Mixing Performance Research Articles

Unveiling the role of mixing in [Fe(CN)6]4− defects and Na content for preparing NaxMn[Fe(CN)6]y · nH2O via microreactor

AbstractTaking advantage of strong mixing performance in oscillating feedback microreactor (OFM), the manganese hexacyanoferrates (NaxMn[Fe(CN)6]y · nH2O, MnHCFs) with low defects and high sodium content were controllably prepared. First, fluid mixing performance in OFM was investigated via dye‐tracer and Villermaux‐Dushman experiments, and the fluid mixing mechanism in OFM was investigated through CFD simulations. Then, MnHCFs were prepared using OFM at different flow rates, and the role of mixing in [Fe(CN)6]4− vacancies and sodium content during co‐precipitation synthesis of MnHCFs was discussed. The results indicate that an increase in flow rates can increase fluid chaos strength, enhancing the mass transfer process to match the extremely fast reaction rate of MnHCFs, thus preparing MnHCFs with high sodium content and low defects. Relevant electrochemical tests indicate that the MnHCF prepared at the largest throughput (180 mL/min) has the highest initial specific capacity (132 mAh/g at 15 mA/g), minimum electrochemical impedance, and fastest sodium ion transport rate.

Experimental Testing and Numerical Simulation of Recycled Concrete Aggregate in a Concrete Mix

This study focuses on exploring the potential of utilizing demolished concrete and promoting sustainable practices through the use of recycled concrete aggregate (RCA) as a substitute for natural aggregates, particularly in the context of Nepal. The region’s susceptibility to frequent earthquakes results in significant volumes of concrete rubble, posing challenges in waste disposal. To address this issue and mitigate resource depletion, the research focuses on concrete recycling. By conducting a thorough analysis of mechanical properties, crack patterns, strength variations, and specific gravity evaluations across different RCA compositions, the study emphasizes the ongoing endeavors toward sustainable concrete practices. A comparative examination of test results involving varying percentages of coarse recycled aggregate content (0%, 25%, 50%, 75%, and 100%) denoted as R0, R25, R50, R75 and R100, respectively, provides insights into the performance of different mixes. The compressive strength of cube for R25 increased by 20.13%, while R50 and R75 showed gains of 8.08% and 1.28%, respectively, while cylinder showed an increase of 25.86%, 18.88%, 9.54% and 2.65% for R25, R50, R75 and R100, respectively, compared to R0 concrete mix when tested at 28 days of curing. Tensile strength of concrete cylinder also improved, with R25 showing an 18.52% increase and R50 showing a 9.26% increase. Additionally, the RCA increased the flexural strength, with R25 leading with a 5% increase and R50 following with a 1.66% increase at 28 days of testing. The inclusion of numerical analysis in ABAQUS CAE using the Kent and Park Model serves to reinforce and support the experimental findings, establishing the credibility of both approaches. In essence, the study strongly advocates for the integration of recycled aggregate in concrete as a means to foster sustainable development and environmentally friendly construction methods.

Design and Investigation of a Passive-Type Microfluidics Micromixer Integrated with an Archimedes Screw for Enhanced Mixing Performance.

In recent years, microfluidics has emerged as an interdisciplinary field, receiving significant attention across various biomedical applications. Achieving a noticeable mixing of biofluids and biochemicals at laminar flow conditions is essential in numerous microfluidics systems. In this research work, a new kind of micromixer design integrated with an Archimedes screw is designed and investigated using numerical simulation and experimental approaches. First, the geometrical parameters such as screw length (l), screw pitch (p) and gap (s) are optimized using the Design of Expert (DoE) approach and the Central Composite Design (CCD) method. The experimental designs generated by DoE are then numerically simulated aiming to determine Mixing Index (MI) and Performance Index (PI). For this purpose, COMSOL Multiphysics with two physics modules-laminar and transport diluted species-is used. The results revealed a significant influence of screw length, screw pitch and gap on mixing performance. The optimal design achieved is then scaled up and fabricated using a 3D additive manufacturing technique. In addition, the optimal micromixer design is numerically and experimentally investigated at diverse Reynolds numbers, ranging from 2 to 16. The findings revealed the optimal geometrical parameters that produce the best result compared to other designs are a screw length of 0.5 mm, screw pitch of 0.23409 mm and a 0.004 mm gap. The obtained values of the mixing index and the performance index are 98.47% and 20.15 Pa-1, respectively. In addition, a higher mixing performance is achieved at the lower Reynolds number of 2, while a lower mixing performance is observed at the higher Reynolds number of 16. This study can be very beneficial for understanding the impact of geometrical parameters and their interaction with mixing performance.

RSVP Keyboard with Inquiry Preview: mixed performance and user experience with an adaptive, multimodal typing interface combining EEG and switch input.

The RSVP Keyboard is a non-implantable, event-related potential-based brain-computer interface (BCI) system designed to support communication access for people with severe speech and physical impairments. Here we introduce Inquiry Preview, a new RSVP Keyboard interface incorporating switch input for users with some voluntary motor function, and describe its effects on typing performance and other outcomes. Four individuals with disabilities participated in the collaborative design of possible switch input applications for the RSVP Keyboard, leading to the development of Inquiry Preview and a method of fusing switch input with language model and electroencephalography (EEG) evidence for typing. Twenty-four participants without disabilities and one potential end user with incomplete locked-in syndrome took part in two experiments investigating the effects of Inquiry Preview and two modes of switch input on typing accuracy and speed during a copy-spelling task. For participants without disabilities, Inquiry Preview and switch input tended to worsen typing performance compared to the standard RSVP Keyboard condition, with more consistent effects across participants for speed than for accuracy. However, there was considerable variability, with some participants demonstrating improved typing performance and better user experience with Inquiry Preview and switch input. Typing performance for the potential end user was comparable to that of participants without disabilities. He typed most quickly and accurately with Inquiry Preview and switch input and gave favorable user experience ratings to those conditions, but preferred standard RSVP Keyboard. Inquiry Preview is a novel multimodal interface for the RSVP Keyboard BCI, incorporating switch input as an additional control signal. Typing performance and user experience and preference varied widely across participants, reinforcing the need for flexible, customizable BCI systems that can adapt to individual users. gov Identifier: NCT04468919.

The Use of Reinforced Concrete for Durable and Aesthetic Sports and Recreational Sports

This study focuses on the design and construction of durable recreational seating using reinforced concrete, addressing the limitations of traditional materials such as wood and metal, which are prone to environmental degradation and high maintenance costs. Reinforced concrete is known for its durability, strength, and resistance to harsh weather conditions, making it an ideal material for public seating in outdoor environments. Several key tests were conducted to assess the performance of the concrete mix used in this project. Sieve analysis confirmed that the fine and coarse aggregates were well-graded, ensuring optimal compaction and strength. The slump test,conducted with a water-cement ratio of 0.6, produced a slump value of 150 mm, indicating medium workability. This level of workability is suitable for concrete that requires easy placement and proper compaction without segregation or excessive bleeding. The compressive strength test at 7 days yielded a compressive strength of 15.81 MPa, demonstrating the early strength development of the concrete. However, compressive strength results for the 14-day and 28-day tests are still pending, as the remaining cubes are currently in the curing tank. These results will provide further insights into the long-term strength and performance of the concrete once the curing process is completed. Preliminary findings suggest that reinforced concrete is an excellent choice for recreational seating due to its ability to provide long-lasting durability and reduced maintenance. The combination of well-graded aggregates, an optimal water-cement ratio, and promising early compressive strength indicates that this material will perform well under both static and dynamic loads typically encountered in public seating.

Study on mixing and combustion performance of a kerosene-fueled dual-cavity configuration scramjet engine

Study on mixing and combustion performance of a kerosene-fueled dual-cavity configuration scramjet engine

Mixed lubrication performance analysis of a novel water-lubricated thrust bearing considering transient thermal, cavitation, and turbulence

Mixed lubrication performance analysis of a novel water-lubricated thrust bearing considering transient thermal, cavitation, and turbulence

Simulation investigation on volumetric mixing of the rotary ERD unit and array in the SWRO desalination system

In SWRO desalination system, both low volumetric mixing and high flow capacity of rotary ERD unit is the bottleneck problem at present. Here, a new motor-driven rotary ERD (MD-RERD) is proposed with a large length-diameter ratio rotor and high flow capacity of 110 m3/h. When the length-diameter ratio increases from 14.5 to 18.5 based on unchanged rotor channel diameter, the volumetric mixing of MD-RERD at rotating speed (140 rpm) decreases from 5.503 % to 1.728 % by CFD simulation, which is much lower than that of commercial rotary ERD. Moreover, the MD-RERD shows high energy recovery efficiency of 98.2 %. To further evaluate the mixing performance, an array model composed of 5 MD-RERD units with the flow capacity of 550 m3/h is constructed. The volumetric mixing of the array is 2.339 % under traditional ZZ-array, which is 35.4 % more than that of the single unit due to poor matching degree of volume flowrate between high-pressure route and low-pressure route. Moreover, when the rotor rotates anticlockwise at 140 rpm, the high-pressure route with U-type shows much higher uniformity of flow distribution than Z-type, which is close to that of low-pressure route with Z-type. Therefore, the Z-type is changed to U-type in high-pressure route to construct the UZ-array. Consequently, the matching degree of volume flowrate between the two routes increases, and the volumetric mixing of the array decreases to 1.968 %, which is only 13.9 % more than that of the single unit. It is beneficial to further improve the comprehensive efficiency of the ERD and thus significantly reduce the energy consumption in SWRO desalination system compared to the commercial ERD with a common volumetric mixing of 6 %.

How Mixed Performance Feedback Shapes Exploration: The Moderating Role of Self-Enhancement

We conduct an experiment to examine how providing decision makers with high versus low peer performance information influences choices between exploration and exploitation. Previous work on organization-level learning suggests that a high-performing peer would fuel exploration, whereas a low-performing peer would dampen it. In line with this, we find that individuals who receive information about a high-performing peer explore more than those who receive information about a low-performing peer. However, we also find that compared to individuals with a low tendency to self-enhance, individuals with a high tendency to self-enhance are less likely to explore when receiving information about a high-performing peer. In fact, these individuals explore at levels comparable to those who receive information about a low-performing peer. We explain this behavioral pattern by demonstrating that as individuals learn and improve, information about a high-performing peer increasingly results in mixed performance feedback; under these conditions of relative interpretive flexibility, exploration is moderated by decision makers’ tendency to self-enhance. When these individual dynamics are aggregated, our data suggest that an organization that provides peer performance information may experience either the same or less exploration than an organization that does not, with the exact difference depending on its proportion of high self-enhancers. These insights into the contingencies and aggregate effects of how individuals interpret and respond to peer performance information are particularly relevant given recent interest in designing organizations that shape employee behavior through the provision of feedback rather than through traditional instruments of coordination and control, such as incentives or hierarchy. Funding: This work was supported by Danmarks Frie Forskningsfond [Grant 25194]. Additionally, this research was supported by a grant from the HEC Paris Foundation.

Unified carbon emissions and market prices forecasts of the power grid

Carbon emissions and market prices forecasts of the power grid are of great importance for all electricity traders and consumers. Both forecasts enable flexible demand scheduling, ensuring sustainability and cost-efficiency. Many studies show the benefits of using both forecasts independently but not in combination, which remains an unexplored problem. The latest state-of-the-art techniques involve advanced statistical and machine learning algorithms leveraging seasonal patterns and exogenous forecasts. However, most of the reported studies deal only with problems of modeling and feature engineering, neglecting the forecast and model errors, which accumulate within the time-evolving power grid. This research aims to tackle these issues by introducing a versatile framework for short-term probabilistic forecasting of unified carbon emissions and market prices for electricity intra-day market participants. The approach utilizes the Hidden Markov Model for predictive estimation to determine the future energy mix of the country’s power grid. Furthermore, a novel optimization-based strategy, Moving Horizon Predictive Correction, is proposed to enhance the estimated energy mix performance, minimizing forecast and model errors. Subsequently, two separate recurrent neural networks are trained to provide probabilistic forecasts of carbon emissions and market prices, accounting for the stochastic dynamic of the power grid. A comparative analysis examines six case studies from various European countries and compares them with state-of-the-art forecasting methods. The results indicate that the proposed method can improve the qualitative measures by up to 53% for carbon emissions and up to 18% for market prices forecasts. Besides improving traditional point perditions, methods show significant increases in the quality of prediction intervals. Further application of the proposed forecasts is employed for a flexible 4–hour electricity consumption schedule. This showcases the usage of the proposed forecasts to find the best possible trade-off for low carbon emission, cost-effective electricity consumption time slots.

Mixing Performance Analysis of a Planetary Concrete Mixer

In this research, the discrete element method is employed to study the mixing performance of a 1m3 capacity planetary concrete mixer. The performance was evaluated based on the homogeneity of granular particle mixing and the scanning of the mixer’s inside by the gyrational and planetary mixing blades. The granular particle mixing was realized by applying the Hertz-Mindlin contact law, constant directional torque, and the Simplified Johnson-Kendall-Roberts (SJKR) models using open-source software. Furthermore, analytical formulations for the trajectories of mixing blades were developed and implemented in MATLAB. The trajectories were plotted at various time intervals, and it was observed that the entire mixer was fully scanned in approximately 30 seconds. Finally, numerical and analytical results were compared to verify the findings.

Enhanced Fluid Mixing in Microchannels Using Levitated Magnetic Microrobots: A Numerical Study.

The efficient mixing of fluids at microscale dimensions presents challenges due to the dominant laminar flow regime which restricts convective mixing. This study introduces a numerical analysis of a novel microrobotic mixing system with a levitated propeller robot, driven by magnetic fields, within a Y-shaped microchannel with a square cross-section (500 × 500 μm). Our research investigates the fluid mixing effectiveness facilitated by the microrobot through various levitation heights and orientations to enhance the mixing index (MI). This index is tested under different conditions by leveraging the dynamics of the propeller robot, characterized by adjustable roll and pitch angles and varying levitation heights. The numerical simulations, conducted using COMSOL® (Finite Element Method, FEM) software, integrate Maxwell's equations for magnetic field interaction with momentum and transport-diffusion equations to analyze fluid dynamics within the microchannel. Results indicate that the propeller robot can achieve an MI of up to 98.94% at a 150 μm levitation height and 1500 rpm propeller speed within 3 s. Additionally, the study examines the impact of propeller speed, Reynolds number, and robot length on mixing performance, providing comprehensive guidance for optimizing microscale fluid mixing in lab-on-a-chip applications.

Numerical investigation and fabrication of L-turns spiral micromixers for enhanced mixing performance

In this paper, we simulated and fabricated an L-turn spiral passive micromixer design and compared it with a simple spiral design, both of which are particularly effective for improving mixing efficiency in bio-applications. Centrifugal force and secondary flow can be strengthened by the recommended spiral design. Furthermore, the L-turns improved the displacement of the velocity profile across the channel width leading to enhanced mixing efficiency. The micromixer performance was evaluated through a series of simulations and the effects of different parameters such as channel dimensions, inter-channel gaps, and flow rate were assessed. The contact area between the fluids is affected by the mentioned features, resulting in improved mixing efficiency. A mixing quality of over 90% is achieved after 26 mm (approximately one-third of the total channel length) at a flow rate of 25 μl/min, with a molecular diffusion coefficient of 1 × 10−10 m2/s. At last, the proposed fabrication process was presented to show the feasibility of the design.

Service Promotion Mix Strategies and Performance of Two-Star Hotels in Calabar Metropolis

The researcher examined the influence of promotion mix strategy on performance of two-star hotels in Calabar, Cross River State. The study was born out of the fact that management of this category of hotel find it challenging on how to select the right mix of promotional activities that will suit their business at a particular time and how to use it correctly to achieve a result. The key objective of the study was to explore the effect of promotion mix strategy on performance of two-star hotels in Calabar. The researcher adopted survey research design. Structured questionnaire was the core instrument for data collection. The data from the field was analyzed using simple linear regression and the result shows a significant relationship between social media, public relation and performance of two-star hotels in Calabar. The researcher concluded that those two-star hotels in Calabar who are ardent in adopting the modern promotion mix and incorporating it into their marketing strategies, have achieved above average performance and have sustainably changed their businesses. The researcher further recommended that two-star hotels management in Calabar that have not been using social media to a large extent should do so in order to boost their performance especially in this season of Calabar carnival rebirth and that management of these hotels should also pay more attention to public relation so as to create good image for the establishment and also enhance performance.

Oxime ether photobromination in a photomicroreactor: Process parameters and kinetic modeling

AbstractPhotobromination reaction of oxime ether (OE) to brominated oxime ether (BOE) is an important process for the synthesis of trifloxystrobin in the fungicide industry. Herein, continuous synthesis of BOE in photomicroreactors was performed. Initially, an investigation was carried out to study the effects of various parameters, including mixing performance, molar ratios, solvents, incident photon flux, and temperature, on the photobromination process. Moreover, a kinetic model was established, and the activation energies for the main and side reactions were determined. The relationship between the reaction rate constant and light flux was illuminated. Transition states and energy changes in the bromination process were analyzed using density functional theory calculation. Remarkably, an 83.1% yield of BOE was achieved in the photomicroreactor and the required reaction time was reduced to approximately 1/10 of the batch reactor. This work was of crucial theoretical significance and practical value for better understanding of photobromination processes and parameter optimization.

Development and Evaluation of a Helical Ribbon-Type Mixer for Mushroom Substrate

Manual substrate mixing for mushroom production such as rice straws, sawdust, and banana leaves is laborious and time-consuming. Substrates need to be thoroughly mixed to produce mushrooms of good quality. This study was done to design, fabricate, and evaluate the performance of a helical ribbon-type mixer. The performance of the ribbon-type mixer was evaluated in terms of the mixing capacity and mixing efficiency. Loading weight (5kg, 10kg, and 15kg) and operating speed (11-15rpm, 16-20rpm, and 21-25rpm) of the machine were used as the performance parameters. Analysis of Variance (ANOVA) for Factorial Experiment in Completely Randomized Design (CRD) was used to analyze the results while comparison among treatment means was tested at 5% level of significance using Duncan's Multiple Range Test (DMRT). Results revealed that the highest machine capacity of 226.67 kg/hr was attained at a loading weight of 15kg and an operating speed of 21-25rpm. Maximum mixing efficiency (95.27%) was achieved with the combination of 15 kg loading weight and an operating speed of 11-15 rpm. The initial investment in fabricating the substrate mixer for mushroom production was Php 21, 713. Operating the substrate mixer for mushroom production had a projected annual cost of Php 3,655.475. Break – even weight was 91,795.24 kg of substrates per year at a custom rate of Php 0.35 per kilogram.

On dynamics of flash boiling bubbles within liquid ammonia systems

It is crucially important to understand the dynamics of flash boiling bubbles of liquid fuels in order to achieve optimal fuel spray and mixing performance in realistic combustion engines. In this study, a modified pseudo-potential lattice Boltzmann method was adopted to capture the dynamics of flash boiling bubbles of liquid ammonia. The critical conditions for the flash boiling state of liquid ammonia were determined using isothermal depressurization techniques. Meanwhile, the evolutions of bubble clusters were investigated, allowing for bubble deformation, coalescence, and collapse in different flash boiling stages. The results show that the evolution of flash boiling bubble clusters presents two main stages, i.e., the early rapid expansion stage and the later slow expansion stage, and both stages are highly sensitive to temperature variations. Low-temperature environments can intensify the competition between bubble coalescence and collapse events, thereby changing the density, pressure, and velocity distribution and delaying the transition of bubbles to the eventual equilibrium state. In addition, the evolution of bubble clusters conforms to the Ostwald ripening mechanism, where large bubbles absorb smaller bubbles, promoting the formation and propagation of pressure waves in liquid ammonia. These pressure waves not only disturb the surrounding fluid to form vortices but also cause significant deformation of adjacent bubbles, thereby affecting the overall efficiency of flash boiling processes.

Advancing Mix Design Prediction in 3D Printed Concrete: Predicting Anisotropic Compressive Strength and Slump Flow

Introducing 3D-concrete printing has started a revolution in the construction industry, presenting unique opportunities alongside undeniable challenges. Among these, the major challenge is the iterative process associated with mix design formulation, which results in significant material and time consumption. This research uses machine learning (ML) techniques such as Extreme Gradient Boosting (XGBoost), Support Vector Machine (SVM), Decision Tree Regression (DTR), Gaussian Process Regression (GPR), and Artificial Neural Network (ANN) to overcome these challenges. A dataset containing 21 mix constituent features and 4 output properties (cast and printed compressive strength, and slump flow) was extracted from the literature to investigate the relationship between mix design and performance. The models were assessed using a range of evaluation metrics, including Mean Absolute Error (MAE), Root Mean Squared Error (RMSE), Mean Squared Error (MSE), and R-squared value. Gaussian Process Regression (GPR) yielded more favorable results. In the case of cast strength, GPR achieved an R2 value of 0.9069, along with RMSE, MSE, and MAE values of 13.04, 170.12, and 9.40, respectively. A similar trend was observed for printed strengths in directions 1, 2, and 3. GPR achieved R-squared values exceeding 0.91 for all directions, accompanied by significantly lower RMSE values (below 4.1). The machine learning models were also validated using four unique mix designs. These mixes were 3D printed and tested for compressive strength and slump flow. GPR's average error was 10.55%, while SVM achieved a slightly lower average error of 9.38%. Overall, this work presents a novel approach for optimizing 3D-printed concrete by enabling the prediction of slump flow and compressive strength directly from the mix design. This approach can facilitate the design and fabrication of 3D-printed concrete structures that fulfill the necessary strength and printability requirements.

Chaotic mixing performance of non-Newtonian fluids in S-Type static mixer and optimization based on response surface methodology

Chaotic mixing performance of non-Newtonian fluids in S-Type static mixer and optimization based on response surface methodology

Synthesis of fluorinated ether free aromatic backbone copolymers containing trifluoromethyl and dimethylamino groups for CO2 separation: Investigation of pure and mixed gas performance under dry and humid conditions

A novel series of linear, high molecular weight aromatic copolymers containing trifluoromethyl and dimethylamino groups was synthesized via facile super-acid catalyzed polyhydroxyalkylation and investigated as CO2 gas separation membrane materials. The molar ratio of the two ketone comonomers used in copolymerization, trifluoroacetophenone (TFAp) and N,N-dimethylamino trifluoroacetophenone (dMATFAp), was systematically varied to produce five copolymers with different dMATFAp contents ranging from 12 to 73 %. The influence of dMATFAp content on physicochemical and mechanical properties as well as pure gas and water vapor separation performance was studied. All synthesized copolymers displayed excellent film forming ability, high thermal stability and high Tg values (Tgs > 380 °C). Pure gas permeability measurements revealed that the increase of dMATFAp molar content from 12 % to 34 % resulted in improved gas permeability, while, on the contrary, further increase of dMATFAp content from 34 to 73 % led to substantial gas permeability decrease ascribed to FFV decrease. In particular, among copolymers, the one with dMATFAp content of 34 % presented the highest CO2 permeability value of 290 Barrer due to its highest CO2 diffusion and CO2 solubility coefficients associated with its higher FFV value. The CO2/CH4 performance of synthesized copolymers fell very close to 2008 upper bound limit and exceeded most of the super-acid catalyzed copolymer membranes reported in the literature and commercial membranes. CO2/CH4 and CO2/N2 selectivity values for the different synthesized copolymers were in the range of 29.9–40 and 22.7–44, respectively. The study of the effect of dMΑTFA on water permeability unveiled that the membrane with the highest dMΑTFAp molar content (73 %) showed the highest water permeability value (23,100 Barrer) as well. This was attributed to the increased concentration of N-methyl substituent of dMΑTFAp which can interact with water molecules thereby increasing solubility. Under process gas stream conditions using a mixture of 3 % H2O-48.5 % CO2-48.5 % CH4, both CH4 and CO2 permeability were significantly reduced (by 35 % and 47 %, respectively) due to the preferential sorption of water vapor over other gases present in the mixture, highlighting the negative effect of water vapor on gas permeability. Accordingly, the CO2/CH4 separation factor was slightly increased from 23.8 to 29. Finally, stability test of the copolymer (BP-TFAp)66-(BP-dMATFAp)34 at 40 °C under humid mixed gas conditions showed that CO2 and CH4 permeability remained unchanged for one month after an initial condition stabilization that is required implying that these copolymer structures are promising materials for CO2 separation.