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Supplemental lighting techniques in greenhouses can increase plant growth and yield but required much energy. We proposed an energy-saving supplemental lighting which was applied during rapid fruit development when transport of photosynthetic products into fruit was active. We experimented physiological responses (photosynthesis, growth, yield) of strawberry plants with single fruits truss, wherein the following 3 treatments were made: plants were cultivated with no supplemental lighting (Control), supplemental lighting throughout experimental period (Normal- light), and supplemental lighting during rapid fruit development (Short- light). The period of rapid fruit development corresponded to 33% of the experimental period, and the cumulative light intensity for the Short- light treatment was half of that for the Normal- light treatment, and two- fold of that for the Control treatment. Consequently, the leaf area and dry weight of the plant body were significantly increased upon Normal- light and Short-light treatments compared with the Control treatment. Yield for the Short- light treatment was also increased and nearly equal to that for the Normal- light treatment but no significance to the Control treatment. However, energy use efficiency of the Short-light was improved by 1.5- fold of the Normal- light treatment. Thus, shortening the period of supplemental lighting in accordance with the characteristics of fruit development is potentially effective.

A torque management model (TMM) focused on the close matching of driving requirements and operating conditions for electric tractors was developed. The TMM used the accelerator pedal output signal to establish the torque demand to adapt for two conditions – field traction and road driving. Further, the TMM uses the limitations of a time-based torque ramp, maximum motor torque at the current speed, and battery state of charge. To verify the performance of the TMM, a tractor control unit (TCU) to support the TMM was designed, and a test bench comprising both driving and loading devices was built. The bench provided the TMM/TCU with the necessary operating states needed as inputs to determine the torque demand. Experiments were performed under five specific manoeuvring cases. The test results showed that the TMM was capable of accurately converting pedal manipulations into torque demands both in the field traction and road driving conditions. The torque changes during testing were properly smoothed by limiting the rising and falling time of the target torque, which was favourable for eliminating impacts due to torque fluctuations. Overloading operations that would occur in case of excessive torque request were avoided by the torque capacity limitation both in the field traction and road acceleration tests. When the bus voltage was deliberately adjusted below the alarm threshold, the TMM could scale down the torque demand in real time according to the deviation between the actual voltage and the threshold, and therefore, it always kept the voltage above the safe level.

Small cooling fan failures are attributed to bearings. If a propeller rotates without any contact by magnetic levitation technology, high-speed rotation and long durability can be achieved. Thus, the authors are developing a small size maglev type motor. The Axial force/Torque Motor (AFTM) can generate axial bearing force and drive torque force in one unit. To increase the filling rate and manufacturing accuracy of winding, we used flex Printed Circuit Board (PCB) technology for AFTM. Coils are formed by winding the flex PCB around the back yoke. To higher manufacturable and improve the performance of AFTM, it is desirable to make flex PCB patterns correctly and increase the occupation ratio of copper. In this paper, we investigated the manufacturable layer configuration of special flex PCBs. Several prototypes with a different cover and copper thickness were manufactured and evaluated. We succeeded in producing a printed pattern with a copper thickness of 50 µm and a polyimide thickness of 5 µm. We could obtain a high filling factor.

Whole crop rice (WCR) is expected to establish a cultivation method using manure produced from animal wastes. Meanwhile, application methods of fertilizer and manure in the WCR cultivation are affe...

In horticultural crop production, accurately estimating the canopy photosynthetic rate (Ac) based on greenhouse climate conditions is of practical value for predicting and controlling crop growth and yield. We developed a method for continuously estimating Ac in a greenhouse from readily obtainable information (i.e., climatic data and canopy photographs) by combining a canopy photosynthesis model with image analysis. The canopy photosynthesis model was based on a sun/shade representation of the crop canopy combined with models of single-leaf photosynthesis, stomatal conductance, mass transfer and leaf energy balance. This combination allowed 1) the incorporation of all major climatic variables (i.e., radiation, CO2 concentration, air temperature, humidity, and wind velocity) into the Ac estimation and 2) the simultaneous estimation of Ac, canopy transpiration rate (Ec), and leaf temperature (TL). The leaf area index (Lc), which changes considerably throughout the growth period of a crop canopy, was evaluated nondestructively from the gap fractions of nadir digital photographs (i.e., the fractions of nonleaf area). The canopy photosynthesis model and image analysis results were combined and used to estimate the Ac, Ec, and TL of spinach canopies grown at ambient and elevated CO2 concentrations (c. 400 and 800 µmol mol−1, respectively). Regardless of the CO2 concentration, the estimates of Ac, Ec, and TL were in good agreement with measurements obtained with the open chamber method throughout the growth period. Analyzing the sensitivity of Ac to input variables revealed that the effects of climatic variables on Ac can vary considerably depending on the Lc and incoming radiation. The proposed method enables not only the estimation of Ac from readily obtainable information but also the quantitative evaluation of the effect of climate control on Ac in horticultural greenhouses.

With the ballast aging, the changes in the size and shape of the ballast particle reduce the drainage capacity, as well as cause a greater permanent deformation of the railroad ballast. Therefore, it is meaningful to investigate the effect of aging on the mechanical behavior of unsaturated ballast, and to estimate the cyclic plastic deformation by considering the aging effects. Here, “aging effect” means the increase in fine fraction content and the particle shape becomes rounded and smooth as compared with fresh ballast. In this study, the influence of aging on the cyclic plastic deformation of unsaturated ballast was evaluated through a series of cyclic loading triaxial compression tests. Test results indicate that the cyclic plastic deformation of ballast is seriously affected by water content, fine fraction content and drainage condition, and the increasing trend becomes more remarkable at the water-rich aged ballast under the fully undrained condition since the effective confining pressure decreases due to the generation of excess pore water pressure. Furthermore, the applicability of two types of estimation models (i.e., a semi-empirical model named University of Illinois at Urbana-Champaign (UIUC) model, and an elasto-plastic model named subloading surface extension (SSE) model) to the prediction for cyclic plastic deformation of unsaturated ballast is also verified in this study by comparing with results of cyclic loading triaxial compression tests. As the result, it is revealed that the UIUC model is suitable for predicting the cyclic plastic deformation of fresh ballast (or slightly aged ballast) with different water contents under the fully drained condition, and the SSE model shows good potential to estimate the cyclic plastic deformation of fresh and aged ballasts by considering the effects of water content and drainage condition. The findings of this study indicate that drainage conditions have a significant effect on predicting the cyclic plastic deformation of aged ballast, and appropriate test conditions for triaxial compression tests (i.e., CD and CU tests) should be selected according to hydraulic properties (i.e., permeability and water retentivity) of the aged ballast.

The response of crops to elevated atmospheric CO2 concentrations ( C a ) is of great concern for horticultural vegetable production in greenhouse facilities, where C a levels are often artificially elevated. To elucidate the long-term effect of the elevated C a on canopy photosynthesis and growth, we conducted long-term continuous measurements of the canopy photosynthesis ( A ) and leaf area index ( L ) of hydroponically grown spinach canopies under elevated C a (approximately 800 μmol mol−1) and ambient C a (approximately 400 μmol mol−1) treatments by combining the open chamber method and image analysis of the top of view of canopies. There existed a positive feedback loop between A and L, where an increase in L caused an increase in A , which subsequently accelerated the increase in L . The enhancing effect of elevated C a on A, which was evaluated with enhancement ratios (i.e., A in the elevated C a treatment divided by A in the ambient C a treatment; A e l e v / A a m b ), showed a short-term increase under high-light conditions during the daytime and a long-term increase with canopy growth toward the harvest. The long-term increase in A e l e v / A a m b was attributed to the enhancement of A e l e v brought on by not only the short-term enhancing effect of elevated C a but also the more rapidly increasing and thus larger L in the elevated C a treatment compared with that in the ambient C a treatment. Both the long-term increase in A e l e v / A a m b and the more rapidly increasing L in the elevated C a treatment were caused by the “compound interest effect” of elevated C a , where the enhancing effects of elevated C a on A and L were gradually amplified over a long-term period through the positive feedback loop between A and L . This compound interest effect of elevated C a also caused a long-term increase in canopy nighttime respiration in proportion to daytime photosynthesis. Through these changes in the canopy-scale carbon balance, the compound interest effect detected in the elevated C a treatment likely contributed to a substantial increase in the final aboveground dry weight at the harvest time. This study highlights the importance of the long-term compound interest effect of elevated C a on canopy photosynthesis, carbon balance, and growth.

Measuring the area of combine-harvested field sections corresponding to a truckload of grain received at a grain elevator (LHA: load harvest area) allows the estimation of brown rice yield. The objective of this study was to evaluate the accuracy of LHA measured based on combine movement traces when the traces were recorded by a GPS or a GPS + Quasi-Zenith Satellite System (QZSS) receiver. For the measurements using a GPS receiver, the mean and standard deviation of relative errors of LHA were 4.7% and 8.1%. The center of the relative error distribution shifted toward positive because positioning errors of a GPS receiver shifted outer edges of harvested sections outward and resulted in measuring larger harvested area than a true value. For the measurements using a GPS + QZSS receiver, the mean and standard deviation of relative errors of LHA were 0.5% and 4.8%. The center of the relative error distribution was around 0% for its better positioning accuracy. The relative errors of LHA tended to be large when an LHA was measured from a field section where only the outer-part of a field is harvested or several small harvested sections. These cases of LHA measurements increased the sum of the perimeter of harvested sections and resulted in deteriorating the measurement accuracy. This result indicated that measurement accuracy of LHA can be further improved by correcting error, which can be estimated based on positioning errors and the perimeter of harvested sections.

Dry-seeded rice cultivation is an effective low-cost cultivation method in Japan, but preventing water leakage from cultivated rice fields remains a challenge. Here we assessed the efficiency of using a vibratory roller in a dry-seeded rice field for preventing water leakage. The tests were conducted at two different soil-water contents (WC: 32 and 39%) before roller compaction. We measured the acceleration response of the vibrating roller by using a micro-electro mechanical system (MEMS) accelerometer, and we determined the volume of water leakage from the field by using a rapid leakage capacity tester. We analyzed the changes in the soil structure by using a micro-focused X-ray CT scanner. We analyzed all of the resulting data to identify any correlation. We observed that water leakage from the field was sufficiently prevented when prior to roller compaction, soil moisture content was 39%. The shape of the soil pores that could efficiently prevent water leakage was flatter than that of the inefficiently compacted soil. In addition, the total porosity decreased, but the small-sized pore fraction increased. The vibration acceleration of the roller significantly increased with the decrease in the volume of water leakage. Thus, in addition to assessing the efficiency of vibratory rollers in reducing water leakage, our data suggest that it is to some extent possible to estimate the water leakage prevention effect from the acceleration response of a vibrating roller.