Mixing Homogeneity Research Articles

Thermal and Durability Properties of Sustainable Green Lightweight Foamed Concrete Incorporating Eco-Friendly Sugarcane Fibre

Efforts to modify cement-based mixtures have always enticed the interest of researchers. Lightweight foamed concrete is immensely porous, and its properties diminish with increasing in the number of pores. To enhance its properties, the solid matrix of LFC can be attuned by integrating numerous natural fibres. The influence of eco-friendly sugarcane fibre in LFC was not investigated before in the current body of knowledge. Hence, there is some ambiguity considering the mechanism by which and the extent to which the sugarcane fibre can influence LFC properties. Therefore, this study concentrates on distinguishing the potential use of sugarcane fibre into lightweight foamed concrete. This study aims to determine the durability and thermal properties of LFC with the addition of sugarcane fibre. Low density of 800kg/m3 were cast and tested. Different weight fractions of sugarcane fibre of 0.15%, 0.30%, 0.45% and 0.60% were used. For durability properties, four parameters were appraised such as water absorption capacity, porosity, drying shrinkage, ultrasonic pulse velocity. While for thermal properties were assessed which were thermal conductivity, thermal diffusivity and specific heat capacity. Protein-based foaming agent Noraite PA-1 was utilized to produce the desirable density of LFC. To get the comparable results, the water to cement ratio was fixed to 0.45 while the cement to sand ratio constant at 1:1.5. The results had indicated that the addition of 0.45% of sugarcane fibre gave the optimum results for all the durability and thermal properties considered in this research. At 0.45% weight fraction of SF, the fibres and the cementitious matrix achieved maximum compaction, which stemmed in excellent mix homogeneity. Beyond the optimum level of sugarcane fibre inclusion, agglomeration and the non-uniform dispersion of fibres was observed, which led to decrease in entire durability and thermal properties appraised.

Effects of impeller designs and configurations on the flow field in multiple impeller system using Computational Fluid Dynamics (CFD)

The work presents the computational study of the flow field in multiple impellers stirred vessel with various impeller types and configurations at 300rpm, 450rpm and 600rpm. Three types of impellers are investigated, namely the pitched blade impeller (PB), flat blade impeller (FB) and sawtooth impeller (ST). In this study, the flow patterns, turbulent kinetic energy dissipation, and power consumption in dual impellers system have been studied using computational fluid dynamics (CFD) by employing the multiple reference frame (MRF) and realizable k-ɛ turbulence model. The results from PBFB and reversed FBPB indicate efficient and powerful mixing with the merging of flows from both impellers that circulates the entire vessel. Besides, the FB and ST configuration exhibits the mixing characteristics that enhance both dispersion and mixing homogeneity. It is proven in this study that the combination of axial and radial impellers improves the weak mixing zones in the stirred vessel by the complex flow patterns produced. On top of that, utilizing two different impellers could achieve two mixing objectives in a system with the exceptional features of each impeller. The results establish promising effects of the reverse rotation in axial impellers and the arrangement of two different impellers in a multiple impeller system. With the rapid growth of industrialization, understanding the fluid dynamics in a multiple impeller stirred vessel is fundamental to optimize and scale up industrial mixing operations. Hence, the empirical findings in this study will be beneficial in selecting the suitable combination of impellers and the orientations that will enhance industrial mixing operations. Apart from that, the present work also illustrates that the computational technique used can be extremely valuable in determining the fluid dynamics in complex multiple impeller system which is challenging to analyse experimentally.

Assessing the Homogeneity of Forage Mixtures Using an RGB Camera as Exemplified by Cattle Rations

The article examines existing methods for assessing the homogeneity of feed mixes in the feed industry and agriculture. As an alternative to existing approaches, the authors offer a low-cost online technology to assess the homogeneity of feed. The feedstuff under study includes feed mixes for cattle or compound feed consisting of naturally-grown feed (green mass of freshly cut grass, haylage, corn silage, etc.) and concentrated components (grain milling, sunflower, and soybean meal). The proposed method based on an RGB camera, a diode lamp, filters, and software is approved by a preliminary study of the physical properties of feed mix components by Specim IQ hyperspectral camera and revealing characteristics of light absorption of each type of components (concentrated/natural origin). The article presents a method of processing a feed mix image fixed by an RGB camera through light filters using Matlab Image Processing Toolbox tools, namely, a Color Thresholder app and Image Region Analyzer app.

Determination and optimisation of Resonant Acoustic Mixing (RAM) efficiency in Polymer Bonded eXplosive (PBX) processing

An investigation into how the efficiency (time and energy required for homogeneity) of Resonant Acoustic Mixing (RAM) can be determined and optimised was undertaken. An idealised Polymer Bonded eXplosive (PBX) simulant based on glass microbeads (28.3 μm D50, 62% v/v in binder and plasticiser) was used for mixing. Mixing evolution was monitored using machine output data, whereby the mixer ‘intensity’ (related to power draw) was plotted against time. Experiments were undertaken with three acceleration settings, three mixer units, and three vessel materials of low, medium, and high surface free energy. Different stages of the mixer ‘intensity’ profiles were found to correspond to discrete stages of mixing, as well as further rheological changes due to continued frictional heating, thus viscosity reduction, beyond homogeneity being achieved. Time to mixing completion was found to be repeatable within a standard deviation of ±10%, strongly dependent on acceleration setting, and additionally dependent on vessel material, though additional data is required to confirm this. A significant difference in mixing time was observed between different LabRAM units. Partial vacuum application without degassing was beneficial for mixing. Finally, a paradigm linking the ‘movement modes’ of mixing was constructed, based on literature observations and the experimental results.

Scalable and tunable Y2O3‐MgO composite for infrared transparency applications

AbstractThe process‐structure‐property correlationships in yttria‐magnesia (YM) composite have been investigated. YM composite was synthesized using commercial powders via ball‐milling route with three different grinding balls (Si3N4, Al2O3, ZrO2) having two different sizes (2 and 5 mm diameter). The alteration in grinding ball material and size produces sintered ceramic having different grain sizes (420–560 nm) and degree of phase mixing homogeneity (0.40–0.70). The contamination induced by the milling ball resulted in changes in Y2O3 and MgO defect chemistry, which influenced the grain growth behavior in the YM composite. The hot‐pressed composite prepared using 2‐mm Si3N4 ball‐milled powders exhibited the finest grain size (420 nm) and better phase mixing homogeneity (0.63). The subsequent impact was seen on transmittance efficiency (71%) over the 3–7‐μm wavelength range, which is ∼85% of the theoretical limit. The findings show that the selection of the right size and type of grinding ball for milling commercial powder is a simple and cost‐effective way for scalable production of YM composite with high transmittance efficiency for infrared windows and dome applications.

Preparation of Water-in-Oil Nanoemulsions Loaded with Phenolic-Rich Olive Cake Extract Using Response Surface Methodology Approach.

In this study, we aimed to prepare stable water-in-oil (W/O) nanoemulsions loaded with a phenolic-rich aqueous phase from olive cake extract by applying the response surface methodology and using two methods: rotor-stator mixing and ultrasonic homogenization. The optimal nanoemulsion formulation was 7.4% (w/w) of olive cake extract as the dispersed phase, and 11.2% (w/w) of a surfactant mixture of polyglycerol polyricinoleate (97%) and Tween 80 (3%) in Miglyol oil as the continuous phase. Optimum results were obtained by ultrasonication for 15 min at 20% amplitude, yielding W/O nanoemulsion droplets of 104.9 ± 6.7 nm in diameter and with a polydispersity index (PDI) of 0.156 ± 0.085. Furthermore, an optimal nanoemulsion with a droplet size of 105.8 ± 10.3 nm and a PDI of 0.255 ± 0.045 was prepared using a rotor-stator mixer for 10.1 min at 20,000 rpm. High levels of retention of antioxidant activity (90.2%) and phenolics (83.1–87.2%) were reached after 30 days of storage at room temperature. Both W/O nanoemulsions showed good physical stability during this storage period.

Spatially-resolved chemical and mechanical examination of adhesive mixing efficiency with ATR-IR and Martens hardness

In this work, a new combined approach to investigate the quality of mixed and cured 2-component epoxy adhesives will be proposed. The spatially-resolved attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) on a microscale and Martens hardness were used to investigate the chemical and mechanical properties respectively the performance of mixed 2-component epoxy adhesives. Therefore, the measurement principle was proved on samples with different proportion of the adhesive hardener. The results show that the difference in hardener proportion has a significant effect on the measurable epoxy concentration and the Martens hardness. In a second step the testing methods were applied to differently mixed adhesive samples to investigate the mixing homogeneity. The mixing methods used were hand mixing, a static mixer, an asymmetrical dual centrifuge and a novel mixing method based on power ultrasound. With a spatially-resolved representation of the ATR-FTIR and Martens hardness test results it is possible to distinguish between different mixed samples and to analyze the mixing quality. It was shown that the resolution and the sensitivity of the ATR-FTIR spectroscopy and the Martens hardness method allow to evaluate the mixing homogeneity of the used 2-component epoxy adhesives. Furthermore, the correlation of the non-destructive ATR-FTIR and hardness test results with destructive lap shear test of adhesive joints was investigated. By this, it was shown, that also the mechanical properties of adhesive joints are affected by the proportion of hardener and the used mixing method and correspond with the ATR-FTIR spectroscopy and Martens hardness.

On the boundedness of parabolic maximal operators on product domains

In this article, appropriate sharp Lp bounds for a certain class of rough maximal operators MΩ,γ with mixed homogeneity are established. Specifically, when the function Ω belongs to Lq(Sm−1×Sn−1) with m,n≥2 and q>1, the boundedness of the such operators is obtained. Further, the extrapolation argument employed in [1] is applied on these gotten bounds to obtain the Lp boundedness of the aforementioned operators whenever the kernels are in the space L(log⁡L)2γ′(Sm−1×Sn−1) or in the block space Bq(0,2γ′−1)(Sm−1×Sn−1) with 1<γ≤2 and q>1. Our obtained results are considered substantial extensions and improvements of what was known previously.

CFD simulation and performance evaluation of gas mixing during high solids anaerobic digestion of food waste

To analyze the flow characteristics of the gas-mixed high solids anaerobic digestion (HS-AD) system and optimize the mixing performance, the mixing performance of gas and non-Newtonian fluid in the HS-AD system was investigated using the CFD simulation. The mixing energy magnitude, input pattern and nozzle inlet angle were optimized by evaluating available mixing indices. The performed experiments showed that the non-Newtonian fluid properties and consistency index of the food waste increased as the total solid increased. Moreover, it was found that the higher the reactor diameter, the greater the input energy, the smaller the dead zone, and the higher the global velocity gradient. Under specific input energy conditions, more mixing was achieved with the gas dispersed inlet compared with the centralized inlet. Symmetrical nozzles were arranged in the digester with a spacing of 180°, and mixing was the most effective when each nozzle formed an angle of 45° with the horizontal tangent of the reactor wall. As for the available mixing indices, both local velocity gradient and UI were the key ones and more meaningful to reflect mixing homogeneity of the system. The obtained results demonstrate that CFD is a powerful tool to optimize the mixing performance in high solids anaerobic digestion systems.

Blend Segregation in Tablets Manufacturing and Its Effect on Drug Content Uniformity-A Review.

Content uniformity (CU) of the active pharmaceutical ingredient is a critical quality attribute of tablets as a dosage form, ensuring reproducible drug potency. Failure to meet the accepted uniformity in the final product may be caused either by suboptimal mixing and insufficient initial blend homogeneity, or may result from further particle segregation during storage, transfer or the compression process itself. This review presents the most relevant powder segregation mechanisms in tablet manufacturing and summarizes the currently available, up-to-date research on segregation and uniformity loss at the various stages of production process—the blend transfer from the bulk container to the tablet press, filling and discharge from the feeding hopper, as well as die filling. Formulation and processing factors affecting the occurrence of segregation and tablets’ CU are reviewed and recommendations for minimizing the risk of content uniformity failure in tablets are considered herein, including the perspective of continuous manufacturing.

MIXING PROCESSES AND EQUIPMENT. CONSTRUCTION MIXTURES AND MIXTURES FOR MANUFACTURING CONSTRUCTION MATERIALS. LECTURE 9

The article presents materials of Lecture 9 Theory of carrying and lifting, construction and road vehicles and equipment, which describes mixing machines, concrete mixtures, their dosage, quality and homogeneity. The process of concrete mixing and energy aspects of its production are described. The data on mixers used for producing mortars and clay suspensions are presented. The design of a special mixer for producing polystyrene-silicate mineralized granules and the production technology for hollow silicate spheres based on the working process of a special mixer are described.

The Use of Copper Oxides as Cross-Linking Substances for Chloroprene Rubber and Study of the Vulcanizates Properties. Part II. The Effect of Filler Type on the Properties of CR Products.

The properties of rubber materials are dependent on the characteristics of the elastomer matrix, the filler type, the cross-linking agent, the number of ingredients, and their interactions. In the previous article, we showed that chloroprene rubber can be efficiently cross-linked with copper(I) oxide or copper(II) oxide. During the processing of rubber compounds, the incorporation of a filler and a curing substance are two substantial parameters, such as the homogeneity of mixing and cross-linking that significantly affect the properties of the vulcanizates. Therefore, this work aimed to evaluate the curing characteristics, mechanical and dynamical properties, morphology, and flammability of the composites containing chloroprene rubber cross-linked with Cu2O or CuO and filled with different fillers (silica, carbon black, montmorillonite, kaolin, chalk). It was found that the type of filler and curing agent had a significant impact on the degree of cross-linking of the chloroprene rubber and the properties of its vulcanizates. The degree and speed of the cross-linking of filled CR were higher when the CR was cured with copper(II) oxide. Among the fillers used, the presence of carbon black or silica ensured the highest degree of CR cross-linking and the most useful properties. The flammability tests indicated that all produced vulcanizates were characterized by a high oxygen index, which allows them to be classified as non-flammable materials.

Fabrication process of smooth functionally graded materials through a real-time inline control of the component ratio

Functionally graded materials (FGMs) play an essential role in tissue engineering because of their satisfactory histocompatibility and excellent mechanical performance. While traditional manufacturing methods allow production of simple FGMs, precise control of composition and customized property at transition between the dissimilar materials is still a challenge. Here, an extrusion-based functionally graded additive manufacturing (FGAM) platform was developed to generate smooth graded parts by thrusting out monolithic cylindrical filaments with high viscosity. Furthermore, the rheological properties, hydrodynamic behavior, and mixed homogeneity of the non-Newtonian fluids were studied. Therefore, the appropriate solid contents, alternative energy-efficient mixers, and optimized printing parameters were proved to be beneficial for an outstanding deposition effect of the suspension. Ultimately, an object with smooth gradient was successfully manufactured. The validity of this strategy was verified via optical microscopy combined with an image processing method to gauge homogeneity and a scanning electron microscope to investigate graded composition and microstructure.

Investigating the upper limit for applying the coarse grain model in a discrete element method examining mixing processes in a rolling drum

Mixing is an essential manufacturing process in various industries. The processing procedure and final product quality depend on the homogeneity of mixing. Because it is difficult to evaluate mixing systems experimentally, the discrete element method is commonly employed. However, as the number of particles increases, this approach incurs huge computational costs. The coarse grain model offers a potential solution, but its applicability has not been widely demonstrated; this study aimed to elucidate the upper limit for applying the coarse grain model. To determine the appropriate simulation parameters, calibrations were performed by comparing the powder bed in experiments versus simulations. Various mixing processes were numerically evaluated, and the mixing characteristics were qualitatively consistent among all coarse-grained ratios. These mixing systems were also evaluated quantitatively based on Lacey’s mixing index, which indicated that the upper limit of the coarse-grained ratio was five times. It is therefore important to secure a sufficient number of particles in each cell and to use an appropriate number of cells. This study clarified the upper application limit and criteria for the coarse grain model and verified the maximum coarse-grained ratio (five times). This approach can be used to determine the coarse-grained ratio and reduce computational costs.

Increased agitation reliability for slurry suspension in mineral processing

Regular maintenance shutdowns are required for mineral processing tanks to clean sedimentation and scale. The labour cost and loss of production during maintenance negatively impact on the economics of the operation. Swirl Flow (SF) technology was developed to improve the reliability of agitation and to maximise tank online time between maintenance intervals. This technology simplifies the engineering in agitator mechanical design with reduced shaft length and removal of baffles. Tests showed that swirling flow could provide more energy efficient suspension compared with draft tubes or multiple impeller designs. It is demonstrated that SF is capable of suspending solids at very high concentration, which is impractical with a conventional agitator. A more uniform velocity over the tank wall surface is generated under SF, free of stagnant zones in the upper corner of the tank and other areas commonly encountered in conventional agitator designs. This feature reduces the formation of large lumpy scale that could form in the stagnant zones. Compared with a conventional agitator designs, SF provides mixing homogeneity with slightly longer mixing time.

Double-Edged Metabolic Effects from Short-Term Feeding of Functionalized Wheat Bran to Mouse Revealed by Metabolomic Profiling

Health-promoting activities of wheat bran are limited by the high-degree crosslinking of its dietary fiber and the low bioavailability of its phenolics. In this study, functionalized wheat bran (FWB) was prepared through a combination of milling, alkaline hydrolysis, high-shear mixing, and high-pressure homogenization treatments. Feasibility and metabolic effects of feeding FWB were investigated by a short-term mouse feeding trial and liquid chromatography-mass spectrometry-based metabolomic analysis. The combinatorial processing dramatically enhanced the function-associated physicochemical properties of wheat bran, including viscosity, fiber compositions, free ferulic acid, and antioxidant capacity. FWB feeding led to diverse positive metabolic effects, including fecal sequestration of bile acids and cholesterol, reduced serum triacylglycerols and cholesterol, elevated fermentation for short-chain fatty acids, increased bioavailability of ferulic acid and its microbial metabolites, and improved redox balance. However, FWB feeding also negatively affected the nutritional status by decreasing the bioavailability of essential amino acids through the excessive loss of amino acids in feces and disrupting lipid homeostasis by reducing choline supply in the liver. These double-edged metabolic effects warrant further investigations on how to achieve the balance between the functionalization of wheat bran bioactives and the disruption of nutrient bioavailability.

INVESTIGATION ON THE AIR-GAS CHARACTERISTICS OF AIR-HYDROGEN MIXER DESIGNED FOR DUAL FUEL – ENGINES

High smoke emissions, nitrogen oxide and particulate matter typically produced by diesel engines. Diminishing the exhausted emissions without doing any significant changes in their mechanical configuration is a challenging subject. Thus, adding hydrogen to the traditional fuel would be the best practical choice to ameliorate diesel engines performance and reduce emissions. The air hydrogen mixer is an essential part of converting the diesel engine to work under dual fuel mode (hydrogen-diesel) without any engine modification. In this study, the Air-hydrogen mixer is developed to get a homogenous mixture for hydrogen with air and a stoichiometric air-fuel ratio according to the speed of the engine. The mixer depends on the balance between the force exerted on the head surface of the valve and the opposite forces (the spring and friction forces) and its relation to decrease and increase the fuel inlet. Computational fluid dynamics (CFD) analysis software was utilised to study the hydrogen and airflow behaviour inside the mixer, established by 3.2 L engine. The Air-hydrogen mixer is examined with different speeds of engine1000, 2000, 3000 and 4000 RPM. Results showed air-hydrogen mixture was homogenous in the mixer. Furthermore, the stoichiometric air-fuel ratio was achieved according to the speed of the engine, the developed mixer of the AIR-Hydrogen mixing process provides high mixing homogeneity and engines with stoichiometric air-fuel ratios, which subsequently contributes to the high levels of efficiency in engine operation. In summary, the current study intends to reduce the emissions of gases and offer a wide range of new alternative fuels usage. While the performance of the diesel engine with the new air-hydrogen mixer needs to be tested practically.

Symmetry in Fourier Analysis: Heisenberg Group to Stein–Weiss Integrals

Embedded symmetry within the Heisenberg group is used to couple geometric insight and analytic calculation to obtain a new sharp Stein–Weiss inequality with mixed homogeneity on the line of duality. SL(2,R) invariance and Riesz potentials define a natural bridge for encoded information that connects distinct geometric structures. The intrinsic character of the Heisenberg group makes it the natural playing field on which to explore the laws of symmetry and the interplay between analysis and geometry on a manifold.

In Situ and Step-Heating 40Ar/39Ar Dating of White Mica in Low-Temperature Shear Zones (Tenda Massif, Alpine Corsica, France).

In order to clarify the link between 40Ar/39Ar record in white mica and deformation, we performed in situ and bulkwise 40Ar/39Ar dating over the East Tenda Shear Zone (Tenda massif, Alpine Corsica). White micas from 11 samples were selected and extensively analyzed using in situ techniques across nested scales of strain‐intensity gradients developed at the expense of a late‐Variscan protolith. 40Ar/39Ar systematics are unaffected by inherited Ar and directly linked to deformation with little or no Ar lattice (volume) diffusion. Extensive sampling allows constraining the end of deformation related to burial and exhumation, respectively, at ~34 and ~22 Ma, bracketing the duration of regional extensional shear to ~12 Myr. Results also highlight a regional strain localization toward the upper contact of the unit with smaller‐scale localization in specific lithologies, notably meta‐aplites. Second‐order complications exist, such as local ill‐defined correlations between ages and finite‐strain microstructures. Thus, the use of a strain gradient as a proxy for strain localization in time is regionally valid but sometimes locally too complex to track or resolve strain partitioning/localization trends at the meter (outcrop) scale and below. Age mixing and incomplete isotopic homogenization by dissolution/precipitation are identified as the main causes of local discrepancies that complicate the link between age and microstructure and the derivation of strain localization rates. Tracking temporal trends in shear distribution across regional‐scale deformation gradients in such settings is possible but requires a multi‐scale approach as implemented here to reveal younging patterns associated to strain localization.

DEM simulations of tote blenders for enhanced axial mixing efficiency

The mixing performance of a multi-bladed tote blender is investigated using a graphics processing unit-based discrete element method program. The positioning, dimensions, and applicability of the baffles are systematically studied according to the axial mixing efficiency. The results indicate that the novel inclined multi-bladed baffles can break the symmetrical axial granular flow and introduce a more efficient convective flow into the granular mixing in the axial direction of the tote blender. Owing to the joint effects of convective mixing and asymmetrical granular flow, the axial mixing efficiency is increased by a factor of nearly 20. More importantly, the novel baffle placement approach exhibits excellent applicability to different operating conditions, particle shapes, and blender sizes. Additionally, the inclined baffles can prevent the segregation caused by shape discrepancies and improve the mixing homogeneity in the steady state. The novel baffle design is promising for applications in more complex industrial blenders for achieving a high axial mixing efficiency.