The coal-biomass briquette is an alternative fuel that replaces low-grade coal. It is expected that the use of coal-biomass briquettes will effectively reduce the indoor concentration of sulfur dioxide (SO 2 ) emitted during raw coal combustion. In this study, indoor concentrations of SO 2 emitted from combustion of either coal-biomass briquettes or low-grade coal in households in Nanchuan, which is in the rural area of Chongqing City, China, were measured. The acidic gases were collected using passive samplers, and the samplers were taken to the laboratory for extraction and measurement. The SO 2 concentrations resulting from the use of coal-biomass briquettes were clearly reduced compared with those resulting from the use of low-grade coal. The concentrations of SO 2 to which the inhabitants (housewives) of the houses were exposed were also measured, and were found to be less with coal-biomass briquettes. Although with coal-biomass briquettes exposure concentrations still exceeded the World Health Organization guideline for SO 2 (125 µg m −3 ), indoor air pollution and adverse effects on human health caused by SO 2 could be decreased by substituting coal-biomass briquettes for low-grade coal as a domestic fuel.

We report the application of an acoustooptic tunable filter (AOTF) to the wavelength monitor in a fiber-optic sensing system with fiber Bragg gratings (FBGs). The system requires good temperature characteristics. A system with good temperature characteristics has been realized using two light wavelengths as references. The accuracy of the measured wavelength was approximately 0.63 pm in the temperature range of the AOTF device from À20 to 70 C. This accuracy corresponds to strain of about 10 À6 .

No abstract

Various optical spectrum analyzers have been used as strain-sensing equipment in fiber-optic sensing system based on fiber Bragg gratings (FBGs), which has been expected and investigated to monitor the safety of buildings, bridges, road slopes and other structures. An acoustooptic tunable filter (AOTF) with surface acoustic waves (SAWs) on LiNbO3 has been applied to a wavelength monitor as a simple spectrum analyzer in the system, because it has the characteristics of a small size, a simple configuration, fast response, and low cost. It has not been experimentally varified whether the wavelength monitor consisting of an AOTF device can be used as the strain-sensing system. To check the performance, the fabricated wavelength monitor with the AOTF device has been tested in the fiber-optic strain-sensing system using FBGs. As a result, the shift in the Bragg reflection wavelength corresponding to the change in strain at the fiber sensor has been detected for the first time by an AOTF device. The accuracy of the measured wavelength was approximately 0.9 pm at room temperature.

No abstract