Volume 27 Issue 7 • July 1990

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Displaying Results 1 - 6 of 6
  • Looking over the horizon (HF radar)

    Publication Year: 1990, Page(s):36 - 39
    Cited by:  Papers (9)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (643 KB)

    The history of HF (over-the-horizon) radar and its basic principles are outlined. Advances in signal processing that have made HF radar an operational reality are reviewed. Working units that the US Navy and the US Air force have in place, as well as some units under construction are described. Nondefence applications of HF radar, most notably the interdiction of drug traffickers and the monitorin... View full abstract»

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  • Nuclear Waste: the challenge is global

    Publication Year: 1990, Page(s):18 - 24
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1024 KB)

    The difficulties in disposing of many millions of tons of nuclear waste, comprising radioactive elements with half-lives ranging from microseconds to eons, are discussed, stressing the global nature of the issue. The IAEA classification of nuclear waste into high, intermediate, and low-level forms is described. The classification is based on several factors, including the waste's source and temper... View full abstract»

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  • Telephone challenges: a plethora of services

    Publication Year: 1990, Page(s):25 - 28
    Cited by:  Papers (2)  |  Patents (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (443 KB)

    Technical advances and changes in the regulatory climate in US telephony since the court-ordered divestiture of AT&T Company in 1984 are examined in this second of a series of articles (for previous article, by G. Zorpette, see ibid., vol.27, no.5, p.28 (1990)). A set of services based on Custom Local Area Signaling Service (Class) technology, introduced in New Jersey in 1987, provides caller ... View full abstract»

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  • Silicon micromechanics: sensors and actuators on a chip

    Publication Year: 1990, Page(s):29 - 31
    Cited by:  Papers (32)  |  Patents (105)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (708 KB)

    The techniques used to fabricate micromechanical structures are described. Bulk micromachining is routinely used to fabricate microstructures with critical dimensions that are precisely determined by the crystal structure of the silicon wafer, by etch-stop layer thicknesses, or by the lithographic masking pattern. Silicon fusion bonding has been used to fabricate micro silicon pressure sensor chip... View full abstract»

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  • Toward more compatible human-computer interfaces

    Publication Year: 1990, Page(s):40 - 43
    Cited by:  Papers (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (457 KB)

    Some poorly understood aspects of human-computer interfaces are identified. The use of guided evolution, or interactive design, to guarantee design flexibility by intentionally leaving some system options open during the early stages is discussed. The importance of evaluating a product design as it is evolving and funneling the results constantly back into the design is stressed, and some methods ... View full abstract»

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  • Van de Graaff's generator

    Publication Year: 1990
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (94 KB)

    The development by Robert J. Van de Graaff of the generator that bears his name is recounted. A memorandum he produced in 1933 reveals his first major insight: he could accelerate ions and electrons to enormous energies by generating a high voltage in a vacuum. Actual experimental work had to wait until September 1929, when the new Ph.D. arrived at Princeton University in New Jersey to work under ... View full abstract»

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