光纤连接器:不仅适用于高速传输

目前光纤电路的应用范围不只是限于极远距离的高速率数据传输.标准的光纤连接器正在逐渐扩展其应用范围,从激光外科手术到水下摄像设备,从石油化工厂的外界环境到原子反应堆的内部,我们都可以找到光纤连接器的应用.本文的目的是想给刚进入光纤连接器领域的工程师们提供一些知识,帮助他们认识连接器的基本类型和安装风格,本文所介绍的内容可以为读者提供连接器性能和价格方面的参考.     

Optimising Channel Assignments for Private Mobile Radio Networks in the UHF 2 Band

Private mobile radio (PMR) services are widely used in business and emergency applications. Typically, these services use the UHF 2 band (450–470 MHz). In order to comply with continental practice, the provision of these services in the UK is to be realigned and a new operational assignment will be generated in 2005. However, this can only be achieved with an appropriate model and the ability to make assignments for large regional networks. The purpose of this paper is to bring our experiences of this problem to the wireless arena. We explain the model used when making assignments for UK PMR networks and identify existing techniques and theory which are appropriate for this problem. We demonstrate that improved assignments and estimates of spectral requirements for large operational services can be found.     

RF measurement of wire complex permeability

The complex permeability of thin round wires is measured with a coaxial system at half-wavelength resonance, using surface impedance and low-loss transmission line concepts. A steel wire is measured over the band 300 MHz-3 GHz. The results compare well to measurements made early in the last century.     

Analysis of an electromagnetic induction detector for real-timelocation of buried objects

Spatial response characteristics of an electromagnetic induction sensor as it passes over a metallic object are investigated using a simple analytical technique. In this low-frequency technique, one replaces a metallic object with equivalent electric and magnetic dipoles and then applies the principles of reciprocity to obtain the induced EMF in a sensor coil. Analysis is carried out for a sensor employing rectangular coils, and the object set is confined to a sphere and a prolate spheroid. The simple approach, which is illustrated with both numerical and experimental data, is found to be adequate to understand the effect on the response characteristics of parameters such as object depth, orientation, aspect ratio, and material properties     

Impact and options for boron diffusions in buried contact solar cells

Boron-diffused rear surfaces are used in place of an Al/Si alloy to form a back surface field (BSF) for single-sided buried contact (SSBC) cells. The findings are that a heavy boron diffusion over a large area can retain high bulk lifetime and have a low saturation current. SSBC solar cells that were made had the entire rear heavily boron diffused. These cells had open-circuit voltages of 650, 645, and 640 mV on 3 and 10 Ω cm p-type, and 100 Ω cm (rear junction) n-type, respectively.     

Evanescent wave cavity ringdown spectroscopy: a platform for the study of supported lipid bilayers

Evanescent wave cavity ringdown spectroscopy (EW-CRDS) is advocated as an approach for monitoring the formation of supported lipid bilayers (SLBs) on quartz substrates in situ and for the quantitative study of fast molecular adsorption kinetics at the resulting modified biomimetic surface. This approach is illustrated using SLBs of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). Complementary atomic force microscopy (AFM) and quartz crystal microbalance with dissipation (QCM-D) measurements confirm the formation of bilayers on quartz. The subsequent interaction of the porphyrin, 5,10,15,20-tetraphenyl-21H,23H-porphine-p,p',p',p'-tetrasulfonic acid tetrasodium hydrate (TPPS) with the cationic bilayer-modified silica surface has been studied using EW-CRDS combined with an impinging-jet to deliver analyte to the surface in a well-defined manner. The adsorption of TPPS to the bilayer was kinetically controlled and the adsorption rate constant was found to be 1.7 (±0.6) × 10(-4) cm s(-1) from finite element modeling of the jet hydrodynamics and associated convective-diffusion equation, coupled to a first-order surface process describing adsorption. These proof-of-concept studies provide a platform for the investigation of molecular processes at biomembranes using EW-CRDS for chemical species showing optical absorbance in the visible and ultraviolet range.     

Antitussive properties of butorphanol

Butorphanol (levo-N-cyclobutylmethyl-3, 14-dihydroxy morphinan), a potent analgetic agent of the narcotic antagonist type with a low abuse potential in laboratory animals, was evaluated for antitussive activity in unanesthetized guinea-pigs and dogs. Subcutaneously, it was over 100 times more active than codeine, dextromethorphan and dl-pentazocine and about 20 times more active than morphine in the guinea-pig, while in the dog it was 100, 10 and 4 times more active than codeine, dl-pentazocine and morphine, respectively. Orally, butorphanol was 15-20 times more active than either codeine or dextromethrophan in both species. Naloxone reversed the antitussive effects of butorphanol, codeine, morphine and dl-pentazocine while those of dextromethorphan were not antagonized. The antitussive effect of butorphanol and morphine lasted about 4 hr and both compounds were longer acting than codeine. Butorphanol was also shown to be as effective against cough of pathological origin as against experimentally induced cough in the dog.