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The directions of primary strain lines of local deformation in Epicardial and Endocardial layers have been the subject of debate in recent years. Different methods led to different conclusions and a complete assessment of strain direction patterns in large and variable (in terms of pathology) cohorts of healthy and diseased patients is still lacking. Here, we use local deformation tensors in order to evaluate the angle of strain lines with respect to the horizontal circumferential direction in both Epi- and Endo-layers. We evaluated this on a large group of 193 subjects including 82 healthy control and 111 patients belonging to a great variety of pathological conditions. We found that Epicardial strain lines obliquely directed while those of Endocardium are almost circumferential. This result occurs irrespective of pathological condition. We propose that the geometric vinculum characterizing Endocardium and Epicardium in terms of different lever arm length and orientation of muscular fibers during contraction inescapably requires Endocardial strain lines to be circumferentially oriented and this is corroborated by experimental results. Further investigations on transmural structure of myocytes could couple results presented here in order to furnish additional experimental explanations.

A self‐wiping co‐rotating twin‐screw extruder (TSE) is operated in a starved state in which the screws are partially filled with resin. Understanding the resin distribution on the screw surface of a TSE in this state is essential for the design, operation, and maintenance of the twin‐screw extrusion process. Accordingly, in this study, the circumferential and axial distribution of resin in a TSE were simulated using a novel method combining the mathematical formulation of Hele–Shaw flow, the finite element method, and a newly developed down‐wind pressure updating scheme. The results of the simulation were found to be in good agreement with experimental measurements. The proposed simulation method enables the detailed visualization of resin distribution in the entire axial and circumferential directions over the length of a TSE, improving the ability to determine both the devolatilization and fiber attrition during the extrusion process. [ABSTRACT FROM AUTHOR]

The use of high-density polyethylene pipes in gas and water distribution networks is steadily growing worldwide. If the resistance of plain pipes is at present time well established using appropriately designed standards, welding issues continue to be globally approached equally in terms of structure and mechanical properties. Consequently, further practical investigations should be aimed at studying mechanical properties in the weld region which includes the melt zone and its heat-affected zones. This work presents a method based on removing layers in order to assess localized variances in mechanical properties throughout the weld seam in both radial and circumferential directions. An experimental plan based on specific machining operations allowed testing 39 standard specimens representing the weld volume matter in three concentric layers for given pipe dimensions and their counterpart standard unwelded ones. The typical stress-strain behavior of semi-crystalline materials is preserved in welded and unwelded specimens but with different characteristic limits. At the weld inner layers, properties such as elastic modulus, yield, and failure stresses displayed lower values, whereas in welded outer layers, the tendency is inversed. The cold drawing extend remained approximately steady for unwelded and welded cases across the pipe wall. This property is less affected by the presence of the weld as it described a constant material flow which is mostly a function of available material quantity for yielding. The approach developed in this study gives consistent indications on welding quality around the pipe weld and across the thickness. Accordingly, outermost and innermost welded layers may exhibit lower or even bad-quality welds as imperfections can concentrate stresses at the joint interface because of cold weld problems. Such method enabled detecting 23% of failures at the weld seam from outer and inner layers while the middle layer did not reveal any failure at the weld. The causes of this behavior are approached using crystallinity evolution in welded and unwelded pipes. [ABSTRACT FROM AUTHOR]

The linear stability analysis is carried out for the suspension flow of spherical particles between a rotating inner cylinder and a stationary concentric outer cylinder. The mass conservation equation and Navier-Stokes equation are applied to the continuous fluid phase and the particle phase. Results of stability analysis show that the increase of wave number in the circumferential direction attenuates the effect of the axial wave number on the amplification factor. The ratio of particle density to fluid density increasing above 0.1 amplifies the flow instability, while it can be weakened with higher circumferential direction wave number. Effect of the critical Taylor number on the amplification factor is reduced by increasing the circumferential direction wave number. The flow stability is affected by the geometry of flow field (the radius ratio) at non-zero circumferential direction wave numbers. [ABSTRACT FROM AUTHOR]

• Analytical solutions of additional stresses for a curved shield tunnel is presented. • Additional stresses caused by construction loadings and soil loss are obtained. • A case study is performed. This paper focuses on analytical solutions of additional stresses for a curved shield tunnel. General equations of additional stress caused by construction loadings were deduced by rewritten Mindlin solutions, and additional thrust and friction force were considered. In addition, theoretical formulae of additional stress caused by soil loss were deduced based on the three-dimensional image theory, and the actual processes of synchronous grouting and over-excavation were considered. Then, by using a curved tunnel in Zhuhai City, China as a case study, the distribution laws of additional stress along the directions of advancement and circumference were investigated. Under the coaction of construction loadings and soil loss, it was found that the distributions of σ x and σ y along the advancement direction for curved tunnels are similar to those for straight-line tunnels. However, the soil around a curved tunnel is more likely to yield because the difference between the normal stresses in two directions is greater than that for soil around a straight-line tunnel. Additional stresses caused by soil loss along the circumferential direction for a curved tunnel were found to no longer have the characteristics of strictly axial symmetry. The values of compressive stress σ x and σ y at the outer side of the curved tunnel were found to be greater and smaller than those at the inner side, respectively. As the curvature radius decreases, the maximum tensile stresses σ x and σ y for curved tunnels were found to decrease and increase, respectively. Furthermore, an insufficient quantity of injection grouting will trigger detrimental effects to nearby structures during the approaching excavation. [ABSTRACT FROM AUTHOR]