Differential Distribution Curves Research Articles

Impact of Lime Saturation Factor on Alite-Ye'Elimite Cement Synthesis and Hydration.

Alite(C3S)-Ye'elimite(C4A3$) cement is a high cementitious material that incorporates a precise proportion of ye'elimite into the ordinary Portland cement. The synthesis and hydration behavior of Alite-Ye'elimite clinker with different lime saturation factors were investigated. The clinkers were synthesized using a secondary thermal treatment process, and their compositions were characterized. The hydrated pastes were analyzed for their hydration products, pore structure, mechanical strength, and microstructure. The clinkers and hydration products were characterized using XRD, TG-DSC, SEM, and MIP analysis. The results showed that the Alite-Ye'elimite cement clinker with a lime saturation factor (KH) of 0.93, prepared through secondary heat treatment, contained 64.88% C3S and 2.06% C4A3$. At this composition, the Alite-Ye'elimite cement clinker demonstrated the highest 28-day strength. The addition of SO3 to the clinkers decreased the content of tricalcium aluminate (C3A) and the ratio of Alite/Belite (C3S/C2S), resulting in a preference for belite formation. The pore structure of the hydrated pastes was also investigated, revealing a distribution of pore sizes ranging from 0.01 to 10 μm, with two peaks on each differential distribution curve corresponding to micron and sub-micron pores. The pore volume decreased from 0.22 ± 0.03 to 0.15 ± 0.18 cm3 g-1, and the main peak of pore distribution shifted towards smaller sizes with increasing hydration time.

Effect of propeller use on residence time distribution (rtd) in single-screw cam-flow rice semolina extrusion

The influence of the speed of the feeding (Nf) and main (Nw) screw, the moisture content of the material (W) and the temperature of the die (Tm) on the average residence time (t) and the Peclet number (Pe) in single-screw extrusion of rice semolina using a propeller were investigated. A computer system with a camera was used to continuously read the colorant saturation as a tracer pulsed into the feed zone of the extruder. The differential distribution curves of dwell times were constructed. The responce surface methodology with an orthogonal central compositional plan was used. Regression equations were obtained describing the influence of the selected independent variables on the average residence time (t) and the Peclet number (Pe). It has been found that the use of a propeller increases the mixing capability of the extruder and brings it closer to the ideal mixer.

Differential Settlement of Track Foundations Identification Based on GRU Neural Network

The timely identification of differential settlement of track foundations is of great significance for the safety of train operation and the maintenance of track structures. However, traditional monitoring techniques cannot meet the requirements of efficient, real-time, and automatic monitoring of track foundation settlement. In order to solve these problems, a real-time identification method based on a gated recurrent unit (GRU) neural network is proposed for the differential settlement of track foundations monitoring. According to parameter sensitivity analysis, the vertical acceleration of the vehicle is selected as the known data fed into the GRU network for differential settlement identification. Then the GRU network is employed to establish the nonlinear relationship between the vertical acceleration of the vehicle and the differential settlement of the track foundation. The results indicate that the longitudinal continuous differential settlement distribution curve of track foundations could be accurately identified with GRU neural network through the real-time vibration response of the vehicle–track. The current method may provide a new means for the real-time and efficient identification of the differential settlement of track foundations.

Granulometric composition of the finite moraine ridge soils of the Upper Volga postglacial region (East European plain, Tver region)

At the experimental field of VNIIMZ (Tver region, village Emmauss) laid a series of 8 soil sections. The first three sections of the southern slope are confined to the transit-accumulative, transit and eluvial-transit microlandscape with a complex of gleevate and gleev soils, which changes to an eluvial-accumulative flat-topped section and similar microlandscapes of the northern slope with slightly bent and gleevate sod-podzolic light loamy soils. In samples taken every 10 cm, the particle size distribution of soils was determined by laser diffraction and sieve (>0.25 mm) methods. The differential distribution curves of soil particles are dominated by fractions of fine sand with a maximum content of diameters of 100–150 µm and silt (1–50 µm). Three granulometrically homogeneous layers are distinguished in the soil profile: the upper one with an arable horizon (0–40 cm), medium (up to 70–80 cm) and super-moraine (up to 120 cm). In the middle part of the soil profile of the northern slope, silty fractions prevail; and in the soils of the southern part of the landscape, a relatively high content of the sandy fraction is observed (the fraction of fine sand, 50–250 µm, dominates, and followed by the coarse silt fraction, 10–50 µm), which, apparently associated with the historical processes of profiles development on binary deposits, erosion, and, possibly, with modern agrotechnological processes.

METHODOLOGICAL BASES FOR DESIGNING DOUBLE-CIRCUIT CLOSED AIR PURIFICATION SYSTEMS

. The article considers the main methodological principles of designing closed double-circuit systems for air purification from polydisperse dust. This cleaning system has a significant advantage compared to its direct-flow counterparts, namely, it allows avoiding emissions of dust not captured in the cleaning apparatus into the atmosphere. This, predominantly fine-grained dust, is captured by repeatedly passing the flow through the catcher of the circulation circuit. That is, the avoidance of environmental pollution is achieved using a new scheme for the movement of a dusty gas stream to be cleaned. The introduction of an innovative flow scheme does not allow the use of traditional calculation methods; therefore, the purpose of the article is to formulate the main methodological approaches to the design of twoloop closed treatment systems. It is shown that the design of a purification system should consist of two main stages. The first is the calculation of the performance indicators of the system elements. It is based on data on the fractional composition of dust (differential distribution curve) and the characteristics of the trapping apparatus and is carried out for the main operating mode of the system (cleaning mode) and the final one (run-out mode). The proposed calculation method, unlike all existing ones, allows obtaining the value of cleaning indicators in dynamics. The second is the hydraulic calculation of the system, consisting of the main and circulation circuits. The calculation is proposed to be carried out by compiling the power balances of each circuit separately and, due to this, it is reasonable to select standard injection equipment for them. The calculation is based on hydraulic indicators, which are determined either by generally accepted hydraulic ratios (reference data), or by the graphs obtained in the course of research and given in the article.

A new method for threshold determination of gray image

The determination of the gray threshold is crucial for the quantitative characterization of digital images. In this study, a new algorithm is proposed to determine the optimal image segmentation threshold. This algorithm is based on a combined analysis of the gray distribution curve and its second differential distribution curve of the digital image. Then, the feasibility and accuracy of the Liu–Cao algorithm are compared with the other 16 algorithms and verified by mercury injection method (MIP) results. Results show that the proposed segmentation threshold algorithm can effectively segment the digital images obtained by various imaging techniques (SEM, CT, FIB/SEM, etc.) and can accurately extract the pore (crack) structures from the image. Image filtering has a certain influence on the gray threshold determination and quantitative characterization, and the impact depends on the quality of the original image. This algorithm can be easily understood and mastered by the researchers and can be widely used in geotechnical and geological areas.

Structure and properties of corrosion-resistant steel obtained by selective laser melting

The objects of study were stainless steel powder 12Kh18N10T of the 20–63 μm fraction and experimental samples obtained on the basis of it by selective laser melting (SLM). The powder was obtained by spraying with argon at a temperature of 1640 °C and a pressure of 27 bar. The particles have the dendritic-cellular structure, with a decrease in their size (<35 μm), the cellular structure prevails, and the dendritic one almost disappears. The distinctive particle size is d50 = 37 μm, d100 = 67 μm. The differential distribution curve is close to the Gaussian form, and asymmetry is associated with satellite and the presence of a small number of particles less than 20 microns in size. The fluidity of the powder was 3,27 g/s, and the bulk density was 4,41 g/cm3. The density of the 12Kh18N10T steel samples grown at the Concept Laser M2 facility with a laser power of 180 W and a speed of 700 mm/s averaged 7,89 g/cm3. Since the density of compact steel is 7,95 g/cm3, the obtained material has enough high density. The microstructure of the 12Kh18N10T sample was described by continuity, the absence of pores and cracks. It was a solid solution of austenite. The average size of coherent scattering regions in the grain volume was 19 nm. The observed arcuate boundaries of parallel semicircular tracks are due to heat removal during crystallization through SLM. The elongated crystallites in the tracks are oriented inward from this boundary. The microhardness of the samples in the transverse plane of the thin section is higher than the microhardness of the planar plane. But the microhardness of the samples obtained from the powder by the SLM is higher than that of the standard compact alloy. Tensile strength and elongation are 651 MPa and 47 %, respectively. The increase in strength is probably due to the grinding of structural parameters in SLM. The fracture surface of the samples is characterized by a pronounced viscous type.

Dependence of Capillary Properties of Contemporary Clinker Bricks on Their Microstructure

Contemporary clinker bricks are applied for outer layers of walls built from other materials and walls which should have high durability and aesthetic qualities. The intended effect depends not only on the mortar applied but also on clinker properties. Traditional macroscopic tests do not allow to predict clinker behaviour in contact with mortars and external environment. The basic information for this issue is open porosity of material. It defines the material ability to absorb liquids: rain water (through the face wall surface) and grout from mortar (through base surface). The main capillary flow goes on in pores with diameters from 300 to 3000nm. It is possible to define pore distribution and their size using the Mercury Intrusion Porosimetry method. The aim of these research is evaluation of clinker brick capillary properties (initial water absorption and capillary rate) and analysis of differences in microstructure of the face and base wall of a product. Detailed results allowed to show pore distribution in function of their diameters and definition of pore amount responsible for capillary flow. Based on relation between volume function differential and pore diameter, a differential distribution curve was obtained which helped to determine the dominant diameters. The results obtained let us state that face wall of bricks was characterized with the lowest material density and open porosity. In this layer (most burnt) part of pores could be closed by locally appearing liquid phase during brick burning. Thus density is lower comparing to other part of the product.

Investigation of properties of protein-mineral prophylactic supplements

It was conducted an analysis of functional and technological properties of protein-mineral supplements, such as iodine-protein, protein-mineral and «SYVOSELEN PLUS» supplement used as a prophylactic measure for a balanced personal diet by essential nutrients. Investigations were conducted in liquids with different polarity (water, oil and water-alcohol solution) and on samples in the dry state. Differential diameter distribution curves of the samples were obtained by dispersion analysis. Spin-spin relaxation times for different solutions of technological supplements were obtained using nuclear magnetic resonance spectrometer. Analysis and correlation of the results obtained by these methods were conducted. These physical properties of the powders are the basis of scientific justification for using protein-mineral supplements in the technology of prophylactic food.

Investigation of pore structure and fractal characteristics of the Lower Silurian Longmaxi shales in western Hunan and Hubei Provinces in China

The pore structure characteristics of the Lower Silurian Longmaxi Formation shales collected from western Hunan and Hubei were investigated using high-pressure mercury injection and low-temperature N2 adsorption/desorption experiments. Total organic carbon values, thermal maturity values and mineralogical compositions were also obtained by relevant experimental methods. The TOC value varies from 0.71% to 4.75%, with a mean value of 2.58%, and their thermal maturities have reached the over-mature stage and dry gas generation window. Quartz and clay minerals are the major mineral compositions in the samples. In contrast to previous studies of other shales (Chalmers and Bustin, 2008; Han et al., 2013; Wang et al., 2013), there are no carbonates in the shale samples of this area. Due to their biogenic source, quartz content is positively correlated with TOC values. Pore size distributions obtained from mercury injection experiments were divided into three groups. Samples with higher TOC content always have smaller dominant pore sizes, and the pore sizes of samples with higher clay mineral content and lower TOC values may be larger, with a major peak between 30 nm and 1 μm. Through analyzing the N2 adsorption and desorption isotherms, we found that the morphology of pores in the shales rich in organic matter is narrow neck and wide body, and that of those rich in clay minerals is flat-shaped. BJH and DFT models were used to derive pore size distributions using N2 adsorption data, and both are representative. The differential distribution curves of pore volumes and surface areas show that all shale samples' dominant pore sizes are within the range of micropores and mesopores, and they are the major contributors to pore surface areas, while mesopores and macropores make more significant contributions to pore volumes. The specific surface area calculated by the BET method ranges from 6.12 to 28.42 m2/g, with an average value of 16.14 m2/g, and the total pore volume varies from 0.0105 to 0.0338 cm3/g, with a mean value of 0.0213 cm3/g. The correlational analysis between pore structure parameters and TOC value, quartz and clay mineral content indicates that organic matter and quartz are positively associated with the micropores and fine mesopores, though larger pores can also exist in organic matter, and clay minerals play an important role in mesopores and macropores generation. Due to the infeasibility of using mercury porosimetry data to obtain fractal dimensions, Dn calculated from N2 adsorption data are used, its value ranges from 2.6353 to 2.7694, with an average value of 2.7284. As we know, the more micropores contained in the shale, the more complex the pore structure will be, and as a result, the fractal dimension will be larger. Therefore, organic matter and quartz positively influence fractal dimension, and there is a negative relationship between clay mineral content and fractal dimension.

Research on Determination for Food-Related Polystyrene Doped with Recycled Plastic by GPC

Polystyrene (PS) had wide range of applications in food packaging field. Mechanical recycling of PS was simulated by multiple extrusions to assess the behavior of physical degradation. The molecular weight and the molecular weight distribution of PS with different extrusion cycles were investigated by gel permeation chromatography (GPC). Experimental results show that the differential and cumulative distribution curves of PS shift to smaller values with the number of extrusions cycled increasing. The Mn and Mw of PS decrease. However, Polydispersity index (PDI) increases obviously.

Percolation modeling of relative permeability hysteresis

Abstract The phenomenon of relative permeability hysteresis is observed during the process of developing an oil field by methods where the flow direction changes and the displacement of oil by water is changed into the displacement of water by oil and vice versa. This paper represents a model of relative permeability hysteresis for drainage and imbibition based on percolation theory. The phenomenon of active oil components׳ adsorption on the rock-forming minerals is chosen for the main mechanism of hysteresis origin. In the process of drainage, this causes surface hydrophobization of initially hydrophilic rock which leads to each phase relative permeability change. To describe this phenomenon a percolation model for media with microheterogeneous wettability is used. The received numerical solution is represented as relative permeability curves and is qualitatively confirmed by the experimental data. The behavior of relative permeability hysteresis is observed and analyzed for different differential radius distribution curves, capillary network coordination numbers, saturation models and hydrophobization degrees. Further, the introduced methodology can be put into practice for relative permeability calculation considering hysteresis in any porous media to reduce the time spent.

Liquid dispersion by centrifugal injectors under large drops forming conditions

The goal of the study of liquid dispersion by centrifugal injector for getting uniform drop size distribution is formulated. The salient methods of dispersion process study and possible means of data processing are discussed. Specimens of the obtained differential and integral size-wise drop distribution curves are given.

Determination of Molecular Weight and Distribution of Tetrafluoroethylene-Hexafluoropropylene Copolymers by a Dynamic Rheology Method

Weight-average molecular weight () and its distribution of tetrafluoroethylene-hexafluoropropylene copolymers (FEP) were measured through dynamic melt viscoelastic tests. According to the Cox–Merz law and the four-parameter Carreau–Yasuda equation, the zero-shear viscosity could be obtained from the complex viscosity-frequency relationship. Then, the of FEP could be gained from the relationship of zero-viscosity and molecular weight. Based on Tuminello's theory, the curves of dynamic storage modulus (G′) vs. frequency (ω) could be transformed to a cumulative molecular weight distribution I(M), from which the weight-fraction differential molecular weight distribution (DMW) was obtained. Here, we gave a new function to estimate the front factor that relates frequency to molecular weight through basic rheological theory. Also, we gave a specific way to scale and normalize the differential distribution curves. Furthermore, when the DMW could be expressed by a three-parameter log-normal, like our samples, a very simple function was given to express the scaling factor, normalization factor, and polydispersity index. Additionally, it was also found that the polydispersity index was independent of scaling and the normalization factor.

Trace metal leaching behavior studied through the use of parametric modeling of water borne soil particles fractionated with a split-flow thin cell.

Leaching of particle-bound metals affects the ability of settling ponds and other engineered structures to remove metallic pollutants, and leaching behavior is related to particle size. In this investigation, water borne soil particles were leached and fractionated with a split-flow thin cell, and the metal loadings were quantified as a function of particle size. For comparison of the metal-loading curves, different empirical modeling procedures were investigated to convert the data to a precise functional form suitable for quantitative comparison of changes in differential loading as a function of particle size. Results of this investigation are presented for a soil sample before and after leaching caused by simulated acid rain conditions. Following simulated acid rain leaching, the shape of the differential distribution curves change, and these changes reflect the particle size mediated leaching behavior. For the soil used in this demonstration, simulated acid rain leaching shifted the differential loading toward larger particle sizes, and the magnitude of the shift varied significantly among the metals. Because settling rate decreases as the square of particle size, this could potentially affect management decisions for settling ponds receiving these particles. The high precision afforded by the analysis allows the development of insight into the leaching mechanisms through comparing "partial" acid rain leaching with "total recoverable" leaching by EPA Method 3050.

Study and application of a mathematical model for the provisional assessment of areas and nasal resistance, obtained using acoustic rhinometry and active anterior rhinomanometry.

Nasal resistance (NR) depends on the geometrical features and tortuosity of the nasal airway and on the air flow. Knowing the longitudinal distribution of cross-sectional areas (CSAs) in the nasal cavity (which can be obtained using acoustic rhinometry) and the laminar nasal resistance (obtainable by processing the rhinomanometric results), it is possible to calculate, utilizing a mathematical model elaborated on the basis of fluid dynamics, the differential nasal resistance (NRdiff) and the cumulative nasal resistance (NRcum), thus localizing the position at which the highest resistance is concentrated and the related longitudinal distribution. Using a mathematical model, we integrated the sigmoid curves DeltaP/Q of rhinomanometry with the cross-sectional areas obtained using acoustic rhinometry, thus obtaining the normal distribution of differential and cumulative nasal resistances. Afterwards, we empirically reduced the cross-sectional areas corresponding to the head, body, tail and the whole inferior turbinate, recalculating the differential and cumulative nasal resistance distribution curves. The results show that reduction of up to 50% of cross-sectional areas does not substantially affect the resistivity role of the nasal valve, while greater reductions move the highest resistivity point to an area at the junction of the body and the head of the inferior turbinate. The study of the differential nasal resistance trend curves as a function of the reduction of cross-sectional areas shows that the resistance variation of the body and the whole inferior turbinate prevail with reductions of up to 40%, while the variation of cross-sectional areas of the body bordering the inferior turbinate head is predominant with higher reductions. The cross-sectional areas of the nasal airway cavity with highest resistivity are mainly located in an anterior position, where the differential nasal resistances are higher, but there are substantial variations produced by reducing the cross-sectional area of the posterior nasal airway. A similar model can produce provisional values for the results obtainable with functional nasal surgery.

On the full-width-at-half-maximum of field ion energy distributions

The full-width-at-half-maximum, FWHM, of rare-gas (He, Ne) field ion energy distributions was measured in three different probe-hole FIMs, all combined with retarding potential analysis. The transmission functions of the spectrometers were analyzed through measurements of the total electron energy distributions. The FWHM resolution for ion energy spectroscopy ranged between 80 and 280 meV depending on pass energies. Differential distribution curves were submitted to deconvolution procedures involving direct and inverse Fourier transformations. Experimental FWHM data, derived from deconvolved ion energy distributions were compared with results of model calculations. At best image field-strengths and at temperatures above 150 K, field ionization of non-accommodated He and Ne appears to cause relatively broad FWHMs (between 0.6 and 1.0 eV). The FWHMs decrease typically by a factor of two, as the temperature of the emitter is decreased below 79 K. For He + emission from an individual W[100] zone line decoration atom at T w = 45 K, a 287 meV FWHM was determined. In the low temperature case, the postulated explanation is the field ionization of He and Ne being approximately at rest in the instant of ionization. Our measurements indicate that selection of different emission sites and variation of the tip radius affect the FWHMs.

Analysis of the Molecular Weight Distributions of Aminolyzed Poly(Ethylene Terephthalate) by Using Gel Permeation Chromatography

Abstract The molecular weight distributions of poly(ethylene terephthalate) fibers aminolyzed with selected primary amines (namely, methylamine, ethylamine, n-butylamine, and ethanolamine) were determined by using gel permeation chromatography. Initially the shape of the differential molecular weight distribution (DMWD) curve did not change although its peak shifted to lower molecular weights. As aminolysis continued, a shoulder appeared on the DMWD curve. Its appearance seemed to coincide with an increase in the density of the product. Ultimately, distinct molecular populations could be identified in the treated polymer depending on the severity of the aminolysis and the selectivity of the particular amine. The lowest is thought to represent primarily crystalline residues and has a peak molecular weight of 3400. The relations between M n and ultimate tenacity and breaking strain for the aminolyzed products were linear.

Adsorption of ammonia on activated carbon

Adsorption isotherms were measured for ammonia on untreated FB4 activated carbon, FB4 activated carbon impregnated with ZnCl2, and on activated carbon from anti-ammonia filter ( Leipzig, F.R.G.). The potential theory was applied to the measurements. The Dubinin-Radushkevich plot in linearized coordinates for sorbents of the first structural type revealed that the Czechoslovak FB4 activated carbon possesses a bidisperse structure, giving two linear segments in the plot. The sample from the filter, which served as a reference material, exhibited a single straight line in the plot. The measurements were supplemented by the mercury porosimetry determination of the differential distribution curves. The three types of activated carbon were characterized by emission spectral analysis. The characteristic curve enables the equilibrium adsorption to be converted to different pressure and temperature conditions, and thus it is a suitable method for trapping ammonia in freezing stores to protect foods in case of leak of coolant.

Influence of the length of the molecule of crosslinking agent and its nature on the value of the parameters of the porous structure of polymeric sorbents

The true and apparent densities, pore radii, differential distribution curves of the pore volume over the radii, the total volume of the pores and the specific surface of copolymers of methyl acrylate with divinyl glycol ethers and nitrogen-phsphorus containing ion-exchangers based on them and synthesized in an aqueous medium have been determined. It is shown that with increase in the length of the molecule of the crosslinking agent the global pore volume of the copolymers and ion-exchangers in the non-hydrated state diminishes. Chemical modification of the copolymers reduced the overall voleme of the pores of the sorbents which is explained by change in their thermodynamic affinity for water and, as a consequence, by change in the elasticity of the gels formed.