We studied a test method to minimize the effects of the environmental test conditions on the engine performance and conduct a fairer test. In this report, we investigated the effects of the fuel temperature and the atmospheric factor calculated on the basis of the dry atmospheric pressure and intake air temperature on the engine performance and emission gases in naturally aspirated diesel engines. As a result, it was clarified that differences in the atmospheric factor influence the test results for the engine power, specific fuel consumption, particulate matter, nitrogen oxide and carbon monoxide. There is a possibility of reducing the variations in the test results by maintaining constant atmospheric factors. Therefore, it is necessary to research this possibility.

We have developed a vertical displacement reduction device that consists of two single-acting hydraulic cylinders, an accumulator, and a valve block, among other components. This device is used to replace existing hydraulic cylinders to simultaneously reduce the vertical displacement input from both sides’ wheels. Obstacle driving tests (a riding test for both sides’ wheels and a right-side-wheel riding test) and field tests (in a Kagoshima rice paddy and in a field after a wheat harvest in Hokkaido) were performed. The performance of the proposed device was evaluated by conducting these tests. The following results were obtained: Boom vertical oscillation was reduced by approximately 65% in the riding test for both sides’ wheels and was reduced by approximately 36% in the field after the wheat harvest. However, this device cannot reduce the vertical displacement caused by body roll; an additional device is needed for this.

To reduce labor costs involved in the transportation of a harvesting containers in a large-scale greenhouse for tomato cultivation, we developed an unmanned harvesting container transport system consisting of a collecting device, transport vehicle, and storage device. The vehicle can travel along a magnetic tape on the floor, and each device has a plastic conveyor. Containers are delivered by inclining the conveyors in the collecting device and in the vehicle. In a cultivation area of 1 ha, the process time for transporting 5 t of tomatoes was estimated to be 4.4-7.5h. Although the acceleration of the container transportation reached a maximum of 6.9m/s², the cushioning material at the bottom of the containers prevented damage to the tomatoes.

The objective of the present study was to develop a device that will enable quick and simple measurement of water stress of the Satsuma mandarin (Citrus Unshiu Marcow), in order to improve appropriate irrigation, which is necessary for the stable production of high-quality fruit. By adopting a method of estimating water potential from the Young’s modulus of leaves to serve as an index for water stress, we developed a portable device for measuring water status of Satsuma mandarin trees that can be used to take measurements of the Young’s modulus easily at the cultivation site. The developed device performs measurement operations automatically, and by using the Young’s modulus to estimate the water potential information on water status of the tree is obtained. The results of performance testing showed that the Young’s modulus and the water potential measured by the pressure chamber had a correlation coefficient of 0.81.

We modified a combine cutter to macerate rice straw by replacing the cutting wheel of the combine cutter with a rotor having no cutting function. We observed that macerated rice straw dried faster than non-treated rice straw in the early drying stage. In a paddy-field test, the moisture content of the macerated rice straw was reduced to a suitable value for preservation more quickly than the non-treated straw, even with rainfall during the test. The reduction rate of the moisture content of the rice straw was increased by turning its windrow upside down using a swath conditioner once per day. The power required by the macerating equipment was ∼60% of that required for cutting.

We constructed a preparation system that can process ensiled rice continuously and examined the system’s work efficiency, the number of staff required and the preparation cost in case of using a dedicated rice-crushing machine or a husk-processing machine. Three workers could perform all processes continuously on our preparation system with a husk-processing machine (3.5t/h efficiency). When the deaeration and sealing process was postponed, two workers could perform continuously. Assuming that the preparation cost of a drying process is 25 yen per kg, the ensiling process can reduce the cost by managing a paddy area more than 5.1 hectares with a dedicated rice-crushing machine (0.9t/h efficiency) or more than 9.3 hectares with a husk-processing machine (3.0t/h efficiency).

In a previous paper, we reported on the performance of a device developed for rice seed disinfection. To treat the rice seed such that its temperature after heating (T_fin) is 75±1°C，the device elicits a control effect equivalent to or more effective than the conventional hot water treatment against rice seed-borne diseases, and without the negative effect of excess heat on seed germination. In this study, we aimed to develop a process control method for T_fin using Predictive Functional Control. In particular, we aimed to calibrate and validate a prediction model for T_fin using the process conditions of the device. We created a multiple linear regression model to predict T_fin, which uses gas humidity, heating time, and other process conditions as predictor variables. The model can predict T_fin within the standard error of 0.5°C in the range of 66.0 to 82.7°C. This result indicates that it is possible to apply the model for device operation and control.