Tadashi Chosa

Evaluation of the Dynamic Accuracy of a GPS Receiver: Is dynamic accuracy the same as static accuracy?

Abstract An experimental testbed and a data analysis procedure were developed to evaluate the dynamic performance of global positioning system (GPS) receivers. Receiver I - radio beacons differential correction based GPS receiver and Receiver II - satellite differential correction based GPS receiver were evaluated. Under dynamic conditions, the position errors were 1.39 and 1.71 m, the speed errors were 0.067 and 0.068 m/s, and the direction errors were 9.7° and 16.9° for the receivers I and II, respectively. The results indicated that the trends in the dynamic accuracy of GPS receivers were completely different from those for static accuracy. The study signifies the need for evaluating the GPS positioning errors under static as well as dynamic conditions to correct the errors.

Effect of Auxiliary Airflow in the Seeding Tube on an Air-assisted Seeding for Rice paddy

This study examined the effects of auxiliary airflow on seed movement in the seeding tube of an air-seeding device. A vinyl tube 8–16 mm in diameter was connected to the seeding tube to study the effect of auxiliary tube diameter for a constant auxiliary pressure of 0.4 MPa. Then, the auxiliary pressure was varied from 0.2 to 0.4 MPa for a constant auxiliary tube diameter of 3 mm. We confirmed that the main airflow velocity increased by 10 m/s and the seed velocity increased by 2.8 m/s for an auxiliary air pressure of 0.4 MPa supplied by a 3-mm-diameter auxiliary tube. However, under this same condition, the seed angle of descent increased by 3.4°.

Measurement System of Air Permeability and Airflow Resistance in Soil Deodorizer

Soil deodorizer has been widely used in Japan since 1970’s. One of challenges on soil deodorizer is to reduce energy consumption of blower towards a low carbon society. Measurement system for air permeability was examined to real soil filter of the deodorizer. Air permeability of soil filter could be measured precisely by using soil sample of 60 mm in diameter and 150 mm in height with confined pressure. Darcy’s law for airflow in soil filter was true under the airflow rate of 50 cm3 s-1 in this test apparatus. To reduce airflow resistance, treatments of improving soil structure were tested. Effect of the repetitive process of water intake & drainage and air movement on reducing airflow resistance was clarified by measuring air permeability of soil filter.