A look at motion in the frequency domain

A moving image can be specified by a contrast distribution, c(x,y,t), over the dimensions of space x,y, and time t. Alternatively, it can be specified by the distribution C(u,v,w) over spatial frequency u,v and temporal frequency w. The frequency representation of a moving image is shown to have a characteristic form. This permits two useful observations. The first is that the apparent smoothness of time-sampled moving images (apparent motion) can be explained by the filtering action of the human visual system. This leads to the following formula for the required update rate for time-sampled displays. W(c)=W(l)+ru(l) where w(c) is the required update rate in Hz, W(l) is the limit of human temporal resolution in Hz, r is the velocity of the moving image in degrees/sec, and u(l) is the limit of human spatial resolution in cycles/deg. The second observation is that it is possible to construct a linear sensor that responds to images moving in a particular direction. The sensor is derived and its properties are discussed

Uniform apparent contrast noise: A picture of the noise of the visual contrast detection system

A picture which is a sample of random contrast noise is generated. The noise amplitude spectrum in each region of the picture is inversely proportional to spatial frequency contrast sensitivity for that region, assuming the observer fixates the center of the picture and is the appropriate distance from it. In this case, the picture appears to have approximately the same contrast everywhere. To the extent that contrast detection thresholds are determined by visual system noise, this picture can be regarded as a picture of the noise of that system. There is evidence that, at different eccentricities, contrast sensitivity functions differ only by a magnification factor. The picture was generated by filtering a sample of white noise with a filter whose frequency response is inversely proportional to foveal contrast sensitivity. It was then stretched by a space-varying magnification function. The picture summmarizes a noise linear model of detection and discrimination of contrast signals by referring the model noise to the input picture domain

An orthogonal oriented quadrature hexagonal image pyramid

An image pyramid has been developed with basis functions that are orthogonal, self-similar, and localized in space, spatial frequency, orientation, and phase. The pyramid operates on a hexagonal sample lattice. The set of seven basis functions consist of three even high-pass kernels, three odd high-pass kernels, and one low-pass kernel. The three even kernels are identified when rotated by 60 or 120 deg, and likewise for the odd. The seven basis functions occupy a point and a hexagon of six nearest neighbors on a hexagonal sample lattice. At the lowest level of the pyramid, the input lattice is the image sample lattice. At each higher level, the input lattice is provided by the low-pass coefficients computed at the previous level. At each level, the output is subsampled in such a way as to yield a new hexagonal lattice with a spacing sq rt 7 larger than the previous level, so that the number of coefficients is reduced by a factor of 7 at each level. The relationship between this image code and the processing architecture of the primate visual cortex is discussed

The Effects of Blowing Over Various Trailing-edge Flaps on an NACA 0006 Airfoil Section, Comparisons with Various Types of Flaps on other Airfoil Sections, and an Analysis of Flow and Power Relationships for Blowing Systems

The results are presented of a two-dimensional investigation conducted to determine the effect of blowing over various types of trailing-edge flaps on a wing having the NACA 0006 airfoil section and a drooped-nose flap. The position and profile of the trailing-edge flap, the nozzle height, and the location of the flap with respect to the nozzle were found to be important variables. Data from many investigations were used to make an evaluation of the effects of blowing on lift. An analysis was made of flow and power relationships for blowing systems

Trinity Monotheism and Daniel Howard-Snyder\u27s Diminished Divinity Problem

In this paper, I summarize and defend a model of the Trinity proposed by William Lane Craig and J.P. Moreland, which is called trinity monotheism. An important element of this model is that there are two ways to be divine; either one must be a proper part of the Trinity or the Trinity itself. I answer one objection in Daniel Howard-Snyder’s thorough critique of this model. He calls this objection the Diminished Divinity Problem and supposes that if the property of divinity is exemplified in two different ways, either by being a proper part of the Trinity or by being the Trinity, then this implies that the Persons of the Trinity exemplify a lesser divinity than the Trinity itself. I argue that this objection is mistaken in two ways: (1) it is predicated on a misunderstanding of what Craig and Moreland’s analogy is intended to represent and (2) it argues fallaciously that since a cat skeleton is dissimilar to the cat itself, then the Persons of the Trinity are equally as dissimilar to the Trinity itself. With a successful answer to Howard-Snyder’s objection, one of the main tenets of trinity monotheism is upheld, bolstering the plausibility of the model

Effect of Reynolds number on stability characteristics of a cruciform wing-body

An experimental investigation was conducted to determine the effect of Reynolds number on the stability characteristics of a body with cruciform wings at large angles of attack. Pressure distributions and force and moment data (axial force not measured) are presented for Mach 1.60 and 2.70, Reynolds numbers based on body diameter from approximately 130,000 to 2,800,000, and angles of attack from 0 deg to 50 deg. In general, the data show only small effects of Reynolds number throughout the range of test condition. Also discussed are force balance and pressure data that suggest a direct relationship between wind choking and the onset of a nonlinear stability variaton with angle of attack

The Rise and Fall of IPRA in Australia: 1959 to 2000

The International Public Relations Association (IPRA) was established in 1955 as the lead international organisation for the development and promotion of public relations as a professional communication practice (L’Etang, 2004). Involvement by Australian practitioners in IPRA began in 1959 and became intensive during a 15-year period from 1982 to the late-1990s when a number of Australians took global leadership roles. Drawing from the IPRA archive and recent interviews by the authors with prominent practitioners in Europe and Australia, who were involved in IPRA’s management and leadership, this article establishes the narrative of international engagement by the burgeoning Australian PR sector and explores the aims and effects of its involvement in IPRA. It concludes that IPRA’s impact on the development of the Australian public relations sector and Australian influence on IPRA was largely ephemeral, limited to a decade from 1983 to 1993, and reveals some problematic aspects of industry practice and governance. Nevertheless, Australian practitioners made use of both the symbolism of international endorsement and international connections established through IPRA to transform the national PR sector from a predominantly local focus to an increasingly international outlook at a time when public relations services were expanding rapidly worldwid

Semiquantitative Infrared Analysis of Diketones and Anhydrides in a Reaction Mixture

The ozonolysis of a hydroxymethylene ketone yields a mixture of diketone and anhydride. Treatment of hydroxymethylene camphor with ozone affords, in addition to the expected camphor quinone, a surprisingly large amount of camphoric anhydride (56%) via Baeyer-Villager reaction. Use of infrared absorption to analyze the relative amounts of camphor quinone and camphoric anhydride in a reaction mixture was studied by comparing peak heights of their carbonyl stretching bands