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The foundation of offshore wind turbines is an important factor that determines their bearing capacity and service life. A theoretical analysis and model test of the bucket foundation with and without bulkheads at a scale of 1:150 are conducted in this study. The frequency-domain impedances of the two models were obtained and compared via cyclic loading tests at different frequencies. When the loading frequency was low, the absolute values of the real and imaginary impedances of the foundation model without a bulkhead in the frequency domain were higher than those of the foundation model with a bulkhead. Based on the analysis of the variation in soil pressure at the top of the bucket, it was found that the variation in soil pressure almost alternated with the cyclic load. The adsorption force is beneficial for the bearing capacity of a composite bucket foundation, making the structure safer. The impedance matrix of the foundation is determined by the size and shape of the foundation, mechanical parameters of the foundation medium, and frequency of the forced vibration. Wolf's lumped-parameter model was evaluated for applicability to analyse the bucket foundations with bulkheads. • A theoretical analysis and model test of the bucket foundation with and without bulkheads are conducted. • The frequency-domain impedances of the two models are obtained and compared via cyclic loading tests at different frequencies. • The adsorption force is beneficial for the bearing capacity of a composite bucket foundation, making the structure safer. [ABSTRACT FROM AUTHOR]

This paper aims to use machine learning (ML) based on a regression algorithm to predict the damage degree of a concrete-filled double-skin steel tubular column (CFDST) after explosion. Three classical single learning algorithms and five excellent ensemble learning algorithms were used to train 2476 sets of data. Five regression indicators were used to evaluate and compare the effectiveness and accuracy of the ML model. The results show that the integrated CatBoost model is superior to the other models, and the model performances are ranked as CatBoost > LightGBM > XGBoost > GBDT > MLP > RF > SVR > DT. Shapley Additive exPlanations (SHAP) is used to explain the contribution of each feature parameter to CatBoost prediction results. Finally, the CatBoost model is used to predict the collected test data, and R2 = 0.989, MSE = 2.98 × 10−6, RMSE = 0.00172, MAE = 0.00151, and MAPE = 7.4% are obtained. This shows that the model has high prediction accuracy and can accurately predict the damage degree after CFDST explosion. • An extensive database of CFDST columns subjected to the close-in explosion is established. • Three classical single learning algorithms and five excellent integrated learning algorithms are used to predict the damage degree of concrete-filled double-skin steel tubular column (CFDST) columns under close-in explosion loads. • After model training and evaluation, the CatBoost model has the best accuracy among the eight models. • The global and local interpretation of the CatBoost model is carried out through the Shapley Additive exPlanations(SHAP), and the influence of different input parameters on the model is visualized. • In the actual damage assessment, compared with the problem that the traditional P-I curve regression formula can only obtain the damage degree of the CFDST column, the CatBoost model can obtain accurate damage conditions. [ABSTRACT FROM AUTHOR]

Generally speaking, in the melting process of alumina ceramics, all the metastable transitional phase will be gradually transformed into the stable α phase with rising temperature due to an irreversible lattice reconstruction. However, under the action of pulsed laser cutting, the lattice structure of α-alumina needs to withstand the great stress from instantaneous high energy impact. Thus, a slip dislocation of 1/4 at. diameter is generated on the atomic plane of each second basal layer to produce γ-alumina. In this work, a ceramic plate comprised of α-alumina is taken as the object of study. The α-to-γ reverse phase transformation of the molten removal is verified by the observed microstructure from scanning electron microscope (SEM) and transmission electron microscope (TEM). Simultaneously, the X-ray diffraction (XRD) investigation shows that the basis of molten removal after laser cutting is still α-alumina. The micrographs of octahedral corners or hexagons are shown in different observation directions. There is no γ-alumina phase transformation product in the spherical granular removal at each vapor-to-melt ratio (r vmr ). In contrast, γ-alumina is detected in the adhering slag with a micro-morphology of cubic phase. The mass fraction is increased with the rising of vapor-to-melt ratio. At the same time, θ-alumina also exists in some spattering removal as intermediate product between α and γ phase. It is indicated that the generation of α-to-γ reverse phase transformation occurs mainly in the melting process of temperature rise, and the maintenance of phase transformation results mainly occurs during cooling process of condensation. [ABSTRACT FROM AUTHOR]

Because of the multiple selections on different crystalline faces in nucleation process of α-alumina, it is necessary to confirm the nucleation mode and growth mechanism of molten removal particles produced by alumina ceramics laser cutting. A model based on driving force of Helmholtz and Gibbs free energies is built to compare different critical nucleation sizes and corresponding nucleation barriers among several crystal planes. The calculation shows that when alumina ceramic is cooled and solidified from a molten state, the material is preferably nucleated in the parallelepiped model with extension and stack along the ( 11 2 ¯ 0 ) plane. X-ray diffraction and scanning electron microscopy detections are taken to verify the nucleation mode that the morphologies thereof are shown as corners of an octahedron or edges of hexagons in different section directions. A pyramid stacking growth mode of spherical particles is proposed to coincide with the hollow micro morphology. The analysis concludes this model is feasible and it makes contribution to the potential application of removal particles for the field of ceramic powder metallurgy during laser processing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Secondary oxidation was foremost stage for unique flavor formation in salted egg yolk. • Primary oxidation directly inhibited the accumulation of aldehydes and ketones. • Primary oxidation indirectly produced beneficial volatiles by changing metabolites. • Secondary oxidation induced the synthesis of flavor precursors in salted egg yolk. • Amino acid metabolism etc. induced by secondary oxidation formed salted egg yolk flavor. To explore the contribution of different lipid oxidation stages to flavor formation in salted egg yolk, potential pathways of flavor formation were characterized by multi-omics strategy and partial least squares structural equation model (PLS-SEM). 72 lipids, 135 metabolites and 5 volatiles related to lipid oxidation were screened out. The degradation of aldehydes and ketones, and the generation of tryptamine and elaidic acid, etc. were promoted by triglycerides (TG) (10:0 16:0 18:1), triglycerides (TG) (18:0 20:1 22:0), etc. at primary and secondary oxidation stage, respectively. The generation of acetophenone, thianaphthene, etc. through the pathway of 2-phenylacetamide, hexanoylcarnitine, etc. was facilitated by these triglycerides (TG) at primary oxidation stage. Furthermore, amino acid metabolisms, pentose phosphate pathway and linoleic acid metabolism occurred at secondary oxidation stage were key pathways to form distinctive flavor. In conclusion, secondary oxidation stage may be more important for the formation of unique flavor (taste) in salted egg yolk. [ABSTRACT FROM AUTHOR]

Abstract: The deformation and failure behaviors of brittle or quasi-brittle solids are closely related to interaction and propagation of stochastically distributed microcracks. The influence of microcrack interaction and evolution on the mechanical properties of materials presents a problem of considerable interest, which has been extensively argued but has not been resolved as yet. In the present paper, a novel numerical method is used to calculate the effective elastic moduli and the tensile strength, and to simulate the failure process of brittle specimens containing numerous microcracks. The influences of some crack distribution parameters reflecting the non-uniform spatial concentration, size and orientation distributions are examined. The effective elastic moduli and the tensile strength of brittle materials exhibit different dependences on microcrack interaction. For example, two microcrack distributions that lead to the identical effective elastic moduli may cause a pronounced difference in the tensile strengths and failure behaviors of materials. By introducing two criteria for microcrack growth and coalescence in terms of Griffith’s energy release rate, the above numerical method is extended to simulate the coalescence process of microcracks that results in a fatal crack and the final rupture of a specimen. [Copyright &y& Elsevier]

The problem of an interface crack between dissimilar piezoelectric layers under mechanical and electrical impacts is formulated by using integral transform and Cauchy singular integral equation methods. The dynamic stress intensity factor and dynamic energy release rate (DERR) are determined through use of the obtained solutions and the effects of the loading ratio, the geometry of crack configuration and the combination of material parameters on the above two quantities are discussed. The numerical calculations indicate that the electrical load can promote or retard the crack growth depending on its magnitude, direction and the existence of the mechanical load and that with the increase of the value of ratio of two material parameters, some material parameters will inhibit the crack growth. On the other hand, some material parameters play the contrary roles. In addition, the geometry of the crack configuration has the significant effects on the DERR. Finally the results are compared with those obtained in a previous investigation. [Copyright &y& Elsevier]

• Novelly developed shear-thickening guar gum hydrogel based media for AFM is proposed in this paper. • A new model for the calculation of shear rate under shear-thickening condition is established and validated. • Surface roughness in terms of Ra using this media reduces from 120.12 nm to 6.48 nm, with a mirror surface obtained. • The conclusions show that shear thickening in AFM is an efficient way to develop the polishing efficiency and quality. Abrasive flow machining (AFM) is a non-traditional finishing method by extruding abrasive media through workpieces' surfaces. In AFM process, the machining capacity of traditional shear-thinning media will be reduced with the decline of viscosity at high shear rate condition. Additionally, the environmental-friendly property of traditional oil-soluble media is poor as the recycling of the media is difficult. In this paper, with an attempt to apply shear thickening to AFM, a novel type of guar gum hydrogel based media with shear-thickening property is proposed. To investigate its shear-thickening and finishing performance, a model of identifying the shear-thickening behavior in AFM is established. Results of the validation experiment show that the model can identify and predict the experimental conditions accurately, and the simulation results are approximately some with the model results. Results of AFM experiments show that finely polished surface can be obtained in the AFM process utilizing this new media. Compared with styrene-butadiene rubber based media (traditional shear-thinning media for AFM), guar gum hydrogel based media can obtain a better finished surface under shear-thickening condition. With shear rate increasing from shear-thinning phase to shear-thickening phase, material removal rate for AISI316 stainless steel in the experiment utilizing this new media increases from 69 mg/h to 351 mg/h, and surface roughness in terms of Ra under shear-thickening condition reduces from 120.12 nm to 6.48 nm. [ABSTRACT FROM AUTHOR]

Abstract: Surface quality of the workpiece has great influence on its service performance and lifespan. Pulse electrochemical finishing (PECF) provides an effective method for improving surface quality of the workpiece. In PECF, surface irregularities are removed by electrochemical dissolution rather than by cutting force. Due to non-contact nature of the process, there is no residual stress and thermal effect on the workpiece surface. For successful utilization of PECF, in present manufacturing, it still demands for more intensive research, including the mechanism of anodic smoothing. The anodic smoothing characteristics of PECF are analyzed through a developed mathematical model. The main influencing factors such as the finishing time, the interelectrode gap, the applied voltage and the rotational speed of electrode have been examined. The predictive values based on the developed mathematical model are found to be in reasonable agreement with the experimental values. The surface roughness Rz ranges from 3μm to 1.22μm. The research achievement through various parametric studies can be used as a guideline for the operation of a PECF system. [Copyright &y& Elsevier]

Abstract Abrasive flow machining (AFM) is a non-traditional surface finishing method by extruding abrasive media through workpieces' surfaces. It is difficult to implement uniformity and controllability for material removal in AFM, which makes predictions of material removal and its distribution along media flow direction significantly imperative. In this paper, a new predictive model for material removal in AFM is proposed based-on combination of material removal model for single abrasive and statistics model of active abrasives. To validate its applicability, two experiments are conducted to calibrate the material removal model, and another two experiments are carried out to validate the calibrated material removal model. Results show that this model can predict material removal in terms of profile height variation Δ H and variation trend of mass variation Δ M precisely, with predictive error (δ error) of 6.4% and 6.9% achieved in the validation experiments. In the case that the workpiece and flow channel are given, the variation of profile height Δ H on the workpiece surface shows consistent distribution trend with the distribution of the pressure and media flow velocity on the workpiece surface. Highlights • A material removal model is proposed to predict distribution of material removal along flow direction in AFM process. • A repositioning method is proposed to gauge material removal by measuring profiles before and after AFM process. • Predictions of material removal distribution in terms of profile height variation Δ H are justified by validation experiments. • Relationship between distribution of material removal and pressure field of abrasive media flow is established. [ABSTRACT FROM AUTHOR]

[Display omitted] • The sedimentation velocity decreases first with particle volume fraction but then increases. • The inelastic collisions are the main interactions between particles. • The velocity equation is corrected by the effective diameter coefficient of aggregation. • The particle dynamic behavior and sedimentation in high-viscosity fluids were observed in micro-scale. To further understand the characteristics of particle–fluid flow, the particle sedimentation process in a high-viscosity fluid is conducted with both experimental and numerical methods. In this work, inelastic collisions between particles during the sedimentation process are observed. Different from the sedimentation in a low-viscosity fluid, the increase of particle sedimentation velocity can be found due to the inelastic collisions in a high-viscosity fluid. This phenomenon is more obvious with the increase of the particle volume fractions and the viscosity of the fluid. The necessary conditions for the inelastic collision phenomenon are determined based on the viscous dissipative dynamics of particle collisions. According to the experimental and numerical results, the interactions between particles in high-viscosity liquids are mainly the inelastic collisions which caused the particle aggregation. The correction coefficient of particle sedimentation velocity equation is obtained, and the applicability of the equation for the sedimentation in a high-viscosity fluid is improved. [ABSTRACT FROM AUTHOR]