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Volume 47 (2016)
- Issue 4 Pages 146-
- Issue 3 Pages 95-
- Issue 2 Pages 59-
- Issue 1 Pages 1-
Volume 47, Issue 4
Vol. 47, No. 4 (Ser. No. 151)
Displaying 1-3 of 3 articles from this issue
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Namseok KIM, Yasushi UEMATSU2016 Volume 47 Issue 4 Pages 146-155
Published: 2016
Released on J-STAGE: September 07, 2023
JOURNAL OPEN ACCESSThe purpose of the present study is to develop a new type of steel greenhouse with wing-like cross section, which has high wind resistance despite a long span. The concept of the development is based on a fact that the characteristics of wind loads on a structure strongly depend on the structure’s shape. First, a computational fluid dynamics (CFD) model suitable for the present study was established by comparing the CFD results with the experimental ones reported by Uematsu et al. (2004) for a steel greenhouse with wing-like cross section. Then, the effects of three parameters describing the wing-like cross section on the drag coefficient were investigated by a series of CFD analyses. Based on the results, together with a consideration for the workability inside the greenhouse, the most suitable cross section was proposed. Note that a two-dimensional model was used in this analysis. Finally, a wind tunnel experiment was carried out using a three-dimensional greenhouse model with the proposed cross section. The span and length of the model were assumed 20 m and 60 m, respectively. The experimental result on the wind pressure distribution was found to be in good agreement with the CFD result. Furthermore, the distribution of wind pressure coefficients on the model was investigated on the basis of the wind tunnel experiment.View full abstractDownload PDF (1930K) -
Hiroki UMEDA, Mami SUZUKI, Yasunaga IWASAKI, Seiji MATSUO, Toshiaki SU ...2016 Volume 47 Issue 4 Pages 156-161
Published: 2016
Released on J-STAGE: September 07, 2023
JOURNAL OPEN ACCESSTo develop an effective method for improving water use efficiency in a closed greenhouse environmental control system, we investigated the effects of air velocity on the growth and water use efficiency of cucumber seedlings under high relative humidity. Seedlings in closed plastic chambers were exposed to one of three air velocities in closed plastic chambers: 0 m s-1, 0.24 m s-1, or 0.66 m s-1. Dry weights of the cucumber seedlings in the 0.24 m s-1 and in 0.66 m s-1 air velocity treatments were higher than that of seedlings in the 0 m s-1 treatment. Seedlings subjected to an air velocity of 0.24 m s-1 was the highest among the treatments, at an average of RH 92.1 %. In addition, seedlings exposed to 0.24 m s-1 and 0.66 m s-1 winds had higher water use efficiencies than seedlings in the 0 m s-1 treatment. These results indicate that in a closed greenhouse environmental control system, controlling air velocity at high relative humidity makes it possible to increase the photosynthetic rate of seedlings while minimizing increases in water uptake.View full abstractDownload PDF (1027K) -
Takaaki SATAKE, Tohru HIJIKATA, Michikazu ICHIKAWA, Kazuhiro ODAKA, Os ...2016 Volume 47 Issue 4 Pages 162-170
Published: 2016
Released on J-STAGE: September 07, 2023
JOURNAL OPEN ACCESSThe genetic algorithm (GA) is a stochastic searching, learning and optimizing method for computer simulation. Utilizing GA, we have developed a basic simulator to find an optimum transportation route which can reduce transport cost of agricultural products. The simulator is coded by C language based on ANSI. It can find an optimum transportation route, given several parameters which are traffic volume, geographical information of passing through points, performance of delivery vehicle, etc. Two pairs of simulation experiments were designed and carried out : 1) traveling with empty load and delivery, 2) picking up cargo and delivering. As a result, the average fuel cost of the transportation route found by GA is considerably lower than the one obtained by random searching (RS) method in each simulation. On the other hand, the searched optimum transportation routes did not correspond between traveling picking up agricultural products and delivering, under the condition that each cargo quantity was same. These results lead us to the conclusion that our simulator is useful for searching an optimum transportation route and that the big cost cut in transportation of agricultural products is realized by combining GA and concrete transportation data about target agricultural products.View full abstractDownload PDF (1330K)
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