Volume Fraction Of Component Research Articles

An experimental and kinetic modeling study of the auto-ignition of natural gas blends containing C1–C7 alkanes

Ignition delay time measurements for multi-component natural gas mixtures were carried out using a rapid compression machine at conditions relevant to gas turbine operation, at equivalence ratios of 0.5–2.0 in ‘air’ in the temperature range 650–1050 K, at pressures of 10–30 bar. Natural gas mixtures comprising C1–C7n-alkanes with methane as the major component (volume fraction: 0.35–0.98) were considered. A design of experiments was employed to minimize the number of experiments needed to cover the wide range of pressures, temperatures and equivalence ratios. The new experimental data, together with available literature data, were used to develop and assess a comprehensive chemical kinetic model. Replacing 1.875% methane with 1.25% n-hexane and 0.625% n-heptane in a mixture containing C1–C5 components leads to a significant increase in a mixture's reactivity. The mixtures containing heavier hydrocarbons also tend to show a strong negative temperature coefficient and two-stage ignition behavior. Sensitivity analyses of the C1–C7 blends have been performed to highlight the key reactions controlling their ignition behavior.

Investigation of the Quality of the Mixture at the First Stage of Operation of a Gravitational Apparatus

The quality of the mixture obtained after the first stage of batch mixing of loose components in the preparation of a finished mixture with a ratio of 1:10 or more is assessed, according to the proposed method of three stages and the results of stochastic simulation of the process of mixing of loose materials in a gravitational apparatus during operation of drums with screw-wound brush elements installed above the trays and with inclined bumpers. The models of the formation of rarefied torches of two types of particles in two cases were employed: (1) after the interaction with the brush elements of the layers of dosage components coming from the drum–tray gap and (2) after the impact of the incoming torches on the bumper. For the first stage of mixing, dependences of the volume and weight fraction of the key component on the reflection angles are simulated with allowance for the physical mechanical properties of the materials and the design and regime parameters of the apparatus, based on the corresponding nonequilibrium differential distribution functions for the number of particles of each component in the angle of scattering from the brush elements (case 1) and the angle of reflection from the bumpers surface (case 2). Using the proposed recurrence relation for dosage materials, the coefficient of inhomogeneity of the mixture at the first stage of mixing particulate components is calculated with the focus on the most significant factors of a quality mixing: the angular speed of drum rotation ω; the degree of deformation of brush elements Δ (the ratio of their length to the height of the drum–tray gap); and the angle of inclination of bumpers to the horizon ψ1. Analysis of the theoretical and experimental results showed their satisfactory agreement and made it possible to reveal the most rational ranges of variation of the сhosen process parameters at the first mixing stage: ω = (45.5–47.2) s–1; Δ = (1.48–1.52); and ψ1 = (0.87–1.04) rad. These findings can be used in the development of the engineering methodology for calculating new gravity mixers.

All-Nanoporous Hybrid Membranes: Incorporating Zeolite Nanoparticles and Nanosheets with Zeolitic Imidazolate Framework Matrices.

Metal-organic framework (MOF) membranes have attractive molecular separation properties but require challenging thin-film deposition techniques on expensive/specialty supports to obtain high performance relative to conventional polymer membranes. We demonstrate and analyze in detail the new concept of all-nanoporous hybrid membranes (ANHMs), which combines two or more nanoporous materials of different morphologies into a single membrane without the use of any polymeric materials. This allows access to a previously inaccessible region of very high permeability and selectivity properties, a feature that enables ANHMs to show high performance even when fabricated with simple coating and solvent evaporation methods on low-cost supports. We synthesize several types of ANHMs that combine the MOF material ZIF-8 with the high-silica zeolite MFI (the latter being employed in both nanoparticle and nanosheet forms). We show that continuous ANHMs can be obtained with high (∼50%) volume fractions of both MOF and zeolite components. Analysis of the multilayer microstructures of these ANHMs by multiple techniques allows estimation of the propylene/propane separation properties of individual ANHM layers, providing initial insight into the dramatically increased permeability and selectivity observed in ANHMs in relation to single-phase nanoporous membranes.

Bidimensional lamellar assembly by coordination of peptidic homopolymers to platinum nanoparticles

A key challenge for designing hybrid materials is the development of chemical tools to control the organization of inorganic nanoobjects at low scales, from mesoscopic (~µm) to nanometric (~nm). So far, the most efficient strategy to align assemblies of nanoparticles consists in a bottom-up approach by decorating block copolymer lamellae with nanoobjects. This well accomplished procedure is nonetheless limited by the thermodynamic constraints that govern copolymer assembly, the entropy of mixing as described by the Flory–Huggins solution theory supplemented by the critical influence of the volume fraction of the block components. Here we show that a completely different approach can lead to tunable 2D lamellar organization of nanoparticles with homopolymers only, on condition that few elementary rules are respected: 1) the polymer spontaneously allows a structural preorganization, 2) the polymer owns functional groups that interact with the nanoparticle surface, 3) the nanoparticles show a surface accessible for coordination.

Microstructure–Property Correlation in High-Strength Formable Steel with Varying Nb-Si Content

High-strength formable quality (HSFQ) steel grades, steel A (0.038Nb, 0.031Si), steel B (0.034 Nb, 0.27Si), and steel C (0.044Nb, 0.26Si), with varying Nb and Si content has been investigated. The microstructure, texture, precipitation, mechanical properties and corrosion behavior of these steel grades have been explored. Very fine grain size in the range of 2.7-3.6 µm was obtained in all these steel grades through controlled hot rolling. However, a significant variation in the crystallographic texture and precipitation behavior in these steels was observed. A higher volume fraction of γ-fiber texture components and uniformly distributed fine Nb(C, N) precipitates were obtained in steel B as compared to steel A and C. This resulted in better properties in steel B with relatively high PSE (product of strength–elongation), high uniform elongation, and high hole expansion ratio. The corrosion properties of the steels were also evaluated, and steel B showed better corrosion resistance among the three grades. Considering the overall performance and properties of these steel grades, steel B with an optimum Nb and Si content is found to have better property and performance among the three grades.

Stress relaxation in symmetric ring-linear polymer blends at low ring fractions.

We combine linear viscoelastic measurements and modelling in order to explore the dynamics of blends of the same-molecular-weight ring and linear polymers in the regime of the low volume fraction (0.3 or lower) of the ring component. The stress relaxation modulus is affected by the constraint release (CR) of both rings and linear components due to the motion of linear chains. We develop a CR-based model of ring-linear blends that predicts the stress relaxation function in the low fraction regime of ring component in excellent agreement with experiments. Rings trapped by their entanglements with linear chains can only relax by linear-chain-induced constraint release, resulting in much slower relaxation of rings than of linear chains. The relative viscosity of the blend with respect to the linear melt viscosity η L at ring overlap volume fraction increases proportionally to the square root of ring molecular weight . Our experimental results clearly demonstrate that it is possible to enhance the viscosity and simultaneously the structural relaxation time of linear polymer melts by adding a small fraction of ring polymers. These results not only provide fundamental insights into the physics of the CR process but also suggest ways to fine-tune the flow properties of linear polymers by means of adding rings.

Production of hydrogen-rich gas from waste rigid polyurethane foam via catalytic steam gasification.

Catalytic steam gasification of waste rigid polyurethane foam, in the fixed-bed reactor, was performed to produce hydrogen-rich gas. The influence of nine kinds of additives on the yield of products (gaseous, solid and liquid product) and the volume fraction of hydrogen was investigated. Among the additives, calcium carbonate, as the catalyst, could effectively enhance the gas yield and the volume fraction of hydrogen. A three-factor three-level completely randomised factorial (3 × 3 × 3) design, with calcium carbonate as the catalyst, was applied to investigate the influence of experimental conditions (temperature, steam flowrate and catalyst dosage) on the volume fraction of gaseous product components. The data were processed with SPSS statistical software. The result showed that the main effects of one variable, the interactive effects between two factors and the interactive effects among three factors all have statistical high significance. The best catalysed process is realised when calcium carbonate is the catalyst, gasification temperature is 1100°C, steam flowrate is 0.7 kg h-1, catalyst dosage is 10 wt% of waste rigid polyurethane foam. Under this condition, the volume fraction of hydrogen reaches up to 79.85%.

Effect of the Phase Composition and the Microstructure on the Microhardness of As-Cast Cu–Ce–La Alloys

The Cu–Ce–La system is of interest for the production of both rare-earth-added bronzes and amorphous alloys. In this work, we investigate the phase composition, the microstructure, and the microhardness of 13 as-cast Cu–Ce–La samples corresponding to the copper angle of the Cu–Ce–La phase diagram. The experimental samples are studied by optical microscopy, scanning electron microscopy, electron microprobe analysis, atomic emission analysis with inductively coupled plasma, X-ray diffraction, and differential thermal analysis. The Vickers microhardnesses of the samples are measured. The microstructure of the samples is characterized by the presence of a eutectic, which is observed at Cu-based solid-solution grain boundaries and, according to electron microprobe analysis data, contains copper, lanthanum, and cerium. The X-ray diffraction analysis data also indicate the presence of the Cu6Ce and Cu6La compounds along with the Cu-based solid solution. The volume fraction of the eutectic component is determined (it is equal to the fraction of the area corresponding to the eutectic in the section of a sample). As the Ce and La contents increase, the fraction of the eutectic component increases. According to thermal analysis data, the ternary eutectic equilibrium takes place along with the binary eutectic equilibria. Significant correlation between the fraction of eutectic component in the microstructure and the hardness of the experimental samples is shown to exist. As the fraction of eutectic in the microstructure increases, microhardness HV also increases. The obtained results are of interest for materials scientists for analyzing the effect of rare-earth metal additions on the phase composition, the microstructure, and the mechanical characteristics of copper alloys.

Microstructure and Texture Evolution with Relation to Mechanical Properties of Compared Symmetrically and Asymmetrically Cold Rolled Aluminum Alloy

The impact of asymmetric cold rolling was quantitatively assessed for an industrial aluminum alloy AA 5454. The asymmetric rolling resulted in lower rolling forces and higher strains compared to conventional symmetric rolling. In order to demonstrate the positive effect on the mechanical properties with asymmetric rolling, tensile tests, plastic-strain-ratio tests and hardness measurements were conducted. The improvements to the microstructure and the texture were observed with a light and scanning electron microscope; the latter making use of electron-backscatter diffraction. The result of the asymmetric rolling was a much lower planar anisotropy and a more homogeneous metal sheet with finer grains after annealing to the soft condition. The increased isotropy of the deformed and annealed aluminum sheet is a product of the texture heterogeneity and reduced volume fractions of separate texture components.

Magnetoelectric Composites: Modeling and Application

The progress in electronic technology is directly coupled with the advances made in materials science. Within the broad class of materials available today, functional materials provide unique opportunity for developing novel components and devices as their physical and chemical properties. A combination of ferromagnetic and ferroelectric materials provides a new class of functional materials, termed as magnetoelectrics. An overview of modern magnetoelectric composites and examples of the design of electronic devices based on them are presented. The feature of these materials is that their parameters changes under the influence of an external magnetic and electric fields. The behavior of magnetoelectric composites in the wide frequency range is considered. Modeling of ME composites at low frequencies and in the field of electromechanical, ferromagnetic and magnetoacoustic resonances has shown that they can be effectively used to design various electronic devices in a wide frequency range. Nomographs method which can be used to plot the ME parameters versus initial material parameters and component volume fractions is presented. Nomographs can be used for a quick test of ME composites for applications where an approximate answer is appropriate and useful. Examples of ME composites application such as: magnetic field sensors, current sensors, microwave phase shifters, filters, attenuators, isolators are presented.

Особенности формирования высококоэрцитивной структуры сплавов (Sm,Zr)(Со,Cu,Fe)z при варьировании соотношения (4f-,4d-)/(3d-) элементов

Processes of the formation of high-coercivity state of Sm0.85Zr0.15(Co0.702Cu0.088Fe0.210)z alloys with different z = 6.0, 6.5 and 6.8, which is the value characterized the relationship of (4f-,4d-)/(3d-) elements in these alloys, are studied. It is shown the interrelation of the chemical composition of samples and their microstructure with the coercive force formed in the course of isothermal tempering and tempering during slow cooling (or stepped tempering). The interrelation of the high-coercivity state of the alloys and quantitative ratio (volume fractions) of the main structural components based on the 2:17R and 1:5H phases is discussed. It is shown that the cellular morphology of the alloy, which corresponds to the high-coercivity state, forms during isothermal tempering, whereas the final phase compositions of the main structural components form in the temperature range from the isothermal aging temperature to 400 °С during stepped (slow) cooling or upon quenching. The magnetic properties of sample in the high-coercivity state are determined by the degree of completeness of phase transformations of the main structural components; this directly depends on their quantitative relationships and the relationship of the (4f-,4d-)/(3d-) elements, i.e., on the z value in the alloy formula (Sm,Zr)(Со,Cu,Fe)z.

Anisotropic complex electrical conductivity of black shale and mudstone from the Moffat Shale Group (Ireland)

ABSTRACTThe geological setting in the north of Ireland, especially concerning the origin of the Moffat Shale Group, has long been under discussion. Within the Tellus Programme of the Geological Survey Ireland, airborne electromagnetic measurements revealed high‐conductivity anomalies that have been interpreted as the response of a black shale. In order to petrophysically characterize the Moffat Shale, a laboratory study using material from two shallow boreholes was carried out. The study focuses on spectral induced polarization measurements on 23 oriented samples in the frequency range from 10−4 to 105 Hz.The sample material can be categorized into two groups. A mudstone‐like rock type shows weakly frequency‐dependent, porosity‐driven conductivities with a strong anisotropy. On the other hand, black shale samples are characterized by moderately anisotropic but strong polarization effects especially at low frequencies and a strong conductivity increase towards higher frequencies. The polarization in the black shale is controlled by the texture and volume fraction of the polarizable components. The spectral induced polarization data are processed by means of a Debye decomposition approach. The anisotropy of the complex electrical conductivity is determined by utilizing the foliation dip angle and assuming tilted transverse isotropic conditions. The relevance of the laboratory findings for airborne electromagnetic surveys is addressed with a synthetic one‐dimensional modelling study.

Anomalous concentration dependence of the thermal conductivity of refractory sintered binary nano-composites TiN-ALN and ZrC-ZrB2

An abnormal concentration dependence of the thermal conductivity of nanocomposites Titanium Nitride-Aluminum Nitride and zirconium carbide-zirconium diboride has been experimentally established from the volume fraction of components. An explanation of the nature of the anomalous dependence and a technique for an approximate estimation of the dependence of the thermal conductivity of a nanocomposite on the volume fraction of components are proposed. Oxygen-free refractory compounds - covalent and metal-like active investigated in the development of new ceramic materials used for achieving higher physical and mechanical characteristics as well as for use in extreme conditions in mechanical engineering, nuclear engineering, aviation, special equipment. The development of technology is constantly stimulates the creation of new materials, which must manifest a complex of properties rarely show by one substance, such decisions cannot find the formation of composite (hetero) materials. In the case of eutectic systems with diffusive non-interacting refractory components, used for the synthesis of composite ceramic materials in a highly thermodynamic state, the possibility of co-building a new group of ceramics with interphase boundary (of eutectics “coarse conglomerate”) with anomalous concentration dependences of the physical and mechanical characteristics of composite materials (flexural strength and modulus of elasticity, super plasticity – elongation more than 500%, tensile, strength and fracture toughness) and thermal properties (thermal conductivity and thermal diffusivity) [1-3].

Effect of Biodiesel Mixture Derived from Waste Frying-Corn, Frying-Canola-Corn and Canola-Corn Cooking Oils with Various ‎Ages on Physicochemical Properties

Waste frying, corn and canola cooking oil biodiesels were produced through the transesterification ‎process and their properties were measured. Three different mixtures of biodiesel with the same blending ratio, namely, WCME1 (frying-corn biodiesel), WCME2 (frying-canola-corn biodiesel) and WCME3 (canola-corn biodiesel), were prepared. The effect ‎of ‎blending ‎biodiesel with various ages ‎‎(zero months (WCME3), eight months (WCME1), and 30 months (WCME2)) on kinematic ‎viscosity and‎ density was investigated under varying temperature and volume fraction. It was found that the kinematic viscosity of WCME2 remained within the ranges listed in ASTM D445 (‎1.9–6.0‎ mm2/s) and EN-14214‎ (‎3.5–5.0‎ mm2/s) at 30 months. It was also observed that both viscosity and density decreased as the temperature increased for each fuel sample. In order to improve the cold flow properties of the samples, the Computer-Aided ‎Cooling Curve Analysis (CACCA) technique was used to explore the crystallization/melting ‎profiles of ‎pure ‎methyl biodiesel as ‎well their blends. The results show that pure WCME2 has the lowest cold flow properties compared to other samples. Furthermore, 10 ‎correlations ‎were developed, tested and compared with generalized ‎correlations for the ‎estimation of the ‎viscosity and densities of pure biodiesels and their ‎blends. These equations depend on the temperature and volume fraction of pure components as well as the properties of the fuel.

Multiscale simulation of elastic modulus of rice stem

The objective was to obtain a quantitative relationship between the multiscale structural parameters and the elastic modulus of rice stem. Anisotropic elastic properties of rice stem were calculated via multiscale simulation. The elastic constants of the sub-layers of cell wall were calculated by the Halpin-Tsai equations and the rule of mixtures. Cellular structure of stem cross section was reconstructed via a skeletonisation method and used to create the finite element models. The influence of multiscale structural parameters, including the volume fractions of skin and vascular bundle, the cell wall thickness of different types of cells, the volume fraction and stiffness of compound composition, the volume fraction of S2 layer and the microfibril angle (MFA) in the layer, on the overall stiffness of rice stem was determined. Numerical results showed that if the volume fraction and stiffness of each cell wall component are assumed to be constant, increasing the volume fraction of the mechanical tissue layer, thickening the fibre cell wall and decreasing the MFA in S2 layer are the most effective ways to increase the longitudinal tensile modulus of rice stem. Changing the cell wall thickness and the volume fraction of vascular bundle is useful for controlling the tangential modulus. However, more effective is to change the cell wall thickness of parenchyma cell and the volume fraction of the vascular bundle for controlling the radial tensile modulus of rice stem.

Effects of deformation conditions on the microstructure, texture and mechanical properties of Ti6Al4V alloy

The evolution of microstructure and texture of Ti6Al4V alloy developed by cold rolled followed by annealed treatment at a thickness reduction ratio of 15%–70% were investigated by scanning electron microscopy and x-ray bulk texture measurement technique. It was found that the grains were severely broken up and elongated by cold rolling, and the degree of the mechanical anisotropy of the Ti6Al4V alloy was increased. For the cold-rolled Ti6Al4V alloy, recovery and recrystallization occurred during annealed treatment under 840 °C for 40 min. The thickness reduction ratio of 10% and 30% of the cold-rolled sheets only partially recrystallized.occurred partial recrystallization. When the thickness reduction ratio reaches 50%, the deformation band structure disappears. Compared to the cold rolled Ti6Al4V alloy, the mechanical anisotropy of the annealed Ti6Al4V alloy was weaker, mainly related to the texture components. The (0001) and components dominate the texture of the cold rolled Ti6Al4V alloy. Among them, and texture components inherit the original microstructure, and the intensity of that was increased with thickness reduction ratio increased. However, the intensity and volume fraction of the texture components rapidly increased and the intensity of the texture and (0001) components were weakened by the annealed treatment. During the annealing treatment, the texture component orientation is gradually strengthened by consuming other scatted orientations. In addition, it can be found that an increase in the intensity and volume fraction of texture component has a positive effect on improving the mechanical anisotropy of the Ti6Al4V alloy.

Toward Image Data-Driven Predictive Modeling for Guiding Thermal Ablative Therapy.

Accurate prospective modeling of microwave ablation (MWA) procedures can provide powerful planning and navigational information to physicians. However, patient-specific tissue properties are generally unavailable and can vary based on factors such as relative perfusion and state of disease. Therefore, a need exists for modeling frameworks that account for variations in tissue properties. In this study, we establish an inverse modeling approach to reconstruct a set of tissue properties that best fit the model-predicted and observed ablation zone extents in a series of phantoms of varying fat content. We then create a model of these tissue properties as a function of fat content and perform a comprehensive leave-one-out evaluation of the predictive property model. Furthermore, we validate the inverse-model predictions in a separate series of phantoms that include co-recorded temperature data. This model-based approach yielded thermal profiles in close agreement with experimental measurements in the series of validation phantoms (average root-mean-square error of 4.8°C). The model-predicted ablation zones showed compelling overlap with observed ablations in both the series of validation phantoms (93.4 ± 2.2%) and the leave-one-out cross validation study (86.6 ± 5.3%). These results demonstrate an average improvement of 17.3% in predicted ablation zone overlap when comparing the presented property-model to properties derived from phantom component volume fractions. These results demonstrate accurate model-predicted ablation estimates based on image-driven determination of tissue properties. The work demonstrates, as a proof-of-concept, that physical modeling parameters can be linked with quantitative medical imaging to improve the utility of predictive procedural modeling for MWA.

Automation in volume fraction of binary phase components

The automation in volume fraction of binary phase components finds a vital role in many chemical and open channel flow passages. In this experimental work, the dissolved air sensor is employed to determine the volume of air in water automatically. The air water mixture is subjected to uniform flow conditions and the air is made to penetrate in water at different elevations and the percentage volume of air is measured. This paper describes the experimental method to measure the volume of air in water and the corresponding results are highlighted.

Evaluation of Volume Fraction of Austenite in Austempering Process of Austempered Ductile Iron

In the present work, an evaluation of the volume fraction of austenite in austempered ductile iron (ADI) is presented by means of three different methods. Experimental tests were conducted on ADI samples after different austempering conditions and contained different volume fractions of the phase components in the metallic matrix (ferrite plates + austenite). A comparison of the volume fraction of austenite was carried out by metallographic magnetic methods using a variable field, as well as X-ray quantitative phase analysis. The main purpose of this work is to show the effectiveness of the proposed magnetic method for estimating the volume fraction of austenite in ADI cast iron. It is evident that the new method in which variable magnetic fields are used to quantify the phase composition exhibits very high accuracy within the second stage of the austempering transformation, in which the metallic matrix consists of ferrite plates and high-carbon austenite. Finally, this research shows that within the first and third stages the estimation of the volume fraction of the austenite is hampered by errors resulting from the presence of martensite (first stage) and carbide phases (third stage).

Photoluminescence polarization and refractive index anisotropy of porous silicon nanocrystals arrays

In this work, the simple way to form oriented arrays of silicon nanocrystals in a dielectric matrix was suggested. Porous silicon nanostructures obtained on the substrates with the [100] and [111] crystallographic orientations were separated from the silicon substrate using epoxy resin. Systems of the porous silicon nanoparticles were characterized by scanning electron microscopy, atomic-force microscopy, ellipsometry and luminescent spectroscopy. It is shown, that the use of epoxy resin suggests the preservation of the silicon nanostructures orientation after separation from the substrate. Based on the Bruggeman effective medium approximation, volume fractions of components of obtained nanosystems were determined for spherical and cylindrical shape of the porous silicon nanoparticles. The influence of the nanostructures orientation on optical and photoluminescent properties of the obtained nanosystems was studied. It is found that the photoluminescent polarization in silicon nanosystems is consistent with the anisotropy of their complex refractive index. Both phenomena originate from the morphological anisotropy of porous silicon nanocrystals.