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Bubble multiphase systems are crucial in industries such as biotechnology, medicine, oil and gas, and water treatment. Optical data analysis provides critical insights into bubble characteristics, such as the shape and size, complementing physical sensor data. Existing detection techniques rely on classical computer vision algorithms and neural network models. While neural networks achieve a higher accuracy, they require extensive annotated datasets, and classical methods often struggle with complex systems due to their lower accuracy. This study proposes a novel framework to address these limitations. Using Superformula parameter regression, we introduce an advanced border detection method for accurately identifying gas inclusions and complex-shaped objects in multiphase environments. The framework also includes a new approach for generating realistic artificial bubble images based on physical flow conditions, leveraging the Superformula to create extensive, labeled datasets without manual annotation. Tested on real bubble flows in mass transfer equipment, the algorithms enable bubble classification by shape and size, enhance detection accuracy, and reduce development time for neural network solutions. This work provides a robust method for object detection and dataset generation in multiphase systems, paving the way for more precise modeling and analysis. [ABSTRACT FROM AUTHOR]

This research quantified the temporal mesostructural evolution of bitumen emulsion–cement composites using the time-lapse high-energy X-ray tomography of a fine-aggregate matrix. The image post-processing and analysis showed that the mastic's significant temporal decrease in volume complemented the expansion of the pore space. Nevertheless, the volume fractions determined by the image analysis essentially differed from the physical composition of specimens and were several times less sensitive to curing. Because of the extremely heterogenous microstructure and the abundance of calcium, the mastic phase had the highest attenuation of X-rays, but the attenuations of bitumen- and cement-dominated systems experienced contrary temporal trends. The sand and pore space had typically smooth and oppositely evolving axial distributions with the highest-density plateau in the middle, while the mastic was distributed uniformly. The radial distributions evolved less irregularly and notably interfered with the post-processing of beam hardening. The temporal increase in the pore space's local thicknesses was extremely unevenly distributed across diameters. Except the sand particle size distributions, all results were almost excellently repeatable. Finally, the interaction with X-rays was identified as crucial for the interpretation and validity of the results. Moreover, although water could not be segmented using the conventional X-ray tomography, its discrete signature was present throughout the behaviour of other phases. [ABSTRACT FROM AUTHOR]

An innovative method for bubble detection and characterization in multiphase flows using advanced computer vision and neural network algorithms is introduced. Building on the research group's previous findings, this study combines high-speed video capture with advanced deep learning techniques to enhance bubble detection accuracy and dynamic analysis. In order to further develop a robust framework for detecting and analyzing bubble properties in multiphase flows, enabling accurate estimation of essential mass transfer parameters, a YOLOv9-based neural network was implemented for bubble segmentation and trajectory analysis, achieving high accuracy. Key contributions include the development of an averaged mass transfer model integrating experimental data, neural network outputs, and scaling algorithms, as well as validation of the proposed methodology through experimental studies, including high-speed video imaging and comparisons with mass transfer coefficients obtained via the sulfite method. By precisely characterizing critical parameters, the algorithm enables accurate gas transfer rate calculations, ensuring optimal conditions in various industrial applications. The neural network-based algorithm serves as a non-invasive platform for detailed characterization of bubble media, demonstrating high accuracy in experimental validation and significantly outperforming traditional techniques. This approach provides a robust tool for real-time monitoring and modeling of bubble flows, laying the foundation for novel, non-invasive methods to measure multiphase media properties. [ABSTRACT FROM AUTHOR]

This paper studies multiphase electrical systems based on the properties of their number of phases. Depending on its parity, the latter can be even or odd. Its factorization provides numerous ways to represent the phase number. Thus, this paper presents the possibilities of modifications together with the properties that arise from the factorizations of the number of phases. Furthermore, we present the formulation of symmetrical components for both even and odd numbers of phases.

The deformation of multiphase metallic alloys or metal matrix composites by forming processes such as rolling or drawing requires the co‐deformation of phases. Severe plastic deformation processes have extended possibilities with the ability to produce unique nanoscaled structures through the formation of strain‐induced super‐saturated solid solutions, the fragmentation of second‐phase particles, or ultimate co‐deformation down to the nanoscale. Based on various examples, the fundamental mechanisms of co‐deformation are addressed. Parameters that promote the extension of existing heterophase boundaries are discussed, and some possible atomic‐scale mechanisms involving dislocation activities based on geometrical and energetic considerations are proposed. Finally, the physical limits of co‐deformation are considered before suggesting research directions that might be followed to develop fundamental knowledge and applications in the field. [ABSTRACT FROM AUTHOR]

Particle aggregation is essential in many industrial processes, spanning the pharmaceutical and food industries, polymer production, and the environment, among others. However, aggregation can also occur, in some processes, as a non-desired side effect. Thus, to be able to monitor aggregation in industrial processes is of high importance to guarantee that the final, required product characteristics are obtained. In this paper, we present an extensive review of the different techniques available for monitoring particle characteristics in industrial processes involving particulate materials, with special emphasis on aggregation processes. These methods include both off-line and on-line techniques, based either on image acquisition techniques or different radiation scattering techniques (light-scattering and ultrasound spectroscopy). The principles behind each technique are addressed, together with their relevant applications, advantages, and disadvantages.

Particle aggregation is essential in many industrial processes, spanning the pharmaceutical and food industries, polymer production, and the environment, among others. However, aggregation can also occur, in some processes, as a non-desired side effect. Thus, to be able to monitor aggregation in industrial processes is of high importance to guarantee that the final, required product characteristics are obtained. In this paper, we present an extensive review of the different techniques available for monitoring particle characteristics in industrial processes involving particulate materials, with special emphasis on aggregation processes. These methods include both off-line and on-line techniques, based either on image acquisition techniques or different radiation scattering techniques (light-scattering and ultrasound spectroscopy). The principles behind each technique are addressed, together with their relevant applications, advantages, and disadvantages. [ABSTRACT FROM AUTHOR]

Modern electric vehicles require power electronic systems capable of operating under a wide variety of operating conditions, including on-board chargers (OBCs) and dc–dc converters. These systems must function across a wide range of parameters, such as phase number, input voltage, and output battery voltage. Considering modern design standards, achieving a high-performance implementation featuring high efficiency and low cost is also mandatory, adding additional technical challenges. To address these challenges, this article proposes a novel OBC architecture designed to operate in both three-phase and single-phase configurations across the full output power range. This is achieved without requiring additional power components or degrading performance. As a consequence, the proposed solution is a universal-charging single-power-processing block that features a cost-effective implementation while achieving high power density and efficiency. In this article, a bidirectional 11-kW 800-V-battery-voltage prototype of the system is designed and constructed for a 400-V (line-to-line) mains supply.

The problems of constructing a multiphase model of the phase field for the processes of phase transitions of the first kind are considered. Based on the Gibbs energy of the complete system expressed in terms of antisymmetrized combinations of phase fields, it is shown that the equations of dissipative dynamics of a locally nonequilibrium system follow from the condition of its monotonic decrease, preserving the normalization of the sum of variables by one and the following properties of the previously known two-phase model. [ABSTRACT FROM AUTHOR]

This paper proposes a new and straightforward method to extend the modulation range of the six-phase cascaded current source inverter (CSI). The proposed technique employs vector space decomposition (VSD) to mitigate the inverter current harmonics and extend the linear modulation region by about 8%. For motor drive applications, increasing the fundamental output component can reflect higher torque production capability for the same drive size, given that thermal limits are not exceeded. The extension can be realized by injecting optimized xy harmonics while keeping the amplitude of the resulting phase currents under the maximum value. The method utilizes a look-up table of optimized values of the injected harmonics to extend the modulation range. The output filter capacitor effects are also studied in this paper, and a selection approach is introduced. Finally, the experimental results of a C-CSI laboratory prototype are presented and discussed to verify the feasibility of the proposed modulation technique.

Due to the density differences between gases and liquids, the gas supply often limits the conversion of gas‐liquid reactions in slug flows. This paper investigates the permeation of reacting gas into an existing gas‐liquid slug flow in fluorinated ethylene propylene capillaries of up to 40 m in length, representing a significant sizing‐up of tube‐in‐tube reactors (maximum 4 m). The amount of gas introduced can be estimated with permeation coefficients given in the literature. Moreover, existing gas bubbles serve as reservoirs for the permeating gas, maintaining the advantageous slug flow pattern. [ABSTRACT FROM AUTHOR]

Extrusion printing represents one of the leading additive manufacturing techniques for tissue engineering purposes due to the possibility of achieving accurate control of the final shape and porosity of the scaffold. Despite many polymeric materials having already been optimized for this application, the processing of biopolymer‐based systems still presents several limitations mainly ascribed to their poor rheological properties. Moreover, the introduction of inorganic components into the biomaterial formulation may introduce further difficulties related to system homogeneity, finally compromising its extrudability. In this context, the present study aimed at developing a new multi‐phase biomaterial ink able to mimic the native composition of bone extracellular matrix, combining type‐I‐collagen with nano‐hydroxyapatite and mesoporous bioactive glass nanoparticles. Starting from a comprehensive rheological assessment, computational‐fluid‐dynamics‐based models were exploited to describe the material flow regime and define the optimal printing process planning. During printing, a gelatin‐based bath was exploited to support the deposition of the material, while the gelation of collagen and its further chemical crosslinking with genipin enabled the stabilization of the printed structure, characterized by high shape fidelity. The developed strategy enables the extrusion printing of complex multi‐phase systems and the design of high‐precision biomimetic scaffolds with great potential for bone tissue engineering. [ABSTRACT FROM AUTHOR]

Due to their many advantages over their counterparts, such as Z-source inverters (ZSIs), split-source inverters (SSIs) have recently received much attention as single-stage boost inverters. This paper discusses a multiphase version of the SSI topology for the first time. Among multiphase systems undergoing a revolution in the research area, five-phase motor drives are a relatively practical selection in industrial applications. Therefore, this paper focuses on a five-phase SSI as an example. The topology, operating principles, modulation techniques, and performance analysis of the analyzed topology are introduced. A modified space-vector modulation (MSVM) scheme is developed to eliminate low-frequency ripples in the input current. There is also a detailed analysis and graphical evaluation of the output currents ripples using the space-vector approach. It is evident that multiphase SSI is suitable for motor drives, especially when a high-output voltage gain is required. In addition to having a nearly identical ripple in output current to a conventional VSI, it has the benefit of performing the boosting action in a single stage with fewer passive components and a low ripple in input current. Finally, the simulation and experimental results have been conducted to demonstrate the viability of the multiphase SSI studied in the theoretical study and analysis. [ABSTRACT FROM AUTHOR]

The oxidation of representative bio-based benzyl-type alcohols has been successfully carried out in a multiphase (MP) system comprised of three mutually immiscible liquid components as water, isooctane, and a hydrophobic ionic liquid as methyltrioctylammonium chloride ([CH 3 (CH 2 ) 6 CH 2 ] 3 N(Cl)CH 3 ), a heterogeneous catalyst (either ad-hoc synthesized carbon-supported Mo or a commercial 5 % Ru/C), and air as an oxidant. The MP-reaction proceeded as an interfacial process with Mo/C or Ru/C perfectly segregated in the ionic liquid phase and the reactant(s)/products(s) dissolved in the aqueous solution. This environment proved excellent to convert quantitatively benzyl alcohols into the corresponding aldehydes with a selectivity up to 99 %, without overoxidation to carboxylic acids. The nature of the catalyst, however, affected the operating conditions with Ru/C active at a lower T and t (130 °C, 4-6 h) compared to Mo/C (150 °C, 24 h). The phase confinement was advantageous also to facilitate the products isolation and the recycle of the catalyst. Notably, in the Mo/C-catalyzed oxidation of benzyl alcohol, benzaldehyde was achieved with unaltered selectivity (>99 %) at complete conversion, for five subsequent reactions through a semicontinuous procedure in which the catalyst was reused in-situ, without ever removing it from the reactor or treating it in any way., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

In this paper, space vector modulation (SVM) techniques are developed to operate the six-phase current-source inverters (CSI) while reducing the common-mode voltage (CMV) content associated with the switching of semiconductors. The CMV issue is a severe issue of high-power electronics converters that causes damage to electric drives and shortens their life span. Since the null states are the main contributor to CMV in SVM schemes, an optimum offline selection method is proposed in this paper for all the presented techniques. The SVM techniques discussed in this proposal are built on the renowned vector space decomposition (VSD) method. The modulation in all the techniques is based on studying the resultant CMV associated with all the possible switching states and then selecting the states that produce the lowest magnitude of CMV. Accordingly, the optimum sequences for the switching patterns are introduced, and the utilization of the dc-link current for each scheme is analyzed. A quantitative comparison is conducted to evaluate all the proposed schemes in the generated CMV in peak and RMS values versus the modulation index and load power factor range. A laboratory prototype is presented, and the experimental results to validate the proposals are illustrated with a detailed discussion.

In this paper, new powertrain configurations for heavy-duty electric vehicles (HDEV) are proposed based on current-source inverters (CSI) and asymmetrical six-phase motors. Voltage-source inverters (VSI) are widespread in many applications; however, VSI-based powertrains require a bulky bank of capacitors with a limited lifetime. Recently, powertrains based on the current-source inverter (CSI) are getting more attention to be a more reliable structure for EVs by replacing the dc-link capacitor with a choke inductor. To the authors’ best knowledge, a six-phase CSI-based powertrain is not fully addressed yet. Since the six-phase CSI comprises two three-phase CSIs, multiple configurations can arise based on the connection between the two CSIs. In this context, the proposed powertrain configurations are based on parallel, cascaded, and standalone six-phase CSIs. The standalone topology is based on separating the two three-phase converters by supplying each converter with a dedicated dc-dc converter. All the proposed configurations are studied from the perspective of structure, modulation, and stresses/sizing. A case study highlights the differences and compares the three structures. The comparison is backed by experimental results, and a detailed discussion is provided for concluding a suggested selection of the best-suited topology.

Three different multiphase systems (MP 1–3) comprised of two immiscible liquids, with or without an ionic liquid (IL: methyltrioctyl ammonium chloride), were investigated for the oxidation of 5‐hydroxymethyl‐furfural (HMF) over 5 % Ru/C as a catalyst and air (8 bar) as an oxidant. These conditions proved versatile for an excellent control of the reaction selectivity to 4 distinct products derived from full or partial oxidation of the carbonyl and alcohol functions of HMF, and each one achieved in 87–96 % isolated yield at complete conversion. MP1 based on water and isooctane, yielded 2,5‐furandicarboxylic acid (FDCA, 91 % yield). In MP2, obtained by adding the IL to MP1, the oxidation proceeded towards the formation of 5‐formyl‐2‐furancarboxylic acid (FFCA, 87–89 % yield). MP2 also proved successful in the design of a one pot–two step oxidation/reduction sequence to prepare 5‐hydroxymethyl‐2‐furancarboxylic acid (HMFCA, 85 % yield). In MP3, the use of an acetonitrile/cyclooctane biphase yielded 2,5‐diformylfuran (DFF, 96 % yield). All the multiphase systems MP 1–3 allowed a perfect segregation of the catalyst in a single phase (either the hydrocarbon or the IL) distinct from the one containing HMF and its oxidation products. This was crucial not only for the catalyst/product separation but also for the recycle of Ru/C that was possible under all the tested conditions. Accordingly, MP‐reaction were run in a semicontinuous mode without removing the catalyst from the reactor nor resorting to conventional separation and activation techniques. Negligible Ru leaching, less than 0.96 ppb, was measured in all cases. [ABSTRACT FROM AUTHOR]

[Display omitted] • Use of Volume of Fluid (VOF) method to model free surface dynamics in UUSTs. • Comprehensive assessment of suitable turbulence models for unbaffled stirred tank analysis. • Study of effects of impeller speed on vortex shape and aeration at different viscosities. • Prediction of Power Number (Np) and vortex shape in non-aerated and aerated conditions. • Prediction of cavities near the impeller blades in super-critical regime. The transition between non-aerated and aerated regimes in uncovered unbaffled stirred tanks (UUSTs) was investigated using computational fluid dynamics (CFD). The Volume of Fluid (VOF) method was employed to model the free surface dynamics under various operational conditions. The simulations were able to predict the peculiar experimentally observed behavior of UUSTs and revealed that at velocities below a critical threshold (N_ < _N crit) , the system remains non-aerated, while exceeding this threshold (N_ ≥ _N crit) induces bubble ingestion, leading to significant changes in power consumption and flow patterns. The CFD simulations accurately predicted the behaviour of the Power Number (Np) as well as the vortex shape inside the tank both in subcritical and supercritical regimes and showed good agreement with original experimental data and correlations from the literature. Additionally, the modeling of the aerated regime successfully predicted the vortex shape, the bubble dispersion within the tank, and the cavities formed behind the blades. [ABSTRACT FROM AUTHOR]

This manuscript discusses the structure of the errors in the solution of elliptic problems introduced by the regularization of the fluid properties discontinuity in a small region of finite size. By using a multiscale approach, the problem of the error calculation is splitted into an outer problem, where the regularization region is replaced by a sharp interface, and an inner local one dimensional problem that eventually imposes effective jump conditions across the interface for the outer problem. Except in some particular cases, the use of regularization techniques introduces first order errors in the solution imposing an error flux jump that is proportional to the tangential Laplacian of the averaged solution and an error jump that is proportional to the normal flux, both multiplied by a prefactor that depends on the averaging rule used. In general, the optimal averaging procedure is shown to depend on the structure of the problem at hand. The errors introduced by standard arithmetic and harmonic averages are obtained for various analytical and numerical examples which are used to discuss the nature of the errors introduced and the importance of first order errors in the solution. The influence of the ratio between the regularization thickness and the grid size is also investigated in numerical implementations of the one-fluid model. • *Error estimation analysis of regularization errors in multiphase flow elliptic problems. • Derivation of a first order model for the estimation of regularization errors. • Analysis of the structure of regularization errors using analytical examples. • Discussion of exact regularization errors in the solution of Laplace/Poisson problems. [ABSTRACT FROM AUTHOR]

The hydrogenation/hydrogenolysis of 5‐hydroxymethylfurfural (HMF) has been carried out either under single (aqueous) phase or batch multiphase (MP) conditions using mutually immiscible aqueous/hydrocarbon phases, 5 % Ru/C as a catalyst, and both with and without the use of trioctylmethyl phosphonium bis‐(trifluoro methane) sulfonimide ([P8881][NTf2]) as an ionic liquid (IL). Alternatively, the hydrogenation of HMF was explored in the continuous‐flow (CF) mode with the same catalyst. By changing reaction parameters, experiments were optimized towards the formation of three products: 2,5‐bis(hydroxy methyl)furan (BHMF), 2,5‐bis(hydroxymethyl)tetrahydrofuran (BHMTHF), and 1‐hydroxyhexane‐2,5‐dione (HHD), which were obtained in up to 92, 90, and 99 % selectivity, respectively, at quantitative conversion. In particular, the single (aqueous) phase reaction of HMF (0.2 m) carried out for 18 h at 60 °C under 30 bar of H2, allowed the exclusive synthesis of BHMF from the partial (carbonyl) hydrogenation of HMF, while the MP reaction run at a higher T and p (100 °C and 50 bar) proved excellent to achieve only HHD derived from a sequence of hydrogenation/hydrogenolysis. It is worth noting that under MP conditions, the catalyst was perfectly segregated in the IL, where it could be recycled without any leaching in the aqueous/hydrocarbon phases. Finally, the hydrogenation of HMF was explored in a H‐Cube® flow reactor in the presence of different solvents, such as ethyl acetate, tetrahydrofuran, and ethanol. At 100 °C, 50 bar H2, and a flow rate of 0.1 mL min−1, the process was optimized towards the formation of the full hydrogenation product BHMTHF. Ethyl acetate proved the best solvent. [ABSTRACT FROM AUTHOR]

Inverter's performance and operating mode may be negatively affected by inverter input (dc‐link) current and voltage ripple. It is a common experience that even theoretically balanced loads with perfectly balanced supply voltages, such as multiphase ac motors supplied by pulse‐width modulation (PWM) inverters, in practice show a certain degree of current unbalance, in the range of a few percent, which introduces a low‐frequency instantaneous power oscillation. This reflects in current and voltage low‐frequency ripple on the dc‐link inverter side (i.e. at the double‐fundamental frequency). A possible method to analyse this matter is through the symmetric sequence components. In particular, based on the first negative current sequence component and by considering the equivalent dc‐link impedance calculated at the dominant double‐fundamental frequency, the amplitude of the corresponding dc‐link voltage ripple component is calculated in this work for a general multiphase load. Finally, the design of the dc‐link capacitor in multiphase inverters is proposed considering requirements referred to the double‐fundamental dc voltage ripple. The feasibility of the proposed developments has been verified for three‐, five‐ and seven‐phase inverters by both numerical simulations and comprehensive experimental tests, always showing a good matching. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three node CHyQMOM is successfully implemented in OpenFOAM-7. • The algorithm can capture particle trajectory crossing without delta shocks. • For wall bounded problems results are not accurate. • Attention should be paid to prevent over-accumulation. The modeling of dilute gas-particle flows is challenging due to particle-trajectory crossing (PTC). Lagrangian particle tracking can be used, but requires a large number of parcels resulting in high computational costs. A less costly method is the Eulerian number density function (NDF) approach, based on the Boltzmann equation, often solved in terms of lower-order moments of the NDF. In this context the conditional hyperbolic quadrature method of moments (CHyQMOM) was developed and is here implemented for the first time in the OpenFOAM-7, together with high-order advection schemes and a new operator splitting procedure. The resulting solver is used to simulate different test cases: phase segregation problems, collision-less and weakly-collisional PTC flows, asymmetric and symmetric Taylor-Green vortex flow and a dilute gas-particle riser. Results, validated against analytical solutions and predictions obtained with Lagrangian particle tracking, show that the implemented CHyQMOM can be used to handle highly non-equilibrium flows. [ABSTRACT FROM AUTHOR]

[Display omitted] • LES framework was adopted to describe bubble columns at high gas velocity. • A phase blending method was used to account for phase inversion. • The Smagorinsky model corrected for BIT effects showed the best performance. • The model can simulate accurately a wide range of operating conditions. In this study the large eddy simulation (LES) turbulence approach was adopted to simulate bubble columns in a wide range of gas velocity and operating conditions, in order to obtain a general model capable of simulating with satisfactory accuracy and moderate computational resources most industrial cases. The model used to carry out the numerical simulations stems on the Eulerian–Eulerian two-fluid model. A particular feature of the model is the implementation of a blending approach, which is adopted to describe the phase inversion at the surface of the gas–liquid mixture. An extended investigation of the main LES turbulence models was conducted at high gas velocity to find the most suitable one for the investigated test cases: the Smagorinsky model accounting also for the bubble induced turbulence provided the most notable results in a wide range of operating conditions. The validity of the model was also confirmed at lower gas velocity. A comparison with the standard k – ε RANS model showed that the LES methods produced significantly more accurate results, in particular for systems with non-symmetrical gas feed, even though the computational time required is marginally higher. [ABSTRACT FROM AUTHOR]

The modulation law of the two-level five-phase voltage source inverters is modelled with two decoupled subspaces and their respective reference voltages. A new voltage-time system based on the duty cycles for this topology is presented in this article. Then, an alternative scheme to the space vector modulation is developed by deriving an analytic solution for the case of study, which is achieved with a low-computational cost algorithm. The strategy reckons the duty periods of the power switches immediately and can be implemented straightforwardly in a digital controller. The zero-sequence voltage is also considered to provide multifrequency operation either in continuous or discontinuous switching modes. The experimental validation, considering the time and frequency responses, supports the theoretical derivations in the introduction of this new method. [ABSTRACT FROM AUTHOR]

It is well known that multiphase machines exhibit the better performance (efficiency, torque density, fault tolerance, etc.) than three-phase machines. From the manufacturing point of view, it is interesting to have the possibility of improving a machine design by just conducting minor changes in the production process. In this regard, six-phase machines emerge as the natural choice to improve a design without modifying the active parts. This article presents an optimal procedure to shift from a three-phase to a six-phase induction motor design by just rearranging the coil connections. By starting from a three-phase winding design, different six-phase winding arrangements are analyzed. A methodology to define all the possible six-phase winding arrangements is presented. Discard criteria based on balanced radial forces and impedances are defined. Afterward, selected winding candidates are compared in terms of analytical calculations and later on, based on finite element (FE) simulations for a 690 V, 1-MW induction machine design. Different possible configurations are evaluated in terms of stator Joule losses, torque ripple, power factor, and electromagnetic efficiency both under healthy and faulted inverter conditions. Finally, a six-phase machine prototype is tested in order to verify the improvement in machine characteristics, thus validating the proposed method. [ABSTRACT FROM AUTHOR]

The suitability of ionic liquids (alkylmethylimidazolium bromides) as surfactants in an aqueous multiphase system for the Pd‐catalyzed hydrocarboxylation of 1‐dodecene is discussed. Attention is paid to the influence of these ionic liquids on the reaction performance and the phase separation. All tested ionic liquids are suitable as surfactants, but their concentration has a strong impact on the reaction performance. The resulting product concentrations are crucial for the phase behavior and so for the phase separation. In recycling experiments, the Pd‐catalyst is successfully separated and reused. [ABSTRACT FROM AUTHOR]

Pickering emulsions have received increasing interest in many fields of application recently. In designing Pickering emulsion properties, focus is typically laid on composition whereas the preparation process as another possible leverage is not considered in detail. Here, Pickering emulsions of constant composition were prepared using two dispersing heads of a rotor‐stator homogenizer and compared in terms of Sauter mean diameters and rheology. It was found that the ratio of tip speed and gap width between rotor and stator is a better correlating parameter than tip speed only. [ABSTRACT FROM AUTHOR]

This paper is a description of the evolution of long-term research work on two-phase flows using parallel studies of dynamic image analysis and stochastic processes analysis. The state of current knowledge on the research of gas-solid and gas-liquid systems as well as a review of research relating to these issues are also presented. The work grants the principles of videogrammetric surveys based on stochastic analysis for a series of photographs taken with video techniques. The method applies the analysis of changes in selected features and parameters in the time domain. Especially in application to multiphase gas-liquid and solid-gas mixture flows, which are characterized by strong variabilities. Parameters such as flow patterns of the mixture were determined as time-space distributions of phase concentration, displacement velocities of separated two-phase structures, volume partitions of phases, and velocity field distributions are evaluated. The changes of certain parameters characterizing the flow in the time domain often hide more useful information. The subject of this study covers the basics of videogrammetry with a description of two-phase mixture motion for co-current flow in channels, mapping of the phase velocity field, also across the tube bundle in shell-and-tube apparatus, phase motion at the flow of a two-phase gas-liquid mixture in mini-channels, transport of liquids in air-lift pump and fluidization of solid particles. [ABSTRACT FROM AUTHOR]

Energy efficiency is a key issue of sustainable development. During the design of industrial devices, it strives to achieve the highest possible energy efficiency. In the industrial systems, two-phase flow is a difficult task, especially the prediction, and maintenance of the two-phase flow regime. That is why this research proposes the evaluation and choice of an algorithm that will give a hint of the device design for which the hydrodynamic conditions of the two-phase mixture flow may be evaluated. The tests were carried out in a rectangular vertical narrow channel, as this type of device is in common use. The work aimed to show which algorithm is better for such evaluation. Parameters such as pressure drop, heat, mass, and momentum transfer are influenced by the phase velocity field. Still, various models are used for the determination of the velocity field. Therefore, there is a problem of choosing a model that will give the results closest to the real conditions. Flow visualization gives the non-invasive determination of the actual velocity field. An analysis of the velocity field was performed, which showed that for different two-phase flow regimes there are differences for given algorithms. The following algorithms were used to determine the velocity vector field: adaptive correlation method and adaptive particle image velocity method were used which are the parts of the general digital particle image velocimetry. The determination of the velocity fields in the quantitative and qualitative assessment of a given two-phase flow regime was obtained. The result of the research is the evaluation of algorithms for characterization two-phase gas-liquid flow. [ABSTRACT FROM AUTHOR]

Summary: Next‐generation distribution systems will be characterized by higher unbalanced currents due to increased asymmetrical currents produced by fast charging of electric vehicles and high short‐circuit currents under meshed operation. The unbalanced currents flowing through earthing impedances produce neutral‐earth voltages (NEVs) that may compromise the security (IEEE 62.92) and the safety (IEEE 80) of the system. Existing PMU‐based distribution system state estimation (PMU‐DSSE) methods described in literature are unable to estimate neutral‐earth voltages. To fulfill the research gap, this paper presents a new PMU‐DSSE formulation capable to estimate NEVs taking advantage of the OpenDSS's multiphase network model. The proposed procedure was successfully applied in two well‐known NEV test cases modeled in the OpenDSS platform. [ABSTRACT FROM AUTHOR]

We developed a generalized multiphase-field modeling framework for addressing the problem of brittle fracture propagation in quartz sandstones at microscopic length scale. Within this numerical approach, the grain boundaries and crack surfaces are modeled as diffuse interfaces. The two novel aspects of the model are the formulations of (I) anisotropic crack resistance in order to account for preferential cleavage planes within each randomly oriented quartz grain and (II) reduced interfacial crack resistance for incorporating lower fracture toughness along the grain boundaries that might result in intergranular crack propagation. The presented model is capable of simulating the competition between inter- and transgranular modes of fracturing based on the nature of grain boundaries, while exhibiting preferred fracturing directions within each grain. In the full parameter space, the model can serve as a powerful tool to investigate the complicated fracturing processes in heterogeneous polycrystalline rocks comprising of grains of distinct elastic properties, cleavage planes, and grain boundary attributes. We demonstrate the performance of the model through the representative numerical examples. [ABSTRACT FROM AUTHOR]

The volumetric, uniform, and selective heating of microwaves is a novel technique with the potential to be established in a wide range of applications. The individual interaction of each phase/component of multiphase/multicomponent systems with microwaves creates more than a temperature in the system. Having a high local temperature on an active site that is a strong microwave receptor promotes catalytic and non‐catalytic reactions. The relatively low temperature of the bulk material(s) restricts the undesirable secondary reactions correspondingly. This finding has already led to several applications. In this work, the fundamentals of microwave heating and their prospective applications are debated. Select lab‐scale results of metal and sulphur removal from petroleum oil, pyrolysis of lignin, and dry reforming of methane are demonstrated. The expected impacts of microwaves on other multiphase reactions are proposed. [ABSTRACT FROM AUTHOR]

The structure of this work in the field of queuing theory consists of two stages. The first stage presents Little’s Law in Multiphase Systems (MSs). To obtain this result, the Strong Law of Large Numbers (SLLN)-type theorems for the most important MS probability characteristics (i.e., queue length of jobs and virtual waiting time of a job) are proven. The next stage of the work is to verify the result obtained in the first stage.

Bu çalışma, çok fazlı polimer sistemlerinde, nanoparçacık ihtiva eden insan servikal kanser HeLa hücrelerinin, hücreler arasındaki yoğunluk farkına dayanılarak ayrıştırılması üzerinedir. Sulu çok fazlı sistemler, suda çözünen polimer ve/veya sürfaktanların çeşitli kombinasyonlarının karıştırılmasını takiben faz ayrışmasıyla oluşur. Sistemin fazları yoğunluklarına göre üst üste dizilirler ve birbirine komşu her iki fazın arasında yoğunluk-adımı olarak hareket edebilen bir interfaz bulunur. Bu interfaz, nesneleri yakalayabilecek bir bariyer görevi görür ve faz ayrışmasıyla oluştuğu için kararlıdır. Bu sistemler hazırlandıktan ve ayrıştırma için eniyilendikten sonra, hücrelerin sisteme eklenmesi ve sentrifügasyon yardımı ile ayrıştırma sağlanır. Bu çalışmada, altın nanoparçacıklarıyla kontrollü şekilde etkileşen HeLa hücrelerinin, yoğunluklarındaki değişime istinaden, sulu çok fazlı sistemlerde ayrıştırılmaları gösterilmiştir.

Carbon capture technology can be set up in combination with biocatalysis to utilize the bound CO2 as substrate in the Kolbe‐Schmitt like enzymatic reaction. The exemplary whole cell biotransformation of catechol to 2,3‐dihydroxybenzoic acid in a triethanolamine‐mediated multiphase system shows increased equilibrium conversion. Apart from the beneficial thermodynamics, the inherent fluid properties of triethanolamine is enabling easy application of CO2 fine bubbles as highly efficient gassing method to minimize the CO2 demand and CO2 emissions. [ABSTRACT FROM AUTHOR]

A new nonstationary conjugate mathematical model of thermal and stressed-strained state in loaded joints of metal elements in the presence of nonideal thermal contact has been formulated. A one-dimensional approximation of the model in a stationary case has been obtained. A numerical investigation of the approximate mathematical model has been carried out. Satisfactory agreement has been shown between the calculated values of thermal resistance of the contact of plane rough surfaces and the experiential data. [ABSTRACT FROM AUTHOR]

This paper presents characterization and operational envelope of a hybrid permanent magnet (HPM) generator in a series hybrid electric vehicle (SHEV) powertrain. A proposed control strategy is applied to characterize the system during vehicle operation within new european driving cycle (NEDC). The HPM generator utilizes a permanent magnet topology assisted with a wound field (WF) rotor while the machine 9-phase output is rectified and connected to the SHEV main dc-link. A brushless exciter with dc stator and multiphase rotor is designed to provide an adjustable dc current and voltage to the HPM generator WF. The brushless exciter dc stator is fed from the vehicle dc-link using a dc/dc converter while its rotor output connects to an integrated 32-leg rotating rectifier the output of which provides a high quality dc to the HPM generator WF. A control strategy incorporating a dynamic model of the HPM generator, brushless exciter, and dc/dc converter is proposed under which the system operational envelope is obtained. The HPM generator efficiency map, torque speed, and WF current behavior is analyzed to realize an optimum operating region while the SHEV operates over the NEDC driving cycle. The analytically predicted results are validated against measurements from a laboratory prototype HPM generator and exciter system. The comparison shows the effectiveness of the control method and accuracy of the developed models. [ABSTRACT FROM AUTHOR]

In this paper, we present a modeling framework for a class of multiphase chemical systems based on non-equilibrium thermodynamics. Compartmental modeling is used to establish the dynamic properties of liquid–vapor systems operating far from thermodynamic equilibrium. In addition to the bulk-phase molar/energetic dynamics, interface transport processes yield to algebraic constraints in the model description. The irreversible system is thus written as a system of differential-algebraic equations (DAEs). The non-equilibrium liquid–vapor DAE system is shown to be of index one. A local stability analysis for the model shows that the equilibrium state is unstable for non-isobaric operation regimes, whereas numerical evidence shows that isobaric operation regimes are stable. To extend the stability analysis, internal entropy production for the irreversible flash-drum is presented as a Lyapunov function candidate. [ABSTRACT FROM AUTHOR]

At 60–150 °C and 15–35 bar H2, two model reactions of levulinic acid (LA), hydrogenation and reductive amination with cyclohexylamine, were explored in a multiphase system composed of an aqueous solution of reactants, a hydrocarbon, and commercial 5 % Ru/C as a heterogeneous catalyst. By tuning the relative volume of the immiscible water/hydrocarbon phases and the concentration of the aqueous solution, a quantitative conversion of LA was achieved with formation of γ‐valerolactone or N‐(cyclohexylmethyl)pyrrolidone in >95 and 88 % selectivity, respectively. Additionally, the catalyst could be segregated in the hydrocarbon phase and recycled in an effective semi‐continuous protocol. Under such conditions, formic acid additive affected the reactivity of LA through a competitive adsorption on the catalyst surface. This effect was crucial to improve selectivity for the reductive amination process. The comparison of 5 % Ru/C with a series of carbon supports demonstrated that the segregation phenomenon in the hydrocarbon phase, never previously reported, was pH‐dependent and effective for samples displaying a moderate surface acidity. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Multiphase systems are relevant in many fields of process engineering. For process and product design in connection with multiphase systems, knowledge on the thermophysical properties of the individual phases such as viscosity and on the interfacial tension between these is required but often lacking in literature. In the present study, the applicability of surface light scattering (SLS) for the simultaneous measurement of interfacial tensions and viscosities in multiphase systems in macroscopic thermodynamic equilibrium is demonstrated. For two model systems consisting of n -decane and methanol as well as n -dodecane and methanol forming a vapor-liquid-liquid equilibrium at atmospheric pressure, surface fluctuations which show an oscillatory behavior at the vapor-liquid and liquid-liquid interface could be associated with hydrodynamic modes. From an exact theoretical description of the dynamics of the surface fluctuations, absolute data for the dynamic viscosities of the two liquid phases as well as the vapor-liquid and liquid-liquid interfacial tensions could be determined at temperatures between (333 and 358) K with total measurement uncertainties (k = 2) down to about 2%. For both systems studied at temperatures close to the upper critical solution temperature, the viscosities of the two liquid phases approach each other and the liquid-liquid interfacial tension tends to zero. [ABSTRACT FROM AUTHOR]

This article presents three variants of the Pulse Width Modulation (PWM) for the Double Square Multiphase type Conventional Matrix Converters (DSM-CMC) supplying loads with the open-end winding. The first variant of PWM offers the ability to obtain zero value of the common-mode voltage at the load’s terminals and applies only six switches within the modulation period. The second proposal archives for less Total Harmonic Distortion (THD) of the generated load voltage. The third variant of modulation concerns maximizing the voltage transfer ratio, minimizing the number of switching, and the common-mode voltage cancellation. The discussed modulations are based on the concept of sinusoidal voltage quadrature signals, which can be an effective alternative to the classic space-vector approach. In the proposed approach, the geometrical arrangement of basic vectors needed to synthesize output voltages is built from the less number of vectors, which is equal to the number of the matrix converter’s terminals. The PWM duty cycle computation is performed using only a second-order determinant of the voltages coordinate matrix without using trigonometric functions. A new approach to the PWM duty cycles computing and the load voltage synthesis by 5 × 5 and 12 × 12 topologies has been verified using the PSIM simulation software.

Applying multiphase systems in microreactors leads to an intensification of heat and mass transport. Critical aspects of the well-studied segmented slug-flow, such as bubble generation and pump control, can be automated, provided a robust sensor for the reliable determination of velocity, phase lengths, and phase ratio(s) is available. In this work, a fast and low-priced sensor is presented, based on two optical transmission sensors detecting flow characteristics noninvasively together with a microcontroller. The resulting signal is mainly due to refraction of the bubble-specific geometries as shown by a simulation of light paths. The high performance of the processing procedure, utilizing the derivative of the signal, is demonstrated for a bi- and triphasic slug flow. The error of