Demonstration of Automatic Impedance-Matching and Constant Power Feeding to and Electric Helicopter via Magnetic Resonance Coupling

Wireless power transfer (WPT) from a transmitter resonator on the ground to an electrically powered miniature heli-copter was attempted to demonstrate WPT using magnetic resonance coupling to an object moving in 3D space. The transmission efficiency was optimized by automatic impedance matching for different flight attitudes: a maximum flight altitude of 590 mm was achieved. Furthermore, an estimation method of transmission efficiency using only the properties on the transmitter side was proposed, with transmission power regulated as constant against the change in the coupling coefficient.

Shear Performance of FRCC Beam-Column Joints Using Various Polymer Fibers

Brittle shear failure should be avoided in beam-column joint of a reinforced concrete(RC)frame during the earthquake.Fiber-reinforced cementitious composite(FRCC)which presents a remarkable deformability especially under tensile and bending load with a large energy absorption capacity is expected to be used in the crucial part of a RC frame.With the development of polymer material,various synthetic fibers have become the best selection to improve concrete capacity and failure resistance without the corrosion of fibers.The objective of this study is to investigate the influence of fiber bridging effect on the shear capacity of FRCC beam-column joint.The main parameter of the test in the present study is the fiber types:aramid,polypropylene(PP)and polyvinyl alcohol(PVA)fiber.To evaluate shear capacity quantitatively,a new calculation method using FRCC tensile characteristics confirmed by the uniaxial tension test is newly proposed.The difference of below 7%between calculated value and experimental value demonstrates that the calculation method is feasible.

Modeling of Bridging Law for PVA Fiber-Reinforced Cementitious Composite Considering Fiber Orientation

The authors have proposed the calculation method of bridging law,that is expressed by tensile stress–crack width relationship,considering the influence of fiber orientation in FRCC(fiber-reinforced cementitious composite).The objective of this study is to propose a new tri-linear model that expresses the bridging law considering fiber orientation.The parameters that give the characteristic points of the tri-linear model are proposed as functions of orientation intensity.The bending test,in which the specimens are fabricated by three different casting methods,is conducted to verify the adaptability of the proposed model.The results of section analysis using the proposed model can present the difference of bending strength due to the fiber orientation.

Wireless Power Transmission into Metallic Tube Using Axial Slit for Infrastructure Diagnostics

Wireless power transfer (WPT) using a metallic tube with axial slits was attempted to demonstrate WPT using magnetic resonance coupling to the diagnostics infrastructure. The transmission efficiency was measured at various distances using the transmission and receiver resonator in the tube. Furthermore, the transmission and receiver resonator were set respectively outside and inside of the tube. Experiment results were assessed computationally using the finite-difference time-domain (FDTD) simulation. As a result, the transmission efficiency of the transmitter and receiver resonators in the metallic slit tube was higher than that of the case without a metallic tube in the range of the normalized transmission-distance of x/d > 0.4. In the simulation, the current density on the metallic tube around both transmitter and receiver coil were connected. These results reveal that the slit on the tube plays a role of the relay coil.