Equation Of State Model Research Articles

Calibration and uncertainty quantification for Davis Equation of State models for the High Explosive PBX 9501 products

AbstractThis paper investigates the uncertainty in the parameters used in the calibration of an Davis Equation Of State (EOS) for the detonation products of the High Explosive PBX 9501. The procedure sought to make use of all available information about this HE to inform the best set of calibration parameters as well as the uncertainty in these parameters. The procedure made use of historical experimental data, the results from thermo‐chemical modeling as well as data on the best isentrope function fit to cylinder test experimental data. Combining all these heterogeneous data sources together in a Bayesian calibration, yielded a posterior mean and covariance. Sampling from the posterior distribution and evaluating an important Quantity Of Interest (QOI) in the EOS model, the detonation speed of a one‐inch rate stick, produced a distribution which showed variations which were in agreement with experiments. The uncertainty in the EOS was reported as eleven sets of model calibrations which spanned the range of this QOI.

Estimating the role of bag constant and modified theory on anisotropic stellar models

In this article, we are devoted to discuss different compact stars admitting anisotropic interiors in a particular modified theory of gravity. For this purpose, a spherically symmetric metric is adopted to formulate the field equations corresponding to two different f(R,T,Q) models, where Q=RαγTαγ. Since the field equations contain extra degrees of freedom, we choose Finch–Skea metric and MIT bag model equation of state to make them solvable. We also use matching conditions to calculate a constant triplet in the chosen ansatz. The resulting solutions are then graphically analyzed for particular values of the bag constant and model parameter in the interior of 4U 1820-30 compact star. The viability and stability of the modified models are also checked through certain tests. Further, we calculate the values of model parameter through the vanishing radial pressure constraint that correspond to the observed data (radii and masses) of eight different star candidates. Finally, we conclude that our models I and II are in well-agreement with the conditions needed for physically relevant interiors to exist.

Simulation study of reactive distillation process for synthesis of dimethyl maleate

Abstract Conventional dimethyl maleate (DMM) synthesis relies on the use of sulfuric acid as a catalyst which requires water washing and produces a large amount of wastewater that harms the environment. The use of this method is expensive since it involves numerous processes such as neutralization of sulfuric acid, washing with water, distillation etc. and the yield of dimethyl maleate is not very high. Reactive distillation integrates the two important industrial processes such as reaction and distillation into a single unit which shortens the overall process, reduces capital and operating costs, and maintains the reaction in a forward direction to enhance the conversion of maleic anhydride by continuously removing of the products. In this work, simulation study based on experimental investigation of reactive distillation process for the synthesis of dimethyl maleate was carried out using Aspen Plus V11. DZH strong cation exchange resin was used as catalyst for esterification reaction of maleic anhydride with methanol. A reactive section of column was packed with Katapak SP type packing loaded with DZH catalyst while non-reactive sections consist of wire gauze packing. In order to describe a reactive distillation process for synthesis of dimethyl maleate, RAD-FRAC equilibrium stage model was employed. The NRTL activity model and RK equation of state model were selected to describe vapor-liquid equilibrium of the system. The reliability of the developed simulated model was verified by validating the simulation results with the experimental ones. The effect of various design and operating parameters on the conversion of maleic anhydride and purity of dimethyl maleate has been studied. It was found that the optimal condition for RD, were as follow: total number of theoretical stages 17, rectifying stages 3, reactive stages 7, stripping stages 5, reflux ratio 0.25, operating pressure 0.1 MPa, reboiler duty 250 Cal/Sec, feed mole ratio 1:5. Under optimized condition the water formed as a results of esterification reaction was constantly removed from the reactive section of the column to maintain reaction balance, the conversion of maleic anhydride was 99.95 %, purity of dimethyl maleate achieved was 0.997 and the reactive distillation process was feasible to produce dimethyl maleate without any wastewater.

Simulation of extreme ultraviolet radiation of laser induced discharge plasma

Extreme ultraviolet (EUV) light source is an important part of EUV lithography system in semiconductor manufacturing. The EUV light source requires that the 4p<sup>6</sup>4d<sup><i>n</i></sup>-4p<sup>5</sup>4d<sup><i>n</i>+1</sup> + 4d<sup><i>n</i>-1</sup>4f transitions of Sn<sup>8+~13+</sup> ions emit thousands of lines which form unresolved transition arrays near 13.5 nm. Laser-induced discharge plasma is one of the important technical means to excite target into an appropriate plasma condition. Laser-induced discharge plasma has a simple structure and a low cost. It also has important applications in mask inspection, microscopic imaging, and spectral metrology. In the design and production process, there are many factors that can influence the conversion efficiency, such as current, electrode shape, and laser power density. The simulation method is a convenient way to provide guidance for optimizing the parameters. In this paper, a completed radiation magneto-hydrodynamic model is used to explore the dynamic characteristics of laser-induced discharge plasma and its EUV radiation characteristics. To improve the accuracy, a more detailed global equation of state model, an atomic structure calculation model including relativistic effect and a collision radiation model are proposed simultaneously. The simulation reconstructs the discharge process effectively, which is divided into five stages in the first half cycle of current, including expansion of laser plasma, column formation of discharge plasma, diffusion of discharge plasma, contraction of discharge plasma, and re-diffusion of discharge plasma. It is revealed that the pinch effect during the current rising time exerts a significant influence on the generation of EUV radiation. The conversion efficiency of EUV radiation is still low under our existing conditions, and hopefully a higher rising rate of current can improve the conversion efficiency in the future work.

Probing Cosmology with Baryon Acoustic Oscillations Using Gravitational Waves

The third-generation (3G) gravitational wave (GW) detectors such as the Einstein Telescope or Cosmic Explorer are expected to play an important role in cosmology. With the help of 3G detectors, we will be able to probe large-scale structure features such as baryon acoustic oscillations (BAO), galaxy bias, etc. We explore the possibility to do precision cosmology, with the 3G GW detectors by measuring the angular BAO scale using localization volumes of compact binary merger events. Through simulations, we show that with a 3G detector network, by probing the angular BAO scale using purely GW observations, we can constrain the Hubble constant for the standard model of cosmology (ΛCDM) with 90% credible regions as . When combined with BAO measurements from galaxy surveys, we show that it can be used to constrain various models of cosmology such as parameterized models for dark energy equations of state. We also show how cosmological constraints using BAO measurements from GW observations in the 3G era will complement the same from spectroscopic surveys.

Celestial attributes of hybrid star in [formula omitted] Einstein-Gauss–Bonnet gravity

Hybrid star is the term given to a neutron star with a quark core. Due to a lot of uncertainties in the calculations and compositions of such a high-density system, it is of great interest and a preferred scenario for particle physicists and astrophysicists. To explore some novel aspects within the framework of the 5D Einstein-Gauss–Bonnet(EGB) gravity, our current study presents a hybrid star model that includes strange quark matter in addition to regular baryonic matter. In hybrid stellar objects, a hadronic outer component surrounds a quark inner component, which prompts the consideration of the most basic MIT bag model equation of state to correlate the density and pressure of strange quark matter within the stellar interior, while radial pressure and matter density due to baryonic matter are connected by a linear equation of state. The model is constructed within the specifications of the Krori and Barua (KB) ansatz (Krori and Barua, J. Phys. A: Math. Gen. 8,508,1975). Here we present the solution for a particular compact object 4U 1538 - 52 with mass M=0.87±0.07M⊙ and radius R=7.866−0.21+0.21 km. We examine the fundamental physical characteristics of the star, which highlights how the values of matter variables are affected by the Gauss–Bonnet coupling parameter α. Finally, as it meets all the physical requirements for a realistic model, we have come to realize that our present model is realistic.

Studies on solubility measurement of codeine phosphate (pain reliever drug) in supercritical carbon dioxide and modeling

In this study, the solubilities of codeine phosphate, a widely used pain reliever, in supercritical carbon dioxide (SC-CO2) were measured under various pressures and temperature conditions. The lowest determined mole fraction of codeine phosphate in SC-CO2 was 1.297 × 10−5 at 308 K and 12 MPa, while the highest was 6.502 × 10−5 at 338 K and 27 MPa. These measured solubilities were then modeled using the equation of state model, specifically the Peng-Robinson model. A selection of density models, including the Chrastil model, Mendez-Santiago and Teja model, Bartle et al. model, Sodeifian et al. model, and Reddy-Garlapati model, were also employed. Additionally, three forms of solid–liquid equilibrium models, commonly called expanded liquid models (ELMs), were used. The average solvation enthalpy associated with the solubility of codeine phosphate in SC-CO2 was calculated to be − 16.97 kJ/mol. The three forms of the ELMs provided a satisfactory correlation to the solubility data, with the corresponding average absolute relative deviation percent (AARD%) under 12.63%. The most accurate ELM model recorded AARD% and AICc values of 8.89% and − 589.79, respectively.

A four parameters quark star in quadratic [formula omitted]action

In this collaborative work, we model charged compact objects within the framework of f(Q) gravity. We assume a quadratic form for the metricity function cast as f(Q)=Q+aQ2 where a can be thought of as a ‘switch’, regaining the classical general relativity limit when it vanishes. In order to close the system of governing equations, we adopt the Krori–Barua ansatz for the metric functions and the MIT bag model equation of state (EOS) determines the evolution of the electric field. The resulting models are singularity-free and describe physically realizable stellar structures such as neutron stars. We demonstrate that the physical attributes of our models are sensitive to four parameters, namely, the EOS, metricity, and charge parameters together with the bag constant. We observe that an increase in the quadratic contribution culminates in a decrease of the density, radial pressure, electric field, and sound speeds while ωr,ωt, anisotropy, and pt increase. The novelty in our work centers on a possible mechanism of increasing the anisotropy of the stellar interior without resorting to exotic fluids or anisotropisation via gravitational decoupling. The robustness of our models can account for observed mass–radius relations of well-known compact stars such as PSR J1614-2230, PSR J1903+6620, Cen X-3 and LMC X-4 and the secondary component of GW190814 event.

Model-free adaptive chaos control for the boost converter

In order to solve the dynamic analysis and chaotic motion control problems of the current-mode-controlled Boost converter system, a state equation model in the continuous current mode is established. The evolutionary path of the periodic motion of the system through the doubling bifurcation to the chaotic motion is analyzed by the bifurcation diagram, Poincaré sections and phase portraits. Then, according to the fundamental principle of the resonant parametric perturbation (RPP) method, a controller is designed based on the model-free adaptive control (MFAC) method to output the perturbation amplitude, and the disturbance quantity is calculated according to the perturbation amplitude. By adding a small amplitude disturbance to the controllable parameter of the controlled system, the chaotic motion of the system is guided to expected periodic orbit. The advantage of this method is that no precise mathematical model (PMM) of the system is required. At the same time, the design of the controller is simple and easy to implement.

Electromagnetic effects on static celestial objects in modified gravity

This paper aims to figure out the existence and development of some particular celestial bodies possessing charged anisotropic interiors in the framework of f(G,T) gravity. The modified field equations corresponding to a quadratic G2+ℵT model are established in which MIT bag model equation of state is employed to engage the role of bag constant, where ℵ symbolizes the coupling parameter. We then consider a Finch–Skea metric to uniquely solve the field equations. The resulting physical parameters are then explored graphically by using estimated data of five distinct compact stars PSR J1614-2230, Vela X-I, PSRJ1903+327, 4U1820-30 and Her X-I. Further, the regularity conditions, role of anisotropic pressure and viability criteria are investigated for different choices of the charge and bag constant. The stability is also determined through causality condition and the adiabatic index. We conclude that all the five charged star candidates correspond to viable and stable structures under the imposed constraints.

Influence of modified gravity on self-gravitating stellar objects

This paper focuses on studying the self-gravitating spherical compositions enclosing anisotropic fluid distribution in the context of f(G,T) theory. The modified field equations representing anisotropic source are formulated, and then the MIT bag model equation of state is used to contribute the participation of bag constant. The mathematical equations are thoroughly computed using a quadratic f(G,T)=G2+ħT model (where ħ indicates the coupling parameter). We utilize the Finch-Skea ansatz to examine the compact objects Her X-I, Vela X-I, PSR J1614-2230, LMC X-4 and 4U1820-30. This solution facilitates in determining the behavior of physical factors, anisotropic source and energy constraints corresponding to the above-mentioned stars graphically. We construct the graphs by following two distinct values of the coupling parameter throughout. Some other important factors such as mass, redshift and compactness are also discussed. To examine the stable character, we use three strategies, i.e., causality condition, Herrera cracking approach and adiabatic index. Interestingly, for both the values of ħ, all the considered candidates signify the viable as well as stable behavior.

Anisotropic quark stars in energy-momentum squared gravity

At super-saturation densities, quarks in the core of neutron stars (NSs) have been a subject of intense investigation for last few decades. In particular, an intriguing conjecture has emerged suggesting that the true ground state of hadronic matter may be strange quark matter (SQM). In the present manuscript, we study internal structure and the physical properties of quark stars (QSs) in energy-momentum squared gravity (EMSG) with MIT bag model equations of state (EoS). An important feature of this theory is the addition of the term f(TμνTμν) to the Einstein-Hilbert action. This modification in the action lead to changes in the right-hand side of Einstein's field equations (EFE). We obtain mass-radius relations for a spherically symmetric configuration supported by the anisotropic fluid matter distribution and solved the hydrostatic equilibrium equations numerically in the framework of EMSG. In addition, we present and discuss the stability of stellar structure depending on the model parameters.

A Paradigm Shift in High-Pressure Equation of State Modeling: Unveiling the Pressure–Bulk Modulus Relationship

A Paradigm Shift in High-Pressure Equation of State Modeling: Unveiling the Pressure–Bulk Modulus Relationship

Analysis of the behavioural capabilities of electric heating loads to participate in power system power regulation

The high proportion of new energy access leads to the scarcity of power system regulation capacity, and it is important to provide regulation capacity for the power system by reasonably regulating the electricity consumption of electric heating temperature-controlled loads. In this paper, in order to analyse the characteristics of the electric heating behaviour and the electric heating load's ability to participate in grid regulation, the differential equations of a typical room temperature change process are constructed first to establish the equation of state model of a two-input system, and then the state equations are discretised into difference equations according to the bilinear discretisation method for iterative solving. This paper analyses that the equivalent heat capacity and thermal resistance parameters of indoor air and wall will affect the temperature response time and the size of the required heating power, with the lowering of the outdoor temperature of a single household room, the average indoor warming time increases, the average cooling time decreases, the average daily power consumption increases, and the total power consumption of the whole community power also rises.

Importance of critical point for the phase behavior of a reservoir fluid

It is a fundamental assumption behind a cubic equation of state that the phase behavior of a pure component can be expressed in terms of its critical temperature and pressure. This paper shows that the location of the critical point also for multicomponent reservoir fluids influences the phase behavior throughout the gas and liquid region. An equation of state model that matches the critical point and the saturation pressure at the reservoir temperature is likely to provide a good match of the phase behavior of a reservoir fluid at all conditions experienced during oil and gas production. An experimental critical point is seldom available for a reservoir fluid but the critical point can be estimated from correlations in the molar ratio of C7+ and lighter hydrocarbons. When PVT data exists, such estimated critical point can be used as an extra datapoint when assigning critical properties to an equation of state model. This is particularly useful as a constraint when the equation of state is to be used for gas injection enhanced oil recovery calculations. When the available PVT data is limited to a saturation point at the reservoir temperature, a reliable equation of state model can be developed by only tuning to the saturation pressure and the estimated critical point. The presented method is applicable to reservoir oils and gas condensates with a C7+ mole% of at least 10.

Solid-fluid phase behaviour in binary mixtures: A new classification focused on paraffinic systems

The solid-fluid phase behavior of mixtures is important in a variety of real situations of industrial interest, including paraffin precipitation from hydrocarbon reservoir fluids, supercritical extraction or precipitation processes, and cryogenic processes among others. In the case of binary mixtures with the presence of fluid and solid phases, such behaviors can yield different topologies in terms of critical lines, three-phase lines, critical end points and quadruple points. The classification proposed by Yamamoto et al. in 1989 for those topologies is probably the best known and most used one, besides being more complete than others when considering experimentally observed behaviors. Nevertheless, a number of publications and in particular two recent PhD theses developed in our groups, found other topologies which deviate from the types considered in Yamamoto's et al. classification. These two theses employed different modelling approaches, using equation of state models for describing fluid phases and differing essentially in considering each solid phase as either made of the heavy compound in pure state or made of a solid solution. The deviations from the types in Yamamoto's et al. classification are compiled and analyzed in this work. Moreover, a new classification is proposed for binary systems with varying degrees of asymmetry. Being motivated by the study of paraffin precipitation from reservoir fluids, this new classification, in contrast to Yamamoto's et al. classification, leaves out of consideration the lower temperature range (up to the triple point of the light component) while, on the other hand, it incorporates some possible behavior variations, in the temperature range of more practical interest, which are not accounted for in Yamamoto's et al. classification. The new classification is shown to cover all possible phase behavior evolutions in the binary series of methane or ethane or propane with a heavier n-alkane and also of carbon dioxide with a n-alkane, considering both, what is known so far in terms of experimental data, and some features predicted with different modelling approaches, which have not been confirmed yet at the experimental level.

Investigating dark matter-admixed neutron stars with NITR equation of state in light of PSR J0952-0607

The fastest and heaviest pulsar, PSR J0952-0607, with a mass of M = 2.35±0.17 M ⊙, has recently been discovered in the disk of the Milky Way Galaxy. In response to this discovery, a new RMF model, 'NITR' has been developed. The NITR model's naturalness has been confirmed by assessing its validity for various finite nuclei and nuclear matter properties, including incompressibility, symmetry energy, and slope parameter values of 225.11, 31.69, and 43.86 MeV, respectively. These values satisfy the empirical/experimental limits currently available. The maximum mass and canonical radius of a neutron star (NS) calculated using the NITR model parameters are 2.355 M ⊙ and 13.13 km, respectively, which fall within the range of PSR J0952-0607 and the latest NICER limit. This study aims to test the consistency of the NITR model by applying it to various systems. As a result, its validity is extensively calibrated, and all the nuclear matter and NS properties of the NITR model are compared with two established models such as IOPB-I and FSUGarnet. In addition, the NITR model equation of state (EOS) is employed to obtain the properties of a dark matter admixed NS (DMANS) using two approaches (I) single-fluid and (II) two-fluid approaches. In both cases, the EOS becomes softer due to DM interactions, which reduces various macroscopic properties such as maximum mass, radius, tidal deformability, etc. The various observational data such as NICER and HESS are used to constrain the amount of DM in both cases. Moreover, we discuss the impact of dark matter (DM) on the nonradial f-mode frequency of the NS in a single fluid case only and try to constrain the amount of DM using different theoretical limits available in the literature.

Asphaltene Flow Assurance Risk Evaluation Case Study to Establish Guidelines for CCUS in Arabian Gulf Carbonate Oil Field

Summary In this paper, we present a case study for a comprehensive series of asphaltene flow assurance risk evaluations in the Arabian Gulf Carbonate Oil Field, where CO2 enhanced oil recovery (EOR) is recognized as one of the highest potential technologies for full-field implementation. At first, the sampling location was carefully selected considering the target reservoir’s features because the reliability of asphaltene studies highly depends on sample representativeness. After the quality assurance and quality control of collected samples, asphaltene onset pressures (AOPs) were measured at multiple temperatures under CO2 mixing conditions. The experimental design was optimized in terms of not only improving evaluation accuracy but also minimizing the experimental/sampling cost. The AOP measurements showed clear potential risks associated with CO2 injection. Subsequently, the numerical model analysis was conducted with the cubic-plus-association equation of state model to identify the risk area during CO2 injection. The analysis suggested that risk area is applicable to not only near-wellbore region at the sampling location but also tubing section/surface facility. Furthermore, risk level can be higher at the deeper location of the target reservoir. Finally, CO2-induced asphaltene formation damage risk was investigated from the viewpoints of precipitated asphaltene particle size and pore throat size in the porous media. As a result, the clogging risks from CO2-induced asphaltene were estimated to be high in the target reservoir. By virtue of the comprehensive risk evaluation, the asphaltene flow assurance risk associated with CO2 injection was identified field-wide. The findings from the evaluation encouraged us to move on to future actions, such as more detailed formation damage risk evaluation and mitigation plan development. The extended asphaltene risk evaluation covering the precipitation to deposition phenomena and the reverse engineering for sampling operations based on the experimental design made a worthy demonstration to reduce unnecessary cost and time while obtaining the key information to drive the project. The procedure in this work can contribute to establishing a subsurface part of a guideline for carbon capture, utilization, and storage (CCUS) from the viewpoint of asphaltene flow assurance risk evaluation.

Influence of three parameters on maximum mass and stability of strange star under linear f(Q) − action

ABSTRACT This study simulates strange stars in f(Q) gravity with an additional source under an electric field using gravitational decoupling by means of the complete geometric deformation (CGD) technique. By employing the Tolman ansatz and the MIT bag model equation of state (EOS), we explore bounded star configurations derived from the $\theta _0^0 = \rho$ and $\theta _1^1 = p_r$ sectors within the CGD formalism. Our models are subjected to physical viability tests, and we analyse the impact of anisotropy and the electric charge parameter E0 as well as the coupling parameters α and β1. Comparisons are made with observational constraints, including GW190814, neutron stars PSR J1614-2230, PSR J1903 + 6620, Cen X-3, and LMC X-4. Notably, we achieve the presence of a lower ‘mass gap’ component by adjusting parameters α and β1. Our models exhibit well-behaved mass profiles, internal regularity, and stability, along with the absence of gravitational collapse verified through the Buchdahl–Andréasson’s limit. In addition, we present a detailed physical analysis based on three parameters, α (decoupling strength), β1 (f(Q)–coupling), and Q (surface charge). This study provides insights into the behaviour of compact objects in f(Q) gravity and expands our understanding of strange star configurations within this framework.

Numerical simulations for largely deformed beams and rings adopting a nontensile smoothed particle hydrodynamics algorithm

Three typical elastic problems, including beam bending, truss extension and compression, and two-rings collision are simulated with smoothed particle hydrodynamics (SPH) using Lagrangian and Eulerian algorithms. A contact-force model for elastic collisions and equation of state for pressure arising in colliding elastic bodies are also analytically derived. Numerical validations, on using the corresponding theoretical models, are carried out for the beam bending, truss extension and compression simulations. Numerical instabilities caused by largely deformed particle configurations in finite/large elastic deformations are analysed. The numerical experiments show that the algorithms handle small deformations well, but only the Lagrangian algorithm can handle large elastic deformations. The numerical results obtained from the Lagrangian algorithm also show a good agreement with the theoretical values. doi: 10.1017/S1446181123000160