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Volume 41, Issue 4
Displaying 1-13 of 13 articles from this issue
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I. Model Experiments on Dimension Dependence of Transfer CoefficientTetsuya HASEBA, Daijiro ITO, Hiroto ISHIDA, Kazuno OHNO, Chiemi TAKAHA ...1986 Volume 41 Issue 4 Pages 311-319
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSField observations and laboratory experiments were performed to evaluate boundary-layer transfer coefficients for a fluttering plant leaf. Within a canopy, a plant leaf sometimes showed a periodic and lateral vibration for a few seconds at a time, when the fluctuation frequency of the main flow in wind was nearly equal to the characteristic frequency of the leaf.
Water-vapor transfer was investigated from rectangular leaf models of various dimensions fluttering resonantly with an artificial fluctuating air-flow with a turbulence-intensity similar to that of the wind within a natural canopy. Evaluated water-vapor transfer coefficients were larger than those estimated according to the conventional laminar boundary-layer theory. Below a critical Reynolds number of 1×104 to 3×104, the transfer coefficients were apparently proportional to the square root of the mean flow speed. Over the Reynolds number range below the critical one, the ratio of transfer coefficients observed in these experiments to those calculated from the theory was expressed as a function of the model length in the flow direction and the width transverse to the flow, that is, it increased with increasing length and decreased with increasing width.
Some causes for an increase in the transfer coefficients obtained from the experiments are discussed for a fluttering leaf model.View full abstractDownload PDF (1071K) -
Takeharu BOKURA1986 Volume 41 Issue 4 Pages 321-329
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSIt is found that high lands in the areas where Yamase winds are predominant are recommended as grasslands after analysing the vertical profiles of atmosphere in Tohoku district.
Being based on the temperature lapse rates and the screen temperatures, the vertical profiles of atmosphere in the summer in Tohoku district are classified in ten types:
When Yamase blows, the vertical profile is complex and one or two inversion layers often exist and Misawa and Sendai which are located in pacific sea side. On the other hand, the vertical profile does have no or one inversion layer at Akita which is located in Japan sea side.
It is difficult to estimate the air temperatures at 1400m height in Misawa from the temperature lapse rate, because of the existence of the temperature inversion layer.
But the air temperature of Misawa at 1400m height is in rather good agreement with the measured air temperature at the top of Hakkoda mountain whose altitude is 1400m, and it is clear that there is very little temperature difference according to altitude.
When Yamase blows, there is very little temperature difference according to altitude, therefore it is considered that similar biomass production can be expected at high lands to that plain.
In August, high land in Yamase region are often covered by mountain clouds which decrease solar radiation and bring high humidity, therefore summer depression of vegetation is considered to be little.View full abstractDownload PDF (2516K) -
Part 2. Freezing Temperature Influenced by the Wet or Dry Conditions on the Leaf Surface of Soybean SeedlingsJuro HANYU, Nobuhiro MATUOKA, Hisashi KON, Keiichi NAKAYAMA1986 Volume 41 Issue 4 Pages 331-335
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSIn order to examine the effect of dew on the leaf surface on the freezing temperature T1 of plant juice, the experiments were conducted by using the radiative cooling apparatus. When a pair of the primary leaves of a soybean seedling spread fully, the seedling was set in the apparatus and then cooled down to a subzero temperature. The mean freezing temperature of wet leaves T1w was -4.4°C and was 0.8°C higher than that of dry leaves T1d as shown in Table 3. The difference in temperature was significant statistically.
When one of a pair of leaves was dry and the other was wet, the wet leaf froze firstly and then the dry leaf froze within a few or longer seconds. The mean freezing temperature of the dry leaves T1dw was -3.9°C as shown in Table 4 and was 1.3°C higher than that of the dry leaves T1d (Table 3) as a result of ice inoculation by freezing of the wet leaf. The mean freezing temperature of the wet leaves T1ww was lower than T1dw as shown in Table 4. It is considered that this difference in freezing temperatures is due to the difference in evaporative cooling between the dry and the wet leaves under low humidity in the experimental cabinet.
The multi-regression equation on the frost injury ratio I, the freezing temperature T1 and the minimum leaf temperature T3 after T1 (see Fig. 1) in the previous paper (Yamanaka et al. 1982) was modified by adding the present experimental data taken at the warmer experimental conditions than the former and the following equation was obtained.
I=-8.21T1-17.40T3-34.26
In analyzing the experimental results, it was found that the frost injury did not occur when the plants were held in the supercooling condition or when the droplets on the leaves froze but plant juice did not freeze or only a part of liquid outside cells froze.View full abstractDownload PDF (553K) -
Part 2. A Theoretical Analysis of Heat Extraction and Accumulation Process by Water CirculationHirakazu SEKI, Tomoaki KOMORI1986 Volume 41 Issue 4 Pages 337-344
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSA theoretical analysis of an operation of extraction and accumulation of the heat generated in composting process by water circulation was made. The calculated results of the average temperature in a compost bed and the water temperature in an accumulator were compared with the experimental results obtained previously.
1) For the case of the intermittent water-circulation, there were slight differences between the calculated results and the experimental results of the average temperature in the bed during temperature recovering periods after the end of water-circulation. However, the calculated results of the water temperature in the accumulator, the available time for heat extraction and the recovery time of temperature in the bed agreed relatively well with the experimental results. The theoretical model was fairly fit for this case.
2) For the case of the continuous water-circulation, the calculated results of the average temperature in the bed were in fair agreement with the experimental results. The calculated results of the water temperature in the accumulator were however 3 to 7 degrees higher than the experimental results. It could be due to the heat loss through the pipes connecting the container for the compost with the accumulator, which was not allowed for in the theoretical model. It is necessary to modify the analytical model by taking account of this kind of heat loss.View full abstractDownload PDF (913K) -
(VIII) Effect of Mist and Submergence on Growth of a Bean PlantKazuyoshi KIMURA1986 Volume 41 Issue 4 Pages 345-350
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe present investigation was designed to examine the differences between the effects of rainfall and those of submergence. The growth response and injury of kidney bean plants were examined after the artificial rainfall (mist), root submerging and whole plant submerging treatments. Plants were exposed to mist (Precipitation: 5mm/h, Diameter of water drop: 0.24mm) or submerged in the growth chamber (20°C, 12hr light+12hr dark) for 5 days.
(1) Growth response and injury immediately after the treatments:
Considerable differences in growth response and injury were observed with the three treatments. In general, the inhibitory effects on growth and injury immediately after the treatments were marked on the shoot by mist, on the root by root submergence and on both the shoot and root by whole plant submergence.
Mist treatment decreased the area, dry weight and chlorophyll content of the leaves, but it increased the fresh weight of the stem and elongation of the root (longest root). The greatest wilting response was observed one hour after the end of mist exposure.
Root submergence decreased elongation, fresh weight and dry weight of root, but increased the dry weight of the stem. Wilting was not observed.
Whole plant submergence decreased markedly elongation, fresh weight of the leaf and root, dry weight of the shoot and root, and chlorophyll content of the leaf. Wilting was observed, but its degree was weaker than that of mist.
(2) Growth response and injury 12 days after the treatments:
Mist treatment caused growth inhibition, but the degree of inhibition was weaker than that immediately after the treatments. The aftereffect of mist remained on fresh weight of leaf and dry weight of shoot and root to some extent. Foliage leaves that opened after mist treatment were injured strikingly.
Root submergence decreased root length, leaf area, fresh weight (leaf, stem) and dry weight (shoot, root) to some extent, but foliage leaves were not injured.
Whole plant submergence decreased elongation, fresh weight and dry weight of shoot and root to a great extent. Foliage leaves were injured, but less severely than by mist.
These results suggest that the exposure to rainfall not only causes weak effects of submergence, but also has a different action on the plant.View full abstractDownload PDF (794K) -
(2) Reduction of the Cooling Load in NighttimeToyoki KOZAI, Zaiyong QUAN, Makio HAYASHI, Ichiro WATANABE, Tadayuki S ...1986 Volume 41 Issue 4 Pages 351-357
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSIn the previous paper (Kozai et al, 1985), cooling load of a greenhouse in summer nighttime Qc(kcal/m2 (floor area)/hr) was stated based upon an experiment carried out in a normal greenhouse. The relatively large values of the soil heat flux Qs and the heat transfer by air infiltration through crevices Qv, which were parts of the Qc, were observed. From the results, a large reduction of Qc was expected, if one reduces Qs and Qv in large quantities.
In the present paper another experiment, cooling a greenhouse continuously with a heat pump cooling system in summer nighttime, was carried out under following conditions, based upon above supposition.
1) To cover the whole floor with two coverings: lower one with foam polystyrene sheet (5cm thick) and upper one with aluminium powder sandwiched polyethylene film to reduce Qs.
2) To seal the whole greenhouse-cover airtightly with polyvinyl chloride film to reduce Qv.
The results of the experiment are summarised as follows.
(1) The quantity of Qc needed in present experiment was only 40% of that needed in former experiment, in keeping the same air temperature difference between inside and outside the greenhouse, and further reduction of 25% was obtained when fit single-layer polyolefine film curtain into the greenhouse.
(2) Average values of Qs and the number of air changes N were, 2kcal/m2/hr and 0.3/hr, fifteen and five times lower than those given in the previous paper, respectively. In consequence, the percentages of Qs and Qv to Qc were decreased from 38% and 40% in former time to 6% and 15% in this time, and the percentage of the overall heat transmission Qt to Qc was increased from 20% in former time to 75% in this time.
(3) Average value of the heat transmission coefficient ht was 2.3kcal/m2/hr/K and it decreased to 70% when fit the polyolefine film curtain into the greenhouse.
(4) The quantity of the heat transfer by convection, thermal radiation and water condensation at the external cover was affected seriously by the meteorological conditions outside the greenhouse.
In the view of the present results, cooling load of a greenhouse Qc in summer nighttime can be decreased effectively by means of reducing the soil heat flux Qs and the heat transfer by air infiltration through crevices Qv.View full abstractDownload PDF (877K) -
Yasumitsu KISHIDA1986 Volume 41 Issue 4 Pages 359-363
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
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1986 Volume 41 Issue 4 Pages 364-364,368
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
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Genji Ohara1986 Volume 41 Issue 4 Pages 365-367
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
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Fukuya KAMOTA, Hitoshi HONJO, Toshikazu ASAKURA1986 Volume 41 Issue 4 Pages 369-374
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
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Ritsuo MURAKAMI1986 Volume 41 Issue 4 Pages 375-381
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
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Group of Young Researchers1986 Volume 41 Issue 4 Pages 383-385
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
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[in Japanese]1986 Volume 41 Issue 4 Pages 386-387
Published: March 10, 1986
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (302K)
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