Showing papers by "Concordia University published in 1975"

A new type of wave digital filter

Abstract: This paper proposes a new wave digital filter derived from doubly terminated LC-ladder networks by replacing each series or shunt arm element of the ladder by its equivalent digital two-port. It is shown that such two-ports may be cascaded without the use of adapters defined by Fettweis ( 1 ). A number of realizations of the wave digital two-ports, which are canonic with respect to both multipliers and delays, have been obtained. Also a realization which is canonic with respect to multipliers only is given and an example considered using this realization. The sensitivity of this filter with respect to the multiplier coefficient changes due to finite word length is compared with the conventional cascaded digital filter and also the one proposed by Renner and Gupta. It is found that the proposed filter appears to be a more desirable form of implementation than the conventional cascade form and comparable to that of Renner and Gupta ( 2 ).

Sum and product separabilities of multivariable functions and applications

Abstract: Necessary and sufficient conditions for reducibility of certain classes of multivariable polynomials are considered. The special case when a polynomial in that class can be factored into a finite product of single variable polynomials is investigated. A set of necessary and sufficient conditions for decomposing a multivariable p.r.f. into a sum of single variable p.r.f.'s is given. Examples to illustrate applications of sum and product separabilities of functions are given.

On the existence of optimal controls

Abstract: Using a recent result due to Berkovitz, we prove the existence of an optimal control in a broad class of problems, under relatively mild conditions.

Spaced, Massed, and Summary Treatments as Review Strategies for ITV Production.

Abstract: While media comparative effectiveness studies have adequately demonstrated that television is as effective as other media and conventional teaching in imparting information (Briggs et al., 1967; Chu & Schramm, 1967), relatively limited attention has been given to the differential examination of television production techniques and their effects on cognitive learning and attitude formation. The major problem with these earlier studies as Ives (1971, p. 152) points out is that "a difference of X between group averages provides very little information about the different instructional procedures which lead to this outcome, and, in the absence of any theoretical formulation the difference is frequently attributed to the better medium. The answer to the question, To what is the difference attributable? is simply: television." Schramm (1972, p. 45) underscores this point in noting, "In contrast to

A Markov Chain Model for Human Granulocyte Movement

Abstract: A continuous-time Markov chain is used to model the two dimensional movement of human granulocytes. The states of the Markov chain are the angles at which the cells move relative to a fixed axis. The method is used to determine the most probable direction of cell movement and to measure quantitatively any chemotactic or aggregative effect. The theory is applicable to any type of cell whose motion follows a zig-zag pattern.

The Discernible Educational Technologist

Abstract: Implementation of the vision of education permanente is bound to produce changes in the roles and working contexts of educational technologists. Current and probable role models can be discerned which not only serve to guide curriculum development for the preparation of educational technologists but also sensitise practitioners to emerging problems and possibilities. Five key but integrated functions are identified and described in detail: learning consultant; educational materials producer; manager of learning resources; educational systems developer; and educational planner. The discernible educational technologist will focus on the optimal allocation of human, material and fiscal resources to produce desired educational outcomes. He may do so by developing theories, systems, techniques or materials to contribute to personal and cultural development through education.

Simultaneous Transmission of Digital Phase-Shift Keying and of Analog Television Signals

Abstract: A method for transmission of a 1.544-Mbit/s data channel in a frequency band which is above the baseband of sound and vision signals of color television in FM microwave systems is described. The impact of the interfering video signal on phaseshift keyed (PSK) performance is evaluated. The probability of error as a function of the receiver carrier-to-noise ratio in the data channel for the case of Gaussian noise, sinusoidal interference, and various video test waveform (color bar, stair step, etc.) interference and combinations of these is measured. Analog and also novel digital methods of insertion of the television sound subcarrier signal are described. Data above video (DAVID) transmission measurement results which have been performed on an RCA 6-GHz microwave hop are presented.

PSK Combiners for Fading Microwave Channels

Abstract: The signal-to-noise (S/N) ratio of digital signals can be improved by using diversity transmission, followed by combining at the receive end, resulting in a lower probability of error P(e) . Second-order combining schemes for data signals are presented in this paper. The effect of delay difference in the two channels of a diversity system is analyzed, using four-phase coherent, phase-shift keying (PSK) as an example. For comparison with predicted performance, experimental results are included.

Topological Model for a Three-Phase Converter

Abstract: The purpose of this article is to develop an efficient model for the analysis of a three-phase converter. An algorithm for the generation of a modified proper tree and fundamental cutset matrix from a network graph is developed, which utilizes much less computer storage space and computation time compared to the classical methods. A three-phase rectifier bridge with its associated protective circuits is considered and the results obtained from the developed technique are discussed.

Conditions for a feedback transfer function matrix to be proper

Abstract: Given rational matrix \hat{G}(s) and a constant matrix K , necessary and sufficient conditions are given for the ration matrix \hat{H}(s) = \hat{G}(s) [I + K\hat{G}(s)]^{-1} to be proper.

Are there four ψ-particles?

Abstract: I t has been sugges t ed (1) t h a t the recent d i s covery of ~-part ie les (2) is a mani f e s ta t ion of the charm s y m m e t r y group S U t. W i t h i n the m i x e d 15 + 1 representa t ions of th i s group, ~ becomes assoc ia ted w i t h the J~)= 1meson none t of usua l S U 3 s y m m e t r y to form a tenfo ld J~ = l mul t ip l e t . I f so the sequence of three ~-part ic les should share some c o m m o n propert ies w i t h the corresponding observed none t mesons . In the SUI. l mode l (~) series of part ic les w i t h ident ica l spin, par i ty , s trangeness , ordinary and i so top ic spin are d i s t ingu i shed b y a s ingle a d d i t i v e q u a n t u m n u m b e r k. I t w i l l be a s sumed (4) tha t al l members of a t enfo ld J ~ 1m u l t i p l e t h a v e a c o m m o n v a l u e of k. In the m o d e l the mass of such a part ic le is g i v e n b y

Profile Characterization of Manufactured Surfaces Using Random Function Excursion Technique, Part 2: Application

Abstract: In Part 1 of this paper an analytical procedure based on the theory of random excursions was described to characterize the texture of a machined surface in terms of four new parameters In this part a number of experimental results are presented to justify the validity of the proposed surface parameters Surface measurements were carried out on ten differently machined surfaces using a specially equipped measuring device with a direct cable link to a hybrid computer The theoretically computed surface parameters compare favorably with the measurements made on the actual surface profiles that were recorded experimentally One of the advantages of the surface parameters presented in this paper is that they correspond directly to the mechanical properties of the machined component and hence can be used readily in specifications Further, the results of this paper show that i) the sampling length is essentially a high-pass filter with geometrically defined characteristics, and ii) the crest and valley excursion parameters are adaptable for both “on-line” and “off-line” surface evaluation The method presented is well-suited for application to computer-aided manufacturing without any special modifications Based on this investigation, a proposal for a mechanical stylus system for “online” surface measurements is also made

Can Conscience be Hypocritical? The Contrasting Analyses of Kant and Hegel

Abstract: Both Kant and Hegel focussed their attention on the problems of self-knowledge and self-scrutiny. Both elaborated a carefully considered view of conscience and sought to wrestle with the moral threat of self-deception. Both believed that a solution of the problems in this area was decisive for their understanding of the moral life and the task of ethics. In his analysis Hegel came to formulate what he considered to be decisive criticisms of Kant. The purpose of this paper is to examine the contrasting views of the two philosophers and provide a context in which the merits of each can be assessed.

Displacement of Serotonin from Its Adenosine Triphosphate Complex by Tricyclic Antidepressant Drugs in Vitro

Abstract: Serotonin forms a high molecular weight micellar complex with ATP, which is assumed to be the storage form of the neurotransmitter in nerve ending granules. Since bound serotonin (5-HT) does not show fluorescence, complex formation is accompanied by quenching of its fluorescence. Using a solution of a 5-HT-ATP complex at a 1:2 molar ratio containing 5 mM 5-HT, we observed fluorescence enhancement upon addition of tricyclic antidepressants in proportion to the amount and nature of the drug. The molar ratio of drug to 5-HT necessary to liberate 50% of bound serotonin was used to characterize the relative efficacy of the drugs in competing with 5-HT for ATP. The drugs also form water-insoluble complexes with ATP in a 2:1 molar ratio even in the presence of 5-HT. The solid complexes were characterized by infrared and NMR spectroscopy as well as by elemental analysis. The liberation of 5-HT from its "storage complex" in vitro suggests that an intraneuronal mode of action of antidepressant drugs is possible, in addition to their known inhibition of reuptake at the presynaptic neuronal membrane.

Wave Motion in Rockfill

Abstract: A mathematical model, coupling an external nonlinear wave and the resulting internal flow in a rockfill embankment with an impervious core is presented. The method of characteristics along with a f...

A tunable filter using amplifier pole

Abstract: A circuit consisting of two periodically operated switches, potentiometers, resistors, and compensated operational amplifiers, but not containing external capacitors, is proposed for the realization of a second-order bandpass and low-pass filter. The filter is electronically tunable and the natural frequency of the filter varies linearly with the width of the pulses controlling the FET switches.

Multiple Signal Analysis for the Delay-Lock Discriminator

Abstract: This correspondence deals with the effect of multiple signals on the control voltage of the delay-lock discriminator (tracker). Given n returned signals with known delay and power, a formula for the tracker estimate is derived. The analysis has specific application to low-altitude altimeters where the leak signal from the transmitter to the receiver may have delay comparable to the delay of the true signal.