Development of Weight-Moisture Grader for Wood by Microwave Sensor

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1. Development of downsize sensor of basis weight and moisture content for wood.In this study, we used a voltage-controlled oscillator with high power and wide range to, , increase S/N ratio, controlled a computer with A/D and D/A converters to detect and average frequency shifts and attenuations with high speed method, and measured the basis weight (standard deviation 2.5 g/m^2) and the moisture weight (standard deviation 0.125 g/m^2) of wood papers are measured simultaneously by using a microwave cavity. The software for the measurement was developed using C language, so that it was easy to install the software into ROM circuits. Therefore, we developed a downsize and potable prototype test instrument.2. Development of scanning sensor of basis weight and moisture content grader for woodAlthough we could make the point measurement by using the downsize test instrumen% we checked thi possibility of moisture grader to move a wood and measure the basis weight and moisture content distrib … More ution of the wood. In particular, we changed the cavity size to get suitable space resolution, and the'spatial resolution of 2 cm was obtained. We developed the microwave cavity which measured the spatial average with the diameter of 2 cm of the wood moisture and was independent of ligneous direction. We obtained the whole profile of basis weight and moisture content of wood by moving the wood on the straight moving table.3. Development of allay type sensor of basis weight and moisture content grader for wood.Finally, we made fundamental measurement of wood moisture grader by using electric scan instead of mechanical scan. Namely, we fabricated a sensor system that Ifas four to eight microwave cavities with different resonant frequencies, uses a divider and a combiner to separate and unite microwave powers provided by one microwave oscillator, and detect the transmitted microwave by using one detector. Therefore, we could the moisture distribution of a wood instantaneously by putting the sensor head on the wood. Less