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61.
62.
J. K. Li Hui Hong B. K. Middleton J. J. Miles 《Journal of magnetism and magnetic materials》1993,120(1-3):206-209
A recording system has been modelled which employs a peak detection scheme consisting of differentiator and cossover detector. The recording behaviours of head and tape combinations are included as variables and the effect of these on overall system error rates have been computed. 相似文献
63.
Traditional thermoelastic stress analysis (TSA) presupposes that the structure being analyzed is cyclically loaded at a constant amplitude and frequency. This approach typically has been used to satisfy the adiabatic reversible assumptions. The authors employ an alternative signal analysis technique that enables one to evaluate the magnitude of the individual components of stress in a component subjected to a loading that is random in both frequency and magnitude. However, the nature of the measured information does not change; i.e., data are inherently noisy, and edge information is unreliable. The latter two aspects have caused many thermoelastic stress analyses to be more qualitative than quantitative. The present paper emphasizes developing the TSA technique into a practical, noncontacting quantitative method for stress analyzing actual engineering structures that are randomly loaded. In particular, ability to determine the individual stresses thermoelastically under random loading is demonstrated. 相似文献
64.
J. T. Dickinson M. L. Klakken M. H. Miles L. C. Jensen 《Journal of Polymer Science.Polymer Physics》1985,23(11):2273-2293
When a notched polymeric material is stressed, the notch opens into a wide crack tip, exposing a region of high stress concentration. The consequences of electron bombardment of the tip of such a stressed material under vacuum are explored here for the first time. Evidence is presented for electron-induced crack growth at stress far below that needed for crack growth due to stress alone. The electron current densities used in these experiments are sufficiently small that thermal heating of the zone near the crack tip is minimal. To provide information on the phenomena involved, we present simultaneous measurements of electron current, gas pressure, and sample load in response to periodic bombardment of the sample. Experiments involving the bombardment of un-notched polymers under stress are also described. Fractography of the unique structures obtained by fracture due to the combination of electron bombardment and stress are presented and interpreted in terms of a crosslinking mechanism. 相似文献
65.
On the eigenvalue problem for fluid sloshing in a half-space 总被引:1,自引:0,他引:1
John W. Miles 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1972,23(6):861-869
Summary The boundary-value problem for free oscillations of a liquid in a half-space, which is bounded above by a rigid plane that contains a circular aperture, is transformed to a homogeneous, Fredholm integral equation for the velocity distribution in the aperture. Rayleigh-Ritz approximations to the eigenvalues are obtained by expanding the velocity distribution in appropriately weighted Jacobi polynomials. Numerical results demonstrate that the convergence of the approximations is much stronger than that of the approximations developed by Henrici, Troesch and Wuytack; for example, retaining twelve terms in the Rayleigh-Ritz expansion yields the dominant eigenvalue within one part in 10–8. A corresponding development is given for the two-dimensional problem, in which the aperture is an infinite strip.
Résumé Le problème aux conditions limites pour les oscillations libres d'un liquide dans l'espace semi-infini sous un plan rigide contenant une ouverture circulaire est transformé en une équation intégrale homogène de Fredholm pour la distribution de vitesse dans l'ouverture. On obtient des approximations de Rayleigh-Ritz pour les valeurs propres en développant le champ de vitesse en série pondérée de polynômes de Jacobi. Les résultats numériques démontrent que la convergence des approximations est bien plus rapide que celle des approximations développées par Henrici, Troesch and Wuytack; par exemple, en retenant douze termes dans le développement de Rayleigh-Ritz on obtient la valeur propre dominante avec une erreur relative moindre que 10–8. Un développement correspondant est donné pour le problème bidimensionnel, pour lequel l'ouverture est une bande infinie.相似文献
66.
Edward Miles 《Fiber and Integrated Optics》1991,10(4):323-350
The Small-Scale Integration (SSI) of fused couplers is proposed. The idea is to make several couplers on a single continuous piece of fiber rather than making discrete couplers and then splicing them together. Rudimentary tooling was set up to fabricate the couplers. Nine devices were successfully integrated onto a single fiber. In addition, a theory of fused tapers was developed. The fabrication parameters are analytically related to fiber geometry, which in turn, is related to the optical performance of the device. 相似文献
67.
John Miles 《Wave Motion》1996,23(4):387-391
Capillary-gravity waves induced by the lateral oscillation of a cylindrical container are considered on Hocking's hypothesis that the surface slope at the contact line is proportional to the vertical velocity. This problem has been considered by Shen, Sun and Hsieh on Evans's hypothesis that the surface slope at the contact line is prescribed and proportional to the excitation. The latter condition, in contrast to that of Hocking, leaves the normal modes and resonant frequencies unchanged from those of the classical problem (for which the surface slope vanishes at the contact line), and is conservative (whereas Hocking's condition implies dissipation). 相似文献
68.
69.
George W. Gokel Harold M. Gerdes David E. Miles John M. Hufnal Glenn A. Zerby 《Tetrahedron letters》1979,20(36):3375-3378
The title heterocycle is used as a carbonyl anion equivalent in the preparation of aldehydes and α-silyl ketones; the key step is the thermal demasking of the heterocycle by loss of isobutylene and sulfur dioxide. 相似文献
70.
The nucleation and growth of the crystalline core in the row structures of isotactic polystyrene were investigated by transmission electron microscopy. The number of core crystals, nucleated at a specific temperature, depends on the external strain. Their length was found to increase with time if the sample is kept at the straining temperature. If a strained sample is cooled to room temperature and subsequently reheated, no further growth of the core crystals is observed. Obstacles in the path of growth were circumvented by local changes of the growing direction. Melt-soluble noncrystallizable molecules are rejected by the growing core into the surrounding melt. The observations suggest a growth mechanism of the cores based on the successive self-induced alignment of molecules at the tip of the growing cores. 相似文献