Статті в журналах: "Estimation des microstructures"

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Amnuaykijvanit, O., S. Anantawaraskul, and T. Rakthanmanon. "Estimation of ethylene/1-butene copolymerization conditions using the autoencoder model." Journal of Physics: Conference Series 2175, no. 1 (January 1, 2022): 012028. http://dx.doi.org/10.1088/1742-6596/2175/1/012028.

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Abstract Chain microstructures of ethylene/1-butene copolymers produced at specific polymerization conditions can be calculated using the copolymerization kinetic model. However, this kinetic model cannot be solved inversely to estimate polymerization conditions from desired microstructures. In this work, the autoencoder (AE) model, the machine learning techniques based on artificial neural network (ANN) concept, was developed to help estimate polymerization conditions to produce polymers with desired microstructures (e.g., molecular weight distribution (MWD), chemical composition distribution (CCD), and number and weight average molecular weight). Two models were developed in this work: one with only microstructural distributions (MWD and CCD) and the other with additional information on average microstructures and polymer yield. The results showed that the proposed AE models can adequately estimate polymerization conditions from desired microstructures with acceptable mean square error (MSE). More specific microstructures lead to better estimation of polymerization conditions with lower MSE.

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Palevicius, Arvydas, and Giedrius Janusas. "Analysis of Periodical Microstructures Using Optical Methods." Advanced Materials Research 433-440 (January 2012): 2021–28. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.2021.

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In this work we present an optical laser based method for characterization of periodical microstructure. It allows indirect evaluation of geometrical and optical parameters of periodical microstructures. Proposed method is applicable for optimization and control of technological processes in the cases when traditional measurement techniques are not suitable. The main experimental results are compared with the computer simulations where the standard programs PCGrate-SX6.0 and and GSolver V4.20b were employed. Error of estimation of geometrical parameters of periodical microstructures by comparing theoretical and experimental values of diffraction efficiencies of periodical microstructures is less than 5%.

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Liu, Zaobao, Jianfu Shao, Weiya Xu, and Chong Shi. "Estimation of Elasticity of Porous Rock Based on Mineral Composition and Microstructure." Advances in Materials Science and Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/512727.

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Estimation of elastic parameters of porous rock like the compressibility of sandstone is scientifically important and yet an open issue. This study illustrates the estimation of the elastic compressibility of sandstone (ECS) based on the assumption that the ECS is determined closely by the mineral composition and microstructures. In this study, 37 samples are collected to evaluate the estimations of the ECS obtained by different methods. The regression analysis is first implemented using the 37 samples. The results show that ECS exhibits linear relations with the rock minerals, pores, and applied compressive stress. Then the support vector machine (SVM) optimized by the particle swarm optimization algorithm (PSO) is examined to generate estimations of the ECS based on the mineral composition and microstructures. The SVM is trained with 30 samples to search for optimal parameters using the PSO, and thus the estimation model is established. Afterwards, this model is validated to give predictions of the left 7 samples. By comparison with the regression methods, the proposed strategy, that is, the PSO optimized SVM, performs much better on the training samples and shows a good capability in generating estimations of the ECS of the 7 testing samples based on the mineral composition and microstructures.

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Blanc, Rémi, Pierre Baylou, Christian Germain, and Jean-Pierre Da Costa. "Confidence Bounds for the Estimation of the Volume Phase Fraction from a Single Image in a Nickel Base Superalloy." Microscopy and Microanalysis 16, no. 3 (March 30, 2010): 273–81. http://dx.doi.org/10.1017/s1431927610000139.

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AbstractWe propose an image-based framework to evaluate the uncertainty in the estimation of the volume fraction of specific microstructures based on the observation of a single section. These microstructures consist of cubes organized on a cubic mesh, such as monocrystalline nickel base superalloys. The framework is twofold: a model-based stereological analysis allows relating two-dimensional image observations to three-dimensional microstructure features, and a spatial statistical analysis allows computing approximate confidence bounds while assessing the representativeness of the image. The reliability of the method is assessed on synthetic models. Volume fraction estimation variances and approximate confidence intervals are computed on real superalloy images in the context of material characterization.

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Ben Ahmed, Amal, Ahmad Bahloul, Mohamed Iben Houria, Anouar Nasr, and Raouf Fathallah. "Multiaxial fatigue life estimation of defective aluminum alloy considering the microstructural heterogeneities effect." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233, no. 9 (August 16, 2018): 1830–42. http://dx.doi.org/10.1177/1464420718792024.

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The Al–Si–Mg high-cycle fatigue behavior is mainly affected by the microstructural heterogeneities and the presence of casting defects. This attempt aims to develop an analytical approach based on the evaluation of the highly stressed volume caused by local porosities and defined as the affected area methodology. The proposed approach is able to predict the aluminum alloy fatigue response by considering the effect of microstructure described by the secondary dendrite arm spacing and its correlation with the defect size effect. A representative elementary volume model is implemented to evaluate the stress distribution in the vicinity of the defect and to determine its impact on the high-cycle fatigue resistance. Work hardening due to cyclic loading is considered by applying the Lemaitre–Chaboche model. The Kitagawa–Takahashi diagrams corresponding to different microstructures and for two loading ratios: R σ = 0 and R σ = −1 were simulated based on the AA method. Simulations were compared to the experimental results carried out on cast aluminium alloy A356 with T6 post heat-treatment. The results show clearly that the proposed approach provides a good estimation of the A356-T6 fatigue limit and exhibits good ability in simulating the Kitagawa–Takahashi diagrams for fine and coarse microstructures.

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McNelley, Terry R., Keiichiro Oh-ishi, and Alexandre P. Zhilyaev. "Microstructure Evolution and Microstructure-Property Relationships in Friction Stir Processing of NiAl Bronze." Materials Science Forum 539-543 (March 2007): 3745–50. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3745.

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Friction stir processing (FSP) has been employed for localized modification and control of microstructures in NiAl bronze materials, which are widely utilized for marine components. The thermomechanical cycle of FSP results in homogenization and refinement and the conversion of microstructures from a cast to a wrought condition within stir zones in the material. However, the direct measurement of stir zone temperatures, strains, strain rates and cooling rates is difficult due to steep gradients and transients in these quantities, and this is an impediment in the assessment of FSP-induced microstructures and properties. Quantitative microstructure analyses following FSP of cast NiAl bronze materials have been used to develop estimates of stir zone thermomechanical cycles. The estimation procedures will be reviewed and the microstructure-based estimates will be compared to results from computational models and embedded thermocouples measurements. Stir zone microstructures comprise a mixture of primary α grains and transformation products of the β that formed during processing. Recrystallization in the primary α occurred due to particle-stimulated nucleation in this low stacking fault energy material. Factors that influence the distribution of strength and ductility in the stir zone appear to include the mixture of microstructure constituents and gradients in microstructure due to gradients in processing conditions.

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Liu, Lishuai, Peng Wu, Yanxun Xiang, and Fu-Zhen Xuan. "Autonomous characterization of grain size distribution using nonlinear Lamb waves based on deep learning." Journal of the Acoustical Society of America 152, no. 3 (September 2022): 1913–21. http://dx.doi.org/10.1121/10.0014289.

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Characterization of grain microstructures of metallic materials is crucial to materials science and engineering applications. Unfortunately, the universal electron microscopic methodologies can only capture two-dimensional local observations of the microstructures in a time-consuming destructive way. In this regard, the nonlinear ultrasonic technique shows the potential for efficient and nondestructive microstructure characterization due to its high sensitivity to microstructural features of materials, but is hindered by the ill-posed inverse problem for multiparameter estimation induced by the incomplete understanding of the complicated nonlinear mechanical interaction mechanism. We propose an explainable nonlinearity-aware multilevel wavelet decomposition-multichannel one-dimensional convolutional neural network to hierarchically extracts multilevel time-frequency features of the acoustic nonlinearity and automatically model latent nonlinear dynamics directly from the nonlinear ultrasonic responses. The results demonstrate that the proposed approach establishes the complex mapping between acoustic nonlinearity and microstructural features, thereby determining the lognormal distribution of grain size in metallic materials rather than only average grain size. In the meantime, the integration of the designed nonlinearity-aware network and the quantitative analysis of component importance provides an acceptable physical explainability of the deep learning approach for the nonlinear ultrasonic technique. Our study shows the promise of this technique for real-time in situ evaluation of microstructural evolution in various applications.

8

Kawa, Marek. "Failure Criterion for Brick Masonry: A Micro-Mechanics Approach." Studia Geotechnica et Mechanica 36, no. 3 (February 28, 2015): 37–48. http://dx.doi.org/10.2478/sgem-2014-0025.

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Abstract The paper deals with the formulation of failure criterion for an in-plane loaded masonry. Using micro-mechanics approach the strength estimation for masonry microstructure with constituents obeying the Drucker-Prager criterion is determined numerically. The procedure invokes lower bound analysis: for assumed stress fields constructed within masonry periodic cell critical load is obtained as a solution of constrained optimization problem. The analysis is carried out for many different loading conditions at different orientations of bed joints. The performance of the approach is verified against solutions obtained for corresponding layered and block microstructures, which provides the upper and lower strength bounds for masonry microstructure, respectively. Subsequently, a phenomenological anisotropic strength criterion for masonry microstructure is proposed. The criterion has a form of conjunction of Jaeger critical plane condition and Tsai-Wu criterion. The model proposed is identified based on the fitting of numerical results obtained from the microstructural analysis. Identified criterion is then verified against results obtained for different loading orientations. It appears that strength of masonry microstructure can be satisfactorily described by the criterion proposed.

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Yuan, Jianhui, Yu Pan, and Xin Zhang. "Ultrahigh Frequency Data Liquidity Duration Estimation: A Case Study of Chinese A Shares." Mathematical Problems in Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/371272.

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Liquidity has always been a hot spot for researchers of financial market microstructures. Analysis of liquidity is of great significance for investors and market regulators. Ultrahigh frequency data records the whole dynamic change of the trading process, so it has advantages in depicting the market microstructure. This study analyzes Asian emerging market equities liquidity using ultrahigh frequency data. We used various forms of WACD models and let trading duration be indicators of liquidity. Through the residual test, we were able to select the best model to describe the overall liquidity.

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Schouwenaars, Rafael, Víctor H. Jacobo, Sara M. Cerrud, and Armando Ortiz. "Finite Element Simulation of Microstresses in a Traditional FGM: The Case of Soft Tribo-Alloys." Materials Science Forum 492-493 (August 2005): 421–28. http://dx.doi.org/10.4028/www.scientific.net/msf.492-493.421.

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Journal bearings are graded systems with a metal-metal composite as the functional layer. Estimation of the microscale stress distributions is used to analyse the interaction between microstructure, material properties and damage mechanisms during wear. The analysis is executed by means of simple plane-strain finite element models mimicking experimentally observed microstructures. It is found that under realistic macrosstress conditions no tensile microstresses are induced in the triboalloy and that plastic flow is inhibited by the graded structure.

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Do, Huy Quang, Shashank Bishnoi, and Karen Louise Scrivener. "Microstructural modelling of autogenous shrinkage in Portland cement paste at early age." Engineering Computations 37, no. 9 (May 4, 2020): 3171–86. http://dx.doi.org/10.1108/ec-08-2019-0353.

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Purpose This paper aims to develop a numerical, micromechanical model to predict the evolution of autogenous shrinkage of hydrating cement paste at early age (up to 7 days). Autogeneous shrinkage can be important in high-performance concrete characterized by low water to cement (w/c) ratios. The occurrence of this phenomenon during the first few days of hardening may result in early-age cracking in concrete structures. A good prediction of autogeneous shrinkage is necessary to achieve better understanding of the mechanisms and the deployment of effective measures to prevent early-age cracking. Design/methodology/approach Three-dimensional digital microstructures from the hydration modelling platform μic of cement paste were used to simulate macroscopic autogenous shrinkage based on the mechanism of capillary tension. Elastic and creep properties of the digital microstructures were calculated by means of finite element (FE) method homogenization. Autogenous shrinkage was then estimated as the average hydrostatic strain resulting from the capillary stress that was globally applied on the simulated digital microstructures. For this estimation, two approaches of homogenization technique, i.e. analytical poro-elasticity and numerical creep-superposition were used. Findings The comparisons of between the simulated and experimentally measured deformations indicate that the creep-superposition approach is more reasonable to estimate shrinkage at different water to cement ratios. It was found that better estimations could be obtained at low degrees of hydration, by assuming a loosely packed calcium silicate hydrates (C-S-H) growing in the microstructures. The simulation results show how numerical models can be used to upscale from microscopic characteristics of phases to macroscopic composite properties such as elasticity, creep and shrinkage. Research limitations/implications While the good predictions of some cement paste properties from the microstructure at early age were obtained, the current models have several limitations that are needed to overcome in the future. Firstly, the limitation of pore-structure representation is not only from lack understanding of C-S-H structure but also from the computational complexity. Secondly, the models do not consider early-age expansion that usually happens in practice and appears to be superimposed on an underlying shrinkage as observed in experiments. Thirdly, the simplified assumptions for mechanical simulation do not accurately reflect the solid–liquid interactions in the real partially saturated system, for example, the globally applying capillary stress on the boundary of the microstructure to find the effective deformation, neglecting water flow and the pore pressure. Last but not least, the models, due to the computational complexities, use many simplifications such as FE approximation, mechanical phase properties and creep statistical data. Originality/value This study holistically tackles the phenomenon of autogeneous shrinkage through microstructural modelling. In a first such attempt, the authors have used the same microstructural model to simulate the microstructural development, elastic properties, creep and autogeneous shrinkage. The task of putting these models together was not simple. The authors have successfully handled several problems at each step in an elegant manner. For example, although several earlier studies have pointed out that discrete models are unable to capture the late setting times of cements due to mesh effects, this study offers the most effective solution yet on the problem. It is also the first time that creep and shrinkage have been modelled on a young evolving microstructure that is subjected to a time variable load.

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Farhangdoost, Khalil, and S. Rahnama. "Developed Random Tessellation for Modeling of Microstructure." Key Engineering Materials 488-489 (September 2011): 529–32. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.529.

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The concept of random tessellation is extensively used in wide area of natural sciences, especially material sciences. In this paper a simple but complete explanation of the random tessellation and mathematical tools requirements is presented. Then introducing the algorithm and the program for display random tessellation diagram was written. This program, with high speed and simple algorithm for random tessellation has the ability to change the level of statistical parameters such as number, mean, variance of the area of the grain. The ability to model microstructures of metals and grains for mechanical application, such as estimation of mechanical properties and crack propagation model in microstructure scale is very important. Finally, the microstructure produced by this program show good fitness of random generation with real microstructure.

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Tu, Wei-Hsiang, Wen-Chang Chu, Chih-Kung Lee, Pei-Zen Chang, and Yuh-Chung Hu. "Effects of etching holes on complementary metal oxide semiconductor–microelectromechanical systems capacitive structure." Journal of Intelligent Material Systems and Structures 24, no. 3 (June 11, 2012): 310–17. http://dx.doi.org/10.1177/1045389x12449917.

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Etching the large area of sacrificial layer under the microstructure to be released is a common method used in microelectromechanical systems technology. In order to completely release the microstructures, many etching holes are often required on the microstructure to enable the etchant to completely etch the sacrificial layer. However, the etching holes often alter the electromechanical properties of the micro devices, especially capacitive devices, because the fringe fields induced by the etching holes can significantly alter the electrical properties. This article is aimed at evaluating the fringe field capacitance caused by etching holes on microstructures. The authors aim to find a general capacitance compensation formula for the fringe capacitance of etching holes by the use of ANSYS simulation. According to the simulation results, the design of a capacitive structure with small etching holes is recommended to prevent an extreme capacitance decrease. In conclusion, this article provides a fringing field capacitance estimation method that shows the capacitance compensation tendency of the design of etching holes; this method is expected to be applicable to the design in capacitive devices of complementary metal oxide semiconductor–microelectromechanical systems technology.

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Mikami, Yoshiki, Masahito Mochizuki, Terumi Nakamura, Kazuo Hiraoka, and Masao Toyoda. "Application of Numerical Simulation Considering the Effect of Phase Transformation to the Estimation of Hardness Distribution in Welds." Materials Science Forum 512 (April 2006): 379–82. http://dx.doi.org/10.4028/www.scientific.net/msf.512.379.

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This study investigated a method for estimating hardness distribution in welds, considering the effect of phase transformation and weld thermal cycles. Hardness distribution in welds was estimated from fractions and hardness of each microstructure by using rule of mixture. Finite element heat conduction analysis was performed to calculate weld thermal cycles. Microstructures formed corresponding to the thermal cycle were also calculated based on the continuous cooling transformation (CCT) diagram. The method mentioned above was applied to welds of Ultra-Narrow Gap welding process, which was developed for welding of ultrafine-grained steels. The calculated thermal cycles in the welds corresponded with measured results. Moreover, the estimated hardness distribution in the welds, which were estimated by using calculated thermal cycles and the phase fraction of each microstructure, was also in good agreement with measured values.

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Shimansky, Ruslan V., Dmitrij A. Belousov, Victor P. Korolkov, and Roman I. Kuts. "Diffractive Sensor Elements for Registration of Long-Term Instability at Writing of Computer-Generated Holograms." Sensors 21, no. 19 (October 6, 2021): 6635. http://dx.doi.org/10.3390/s21196635.

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The research and development of methods using of the specialized diffractive microstructure sensors embedded in the pattern of computer-generated holograms (CGH) manufactured on circular and X-Y laser writing systems is discussed. These microstructures consist of two parts: one of which is written before the CGH in the field of future hologram and the second one is written during the long-term writing of the CGH. The shift between the first and second part of the microstructure is the trace of the writing errors and allows one to determine and calculate the error of CGH fabrication along both orthogonal coordinates. The developed method is based on the principle of diffraction-based overlay with 1D and 2D built-in diffractive microstructure-sensors. Mathematical modeling and results of experimental test writings of such diffractive microstructure sensors are described. The efficiency of using these types of build-in sensors for the writing errors estimation for CGHs is demonstrated.

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TERAKI, Junichi, Tohru HIRANO, and Kenji WAKASHIMA. "The Estimation of Microstructures in Multiphase Composites by Inverse Analysis." Transactions of the Japan Society of Mechanical Engineers Series A 57, no. 537 (1991): 1222–27. http://dx.doi.org/10.1299/kikaia.57.1222.

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Mrzygłód, B., P. Matusiewicz, A. Tchórz, and I. Olejarczyk-Wożeńska. "Quantitative Analysis of Ductile Iron Microstructure – A Comparison of Selected Methods for Assessment." Archives of Foundry Engineering 13, no. 3 (September 1, 2013): 59–63. http://dx.doi.org/10.2478/afe-2013-0060.

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Abstract Stereological description of dispersed microstructure is not an easy task and remains the subject of continuous research. In its practical aspect, a correct stereological description of this type of structure is essential for the analysis of processes of coagulation and spheroidisation, or for studies of relationships between structure and properties. One of the most frequently used methods for an estimation of the density Nv and size distribution of particles is the Scheil - Schwartz - Saltykov method. In this article, the authors present selected methods for quantitative assessment of ductile iron microstructure, i.e. the Scheil - Schwartz - Saltykov method, which allows a quantitative description of three-dimensional sets of solids using measurements and counts performed on two-dimensional cross-sections of these sets (microsections) and quantitative description of three-dimensional sets of solids by X-ray computed microtomography, which is an interesting alternative for structural studies compared to traditional methods of microstructure imaging since, as a result, the analysis provides a three-dimensional imaging of microstructures examined.

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Heo, Jun-Mu, Seo-Eun Cho, and Seung-Gul Kang. "The Difference in Spectral Power Density in Sleep Electroencephalography According to the Estimation of Total Sleep Time." Chronobiology in Medicine 5, no. 2 (June 30, 2023): 58–63. http://dx.doi.org/10.33069/cim.2023.0010.

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Objective: The discrepancy between self-reported subjective sleep time and objective sleep time varies from person to person, and the mechanism that can explain this discrepancy is unclear. This study aimed to investigate the difference in the spectral power of sleep electroencephalography (EEG) according to the estimation of total sleep time (TST).Methods: Of the 4,080 participants in the Sleep Heart Health Study, 2,363 participants with complete data from polysomnography, morning sleep survey, and spectral power of sleep EEG were included in the analysis. The participants were classified as normo-estimators (estimation of TST <±60 min), under-estimators (underestimation of TST ≤60 min), or over-estimators (overestimation of TST ≥60 min). A fast Fourier transformation was used to calculate the EEG power spectrum for total sleep duration within contiguous 30-s epochs of sleep. The sleep EEG spectral power was compared among the groups after adjusting for potential confounding factors, such as age, sex, proportion of participants with insomnia, apnea-hypopnea index, and TST.Results: Of the 2,363 participants, 1,507 (63.8%), 412 (17.4%), and 444 (18.8%) were assigned to the normo-, under-, and over-estimator groups, respectively. The power spectra during total sleep differed significantly among the groups in the delta (p=0.008) and theta bands (p=0.017) after controlling for potential confounders.Conclusion: Higher delta and theta powers were found in the under-estimators than in the over-estimators. This study suggests that differences exist in the microstructures of polysomnography-derived sleep EEG between these two groups. This study suggests that differences exist in the microstructures of polysomnography-derived sleep EEG based on differences in sleep time estimation.

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JIN, YI, CHENG WANG, SHUNXI LIU, WEIZHE QUAN, and XIAOKUN LIU. "SYSTEMATIC DEFINITION OF COMPLEXITY ASSEMBLY IN FRACTAL POROUS MEDIA." Fractals 28, no. 05 (August 2020): 2050079. http://dx.doi.org/10.1142/s0218348x20500796.

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Microstructures dominate the physical properties of fractal porous media, which means the clarification of complexity types and their assembly are of fundamental importance for static or dynamic purposes. In this work, we identified fractal porous media to dual-complexity systems composed of stationary and scale-invariant complexities as per fractal topography theory, and proposed an open mathematical framework to characterize complexity assembly in microstructures, realized the original complexity, such as random, multi-phase, and multi-type features by the quartet structure generation set (QSGS) algorithm, and unified the behavioral complexity, including the self-similar and self-affine properties by fractal topography model. For demonstration, the control mechanisms on the microstructures from different complexities are discussed, with their physical implications and relations to the physical properties of porous media clarified in principle. The results indicate that our framework is open to arbitrary original and behavioral complexities, and eases the modeling of multi-scale microstructures and the property estimation significantly.

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Graziani, Riccardo, Kyle P. Larson, Richard D. Law, Marc-Antoine Vanier, and James R. Thigpen. "A refined approach for quantitative kinematic vorticity number estimation using microstructures." Journal of Structural Geology 153 (December 2021): 104459. http://dx.doi.org/10.1016/j.jsg.2021.104459.

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Garcia-Mateo, C., F. G. Caballero, C. Capdevila, and C. Garcia de Andres. "Estimation of dislocation density in bainitic microstructures using high-resolution dilatometry." Scripta Materialia 61, no. 9 (November 2009): 855–58. http://dx.doi.org/10.1016/j.scriptamat.2009.07.013.

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Sobczyk, K. "Morphological complexity of material microstructures: From stochastic models to fracture estimation." Probabilistic Engineering Mechanics 23, no. 4 (October 2008): 444–55. http://dx.doi.org/10.1016/j.probengmech.2007.10.013.

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Kar, Arkamitra, Indrajit Ray, Udaya B. Halabe, Avinash Unnikrishnan, and Ben Dawson-Andoh. "Characterizations and Quantitative Estimation of Alkali-Activated Binder Paste from Microstructures." International Journal of Concrete Structures and Materials 8, no. 3 (July 12, 2014): 213–28. http://dx.doi.org/10.1007/s40069-014-0069-0.

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Lu, Guoyang, Zijian He, Pengfei Liu, Zhihao He, Gaoyang Li, Hao Jiang, and Markus Oeser. "Estimation of Hydraulic Properties in Permeable Pavement Subjected to Clogging Simulation." Advances in Civil Engineering 2022 (January 21, 2022): 1–13. http://dx.doi.org/10.1155/2022/5091895.

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Permeable pavements are often affected by pore clogging, which leads to their functional failure and reduced service life. However, the clogging mechanism and its impact on the permeability and complex pore microstructures in pervious pavement remain unclear. The aim of current study is to quantify the clogging behavior in pervious pavement materials and carry out investigations on the development of pore characteristics and permeability. Novel polyurethane-bound pervious mixture (PUPM) was adopted for comparative study in present research with conventional Porous Asphalt (PA). The Aachen Polishing Machine (APM) was selected to perfectly serve as a simulator for clogging process of pavement in the actual service condition. The permeability and pore microstructure of the pervious pavement material were then characterized by using the self-developed permeameter and X-ray Computed Tomography (CT) scanning, respectively. The development of pore characteristics in terms of clogging was experimentally illustrated. Based on the pore characteristics, the flow behavior of PUPM subjected to different clogging periods was predicted based on the developed non-Darcy flow model. The developed experiments and analysis can further strengthen the understanding of the clogging mechanism within the porous pavement material. The results can also serve for the optimization of the pervious pavement design in the engineering application.

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Wejrzanowski, Tomasz, Wojciech Spychalski, Krzysztof Różniatowski, and Krzysztof Kurzydłowski. "Image Based Analysis of Complex Microstructures of Engineering Materials." International Journal of Applied Mathematics and Computer Science 18, no. 1 (March 1, 2008): 33–39. http://dx.doi.org/10.2478/v10006-008-0003-1.

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Image Based Analysis of Complex Microstructures of Engineering MaterialsThe paper presents various methods for quantitative description of material structures. The main focus is on direct methods of description based on image analysis. In particular, techniques for the estimation of the size, shape and spatial distribution of structural elements observed by different microscopic techniques are described. The application of these methods for the characterization of the structures of engineering materials is demonstrated on a stainless steel used in petrochemical installations. It is shown that the methods applied are useful for the assessment of service degradation of materials.

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Koyama, Toshiyuki, and Toru Miyazaki. "An Estimation of the Free Energy of the Microstructures in Aged Alloys." Journal of the Japan Institute of Metals 53, no. 7 (1989): 643–50. http://dx.doi.org/10.2320/jinstmet1952.53.7_643.

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Shen, Yiou, Yan Li, and Feng Lv. "Estimation of the Elastic Modulus and Moisture Absorption of Sisal Fibre." Advanced Materials Research 750-752 (August 2013): 204–9. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.204.

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Microstructures of sisal fibres were revealed optically. Statistics on dimensional parameters for sisal fibres were used to establish a geometrical model in order to estimate the elastic modulus and moisture absorption capability of sisal fibres. The single fibre tensile test was conducted on the sisal. The predicted longitudinal modulus and water absorption was in good agreement with experimental results. It was found that the lumen ratio is a significant factor in determine the mechanical properties of the natural fibre.

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Jeulin, Dominique. "Multi Scale Random Models of Complex Microstructures." Materials Science Forum 638-642 (January 2010): 81–86. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.81.

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Many nanocomposite materials are obtained by dispersing a charge in a matrix. Due to the conditions of mixing, the arrangement of the charge usually presents some heterogeneity at different scales. In order to predict the effective properties of such composites (like the dielectric permittivity or the elastic moduli), it is necessary to know the properties of the two components (charge and matrix), and their spatial distribution. To fulfil this project, we developed a general methodology in several steps: the morphology is summarized by multi-scale random models accounting for the heterogeneous distribution of aggregates. The identification of models is made from image analysis. It is then used for the prediction of effective properties by estimation, or by numerical simulations. Our approach is illustrated by various examples of multi-scale models: Boolean random sets based on Cox point processes and various random grains (spheres, cylinders), showing a very low percolation threshold and therefore a high conductivity or elastic moduli for a low charge content; multi-scale iterations of random media.

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Desai, Meghna, and Thilo Rehren. "Estimating carbon content in crucible steel using image analysis." Historical Metallurgy 54, no. 2 (October 10, 2023): 1–11. http://dx.doi.org/10.54841/hm.664.

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Pre-industrial crucible steel ingots, produced in both Central and South Asia, are an important class of iron-carbon alloys. Their microstructure reflects their formation from a liquid alloy at a carbon content of 1.0–2.5wt%, which is higher than most mild steels but lower than most cast irons. This article introduces a tool to quantify the carbon content of such alloys based on an operator-supervised image analysis which determines the relative proportions of austenite/pearlite and cementite, respectively, from high-contrast back-scatter electron images of unetched samples. Using examples from a recently discovered hoard of crucible steel ingots in Telangana, south-central India, we demonstrate the capabilities of the tool and test its usefulness. The main benefit is in improving accuracy and precision in metallography-based carbon content determination in such alloys by reducing the uncertainty in area estimation in complex microstructures based on visual impression alone.

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Acharya, Srijan, Praveen Gupta, Kaushik Chatterjee, and Satyam Suwas. "Microstructure, Texture and Mechanical Properties after Cold Working and Annealing in a Biomedical Ti-Nb-Ta Alloy." Materials Science Forum 941 (December 2018): 2465–70. http://dx.doi.org/10.4028/www.scientific.net/msf.941.2465.

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β titanium alloys, comprising alloying elements such as Nb, Ta, Zr, are considered promising materials for use in orthopedic applications, as the lower elastic modulus of these alloys, reduces the chance of implant failure caused by stress shielding. The mechanical behavior of these alloys depend on the composition as well as the stability of the phases. In the present study, the effect of cold rolling and subsequent annealing on the microstructure, texture and mechanical behavior of a Ti-Nb-Ta-O alloy has been investigated. Structural characterization was done using x-ray diffraction (XRD) and optical microscopy. Mechanical properties were evaluated by estimation of hardness and elastic modulus. The results show that, (1) the alloy contains single-phase β microstructure in both deformed as well as annealed condition with no evidence of deformation induced phase transformation, (2) the microstructures of cold worked alloy become increasingly inhomogeneous with dominance of shear bands at higher rolling strains, (3) high value of hardness to modulus ratio could be obtained in the present alloy due to stability of β phase and interstitial strengthening.

31

Макаренко, Константин, Konstantin Makarenko, Дмитрий Илюшкин, and Dmitriy Ilyushkin. "FRACTAL ANALYSIS OF MICROSTRUCTURES IN GRAPHITIZED CAST IRON." Bulletin of Bryansk state technical university 2016, no. 1 (March 31, 2016): 34–43. http://dx.doi.org/10.12737/18185.

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The dimensionaltopological parameters of a structure such as size, shape, quantity and distribution characterizing a graphite phase in cast iron exert a significant influence upon material properties. But, the definition of these parameters according to the system presented in SARS 3443-87, to the considerable extent, depends upon human factor. The use of results of such an analysis does not allow creating adequate simulators for the estimation of correlation of structure and properties. The widespread introduction of computer analysis methods for the control of material structures dictates new requirements to the development of methods using a mathematical description of material phase structure. One of the methods based on a multifractal analysis of cast iron microstructure representation is shown in this paper. Data obtained at the use of carbon fleck fractal identification method can be used at the development of simulators of the correlation in structure graphitized cast iron properties.

32

Cao, Furong, Huizhen Guo, Nanpan Guo, Shuting Kong, and Jinrui Liang. "Room-Temperature Strengthening, Portevin-Le Chatelier Effect, High-Temperature Tensile Deformation Behavior, and Constitutive Modeling in a Lightweight Mg-Gd-Al-Zn Alloy." Materials 16, no. 4 (February 16, 2023): 1639. http://dx.doi.org/10.3390/ma16041639.

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To explore room-temperature strengthening and high-temperature ductility, a lightweight novel Mg-1.85Gd-0.64Al-0.62Zn alloy was fabricated by innovative multidirectional forging and a hot-rolling technique. Microstructures and mechanical properties were studied at room and elevated temperatures with an optical microscope, an X-ray diffractometer, and a tensile tester. An ultimate tensile strength of 260 MPa, yield strength of 171 MPa, and elongation of 20.4% were demonstrated at room temperature. The room-temperature strengthening mechanisms were identified by strengthening the model estimation. A type C Portevin-Le Chatelier effect was discovered and elucidated in this alloy. X-ray diffraction analysis revealed that the phase composition is α-Mg solid solution and (Mg, Al)3Gd, Al7Zn3, and Al2Gd intermetallic compounds. Examination of the microstructure at elevated temperatures revealed that dynamic recrystallization and dynamic grain growth occur. In particular, it was discovered that bimodal microstructures or incomplete dynamic recrystallization microstructures exist in high-temperature deformation. A maximum quasi-superplasticity of 228.4% was demonstrated in this alloy at 673 K and 5.0 × 10−4 s−1. Flow stress curves showed that the present alloy exhibits Sotoudeh–Bate curves or a long intermediate strain-hardening stage followed by a strain-softening stage. A modified Zerilli–Armstrong constitutive equation incorporating the number of dislocations was established. The power-law constitutive equation was established to identify the deformation mechanism. Both constitutive models had good predictability. At 673 K and 5.0 × 10−4 s−1, the stress exponent was 4, and the average deformation activation energy was 104.42 kJ/mol. The number of dislocations inside a grain was 146. This characteristic evidence confirmed that dislocation motion controlled by pipe diffusion dominates the rate-controlling process under this condition.

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Velilla-Díaz, Wilmer, Luis Ricardo, Argemiro Palencia, and Habib R. Zambrano. "Fracture Toughness Estimation of Single-Crystal Aluminum at Nanoscale." Nanomaterials 11, no. 3 (March 9, 2021): 680. http://dx.doi.org/10.3390/nano11030680.

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In this publication, molecular dynamics simulations are used to investigate the fracture behavior of single-crystal aluminum. The stress intensity factor is estimated by means of four different methods, the accuracy is assessed for each approach and the fracture toughness is estimated. The proposed methodology is also applied to estimate the fracture toughness for graphene and diamond using published data from other scientific articles. The obtained fracture toughness for the single-crystal aluminum is compared with other nanomaterials that have similar microstructures. Dislocation emission during the fracture simulation of the cracked nano-crystal of aluminum is analyzed to study the fracture behavior. Brittle fracture behavior is the predominant failure mode for the nanomaterials studied in this research.

34

Yoda, Mitsuhiro, and Satoshi Konishi. "Estimation of an open-loop compact adaptive passive noise control system with microstructures." Journal of the Acoustical Society of America 110, no. 1 (July 2001): 638–41. http://dx.doi.org/10.1121/1.1379077.

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35

Lee, Young Jung, Byung-Hoon Lee, Gil-Su Kim, Dae-Gun Kim, Deok-Soo Kim, and Young Do Kim. "Evaluation of conductivity in W–Cu composites through the estimation of topological microstructures." Materials Letters 60, no. 16 (July 2006): 2000–2003. http://dx.doi.org/10.1016/j.matlet.2005.12.113.

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36

Kim, Se-Yun, Ji-Su Kim, Jae Hun Lee, Jong Hak Kim, and Tong-Seok Han. "Phase Stiffness Estimation of Two-phase Pebax/PBE Membranes Using Reconstructed 3D Microstructures." Multiscale Science and Engineering 2, no. 2-3 (July 15, 2020): 143–52. http://dx.doi.org/10.1007/s42493-020-00041-6.

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37

Ohser, Joachim, Claudio Ferrero, Oliver Wirjadi, Alina Kuznetsova, Jochen Düll, and Alexander Rack. "Estimation of the probability of finite percolation in porous microstructures from tomographic images." International Journal of Materials Research 103, no. 2 (February 2012): 184–91. http://dx.doi.org/10.3139/146.110669.

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38

Tewari, A., and A. M. Gokhale. "Efficient estimation of number density in opaque material microstructures: the large-area disector." Journal of Microscopy 200, no. 3 (December 2000): 277–83. http://dx.doi.org/10.1046/j.1365-2818.2000.00759.x.

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39

Gonchar, A. V., M. S. Anosov, and D. A. Ryabov. "Estimation of Structural Degradation of the Heat Affected Zone of the Welded Joint Under Fatigue." Russian Journal of Nondestructive Testing 58, no. 9 (September 2022): 790–99. http://dx.doi.org/10.1134/s1061830922090066.

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Abstract We consider the features of using modern nondestructive methods for assessing structural degradation in the process of elastic-plastic cyclic loading of normalizing (average grain size 10 μm) and overheating (average grain size 45 μm) zones of the heat affected zone of St3 steel. In this case, the approaches of digital image processing of microstructures, fractal analysis, and ultrasonic and magnetic testing were used. The features of the stages of degradation of the structure under fatigue and the corresponding behavior of the numerical microstructure parameters such as fractal dimension and the concentration and fraction of defects and slip bands are analyzed, as well as changes in the elastic properties of the material under study (determining an acoustic parameter that takes into account the complex change in the velocities of longitudinal and transverse waves) and the coercive force. It has been established that cyclic loading of samples from the sections of the heat affected zone leads to the formation of a large number of structural defects in the form of deformation bands, discontinuities, and microcracks, the occurrence of which is accompanied by a considerable change in the numerical microstructure characteristics (a decrease in the value of fractal dimension) as well as elastic (a decrease in the values of acoustic parameters) and magnetic (an increase in coercive force) properties. It is also shown that cyclic loading of the material under study leads to an increase in microhardness. However, the nature of such an increase for overheating and normalizing zones is different. The results of the research can be applied to the problems of diagnosing premature destruction and monitoring the most loaded zones of St3 steel structures to determine the residual resource.

40

Chen, Hongsheng, Chongsheng Long, Hongxing Xiao, Tianguo Wei, and Guan Le. "Estimation of the chemical compositions and corresponding microstructures of AgInCd absorber under irradiation condition." Nuclear Engineering and Technology 52, no. 2 (February 2020): 344–51. http://dx.doi.org/10.1016/j.net.2019.07.021.

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41

Velichko, A., A. Wiegmann, and F. Mücklich. "Estimation of the effective conductivities of complex cast iron microstructures using FIB-tomographic analysis." Acta Materialia 57, no. 17 (October 2009): 5023–35. http://dx.doi.org/10.1016/j.actamat.2009.07.004.

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42

Han, Myounghee, Yongjoo Kim, Jang Ryul Park, Benjamin J. Vakoc, Wang-Yuhl Oh, and Sukyoung Ryu. "Retinal Blood Vessel Caliber Estimation for Optical Coherence Tomography Angiography Images Based on 3D Superellipsoid Modeling." International Journal of Image and Graphics 19, no. 02 (April 2019): 1950011. http://dx.doi.org/10.1142/s0219467819500116.

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Changes of retinal blood vessel calibers may reflect various retinal diseases and even several non-retinal diseases. We propose a new method to estimate retinal vessel calibers from 3D optical coherence tomography angiography (OCTA) images based on 3D modeling using superellipsoids. Taking advantage of 3D visualization of the retinal tissue microstructures in vivo provided by OCTA, our method can detect retinal blood vessels precisely, estimate their calibers reliably, and show the relative flow speed visually.

43

Masmoudi, Mohamed, Wahid Kaddouri, Kaouther Bourih, Abdellah Bourih, and Salah Madani. "A Multi-Scale Homogenization Procedure for the Estimation of Young’s Modulus of Porous Materials by a Multi-Void Shape Model." Revue des composites et des matériaux avancés 32, no. 4 (August 31, 2022): 165–72. http://dx.doi.org/10.18280/rcma.320401.

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Transversal cross-section pores of lotus-type porous materials are generally considered circular; however, they exhibit various pore geometries, which affect their effective properties. The main objective of this work is to develop a generalized model which allows estimating the effective Young’s modulus of multi-void shape porous microstructures by exploiting a relationship developed to evaluate the effective Young’s modulus of porous materials with single-void shape. A procedure based on free software is then proposed to allow the application of the proposed generalized model on real lotus-type porous material images to estimate the effective Young’s modulus. The free tool allows the processing of real porous materials images to obtain multi-void shape microstructures and their pores parameters data. The validation of the generalized model has been established by confronting the obtained results with experimental data taken from literature; an excellent agreement was observed. Therefore, it can be concluded that the proposed procedure associated with the generalized model can be used efficiently for predicting the effective Young’s modulus of the multi-void porous materials, particularly lotus-type porous materials.

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Ohser, Joachim, Claudia Redenbach, and Katja Schladitz. "MESH FREE ESTIMATION OF THE STRUCTURE MODEL INDEX." Image Analysis & Stereology 28, no. 3 (May 3, 2011): 179. http://dx.doi.org/10.5566/ias.v28.p179-185.

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The structure model index (SMI) is a means of subsuming the topology of a homogeneous random closed set under just one number, similar to the isoperimetric shape factors used for compact sets. Originally, the SMI is defined as a function of volume fraction, specific surface area and first derivative of the specific surface area, where the derivative is defined and computed using a surface meshing. The generalised Steiner formula yields however a derivative of the specific surface area that is – up to a constant – the density of the integral of mean curvature. Consequently, an SMI can be defined without referring to a discretisation and it can be estimated from 3D image data without need to mesh the surface but using the number of occurrences of 2×2×2 pixel configurations, only. Obviously, it is impossible to completely describe a random closed set by one number. In this paper, Boolean models of balls and infinite straight cylinders serve as cautionary examples pointing out the limitations of the SMI. Nevertheless, shape factors like the SMI can be valuable tools for comparing similar structures. This is illustrated on real microstructures of ice, foams, and paper.

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Ogierman, Witold, and Grzegorz Kokot. "Analysis of Strain Field Heterogeneity at the Microstructure Level and Inverse Identification of Composite Constituents by Means of Digital Image Correlation." Materials 13, no. 2 (January 8, 2020): 287. http://dx.doi.org/10.3390/ma13020287.

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The present paper is devoted to the theoretical study on the estimation of the full-field strain at the microstructural level of composite materials by means of Digital Image Correlation (DIC). The main aim of the paper is to investigate the influence of speckle size on the accuracy of the strain field measurement at the microscale. The DIC analysis was conducted based on artificial speckle patterns generated numerically and the deformation behavior of the composites was simulated by using the finite element method (FEM). This approach gives the opportunity to compare the results of the DIC in terms of speckle size with the reference FEM solution. Moreover, the paper focuses on the inverse identification of the material constants of the composite constituents by using information associated with the measured strain field. The inverse problem is solved by using a novel two-step optimization procedure, which reduces the problem complexity. The feasibility and accuracy of the proposed approach are presented by analysis of two exemplary microgeometries representing the microstructures of fiber reinforced composites.

46

Tanaka, M., Y. Kimura, A. Kayama, L. Chouanine, Reiko Kato, and J. Taguchi. "Image Reconstruction and Analysis of Three-Dimensional Fracture Surfaces Based on the Stereo Matching Method." Key Engineering Materials 261-263 (April 2004): 1593–98. http://dx.doi.org/10.4028/www.scientific.net/kem.261-263.1593.

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A computer program of the fractal analysis by the box-counting method was developed for the estimation of the fractal dimension of the three-dimensional fracture surface reconstructed by the stereo matching method. The image reconstruction and fractal analysis were then made on the fracture surfaces of materials created by different mechanisms. There was a correlation between the fractal dimension of the three-dimensional fracture surface and the fractal dimensions evaluated by other methods on ceramics and metals. The effects of microstructures on the fractal dimension were also experimentally discussed.

47

Lee, Minhui, Youngseuk Keehm, and Dahee Song. "Quantitative analysis of resolution and smoothing effects of digital pore microstructures on numerical velocity estimation." Geosciences Journal 21, no. 3 (May 9, 2017): 431–40. http://dx.doi.org/10.1007/s12303-017-0102-9.

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48

Hirano, Tohru, and Kenji Wakashima. "Mathematical Modeling and Design." MRS Bulletin 20, no. 1 (January 1995): 40–42. http://dx.doi.org/10.1557/s0883769400048922.

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For the design of functionally gradient materials (FGMs), necessary material properties, such as thermal-expansion-coefficient and Young's modulus in the specific region, are optimized by controlling the distribution profiles of composition and microstructures, as well as micropores in the materials. For this purpose, our research team employs the inverse design procedure in which both the basic material combination and the optimum profile of the composition and microstructures are determined with respect to the objective structural shape and the thermomechanical boundary conditions. Figure 1 shows the inverse design procedure for FGM, in which the final structure to be developed, as well as the boundary conditions, are specified first. After the fabrication method and an allowable material combination are selected from the FGM database, the estimation rules for the material properties of the intermediate compositions are determined based upon the micro-structure. Then, the temperature distribution and the thermal-stress distribution are calculated with the assumed profiles of the distribution functions for the constituents. Other possible combinations and different profiles are also investigated until the optimum is obtained.

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Behrmann, Ole, Thomas Lisec, and Björn Gojdka. "Towards Robust Thermal MEMS: Demonstration of a Novel Approach for Solid Thermal Isolation by Substrate-Level Integrated Porous Microstructures." Micromachines 13, no. 8 (July 26, 2022): 1178. http://dx.doi.org/10.3390/mi13081178.

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Most current thermal MEMS use fragile structures such as thin-film membranes or microcantilevers for thermal isolation. To increase the robustness of these devices, solid thermal insulators that are compatible with MEMS cleanroom processing are needed. This work introduces a novel approach for microscale thermal isolation using porous microstructures created with the recently developed PowderMEMS wafer-level process. MEMS devices consisting of heaters on a thin-film membrane were modified with porous microstructures made from three different materials. A thermal model for the estimation of the resulting thermal conductivity was developed, and measurements for porous structures in ambient air and under vacuum were performed. The PowderMEMS process was successfully used to create microscale thermal insulators in silicon cavities at the wafer level. Measurements indicate thermal conductivities of close to 0.1 W/mK in ambient air and close to 0.04 W/mK for porous structures under vacuum for the best-performing material. The obtained thermal conductivities are lower than those reported for both glass and porous silicon, making PowderMEMS a very interesting alternative for solid microscale thermal isolation.

50

Wu, Ming, Krishna Kumar Saxena, Zhongning Guo, Jun Qian, and Dominiek Reynaerts. "Fast Fabrication of Complex Surficial Micro-Features Using Sequential Lithography and Jet Electrochemical Machining." Micromachines 11, no. 10 (October 20, 2020): 948. http://dx.doi.org/10.3390/mi11100948.

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This paper presents fabrication of complex surficial micro-features employing a cross-innovative hybrid process inspired from lithography and Jet-ECM. The process is referred here as mask electrolyte jet machining (MEJM). MEJM is a non-contact machining process which combines high resolution of lithography and greater flexibility of Jet-ECM. It is a non-contact process which can fabricate variety of microstructures on difficult-to-machine materials without need of expensive tooling. The presented work demonstrates the process performance of this technology by statistical analysis and multivariate kernel density estimation (KDE) based on probabilistic density function. Micro-letters are fabricated as an example of complex surficial structure comprising of multiple intersecting, straight and curved grooves. The processing response is characterized in terms of geometrical size, similarity ratio, and cumulative shape deviation. Experimental results demonstrated that micro letters with good repeatability (minimum SD of shape error ratio 0.297%) and shape accuracy (minimum shape error of 0.039%) can be fabricated with this technology. The results suggest MEJM could be a promising technology for batch manufacturing of surface microstructures with high productivity.

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