Showing papers by "University of New Brunswick published in 1968"

Estimation of latent ability using a response pattern of graded scores

Abstract: Estimation of latent ability using the entire response pattern of free-response items is discussed, first in the general case and then in the case where the items are scored in a graded way, especially when the thinking process required for solving each item is assumed to be homogeneous. The maximum likelihood estimator, the Bayes modal estimator, and the Bayes estimator obtained by using the mean-square error multiplied by the density function of the latent variate as the loss function are taken as our estimators. Sufficient conditions for the existence of a unique maximum likelihood estimator and a unique Bayes modal estimator are formulated with respect to an individual item rather than with respect to a whole set of items, which are useful especially in the situation where we are free to choose optimal items for a particular examinee out of the item library in which a sufficient number of items are stored with reliable quality controls. Advantages of the present methods are investigated by comparing them with those which make use of conventional dichotomous items or test scores, theoretically as well as empirically, in terms of the amounts of information, the standard errors of estimators, and the mean-square errors of estimators. The utility of the Bayes modal estimator as a computational compromise for the Bayes estimator is also discussed and observed. The relationship between the formula for the item characteristic function and the philosophy of scoring is observed with respect to dichotomous items.

The effect of particle size distribution on packing density

Abstract: The packing density of a multi-particle system is found to increase if the particle size distribution is extended. Results are reported for Gaussian and log-normal size distributions using dense random packing of two sands with particle sizes of front <0.07 to 8.0 mm. Packing density is shown to be a function only of size distribution represented by a dimensionless standard deviation, and of particle shape. It is independent of particle size. Packing densities of binary mixtures of continuously distributed systems are found to depend upon the composition of the mixture, the mean-size ratio of the components of the binary, and upon the packing density of the individual components. Maxima occur at compositions of 55 to 75% larger component, and increasing mean-size ratios result in greater packing densities. The “increase in packing density” factor is a useful function for comparing, and setting limits to, packing densities of binary mixtures. The results should allow improved prediction and control of packing densities of many commonly encountered particle systems.

A New Method of Determining Loss Coefficients

Abstract: A new method is presented for finding B coefficients expressing loss in a power system as a function of power input. The computer program necessary to find these loss (B) coefficients is very simple, and transformations of variables are not required. The method takes advantage of the fact that partial derivatives of voltage phase angles with respect to any plant power output are independent of system generation schedules and load levels, as shown in a previous paper. Many of the usual assumptions in calculating B coefficients are eliminated.

Rotational analysis of the γ bands of SiF

Abstract: The rotational analysis of the 0-0, 1-1, 0-1 and 1-2 bands of the γ system of SiF has been completed. The upper state C is most probably 2Δ (case b). Derived constants for this state, in units of cm-1, are as follows: T00 = 39 537.45 (relative to × 2II1/2) ΔG1/2 = 878.38 B0 = 0.600 68 α = 0.005 39 A0 = 2.46.

Algorithms: Algorithm 322:F-distribution

Abstract: In t eg ra t ed in series, this gives results which appear to be correct to very nearly the full single precision accuracy of the machine (in terms of the number of digits after the decimal point, not necessarily significant digits). An approximation due to R. A. Fisher [1] gives results accurate to within ~ 3 X 10 -7 when maxn has been set at 30. The tradeoff on time is also optimal at about this point . The rea l p r o c e d u r e gauss computes the area under the lef t -hand portion of the normal curve. Algori thm 209 [6] may be used for this purpose. Thanks to the referee for many helpful suggestions, most of which have been incorporated, and to David F. Foster , who wrote an early version of par t of the program.

An Improved Method of Determining Incremental Loss Factors from Power System Admittances and Voltages

Abstract: A method is presented for reducing the many complicated calculations of partial derivatives involved in the exact expression for incremental loss factors (that is,) needed for economic load dispatching. Calculations of the partial derivatives of voltage phase angles with respect to plant power output, which comprise the major obstacle to use of the exact expression, are avoided by digital-computer simulation of the mode of operation implied by the partial derivatives. These partial derivatives are investigated and are shown to be independent of system generation schedules and load levels. Their values may be determinied for one particular set of operating conditions and used thereafter (with the partial derivatives of total power loss with respect to voltage phase angles) to determine the most economic schedule of generation. The method gives very accurate values for the incremental loss factors for a Voltage-controlled system. For a non-voltage-controlled system, the values appear to be as accurate as those determined by B coefficients calculated by the usual tensor method.

Response of multidimensional nonlinearities to inputs which are separable processes

Abstract: The property of separability of a process with respect to n random processes is defined and examples of such a process are given. The equivalent gains of a multidimensional nonlinearity (m.d.n.l.), obtained by Kazakov, are shown to constitute the best linear model of the m.d.n.l. in the Wiener sense if, and only if, each of the inputs is separable with respect to all the inputs. An extended version of Price's theorem is stated and proved, and its use in the determination of the output autocorrelation function for an m.d.n.l. is demonstrated. A series representation of the output autocorrelation function for an m.d.n.l. is also derived. The concepts of d.c. incremental gain and modified nonlinearity are extended to the multidimensional case, and their use in the analysis of closed-loop systems containing an m.d.n.l. is indicated. Finally, the applicability of these results to the general m.d.n.l. with n inputs and r outputs is demonstrated.

Social judgment approach to the investigation of french and english canadian attitudes

Abstract: The present study attempted to test the applicability of the social judgment approach to measuring attitudes and to predict, from responses to a latitude of acceptance-rejection scale, reactions to propaganda falling into various regions of the social judgment continuum.' It was expected that historical and current events in Canada involving French and English Canadians would make these two factions ideally suited for the purpose of the study. The social judgment approach assumes that "attitudes refer to the stands the individual upholds and cherishes. .."2 It also assumes that such stands are ordered along a "reference scale" made up of stands which the individual finds acceptable (his latitude of acceptance), stands which he finds objectionable (his latitude of rejection), and stands to which he is indifferent (his latitude of noncommitment). The totality of these three latitudes comprises the social judgment continuum. The social judgment continuum is measured by a latitude of acceptance-rejection scale.3 From the work reported by several investigators, it is readily apparent that a person's reaction to propaganda will be different depending upon whether propaganda falls within his latitude of acceptance, his latitude of noncommitment, or his latitude of rejection.4 Sherif and Jackman, for example, reported that subjects rated the truth value of a propaganda statement differently depending upon whether the statement was in accord with their existing attitudes or not.5 The study was conducted during the debate on the repeal of * Dr. Larimer was formerly an Assistant Professor of Psychology at the University of New Brunswick in Canada and is currently at the Laboratory for Psychosocial Studies, Pennsylvania State University, Middletown, Pennsylvania. 1 For an excellent review and clarification of the social judgment approach to

Notes on the siphonaptera of new brunswick

Abstract: A complete list of the 29 species of fleas known from New Brunswick is presented, including several species not previously recorded and one previously undescribed species. New records are listed, with host data, for most of the species.

Accelerometer Characteristics of a Drag-Cup Induction Machine

Abstract: The two-phase drag-cup induction machine is analyzed using a generalized machine model and the performance equations solved by digital computer. Methods of determining machine parameters are examined and a method for experimental determination of stator to rotor mutual inductance and rotor self-inductance is developed using a procedure based on the least mean squared error criterion. Fuller and Trickey's method is used for determination of the equivalent resistance of the drag-cup rotor. Computed accelerometer sensitivity values are experimentally verified for a particular machine. The effects of machine parameters upon the magnitude of accelerometer sensitivity and upon its variation with respect to speed are studied, and qualitative conclusions drawn regarding the most suitable parameter values for satisfactory accelerometer performance. The results should provide useful guidelines in selecting a suitable induction machine for use as an accelerometer and for the use of the designer in designing a machine to have specified accelerometer characteristics.

Dependence of the overtraining extinction effect on attention to runway cues.

Abstract: Six groups of rats were given 60 extinction trials in a runway following 30, 90 or 120 acquisition trials. For half the groups, a hurdle was interposed in the runway during both acquisition and extinction. For rats tested with the hurdle, the 30-trial group extinguished more readily than the other two groups. With the hurdle absent, overtrained rats extinguished more readily. This was interpreted as supporting the hypothesis that overtraining transfers control of responding from external to internal cues, and that internally controlled running is relatively more susceptible to extinction. Now at Dalhousie University, Halifax, Nova Scotia.

Partial avoidance of jump resonance in feedback systems

Abstract: For a specified maximum value of input amplitude, partial avoidance of jump resonance in the frequency response of certain non-linear feedback systems can be achieved by shaping the open-loop frequency response of the linear part of the system. The procedure is illustrated with an example of feedback amplifier circuit.

Prediction of jump resonance in systems containing certain multidimensional nonlinearities

Abstract: An expression is derived for the incremental describing function of a nonlinearity whose first-harmonic output has a phase shift with respect to the input. Its application in predicting jump resonance in feedback systems containing certain multidimensional nonlinearities is demonstrated by three typical examples.

Double-valued relays with random inputs

Abstract: The paper considers some theoretical methods which have been proposed for linearising double-valued relay nonlinearities with Gaussian inputs. Most methods depend on the description of the relay as a function of the input and its derivative, which will be referred to as the f(x,x?) model. It is shown, by comparing experimentally measured equivalent gains with theoretical gain expressions, that the f(x,x?) model is a poor approximation to an actual double-valued relay. Some qualitative and approximate theoretical results are derived for double-valued relays without resorting to the f(x,x?) model. These predict the following two effects, which are clearly seen in the experimental measurements, and which are not given by existing methods: (a) the equivalent gains depend on the input signal spectrum and (b) the imaginary part of the equivalent gain is very small. It almost always makes a negligible contribution to the overall equivalent gain.

Research in prosthetics in New Brunswick.

Abstract: Ce n'est qu'après la tragédie de la Thalidomide, qu'un effort poussé fut amorcé au Canada pour développer des méthodes de traitement plus efficace. Celles-ci ont pour but de développer des moyens artificiels, facilitant aux amputés l'activation de leurs prothèses. Présentement, quatre centres de recherche au Canada, travaillent sur le développement et l'amélioration des prothèses. Ceux-ci sont situés dans les villes de Winnipeg, Toronto, Montréal et Frédéricton. Voici un des trois projets du “Bio-Engineering Institute” établit à l'Université du Nouveau-Brunswick en 1965: “L'investigation et le développement des systèmes de contrôle myoélectrique”. Après plusieurs expériences, il semble que les amputés du membre supérieur dont le moyon est très court bénéficient davantage des prothèses à contrôle myoélectrique; étant donné que des contractions d'intensité différente d'un même muscle, produisent deux mouvements isolés (flexion et extension) de la prothèse. Les quatre étapes du programme d'ergothérapie sont: L'évaluation des patients afin de déterminer ceux qui bénéficient de prothèses à contrôle myo-électrique. La sélection et l'entraînement des muscles utilisés comme contrôle de la prothèse. L'entraînement fonctionnel avec prothèses après appareillage. L'évaluation du système de contrôle. Dans la sélection des points de contrôle, il y a deux facteurs à considérer: que le muscle soit superficiel et qu'il ait perdu sa fonction première qu'il puisse être utilisé isolément Il semble donc qu'un muscle produisant une contraction adéquate peut être utilisé comme point de contrôle.

Comment on “The frequency response and jump-resonance criteria of non-linear control systems”

Abstract: (1968). Comment on “The frequency response and jump-resonance criteria of non-linear control systems”. International Journal of Control: Vol. 8, No. 2, pp. 201-203.