Boundary Layer Flow and Heat Transfer Analysis by Using the Correlation Coefficient and Regression Model Over a Stretching Bullet-Shaped Object

The boundary layer theory is important when fluid flows over a solid surface that is moving or stationary. In presence of the boundary layer, the effective shape of the body may change leading to changes in pressure distribution, as a result, the overall lift and drag forces change. Therefore, the Boundary layer theory helps in designing aerofoil’s, to compute the lift and drag forces for the aerospace and automobile designers, to control the heat transfer rate from the device, etc. So, the present problem will help design the various types of bullet-shaped objects in the field of automobile engineering. Therefore, the current problem has focused on the two-dimensional axisymmetric BL flow over a stretching bullet-shaped object for the effect of magnetic field strength (M), linear stretching parameter (M), and surface thickness parameter (s). Therefore, the main goal of this work is to determine the relation by applying the correlation coefficient among the physical parameters and velocity field, temperature field, shear stress (τw), Nusselt number (Nux). Hence, the novelty of the current paper is to develop the relationship among the dependent and independent parameters by the correlation coefficient and also developed the numerical method to solve these highly nonlinear equations. The numerical results are discussed for the three different values of the stretching ratio parameter and two values of the surface thickness parameter. The velocity and temperature distribution equations are compressed into a system of ODEs with similarity transformations. These ODEs are then solved using a spectral quasi-linearization method (SQLM) by applying Taylor series expansions that can be used to linearize the non-linear terms in the equations. These resulting linearized systems of equations are determined by the spectral collocation method. The convergence of the numerical solutions was performed by using the residual error of the PDEs. The error analysis is established for the validity of the present model. This error norm is applied to establish the validity and convergence of the numerical solution. The outcome of the mentioned dimensionless parameters over the fluid velocity field, temperature field, skin friction coefficient (Cf), and Nusselt number (Nux) are displayed graphically. It is observed that the parameters M and M are positively correlated with fluid velocity distribution within the BL but the surface thickness parameter(s) are negatively correlated. The rate of temperature increases for the parameter M and Pr but decreases for M and s. Therefore, the boundary layer thickness reduces for increasing the values of M and M but increases for increasing the values of s. The velocity of the fluid is about 80% higher in the case of a thinner surface (s = 0.2) than the thicker surface (s = 2.0) and the heat transfer rate is also igher in the case of a thinner surface comparatively thicker surface. The innovation of this present problem lies in the unification of more physical parameters into the governing equations and an attempt to give a thorough analysis of how the flow properties are affected by these parameters.

Mechanical Properties of Additively Manufactured Periodic Cellular Structures and Design Variations

Advances in manufacturing technologies have led to the development of a new approach to material selection, in that architectured designs can be created to achieve a specific mechanical objective. Cellular lattice structures have been at the forefront of this movement due to the ability to tailor their mechanical response through tuning of the topology, surface thickness, cell size, and cell density. In this work, the mechanical properties of additively manufactured periodic cellular lattices are evaluated and compared, primarily through the topology and surface thickness parameters. The evaluated lattices were based upon triply periodic minimal surfaces (TPMS), including novel variations on the base TPMS designs, which have not been tested previously. These lattices were fabricated out of Inconel 718 (IN718) through the selective laser melting (SLM) process. Specimens were tested under uniaxial compression, and the resultant mechanical properties were determined. Further discussion of the fabrication quality and deformation behavior of the lattices are provided. Results of this work indicate that the Diamond TPMS lattice has superior mechanical properties to the other lattices tested. Additionally, with the exception of the Primitive TPMS lattice, the base TPMS designs exhibited superior mechanical performance to their derivative lattice designs.

Gray matter declines with age and hearing loss, but is partially maintained in tinnitus

The impact of age-related hearing loss extends beyond the auditory pathway and impacts brain areas related to cognitive impairment and even dementia. The presence of tinnitus, a sensation of sound that frequently co-occurs with hearing loss, is additionally linked to cognitive decline. Interestingly, structural neuroimaging studies have reported that hearing loss may precede or modulate the onset of cognitive impairment. In this study, we aimed to disentangle the effects of age, hearing loss, and tinnitus on gray matter structure. In total, 39 participants with hearing loss and tinnitus, 21 with hearing loss but without tinnitus, and 39 controls were included in this voxel- and surface-based morphometry MRI study. Whole brain volume and surface thickness measures were compared between the groups. Age-related gray matter volume decline was observed in all groups. Several brain areas showed smaller gray matter volume and cortical surface thickness in hearing loss without tinnitus, relative to controls. This reduction was observed both within and outside of the auditory pathway. Interestingly, these reductions were not observed in participants with tinnitus, who had similar hearing loss and were of similar age. Since we have tools to improve hearing loss, hearing screening may aid in the battle against cognitive decline.

Evidence of cortical thickness reduction and disconnection in high myopia

High myopia (HM) is associated with impaired long-distance vision. accumulating evidences reported that abnormal visual experience leads to dysfunction in brain activity in HM even corrected. However, whether the long-term of abnormal visual experience lead to neuroanatomical changes remain unknown, the aim at this study is to investigate the alternation of cortical surface thickness in HM patients. 82 patients with HM (HM groups), 57 healthy controls (HC groups) were recruited. All participants underwent high-resolution T1 and resting-state functional magnetic resonance imaging (MRI) scans. The cortical thickness analysis was preformed to investigate the neuroanatomical changes in HM patients using computational anatomy toolbox (CAT 12) toolbox. Compare with HCs, HM patients showed decreased the cortical surface thickness in the left middle occipital gyrus (MOG), left inferior parietal lobule (IPL), right inferior temporal gyrus (ITG), right precuneus, right primary visual area 1 (V1), right superior temporal gyrus (STG), right superior parietal lobule (SPL), right occipital pole, and right the primary motor cortex (M1), and increased to the parietal operculum (OP4) (P < 0.01, FWE-corrected), the mean cortical thickness of right orbitofrontal cortex (OFC), right dorsolateral prefrontal cortex (DLPFC) and right subcallosal cortex showed negatively correlation between clinical variables (axis length (ALM), the average macular thickness (AMT), keratometer (KER) 1, KER2, the mean KER, the mean macular fovea thickness (MFK), the refractive diopter) in HM patients. Our result mainly provided an evidence of cortical thickness reduction and disconnection in visual center and visual processing area, and cortical thickness increase in left multimodal integration region in HM patients. This may provide important significance of the study of the neural mechanism of HM.