COMBINED EXTRUSION OF GLASSES WITH A CONICAL BOTTOM. METHODOLOGY FOR CALCULATING TECHNOLOGICAL PARAMETERS OF THE TRADITIONAL PROCESS OF CONSTRAINED EXTRUSION

The methodology for calculating the energy-power and deformation parameters of the traditional process of constrained extrusion of glasses with a conical bottom part, including preliminary obtaining by molding the outer conical section of the bottom part of the product and the subsequent reverse extrusion of the glass with an internal cavity of the required geometry, is presented. The extrusion of both non-hardening and hardening material is considered. In the latter case, the account of the hardening of the extruded material is described in detail. The above formulas allow us to determine such important parameters of the stamping process as total and specific deforming force, maximum pressure on the die wall, and an increase in the yield stress.

COMBINED EXTRUSION OF GLASSES WITH A CONICAL BOTTOM. METHODOLOGY FOR CALCULATING TECHNOLOGICAL PARAMETERS OF THE TRADITIONAL FREE EXTRUSION PROCESS

The method of calculating the energy-power and deformation parameters of the traditional process of free extrusion of glasses with a conical bottom part, including preliminary formation of the outer conical section of the bottom part of the product by molding and the following reverse extrusion of the glass with an internal cavity of the required geometry. The extrusion of both non-hardening and hardening material is considered. In the latter case, the account of the hardening of the extruded material is described in detail. The above formulas allow us to determine such important parameters of the stamping process as total and specific deforming force, maximum pressure on the die wall, and an increase in the yield stress.

Teaching the Notion Conic Section with Computer

The article discusses the problem of introducing and constructing mathematical concepts using a computer. The Wolfram Mathematica 12 symbolic calculation system is used at each stage of the complex spiral process to form the notion of conic section and the related concepts of focus, directrix and eccentricity. The nature of these notions implies the use of appropriate animations, 3D graphics and symbolic calculations. Our vision of the process of formation of mathematical concepts is presented. The notions ellipse, parabola and hyperbola are defined as the intersection of a conical surface with a plane not containing the vertex of the conical surface. The conical section is represented as a geometric location of points on the plane for which the ratio of the distance to the focus to the distance to the directrix is a constant value. The lines of hyperbola and ellipse are determined by their foci. The equivalence of different definitions for conical sections is commented.

Finite element simulation and statistical investigation of an orthodontic mini-implant’s stability in a novel screw design

One of the essential aspects of the mini-implant’s successful application is its stability after being installed in the bone. The stability of the mini-implant affected the most by its geometry. In the present research, the effect of the geometry-related parameters of the mini-implant on its lateral displacement is investigated by Finite Element (FE) modeling using ABAQUS software. The parameters studied include length, diameter, pitch, and depth of the screw threads; besides, length and angle of the conical section. The Taguchi method was used to prevent many experiments. The mesh convergence tests and experimental tests confirmed the FE model quantitatively and qualitatively. Mean of means and variance analysis determined the parameters significance and their contribution on the stability. The screw diameter and length have the most contribution to mini-implant’ displacement. The effect of screw pitch was less than that for length and diameter. The conical section improved the initial stability by creating compressive stress and additional friction in its surrounding bone. No significant effects on the stability of the mini-implant have been observed for the non-threaded part. By examining the effect of thread depth on its stability by defining the ratio of thread depth to the internal diameter and to maintain the strength of the screw the optimal value for internal to external ratio is set at about 0.7.

Analysis of Gas-Liquid-Solid Three-Phase Flows in Hydrocyclones Through a Coupled Method of VOF and DEM

Liquid-gas-solid three-phase flows in hydrocyclones are studied numerically in this paper by employing a coupled method of volume of fluid (VOF) and discrete element model (DEM) with RSM turbulence model. The numerical method is validated by comparing the calculated results to those of experiments published in literature about the separation of particle flows in hydrocyclones. Since VOF-DEM model could capture the gas-liquid interface of particle flows, the three-dimensional formation process of the air-core together with the formation of the spiral trajectory of particles are depicted for the first time. In addition, the effects of the particle concentration ? (less than 12%) on the air-core formation time Tf and diameter Da are studied systematically, which has not been reported in literature. The increase of ? has both positive and negative actions on the change of Tf and Da, and compromises of two kinds of actions generate the valley or peak of curves of Tf vs ? and Da vs ?, respectively. Moreover, the results for three hydrocyclones with different cone angles are also compared to study the effects of the cylindrical and conical section on the air-core formation and the separation performance of the hydrocyclones. By analyzing the flow fields and the pressure changes inside the hydrocyclones, qualitative explanations of the relevant discoveries are given in this paper. The results will be helpful in the investigation of the multiphase flow behaviors in the hydrocyclone and in the selection of the appropriate hydrocyclone.

Plastic Shaping of Concentrator-Waveguide Tip for Ultrasound Endovascular Ablation

One of the most effective methods of treating intravascular formations at present is the use of stepped ultrasonic waveguide systems of a tubular type (concentrators-waveguides) with a hollow spherical tip, the presence of which makesit possible to supply liquid media to the dislocation zone of an intravascular formation with the aim of additional cavitation effect and as efficiently as possible. destroy intravascular formations due to vibration impact. Based on the results of the analysis on the features of the existing shaping methods for obtaining a hollow spherical tip of the concentrator-waveguide, it is advisable to use methods of plastic deformation – expansion and crimping. The paper presents results of preliminary calculations, numerical modeling and experimental studies of tip shaping processes of the concentrator-waveguide by distribution and crimping. On the basis of the finite element method in the environment of the ABAQUS software package, modeling of the expansion and crimping of a pipe billet was carried out, which has made it possible to: evaluate the stress-strain state of the deformable conical section of the billet, the change in wall thickness during the forming process and calculate the length of the billet for the design of the conical section; to establish the patterns of the influence of geometric parameters on the power modes of the distribution process; to set the parameters of the modes of forming the tip of the concentrator-waveguide by the method of distribution and crimping, which ensure the formation of the required geometry. The obtained results of preliminary calculation, numerical modeling and experimental studies of tip shaping processes of the concentrator-waveguide by distribution and crimping have similar values, which confirms the correctness of using both the method of preliminary calculation and numerical modeling in the development of the technology for manufacturing the concentrator-waveguide.

Exploratory development of a rotary offset crusher

SYNOPSIS The quest for efficiency in comminution is an ongoing concern as comminution usually constitutes a major cost component in the metal production industry. Such improvements can be made by circuit optimization or development of more efficient equipment. A novel crusher, known as the rotary offset crusher (ROC), promises to deliver in this space. The ROC was invented in 2002 by Michael Hunt, Henry Simonsen, and Ian Sinclair, but failed to garner enough support to progress to production. The original design concept was recently rekindled, and a laboratory version of the crusher has been built and commissioned at the University of the Witwatersrand. The crusher is simple in design, with two cylindrical discs that are parallel to each other, and, as the name implies, there is an offset between the vertical axes of the discs. The top disc has a conical section on its lower face, and this creates a crushing zone between the opposite faces of the two spinning discs. Centrifugal motion transports particles through the crushing zone. Batch experiments have been conducted with quartz at various crusher settings (discs offset, rotational speed, and vertical exit gap) for various feed size distributions. The indications so far suggest that the disc speed is a key factor affecting the performance. Size reduction ratios as high as 11 were recorded from experiments with quartz at a speed of 830 r/min. Keywords: rotary offset crusher, comminution, throughput.

Lymphoma of the uterine cervix- a rare clinical presentation: A case report

Background/Aim. Lymphomas are malignant diseases of lymphocytes. There are two basic types of lymphoma: Hodgkin's lymphoma (HL) whose main characteristic is the presence of Reed-Sternberg cells and non-Hodgkin's lymphoma (NHL), which presents a heterogeneous group of diseases, and depending on the growth rate and the course of the disease, they can be indolent (slow-growing) and aggressive (fast-growing). Follicular lymphoma (FL) is the most common indolent form of NHL, while diffuse large B-cell lymphoma (DLBCL) is the most common aggressive form. Case report. This paper presents a case of NHL, DLBCL, localized in the cervix, histo-pathologically diagnosed in a 35-year-old woman who, after a cervical biopsy, was patho-histologically diagnosed with mild dysplasia (CIN1 / L-SIL) of the cervical epithelium and, after that, an infection with Human Papilloma Virus (HPV), subtypes 16 and 31 was proven. The diagnosis of DLBCL was patho-histologically confirmed on a conical section of the vaginal portion of the uterus, after which the disease was treated with eight cycles of chemotherapy (HT) according to the RCHOP protocol. Conclusion. The coexistence of CIN1 / L-SIL and NHL is random and may overlook concomitant cervical lymphoma, which is usually localized subepithelially, if the biopsy is not adequately performed and if HPV serotyping is not performed.