Showing papers by "Concordia University published in 1977"

Swirl Flows in Combustion: A Review

Abstract: Consideration is given to the major features of the characterization of swirl flow combustion, with emphasis on application to practical combustors. Recent experimental work is surveyed first with special regard to the main effects of swirl on the performance, stability, and combustion intensity of flames in combustors. Since solution of the basic governing equations yields predictions that are realistic only if the physical processes are sufficiently well expressed in mathematical form and suitable computational methods of solution are employed, these details are discussed. The treatment is brief, since extensive reviews are available in the literature. It is possible to predict major features of these swirling flows and some solutions are exhibited. The achievements and current status of serial flow combustion are summarized.

The production and utility of recovered dislocation substructures

Abstract: The production of dislocation substructures by cold working and recovery, fatigue, creep and hot working are reviewed. The relationships of subgrain size and dislocation density to the causal parameters of strain, strain rate, strain amplitude, temperature, stress and time (as applicable) are presented for each process. The importance of dislocation mechanisms such as climb, cross-glide, annihilation and subboundary formation are explained. The relative capabilities and limitations of each mode of creation with respect to both external processing and internal mechanisms are explored. The effects of the metal's stacking fault energy, of solid solution and of particle dispersion on structure and behavior are presented. The properties of the different kinds of substructures for room temperature and creep service are examined. The need for modification of the Petch relationship between yield strength and subgrain size is explored. The thermal stability is shown to be an important factor for creep service. It is concluded that the most suitable modes of substructure preparation are either cold working and recovery or hot working both from the view point of fitting into current industrial practice and from that of dependable, useful service properties.

New algorithms for constrained minimax optimization

Abstract: A constrained minimax problem is converted to minimization of a sequence of unconstrained and continuously differentiable functions in a manner similar to Morrison's method for constrained optimization. One can thus apply any efficient gradient minimization technique to do the unconstrained minimization at each step of the sequence. Based on this approach, two algorithms are proposed, where the first one is simpler to program, and the second one is faster in general. To show the efficiency of the algorithms even for unconstrained problems, examples are taken to compare the two algorithms with recent methods in the literature. It is found that the second algorithm converges faster with respect to the other methods. Several constrained examples are also tried and the results are presented.

Fishery resource use in a subarctic Indian community

Abstract: Cree Indians of Fort George, James Bay, northern Canada, maintain a large and successful subsistence fishery. Methods used in the fishery, seasons and locations of catch, and yield levels were studied, together with the population biology of two sea-run Coregonus species, cisco and whitefish, that dominate the catch. The fishery was characterized by a high degree of order, social regulation of the fishing effort and the gillnet mesh size, and practices that were identified as adaptations to the subarctic ecosystem. Fishing methods used permit the Cree to control the magnitude of the harvest and the species and size composition of the catch. There is evidence that fishers can alter the scarcity-abundance patterns of the fish stocks, and have a biologically measurable effect on the populations.

Amoeboid movement as a correlated walk

Abstract: The movement of slime-mold amoebae under isotropic conditions in two dimensions is represented as a Correlated Walk with straight steps of variable length. The steps are correlated via the angle α turned through from step to step. The hypotheses and predictions of the model compare favourably with experimental data for Dictyostelium discoideum amoebae.

Hume's Political Science and the Classical Republican Tradition

Abstract: La science politique de Hume marque un point tournant dans l'histoire de la pensee politique. On pent mieux apprecier sa signification si on la considere comme une reponse structuree aux essais de construction d'une science politique fondee sur l'experience tentes par les theoriciens de la tradition republicaine classique. Sa discussion des formes de gouvernement, du regime mixte en Grande Bretagne, du role des legislateurs, de l'influence du gouvernement sur le comportement social, des sources de la puissance militaire, de la sagesse d'acquerir des colonies, des merites de la politique de la Grece et de Rome dans l'Antiquite, et en dernier lieu, sa conception d'une republique parfaite, tons ces themes font partie d'une reponse systematique aux oeuvres de Machiavel, Harrington, Bolingbroke et autres. La conception de Hume du gouvernement constitutionnel derive d'une application plus consistante du raisonnement experimental an domaine politique. Sa science politique offre done une nouvelle theorie du gouvernement republicain qui a eu une profonde influence sur les penseurs americains, notamment Hamilton et Madison. Ces derniers y trouverent une conception du politique qui pouvait etre appliquee aux grandes societes mercantiles.

Concurrent intracranial self-stimulation and amphetamine self-administration in rats.

Abstract: In a two-lever testing chamber, rats had concurrent access to intravenous amphetamine and brain stimulation reinforces. Responding for each reinforcer was generally increased above baseline rates taken when only one reinforcer was available. Amphetamine stereotypy was observed, but did not interfere with rapid lever-pressing for brain stimulation.

Digital-filter synthesis using concept of generalised-immittance convertor

Abstract: By using the concept of the generalised-immittance convertor, new 2nd-order digital-filter sections are developed. These are then used as building blocks in a cascade synthesis. The proposed synthesis yields lowpass, highpass and bandstop filters with improved inband signal/noise ratio relative to that in conventional cascade filters. In addition, it yields low-noise and economical digital equalisers.

A simple voltage controlled oscillator with grounded capacitors

Abstract: A simple voltage controlled oscillator circuit using capacitors, all of which are grounded, is presented. The circuit is thus attractive from the point of view of monolithic or hybrid IC fabrication. The frequency of oscillation can be varied over a wide range, with the amplitude of oscillation remaining relatively stable over the range. Experimental results are given that agree closely with the theoretical predictions.

Constrained Flow Past Cavitating Bluff Bodies

Abstract: An experimental program has been carried out to determine the effects of wall interference on the drag and vortex shedding characteristics of cavitating two-dimensional triangular prisms and circular cylinders. The former shapes were chosen to eliminate effects of Reynolds number in interpreting the results. Direct pressure measurements were made to estimate the drag force. The vortex shedding frequency of the cavitating bodies was recorded with the help of a pressure transducer. The gap velocity u1 and the jet contraction velocity uj are shown to be the proper velocity scales to form the drag coefficients and Strouhal numbers for the bluff shapes tested. The drag coefficient was found to increase due to wall interference effects when partial cavitation conditions prevailed. The trend of the drag coefficient data indicated that wall interference effects are relatively small at very low cavitation numbers (σ → σch ) which correspond to choking conditions. As choking conditions are reached, the vortex shedding from the cavitating source becomes intermittent and finally vortex shedding ceases.

Two-dimensional wave digital filters using doubly terminated two-variable LC-ladder configurations

Abstract: This paper proposes a method of obtaining a two-dimensional wave digital filter of the recursive type from a doubly terminated LC-ladder network in two variables by replacing each series or shunt arm element of the ladder by its equivalent digital two-port. A number of realizations of the wave digital two-ports, which are canonic in multipliers, have been obtained. An example of a circularly symmetric low-pass two-dimensional digital filter is considered using these realizations. The sensitivity of this filter with respect to the multiplier coefficient changes due to finite word length is compared with that of the direct realization. It is found that the wave digital filter appears to be a more desirable form of implementation than the conventional cascade form.

Approximation of two-variable filter specifications in analog domain

Abstract: This paper describes a technique for approximating 2-variable filter specifications in the continuous or analog domain. It is shown that the design of 2-variable filter functions using this approach reduces to the problem of identifying a suitable 2-variable reactance function g(s_1,s_2) and the realization of a stable single-variable transfer function T(s) . Then T(g(s_1,s_2)) is the desired 2-variable stable transfer function which is guaranteed to have at least one realization whenever T(s) and g(s_1,s_2) are realizable. Applications of the theory developed in this paper are presented in the design of lumped-distributed filters and 2-dimensional digital filters.

Frequency transformations for digital filters

Abstract: It is shown that the reactance transformation for an analog filter corresponds to an all-pass function transformation in the case of a digital filter. It is further shown how this result could be used to obtain in a simple way the spectral transformations for digital filters derived by Constantinides.

A new continuously tunable sinusoidal oscillator without external capacitors

Abstract: A new sinusoidal oscillator circuit using only operational amplifiers (OA's) and resistors, which is attractive for monolithic IC fabrication, is presented. The circuit can be made to oscillate by adjusting a resistor ratio, while its frequency can be controlled over a wide range by a grounded resistor, independent of condition of oscillation. Experimental results are given which agree with the theoretical analysis.

The Speed-Torque Transfer Function of Electric Drives

Abstract: A new method for calculation of speed-torque transfer functions is presented. It is applicable to any electrical machine described by a set of linear equations. By predicting the form of the transfer function as well as the nature of its zeroes, the method yields a considerable insight into speed-load interaction and can be used in the design of motor drives.

Variables influencing the posthypnotic persistence of an uncanceled hypnotic suggestion.

Abstract: A fundamental belief about hypnosis is that any suggestion that is administered to the hypnotized S should be clearly and unambiguously canceled during hypnosis. It is believed that if the hypnotist does not do this, the suggestions will persist posthypnotically, and in some cases will have quite profoundly disruptive effects upon the hypnotized person’s subsequent behavior posthypnosis. The basis for this belief is entirely anecdotal. Weitzenhoffer,’ for instance, administered a posthypnotic suggestion that the S would be unable to stand up at the end of hypnosis session until the hypnotist clapped his hands. Following hypnosis, the S was asked to stand up, and, as expected, was unable to. He was still unable to, however, when the hypnotist clapped his hands, and the experimenter (E ) became concerned that he had inadvertently triggered off a hysterical paralysis. The S was rehypnotized, and it transpired that as the E was canceling the suggestion, a power lawn mower outside the experimental room had drowned out his voice just as he was describing the hand-clap condition. The S remained unaware that the suggestion had been canceled, and it remained in force. Evans,2 likewise suggested amnesia to the number 6 to a group of Ss. He intended the amnesia to last for the duration of the session, but one S misunderstood the instruction to mean that the amnesia for the number 6 was to last until a later scheduled session. The S was a high school mathematics teacher, who proceeded to experience great teaching difficulty in the classroom during the interim. In another such i n ~ i d e n t , ~ Schultz placed a coin on the back of a S’s hand, and suggested the coin was red hot and would burn the hand without causing pain. There was no trace of a burn when the coin was lifted, but two weeks later the S reported that every morning since the session he had awakened with a painless blister on the very same spot on the back of his hand; the blister had proceeded to subside during the course of the day. Schultz then remembered that he had forgotten to cancel the suggestion, and proceeded to do so. From there on, the man’s daily blister ceased. There are at least 20 other examples like this known to the author, but they are all likewise anecdotal and may thus overestimate the incidence of the phenomenon. There may be many instances where the hypnotist fails to cancel the suggestion and the S suffers no posttrance sequalae. Such cases, by their very nature, would tend to go unreported. Only one report known to the present

Venture Capital Management: A Survey of Attitudes towards Selection Criteria1:

Abstract: In the literature, a number of factors such as high risk, high expected return, the lack of alternate traditional sources of capital and other non-financial factors (e.g., management) have been ide...

Metastable ion studies. VII—loss of water from the molecular ion of cyclopentanol

Abstract: Metastable peaks for the loss of water from the molecular ion of cyclopentanol and six 2H labelled analogues have been studied. The results, together with some thermochemical date and a detailed examination of metastable peak shapes, have allowed the identification of the two mechanisms for water loss, both of which take place from the α-cleaved molecular ion. Daughter ion structures are proposed.

Relation of paternal availability to problem solving and sex-role orientation in young boys

Abstract: -This study investigated the relation of the father's availability to his 4-yr.-old son's problem-solving ability and sex-role orientation. The subjects were middle-class boys and their parents; 16 boys had fathers who were more available and 14 boys had fathers whose availability was relatively low. Three problem-solving measures and a sex-role orientation test were administered to the sons. The boys with the more available fathers performed better than the boys with the less available fa;hers on one of the problem-solving measures. Correlations between paternal availability and all three problem-solving tests were positive and significant for the group whose fathers were more available. There was no significant difference between the groups in sex-role orientation. Parental availability was associated with other .measures which also related to children's scores. Data indicated that higher availability of the father is positively associated with the son's problem-solving ability, but that other factors, especially maternal ones, influence the relation.