Shotaro Yuzawa

Prediction of soil reaction forces on a moldboard plow surface

Abstract Using mathematical models, approximate trajectories of soil furrow subslices were determined and the forces occurring on the moldboard surface were calculated. The various components of the normal force along the trajectory line of the middle section of the furrow slice were analysed in relation to the velocity of plowing operation and the curvature of the path. The soil reaction forces encountered by the share portion of the plow were also determined by a model which used the method of trial wedges to determine the angle of the failure surface with the horizontal. The sum of the calculated forces was compared with that obtained by actual plowing experiments performed in the laboratory.

Compaction characteristics for the towed and driven conditions of a wheel operating in an agricultural soil

Abstract High axle loads, duration of strain as well as strain rate due to applied stresses, and field moisture condition have been found to contribute to compaction in the field. Numerous previous investigations on agricultural soil compaction were carried out with relatively dry soil. The aim of this study was to investigate the interrelationships between compaction, applied load, vehicle speed and a certain practical range of soil moisture content through a soil bin investigation of the compaction which results from the passage of a towed and a driven wheel. Soil pressure and the corresponding bulk density were analysed using a model proposed by Bailey et al. ( J. agric Engng Res. 33 , 257–262 (1986)) and ANOVA techniques. The results showed that compaction was higher at the higher moisture content level for both towed and driven conditions of the wheel, and that it was applied load that had the greatest contributory effect. Also, compaction was higher in the case of the driven wheel as compared to the towed wheel due to the phenomenon of slip sinkage. Baileys model, it appears, can be utilized in the field for a practical estimation of compaction resulting from the passage of a towed wheel.

A model to determine the trajectory of soil motion on a moldbroad plow surface

Abstract A mathematical model was developed to determine the soil trajectory of motion on the moldboard plow surface. With the use of the model, trajectory lines of soil particle travel were calculated based on the shape of the moldboard plow surface. Also, with the use of the values of soil properties, soil-metal coefficient of friction, the travel speed of plow and the soil modulus of elasticity, equations of forces were solved for equilibrium condition of the furrow slice passing over the moldboard surface. The use of the model can be xtended to the approximation of the soil reaction forces occurring the plowing operation. Laboratory experiments were conducted to verify the validity of the model. the moldboard shape factors used were derived from the coordinates of points describing the contours of the plow surface as measured by a profilograph.

Basic studies on the application of fuzzy theory to farm work planning. II. Presumption of field capacity by using fuzzy inference.

In the last several years, some expert systems for agriculture have been developed.However, these present systems cannot yet deal with imprecise or uncertain information such as “fairly long working hours”. An experienced farmer often tends to use words rather than numbers to describe his knowledge.In this study, fuzzy inference was employed in order to presume field capacity from if-then rules represented by farmers language.Membership functions of daily working hours and daily field capacity were determined by the answers of the questionarie on the puddling. Fuzzy production rules were made up by using these membership functions.Fuzzy inference was applied to the presumption of field capacity and its effectiveness to agricultural information processing was discussed in this paper.