scholarly journals Formation surfaces of Monge by the kinematic method in AutoCAD environment

2019 ◽  
Vol 15 (2) ◽  
pp. 106-116
Author(s):  
Viktoryna A Romanova
Keyword(s):  
Tangent Plane ◽  
Sine Wave ◽  
Circular Cone ◽  
Dynamic Mode ◽  
Developable Surface ◽  
Monitor Screen ◽  
Straight Line ◽  
Kinematic Method ◽  
Conical Surfaces

Aims of research. Studying the possibility of forming Monge carved surfaces, defined by the method of their formation, creating an algorithm and program in the AutoLISP language to demonstrate the formation of surfaces in the AutoCAD environment in a dynamic mode. Methods. Monge carved surfaces are formed by a flat curve, located in the tangent plane to the fixed guide of the developable surface, when the plane and the curve roll along the guide surface without sliding. The described method of formation of these surfaces allows to perform their formation by the kinematic method in the AutoCAD environment using AutoLISP software. The article describes the construction of the Monge surfaces using cylindrical and conical surfaces as guides. A straight line and a sine wave are used as the forming lines. Results. An algorithm and a program in the AutoLISP language were created to form sets of compartments of several Monge surfaces and to visualize the formation of these surfaces in a dynamic mode by sequentially displaying the compartments on the monitor screen. The mini-film about formation of Monge surface by rolling a plane with a straight line along a circular cone is created. In the mini-film the drawings received by transformation of drawings of the AutoCAD environment are used.

scholarly journals Vizualizing of semi-regular polyhedrons in AutoCAD environment

2019 ◽  
Vol 15 (6) ◽  
pp. 449-457
Author(s):  
Viktoryna A. Romanova
Keyword(s):  
Programming Language ◽  
Functional Programming ◽  
Dynamic Mode ◽  
Structural Shape ◽  
Monitor Screen ◽  
Research Software ◽  
Truncated Octahedron ◽  
Regular Polyhedra ◽  
Electronic Model ◽  
Kinematic Method

The paper examines the automated formation by the kinematic method of the surfaces of Archimedes' semi-regular polyhedra of three forms: truncated tetrahedron, truncated octahedron and truncated icosahedron. To solve this problem, AutoCAD and the built-in programming language AutoLISP were used. Each of these five semi-regular polyhedra of Archimedes has faces of two kinds. In this regard, the surface of a separate polyhedron is considered to consist of two structural forms. Each structural shape is formed in the AutoCAD environment from the compartments of the surfaces of the faces of the polyhedron of the same type, and each compartment is assigned to a specific layer of the drawing. The formation of constructive forms is provided by user-defined functions developed in the functional programming language AutoLISP. User-defined functions not only form images of surfaces, but also perform all the necessary calculations. The electronic model of each polyhedron is formed by the union of its structural forms. A block is formed from it. The surface formation of each polyhedron performs user-defined functions that provide “freezing” of drawing layers intended for surface compartments, insertion of a block with an electronic model of the polyhedron, and sequential “defrosting” of drawing layers. When there is a “thawing" of the layers of the drawing, the process of forming a polyhedron is shown on the monitor screen. As a result of research software that includes userdefined functions for the formation of an electronic model of selected polyhedrons and visualization of the process of formation of their surfaces in a dynamic mode was created.

A new kinematic method for mapping seismic reflectors

Geophysics ◽  
1999 ◽  
Vol 64 (5) ◽  
pp. 1594-1602 ◽  
Author(s):  
Jingping Zhe ◽  
Stewart A. Greenhalgh
Keyword(s):  
Numerical Scheme ◽  
Graphical Method ◽  
Common Tangent ◽  
Curved Boundaries ◽  
Curved Boundary ◽  
Straight Line ◽  
Kinematic Method ◽  
The Common ◽  
Seismic Reflectors ◽  
Arbitrary Velocity

This paper presents a modern version of an old technique of common tangent reflection migration. Rather than using the graphical method of swinging arcs and looking for the envelope of touching tangents on widely separated geophones, we use a numerical scheme of searching along each isochron, constructed by a wave‐equation‐based modeling scheme for arbitrary velocity media, to find the common tangent points. The assumption is made that the receivers are close together so that the interface can be locally approximated by a straight line, although different pairs of receivers permit different tangents to be found, enabling a curved boundary to be migrated. The technique can be extended to several shot gathers to map multiple curved boundaries. Synthetic examples are used to illustrate the capabilities of the method and the effect of using an erroneous velocity distribution.

Devolution of Inhomogeneities in Bone Structure—Predictions of Adaptive Elasticity Theory

1980 ◽  
Vol 102 (4) ◽  
pp. 287-293 ◽  
Author(s):  
K. Firoozbakhsh ◽  
S. C. Cowin
Keyword(s):  
Stress State ◽  
Elastic Body ◽  
Bone Structure ◽  
Cylindrical Body ◽  
Sine Wave ◽  
Initial Shape ◽  
Straight Line ◽  
Living Bone ◽  
Homogeneous Stress ◽  
Anisotropic Elastic

In this paper we consider an initially inhomogeneous adaptive elastic body subjected to a steady homogeneous stress state. The adaptive elastic body, which is a model for living bone tissue, is inhomogeneous in both its anisotropic elastic properties and its density. The principal result of the paper is the determination of the devolution of the initially inhomogeneous body to a homogeneous body under the influence of the steady homogeneous stress state. A cylindrical body that is inhomogeneous along the axis of the cylinder, but homogeneous in each transverse plane of the cylinder, is used as an example. This cylindrical body is loaded by a steady uniform stress directed along the cylindrical axis. The temporal devolution of an inhomogeneity in the initial shape of a sine wave is illustrated. As time progresses the amplitude of the sine wave decreases, rapidly at first and then more slowly. As time becomes very large the sine wave becomes a straight line signifying that the cylinder has become homogeneous.

Gnomonic Projection of the Surface of an Ellipsoid

1997 ◽  
Vol 50 (2) ◽  
pp. 314-320 ◽  
Author(s):  
Roy Williams
Keyword(s):  
Tangent Plane ◽  
The Body ◽  
Normal Curvature ◽  
Geodesic Mapping ◽  
Straight Line ◽  
Ellipsoid Of Revolution

When a surface is mapped onto a plane so that the image of a geodesic arc is a straight line on the plane then the mapping is known as a geodesic mapping. It is only possible to perform a geodesic mapping of a surface onto a plane when the surface has constant normal curvature. The normal curvature of a sphere of radius r at all points on the surface is I/r hence it is possible to map the surface of a sphere onto a plane using a geodesic mapping. The geodesic mapping of the surface of a sphere onto a plane is achieved by a gnomonic projection which is the projection of the surface of the sphere from its centre onto a tangent plane. There is no geodesic mapping of the ellipsoid of revolution or the spheroid onto a plane because the ellipsoid of revolution or the spheroid are not surfaces whose curvature is constant at all points. We can, however, still construct a projection of the surface of the ellipsoid from the centre of the body onto a tangent plane and we call this projection a gnomonic projection also.

Large Amplitude Vibrations of Strings

1994 ◽  
Vol 61 (2) ◽  
pp. 296-301 ◽  
Author(s):  
A. W. Leissa ◽  
A. M. Saad
Keyword(s):  
Single Mode ◽  
Small Strain ◽  
Sine Wave ◽  
Transverse Displacement ◽  
Coupled Equations ◽  
Transverse Vibrations ◽  
Straight Line ◽  
Highly Nonlinear ◽  
Large Amplitude Vibrations ◽  
Line Equilibrium

The study of nonlinear, free, undamped transverse vibrations of a stretched string may be traced back to an equation of motion developed by Kirchhoff more than a century ago. Subsequent studies have typically assumed small slopes and done little to incorporate longitudinal coupling effects. In the present work a new set of coupled equations is derived. These highly nonlinear equations are solved by means of a newly developed Galerkin procedure which determines variations of the transverse and longitudinal displacements in both space and time. Time variation is determined by incremental use of polynomials. Validity of solutions is verified by independent finite difference solutions. Numerical results are presented for three example problems wherein the string is displaced transversely into a half-sine wave, and released from rest. The problems include: (1) moderate strain (ε0 = 0.005) in the straight line equilibrium position and moderate transverse displacement (δ = 0.1L), (2) moderate strain and large displacement (δ = 0.4L), and (3) small strain (ε0 = 10 −5) and moderate displacement. Plots of transverse and longitudinal displacement with time are shown for all three examples. From these plots it is seen that higher modes are generated when only a single mode is initiated, and that the motion is definitely nonperiodic.

Design and Analysis on the Anti-Lock Braking Control System of a Four-Wheel Vehicle

2014 ◽  
Vol 599-601 ◽  
pp. 864-869 ◽  
Author(s):  
Xi Xia Liu ◽  
Rui Wang ◽  
Lei Yuan
Keyword(s):  
Control System ◽  
Dynamic Mode ◽  
Tire Model ◽  
Vehicle Dynamic ◽  
Slip Ratio ◽  
Matlab Simulink ◽  
Straight Line ◽  
Braking Distance ◽  
Braking Control ◽  
Set Up

A PID Anti-lock Braking Control system has been designed according to the principle and method of vehicle dynamic. A vehicle dynamic mode which includes tire model, the controller model and braking model has been set up by the MATLAB/Simulink software. The vehicle straight line braking condition has been simulated by using the model, compared and analysed the influence of slip ratio and braking distance by the system, the results show that the design was effective and feasible which also can achieve the goal of prevent wheels locking.

scholarly journals Visualizing surface formation of semi-regular polyhedra of Archimedes

2020 ◽  
Vol 16 (4) ◽  
pp. 279-289
Author(s):  
Viktoryna A. Romanova
Keyword(s):  
Geometric Parameters ◽  
Common Method ◽  
Dihedral Angles ◽  
Functional Language ◽  
Surface Formation ◽  
Monitor Screen ◽  
Regular Polyhedra ◽  
Electronic Model ◽  
Kinematic Method ◽  
Special Programs

The most common method of forming semi-control polyhedra consists in cutting off angles and ribs of regular polyhedra by planes. The aim of the work - to consider the automated formation of a number of surfaces of semi-regular Archimedean polyhedra based on the dodecahedron. These include the truncated dodecahedron, the icosododecahedron, the romboicosododecahedron and the truncated icosododecahedron. The formation of surfaces is carried out by the kinematic method in AutoCAD using programs compiled in the AutoLISP language. Methods. The methodology for the formation of these polyhedra provides for truncation of the angles and edges of the dodecahedron. This requires the calculation of a number of geometric parameters of these polyhedra and dodecahedron, such as the value of the truncation of the dodecahedron edges, the size of the edges of truncated polyhedra, the centers of faces, dihedral angles, etc. In order to generate these surfaces, a frame is constructed because the frame lines are used as guides to form surfaces in a kinematic way. The electronic model of each polyhedron is constructed as a set of compartments of surfaces of all its faces, and each compartment is assigned to a certain layer of the drawing. The frame and electronic model of the polyhedra under study are formed by means of user programs composed in the functional language AutoLISP. The process of forming surfaces of selected polyhedra in the AutoCAD environment is provided by special programs that are also compiled in the AutoLISP language. Results. Software was created to demonstrate the process of formation of a number of Archimedes polyhedra on the monitor screen.

Microdensitometer—computer correlation analysis of ultrastructural periodicity

1978 ◽  
Vol 36 (2) ◽  
pp. 32-33
Author(s):  
D.R. Ensor ◽  
C.G. Jensen ◽  
J.A. Fillery ◽  
R.J.K. Baker
Keyword(s):  
Correlation Analysis ◽  
Background Noise ◽  
Computer Control ◽  
Optical Diffraction ◽  
Screw Thread ◽  
Straight Line ◽  
Computer Storage ◽  
Correlation Process ◽  
Electron Microscope Image ◽  
Fixed Beam

Because periodicity is a major indicator of structural organisation numerous methods have been devised to demonstrate periodicity masked by background “noise” in the electron microscope image (e.g. photographic image reinforcement, Markham et al, 1964; optical diffraction techniques, Horne, 1977; McIntosh,1974). Computer correlation analysis of a densitometer tracing provides another means of minimising "noise". The correlation process uncovers periodic information by cancelling random elements. The technique is easily executed, the results are readily interpreted and the computer removes tedium, lends accuracy and assists in impartiality.A scanning densitometer was adapted to allow computer control of the scan and to give direct computer storage of the data. A photographic transparency of the image to be scanned is mounted on a stage coupled directly to an accurate screw thread driven by a stepping motor. The stage is moved so that the fixed beam of the densitometer (which is directed normal to the transparency) traces a straight line along the structure of interest in the image.

Freeze fracture imaging and computer simulation of liposome structure: Membrane geometry and defects

1983 ◽  
Vol 41 ◽  
pp. 646-647
Author(s):  
Joseph A. Zasadzinski
Keyword(s):  
Liquid Crystalline ◽  
Freeze Fracture ◽  
Continuum Theory ◽  
Closed Surfaces ◽  
Straight Line ◽  
Low Weight ◽  
Concentric Spheres ◽  
Membrane Geometry ◽  
Dupin Cyclides ◽  
Limiting Case

At low weight fractions, many surfactant and biological amphiphiles form dispersions of lamellar liquid crystalline liposomes in water. Amphiphile molecules tend to align themselves in parallel bilayers which are free to bend. Bilayers must form closed surfaces to separate hydrophobic and hydrophilic domains completely. Continuum theory of liquid crystals requires that the constant spacing of bilayer surfaces be maintained except at singularities of no more than line extent. Maxwell demonstrated that only two types of closed surfaces can satisfy this constraint: concentric spheres and Dupin cyclides. Dupin cyclides (Figure 1) are parallel closed surfaces which have a conjugate ellipse (r1) and hyperbola (r2) as singularities in the bilayer spacing. Any straight line drawn from a point on the ellipse to a point on the hyperbola is normal to every surface it intersects (broken lines in Figure 1). A simple example, and limiting case, is a family of concentric tori (Figure 1b).To distinguish between the allowable arrangements, freeze fracture TEM micrographs of representative biological (L-α phosphotidylcholine: L-α PC) and surfactant (sodium heptylnonyl benzenesulfonate: SHBS)liposomes are compared to mathematically derived sections of Dupin cyclides and concentric spheres.

Human Enamel Replication

1976 ◽  
Vol 34 ◽  
pp. 180-181
Author(s):  
Norman L. Dockum ◽  
John G. Dockum
Keyword(s):  
Organic Matrix ◽  
Human Teeth ◽  
Human Enamel ◽  
Straight Line ◽  
Ultrastructural Characteristics

Ultrastructural characteristics of fractured human enamel and acid-etched enamel were compared using acetate replicas shadowed with platinum and palladium. Shadowed replications of acid-etched surfaces were also obtained by the same method.Enamel from human teeth has a rod structure within which there are crystals of hydroxyapatite contained within a structureless organic matrix composed of keratin. The rods which run at right angles from the dentino-enamel junction are considered to run in a straight line perpendicular to the perimeter of the enamel, however, in many areas these enamel rods overlap, interlacing and intertwining with one another.

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