Sophia University

About: Sophia University is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Nonlinear system & Catalysis. The organization has 4986 authors who have published 7657 publications receiving 106567 citations. The organization is also known as: Jōchi Daigaku.

Thermal Conductivity of High-Strength Polyethylene Fiber and Applications for Cryogenic Use

Abstract: The local temperature rise of the tape is one of instabilities of the conduction-cooled high temperature superconducting (HTS) coils. To prevent the HTS tape from locally raising a temperature, high thermal conductive fiber reinforced plastic was applied to coil bobbin or spacer for heat drain from HTS tape. The thermal conductivity of ramie fibers increases by increasing orientation of molecular chains with drawing in water, and decreases by chain scission with γ-rays irradiation or by bridge points in molecular chains with vapor-phase-formaldehyde treatments. Thermal conductivity of high strength ultra-high-molecular-weight (UHMW) polyethylene (PE) fiber increases lineally in proportion to tensile modulus and decreases by molecular chain scissions with γ-rays irradiation. This result suggested the contribution of the long extended molecular chains due to high molecular weight on the high thermal conductivity of high strength UHMW PE fiber. Thermal conductivity of high strength UHMW PE fiber reinforced plastics in parallel to fiber direction is proportional to the cross sectional ratio of reinforcement oriented in the conduction direction. Heat drain effect of high strength UHMW PE fiber reinforced plastic from HTS tape is higher than that of glass fiber reinforced plastic (GFRP) and lower than that of aluminum nitride (AlN). In the case of HTS coil, the thermal stability wound on coil bobbin made of high strength UHMW PE fiber reinforced plastic is good as that of AlN, and better than that of GFRP.

Robust Guidance Law with L2 Gain Performance

Abstract: The guidance law design problem is formulated as a disturbance attenuation L2 gain control problem where target accelerations are regarded as unpredictable disturbances that are completely unknown, but bounded and guidance parameter errors are viewed as bounded control system parameter uncertainties. By using a Lyapunov-like approach to find the feedback control, a guidance law satisfying the L2 gain performance is derived from a linear time-varying mathematical model that describes the missile-target engagement. During the derivation of the guidance law, its robust stability is proved. Simulation results show that the presented guidance law provides strong robustness properties against heading error, guidance parameter errors, and target maneuvers; thus they obtain excellent miss-distance performance over the conventional realistic true proportional navigation guidance law.