Showing papers by "University of Waterloo published in 1984"
TL;DR: The performances of SIMPLE, SIMPLER, and SIMPLEC are compared for two recirculating flow problems and several modifications to the method are shown which both simplify its implementation and reduce solution costs.
Abstract: Variations of the SIMPLE method of Patankar and Spalding have been widely used over the past decade to obtain numerical solutions to problems involving incompressible flows. The present paper shows several modifications to the method which both simplify its implementation and reduce solution costs. The performances of SIMPLE, SIMPLER, and SIMPLEC (the present method) are compared for two recirculating flow problems. The paper is addressed to readers who already have experience with SIMPLE or its variants.
3,276 citations
TL;DR: Intra-subject variability of joint moment patterns over the stride period was high at the knee and hip, but low at the ankle and in a recently defined total limb pattern, called support moment.
779 citations
TL;DR: In two experiments, no evidence for perception without awareness was found in a Stroop-priming task when the threshold for detecting color-word primes was measured reliably by a forced-choice procedure.
Abstract: In two experiments, no evidence for perception without awareness was found in a Stroop-priming task when the threshold for detecting color-word primes was measured reliably by a forced-choice procedure. Color words and color patches were either congruent or incongruent, and no priming occurred when the words were presented at the detection threshold. However, systematic increases in the level of detection for the primes led to correlated increases in the magnitude of priming. The results provide no support for recent claims that priming is a more sensitive indicator of perceptual processing than detection based upon verbal report. A resolution to the apparent discrepancy between the present results and previously reported findings is suggested.
556 citations
01 Jan 1984
TL;DR: This paper presents a new method for using cubic interpolating splines in a key frame animation system which produces a very general class of interpolating cubic splines which includes the cardinal splines as a proper subset.
Abstract: This paper presents a new method for using cubic interpolating splines in a key frame animation system. Three control parameters allow the animator to change the tension, continuity, and bias of the splines. Each of these three parameters can be used for either local or global control. Our technique produces a very general class of interpolating cubic splines which includes the cardinal splines as a proper subset.
504 citations
TL;DR: In this article, the authors show that if the zone of tension saturation extends to ground surface, then the addition of a very small amount of water can result in an immediate and large rise in the water table.
416 citations
TL;DR: In this paper, some novel circuit techniques for realizing linear CMOS tranconductance elements are proposed, which have superior linearity and input voltage range compared with the conventional source-coupled differential pair.
Abstract: Some novel circuit techniques for realizing linear CMOS tranconductance elements are proposed. The circuits discussed have superior linearity and input voltage range compared with the conventional source-coupled differential pair. Design tradeoffs are examined and computer simulation results are used to verify theoretical predictions. The results show close agreement between predicted behavior and simulated performance.
343 citations
TL;DR: In contrast to the shallow groundwaters, the isotopic and chemical compositions of the deep, saline waters and brines are determined by extensive, low-temperature rock-water interactions as mentioned in this paper.
332 citations
TL;DR: Results of reaction time, movement time, and kinematic trajectory analyses question the conclusions of Kelso, Southard and Goodman (1979) regarding the synchronicity of movement of the two limbs.
Abstract: Three experiments were designed to investigate the underlying processes in bimanual control. With one hand alone, or with both simultaneously, subjects moved styli from the midline of the body to l...
326 citations
TL;DR: In this paper, the theory of Sarason is applied to the determination of the optimal weighted sensitivity function and an upper bound on its norm, and the problem of achieving small sensitivity over a specified frequency band is studied.
Abstract: This paper deals with the design of feedback controllers which minimize the H^{\infty} -norm of the sensitivity function, suitably weighted. This approach to the theory of feedback design was introduced by Zames [1] and developed by Zames and Francis [2]. In this paper the theory of Sarason [3] is applied to the determination of the optimal weighted sensitivity function and an upper bound on its norm. The problem of achieving small sensitivity over a specified frequency band is studied, and the effect of nonminimum phase is elucidated. Finally, a method is introduced for handling plant poles and zeros on the imaginary axis.
306 citations
274 citations
TL;DR: In this article, a continuous atmospheric pressure flash pyrolysis process for the production of organic liquids from cellulosic biomass has been demonstrated at a scale of 1-3 kg/hr of dry feed.
Abstract: A continuous atmospheric pressure flash pyrolysis process for the production of organic liquids from cellulosic biomass has been demonstrated at a scale of 1–3 kg/hr of dry feed. Organic liquid yields as high as 65–70% of the dry feed can be obtained from hardwood waste material, and 45–50% from wheat straw. The fluidized sand bed pyrolysis reactor operates on a unique principle so that char does not accumulate in the bed and treatment of the sand is not necessary. The product gas, about 15% of the yield, has a medium heating value. The liquid product is an acidic fluid, which pours easily and appears to be stable. A preliminary economic analysis suggests that if the pyrolysis oil can be used directly as a fuel, its production cost from wood waste is probably competitive with conventional fuel oil at the present time.
TL;DR: In this article, a graph metric is defined that provides a measure of the distance between unstable multivariable plants, and the graph metric induces a "graph topology" on unstable plants, which is the weakest possible topology in which feedback stability is robust.
Abstract: In this paper, a "graph metric" is defined that provides a measure of the distance between unstable multivariable plants. The graph metric induces a "graph topology" on unstable plants, which is the weakest possible topology in which feedback stability is robust. Using the graph metric, it is possible to derive estimates for the robustness of feedback stability without assuming that the perturbed and unperturbed plants have the same number of RHP poles. If the perturbed and unperturbed systems have the same RHP poles, then it is possible to obtain necessary and sufficient conditions for robustness with respect to a given class of perturbations. As an application of these results, the design of stabilizing controllers for unstable singularly perturbed systems is studied. Finally, the relationship of the graph metric to the "gap metric" introduced by Zames and El-Sakkary is studied in detail. In particular, it is shown that the robustness results of Zames and El-Sakkary do not enable one to conclude the causality, of the perturbed system, whereas the present results do.
TL;DR: Polynomial algorithms to locate minimum weight dominating sets and independent dominating sets in strongly chordal graphs and to efficiently solve certain optimization problems for totally balanced matrices are presented.
TL;DR: In this article, the Hartree-Fock wave function was used to approximate the tetraexcited contribution in the form suggested by the unrestricted Hartree Fock type wave function, or one of its projected versions, such as the alternant molecular orbit method.
Abstract: In nondegenerate systems, the tetraexcited clusters are well approximated by products of disconnected pair clusters and the connected quadruply excited component is negligible. In contrast, when the reference state becomes quasidegenerate with the lowest biexcited configuration(s), the connected quadruply excited clusters become very important. To extend the applicability of the coupled-pair many-electron theory to such situations, we approximate the connected tetraexcited contribution in the form suggested by the unrestricted Hartree-Fock-type wave function, or one of its projected versions, such as the alternant molecular-orbital method. We show that the incorporation of the connected quadruply excited clusters into the coupled-pair equations effectively cancels certain nonlinear terms, originating from disconnected quadruple excitations, so that the resulting equations are very similar (up to a numerical factor) to the approximate coupled-pair theory, in which only those nonlinear terms which factorize with respect to the hole-electron pairs are considered. This fact shows in turn why various approximate coupled-pair approaches can often provide better results than the full coupled-pair many-electron theory.
TL;DR: The time courses of the various changes which are similar to those in chronic nerve stimulation experiments, indicate that various functional systems of the muscle fibre do not change simultaneously.
Abstract: Effects of a long-term, high intensity training program upon histochemically assessed myofibrillar actomyosin ATPase, myosin composition, peptide pattern of sarcoplasmic reticulum (SR), and parvalbumin content were analysed in muscles from the same rats which were used in a previous study (Green et al. 1983). Following 15 weeks of extreme training, an increase in type I and type IIA fibres and a decrease in type IIB fibres occurred both in plantaris and extensor digitorum longus (EDL) muscles. In the deep portion of vastus lateralis (VLD), there was a pronounced increase from 10±5% to 27±11% in type I fibres. No type I fibres were detected in the superficial portion of vastus lateralis (VLS) both in control and trained animals. An increase in slow type myosin light chains accompanied the histochemically observed fibre type transition in VLD. Changes in the peptide pattern of SR occurred both in VLS and VLD and suggested a complete transition from type IIB to IIA in VLS and from type IIA to I in VLD. A complete type IIA to I transition in the VLD was also suggested by the failure to detect parvalbumin in this muscle after 15 weeks of training. Changes in parvalbumin content and SR tended to precede the transitions in the myosin light chains. Obviously, high intensity endurance training is capable of transforming specific characteristics of muscle fibres beyond the commonly observed changes in the enzyme activity pattern of energy metabolism. The time courses of the various changes which are similar to those in chronic nerve stimulation experiments, indicate that various functional systems of the muscle fibre do not change simultaneously.
TL;DR: The results indicate that metabolic measures alone are not sufficient to adequately assess tasks which evoke primarily local muscle demands as well as qualitative biomechanical analysis suggests that the EMG differences are primarily due to differences in the moments and forces arising from the angular and linear accelerations of the load and trunk.
Abstract: The effect of two different load placements (just below mid-back or just above shoulder level) on erector spinae EMG, trapezius EMG, and heart rate were investigated during load carriage. The EMG and heart rates were telemetered from 11 subjects while they walked on a smooth level surface at an average velocity of 5.6 km·h−1 carrying a load of 19.5 kg in a specially designed backpack. The average rectified EMG amplitude was calculated digitally for both load placements. The high load placement resulted in significantly higher levels of muscle activity than did the lower placement. Heart rate was not significantly different between the two placements. A qualitative biomechanical analysis suggests that the EMG differences are primarily due to differences in the moments and forces arising from the angular and linear accelerations of the load and trunk. The results indicate that metabolic measures alone are not sufficient to adequately assess tasks which evoke primarily local muscle demands.
TL;DR: In this article, a new interaction geometry for optical Ramsey fringes comprised of four traveling waves instead of the three usual standing waves is presented, which leads to an improved contrast, using the optothermal detection of the vibrational excitation of a supersonic beam illuminated by a waveguide.
Abstract: We present a new interaction geometry for optical Ramsey fringes comprised of four traveling waves instead of the three usual standing waves. First, we demonstrate experimentally that the new method leads to an improved contrast, using the optothermal detection of the vibrational excitation of ${\mathrm{SF}}_{6}$ in a supersonic beam illuminated by a waveguide ${\mathrm{CO}}_{2}$ laser. Second, we give a simple theoretical description of the method, using evolution matrices of spinors and pseudospin-vector representations of these spinors. Finally, we introduce strong-field density-matrix diagrams to discuss the differences between the various interaction geometries as well as between the Ramsey fringes and the usual stimulated photon echoes.
TL;DR: Mass balance considerations show that the amount and degree of alteration of bitumen is more than adequate to account for the reduced sulfur species (lead, zinc, and iron sulfides) deposited at Pine Point.
Abstract: Bitumen is a common associate of carbonate-hosted lead-zinc deposits. On the Pine Point lead-zinc property, Northwest Territories, Canada, there are two forms of bitumen. Unaltered bitumens have atomic hydrogen/carbon ratios of about 1.4, sulfur contents of about 7.8 percent, and sulfur isotope ratios (§34S) of approximately +4.6 per mil. Altered bitumens occur in proximity to sulfide ore bodies and white sparry dolomite. Their hydrogen/carbon ratios are about 1.02, the sulfur contents average 22 percent, and the §34S values are about +12.4 per mil. These data indicate that some bitumen has participated in the thermochemical reduction of sulfate to produce hydrogen sulfide required to precipitate the ores. Mass balance considerations show that the amount and degree of alteration of bitumen is more than adequate to account for the reduced sulfur species (lead, zinc, and iron sulfides) deposited at Pine Point. These reactions may provide an important means of generating the large volumes of sulfide necessary to precipitate ore bodies in carbonate rocks.
TL;DR: In this article, experimentale de quatre contacteurs a boucle externe, dont le rapport des sections du trop plein et du tube de montee se situe dans le domaine 0,11≤A d /A r ≤ 0,69 and de trois contacteur a tubes concentriques, cet.
Abstract: Etude experimentale de quatre contacteurs a boucle externe, dont le rapport des sections du trop plein et du tube de montee se situe dans le domaine 0,11≤A d /A r ≤0,69 et de trois contacteurs a tubes concentriques, ce rapport se situant dans la gamme 0,13≤A d /A r ≤0,56. Resultats concernant la vitesse du liquide dans la colonne de montee, le nombre de Bodenstein de la phase liquide et le temps de melange
Book•
01 Jul 1984TL;DR: This paper gave excellent and thorough treatment of major demographic aspects of British Caribbean slavery from abolition of slave trade to slave emancipation, drawing heavily on extensive date available from slave registration returns for various islands to provide comparative perspective of nature of slave life.
Abstract: This book is a reprint of work that originally appeared in 1984. It gives excellent and thorough treatment of major demographic aspects of British Caribbean slavery from abolition of slave trade to slave emancipation. Draws heavily on extensive date available from slave registration returns for various islands to provide comparative perspective of nature of slave life. It is essential for serious scholars of the region.
TL;DR: It is shown that f(n)-time one-way cellular automata are equivalent to f( n)-time trellis automata, the real-timeOne-way Cellular automata languages are closed under reversal, the 2n- time one- way cellular Automata are equivalents to real- time cellular automATA and the latter are strictly more powerful than the real -time one -way cellularAutomata.
Abstract: It is shown that f(n)-time one-way cellular automata are equivalent to f(n)-time trellis automata, the real-time one-way cellular automata languages are closed under reversal, the 2n-time one-way cellular automata are equivalent to real-time cellular automata and the latter are strictly more powerful than the real-time one-way cellular automata.
01 Jul 1984
TL;DR: Characterization of (2(q + 1) + 2, 2, t, q)-min-hyper in PG(t, q) (t 3, q 5) and its applications to error-correcting codes and the theory of rank metric is transposed.
Abstract: We transpose the theory of rank metric. Gabidulin codes (8) W. C. Huffman and V. Pless, Fundamentals of Error-Correcting Codes. Cambridge. Leech's construction is based on the binary Golay code of length. 24. Later on (13) V.Pless, An Introduction to the Theory of Error-Correcting Codes, Wi. Download full text in PDF Opens in a new window. R. Brualdi and V. Pless, On the length of codes with a given covering radius, Preprint. Introduction to the Theory of Functions of One VariableA. Characterization of (2(q + 1) + 2, 2, t, q)-min-hyper in PG(t, q) (t 3, q 5) and its applications to error-correcting codes. of Coding Theory. 5. 1.
TL;DR: It is demonstrated that lipoxygenase activity mediates the formation of superoxide anion, and support the contention that membrane senescence is attributable to a sequence of reactions in which lipasederived fatty acids are utilized by lip oxygengenase to generate O− 2 and hydroperoxides.
TL;DR: In this article, photoacoustic spectroscopy has been applied in the infrared region to the characterization of a number of heteropoly compounds which show interesting trends in activity and selectivity in the conversion of methanol to hydrocarbons.
TL;DR: The findings suggest that the females have a significantly lower overall capacity for aerobic oxidation and for anaerobic glycolysis than the males and the females has a greater capacity for beta-oxidation relative to the capacity of the citric acid cycle.
TL;DR: In this paper, a correlation has been observed between cation size, structural microporosity, and bulk secondary structure in monovalent cation effects on the bulk structure and surface properties of the A3PW 12O40 and A3PMo12O40 heteropoly systems.
TL;DR: Computational and theoretical aspects of a new heuristic for the multidimensional zero-one knapsack problem are studied and its computational efficiency is compared with two other well-known heuristics.
TL;DR: In this article, the behavior of a series of heteropoly compounds during temperature-programmed desorption (TPD) before and after exposure to pyridine has been examined and correlated with structural changes and variations in sorptive capacities of these materials.
TL;DR: This program automates the very labor-intensive and therefore time-heavy and expensive process of manually assembling and cataloging individual cards for use in a multi-player game.
TL;DR: In this paper, an economical method of solving the equations of motion for two and three dimensional problems using non-orthogonal boundary-fitted meshes is described, which is intended for flows in which compressibility effects do not dominate.
Abstract: For three-dimensional fluid flows in complex geometries, it is convenient to make predictions using a non-orthogonal boundary-fitted mesh. The present paper describes an economical method of solving the equations of motion for two and three dimensional problems using such meshes. The locations on the mesh at which the depenent variables are calculated, and the methods used to solve the equations, are key issues in the development of a successful algorithm; these are discussed in the present paper. Results obtained when the proposed method is applied to several problems are also described. The method is intended for flows in which compressibility effects do not dominate.