Yohzoh Okumura

Photoelectric inclination sensor and its application to the measurement of the shapes of 3D objects

A method for obtaining the tilt angle and direction in a two-dimensional plane, by using a photoelectric inclination sensor consisting of an LED, a hemispherical spirit level, and a photodiode array is explained. An application of the sensor to the measurement of the shape of a 3-D object is also described. Light from the LED projects a bubble in the spirit level and throws a shadow onto the surface of an array composed of four equivalent p-n junction diodes, isolated from each other by a cross on a wafer. The tilt angle and direction in a two-dimensional plane are obtained by combining the diode outputs. By positioning the sensor on the crosspoints of the lines drawn longitudinally and latitudinally at an interval on the surface of a small mountain in a Japanese garden, the x and y components of the tilt angle can be obtained and its shape is reconstructed by a computer. The principle of the sensor, the system to display the tilt angle and its x and y components, and the application of the system to the measurement of the shape of a mountain are explained. >

Statistical analysis of field data of railway noise and vibration collected in an urban area

Abstract The effects of various factors on railway noise and vibration were studied through multiple regression analysis of the field data at 79 sites along 8 railway lines in an urban area. The results show that peak and sound exposure levels of railway noise can be explained fairly well by distance from track, railway structure, train speed, train length and so on. Because of the close relationship between peak and sound exposure levels, the main factors such as distance from track and railway structure give similar contributions to both noise levels. Train speed gives a greater contribution to peak level than to sound exposure level, while train length gives less. Regarding the vibration level, it was found that the contribution of background vibration is greater than that of railway structure and train speed. The results were applied to predict railway noise and vibration, and were also compared with the results of the Shinkansen Super Express railway which have already been reported.

Photoelectric inclination sensor

Abstract A method for obtaining the tilt angle and direction in the two-dimensional plane by using a photoelectric inclination sensor, consisting of LED, a hemispherical spirit level and a photodiode array is explained. Light from the LED projects a bubble in the spirit level and throws a shadow onto the surface of the array composed of four equivalent p-n junction diodes, isolated from each other by a cross on a wafer. When the sensor is kept horizontal, the area of the shadow in each diode is exactly equivalent. But when it is inclined, the area is not equivalent. Assuming that the shadow on the array in a low tilt angle is circular and the output current per unit area is constant over the surface of the diodes, the tilt angle and direction in a two-dimensional plane is obtained by combining the diode outputs. The principle of the sensor, its fabrication process, theoretical analysis of the sensor output against tilt angle and direction, and the system to display them in CRT are explained. Finally, the experimental values are discussed.

CHANGES OF THE SHINKANSEN SUPER EXPRESS RAILWAY NOISE SINCE THE OPENING IN 1964

Abstract Slow peak and sound exposure levels L Amax , L AE of the Shinkansen Super Express railway noise measured in 1976, 1981 and 1985 and the physical noise measure prescribed in the environmental quality standards were analyzed by a multivariate statistical method. The results of these surveys were compared. Five factors (distance, train speed, railway structure, train passby and noise barrier) can account for about 61–72% of variance of L Amax and L AE . The contributions of the various factors to the noise levels changed in these surveys. The change in equivalent sound level L eq24 since the opening of the line was also discussed. From the opening to around 1975 L eq24 increased with increasing number of trains per day. Then the level decreased gradually because of the implementation of anti-noise measures, and L eq24 in 1985 seems to be comparable with that in 1965. The present railway noise within 12·5 m from the track, however, exceeds the quality standards in Japan.

Reaction to the outdoor noise among inhabitants in Nagoya, Japan and Beijing, China

Inhabitants’ reaction to outdoor noise in Nagoya and in Beijing was surveyed. A questionnaire on noise was conducted with more than 2000 people in Nagoya and more than 1000 in Beijing. They were also asked whether they were sensitive to each of the 37 types of noise sources. The responses of inhabitants to the above questionnaire in Beijing are more sensitive than those in Nagoya to loudness, annoyance, and sleep disturbance. Road traffic noise is the most audible of 37 noise sources in both cities. Sounds of fireworks and sounds from festivals are also highly audible in Beijing. The most annoying noise is one from motorcycle gangs in both cities, and one from construction in Beijing. The annoyance rates in Beijing are higher than those in Nagoya.