Experimental measurements have shown that nondestructive magneto‐optic readout from magnetic filmcomputer elements by means of the longitudinal Kerr‐effect can operate at rates of at least one million bits per secon...
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Experimental measurements have shown that nondestructive magneto‐optic readout from magnetic filmcomputer elements by means of the longitudinal Kerr‐effect can operate at rates of at least one million bits per second. If the steady light source of the magneto‐optic apparatus is sufficiently bright, a signal‐to‐noise ratio of four or better can be obtained from the photomultiplier readout tube. Since the reversal time of thin ferromagneticfilms is less than a microsecond, writing speed can be as fast as readout. Information readout from a magnetic film can be obtained by scanning with a high‐intensity light spot. Spurious variations in surface reflectivity of the films are sufficiently small so that parts of the film magnetized in opposite directions can be clearly determined. Experiments with an electronic strobing magneto‐optic method make it possible to observe the details of the magnetization reversal process in very small parts of a film with a time resolution of the order of a nanosecond. Since this strobing process involves sampling and integration, the information bandwidth is too small to be used for digital computer readout. However, this method is useful in studying fine details of the magnetization reversal process. Measurements show that the reversal is repeatable in the different parts of the film.
Conventional magnetic technologies allow an extensive trade‐off, in computer storage systems, of total capacity, access time to data and price. In the area of ``mass'' memories significant improveme...
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Conventional magnetic technologies allow an extensive trade‐off, in computer storage systems, of total capacity, access time to data and price. In the area of ``mass'' memories significant improvements in capacity and access time are needed that cannot be obtained using inductive recording. That technology is limited by the dimensional factors that can be achieved mechanically and the frequency response of the transducer materials. The substitution of optical transducers relieves both of these limitations so that order‐of‐magnitude improvements are possible. This paper includes a discussion of the computer needs, the limitations of inductive recording and an illustration in a specific product configuration of the improvement possible by the substitution of a particular magneto‐optic approach.
A model of the peripheral auditory system, which relates the firing patterns of single auditory‐nerve fibers to acoustic stimuli, is discussed. Two aspects of the model's response to sinusoidal stimuli are c...
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A model of the peripheral auditory system, which relates the firing patterns of single auditory‐nerve fibers to acoustic stimuli, is discussed. Two aspects of the model's response to sinusoidal stimuli are compared with electrophysiological data obtained [N. Y.‐S. Kiang, personal communications (1961–1963)] from single auditory‐nerve fibers of the cat: (1) the equal response or “tuning” curves of individual fibers and (2) the sensitivity of a population of fibers as a function of frequency when each fiber responds to sinusoidal stimuli delivered at the “characteristic frequency” of the fiber. The model is composed of three elements: (1) a linear system intended to represent the outer, middle, and the mechanical part of the inner ear, (2) a nonlinear transducer intended to represent the sensory cells, and (3) a simplified representation of a nerve fiber that is probabilistic and contains a threshold and a refractory period. The model's responses to a variety of stimuli and its spontaneous activity were investigated with the aid of a digital computer (the TX‐2 computer of the Lincoln Laboratory MIT). [Supported in part by the U. S. Army, the U. S. Air Force Office of Scientific Research, and the U. S. Office of Naval Research; and in part by the National science Foundation (grant G‐16526); and the National Institutes of Health, U. S. Department of Health, Education, and Welfare (grant MH‐04737‐03).]
With the current emphasis on computers in science and engineering, it is felt that the undergraduate of such disciplines should be introduced to the applications of the computer as early in his educational program as ...
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With the current emphasis on computers in science and engineering, it is felt that the undergraduate of such disciplines should be introduced to the applications of the computer as early in his educational program as feasible. With this premise in mind, an IBM 1620 computer has been put to use in an undergraduate light and optics laboratory course, generally taken by sophomores and/or juniors. Several experiments that are performed in the laboratory, together with their respective computer programs, written for the 1620 in FORTAN II language, are presented.
The purposes of the experiments were (a) to evaluate the influence of a computer display on the ability of listeners to recognize complex sounds, (b) to determine what effect variations in audio signal‐to‐noise (S/N...
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The purposes of the experiments were (a) to evaluate the influence of a computer display on the ability of listeners to recognize complex sounds, (b) to determine what effect variations in audio signal‐to‐noise (S/N) ratio would have on combined performance, and (c) to discover the strategy used by the listener to combine the computer with audio evidence. Thirty‐three Naval Ratings were tested over twelvesessions. In the scored sessions, listening performance, computer performance, and listener‐plus‐computer performance (C & Li) were assessed. It was found: (1) that the computer display was effective in producing better recognition; (2) that the higher the S/N ratio, the greater C & Li performance; (3) that the lower the S/N ratio, the greater the utilization of the computer information; (4) that the utilization of the computer evidence did not improve with training; and (5) that a relatively simple additive model described the method by which the listeners combined the two sources of evidence.
A time‐dependent analysis of crossed‐field interaction has been formulated for computer calculation. The computer program has achieved, for the first time, accurate and complete simulation of the magnetron oscillato...
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A time‐dependent analysis of crossed‐field interaction has been formulated for computer calculation. The computer program has achieved, for the first time, accurate and complete simulation of the magnetron oscillator, magnetron amplifier, and smooth‐bore magnetron. We believe that crossed‐field interaction of the distributed‐emission type is finally predictable. The computer results are reliable enough to serve as design information. They also indicate that the nature of the interaction is turbulent in the sense that the operation of these devices borders between order and disorder under certain conditions.
A natural science course for nonscience majors used the digital computer in teaching classical mechanics. The advantages of using the computer in physics courses for both science and non-science majors are discussed.
A natural science course for nonscience majors used the digital computer in teaching classical mechanics. The advantages of using the computer in physics courses for both science and non-science majors are discussed.
New semi‐hard magnetic alloys, which have a square hysteresis loop and a low value of magnetostriction, are presented here. These alloys consist of about 90% Co, about 1% Be, and the balance Fe. We can attain a coerc...
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New semi‐hard magnetic alloys, which have a square hysteresis loop and a low value of magnetostriction, are presented here. These alloys consist of about 90% Co, about 1% Be, and the balance Fe. We can attain a coercive force between 10 and 30 Oe by controlling the Be content. The Co content affects the stress sensitivity of the hysteresis‐loop shape. One example is a tape 0.126 mm wide and 0.011 mm thick containing 88.5% Co, 1.3% Be, and 10.2% Fe, finally annealed at 800°C for 10 sec. This tape exhibits a coercive force of about 30 Oe, a squareness ratio of about 0.9, and very small change in the hysteresis‐loop shape with 20‐kg/mm2 tensile stress. In a sample containing more than 0.7% Be, CoBe precipitates and the grain size is much smaller than in a sample without Be. This fact contributes to the increase of coercive force with Be content. Moreover, the drawn wire has a 〈111〉 fiber texture, and the rolled‐flat tape has a {110} 〈111〉 texture. These textures do not change until at least 900°C annealing temperature, and the squareness ratio of the hysteresis loop along the wire or the tape axis remains high. One of these alloys is now used for information storage in a computermemory device named CTM (Composite Tape Memory).
This paper reviews the impact of digital computers on acoustics research since their introduction about a decade ago. The influential r?le that computers have attained in acoustics has resulted from their imaginative ...
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This paper reviews the impact of digital computers on acoustics research since their introduction about a decade ago. The influential r?le that computers have attained in acoustics has resulted from their imaginative use as research tools for analysis, control of experiments,modeling, and simulation—rather than from straightforward calculating applications. Illustrative examples discussed in this paper include modeling of the human speech‐production process and the mechanical and neural aspects of hearing, speech analysis and synthesis, automatic speech and speaker recognition, generation of musical sounds and psychoacoustic test stimuli, study of the perceptual correlates of acoustic stimuli, multidimensional scaling, simulation of ray propagation in the deep ocean and in reverberant enclosures, acoustic measurements in concert halls, digital modeling of auditorium designs. Monte Carlo simulation of wave propagation in multimode transmission media, and acoustic image reconstruction of unknown objects by “inverse diffraction” on the computer.
A system is described for the projection, digitizing, and recording of photographed spark chamber tracks. A Slo‐Syn‐driven projector automatically frames the film and projects the tracks on a screen mounted in a pre...
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A system is described for the projection, digitizing, and recording of photographed spark chamber tracks. A Slo‐Syn‐driven projector automatically frames the film and projects the tracks on a screen mounted in a precision commercial plotting board. A reticle projector, mounted on the plotting board pen holder, is manually positioned by means of the plotting board drive tapes which also drive the encoders of an accumulating digitizer system. A photoelectric gap counting device can be substituted as an alternate for one of these encoders. The all‐transistor digitizer system is equipped with manual switches for labeling of tracks, inserting frame numbers, etc., and has a versatile output format on seven hole paper tape. The paper tape with its track coordinate information is used as the input for computer programs designed to calculate the particle physics evidenced by the track.
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