Effects of Temperature, Relative Humidity, and Carbon Dioxide Concentration on Growth and Glucosinolate Content of Kale Grown in a Plant Factory

The growth of plants and their glucosinolate content largely depend on the cultivation environment; however, there are limited reports on the optimization of ambient environmental factors for kale grown in plant factories. This study was conducted to investigate the effects of temperature, relative humidity, and the carbon dioxide (CO2) concentration on kale growth and glucosinolate content in different growth stages of cultivation in a plant factory. Kale was grown under different temperatures (14, 17, 20, 23, and 26 °C), relative humidities (45, 55, 65, 75, and 85%), and CO2 concentrations (400, 700, 1000, 1300, and 1600 ppm) in a plant factory. Two and four weeks after transplantation, leaf samples were collected to evaluate the physical growth and glucosinolate contents. The statistical significance of the treatment effects was determined by two-way analysis of variance, and Duncan’s multiple range test was used to compare the means. A correlation matrix was constructed to show possible linear trends among the dependent variables. The observed optimal temperature, relative humidity, and CO2 range for growth (20–23 °C, 85%, and 700–1000 ppm) and total glucosinolate content (14–17 °C, 55–75%, and 1300–1600 ppm) were different. Furthermore, the glucosinolate content in kale decreased with the increase of temperature and relative humidity levels, and increased with the increase of CO2 concentration. Most of the physical growth variables showed strong positive correlations with each other but negative correlations with glucosinolate components. The findings of this study could be used by growers to maintain optimum environmental conditions for the better growth and production of glucosinolate-rich kale leaves in protected cultivation facilities

Vibration Assessment of a 12-kW Self-Propelled Riding-Type Automatic Onion Transplanter for Transplanting Performance and Operator Comfort

Vibration assessment of upland crop machinery under development is essential because high vibrational exposures affect machine efficiency, service life of components, degradation of the working environment, and cause health risks to the operator. It is intensively assessed for automobiles as well as large off-road agricultural vehicles (i.e., tractors). However, it is mostly overlooked in the case of the small or medium riding-type upland utility vehicles. Therefore, the vibration exposures of a 12-kilowatt self-propelled riding-type automatic onion transplanter were measured and evaluated to assess the performance of onion transplantation and the operator’s comfort in this study. Different types of driving surfaces, operating statuses (static and driving), and load conditions were considered to analyze the vibration exposure. The precision of transplantations was evaluated while operating the transplanter on the soil surface with different driving speeds and load conditions. Tri-axial accelerometers and a LabVIEW-coded program were used for data acquisition. The vibrational exposures were evaluated based on ISO standards, and power spectral density (PSD) was estimated to assess the major frequencies. According to the statistical analysis, the daily exposure value (A(8)) and the vibration dose value (VDV) varied from 10 to 15 ms−2 and 20 to 31 ms−1.75, respectively, which exceeded the ISO 2631-1 standards (i.e., A(8): 1.15 ms−2 and VDV: 21 ms−1.75). The calculated health risk factor (RA) was moderate. Moreover, a high weighted acceleration (around 8 ms−2) was observed on the seedling conveyor belt, which might result in missing seedlings during transplanting. The vibration exposures of the developed onion transplanter need to be minimized following the ISO standards, and vibration reduction would also improve the market competitiveness

Stress and Fatigue Analysis of Picking Device Gears for a 2.6 kW Automatic Pepper Transplanter

A seedling picking device is an essential component for an automatic transplanter to automatically convey the seedling to the dibbling part. It is necessary to find the appropriate material and dimensions for the picking device gears to avoid mechanical damage and increase their durability. Therefore, the objectives of this research were to analyze the stress of a picking device gear mechanism in order to select suitable materials and dimensions, and to predict the fatigue life by considering the damage level. The picking device gear shaft divided the input power into two categories, i.e., crank and cam gear sets. Finite element analysis simulation and American Gear Manufacturers Association standard stress analysis theory tests were conducted on both of the crank and cam gear sets for different materials and dimensions. A test bench was fabricated to collect the load (torque) data at different gear operating speeds. The torque data were analyzed using the load duration distribution method to observe the cyclic load patterns. The Palmgren–Miner cumulative damage rule was used to determine the damage level of the picking mechanism gears with respect to the operating speed. The desired lifespan of the transplanter was 255 h to meet the real field service life requirement. Predicted fatigue life range of the picking mechanism gears was recorded as from 436.65 to 4635.97 h, making it higher (by approximately 2 to 18 times) than the lifespan of the transplanter. According to the analyses, the “Steel Composite Material 420H carbon steel” material with a 5 mm face width gear was suitable to operate the picking device for a 10-year transplanter service life. The analysis of stress and fatigue presented in this study will guide the design of picking device gears with effective material properties to maintain the recommended service life of the pepper transplanter

Vibration Assessment of a 12-kW Self-Propelled Riding-Type Automatic Onion Transplanter for Transplanting Performance and Operator Comfort

Vibration assessment of upland crop machinery under development is essential because high vibrational exposures affect machine efficiency, service life of components, degradation of the working environment, and cause health risks to the operator. It is intensively assessed for automobiles as well as large off-road agricultural vehicles (i.e., tractors). However, it is mostly overlooked in the case of the small or medium riding-type upland utility vehicles. Therefore, the vibration exposures of a 12-kilowatt self-propelled riding-type automatic onion transplanter were measured and evaluated to assess the performance of onion transplantation and the operator’s comfort in this study. Different types of driving surfaces, operating statuses (static and driving), and load conditions were considered to analyze the vibration exposure. The precision of transplantations was evaluated while operating the transplanter on the soil surface with different driving speeds and load conditions. Tri-axial accelerometers and a LabVIEW-coded program were used for data acquisition. The vibrational exposures were evaluated based on ISO standards, and power spectral density (PSD) was estimated to assess the major frequencies. According to the statistical analysis, the daily exposure value (A(8)) and the vibration dose value (VDV) varied from 10 to 15 ms−2 and 20 to 31 ms−1.75, respectively, which exceeded the ISO 2631-1 standards (i.e., A(8): 1.15 ms−2 and VDV: 21 ms−1.75). The calculated health risk factor (RA) was moderate. Moreover, a high weighted acceleration (around 8 ms−2) was observed on the seedling conveyor belt, which might result in missing seedlings during transplanting. The vibration exposures of the developed onion transplanter need to be minimized following the ISO standards, and vibration reduction would also improve the market competitiveness