate measure of the uncertainty of the knowledge of the real phase diagram of this mixture. In this paper, the phase diagram of a mixture of hydrogen and oxygen is determined using the previously proposed modified van der Waals model for individual and mixed compounds. Calculations were performed in two variants (A and B) differing in the binary interaction parameter. To control these variants, model diagrams were determined for mixtures of hydrogen with nitrogen, argon, and methane, for which there are experimental data in the range of pressures and temperatures comparable to those mentioned above for a mixture of hydrogen and oxygen. Variant B is more realistic as it is in better agreement with experiment than variant A. The phase diagram calculated by method B for a mixture of hydrogen and oxygen is close to the calculation by method I, which indicates that it is more realistic than method II. [ABSTRACT FROM AUTHOR]

In this work, we reported values of speed of sound and density of the methyl caprate + methyl oleate binary system over the whole composition range from 0 % to 100 % for pressures ranging from 0.1 MPa to 70 MPa and at 303.15 K. A pulse-echo technique working by reflection was used to measure the speed of sound w at 3 MHz. A vibrating U-tube densimeter was used to obtain density data. From the combination of both these measurements, the isothermal and isentropic compressibilities were determined. Finally, the speed of sound molecular weight product and the molecular compressibility κ m , also known as Wada's constant, were calculated and represented as function of molar fraction in order to determine the best combining rule for predicting the speed of sound of the mixture from pure Fatty Acid Methyl Ester properties. [ABSTRACT FROM AUTHOR]

Abstract Real foams can be viewed as geometrically well-organized dispersions of more or less spherical bubbles in a liquid. When the foam is so drained that the liquid content significantly decreases, the bubbles become polyhedral-like and the foam can be viewed now as a network of thin liquid films intersecting each other at the Plateau borders according to the celebrated Plateau’s laws. In this paper we estimate from below the surface area of a spherically bounded piece of a foam. Our main tool is a new version of the divergence theorem which is adapted to the specific geometry of a foam with special attention to its classical Plateau singularities. As a benchmark application of our results, we obtain lower bounds for the fundamental cell of a Kelvin foam, lower bounds for the so-called cost function, and for the difference of the pressures appearing in minimal periodic foams. Moreover, we provide an algorithm whose input is a set of isolated points in space and whose output is the best lower bound estimate for the area of a foam that contains the given set as its vertex set.

This research investigates the performance of medium density fiberboard (MDF) with respect to hot press parameters. The performance of the board, type of glue, and production efficiency determine the optimum temperature and pressure for hot pressing. The actual temperature of the hot press inside the MDF board determines the properties of the final product. Hence, the optimal hot press parameters for the desired product are experimentally obtained. Moreover, MDF is experimentally investigated in terms of its vertical density profile, bending, and internal bonding under the various input parameters of temperature, pressure, cycle time, and moisture content during the manufacturing process. The experimental study is carried out by varying the temperature, pressure, cycle time, and moisture content in the ranges of 200–220 °C, 145–155 bar, 260–275 s, and 8–10%, respectively. Consequently, the optimum input parameters of a hot-pressing temperature of 220 °C, pressure of 155 bar, cycle time of 256 s, and moisture content of 8% are identified for the required internal bonding (0.64 N/ mm 2 ), bending (32 N/ mm 2 ), and increase in both the core and peak density of the vertical density profile as per the ASTM standard. [ABSTRACT FROM AUTHOR]