This paper presents summary results of analytical discussions of steering control system model of tractor determined by experimental method.
The differential element of the model H₁(s) put out the front wheel angle multiplied the travel speed of tractor. To obtain the optimal response, the gain constant K₁ of steering control operation is required to vary inversely with the travel speed in case of the model H₁(s) and with the forecast length in case of the model H₂(s). The stable region depends on the open loop gain K and the forecast time T₂ in the model H₂(s), but it can be controlled by the first order lag time T₁ in the model H₁(s).
The applicable ranges for the two models to obtain the optimal response are different with the travel speed. The model H₂(s) has an upper limit of travel speed and beyond the limit the range for H₁(s) can be applied.

View full abstract

This paper describes a theoretical analysis of stationary turning motion of the tracked vehicles on level soft ground.
In developing the equations of stationary turning motion on soft ground, we intend to take into account factors concerning steering problems such as the track slip-sinkage and plowing, the distribution of normal and shear stresses beneath the track shoe under the road wheel, the load transfer due to track tensions and vehicle structure, namely, vehicle weight, nominal track contact length, vehicle tread, track contact width, number of road wheel, etc.
These equations have been numerically solved on a digital computer. The results are summarized as follows;
(1) The specific slip radii of tracks increase rapidly with the increase of steering ratio ε, however, beyound ε=1.3 they are almost constant.
(2) Both the driving and braking forces increase with the increase of steering ratio ε, and then, they become almost constant.
(3) The sinkages of tracks are related to steering ratio ε. The sinkage of inner track increases proportionally to steering ratio ε, while the sinkage of outer track increases gradually with ε.
(4) The accurately computed value of turning radius is approximately 1.7 times larger than the calculated value based on a simple geometrical relation which neglects the effects of longnitudinal track slippages.

View full abstract

In order to obtain the data on the design and utilization of rotary mowers, an apparatus of measuring cutting energy was made for trial. The effects of the cutting energy on the bevel angle of knife, the cutting speed and the diameter of pasture stalk were investigated. After the rotary knife cut off the pasture, the speed and energy of rotation went down. Then the equation of the cutting energy was set up as follows.
Cutting energy E=1/2I (ω_2n²-ω₂²)
I; Moment of inertia of the shaft with rotary knife
ω_2n; Angular velocity in case of no load
ω_2; Angular velocity after cutting
The results of experiments are summarized as follows.
1) Analyzing the variance of the results of experiments, the significant difference at 1 percent level was recognized in the bevel angle of knife, the cutting speed and the diameter pasture stalk.
2) The relation between the bevel angle and the cutting energy became a cubic function. As the bevel angle became smaller than 23deg., the cutting energy decreased rapidly. As the angle became bigger than 45deg., the cutting energy increased rapidly.
3) The relation between the cutting speed and the cutting energy became the quadratic function. As the cutting speed became faster than about 40m/s, or slower than about 20m/s, the cutting energy increased. When the bevel angle was large, or stalk was thick, this relation became more clearly.
4) The relation between the diameter of stalk and the cutting energy became a linear function. As the cutting speed was rather slow the effect of stalk diameter on the cutting energy was remarkable.

View full abstract

Soil factors affecting the pulling force of root vegetables were investigated. The effects of soil factors on friction and shear resistance were analyzed on the assumption that the soil resistance with the pulling of root vegetables was the sum of the friction and the shear resistance of soil around the main root (Fig. 1).
The process of analyses were as follows. (1) Adhesion and cohesion were approximated to friction and shear resistance respectively on the hypothesis that the normal stress of soil on the surface of main root was 0 (Fig. 2). (2) It was presumed that adhesion and cohesion were affected by soil properties, soil moisture content and penetrating resistance (Fig. 3).
The effect of adhesion and cohesion on the pulling force or pulling resistance was investigated, changing soil moisture content and penetrating resistance independently, in the small artificial fields. The results of experiments were as follows.
(1) The pulling force increased with the increasing soil moisture content and penetrating resistance (Fig. 5). (2) High correlations were observed between the pulling force and adhesion or cohesion (Fig. 6, 7). These results indicated that the adhesion and the cohesion on the pulling force were affected by soil properties, soil moisture content and penetrating resistance.
From this investigation our previous assumption that the most important soil factors affecting the pulling force of root vegetables would be soil moisture content and penetrating resistance (FURUYA, in print) developed more favourably for us. According to our new assumption the important soil factors affecting the pulling force of root vegatebles were systematic series of effective factors: soil properties·soil moisture content·penetrating resistance →adhesion·cohesion→pulling resistance.

View full abstract

An old-type leaf-stripping machine have been operated in the field but has a limited work efficiency.
This paper describes a new-type trial leaf-stripping unit for sugar cane. Topped green canes were carried to a sugar mill and then stripped collectively by this unit which was designed to have a work efficiency of 15ton/hr and 2% trash.
The stripping performance of this unit was evaluated. The results obtained are as follows.
1) The leaf-stripping efficiency was 14.6ton/hr which nearly approached the target of 15ton/hr. This value was larger by 20-30 times than the value obtained by manual operation.
2) Trash ratio was 6.2% at the 1st blower and 2.3% at the 2nd blower which took the last process of the leaf stripping.
3) The sum of cane losses both at the 1st and 2nd leaf-strippers was 0.23%.
4) Bruises on the cuticle of the cane caused by impact force of the chain were observed, but these bruises gave only an insignificant influence on the quality of the cane because the cane was stripped and processed within short time by this unit.
5) The leaf stripping cost by this unit was about 2770yen/ton which was the decrease of approximately 26% compared with the manual operation.
These results lead to the conclusion that the performance of this new-type unit is generally satisfactory but it will need further examination of the durability for practical use.

View full abstract

For the purpose of processing mechanization of Baker's garlic after harvest, an experimental processing device was designed and built for a trial. The results of the test run showed the advantage of the safety, the elimination of cutting work of roots and stalks and the decrease of mental stress. However, the efficiency and accuracy using the processing device are still not satisfactory comparing with the conventional method. Some of the problems are pointed out as follows.
1. It is desirable to change the cutting length of processing device following the change of the bulb diameter of Baker's garlic.
2. As the acceptable cutting range of the root's side is very narrow, 0.7-0.9mm, the positioning of Baker's garlic is better to be made by deciding the cutting point from the root's side. It is further necessary to improve the guide plate of the processing device to know the exact point of cutting at the time positioning the Baker's garlic.
3. Furthermore, the experimental processing device must be improved for more efficiency and accuracy in regard to the optimum velocity of clip, the distance between each clips, the moving direction of the clips and the operation of normal working area.

View full abstract

To study the drying characteristics of beef samples during freeze-drying process using a radiant heating, experiments were carried out at different sample surface temperatures with the freeze-drying apparatus reported in reference (2). The results obtained from these experiments and drying conditions were summarized as follows.
1. Schematic diagram of the radiant heating apparatus and the conditions of sample surface temperatares were shown in Fig. 1 and Table 1, respectively.
2. Experimental data were obtained in relation to the drying characteristics of the sample tested and the corresponding operating conditions during drying processes. The former consisted of the change in sample weight, calculated drying rate and sample temperatures while the latter included the heater and condenser surface temperatures as well as the total pressure in vacuum chamber. A result obtained for the sample number 15 was shown in Fig. 4. The changes in moisture contents, dimensions and densities of raw and dry samples, and the thermal conductivities of the dried region during 1st drying period (sublimation drying period) were presented in Table 2. The mathematical model (Fig. 3) proposed by Massey and Sunderland (1967) was used to measure the thermal conductivities. Typical sample weight and drying rate curves at various temperature conditions were shown in Fig. 5 and Fig. 6, respectively.
3. The equilibrium moisture contents (E. M. C.) were defined as the moisture contents of dry samples to the chamber pressures and the specimen temperatures at the end of drying process. The plots of E. M. C. against the specimen temperatures at the total pressure 0.31-0.57torr were shown in Fig. 7.
The maximum and minimum value of the E. M. C. were 5.3% w. b., 1.2% w. b., respectively. Rather great differences of the E. M. C. in low temperature range were attributed to the differences in the 2nd drying time.
4. Thermal conductivities of the dried region vs. the sample temperatures relationships were shown in Fig. 8. The results of this study obtained at the total pressure of 0.31-1.5torr were consistent with that reported by Massey and Sunderland, who had reported the conductivity of 0.055-0.075kcal/(mh°C) at 0.2-1.0torr. There was no evident effect of temperature level as indicated by Triebs et al. (1966), however, the thermal conductivity had tendency to decreace with the surface temperature over 60°C. This effect was interpreted in terms of the scorching of sample surface. The thermal conductivity in a direction perpendicular to the grain was substantially less than that parallel to the grain.

View full abstract

A method of analysing deep bed drying of rough rice was devised combining the drying characteristics of a single rough rice and the forced air drying theory of granular bed presented by previous reserchers such as Van Meel and Toei in the field of chemical engineering.
The results obtained were as follows.
1) The equilibrium moisture content of a single grain of rough rice was expressed by equation (16).
2) When the drying characteristics were approximated to a straight line as oba'd in Fig. 3, the drying constant was expressed by equation (17).
3) The equations (11)-(14) of forced air drying theory could be used for the practical drying analysis with sufficient accuracy.
4) The dimensional equations (21)-(24) derived from the dimensionless equations (11)-(14) provided a easier calculating procedure.
5) In practical situation, the coefficicnt (γ) of effective surface area of bulk was in a range of 0.8-0.85.
6) Calculated results could not explain the delay of drying by latent heat of bulk and the large drying rate of early drying period which appeared when air volume was extremely large.

View full abstract

This study was conducted to know physical properties of animal waste by measuring distribution of particle diameter and sedimentation rate in slurry. The experiment was carried out on pig slurry and other cattle slurry. Distribution of particle diameter was measured by combining sieve analysis and microscopy. Distribution of sedimentation rate was measured by Andreasen pipette method and centrifugal sedimentation method. Experimental results from two methods were shown together.
Particle density of animal waste was estimated by the authors.
The results obtained from these experiments are summarized as follows.
1) Distribution of sedimentation rate for animal waste was measured by combining Andreasen pipette method and centrifugal sedimentation method. Distribution of particle diameter was measured by means of sieve analysis and microscopy. These methods were relatively simple and accurate and applicable over broad range.
2) It converted sedimentation rate in centrifugall force field into sedimentation rate Umg ((4) equation) in gravity field. Distribution of sedimentation rate and particle diameter obtained from different methods was expressed uniformly all over the measurement range.
3) The rate (1-K) of observed dissolution in animal waste was obtained from the asymptotic value K of distribution curve of residue on sedimenvation rate. It was about 10% for pig slurry and about 13% for cattle slurry.
4) Distribution of sedimentation rate for animal waste was found that the distribution curve for residue showed two step downward curve as shown in Fig. 4 and Fig. 5 and the distribution ranges were similar. Mean sedimentation rate was 0.1370cm/sec. for pig slurry and 0.0924cm/sec for cattle slurry.
5) As shown in Fig. 6 and Fig. 7, the distribution of particle diameter of animal waste showed that the distribution curve of residue was two step downward curve and touched the horizontal axis at R=0. Concentration to the small particle diameter for cattle slurry was more remarkable than for pig slurry. Mean particle diameter was 665μ for pig slurry and 458μ for cattle slurry.
6) By applying Rosin-Rammler distribution function with K as asymptotic value to distribution of sedimentation rate and particle diameter of animal waste, the coefficients n, b and standard deviation were calculated as shown in Table 3.
7) Particle density ρ_s of animal waste in saturation state was obtained from the distribution of sedimentation rate and the particle diameter of the same sample, and the relation between ρ_s and the particle diameter was shown in Fig. 8 and Fig. 9. The value ρ_s of pig slurry had a small difference from solvent density ρ₁ and almost uniform through all the particle range. The value ρ_s of cattle slurry was somewhat larger for middle size particles of about 50μ.

View full abstract

In the previous paper, a formulation of crop production was made, assuming that it was an optimal control problems of distributed parameter systems.
This paper is dealing with solving an example by gradient method that is a fundamental computational procedure for optimal control problems. This example assumes a simple crop production problem such as obtaining the optimal control function which maximize number of individuals above a limited weight by means of controlling crops in community constructed from one species.
It can be well shown that controlling crop individuals improves the performance index and changes the inner communitie's structure. However some problems, such as expressing control cost and control function, deciding production period and number of divisions, are remained for further study.

View full abstract