A study of mission duration extension problems Summary report, 1 Oct. 1966 - 1 Oct. 1967

Characteristics, constraints, and implications of long duration space missions based on use of available hardware and maintenance/repair actions in spac

Advances in lightning protection that satisfies contemporary standards

Described here are the LEC, Inc. Spline Ball Ionizer (trademark) (SBI) and the Spline Ball Terminal (trademark) (SBT) families and how their use in a conventional lightning protection system can achieve strike prevention in a conventional setting. A properly completed standards based system which is composed of the SBI and SBT in a hybrid system will provide two modes of lightning protection: (1) a stroke prevention mode that reduces the risk of a strike to the protected facility in proportion to the size of that facility and the size and number of SBI/SBT's used; and (2) a Stroke Collector-Diverter System that is far superior to any system now in use because it collects strokes entering the protected area from any direction and angle

A study of an Extended Lunar Orbital Rendezvous /ELOR/ mission. Volume 3 - Summary of results

Optimal system and mission planning for extended lunar orbital rendezvous missio

NDE: An effective approach to improved reliability and safety. A technology survey

Technical abstracts are presented for about 100 significant documents relating to nondestructive testing of aircraft structures or related structural testing and the reliability of the more commonly used evaluation methods. Particular attention is directed toward acoustic emission; liquid penetrant; magnetic particle; ultrasonics; eddy current; and radiography. The introduction of the report includes an overview of the state-of-the-art represented in the documents that have been abstracted

Fracture toughness testing data: A technology survey

Technical abstracts for about 90 significant documents relating to fracture toughness testing for various structural materials including information on plane strain and the developing areas of mixed mode and plane stress test conditions are presented. An overview of the state-of-the-art represented in the documents that have been abstracted is included. The abstracts in the report are mostly for publications in the period April 1962 through April 1974. The purpose of this report is to provide, in quick reference form, a dependable source for current information in the subject field

Register of experts for information on mechanics of structural failure

This register is comprised of a list of approximately 300 experts from approximately 90 organizations who have published results of theoretical and/or experimental research related to six problem areas in the mechanics of structural failure: (1) life prediction for structural materials, (2) fracture toughness testing, (3) fracture mechanics analysis; (4) hydrogen embrittlement; (5) protective coatings; and (6) composite materials. The criteria for the selection of names for the register are recent contributions to the literature, participation in or support of relevant research programs, and referral by peers. Each author included is listed by organizational affiliation, address, and principal field of expertise. The purpose of the register is to present, in easy reference form, sources for dependable information regarding failure modes and mechanisms of aerospace structures. The register includes two indexes; an alphabetical listing of the experts and an alphabetical listing of the organizations with whom they are affiliated

Life prediction of materials exposed to monotonic and cyclic loading: A new technology survey

Reviewed and evaluated technical abstracts for about 100 significant documents are reported relating primarily to life prediction for structural materials exposed to monotonic and cyclic loading, particularly in elevated temperature environments. The abstracts in the report are mostly for publications in the period April 1962 through April 1974. The purpose of this report is to provide, in quick reference form, a dependable source for current informatio

Simple bonding technique for high-temperature ceramic coatings

Coatings, consisting of zirconia powder bonded with orthophosphoric acid and a small amount of hydrofluoric acid, are hard, strong, and refractory, resist thermal shock, and provide good thermal protection. After the aqueous coating is applied to a metallic surface, only a 600 deg F cure is required before service

Missing data in randomised controlled trials: a practical guide

Objective: Missing data are ubiquitous in clinical trials, yet recent research suggests many statisticians and investigators appear uncertain how to handle them. The objective is to set out a principled approach for handling missing data in clinical trials, and provide examples and code to facilitate its adoption. Data sources: An asthma trial from GlaxoSmithKline, a asthma trial from AstraZeneca, and a dental pain trial from GlaxoSmithKline. Methods: Part I gives a non-technical review how missing data are typically handled in clinical trials, and the issues raised by missing data. When faced with missing data, we show no analysis can avoid making additional untestable assumptions. This leads to a proposal for a systematic, principled approach for handling missing data in clinical trials, which in turn informs a critique of current Committee of Proprietary Medicinal Products guidelines for missing data, together with many of the ad-hoc statistical methods currently employed. Part II shows how primary analyses in a range of settings can be carried out under the so-called missing at random assumption. This key assumption has a central role in underpinning the most important classes of primary analysis, such as those based on likelihood. However its validity cannot be assessed from the data under analysis, so in Part III, two main approaches are developed and illustrated for the assessment of the sensitivity of the primary analyses to this assumption. Results: The literature review revealed missing data are often ignored, or poorly handled in the analysis. Current guidelines, and frequently used ad-hoc statistical methods are shown to be flawed. A principled, yet practical, alternative approach is developed, which examples show leads inferences with greater validity. SAS code is given to facilitate its direct application. Conclusions: From the design stage onwards, a principled approach to handling missing data should be adopted. Such an approach follows well-defined and accepted statistical arguments, using models and assumptions that are transparent, and hence open to criticism and debate. This monograph outlines how this principled approach can be practically, and directly, applied to the majority of trials with longitudinal follow-up

Fracture toughness testing data. A bibliography

This bibliography is comprised of approximately 800 reference citations related to the mechanics of failure in aerospace structures. Most of the references are for documents that include fracture toughness testing data and its application or documents on the availability and usefulness of fracture mechanics analysis methodology. The bibliography represents a search of the literature published in the period April 1962 through April 1974 and is largely limited to documents published in the United States