Seichi Okamura

A new microstripline-type moisture sensor for heavily wet tea leaves

This paper describes a new sensor for high moisture measurement in producing green tea. The sensor is based on the microwave transmission technique. It uses a microstripline, on which tea leaves under test are overlaid. A microwave signal at 3 GHz was transmitted along the line, and attenuation and phase shift of the wave were measured. The moisture content of the leaves was calculated by a new idea of using the ratio of two signals corresponding to the attenuation and the phase shift. The sensor measured a moisture content range from 155 to 320% on a dry basis.

Moisture Content Measurement for Green Tea Using Phase Shifts at Two Microwave Frequencies

The experimental results for moisture measurement of green tea usingmicrowave free-space technique are presented. The method is based on a ratioof phase shifts at two microwave frequencies after propagating through asample of green tea. It is shown that the method provides the moisturecontent of tea leaves from 6% to 32% on a dry basis without any knowledge onthe thickness and the density of sample. The mean and the maximum errors inthe moisture determination for tea leaves were 1.2% and 3.7%, respectively.

Structural properties of In-Se thin films prepared by direct evaporation of InSe chunk

Abstract In-Se films were deposited by direct evaporation of an InSe chunk using hot-wall-type evaporation equipment. The crystal structure was studied by X-ray diffraction using the Cu Kα line and the crystallographic properties of the films, such as the half width of the diffraction peak and the standard deviation of the rocking curve, were estimated as a function of the preparative conditions. It was found that films with a thickness above the critical value had a preferred (0001) orientation and that this critical thickness depended both on the substrate and on the source temperatures. In the present study, the films grown at 320°C with Tso in the range from 550 to 570°C had the highest orientation.

A density-independent method for high moisture content measurement using a microstrip transmission line.

This paper describes a method to measure high moisture content in materials from 190% to 350% on a dry weight basis. The method uses a microstrip transmission line, on which the material under test is overlaid. A parameter calculated from the attenuation and phase shift of the microwave signal is proposed to measure the moisture content. The experiments were performed on samples of sawdust, and the results show that the method is able to determine high moisture content independent of density. The standard error of calibration for the moisture content determination was 12.4% in the moisture content range from 190% to 350%.

Properties of Dielectric Ring Resonator and Application to Moisture Measurement

This paper presents properties of a dielectric ring resonator and its application to measurement of material moisture. Theoretical analysis has been done to select better resonant modes in the resonator with higher sensitivity and wider moisture content measurable range than the formerly often used TE011 mode by some researchers. Experiments have also been done to verify the theoretical results. The HE212 mode in the resonator has the highest sensitivity of 1.0 MHz frequency shift corresponding to change of 1.0% moisture content. The measurable range of moisture content is up to 12% at dry basis. The mode of HE211 has a wide measurable range approximately between 3% and 75% and its corresponding frequency shift is 12 MHz.

Moisture content measurement by microwave attenuation and problems

This paper describes about the state of a microwave moisture sensor using for a drying process of green tea production in Japan. It can measure moisture content in the standard deviation of 6.8% of the readings but has some problems to be solved for better operation in future.

New Moisture Sensor with Microstripline for High Moist Leaves in Green Tea Production (Neuer Feuchtesensor mit Mikrostreifenleitung für hochfeuchte Blätter in der Produktion von grünem Tee)

This paper describes a new sensor for the production of green tea. It can measure the moisture content as high as 160 to 300% on dry basis by use of microwave at 3GHz. The wave traveling down along a microstripline detects the information on the moisture contents of the green tea leaves overlaid on the microstripline. The moisture content of the leaves is calculated from two signals of the ratio of attenuation and phase shift of the waves traveling over the microstripline. The error of the measurement was about 3% of the readings. Ein neuer Sensor für die Produktion von grünem Tee wird vorgestellt. Hohe Feuchtegehalte zwischen 160 und 300% (dry basis) werden mittels Mikrowelle bei 3GHz gemessen. Eine Welle auf einer Mikrostreifenleitung ermittelt die Informationen über den Feuchtegehalt der grünen Teeblätter, die auf der Mikrostreifenleitung liegen. Der Feuchtegehalt der Blätter wird aus dem Verhältnis von Dämpfung und Phasenverschiebung der sich auf der Mikrostreifenleitung ausbreitenden Wellen errechnet. Die Messabweichung betrug etwa 3%.

Measurement of complex permittivity of moist sawdust by perturbation method with a dielectric ring resonator

This paper presents complex permittivity measurement of material using dielectric ring resonator. The method descried in the paper uses the perturbation method of dielectric ring resonator. In the conventional method, the value of one parameter in the formula of the perturbation method had been obtained using a standard sample and it was assumed as a constant. In our proposed method, it is obtained by the analytical solution of the dielectric ring resonator. Thus the measurement accuracy by the proposed method has been greatly improved. The proposed method was used to measure the permittivity of the sample of sawdust, of which the moisture content is from 0 to 120% on dry basis. The values of complex permittivity obtained by using HE211 mode and TE011 mode are in good agreement. By the proposed method, the maximum difference for real and imaginary part of permittivity using the two modes are 5.8% and 5.0%, respectively. It was shown that the results are much better than that by the conventional method.

Comparison of density-independent methods for moisture measurement using microwave free-space technique

This paper compares our proposed new method to the former methods for density-independent moisture measurement using microwave free-space technique. The measurement setups and the published results of the two methods are summarized and compared. The methods are compared in the aspects of accuracy and moisture range based on the measurements for the same samples of green tea and timber. It is shown that the accuracy by the new method is better than that by the former method for both materials in the moisture range from 2 to 30%. The results also indicates that the new method has the feature to be able to measure wide moisture range. The new method measures moisture content up to 42% for green tea, in contrast to the former method, by which the maximum measurable moisture content is approximately 30%.

Moisture measurement by dielectric ring resonator in microwave range

This paper presents a study on the measurement of material moisture in the microwave range. The dielectric ring resonator is utilized as the model for both theoretical analysis and measurement. It denotes that the TM/sub 011/ mode has high accuracy with its measurable range of moisture up to 40% (dry basis), and the HE/sub 211/ mode has a measurable range of more than 100% with acceptable accuracy.