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Volume 26 (1995 - 199･･･
- Issue 4 Pages 187-
- Issue 3 Pages 139-
- Issue 2 Pages 81-
- Issue 1 Pages 3-
Volume 26, Issue 4
Displaying 1-4 of 4 articles from this issue
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Hideki MORIYA, Shuichiro MATSUI, Yoshihiro MIWA, Kiyokazu GOTO1996 Volume 26 Issue 4 Pages 187-196
Published: March 25, 1996
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSTo execute the afforestation and revegetation for the protection of environment, the techniques for raising good seedlings are required. Seedlings of camphor tree, a broad-leaved tree, were used in this experiment. From August to January, the growth characteristics of the seedlings were observed under different conditions of light intensity and soil moisture content in a plastic house.
The changes of total dry weight, leaf area and leaf dry weight were well fitted to simple logistic curves. Under shading (ca. 29% of control), the dry matter production, absolute growth rate and relative growth rate (RGR) increased compared with those of control; these were ascribed to the characteristics of camphor trees. The top growth was also accelerated due to the sufficient partitioning of photoassimilate to leaf fraction. According to the growth analysis, the adaptation form of camphor tree seedlings to shading was interpreted as the ‘stress avoidance’ in which the leaves became thin and large. While, under conditions of low soil moisture, RGR decreased because the top growth was restricted. This adaptation form was the ‘stress tolerance’ in which the dry matter partitioning to roots increased.View full abstractDownload PDF (1132K) -
Mhammed Larhrafi, Soichi NISHIYAMA, Hiroshi KAWANO, Koichi IYANAGA1996 Volume 26 Issue 4 Pages 197-203
Published: March 25, 1996
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESS
In an attempt to develop a low cost by-pass elbow meter for flow monitoring in microirrigation systems, characteristics of by-pass flow across 90° commercial PVC elbows were clarified for the case of diameters ranging from 20mm to 50mm. The by-pass and main flow discharge relationship was found to be linear, this linearity characteristic could be valuable for flow measurements. Metering characteristics of each elbow as a function of the pressure head differential and as a function of the by-pass flow were determined for each elbow.
When inserting within the by-pass path a high resistance in comparison with the by-pass friction losses, the by-pass flow rate and main discharge relationship will remain strictly linear and the error in flow metering falls within the range of the by-pass flow meter reading precision. The performance of an elbow meter when calibrated on by-pass flow basis is quite as good as when it is calibrated on the basis of the pressure head difference.
Since the by-pass flow rate is too small in comparison with the main flow discharge (1/20 for the case of 30mm elbow with 10mm orifice size), the by-pass elbow meter will use a low flow rates flow meter usually at low cost to give accurately total discharge. By also selecting an appropriate by-pass orifice size, the range of the by-pass flow meter could be adjusted to the desired range.View full abstractDownload PDF (720K) -
Discharge and drying process of sludge from a rotary drum solar dryerSeishu TOJO, Kengo WATANABE, Fusakazu AI, Allen C. CHAO1996 Volume 26 Issue 4 Pages 205-210
Published: March 25, 1996
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSA proposed solar drying system which consists of a solar housing and a perforated rotary drum dryer was studied to clarify the rapid drying of the sludge while being discharged from the drum. The sludge was pushed out gradually through small holes around the periphery while the drum was rotating. Sludge movement and discharge were observed with a video camera using a drum made from transparent flexiglass. The following findings discuss the relationship between the sludge discharge, hole size and the drum speed.
1. The sludge was carried up with the rotation of the drum up to a certain angle. This motion was explained by the friction between the inner surface of the drum and the sludge. The angle of repose in the drum was calculated with the theoretical model when the rotating rate of the drum was low. At high rotating rate, the angle of the repose was larger because the sludge did not slip on the drum surface and the slipping occurred only within the sludge layer.
2. The amount of the discharged sludge was proportional to the 1.9th power of the hole diameter and to the 0.53th power of rotation rate of the drum. The discharge was independent of the sludge height in the drum.
3. The drying rate during the discharge process was measured using the formed samples. The rate was proportional to the square root of the Reynolds number while evaporation was proportional to the 1.5th power of the bar diameter.
4. The hole diameter must be smaller because drying rate was higher at smaller bar diameter. Sludge particle diameter and admixtures must be considered in selecting the best hole diameter.View full abstractDownload PDF (638K) -
Measurement of Silo Storage of PaddyYoshihiro MIWA, Kiyokazu GOTO1996 Volume 26 Issue 4 Pages 211-217
Published: March 25, 1996
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSIn the period of paddy storage at the concrete silo of country elevator, various storage states, for example silo surface temperature, grain temperature etc., were measured. The measurement duration was from december, 1989 to september, 1990.
(1) The moisture content was about 13.5%WB, and the grain temperature was 12-15°C, which were fairly constant when grain was unloaded in the silo.
(2) Regarding to the change of air temperature at upper space in the silo, the amplitude was a little smaller, and the time lag of 4-5 hours existed in comparison with the atmospheric condition. However, the long term trend of both temperature change was similar.
(3) The relative humidity at upper space in the silo was constant, the value was the water activity of stored paddy.
(4) In the daytime, the surface temperature was much higher than atmospheric temperature because of the solar radiation. The highest temperature appeared at the roof of silo. There was no difference in surface temperature owing to the height at the vertical side.
(5) The direction of heat flux though silo wall was from inside to outside in winter, so the grain temperature lowered gradually, and inverse in spring and summer.
(6) At the direction receiving solar radiation, the grain temperature showed a one-cycle-per-day periodic change within the distance of 100mm from the wall. Because the grain temperature of peripheral zone in the silo and the atmospheric temperature changed similarly over long term, the adiabatic effect of concrete wall cannot be expected.
The temperature of grain which locates in the higher place in the silo was higher, however the difference is small.
(7) The integrated grain temperature during storage was calculated. The closer to the silo wall the grain is located, the bigger the value became, so the deterioration may occur rapidly.View full abstractDownload PDF (779K)
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