Decoking of fixed-bed catalytic reactors

A mathematical model for the description of the non-steady state process of decoking of a fixed bed catalytic reactor is presented. The relevant dimensionless groups are identified and their influence on the process discussed. Appropriate relationships are given for the estimation of the maximum temperature in the bed. Methods of monitoring the process and of controlling it in the case of unknown or variable coke contents are explained

Towards automated generation of scripted dialogue: some time-honoured strategies

The main aim of this paper is to introduce automated generation of scripted dialogue as a worthwhile topic of investigation. In particular the fact that scripted dialogue involves two layers of communication, i.e., uni-directional communication between the author and the audience of a scripted dialogue and bi-directional pretended communication between the characters featuring in the dialogue, is argued to raise some interesting issues. Our hope is that the combined study of the two layers will forge links between research in text generation and dialogue processing. The paper presents a first attempt at creating such links by studying three types of strategies for the automated generation of scripted dialogue. The strategies are derived from examples of human-authored and naturally occurring dialogue

Reference and the facilitation of search in spatial domains

This is a pre-final version of the article, whose official publication is expected in the winter of 2013-14.Peer reviewedPreprin

Vagueness as Cost Reduction : An Empirical Test

This work was funded in part by an EPSRC Platform Grant awarded to the NLG group at Aberdeen.Publisher PD

Production of Referring Expressions for an Unknown Audience : a Computational Model of Communal Common Ground

The research reported in this article is based on the Ph.D. project of Dr. RK, which was funded by the Scottish Informatics and Computer Science Alliance (SICSA). KvD acknowledges support from the EPSRC under the RefNet grant (EP/J019615/1).Peer reviewedPublisher PD

Vagueness in referring expressions of quantity: effects on the audience

NLG systems that generate natural language text from numerical input data must decide be- tween alternative surface linguistic forms for the natural language output. When using refer- ring expressions to identify numerical quantities, the system must decide between vague and crisp surface forms of the referring expression. Ideally, the system would be equipped with heuristics that it could use to make these decisions in the way that best suits the audience: however there is currrently little empirical data to draw on concerning the differential audience benefits of vague and crisp surface forms. In this paper we describe a series of experiments that investigate whether different surface forms affect the audience’s cognitive load in differ- ent ways. We estimate cognitive load by measuring the response latencies in a forced choice referent identification task in which we vary the surface form of the referring expression that constitutes the instruction in the task. We find that the pattern of audience responses across the series of experiments provides little support for the cost reduction hypothesis that vague surface forms should place fewer cogntive demands on the audience than crisp surface forms: instead the results support the view that referring expressions that contain numerals are more taxing for the audience than referring expressions that use natural language quantifiers, at least in the context of a forced choice referent identification task. We offer this work as an initial foray into the provision of heuristics to augment NLG systems with audience-sensitivity

The utility of vagueness: does it lie elsewhere?

Much of everyday language is vague, yet standard game-theoretic models do not find any utility of vagueness in cooperative situations. We report a novel experiment, the fourth in a series that aims to discern the utility of vagueness from the utility of other factors that come together with vagueness. We argue that the results support a view of vagueness where the benefits that vague terms exert are due to other influences that vagueness brings with it rather than to influences of vagueness itself

Lexical choice and conceptual perspective in the generation of plural referring expressions

A fundamental part of the process of referring to an entity is to categorise it (for instance, as the woman). Where multiple categorisations exist, this implicitly involves the adoption of a conceptual perspective. A challenge for the automatic Generation of Referring Expressions is to identify a set of referents coherently, adopting the same conceptual perspective. We describe and evaluate an algorithm to achieve this. The design of the algorithm is motivated by the results of psycholinguistic experiments.peer-reviewe

Generating under global constraints: the case of scripted dialogue

Recently, the view of Natural Language Generation (NLG) as a Constraint Satisfaction Problem (CSP) has seen something of a revival. The aim of this paper is to examine the issues that arise when nlg is viewed as a CSP, and to introduce a novel application of constraint-based NLG, namely the ScriptedDialogue. ScriptedDialogue shares a number of crucial features with discourse, which make it possible to control the global properties of a computer-generated dialogue in the same way as those of a generated discourse. We pay particular attention to the use of soft constraints for enforcing global properties of text and dialogue. Because there has been little research into the formal properties of soft constraints in relation to generation, we start out with a theoretical exploration. We argue that, when multiple constraints are involved, it is important to define properly what is being optimised before proposing specific algorithms, and we argue that such definitions are often lacking in csp-based nlg. We show that it can be difficult (and sometimes even impossible) to guarantee satisfaction of global constraints by following local strategies. Based on these difficulties, we propose a novel approach to the generation of discourse and dialogue which combines csp solving with revision. Scripted Dialogue is used to illustrate this approach, which is compared with alternatives such as monitoring and estimation