Ratio Of Horizontal Distance Research Articles

A study on three coalescence modes of non-collinear parallel elliptical double cracks

Based on the Gurson-Tvergaard-Needleman (GTN) damage model, this study focused on the coalescence modes of non-collinear parallel elliptical double cracks in a homogeneous plate, and the coalescence modes of elliptical double cracks under different horizontal distances and vertical distances were investigated. The ratio of horizontal distance s to crack length a was taken as the horizontal axis, the ratio of vertical distance h to crack length a was taken as the vertical axis to plot the graph, then the coalescence modes were summarized and compared with the coalescence modes of linear double cracks. It was found that the non-collinear parallel elliptical double cracks exhibited three coalescence modes: crack tip to crack tip coalescing, crack interval to crack interval coalescing, and crack tip to crack interval coalescing. Each coalescence mode had its own characteristics. The three coalescence modes were distributed regularly in three regions in the graph with s/a and h/a as coordinates. When the horizontal distance s and the vertical distance h between the double cracks were equal respectively, there were significant differences in the crack propagation process and coalescence modes between elliptical double cracks and linear double cracks.

Nonempirical fractal permeability model and experimental verification of hydrate-bearing sediments based on heterogeneous distribution of particles

The one of the factors limiting production of gas-water is affected by sediments' permeability. Evaluating the normalized permeability (Kn) of sediments containing hydrates is necessary for analyzing the saturation (decomposition level) and flow capacity. The mistakes in Kn prediction are frequently brought about by the assumption such as homogenous particles distribution and ignoring microscopic pore structure. To address the issue, a fractal-based nonempirical prediction model of Kn was developed by modeling, parameter acquisition using SEM and Analyzer, experiment validation, error comparison with published data, and sensitivity analysis for evolution, respectively. Assuming that sediment skeleton particles were misaligned spherical particles of equal diameter. The heterogeneity of sediments was described by the vertical and horizontal distance ratio (m) and offset angle (θ) of the particles. This led to a novel approach for determining average tortuosity (τav,0) and tortuosity fractal dimension (Dτ,0). The viability of the model was confirmed by permeability measurement experiments. Additionally, using the measuring function of SEM, the maximum pore diameter of sediments was obtained. Furthermore, a comparison with earlier data demonstrated the effect. Considering heterogeneity, the average accuracy of Geometric Mean Variance in Kn has increased to 9.66%. Finally, each parameter's impact on prediction was examined. At m = 1.357, Dτ,0 grows symmetrically. Kn,GC varies 15 times more with an increase in Dτ,0 than Kn,PF. All findings indicate that the new model is more likely to be forecasted Kn for a variety of systems, including clayey-silt, sand, and silty-sand system, and especially in reflecting the heterogeneity.

Forehead Fat Grafting: Asian Facial Contouring and Augmentation.

Aesthetic facial contouring procedures, particularly forehead augmentation, continue to increase in popularity in the Asian population. However, there are very few reports in the literature specifically examining the long-term outcomes of forehead fat grafting. In the present study, the authors aimed to objectively evaluate the efficacy of autologous forehead fat grafting through evaluation of facial proportions and patient-reported outcomes. Patients who underwent autologous fat grafting for forehead contouring procedures between July of 2011 and June of 2017 were recruited for participation in the study. Patient demographic and clinical variables were collected preoperatively and postoperatively. Facial proportion analysis was collected and compared from preoperative and postoperative photographs. Satisfaction with outcome was assessed by the patient, the surgeon, and a layperson postoperatively. A related-samples Wilcoxon signed rank test was used for statistical analysis. Postoperative outcomes were evaluated in a total of 24 patients who underwent forehead autologous fat-grafting procedures. The average postoperative follow-up was 8.1 months. There were no intraoperative or postoperative complications. More than 50 percent of the postoperative results were evaluated as "satisfactory" by all three groups (i.e., patient, surgeon, and layperson) in terms of aesthetic contouring. Average forehead projection increased 0.24 U (ratio of horizontal distance from midforehead plane to cornea plane/cornea diameter) after one round of fat grafting (p = 0.01). Seven patients (29.2 percent) required more than a single round of fat grafting to achieve optimal results. Autologous fat grafting remains a viable option for forehead contouring and augmentation. The findings of this study demonstrate that the operation is effective and offers stable satisfactory results after long-term follow-up. Therapeutic, IV.

ANALYSIS AND OPTIMIZATION OF HANDLING PERFORMANCE OF A CAR PERFORMING A LANE-CHANGE MANOEUVRE

Based upon the closed–loop evaluation method of handling performance, this paper gives an analysis of the effect of six structural parameters of a car (the stiffness of steering system, the front and rear roll steer coefficients, the ratio of horizontal distance of front axle from vehicle c.g. to the wheelbase, wheelbase, and the moment of inertia of the vehicle about the yaw axis through vehicle c.g.) on its handling performance when performing a lane–change manoeuvre. In addition, by using a hybrid optimisation method which is a combination of orthogonal experiment method and complex figure method, the six structural parameters are optimised.

Study of Q345 Steel under Tensile Failure with Bilateral Parallelcracks

The parallel crackswere prefabricated on both sides of theQ345 steel specimensand the tensile failure tests were performed.The effects of parallel crack spacing and crack length on the crack propagation behavior were studied and the fracture modes were investigated with electronic scanning microscope.The finite element analysis of tensile fracture process was also fulfilled based on the ductile metal damage theory, and the crack propagation and the crack stress field evolution around the crack tips were studied. The simulation was agreed with experimental results, and these analysis shows that the crack propagation related with double crack tip of horizontal distance ratio. When the longitudinal and horizontal distance ratio of the two crack tip is less than 1, the linkage between two cracks occurs, or two cracks expand independently. Simulation analysis shows that cracks deflect and connect with another one when the two high Mises plastic stress zones are met with each other; on the contrary, cracks propagate separately.

Effect of a Side Wall on the Natural Convection Heat Transfer from a Vertical Row of Horizontal Square Rods

Experimental study is carried out to investigate natural convection from a vertical array of three horizontal square rods fixed adjacent to a vertical adiabatic wall and tested under constant heat flux condition. The experimental rig is designed and constructed for this purpose with variable horizontal distance ratio (H/D) in the range (0.125 < H/D < 3.0). The vertical distance between the rods is changed to get ratio (S/D) ranges of (1.5 < S/D < 4). The Rayleigh number tested is in the range of (1.26 × 106 < Ra < 6.6 × 106) with variable heating levels. The finite volume computational method is used to determine the flow and thermal field around the array of the square rods in different experimental configurations. The computed fields confirm the discussion of the experimental behavior of each rod in the array at each test configuration. Results show that the main parameters affecting the heat dissipation rate of each of the rods are position of the rod in the array, relative vertical distance between the rods and horizontal distance to the adiabatic side wall. The chimney effect noticed between the rods and the adiabatic wall plays a big role in heat transfer enhancement at certain (H/D) values. Experiments show that the ability of the rods to dissipate heat was increased at the largest tested vertical distances with the same behavior noticed for the small horizontal distances relative to the adiabatic wall with a tendency of each rod to behave as a free rod as its horizontal distance to the wall is increased. A dimensionless empirical correlation for each rod was found. Another general correlation for the whole array is used to relate the experimental data of each rod according to its position in the array.