Experimental Simulation Study Research Articles

Influence of Voltage Rising Time on the Characteristics of a Pulsed Discharge in Air in Contact with Water: Experimental and 2D Fluid Simulation Study

In the context of plasma–liquid interactions, the phase of discharge ignition is of great importance as it may influence the properties of the produced plasma. Herein, we investigated the influence of voltage rising time (τrise) on discharge ignition in air as well as on discharge propagation on the surface of water. Experimentally, τrise was adjusted to 0.1, 0.4, 0.6, and 0.8 kV/ns using a nanosecond high-voltage pulser, and discharges were characterized using voltage/current probes and an ICCD camera. Faster ignition, higher breakdown voltage, and greater discharge current (peak value) were observed at higher τrise. ICCD images revealed that higher τrise also promoted the formation of more filaments, with increased radial propagation over the water surface. To further understand these discharges, a previously developed 2D fluid model was used to simulate discharge ignition and propagation under various τrise conditions. The simulation provided the spatiotemporal evolution of the E-field, electron density, and surface charge density. The trend of the simulated position of the ionization front is similar to that observed experimentally. Furthermore, rapid vertical propagation (<1 ns) of the discharge towards the liquid surface was observed. As τrise increased, the velocity of discharge propagation towards the liquid increased. Higher τrise values also led to more charges in the ionization front propagating at the water surface. The discharge ceased to propagate when the charge number in the ionization front reached 0.5 × 108 charges, irrespective of the τrise value.

Unraveling the mechanism of small molecule induced activation of Staphylococcus aureus signal peptidase IB

Staphylococcus aureus signal peptidase IB (SpsB) is an essential enzyme for protein secretion. While inhibition of its activity by small molecules is a well-precedented mechanism to kill bacteria, the mode of activation is however less understood. We here investigate the activation mechanism of a recently introduced activator, the antibiotic compound PK150, and demonstrate by combined experimental and Molecular Dynamics (MD) simulation studies a unique principle of enzyme stimulation. Mass spectrometric studies with an affinity-based probe of PK150 unravel the binding site of PK150 in SpsB which is used as a starting point for MD simulations. Our model shows the localization of the molecule in an allosteric pocket next to the active site which shields the catalytic dyad from excess water that destabilizes the catalytic geometry. This mechanism is validated by the placement of mutations aligning the binding pocket of PK150. While the mutants retain turnover of the SpsB substrate, no stimulation of activity is observed upon PK150 addition. Overall, our study elucidates a previously little investigated mechanism of enzyme activation and serves as a starting point for the development of future enzyme activators.

Experimental and numerical simulation study on enhanced oil recovery by N2-Assisted water huff-n-puff in a tight oil reservoir

The water huff-n-puff (WHP) method is widely used for improving oil recovery in tight reservoirs. However, the poor flow conductivity and low sweep efficiency of the matrix restrict the oil recovery performance of this method. Herein, N2-assisted water huff-n-puff (NAWHP) was proposed to improve oil recovery under reservoir conditions. First, the feasibility of NAWHP for tight reservoirs was investigated by comparing the enhanced oil recovery (EOR) performance with that of WHP and N2 huff-n-puff (NHP). The core flooding experimental results revealed that NAWHP facilitated oil recovery improvement, outperforming the existing practice of water or N2 huff-n-puff injection. Thereafter, with the aid of nuclear magnetic resonance (NMR) technology, the application of NAWHP could significantly enhance oil recovery in fractured tight cores, which mainly increased oil recovery from micro- and nanopores in the matrix. Specifically, for submicron pores and micropores, after three cycles of NAWHP, the recovery efficiency increased by 21.35% and 36.19%, respectively, while the recovery only increased by 14.34% and 24.8%, respectively, during WHP. For nanopores and micro/nanopores, the use of WHP increased the total oil recovery by only 4.71%, while the use of NAWHP increased the total oil recovery threefold. Finally, a series of numerical simulations were conducted to explore the effects of different parameters on oil recovery by NAWHP. The results illustrated that a high N2–water ratio (NWR) positively affected the overall oil recovery, but the higher the NWR was, the more difficult to extract the oil below the injection layer. By injecting 13,000 m3 of N2, the maximum swept volume was achieved for the matrix, and water filled the major fractures after injecting 11,000 m3, effectively accomplishing this task. Increasing the soaking time positively influenced oil recovery, N2 diffusion within the matrix led to an even distribution over 50 days, and water imbibition caused a significant increase in the oil saturation in hydraulic fractures within 30 days. The application of NAWHP increased the number of huff-n-puff cycles of water from a maximum of 3–5.

Experimental and numerical simulation studies of electrical resistance of cementitious materials under varying temperature history

Many in-service concrete structures are normally exposed to varying temperature condition. The time-dependent and non-uniform temperature distribution in concrete structures could affect the accurate assessment of their electrical properties. Therefore, the influences of temperature change over time and the spatial variation in temperature on the measured electrical resistance of cementitious materials are still in need of investigation. The coupled thermal-electrical responses of two types of cementitious materials under varying temperature history were investigated by a series of thermal and electrical tests in this study. Then a coupled thermal-electrical finite element (FE) model was developed to simulate the coupled thermal-electrical responses. The results show that the input direct current has a minor effect on the measured electrical resistance by embedded four-probe method and the specimen temperature when it is no greater than 3 mA. The relationship between the measured temperature at 10-mm depth of the specimen and the apparent resistance is well captured by a linear equation. The coupled thermal-electrical finite element model can predict well the developments of specimen temperature and apparent electrical resistance under varying temperature history. The FE results reveal that the non-uniform temperature variation results in the redistribution of electrical current within the tested specimen. However, electrical field between the two inner electrodes is always uniform when the embedded four-probe method is used, which is not affected by the non-uniform temperature variation.

Effects of side-chain lengths on the structure and properties of anhydrides modified starch micelles: Experimental and DPD simulation studies

Anhydride-modified starch micelles have great potential in the delivery of hydrophobic guest molecules. This study aimed to experimentally explore the effects of side-chain lengths on the structure and properties of anhydride-modified starch micelles, and to visualize the self-assembly and loading process of these micelles through Dissipative particle dynamics (DPD) simulations. Starch micelles could only form when the carbon chain length exceeded four. The highly hydrophobic C18 starch micelle exhibited the minimum particle size (65 nm) and maximum loading capability (59.10 μg/mg). For each addition carbon atom in the anhydride side chains, the critical micelle concentration (CMC) of starch micelles decreased average of 1.79 %. Thermodynamic results showed that the micellization was an entropy-dominated driven process, and longer carbon chains enhanced the stability of starch micelles. DPD results showed that the starch chains formed the small clusters then spherical aggregates and finally core-shell structure spherical micelle. Curcumin was loaded into micelles by adjoint aggregation-micellization-adsorption mechanism. Overall, this study provides microscopic insight into the micellization and drug-loading mechanisms for anhydrides modified starch micelles.

A shock-tube experimental and kinetic simulation study on the autoignition of methane at ultra-lean and lean conditions

Coalbed methane represents an important kind of natural gas resource in many countries. However, the low-concentration property of coalbed methane limits its applications. To gain insight into the combustion kinetics of coalbed methane and facilitate its combustion utilization, this work reports an experimental and kinetic simulation study on the autoignition properties of methane at ultra-lean and lean conditions. A shock-tube (ST) facility is used for ignition delay time (IDT) measurements with equivalence ratios at 0.5, 0.1, and 0.05 with pressure at 2 and 10 bar under the temperature ranging from 1320 to 1850 K. The measured IDTs can be correlated into a general Arrhenius expression, and the equivalence ratio effect on IDTs is then analyzed. Seven detailed chemical kinetic mechanisms are employed to predict the IDTs and statistical error indicators are used to evaluate their performance. Detailed kinetic analysis via sensitivity and reaction path analysis is performed to uncover the kinetic differences among the seven mechanisms. It is shown that some of the reaction paths only exist in the NUIGMech1.3 mechanism, while the other detailed mechanisms do not consider them. Reaction path analysis indicates that the reactions related to O2, OH and O species become more important compared to the reactions involving CH3 and H radicals as the equivalence ratio decreases from lean to ultra-lean conditions. Detailed chemical kinetics analysis is also conducted to demonstrate the uncertainty of key reactions. The present work should be valuable to gain insight into the methane ignition characteristics and to facilitate kinetic mechanism optimization of methane combustion.

Experimental and Numerical Simulation Study on CO2-Assisted Steamflooding in Ultraheavy Oil Reservoirs

Experimental and Numerical Simulation Study on CO2-Assisted Steamflooding in Ultraheavy Oil Reservoirs

Analysis of drop-on-demand printing characteristics and stability driven by inertial forces

As the core technology in the field of microdroplet related applications, researchers have been striving to develop new driving methods and improve the stability of inkjet printing technology to meet the diverse needs of various materials and applications. In this study, a novel, simple, and cost-effective droplet printing method based on inertial force driving is proposed, and its printing characteristics and stability are investigated through experimental and numerical simulation studies. A numerical model was developed to explore the effects of operating parameters and fluid properties on the printing process. The results showed that for a given fluid, it is easier to form satellite droplets when driven from a smaller nozzle with higher voltage and pulse width. The hydrophilic nature of the nozzle can suppress the formation of satellite droplets, but it is prone to retain liquid, thereby affecting the next printing effect. Under certain operating conditions, fluids with lower density, higher viscosity, and higher surface tension are difficult to be driven but can suppress the formation of satellite droplets and promote printing stability. Finally, a parameter space composed of dimensionless numbers Op representing operating parameters and Z representing fluid properties (reciprocal of the Oh number) was established to investigate the comprehensive influence on the printing. The correctness of this parameter space in guiding the selection of parameters for stable droplet printing was validated through experiments.

Experimental, electrochemical and DFT simulation studies of a novel Schiff base derivative as an efficient mild steel corrosion inhibitor in acidic environments

A newly synthesized Schiff base, consisting 3-methyl-2-{(E)-[(2E)-3-phenylprop-2-en-1-ylidene] amino} butanoic acid, is utilized to prevent mild steel from corroding in acidic environments. FTIR spectra validate the prepared SB. The corrosion rate at various temperatures was measured using electrochemical techniques like as polarization and electrochemical impedance tests. At a higher temperature of 333K, this molecule exhibits about 90% inhibition efficacy with 50 ppm inhibitor. The corrosion inhibition mechanism was measured using thermodynamic and adsorption characteristics. These findings suggest that chemical adsorption causes a surface layer to form on the metal surface. The Langmuir adsorption isotherm is followed. The creation of the adsorption layer on the metal surface is confirmed by SEM and AFM pictures. Quantum chemical calculations were calculated and discussed.

Probing phonon focusing, thermomechanical behavior, and moiré patterns in van der Waals architectures using surface acoustic waves

Surface acoustic waves (SAWs) propagate along solid-air, solid-liquid, and solid-solid interfaces. Their characteristics depend on the elastic properties of the solid. Combining transmission electron microscopy (TEM) experiments with molecular dynamics (MD) simulations, we probe atomic environments around intrinsic defects that generate SAWs in vertically stacked two-dimensional (2D) bilayers of MoS2. Our joint experimental-simulation study provides insights into SAW-induced structural and dynamical changes and thermomechanical responses of MoS2 bilayers. Using MD simulations, we compute mechanical properties from the SAW velocity and thermal conductivity from thermal diffusion of SAWs. The results for Young’s modulus and thermal conductivity of an MoS2 monolayer are in good agreement with experiments. The presence of defects, such as nanopores which generate SAWs, reduces the thermal conductivity of 2D-MoS2 by an order of magnitude. We also observe dramatic changes in moiré patterns, phonon focusing, and cuspidal structures on 2D-MoS2 layers.

Adsorption properties of n-octane/1-octene binary mixtures in the zeolitic imidazolate frameworks, ZIF-8 and ZIF-67: Combined experimental and molecular simulation study

1-Octene, a linear α-olefin, can be used as a comonomer for producing plastics, oils, waxes, and surfactants. High-purity 1-octene can be obtained by removing paraffin byproducts using energy-intensive distillation. Adsorptive separation using porous material–based adsorbents is a promising alternative to distillation. Most reported adsorbents are zeolites, which preferentially adsorb 1-octene rather than n-octane owing to their polar framework. However, the existing studies are insufficient for investigating apolar adsorbents that adsorb more amounts of n-octane than 1-octene. Herein, the adsorption properties of the apolar adsorbents, zeolitic imidazolate frameworks-8 (ZIF-8) and ZIF-67, obtained from a n-octane/1-octene liquid binary mixture were systematically investigated by conducting batch adsorption experiments for the n-octane volume fraction of 10 %–90 %. Results show that ZIF-8 and ZIF-67 are promising adsorbents for the selective adsorption of n-octane owing to the preferential adsorption of n-octane in the micropores of the ZIFs at the high concentration of n-octane. Configurational-bias grand canonical Monte Carlo simulations confirm that the host–adsorbate energy between ZIF-8 and n-octane is higher than that between ZIF-8 and 1-octene, whereas the host–adsorbate energy between ZIF-67 and n-octane is similar to that between ZIF-67 and 1-octene.

Experiment and numerical simulation study of polycarboxylate superplasticizer modified cemented ultrafine tailings filling slurry: Rheology, fluidity, and flow properties in pipeline

Understanding the rheological properties of cemented paste backfill is crucial for optimizing its flowability and ensuring the efficient transportation in mine site. Due to the superfine size, the high-concentration filling slurry prepared by ultrafine tailings (the mean size < 0.019 mm) usually exhibits poor flow performance. In this study, the polycarboxylate superplasticizer (PCS) was adopted as an additive to modify cemented ultrafine tailings filling slurry. Experiment tests and numerical simulation were conducted to investigate effects of PCS dosages, solid and binder contents on rheological, fluidity, and flow performance. Results indicate that the PCS modified filling slurry conforms to Bingham model and shows shear-thinning behavior. As PCS dosage increases from 0 to 0.30 wt%, the yield stress gradually decreases, whereas the plastic viscosity initially increases then decreases. The electrostatic repulsion and steric hindrance generated by PCS can disintegrate the floc structures formed by ultrafine particles, leading to more release of free water, and reducing interparticle friction, correspondingly, improving flowability of filling slurry. The optimal PCS dosage is determined as 0.15–0.25 wt% considering transportation requirement. For a given PCS dosage, the yield stress and plastic viscosity exhibit an exponential growth with solid content, while a continuous decline with binder content. Furthermore, the fluidity increases linearly and exponentially with PCS dosage for filling slurry at solid content of 59–62 wt% and 63 wt%, respectively. An exponential model is established to quantify the relationship between yield stress and fluidity, which provides a method for predicting rheological parameters. With addition of PCS dosage, the flow performance of filling slurry is enhanced significantly in transportation pipeline. The maximal flow velocities at the pipeline center increase, and those near the pipeline wall decrease. The findings afford a practical guidance for designing and optimizing materials proportions of PCS modified filling slurry to achieve the desired flowability in mine site.

Targeted enhancement of ultra-micropore in highly oxygen-doped carbon derived from biomass for efficient CO2 capture: Insights from experimental and molecular simulation studies

The preparation of efficient CO2adsorbents is crucial for CO2capture. Compared to polymer-basedcarbons and metal-organic frameworks(MOFs), biomass-basedcarbon exhibits lower adsorption performance. Here, we prepared high oxygen doped ultramicroporous carbon through hydrothermal treatment and mechanical compaction assisted KOH activation. The study found that mechanical compaction treatment can target a 24 % increase in the volume of ultra-micropores, resulting in a CO2capture of the prepared ultramicroporous carbon reaching 5.6 mmol g−1, which is 22 % higher than that of conventionally prepared porous carbon. Molecular simulation calculations roughly estimated that functional groups and pore structures contribute 60 % and 40 %, respectively, to CO2capture at 0.15 bar, and 47 % and 53 % at 1 bar. Meanwhile, we found that the selectivity of CO2/N2is mainly related to the trend of oxygen functional groups, and is not significantly correlated with the micropore volume smaller than 0.7 nm. Theoretical calculations revealed that the introduction of oxygen groups into porous carbon resulted in an increase in selectivity of over 150 %, which is stronger than the effect of pore structure. This work provides valuable theoretical and experimental support for the design, preparation, and application of adsorbents for capturing CO2in flue gas.

Probing the capability of the MOF-74(Ni)@GrO composite for CO2 adsorption and CO2/N2 separation: A combination of experimental and molecular dynamic simulation studies

Given the significant impact of carbon dioxide emissions on current and future human life, the imperative for CO2 reduction becomes evident. Metal-organic frameworks (MOFs) composites stand out as highly effective adsorbents for CO2 capture and separation. In this study, MOF-74(Ni)@graphene oxide (GrO) composites were successfully generated through a hydrothermal synthesis route. The thermal, pore, and textural properties of the new MOF composites were experimentally tested through TGA, N2 adsorption–desorption, XRD, and FTIR. The adsorption and separation characteristics of the new MOF composites were evaluated through experimental and molecular dynamic (MD) simulation studies at ambient conditions. Interestingly, the BET surface area of all composites significantly increased compared to the pristine MOF. Among all composites, MOF-74(Ni)@GrO-10 demonstrated the highest value, surpassing others by 1060 cm2/g. MOF-74(Ni)@GrO-10 composite demonstrates the maximum amount of CO2 uptake capacity of 5.76 mmol/g experimentally and 6.65 mmol/g numerically, evidencing a substantial enhancement of 25 % and 28 % in comparison to the pristine MOF-74(Ni). The determination of CO2/N2 selectivity for all samples was carried out through a single-component isotherm under post-combustion conditions (PCO2/PN2: 0.15 bar/ 0.75 bar). Concerning CO2/N2 selectivity, the MOF-74(Ni)@GrO-10 composite also displayed the highest selective adsorption values of 44 and 45 experimentally and numerically, respectively. This marks a significant 7 % enhancement compared with the bare MOF. MOF-74(Ni)@GrO-10 exhibited a significantly higher heat of CO2 adsorption compared to bare MOF-74.As evidenced by both experimental and numerical results, MOF-74(Ni)@GrO-10 indicated 37 kJ/mol and 39 kJ/mol, and MOF-74(Ni) showed 34.5 kJ/mol and 36.5 kJ/mol heat of CO2 adsorption, implying that CO2 molecules have a stronger interaction with the composite adsorbent than the bare MOF. MOF-74(Ni)@GrO-10 also exhibited high stability, preserving 95 % of its structure after five consecutive adsorption–desorption cycles in both studies. The research finding implies that MOF-74(Ni)@GrO-10 is a promising adsorbent that can be widely used in adsorption and separation technology.

Long-chain alkyl groups enhance the water-repellent properties of short-chain perfluoroalkyl compounds: An experimental and computer simulation study

The polymers composed of long-chain stearyl acrylate (SA) and short-chain (perfluorohexyl) ethyl methacrylate (FA) were synthesized using the emulsion polymerization technique. Cotton fabric was then coated with these polymers to act as a water-repellent agent. Surface wetting properties of the coated cotton fabric were tested. In a peculiar manner, the water repellency of the coatings did not improve with the increase of the perfluorohexyl group. Therefore, the polymer's crystallization behaviors and melting temperature were assessed through differential scanning calorimetry (DSC) and computer simulation. A computer simulation was employed to analyze the density, surface energy, element distribution, chain arrangement, bond order parameter, and surface images of the polymer film. The results suggest that water repellency is not directly related to the film's surface energy but rather depends on the element proportion, bond angle distribution, and dihedral angle torsion energy. The key points will serve as invaluable indicators for the development of a highly efficient water-repellent coating with a low proportion of fluorine and provide a more sustainable solution for water-repellent applications.

Experimental, theoretical, and Monte Carlo simulation study of radiation shielding properties of La2O3-Added lithium borate glasses

The La2O3-added lithium borate glasses in the composition of (80-x)B2O3: xLa2O3: 10Li2O: 10Al2O3 (x = 10, 15, 20, 25, and 30 mol%) were prepared by the melt quenching process. The gamma-ray shielding properties of glasses were measured experimentally at various gamma-ray energies acquired from sources of 133Ba, 137Cs, and 60Co and compared with the FLUKA Monte Carlo simulation. FLUKA was also utilized for investigation and compared with the theoretical values obtained using the WinXCom program across the energy range from 0.015 MeV to 15 MeV. The mass attenuation coefficient (μm), effective atomic number (Zeff), effective electron density (Neff), mean free path (MFP) and half-value layer (HVL) were reported. From the results, it was found that adding La2O3 to the glass structure increased μm, Zeff, and Neff, while MFP and HVL decreased. The glasses exhibited the lowest HVL value, indicating improved shielding ability when compared with some shielding materials. PHITS has been utilized to simulate the variations in the absorbed dose resulting from interaction of protons within the modelled phantom. These findings demonstrate the suitability of La2O3-added lithium borate glasses as radiation shielding materials.

Desulfurization characteristics of slaked lime and regulation optimization of CFB-FGD process—A combined experimental and numerical simulation study

Circulating fluidized bed flue gas desulfurization (CFB-FGD) process has been widely applied in recent years. However, high cost caused by the use of high-quality slaked lime and difficult operation due to the complex flow field are two issues which have received great attention. Accordingly, a laboratory-scale fluidized bed reactor was constructed to investigate the effects of physical properties and external conditions on desulfurization performance of slaked lime, and the conclusions were tried out in an industrial-scale CFB-FGD tower. After that, a numerical model of the tower was established based on computational particle fluid dynamics (CPFD) and two-film theory. After comparison and validation with actual operation data, the effects of operating parameters on gas–solid distribution and desulfurization characteristics were investigated. The results of experiments and industrial trials showed that the use of slaked lime with a calcium hydroxide content of approximately 80% and particle size greater than 40 μm could significantly reduce the cost of desulfurizer. Simulation results showed that the flow field in the desulfurization tower was skewed under the influence of circulating ash. We obtained optimal operating conditions of 7.5 kg·s−1 for the atomized water flow, 70 kg·s−1 for circulating ash flow, and 0.56 kg·s−1 for slaked lime flow, with desulfurization efficiency reaching 98.19% and the exit flue gas meeting the ultraclean emission and safety requirements. All parameters selected in the simulation were based on engineering examples and had certain application reference significance.

The Design of a Parameterization Scheme for 137Cs Based on the WRF-Chem Model and Its Application in Simulating the Fukushima Nuclear Accident

Based on the Weather Research and Forecasting Model Coupled with Chemistry (WRF-Chem) atmospheric chemistry model, a parameterization scheme for the radioactive isotope caesium (137Cs), considering processes such as advection, turbulent diffusion, dry deposition, and wet deposition, was constructed, enabling the spatial distribution simulation of the concentration and deposition of 137Cs. The experimental simulation studies were carried out during the high emission period of the Fukushima nuclear accident (from 11 to 17 March 2011). Two sets of comparison experiments, with or without deposition, were designed, the effects of wind field and precipitation on the spatial transport and ground deposition of 137Cs were analyzed, and the influence of wind field and precipitation on 137Cs vertical transport was analyzed in detail. The results indicate that the model can accurately simulate the meteorological and 137Cs variables. On 15 March, 137Cs dispersed towards the Kanto Plain in Japan under the influence of northeastern winds. In comparison to the experiment without deposition, the concentration of 137Cs in the Fukushima area decreased by approximately 286 Bq·m−3 in the deposition experiment. Under the influence of updrafts in the non-deposition experiment, a 137Cs cloud spread upward to a maximum height of 6 km, whereas in the deposition experiment, the highest dispersion of the 137Cs cloud only reach a height of 4 km. Affected by the wind field, dry deposition is mainly distributed in Fukushima, the Kanto Plain, and their eastern ocean areas, with a maximum dry deposition of 5004.5 kBq·m−2. Wet deposition is mainly influenced by the wind field and precipitation, distributed in the surrounding areas of Fukushima, with a maximum wet deposition of 725.3 kBq·m−2. The single-station test results from the deposition experiment were better than those for the non-deposition experiment: the percentage deviations of the Tokyo, Chiba, Maebashi, and Naraha stations decreased by 61%, 69%, 46%, and 51%, respectively, and the percentage root mean square error decreased by 46%, 25%, 38%, and 48%, respectively.

Steel/plastic-steel hybrid fiber UHPC dynamic tensile performance: An experimental and numerical simulation study

Steel fibers (ST) in Ultra-high performance concrete (UHPC) play an important role in enhancing its mechanical strength and toughness. However, the brittleness of UHPC increases significantly under dynamic loading, while the contribution of ST to its tensile strength and fracture mode is relatively limited. In this study, Ultra-high performance hybrid fiber reinforced concrete (UHP-HFRC) was prepared using four hybrid ratios of ST and plastic steel fibers (high-performance polypropylene, PSF), and a series of quasi-static and dynamic splitting tests were conducted to investigate the effect of PSF on its dynamic tensile behavior. Additionally, X-ray computed tomography (X-CT) and SEM characterization techniques were applied to reveal the fiber synergy effect and enhancement mechanisms from the perspective of microcrack development. In addition, a novel hybrid fiber modeling method is proposed for finite element simulation of the dynamic tensile response of UHP-HFRC. The results indicate that fiber hybridization reduces the degree of damage of UHPC under dynamic loading, and its contribution is influenced by the strain rate. The increase in steel fiber content increases the dynamic tensile strength of UHP-HFRC, but the increase in PSF content contributes to the increase in energy absorption at fracture, and it is recommended to use 1 % of PSF mixed with ST. The simulation results show the constitutive relationships and failure modes that agree with the impact test results, verifying that the proposed three-dimensional mesoscopic model can effectively analyze the dynamic splitting performance of UHP-HFRC.

A Combined Experimental, DFT and Molecular Dynamics Simulation Study of Binary Mixture of Ethylbenzene and Aniline

AbstractDensity and viscosity values of the binary mixture of ethylbenzene and aniline have been experimentally measured in different mole fractions at temperatures of 293.15 to 313.15 K and at an absolute pressure of 86.7 kPa. Based on the obtained experimental data, the excess molar volume and viscosity deviations have been reported, which can interpret the interactions in this mixture. The obtained data were fitted with the Redlich‐Kister equation. In addition, the viscosity results are discussed using the equation proposed by Gruenberg‐Nissan. After experimental studies, in order to investigate the interactions of these two components and their mixture, quantum mechanical calculations and molecular dynamics simulation have been used. In this way, the structures of the desired molecules have been optimized. Then Atoms in Molecules (AIM) and frontier molecular orbital (FMO) techniques have been used for a more detailed investigation. Finally, by plotting radial distribution functions (RDFs) obtained from molecular dynamics, these interactions have been investigated in a more comprehensive way. In addition, the simulated densities at 298.15 K have been reported. At the end, clear pictures of the interactions of molecules in mixtures were obtained by comparing the achievements of experimental measurements, quantum chemical and calculations MD simulation.