Mass Fraction Of Particles Research Articles

Shear stiffening and magneto-induced properties of magnetorheological elastomer based on self-healing poly(urethane-urea) matrix

A novel multifunctional composite material, defined as self-healing magnetorheological elastomer (SH-MRE), which exhibits both shear stiffening and magnetorheological effects as well as self-healing ability, is obtained by dispersing carbonyl iron particles in a poly(urethane-urea) matrix. The dynamic shear properties are tested through oscillation frequency and magnetic field sweeps. When shear stress is applied with an excitation frequency of 0.1 Hz to 100 Hz, the storage modulus of the poly(urethane-urea) matrix increases sharply, showing a good shear stiffening effect. In addition to the magnetically dependent mechanical properties with a magnetic flux density of 0–0.894 T, the self-healing efficiency of the isotropic SH-MREs with destructive shear damage after healing can be influenced by the mass fraction of the carbonyl iron particles, the applied magnetic field strength and the support of trace solvents. Based on the experimental results, it is believed that the hydrogen bonds in the dynamic hard domains and the magnetic interaction forces between the carbonyl iron particles induced by the magnetic field are the cause of the good multifunctional properties.

Highly Sensitive and Stable Multifunctional Self-Powered Triboelectric Sensor Utilizing Mo2CTx/PDMS Composite Film for Pressure Sensing and Non-Contact Sensing.

Sensors based on triboelectric nanogenerators (TENGs) are increasingly gaining attention because of their self-powered capabilities and excellent sensing performance. In this work, we report a Mo2CTx-based triboelectric sensor (Mo-TES) consisting of a Mo2CTx/polydimethylsiloxane (PDMS) composite film. The impact of the mass fraction (wt%) and force of Mo2CTx particles on the output performance of Mo-TES was systematically explored. When Mo2CTx particles is 3 wt%, Mo-TES3 achieves an open-circuit voltage of 86.89 V, a short-circuit current of 578.12 nA, and a power density of 12.45 μW/cm2. It also demonstrates the ability to charge capacitors with varying capacitance values. Additionally, the Mo-TES3 demonstrates greater sensitivity than the Mo-TES0 and a faster recovery time of 78 ms. Meanwhile, the Mo-TES3 also demonstrates excellent stability in water washing and antifatigue testing. This demonstrates the effectiveness of Mo-TES as a pressure sensor. Furthermore, leveraging the principle of electrostatic induction, the triboelectric sensor has the potential to achieve non-contact sensing, making it a promising candidate for disease prevention and safety protection.

Effect of intercritical annealing temperature on microstructure and mechanical properties of V-Ti-Mo microalloyed medium Mn steel

The effect of intercritical annealing temperature on the microstructure and mechanical properties of V-Ti-Mo microalloyed medium Mn steel were investigated using a scanning electron microscope, electron backscatter diffraction, X-ray diffraction and transmission electron microscope. The results showed that the microstructure of the experimental steel in the hot rolled state and after annealing at different temperatures consisted of martensite and reverted austenite. As the annealing temperature increased, the content of reverted austenite increased linearly and reached a maximum value of 29.08 % after annealing at 650 °C. It was difficult to occur austenitic reverted transformation at an annealing temperature of 580 °C. In addition, block-like reverted austenite appeared after annealing at 600 °C, and the austenite size had the largest after annealing at 650 °C. With the increase of annealing temperature, the mass fraction of M3C particles decreased gradually, while that of MC particles increased progressively. Specifically, the mass fraction of 1–5 nm sized MC particles increased first and then decreased, indicating the precipitation strengthening effect was enhanced initially and then weakened. As the annealing temperature rose, the yield strength and tensile strength of the steels decreased gradually, whereas the elongation and impact energy gradually increased. The steel annealed at 650 °C exhibited optimal comprehensive mechanical properties, with a strength-ductility product reaching 26.8 GPa· %.

The impact of high-temperature treatments on maize growth parameters and soil nutrients: A comprehensive evaluation through principal component analysis.

In contrast to prolonged exposure to high temperatures, investigating short-term high-temperature stress can provide insights into the impact of varying heat stress durations on plant development and soil nutrient dynamics, which is crucial for advancing ecological agriculture. In this study, five heating temperatures were set at 200°C, 250°C, 300°C, 350°C, and 400°C, along with five heating time gradients of 6s, 10s, 14s, 18s, and 20s, including a control. A total of 26 treatment groups were analyzed, focusing on maize growth parameters and soil indicators. Principal component analysis was used for comprehensive evaluation. The results showed that high-temperature treatments with different heating times significantly influenced maize growth and soil properties. For instance, the treatment of 300°C+6s resulted in the longest total root length, while 200°C+6s led to the highest average root diameter. Plant height and leaf length were notably increased with the treatment of 400°C+6s. Most treatments resulted in decreased soil pH and organic matter content. Notably, the treatment of 350°C+16s showed the highest available phosphorus content, reaching 24.0 mg/kg, an increase of 4.5 mg/kg compared to the control. The study found that the average levels of active organic carbon and peroxidase were 1.26 mg/g and 3.91 mg/g, respectively. Additionally, the average mass fractions of clay, silt, and sand particles were 8.99%, 66.75%, and 24.26%, respectively. Through principal component analysis, six principal components were able to extract 19 indicators from the 26 treatments, covering 86.129% of the information. It was observed that 16 treatment methods performed better than the control in terms of soil comprehensive quality. The optimal treatment temperature and time identified for improving soil physicochemical properties and crop growth were 300°C+6s. These findings can be used to guide agricultural management and soil improvement practices, ultimately enhancing field productivity and providing valuable insights for sustainable agricultural development.

Study of shear properties and shear model of soil-rock mixture

This study investigates the shear characteristics of soil-rock mixtures, a critical factor influencing slope stability in engineering construction. Soil-rock mixtures, often exhibit poor integrity and can easily soften in water due to geological influences. The YT1200 direct shear drawing friction system was employed to conduct shear tests, analyzing the effect of varying water content and fine particle mass fraction under different normal stresses. Utilizing fractional derivatives, we formulated a fractional derivative shear model. Test results illustrated a softening phenomenon post achieving peak shear stress in the soil-rock mixture. It was found that peak shear stress is directly proportional to the normal stress, and inversely proportional to both water content and fine particle mass fraction. Additionally, the cohesion and internal friction angle decrease according to a power function with increasing water content, and non-linearly decrease with the rise of fine particle mass fraction. The proposed shear model aptly simulates the entire shear failure process of the soil-rock mixture, effectively analyzing the influence of key factors on shear characteristics. These findings contribute to the strength prediction and numerical simulation of soil-rock mixtures, thereby aiding in the design of reinforcement schemes and slope stability analysis.

Enhanced viscoelastic magneto-mechanical properties for off-axis anisotropic magnetorheological elastomers: Experiment and modelling

In this study, the microstructure of tilt angle magnetic chains is adopted to construct off-axis anisotropic magnetorheological elastomers (MREs) for tailoring viscoelastic magneto-mechanical properties. The magnetorheological behaviour of anisotropic MREs is investigated using magneto-controlled smart devices to achieve dynamic mechanical response. The viscoelastic behaviour is modelled by fractional derivative (FDM) and extended Kelvin-Voigt model (EKVM), the viscoelastic properties of anisotropic MREs are characterized by experimental and theoretical methods. Meanwhile, a magneto-induced mechanical model is established to reveal the influence of the tilt angle of the magnetic chain, the prestrain, the mass fraction of carbonyl iron particles (CIPs), and the magnetic flux on the magneto-induced mechanical properties. First, the complex moduli of anisotropic MREs with 25% and 40% mass fractions containing 0°, 15°, and 25° magnetic chains were experimentally characterized under shear mode using excitation frequency (1–100 Hz) and flux densities (300mT). The nonlinear robustness method is used to identify the parameters of the storage modulus and loss modulus functions from the experimental results in the viscoelastic theoretical models. The error analysis of anisotropic MREs for complex moduli between the theoretical and experimental solutions is evaluated at different tilt angles and CIPs contents. Finally, magnetorheological tests on anisotropic MREs verified the theoretical results on the magneto-induced elastic modulus influenced by tilt angle, magnetic particle content and flux density. The description of the storage modulus in EKVM, with an error of less than 3%, is superior to that in FDM, with an error of less than 8.1% in the frequency domain. The loss modulus of anisotropic MREs in FDM for different tilt angles and mass fractions, was accurately evaluated at low frequency compared to the EKVM solution.

Study on Bridging Characteristics of Fiber Particles in Flowing Insulating Oil Under DC Electric Field

This paper investigates the bridging behavior of fiber particles in insulating oil under the background of flow-electric coupled field, which is of great significance for explaining the micro-discharge and the deterioration of overall electrical property of insulating oil in transformer. Based on the observation experiments, a constructed oil circulation device and shooting system is used to study the bridging characteristics of fiber particle swarm in oil flow under DC electric field. The effects of electric field intensity, oil flow velocity and mass fraction of particles in oil on the bridging process are analyzed in detail, and the changes of conduction current between electrodes under different conditions are recorded. The results show that the bridging behavior of fiber particle swarm is the result of the combined action of flow field and electric field. The forces provided by electric field on the fiber particles cause them to aggregate and bridge between electrodes, and with the increase of field intensity, the bridging speed increases significantly. The influence of flow velocity is more complicated, and it has different effects on the bridging process of particles under low and high field intensity. The mass fraction of fiber particles in oil is negatively correlated with the difficulty of bridging between electrodes. Finally, the bridging mechanism is explained from the perspective of the forces on particles and electric field distortion, and the variation characteristics of conduction current between electrodes are analyzed.

Hardness and tribological behaviour of annealed electroless nickel phosphorus composite layers with incorporated boron particles

In this study, a possible alternative to hard chromium coatings is investigated. Amorphous boron particles have been incorporated in electroless nickel‑phosphorus (NiP) deposits, yielding a dispersion coating. The distribution of the particles is homogenous and the maximum mass fraction of particles embedded in the coating is 6.2 ± 0.2 wt%. Measurements of the zeta potential and particle size of amorphous boron particles in a diluted electrolyte showed that the particles withstood agglomeration until 120 days. Primary and secondary hardness maxima are observed after thermal annealing at 400 °C and 860 °C due to the formation of nickel phosphide, nickel boride and nickel boride phosphide phases. X-ray diffractometry shows an increase in nickel and nickel phosphide crystal size at 400 °C before levelling off at 600 °C. The annealing duration should be kept between 30 and 60 min for optimal hardness. The wear resistance increases when the coating is annealed at 400 °C. DSC measurements on nickel phosphorus incorporated with boron particles, Ni-P-B, bulk material with P-content (9.6 ± 0,6 wt%) and B-content (4.5 ± 0.8 wt%) showed that the solidus line lies at 926 °C, which is why a maximum annealing temperature of 860 °C was chosen to avoid melting of the material. The relative texture and phase coefficients, RTC and RPC, showed that the nickel phase is preferred in the NiP system at 400 °C and 600 °C while the Ni3P phase is preferred in the Ni-P-B system at the same annealing temperature. REM and EDX area analyses are used to show the areal distribution of nickel, phosphorus, and boron before and after the annealing process along the thickness of the coating. A diffusion layer between substrate and coating that contains iron nickel boride and iron nickel phosphide lamellar structure is observed.

Effect of aerosolized TiO2 nanoparticles on enhanced heat transfer performance in a pipe flow: Experimental investigation

In this experimental investigation, the effect of TiO2 nanoaerosol on the forced convective heat transfer in a pipe flow is investigated. The experiments are conducted at various particle mass fractions (0.005, 0.01, and 0.05), Reynolds numbers (1600, 2100, and 2600), and heat inputs (30, 60, and 90 W). At these operating conditions the Nusselt number, aerosol heat transfer coefficient, and temperature distribution are recorded to analyze the heat transfer performance of the TiO2 nanoaerosol. In this regard, the maximum heat transfer enhancement of the TiO2 nanoaerosol is monitored at the peak operating conditions. The enhancement of the Nusselt number value for the particle mass fraction of 0.05 is reported to be 31.88 ± 0.51%, 14.77 ± 0.63%, and 17.34 ± 0.66% compared to the particle mass fraction of 0.005 at the maximum nanoaerosol Reynolds number of 2600 for 30, 60, and 90 W heat inputs. Simultaneously, the influence of Reynolds numbers and particle mass fractions on the pressure drop of the TiO2 nanoaerosol is studied. The friction factor, viscosity of nanoaerosol, nanoparticles agglomeration, and the Brownian motion of the nanoparticles contributed to the enhancement of the pressure drop. For all particle mass fractions, the average pressure drop is 183% higher at the Reynolds number (2600). While increasing the particle mass fraction causes the pressure drop to increase by 9 times at the constant Reynolds number.

Mechanical and high-temperature wear resistance properties of WC-reinforced AlCoCrFeNiTi0.5 high entropy alloy matrix composite

x wt.% WC/AlCoCrFeNiTi0.5 (x = 0, 5, 8, 10, 15) high entropy matrix composites (HEAC) with different mass fractions of WC particles were prepared by mechanical alloying (MA) and spark plasma sintering (SPS). Their microstructure, mechanical properties, room-temperature (RT) and high-temperature (HT) wear resistance properties were investigated. It shows the sintered HEACs are mainly composed of a face-centered cubic (FCC) solid solution matrix, (Fe, Co)6W6C, and other carbides. The increase of WC particles leads to the fracture strength and wear resistance of AlCoCrFeNiTi0.5 being increased first and then decreased. The 8 wt% WC/AlCoCrFeNiTi0.5 HEAC shows higher strength and better wear resistance properties due to the formation of carbides and protection of the dense oxide film on the worn surface. The high-temperature wear mechanism is mainly adhesive wear, and oxidative wear in the case with lower WC content, but it becomes adhesive wear, abrasive wear, and oxidative wear in the case with higher WC content. This work provides light for investigating tribological properties of high-entropy matrix composites for surface engineering.

Acoustic Characterization of Transmitted and Received Acoustic Properties of Air-Coupled Ultrasonic Transducers Based on Matching Layer of Organosilicon Hollow Glass Microsphere.

An air-coupled transducer was developed in this study, utilizing hollow glass microsphere-organosilicon composites as an acoustically matching layer, which demonstrated outstanding acoustic performance. Firstly, a comparison and analysis of the properties and advantages of different substrates was carried out to determine the potential application value of organosilicon substrates. Immediately after, the effect of hollow glass microspheres with different particle sizes and mass fractions on the acoustic properties of the matching layer was analyzed. It also evaluated the mechanical properties of the matching layer before and after optimization. The findings indicate that the optimized composite material attained a characteristic acoustic impedance of 1.04 MRayl and an acoustic attenuation of 0.43 dB/mm, displaying exceptional acoustic performance. After encapsulating the ultrasonic transducer using a 3D-printed shell, we analyzed and compared its emission and reception characteristics to the commercial transducer and found that its emission acoustic pressure amplitude and reception voltage amplitude were 34% and 26% higher, respectively. Finally, the transducer was installed onto a homemade ultrasonic flow meter for practical application verification, resulting in an accuracy rate of 97.4%.

Portable organophosphorus pesticide detection device based on controllable microfluidic and luminol composite nanofibers

Excessive organophosphorus pesticide residues in food are a serious threat to human health, it is very urgent to develop a portable, low-cost, and high precision pesticide residue detection device to achieve rapid detection of organophosphorus pesticide residues. In this study, a portable organophosphorus pesticide detection device equipped with microfluidic and luminol composite nanofibers was developed. The microfluidic chip was designed and optimized by a combine of mathematical model and multi-physics coupling simulation. The luminol particles were solidly loaded on polyacrylonitrile (PAN) electrospinning film through electrospinning method to achieve efficient utilization of microfluidic chips and luminol fluorescent reagents. The influence of the mass fraction of luminol particle on the microstructure of electrospinning film was analyzed, and the optimal mass fraction was determined by measuring the fluorescent stability and fluorescent intensity. The electrospinning film and the microfluidic chip was loaded to an independently developed portable organophosphorus pesticide detection device, whose detection limit can reach 0.035 mg/L and the average detection time can reach 30 s. The portable organophosphorus pesticide detection device shows high stability, high detection accuracy and efficiency, which can be widely adopted in the detection of organophosphorus pesticides.

Sources and composition of elemental carbon during haze events in North China by a high time-resolved study

Despite the implementation of stringent emission reduction measures in the past year, severe winter haze events still occurred frequently in North China, with only marginal decreases observed in elemental carbon (EC) concentrations. EC not only constitutes a fraction of particle mass but also interacts with boundary layer and influences haze formation. Given the complex composition of EC, characterizing its sources and composition during haze processes is challenging yet crucial for understanding haze formation and evolution. Here, hourly-resolution PM2.5 samples were collected during three different haze event (P1-P3) in the North China Plain to investigate dynamic changes in EC source across different haze processes. The average EC concentrations and char/soot ratios were 9.94 ± 4.80 μgC·m−3, 14.5 ± 6.93 μgC·m−3, 15.9 ± 5.54 μgC·m−3, and 2.42 ± 0.98, 2.70 ± 0.88, 2.61 ± 0.95 for P1, P2 and P3, respectively. Backward trajectory analysis showed distinct variations in EC concentration and composition under the influence of different air masses during the three haze events, with local air masses influenced days exhibiting higher EC concentrations and char/soot ratios. The char/soot ratio based diagnostic method suggested that EC was predominantly influenced by coal combustion and vehicle emissions. Further positive matrix factorization analysis suggested that biomass burning and residential coal combustion were the main contributors of EC (58 %) and played a dominant role in driving variations in EC concentrations during haze episodes. Potential source contribution function analysis results highlight that local biomass burning and residential coal combustion could be major reason for the EC elevation in different haze events. Our results provide valuable insights into the sources and composition of EC during haze events, facilitating the implementation of effective measures for mitigating both EC and PM pollution.

Statistical modelling and kinetics of copper loss to printed circuit board (PCB) fibreglass during PCB ammine leaching

ABSTRACT PCB dust leach feed contains fibreglass particles responsible for incomplete copper recovery observed during PCB dust leaching. Interaction of fibreglass particles with ammine leach solution was studied by varying contact time, operating temperature and pulp density at different initial concentrations. Box Behnken RSM design was utilised to design the experimental tests. The 3D plots, ANOVA, Pearson correlation and multiple regression analysis show the initial copper concentration impacts the response QCu most. Of the five non-linear adsorption kinetic models employed, Elovich and Avrami's kinetic model best fitted the experimental data with R2 of 0.9632 and 0.9435, respectively. The pHpzc analysis of fibreglass particles shows the material possesses a neutral surface charge at pH = 7.1. Evaluation of the kinetic models and pHpzc analysis of copper losses to PCB fibreglass particles supports dual mechanisms of physisorption and ion exchange co-occurring in the solid–liquid systems. At 1 g fibreglass particles in 100 mL of 50 mg/L copper ammine leach solution, maximum loss of about 1.5 mg/L copper was obtained in 12 h. This clearly indicates limitation to maximum target metal recovery. Copper loss to fibreglass particles occurs during PCB leaching up to an amount which depends on the mass fraction of the glass fiber particles in the pulp, leach solution concentration and time.

Diffusion mechanism of solid waste product utilization pulping and fracture network grouting

China's commitment to achieving carbon neutrality by 2060 has highlighted the pressing need for effective solid waste recycling. The reinforcement of mine water hazards has led to increased production costs due to the significant consumption of slurry. This study focuses on the development of mine crack grouting sealing and reinforcement materials using mine slag powder and waste rubber particles, along with cement reinforcement and alkali slag stimulation. The impact of water-cement ratio, rubber particle content, and slag mass fraction on slurry performance is analyzed, and the optimal values for these parameters are determined. A two-phase seepage simulation using COMSOL is conducted to investigate the flow and diffusion of slurry in a fractured network rock mass. The findings indicate that a water-cement ratio of 0.7 and a slag and rubber particle mass fraction of 70% and 30% respectively result in the slurry with favorable fluidity and mechanical properties. The diffusion pattern of the slurry in the fractured rock mass is characterized by vortex-like diffusion. The stability of the fractured rock mass is influenced by both grouting time and pressure, which should be carefully considered during on-site operations. This research has significant implications for the integrated prevention and control of mine water hazards and the large-scale utilization of high-dosage solid waste, thereby ensuring production safety, ecological environment safety, and sustainable development in mining areas.

Hardness prediction in the upsetting process of Al%ZrO2—an approach to machine learning using regression and classification models

The current study focuses on the prediction of metal hardness distribution in upsetting tests for different compositions of ZrO2 embedded with an aluminum matrix using machine learning algorithms and finite element (FE) analysis. The mass fraction of the ZrO2 particles varied from 4% to 8%, and three sets of solid cylindrical rods with Al4%ZrO2, Al6%ZrO2, and Al8%ZrO2 were prepared using the stir casting method. The upsetting process was simulated, and an equation for predicting hardness was developed from the equivalent strain distributions. Artificial neural networks (ANNs), multilinear regression (MLR) along with equations developed from FE analysis were used to train the model for regression analysis, considering the principal stresses, friction factor, anisotropy ratio, effective strain, and hoop strain as input and the magnitude of hardness as output parameters. Regression analysis reveals that ANN (tri-layer network), XGBoost, and MLR algorithms are the best suitable for the given data sets with a root mean square ( R2) greater than 0.95. XGBoost, ANN (narrow), and SVM are linear and are the most recommendable classifier algorithms for the current investigation. Hardness data from ring compression tests were used to validate the results obtained from the trained models with the test results.

Residential combustion of coal: Effect of the fuel and combustion stage on emissions

Worldwide coal is still used for household heating purposes not only because it is available and cheap but also due to behavioural issues. Regional variability in fuels and combustion appliances make accurate emission estimates from this source hard to achieve. In the present study, gaseous (CO, VOCs, SO2 and NOX) and particulate matter (TSP) emission factors (EFs) were determined for Spanish household coal combustion covering three commercial coals and distinct combustion stages and mimicking usage patterns in real households. TSP samples were analysed to determine water-soluble inorganic ions, metal(loid)s, and organic and elemental carbon (OC and EC). Additionally, the morphology of the emitted particles was also characterised.CO (3.43–169 g kg−1), NOX (1.29–6.00 g kg−1) and SO2 (8.96–22.3 g kg−1) EFs showed no trend regarding the combustion stage or coal type tested. On the other hand, VOC, TSP and EC EFs were higher for the ignition/devolatilisation combustion stage, regardless of the fuel tested. TSP EFs (0.085–1.08 g kg−1) increased with increasing coal volatile matter while the opposite trend was recorded for VOC emissions (0.045–3.39 gC kg−1).TSP carbonaceous matter was dominated by EC while OC represented a small fraction of the particulate mass emitted (less than 8 %wt.). Inorganic compounds composed an important fraction of the TSP samples. Sulphate particulate mass fractions (8.66–22.9 %wt.) appeared to increase with coal S-content. Coal combustion released particles with diverse morphologies, including silicate-rich particles, ferro- and glassy-spheres. This study provides novel emission factors to update emission inventories of residential coal combustion. Additionally, detailed chemical profiles were obtained for source apportionment.

The Effect of Temperature on the Size and the Deposition of Asphaltene Particles

Summary The deposition of asphaltene as a main component of crude oil is considerably affected by temperature. Despite the studies on influencing factors on deposition and size of asphaltene particles, no experimental research was previously conducted on the simultaneous impact of temperature on asphaltene particle size and deposition. In this study, the asphaltene deposit mass was measured within a Couette device at various temperatures ranging between 20 and 65°C under a constant angular velocity. Furthermore, the asphaltene particle size was simultaneously measured to investigate the relationship between deposition mass and asphaltene particle size and also to validate the concept of critical particle size. A digital microscope was used to measure the size of unstable asphaltene particles in oil. Asphaltene solubility and oil viscosity were measured to understand the deposition mechanisms. The analysis of microscopic images indicated that larger asphaltene particles are produced at higher temperatures. Although the total mass of the deposit was decreased with temperature, the deposition fraction, defined as mass fraction of total unstable asphaltene particles that deposit, was increased. Higher fraction of deposition was found for larger particles that is in contradiction to the previously introduced critical particle size concept. Additionally, the effect of solubility was found to be dominant in comparison with viscosity from the point of view of the total mass of the deposit. For the oil sample investigated in this study, a 45°C increase in temperature reduced the total mass of the deposit by 46.84%.

A Eulerian population balance/Monte Carlo approach for simulating laminar aluminum dust flames

Recently, metal powders have been conceptualized as carbon-free recyclable energy carriers that may form a cornerstone of a sustainable energy economy. The combustion of metal dusts in oxidizing atmospheres is exothermal and yields oxide particles that could, potentially, be retrieved and, subsequently, recharged by conversion to pure metals using green primary energy sources. As a step towards a predictive tool for designing metal dust combustors, we present a fully Eulerian modelling approach for laminar particle-laden reactive flows that is, conceptually, based on a population balance description of the dispersed particles and relies on a stochastic Eulerian solution strategy. While the population balance equation (PBE) is formulated for the number-weighted distribution of characteristic properties among all particles near a spatial location, it is kinetically informed by the rates at which mass, momentum and heat are exchanged between the carrier gas and the particulate phase on the single particle level. Within the scope of the Eulerian Monte Carlo solution scheme, the property distribution is discretely represented in terms of the total number density and a finite number of property samples and the computational work is channelled towards the Eulerian estimation of mean particle properties.For the case of reactive aluminum particles, we combine a kinetic description of the gas-particle heat and mass transfer with a transport-limited continuum formulation to obtain rate expressions that are valid across the entire particle size range from the free molecular through the continuum regime. Besides velocity, the particle properties include only the particle mass, temperature and oxide mass fraction. This set of thermochemical degrees of freedom is retained also as phase transitions due to melting occur, drawing on a smooth blend of the solid and liquid thermodynamic and material properties. The particle-level formulation encompasses aluminum evaporation, surface oxidation, scavenging of oxide smoke, oxide evaporation/dissociation and radiation. After investigating how these effects translate, through the PBE, to the particle population level and affect the combustion in a homogeneous dust reactor, we analyze the combustion of an aluminum dust in a counterflow flame and validate predictions of the particles’ centerline velocity profile and the flame speed by comparison with available experimental data. Concomitantly, nitrogen oxide emissions are investigated along with the particle burnout and outlet size distribution.

Tunable contact angle hysteresis on compliant magnetoactive elastomers

It is shown that the advancing (ACA) and receding (RCA) contact angles of water on extremely soft (shear modulus of the order of 10kPa) magnetoactive elastomer (MAE) films significantly depend on the applied magnetic field. The difference between these angles, known as the contact angle hysteresis, is examined. The roles of the filler concentration and material softness are elaborated. The highest change in the contact angle hysteresis (CAH) from 34∘ in the absence of magnetic field to 76∘ in a magnetic field of 0.4T is achieved for the softest sample with the lowest mass fraction of iron particles (70wt%). The dependence of the CAH on magnetization history (“magnetic hysteresis”) is observed. This magnetic hysteresis is clearly pronounced for the ACA and has little effect on the RCA. Magnetic field-induced changes of the surface roughness exhibit qualitatively the same hysteresis behavior with regard to the external magnetic field as the ACA. The results are promising for the development of smart surfaces for applications where the dynamic wetting has to be controlled.