All issues
Volume 49 (1999)
- Issue 2 Pages 35-
- Issue 1 Pages 1-
Volume 49, Issue 1
Displaying 1-4 of 4 articles from this issue
- |<
- <
- 1
- >
- >|
Paper
-
Takashi NAKAJIMA1999 Volume 49 Issue 1 Pages 1-10
Published: 1999
Released on J-STAGE: July 21, 2011
JOURNAL FREE ACCESSThe gas detection mechanism of a semiconductor gas sensor uses the phenomenon in which the flammable gas is adsorbed on the surface of the sensor when a sintered compact of metallic oxide is heated at a constant temperature with an electric heater in the sensor. If the sensor is set to be activated at a certain temperature, flammable gas such as hydrogen, methane and propane can be detected. A gas leak alarm device uses this phenomenon. Ethanol, however, tends to adsorb more onto the surface of the sensor than other types of flammable gas, and this is a cause of gas sensor malfunction. It is also difficult to distinguish gas types because there is not enough data.
We have reported that we could distinguish propane, methane and ethanol by using multiple semiconductor gas sensors to improve the capability of distinguishing gas types, by comparing the output response patterns using a heater voltage control and by investigating the output voltage ratio.
In estimating the output response to mixed gases, many patterns were possible as determined by the concentration of each gas. However, when the heater voltage is changed, it is not possible to obtain an output response to mixed gases by merely calculating and synthesizing single gas output responses. This paper describes a simulation of the output response to mixed gases from the output responses to single gas and infers an output response to mixed gases.View full abstractDownload PDF (735K) -
Yuichi WATANABE, Sanae MATSUSHIMA1999 Volume 49 Issue 1 Pages 11-18
Published: 1999
Released on J-STAGE: July 21, 2011
JOURNAL FREE ACCESSIt is useful in planning the safety countermeasures of initial behavior at earthquake that the walking ability at the time shaking by earthquake is studied. In order to investigate the relation between intensity scale of earthquake and walking speed, walking experiments were carried out on the table of the shaking machine. JMA seismic intensity scale was 3∼6 ranges. The walking distance of subjects was 2 m on this hypothesis that man was in a house. Though the number of subjects were the few (male 15, female 15), the followings were chiefly found in this experiment.
(1) The average walking speed of subjects at earthquake motion did not change at a standstill so far as JMA seismic intensity scale 4. However, the walking speed gradually began to decrease from JMA seismic intensity 4. The decrease ratio of the walking speed has increased as JMA seismic intensity becomes stronger than 4.
(2) It was the maximum speed in the vibration factor of the floor that the walking speed at earthquake motion could be showed with one straight line irrespective of the frequency. The walking speed of subjects has decreased in proportion to the maximum speed of the floor.
(3) The average walking speed of male and female were nearly the same speed, but female reached to a walking limit with weaker seismic intensity scale than male. There was a individual difference in the walking speed and limit.View full abstractDownload PDF (639K) -
Lijing GAO, Masataro SUZUKI, Ritsu DOBASHI, Toshisuke HIRANO1999 Volume 49 Issue 1 Pages 19-25
Published: 1999
Released on J-STAGE: July 21, 2011
JOURNAL FREE ACCESSA study has been performed on the heat transfer near the leading flame edge spreading over a cellulose sheet permeated with an adhesive and the effects of the adhesive on the flame spread phenomena were discussed. The test pieces used were filter paper sheets permeated various amounts of adhesive, polyvinyl acetate resin or urea resin. The temperature distribution of the gas phase and test piece surface near the leading flame edge spreading over each test piece was measured using a set of fine thermocouples, and on the basis of the results, the details of heat transfer were evaluated. Either of the isotherms near the leading flame edge spreading over a filter paper sheet permeated with polyvinyl acetate resin or urea resin was shown to be almost the same with that over a pure filter paper except for a slight shift of the higher temperature region of the former to the sheet surface. The amount of heat transferred through gas phase to the pure filter paper sheet was indicated to be larger than that to the filter paper sheet permeated with an adhesive. This was inferred to be the main cause to decrease the mass burning rate with polyvinyl acetate resin permeation. In addition to this effect, radiative heat loss from the surface was inferred to be effective for reducing the mass burning rate with urea resin permeation to extinction.View full abstractDownload PDF (646K) -
Nobuhide TAKAHASHI, Hiroshi KOSEKI, Toshisuke HIRANO1999 Volume 49 Issue 1 Pages 27-33
Published: 1999
Released on J-STAGE: July 21, 2011
JOURNAL FREE ACCESSThermography gives detailed information on thermal radiation from fires. An apparent temperature distribution of thermography can be converted into a radiance distribution of a pool fire by simple calculations. Irradiance can be also calculated from the radiance distribution. The calculations have been validated by comparing irradiance measured by a wide view angle thermopile-type radiometer. Thus, radiative characteristics of a large-scale crude oil pool flame formed above a 20 m-diam. pan have been examined in detail by analyzing thermographic data. The results can be summarized as follows:.
(1) A mean radiance distribution of a large-scale pool fire represents the appearance of the largest radiance immediately above the rim of the pan and another local maximum at 0.6D (D is a pan diameter and equals 20 m) in height. The local maximum is due to intermittent luminous zones appearing among the smoke.
(2) The fire plume up to 0.3D including the continuous diffusion flame at the rim contributes to the total irradiance by about 40% and the fire plume up to 1D contributes to by 85%.
(3) The radiance of intermittent luminous zones appearing among the smoke is higher than that of continuous luminous flames and reaches 85 kW/m2/sr. The intermittent luminous zones are inferred to bring about large thermal radiation to the surroundings.
(4) The radiance of smoke parts on the recorded video image has been estimated to be smaller than 20 kW/m2/sr (apparent temperature; 1026K), comparing the video image with a simultaneous radiance distribution. An average proportion of irradiance emitted from the smoke parts in the total irradiance is estimated to be about 64%.View full abstractDownload PDF (662K)
- |<
- <
- 1
- >
- >|