Masayuki Koike

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.

Several contributions to soil compactibility induced by cyclic loading test

Abstract To investigate the soil compactibility during the cyclic loading, three different kinds of paddy field soils were prepared so as to clarify interrelationships among stress amplitude ratio, bulk density, soil water content and pore water pressure. The presetting values of specimen include the soil water content(percent dry basis) and bulk density of 25% d.b. and 1.1 Mg/m 3 respectively. The relation between the number of cyclic loading and axial strain exhibited an asymptotically increasing trend, converging toward a specific value for each experimental condition. Possible effect caused by elastic–plastic characteristics could be recognized, when axial strain for 0.5 Hz excitation becomes greater than the one of 1.0 Hz under same stress amplitude ratio. When the stress amplitude ratio took 0.1, the absolute value of axial strain of 0.5 Hz was greater than the one of 1.0 Hz, whereas its decreasing trend was recognized in the sequence of silt, clay and silty sand. The qualitative relations between pore water pressure and number of cyclic loading were also examined to scrutinize the effect of effective water pressure to the soil compactibility.

Cyclic torsional shear loading test for an unsaturated, hollowed specimen using Bangkok clayey soil

Cyclic torsional shear loading was applied to simulate the loading characteristics which take place particularly during quick turning operations of a tractor in the field. Indoor experimental tests using a cyclic torsional shear loading method were conducted to clarify the dynamic behavior of Bangkok clayey soil. Since most agricultural soils in the field are normally unsaturated, this test method was used to better match field conditions. The dynamic behavior of our test soil was observed in conjunction with various factors including stress, strain, loading frequency, bulk density, moisture content, and number of loading cycles. Some related results were also obtained under static loading using a triaxial test method.

Truck allocation planning for cost reduction of mechanical sugarcane harvesting in Thailand: an application of multi-objective optimization

In Thailand, the chopper-type mechanical sugarcane harvester is widespread. This type of harvester usually operates with some trucks. When sufficient numbers of trucks are available, the chopper can carry out continuous harvest operation. However, there are not enough trucks in the surveyed region to cover the transportation needs. Hence, effective allocation planning of trucks is vital. By determining the optimum number of trucks needed for the sugarcane fields, it is possible to make efficient use of the chopper.

Triaxial force measurement at specific positions on a soil-cutting blade

Abstract In order to create a mathematical model of a soil-cutting blade, it is necessary to understand thoroughly the behavior of a soil slice and its interaction with the blade surface. The triaxial force transducer was developed to serve as one of the various tools to verify the proposed mathematical model. The prototype model transducer was fabricated, calibrated and tested with a soil slice on a flat cutting blade. The calibration results have indicated high sensitivity and the capability of simultaneous measurement in three directions. As a technological refinement, the detecting part of this triaxial force transducer was tapered to solve the problem of soil clogging in the opening clearance. Furthermore, the effects of the clearance configurations between the bore on the soil-cutting blade and the detecting part which is embedded in this bore were investigated to determine the most desirable configuration. The comparative results indicated that by tapering both the detecting part and the bore, the tangential stress measurement gained the highest value, and provided the most satisfactory condition for three-dimensional stress management.

Custom Hire Systems for Agricultural Machines in Southeast Asia — In a Rural Community in Thailand —

Abstract A distinctive feature analysis of custom hire systems is made in an attempt to clarify the process of technology acceptance in relation to demographic changes in mobility at the frontier in the western part of Thailand. Field surveys reveal that the mental component to agricultural mechanization varies from one community to another. There was a comprehensive settlement scheme at the study site around 40 years ago. Farmers suggested that a custom hire service would constitute a reliable tool for implementing specific farming practices and obtaining a reasonable income. To cope with the difficulties involved in securing a cheaper workforce and the necessary operating capital convinced the farmers that a professional custom hire business would be useful for achieving sustainable agriculture.

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.