Evaluation of test procedures for hydrogen environment embrittlement

Report presents discussion of three common and primary influences on embrittlement process. Application of theoretical considerations to design of test coupons and methods is illustrated for both internal and external hydrogen embrittlement. Acceptable designs and methods are indicated

A corrected formula for uncertainty in estimations of gestational age from fetal head circumference measurements

Numerous publications over recent years have proposed methods for estimation of gestational age (GA) from fetal measurements including biparietal diameter, head circumference, crown-rump length and others. The manuscript of Altman and Chitty1 presented statistical modelling of data from 663 fetuses to define charts and tables for pregnancy dating based upon such measures. The resulting outputs are tables of mean GA estimates based upon each measurement, each with a corresponding standard deviation that encompasses the uncertainty in the prediction. We here address an erroneous result in the appendix of this work, associated with the uncertainty in GA prediction based upon derived head circumference measurements

New Issues In The Study Of Infant Categorization: A Reply To Husaim And Cohen

Husaim and Cohen\u27s focus (Merrill-Palmer Quarterly, 1981, 27, 443–456) on the learning of ill-defined categories by infants is securely motivated. Still, some of the particular questions they pursue—namely, how many dimensions are used to form the categories and what is the salience hierarchy of the dimensions—are tricky and perhaps misleading. Underlying their design and analysis is the basic assumption that the dimensions or attributes of the stimulus as defined by the experimenter have psychological reality for the infants. This assumption is questioned. Infants may perceive different attributes in the stimulus or they may not articulate the stimulus into attributes at all

A film-rupture model of hydrogen-induced, slow crack growth in alpha-beta titanium

The appearance of the terrace like fracture morphology of gaseous hydrogen induced crack growth in acicular alpha-beta titanium alloys is discussed as a function of specimen configuration, magnitude of applied stress intensity, test temperature, and hydrogen pressure. Although the overall appearance of the terrace structure remained essentially unchanged, a distinguishable variation is found in the size of the individual terrace steps, and step size is found to be inversely dependent upon the rate of hydrogen induced slow crack growth. Additionally, this inverse relationship is independent of all the variables investigated. These observations are quantitatively discussed in terms of the formation and growth of a thin hydride film along the alpha-beta boundaries and a qualitative model for hydrogen induced slow crack growth is presented, based on the film-rupture model of stress corrosion cracking

DUAL PRICING - AN INDUSTRY RESPONSIBILITY?

Uses and supports the dual pricing concepts; but raises questions about its effectiveness and seeks other ways to provide the consumer with information to aid in buying decisions.Demand and Price Analysis,

A mathematical investigation of a heat transfer configuration

Solutions to heat transfer problems using Laplace transfor

Life science payloads planning study

Preferred approaches and procedures were defined for integrating the space shuttle life sciences payload from experiment solicitation through final data dissemination at mission completion. The payloads operations plan was refined and expended to include current information. The NASA-JSC facility accommodations were assessed, and modifications recommended to improve payload processing capability. Standard format worksheets were developed to permit rapid location of experiment requirements and a Spacelab mission handbook was developed to assist potential life sciences investigators at academic, industrial, health research, and NASA centers. Practical, cost effective methods were determined for accommodating various categories of live specimens during all mission phases

Located horizon variation study Final report, 20 May 1968 - 13 Jan. 1969

Meteorological data interpolation techniques for computing horizon radiance profiles evaluated for possible error introduction