Gas Law Research Articles

Assessment of Multi-Physical Fields Reconstruction Approaches in Three-Dimensional Supersonic Flow with Shocks

The paper evaluates the application of several multi-physical fields reconstruction approaches based on the Tomographic Particle Image Velocimetry (PIV) in three-dimensional supersonic flows with shock waves, including the pressure, temperature, and density. The MacCormack method and the Flux Vector Splitting method with outstanding performance in two-dimensional supersonic flow are extended into three-dimensional forms. The conventional Poisson method is also considered because of its widespread application and high accuracy in subsonic and transonic flow. All of these approaches are established by the conservative Navier-Stokes equations and solved by the time-marching iteration process, combined with the perfect gas law and adiabatic flow assumption. The performances are evaluated by numerical velocimetry data. To simulate the typical three-dimensional features, the cases of uniform freestream at Mach 0.78 and 3 past a cone with a 20° half-angle are selected to obtain a sufficient spanwise velocity component. The results confirm the feasibility of the PIV-based reconstruction methods in the conical flow field. The conventional Poisson method performs well only in the subsonic case while the Flux Vector Splitting method has a better performance in supersonic flow, including higher accuracy, stability, and efficiency, with a low-level root-mean-square error of 0.449% and local maximum relative error of 1%.

Blood viscometer using capillary blood flow under disposable compliance pump

Blood viscosity is considered a promising indicator of cardiovascular disease and helps predict disease risks. However, conventional methods require two highly precise pumps to maintain consistent flow rates in co-flowing streams. In this study, a low-cost and disposable compliance pump was fabricated by inserting three components (a syringe needle, a blood-loaded syringe, and an air compliance unit [ACU]) into a three-way valve. Since the pump induces transient blood flow, accurately obtaining the transient flow rate is necessary. A correction factor was employed to improve the blood velocity obtained by microparticle image velocimetry. Air pressure inside the ACU was estimated using the ideal gas law. A discrete fluid circuit model was constructed to estimate the flow rate and pressure in a microfluidic channel. Four types of fluid physical properties (fluid resistance, fluid viscosity, time constant, and compliance coefficient) were obtained by analysing flow rate and pressure. The proposed method was employed to detect several types of suspended blood (variations in haematocrit, thermal-shocked RBCs, and RBC aggregation-enhanced blood). From the quantitative comparison, the proposed method provides better results than the previous method. Therefore, the proposed method is a promising tool for detecting biophysical variations in suspended blood.

Mechanisms associated with sulfidation gas release, desulphurisation and degradation of rubber powder in crumb rubber modified asphalt

ABSTRACT Odorous sulphidation gases are released during the construction of crumb rubber-modified asphalt (CRMA), causing pollution to the environment. To study the associated mechanism of sulfidation gas (H2S, CH4S, COS and CS2) release and the desulphurisation and degradation of CR in asphalt, the release law of sulphidation gas of CRMA was studied by a gas detector. Gel permeation chromatography (GPC), fluorescence microscope, toluene insoluble (TI) and potentiometric titration tests were used to study the desulphurisation and degradation of CR. The results showed that vulcanised CR in CRMA led to the generation of sulphidation gas with the increase in temperature, time and stirring speed. The average molecular weight of CRMA increased, while the TI and unsaturation (A) decreased after the desulphurisation and degradation of CR. Under the influence of temperature, heating time and stirring speed, the A was reduced by 0.72%∼8.87%, 1.18%∼10.69% and 0.75%∼8.12%, respectively. There was a strong correlation between the concentration of sulphidation gas and the desulphurisation and degradation parameters of CRMA. The reaction of ·H, –CH3, CO with the –SxH generated by the C–S, S–S, C=C fracture during the desulphurisation and degradation of CR was the main reason for the generation of sulphidation gas.

Analysis of the influence of temperature on the adsorption characteristics of coal: Insights into low-temperature outburst prevention

To investigate the impact of temperature reduction on the adsorption characteristics of coal gas, isothermal adsorption experiments were conducted with environmental temperature and moisture content as variables. The changing patterns of coal gas adsorption characteristics, adsorption theories, and the temperature response of gas expansion were analyzed. Furthermore, engineering measures for preventing gas outbursts in low-temperature frozen coal seams were discussed. The research findings indicate that the gas adsorption capacity of coal samples increases with decreasing temperature. When the temperature decreases from 20 to −20 °C, the gas adsorption capacity decreases from 34.48 to 19.90 cm3/g. At the same pressure, the adsorption capacity of coal is negatively correlated with temperature. The Langmuir theoretical model better reflects the adsorption law of coal gas under different environmental temperature conditions, wherein the adsorption constant “a” gradually decreases with the increase in environmental temperature. In a closed space, the gas pressure decreases with the decrease in coal sample temperature. Under the new adsorption equilibrium, the gas pressure in the coal sample tank decreases linearly with temperature. Coal samples with different moisture contents exhibit varying degrees of decrease in gas pressure at the same temperature, with higher moisture content resulting in a smaller decrease in gas pressure. Gas expansion energy decreases linearly with the decrease in coal temperature, indicating a proportional relationship between gas expansion energy and coal gas release pressure. As the temperature decreases, the gas pressure decreases. Based on the experimental results, a synergistic approach for preventing gas outbursts through low-temperature freezing is proposed.

Acid-Extracted Hydrocarbon Anomalies and Significance in the Chaoshan Depression of the Northern South China Sea

To predict the favorable zones and the types of reservoirs, acid extraction has been used in the Chaoshan depression to detect trace amounts of light hydrocarbons, heavy hydrocarbons, and the δ 13C (‰) of methane. As a result, two integration anomalous zones for exploration activity were blocked out in the northeastern and southwestern parts of the Chaoshan Depression, respectively. By analyzing the differentiation law and structural characteristics of hydrocarbon gases, as well as the stable carbon isotope ratio of methane, the underlying reservoirs were predicted to be gas reservoirs, and the seismically interpreted Dongsha-A (DS-A) structure was predicted to be a gas-rich structure. By correlating the seismic profile and geochemical anomalies, it was determined that fault planes and micro-fractures are the main controlling factors for the occurrence of the seabed’s geochemical anomalies. A composite formation mechanism of “lower generation, upper accumulation and micro fractures leaking” is proposed for the control of the underlying petroleum reservoirs, as well as for the micro-fracture control of permeability and surface adsorption control. Acid-extracted hydrocarbon anomalies have favorable indicating significance for exploration activity.

Finite element modeling of thermal‐hydro‐mechanical coupled processes in unsaturated freezing soils considering air‐water capillary pressure and cryosuction

AbstractThis paper presents a comprehensive computational model for analyzing thermo‐hydro‐mechanical coupled processes in unsaturated porous media under frost actions. The model employs the finite element method to simulate multiphase fluid flows, heat transfer, phase change, and deformation behaviors. A new soil freezing characteristic curve model is proposed to consider the suctions from air‐water capillary pressure and water‐ice cryosuction. A total pore pressure with components from liquid water pressure, air pressure, and ice pressure is used in the effective stress law. Vapor and dry air are considered miscible gases, utilizing the ideal gas law and Dalton's law. The governing equations encompass the linear momentum balance equation, the energy balance equation, and mass conservation equations for water species (ice, liquid, and vapor) and dry air. Weak forms are formulated based on primary variables of displacement, water pressure, air pressure, and temperature. The spatial discretization is achieved through the finite element method, while temporal discretization employs the fully implicit finite difference method, resulting in a system of fully coupled nonlinear equations. To verify the proposed computational model, a numerical implementation is developed and validated against a set of experimental data from the literature. The successful verification demonstrates the robustness of the model. A detailed discussion of the contributions from phase change strain and different sources of pore pressure is also addressed.

Energy-information trade-off induces continuous and discontinuous phase transitions in lateral predictive coding

Lateral predictive coding is a recurrent neural network that creates energy-efficient internal representations by exploiting statistical regularity in sensory inputs. Here, we analytically investigate the trade-off between information robustness and energy in a linear model of lateral predictive coding and numerically minimize a free energy quantity. We observed several phase transitions in the synaptic weight matrix, particularly a continuous transition that breaks reciprocity and permutation symmetry and builds cyclic dominance and a discontinuous transition with the associated sudden emergence of tight balance between excitatory and inhibitory interactions. The optimal network follows an ideal gas law over an extended temperature range and saturates the efficiency upper bound of energy use. These results provide theoretical insights into the emergence and evolution of complex internal models in predictive processing systems.

Study on the secondary oxidation behavior and microscopic characteristics of oxidized coal gangue.

Spontaneous combustion of coal gangue (CG) hills has caused varieties of secondary disasters that seriously endanger the ecological environment of the world. The emission law of index gases and their oxidation kinetics during the secondary oxidation process of CG with different ranks of oxidation were studied by using the temperature programmed device and online mass spectrometer (MS). Fourier transform infrared spectroscopy (FTIR) was used to reveal the changes of the CG internal active functional groups. The results showed that the energy required for the combustion of CG with low rank of pre-oxidation was significantly lower than that of the raw sample. However, as the oxidation rank increased, due to amounts of volatile components were released in the process of oxidation reaction, the CG in the combustion process of the emission of index gases and its oxygen consumption rate gradually reduced; the rapid oxidation stage shifted to the direction of the high temperature. In this study, the risk of spontaneous combustion of CG after oxidation at 80℃ under 3% oxygen concentration was the strongest. The results of this paper are of great guiding significance for exploring the spontaneous combustion characteristics of CG hills and their prevention by traditional covering method.

A multi-decadal time series of upper stratospheric temperature profiles from Odin-OSIRIS limb-scattered spectra

Abstract. A new upper stratospheric (35–60 km) temperature data product has been produced using Optical Spectrograph and InfraRed Imager System (OSIRIS) limb-scattered spectra that now spans over 22 years. Temperature is calculated by first estimating the Rayleigh scattering signal and then integrating hydrostatic balance combined with the ideal gas law. Uncertainties are estimated to be 1–5 K, with a vertical resolution of 3–4 km. Correlative comparisons with the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) and the Microwave Limb Sounder on Aura (MLS) are consistent with these uncertainty estimates and generally have no regions of statistically significant drift. The data product has been publicly released as part of the nominal OSIRIS v7.3 processing.

Gatekeeper model for ion selective membranes

A two-parameter model describes the resistance of a membrane challenged with different salt concentrations on either side of the membrane. This model treats the membrane as a circuit consisting of a resistor located between two switches. One switch is on the diluate side of the membrane. The second switch is on the concentrated side. The probability of the diluate side switch being active (loaded with a counter-ion) is β (dimensionless) and the probability of the switch being active (loaded with a counter-ion) on the concentrated side is γ (dimensionless). The probability of the circuit being active is the product of the probabilities βγ in which case the circuit is actively transporting a counter-ion across the membrane. The probability functions are calculated from the conductivity of the diluate λD (mS/cm), the concentrate λC (mS/cm) and a fitted parameter {Ksat} (mS/cm). The functions are β = λD/(λD +{Ksat}) and γ = λD/(λD + {Ksat}). These functions derived from enzyme kinetics where {Ksat} is analogous to the Michaelis-Menton saturation coefficient. The second fitted parameter is the minimum resistance rmin (Ωˑcm2) representing the case where the product βγ approaches unity (λD and λC ≫ {Ksat}). The product of the minimum resistance rmin and the applied voltage is analogous to the reciprocal of the maximum rate of an enzyme reaction. The resistance of the membrane rmem (Ωˑcm2) is rmem = rmin/(βγ). Measurements made with equal salt solutions on both sides of the membrane are used to calculate the resistance under any salt conditions. The probability functions β and γ represent the relative activity of the counter-ions on the surfaces of the membrane. This suggests that the Nernst potential across the membrane vmem (Volts) is expressed as vmem= (ɌT/Ƒ)ˑln (γ/β) where Ɍ (8.314 J/°K⋅mol) is the gas law constant, T (°K) is the temperature, and Ƒ (96,485 C/mol) is the Faraday constant. The current density (A/cm2) generated across the membrane under reverse electrodialysis conditions is i = vmem/rmem and the power density P (W/cm2) is P = i2rmem. It is, therefore, possible to estimate the performance of a membrane from a limited data set of resistance data such as may be found in the literature.

Analysis and Calculation of Two-Phase Flow in Industrial Pipelines Using Regime Classification

The analysis shows that using regime classification for individual phases, it is possible to obtain a more reliable design scheme for two phase flows. In contrast to the flow structure, the concept of mode is more accessible for calculating an industrial pipeline. In this case, transient processes can be determined and calculated. The analysis shows that in field conditions it is very difficult to determine transition boundaries for flow structures. However, taking into account the structural approach, it is very difficult to determine the boundaries of the flow, and based on the laws of hydrodynamics of a homogeneous liquid and gas, it is possible to determine the transition of one regime to another using the Reynolds number. This technique is based on the theory of the great Russian scientist Academician A.P. Krylov. Let us note that this theory has not yet lost its specialty in the fishing industry. Based on numerous data, a method for calculating the gas-liquid mixture in horizontal pipes is proposed. Based on the laws of homogeneous liquid and gas, an equation for the distribution of speed, flow and pressure loss in a pipeline is obtained. The analysis shows that, based on the laws of homogeneous liquid and gas, it is possible to propose a method for calculating the hydrodynamic parameters of a two-phase flow, such as liquid and gas in a round pipe. This technique is based on the theory of Academician A.P. Krylov, which characterizes the reliability of this technique.

Fruits of the Gardens: Ethics, Metaphysics, and Textual Pleasures in Late Qajar Iran

Abstract This article introduces a miscellany notebook in Arabic and Persian, entitled Favāka al-basātin (Fruits of the Gardens), compiled around 1914 in Tehran by Hājj Mirzā Mohammad Tehrāni (d. 1914–21), a learned sugar merchant and bookseller. The notebook covers a broad range of topics on faith, philosophy, and ethics. It frequently draws on the Qurʾan and the Hadith, as well as Stoic proverbs, mostly from the Meditationes (Meditations) of Marcus Aurelius (r. 161–80), which was well received in nineteenth-century Persian advice literature. The text also includes passages from the Thousand and One Nights and sections on modern sciences, such as electricity, gas laws, and liquid dynamics, and a theory of colors explaining the rainbow. The article’s introductory section provides brief biographical background of the compiler of this notebook, the second section presents an overview of its contents, and the final section explores the question of authorial subjectivity and the author-text relationship by putting in perspective the volume’s gradual compilation, its eclectic range of topics, and its fluid structure. Through its diverse reading and writing strategies, this notebook represents an informative and heuristic venue that opens new analytical angles on Iran’s cosmopolitan, multifaceted, and heterogenous intellectual milieu in the late Qajar period.

Stochastic star formation in the Milky Way inferred from the unity index of the Kennicutt–Schmidt law

Abstract We performed a correlation analysis between the brightness temperature of the CO line and number density of H ii regions in the longitude–velocity diagram (LVD) of the Milky Way in order to investigate the volumetric star-formation law. We determined the index α of the Kennicut–Schmidt law for the molecular gas defined by $\rho _{\rm SFR}\propto \rho _{\rm H_2}^\alpha$, where ρSFR is the SFR (star-formation rate) density and $\rho _{\rm H_2}$ is the molecular-gas density. We obtained α = 1.053 ± 0.075 and 1.031 ± 0.067 for the CO-line data from the Nobeyama 45 m and Columbia 1.2 m telescope Galactic plane surveys, respectively. This result is consistent with the KS indices currently determined for the molecular gas in the Milky Way as well as in spiral and starburst galaxies. We argue that an index close to 1 is universal in favour of stochastic (spontaneous) star formation, but is inconsistent with the cloud-collision model, which predicts a steeper index of α = 2. We also suggest that the efficiency of star formation in the Galactic Centre is an order of magnitude lower than that in the disc.

An equation for the ‘weather glass’

The ‘weather glass’, containing air and (usually) water, is a compact barometer, less accurate but more convenient than the Torricellian barometer of 1644. The weather glass pre-dates the Torricellian barometer, and coexisted with it until it was out-competed from about 1860 by the more accurate, comparably compact aneroid barometer. Today, the weather glass is sold as an elegant interior decoration and is also constructible in a student laboratory. Elementary physics allows one to model its response to changing pressure at constant temperature and also the adjustments that need to be made if the temperature varies. In an air- and water-containing weather glass, the principal factor affecting movements of the water level is the expansion and contraction of the atmospheric nitrogen, oxygen, and argon in a headspace above the water, well represented by the ideal gas law. The water acts primarily as a piston allowing the expansion and contraction to be observed. In contrast, Torricellian and aneroid barometers respond directly to the pressure difference between the atmosphere and a vacuum.

How to Estimate Closeness to the Truth for Scientific Laws. A Case Study of the Development of Gas Laws over 140 Years

How to Estimate Closeness to the Truth for Scientific Laws. A Case Study of the Development of Gas Laws over 140 Years

PARAMETRIC STUDY OF SUCTION OR BLOWINGEFFECTS ON TURBULENT FLOW OVER A FLATPLATE

The two-dimensional, incompressible, and turbulent boundary layer flow over a flat plate with suction or blowing from a spanwise slot is examined numerically. The mathematical modeling involves the derivation of the governing partial differential equations of the problems. These are the continuity, the momentum, the energy and the (K-ε) turbulence model. Besides, the perfect gas law is also used. A numerical solution of the governing equations is approximated by using a finite volume method, with staggered grid and modified SIMPLE algorithm. A computer program in FORTRAN 90 is built to perform the numerical solution.The developed computational algorithm is tested for the flow over a flat plate (4m) long with uniform suction or blowing velocity ratios of (V/U∞ =± 0.0185, ± 0.0463 and ±0.0925 m/s) are imposed on the slot for Reynolds number of (1.36 x 107 ), based on the plate length. The position of the slot change in the range of (X/L=1/4, 1/2 and 3/4) from leading edge and also, change width of slot in the value equal (0.12, 0.2 and 0.28m).The plate temperature is (70 °C), with the free stream velocity and temperature are (8.6m/s) and (25 °C) respectively. In addition, the effects of pitch angles on the flow field are investigated in the range of (30о   150о).The numerical results show that, for a uniform blowing, location of slot equal (X/L=1/4) from leading edge, a significant reduction of skin friction coefficient, wall shear stress and boundary layer thickness [displacement and momentum] to occur. While, an increase in boundary layer shape factor. Reynolds stress (uv) is more decreased than [(uu) and (vv)], mean velocity profiles in wall coordinates and dimensionless distance (U+, y+) decreases. When slot location is moved downstream to locations (X/L=1/2 or 3/4) a similar behavior can be said and most effective slot is obtained as (slot at X/L= 3m) from leading edge. While width of slot equal (0.28m) is better than values equal (0.12m and 0.2m). An opposite observations for the case of suction. The numerical results are compared with available numerical results and experimental data and a satisfactory results are obtained.

Programmable intratumoral drug delivery to breast cancer using wireless bioelectronic device with electrochemical actuation

ABSTRACT Objective Breast cancer is a global health concern that demands attention. In our contribution to addressing this disease, our study focuses on investigating a wireless micro-device for intratumoral drug delivery, utilizing electrochemical actuation. Microdevices have emerged as a promising approach in this field due to their ability to enable controlled injections in various applications. Methods Our study is conducted within a computational framework, employing models that simulate the behavior of the microdevice and drug discharge based on the principles of the ideal gas law. Furthermore, the distribution of the drug within the tissue is simulated, considering both diffusion and convection mechanisms. To predict the therapeutic response, a pharmacodynamic model is utilized, considering the chemotherapeutic effects and cell proliferation. Results The findings demonstrate that an effective current of 3 mA, along with an initial gas volume equal to the drug volume in the microdevice, optimizes drug delivery. Microdevices with multiple injection capabilities exhibit enhanced therapeutic efficacy, effectively suppressing cell proliferation. Additionally, tumors with lower microvascular density experience higher drug concentrations in the extracellular space, resulting in significant cell death in hypoxic regions. Conclusions Achieving an efficient therapeutic response involves considering both the characteristics of the tumor microenvironment and the frequency of injections within a specific time frame.

On the ideal gas law for crowds with high pressure

Active particle systems, such as human crowds, are out of equilibrium posing a significant challenge in identifying a suitable equation of state. However, several previous observations suggest that a crowd’s speed distribution may conform to a two-dimensional Maxwell–Boltzmann distribution under certain yet-to-be-determined conditions. Our research uncovers that the divergence between the fluctuation velocity magnitude’s probability density function and its best 2D Maxwell–Boltzmann fit diminishes in a power-law fashion with decreasing collision time scale between individuals. These findings are robustly supported by both experimental data and simulations with diverse boundary conditions and force potentials. The equilibrium characteristics of crowds are interpreted through a canonical ensemble framework. Furthermore, we show that high pressure indicates equilibrium characteristics in human crowds. Remarkably, we reveal the ideal gas law for human crowds without resorting to any behavior assumption. We demonstrate the predictive capability of the ideal gas law on both observational and modeling data. Our research highlights a new pathway to explore and validate traditional thermodynamic quantities and laws in the setting of high-pressure human crowds, advancing our understanding of active matter systems.

Application of Flue Gas Foam-Assisted Steam Flooding in Complex and Difficult-to-Produce Heavy Oil Reservoirs.

In order to study the mechanism of improving recovery efficiency of complex difficult-to-recover heavy oil reservoirs and explain the interaction and migration law of flue gas, foam, and steam, this paper designed the experiment of flue gas influence on heavy oil flow and the experiment of flue gas foam displacement in complex difficult-to-recover heavy oil model. The results show that the flue gas has expansion and an energy enhancement effect. Moreover, the interfacial tension of heavy oil can be reduced, and the higher the CO2 content in flue gas, the more beneficial it is to reduce the interfacial tension. When there is an interlayer in the reservoir, the gas can form a "puncture" in the interlayer, which provides a channel for the subsequent upward expansion of steam, so that the upper part of the interlayer can be used to expand the steam sweep range. The main mechanism of improving heavy oil recovery with flue gas foam is that the foam regulates fluid mobility and improves the thermal sweep efficiency of steam. In addition, the injected foam can emulsify with heavy oil, reduce the viscosity of heavy oil, and improve the fluidity of heavy oil. Finally, the maximum oil production rate increased from 1.809 to 2.455 g/min, and the recovery rate increased from 44.3 to 68.8%.

Hypobaric type oxygenators - physics and physiology.

Brain injury is still a serious complication after cardiac surgery. Gaseous microemboli (GME) are known to contribute to both short and longer-term brain injury after cardiac surgery. Hypobaric and novel dual-chamber oxygenators use the physical behaviors and properties of gases to reduce GME. The aim of this review was to present the basic physics of the gases, the mechanism in which the hypobaric and dual-chamber oxygenators reduce GME, their technical performance, the preclinical studies, and future directions. The gas laws are reviewed as an aid to understanding the mechanisms of action of oxygenators. Hypobaric-type oxygenators employ a high oxygen, no nitrogen environment creating a steep concentration gradient of nitrogen out of the blood and into the oxygenator, reducing the risk of GMEs forming. Adequately powered clinical studies have never been carried out with a hypobaric or dual-chamber oxygenator. These are required before such technology can be recommended for widespread clinical use.