Showing papers by "University of Waterloo published in 1975"
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01 Jan 1975TL;DR: In this article, the authors provide a broad range of fully worked-out examples for stress analysis in realistic settings, including physics of materials, theory of elasticity methods, and computer-oriented numerical methods.
Abstract: This exploration of stress analysis focuses on techniques for analysis in realistic settings. It provides coverage of mechanics of materials, theory of elasticity methods, and computer-oriented numerical methods-all supported with a broad range of fully worked-out examples.
919 citations
TL;DR: In this article, the problem of finding a linear inequality whose zero-one solutions are precisely the zeroone solutions of the corresponding linear inequalities was investigated in terms of graph theory and threshold logic.
Abstract: Given an m $\times$ n zero-one matrix $\underset\tilde\to A$ we ask whether there is a single linear inequality $\underset\tilde\to a \underset\tilde\to x \leq b$ whose zero-one solutions are precisely the zero-one solutions of $\underset\tilde\to A \underset\tilde\to x \leq e$. We develop an algorithm for answering this question in O(m$n^2$) steps and investigate other related problems. Our results may be interpreted in terms of graph theory and threshold logic.
468 citations
TL;DR: In this article, a diagrammatic approach to perturbation theory of fermion systems is presented, and the second and third-order excitation energy contributions are given in a simple way without the involvement of the Green function formalism.
Abstract: Publisher Summary The chapter discusses the time-independent diagrammatic approach to perturbation theory of fermion systems. The chapter explores the perturbation theory for a non-degenerate level. The formulas derived serves as a starting point for the subsequent consideration of the excitation and ionization energies. The advantages of the direct calculation of excitation energies, compared with the approach in which the total energies of the pertinent electronic states are calculated separately for each state and then the excitation energies are obtained by subtracting the appropriate state energies, are quite obvious. The Rayleigh-Schrodinger (RS) perturbation theory (PT) for the case of a non-degenerate level of some Hamiltonian operator is discussed. The chapter discusses that even the Rayleigh-Schrodinger perturbation expressions for the direct calculation of the excitation energies may be obtained in a rather simple way without the involvement of the Green function formalism. On the contrary, our simple approach using the ordinary perturbation theory for separate levels presents certain desirable features of the Green function formalism. The chapter explains the diagrammatic representation of Wick's theorem and resulting diagrams. General explicit formulas for the second- and third-order excitation energy contributions are given in the chapter.
420 citations
TL;DR: In this paper, a pure culture of Pseudoinonas putida was grown in both a batch and continuous culture using phenol as the limiting substrate, and the applicable kinetic constants were either measured (μM, KI) or estimated (KS) from the experimental data.
Abstract: A pure culture of Pseudoinonas putida was grown in both a batch and continuous culture using phenol as the limiting substrate. Of two substrate inhibition models examined, the Haldane function was found to statistically best describe the kinetics. The applicable kinetic constants were either measured (μM, KI) or estimated (KS) from the experimental data. Particularly in the continuous culture, wall growth was found to exert significant effects on the broth biomass concentration and phenol conversion, both of which decreased with increasing amounts of wall growth. These effects are opposite to those predicted by wall growth models and to experimental results of others using mixed culture (activated sludge) systems.
388 citations
05 May 1975
TL;DR: It is shown that primality is testable in time a polynomial in the length of the binary representation of a number, and a partial solution is given to the relationship between the complexity of computing the prime factorization of a numbers, computing the Euler phi function, and computing other related functions.
Abstract: The purpose of this paper is to present new upper bounds on the complexity of algorithms for testing the primality of a number. The first upper bound is 0(n1/7); it improves the previously best known bound of 0(n1/4) due to Pollard [11]. The second upper bound is dependent on the Extended Riemann Hypothesis (ERH): assuming ERH, we produce an algorithm which tests primality and runs in time 0((log n)4) steps. Thus we show that primality is testable in time a polynomial in the length of the binary representation of a number. Finally, we give a partial solution to the relationship between the complexity of computing the prime factorization of a number, computing the Euler phi function, and computing other related functions.
367 citations
TL;DR: In this paper, the authors focus on determining equations for the local and mean rate of laminar heat transfer, which are approximately valid for different geometries by use of these equations, several new correlations are obtained for various heat transfer problems, and the results compared with experiments.
Abstract: Publisher Summary The first part of the chapter focuses on determining equations for the local and mean rate of laminar heat transfer, which are approximately valid for different geometries By use of these equations, several new correlations are obtained for various laminar heat transfer problems, and the results compared with experiments The problems considered involve heat transfer (1) from a cylinder, (2) from a sphere, (3) between concentric cylinders, (4) between concentric and eccentric spheres, (5) between vertical plates, and (6) from a nonisothermal vertical plate Attention is then turned to turbulent free convection heat transfer where the heat transfer from inclined plates and between differentially heated plates is considered A method of solving problems involving both laminar and turbulent convection is then outlined The criterion developed for the regions of applicability of the laminar and turbulent equations is shown to accurately predict the experimentally determined onset of instability of the laminar flow for free convection from an isolated plate A recommendation is then made for correlating heat transfer results in a clearer and more convenient way
302 citations
TL;DR: Backtrack algorithms for listing certain kinds of subgraphs of a graph are described and analyzed and their applications are analyzed.
Abstract: Backtrack algorithms for listing certain kinds of subgraphs of a graph are described and analyzed. Included are algorithms for listing all spanning trees, all cycles, all simple cycles, or all of c...
276 citations
TL;DR: In this article, the authors examine the assumptions social observers have employed to understand the role of "justice" in human endeavors and find that the commitment to justice is a natural expression of the human potential.
Abstract: The articles in this issue enable one to examine the assumptions social observers have employed to understand the role which “justice” plays in human endeavors. Justice is seen by some as a by-product of the individual's attempt to maximize his outcomes and an ideological support for the exercise of power. Others consider that justice, in its various forms, is an expression of the various functional requirements of society. Finally, there are those who find that the commitment to justice is a natural expression of the human potential. All the contributors must deal directly, or indirectly, with two compelling observations. Justice is one of the most sacred and pervasive themes in social behavior. And yet, it can take dramatically different forms even within the same society.
245 citations
TL;DR: In this article, a simple but reliable method for the prediction of intermolecular potentials is presented and tested for the case of the lighter noble gases and some of their mixtures.
226 citations
TL;DR: A special class of prime implicants is described for regular functions and it is shown that for anyP in this class,F(P) consists of one facet of H, and this facet has 0–1 coefficients, and every nontrivial facet ofH with 0-1 coefficients is obtained from this class.
Abstract: The role of 0–1 programming problems having monotone or regular feasible sets was pointed out in [6]. The solution sets of covering and of knapsack problems are examples of monotone and of regular sets respectively. Some connections are established between prime implicants of a monotone or a regular Boolean functionβ on the one hand, and facets of the convex hullH of the zeros ofβ on the other. In particular (Corollary 2) a necessary and sufficient condition is given for a constraint of a covering problem to be a facet of the corresponding integer polyhedron. For any prime implicantP ofβ, a nonempty familyF(P) of facets ofH is constructed. Proposition 17 gives easy-to-determine sharp upper bounds for the coefficients of these facets whenβ is regular. A special class of prime implicants is described for regular functions and it is shown that for anyP in this class,F(P) consists of one facet ofH, and this facet has 0–1 coefficients. Every nontrivial facet ofH with 0–1 coefficients is obtained from this class.
206 citations
TL;DR: In this paper, the authors reported new experimental measurements on the natural convective heat transport through a horizontal layer of air, covering the Rayleigh number range from subcritical to 4 × 106.
TL;DR: In this article, an interpretative review of the literature on flow through porous media is presented, focusing on those aspects of flow and pore structure that deal with the relationship between flow and structure.
TL;DR: Two experiments show that changes in the leaf itself, brought about by microbial excretions and secretions, or by a hydrolytic agent (hot HCl), can also increase its palatability to the detritus-feeding amphipod Gammarus pseudolimnaeus.
Abstract: Many detritus-feeders prefer dead leaves which are colonized by microorganisms-i.e. conditioned leaves, over freshly fallen or sterile leaves. Traditionally, this has been attributed to the build-up of microbial cells on the substrate. Two experiments show that changes in the leaf itself, brought about by microbial excretions and secretions, or by a hydrolytic agent (hot HCl), can also increase its palatability to the detritus-feeding amphipod Gammarus pseudolimnaeus.
TL;DR: A simple but general parallel programming language is considered, and a program simulating an elementary airline reservation system is given, and several properties of the program are demonstrated using the technique.
TL;DR: In this article, radiocarbon dates suggest the low-water stage has an age of about 11,000 yr BP, and that Lake Algonquin drained 10,000-15,000 y. a.
TL;DR: A piece-wise compromising method of solution is presented, which conveniently groups generating units and uses successive approximations dynamic programming and the grouping criterion presented appears to be the cornerstone of the superior performance of the proposed method.
Abstract: Host currently used thermal-generator maintenance scheduling methods schedule each unit at a time, leading in many cases to a poor local optimum or to an unfeasible solution. Considering simultaneously all units in the scheduling process, a computationally impractical method results. In this paper a piece-wise compromising method of solution is presented, which conveniently groups generating units and uses successive approximations dynamic programming. The optimal maintenance scheduling problem is formulated by employing a suitable state-space representation; most common constraints used in practice are described and a multiple objective function is presented. The effectiveness of the optimizing method is illustrated by solving a problem with data obtained from a real system. The grouping criterion presented appears to be the cornerstone of the superior performance of the proposed method.
TL;DR: In this paper, the relationship between the particle size and the size of the cavity nucleated at the particle is discussed as is the frequency of cavities as a function of particle dimensions and interparticle spacing.
TL;DR: In this paper, the stability properties of numerical methods for functional differential equations, similar to A-stability for ordinary differential equations are considered, and definitions are proposed for categories of numerical stability.
Abstract: Stability properties of numerical methods for functional differential equations, similar to A-stability for ordinary differential equations, are considered. Definitions are proposed for categories of numerical stability. Some of the backward differentiation methods are shown to have these stability properties.
TL;DR: In this paper, the existence of one biogeographic conodontophorid province, largely restricted to equatorial regions and characterized by raised salinity and temperature, was recognized in North America, Australia and Siberia.
Abstract: Ordovician conodontophorid distribution, paleogeography, paleoclimate, and global tectonics strongly support the existence of one biogeographic conodontophorid province, largely restricted to equatorial regions and characterized by raised salinity and temperature. This Midcontinent Province is recognized in North America, Australia, and Siberia. The same data indicate that in other areas the North Atlantic Province represents a normal-marine, virtually cosmopolitan fauna. In both provinces, communities are recognized that show a lateral segregation, strongly indicating that the majority of Ordovician conodontophorids were benthic or nektobenthic. The only Ordovician pelagic forms we recognize are the simple cone genera that either lack, or have a simple, symmetry transition series. It appears possible to correlate certain evolutionary changes in the conodont apparatus with changes in preferred habitat.
TL;DR: It is proved that there is a function h(k) such that every undirected graph G admits an orientation H with the following property: if an edge uv belongs to a cycle of length k in G, then uv or vu belong to a directed cycle oflength at most h( k) in H.
TL;DR: Linear codes over the ring of integers modulo q = pr, p a prime, are considered and natural analogs to Hamming, Reed—Solomon, and BCH codes over finite fields are defined and their properties investigated.
Abstract: Linear codes over the ring of integers modulo q = pr, p a prime, are considered. Natural analogs to Hamming, Reed—Solomon, and BCH codes over finite fields are defined and their properties investigated. Some ring theoretic problems encountered are discussed.
TL;DR: In this article, the authors give a condensed proof of the existence of room squares for positive odd sides except 3 and 5, and some areas of current research on room squares are also discussed.
Abstract: The authors give a condensed proof of the existence of Room squares for positive odd sides except 3 and 5. Some areas of current research on Room squares are also discussed.
TL;DR: The authors have observed the similarity between terminal graphs and three-dimensional vectors and have used it to develop the “vector-network model” which forms the bridge between vector methods and graph techniques.
TL;DR: In this article, a numerical inversion of the Laplace transform is used to calculate the frequency domain function at pre-assigned complex points and form a weighted sum, which is then used for the integration of differential equations.
Abstract: A new method for the calculation of time responses of lumped time invariant networks is presented. It is based on the numerical inversion of the Laplace transform and involves the computation of the frequency domain function at pre-assigned complex points and forming a weighted sum. The method exactly inverts a certain number of terms of the Taylor expansion of the time response and is thus equivalent to the methods used for the integration of differential equations. This equivalence is established on two examples. The order of integration can be changed between 1 and 46 without any difficulty. Additional properties resulting from the application of the numerical Laplace transform inversion are also discussed and some novel applications indicated.
TL;DR: It is suggested that young adults modify the complexity of their communications to different aged listeners in accordance with their expressed perceptions of the intellectual attributes of their auditors.
Abstract: Two experiments were conducted in order to discover (a) the expressed attitudes of young adults about the intellectual abilities of seven target groups ranging in age from infant to elderly, and (b) if and in what manner young adults differentially explain the rules of a simple game to these same target groups. In Experiment I, questionnaires requiring the attribution of intellectual capabilities of infants, preschoolers, preadolescents, adolescents, and young and middle-aged, and elderly adults were completed by 243 subjects. Intellectual ability was seen as increasing with age until old age. The elderly were consistently perceived as less competent than both young and middle-aged adults. The result of Experiment II, in which 60 subjects participated, suggested that young adults modify the complexity of their communications to different aged listeners in accordance with their expressed perceptions of the intellectual attributes of their auditors.
TL;DR: A pattern of results suggests that dichotic listening laterality, and possibly speech lateralization, are more influenced by environmental than by genetic factors.
TL;DR: In a series of four experiments, subjects were presented with eight item arrays tachistoscopically and were required to recall a digit presented among seven letters or a lette...
Abstract: In a series of four experiments, subjects were presented with eight item arrays tachistoscopically. In two tasks, the subject was required to recall a digit presented among seven letters or a lette...
TL;DR: The error analysis for computing the QR decomposition by Givens transformations was given originally by Wilkinson for n × n square matrices, and later by Gentleman for N × p (p ⩽ n ) tall thin matrices as mentioned in this paper.
TL;DR: An analytic model for predicting the subinterval distributions selected by classes of adaptive algorithms is developed, and the well-known algorithm SQUANK was reprogrammed to make it operate under the global criterion.
Abstract: A study has been made of two alternative subinterval selection strategies for adaptive quadrature. The more commonly used is termed a local acceptance criterion (as in SQUANK), and the other is termed a global acceptance criterion (as in AIND). An efficient programming technique for the global alternative is given, and an analytic model for predicting the subinterval distributions selected by classes of adaptive algorithms is developed. To test tile predictions of the model, the well-known algorithm SQUANK was reprogrammed to make it operate under the global criterion. Experiments with these routines were carried out comparing their actual performance with the predicted performance and with the performance of CADRE and AIND, and some conclusions are drawn.