Real Grain Research Articles

Kinetics of grain-boundary nucleated transformations in rectangular geometries and one paradox relating to Cahn's model

It was found by Jägle and Mittenmeijer [Acta Mater. 59 (2011) 5775-5786] as a result of computer simulation that Cahn's equation underestimates pronouncedly the transformed fraction in reality. To test the hypothesis that a strong correlation in the arrangement of grains in the Cahn model (they are “tied” to planes) can be responsible for this phenomenon, the paradox of packing is described: the structures composed of the same elements (random parallelepipeds) transforming in the same way, but packed differently, give different transformation rates. One of these structures is a special Cahn model – the grain structure of parallelepipeds formed by three sets of random parallel planes orthogonal to each other. An alternative structure consists of the same parallelepipeds, but randomly packed; it looks like a real grain structure. It is shown analytically that the kinetics of transformation in the first structure is considerably slowed down in comparison with that in the second. For the various intermediate structures under consideration, the kinetic curves are between these two, so that the following rule is established: the transformation kinetics is accelerated, when the correlation in the arrangement of the parallelepipeds weakens. Preliminarily, volume-fraction expressions are obtained for the systems of an infinite number of parallel planes arranged both regularly and randomly. As a special case of random arrangement, a non-Poissonian point process (the second-order Erlang process) of the arrangement of planes is considered for the first time. The exact volume-fraction expression obtained for this case shows that it cannot be derived by Cahn's method, i.e. the extended-volume approach is applicable only to Poisson processes. The volume fraction equations for regular planes are used to study cubic grain structures, both regular and random. It is shown that Cahn's equation underestimates the transformation kinetics in both regular and random structures with four different size distributions of cubes; the degree of underestimation depends on the size distribution, being the largest in the regular structure.

Grain size estimation in polycrystals: Solving the corpuscle problem using Maximum Likelihood Estimation

In materials science, the microstructures of materials are generally characterized by 2D observation (e.g. electron microscopy). For polycrystalline materials, such as crystalline rocks or ceramics, those observations can be used to measure the grain size distribution. However, the fact that grain sizes are measured in planar cuts introduces a statistical bias, since the real (3D) grain sizes cannot be directly measured. For almost spherical grains, this bias can be computed thanks to the so-called Wicksell's equation. This paper proposes a method, based on Maximum Likelihood Estimation (MLE) for unfolding the apparent 2D distribution. The efficiency of this method is extensively investigated in the special case of lognormal distribution. In this case, 10% uncertainty on the distribution parameters can be reached with only 580 empirical values.

Establishment and extension of digital aggregate database using auxiliary classifier Wasserstein GAN with gradient penalty

For road construction, the morphological characteristics of coarse aggregates such as angularity and sphericity have a considerable influence on asphalt pavement performance. In traditional aggregate simulation processes, images of real coarse grains are captured, and their parameters are extracted manually for reproducing them in a numerical simulation such as Discrete Element Modeling (DEM). Generative Adversarial Networks can generate aggregate images, which can be stored in the Aggregate DEM Database directly. In this paper, it has been demonstrated that applying Auxiliary Classifier Wasserstein GANs with gradient penalty (ACWGAN-gp) is reliable and efficient for the establishment of an aggregate image database. In addition, the distribution of original images was compared with that of images generated based on ACGAN and ACWGAN-gp models. Generated images were validated through obtaining identifiable edge coordinates and represented as DEM input in the simulation process. The results prove that the ACWGAN-gp approach can be used for generating aggregate images for the DEM database. It successfully generates high-quality images of aggregates with a representative distribution of morphologies used for DEM simulation. This work shows convenience and efficiency for machine learning applications in the road construction field.

Statistical Assessment of the Effects of Grain-Structure Representation and Micro-Properties on the Behavior of Bonded Block Models for Brittle Rock Damage Prediction

The ability to predict the mechanical behavior of brittle rocks using bonded block models (BBM) depends on the accuracy of the geometrical representation of the grain-structure and the applied micro-properties. This paper evaluates the capabilities of BBMs for predictive purposes using an approach that employs published micro-properties in combination with a Voronoi BBM that properly approximates the real rock grain-structure. The Wausau granite, with Unconfined Compressive Strength (UCS) of 226 MPa and average grain diameter of 2 mm, is used to evaluate the effectiveness of the predictive approach. Four published sets of micro-properties calibrated for granites with similar mineralogy to the Wausau granite are used for the assessment. The effect of grain-structure representation in Voronoi BBMs is analyzed, considering grain shape, grain size and mineral arrangement. A unique contribution of this work is the explicit consideration of the effect of stochastic grain-structure generation on the obtained results. The study results show that the macro-properties of a rock can be closely replicated using the proposed approach. When using this approach, the micro-properties have a greater impact on the realism of the predictions than the specific grain-structure representation. The grain shape and grain size representations have a minor effect on the predictions for cases that do not deviate substantially from the real average grain geometry. However, the stochastic effect introduced by the use of randomly-generated Voronoi grain-structures can be significant, and this effect should be considered in future studies.

Real single grain grinding FEM simulation for case-hardened steel based on equivalent contact area analysis

Abstract Grinding is an indispensable phase in the gear production chain as it allows very stringent requirements characteristic of the automotive sector to be satisfied. The main goal of this finishing process is to ensure compliance with the surface integrity and dimensional tolerance specifications of the product. A single-grain grinding FEM model has been implemented to predict grinding load values based on real grain geometry using a set of Johnson & Cook coefficients able to represent the flow stress curve of a typical gear case-hardened steel 27MnCr5. Grain geometry acquired through computed tomography was imported into three-dimensional process simulation software DEFORM-3D. As the use of real grain geometry leads to time-consuming simulations, an equivalent defined geometry grain was implemented to compare cutting behavior and calculate maximum force values through real contact area analysis under the same process parameters. Calculated loads were subsequently compared with experimental results, showing good agreement with a maximum percentage difference less than 13% for two different grain geometries. Grinding force measurements were performed in a single-grain configuration on a CNC surface grinding machine adopting a wheel speed of 384 rad/s, feed rate of 8.6 mm/s and a depth of cut of 0.1 mm.

Temperature-dependent fatigue response of a Fe44Mn36Co10Cr10 high entropy alloy: A coupled in-situ electron microscopy study and crystal plasticity simulation

The fatigue behavior of Fe44Mn36Co10Cr10 high entropy alloy (HEA) at room temperature and 300 °C was studied by in-situ SEM observation, electron back-scattered diffraction (EBSD) and crystal plasticity simulation. The microstructure evolution and deformation process was observed by in-situ SEM fatigue experiment. The misorientation and geometrically necessary dislocation (GND) density was analyzed by EBSD. A crystal plasticity finite element (CPFE) modeling method based on the real grain morphology was proposed. The cumulative plastic strain, dominant slip system and dominant slip plane distributions were obtained. CPFE simulation shows multiple dominant slip systems being activated, which agrees with the multiple slip phenomena observed by in-situ SEM.

Dynamic microwave-assisted extraction combined with liquid phase microextraction based on the solidification of a floating drop for the analysis of organochlorine pesticides in grains followed by GC

A convenient, cost-effective and fast method using dynamic microwave-assisted extraction and liquid phase microextraction based on the solidification of a floating drop was proposed to analyze organochlorine pesticides in grains including rice, maize and millet. Twelve samples can be processed simultaneously in the method. During the extraction process, 10% acetonitrile-water solutions containing 110μL of n-hexadecane were used to extract organochlorine pesticides. Subsequently, 1.0g sodium chloride was placed in the extract, and then centrifuged and cooled. The n-hexadecane drops containing the analytes were solidified and transferred for determination by gas chromatography-electron capture detector without any further filtration or cleaning process. Limits of detection for organochlorine pesticides were 0.97–1.01μg/kg and the RSDs were in the range of 2.6%–8.5%. The developed technology has succeeded in analyzing six real grains samples and the recoveries of the organochlorine pesticides were 72.2%–94.3%. Compared with the published extraction methods, the developed method was used to analyze organochlorine pesticides in grains, being more environmentally friendly, which is suitable for the daily determination of organochlorine pesticides.

Date of ear emergence: a factor for notable changing the grain yield of modern winter wheat varieties in different environments of Bulgaria

Abstract. Wheat is a crop with a very long growing season, during which it is subjected to prolonged exposure to many environmental factors. For this reason, the interaction of genotype with conditions is very common for any character of wheat. This study aims to determine whether the grain yield is affected by the change of the ear emergence date (EED) in various environments. In a four-year period, 30 current for national real grain production winter wheat varieties were studied. The EED and grain yield (GY) were studied as quantitative traits within five locations of the country having various soil and climatic conditions. Using several statistical programs, genotype x environment interaction of two traits was analyzed. The emphasis on data analysis was whether changes of traits due to the conditions were related and that the optimization of the ear emergence date could serve as a breeding tool for increasing grain yield. The date of ear emergence and grain yield are traits that are reliably influenced by growing conditions. The change in the date of emergence is mainly of the linear type, while the grain yield shows linear and nonlinear type changes in the same environmental conditions. It was found that the key roles in the change of characteristics are the conditions of the year, with the relatively weakest impact of the genotype on them. There is a positive relationship between the two traits, although their change depends on environmental factors. Although they change to different degrees and in relation to each other, there is a positive correlation between them. The more favorable the environmental conditions, the weaker the relationship between these two traits and vice versa. Under changing climatic conditions, the change in the relationship between the two traits is a signal of the need to create different varieties by date of ear emergence in order to obtain higher yields in the future.

Approach to the numerical modelling of the chip temperatures in single grain scratching

To achieve a fundamental understanding of the physical mechanisms and the heat generation in the contact zone during grinding, a large number of experimental and numerical investigations have been carried out to analyse the interaction of single grain and workpiece. Existing numerical models of the interaction between grain and workpiece do not represent the reality and especially the influence of the three-dimensional grain geometry on the temperatures during single grain scratching with sufficient accuracy. An experimental validation of the simulated temperatures has not been carried out yet as there is no appropriate method to measure them in experimental investigations. In this study, a three-dimensional FE-model of the interaction between CBN-grain and workpiece (100Cr6) in the grinding process is presented. The model predicts the chip temperatures for real grain geometries to investigate the interactions between grain and workpiece. The experiments to validate the model were carried out using a ratio pyrometer.

Multi-Class Grain Size Model for Forged Alloy 718 Aircraft Parts

The evolution of microstructural features such as local grain size and local grain size distribution are essential in view of the final physical and mechanical properties of the nickel base alloy 718 for aircraft parts forged in a multi-step production route. Due to increasing standards and the need of the prediction of fracture mechanical properties, a multi-class grain size model for a more detailed microstructure prediction is necessary. Therefore, a multi-class model considers the real initial non-uniform grain size distribution and structure of the pre-material at the beginning of the forging process, which affects the evolution of grain sizes during thermo-mechanical treatment and leads to different results than commonly used uniform grain structures. The initial distribution is defined by grain classes according the ASTM standard. It is shown that the presence of different classes and distributions of grains are as import as the applied strain, strain rate and temperature on dynamic, meta-dynamic and static recrystallization. Additionally, dissolution processes of delta phase and grain growth kinetics are included in the model to properly indicate the recrystallized fractions and represent the resulting multi-class microstructure. A series of simulations with different initial distributions is discussed and compared with examined forged samples in terms of the resulting microstructure for typical forging parameters. Based on these results the microstructure model can be used in combination with collected process data to predict the resulting properties and for the design of new aircraft parts.

Modelling realistic ballast shape to study the lateral pull behaviour using GPU computing

The use of the Discrete Element Method to model engineering structures implementing granular materials has proven to be an efficient method to response under various behaviour conditions. However, the computational cost of the simulations increases rapidly, as the number of particles and particle shape complexity increases. An affordable solution to render problems computationally tractable is to use graphical processing units (GPU) for computing. Modern GPUs offer up 10496 compute cores, which allows for a greater parallelisation relative to 32-cores offered by high-end Central Processing Unit (CPU) compute. This study outlines the application of BlazeDEM-GPU, using an RTX 2080Ti GPU (4352 cores), to investigate the influence of the modelling of particle shape on the lateral pull behaviour of granular ballast systems used in railway applications. The idea is to validate the model and show the benefits of simulating non-spherical shapes in future large-scale tests. The algorithm, created to generate the shape of the ballast based on real grain scans, and using polyhedral shape approximations of varying degrees of complexity is shown. The particle size is modelled to scale. A preliminary investigation of the effect of the grain shape is conducted, where a sleeper lateral pull test is carried out in a spherical grains sample, and a cubic grains sample. Preliminary results show that elementary polyhedral shape representations (cubic) recreate some of the characteristic responses in the lateral pull test, such as stick/slip phenomena and force chain distributions, which looks promising for future works on railway simulations. These responses that cannot be recreated with simple spherical grains, unless heuristics are added, which requires additional calibration and approximations. The significant reduction in time when using non-spherical grains also implies that larger granular systems can be investigated.

Kinetics of Grain-Boundary Nucleated Transformations in Rectangular Geometries and One Paradox Relating to Cahn's Model

It was found by Jagle and Mittenmeijer [Acta Mater. 59 (2011) 5775-5786] as a result of computer simulations that Cahn’s equation underestimates pronouncedly the transformed fraction in reality. To test the hypothesis that a strong correlation in the arrangement of grains in the Cahn model (they are “tied” to planes) can be responsible for this phenomenon, the paradox of packing is described: the structures composed of the same elements (random parallelepipeds) transforming in the same way, but packed differently, give different transformation rates. One of these structures is a special Cahn model – the grain structure of parallelepipeds formed by three sets of random parallel planes orthogonal to each other. An alternative structure consists of the same parallelepipeds, but randomly packed; it looks like a real grain structure. It is shown analytically that the kinetics of transformation in the first structure is considerably slowed down in comparison with that in the second. For the various intermediate structures under consideration, the kinetic curves are between these two, so that the following rule is established: the transformation kinetics is accelerated, when the correlation in the arrangement of the parallelepipeds weakens. Preliminarily, volume-fraction expressions are obtained for the systems of an infinite number of parallel planes arranged both regularly and randomly. As a special case of random arrangement, a non-Poissonian point process (the second-order Erlang process) of arrangement of planes is considered for the first time. The exact volume-fraction expression obtained for this case shows that it cannot be derived by Cahn’s method, i.e. the extended-volume approach is applicable only to Poisson processes. The volume fraction equations for regular planes are used to study cubic grain structures, both regular and random. It is shown that Cahn’s equation underestimates the transformation kinetics in both regular and random structures with four different size distributions of cubes; the degree of underestimation depends on the size distribution, being the largest in the regular structure.

Economic significance, nutritional value and application of triticale

Triticale is a new type of real grain, which was created by the breeding and selection of a man. This species deserves more and more attention from both domestic producers and producers on a global scale because it encompassed all the positive properties of wheat and rye. The paper clearly presents the knowledge about the importance, nutritional value and application of triticale and the effect of its usage in a diet of monogastric animals. The variety of uses, appropriate chemical composition, acceptable and studied breeding technology, classifies triticale as an irreplaceable source of energy and protein needs of animals. Due to its multiple usages: for grain, fodder and as a raw material for biofuel, contributes to the economic sustainability of crop production. The needs of this plant at the level of agrotechnical investments are less than in other cereals, so triticale is increasingly presented in organic and sustainable agricultural production.

PKB Zmaj - nova sorta ozime raži Instituta PKB Agroekonomik

For the last twenty years, in addition to breeding wheat, PKB Agroekonomik Institute has been working very intensively on breeding other real or bread grains. High-yielding, late winter rye variety PKB Zmaj has been obtained by the pedigree method by a simple crossing of genetically different parents from the collection of PKB Agroekonomik Institute: variety Rtanj and line PKB-R-105. This variety of winter rye combines genes responsible for very high yield potential, resistance to lodging, low temperatures and more significant diseases in the rye. Winter rye variety PKB Zmaj was registered by the Ministry of Agriculture, Forestry and Water Management of the Republic of Serbia in 2018. With the use of optimal agricultural techniques, the variety PKB Zmaj has a high genetic potential for fertility and high adaptation to different climatic and soil conditions.

МОДЕЛЬ СИСТЕМНОЙ ДИНАМИКИ РЕГИОНАЛЬНЫХ РЫНКОВ ЗЕРНА

The paper develops a methodology for modeling regional markets for field crops, taking grain markets as a case. It proposes and tests a new combination of model assumptions that solves the problem of reproducing the actually observed stability of product supply to the consumer in the context of predominantly market regulators. A basic model of the grain market functioning is developed, describing in continuous time the chain of commodity flows linking producers and consumers. Interregional transportation is taken into account. This is a prototype of a future model, which should be calibrated on actual data and include markets for grain processing products, as well as the possibility of simulating economic policy instruments. The model is based on the principle of market fundamentalism when modeling the volume of grain production, setting them in a sole dependence on prices. The same principle, yet with reservations, is applied in the modeling of exports and interregional transportation. Consumption modeling combines opposing principles of market fundamentalism, which guides consumers, and market skepticism of resellers – counterparties of consumers. Resellers, when deciding on the volume of supplies, neglect prices – they are guided by the size and dynamics of grain stock. As a result of computer simulations, it is shown that a set of assumptions underlying the model provides, with an appropriate selection of parameters, the necessary dynamic properties of the model: in all regions, the relative stability of consumption and prices during the season is secured, and short-term fluctuations in domestic prices effectively direct grain transportation to regions in need. Moreover, the volume of grain exports weakly correlates with domestic price of grain, which is typical for the real Russian grain market. The ultimate aim of the study, one of the stages of which is the algorithm presented in the paper, is to create tools for analyzing the interaction effects of the economic policy measures applied in different sections of the production and processing chains of various types of field crops for periods shorter than a year.

Natural Crossing for Rice Variety (Oryza sativa. L) Recovery

The rice production can be reached through a good intensification pattern, ­in this case used of superior varieties. Superior varieties are varieties that produced from difficult activities. The research objective was to determine the success rate of natural crosses between rice varieties with jajar legowo models. The research method used a randomized block design in the fields of Banjarejo, Taman, Madiun City in the first planting season of 2019. Treatment of jajar legowo model was 2:1, the varieties used a Trisakti and rice genotype A. The test results show that real rice grains to good crossovers weight and number of grains with high variation.The results of this research will be carried out with the next testing stages, the grain characters to obtain new superior varieties. The superior characteristic that is expected is the combination of superior traits of both parents and superior varieties resulting from natural crosses can be obtained after repeated selection and evaluation so that homogeneity and yield stability are maintained

Ultrasensitive ratiometric detection of Pb2+ using DNA tetrahedron-mediated hyperbranched hybridization chain reaction

A fluorescent sensing strategy was developed for rapid, highly sensitive and specific detection of lead (II) ion (Pb2+) on the basis of Pb2+ DNAzyme-controlled tetrahedral DNA nanostructure (TDN)-mediated hyper-branched hybridization chain reaction (hHCR). In this strategy, DNA hairpins used for HCR amplification are modified on the four vertexes of TDN, which are then used to perform rapid TDN-hHCR in the presence of an initiator strand, producing large-sized cross-linked reaction products and thus giving greatly improved fluorescence resonance energy transfer (FRET) signal output. Pb2+ DNAzyme catalyzes the cleavage of the initiator strand, inhibiting the initiation of TDN-hHCR and giving decreased FRET signal. Synergetic signal amplification of Pb2+ DNAzyme-catalyzed cleavage reaction and subsequent TDN-hHCR confers the sensing platform with ultrahigh sensitivity. As low as 0.25 pM Pb2+ can be detected by using either signal “turn-on” or “turn-off” mode. The whole detection process can be finished within 20 min. Strong anti-interference capacity of FRET-based ratiometric detection and high specificity of Pb2+ DNAzyme endow the sensing platform with great practical application potential, which was demonstrated by the accurate detection of Pb2+ in real river water, fruit, vegetable and grain samples.

Effect of grain boundary energy anisotropy on grain growth in ZK60 alloy using a 3D phase-field modeling* *Project supported by the National Key Research and Development Program of China (Grant No. 2016YFB0701204), the 111 Project, China (Grant No. B20029), the Fundamental Research Funds for the Central Universities, China (Grant Nos. N2002017 and N2007011), the National Natural Science Foundation of China

A three-dimensional (3D) multiple phase field model, which takes into account the grain boundary (GB) energy anisotropy caused by texture, is established based on real grain orientations and Read–Shockley model. The model is applied to the grain growth process of polycrystalline Mg (ZK60) alloy to investigate the evolution characteristics in different systems with varying proportions of low-angle grain boundary (LAGB) caused by different texture levels. It is found that the GB energy anisotropy can cause the grain growth kinetics to change, namely, higher texture levels (also means higher LAGB proportion) result in lower kinetics, and vice versa. The simulation results also show that the topological characteristics, such as LAGB proportion and distribution of grain size, undergo different evolution characteristics in different systems, and a more serious grain size fluctuation can be caused by a higher texture level. The mechanism is mainly the slower evolution of textured grains in their accumulation area and the faster coarsening rate of non-textured grains. Therefore, weakening the texture level is an effective way for implementing a desired homogenized microstructure in ZK60 Mg alloy. The rules revealed by the simulation results should be of great significance for revealing how the GB anisotropy affects the evolution of polycrystalline during the grain growth after recrystallization and offer the ideas for processing the alloy and optimizing the microstructure.

Assessing consumers' understanding of the term "Natural" on food labeling.

The objective of this study was to gain a better understanding of how consumers' interpret the term "natural" by assessing food choice based on labels describing attributes of a product associated with the term "natural"; to assess food intake of chosen food, and; to determine factors that influence food choice and intake. A randomized, single-visit pilot study was conducted where participants (n = 105) were presented with seven identical bowls of granola each bearing a different descriptive label. Participants were asked to choose and eat the granola (ad libitum) that coincided with what was closest to their view of "natural." Food choice, intake amount, demographics, self-health perception, label use, dietary restraint, and mindfulness were measured. "Organic" (31%), "Made with real grains" (17%), and "No preservatives" (15%) were the top three chosen labels. These choices related to concerns about environment and processing, personal health, and additives and preservatives, respectively (P = 0.049). Income level and age were significantly associated with choice (P = 0.003). Defining the term "natural" for use on food labels will require follow-up researchacrosseconomically diverse populations and age groups to understand expectations of food products bearing the term "natural."

VARIATION OF THERMAL CONDUCTIVITY WITH POROSITY

Thermal conductivity in porous media as a function of the grain size and porosity has been studied establishing a relation between these two parameters. The study has been developed for a homogeneous porous medium with grain size in a very close range of particle diameter. The study has been extended from very small particles to large ones, to cover most of the real grain size. As a result of this study porous medium with homogeneous mineralogical structure and composition has been thermally characterized. The performance of this porous medium as for the heat flow is concerned has also been studied and analysed as one of the goals of this paper. Results have shown that thermal conductivity is greatly influence by porosity in porous media, thus affecting the heat transfer flow, which may affect civil structures in close contact with the porous media.The study has shown a very good agreement between predicted values and experimental result, which proves the validity of the study.