Showing papers by "University of Newcastle published in 1975"

Output feedback stabilization and related problems-solution via decision methods

Abstract: Given an unstable finite-dimensional linear system, the output feedback problem is, first, to decide whether it is possible by memoryless linear feedback of the output to stabilize the system, and, second, to determine a stabilizing feedback law if such exists. This paper shows how this and a number of other linear system theory problems can be simply reformulated so as to allow application of known algorithms for solution of the existence question, with the construction problem being solved by some extension of these known algorithms. The first part of the output feedback problem is solvable with a finite number of rational operations, and the second with a finite number of polynomial factorizations. Other areas of application of the algorithm are described: Stability and positivity tests, low-order observer and controller design, and problems related to output feedback. Alternative computational procedures more or less divorced from the known algorithms are also proposed.

Timing Space and Spacing Time

Abstract: A plea is made for a chronosophical approach to the selection of dimensions of time which might be relevant to the description and explanation of urban processes. Following the definition of some basic terms and concepts which might be used in the future development of a notational schema, the paper considers some possibilities which are inherent in the idea of timing space. This is followed by similar consideration of the idea of spacing time. These themes are compounded in a simple example which suggests that fundamental ongoing processes in daily urban behaviour are usefully summarised by what we call the accordion effect. The final section proposes that new insights into the problem of evaluating the quality of life of urban residents are obtained when such an approach is taken.

The existence of Room squares

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.

Formal semantics of a class of high-level primitives for coordinating concurrent processes

Abstract: High level programs for generating systems of cooperating concurrent processes are classified according to syntactic criteria. Their semantic characterization by means of Petri Nets, a mathematical theory of system descriptions, induces a corresponding syntactic classification on the latter. This permits the transferal of intuitively important semantical results of Petri Net theory to their corresponding programs. As a consequence it becomes possible to determine a certain kind of semantic correctness of a programm merely by its syntactic classification. Alternate solutions to a well known synchronization problem are treated in this way.

Minimal order observers for estimating linear functions of a state vector

Abstract: This paper studies the necessary and sufficient conditions for a pth-order observer to observe linear functions of the states of a linear dynamical system. The conditions are a set of multivariable polynomial equations which must be satisfied for some variable set in order for a pth-ncder observer to exist. It is possible to test for the existence of such a variable set in a finite number of steps via decision methods and thereby to construct an observer with the aid of polynomial factorization. To minimize the computational effort, the necessary and sufficient conditions are expressed in terms of the minimum number of variables.

Twenty-step algorithm for determining the asymptotic number of trees of various speces

Abstract: The technique for finding for asymptotic number of unlabled trees of various sorts was developed by polya (1973) and perfected by Otter (1848). Modern presentations are available in the book of Harary and Palmer (1973; Chapter 9), and in the paper of Bender (to appear).

Dimensions of temperament in infant school children

Abstract: SUMMARY A Principal Component Analysis of 39 temperamental attributes on a random sample of 209 infant school children produced four meaningful components. These identified components make an important contribution to an understanding of temperamental organization. A brief questionnaire using the above data has been developed for measuring temperament in infant school children. There are 30 questions with appropriate probes which relate to four components (dimensions): (a) Withdrawal, poor adaptation, dependence, etc.; (b) High activity, intensity, distractibility, etc.; (c) Moodiness, sulkiness; (d) Irregularity. Tentative norms arc provided for the above dimensions.

A Kantian View of the City: A Factorial-Ecology Experiment in Space and Time:

Abstract: This paper reports on a factorial-ecology experiment using ‘space—time units’. City space is divided ten ways and time eight ways to produce a set of eighty space—time units. Data is artificially created for these eighty units covering twenty-two variables. From a factor analysis of this data set, seven factors are extracted and interpreted by using the input variables and the space—time framework.

Noniterative Automatic Equalization

Abstract: An equalizer based on the minimum mean-square error (MSE) criterion, but with direct solution of the resulting equations, is described. The direct solution is based on the algorithms devised by Levinson and Trench. With the availability of large-scale integration (LSI) bipolar computing elements, these algorithms are competitive with iterative procedures. A method is considered for the estimation of the required parameters, and for automatic adaption to a changing channel. It is shown that the delay can be adjusted to achieve minimum MSE with respect to that parameter. Simulations undertaken show the robust performance of the algorithm, and that the equalizer performance is not adversely affected by operation in decision-directed mode.

Laser Raman Spectroscopy and Its Application to the Study of Adsorbed Species

Abstract: Publisher Summary This chapter outlines some of the advantages of Raman Spectroscopy. The chapter discusses specific examples of the application of Raman spectroscopy to studying adsorbate—adsorbent interactions and explains the nature of the Raman effect. Though as yet in its infancy, the application of laser Raman spectroscopy to the study of the nature of adsorbed species appears certain to provide unusually detailed information on the structure of oxide surfaces, the adsorptive properties of natural and synthetic zeolites, the nature of adsorbate—adsorbent interaction, and the mechanism of surface reactions. The fact that substrates do not substantially interfere with the spectrum of the adsorbed molecule itself makes Raman spectroscopy the most valuable method for examining vibrations of adsorbed species.

A Gaussian sum approach to phase and frequency estimation

Abstract: In this paper, a theory of optimal nonlinear estimation from sampled data signals where the a posteriori probability densities are approximated by Gaussian sums is adapted for application to phase and frequency estimation in high noise. The nonlinear estimators (demodulators) require parallel processing of the received signal. In the limit as the number of parallel processors becomes infinite the FM demodulators become optimum in a minimum mean square error sense and the PM demodulators become optimum in some well defined sense. For the clearly suboptimal case of one processor, the demodulators can be readily simplified to the familiar phase-locked loop. On the other hand, for the intermediate case, significant extension of the phaselocked loop threshold is achieved where (say) six parallel processors are involved.

The dipole-dipole potential in statistical mechanics

Abstract: We study the interaction energy of a system of N particles with embedded point dipoles in a cube, this cube being duplicated indefinitely throughout space. We are able to evaluate exactly this energy for arbitrary positions and orientations of the N particles, to provide an effective hamiltonian suitable for the study of the statistical mechanics of dipolar systems by both rigorous methods and computer simulation techniques. We describe methods for the rapid numerical evaluation of the hamiltonian and how it may be employed for the tasks outlined above.

A nonlinear fixed-lag smoother for finite-state Markov processes

Abstract: The fixed-lag smoothing of random telegraph type signals is studied. The smoothers are derived by first obtaining fixed-point smoothing equations and then using a time discretization. Simulation results are described that verify the qualitative carry-over of known results for the linear-Gaussian problem: the greater the lag, the greater the improvement; beyond a certain lag, no further improvement is obtained by the increase of lag; and the higher the signal-to-noise ratio (SNR), the greater is the improvement over filtering obtained through the use of smoothing. Smoothing errors of one-half the corresponding filtering error are demonstrated.

Determination of the parameters and parameter variations of a 3-phase induction motor having a current-displacement rotor

Abstract: The paper describes a method of determining the parameters and parameter variations of a 3-phase cage induction motor having a current-displacement rotor. The method is based on the use of the Newton-Raphson procedure for the solution of two nonlinear equations in two unknowns, these being the rotor resistance and leakage reactance at any particular rotor frequency.

Influence of clay-solute interactions on aqueous copper ion levels

Abstract: The extent to which Cu (II) species are removed from aqueous solution by kaolinite clay suspensions has been shown to vary with solution pH, the nature of any ligands present, and the order of contact of the :species. The ability of kaolin type clays to sorb both anions and cations introduces some unexpected effects, and raises some interesting queries in regard to the release of Cu from clay soils and stream sediments.

On eigenvalues of complex matrices in a sector

Abstract: It is shown that the test to determine whether all eigenvalues of a complex matrix of order n lie in a certain sector can be replaced by an equivalent test to find whether all eigenvalues of a real matrix of order 4n lie in the left haft plane.

A zoned heat transfer model of a large tangentially fired pulverized coal boiler

Abstract: A mechanistic model of a tangentially-fired pulverised-fuel furnace of 900 MW thermal input is described, in which a zoned method of computation predicts the temperature distribution within the chamber and the heat absorbed by the water-tube walls. The cylindrical model, comprising 45 gas and 21 surface zones, approximates the furnace, which is rectangular in cross section. The flow pattern within the chamber is assumed but the treatment of coal combustion and the complexities of radiative inter-change are rigorous within the liminations of the method. A series of simulations to demonstrate the effect of variation in gas flow pattern, boiler load and ash content in the coal is presented. These show that variation in the specific surface of the ash has a dominating influence, whereas the effect of the flow pattern is smally by comparison. Measurements taken on the actual furnace provide a check on the validity of the model. Comparisons are generally good although temperature predicted close to the furnace walls at burner level are consistently low. Investigations to improve the comparisons, and the method in general, are recommended.

Comments on "Optimal inputs for system identification"

Abstract: The above paper has presented a number of methods for designing "optimal" inputs for system identification based on maximization of the trace of the information matrix. This approach leads to simple design algorithms. However caution must be exercised in interpreting the results as it will be shown in this note that the resulting inputs can, in many instances, give a singular information matrix, i.e, ambiguity in parameter estimates.

Maintaining recency despite a stimulus suffix.

Abstract: Two processes of information retrieval were considered in the context of the logogen model. The aim was to establish whether information about the final items of an auditory short-term memory list is held exclusively in precategorical acoustic storage at presentation or whether these items are automatically registered in a cognitive store as well. Error data for a final heterogeneous item in alphanumeric lists showed significantly better recall, despite the addition of a stimulus suffix. Although these results demonstrated that coding had proceeded further than a precategorical stage, which maintains only physical features, the possibility remained that the effect was due to a bias in focal attention and selective coding at list presentation. A second experiment increased the difficulty of the retrieval task, and effectively precluded the possibility of a bias in attention. The results confirmed the findings in the first experiment. It was concluded that information about the final item(s) is registered a...

On numerical ranges of operators on locally convex spaces

Abstract: Numerical range theory for linear operators on normed linear spaces and for elements of normed algebras is now firmly established and the main results of this study are conveniently presented by Bonsall and Duncan in (1971) and (1973). An extension of the spatial numerical range for a class of operators on locally convex spaces was outlined by Moore in (1969) and (1969a), and an extension of the algebra numerical range for elements of locally m-convex algebras was presented by Giles and Koehler (1973). It is our aim in this paper to contribute further to Moore's work by extending the concept of spatial numerical range to a wider class of operators on locally convex spaces.

On a frequency-domain condition in linear optimal control theory

Abstract: A simple frequency domain inequality is known to be necessary but not, in general, sufficient, for the existence of the infimum defined by a linear-quadratic optimal control problem This note shows that for a certain class of performance indices, the condition is also sufficient

The Theory of Optimal City-Sizes: Elementary Speculations about Analysis and Policy

Abstract: In Australia, as in other countries, the view has been widely accepted that our largest cities have developed beyond an optimal size, and that natural or market forces are incapable of bringing about an optimal pattern of national settlement . Accordingly, politicians have adopted policies to encourage the growth of smaller cities and to promote decentralisation . In doing so, they lack adequate guidance from economic analysis for as Harry Richardson (1972) has recently said, the economic literature on the optimality of city sizes and of patterns of national settlement is `littered with inconsistencies and confusion' . There seems little doubt that the classical concept of an optimal city size adds to the confusion and is not very relevant to the planning of an optimal pattern of national settlement . The classical view suggests an inherent optimal size for cities . As Lowdon Wingo points out, the classical view implies that `The best of all possible worlds would find urban

Seasonal and sexual variations in the responsiveness of rabbit hearts to prolactin.

Abstract: Rabbit hearts perfused by the Langendorff technique were studied. The addition of ovine prolactin (NIH-P-S-10) to the perfusate in a concentration of 50 µg/ml produced rapid increases in both the amplitude and rate of contraction in 33 adult male hearts studied in winter. Prepubertal male animals showed no response, and only 1 out of 12 adult females responded. Pretreatment for 10 days with 2.5 µg/day testosterone propionate led to minimal inotropic but not chronotropic responses in 2 out of 4 prepubertal males and 2 out of 4 adult females to prolactin. Clear responses to prolactin were seen in 5 adult males pretreated with reserpine. Propanolol consistently reversed both the inotropic and chronotropic actions of prolactin. The original experiments were performed in January and February. When tested in May, adult males failed to respond to prolactin and this situation persisted until October when responsiveness again appeared. The same prolactin preparation and procedures were used throughout indicating t...