Factors Influencing the Apparent Rotation of a Line on Radially Transformed Backgrounds

Perception ◽  
1983 ◽  
Vol 12 (3) ◽  
pp. 313-322 ◽  
Author(s):  
Nicholas J Wade ◽  
Michael T Swanston ◽  
Hiroshi Ono ◽  
Peter M Wenderoth
Keyword(s):  
Spatial Frequency ◽  
Oblique Line ◽  
Zoom Lens ◽  
Television System ◽  
Vertical Grating ◽  
Apparent Rotation ◽  
Factors Influencing ◽  
Constant Rate ◽  
Orientation Anisotropy ◽  
Angular Subtense

The expansion and contraction of a display consisting of a stationary grating with a superimposed inclined line leads to the apparent rotation of the line. This phenomenon has been investigated in six experiments with the use of a television system with a motorized zoom lens to effect such transformations. The maximum apparent line rotation occurs with the line at 45° to the grating. In experiment 1 a greater magnitude of apparent rotation was found with a vertical grating and an oblique line than vice versa. Zoom-out (contraction) also produced greater rotation than zoom-in (expansion). The orientation anisotropy was not dependent upon the orientation of the display to the retinal meridian (experiment 2): the extent of apparent line rotation was approximately the same with a vertical grating when the head was upright or tilted so that the retinal meridian was at 45°. At a constant rate of zooming, a zoom duration of 2 s produced a larger apparent line rotation than one of 1 s, but it was not influenced by the initial angular subtense of the superimposed line (experiment 3). Neither the spatial frequency of the grating nor the width of the line affected the apparent rotation (experiments 4, 5, and 6). Experiment 5 compared the apparent rotation when the display was zoomed (i) with a fixed surround and (ii) with a surround that also expanded during zooming. The magnitude of rotation in the latter condition was reduced to about 25% of that with a fixed surround. The results are discussed in terms of the discrepancy between the perceived transformations of the background grating and the superimposed line.

Orientation Specificity and Spatial Selectivity in Human Vision

Perception ◽  
1973 ◽  
Vol 2 (1) ◽  
pp. 53-60 ◽  
Author(s):  
J A Movshon ◽  
C Blakemore
Keyword(s):  
Spatial Frequency ◽  
Human Visual System ◽  
Human Vision ◽  
Orientation Tuning ◽  
High Contrast ◽  
Vertical Grating ◽  
Spatial Frequencies ◽  
High Contrast Grating ◽  
Orientation Specificity ◽  
Adaptation Method

An adaptation method is used to determine the orientation specificity of channels sensitive to different spatial frequencies in the human visual system. Comparison between different frequencies is made possible by a data transformation in which orientational effects are expressed in terms of equivalent contrast (the contrast of a vertical grating producing the same adaptational effect as a high-contrast grating of a given orientation). It is shown that, despite great variances in the range of orientations affected by adaptation at different spatial frequencies (±10° to ±50°), the half-width at half-amplitude of the orientation channels does not vary systematically as a function of spatial frequency over the range tested (2·5 to 20 cycles deg−1). Two subjects were used and they showed significantly different orientation tuning across the range of spatial frequencies. The results are discussed with reference to previous determinations of orientation specificity, and to related psychophysical and neurophysiological phenomena.

Apparent Rotation of a Line Superimposed upon Radially Expanding and Contracting Backgrounds

Perception ◽  
1981 ◽  
Vol 10 (3) ◽  
pp. 265-271 ◽  
Author(s):  
Michael T Swanston ◽  
Nicholas J Wade
Keyword(s):  
Oblique Line ◽  
Relative Orientation ◽  
Head Movements ◽  
Apparent Rotation ◽  
Stationary Observer ◽  
Horizontal Grating

An oblique line superimposed on a vertical or horizontal grating appears to rotate when the whole pattern is expanded or contracted. The apparent rotation occurs with head movements towards or away from a stationary grating, or with zooming a grating relative to a stationary observer. The magnitude and direction of the apparent rotation is dependent upon the relative inclination of the line to the grating and is most pronounced with a relative orientation of 45°.

Analysis of woven fabric behavior under punching force

2021 ◽  
pp. 152808372110086
Author(s):  
Magdi El Messiry ◽  
Eman Eltahan
Keyword(s):  
Tensile Strength ◽  
Failure Modes ◽  
Woven Fabric ◽  
Insignificant Change ◽  
Plain Weave ◽  
Factors Influencing ◽  
Failure Energy ◽  
Constant Rate ◽  
Protective Fabrics ◽  
Force Displacement

In several applications, the industrial and protective fabrics might be subjected to punching by the rigid sharp spikes. Fabric resistance to the penetration of the puncher at a constant rate was studied. The analysis of the factors influencing the resistance of the fabric and an explanation of the puncture mechanism were generated. Punching force-displacement curves were obtained and four noticeable fabric failure modes were observed. A special setup was designed so that the fabric sample can be subjected to the biaxial stresses during the puncture tests. This paper studies the puncture behaviors of the plain, twill 1/3, and twill 2/2 woven fabric designs. It was found that the increase in the number of fabric layers from one to three and the number of picks/cm from 17.6 to 27.2 would elevate the punching resistance and the punching energy by 354% and 333%, respectively, with the insignificant change in the values of specific punching force and energy. Plain weave design proved to have higher values than twill design. A high correlation was observed between fabric tensile strength, fabric Young’s modulus, fabric failure energy and its punching force and punching energy.

scholarly journals Analysis of the Single Frequency Network Gain in Digital Audio Broadcasting Networks

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 569
Author(s):  
Kamil Staniec
Keyword(s):  
Signal Strength ◽  
Single Frequency ◽  
Digital Audio ◽  
Television System ◽  
Protection Level ◽  
Effective Coverage ◽  
Single Frequency Network ◽  
Digital Audio Broadcasting ◽  
Factors Influencing ◽  
Reception Mode

The single frequency network (SFN) is a popular solution in modern digital audio and television system networks for extending effective coverage, compared to its traditional single-transmitter counterpart. As benefits of this configuration appear to be obvious, this paper focuses on the exact analysis of so-called SFN gain—a quantitative effect of advantage in terms of the received signal strength. The investigations cover a statistical analysis of SFN gain values, obtained by means of computer simulations, with respect to the factors influencing the coverage, i.e., the protection level, the reception mode (fixed, portable, mobile), and the receiver location (outdoor, indoor). The analyses conclude with an observation that the most noteworthy contribution of the SFN gain is observed on the far edges of the networks, and the least one close to the transmitters. It is also observed that the highest values of the SFN gain can be expected in the fixed mode, while the protection level has the lowest impact.

Some Factors Influencing the Road Wear of Tires

1952 ◽  
Vol 25 (3) ◽  
pp. 656-668 ◽  
Author(s):  
R. D. Stiehler ◽  
M. N. Steel ◽  
J. Mandel
Keyword(s):  
Climatic Conditions ◽  
Effect Of Temperature ◽  
The Road ◽  
Synthetic Rubber ◽  
Factors Influencing ◽  
Primary Object ◽  
Constant Rate ◽  
Weight Method ◽  
One Year ◽  
Mutually Independent

Abstract Three road tests of tires for tread wear were statistically designed. The design of test equalized the treatment of tires, and included a study of some of the factors influencing the road wear of tires in addition to the primary object of the test. Among these factors were the effects of vehicle, wheel position, day of test, climatic conditions, and length of storage. A study was made also of two methods of measurement-depth of tread grooves and weight loss. The information on these factors was obtained at no increase in cost of test. It was found that atire loses weight at essentially a constant rate, whereas, the depth of the tread grooves decreases at a declining rate, which results in a bias in the tread wear ratings. The weight method was also found to be more sensitive than the depth method. The study of the effects of vehicle and wheel positions led to the conclusion that differences in the rate of wear on different wheels do not affect the tread wear comparisons, since the rate in slow wearing positions is proportional to that in fast wearing positions, and the coefficient of variation is about the same. These results led to the conclusion that geometric rather than arithmetic averages be used in evaluating tread wear. The study of the effect of day of testing and of climatic conditions indicated that the surface temperature of the road and tire has a pronounced effect on rate of wear. Natural rubber treads containing channel black wore faster as the temperature increased, whereas, synthetic rubber tread containing furnace blacks wore faster as the temperature decreased. Other treads wore at about the same rate as the temperature changed. The effect of temperature on tread wear was greater in many instances than the effect of a lower coefficient of friction on wet roadways. Storage of tires generally increased the rate of wear; however, some treads did not wear faster after one year of storage. The object of one test was to determine the effect of type of rubber and black on tread wear. It was found that the rubber and black are mutually independent in their effects. The behavior of natural and synthetic rubbers or of channel and furnace blacks with a change in temperature made it impossible to compare them without stating the conditions of test.

FACTORS INFLUENCING THE NET CONSUMPTION OF GLUCOSE BY THE ISOLATED PERFUSED RAT LIVER

1965 ◽  
Vol 43 (4) ◽  
pp. 617-626 ◽  
Author(s):  
Ellen R. Gordon
Keyword(s):  
Steady State ◽  
Rat Liver ◽  
Glucose Consumption ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Steady State Condition ◽  
Isolated Rat Liver ◽  
Factors Influencing ◽  
Constant Rate ◽  
Isolated Rat

Several factors have been found to influence the ability of the isolated rat liver to achieve and maintain a steady-state condition when receiving glucose at a constant rate. The net glucose consumed could be altered by starving the experimental animal for 72 hours, by changes in the blood of donor rats produced by starvation, by lowering of the pH of the perfusate, and by injury to the liver itself. In cases in which the net glucose consumption by the liver was lowered by starvation of the donor rats for 24 hours, the addition of insulin to the perfusate doubled the net consumption of glucose. These experiments demonstrate that insulin has an effect on the net consumption of glucose by the liver.

Factors influencing spatial frequency extraction in faces: A review

2018 ◽  
Vol 93 ◽  
pp. 123-138 ◽  
Author(s):  
Coline Jeantet ◽  
Stéphanie Caharel ◽  
Raymund Schwan ◽  
Joëlle Lighezzolo-Alnot ◽  
Vincent Laprevote
Keyword(s):  
Spatial Frequency ◽  
Factors Influencing

scholarly journals Faces behind bars: illusory eye movements induced by gratings

2021 ◽  
Vol 2 ◽  
Author(s):  
Benjamin Balas
Keyword(s):  
Eye Movements ◽  
Spatial Frequency ◽  
Illusory Motion ◽  
Single Image ◽  
Object Shape ◽  
Vertical Grating ◽  
Moire Pattern ◽  
Wide Range ◽  
The Relationship ◽  
Forward Looking

I describe a novel illusion in which perceived eye movements are induced by moving a vertical grating across a single image of a forward-looking face. By varying properties of the grating, a wide range of illusory eye movements can be generated including nystagmus, a ‘swirling’ motion of the eyes, and vertical scanning/blinking. I suggest that the phenomenon is closely related to the footsteps illusion, but reveals the role that object shape and grating spatial frequency together play in determining the direction of illusory motion that observers perceive. I also discuss the relationship between the current illusion, the footsteps illusion, and Moire pattern animations.

Determination of the Best Emulsion for the Microscopy of Crystals

1981 ◽  
Vol 39 ◽  
pp. 32-33
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Spatial Frequency ◽  
Information Transfer ◽  
Signal To Noise Ratio ◽  
Experimental Situation ◽  
Photographic Emulsion ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Frequency Space ◽  
Noise Ratio

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.

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