Silicon infrared diffuser for wireless communication.
We show what we believe to be a novel way to use silicon in infrared radio communication as a suitable material for the realization of optical diffusers in the range of 850-1600 nm. A crystalline silicon wafer is made porous by means of electrochemical etching. The porous silicon produced is optically characterized, and measurements report a high reflectance in the band of interest. We also study the angular distribution of diffused radiation by the porous silicon surface at different angles of incident radiation. Measurements show that radiation diffuses in a quasi-Lambertian manner, confirming the good performance of this material as an incident radiation diffuser.
Aluminum diffuser of Lambert scattering and high reflectivity based on abrasion and sodium hydroxide corrosion
We discover that an aluminum surface roughened with 30–70 µm carborundum abrasive gets Lambert scattering properties and a higher hemisphere reflectivity after being corroded with sodium hydroxide solution. Experimental results demonstrate that the scattering properties of the corroded aluminum surface conform to the Lambert cosine law at normal incidence and the hemisphere reflectivity is obviously improved in the 250–1500 nm spectrum range.
Centrifuge modelling of effects of shield tunnels on existing tunnels in soft clay
With the rapid development of the subway network,the phenomena of shield tunnels going across the adjacent tunnels are becoming more and more common.The interaction between shield tunneling and nearby tunnels is more complicated than the ordinary shield tunneling in intact soil strata.Based on the project of Shanghai Bund Passage crossing Metro Line 2,the method of centrifuge modeling together with the field measurement is employed to study the effects shield tunneling on nearby strata and existing tunnels.In centrifugal model tests,the effects simulation techniques considering the unloading of excavation,ground loss and grouting are developed to analyze the longitudinal settlement of the shield tunnel and the existing tunnel induced by the shield tunneling.Besides,the deformation distribution and settlement curves of the existing tunnels during shield construction are studied by using the monitoring data.