By Topic

Proceedings of the IEEE

Issue 7 • Date Jul 1989

Filter Results

Displaying Results 1 - 9 of 9
  • Science and computing

    Publication Year: 1989 , Page(s): 1018 - 1019
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    The author contends that computers are unprecedented among human inventions in that they are a boon to experimenters and theorists alike. He points out that the power of computers has grown, and their cost has decreased, at a high-exponential rate-over the last 35 years; and the end is not in sight. In the last 33 years supercomputers, currently the most powerful computers, were needed to solve basic problems in a number of scientific fields. The author argues that novel uses of supercomputers need novel mathematics to make effective use of the computing power, underlining the importance of mathematics for science and of science from mathematics. He cautions that at the level of complexity of supercomputing it is not in general possible to get bounds for the errors due to discretizing the model View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Time-frequency distributions-a review

    Publication Year: 1989 , Page(s): 941 - 981
    Cited by:  Papers (893)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3452 KB)  

    A review and tutorial of the fundamental ideas and methods of joint time-frequency distributions is presented. The objective of the field is to describe how the spectral content of a signal changes in time and to develop the physical and mathematical ideas needed to understand what a time-varying spectrum is. The basic gal is to devise a distribution that represents the energy or intensity of a signal simultaneously in time and frequency. Although the basic notions have been developing steadily over the last 40 years, there have recently been significant advances. This review is intended to be understandable to the nonspecialist with emphasis on the diversity of concepts and motivations that have gone into the formation of the field View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Computational approaches to discovering semantics in molecular biology

    Publication Year: 1989 , Page(s): 1056 - 1060
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    One of the central problems of molecular biology stems from the discovery of the semantics of DNA. This discovery relies in a critical way on a variety of expensive computations. In order to solve these computations, both parallel computers and special-purpose hardware play a major role. The authors discuss the basic methodology involved in discovering the evolutionary structure of both DNA and proteins. Both fundamental issues and implementation issues are considered. The fundamental questions involve determining just how the sequences are to be compared. The implementation issues concern the vast amounts of computation required to execute the known algorithms View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Large-scale problems and supercomputing in the Department of Energy

    Publication Year: 1989 , Page(s): 1020 - 1037
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1900 KB)  

    Examples of important US Department of Energy (DOE) supercomputer applications are given, including energy systems design, weapons systems design, and basic research. Computational techniques used in these applications are discussed, along with results and outstanding problems. The DOE's approach to providing supercomputer resources to its researchers is outlined, including descriptions of the supercomputer resources available to various programs. In addition, the DOE research programs in parallel architectures, algorithms, and mathematical methods are discussed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Millimeter and submillimeter wavelength radioastronomy

    Publication Year: 1989 , Page(s): 993 - 1017
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2412 KB)  

    The significance of radio astronomy at millimeter and submillimeter wavelengths is described, and some of the more important results are given. The limitations imposed by the atmosphere are discussed, and the observation techniques used to overcome these limitations are outlined. The major new millimeter and submillimeter telescopes are described, and the techniques used to construct large-diameter, high-precision antennas are discussed. Methods of measuring the surface of a high-precision antenna are described with particular emphasis on microwave holography. The current state of the high-sensitivity receiving systems for these wavelengths is outlined with emphasis on recent work in superconducting devices and multibeam receivers. A brief description of astronomical millimeter-wave interferometers is given, and the recent progress made in the application of very-long-baseline interferometry techniques at millimeter wavelengths is described View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comments, with reply on `Continuous time relay-controlled model reference adaptive-system' by A. Abdulkareem and R. Nagarajam

    Publication Year: 1989
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (44 KB)  

    An adaptive scheme is shown by the authors of the above paper (ibid., vol.71, no.2, p.275-6, Feb. 1983) for continuous time model reference adaptive systems (MRAS), where relays replace the usual multipliers in the existing MRAS. The commenter shows an error in the analysis of the hyperstability of the scheme, such that the validity of this configuration becomes an open question View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Scientific computing challenges arising from space-borne observations

    Publication Year: 1989 , Page(s): 1061 - 1091
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4784 KB)  

    Five supercomputing problems are described: (1) determining the motions of the Earth's inner core boundary from outer-space measurements of the magnetic field; (2) simulating the global dynamics of the Earth's ocean currents, sea-ice cycles, land surface biology, and interannual atmospheric climates; (3) upper atmospheric chemistry; (4) modeling solar flare eruptions; and (5) the role of jet processes in the birth of stars. In addition, two examples indicating the growing importance of the use of supercomputers for scientific visualization are presented. The first deals with remote mapping from space of the Earth's topography or other planets. The second problem from astrophysics deals with mapping the cosmic background radiation in the presence of other astronomical signatures. A brief overview of interdisciplinary modeling plans under development for the next generation of supercomputers is given View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Subcompact hydrogen maser atomic clocks

    Publication Year: 1989 , Page(s): 982 - 992
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (972 KB)  

    Recent progress in compact hydrogen maser atomic frequency standards or clocks is reviewed. After a brief description of the principle of a hydrogen maser, the techniques used to realize high-performance compact hydrogen masers are discussed. Two approaches in compact hydrogen maser design are presented. The first approach uses active or atomic resonance sustained maser oscillation. The design uses cavity Q enhancement to overcome the intrinsic higher losses in a compact cavity. The versatility of the cavity design enables masers of various sizes to be realized. The complete package for the smallest oscillating compact maser measures 17.8×30.5×43.2 cm, weighs 19.5 kg, and has a measured stability of 4.14×10-14 for an averaging time τ=400 s, with a τ-1/2 dependence for τ<105 s. The second approach uses a passive maser. The design uses the atomic resonance as a narrow-bandpass amplifier. Using a dielectric loaded cavity, a package size of 26.7×66.0×45.5 cm with a weight of 30 kg and a stability of 1.0-3.0×10-12 τ-1/2, for 1<τ<105 s, has been attained. Compact masers of both designs have demonstrated frequency drift rates of 1×10-15 per day or less View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Supercomputer requirements for selected disciplines important to aerospace

    Publication Year: 1989 , Page(s): 1038 - 1055
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2020 KB)  

    Speed and memory requirements placed on supercomputers by five different disciplines important to aerospace are discussed and compared with the capabilities of various existing computers and those projected to be available before the end of this century. The disciplines chosen for consideration are turbulence physics, aerodynamics, aerothermodynamics, chemistry, and human vision modeling. Example results for problems illustrative of those currently being solved in each of the disciplines are presented and discussed. Limitations imposed on physical modeling and geometrical complexity by the need to obtain solutions in practical amounts of time are identified. Computational challenges for the future, for which either some or all of the current limitations are removed, are described. Meeting some of the challenges will require computer speeds in excess of exaflop/s (1018 flop/s) and memories in excess of petawords (1015 words) View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

The most highly-cited general interest journal in electrical engineering and computer science, the Proceedings is the best way to stay informed on an exemplary range of topics.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
H. Joel Trussell
North Carolina State University