All issues
Volume 38 (2007 - 200･･･
- Issue 4 Pages 237-
- Issue 3 Pages 167-
- Issue 2 Pages 101-
- Issue 1 Pages 1-
Volume 38, Issue 4
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
Hideki MORIYAMA, Sadanori SASE, Yasushi UEMATSU, Tomoharu YAMAGUCHI2008 Volume 38 Issue 4 Pages 237-248
Published: March 25, 2008
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSThe wind pressure coefficients Cp on a pipe-framed greenhouse (or simply ‘pipe house’), whose shape consists of two or more curvatures, have been evaluated with a 1:20 scale model in a turbulent boundary layer. The length/width ratio of the model was 8.3. The Cp distribution was evaluated at various cross-sections of the model for various wind directions θ from 0° (normal to the ridge) to 90° (parallel to the ridge). The evaluated Cp distribution for θ=0° was compared with the specifications for greenhouses with gable and circular arc roofs in the current design standard for greenhouse structures, and a significant difference was observed. The Cp distribution changed significantly with wind direction. The largest negative Cp value was about -3.5 near the ridge corner when θ=25°. The influence of side gable openings on the external pressure coefficient Cpe and internal pressure coefficient Cpi were also investigated. It is found that the Cpe distribution was not affected by the openings. On the other hand, the influence of openings on the Cpi value was significant. When θ=0°, the value of Cpi was as low as -0.9, which sifted the net wind force coefficient Cf to a positive value. The value of Cpi depended on the location of the openings as well as on the wind direction. When θ=90°, the value of Cpi varied from -0.2 in the leeward opening case to +0.5 in the windward opening case.View full abstractDownload PDF (6242K) -
Field scale test of a composting system with vacuum-type aerationYoshiyuki ABE, Toshihiko IBUKI, Fumihito MIYATAKE, Yoshifumi HONDA2008 Volume 38 Issue 4 Pages 249-262
Published: March 25, 2008
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSPilot tests on a full-scale compost plant that uses vacuum-type aeration, allowing compost to be turned with a linear crane and ammonia to be removed by mean of chemical scrubbers, were conducted to evaluate the collection of ammonia discharge from the composting process.
When 300mm-diameter inlets of a vacuum-type aeration system, filled with wood chips, were laid 1.5m apart from one another at the compost bottom, the inlets resisted clogging due to water condensate or sediment, therefore accelerating the digestion of organic matter and the evaporation of raw materials. In addition, ammonia discharge from the compost surface was reduced compared with that of a positive-pressure aeration system; in the vacuum-type system 9.4% of the initial total nitrogen and approximately 90% of the ammonia discharge was removed by the scrubbers while the other 10% was contained in the water condensate or the drainage, which sum was equal to the ammonia discharge in the positive-pressure aeration system.View full abstractDownload PDF (6723K) -
Hideki MORIYAMA, David R. MEARS, Sadanori SASE, Atsuo IKEGUCHI, Tomoha ...2008 Volume 38 Issue 4 Pages 263-274
Published: March 25, 2008
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSTo investigate the low-cost reasonable design of a pipe-framed greenhouse (pipe house) under snow load, seven numerical finite element models of simple pipe houses were analyzed by stress analysis and buckling analysis. These determined the optimum position of bracing for pipe houses. The influence of the width and ridge height of the structure and the section modulus of the arch pipes on the upper limit of the allowable snow load was also obtained. Moreover, the relationship between a reasonable pipe house design and the arch pipe used for the structure was investigated. For the structures modified by the addition of two tension braces at points between 63% to 70% of the ridge height, the allowable snow load was significantly increased. The influence of addition of braces was remarkable for wider spans. There was little influence from the difference of the ridge height of the pipe house on the maximum allowable snow load for the heights considered using stress analysis. However, the maximum allowable snow load obtained by the buckling analysis decreased 54% as the ridge height increased so a buckling analysis is important. Considering the change of the support condition due to softening of the ground, increasing the size of the pipe section increases the allowable pipe spacing and reduces the total steel mass and shading of the structure. For a typical size pipe house, by replacing arch pipes of 19.1mm diameter with 1.1mm thickness by pipes of 42.7mm diameter with 2.0mm thickness, steel mass and shading rate decreased by 58% and 77% respectively.View full abstractDownload PDF (3122K) -
Yasuhiro HARADA, Naoaki DOSHU, Masato KOTAKE2008 Volume 38 Issue 4 Pages 275-283
Published: March 25, 2008
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSThe objective of this study is to estimate the airborne dust and ammonia-containing waste air emitted from Animal houses. Layer houses containing 120 layers, were investigated from July 2001 to December 2002. Layer houses kept at a constant temperature inside and ventilation air volume and having the same structure, were investigated as controls. The dust concentration in a typical layer house was 1.58mg/m3. The dust concentration was not correlated with the temperature inside, amount of ventilation, relative humidity of ventilated air, or passage of time. The dust emission was estimated to be 44.3g/day. The dust emitted per day increased in summer and peaked at about 80g/day. The ammonia concentration in a typical layer house was 2.4ppm on average and pealed at 4ppm. Ammonia generation was correlated with the temperature inside. The average total ammonia emitted was estimated to be 58.8g/day. The ammonia emission was higher in the summer and peaked at 156.7g/day. Generation of ammonia and airborne dust in layer houses was controlled by meteorological conditions, structural conditions, and air-conditioning to maintain a low temperature and low ventilation air volume.View full abstractDownload PDF (1065K) -
JUN Li, Keo INTABON, Yutaka ISHIKAWA, Yutaka KITAMURA, Hikaru HASIMOTO ...2008 Volume 38 Issue 4 Pages 285-292
Published: March 25, 2008
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSThe mixing of Poly lactic acid (PLA), an important biodegradable plastics with other materials is promising to develop new biodegradable composites. In this experiments, PLA was mixed to fine powder of sugarcane bagasse to produce a new kind of PLA-bagasse specimens. The effects of PLA addition on the mechanical characteristic, thermal resistance, biodegradability under soil conditions, and crystallization degree of PLA fraction were investigated. Economically, cost-down of the new specimens was also considered.
The addition of Bagasse enhanced the flexural modulus and flexural strength. The Distortion temperature under load (DTUL) of the specimens was also increased to the outstripped level of ABS in plastic. The addition of Bagasse also increased the crystallization degree on the specimens. Now, in regard to the biological degradability, the mass loss rate of the PLA-bagasse composite was higher than that of PLA in 30 days of incubation.
It is expected that the addition of bagasse into other bio-materials to develop new biodegradable composites might lead to economically use of higer price PLA.View full abstractDownload PDF (2736K) -
Yongyu LI, Keitaro SUZUKI, Yaohua HU, Kenichi OHTSUBO, Keo INTABON, Ta ...2008 Volume 38 Issue 4 Pages 293-299
Published: March 25, 2008
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSIn this study, two kinds of rice with a similar high amylose content, produced in Japan and China respectively, Yumetoiro and Zhongzao22hao, were used as materials for rice noodle. The endothermic property (Differential scanning calorimetry) of both rice flour and the dynamic viscoelastic property of their correspondent rice noodle, as well as cooking loss and cooking yield were discussed. The results showed that the gelatinized peak temperature (DSC) of Yumetoiro was approximately 16°C lower than that of Zhongzao22hao, and it can be inferred Zhongzao22hao has a stronger crystal structure than Yumetoiro. On the other hand, it is clear that according to the time dependence of the storage modulus and loss modulus, the retrogradation of rice noodle from Yumetoiro was later than that of rice noodle from Zhongzao22hao, and the rice noodle from Yumetoiro was more difficult to harden than that from Zhongzao22hao. The loss tangent of Yumetoiro noodle was less than that of Zhongzao22hao noodle, so it appears the Yumetoiro noodle has more contribution on elasticity than Zhongzao22hao noodle. Moreover, the cooking loss of rice noodle from Yumetoiro was significantly higher than that of rice noodle from Zhongzao22hao. From the point of the cooking process, Yumetoiro has disadvantages for producing rice noodles.View full abstractDownload PDF (847K)
- |<
- <
- 1
- >
- >|