THE LOGIC OF AUTOMATA

Automata are the prime example of general systems over discrete spaces, and yet the theory of automata is fragmentary and it is not clear what makes a general structure an automaton. This paper investigates the logical foundations of automata relating it to the semantics of our notions of uncertainty, state and state-determined. A single framework is established for the conventional spectrum of automata: deterministic, probabilistic, fuzzy, and non-deterministic, which shows this set to be, in some sense, complete. Counter-examples are then developed to show that this spectrum alone is inadequate to describe the behaviour of certain forms of uncertain system. Finally a general formulation is developed based on the fundamental semantics of our notion of a state that shows that the logical Structure of an automaton must be at least a positive ordered semiring. The role of probability logic, its relationship to fuzzy logic, the rotes of topological models of automata, and the symmetry between inputs and outputs in hyperstate/hyperinput-determinedsystems are also discussed.     

Controller reduction via stable factorization and balancing

A controller reduction procedure based on a representation of a controller as a matrix function defined using stable proper transfer functions and employing a balancing technique is studied in this paper. For a certain right coprime factorization of an LQG designed controller K(s) = N(s)D^-1(s), we approximate using a balancing technique the pair [D(s), N(s)]^T by a low-order pair [D₁(s), N₁(s)]^T defining a factorization of the reduced-order controller K ₁(s) = N₁(s)D₁ ^-1(s). We show that reducing the controller order in this way is motivated in a natural way, which leads to the expectation of both good stability properties and good accuracy of approximation of closed-loop behaviour. This is also demonstrated in some examples.     

Requiem for a theory: the ‘ story grammar’ story

Abstract

Story grammar was a fairly hot topic in artificial intelligence (AI) from the mid-1970s to the early 1980s. Now, however, it has virtually disappeared as a research issue in AI. The process of science is one where theories are proposed, experiments are conducted, hypotheses are tested, theories are revised and, ultimately, theories are either accepted or rejected. The story grammar story is surveyed with a view towards describing what it was, and explaining what happened to it, from the perspective of the scientific process.     

Knowledge acquisition, modelling and inference through the World Wide Web

The development of knowledge-based systems involves the management of a diversity of knowledge sources, computing resources and system users, often distributed geographically. The knowledge acquisition, modelling and representation communities have developed a wide range of tools relevant to the development and management of large-scale knowledge-based systems, but the majority of these tools run on individual workstations and use specialist data formats making system integration and knowledge interchange very problematic. However, widespread access to the Internet has led to a new era of distributed client–server computing. In particular, the introduction of support forformson World Wide Web in late 1993 has provided an easily programmable, cross-platform graphic-user interface that has become widely used in innovative interactive systems. This article reports on the development of open architecture knowledge management tools operating through the web to support knowledge acquisition, representation and inference through semantic networks and repertory grids.     

THE LOGIC OF AUTOMATA

Automata are the prime example of general systems over discrete spaces, and yet the theory of automata is fragmentary and it is not clear what makes a general structure an automaton. This paper investigates the logical foundations of automata relating it to the semantics of our notions of uncertainty, state and state-determined. A single framework is established for the conventional spectrum of automata: deterministic, probabilistic, fuzzy, and non-deterministic, which shows this set to be, in some sense, complete. Counter-examples are then developed to show that this spectrum alone is inadequate to describe the behaviour of certain forms of uncertain system. Finally a general formulation is developed based on the fundamental semantics of our notion of a state that shows that the logical structure of an automaton must be at least a positive ordered semiring. The role of probability logic, its relationship to fuzzy logic, the roles of topological models of automata, and the symmetry between inputs and outputs in hyperstate/hyperinput-determined systems are also discussed.     

Structural controllability and matrix nets†

We establish structural controllability results for matrix pairs [A, B] where A = A ₀ + Σ μ _iA_i , B = B ₀ + σ μ _i, B_i , with the A_i , B_i , fixed, and the μ _i , free scalar parameters. The results characterize structural controllability in several ways, via tests involving the checking of the rank or the evaluation of the determinant of various constant matrices formed from the A_i , B_i . A number of the results used as intermediate results tests for a full rank property of matrix nets, i.e. tests that check if M = M₀+ Σμ_iM_i prescribed, μ _i variable, has full rank for almost all μ _i .     

Effects of Variety, Maturity and Processing on Pear Juice Quality and Protein Stability

?Anjou, Comice, and Bartlett pears were processed into clarified juices from hard green and soft ripened fruits. Processing trials with and without SO₂ were conducted. Effects of variety, maturity and processing on browning, turbidity, proteins, and stability were investigated. Browning increased with heat treatment, and was reduced by processing with SO₂. Total soluble protein content increased with fruit maturity and processing with SO₂. Protein fractions from a clarifying enzyme preparation (mainly arabinase and amylase) with MW in the range of 64,000–92,000 and containing glycoproteins were not removed by fining/clarification. They contributed to protein instability in the clarified pear juices, but could be removed by heat treatment (pasteurization) prior to final filtration and bottling. Our results indicate some enzymes added for clarification during processing may contribute to post-clarification haze and sediment formation.     

FACTORS AFFECTING THE ULTRAVIOLET INACTIVATION OF ESCHERICHIA COLI K12 IN APPLE JUICE AND A MODEL SYSTEM*

Ultraviolet (UV) light has been used successfully for years to sterilize water and was recently approved as an acceptable irradiation treatment for the processing of juice. Although there is considerable information on the efficacy of UV processing in the treatment of water, limited data are available on its efficacy in fluid food systems. The objectives of this work were to determine the effects of apple‐juice properties on the UV inactivation of Escherichia coli K12 and the interdependence of intensity and time on the efficacy of UV light. Results showed that absorbance (A) and suspended solids (SS) affected UV inactivation, while pH and dissolved solids did not. Concerning the interdependence of intensity and time, intensity levels can only be changed without sacrificing effectiveness at a limited range of intensity and dose levels. This means that the range of the intensity level of the actual UV reactor must be considered in process‐parameter determination.     

1,4-Dihydroxyanthraquinone-2-thioethers. Dyes for Synthetic-polymer Fibres

The synthesis of a series of 2-thioethers of 1,4-dihydroxyanthraquinone by various preparative routes is described. The colour, dyeing and fastness properties on synthetic-polymer fibres of these dyes is discussed in terms of the nature of the substituent in the thiol group. 2-(2-aminophenylthio)-l, 4-dihydroxyanthraquinone, which gave the new heterocycle 6,13-dihydroxyanthra-[2,3-b]benzo[d] thiophen-7,12-dione on Pschorr intramoleadar cyclization, was observed to undergo cyclization, during both its synthesis and its application to polyester fibres, to the blue coloured 7-hydroxy-14H-mphtho[2,3-a] pheno-thiazine-8,13-dione.