Inclusion Behavior in a Curved Bloom Continuous Caster with Mold Electromagnetic Stirring

Mold electromagnetic stirring (M-EMS) has been widely used in many continuous casters. In order to have a deep insight into the collision-coalescence among inclusions under M-EMS by a Eulerian approach, the effects of Archimedes electromagnetic force on the inclusion are expressed by three-dimensional Archimedes electromagnetic slipping velocity and Archimedes electromagnetic collision. Numerical results show that a turbulent collision is the most important factor to cause inclusions to collide with each other, Archimedes electromagnetic collision has a minor effect, Stokes collision is the third factor, and Brownian can be ignored. In the case of M-EMS, there are two recirculation zones above and below the M-EMS central cross-section, and the inclusion spatial distributions have the inverted U-shape.

Residual Stress Measurements in a 316L Uniaxial Samples Manufactured by Laser Powder Bed Fusion

Uniaxial samples have been manufactured for tension/compression testing from 316L stainless steel by laser powder bed fusion (LPBF). Samples manufactured by LPBF are known to contain high levels of residual stresses. These uniaxial samples were built from a solid cylindrical rod and subsequently machined to reduce the central cross section of the sample to the required gauge diameter and improve the surface finish. Finite element (FE) models have been developed to simulate the LPBF process of the rods, their removal from the build plate and subsequent machining into the tension/compression samples. High tensile residual stresses were predicted at the surface of the samples, balances by similar magnitude compressive stresses along their axis. Post machining however, these stresses were reduced by around 80% or more. Residual stress measurements were performed on the samples post machining using the neutron diffraction techniques. These measurements confirmed that negligible residual stresses remained in the samples post removal from the build plate and machining.

Modelling levitated 2-lobed droplets in rotation using Cassinian oval curves

A simple model of rotating 2-lobed droplets is proposed by setting the outline shape of the droplet to the Cassinian oval, a mathematical curve that closely resembles in shape. By deriving the governing equation of the proposed model and obtaining its stationary solutions, the relationship between the angular velocity of rotation and the maximum deformation length is explicitly and precisely calculated. The linear stability analysis is performed for the stationary solutions, and it is demonstrated that the stability of the solutions depends only on the ratio of the deformation length to the radius of the central cross-section of the droplet, which is independent of the physical properties of the droplet. Via comparison with an experimental study, it is observed that the calculated result is consistent with the deformation behaviour of actual 2-lobed droplets in the range where the stationary solution of the proposed model is linearly stable. Therefore, the proposed model is a suitable model for reproducing the steady deformation behaviour of 2-lobed droplets in a wide range of viscosities, surface tensions, densities and initial radii of the droplet, and especially if the viscosity of the droplet is low, the entire process of deformation of the 2-lobed droplet, including the unsteady breakup process, can be very well reproduced by the proposed model.

Methane-air flame thermometry using planar lase-induced fluorescence (PLIF)

Temperature measurements were performed in a central cross-section of a partially premixed atmospheric methane-air flame of a laboratory burner using two-line planar laser-induced fluorescence (PLIF) of OH radicals and coherent anti-Stokes Raman scattering (CARS) by H2 molecules. The results of a comparative analysis of 2D PLIF and single-point CARS thermometry of the flame are presented.

Photoreceptor Inner and Outer Segment Junction Reflectivity after Vitrectomy for Macula-Off Rhegmatogenous Retinal Detachment

Purpose. To evaluate the spatial distribution of photoreceptor inner and outer segment junction (IS/OS) reflectivity changes after successful vitrectomy for macula-off retinal detachment (PPV-mOFF) using spectral domain optical coherence tomography (SdOCT).Methods. Twenty eyes after successful PPV-mOFF were included in the study. During a mean follow-up period of 15.3 months, SdOCT was performed four times. To evaluate the IS/OS reflectivity a four-grade scale was used.Results. At the first follow-up visit the IS/OS had very similar reflectivity in entire length of the central scan with total average value of 1,05. At the second visit the most significant increase of the reflectivity was observed in temporal and nasal parafovea with average values of 2,17 and 2,22, respectively. The third region of increased reflectivity of an average value of 2,33 appeared during the third follow-up visit and was located in the foveola. At the last follow-up visit in entire central cross section the IS/OS reflectivity exceeded grade 2 reaching the highest average values in nasal and temporal parafovea and foveola.Conclusions. A gradual increase of the IS/OS reflectivity was observed in eyes after PPV-mOFF. The process is not random and starts independently in the peripheral and central part of the macula which may be attributed to the variable regenerative potential of cones and rods.

Experimental Research on the Character of Resist Explosion for Reinforced Concrete Structure of Sand Filling

Explosion containment structure (chamber) is used to protect personnel and experimental equipment during the destruction of explosion environmental for research blasting or disposal exploder. Reinforced concrete has advantiage of low cost and simple process in buliding ,so it was usually used of buliding the structure of resist explosion.This paper demonstrates reinforced concrete structures character of resist explosion under envirmonent of filling sand,the hoop strain of structure central cross section were measured loaded by different mass explosive charges,the safe criterion of reinforced concrete structure was obtained. Loaded by the explosion,the damage mechanics of reinforced concrete structure that diameter equal to height was analysed,and the method for avoiding the structure fail was suggest.

Large Deformation Behavior of Pipe Bends Subjected to In-Plane Bending

Ground liquefaction during earthquakes can produce a significant amount of lateral ground displacement. For buried gas pipelines, deformation and strain are likely to be concentrated on the pipe bends. Closing and opening in-plane bending experiments were conducted for various kinds of pipe bends until the measured strain exceeded 25% using pipe specimens of a diameter from 100 to 300 mm. The deformation behavior was different between the closing mode and the opening one. In the closing mode, an ovalization was observed in the central cross section of the bend, and internal pressure was maintained in all experiments. On the other hand, unique behavior was observed in the opening mode. When the pipe diameter was 300 mm (Do/t=43), local buckling was observed at the center of the bend. However, when Do/t was less than 32 (200 mm in diameter), the flexural rigidity of the bend became much higher than that of a straight pipe, and buckling and rupture were observed in the straight pipe. Finite element analyses were carried out using linear shell elements, and the validity of the numerical modeling technique over 25% of plastic strain was confirmed.

Lyapunov Exponents and Stochastic Stability of Coupled Linear Systems Under Real Noise Excitation

The almost-sure asymptotic stability of a class of coupled multi-degrees-of-freedom systems subjected to parametric excitation by an ergodic stochastic process of small intensity is studied. Explicit asymptotic expressions for the largest Lyapunov exponent for various values of the system parameters are obtained by using a combination of the method of stochastic averaging and a well-known procedure due to Khas’minskii, from which the asymptotic stability boundaries are determined. As an application, the example of the flexural-torsional instability of a thin elastic beam acted upon by a stochastically fluctuating load at the central cross-section of the beam is investigated.