High speed drives review: machines, converters and applications

The development of new power electronic device and high performance magnetic materials are the main technological factors that have led both industries and research community to focus their attention on high speed electrical drives. Several papers have already outlined the electrical machine and/or converter topology choice for certain high speed application. This choice depends on the applications under study. This paper aims to identify the most important high speed applications. For each of them, the main design challenges are highlighted and an overview of available market product is presented

Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

Low-thrust chemical propulsion system pump technology

Candidate pump and driver systems for low thrust cargo orbit transfer vehicle engines which deliver large space structures to geosynchronous equatorial orbit and beyond are evaluated. The pumps operate to 68 atmospheres (1000 psi) discharge pressure and flowrates suited to cryogenic engines using either LOX/methane or LOX/hydrogen propellants in thrust ranges from 445 to 8900 N (100 to 2000 lb F). Analysis of the various pumps and drivers indicate that the low specific speed requirement will make high fluid efficiencies difficult to achieve. As such, multiple stages are required. In addition, all pumps require inducer stages. The most attractive main pumps are the multistage centrifugal pumps

Advanced vehicle systems assessment. Volume 2: Subsystems assessment

Volume 2 (Subsystems Assessment) is part of a five-volume report entitled Advanced Vehicle Systems Assessment. Volume 2 presents the projected performance capabilities and cost characteristics of applicable subsystems, considering an additional decade of development. Subsystems of interest include energy storage and conversion devices as well as the necessary powertrain components and vehicle subsystems. Volume 2 also includes updated battery information based on the assessment of an independent battery review board (with the aid of subcontractor reports on advanced battery characteristics)

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Alternative Fuels for Transportation

Exploring how to counteract the world's energy insecurity and environmental pollution, this volume covers the production methods, properties, storage, engine tests, system modification, transportation and distribution, economics, safety aspects, applications, and material compatibility of alternative fuels. The esteemed editor highlights the importance of moving toward alternative fuels and the problems and environmental impact of depending on petroleum products. Each self-contained chapter focuses on a particular fuel source, including vegetable oils, biodiesel, methanol, ethanol, dimethyl ether, liquefied petroleum gas, natural gas, hydrogen, electric, fuel cells, and fuel from nonfood crops