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s Recently, super gas wet and gas wet surfaces have been extensively attended in petroleum industry, as supported by the increasing number of publications in the last decade related to wettability alteration in gas condensate reservoirs. In many cases, contact angle measurement has been employed to assess the wettability alteration. Even though contact angle measurement seems to be a straightforward approach, there exist many misuses of this technique and consequently misinterpretation of the corresponding results. In this regard, a critical inspection of the most recent updated concepts and the intervening parameters in the contact angle based wettability evaluation of liquid-solid-gas systems could aid to provide some remediation to alleviate this problem. To this end, this work presents a survey on the accurate terms and rigorous protocols based on the community of surface science and chemistry. As a preliminary step, advancing, receding, static, and the most stable contact angle terminology are defined. The study is followed by the definition of the contact angle hysteresis effect. The application of surface free energy in the selection of the best gas wet agent is then analyzed. Afterward, the impact of the size-dependent behavior of drop on contact angle is discussed. Finally, a sessile drop experiment is explained to achieve the defined parameters. For future contributions to petroleum industry journals, like this journal, this work could offer an easy use of the conceptual framework for analyzing the results and comparative evaluations in chemical wettability modifier agents.

Cooling enhances the energy conversion efficiency and output of photovoltaic (PV) panels. In this work, the effects of natural convection, forced convection, and evaporative cooling on the performance of polycrystalline PV panels were investigated. The output and efficiency of a cooled PV panel were monitored and compared to those of an uncooled PV panel under the same conditions. The cooling was conducted using an insulated channel installed below a PV panel. Natural convection cooling was investigated for various channel air gaps (H = 30, 60, 90, and 120 mm). Natural convection currents in the cooling channels were capable of cooling the panel with wide air gaps. In forced convection cooling, the air was introduced by fans installed at the bottom opening of the cooling channel with various air velocities (ua = 1, 2, and 3 m/s). Evaporative natural convection cooling was performed by a wetted fabric along the lower surface of the cooling channel, whereas evaporative forced convection cooling by pushing air along the wetted lower surface of the channel. The experimental data showed that the panel efficiency and output increased due to cooling. The experimental results of natural convection cooling revealed that the use of an air gap of 120 mm to cool the solar panel contributed to an increase in the panel daily energy production and efficiency by 1.7% and 1.2%, respectively. For forced convection cooling, using air at a speed of 3 m/s increased the daily energy production by 4.4% and the efficiency by 4%. Natural convection evaporative cooling increased the daily energy production and the efficiency by 3.6% and 2.7%, respectively. Forced convection evaporative cooling contributed, at a speed of 2 m/s, to an increase in the daily energy production by 3.8% and an increase in efficiency of 3.8%.

Energy pile is a kind of economic and efficient geothermal utilization technology that the ground heat exchanger (GHE) used in ground source heat pump (GSHP) is embedded into building pile foundation to realize heat exchange with surrounding soil. Adding phase change material (PCM) into the energy pile can not only reduce the temperature variation and thermal deformation range of energy pile, but also improve its energy storage and heat transfer performance. In this work, phase change concrete energy pile (PCCEP) is proposed by using PCM as a part of backfill material of energy pile. A three-dimensional numerical model is developed to find the influences of thermal properties of PCCEP on its thermo-mechanical behaviour. According to the model, the influences of thermal conductivity, phase change latent heat (PCLE) and phase change temperature (PCT) on the thermal performance and mechanical characteristics of PCCEP are numerically investigated. It can be seen that for improving heat transfer performance of PCCEP, the thermal conductivity should be increased, but from the perspective of reducing change of pile displacement, axial force and side friction resistance, the thermal conductivity should be reduced. Under heat release mode, lower PCT and larger PCLE contribute to the improvement of thermal performance of PCCEP, and accordingly the rise range of pile temperature, pile displacement change and pile thermal stress can all be reduced. The experimental validation on the model shows that the simulation values of pile wall middle temperature(PWMT) and pile top displacement are agreed well with the corresponding experimental results, the real-time relative error of PWMT and pile top displacement are respectively within 5.1 and 12%.

The tool and die applications are preferred the unconventional machining processes as they are popular in machining the difficult to cut type complex contour/ profile. The complex profile machined on hard material. Some special materials like Stainless Steel 12X18H10T withstand its inherent properties even it exposes at higher temperature. This investigation aims to expand its application by investigating its machinability in Electro Chemical machining process for surface finish. The process parameters like gap between work material and tool, discharge current, concentration of electrolyte and applied voltage at three levels. The Taguchi approach is used for optimizing the process parameters and confirmation runs also conducted for developing the mathematical modelling. For optimizing number of experiment the Taguchi L9 is utilized for this investigation.

In the present paper, we have studied the dependence of thermal conductivity on shape, size and dimension of nanomaterial. By using the quantitative expression of melting temperature, the expression for thermal conductivity is deduced in this work. Kapitza resistance term is also considered in the study to better explain the thermal conductivity variation in nanomaterials with scattering effect on thermal properties. The thermal conductivity is found to decreased as size of nanomaterials decease. The variation in thermal conductivity with size is calculated for nanowire, nanofilm, spherical, regular tetrahedral particle, regular octahedral particle, and regular icosahedral particle shapes. The results calculated in the present work are compared with the available experimental results to judge the validity of the present model.

Rechargeable magnesium batteries (RMBs), as one of the most promising candidates for efficient energy storage devices with high energy, power density and high safety, have attracted increasing attention. However, searching for suitable cathode materials with fast diffusion kinetics and exploring their magnesium storage mechanisms remains a great challenge. CuS submicron spheres, made by a facile low-temperature synthesis strategy, were applied as the high-performance cathode for RMBs in this work, which can deliver a high specific capacity of 396 mAh g−1 at 20 mA g−1 and a remarkable rate capacity of 250 mAh g−1 at 1000 mA g−1. The excellent rate performance can be assigned to the nano needle-like particles on the surface of CuS submicron spheres, which can facilitate the diffusion kinetics of Mg2+. Further storage mechanism investigations illustrate that the CuS cathodes experience a two-step conversion reaction controlled by diffusion during the electrochemical reaction process. This work could make a contribution to the study of the enhancement of diffusion kinetics of Mg2+ and the reaction mechanism of RMBs.

When agricultural goods begin to be transported by those temperatures where value added products can be transported, cold room assessments in industrial applications must be validated. Computational feedback can improve the process consistency. Data on coolant and boundary dynamics can be evaluated by means of computer fluid dynamics (CFD). Air speed and air temperature are the distribution parameters in this analysis. When the vegetable temperature is preserved with less variations in the storage room, as well as the required air distribution, the best effects of proper preservations are achieved. With proper air circulation, temperature difference is minimised. Air speed is necessary to protect the cold storage of agricultural products. This project's main objective was to observe the decrease in temperature when PCMs are used within the cold storage space. Most of the experimental results demonstrated that in the event of regular openings of doors, also in the context of electricity failures using PCM, the temperature retained inside the cool space was 1–4.5 °C lower than without PCM, even in the cases of electrical failures using PCM. The present study focuses on applying guidelines to enhance cold room technology for improved outcomes in cold storage. Present work discussed about the reference methods and the techniques used in previous literature with future recommendations.

The generalized exponential rational function (GERF) method is used in this work to obtain analytic wave solutions to the Kudryashov-Sinelshchikov (KS) equation. The KS equation depicts the occurrence of pressure waves in mixtures of liquid-gas bubbles while accounting for thermal expansion and viscosity. By applying the GERF method to the KS equation, we obtain analytic solutions in terms of trigonometric, hyperbolic, and exponential functions, among others. These solutions include solitary wave solutions, dark-bright soliton solutions, singular soliton solutions, singular bell-shaped solutions, traveling wave solutions, rational form solutions, and periodic wave solutions. We discuss the two-dimensional and three-dimensional graphics of some obtained solutions under the accurate range space by selecting appropriate values for the involved arbitrary parameters to make this research more praiseworthy. The obtained analytic wave solutions specify the GERF method’s dependability, capability, trustworthiness, and efficiency.

Torrefaction is a pretreatment method that converts biomass to a fuel-like substance that can replace coal for sustainable power generation. In this work, a thermodynamic-based process simulation model was developed to simulate the gasification of empty fruit bunch (EFB), with torrefaction as pretreatment, to determine the optimum conditions; equivalence ratio, reactor temperature, torrefaction medium concentration, steam-to-biomass (S/B) ratio and system configuration were studied to determine their influence on hydrogen concentration, higher heating value (HHV), syngas ratio and cold gas efficiency (CGE). The highest hydrogen yield was obtained at an S/B ratio of 1.3 at 800 °C, with a syngas ratio of 2.5 and a CGE of 84%. Concentration of torrefaction medium showed no effect on hydrogen concentration due to the simplicity of the model used, but work is in progress in this direction. Therefore, steam gasification is more suitable than air gasification in hydrogen production.

Rare-earth calcium oxyborate crystals (RECa4O(BO3)3, RECOB, RE: rare-earth elements) is a kind of multifunctional crystal materials. In this work, the temperature dependent behaviors of the electro-elastic constants for NdCOB crystal were investigated over the temperature range of –80–200 oC, and their temperature coefficients were evaluated. It is found that NdCOB possesses minimal variation of relative dielectric permittivities (

The fundamental understanding of the effects of rare earth (RE) on the phase transformation of Fe-based alloys is essential in the development of advanced RE-containing high strength steels. In this work, we investigated the effects of La and Ce on the martensitic phase transformation of Fe in terms of the driving force and minimum energy path (MEP) using the first-principles calculations. The calculations of formation energy show that the RE substitution increases the stabilization of fcc-Fe and decreases that of bcc-Fe, thus decrease the driving force of phase transformation. Meanwhile, the analysis based on the generalized solid-state nudged elastic band (G-SSNEB) method indicates that in the RE-containing systems, an additional energy barrier appears when the phase transformation proceeds along the Bain transition path to c/a ratio of 1.14 in the FM state, which is associated with a sudden decrease in magnetization due to the hybridization between the orbitals of the RE atoms and those of the nearest neighbor Fe atoms. The results of potential-energy surfaces (PES) confirm that magnetic ordering and lattice volume change simultaneously with the Bain transition, and in comparison with pure Fe, the variation between the onset and the end structural volumes of the phase transformation is slight for the RE-containing Fe systems.

The long-period stacking ordered phases (LPSOs) in Mg−Ni−Y system have been attracting great interest as effective strengthening components because of their unique structural characteristics and deformation mechanism. However, the phase relationships in LPSOs are complicated and unclear, which restricts the design of advanced magnesium-based alloys. The aim of the present work is to experimentally determine the phase equilibria relationships focusing on LPSOs and establish the thermodynamic description for Mg−Ni−Y system. Four types of LPSOs, that is, 14H, 12R, 18R and 10H, are confirmed through equilibrated alloys and high-resolution transmission electron microscopy (HR-TEM). The formation enthalpies of LPSOs (14H, 12R, 18R and 10H) are calculated based on density functional theories (DFT) calculations. A new ternary compound, termed as τ phase, is observed for the first time which is likely to be the distorted structure of 12R as determined from the TEM image which shows a 12-layer closed packing plane distance of 3.252 nm and a shear angle of 83.2° between (0002) and (10 1 ¯ 0) planes. Based on the determined phase equilibria relationship, the Mg−Ni−Y system is assessed and a self-consistent description is obtained where the LPSOs are modeled as the stoichiometric compounds. The comparison between the calculation result and experimental data suggests the accuracy of the present thermodynamic database in the Mg-rich corner.

Estimating oil recovery factors and oil reserves depend primarily on vertical, areal, and displacement efficiencies. This work presents a new accurate correlation to estimate the efficiency of the vertical sweep relevant to water/oil ratio (WOR), reservoir permeability variation (V), and water to oil mobility ratio (M). This correlation covers the mobility ratio of (0 ≤ M ≤ 10) and permeability variation of (0.3 ≤ V ≤ 0.8). The proposed mathematical correlation to estimate the efficiency of vertical sweep in the above range achieves a high correlation coefficient of 0.9999 with an average percentage error of −0.05 %, an average absolute percentage error of 0.53 %, and a standard deviation of 1.37 %. Furthermore, new graphical and mathematical correlations were proposed to determine the efficiency of vertical sweep and the correlating parameter (Y) covering a wide range of 0 ≤ M ≤ 50 and 0.1 ≤ V ≤ 0.9. These correlations achieve a high determination coefficient of 0.99 with an average percentage error of −0.039 %, an average absolute percentage error of 2.49 %, root mean square error (RMSE) of 0.018 and a standard deviation of 3.5. In addition to the proposed correlations, this work presents an artificial neural network model to calculate vertical sweep efficiency for the wide data range as a direct function of M, WOR, and V, with high accuracy as deduced from the calculated statistical error analysis. To the best of our knowledge, no published mathematical correlation covers this range of data presented in this work to calculate the vertical sweep efficiency.

In this work, a generalized unsteady magnetohydrodynamic transport of a rate type fluid near an unbounded upright plate is analyzed under Newtonian heating and non-uniform velocity conditions. The vertical plate is suspended in a porous medium and is encountering the radiation effects. Three different fractional models for Maxwell fluid are established by using the modern definitions of Atangana–Baleanu, Caputo–Fabrizio, and Caputo fractional operators. Triple fractional analysis is conducted to reach out to the solutions of consequent flow and energy equations. Laplace transform and Stehfest’s numerical algorithm are jointly applied to solve each fractional model. Shear stress and heat transfer rate are measured at the solid–fluid interface in the form of skin friction coefficient and Nusselt number respectively. The physical significance of associated parameters in velocity and energy boundary layers is investigated and graphs are provided to discuss the relevant physical arguments. A tabular analysis is performed to demonstrate the influence of physical parameters on shear stress and heat transfer rate. An empirical comparison between fractional and classical solutions indicates that fractional operators provide a better explanation of the physical features of the model. It is also analyzed that for Newtonian heating and non-uniform velocity conditions, the Atangana–Baleanu fractional operator is the finest fractional model to describe the memory effect of velocity and energy distribution. The velocity of a Maxwell fluid is always higher for constant velocity condition as compared to the ramped velocity condition. Furthermore, the heat transfer rate declines for increasing values of the fractional parameter α and a minimum value is witnessed for the classical model but, it follows an inverse trend when the radiation parameter R d increases.

The solution behavior of a second element in the primary phase (α(Mg)) is important in the design of high-performance alloys. In this work, three sets of features have been collected: a) interaction features of solutes and Mg obtained from first-principles calculation, b) intrinsic physical properties of the pure elements and c) structural features. Based on the maximum solid solubility values, the solution behavior of elements in α(Mg) are classified into four types, e.g., miscible, soluble, sparingly-soluble and slightly-soluble. The machine learning approach, including random forest and decision tree algorithm methods, is performed and it has been found that four features, e.g., formation energy, electronegativity, non-bonded atomic radius, and work function, can together determine the classification of the solution behavior of an element in α(Mg). The mathematical correlations, as well as the physical relationships among the selected features have been analyzed. This model can also be applied to other systems following minor modifications of the defined features, if required.

This paper reports on analysis of an experimental study that aimed to determine the apparent gas permeability in cracked concrete. There is a lack of research on this topic in the international literature, due to the difficulty of performing reliable experimental testing for gas permeability. The principal interest of this work is to present new and reliable experimental results. Analytical functions between the evolution of the apparent crack permeability and the apparent crack opening are also proposed. These functions appear to be relevant in consideration of Poiseuille theory.

Low dimensional sp3 carbon nanostructures have attracted increasing attention recently, due to their unique properties and appealing applications. Based on in silico studies, this work exploits the impacts from functional groups on the tensile properties of carbon nanothreads (NTH) – a new sp3 carbon nanostructure. It is found that functional groups will alter the local bond configuration and induce initial stress concentration, which significantly reduces the fracture strain/strength of NTH. Different functional types lead to different local bond re-configurations, and introduce different impacts on NTH. Further studies reveal that the tensile properties decreases generally when the content of functional groups increases. However, some NTHs with higher content of functional groups exhibit higher fracture strain/strength than their counterparts with lower percentage. Such observations are attributed to the synergetic effects from the sample length, self-oscillation, and distribution of functional groups. Simulations show that the tensile behaviour of NTH with the same functional percentage differs when the distribution pattern varies. Overall, ethyl groups are found to induce larger degradation on the tensile properties of NTH than methyl and phenyl groups. This study provides a comprehensive understanding of the influence from functional groups, which should be beneficial to the engineering applications of NTH.

Granular matter can exhibit solid or liquid behavior, which contains complex physical mechanisms. In this work, we experimentally investigated the structural relaxation and avalanche dynamics of particle piles under vertical vibration. The influence of vibration parameters on the avalanche process was studied. The morphological features of avalanches were recorded and classified using high-speed camera. The effects of vibration parameters and particle properties on the relaxation mode are obtained. It is found that the evolution of particle pile height with time can be described by an exponential decay function. The relaxation rate and avalanche characteristics of four types of particles with different sizes are discussed. At the same acceleration level, for two larger particles, a smaller amplitude (A = 0.025 mm) leads to a faster relaxation rate, while for two smaller particles, a large amplitude (A = 0.500 mm) leads to a faster relaxation rate. The analogy powder surface tension is introduced to address the cohesion and flowability evolution of particles under vibration.

Liquid–solid fluidized beds (LSFB) modeling validation is crucial for establishing design rules and monitoring tools. However, it generally relies on comparing global variables, which overlook dynamic features that influence reaction outputs. This work aims to implement time series analysis tools to compare Radioactive Particle Tracking data with a simulation consisting of Computational Fluid Dynamics coupled with Discrete-Element Method. Experiments have been performed in a pilot-scale LSFB of calcium alginate spheres fluidized with a calcium chloride solution. The Diks’ test indicates that the simulation can capture the LSFB behavior. It also allows diagnosing flow regime transitions from the simulation. Trends of solid dispersion coefficients and mixing times predicted by the simulation are in good agreement with the experiments.

Microdroplets and their dispersion, with a large specific surface area and a short diffusion distance, have been applied in various unit operations and reaction processes. However, it is still a challenge to control the size and size distribution of microdroplets, especially for high-throughput generation. In this work, a novel ultra-high speed rotating packed bed (UHS-RPB) was invented, in which rotating foam packing with a speed of 4000–12000 r·min–1 provides microfluidic channels to disperse liquid into microdroplets with high throughput. Then generated microdroplets can be directly dispersed into a continuous falling film for obtaining a mixture of microdroplet dispersion. In this UHS-RPB, the effects of rotational speed, liquid initial velocity, liquid viscosity, liquid surface tension and packing pore size on the average size (d32) and size distribution of microdroplets were systematically investigated. Results showed that the UHS-RPB could produce microdroplets with a d32 of 25–63 μm at a liquid flow rate of 1025 L·h–1, and the size distribution of the microdroplets accords well with Rosin–Rammler distribution model. In addition, a correlation was established for the prediction of d32, and the predicted d32 was in good agreement with the experimental data with a deviation within ±15%. These results demonstrated that UHS-RPB could be a promising candidate for controllable preparation of uniform microdroplets.

In this work, we introduce the notion of dG-Choquet integral, which generalizes the discrete Choquet integral replacing, in the first place, the difference between inputs represented by closed subintervals of the unit interval [0,1] by a dissimilarity function; and we also replace the sum by more general appropriate functions. We show that particular cases of dG-Choquet integral are both the discrete Choquet integral and the d-Choquet integral. We define interval-valued fuzzy measures and we show how they can be used with dG-Choquet integrals to define an interval-valued discrete Choquet integral which is monotone with respect to admissible orders. We finally study the validity of this interval-valued Choquet integral by means of an illustrative example in a classification problem. © 2021 This work was supported in part by the Spanish Ministry of Science and Technology, under project PID2019-108392GB-I00 (AEI/10.13039/501100011033), by the project PJUPNA-1926 of the Public University of Navarre and by the project VEGA 1/0267/21 .

Since the multi-layered structures are widely used nowadays, and due to interesting applications of cylindrical shells, this study is dedicated to analyzing free vibrational behaviors of functionally graded saturated porous micro cylindrical shells with two nanocomposite skins. Based on Biot's assumptions, constitutive relations for the core are presented and effective properties of the skins are determined via the rule of mixture. A sinusoidal theory is used to capture the shear deformation effects, and to account for the scale effects, the modified couple stress theory is employed which suggests a material length-scale parameter for predicting the results in small-dimension. With the aid of extended form of Hamilton's principle for dynamic systems, differential equations of motion are extracted. Fourier series functions are used to obtain natural frequencies and after validating them, a set of parametric studies are carried out. The results show the significant effects of porosity and Skempton coefficient, pores placement patterns, CNTs addition and distribution patterns, temperature variations, material length-scale parameter and viscoelastic medium on the natural frequencies of the microstructure. The outcomes of this work could be used to design and manufacture more reliable micro cylindrical structures in thermo-dynamical environments.

This work investigates three nonlinear equations that describe waves on the oceans which are the Kadomtsev Petviashvili-modified equal width (KP-MEW) equation, the coupled Drinfel’d-Sokolov-Wilson (DSW) equation, and the Benjamin-Ono (BO) equation using the modified ( G ′ G 2 ) -expansion approach. The solutions of proposed equations by modified ( G ′ G 2 ) -expansion approach can be trigonometric, hyperbolic, or rational solutions. As a result, some new exact solutions are obtained and plotted.

Formation of galvanic cells between constituent phases is largely responsible for corrosion in Mg-based alloys. We develop a methodology to calculate the electrochemical potentials of intermetallic compounds and alloys using a simple model based on the Born-Haber cycle. Calculated electrochemical potentials are used to predict and control the formation of galvanic cells and minimize corrosion. We demonstrate the applicability of our model by minimizing galvanic corrosion in Mg-3wt%Sr-xZn alloy by tailoring the Zn composition. The methodology proposed in this work is applicable for any general alloy system and will facilitate efficient design of corrosion resistant alloys.

We develop efficient algorithms for determining the number of global cubic fields of given discriminant. They are based on earlier work of Hasse for cubic number fields. Our new ingredients allow to enlarge the range of computations considerably. For explicit calculations we used Magma.

In this work, thermodynamic and kinetic factors that affect formation and phase transformation process of different solid forms of levofloxacin hydrochloride were investigated in detail. Dynamic vapor sorption experiments (DVS) and varying temperature-powder X-ray diffraction (VT-PXRD) experiments were carried out to study moisture-dependent stability, thermal stability as well as the transformation process between Form I and Form II. Critical water activities of levofloxacin hydrochloride were determined in temperature range of 5.0–45.0 °C. Raman spectroscopy was applied to in situ monitor the temperature-induced phase transformation and the hydration process of levofloxacin hydrochloride, and one possible mechanism consisting of multiple chemical equilibria was proposed to analyze the effect of thermodynamic and kinetic factors on the formation and transformation of different solid forms. Results show that the anhydrate, Form II would transform to the monohydrate, Form I more easily with the increasing water content. And the transition point moves toward higher water contents as the temperature increases. The results suggested that, except for thermodynamic factors, kinetic factors also play an essential role in controlling the solid forms of polymorphic compounds.

In the current work, a solar-based energy plant that includes an organic Rankine cycle, an NH 3 − LiNO 3 operated refrigeration system, reverse osmosis desalination, and hydrogen production device are integrated, modeled, and optimized. A parametric examination is designed with Matlab software to show the impact of varying primary system variables on outputs like system total energy, exergy efficiency, and total exergy output. All processes have been carried out for different working fluids, namely iso-butane, Propane, n-octane, and the results are compared. Parametric analysis reveals that at solar radiation of 800 W/m2, which is reasonable for the sun in most of the Middle East, selecting n-Octane as a working media results in an increase in the hydrogen production rate of about 150%. This also confirms the importance of selecting the right working fluid for the ORC unit. Moreover, the influence of substantial decision variables on the hydrogen production, net out pout power, exergy efficiency indicated that multi-criteria optimization is necessary. The multi-objective optimization strategy suggests the TIP = 1753 kPa, Toil = 99 °C , η i s t u r = 0.9, η i s p u m p = 0.87, and AHeliostat = 2800 m2, for the optimum state of the studied system. Additionally, the scatter distribution and sensitivity analysis for optimum point introduced by multi-criteria optimization utilized for better understanding the optimization process.

In the present work, the performance improvement of a waste heat recovery system is investigated by applying a fuel cell and thermoelectric generator. With the use of energy, exergy, exergo-economic, and environmental analyses (4E analysis), the performance of the improved system is evaluated. A mathematical simulation in the Engineering Equation Solver (EES) is developed for basic and modified systems. Comparative analysis is carried out to demonstrate the benefit of the suggested system. The logical and correct combination of appropriate subsystems can lead to the maximum exploitation of an energy source, which is the innovation of the present work. The comparison of suggested system (PR/FC-TEG) with the CHP system indicates that the net output power of the PR/FC-TEG system is 3881 kW compared with 958.4 kW for the CHP system. However adding fuel cell to the PR/FC-TEG system increase output power by about 2162 kW, and it imposes 4823 kW exergy destruction rate to the system. The exergy destruction rate of the PEM FC, regenerator, and vapor generator are about 88.96% of the total exergy destruction rate, which infers the importance of these components in the PR/FC-TEG system improvement. Parametric analysis on the PR/FC-TEG performance with changing four influencing parameters is performed. Results indicate that increasing the turbine 1 inlet temperature by about 1.1% increases the cost of generated electricity from 72.92 to 73.88 $/GJ and decreases the sustainability index from 1.68 to 1.65. The multi-objective optimization of the developed system can be a promising option for future study.

In our previous work, a partially decoupled process (PDP) was proposed for efficient conversion of ethane to increase the ethylene yield and a new structural reactor called forward-impinging-back reactor (FIB) was proposed for scale-up. In this work, the influence of changing the composition and temperature of the heat carrier was investigated by simulations with detailed chemistry to further increase of the C2 (C2H2 + C2H4) yield in the PDP of ethane. At ideal mixing conditions, the C2 yield is 75.3% without steam addition and it is 82.9% at steam addition ratio of β =1.4. In comparison, the C2 yield in an FIB reactor is 62.4% without steam addition and it increases to 78.5% with steam addition (β =1.4). The requirement of high mixing efficiency is diminished by steam addition, which is favorable for reactor scale-up.

Particle size and content of RDX are the two main factors that affect the burning stability of RDX-based propellants. However, these effects and the corresponding mechanisms are still controversial. In this work, we investigated the physicochemical processes during burning and the corresponding mechanisms through the technologies of structure compactness analysis on the base of voidage measurement and theoretical interfacial area estimation, apparent burning rate measurement using closed vessel (CV) and extinguished burning surface characterization relying on interrupted closed vessel (ICV) and scanning electron microscope (SEM). The results indicate that the voidage increased with the increase of RDX content and particle size due to the increasing interfacial area and increasing interface gap size, respectively. The apparent burning rate increased with the increase of RDX particle size because of the decreasing RDX specific surface area on the burning surface, which could decrease the heat absorbing rates of the melting and evaporation processes of RDX in the condensed phase. Similarly, the apparent burning rate decreased with the increase of RDX content at pressures lower than around 55 MPa due to the increasing RDX specific surface area. Whereas, an opposite trend could be observed at pressures higher than around 55 MPa, which was attributed to the increasing heat feedback from the gas phase as the result of the increasing propellant energy. For propellants containing very coarse RDX particles, such as 97.8 and 199.4 μm average size, the apparent burning rate increased stably with a flat extinguished surface at pressures lower than around 30 MPa, while increased sharply above around 30 MPa with the extinguished surface becoming more and more rugged as the pressure increased. In addition, the turning degree of u-p curve increased with the increase of coarse RDX content and particle size, and could be reduced by improving the structure compactness.

The volumetric weight of a package has become an essential factor in calculating the delivery cost of shipments in the international logistics market. In this work, we extend the two-dimensional vector packing problem by considering a more realistic cost structure, which is a general function of volumetric weight. The problem is to pack a set of different items into some identical bins without violating weight limits and volume capacities so that the total delivery cost is minimized. We develop an exact approach based on a branch-and-price algorithm and subset-row inequalities for the problem. To efficiently solve the pricing problem in column generation, a label-setting algorithm with an effective label dominance rule and a bounding procedure is presented. A stronger label dominance rule is derived for the case where the cost function is convex. The computational results show that the exact method is effective in solving the various test instances of the problem. If the volumetric weight is not considered, the exact method can be adapted to solve the two-dimensional vector packing problem with piecewise linear cost function and outperformed the existing exact algorithm by computing 27 optimal solutions for previously open instances.

High entropy alloys (HEAs) with superb mechanical properties have been traditionally produced by solidification and subsequent heat treatment. In this paper, we demonstrate a new route via one-step process using sub-rapid cooling. Under proper cooling rates, the CrFeCoNiAl0.6 HEA could form ultrafine FCC+BCC dual-phase structure. By varying cooling rate, we can control the fraction of the BCC phase and refinement of FCC microstructures that have tunable mechanical properties in yield strength and hardness ranging from ∼580 to ∼1460 MPa and ∼260 to ∼550 Hv. We show that the structure-property-processing relation originates from the sideplate microstructures formed during fast cooling that have specific crystallographic orientation relationship between the FCC and BCC phases and chemical segregation. This work provides a new setting for better understanding of the solid-state phase transformation in HEAs under sub-rapid solidification conditions as well as a novel method for development of high-performance HEAs.

This article is mainly devoted to the investigation on the stability and Hopf bifurcation of fractional-order neural networks with mixed delays. Applying a suitable substitution of variable, a novel equivalent fractional-order neural networks concerning single delay is set up. By analyzing the corresponding characteristic equation of the involved fractional-order delayed neural networks and choosing the time delay as bifurcation parameter, we derive a new sufficient condition to guarantee the stability behavior and the appearance of Hopf bifurcation for the considered fractional-order delayed neural networks. The study reveals that the time delay is a key factor which has a vital impact on stability and Hopf bifurcation of neural networks. The obtained results of this work can be effectively applied to design neural networks. The numerical simulations and bifurcation diagrams are displayed to verify the rationality of the analytical results.

Trichloroethylene (TCE) is largely used in industries as a cleaning and degreasing solvent. TCE is a potential carcinogen and is known to cause organ damage when exposed to prolonged higher concentrations. Numerical simulation of fixed and fluidized bed adsorption of TCE can help in the development of efficient adsorption processes to prevent industrial workers in the vicinity from acute TCE exposure. In the present work, a parametric optimization based numerical experimentation algorithm is implemented by open-source computational solvers to model fixed and fluidized bed adsorption of trichloroethylene vapors on activated carbon. The algorithm optimizes four parameters pertaining to linear driving force (LDF) formulation of surface barrier and microporous diffusion. The optimized parameters were utilized to evaluate ζ ¯ , a dimensionless number defined as the temporal and spatial average ratio of surface barrier diffusion resistance to microporous diffusion resistance. The average value of ζ ¯ is 0.139 for fixed bed operation (u/umf = 0.7), 1.130 for fluidized bed operation (u/umf = 1), 4.436 for fluidized bed operation (u/umf = 1.5) and 6.317 for fluidized bed operation (u/umf = 2). Therefore, the dimensionless number ζ ¯ may serve to predict the extent of change in amount adsorbed per unit adsorbent mass with change in fluidization velocity.

Heat transfer is of vital importance because of its application in industries. A new nanofluid class called "hybrid nanofluid" is being used to boost ordinary fluids' heat transfer capabilities and has a higher heat exponent than nanofluids. The hybrid nanofluids (HNFs) are associated with two-element nanoparticles immersed in a base fluid. The steady hybrid nanofluid flowing and thermal transport characteristics passed overhead a slippery surface are investigated in this research. The impact of nanosolid particle shapes, Porosity material, heat source, viscous dissipative flow, and radiative flux are also involved in this examination. In a regime of partial-differential equations (PDEs), the predominant flow equations are formulated. Keller-box's computational technique is the utilized method to detect the self-similar solution for formulas transformed into ordinary-differential equations (ODEs) through appropriate transmutations. Williamson hybrid nanofluid has been considered for this work, which consists of double diverse kinds of nanoparticle, Copper (Cu) and Silicon dioxide (SiO2) in the rich viscous based fluid of kind EO (Engine Oil). The noteworthy result of this analysis is that the comparing thermal transmission level of such kind of fluid (SiO2-Cu/EO) which has progressively more upsurges as compared to traditional nanofluids (Cu-EO). The lamina-shaped elements cause the utmost important thermal conductivity in the boundary- layer, whilst the lowermost thermal conductivity is detected in sphere shaped nanoparticles.

A series of single Ce3+ doped and Ce3+ and Tb3+ co-doped Na2BaCa(PO4)2 (NBCP) phosphors have been synthesized by conventional solid-stated reaction method. The crystal structure, luminescence properties, thermal stability and energy transfer were carefully investigated. The Ce3+ is inferred to substitute the Ba2+ site in NBCP lattice. The color-tunable emission from blue to green is observed by adjusting Tb3+ concentration among NBCP: 0.03Ce3+, yTb3+ phosphors. The energy transfer behavior from Ce3+ to Tb3+ ions is both illustrated by co-doped PL spectra and decay curves. The energy transfer efficiency is as high as 91.5%. The mechanism of energy transfer is resonance type of dipole-dipole transition. In this work, the optimal phosphor exhibits the excellent thermal stability which keeps at 94.9% of that initial value at room temperature when temperature reaches to 150 ˚C. The Ce3+ and Tb3+ co-doped NBCP phosphor is a promising candidate for the application in the general lighting and display fields.

In this work, using a spherically symmetric metric, we investigate a minimally interacting holographic dark energy model within the framework of Saez-Ballester Theory. We predict that the dark energy component dominating the universe is of phantom type, which will lead the model universe to cosmic doomsday (big rip singularity). As big rip and holographic dark energy are incompatible with each other, we employ a higher dimensional scenario so that the cosmic doomsday is replaced by the de-Sitter phase. The model expands with a slow and uniform change of size during the early evolution, whereas the change becomes faster, agreeing with the present observation of the accelerated expansion. The present values of Hubble’s parameter and the dark energy EoS parameter are measured to be H = 67 and λ = − 1 . 00011 , which agree with the respective values H 0 = 67 . 36 ± 0 . 54 kms − 1 Mpc − 1 and λ = − 1 . 03 ± 0 . 03 of the most recent Planck 2018 result.

In order to clarify the solvent extraction and separation behaviors of rare earths and impurity of Al during the extraction and enrichment of low-concentration leach solution of ion-adsorption rare earth ore, the extraction mechanism and separation behaviors of Nd3+ and Al3+ in the Nd2(SO4)3–Al2(SO4)3 mixed solution using P507 were studied in this work. The extraction of Nd3+ and Al3+ follows the cation exchange mechanism. With the increase of the equilibrium pH, βNd/Al in the extraction of the Nd2(SO4)3–Al2(SO4)3 mixed solution using P507 is always higher than that in the extraction of single Nd2(SO4)3 and Al2(SO4)3 solutions. It can be attributed to the fact that the extraction of Nd3+ using P507 is much faster than that of Al3+, and Al3+ is more prone to be hydrolyzed at lower pH. βNd/Al in the extraction of the Nd2(SO4)3–Al2(SO4)3 mixed solution decreases gradually with the increase of mixing time within the equilibrium pH range of 1.5–1.9. The extraction of Nd3+ using P507 is much faster than that of Al3+, but the stability of Al3+-loaded organic phase is better than that of Nd3+-loaded organic phase, thus Nd3+ in the Nd3+-loaded organic phase is gradually replaced by Al3+ in the aqueous phase with the increase of mixing time.

The intrinsic origins and formation of atomic-scale structure in multicomponent alloys remain largely unknown owing to limited simulations and inaccessible experiments. Herein, we report the formation of three-dimensional periodicity from a disordered atomic-scale structure to an imperfect/perfect ordered cluster and finally to long-range translational and rotational symmetry coupled with Nb heterogeneity. Significant atomic-scale structural clustering and atomic arrangements involving solvent or solute atoms simultaneously occurred during isothermal annealing. A close relationship between atomic-scale structural evolution and composition variation has important implications in depicting the chemical and topological packing during the early crystallization stage in metallic glasses. This work can provide a comprehensive understanding of how short-range orders evolve into long-range periodicity and will further shed light on the origins and nature of metallic glasses.

Flotation is an efficient pre-treatment technology for oily water. In this work, the interaction process between the moving oil droplet and the gas bubble was studied by high-speed camera and Bassset-Boussinesq-Oseen (BBO) theoretical model, and the experimental and simulation results of the oil droplet trajectory were compared. Moreover, the micro-particle image velocimetry system was utilized to observe the flow inside and outside of the moving oil droplet. The results show that the BBO model with the mobile bubble’s surface can reflect the velocity change trend of the oil droplet during the interaction process between the moving oil droplet and the gas bubble, but there are some significant differences between the experimental and simulation results. While the oil droplet is moving on the bubble’s surface, the velocity of the area near the contact point of oil droplet–gas bubble is less than that of the other areas inside the oil droplet. Meanwhile, the flow of water above the oil drop is more biased towards the gas bubble.

This paper shows the verification work of SARAX code system in the reactor core transient calculation based on the simplified EBR-II Benchmark. The SARAX code system is an analysis package developed by Xi'an Jiaotong University and aims at the advanced reactor R&D. In this work, a neutron-photon coupled power calculation model and a spatial-dependent reactivity feedback model were introduced. To verify the models used in SARAX, the EBR-II SHRT-45R test was simplified to an ULOF transient with an input flowrate change curve by fitting from reference. With the neutron-photon coupled power calculation model, SARAX gave close results in both power fraction and peak power prediction to the reference results. The location of the hottest assembly from SARAX and reference are the same and the relative power deviation of the hottest assembly is 2.6%. As for transient analysis, compared with experimental results and other calculated results, SARAX presents coincident results both in trend and absolute value. The minimum value of core net reactivity during the transient agreed well with the reported results, which ranged from −0.3$ to −0.35$. The results verify the models in SARAX, which are correct and able to simulate the in-core transient with reliable accuracy.

The high strength is a typical advantage of body-centered-cubic high-entropy alloys (BCC HEAs). However, brittleness and weak strain-hardening ability are still their Achilles’ heel. Here, extraordinary strength together with good tensile ductility are achieved in (Zr0.5Ti0.35Nb0.15)100-xAlx alloys (at.%, x = 10 and 20) at room temperature. Relatively low densities of less than 6 g/cm3 are exhibited in these alloys. Designing nanoprecipitates and diversifying dislocation motions are the keys to achieving such salient breakthrough. It is worth noting that the tensile strength of 1.8 GPa in (Zr0.5Ti0.35Nb0.15)80Al20 alloy is a record-high value known in reported BCC HEAs, as well as a tensile strain over 8%. Furthermore, the maximum strain of ∼25% in (Zr0.5Ti0.35Nb0.15)90Al10 alloy can challenge existing limit value, and is accompanied with a tensile strength of 1.2 GPa. The current work does not only provide novel ultra-strong and tough structural materials with low density, but also sheds new light on designing BCC HEAs with attractive performances and strain-hardening ability.

The 5.0 vol.% GNP/2024Al composites were prepared by accumulated shear deformation combined with heat treatment, i.e. the thermomechanical treatment (TMT). The results showed that homogeneous distributed GNPs that aligned along the plastic deformation direction were obtained by six-pass drawing in the solution heat treatment state. The introducing of high-density dislocations in Al matrix by multiple drawing resulted in enhanced nucleation of precipitates and subsequent uniform growth during ageing. Consequently, ultra-strength GNP/2024Al composites, with yield and ultimate tensile strength 482 and 571 MPa, respectively, were achieved. The high strength was attributed to homogeneous dispersion of undamaged GNPs, fine and dispersed precipitations and work-hardening effect. This work demonstrated that TMT could act as a feasible strategy for preparing high-performance GNP/Al composites.

Significantly enhanced varistor properties via tailoring interface states were obtained in Ca1–2x/3YxCu3Ti4O12-SrCu3Ti4O12 composite ceramics. The breakdown field was improved to 35.8 kV•cm−1 and the nonlinear coefficient in 0.1–1 mA cm−2 was enhanced to 14.6 for Ca0.67Y0.5Cu3Ti4O12-SrCu3Ti4O12. Noticeably, the withstand voltage of single grain boundary reached up to 24 V while the reported ones were constant to about 3 V. Greatly improved properties were attributed to the formation of superior grain boundary rather than the reduced grain size. Surprisingly, with distinct discrepancy of nonlinear performance in the composites, the resistance and activation energy of grain boundary exhibited little differences. Based on the double Schottky barrier at grain boundary and the field-assisted thermal emission model, it was found that the excellent electrical nonlinearity arose from the formation of deeper and broader interface states at grain boundary. In this case, interface states were not easily entirely filled and the barrier could maintain its height under applied voltage. This work provides a novel routine for enhancing the varistor properties of CaCu3Ti4O12 based ceramics by manipulating interface states at grain boundary.

Nanofluids are extremely popular among researchers because of their high heat transfer rates which have major industrial applications. The foremost aim of the present work is to investigate the impact of thermal radiation in Sisko nanofluid flow with gold nanoparticles toward a stretching surface. The combined heat and mass transfer characteristics are investigated. Nanoparticles are used with blood as a base fluid. The suitable transformations are used to convert the governing PDEs into the nonlinear ODEs. The numerical solution of the nonlinear ODEs is obtained by using the bvp4c (Labotto IIIa) based shooting method. Moreover, flow predictions for each physical parameter are discussed. Physical reasons are used to illustrate the physical consequences of flow parameters versus perceived flow fields. The outcomes show that the velocity profile is declining function of velocity slip parameter. The temperature profile of the nanofluid is upgraded for both thermal radiation parameter and volume fraction of nanoparticles.

International audience; In order to extract the most capacity out of Li-ion battery (LIB) active materials, the optimization of the electrodes architectures at the mesoscale is essential. This work focuses on the morphology of the inactive phase (carbon additives and binder) through a 3-D modeling approach based on stochastic generation of electrode mesostructures with realistic LiNi1/3Mn1/3Co1/3O2 particle size distributions. It was found that having the inactive phase as a film spread on the active material results in poorer performance in part due to the loss of active surface area when compared to an agglomerate-like morphology.

Perovskite K(Ta,Nb)O3 (KTN) single crystal has drawn great interests for its outstanding electro-optic performance and excellent piezoelectric response. However, growth of compositionally uniform KTN single crystals has always been a great challenge for the great segregation difference between Nb and Ta. In this work, we propose a thermal field optimization strategy to resolve this challenge. Homogenous Sn doped KTN (Sn:KTN) single crystal with significantly reduced composition gradient (0.003 mol/mm, 1/4–1/8 of other KTN system), minimal TC variation (13 °C) and excellent piezoelectric and dielectric response (d33 = 373 pC/N and e 33 T = 5206) has been successfully achieved. We found that the functional properties of Sn:KTN were greatly affected by the near-room temperature tetragonal-cubic phase transition. From the intrinsic aspect, longitudinal lattice deformation becomes much easier, resulting in maximum piezoelectric ( d 33 ∗ ), dielectric ( e 33 T ∗ ), elastic ( s 33 E ∗ )and electromechanical coupling ( k 33 ∗ ) coefficients along polar direction [001]C. From the extrinsic aspect, both domain wall density and domain wall mobility are greatly improved for the reduced lattice distortion, which also contribute a lot to the functional properties. This work provides a simple and practical route for designing and growing high quality crystals, and more importantly, reveals the fundamental mechanism of the phase transitions/boundaries on the functional properties.

A wave rotor is suitable for compact and efficient pressure-exchange between gas flows. This work measured the circumferential pressure distribution of the rotor/stator interfaces and utilized a CFD method to simulate the unsteady pressure waves. The experimental and CFD results showed some slopes in the circumferential pressure distributions, and the slopes indicated the traces of specific unsteady pressure waves. Such traces varied regularly if the rotational speed varied within a range from −11% to +11% off the baseline value, but they were seriously disturbed if the rotational speed varied by −45% from the baseline value. It verified that a pressure wave in a wave rotor tended to keep its pressure ratio and propagation velocity unchanged if the rotational speed varied by a small extent, and that the pressure wave could not keep its propagation patterns if the rotational speed varied by a large extent. Because of the pressure wave behaviors, the wave rotor demonstrated specific regulations of the rotational speed effects on its operational states.

NaNbO3-based ceramics usually show ferroelectric-like P-E loops at room temperature due to the irreversible transformation of the antiferroelectric orthorhombic phase to ferroelectric orthorhombic phase, which is not conducive to energy storage applications. Our previous work found that incorporating CaHfO3 into NaNbO3 can stabilize its antiferroelectric phase by reducing the tolerance factor (t), as indicated by the appearance of characteristic double P-E loops. Furthermore, a small amount of MnO2 addition effectively regulate the phase structure and tolerance factor of 0.94NaNbO3-0.06CaHfO3 (0.94NN-0.06CH), which can further improve the stability of antiferroelectricity. The XRD and XPS results reveal that the Mn ions preferentially replace A-sites and then B-sites as increasing MnO2. The antiferroelectric orthorhombic phase first increases and then decreases, while the t shows the reversed trend, thus an enhanced antiferroelectricity and the energy storage density Wrec of 1.69 J/cm3 at 240 kV/cm are obtained for 0.94NN-0.06CH-0.5%MnO2(in mass fraction). With the increase of Mn content to 1.0% from 0.5%, the efficiency increases to 81% from 45%, although the energy storage density decreases to 1.31 J/cm3 due to both increased tolerance factor and non-polar phase.

Dual-phase rare-earth-zirconate high-entropy ceramics have gained significant research interest recently. However, the large composition complexity and serious lattice distortion from multi-components doping increase the uncertainty of their crystal structures. In this work, a series of dual-phase rare-earth-zirconate medium- and high-entropy ceramics are successfully fabricated. Results of this study indicate that these dual-phase ceramics are composed of pyrochlore and fluorite structures. Simultaneously, a principal element design criterion of the pyrochlore-fluorite dual-phase medium- and high-entropy ceramics is proposed. The phase structures of pyrochlore-fluorite dual-phase samples are co-determined by the average ionic radius ratio and the size disorder parameter. When the average ionic radius ratio is in the range of 1.4 to 1.5 and the size disorder parameter is larger than 5%, it is more inclined to form pyrochlore-fluorite dual-phase structure. This work has an important guiding significance to the composition design of pyrochlore-fluorite dual-phase medium- and high-entropy ceramics.