Apex Of Cone Research Articles

Ex Vivo Lenticule Customization for Stromal Lenticule Addition Keratoplasty.

The purpose of this study was to explore the optimal shape of customized lenticules for stromal lenticule addition keratoplasty (SLAK) for off-centered ectasia. Two different methods to create ex vivo models of eccentric-keratoconus were investigated. Twelve human corneas were used to create model 1 by a hyperopic photorefractive keratectomy (PRK), and model 2 by masked phototherapeutic keratectomy (PTK) on the anterior corneal surface, whereas both types received myopic ablation of the posterior surface. Keratoconus models underwent a modified femtosecond laser (FSL) flap-cut to create stromal pockets. Sixteen human corneas underwent FSL dissection to obtain four lenticule types: type I (planar) and type II (negative) lenticules were used without modifications, whereas type III (customized-planar), and type IV (customized-negative) lenticules underwent further masked-PRK to obtain an asymmetric bow-tie shape. Topographic, aberrometric analysis, and anterior segment optical coherence tomography (AS-OCT) were performed in all recipient corneas before and after lenticule implantation. Keratoconus model was successfully reproduced. Tomographic analysis showed a significant inferiorly decentered corneal steepening with coherent stromal thinning. Model 2 reproduced better the curvature of real keratoconus. Lenticules type I implantation induced a homogeneous corneal thickening, type III produced higher thickening in the inferior half of the cornea. Type II determined a maximal peripheral pachymetric increase, with a gradual reduction toward the center, and type IV presented an asymmetric peripheral thickening. Topographic assessment showed a cone apex flattening in all cases, but it was significantly higher in types II and IV. Customized lenticules improved significantly corneal surface regularity regarding types I and II. The approach of customizing lenticules by increasing their asymmetry and tailoring the re-shaping effects, may improve SLAK outcomes in eccentric keratoconus.

Comparative analysis and enhancement of conical component calculation under internal pressure in European pressure vessel Standards

This paper presents a comprehensive analysis of conical components in pressure vessels emphasizing their significance when utilized to transition between different diameters or slopes. A thorough design and analysis are underscored as essential for ensuring the safety and reliability of these components under diverse loading circumstances. The paper aims to propose enhancements to the European Pressure Vessel Standards concerning conical components under internal pressure, with a focus on improving safety, reliability, and compliance with industry standards. Existing European standards are reviewed, identifying potential gaps and proposing practical solutions. The paper also presents research findings on the influence of cone apex angles, shell geometries and design pressure on cone plate thickness calculations. A new methodology for the design and analysis of conical components in pressure vessels is proposed, offering a potential pathway to safer and more efficient pressure vessels. A range of cylinder diameter between 1000 and 2500 mm and cone angles between 30° and 60° are used as input to quantify the difference in cone thickness for a design pressure ranging between 10 and 200 barg. The proposed method yields results much closer to AD2000 compared to EN13445, leading to slightly thicker cones (up to 2.2 mm for the selected range of cone diameters and angles) compared to the former, resulting in safer pressure vessel design, and thinner cones (up to 22 mm) compared to the latter resulting in significant material savings. A comparative analysis was performed through Finite Element Analysis validating the EN13445 unsuitability for cone thickness calculations. A modification is proposed for equation (7.6)-(8) in EN13445 resulting in thinner plates reducing the cone plate thickness difference to 0.9 % on average compared to the current deviation of -9.6 % on average for the selected range of cylinder diameters and cone angles.

The modeling method for vibration characteristics analysis of composite laminated rotationally stiffened shell.

The composite laminated rotationally stiffened shell is widely applied in aviation, aerospace, ship, machinery and other fields. To investigate the vibration characteristics of composite laminated rotationally stiffened shells with varying elastic boundary conditions, a modeling method of composite laminated rotationally stiffened shells is established. Firstly, the first-order shear deformation theory (FSDT) and the modified Fourier series method are effectively applied to establish the allowable displacement function of the composite laminated rotationally stiffened shell. Secondly, the energy function of composite laminated rotationally stiffened shell is established, and the simulation of complex elastic boundary and coupling boundary is realized by using artificial virtual spring technology. Thirdly, the Rayleigh-Ritz method is used to solve the energy function. Finally, the vibration characteristics of composite laminated rotationally stiffened shells are obtained and analyzed. In the analysis of numerical results, the fast and uniform convergence of analysis modeling and the accuracy of the calculated results are verified. On this basis, the effect of some important parameters such as thickness-to-radius ratio and length-to-radius ratio of shell, boundary spring stiffness values, cone apex angle, thickness and width of laminated beams, number of stiffeners on the vibration characteristics of composite laminated rotationally stiffened shell is studied. In theory, it makes up for the vibration characteristics analysis of composite laminated rotationally stiffened shells. In practical application, it guides the noise reduction design of related structures.

Periodic orbits, pair nucleation, and unbinding of active nematic defects on cones.

Geometric confinement and topological constraints present promising means of controlling active materials. By combining analytical arguments derived from the Born-Oppenheimer approximation with numerical simulations, we investigate the simultaneous impact of confinement together with curvature singularity by characterizing the dynamics of an active nematic on a cone. Here, the Born-Oppenheimer approximation means that textures can follow defect positions rapidly on the timescales of interest. Upon imposing strong anchoring boundary conditions at the base of a cone, we find a rich phase diagram of multidefect dynamics, including exotic periodic orbits of one or two +1/2 flank defects, depending on activity and nonquantized geometric charge at the cone apex. By characterizing the transitions between these ordered dynamical states, we present detailed understanding of (i) defect unbinding, (ii) defect absorption, and (iii) defect pair nucleation at the apex. Numerical simulations confirm theoretical predictions of not only the nature of the circular orbits but also defect unbinding from the apex.

Formation of Alternating Surfactant-Enriched and Surfactant-Depleted Phases in the Taylor Cone of a Nanoelectrospray.

The electrospray ionization of highly conductive solutions containing Triton X-100, a nonionic surfactant, is found to induce alternating periods of surfactant enrichment and depletion when the concentration of the surfactant is near the critical micelle concentration (CMC) and when the flow rate is on the order of 10 nL/min. Analyzing the surfactant-protein mixture shows that the protein is partially denatured during the surfactant enrichment. The measurement of the phospholipid and oligosaccharide mixture prepared in the surfactant solution shows that the ion signal of the lipid is in phase with, and the hydrophilic oligosaccharide is out of phase with the surfactant signal. The results suggest that this novel phenomenon can be exploited for in situ separation of compounds in ESI-MS. Besides the ion signal, the condition of the alternating phase is also reflected in the spray current and Taylor cone's apex angle. The phase separation is likely related to the formation of a micelle in the Taylor cone and can be selectively triggered by tuning the flow rate with emitter voltage for an on-demand application.

Simulation of liquid cone formation on the tip apex of indium field emission electric propulsion thrusters

Field emission electric propulsion (FEEP) thrusters possess excellent characteristics, such as high specific impulse, low power requirements, compact size and precise pointing capabilities, making them ideal propulsion devices for micro-nano satellites. However, the detection of certain aspects, such as the evolution process of the liquid cone and the physical quantities at the cone apex, proves challenging due to the minute size of the needle tip and the vacuum environment in which they operate. Consequently, this paper introduces a computational fluid dynamics (CFD) model to gain insight into the formation process of the liquid cone on the tip apex of indium FEEP. The CFD model is based on electrohydrodynamic (EHD) equations and the volume of fluid (VOF) method. The entire cone formation process can be divided into three stages, and the time-dependent characteristics of the physical quantities at the cone apex are investigated. The influences of film thickness, apex radius size and applied voltage are compared. The results indicate a gradual increase in the values of electrostatic stress and surface tension stress at the cone apex over an initial period, followed by a rapid escalation within a short duration. Apex configurations featuring a small radius, thick film and high voltage exhibit a propensity for liquid cone formation, and the cone growth time decreases as the film thickness increases. Moreover, some unstable behavior is observed during the cone formation process.

Thermoelastic analysis of axisymmetric conical shells: Investigating stress–strain response under uniform heat flow with semi-coupled approach

ABSTRACT This study addresses the issue of thermal stresses and strains in a thin-walled conical shell subjected to uniform heat flow along its side surfaces and at both ends of the thermal insulation shell. The governing equations are derived using a semi-coupled static thermoelastic equation and an energy equation. The energy equation ignores strain rate effects, but static behavior equations consider temperature variations in axisymmetric thin-walled conical shells. Semicoupled methods, due to their simpler analysis, are suitable for thermal stress analysis when structural and thermal disturbances differ significantly. To obtain solutions, the Galerkin finite element method is employed, yielding valuable insights. Using the Galerkin reduced weight residual method, the sum of the weight residuals on the shell thickness is set to zero. Through a comprehensive problem-solving approach, the effects of increasing the angle of the cone apex in different thermal boundary conditions are investigated in two one-ended and two-ended cases.

Nonlinear Vibration of Truncated Open Conical Nanoshells Under Harmonic Excitation

The nonlinear forced vibration behavior of truncated open conical nanoshells is investigated in this paper. Nonlocal elasticity theory has been employed to modify the size-dependent effect of micro/nanostructure. Von Karman nonlinear strains are used to consider the geometric nonlinearity of the nanoshells. Using Hamilton’s principle, the equations of motion and boundary conditions of truncated open conical nanoshells are derived. Galerkin method is used to solve the governing equations. Then, to determine the nonlinear forced vibration behavior of truncated open conical nanoshells, complex averaging and arc-length continuation methods are employed. Finally, the effect of nonlocal parameters, cone apex angle, the amplitude of harmonic excitation, structural damping coefficient, and geometrical parameters on the nonlinear frequency response of the truncated open conical nanoshells are discussed.

Free convection flow from a heated cone with a downward tip submerged in Newtonian fluids employing a finite volume technique

Computational fluid dynamics technique have been employed to capture the plain convective flow past from a heated cone with a tip downward in various stagnant Newtonian fluids. Using detailed isotherm patterns around the cone under steady-state conditions examine the heat transfer characteristics that have been reported. The findings illustrate the distribution of the friction factor, average Nusselt number and local Nusselt number around the cone surface over a wide range of dimensionless values such as Grashof and Prandtl numbers. The guiding PDEs such as conservation of mass, momentum and energy are solved by finite volume method using commercial software of ANSYSCFX16.0. To simplify the governing equations while capturing the natural convection, Boussinesq approximation has been adopted to coupling the flow and temperature fields.This study reveals the contribution of various angles (φ = 15°,300and45°), diverse Prandtl numbers (Pr = 0.71,5,10,20,50) and distinct Grashof numbers (GrL = 104, 105, 106) for the efficacy of them over the slant surface of the cone. The heat transmission and parametric features of these processes have been discussed for how heat can be transferred from a heated cone when it is submerged in a liquid. Visualization of the effects of different parameters for different cone apex angles was done by displaying the results graphically. The present simulations are in a near match to the numeric values appeared in the literature.

Dynamics of a Laser-Induced Cavitation Bubble near a Cone: An Experimental and Numerical Study

A bubble’s motion is strongly influenced by the boundaries of tip structures, which correspond to the bubble’s size. In the present study, the dynamic behaviors of a cavitation bubble near a conical tip structure are investigated experimentally and numerically. A series of experiments were carried out to analyze the bubble’s shape at different relative cone distances quantitatively. Due to the crucial influence of the phase change on the cavitation bubble’s dynamics over multiple cycles, a compressible two-phase model taking into account the phase change and heat transfer implemented in OpenFOAM was employed in this study. The simulation results regarding the bubble’s radius and shape were validated with corresponding experimental photos, and a good agreement was achieved. The bubble’s primary physical features (e.g., shock waves, liquid jets, high-pressure zones) were well reproduced, which helps us understand the underlying mechanisms. Meanwhile, the latent damage was quantified by the pressure load at the cone apex. The effects of the relative distance γ and cone angle θ on the maximum temperature, pressure peaks, and bubble position are discussed and summarized. The results show that the pressure peaks during the bubble’s collapse increase with the decrease in γ. For a larger γ, the first minimum bubble radius increases while the maximum temperature decreases as θ increases; the pressure peak at the second final collapse is first less than that at the first final collapse and then much greater than that one. For a smaller γ, the pressure peaks at different θ values do not vary very much.

Active topological defect absorption by a curvature singularity

We leverage the Born–Oppenheimer approximation to present a general description of topological defects dynamics in p-atic materials on curved surfaces. Focusing on the case of an active nematic, we find that activity induces a geometric contribution to the motility of the defect. Moreover, in the case of a cone, the simplest example of a geometry with curvature singularity, we find that the motility depends on the deficit angle of the cone and changes sign when the deficit angle is greater than π, leading to the change in active behavior from contractile (extensile) to extensile (contractile) behavior. Using our analytical framework, we then identify for positively charged defects the basin of attraction to the cone apex and present closed-form predictions for defect trajectories near the apex. The analytical results are quantitatively corroborated against full numerical simulations, with excellent agreement when the capture radius is small compared to the cone size.

Numerical investigation of displacement pile installation in silica sand

The penetration of deep foundations into sand is a classic geotechnical engineering problem that carries not yet fully understood aspects of the soil-pile interaction. The complexity of rigorous numerical and experimental studies of these foundations is well-stated in the literature. Extensive measurements of the properties of the soil that surrounds the pile are difficult to obtain experimentally. In this paper, the analysis of the installation of closed-ended, displacement piles in two silica sands is undertaken. Centrifuge tests from the literature on loose and dense dry sand samples are employed for validation of the numerical models, based on the Arbitrary Lagrangian-Eulerian (ALE) method. To capture the constitutive behaviour of the sand, the hypoplastic constitutive law with intergranular strain is adopted. After successful validation, an investigation on the variation of the initial conditions of the soil mass surrounding the pile during its installation is undertaken, and their influence on the tip resistance, the radial stresses, and the void ratio at the target penetration depths are identified. This paper illustrates the effect of cone apex angle on the state of sand after installation. Flat-ended piles tend to create clear zones of dilated material around the shaft.

Associations between Orbital Morphology and Exophthalmos Changes after Endoscopic Orbital Decompression to Treat Thyroid-related Orbitopathy

Purpose: To investigate orbital morphology parameters associated with exophthalmos changes in patients undergoing endoscopic orbital decompression to treat thyroid-related orbitopathy.Methods: In total, 33 eyes of 18 patients with thyroid-related orbitopathy who underwent endoscopic orbital decompression were included in this retrospective study. Data were collected before and 6 months after surgery. We performed Hertel exophthalmometry and derived orbital morphology parameters from two-dimensional facial computed tomography records. Parameters associated with exophthalmos reduction on univariate linear regression analysis were subjected to multivariate linear regression analyses.Results: Univariate linear regression showed that the preoperative length of the medial orbital wall (β = 0.179, <i>p</i> = 0.032) and the postoperative distance from the cone apex to the medial wall defect (β = -0.139, <i>p</i> = 0.006) were associated with exophthalmos reduction after endoscopic orbital decompression surgery. Multivariate linear regression of these two parameters showed that the distance from the apex to the medial wall defect was associated with exophthalmos reduction (β = -0.118, <i>p</i> = 0.019).Conclusions: The postoperative distance from the cone apex to the medial wall defect was associated with exophthalmos reduction. In patients with thyroid-related orbitopathy, this association should be considered when planning endoscopic orbital decompression.

Thermal Elastohydrodynamic Lubrication Analysis for Rolling Cone Enveloping End Face Worm Drive

To explore the thermal elastohydrodynamic lubrication performance of rolling cone enveloping end face worm drive, the mathematical model of thermal elastohydrodynamic lubrication is established based on the meshing theory of rolling cone enveloping end face worm drive and elastohydrodynamic lubrication theory. With the help of the numerical analysis software MATLAB, the thermal elastohydrodynamic lubrication performance under smooth conditions is selectively analyzed by the multigrid method. Besides, the effects of throat coefficient, cone apex radius and half cone angle of the rolling cone on thermal elastohydrodynamic lubrication performance are analyzed at the meshing out of the transmission pair. The results show that the thermal elastohydrodynamic lubrication film thickness at meshing out of the worm gear is the smallest; the oil film thickness, oil film pressure and oil film temperature are reduced from meshing in to meshing out. The oil film temperature at the interlayer is the largest. The oil film temperature at the end face worm surface is the smallest. The small half-cone angle of the cone apex radius and larger throat coefficient and cone apex radius may achieve better thermal elastohydrodynamic lubrication performance of rolling cone enveloping end face worm drive.

Numerical and Physical Modeling of the Effect of the Cone Apex Angle on the Penetration Resistance in Coarse-Grained Soils

The tip shape of penetrometers and piles has an important influence on the soil resistance mobilized during penetration. Blunt or flat tips typically generate greater penetration resistances, which can lead to refusal during in-situ testing and pile driving in the field. Results are presented from numerical and experimental investigations on probes with conical tips of varying apex angles to quantify the effect of the apex angle on the mobilized penetration resistance and associated failure mechanisms. Discrete element modeling (DEM) simulations were performed in unconfined and confined (i.e., stress-controlled) specimens to model shallow and deep penetration conditions, respectively. Centrifuge penetration tests were performed by quasi-statically advancing an instrumented probe to a depth-to-probe-diameter ratio of 16.7. The numerical and experimental results indicate that at shallow depths, the sharper tips mobilize smaller penetration resistances. In deep penetration conditions, the changes in penetration resistance with tip apex angle are less pronounced. Based on the results of the two investigations and values reported in the literature, a relationship characterizing the functional form between tip apex angle and normalized penetration resistance is proposed. A mesoscale analysis of the DEM simulation shows differences in the failure mechanisms induced by sharp and blunt tips: the zone where large particle displacements and stress changes occur is large and located below the tip for penetration with blunt tips, whereas the zone is smaller and located both laterally and below the tip for sharp tips.

Kinetics of orientation processes in nematic liquid crystals in a periodically changing magnetic field

The method of obtaining a magnetic field, the intensity vector of which moves along a conical surface at different values of the angle between the intensity vector and the axis of rotation of the magnetic field, the values of the intensity and angular velocity of rotation of the magnetic field, is described. An increase in the phase shift between the intensity vector and the director is found with an increase in the angle at the apex of the magnetic field cone. In the studied range of angular velocities of rotation of the magnetic field at angles between the intensity vector and the axis of rotation of the magnetic field less than 60 °, the director moves synchronously with the field. An exponential character of the dependence of the orientation relaxation time, which characterizes the rapid action of liquid crystal technical devices, on pressure and temperature is established.

Effect of a Conical Cellulose Structure on Horseradish Peroxidase Biomacromolecules

The effect of a dielectric conical structure on the adsorption properties of an enzyme on mica was studied by atomic force microscopy (AFM) with the example of horseradish peroxidase (HRP). The cone used was a cellulose cone with a 60° apex angle. Namely, AFM allowed us to reveal an increase in the enzyme’s aggregation during its adsorption onto mica from the solution incubated near the cone apex for 40 min—as compared with the control enzyme samples incubated far away from the cone. In contrast, no change in the HRP adsorption properties was observed after shorter (10 min) incubation of the sample near the cone. The enzymatic activity of HRP was found to be the same for all the enzyme samples studied. Our findings should be considered upon designing biosensors (in particular, those intended for highly sensitive diagnostic applications) and bioreactors containing conical structural elements. Furthermore, since HRP is widely employed as a model enzyme in studies of external impacts on enzymes determining food quality, our data can be of use in the development of food-processing methods based on the use of electromagnetic radiation (microwave treatment, radiofrequency heating, etc.).

Heat transfer characteristics of jet impingement onto the concave surface of a cone

ABSTRACT Heat transfer coefficient measurements for jet impingement onto the concave surface of a cone with apex angles equal to 30° and 70° are reported in this study. Static pressure measurements along the cone surface are also reported which aid in explaining the results from the heat transfer measurements. The conical geometry finds application for the heating of aircraft gas turbine engine nose bullet region which could experience ice formation whenever aircraft operates at higher altitudes. The concave surface of the cone is heated by impinging hot air tapped from the compressor. The heat transfer coefficients, which are significantly different compared to flat surface impingement, and are scarcely available, are reported in this study. The influence of the jet axis coincident with the cone axis and impinging into apex region was studied first. The methodology where a thin stainless-steel foil is heated with a known heat flux by passing electric current through it and then measuring the detailed surface temperature using an infrared thermal camera, was used to compute the wall Nusselt distribution. The Nusselt number variation is presented as a function of nondimensional apex to nozzle spacing (L/D) and the nondimensional axis displacement (O/D). Three different diameter (D equal to 10 mm,14 mm and 20 mm) pipes were used for the concentric impingement case and the Nusselt number distribution was observed not depend on the injection diameter. The jet Reynolds number was varied between 25000 and 82000. The peak Nusselt number values are similar to those for flat plate impingement and do not occur at the cone apex, but at a nondimensional distance between 3.2 and 3.9 for 4.25 < L/D < 10.25 for the 30° cone. The peak Nusselt number values increase by almost 30% with decrease in the L/D from 10.2 to 3.0. Wall static pressure measurements indicated that the peak Nusselt number values occur in regions where the interaction between the incoming and outgoing streams is strongest – these regions occur at distances downstream from the stagnation region toward cone exit. The peak heat transfer coefficient location could not be obtained for the 70° cone, but the measured maximum values are higher by 30–50% compared to those for the 30° case. The jet is able to penetrate further toward the apex of the cone for 70° cone compared to 30° cone shifting the peak heat transfer locations closer to the apex for larger apex angle case. There is insignificant influence of jet diameter on Nusselt number variation for the three diameter values investigated in this study. The influence of displacing the jet axis by a distance equal to half the jet diameter in a direction perpendicular to the cone axis was also studied but detailed measurements were possible only for the 30° cone. Two semi-circular regions, one close to the impingement tube and the other away from the tube, displaying similar heat transfer coefficient behavior were observed. A peak in the Nusselt number occurs in each semi-circular region and the magnitude of the peaks are nearly same and they lie on either side of the peak location observed for the concentric impingement case when the flow geometric parameters are similar for the two cases. The measurements for the 70° cone exhibited all features of the 30° cone but the maximum values were higher by nearly 40% for this case.

Work needed to force the water-air interface down in the re-entrant structured capillary pore

The re-entrant structure of the membrane surface has attracted researchers' attention recently, due to its ability to make the membrane surface more wetting resistant-either in water or in liquids of low surface tension. The underlying principle of this approach is that an energy barrier has to be overcome when the transition occurs from the Cassie Baxter state to the Wenzel state of the rough membrane surface, which prevents the passage of liquid through the membrane pore. In this work, the energy barrier was evaluated for the cone-shaped pore based on Young's theory of the capillary force. It was found that the energy barrier is enhanced by increasing the angle of the apex of the cone, the pore length, and the contact angle. The effects of the first two geometrical factors, the angle of apex of cone and pore length, are much stronger than the effect of the contact angle. It is believed that this work will offer a guideline for the rational membrane design to reduce, and even prevent, the pore wetting of membranes, particularly for oil/water separation and membrane distillation.

Bearing capacity of conical footing on anisotropic and heterogeneous clays using FEA and ANN

The paper presents axisymmetric FEA solutions for the bearing capacity of conical footings embedded in anisotropic and inhomogeneous clays using NGI-ADP model. The bearing capacity factor of conical footings is defined to be a function of three dimensionless parameters: (i) the cone apex angle, (ii) the increasing strength gradient ratio, and (iii) the anisotropic shear strength ratio. A series of parametric studies is carried out to portray the influence of all input parameters on the bearing capacity factors. Based on the FEA results of 216 investigated cases, the artificial neural network (ANN) is adopted to capture the relationship between input parameters and output bearing capacity factors. The complex relationship between input parameters and output bearing capacity is studied through the use of design charts and failure patterns. A new accurate equation with a high value of R2 is proposed and the sensitivity of each input parameter on the output results is scored by adopting the results from the ANN model. This study has provided some practical insights into the performance of conical footings embedded in anisotropic and inhomogeneous clays.