The Stereokinetic Phenomenon from Two or Three Points

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 209-209 ◽  
Author(s):  
H Komatsu
Keyword(s):  
Visual System ◽  
Relative Velocity ◽  
Frontoparallel Plane ◽  
End Points ◽  
Apparent Position ◽  
Apparent Length ◽  
Straight Line ◽  
The Absolute ◽  
Centre Of Rotation

The stereokinetic phenomenon occurs when certain 2-D patterns are rotated in the frontoparallel plane. Zanforlin explained this phenomenon by the hypothesis of the minimisation of velocity differences. Our visual system minimises relative velocity differences between the various points of the pattern, which determines the apparent height of the stereokinetic cone. Zanforlin and Vallortigara applied the hypothesis to a rotating straight line or the two end-points of a straight line. They showed that the apparent length of the line does not depend on the absolute physical velocities of the end-points but rather on the relative velocities, and the absolute physical velocities merely affect the apparent position of the line with respect to the plane of the disk. In the present experiments with two points, the apparent length indeed depended on the relative velocities, but the absolute velocities did not affect the apparent position. The apparent position of the line with respect to the plane of the disk depended on whether or not the centre of rotation was between the two end-points. Adding one more point gave a triangle that appeared slanted into 3-D space. The shape composed of three points was held constant, even when rotated and slanted. The height of the apparent triangle also depended on the relative velocities.

scholarly journals Morphometric characteristics of the collagen of periimplant zones by using suture material of different structure and chemical composition with the aim of correction of age skin changes

2019 ◽  
Vol 23 (1) ◽  
pp. 104-109
Author(s):  
M. Turkevуch
Keyword(s):  
Chemical Composition ◽  
Suture Material ◽  
Threshold Function ◽  
Quantitative Composition ◽  
Skin Changes ◽  
Collagen Formation ◽  
Black And White ◽  
Straight Line ◽  
Collagen Density ◽  
The Absolute

Morphometric analysis of collagenogenesis of perimplant zones was carried out at application of suture material of different structure and chemical composition for the purpose of establishing the quantitative composition of collagen. The thickness of the sleeve wall was measured using ImageJ ver.1.48u (1,2) using the “straight line” tool. The collagen density of the clutch wall and the collagen density in the surrounding tissues were measured by converting the images into black and white format, followed by obtaining a binary image using the “threshold” function of the ImageJ program. It is established that according to the indicators of thickness of a collagen sleeve and its density leaders are materials LLS. In terms of the density of collagen in tissues close to the clutch, the absolute leader is LLS material. In general, according to the values of all three parameters, the absolute leader in the intensity of collagen formation as the walls of the muffle and surrounding tissues is the LLS material, in the second place, on the aggregate of the three indicators, the materials NS and EV are located.

scholarly journals Optical axes of catadioptric systems including visual, Purkinje and other nonvisual systems of a heterocentric astigmatic eye

2010 ◽  
Vol 69 (3) ◽  
Author(s):  
W. F. Harris
Keyword(s):  
Visual System ◽  
Optical Axis ◽  
The Other ◽  
Optical Systems ◽  
Numerical Examples ◽  
Straight Line ◽  
Optical Axes ◽  
Catadioptric Systems ◽  
Reflecting Surfaces ◽  
Special Case

For a dioptric system with elements which may be heterocentric and astigmatic an optical axis has been defined to be a straight line along which a ray both enters and emerges from the system.  Previous work shows that the dioptric system may or may not have an optical axis and that, if it does have one, then that optical axis may or may not be unique.  Formulae were derived for the locations of any optical axes.  The purpose of this paper is to extend those results to allow for reflecting surfaces in the system in addition to refracting elements.  Thus the paper locates any optical axes in catadioptric systems (including dioptric systems as a special case).  The reflecting surfaces may be astigmatic and decentred or tilted.  The theory is illustrated by means of numerical examples.  The locations of the optical axes are calculated for seven optical systems associated with a particular heterocentric astigmatic model eye.  The optical systems are the visual system, the four Purkinje systems and two other nonvisual systems of the eye.  The Purkinje systems each have an infinity of optical axes whereas the other nonvisual systems, and the visual system, each have a unique optical axis. (S Afr Optom 2010 69(3) 152-160)

scholarly journals Condition Absolute Stability Control System of Electromagnetoelastic Actuator for Communication Equipment

2020 ◽  
Vol 8 (1) ◽  
pp. 08-15 ◽  
Author(s):  
Sergey Mikhailovich Afonin
Keyword(s):  
Control System ◽  
Absolute Stability ◽  
Stability Control ◽  
Straight Line ◽  
Stability Control System ◽  
Stationary Set ◽  
The Absolute ◽  
Communication Equipment ◽  
Stable Control

We obtained the condition absolute stability on the derivative for the control system of electromagnetoelastic actuator for communication equipment. We applied the frequency methods for Lyapunov stable control system to calculate the condition absolute stability control system of electromagnetoelastic actuator. We used Yakubovich criterion absolute stability system with the condition on the derivative. The aim of this work is to determine the condition of the absolute stability on the derivative for the control system of electromagnetoelastic actuator. We received the stationary set of the control system of the hysteresis deformation of the electromagnetoelastic actuator. The stationary set is the segment of the straight line.

scholarly journals Method for determining the kinematic parameters of the vertical rotor blades for the destruction of the tuberous layer

2020 ◽  
pp. 82-90
Author(s):  
V. A. Volsky V. A. ◽  
V. S. Bonchik
Keyword(s):  
Hydraulic Drive ◽  
Extreme Points ◽  
Geometric Shape ◽  
Kinematic Parameters ◽  
End Points ◽  
End Point ◽  
Vertical Rotor ◽  
Starting Point ◽  
The Absolute ◽  
Angle Of Rotation

Annotation Purpose. Development of a technique for determining the velocities of collision of the blades with the tuberous layer, the trajectory of movement, the magnitude and direction of the velocities of the most characteristic points. Methods. The research was carried out using the basic provisions of theoretical mechanics, statistics, probability theory, methods of differential calculations, mathematical modeling and applied programming. The studies were carried out on a specially designed laboratory installation using a vertical rotor hydraulic drive and strain gauge equipment mounted on a tractor, as well as a set of variable connecting plates for setting the machine operating modes. Results. The calculations of the absolute collision velocities of the blades of the lower and upper beaters of the vertical rotor at the start and end points, respectively, are performed. The geometric shape of the working surfaces and the direction of rotation for the extreme points of the outer contours of the blades of the lower and upper beaters of the vertical rotor of the potato harvester are substantiated. Conclusions. Using the above technique, as well as graphical dependences, we calculated the rational kinematic parameters of the blades of the lower and upper beaters of the vertical rotor, respectively, at the start and end points, where the greatest destruction of the tuber layer. For the lower beater blade, the absolute collision speed at the angle of rotation ωнt = 120° at the starting point = 1.6 m/s, at the end point – = 1.94 m/s. For the upper beater blade, the absolute collision speed at the angle of rotation ωвt = 120° at the starting point = 1.4 m/s, at the end point – = 1.92 m/s. Therefore, according to the specified rational kinematic parameters of the blades of the lower and upper beaters of the vertical rotor, it is possible to design the geometric shape of the surfaces of the crushing working bodies of potato harvesters. Keywords: blade, breaking surface, breasts, potatoes.

scholarly journals A generalisation of Lorentz-equivalence in a substratum theory

1966 ◽  
Vol 6 (1) ◽  
pp. 101-105 ◽  
Author(s):  
S. J. Prokhovnik
Keyword(s):  
Relative Velocity ◽  
Uniform Motion ◽  
Straight Line ◽  
Substratum Theory

AbstractIt has been shown that the assumption of a specified cosmological substratum leads to the Lorentz-equivalencc of observers whose uniform motion in the substratum lies along a common straight line. The result is generalised for any pair of unaccelerated observers thus confirming that only the relative velocity of such observers is relevant in relating their observations of an event.

scholarly journals THE EFFECT OF CHANGES OF ENVIRONMENT ON THE ELECTRICAL AND IONIC PATTERN OF MUSCLE

1956 ◽  
Vol 40 (2) ◽  
pp. 263-288 ◽  
Author(s):  
F. H. Shaw ◽  
Shirley E. Simon ◽  
B. M. Johnstone ◽  
Mollie E. Holman
Keyword(s):  
Action Potential ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Na Pump ◽  
Straight Line ◽  
Slight Elevation ◽  
The Absolute ◽  
K Concentration ◽  
Toad Bufo ◽  
External K

The resting and action potentials of sartorius muscles of the toad, Bufo marinus, have been measured under varying conditions of external environment. At the same time, analyses for Na+ and K+ content were carried out. There was a slight elevation of 2 mv. when the measurements were made in phosphate-Ringer instead of in bicarbonate-Ringer. The R.P. was independent of the hydrogen ion concentration between pH 6.5 and 8.5, although at these pH's there was marked alteration in the level of Na+ and K+ in the muscle. Alteration of the external K+ level between 0 and 50 m.eq./liter has little influence on the internal K+ concentration. When the log of the external K+ concentration is plotted against the R.P. there is not a linear relationship until the external K+ is raised above 12 m.eq./liter, at which point the cell is unexcitable. Above this value a straight line with a slope of 58 mv. per ten-fold change in concentration is obtained, but the absolute values at any point are about 35 per cent higher than those which would be given by the Nernst equation. Alteration of the external Na+ level within a range of 45 to 650 m.eq./liter resulted in marked changes in the internal Na+ content, without, however, having any effect on the ratio Na+out/Na+in. This ratio has remained at about 3 in spite of marked fluctuations in the absolute value of the internal and external Na+ levels. When the Na+ level is lowered there is a decrease in the height of the action potential although there is no alteration in the ratio Na+out/Na+in. As the Na+ level is raised the height of the action potential is not affected even in the presence of a fivefold increase in Na+ in the Ringer. The results do not support the conclusion that the bioelectric potentials can be calculated from the ionic ratios by means of simple physical chemical hypotheses such as the Nernst or Goldman equations. The maintenance of the normal K+ content of the cell cannot be accounted for by a Donnan mechanism. No definite evidence has been produced to explain the mechanism of a Na+ "pump." In other words, the concept of a Na+ pump requires that there shall be a physico- or organochemical mechanism which will distinguish between Na+ and K+ (or other) ions. There is evidence that Na+ can be extruded against a concentration gradient. On the other hand the cell is able to maintain a constant ratio of external to internal Na+ even when the cell has been severely damaged by very high external Na+ levels.

Gas Laws

2009 ◽  
Author(s):  
Christopher O. Oriakhi
Keyword(s):  
Absolute Temperature ◽  
Absolute Zero ◽  
Standard Temperature ◽  
Gas Laws ◽  
Temperature Scales ◽  
Straight Line ◽  
Temperature And Pressure ◽  
The Absolute ◽  
The Relationship ◽  
Boyle’S Law

Volumes and densities of gases vary significantly with changes in pressure and temperature. This means that measurements of the volumes of gases will likely vary from one laboratory to another. To correct for this, scientists have adopted a set of standard conditions of temperature and pressure (STP) as a reference point in reporting all measurements involving gases. They are 0°C (or 273 K) and 760mmHg or 1 atm (or 1.013×105 N m−2 in S.I. units). Therefore standard temperature and pressure, as used in calculations involving gases, are defined as 0°C (or 273 K) and 1 atmosphere (or 760 torr). (Note: For calculations involving the gas laws, temperature must be in K.) Boyle’s law states that the volume of a given mass of gas at constant temperature is inversely proportional to the pressure. The law can be expressed in mathematical terms: V α 1/P or PV = k at constant n and T Since P×V = constant, problems dealing with P–V relationships can be solved by using the simplified equation: P1V1 = P2V2 Here P1, V1 represent one set of conditions and P2, V2 represent another set of conditions for a given mass of gas. Charles’s law states that the volume of a given mass of gas is directly proportional to its absolute temperature. So if the absolute temperature is doubled, say from 300 K to 600 K, the volume of the gas will also double. A plot of the volume of a gas versus its temperature (K) gives a straight line. A notable feature of such a plot is that the volume of all gases extrapolates to zero at the same temperature, −273.2◦C. This point is defined as 0 K, and is called absolute zero. Thus, the relationship between the Kelvin and Celsius temperature scales is given as: K = 0°C + 273. Scientists believe that the absolute zero temperature, 0 K, cannot be attained, although some laboratories have reported producing 0.0001 K.

Curves with corners

1962 ◽  
Vol 55 (5) ◽  
pp. 326-329
Author(s):  
Clarence R. Perisho
Keyword(s):  
Step Function ◽  
Analytical Geometry ◽  
Line Segments ◽  
Absolute Value ◽  
Geometric Figures ◽  
Straight Line ◽  
The Absolute ◽  
Continuous Curves ◽  
Sharp Corners

The graphs of functions usually studied in algebra and analytical geometry are smooth, continuous curves, with no sharp corners or discontinuities. There is, however, a certain fascination about equations that represent curves with unusual characteristics. The absolute-value notation can be used to write equations for many common geometric figures1 and to simplify equations which involve the step function.2 Absolute-value notation can also be used to write the equations of graphs involving straight-line segments with any number of corners or vertices.

A Robot Calibration Method Based on Virtual Closed Kinematic Chain

2010 ◽  
Vol 139-141 ◽  
pp. 2162-2167
Author(s):  
Tian Qin Wang ◽  
Chang Liu ◽  
Zhen Pu Zhang ◽  
Da Cheng Wang
Keyword(s):  
Genetic Algorithm ◽  
Laser Beam ◽  
Kinematic Chain ◽  
Calibration Method ◽  
Kinematic Parameters ◽  
Robot Calibration ◽  
Straight Line ◽  
Simulating Analysis ◽  
The Absolute ◽  
Calibration Approach

This paper offers a robot calibration approach based on the virtual closed kinematic chain so that the absolute location accuracy of a robot can be improved. The calibration approach suggests that laser beam can be mounted on the robot’s end so as to form a virtual closed kinematic chain in the interest of enlarging the pose errors to proper extent, in this way straight line equations in space can be acquired when the robot positions are changed continuously, in the end the robots’ kinematic parameters can be figured out by genetic algorithm while measurement can be totally avoided in the calibration. Calibrating practices, simulating analysis and experiments on robots show that the approach can improve the absolute calibrating accuracy effectively.

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