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Volume 57, Issue 1
Displaying 1-8 of 8 articles from this issue
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Song GU, Kyoichi OTSUKI, Makio KAMICHIKA2001 Volume 57 Issue 1 Pages 1-10
Published: March 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDaily albedos of a bare sand surface were measured with a solarimeter (Eko MS-62) between 23 August and 30 November in 1997 at Tottori sand dune, Japan. These quickly decreased on rainy days, and recovered during dry spells (days between rainfalls).
A strong exponential relationship was found between daily albedos and the number of dry days. The daily albedos on dry days also showed a direct relationship with daily transmissivities in the range less than 0.55.
Two simple models were developed to estimate daily albedos for dry spell days on bare Tottori sand surface using routine meteorological data. Daily albedos were calculated using these two models, and compared with the measured daily albedos. For Model #1, the daily albedos were successfully predicted only using the number of dry spell days; the correlation coefficient between the estimated and measured albedo was 0.73, and the standard error was 1.2%. For Model #2, the number of dry spell days and transmissivity were considered in order to calculate the daily albedo on dry spell days; the correlation coefficient was 0.85, and the standard error was 0.9%. Estimated albedos were in good agreement with measured albedos.View full abstractDownload PDF (1082K) -
Ahmed M. ABDEL-GHANY, Toyoki KOZAI, Chieri KUBOTA, Ibrahem S. TAHA2001 Volume 57 Issue 1 Pages 11-19
Published: March 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSIn this article a mathematical method is established for predicting the monochromatic radiative properties (optical constants) of liquid radiation filters. The liquid radiation filter, LRF, is used as a selective solar radiation absorber for controlling the greenhouse temperature in a hot climate. LRF strongly absorbs the UV (ultraviolet) and NIR (near infrared) wave bands and highly transmits the PAR (photosynthetically active radiation) wave band. Moreover it is used as physical plant growth regulator in photomorphogenesis studies. The monochromatic optical constants of the LRF such as the refractive index nf, λ, the absorption coefficient σf, λ and the dimensionless extinction coefficient kf, λ are mathematically investigated by using the ray tracking technique. The transmittance due to absorption of the LRF τf, λ was investigated by considering the reflectance on the fluid surface. The consideration of a simplified refractive index nf, λ instead of a refractive index with complex part (nf, λ-ikf, λ) for the LRF is also examined because the LRF is highly absorptive radiatively and highly conductive electrically. The results of the present study show that all the monochromatic optical constants of the LRF can be investigated mathematically by using some limiting measured values of the spectral transmittance and reflectance. The simple refractive index nf, λ can be used for the LRF instead of the one with a complex part.View full abstractDownload PDF (1036K) -
Atsushi TORIYAMA, Nobutaka MONJI, Yasuyuki AONO, Ken HAMOTANI2001 Volume 57 Issue 1 Pages 21-27
Published: March 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSWe investigated the effects of urban sky view factor and foliage view factor on the thermal environment, based on field experiments in the street canyons of Osaka. Mean radiation temperature (MRT) and physiologically equivalent temperature (PET) are used as the indices of the thermal environment. We found that MRT and PET decrease with a decrease in the sky view factor and with an increase in foliage view factor. The difference of 0.22 in the sky view factor caused a difference of 23°C in PET. A difference of about 0.27 to 0.35 in the foliage view factor caused a difference of about 8.2 to 9.0°C in PET.
We tried to convert the effect of wind speed to that of the foliage and found that an increase of about 3ms-1 in wind speed is necessary to obtain the same effect as a change in the foliage view factor from 0.27 to 0.35.View full abstractDownload PDF (770K) -
Hirakazu SEKI, Tatsuo KIMURA, Akihito MIYAMOTO, Hiroshi SUGAYA, Kaori ...2001 Volume 57 Issue 1 Pages 29-40
Published: March 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSA mathematical model was developed for predicting air temperature, humidity and velocity fields in a closed-type sloped greenhouse. Calculated results of air temperature profile along the slope agreed well with the experimental results except in the daytime when the air temperature was high, and it seemed that the model would be useful for environment analysis in the sloped greenhouse. This model would be better if three-dimensional heat flow had been taken into account in the daytime. Both the calculated and experimental results showed that air temperature was higher in the upper part of the slope than that in the lower part for the greenhouse with a double-film-cover. For the greenhouse with a single-film-cover, however, air temperature in the upper part was not necessarily higher than that in the lower part especially in the nighttime. Provided that floor and cover temperatures were uniform, respectively, air temperature and velocity fields were simulated. The simulated results showed an appearance of air temperature difference between the upper and lower parts. Both the higher and lower temperature regions extend as inclined angle increases. However, this temperature difference between the upper and lower parts in the case of 10 degrees of inclined angle is not so different from that in the case of 30 degrees. In addition, an increase in the inclined angle makes air velocity larger, so that its increase over a certain critical value inhibits the development of air temperature difference between the upper and lower parts rather than promotes it.View full abstractDownload PDF (3691K) -
Mika SAGAWA, Kenji KURATA, Kunio TAKAHASHI, Kenichi MINEUCHI2001 Volume 57 Issue 1 Pages 41-48
Published: March 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe objective of this study was to find simple and objective methods of diagnosing the ailments of trees in indoor spaces, such as atriums. In this study, two simple diagnostics were compared. One was the analysis of the laser-induced fluorescence spectra of leaves and the other was the analysis of the laser-induced chlorophyll-fluorescence induction kinetics (Kautsky effect). In the latter analysis, second time derivatives of the induction-kinetics curves were used. Cinnamomum camphora and Quercus myrsinifolia grown under different light conditions and Cinnamomum camphora under water stress were used in the experiments. The effects of low irradiance were detected in both the induction kinetics and the spectra; however, the effects of water stress were detected in the induction kinetics only. These results indicate the possibility of utilizing laser-induced-fluorescence induction-kinetics for diagnosing the ailments of trees.View full abstractDownload PDF (1102K) -
Mika SAGAWA, Kenji KURATA, Kunio TAKAHASHI, Kenichi MINEUCHI2001 Volume 57 Issue 1 Pages 49-54
Published: March 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSEfficient tree diagnosis methods have been required for the improvement of maintenance techniques in indoor plants. Laser induced chlorophyll fluorescence induction kinetics have been shown to be one of the possible techniques to detect indoor tree conditions. In this study, changes in induction kinetics and leaf sugar content with the dark treatment were investigated using Myrica rubra and Ternstroemia gymnanthera. Measurements conducted during July and September (Japan) showed good correlation between the period of dark treatment and the induction kinetics/leaf sugar content, regardless of the kind of trees tested. Effects of the dark treatment were detected in the second time derivatives of the induction kinetics curves between 5-24s. However, results in the early spring and late fall did not show such correlation. These results showed that LIF application to detect low irradiance stress of indoor plants has high potential, but that its application season is restricted.View full abstractDownload PDF (829K) -
Effects of Ridge Geometry, Depth of Buried Pipes, and Change in the Surface Temperature of Pipes in the Daytime on Soil TemperatureItsuo TANAKA, Yukitsugu ISHII2001 Volume 57 Issue 1 Pages 55-59
Published: March 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe control of soil temperature in the root zone by circulating warm or cold water in pipelines buried in ridges has been carried out for a long time. However there is little research on temperature distribution in the ridge during the temperature control process. In our previous paper (Tanaka and Ishii, 2000), numerical solutions of soil temperature distribution in a ridge were shown for the cases of soil cooling and soil heating, and the effects of soil physical properties, ambient air temperature, direct solar radiation absorbed at ridge surfaces, and the surface temperature of pipes on soil temperature distribution were examined. In this paper, the effects of ridge geometry and depth of buried pipes on soil temperature were examined using the same method and conditions as those shown in the previous paper. Further simulations for the case of changing the surface temperature of pipes with time to prevent high soil temperature in the daytime were carried out for the case of soil heating.View full abstractDownload PDF (516K) -
Seiji HAYAKAWA, Jiquan ZHANG, Haruhiko YAMAMOTO, Kenji SUZUKI, Taiichi ...2001 Volume 57 Issue 1 Pages 61-67
Published: March 10, 2001
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (3862K)
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