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I work for Department of Life and Environmental Agricultural Sciences, Tottori University. Current research subject: 1) Technical, Economic, and Environmental assessment and optimum design of photovoltaic and wind power system for food production in drylands , such as aquaponics, solar pumping . 2) Development of wind turbine techniques applied to desert environment and cold climate.
In hydroponics, the flow pattern of nutrient solution in a cultivation container affects the growth of plants. Even if the flow rate of nutrient solution is the same between containers, the flow pattern may differ based on the size and shape of the containers. Therefore, the flow pattern cannot be comprehensively described by flow rate alone. In order to identify the relationship between plant growth, root morphology, nutrient uptake, and flow pattern, a hydroponic cultivation of Swiss chard was carried out. In addition, in order to describe the flow pattern in a specific cultivation container, hydroponic flow patterns were observed via flow field visualization using particle image velocimetry. As a result, with the increase in flow rate, it was found that a specific flow rate can form an ideal flow pattern for plant growth. Under this flow pattern, nutrient absorption is promoted and roots are elongated, thereby absorbing more nutrients and further promoting plant growth. However, when the flow rate exceeds the ideal value, plant growth is hindered. In summary, identifying the ideal nutrient solution flow pattern in hydroponics can facilitate better crop production.
Bateer Baiyin; Kotaro Tagawa; Mina Yamada; Xinyan Wang; Satoshi Yamada; Sadahiro Yamamoto; Yasuomi Ibaraki. Effect of the Flow Rate on Plant Growth and Flow Visualization of Nutrient Solution in Hydroponics. Horticulturae 2021, 7, 225 .
AMA StyleBateer Baiyin, Kotaro Tagawa, Mina Yamada, Xinyan Wang, Satoshi Yamada, Sadahiro Yamamoto, Yasuomi Ibaraki. Effect of the Flow Rate on Plant Growth and Flow Visualization of Nutrient Solution in Hydroponics. Horticulturae. 2021; 7 (8):225.
Chicago/Turabian StyleBateer Baiyin; Kotaro Tagawa; Mina Yamada; Xinyan Wang; Satoshi Yamada; Sadahiro Yamamoto; Yasuomi Ibaraki. 2021. "Effect of the Flow Rate on Plant Growth and Flow Visualization of Nutrient Solution in Hydroponics." Horticulturae 7, no. 8: 225.
For the wind turbines installed in the cold and humid regions, icing accretion on the blade surface seriously degrades its performance. The Straight-Bladed Vertical Axis Wind Turbine (SB-VAWT) is also troubled by the problem. For exploring the characteristics of icing, the icing wind tunnel tests have been carried out in this paper. An icing wind tunnel experimental system is designed and fabricated. The experimental parameters in the icing wind tunnel system are measured. A rotor test stand with two blades of NACA0018 airfoil is designed and amounted in the icing wind tunnel. The icing test is conducted under the different tip speed ratios and the rime ice condition. The experimental results show that the rotational speed of the blade has significant effects on the characteristics of icing. When the tip speed ratio is lower than 1, the ice layer covers in the whole blade surface and grows layer by layer. As the tip speed ratio is higher than 1, the ice layer mainly concentrates in the vicinity of the leading edge. Three factors, which are the relative angle of attack, the rotational position of blade and the centrifugal force, influencing on the characteristics of icing are analyzed and discussed.
Wenfeng Guo; He Shen; Yan Li; Fang Feng; Kotaro Tagawa. Wind tunnel tests of the rime icing characteristics of a straight-bladed vertical axis wind turbine. Renewable Energy 2021, 179, 116 -132.
AMA StyleWenfeng Guo, He Shen, Yan Li, Fang Feng, Kotaro Tagawa. Wind tunnel tests of the rime icing characteristics of a straight-bladed vertical axis wind turbine. Renewable Energy. 2021; 179 ():116-132.
Chicago/Turabian StyleWenfeng Guo; He Shen; Yan Li; Fang Feng; Kotaro Tagawa. 2021. "Wind tunnel tests of the rime icing characteristics of a straight-bladed vertical axis wind turbine." Renewable Energy 179, no. : 116-132.
An open-field cultivation combined-type aquaponic system (OCAS) was developed to effectively utilize saline groundwater and prevent soil salinization while ensuring food production in drylands. To achieve the sustainable food production of the OCAS in power-scarce areas, a stand-alone photovoltaic system (PVS) for the OCAS was designed through a feasibility study of utilizing solar energy to meet its power demand. As a case study, the OCAS was established in La Paz, Baja California Sur, Mexico, with power consumption 22.72 kWh/day and annual average daily global horizontal irradiation (GHI) 6.12 kWh/m2/day, considering the 2017 meteorological data. HOMER software was employed for performance analysis and techno-economic evaluation of an appropriate PVS. Thousands PVS configurations were evaluated in terms of total net present cost (NPC) and levelized cost of energy (COE). The PVS that fulfilled the power demand and had the smallest NPC was proposed, for which the NPC and COE were calculated as $46,993 and $0.438/kWh, respectively. The relationship between its annual power supply and power demand of the OCAS was also analyzed in detail. It was found that the operation hours and the amount of power generation by the proposed PVS were 4156 h and 19,106 kWh in one year. Additionally, it was predicted that the excess power would occur almost every afternoon and reach 43% of the generated power. Therefore, the COE can be further reduced by rationally utilizing the excess power during operation.
Bateer Baiyin; Kotaro Tagawa; Joaquin Gutierrez. Techno-Economic Feasibility Analysis of a Stand-Alone Photovoltaic System for Combined Aquaponics on Drylands. Sustainability 2020, 12, 9556 .
AMA StyleBateer Baiyin, Kotaro Tagawa, Joaquin Gutierrez. Techno-Economic Feasibility Analysis of a Stand-Alone Photovoltaic System for Combined Aquaponics on Drylands. Sustainability. 2020; 12 (22):9556.
Chicago/Turabian StyleBateer Baiyin; Kotaro Tagawa; Joaquin Gutierrez. 2020. "Techno-Economic Feasibility Analysis of a Stand-Alone Photovoltaic System for Combined Aquaponics on Drylands." Sustainability 12, no. 22: 9556.
Water resource issues are a challenging area of research in semiarid regions of the world. The objective of the current study was to reveal the main characteristics of seasonal surface runoff for the semiarid western Heilongjiang Province of China. The Alun River Basin, which has hydrological and meteorological characteristics of the local region, was adopted as the study location. A distributed rainfall-runoff combined with snowmelt hydrological model was used to carry out the runoff calculation for the six years (2011–2016). The results indicated that: The mean annual runoff coefficient was 0.34; snowmelt runoff accounted for 2.2% of annual total runoff in 2011–2016; the main part of annual rainfall and runoff was concentrated in the rainy season from June to September, the proportions of rainfall and runoff in this period were 78% and 86% to that of the annual means of 2011–2016; the peak flow represents a decreased trend since 2013, and evidently decreased in 2015 and 2016; less annual precipitation complex with paddy field retention of rainwater and runoff led to the peak flow and annual runoff coefficient in 2016 were obviously lower than that of annual means of 2011–2016. The results are expected to provide the basis for rational development and utilization of surface runoff, and further researches on surface runoff and water resources of the semiarid western Heilongjiang Province of China.
Jinbai Huang; Kotaro Tagawa; Bin Wang; Jiawei Wen; Jingcai Wang. Seasonal Surface Runoff Characteristics in the Semiarid Region of Western Heilongjiang Province in Northeast China—A Case of the Alun River Basin. Water 2019, 11, 557 .
AMA StyleJinbai Huang, Kotaro Tagawa, Bin Wang, Jiawei Wen, Jingcai Wang. Seasonal Surface Runoff Characteristics in the Semiarid Region of Western Heilongjiang Province in Northeast China—A Case of the Alun River Basin. Water. 2019; 11 (3):557.
Chicago/Turabian StyleJinbai Huang; Kotaro Tagawa; Bin Wang; Jiawei Wen; Jingcai Wang. 2019. "Seasonal Surface Runoff Characteristics in the Semiarid Region of Western Heilongjiang Province in Northeast China—A Case of the Alun River Basin." Water 11, no. 3: 557.
Kotaro Tagawa; Xinyan Wang; Bateer Baiyin. Feasibility Study on Small Scale Food Production Using Off-Grid Photovoltaic Water Pumping System in Coastal Dune. Advancements in Civil Engineering & Technology 2018, 1, 1 -2.
AMA StyleKotaro Tagawa, Xinyan Wang, Bateer Baiyin. Feasibility Study on Small Scale Food Production Using Off-Grid Photovoltaic Water Pumping System in Coastal Dune. Advancements in Civil Engineering & Technology. 2018; 1 (5):1-2.
Chicago/Turabian StyleKotaro Tagawa; Xinyan Wang; Bateer Baiyin. 2018. "Feasibility Study on Small Scale Food Production Using Off-Grid Photovoltaic Water Pumping System in Coastal Dune." Advancements in Civil Engineering & Technology 1, no. 5: 1-2.
Based on a concept of “cost reduction by large rotor and small generator”, a kind of small vertical axis wind turbine (VAWT) called a butterfly wind turbine (BWT) has been developed with rotor diameter of 7 m and five looped blades. One of the features is a mechanical system which can twist each blade of a VAWT by using the centrifugal force acting on the blades in order to prevent over-speeding of the rotor. An electric power generation system that combines the BWT utilizing the over-speed control system (OCS) with a coreless generator connected to a three-time increasing gear unit is constructed in this study. The performance of the BWT power-generation system is predicted by the blade element momentum (BEM) theory. The final goal of this research is to show the feasibility of the low-cost VAWT power generation system with the proposed OCS. From the results of a series of forcible rotation experiments of the BWT rotor that is driven by an induction motor in very low wind speed condition, it is shown that the twist movement of the blades is improved by the design of the OCS that considers the observed radial force deprived of the centrifugal force and the pre-compression of springs. In the generation experiments with the final design of the OCS, the expected twists of the blades are observed for the first time in strong natural wind speed over 18 m/s.
Yutaka Hara; Kotaro Tagawa; Shigenori Saito; Keisuke Shioya; Takeshi Ono; Kenji Makino; Kazutoshi Toba; Takakazu Hirobayashi; Yousuke Tanaka; Kazuo Takashima; Susumu Sasaki; Kengo Nojima; Shigeo Yoshida. Development of a Butterfly Wind Turbine with Mechanical Over-Speed Control System. Designs 2018, 2, 17 .
AMA StyleYutaka Hara, Kotaro Tagawa, Shigenori Saito, Keisuke Shioya, Takeshi Ono, Kenji Makino, Kazutoshi Toba, Takakazu Hirobayashi, Yousuke Tanaka, Kazuo Takashima, Susumu Sasaki, Kengo Nojima, Shigeo Yoshida. Development of a Butterfly Wind Turbine with Mechanical Over-Speed Control System. Designs. 2018; 2 (2):17.
Chicago/Turabian StyleYutaka Hara; Kotaro Tagawa; Shigenori Saito; Keisuke Shioya; Takeshi Ono; Kenji Makino; Kazutoshi Toba; Takakazu Hirobayashi; Yousuke Tanaka; Kazuo Takashima; Susumu Sasaki; Kengo Nojima; Shigeo Yoshida. 2018. "Development of a Butterfly Wind Turbine with Mechanical Over-Speed Control System." Designs 2, no. 2: 17.
Yan Li; Kotaro Tagawa; Fang Feng; Qiang Li; Qingbin He. A wind tunnel experimental study of icing on wind turbine blade airfoil. Energy Conversion and Management 2014, 85, 591 -595.
AMA StyleYan Li, Kotaro Tagawa, Fang Feng, Qiang Li, Qingbin He. A wind tunnel experimental study of icing on wind turbine blade airfoil. Energy Conversion and Management. 2014; 85 ():591-595.
Chicago/Turabian StyleYan Li; Kotaro Tagawa; Fang Feng; Qiang Li; Qingbin He. 2014. "A wind tunnel experimental study of icing on wind turbine blade airfoil." Energy Conversion and Management 85, no. : 591-595.