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41.
Low-loss single-mode fibres with GeO2-doped SiO2 cores have been made by the c.v.d. method and the loss spectrum from 0.6 to 1.8 ?m measured. The minimum loss of the fibre with suitably designed parameters, characterised by the refractive-index difference and the core diameter, was 0.75 dB/km at 1.05 ?m. 相似文献
42.
In order to achieve the high-rate production of fibre preforms, the deposition mechanism in the VAD process has been investigated. The particle deposition rate was found to depend on the Reynolds number of the flame stream. The high-rate preform production of 4.5 g/min was attained by applying this result to the preform fabrication technique. 相似文献
43.
Nakahara Motohiro Chida Kazunori Hanawa Fumiaki Sudo Shoichi Horiguchi Masaharu 《Electronics letters》1980,16(3):102-103
A low-loss and wide-bandwidth optical fibre in the long-wavelength region has been fabricated by the v.a.d. method. Loss at 1.3 ?m is 0.98 dB/km and 6 dB down bandwidth is 1600 MHz km at 1.26 ?m. 相似文献
44.
A large preform for 220 km of fibre was fabricated with the vapour-phase axial deposition (VAD) method. The deposition rate for the core was 1.7 g/min. Optical fibre drawn from a part of the preform had optical attenuation of 0.58 dB/km and bandwidth 500 MHz km0.9 at a wavelength of 1.3 ?m. 相似文献
45.
A nonmechanical scanning Mirau-type spectral interference microscope has been developed for the measurement of three-dimensional surface profiles of discontinuous objects. An acousto-optic tunable filter (AOTF) is used as a high-resolution spectral filter, which scans the optical frequency of the broadband light emitted from a superluminescent diode. To generate spectral fringes that make full use of the limited coherence length of the filtered light we unbalanced the Mirau interferometric system by positioning the reference mirror nearly halfway between the top and the bottom of the step height. When the frequency of the broadband light source is scanned by an AOTF, the interference fringes move in opposite directions on the top and the bottom of the object. To uniquely determine the sign of the fringe movement over the large area of the object, we developed a three-dimensional Fourier-transform technique, and from the detected sign of the fringe movement and phase information, we determined the three-dimensional step height. Experimental results of the measurement of 100-microm step height are presented. The main advantages of the proposed system are that it provides nonmechanical scanning and a large measurement range without ambiguity in the sign of the phase. 相似文献
46.
47.
J Nakayama K Hamano Y Shimakura N Iwasaki C Nakahara N Imoto K Kobayashi T Arinami H Hamaguchi 《Canadian Metallurgical Quarterly》1997,28(6):335-337
BACKGROUND: Most adult anatomical texts state that the deep inguinal ring is situated midway between the anterior superior iliac spine and the pubic tubercle. The aim of this study was to determine if this was true in prepubescent children. METHODS: A total of 107 inguinal ligaments and canals were measured during inguinal operations in 80 children (68 boys, age range 1-118 months). RESULTS: The length of the inguinal ligament increased from a median of 4.3 cm (range 3.6-6.8) at less than 1 year of age to 7.5 cm (range 6.7-10.1) at over 4 years of age. The internal ring was situated medial to the midpoint of the inguinal ligament throughout childhood. The ratio of internal ring to public tubercle over inguinal ligament length was 42% (range 27-58) at less than 2 years; and 34% (range 25-46) at over 4 years. The inguinal canal remained short (median 1 cm (range 0.7-1.1) at less than 2 years, and median 1.1 cm (range 0.7-2.3) at over 4 years) suggesting that growth of the inguinal region in this age group occurs outside the canal. CONCLUSIONS: These results have implications for the siting of incisions, and question the necessity of opening the inguinal canal in children. 相似文献
48.
An ultrashort electrical pulse with a pulse width of 3.3 ps was generated successfully from an ordinary metal-semiconductor-metal photodetector simply by adding an input resistor and hold capacitor. The new detector not only provides ultrashort fall time, but also has other advantages such as ease of fabrication, high sensitivity, and low-bias operation. 相似文献
49.
Treatment of perfumery materials such as aromatic hydrocarbons was attempted using atmospheric surface discharge and UV light irradiation. The maximum decomposition rate of phenyl ethyl benzene with a concentration of 8% using the discharge with UV light is 96%, that is 12% higher than that without UV light. Combination of surface discharge and UV light enhances the decomposition rate and energy efficiency, and enables to suppress the generation of by-products such as benzene. 相似文献
50.
In this paper, the synthesis and solid-state structures of β-alkyl-substituted dipyrrolyldiketone BF2 complexes are discussed; these complexes can function as π-conjugated acyclic anion receptors (“molecular flippers”) and are potential building subunits of anion-responsive π-conjugated oligomers or polymers. Modes of the solid-state assemblies in these complexes determined by performing single-crystal X-ray analysis are found to depend on the lengths of the alkyl chains at the β-positions. A β-methyl-substituted receptor has a highly planar structure, which efficiently forms stacking assemblies in the core π-plane in the solid state, while a β-ethyl-substituted receptor shows no stacking assemblies due to the presence of bulky ethyl moieties, which form only dimeric structures by hydrogen bonding. β-Alkyl-substituted anion receptors can be used not only as monomer units of stimuli-responsive polymeric macromolecules but also as components of solid-state electronic materials. 相似文献