Densification Properties Research Articles

A supervised functional Bayesian inference model with transfer-learning for performance enhancement of monitoring target batches with limited data

To increase the monitoring performance of the batch process with serious nonlinearity, uneven-length, and limited-data issues, a supervised transfer-learning based functional Bayesian inference method is developed in this study. The raw uneven-length batch data are firstly transformed into functional data by choosing appropriate orthogonal wavelet basis functions (WBFs). Using the approximation coefficients representing the latent features that are inherent to the raw data, a Gaussian process model and a Bayesian inference method are applied based on the coefficients in each source batch process and the established models are transferred to enhance modeling performance for the target process with limited batches. In the proposed functional method, the unfolding operation is not needed for preprocessing, avoiding distortion of the raw data structure. With the compact support property of WBFs, within-batch detection can be implemented effectively to recognize faults earlier. The advantages of the proposed model are verified using a numerical case and an industrial polytetrafluoroethylene process.

An Experimental Study of Compaction and Strength of Stabilized Cohesive Soil by Stone Powder

The In this experimental study, natural stone powder was utilized to improve a cohesive soil’s compaction and strength properties. According to the significant availability of limestone in the globe, it has been chosen for the purpose of the study, in addition to considering the existing rock industry massive waste. Stone powder was used in percentages of 4, 8, 12, 16% replaced from the soil weight in dry state. Some of cohesive soil’s consistency, shear, and compaction properties were depicted after improvement. The outcomes yielded in significant amendments in the experimented geotechnical properties after stone powder addition considering 60 days curing period. Cohesion and friction angle were notably increased by 12% and 21% respectively. This study can provide an experimental basis for the stabilization mechanism of the fine-grained soil, and guidance for the better stabilization scenario by available cheap natural resources and waste.

Improving the compaction properties and shear resistance of a sand reinforced with COVID-19 waste mask fibers

Due to the COVID-19 pandemic, disposable face-masks were excessively used around the world, which led to severe environmental problems. The main purpose of this research is to test the possibility of reinforcing a sandy soil with mask fibers to reuse pandemic-generated waste materials. When testing the compaction properties, the sand was reinforced with a fiber content that increased from 0% to 0.5%, with successive small increments of 0.1%. An optimum content of 0.1% remarkably increased the maximum dry density of the soil and dropped its optimum moisture content. Add to that, it was noticed that 15 mm and rectangular chips were respectively the optimum fiber length and shape to maximize the improvement of the sand compaction properties. Regarding the shear strength, fiber contents of 0.1%, 0.25%, and 0.5% were adopted. The direct shear tests have shown that the highest enhancement was observed for an optimum fiber content of 0.25%. Similarly to compaction tests, 15 mm and rectangular chips were respectively the optimum fiber length and shape to extremely enhance the shear resistance of the tested sand.

Effect of particle packing structure on the elastic modulus of wet powder compacts analyzed by persistent homology

This study applies persistent homology (PH) to the structural analysis of wet powder compacts to clarify the effect of packing structure on the elastic modulus, and proposes an equation for the relationship between saturation and elastic modulus based on the index of structural homogeneity. The relationship between the saturation and the elastic modulus was experimentally obtained by compression tests of wet powder compacts. The elastic modulus decreased linearly with increasing saturation, but the slope was different depending on the packing structure of compacts which were made from high purity alumina with different particle size distributions. PH was applied to the packing structure of particles of different diameters calculated by DEM simulation to evaluate the packing structure. The features of each packing structure were extracted by PH, and the index of structural homogeneity was obtained. A new empirical equation is proposed which can predict the relationship between the elastic modulus and the saturation considering structural homogeneity, specific surface area, surface tension, and porosity as the main factors affecting the elastic modulus in the partially saturated state. These results indicate that PH analysis is effective to evaluate the packing structure and that this method may predict the mechanical properties of wet powder compacts.

Study on the Structure and Properties of SrTiO3 Modified K0.5Na0.5NbO3 lead-Free Ceramics with a Sintering Aid of NiO

In this experiment, a new piezoelectric ceramic system (1-x)K0.5Na0.5NbO3-xSrTiO3−0.4%molNiO (abbreviated as KNNST) with high properties and density was obtained by using K0.5Na0.5NbO3 (abbreviated as KNN) as matrix, adding new component SrTiO3 and sintering aid NiO, and adopting traditional solid-state sintering process at lower sintering temperature. XRD, SEM and other modern test analysis show that when a small amount of sintering aid NiO is added, KNNST ceramic samples with SrTiO3 doping in the range of 0 ≤ x ≤ 0.08 can form a single perovskite structure without any impurity phase. When 0.02 < x < 0.06, KNNST ceramics exist a polymorphic phase boundary (PPB) between orthorhombic and tetragonal phases, and thus excellent properties were obtained when x = 0.04, they are respectively d 33 = 287pC/N, k p = 48%, ε r = 1216, tanδ = 2.2%, T C = 373°C, P r = 26.5 μC cm−2, E C = 2.06 kV mm−1. This shows that by introducing new component and adding sintering aid, a new phase boundary can be constructed, a new solid solution ceramic can be formed, and the compactness and electrical properties of the KNNST ceramics can be improved. This provides an effective way to improve the properties of KNN based piezoelectric ceramics, and also provides hope for practical applications.

The Development of Advanced Mathematical Models to Predict Compaction Parameters of FineGrained Soils in Terms of Atterberg Limits

Compaction is an important engineering process that ensures the stability of soils by compressing them to a predefined strength. However, in most construction projects, particularly large-scale projects, achieving the appropriate compaction properties, such as optimum moisture content (OMC) and maximum dry density (MDD), it requires time and high cost. Predicting the compaction characteristics from the Atterberg limit, which involves simpler and faster testing techniques, becomes an important task in this scenario. The purpose of this study is to study the comparison of the multiple linear regression (MLR) method with the response surface method (RSM) and artificial neural network (ANN) to determine an accurate, efficient and simple technique to predict soil compaction parameters. For this research, 29 samples were subjected to a variety of laboratory testing. All of the parameters’ statistical relationships were analyzed. In this research, techniques are used, and the findings of these studies are discussed and analysed. To see the performance and accuracy of the model, the criteria for validation of the model used are based on the value of coefficient of determination (R2), absolute mean error (MAE), mean square error (MSE) and mean square root error (RMSE). A comparison with the test data revealed that the coefficient of determination (R2) of ANN model predictions was greater than those of other models. In addition, the findings indicate that the accuracy of ANN models are superior to the statistical models MLR and RSM.

Distinct types of crevasse splays formed in the area of Middle Miocene mires, central Poland: Insights from geological mapping and facies analysis

This paper focuses on subaerial- and subaqueous-type crevasse splays in the lignite-bearing Mid-Miocene succession near the town of Konin in central Poland. During the formation of these floodplain forms arose on the surface of highly compactable peat, then transformed into lignite, in territories of at least intermittently active tectonics. Hence, both of these major types of crevasse splays are consistently divided into deformed and undeformed subtypes in this paper. All these types and subtypes are found within the first mid-Polish lignite seam (MPLS-1), which is mined for electricity production in the study area. The numerous borehole data and ongoing exploitation of the MPLS-1 allow the geological mapping and detailed facies analyses of the crevasse-splay sediments to be conducted in most cases.The crevasse-splay sandbodies studied in the Tomisławice and Jóźwin IIB lignite opencasts are small as they cover an area of <0.075–0.63 km2. Their maximum length reaches up to 0.9 km, whilst their maximum thickness obtained from the borehole is 5.3 m, and ca. 1.4–3 m as observed in the field. These sandy deposits were accumulated during overbank flooding on the Mid-Miocene mire (backswamp) surface under subaerial and/or subaqueous conditions. In the latter case, ‘prograding splay deposits’ are typical of crevasse-splay microdeltas. Due to the tectonic activity and high compaction properties of peat/lignite, the interseam sands sometimes underwent both ductile and brittle deformation. This allowed subtypes of the crevasse splays that split the currently mined MPLS-1 to be distinguished. In addition to the cognitive value, a better knowledge of the crevasse-splay sediments, their spatial distribution, and deposition mechanisms can be of great use for lignite extraction planning and operations.

Portland cement clinkers turned into garnets by spark plasma sintering

The feasibility of sintering Portland cement clinker powders by Spark Plasma Sintering (SPS) has been studied. Different SPSed compacts have been successfully obtained by this technique. The compacts have been characterized by means of X-Ray Diffraction, InfraRed spectroscopy, Scanning Electron Microscopy, Raman Microscopy and Vickers hardness. It is worth noting the finding that slight mineralogical variations in the starting compositions may induce dramatic changes, both in the final mineralogical composition and in the morphology, which can affect the properties of the SPSed compacts. Thus, we find that SPS allows artificial garnets to be obtained in the laboratory by applying pressures as low as 50 MPa, while they are materials that would require much higher pressures in natural environments (2–10 GPa). According to the Selsing model, it has been calculated that the material itself acts as a pressure amplifier at the micrometric level by a factor of 40–200 times. A new model describing the formation of garnets considering the emergence of two transitory eutectic liquids has been explained to justify this phenomenon. This result opens the door to looking for compositions for specific applications with high added value in the field (i.e. high hardness), mainly in the manufacturing of high-pressure (GPa) phases by applying relatively low pressures (MPa).

Composition–structure–property relationships of transparent Ca–Al–Si–O–N oxynitride glasses: The roles of nitrogen and aluminum

AbstractWe explore the formation and composition–structure–property correlations of transparent Ca–Al–Si–O–N glasses, which were prepared by a standard melt‐quenching technique using AlN as the nitrogen source and incorporating up to 8 at.% of N. Their measured physical properties of density, molar volume, compactness, refractive index, and hardness—along with the Young, shear, and bulk elastic moduli—depended roughly linearly on the N content. These effects are attributed primarily to the improved glass‐network cross‐linking from N compared to O, rather than the formation of higher‐coordination AlO5and AlO6groups, where27Al magic‐angle‐spinning nuclear magnetic resonance experimentation revealed that aluminum is predominately present in tetrahedral coordination as AlO4units. Yet, several physical properties, such as the refractive index along with the bulk, shear, and Young's elastic moduli, increase concomitantly with the Al content of the glass. We discuss the incompletely understood mechanical–property boosting role of Al as observed both herein and in previous reports on oxynitride glasses, moreover suggesting glass‐composition domains that are likely to offer optimal mechanical properties.

Impact of drug loading on the compaction properties of itraconazole-PVPVA amorphous solid dispersions

The impact of drug loading on the compaction properties of itraconazole (ITZ)- poly(vinylpyrrolidone-co-vinyl-acetate) (PVPVA) amorphous solid dispersions (ASDs) was studied. Neat amorphous ITZ, amorphous PVPVA, and their ASDs from 20% to 80% ITZ loadings were prepared by spray drying. Physical characterization showed that all powders have comparable particle size and morphology. All samples were equilibrated under 33% RH prior to compaction studies using a compaction simulator. Tabletability and compactability profiles of the ASD powders differed significantly, while their compressibility was similar. At compaction pressures from 50 to 150 MPa, tensile strength of ASD compacts increased with the increase of ITZ loading, reaching to the maximum at 40–60% ITZ loadings and then decreased as ITZ loading further increased. However, at the compaction pressure of 200 MPa, a monotonic decrease of tensile strength with the increase of ITZ loading was observed. In addition, except for the ASD with 20% ITZ loading, the detrimental effect of compaction pressure on tensile strength was observed at pressures at or above 150 MPa. Overall, this work highlights the importance of evaluating the compaction properties of ASD intermediates prior to downstream tablet development, especially if a high drug loading ASD is desired.

The Use of Compaction Simulation as a Tool to Aid Successful Tablet Formulation

Early assessment of compaction properties of both APIs and formulations is an important consideration in early tablet development and can help to de-risk scale up from R&amp;amp;D to production scale. In this work, three model APIs and a tablet formulation were assessed using a compaction simulator. Compaction simulation was shown to be able to differentiate between the compaction properties of APIs and formulations and when combined with additional information on API properties (flowability, solubility) and tablet requirements (size, strength) can guide formulation strategy.&amp;nbsp;

Influence of environmental conditions and voltage application on the electromechanical performance of Nafion-Pt IPMC actuators

Ionic polymer–metal composites (IPMCs) are a class of ionic-type electroactive polymers which can be configured as capacitor actuators with very low voltage requirements (⩽5 V AC or DC). Their compact, portable, and lightweight properties, coupled with a biomimetic bending actuation response, makes them ideal for human–machine integrated technologies such as medical implants, active skins, and artificial muscles. Unfortunately, IPMC actuator’s hydration-related sensitivity inhibits practical application in industry and makes experimental research difficult. Therefore, this research sought to quantify the hydration-related parameters of IPMC actuators by applying a wide range of experimental tests to characterize the material’s hydration-dependent features. This included saturation, dielectric, and bending actuation measurements. The IPMC’s degree of saturation properties were classified to establish sample rehydration, preparation, and preservation techniques. IPMC electrical-solvent properties were measured to estimate IPMC actuation performance based on capacitance and dissipation measurements. Maximized actuation was identified for samples tested in 95% RH (i.e. percentage relative humidity). This condition produced an optimized displacement range and retained quality. Through statistical analysis, the work showed large electroactive performance variability (up to 50% deviation), which is a primary obstacle inhibiting this technology from practical application. Finally, an array of electrical field bias applications (i.e. cycled, constant, and post voltage removal monitoring) at intensities ranging from 0.75 to 1.2 V (direct current voltage) were used to quantify actuation rate, maximum displacement, as well as voltage application and removal back-relaxation behavior.

Properties of Compacts from Mixtures of Calcium Fluoride Micro- and Nanopowders

In this work, compacts from mechanical mixtures of CaF2 micron powder (MCP) with CaF2 nanopowder (NP) additives were produced, with mass ratios of the mixture components ranging from 10:0.125 to 10:1, respectively, using magnetic pulse (MP) and static pressing (SP) methods. The effects of pressure (Pp) and pressing temperature (Tp), concentration and phase composition of the additive on the density and color of compacts were studied, taking into account the properties of the initial components of the mixtures. The evolution of pulsed cathodoluminescence (PCL) spectra and photoluminescence (PL) of compacts from pure powders and their mixtures depending on Pp, Tp and characteristics of initial CaF2 NP was also studied. A new near-infrared (NIR) band associated with fluoride vacancies was discovered with a maximum at ~765 nm in PCL spectra of compacts produced by MP at a temperature of 425 °C. A blue band at 435 nm associated with impurity oxygen vacancies in the CaF2 lattice was found in PL spectra compacts of pure NP and powder mixtures. The density of compacts of pure NP and MCP reached 89% of the theoretical density, and the density of compacts of mixtures did not exceed 78%. The defective structure and phase composition of the CaF2 NP had a decisive effect on the luminescent properties of compacts from mixtures of micro- and nanopowders.

Influence of Graphene Sheets on Compaction and Sintering Properties of Nano-Zirconia Ceramics.

The use of a nanostructured graphene-zirconia composite will allow the development of new materials with improved performance properties and a high functionality. This work covers a stepwise study related to the creation of a nanostructured composite based on ZrO2 and graphene. A composite was prepared using two suspensions: nano-zirconia obtained by sol-gel synthesis and oxygen-free graphene obtained sonochemically. The morphology of oxygen-free graphene sheets, phase composition and the morphology of a zirconia powder, and the morphology of the synthesized composite were studied. The effect of the graphene sheets on the rheological and sintering properties of a nanostructured zirconia-based composite powder has been studied. It has been found that graphene sheets in a hybrid nanostructure make it difficult to press at the elastic deformation stage, and the composite passes into the plastic region at a lower pressure than a single nano-zirconia. A sintering mechanism was proposed for a composite with a graphene content of 0.635 wt%, in which graphene is an important factor affecting the process mechanism. It has been determined that the activation energy of the composite sintering is more than two times higher than for a single nano-zirconia. Apparently, due to the van der Waals interaction, the graphene sheets partially stabilize the zirconia and prevent the disordering of the surface monolayers of its nanocrystals and premelting prior to the sintering. This leads to an increase in the activation energy of the composite sintering, and its sintering occurs, according to a mixed mechanism, in which the grain boundary diffusion predominates, in contrast to the single nano-zirconia sintering, which occurs through a viscous flow.

Investigation of Soil Physiochemical Properties Effects on Soil Compaction for a Long Year Tilled Farmland

In many parts of the world, the earth has been heavily compacted as a result of large farm equipment. For soil compaction, the main constituent factors were soil physiochemical properties such as soil texture, moisture content, electrical conductivity, cation exchange capacity, total organic carbon, organic matter, total nitrogen, and soil pH directly and indirectly. This article addressed the causes and effects of soil compaction, operating parameters, and soil physicochemical properties in the Bishoftu long year tilled farmland of Ethiopia. For the experimental test, 5 different depths (5, 10, 15, 20, and 25 cm) and fifteen sample points were selected in 0.6 ha of 60 m by 100 m farmland for taking soil compaction data. Soil samples are taken from three depth ranges (0–10, 10–20, and 20–30 cm) from farmlands for investigation of soil physicochemical properties. The maximum and minimum values of the cone index of this study were 1918.133 kPa and 864.733 kPa, respectively, by taking the average of all sample points. The soil laboratory result shows that Bishoftu farmland soil is a mixture of loam, clay loam, and sandy clay loam with 47.33% of sand, 25.67% of clay, and 27% of silt. The maximum and minimum percentages of soil moisture values were 27.02 and 21.46 at 0–10 cm and 20–30 cm depth, respectively. Total organic carbon, organic matter, and total nitrogen exhibit positive relationships with depth and soil compaction. The correlation analysis indicates soil pH, electric conductivity, percentage of sand, cation exchange capacity, organic matter, and total nitrogen were among soil physiochemical parameters that are positively correlated with soil compaction. Furthermore, the percentage of clay, percentage of silt, and total organic carbon ( p ≤ 0.05 ) are negatively correlated with soil compaction in soil samples.

Effect of silica fume on the undrained strength parameters of dispersive

Dispersive soils are one of the problematic soils such as swelling and collapsible soils and they are common in many countries of the world. Due to dispersive soils, significant problems arise in road embankments and earth dams. Therefore, the use of such soils is possible with treatment. Silica fume (SF) as a waste material has been used in concrete production instead of partially cement, in the stabilization of expansive soils and in many civil engineering applications for different purposes. Within the scope of this study, to determine the dispersibility behavior of the soil sample, crumb test was performed. SF additive was used to improve the soil sample, which was determined to have high dispersibility. The compaction properties of the soil specimens mixed with SF in different proportions (0, 5, 10, 15, 20, 25 and 30%) were determined by the standard Proctor test. Crumb tests were performed to assess the dispersibility potential of the prepared specimens, and also unconsolidated and undrained (UU) triaxial tests were carried out to evaluate the strength parameters. UU experiments were performed under 20 kPa, 40 kPa and 60 kPa effective cell pressures on specimens cured for 1, 7 and 28 days because stabilization occurred at shallow depths in field applications. As a result, it was determined that the dispersibility feature of the soil sample was treated and the strength properties were improved depending on the SF content.

GLS methods for Stokes equations under boundary condition of friction type: formulation-analysis-numerical schemes and simulations

In this paper, we present in two and three dimensional space Galerkin least squares (GLS) methods allowing the use of equal order approximation for both the velocity and pressure modeling the Stokes equations under Tresca’s boundary condition. We propose and analyse two finite element formulations in bounded domains. Firstly, we construct the unique weak solution for each problem by using the method of regularization combined with the monotone operators theory and compactness properties. Secondly, we study the convergence of the finite element approximation by deriving a priori error estimate. Thirdly, we formulate three numerical algorithms namely; projection-like algorithm couple with Uzawa’s iteration, the alternative direction method of multiplier and an active set strategy. Finally some numerical experiments are performed to confirm the theoretical findings and the efficiency of the schemes formulated.

A probabilistic model for field density distribution of asphalt pavements

ABSTRACT The field density of as-constructed asphalt pavements usually exhibits considerable variability. Understanding and quantifying this variability is of crucial importance for building more reliable and durable pavements. This study investigates the probability distribution of the field density based on an analytical model of gyratory compaction. The model is derived from mass balance and the transition state theory for the process of aggregate rearrangement. Meanwhile, the variability in the compaction effort is also taken into account. The model is first calibrated by the laboratory gyratory compaction experiments, and is then used to predict the probability distribution of the field density, which is compared with field measurements. It is shown that the probabilistic model can capture the left-skewed and leptokurtic features of the field density distribution. The present model surpasses the commonly used Gaussian distribution for characterising the field density distribution. A parametric study is performed to investigate the effects of the compaction properties of mixture and field compaction effort on the probability distribution of the field density. The model can potentially be used to guide the asphalt mix design for achieving the desired field density.

Microstructure, Mechanical and Electrical Properties of Hybrid Copper Matrix Composites with Fe Microspheres and rGO Nanosheets.

Copper matrix composites have a wide application as magnetic conductive materials, electromagnetic materials, electrical discharge machining materials, etc. Such materials are expected to have a good combination of excellent electrical conductivity and good mechanical strength. In this work, micro/nano hybrid reinforcements with Fe microspheres and reduced graphene oxide (rGO) nanosheets were developed for copper matrix composites. The rGO/Fe/Cu powders were firstly wet-mixed and then densified by the vacuum hot-pressing sintering to obtain the bulk compacts. Microstructure, electrical conductivity and mechanical properties of such compacts were investigated. Microstructural result of as-sintered compacts shows that the Fe microspheres could distribute in the matrix uniformly, and rGO nanosheets exhibit both agglomerated and dispersed states. The grain size of Cu matrix decreased with the increase of the rGO content. Hardness, compression and tensile 0.2% yield strength of the as-sintered compacts were improved evidently by the addition of the hybrid Fe/rGO, comparing with pure Cu and single Fe-added composites. However, a lower electrical conductivity appeared in the more rGO-added composites, but still reached more than 33.0% international annealing copper standard (IACS). These performance change could be sought in the spatially geometrical distribution and characteristics of such micro/nano Fe/rGO hybrid addition, and the relevant mechanisms were discussed.

Geotechnical Review for Gypseous Soils: Properties and Stabilization

In many arid and semi-arid regions, collapsible soils are well-known to be problematic in nature and negatively affect the performance of engineering structures. Gypseous soil considers one of the well-known types of collapsible soil. It represents a real challenge to engineers due to different problems encountered by engineering projects implemented in this soil. The mineralogy, composition, and fabric of gypseous soil affect its ability to deform when subjected to wetting (due to changing the whole structure soil particles). Numerous studies considered the problems of gypseous soils and their treatment with different additives and using different methods. In this paper, the properties of gypsum (physical appearances, hardness, density, chemical structure), gypsum effect on soil properties (specific gravity, compaction properties, shear strength), main geotechnical properties of gypseous soils, their problems, and different important additives (traditional and non-traditional) and methods used in gypseous soils problems mitigation have been discussed. Gypsum is one of unpredictable materials that have different forms, low hardness, and low density. Gypsum is the main occurring source of sulphate in soils, it affects their geotechnical properties to different degrees depending on its content, the presence of the other salts (than gypsum), soil gradation and type, and organic matters. There is a critical gypsum content beyond which gypsum negatively affects the shear strength of soils, this content is (10-20)%. Finally, although there are many additives used in the treatment of gypsum soil, the use of some additives should be done with caution to avoid destructive results, especially with clay gypseous soil.