Positional Accuracy of Holes When Drilling in Inclined Workpiece Surfaces Part 2: Mathematical Force Model

1994 ◽  
Vol 208 (2) ◽  
pp. 141-152 ◽  
Author(s):  
J Kaminski ◽  
R Crafoord
Keyword(s):  
Mathematical Model ◽  
Computer Simulations ◽  
Force Model ◽  
Positional Accuracy ◽  
Contact Areas ◽  
Axis Of Rotation

In this paper, a drill wandering mechanism when drilling in inclined workpieces is described. A mathematical model for calculation of chip areas on the chisel edge and the lips has been developed and implemented by a computer. Simulations of the forces that occur on the contact areas between the drill tip and the workpiece are presented and discussed. A mathematical model for calculation of the resultant drill deflection, deviations in the drill axis of rotation and the position of its centre point as the drill penetrates the material is also proposed.

scholarly journals Effectiveness of a salt transport cascade in the renal medulla: computer simulations

1987 ◽  
Vol 252 (6) ◽  
pp. F1095-F1102 ◽  
Author(s):  
P. Lory
Keyword(s):  
Mathematical Model ◽  
Active Transport ◽  
Computer Simulations ◽  
Renal Medulla ◽  
Salt Transport ◽  
Countercurrent System ◽  
Federation Proc

Based on morphological observations, it has been concluded that the upper parts of the long descending limbs of Henle's loops should be able to secrete salts into the tubular fluid (Kriz, W. Federation Proc. 42:2379-2385, 1983). In the same article, a hypothesis is given depicting how this active transport in concert with certain characteristics of the medullary architecture might produce a transport cascade toward the papillary tip, thus supporting the accumulation of salts in this region. The effectiveness of the proposed mechanism can be judged by a mathematical model only. The computer simulations of the present study demonstrate that this mechanism indeed leads to an increase of the concentrating capability of the renal countercurrent system.

A wear model for subrough surface contacts of martensitic steels

2019 ◽  
Vol 233 (10) ◽  
pp. 1574-1584 ◽  
Author(s):  
Anatoliy G Suslov ◽  
Mikhail G Shalygin
Keyword(s):  
Mathematical Model ◽  
Structural Heterogeneity ◽  
Martensitic Steels ◽  
Adhesion Forces ◽  
Friction Couple ◽  
Wear Model ◽  
Theoretical Concepts ◽  
Contact Areas ◽  
Wear Modelling ◽  
Deformation Component

This article includes an analysis of techniques for determining wear of contact areas to show two lines of wear research – due to deformations and adhesion forces. It has been established that surface subroughness is not presently taken into account in calculations of wear despite the fact that this surface property is of increasing research interest. The paper aims to develop a mathematical model of wear for subrough surface contacts in the context of deformation and theories of adhesion. Mathematical wear modelling for subrough surfaces is based on studies on causes of their formation due to phase and structural heterogeneity of the material. The article considers contact interaction at the level of surface subroughness; physics of interaction of contact areas at the level of surface subroughness; a mathematical model of deformation and adhesive wear for subrough surface contacts of martensitic steels; some analytical dependences of the theoretical model for a body-centred tetragonal lattice. Analysis of the theoretical concepts shows that wear of subrough surface contacts depends largely on the deformation component, while the adhesive component is significant only during the ‘bedding-in’ period for a friction couple. The materials of the article can be used to calculate the wear for contact areas at the level of surface subroughness.

A Hysteresis Restoring Force Model of Disc-Shaped Metal Rubber Isolation Component

2012 ◽  
Vol 271-272 ◽  
pp. 186-189 ◽  
Author(s):  
Feng Li Cao ◽  
Hong Bai Bai ◽  
Zhong Bo He ◽  
Guo Quan Ren
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Experimental Verification ◽  
Vibration Isolation ◽  
Practical Significance ◽  
Force Model ◽  
Stiffness Coefficient ◽  
Restoring Force ◽  
Restoring Force Model ◽  
Metal Rubber

Dynamic load experiments of the disc-shaped metal rubber isolation component are performed. Through analyzing variation law of the parameters with amplitude and frequency, which are stiffness coefficient, damping coefficient and damping component factor, the hysteresis restoring force model which is able to fully reveal the dynamic characteristics of the component is established. The experimental verification results show that the theoretic calculations are consistent with the experimental data, which verifies the practicability and effectiveness of mathematical model and parameter identification. It has important practical significance for design of vibration isolation component with different requirements.

Mathematical model and computer simulations of telomere loss

2019 ◽  
Vol 465 ◽  
pp. 78-89 ◽  
Author(s):  
Ana Martinčić Špoljarić ◽  
Ivica Rubelj ◽  
Miljenko Huzak
Keyword(s):  
Mathematical Model ◽  
Computer Simulations ◽  
Telomere Loss

scholarly journals The charge percolation mechanism and simulation of Ziegler-Natta polymerizations, Part VII: Effects of the distribution of chromium active centers on silica on the polymerization of ethylene

2008 ◽  
Vol 73 (1) ◽  
pp. 97-111 ◽  
Author(s):  
Dragoslav Stoiljkovic ◽  
Branka Pilic ◽  
Misa Bulajic ◽  
Nebojsa Djurasovic ◽  
Nikolaj Ostrovskii
Keyword(s):  
Mathematical Model ◽  
Transition Metal ◽  
Induction Period ◽  
Computer Simulations ◽  
Chromium Oxide ◽  
Silica Surface ◽  
Chromium Concentration ◽  
Active Centers ◽  
Metal Compounds ◽  
Surface Discontinuity

The charge percolation mechanism (CPM) of olefin polymerization in the presence of transition metal compounds has been applied to explain the polymerization of ethylene by silica supported chromium oxide. In the previous work of this series, the fundamental issues and mechanism of this polymeri?zation were presented. In this work the compatibility of the CPM with the em?pirical findings is confirmed. The CPM has been applied to explain: the appea?rance of an induction period; the deactivation of active centers and the forma?tion of oligomers; the effects of chromium concentration on the silica surface, the silica surface discontinuity and the pore size of silica on polymerization and the formation of the structure of polyethylene. A mathematical model has been derived to explain the effects of the CrOx/SiO2 ratio on the productivity of Phil?lips catalysts in the polymerization of ethylene. The empirical findings have also been confirmed by computer simulations.

Properties of the paraelectric-solid and molten phases of sodium nitrite

1982 ◽  
Vol 382 (1783) ◽  
pp. 471-482 ◽  
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Molten Salt ◽  
Computer Simulations ◽  
Sodium Nitrite ◽  
Electrostatic Interactions ◽  
Paraelectric Phase ◽  
Force Model ◽  
Axis Parallel ◽  
High Degree

Molecular dynamics computer simulations have been made on the paraelectric phase of solid sodium nitrite and on the melt. The interionic-force model used in the calculations is based on a rigid-ion representation of the electrostatic interactions, supplemented by a set of atom-atom potentials. Reorientation of the anions in the solid is shown to occur predominantly about an axis parallel to the crystallographic c -direction. The structure of the molten salt is found to be characterized by a high degree of local octahedral coordination. Agreement with the available experimental data is satisfactory.

Fuzzy Track-Keeping Steering Design for a Precise Control of the Ship

2013 ◽  
Vol 196 ◽  
pp. 140-147 ◽  
Author(s):  
Józef Małecki
Keyword(s):  
Mathematical Model ◽  
Fuzzy Logic ◽  
Fuzzy Control ◽  
Computer Simulations ◽  
Control Law ◽  
Intelligence Gathering ◽  
Precise Control ◽  
Counter Measures ◽  
Command Signals ◽  
The Military

In this paper we design the fuzzy logic autopilot to precise control and a track-keeping control of the ship. Precise control of ship has known an increasing interest in the last years. The main benefits of usage of autopilot for control of ship can be removing a man from the dangers of the undersea environment and reduction in cost of exploration of deep seas. Currently, it is common to use the special ship to accomplish missions as the inspection of coastal and off-shore structures, cable maintenance, as well as hydrographical surveys. In the military field they are employed in such tasks as surveillance, intelligence gathering, torpedo recovery and mine counter measures. Hence, a problem of its ability to move along a reference path and keep a desired orientation is regarded. A non-linear mathematical model describes the vehicle’s dynamics. Command signals are generated by an autopilot with fuzzy control law implemented. Some results of computer simulations are provided to demonstrate effectiveness, correctness and usefulness of the approach.

scholarly journals METHOD FOR MEASURING ERROR ESTABLISHMENT IN 5-AXIS MILLING MACHINES WITH A TOUCH PROBE

2019 ◽  
Vol 3 ◽  
pp. 77
Author(s):  
Tsvetan Kaldashev
Keyword(s):  
Mathematical Model ◽  
Measuring Error ◽  
Axis Of Rotation ◽  
Milling Machines ◽  
Touch Probe

The present paper proposes a method for measuring and compensating for error establishment. The measurement is done with a touch probe and the measuring program is a macro program. A mathematical model was developed to experimentally determine the error of non-alignment of the axis of rotation of the workpiece with the physical axis of rotation of mass C. A virtual approach to compensate for the error of establishment by using a postprocessor for the particular machine was also proposed.

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