Showing papers by "University of Waterloo published in 1974"

Exact and Invariant Second-Moment Code Format

Abstract: A fundamental analysis of the meaning of second-moment reliability in multivariate problems is presented. The format described is entirely derived from one basic assumption concerning the measurement of reliability. All formulations are exact, and approximations involving the assumption of small variance are only introduced to simplify practical equations. The format is fully invariant under any change of formulation of the failure criteria consistent with the laws of algebra and mechanics.

Second-order scalar-tensor field equations in a four-dimensional space

Abstract: Lagrange scalar densities which are concomitants of a pseudo-Riemannian metric-tensor, a scalar field and their derivatives of arbitrary order are considered. The most general second-order Euler-Lagrange tensors derivable from such a Lagrangian in a four-dimensional space are constructed, and it is shown that these Euler-Lagrange tensors may be obtained from a Lagrangian which is at most of second order in the derivatives of the field functions.

Review of load-flow calculation methods

Abstract: A survey is presented on the currently available numerical techniques for power-system load-flow calculation using the digital computer. The review deals with methods that have received widespread practical application, recent attractive developments, and other methods that have interesting or useful characteristics. The analytical bases, computational requirements, and comparative numerical performances of the methods are discussed. Attention is given to the problems and techniques of adjustments in load-flow solutions, and the suitabilities of various methods for modern applications such as security monitoring and optimal load flow are examined.

The occurrence of benthos deep in the substratum of a stream

Abstract: Summary 1 The vertical distribution of the benthic fauna of the Speed River, Ontario, was studied over a 13-month period from October 1970 to October 1971. Various physical and chemical parameters of this interstitial environment were also measured. 2 Several new techniques for sampling the interstitial environment of rivers wert devised. These methods and their relative efficiencies are considered. 3 The validity of the terms ‘hyporheal’ and ‘hyporheic’ are discussed and the term ‘hyporheos’ is offered to replace the former. 4 A brief resume of interstitial sampling methods is given with comments on their limitations for sampling deep heterogeneous substrates. 5 Chemical parameters are thought to be more important in the control and distribution ofthe fauna than physical parameters. 6 It is suggested that many larvae of stream-dwelling chironomids have over-wintering stages when they penetrate deep into the substrate to: (a) actively feed on the trapped organic detritus; (b) follow an optimum temperature for development. 7 It is suggested that the shape of an organism determines its success as a hypo-rheic form and examples are given. 8 The numbers of animals oecurring in the sub-benthic populations are shown to be very large indeed. For the Speed River, estimates of between 184,760 and 797,960 animals/m^ are made for different times of the year. Dry weight biomass is estimated o t vary between 30 9 g and 253-2 g/m^ throughout the year. 9 Sub-benthic or hyporheic populations are shown to exist in at least three other Canadian rivers. Some ofthe animals found are shown to be common to two or more of these rivers. 10 The inefficiencies of many conventional benthic samplers in sampling the total biomass of certain streams with hyporheic populations is discussed.

Sugar and Slavery: An Economic History of the British West Indies, 1623-1775

Abstract: Richard B Sheridan, Sugar and Slavery: An Economic History of the British West Indies, 1623-1775, Baltimore: Johns Hopkins University Press, 1974, xiv + 529 ppRichard B Sheridan's new and important book is best viewed as a harbinger of things to come It serves a pivotal function in summarizing the existing knowledge of, and pointing new directions for, the study of the colonial sugar industry and it does these things wellSheridan's own The Development of the Plantations to 1750: An Era of West Indian Prosperity, 1750-1775 (Barbados, 1970) treats both the British and the non-British West Indies in much the same fashion as the book under review here Carl and Roberta Bridenbaugh's No Peace beyond the Line: The English in the Caribbean, 1624-1690 (New York, 1972) covers the years after the founding of the English colonies in the literate, descriptive manner for which they are well known Richard S Dunn's Sugar and Slaves: The Rise of the Planter Class in the English West Indies, 1624-1713 (Chapel Hill, NC, 1972) is a model of research and analysis, remaining literate while going well beyond the descriptive; with it Dunn has made a significant contribution to the social history of the seventeenth century and created a point of contrast and comparison for the many studies of society in England and the continental colonies both already completed and still in progress Sheridan's new book supplements those of the Bridenbaughs and Dunn, as well as his own earlier work, and goes beyond them all into other times and other mattersSugar and Slavery is essentially a description of all aspects of the production and distribution of sugar within the British Empire from the earliest times to the American Revolution Sheridan touches on almost everything, beginning with the organization and settlement of the islands and continuing through detailed discussions of every aspect of his story to treatments of the imperial impact upon and the imperial implications of every feature of the sugar business He has assembled great quantities of information, organized them well, written up the whole adequately, and provided the reader with a compendium on the subject of the sugar industry of the British West Indies "It is the contention of this study that, however inhumane, the sugar industry made a notable contribution to the wealth and maritime supremacy of Great Britain" (p xii) Sugar and Slavery will not be easily surpassedShould anyone be interested in further work in the subject, Sheridan's book suggests what is yet to be done For instance, he has quite properly made much of the newer materials that he uncovered in his research His work began as a doctoral dissertation at the London School of Economics a quarter-century ago Since then Sheridan has visited archives in Great Britain, the United States and the Caribbean to find other sources Among those he has turned to especially good use are the records of individual plantations Much more can be done with just this type of source, and the recent or imminent publication of four guides will make the task easier The Guide to Manuscript Sources for the History of Latin America and the Caribbean in the British Isles (Oxford, 1973), edited by Peter Walne, mirrors for Great Britain Kenneth Ingram's Manuscripts Relating to Commonwealth Caribbean Countries in United States and Canadian Repositories (Barbados, 1974) Ingram, the librarian of the University of the West Indies at Mona, Jamaica, completed an even more massive survey devoted just to Jamaica as a 1970 thesis for the University of London; we can hope for its imminent publication since it will neatly complement Jerome S Handler's valuable Guide to Source Materials for the Study of Barbados History, 1627-1834 (Carbondale, 111, 1971) Studies of the organization and operation of individual sugar plantations based on collections of plantation records will provide us with the facility of testing and expanding Sheridan's own work …

A control system for coordinated inventory replenishment

Abstract: There are frequent occasions where the coordination of replenishment orders for selected groups of items can lead to significant savings in the costs of replenishment. This paper is concerned with a practical procedure for selecting the order-up-to-levels, can-order points and must-order points of a particular coordinated control system. Demand is Foisson and a fixed non-zero replenishment lead time is assumed. Cost comparisons with the best independent control strategy indicate that substantial savings (averaging 18-8% over some 104 examples) are possible through coordination.

Correlation effects in the low–lying excited states of the PPP models of alternant hydrocarbons. I. Qualitative rules for the effect of limited configuration interaction

Abstract: Simple rules for an estimate of the correlation effects in the low-lying states of alternant hydrocarbons, as described by the Pariser–Parr–Pople Hamiltonian, are formulated These rules are based on the alternancy and spin symmetry classification of states in both strongly and weakly correlated limits and on the valence bond characteristics of those states in the fully correlated limit It is shown that the largest effect of the electron correlation will be found for the singlet “minus” states (using Pariser's classification of the alternancy symmetry species), a smaller effect for the triplet “plus” states, and a much smaller effect for the remaining states These rules are exemplified by limited CI calculations including all monoexcited and all mono- and bi-excited configurations, respectively, for a number of π-electronic systems In view of these rules the success of the PPP model in the monoexcited CI approximation may be understood

Equilibrium theory of the planetary boundary layer with an inversion lid

Abstract: The maintenance of an elevated inversion in steady flow above a cold, rotating surface is shown to be possible for a certain range of the ‘buoyancy number’ bfV g, where b is the buoyant acceleration appropriate to the density deficiency of the fluid above the inversion, f is Coriolis parameter and V gis geostrophic velocity (so that fV gis also horizontal pressure gradient in kinematic units) The height of the inversion lid is determined by a balance of surface stress and buoyancy, in a way which may be deduced from laboratory experiments With the aid of such empirical evidence a theory is constructed for the layer below the inversion lid The cross-isobar angle of ground-level stress is found to increase with the buoyancy number, to a limiting value of 90‡, by which time the inversion descends to the ground Under typical conditions, a temperature difference of order 10‡C is necessary to eliminate the possibility of an equilibrium, elevated inversion lid and reduce ground level wind stress to a vanishingly small value

Nonlinear programming using minimax techniques

Abstract: A minimax approach to nonlinear programming is presented. The original nonlinear programming problem is formulated as an unconstrained minimax problem. Under reasonable restrictions, it is shown that a point satisfying the necessary conditions for a minimax optimum also satisfies the Kuhn-Tucker necessary conditions for the original problem. A leastpth type of objective function for minimization with extremely large values ofp is proposed to solve the problem. Several numerical examples compare the present approach with the well-known SUMT method of Fiacco and McCormick. In both cases, a recent minimization algorithm by Fletcher is used.

Till Stratigraphy in Parts of Southwestern Ontario

Abstract: Late Wisconsinan fluctuations of the Huron, Georgian Bay, Ontario, and Erie glacial lobes gave rise to a complex sequence of interfingering till sheets in the area between Stratford and Toronto, Ontario. Tills are the basis of establishing the stratigraphy of the area because of their distinctive and consistent characteristics. New names (Tavistock Till, Stratford Till, Stirton Till, Mornington Till, Elma Till, Maryhill Till, Pottery Road Formation) are proposed to replace previous informal names. The extent of Wentworth Till and Halton Till is revised. Subdivision of the Thorncliffe Formation into three members and dropping of the name Leaside Till are proposed. While a small area of older till is exposed between Woodstock and Waterloo, most tills are of Port Bruce Stadial age, and some are of Port Huron Stadial age. Probable Middle Wisconsinan interstadial deposits are now known from the interior of southwestern Ontario, as well as from previously described sites near Lake Erie and Toronto. Although over 16,600 sq km of mapping has been carried out in the region in the last 15 yr, only the deposits of the Erie and Ontario glacial lobes are relatively well known; sequences of Huron and Georgian Bay lobe deposits remain inadequately known or poorly understood.

On conservative elastic systems of the first and second kind

Abstract: In introducing the definition of a generalized kind of selfadjointness, it can be shown that there are truly nonconservative systems in the classical sense which in the light of a generalized concept are, however, conservative systems of the second kind. Systems like these buckle by divergence, do possess a generalized conservation theorem, and a generalized Rayleigh's quotient. Examples of such systems are given: the pinnedpinned rod, the rod with sliding ends, and the simply supported plate, all of them subjected to compressive follower forces. An example involving a complex differential equation is also treated: Greenhill's problem of the torsion of a pinned-pinned shaft.

Memory of a speaker's voice: reaction time to same- or different-voiced letters.

Abstract: Subjects were presented with a sequence of two letters, each letter spoken in either a male or female voice. On each trial, the subject was required to indicate, as quickly as possible, whether the two letters had the same name. Reaction times (RTs) were faster for letters spoken in the same voice for both “same” and “different” responses, even when letters were separated by 8 s. These results are incompatible with the notion of physical and name codes in auditory memory since a “different” response should always be based on a comparison of letter names and should not be influenced by voice quality. It was also found that RTs were not influenced by the phonemic distinctive feature similarity of the letters. Present address: University of Reading, Reading, England.

Further studies on the distribution of stream animals within the substratum1

Abstract: Samples collected with apparatus consisting of a series of pipes filled with gravel, driven into a streambed, and then opened for lateral colonization, confirm that invertebrates occur deep in the substratum: between 16 and 18 animals were found in each 600 ml from 13.5 cm down to at least 50 cm. Samplers buried in a trench dug into the true bank under the soil do not confirm studies suggesting that stream animals occur far from the water’s edge under the banks: only a few truly aquatic animals were found 50 cm into the bank, although some occurred as far as 2 m from the water. An earlier study demonstrated that stream invertebrates occur deep into the gravel in the bed of a stream (Coleman and Hynes 1970) and that sufficient numbcrs of them do so to cause grave rescrvations about the validity of most quantitative studies of the benthos of running water. Almost immediately doubts were cast on the results and it was suggested that they had been obtained because the so-called “pot” samplers had been filled with gravel dug from the stream ,and sunk into holes similarly dug out. This, the critics contended, had caused loosening of the gravel, washout of silt, and conditions generally favorable for colonization at depth. The same general criticism can be lcvclcd at two subsequent studies that also involved digging (Radford and IIartland-Rowe 1971; Bishop 1973), and which both showed that animals occur far down in the substratum. Indeed, Bishop’s study, made in a tropical stream and so perhaps fret of much scasonal perturbation, indicates that the criticism has some validity in that the numbers and biomass in all of four levels down to 40 cm bccamc smaller the longer his buried samplers were left in position. However, cvcn after 6 months thcrc were still apprcciablc numbers of animals down to 40 cm. Mundie ( 1971)) using an apparatus that did not involve colonization of gravel that had been moved, also rcportcd signifiL This work was supported by a grant from the National Research Council of Canada. cant numbers of animals down to a depth of 30 cm in a salmon stream in British Columbia. IIis apparatus, however, can bc used only in certain fixed situations. We thought of various ways of overcoming the drawbacks of our sampling system, and one of these was the freezing method dcscribcd by Stocker and Williams ( 1972). That, however, although an excellent way of obtaining undisturbed samples of sedimcnt, failed to capture animals bccausc they fled before the cold. Our next idea was to make samplers that could bc hammered in and opened and closed in situ; these devices, because they were rather impressive structures, came to bc known in our laboratory as “superpots.” Like the dinosaurs and other cumbersome monsters they have bccomc obsolete, but bccausc they did (mostly) what they wcrc dcsigncd to do they confirmed both our previous results and also some of the doubters’ doubts. Results obtained with them also confirm the validity of samples collected with our latest far less awkward sampler (Williams and IIynes 1974). We were also conccrncd that the Eindings of Schwocrbcl ( 1967)) that stream animals occur in numbers far from the water’s edge along the sides of streams, might indicate a further large source of error in current estimates of the biomass in lotic habitats. So, in conjunction with the superpot study, WC dug a trench into the bank and inscrtcd samplers somewhat like those of Schwocrbcl. LIMNOLOGY AND OCEANOGRAPI-IY 92 JANUARY 1974, V. L9( 1) Distribution of stream animals 93