Abstract ：

Fluid-structure interaction (FSI) gained a huge attention of scientists and researchers due to its applications in biomedical and mechanical engineering. One of the most important applications of FSI is to study the elastic wall behavior of stenotic arteries. Blood is the suspension of various cells characterized by shear thinning, yield stress, and viscoelastic qualities that can be assessed by using non-Newtonian models. In this study we explored non-Newtonian, incompressible Casson fluid flow in a bifurcated artery with a stenosis. The two-dimensional Casson model is used to study the hemodynamics of the flow. The walls of the artery are supposed to be elastic and the stenosis region is constructed in both walls. Suitable scales are used to transform the nonlinear differential equations into a dimensionless form. The problem is formulated and discretized using Arbitrary Lagrangian-Eulerian (ALE) approach. The finite element method (FEM) technique is used to solve the system of equations, together with appropriate boundary conditions. The analysis is carried out for the Bingham number, Hartmann number, and Reynolds number. The graphical results of pressure field, velocity profile, and load on the walls are assessed and used to study the influence of hemodynamic effects on stenotic arteries, bifurcation region, and elastic walls. This study shows that there is an increase in wall shear stresses (WSS) with increasing values of Bingham number and Hartmann number. Also, for different values of the Bingham number, the load on the upper wall is computed against the Hartmann number. The result indicate that load at the walls increases as the values of Bingham number and Hartmann number increase.

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Abstract ：

As a result of its wide range of applications, FSI has grabbed the attention of researchers and scientists. In this study we consider an incompressible, laminar fluid flowing through the bifurcated channel. The wavy walls of the channel are considered elastic. Moreover, a magnetic field is applied towards the axial direction of the flow. Using a two-way fluid-structure interaction, an Arbitrary Lagrangian-Eulerian (ALE) formulation is used for coupling the problem. The problem is discretized using P 2 and P 1 finite element methods to approximate the displacement, pressure, and velocity. The linearized system of equations is solved using Newton's iterative scheme. The analysis is carried out for the Reynolds number and Hartman number. The ranges of the studied parameters are Reynolds number 300 & LE; R e & LE; 1000 and Hartmann number 0 & LE; H a & LE; 10 . The hemodynamic effects on the bifurcated channel and elastic walls are calculated using velocity, pressure, wall shear stresses (WSS), and loads at the walls. The study shows there is an increase in boundary load as the values of the Hartman number increase hence WSS increases. On the other hand, an increase in the Reynolds number increases the resistance forces hence velocity and WSS decrease. Also, numerical values of WSS for rigid and elastic walls are calculated. Studies showed that WSS decreases for the FSI case when compare to CFD (computational fluid dynamic) case.

Keyword ：

elastic walls elastic walls bifurcation bifurcation wall shear stress wall shear stress fluid-structure interaction fluid-structure interaction biomagnetic fluid biomagnetic fluid finite element method finite element method

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Abstract ：

Heat flux manipulation based on thermal metamaterials under diffusive heat conduction has been ex-tensively studied due to their extraordinary potential in energy utilization. However, the requirement of extreme material parameters or even infinite singularity may significantly limit their practical applica-tions. In this work, we propose a new method for uniformly designing thermal cloak and concentrator with interconnected structure. The condition for realizing the undisturbed temperature distribution of the background medium in thermal cloak is strictly deduced. Through adjusting two geometric parameters of the interconnected structure, we analytically demonstrate that the thermal cloak and concentrator are realizable, where the heat flux can be shielded or concentrated in the target region. The desired ther-mal functionalities are confirmed both by the finite element simulations and heat transfer experiments. Furthermore, the results of interconnected structure are in excellent agreement with that of conventional thermal devices, and demonstrate that the interconnected structure provides an efficient method for ma-nipulating heat flux over a very wide range (from cloaking to concentrating) despite having a simple composition and structural characteristics. The feasibility of interconnected structure can enhance the se-lection of bulk natural materials in addition to easy manufacturability for the heat flux manipulation, which might be extended to other disciplines, such as electromagnetics and acoustics. (c) 2022 Elsevier Ltd. All rights reserved.

Keyword ：

Thermal cloak Thermal cloak Heat conduction Heat conduction Thermal concentrator Thermal concentrator Interconnected structure Interconnected structure

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Abstract ：

The non-isothermal couple stress fluid inside a reverse roll coating geometry is considered. The slip condition is considered at the surfaces of the rolls. To develop the flow equations, the mathematical modelling is performed using conservation of momentum, mass, and energy. The LAT (lubrication approximation theory) is employed to simplify the equations. The closed form solution for velocity, temperature, and pressure gradient is obtained. While the pressure and flow rate are obtained numerically. The impact of involved parameters on important physical quantities such as temperature, pressure, and pressure gradient are elaborated through graphs and in tabular form. The pressure and pressure gradient decreases for variation of the couple stress parameter and velocity ratio parameter K. While the variation of the slip parameter increases the pressure and pressure gradient inside the flow geometry. Additionally, flow rate decreases for the variation of the slip parameter as fluid starts moving rapidly along the roller surface. The most important physical quantity which is responsible for maintaining the quality of the coating and thickness is flow rate. For variation of both the couple stress parameter and the slip parameter, the flow rate decreases compared to the Newtonian case, consequently the coating thickness decreases for the variation of the discussed parameter.

Keyword ：

non-isothermal flow non-isothermal flow slip condition slip condition analytic solution analytic solution heat transfer heat transfer reverse roll coating reverse roll coating couple stress fluid couple stress fluid lubrication approximation theory (LAT) lubrication approximation theory (LAT) shooting technique shooting technique

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Abstract ：

Magnetic anomaly detection is becoming increasingly prevalent for detecting and locating the buried pipelines. The detection performance is often hindered by adjacent pipeline, near-field ferromagnetic objects and random noises. In order to overcome these obstacles, a magnetic anomaly detection method based on deep learning neural networks (DLNN) is proposed to decouple and denoise the integrated detection to accurately extract the magnetic anomaly of single pipeline. The theoretical derivation of the vertical component of magnetic anomaly was executed based on Poisson's equation. Then the integrated detection was simulated by summing magnetic anomalies of parallel pipelines and metal sphere, as well as white Gaussian noise. The DLNN was constructed with improved optimization design, and trained using supervised learning method. The results show that the proposed method exhibits almost immune to random noises, the prediction accuracy approaches to 90% with signal to noise ratio (SNR) of 30 dB. Meanwhile, the predictive accuracy is still above 80% with interferences both from near-field ferromagnetic objects and random noises with SNR of 30 dB. The method becomes practically significant in the development of geomagnetic inspection instruments for the adjacent parallel pipelines.

Keyword ：

Deep learning Deep learning Adjacent parallel pipelines Adjacent parallel pipelines Magnetic anomaly detection Magnetic anomaly detection Neural networks Neural networks

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Abstract ：

As the main geometric defect in pipeline maintenance, dent has been paid more attention by pipeline managers because of its strong stress concentration. To investigate the formation mechanism of a pipeline dent, an indentation test of a pipe subjected to concentrated lateral load was carried out in the laboratory to simulate the formation process of the dent, and a 3D numerical model corresponding to the test was established to verify the results between the experiment and simulation. Subsequently, the stress and strain response of the dented pipeline was analyzed in detail in various stages of dent formation process. Deformation analysis revealed that the residual stresses state formed in the dented area after unloading is related to the depth of the dent, which may be in tension or in compression. During the formation of the dent, the pipeline presents "similar to"-type wave-like bending state in the axial direction. These dent formation mechanisms may provide a guidance for dent assessment studies.

Keyword ：

Deformation response Deformation response Failure analysis Failure analysis Modeling studies Modeling studies Dented pipeline Dented pipeline

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Abstract ：

The blade coating process of a micropolar fluid using the plane and exponential coater has been studied. Equations are simplified utilizing lubrication approximation theory. The analytical expressions for flow rate, pressure gradient, and velocity are obtained, while load and coating thickness are computed numerically with the help of the shooting method. We show how the microrotation parameters epsilon and the coupling number N influence the flow characteristics, such as pressure distribution, velocity, pressure gradient and related engineering quantities such as load and thickness in the blade coating process, and they are shown graphically as well as in tabular form. We find that, for coupling number N and microrotation parameter epsilon, the pressure increases when compared to the Newtonian fluid. Moreover, the coating thickness decreases for the Newtonian case when N increases.

Keyword ：

Shooting method Shooting method Micropolar fluid Micropolar fluid Blade coating Blade coating Lubrication approximation theory (LAT) Lubrication approximation theory (LAT) Incompressible flow Incompressible flow Exact and numerical solution Exact and numerical solution

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Abstract ：

In recent years, many accidents caused by alternating current (AC) corrosion have been reported. AC corrosion has become a serious potential damage to buried steel pipelines. The X100 pipeline steel is a very promising material for long-distance gas pipelines, and Korla soil is a typical saline-alkali soil of West China. The coarse-grained heat-affected zone (CGHAZ) and the intercritically reheated coarse-grained heat-affected zone (ICCGHAZ) were simulated by a Gleeble thermomechanical processing machine through different thermal cycle times, peak temperatures, and cooling rates. Electrochemical corrosion measurements, immersion experiments and surface analysis techniques were used to characterize the corrosion behavior of the base metal, CGHAZ, and ICCGHAZ of the X100 pipeline steel in simulated Korla soil solution under AC interference. The X100 pipeline steel base metal, CGHAZ, and ICCGHAZ exhibited active dissolution in the simulated Korla soil solution under AC interference, and the average corrosion rate increased with the increase in AC density. The amplitude of the polarization potential oscillation caused by AC interference and the microstructure had an important influence on the corrosion rate and corrosion morphology of the X100 pipeline steel base metal, CGHAZ and ICCGHAZ. Under the interference of 5 mA·cm-2 AC density, the X100 pipeline steel base material shows the most negative corrosion potential and the largest average corrosion rate, while the ICCGHAZ shows the most positive corrosion potential and the smallest average corrosion rate. Under the interferences of 20 and 50 mA·cm-2 AC densities, the ICCGHAZ of X100 pipeline steel shows the most negative corrosion potential and the largest average corrosion rate, while the base metal shows the most positive corrosion potential and the smallest average corrosion rate. Under the interference of 20 mA·cm-2 AC density, the X100 pipeline steel is locally corroded. CGHAZ and ICCGHAZ have obvious grain boundary corrosion, whereby GCHAZ grain boundary corrosion morphology is slit-shaped, and ICCGHAZ grain boundary corrosion morphology is continuous pores. © 2020, Science Press. All right reserved.

Keyword ：

Underground corrosion Underground corrosion Steel pipe Steel pipe Electric impedance measurement Electric impedance measurement Morphology Morphology Steel corrosion Steel corrosion Heat affected zone Heat affected zone Metals Metals Corrosion rate Corrosion rate Electrochemical corrosion Electrochemical corrosion Surface analysis Surface analysis Grain boundaries Grain boundaries Soil moisture Soil moisture Pipeline corrosion Pipeline corrosion Pipelines Pipelines Corrosive effects Corrosive effects

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Abstract ：

The work aims to clarify the influence of stray alternating current (AC) on the corrosion under the anticorrosive coating caused by peeling and damage of buried steel pipeline corrosion coating and the mechanism of action leading to peeling of coating. COMSOL Multiphysics® simulations, AC impedance spectroscopy analysis and three-dimensional microscope were used to study the corrosion mechanism and stripping behavior of X70 high-strength pipeline steel at 3PE coating stripping under AC stray current in Golmud soil simulation solution. The protective performance of the coating was significantly reduced due to the presence of damage points and stripping areas in the coating. The stray current was unevenly distributed on the surface ofX70 steel in the initial reserved stripping area, and the current density at the breakage point was significantly higher than that at the edge of the stripping area. The corrosion reaction caused by stray currents was mainly concentrated at the damage point of the coating, while the X70 steel under the reserved peeling zone showed crevice corrosion phenomenon. Corrosion pit depth at the damage point of the coating gradually became deeper as the current density increased, but when the AC current density increased from 0 A/m2 to 100 A/m2, the peeling area of the anti-corrosion coating increased significantly. After that, when the current density continued to increase, the peeling area remained basically unchanged. When the applied alternating current density was the same, the peeling area of the anti-corrosion layer increased as the peeling area of the reserved anti-corrosion layer decreased, and the maximum corrosion pit on the X70 steel sample slightly deepened. There is a critical current density in the delamination area of coatings caused by AC stray currents and such density can result in and keep maximum stripping area. When the initial stripping area of coating is smaller, corrosion and coating stripping of X70 steel caused by AC stray current are more serious. © 2018, Chongqing Wujiu Periodicals Press. All rights reserved.

Keyword ：

Current density Current density Critical current density (superconductivity) Critical current density (superconductivity) Steel corrosion Steel corrosion Electric impedance measurement Electric impedance measurement Stripping (removal) Stripping (removal) High strength steel High strength steel Crevice corrosion Crevice corrosion Pitting Pitting Steel pipe Steel pipe Underground corrosion Underground corrosion Corrosion resistant coatings Corrosion resistant coatings Pipeline corrosion Pipeline corrosion Pipelines Pipelines

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To increase the delivery capacity and flow stability of the screw pump and reduce wear between the stator and the rotor, a surface forming method of single-head cone screw-bush pair with equal cavities and large delivery capacity was investigated based on the conventional single cone screw theory. An equation of the cone screw-bush pair surface was established according to the space engagement theory. A flow equation of single cone screw bush pair was built based on the cone screw-bush pair section equation and the rule of its variation. The calculation method of the screw structure size at a given flow rate was determined as well. A kinematics equation of the single cone screw-bush pair was obtained after a kinematics analysis of the single cone screw-bush pair conducted. The movement formula of a single cone screw-bush pair with equal cavities and large delivery capacity was concluded. Three-dimensional model of a single cone screw and a bush was built and the motion simulation of the pair was conducted based on MATLAB and Pro/Mechanism. The kinematics rules were summarized at the same time. Moreover, a single cone screw and a bush solid model were processed based on the three-dimensional model of the cone screw-bush pair and the three-dimensional printing technology. The correctness of the equation of the single cone screw-bush pair surface was verified.

Keyword ：

motion analysis motion analysis surface modelling surface modelling cone screw-bush pair cone screw-bush pair flow area flow area Pump Pump

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