Search

We combine X-ray-specific tracer particles, a photon counting detector, and a liquid metal jet anode X-ray source to achieve O(1 kHz) X-ray imaging speeds in the laboratory, 15× faster than previous comparable studies with O(50 μm) tracers. To examine the limits of this measurement technique we conduct three experiments: 2D and 3D X-ray particle velocimetry (XPV) of Poiseuille pipe flow, 3D XPV of flow around a Taylor bubble, and 3D scalar mixing with a laminar jet. These experiments demonstrate the performance improvement achievable by combining the aforementioned elements, the applicability to multiphase flows and deforming systems, and the potential to capture scalar and vector quantities simultaneously. Most importantly, these experiments are conducted with a laboratory-scale system, showing that in-lab X-ray particle velocimetry techniques are now becoming usable for a wider range of flows of interest. Furthermore, the design of XPV experiments is discussed to clarify the trade offs between achievable imaging speed, domain size and spatiotemporal resolution.

Effective flow line and piping network design depends on the accurate prediction of pressure drop in multiphase flow for horizontal and near horizontal pipes. Since early 1950, several empirical correlations and mechanistic models have been developed to predict pressure drop. All correlations used by the industry, in addition to their applicability limitations, fall short of providing the necessary precision of pressure drop predictions. However, compared to empirical correlations, the recently developed mechanistic models improved pressure drop prediction. To design and construct more dependable and economical surface piping networks and wells, it is still necessary to improve prediction accuracy. This study uses the Adaptive Neuro-Fuzzy Inference System (ANFIS) to create a model that predicts pressure drop in horizontal and near-horizontal pipelines with greater accuracy and simplicity. Using the ANFIS method, the fuzzy modelling procedure can gather knowledge about a set of data to determine the membership function parameters that will enable the associated fuzzy inference system to track input/output data most effectively. The model was created and tested using field data encompassing various variables. The model was developed using 450 different data sets that were collected from the Asian continent. 113 data sets were used for testing, and a total of 337 data sets were used for training. Trend analysis was carried out during the model development phase prior to the model’s completion. This is performed to make sure the model is stable and to make sure the created model is physically sound and accurately simulates the real physical process. To determine the percentage of error between the predicted value and the actual measured data, statistical analysis was carried out. To compare the performance of the new ANFIS model to earlier empirical correlations and mechanistic models, graphical and statistical techniques were also used. The new model outperformed known correlations and the most recent mechanistic models by a significant margin in producing incredibly accurate pressure drop predictions. The Dukler et al. empirical correlation, Beggs and Brill empirical correlation, Xiao mechanistic model, and Gomez mechanistic model had values of 25.284, 20.940, 30.122, and 20.817, respectively, while the ANFIS model had a value of 13.256 for the lowest average absolute percentage error. Additionally, the Duckler and Beggs & Brill models came in second and third, with values of 0.908 and 0.906, respectively, and the ANFIS model had the highest coefficient of determination at 0.955. [ABSTRACT FROM AUTHOR]

Summary: This paper presents more compatible three‐stage inverter‐based ring voltage controlled oscillators (VCOs) by modifying the current‐starved delay cell to oscillate with high tuning range. Unlike some ring structures in which extra transistors are used as current boosting to enhance the frequency tuning range, no extra elements are used in the proposed three‐stage VCOs for increasing the tuning range. Besides, a new method is introduced to couple two proposed ring VCOs for designing a six‐phase ring VCO. The coupling method can be generalized to some other ring VCOs to generate multiphase signals. The proposed circuits have wide frequency tuning ranges and show good noise performances. The proposed six‐phase VCO can oscillate from 1.62 GHz to 3.45 GHz, which illustrates 72.2% tuning range. The phase noise of the proposed VCO is −97.5 dBc/Hz at 1 MHz offset frequency. The circuit figure of merit is −181.5 dBc/Hz. The post‐layout simulation results of the proposed six‐phase VCO are provided based on the TSMC 0.18 μm CMOS process. [ABSTRACT FROM AUTHOR]

Abstract Microfluidic devices with complex geometries and obstacles have attracted considerable interest in biomedical engineering and chemical analysis. Understanding droplet breakup behavior within these systems is crucial for optimizing their design and performance. This study investigates the influence of triangular obstacles on droplet breakup processes in microchannels. Two distinct types of triangular obstructions, positioned at the bifurcation (case I) and aligned with the flow (case II), are analyzed to evaluate their impact on droplet behavior. The investigation considers various parameters, including the Capillary number (Ca), non-dimensional droplet length (L*), non-dimensional height (A*), and non-dimensional base length (B*) of the triangle. Utilizing numerical simulations with COMSOL software, the study reveals that the presence of triangular obstacles significantly alters droplet breakup dynamics. Importantly, the shape and location of the obstacle emerge as key factors governing breakup characteristics. Results indicate faster breakup of the initial droplet when the obstacle is positioned in the center of the microchannel for case I. For case II, the study aims to identify conditions under which droplets either break up into unequal-sized entities or remain intact, depending on various flow conditions. The findings identify five distinct regimes: no breakup, breakup without a tunnel, breakup with a tunnel, droplet fragmentation into unequal-sized parts, and sorting. These regimes depend on the presence or absence of triangular obstacles and the specific flow conditions. This investigation enhances our understanding of droplet behavior within intricate microfluidic systems and provides valuable insights for optimizing the design and functionality of droplet manipulation and separation devices. Notably, the results emphasize the significant role played by triangular obstacles in droplet breakup dynamics, with the obstacle’s shape and position being critical determinants of breakup characteristics.

Cycling stability is the biggest challenge for cathodes of sodium‐ion batteries (SIBs), which is directly affected by the structure design. Herein, the combination of high‐entropy (HE) and multiphase structure is demonstrated to be helpful for maintaining the structure and improving the cycling stability. In the Ni/Mn/Cu/Ti/Sn five‐component HE multiphase cathode, the multiple elements at transition metal sites can enlarge the lattice and stabilize the structure simultaneously without causing an obvious capacity drop, achieving the synergistic effect of multi‐cations. In the HE cathodes consisting of P2 and O3 phases, the harmful phase transition in high‐voltage is suppressed and the cycling performance is improved. A capacity retention of 77.3 mAh g−1 after 300 cycles is delivered, and an improved rate performance of 88.7 mAh g−1 at 750 mA g−1 is observed, better than that of the low‐entropy multiphase cathode(P2 and O3) and the HE oxide single O3‐phase cathode. The weighted average ionic radius(WAIR) of all transition metals is demonstrated critical for the formation of the phase composition in HE composites. Through comparing a series of HE and multiphase cathodes, an empirical range of WAIR is obtained, which shows guidance for the design of other cathode materials. [ABSTRACT FROM AUTHOR]

This paper proposes an improved cumulant collision model for the pseudo-potential lattice Boltzmann method (LBM) to increase the stability of multiphase flow simulations involving low viscosities. This model is based on the work of Kharmiani et al. in (J Stat Phys 175: 47, 2019), which can be extended regardless of the collision model. The original cumulant collision model (Geier et al. in Comput Math Appl 70:507, 2015) causes a non-physical shape of droplets in pseudo-potential LBM because only the first-order central moments are considered in the forcing scheme. The improved cumulant collision model proposed in this paper applies the central moment forcing scheme to the original cumulant model to cover the high-order central moments. Several numerical simulations were carried out to validate the proposed model. First, the problem of a stationary liquid layer was solved, where the proposed model was demonstrated to be thermodynamically consistent. Second, the problem of a stationary droplet was solved, where the result agreed well with Laplace’s law. Third, the problem of a droplet impact on a liquid film was solved, where the crown radius agreed well with the analytical and numerical results available. Fourth, the simulation results carried out with the raw moment, central moment, and the proposed improved cumulant collision models were compared, as the liquid and vapor viscosities were gradually lowered. With all else being equal, only the lattice Boltzmann method with the proposed improved cumulant collision model was able to successfully simulate a density ratio of 720 and a Reynolds number of 8.7 × 10 4 . [ABSTRACT FROM AUTHOR]

Background: Breath-hold volumetric interpolated breath-hold examination (BH-VIBE) of multiphase contrast-enhanced liver magnetic resonance imaging (MPCE-LMRI) requires good cooperative individuals to comply with multiple breath-holds. Purpose: To develop a free-breathing modified VIBE (FB-mVIBE) as a substitute of BH-VIBE in MPCE-LMRI. Material and Methods: We modified VIBE with a high acceleration factor (2 × 2) and four averages to produce the mVIBE scan. A total of 90 individuals (40 men; mean age = 54.6 ± 10.0 years) who had received MPCE-LMRI as part of a voluntary health check-up for oncology survey were enrolled. Each participant was scanned in four phases (pre-contrast, arterial phase, venous phase, and delay phase), and each phase had two sequential scans. To encounter the timing effect of contrast enhancement, three scan orders were designed: BH-VIBE and FB-mVIBE (group A, n = 30); BH-VIBE and FB-VIBE (group B, n = 30); and FB-mVIBE and BH-VIBE (group C, n = 30). The comparisons included the objective measurements and 25 visual-score by two abdominal radiologists independently. Results: Consistency between raters was observed for all three sequences (intraclass correlation coefficient [ICC] = 0.741–0.829). For rater 1, the mean scores of FB-mVIBE (23.67 ± 1.32) were equal to those of BH-VIBE (23.83 ± 1.98) in groups C and B (P = 0.852). The mean scores of FB-mVIBE (22.07 ± 3.02), but significantly higher than those of FB-VIBE (14.7 ± 3.41) in groups A and B (P <0.001). Similar scores were found for rater 2. The objective measurement of FB-mVIBE were equal to or higher than BH-VIBE and markedly superior to FB-VIBE. Conclusion: FB-mVIBE is a practical alternative to BH-VIBE for individuals who cannot cooperate with multiple breath-holds for MPCE-LMRI. [ABSTRACT FROM AUTHOR]

When considering multiphase flow scenarios, the interpretation of petrophysical properties poses significant challenges for production forecasts and reservoir modeling. The findings of the numerical modeling were therefore subject to uncertainty because characteristics like relative permeability and capillary pressure curve were hardly ever bound by interpretations. The uncertainty may result in inaccurate predictions of reservoir performance and skewed perceptions of the reservoir. Due to the difficulty in directly interpreting such property from the available field data and the expensive cost of coring, analyses or experimental measurements to determine relative permeability and capillary pressure were infrequently carried out. Such a gap would be filled by a straightforward yet rigorous method. In this study, we develop production projections for a wide range of three-phase compositional volatile oil reservoirs. Then, we used an artificial neural network to figure out how petrophysical characteristics and production data relate to one another. The artificial neural network model was adjusted, and the final trained model was tested blindly to determine how well it predicted permeability, multiphase relative permeability, and capillary pressure data. For the testing scenarios, consistency is seen between the predicted values and the original ones, despite some mispredictions being present. To provide production projections that can be compared to those from the reservoir model that include the initial petrophysical characteristic, the anticipated properties are then propagated into reservoir models. The comparison findings show that for 65/59/34 out of 74 testing scenarios, the reservoir model with artificial neural network-predicted features can anticipate oil/gas/water output with < 20% inaccuracy. With the developed artificial neural network tool, the reservoir engineers can evaluate the three-phase relative permeability surface from rate-transient data conveniently improving the accuracy of the relative permeability data implemented by history matching or from core experiments which sometimes are extremely expensive. The findings of this study can help for a better understanding of the relationships between three-phase rate-transient data and the relative permeability surface as well as the horizontal/vertical permeability. [ABSTRACT FROM AUTHOR]

The dephosphorization behavior of multiphase steel slag in converter steelmaking process is very important for higher steel quality with ultra-low phosphorus content. In this paper, the multiphase steel slag with different BaO content reacted with hot metal at 1873 K temperature. The influence of the reaction on dephosphorization was investigated. The mineralogical phase was observed. The phosphorus partition between phosphorus enriched phase and liquid phase was discussed. The phosphorus partition ratio between steel slag and hot metal was obtained. The main mineralogical phases of steel slag were phosphorus enriched phase mCa2SiO4-Ba1-xCax(PO4)2 and RO (FeO/MgO) phase. The barium existed in phosphorus enriched phase and liquid phase, not in RO phase. The phosphorus content in phosphorus enriched phase increased from 1.12% to 1.36% with the addition of BaO. The phosphorus partition ratio between phosphorus enriched phase and liquid phase increased from 2.60 to 3.77, increased 45.00% by the addition of BaO. The phosphorus partition ratio between steel slag and hot metal increased from 55.35 to 97.50, increased 76.15% by the addition of BaO in steel slag. [ABSTRACT FROM AUTHOR]

AbstractNuclear thermal propulsion (NTP) is a highly efficient type of propulsion system that could yield a specific impulse up to 800 s. High-performance NTP allows for possibilities of various mission types from flyby to interplanetary flight, manned or unmanned. Centrifugal nuclear thermal propulsion (CNTP) is a type of NTP that uses liquid fissile material instead of a solid core in a standard reactor configuration. CNTP requires an interaction between liquid fissile fuel and gaseous propellant to perform heat transfer and generate thrust in a spinning enclosure. Because of the liquid state of the fissile fuel, it is essential to monitor bubble behavior and trajectory. For example, the bubble dwell time within the liquid and hydrogen flow rates can influence the liquid volume fraction and volume, which in turn can affect reactivity. A model is developed and presented that, as it matures, will predict the bubbles’ behavior based on the various types of liquid and gas and their corresponding properties as well as assist in cross-validation with the concurring experiment. The model primarily utilizes the smooth particle hydrodynamics (SPH) approach to simulate the liquid and gas interaction within the design space. The physics include buoyancy and drag on the bubbles. The pressure field within the liquid is modeled using hydrostatics, in which centrifugal motion introduces a radial gradient. Boundary conditions are devised to confine the liquid and gas within the enclosure. In this paper, we present the progress to date in two centrifugal fuel element–relevant subscale devices, the so-called “Antfarm” and “Blender II.” Antfarm is a static stage in a rectangular enclosure where buoyancy is purely gravity driven. Blender II refers to a rectangular enclosure that spins at up to 7000 rpm. Both Antfarm and Blender II are experiments that provide important data for validation against our SPH model. Two liquid and gas combinations are modeled in the present study using the Antfarm setup: water-air, and Galinstan-Nitrogen. The bubbles’ behavior was comparable to the experiment, and the velocity was at the same order of magnitude. The liquid simulation performed for the Blender II model shows that the pressure gradient within the liquid in the radial direction matches that predicted analytically from the centrifugal acceleration. The Blender II liquid model awaits experimental data for validation and verification. [ABSTRACT FROM AUTHOR]

Multiphase palladium-based nanocatalysts provide more active sites for electrocatalytic reactions due to their abundant interfacial defects, thus effectively promoting their electrocatalytic efficiency. However, the preparation and synthesis of such multiphase-structure palladium-based catalysts and the fine regulation of their compositions are still a great challenge. In this work, multiphase wavy PdSnP nanowire catalysts were obtained by doping PdSn nanocatalysts with phosphorus atoms. The nonmetallic phosphorus atom can turn the crystal phase into the amorphous phase when it enters the lattice of PdSn nanowire catalysts. Therefore, a crystalline and amorphous multiphase structure can be constructed in wavy PdSn nanowire catalysts by controlling the doping of phosphorus atoms carefully. Due to atoms with abundant interfacial defects on their surface, the multiphase wavy PdSnP nanowire catalysts showed enhanced catalytic efficiency in the electrocatalytic oxidation reactions of methanol and ethanol. In the methanol oxidation reaction, the mass and specific activities of the multiphase PdSn0.41P0.093 nanocatalyst are 4617.2 mA mgPd–1 and 20.89 mA cm–2, respectively, and in the ethanol oxidation reaction, the mass and specific activities of the multiphase PdSn0.41P0.093 nanocatalyst are 4453.1 mA mgPd–1 and 20.14 mA cm–2, respectively. This study provides a reference for the design and synthesis of high-efficiency electrocatalysts for methanol and ethanol oxidation. [ABSTRACT FROM AUTHOR]

Aircraft oil-strut shock absorbers rely on orifice designs to control fluid flow and optimize damping performance. However, the complex nature of cavitating flows poses significant challenges in predicting the influence of orifice geometry on energy dissipation and system reliability. This study presents a comprehensive computational fluid dynamics (CFD) analysis of the effects of circular, rectangular, semicircular, and cutback orifice profiles on the internal flow characteristics and damping behavior of oleo-pneumatic shock absorbers. High-fidelity simulations reveal that the rectangular orifice generates higher damping pressures and velocity magnitude than those generated by others designs, while the semicircular shape reduces cavitation inception and exhibits a more gradual pressure recovery. Furthermore, the study highlights the importance of considering both geometric and thermodynamic factors in the design and analysis of cavitating flow systems, as liquid properties and vapor pressure significantly impact bubble growth and collapse behavior. Increasing the orifice length had a negligible impact on damping but moderately raised orifice velocities. This research provides valuable insights for optimizing shock absorber performance across a range of operating conditions, ultimately enhancing vehicle safety and passenger comfort. [ABSTRACT FROM AUTHOR]

Effective flow line and piping network design depends on the accurate prediction of pressure drop in multiphase flow for horizontal and near horizontal pipes. Since early 1950, several empirical correlations and mechanistic models have been developed to predict pressure drop. All correlations used by the industry, in addition to their applicability limitations, fall short of providing the necessary precision of pressure drop predictions. However, compared to empirical correlations, the recently developed mechanistic models improved pressure drop prediction. To design and construct more dependable and economical surface piping networks and wells, it is still necessary to improve prediction accuracy. This study uses the Adaptive Neuro-Fuzzy Inference System (ANFIS) to create a model that predicts pressure drop in horizontal and near-horizontal pipelines with greater accuracy and simplicity. Using the ANFIS method, the fuzzy modelling procedure can gather knowledge about a set of data to determine the membership function parameters that will enable the associated fuzzy inference system to track input/output data most effectively. The model was created and tested using field data encompassing various variables. The model was developed using 450 different data sets that were collected from the Asian continent. 113 data sets were used for testing, and a total of 337 data sets were used for training. Trend analysis was carried out during the model development phase prior to the model’s completion. This is performed to make sure the model is stable and to make sure the created model is physically sound and accurately simulates the real physical process. To determine the percentage of error between the predicted value and the actual measured data, statistical analysis was carried out. To compare the performance of the new ANFIS model to earlier empirical correlations and mechanistic models, graphical and statistical techniques were also used. The new model outperformed known correlations and the most recent mechanistic models by a significant margin in producing incredibly accurate pressure drop predictions. The Dukler et al. empirical correlation, Beggs and Brill empirical correlation, Xiao mechanistic model, and Gomez mechanistic model had values of 25.284, 20.940, 30.122, and 20.817, respectively, while the ANFIS model had a value of 13.256 for the lowest average absolute percentage error. Additionally, the Duckler and Beggs & Brill models came in second and third, with values of 0.908 and 0.906, respectively, and the ANFIS model had the highest coefficient of determination at 0.955.

The current research aims to investigate the deposition and dispersion of nanoparticles for thermally developing laminar flow inside a cooling channel of a photovoltaic (PV) panel. The particle transport is modeled in an Eulerian-Lagrangian framework using a two-way coupling approach to perform the particle trajectories. In the absence of turbulent fluctuations, Brownian diffusion is the main force that contributes to particle deposition due to the small size of the particles used in the current study (below 100 nm). Several parameters were investigated such as inlet temperature, Reynolds number, nanoparticle size, and concentration in order to record the subsequent effects on the deposition efficiency, heat transfer coefficient, and pressure drop. There is no direct particle deposition model available in commercial computational packages such as fluent, so a deposition model was developed and programed in c-language using the user-defined function (UDF) capabilities available in the fluent solver to model how the particles are affected by wall impacts. Model validation was performed against the experimental studies found in the literature and showed good agreement. The efficiency of particle deposition on the channel wall was found to increase with decreasing nanoparticle size and/or Reynolds number. Furthermore, the deposition efficiency increased with the increase in fluid inlet temperature and nanofluid concentration. Moreover, the heat transfer rate was decreased as a result of decreasing nanofluid concentration caused by nanoparticle deposition on the channel walls, while the pumping power was also decreased due to concentration loss. [ABSTRACT FROM AUTHOR]

Microinclusions in steel will significantly affect mechanical performance of final products and therefore require serious concern during metallurgical process. Herein, the collision, coalescence as well as floatation of bubble–inclusion coexisting system is fully studied through a new mathematical model. It comes to the following conclusions: as bubbles rise, they induce a flow of liquid steel from their upper surface to their lower surface, and inclusion droplets rise and collide in the wake of the bubble. The velocity of the bubbles is affected by their deformation, with deformation rates being linked to the Weber number. The coalescence time of these inclusions is primarily influenced by viscosity and surface tension. Coalescence accelerates with higher surface tension or reduced viscosity, and this phenomenon can be described by a formula, which is developed by simulation results. According to this formula, coalescence time of 3CaO·Al2O3 is 20% longer than that of 12CaO7·Al2O3. Consequently, 12CaO7·Al2O3 is more prone to coalescence. The movement of inclusions can be controlled by adjusting gas volume and flow rate. Moreover, promoting coalescence can be achieved by altering the viscosity of inclusions and the surface tension coefficient, making it easier to remove these unwanted inclusions. [ABSTRACT FROM AUTHOR]

Copyright of e & i Elektrotechnik und Informationstechnik is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pulse width modulation in voltage source inverters with an arbitrary number of phases is analyzed in this paper. The problem is treated as purely algebraic, without any use of space vectors. Regardless of avoiding space vectors, the same results are achieved. It is shown that the problem of determining duty ratio values does not have a unique solution, and that there is one degree of freedom to choose one duty ratio, but within a limited range. Limits of the range are derived. Feasibility constraints for the required set of line voltages are derived, reducing to the requirement that the highest of the line voltages should be lower than the DC bus voltage. The analysis is illustrated in cases varying from two to five phases, and experimentally verified in the case of three phases. The method is simple and could be applied to any number of phases, even for the voltages that are not sinusoidal.

This article presents three modulation improvements for the series-capacitor buck (SCB) converter and its topological derivatives. The first consists of various phase activation sequences (PHACTSs) which raise the maximum input-to-output voltage conversion ratio of an N-inductor, N-phase SCB converter beyond the traditional limit of 1/N2, without incurring any additional voltage stress to the switches. Phase counts up to 16 are analyzed with conversion ratios increasing by a factor of up to 7. Due to the inherent link between the converter's maximum attainable output voltage and maximum output current slew rate, these PHACTSs offer a significant improvement to the load-voltage transient response. Utilizing the flying capacitors that link adjacent inductors, a second modulation technique is introduced that effectively increases the digital pulse-width-modulator's (DPWM) output-voltage resolution, by a factor of N, by employing a novel method of minimum duty increments (MDIs). Despite the commonly-held assumption of automatic steady-state inductor-current-balancing present in an N-inductor SCB, large-signal modelling reveals that slight current imbalances inevitably arise, even in lossless configurations, with three or more output inductors. After elucidating its origin, this article introduces a third modulation technique that can reduce these inductor current imbalances through a particular implementation of MDI. A discrete prototype of an 11-inductor, 48 V-to-1.0 V, 275 A-load, SCB converter was fabricated to experimentally demonstrate and validate the simulated results of the increase in both the output voltage ceiling and DPWM resolution, as well as to evaluate the MDI-DPWM output-voltage linearity. Finally, the maintenance of both inductor current balancing and low switch-voltage-stress is experimentally substantiated when using MDI.

This research project was focused on understanding the production and response to heat treatment for a Fe8Mn2Al2Si0.3C steel alloy. These alloys can be heat treated to produce multiphase microstructures containing ferrite, austenite, martensite, and/or iron carbide. A previous project examined "high" carbon contents (0.5 wt% and 0.75 wt%), where the microstructure consisted primarily of stabilized austenite and heat treatment could produce austenite plus ferrite dual-phase microstructures that had higher hardness and, presumably, higher tensile strength (Druschitz in Inter Metalcast, 2023. https://doi.org/10.1007/s40962-023-01000-1). In this study, we examined a "low" carbon content (0.3 wt%), where the microstructure was primarily martensite and heat treatment could produce martensite plus ferrite and/or austenite. Therefore, this lower carbon content Fe8Mn2Al2Si0.3C steel had higher hardness (and presumably greater strength) compared to the higher carbon content steels. [ABSTRACT FROM AUTHOR]

Polypropylene-based multiphase compositions with a disperse elastomer phase provide superior impact strength. Making this property indifferent to processing steps requires stabilization of the morphology of these materials. Various approaches have been tested over time, each of which shows limitations in terms of performance or applicability. Using polyethylene (PE) homo- and copolymers capable of silane-based crosslinking as modifiers was explored in the present study, which allows decoupling of the mixing and crosslinking processes. Commercial silane-copolymerized low-density PE (LD-PEX) from a high-pressure process and silane-grafted high-density PE (HD-PEX) were studied as impact modifiers for different types of PP copolymers, including non-modified reference PE grades, LDPE and HDPE. Blends based on ethylene–propylene random copolymers (PPR) and based on impact- (PPI) and random-impact (PPRI) copolymers show improvements of the stiffness–impact balance; however, to different degrees. While the absolute softest and most ductile compositions are achieved with the already soft PPRI copolymer base, the strongest relative effects are found for the PPR based blends. Modifiers with lower density are clearly superior in the toughening effect, with the LD-PEX including acrylate as second comonomer sticking out due to its glass transition around −40 °C. The impact strength improvement found in most compositions (except at very high content) results, however, not from the expected phase stabilization. For comparable systems, particle sizes are normally higher with crosslinking, probably because the process already starts during mixing. Thermoplastic processability could be retained in all cases, but the drop in melt flow rate limits the practical applicability of such systems. [ABSTRACT FROM AUTHOR]

Diffraction elastic constants (DECs) describe the elastic response of a subset of orientation‐correlated grains which share a common lattice vector. DECs reflect the elastic behaviour of the single‐crystal constituents through their dependence on grain orientation. DECs furthermore depend on the behaviour of the polycrystal aggregate both through the dependence on preferred orientation and through the average elastic interaction of the grains in the subset with their surroundings. The latter is also known as grain–matrix interaction which is grain‐shape dependent. Both dependencies can make the DECs uniquely sensitive to the elastic effects of the grain shape, texture and phase composition. Several micro‐mechanical models are explored for use in calculating both DECs and overall elastic constants. Furthermore, it is shown how discrete data from electron backscatter diffraction on grain shape, grain orientations and neighbouring grains can be used for DEC calculations. Lastly, the inverse problem of calculating single‐crystal elastic constants from DECs is discussed in detail. All calculations discussed in this work can be verified using the freely available computer program IsoDEC. [ABSTRACT FROM AUTHOR]

In this study, the effects of Cu addition on AlFeMnTiSi0.75Cux (x = 0, 0.25, 0.5, 0.75, 1.00; in molar ratios) high entropy alloys (HEAs) prepared via mechanical alloying and spark plasma sintering were investigated. The structure, phase, morphology and composition of HEA powders were analysed and the results revealed that the AlFeMnTiSi0.75Cux HEAs exhibited a multiphase structure. Additionally, after sintering at 900 °C, the formation of BCC, µ and L21 phases in the densified HEAs was enhanced. The investigation of the hardness, nanoindentation and compressive properties revealed that the microstructural and mechanical properties of AlFeMnTiSi0.75Cux HEAs were improved at the optimal Cu fraction (0.25 molar ratio). The nanoindentation results revealed that the AlFeMnTiSi0.75Cux HEAs exhibited the highest hardness and elastic modulus (HIT = 19.2 GPa, EIT = 336 GPa). These results improve the current understanding of multiphase HEAs and may pave way for the development of advanced HEAs with superior mechanical properties. [ABSTRACT FROM AUTHOR]

This research work demonstrates the optimization of effective process parameters by response surface methodology (RSM) and experimental validation of M-type/multiphase catalytic pyrolysis of equally mixed waste expanded polystyrene and waste high-density polyethylene. The M-type/multiphase catalytic pyrolysis process of mixed feed was performed over ZSM-5 ammonium powder as catalyst (surface area = 400 m2/g, SiO2/Al2O3 = 200–400:1, Alfa Asear, USA) in a semi-batch reactor for the production of valuable target aromatic hydrocarbons benzene, toluene and ethylbenzene (BTE). The RSM predicted that maximum liquid yield of 73.86 wt. % was obtained at the optimum temperature of 553.28 °C, heating rate of 14.94 °C/min and feed-to-catalyst ratio of 22.48:1, whereas the actual maximum liquid yield of 73.72 wt.% was obtained using the optimized process parameters predicted by RSM. The negligible deviation of only 0.19% was found between actual/experimental liquid yield (73.72 wt.%) and predicted liquid yield (73.86 wt.%). The pyrolysis oil was obtained at the optimum condition having total BTE content of 31.83 wt.% and styrene content of 51.99 wt.%. The Fischer test value (< 0.0001) and probability value (1768.37) obtained by the analysis of variance indicate that the model is significant. The fuel oil obtained at the optimum a condition comes up with very high gross calorific value of 12,889 Cal/g, which indicates the presence of low molecular weight valuable hydrocarbons in the oil. [ABSTRACT FROM AUTHOR]

DC–DC converters are among the main components of DC power systems based on renewable energy sources. In some applications, interleaved multi-phase converters are employed to reduce the converter input current and output voltage ripples and increase reliability. On the other hand, modular converters are also employed in some applications mainly to increase the system power range, reliability, and reconfigurability. Developing effective methods for controlling and monitoring the modular multi-phase converters plays an important role in the power system's performance and efficiency. In this paper, a new effective Lyapunov-based control method is proposed for the modular multi-phased DC–DC boost converters. The modular converter includes two main multi-phase modules and one reserved module which substitutes the main modules in the fault conditions. The proposed control method is superior to the conventional proportional-integral controller in terms of the response speed and converter's current and voltage transient variations. Also, the proposed controller reduces the number of integrators which leads to the simplified implementation. The validity of the proposed method is confirmed by simulation and experimental results. [ABSTRACT FROM AUTHOR]

Aortic dissection (AD) has a high mortality rate. About 40% of the people with type B AD do not live for more than a month. The prognosis of AD is quite challenging. Hence, we present a triphasic model for the formation and growth of thrombi using the theory of porous media (TPM). The whole aggregate is divided into solid, liquid and nutrient constituents. The constituents are assumed to be materially incompressible and isothermal, and the whole aggregate is assumed to be fully saturated. Darcy's law describes the flow of fluid in the porous media. The regions with thrombi formation are determined using the solid volume fraction. The velocity- and nutrient concentration-induced mass exchange is defined between the nutrient and solid phases. We introduce the set of equations and a numerical example for thrombosis in type B AD. Here we study the effects of different material parameters and boundary conditions. We choose the values that give meaningful results and present the model's features in agreement with the Virchow triad. The simulations show that the thrombus grows in the low-velocity regions of the blood. We use a realistic 2-d geometry of the false lumen and present the model's usefulness in actual cases. The proposed model provides a reasonable approach for the numerical simulation of thrombosis. [ABSTRACT FROM AUTHOR]

We present an hp-adaptive discretization for a sharp interface model with a level-set ghost-fluid method to simulate compressible multiphase flows. The scheme applies an efficient p-adaptive discontinuous Galerkin (DG) operator in regions of smooth flow. Shocks and the phase interface are captured by a Finite Volume (FV) scheme on a h-refined element-local sub-grid. The resulting hp-adaptive scheme thus combines both the high order accuracy of the DG method and the robustness of the FV scheme by using p-adaptation in smooth areas and h-refinement at discontinuities, respectively. For the level-set based interface tracking, a similar hybrid DG/FV operator is employed. Both p-refinement and FV shock and interface capturing are performed at runtime and controlled by an indicator, which is based on the modal decay of the solution polynomials. In parallel simulations, the hp-adaptive discretization together with the costly interface tracking algorithm cause a significant imbalance in the processor workloads. To ensure parallel efficiency, we propose a dynamic load balancing scheme that determines the workload distribution by element-local wall time measurements and redistributes elements along a space filling curve. The parallelization strategy is supported by strong scaling tests using up to 8192 cores. The framework is applied to established benchmarks problems for inviscid, compressible multiphase flows. The results demonstrate that the hybrid adaptive discretization can efficiently and accurately handle complex multiphase flow problems involving pronounced interface deformations and merging interface contours. [ABSTRACT FROM AUTHOR]

In this study, multiphase Eulerian computational fluid dynamics (CFD) modelling is developed to predict the hydrodynamics, mass transfer, and chemical absorption of CO2 using a monoethanolamine (MEA) solution in a structured packed column. First, the hydrodynamic simulation of liquid dispersion in a structured packed bed using a two‐dimensional CFD is performed. The simulation results of the radial distribution of the liquid holdup are compared with the literature experimental data. The model prediction matches the experimental data at the top position of the column, whereas a slight deviation is found at the bottom position of the column. Using a validated CFD model, the reactive mass transfer is modelled to study CO2 capture in a structured packed column with Mellapak 500.X. The model results are compared to the literature experimental results of CO2 mole fractions along the height of the column. It is found that the model results match the experimental findings. Furthermore, CFD modelling is extended to investigate the influence of operating conditions such as gas and liquid velocities on CO2 removal efficiency. The present CFD model demonstrates the porous media approach for reactive absorption of CO2 in a structural packed bed. [ABSTRACT FROM AUTHOR]

The magnesium salt Mg(NO3)2·2H2O from laterite nickel ore nitric acid leaching process can be reused by thermal decomposition using calciner. To improve the performance of the calciner, a new numerical model integrating the gas-particle hydrodynamics and the particle pyrolysis reaction was established by Euler-Lagrange approach. In particular, the particle size variation caused by pyrolysis reaction was considered to accurately describe the gas-particle hydrodynamics. The particle pyrolysis model was developed to realize the interphase mass transfer. The P-1 model was modified to realize interphase radiation heat transfer. Then, the influence of different parameters on the thermal decomposition processes was discussed by using the established model. Finally, the optimal conditions for Mg(NO3)2·2H2O thermal decomposition were determined via response surface optimization analysis. The results show that the thermal decomposition of Mg(NO3)2·2H2O can be improved by increasing the initial hot gas temperature, reaction zone height, and decreasing treatment capacity of Mg(NO3)2·2H2O. The degree of influence of each parameter on thermal decomposition follows the order of initial hot gas temperature > treatment capacity of Mg(NO3)2·2H2O > reaction zone height. The decomposition rate of 99.99 % is obtained at optimized conditions of initial hot gas temperature 1111 K, Mg(NO3)2·2H2O treatment capacity 251 kg/h and reaction zone height 9 m.

Abstract In this study, the low temperature creep properties of multiphase bituminous materials (binder, mastic, Fine Aggregate Matrix—FAM, and mixture) were experimentally evaluated, and the impact of size effect on FAM and mixture specimen was also assessed. First, the mix design of mastic and FAM was performed based on the reference mixture Asphalt Concrete (AC) 22 TS. The mathematical adaptation to the boundary sieve method was applied to calculate FAM gradation and binder content. Next, a preparation method was proposed to produce Fine Aggregate Matrix (FAM) in a laboratory environment, and scale-up slab samples were also fabricated for FAM and mixture specimens to evaluate the size effect phenomenon. Finally, three-point bending (3 PB) creep tests were conducted on the multiphase bituminous specimens with different dimensions at -6 °C, -12 °C, and -18 °C with a modified Bending Beam Rheometer (BBR) device and a dynamic loading machine, depending on the sample size. Results indicate that the creep stiffness of the FAM was close to mixtures and much higher than the one observed in binder and mastic. The proposed fabrication approach provides a satisfactory method for preparing a representative FAM phase in the mixture, while the air voids can be easily adjusted during the slab compaction procedure. This study supports the idea of using FAM to discriminate asphalt mixtures for cold regions. The correlation between up-scaled FAM and mixture specimens should be further investigated, including different mixture types and corresponding FAM.

MFIX-Exa is a computational fluid dynamics–discrete element model (CFD-DEM) code designed to run efficiently on current and next-generation supercomputing architectures. MFIX-Exa combines the CFD-DEM expertise embodied in the MFIX code—which was developed at NETL and is used widely in academia and industry—with the modern software framework, AMReX, developed at LBNL. The fundamental physics models follow those of the original MFIX, but the combination of new algorithmic approaches and a new software infrastructure will enable MFIX-Exa to leverage future exascale machines to optimize the modeling and design of multiphase chemical reactors.

Aircraft oil-strut shock absorbers rely on orifice designs to control fluid flow and optimize damping performance. However, the complex nature of cavitating flows poses significant challenges in predicting the influence of orifice geometry on energy dissipation and system reliability. This study presents a comprehensive computational fluid dynamics (CFD) analysis of the effects of circular, rectangular, semicircular, and cutback orifice profiles on the internal flow characteristics and damping behavior of oleo-pneumatic shock absorbers. High-fidelity simulations reveal that the rectangular orifice generates higher damping pressures and velocity magnitude than those generated by others designs, while the semicircular shape reduces cavitation inception and exhibits a more gradual pressure recovery. Furthermore, the study highlights the importance of considering both geometric and thermodynamic factors in the design and analysis of cavitating flow systems, as liquid properties and vapor pressure significantly impact bubble growth and collapse behavior. Increasing the orifice length had a negligible impact on damping but moderately raised orifice velocities. This research provides valuable insights for optimizing shock absorber performance across a range of operating conditions, ultimately enhancing vehicle safety and passenger comfort.

In this study, the low temperature creep properties of multiphase bituminous materials (binder, mastic, Fine Aggregate Matrix—FAM, and mixture) were experimentally evaluated, and the impact of size effect on FAM and mixture specimen was also assessed. First, the mix design of mastic and FAM was performed based on the reference mixture Asphalt Concrete (AC) 22 TS. The mathematical adaptation to the boundary sieve method was applied to calculate FAM gradation and binder content. Next, a preparation method was proposed to produce Fine Aggregate Matrix (FAM) in a laboratory environment, and scale-up slab samples were also fabricated for FAM and mixture specimens to evaluate the size effect phenomenon. Finally, three-point bending (3 PB) creep tests were conducted on the multiphase bituminous specimens with different dimensions at -6 °C, -12 °C, and -18 °C with a modified Bending Beam Rheometer (BBR) device and a dynamic loading machine, depending on the sample size. Results indicate that the creep stiffness of the FAM was close to mixtures and much higher than the one observed in binder and mastic. The proposed fabrication approach provides a satisfactory method for preparing a representative FAM phase in the mixture, while the air voids can be easily adjusted during the slab compaction procedure. This study supports the idea of using FAM to discriminate asphalt mixtures for cold regions. The correlation between up-scaled FAM and mixture specimens should be further investigated, including different mixture types and corresponding FAM. [ABSTRACT FROM AUTHOR]

In single phase flows, benchmarks like the lid driven cavity have become recognized as fundamental tests for newly developed computational fluid dynamics, CFD, codes. For multiphase free surface flows with variable surface tension, the presently studied pool with isothermal sidewalls is suggested as it is the simplest domain where Marangoni effects can dominate. It was also chosen due to its strange sensitivity to the initial setup which is discussed at length from a chosen number of 'scenarios'. It was found that the fluid interface can reverse deformation by a change in the top boundary condition, the liquid equation of state, and the gravity level. For the top boundary condition, this reversal is due to vapor expansion within the closed volume, creating an additional convection mechanism. Not only does the interface reverse, but the peak height changes by more than an order of magnitude at the same Marangoni number. When including gravity, the peak velocity can increase significantly, but it can also cause a decrease when done in combination with a change in the top wall boundary condition. Finally, thermal expansion of the liquid phase causes the peak velocity to be reduced, with additional reductions from the gravity and top wall condition. The differences in each scenario could lead to significant errors in analyzing a practical application of Marangoni flows. Therefore, it is important to demonstrate that a new CFD code can not only resolve Marangoni convection, but also has the capability to resolve the scenario most relevant to the application at hand. [ABSTRACT FROM AUTHOR]

Accurate differentiation between the intracranial and extracranial location of the acute internal carotid artery (ICA) occlusion is essential for guiding treatment decisions and mechanical thrombectomy planning. Multiphase Computed Tomography angiography (mCTA) appears to be superior to Single-phase Computed Tomography angiography (sCTA) in the evaluation of acute ICA occlusions. The main objective of our research is to study the accuracy of mCTA compared to sCTA in distinguishing isolated acute intracranial ICA occlusion from extracranial or tandem occlusion. Two observers independently analyzed sCTA and mCTA of patients with acute ICA occlusion at two different time points. The location of the occlusion was categorized as intracranial or extracranial for both imaging techniques and then compared with digital subtraction angiography (gold standard). Sensitivity and specificity rates for isolated intracranial ICA occlusion on sCTA and mCTA were calculated. Kappa statistics were used to assess interobserver agreement. The sensitivity of sCTA and mCTA was 48.28% (28.36%–68.19%) and 79.31% (62.84%–95.78%) respectively for the diagnosis of isolated intracranial ICA occlusion, with an almost perfect interobserver agreement between both observers (p < 0.001). Our research suggests that mCTA is more accurate than sCTA in distinguishing isolated intracranial occlusions from extracranial or tandem occlusions. • Differentiating between isolated intracranial from tandem occlusion is essential for procedure planning. • Intracranial ICA occlusion can mimic an extracranial affectation on single CTA. • Multiphase CTA is superior to single CTA in detecting isolated intracranial ICA occlusion. [ABSTRACT FROM AUTHOR]

Manganese-co-doped N:CdS composite nanoparticles (CNps) have been prepared by using the co-precipitation method. 2-Mercaptoethonal is used as a surfactant to control the size of nanoparticles. X-ray diffraction (XRD) studies confirm the size of the particles in the nanorange. The Rietveld refinement with X'-pert high-score software studies show multiphase existence in as-prepared composite nanoparticles. The energy dispersive analyses of X-ray studies (EDAX) confirm the presence of doped Mn and nitrogen elements in CdS. The Fourier transform infrared spectroscopy (FTIR) studies confirm the presence of surfactant. The ultraviolet-visible spectroscopy studies (UV-Vis) show a clear blue shift in the band gap, which is an indication of the quantum confinement effect. The photoluminescence studies (PL) attribute the emission of a characteristically strong peak at l = 632 nm, corresponding to the (4T16A1) transition, to the inclusion of Mn2+ in the core of the CdS lattice. The electron paramagnetic spectroscopy (EPR) studies show paramagnetic behavior. The hyperfine splitting constant (A) values around 7 mT from EPR confirms the inclusion of Mn2+ and N3- in the tetrahedral sites of the CdS core. The variation in optical and magnetic properties of as-prepared composite nanoparticles has the potential for optoelectric and magnetoluminescence devices. [ABSTRACT FROM AUTHOR]