Technology and Theory of Mechanically Activated Water in Bakery Industry

Introduction. Bakery products are an important part of traditional Russian menu. Activated water helps to improve the quality of flour products. The present research objective was (1) to activate water with mechanical energy to change the physicochemical properties of the dough; (2) to evaluate the energy efficiency of the new technological process, and (3) to determine the quality indicators of bread. Study objects and methods. The research featured high quality wheat flour, drinking water, and pressed baking yeast (Saccharomyces cerevisiae). Standard research methods were used to assess the physical and chemical properties of water, namely acidity index (pH), surface tension coefficient, and biological activity. The physico-chemical properties of the dough were studied by maximum shear stress and adhesion. Results and discussion. The samples of activated water demonstrated the following technological properties. Its acidity due decreased as pH fell down to 6.05. With a total mixing time of 10 min, the surface tension decreased by about 10%; after 5 min, it decreased by 4%, while the biological activity of activated water increased by 1.5 times. Mechanically treated water used for bread production contributed to the overall energy saving during kneading and increased its water-binding ability. Moisture removal was by 30–40% more intensive than in the control dough sample. Also, the quality of gluten changed as a result of higher shear stress, which gave the experimental dough better forming properties necessary for the production of high-quality bread. The mechanically activated water increased the specific volume of bread from 2.05 to 2.38 cm3/g. Conclusion. The activated water improved the physico-chemical and rheological properties of dough, as well as the main sensory indicators of bread, e.g. porosity and bread crumb elasticity.

Numerical Simulation on the Effect of Rock Joint Roughness on the Stress Field

In view of the influence of Joint Roughness Coefficient (JRC), which is for quantitative description of the joint surface roughness, on the stress field of the rock mass, compression test and shear-compression test were simulated on models with different joint roughness. The photoelasticity technique is applied to examine the feasibility of numerical simulation. The results show that numerical simulation results are in agreement with the results of photoelastic experiments. The stress concentration area is distributed near the joint plane. Thus, the joint plane controls the shear strength of the rock. In compression test, the maximum shear stress of the model is proportional to JRC and the normal pressure. In shear-compression test, when the ratio of the axial shear to the normal pressure is small, the maximum shear stress is nonlinearly positively correlated with JRC. When the ratio of the axial shear to the normal pressure is relatively large, the relationship curve between the maximum shear stress and JRC is parabolic. When the JRC is small, as the ratio of the axial shear force to the normal pressure increases, the maximum shear stress changes abruptly, and the maximum shear stress after the mutation decreases significantly. The reason is that the upper and lower parts of the model have slipped, resulting in a redistribution of stress. In addition, when the JRC is 6 to 12, it is more likely to cause stress concentration.

Effects of Grain Boundary Angles on Initial Deformation of 304 Austenitic Stainless Steel under Nanoindentation: A Molecular Dynamics Simulation

Nitrogen-containing 0Cr19Ni10 (304 NG) austenitic stainless steel plays a significant role in Generation IV reactor pressure vessels. The structure and properties of 304 NG are heavily influenced by the grain boundaries (GBs), especially the initial mechanical response and dislocation evolutions. Hence, in this paper, we carried out molecular dynamics (MD) simulations to investigate the effects of the GB angles on the initial deformation of 304 models under nanoindentation. It is found that the GB angle has great effects on the mechanical properties of 304 NG. With the GB angles changing from 90° to 150°, the values of Young’s modulus and maximum shear stress first decrease and then increase due to decreasing of the interaction among the GBs and the grain interiors (GIs) and the smoother shape of GBs. The hardening region slope decreases rapidly result from the GB angles changing the grain size on the both sides, which fully fits the Hall–Petch relationship. After the dislocations reaching the GBs along the slip system, the dislocation piles-up on the GBs at first, and then GBs serve as a source of dislocation and emit dislocation to free surface with the depth of nanoindentation increasing. This work provides a better understanding on the angle effects of GBs in materials.

Parametric stress-strain analysis for upstream slope of the asphaltic concrete core rockfill dams in static state

In this study, the effects of various geometric parameters of a dam in 2D static analysis of stress-strain on the upstream slope of the asphaltic concrete core rockfill dams were investigated. For this purpose, first the geometric characteristics of a large number of world's dams were collected and assessed, then by geometric modeling of these dams, many numerical models were developed for static analysis using GeoStudio software in eight height classes, three cases of upstream and downstream slopes, three different shape and thickness of the asphaltic concrete core under different Impounding states including "Full Reservoir", "Half full Reservoir", "End of construction and "Rapid Drawdown on a rigid type of foundation. The results of this study demonstrated that in four different construction and impounding states and in three different cases of slopes, Increasing the height parameter, causes increasing the Maximum total stress, Maximum total strain, Shear strain and Maximum shear stress for all construction and impounding states. The Maximum total stress decreased for all operating situations as the upstream slope reduced. According to the obtained results from the static stress-strain analysis, increasing both vertical and inclined asphaltic concrete core thicknesses, leads to decreasing the Maximum shear stress in Full Reservoir state but it increases in other state of impoundment. Moreover, by comparing the displacements related to specified points on the upstream slopes, increasing the height parameter, leads to increasing both horizontal and vertical displacements, the volumetric strain, deviator strain and deviator stress for all impounding conditions. In the following, the additional results were provided along with diagrams for further analysis.

Study on the Influence and Law of Waterproof System Design Factors on the Typical Stress of Bridge Deck Pavement

To improve the structural design rationality of cement concrete bridge deck pavement systems and reduce diseases such as interlayer displacement and rutting in the early stage of bridge deck use, this paper studies the influence and law of the coupling effect of various factors of the waterproof system on the typical stress of bridge deck pavement and determines the best structure combination for the bridge deck pavement structure. A finite element model was established by using commercial software to simulate the mechanical response of different types of waterproof bonding layer, waterproof leveling layer, and impervious structure layer under different parameters. The simulation results show that when the thickness of the pavement layer was 8 cm, the maximum shear stress of the pavement layer occurred in the middle of the wearing course and the junction between layers. When the pavement layers were continuous, the maximum strain of the waterproof bonding layer with the “rubber asphalt + protective plate” structure in the transverse and longitudinal directions was the largest. When the waterproof leveling layer was cement concrete, the structure bore a large amount of stress and easily produced cracks, resulting in water damage. High-density water-based asphalt concrete with a low permeability coefficient can reduce the interlayer shear stress and effectively ensure the interlayer bonding effect. On this basis, the following bridge deck pavement structure was proposed: waterproof system + multifunctional waterproof layer + load-bearing structure layer + surface functional layer.

Influence of shear rate on the soil's shear strength

One of the most important mechanical properties is shear strength. It is conditioned by the value of the maximum shear stress that the soil can withstand before failure. Exceeding the shear strength causes one particle to slide next to another, causing the failure of soil. The shear strength of the soil for effective stresses is1 a combination of drained strength parameters: internal friction angle (φ) and cohesion (c) defined by the Mohr-Coulomb failure criterion. It is determined “in situ” and by laboratory experiments. Direct shear is the oldest and the simplest laboratory experiment to determine the shear strength of the soil. The first phase of experiment is specimen consolidation under specific vertical stress, and in the second phase specimens are sheared at a given shear rate, depending on the consolidation properties of the soil. Cohesionless soils are sheared at up to 100 times higher shear rate compared to cohesive soils. Shear rate and drainage conditions affect the magnitude of soil strength parameters. The paper is based on the comparison and demonstration of the influence of different shear rates on the peak and residual shear strength in the direct shear device. The tests were performed on two samples of low plasticity clay (CL) and one sample of high plasticity clay (CH).

Computational Fluid Dynamics Simulations of Mitral Paravalvular Leaks in Human Heart

In recent years, computational fluid dynamics (CFD) has been extensively used in biomedical research on heart diseases due to its non-invasiveness and relative ease of use in predicting flow patterns inside the cardiovascular system. In this study, a modeling approach involving CFD simulations was employed to study hemodynamics inside the left ventricle (LV) of a human heart affected by a mitral paravalvular leak (PVL). A simplified LV geometry with four PVL variants that varied in shape and size was studied. Predicted blood flow parameters, mainly velocity and shear stress distributions, were used as indicators of how presence of PVLs correlates with risk and severity of hemolysis. The calculations performed in the study showed a high risk of hemolysis in all analyzed cases, with the maximum shear stress values considerably exceeding the safe level of 300 Pa. Results of our study indicated that there was no simple relationship between PVL geometry and the risk of hemolysis. Two factors that potentially played a role in hemolysis severity, namely erythrocyte exposure time and the volume of fluid in which shear stress exceeded a critical value, were not directly proportional to any of the characteristic geometrical parameters (shape, diameters, circumference, area, volume) of the PVL channel. Potential limitations of the proposed simplified approach of flow analysis are discussed, and possible modifications to increase the accuracy and plausibility of the results are presented.

The Delayed Decrease of Seismicity In The Eastern Margin of The Japan Sea Due To The Megathrust Event In 2011 Along The Japan Trench

In the eastern margin of the Japan Sea, off the west coast of Tohoku district, the seismicity increased right after the M9 megathrust event off the east coast of the Tohoku district on March 11, 2011. Four months later, the seismicity decreased to the half level of that before the M9 event. Such quantitative study was done by the point-process model selection with AIC. The decrease lasted for eight years until an M6.7 event occurred within the area in 2019. When we compare the seismicity change between before and after the M9 event, with the post seismic change of the maximum shear stress obtained by the viscoelastic simulation for a thousand years after the M9 event, we can estimate a loading rate of the shear stress in the area before the M9 as 24 kPa/y. For the term after the M9 event, the rate is a half of it; 12 kPa/y. When we assume the whole dilatation change due to the M9 event had been canceled by the time of the M6.7, the increasing rate of the mean stress after the M9 event is 21 kPa/y at most. When we will be able to use JMA catalog for 2020 or later years, we can obtain the seismicity level after the M6.7 quantitatively, and we will be able to narrow down this estimation.

Distributions of Stress and Interlaminar Shear Stress in Laminates under Normal Load

The normal stress of each layer of the laminate composite material will undergo complex changes after normal compression, and shear stress will also appear between the layers. In order to explore the distribution laws of normal stress and shear stress, this paper uses Hooke's law and the equilibrium condition of force to carry out mathematical derivation, the analytical formulas for normal stress and shear stress are obtained, and their respective maximum values ​​are given. Studies have shown that the maximum normal stress occurs at the center of the laminate, and its value is proportional to the external load, and is also closely related to the length, width, thickness, elastic modulus of the cementing agent, elastic modulus and Poisson’s ratio of the laminate; The maximum shear stress occurs at the four corners of the laminate, and its value is proportional to the external load and the shear modulus of the cementing agent, inversely proportional to the thickness of the cementing agent layer, and its value is also closely related to the length, width, elastic modulus and Poisson's ratio of the laminate. The analytical formulas for normal stress and interlayer shear stress is helpful to deepen the understanding of the internal force distribution law of laminated plates, and the maximum value calculation formula can greatly facilitate the calculation of strength.

Interfacial, mechanical, and thermal behavior of PEI/glass fiber welded joints influenced by hygrothermal conditioning

This work aims to characterize the influence of hygrothermal conditioning on the mechanical and thermal behavior as well as the fractographic aspects of the interface of poly(ether imide) and glass fiber composite joints welded by electrical resistance using 400 mesh of AISI 304 stainless steel. The composites were mechanically characterized by Lap Shear Strength (LSS) and End Notched Flexure (ENF) testing to investigate maximum shear stress and energy from mode II interlaminar fracture toughness. Fractography was performed by SEM, while the influence on glass transition temperature and working temperature were evaluated by Dynamic-Mechanical Analysis and thermogravimetry. In the conditioned samples, the mechanical properties reduced 23% in the LSS test and 28% in the ENF test, while the fractography studies revealed elements of interlaminar and intralaminar fracture in both conditions. Thermal properties did not change significantly to disqualify this composite when applied to welding.