Correlation Between Corpus Callosum Shape and Craniometric Measurements According to Mri Data

The correlation between the cranial height and the height of the corpus callosum trunk bulge, and the relationship between the corpus callosum shape and the cranial shape have not been studied. The purpose of the article was to determine the individual variability of the corpus callosum height and shape of adults, and their dependence on the cranial height and shape. The material was two samples from a series of MR scans of the head of men and women of the second period of adulthood (19 variations in each group) without the central nervous system pathology. Magnetic resonance tomographic scanner Magnetom C was used for obtaining MRI images. Morphometric study was conducted using RadiAnt Dicom Viewer software on MR scans performed in the sagittal area in T1- and T2-weighted images modes. According to the findings, the height of the corpus callosum trunk bulge of men is on average – 26.1 ± 2.8 mm, women – 25.2 ± 2.6 mm, and the neurocranium height – 150.4 ± 6.9 mm and 140.2 ± 4.2 mm, respectively. Wherein the aspect ratio of the neurocranium height to the corpus callosum trunk bulge height in men is 5.8 ± 0.7, in women – 5.6 ± 0.5. The aspect ratio of the corpus callosum longitudinal size along the constricting chord to its trunk bulge height in men is on average 2.8 ± 0.3, in women – 2.7 ± 0.3. The absence of correlation between the cranial height and the corpus callosum trunk bulge height, and the absence of correlation between the corpus callosum shape and cranial shape in people of the second period of adulthood have been concluded.

Choroidal thickness and vessel pattern in myopic eyes with dome-shaped macula

AimTo analyse the choroidal thickness (CT) and vessel pattern of myopic patients with dome-shaped macula (DSM) and their association with the DSM axis and serous retinal detachment (SRD).MethodsRetrospective study. The CT and vessel pattern were assessed on optical coherence tomography (OCT), OCT-angiography and ultra-wide-field photography.Results27 eyes of 18 subjects (mean age: 65 years) were included. Compared with the 11 eyes (41%) with horizontal DSM, the 16 eyes (59%) with vertical DSM had a shorter axial length (25.8±2 mm vs 28.3±2.5 mm; p=0.01), a higher mean macular bulge height (624.4±207 µm vs 255.4±160.3 µm; p=0.0001) and a thicker CT (183.1±91.1 µm vs 72±38.3 µm; p<0.001). Large choroidal vessels crossed the macular area in 75% of eyes with vertical DSM vs 27% of eyes with horizontal DSM (p=0.02), whereas a watershed zone framing the macula was more often seen in horizontal DSM (72% vs 25%, p=0.02). Thirteen eyes (48%) had an SRD that was not associated with the DSM axis, the mean bulge height, the CT or the vessel pattern.ConclusionThe presence of an SRD did not correlate with the DSM axis, the CT or the vessel pattern. However, the rate of large choroidal vessels crossing the macula was higher in vertical DSM than in horizontal DSM.

Magnetic Medium-Assisted Inverse Bulge Pre-Forming and Deep Drawing Composite Forming Process for Improving Forming Performance of the Cylindrical Parts

Due to the poor plasticity of aluminum alloy at room temperature, it is difficult to form thin-walled and complex curved parts. This paper proposes a composite method of inverse bulge pre-forming deep drawing based on intelligent magnetorheological (MR) fluid materials. Through the experiments and finite element modeling of cylindrical parts with drawing ratios of K1=2.125 and K2=2.25 were carried out under different forming conditions. The effect of soft mold medium on the drawing forming of cylindrical parts was studied. The research results show that the uniformity of the wall thickness of the parts is enhanced after using the soft mold medium. When the inverse bulge height is about 9mm and 5mm, the wall thickness variance of the cylindrical part is 0.0023 and 0.0025 pectively, which is reduced by 86.31% and 82.8% respectively. In the pre-forming stage, as the height of inverse bulge is increased, the maximum equivalent stress moves from the fillet area of the blank holder to the outer surface of the highest point of the bulging area. Taking drawing ratio of K1=2.125 as an example, the circumferential compressive stress in the flange area decreases and is distributed unifomly under the back pressure and soft drawbeads, the radial stress gradient and equivalent stress gradient at the fillet of die are reduced; For cylindrical parts with drawing ratios of K1=2.125 and K2=2.25, when the inverse bulge height is 9mm and 5mm, the forming effect of the part is the best.

Finite element modeling of the shaped charge jet and design of the reusable perforating gun

Finite element method is used to study the formations of the penetration jet, the bulge, and the burr in the designed reusable perforating gun. The attached layer of the soft metal on the perforator is studied for the controlling of the bulge height on the casing of the reusable perforating gun. Results indicate that the shaped charge jet is initially formed in the center of the shaped charge liner and then the material of the liner is driven to the centerline of the liner by the detonation wave. The attachment of the soft metal layer to the cartridge of the perforator can be beneficial to control the bulge height. The design on the blind holes on the casing can affect the burr height formed by the collision between the jet and the casing. With the increase in the liner angle, the penetration width on the cement wall of the wellbore is increased.

Optimizing Process and Geometry Parameters in Bulging of Pipelines

The objective of this work is to determine the optimum process and geometry parameters to attain maximum bulge height without necking / splitting failure. The effect of process parameters on strain path and its correlation with bulge height is also carried out., ANOVA is used to study the relative contribution of geometry properties, process parameters and tube thickness. It is found that the strain hardening exponent has the highest impact on bulging followed by plastic anisotropy and thickness of tube has a relatively lesser contribution to limit strains of tube bulging. The effects of process parameters, at a specific bulge height, are studied on effective strain distribution and thinning distribution, the homogeneity of which is expressed in the terms of real Kurtosis value. It is concluded that optimum process parameters not only gives less thinning and greater bulge height, it also gives more uniform deformation pattern (thinning and effective strain). The validation of optimum process parameters obtained through Taguchi is carried out using additive model and it is found that the observed value is well in agreement with the predicted value. It is also found that friction has a negative impact on bulge height as well as thinning. This is because higher friction resists the flow of material and causes the material to thin more rapidly at the critical area where necking is taking place. It is also found that bulge height is maximum at higher pressure and higher bulge length and thinning is minimum at lower pressure and higher bulge length.

Hydrodynamic Ram Effect Caused by Debris Hypervelocity Impact on Satellite Tank

To study the hydrodynamic ram effect caused by the debris hypervelocity impact on the satellite tank, a numerical simulation of the spherical debris impacting the satellite tank at the velocity of 7000 m/s was carried out based on ANSYS/LS-DYNA software. The attenuation law of debris velocity, the propagation process of the shock wave and the deformation of the tank walls were investigated. The influences of the liquid-filling ratio, the magnitude, and direction of angular velocity on the hydrodynamic ram effect were analyzed. Results show that the debris velocity decreased rapidly and the residual velocity was 263 m/s when the debris passed through the tank. The shock wave was hemispherical, and the pressure of shock wave was the smallest at the element with an angle of 90° to the impact line. The maximum diameter of the front perforation was larger than that of the back perforation and the bulge height on the front wall was smaller than that on the back wall. With the decrease of the liquid-filling ratio, the diameter of the perforations and bulge height decreased. When the debris impacted the satellite tank with the angular velocity in the x direction, the debris trajectory did not deflect. When the debris impacted the satellite tank with the angular velocities in the y and z direction, the debris trajectory deflected to the negative direction of the z axis and y axis, respectively. The magnitude of the angular velocity affects the residual velocity of debris and the diameter of perforations.

Maximum Bulge Height and Weld Line Displacement in Hydroforming of Tailor Welded Blanks

Tailor welded blank (TWB) has many advantages over a traditional blank for manufacturing automobile sheet metal components, such as significant flexibility in product design, higher structural stiffness, and crash behavior. However, lower formability and weld line movement are some of the problems associated with forming of TWBs. Hydroforming is a potential technique to enhance formability. In this work, the effect of thickness ratio on maximum dome height and weld line movement in hydraulic bulging of laser welded interstitial-free (IF) steel blanks of different thickness combinations has been predicted using finite element (FE) simulations. The results are also validated with hydraulic bulging experiments on TWBs. It has been found that with increase in thickness ratio, the maximum bulge height decreased and weld line displacement toward thicker side increased. These results have been used to relocate the weld line toward the thinner side in the initial blanks and achieve a more uniform bulge profile of the dome. The peak pressure to achieve maximum safe dome height and percentage thinning has also been found out. The results showed huge improvement in uniformity of bulge profile with little reduction in dome height.

Effect of Different Proportion of Coarse and Fine Grain Microstructure on Superplastic Forming Characteristics

The study was carried out to understand the effect of inhomogeneous microstructure on thickness variation in superplastically formed bulge. Friction stir processing was performed at rotational and traverse speeds of 720rpm and 155mm/min respectively on a 6mm sheet maintaining 50% overlap on the retreating side. Different probe dimensions were selected to obtain different proportions of fine grained stir zone in thickness direction. The proportions of the fine grained stir zone were 25%, 50%, 72% and, 100%. The sheets containing inhomogeneous microstructure were subjected to superplastic bulge forming under constant gas pressure up to a bulge height of 23.5mm. The sheet which was processed with 72% fine grains showed lower thickness variation from edge to apex and the bulge shape in this condition was close to the ideal spherical profile.