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81.
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
82.
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
83.
84.
Abstract— Phytochrome control of nitrate reductase activity has been studied in cotyledons and hypocotyls of light-grown Sinapis alba. Under polychromatic irradiation, an increase in the fluence rate of far-red light added to a constant source of photosynthetically active radiation causes a decrease in the phytochrome photoequilibrium and, in the hypocotyl, this results in decreased nitrate reductase activity. However, in the cotyledons this difference is only observed transiently. In both organs, enzyme activity is correlated with the level of the far-red light absorbing form of phytochrome, Pfr . These correlations are not altered when the fluence rate (with respect to phytochrome) is increased, suggesting that the responses are not fluence rate dependent. The results obtained are consistent with the notion that in fully de-etiolated seedlings, Pft alone controls nitrate reductase activity. 相似文献
85.
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
86.
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
87.
88.
Gareth J. Brown Des S. Creasey Nick J. Miles 《Particle & Particle Systems Characterization》1996,13(4):260-263
The avalanching behaviour of two coal types was determined, one of good and the other of poor handleability characteristics. This revealed significant differences in the nature of flow of the coals. Analysis of the strange attractors of the weight series of avalanches enabled quanitification of this difference, and the establishment of practical, relative criteria for the measurement of coal handleability. These criteria will now enable a structured study of the variables that affect handleability, for example proportion of fines and moisture content, and industrial consumers of coal to specify minimum acceptable limits for its transport characteristics. 相似文献
89.
In the paper we give a method for calculating the tractions (local forces) of the fluid motion determined by an incoming plane pressure wave on an artificial hair cell transducer structure. The sensing element of the transducer is a standing high aspect ratio cilium in the shape of a narrow thin curved beam (tape-like), which can be easily fabricated in micro-/nanotechnology. The method is based on considering the system of partial differential equations describing the motion of the compressible viscous fluid in an acoustic linearized approximation, and representation of the velocity field as a viscous acoustic single-layer potential. The boundary conditions, stating the cancellation of the velocity components on the solid beam, yield a two-dimensional (2-D) system of three integral equations over the beam's surface for the traction components. In the case of a narrow cilium, the system of integral equations furnishes a system of two 1-D integral equations over the symmetry curve of the structure for obtaining the tangential and normal components of the traction. This system is solved numerically by a finite (boundary) element method. The numerical code written for solving the problem was applied to some particular structures. The last structure is similar to the trichobothrium of a spider Cupiennius salei. The results obtained show that the curvature of the hair is enhancing sensitivity to flows directed normal to the main shaft of the hair confirming the assertion of Barth et al. [Philos. Trans. R. Soc. London, Ser. B 340, 445-461 (1993)]. 相似文献
90.
We demonstrate a method for generating flow within a microfluidic channel using an optically driven pump. The pump consists of two counter rotating birefringent vaterite particles trapped within a microfluidic channel and driven using optical tweezers. The transfer of spin angular momentum from a circularly polarised laser beam rotates the particles at up to 10 Hz. We show that the pump is able to displace fluid in microchannels, with flow rates of up to 200 microm(3) s(-1) (200 fL s(-1)). The direction of fluid pumping can be reversed by altering the sense of the rotation of the vaterite beads. We also incorporate a novel optical sensing method, based upon an additional probe particle, trapped within separate optical tweezers, enabling us to map the magnitude and direction of fluid flow within the channel. The techniques described in the paper have potential to be extended to drive an integrated lab-on-chip device, where pumping, flow measurement and optical sensing could all be achieved by structuring a single laser beam. 相似文献