Base heating methodology improvements, volume 1

This document is the final report for NASA MSFC Contract NAS8-38141. The contracted effort had the broad objective of improving the launch vehicles ascent base heating methodology to improve and simplify the determination of that environment for Advanced Launch System (ALS) concepts. It was pursued as an Advanced Development Plan (ADP) for the Joint DoD/NASA ALS program office with project management assigned to NASA/MSFC. The original study was to be completed in 26 months beginning Sep. 1989. Because of several program changes and emphasis on evolving launch vehicle concepts, the period of performance was extended to the current completion date of Nov. 1992. A computer code incorporating the methodology improvements into a quick prediction tool was developed and is operational for basic configuration and propulsion concepts. The code and its users guide are also provided as part of the contract documentation. Background information describing the specific objectives, limitations, and goals of the contract is summarized. A brief chronology of the ALS/NLS program history is also presented to provide the reader with an overview of the many variables influencing the development of the code over the past three years

Squibs and Discussions Aligning Phonetic Segments Articulation Assessment

for Children's In a recent paper published in this journal (Covington 1996), an algorithm is described which aligns segments within a pair of words for the purpose of identifying historical cognates. This algorithm could have a further application in the field of speech therapy, and in particular in the practice of articulation assessment of young children. The present author developed a similar algorithm some years ago for this purpose. In this paper, we explore some points of comparison between the two applications. 1. Articulation Testing It is well known that a child's acquisition of phonology is gradual, and can be charted according to the appearance of phonetic distinctions (e.g., stops vs. fricatives), the disappearance of childish mispronunciations, especially due to assimilation ([9o9] for dog), and the ability to articulate particular phonetic configurations (e.g., consonant clusters). Childhood speech impediments, often a symptom of other learning disor-ders, can often be diagnosed early on by the identification of delayed acquisition of these articulatory skills. Whether screening whole populations of children, or assessin

Similarity metrics for aligning children’s articulation data

This paper concerns the implementation and testing of similarity metrics for the alignment of phonetic segments in transcriptions of children's (mis)articulations with the adult model. This has an obvious application in the development of software to assist speech and language clinicians to assess clients and to plan therapy. This paper will give some of the background to this general problem, but will focus on the computational and linguistic aspect of the alignment problem. 1.1. Articulation testing It is well known that a child's acquisition of phonology is gradual, and can be charted according to the appearance of phonetic distinctions (e.g. stops vs. fricatives), the dis

Evaluation Metrics for a Translation Memory System

This paper concerns the methods of evaluation of a computational translator’s aid known as a Translation Memory (TM). A typical TM system selects candidate translations into a target language by obtaining matches to an input source-language sentence from a database comprising source–target pairs of previously translated sentences. We describe a metric for evaluating TMs and illustrate it with a case study based on a particular commercial TM system and a database of French–English sentence pairs specifically created from a previously translated text. This metric builds on definitions of the familiar parameters of precision and recall, and involves a measure of the ‘usefulness ’ to a translator of the selections made by the system. Several variations on these parameters and suggested weighting schemes are discussed in the search for a suitable metric, resulting in a ‘weighted precision ’ measure based on the number of keystrokes needed to correct the proposed text. In combination with appropriate measures of recall, parameters which could serve both as numerical optimisation criteria to be employed by the translator in seeking the most efficient use of a TM tool, and as means of carrying out quantitative evaluations of such systems ar