Proposal and Design of a Slim Electronically Steerable Parasitic Array Radiator Antenna in the 2.4-GHz Band

We propose an electronically steerable parasitic array radiator antenna that is about 96% smaller than a conventional one. The antenna can shape a beam with a working gain of about 6 dBi without a matching circuit and steer the beam in steps of 45°. The reactance with which parasitic elements are loaded is designed to achieve vswr of <3 in the frequency band for IEEE802.11b by controlling the set of reactance values in three steps. Consequently, a pen-sized beam steerable antenna can be made for a 2.4-GHz-band wireless local area network. The antenna is unique in that the current excited on parasitic elements is stronger than that excited on the fed element when a beam is shaped.     

Proposal of Integrated Test Facility for in-Vessel Thermofluid Safety of Fusion Reactors

A vacuum vessel (VV) of a tokamak fusion reactor like the International Thermonuclear Experimental Reactor (ITER) consists the first confinement barrier that includes the largest amount of radioactive materials such as tritium and activation products. The ingress of coolant event (ICE) is a design basis event in the ITER where water is used as the coolant. The loss of vacuum event (LOVA) is also considered as an independent design basis event. Based on the results of ICE and LOVA preliminary experiments, an integrated in-vessel thermofluid test is being planned and conceptual design of the facility is in progress. The main objectives of the integrated test are to investigate the consequences of possible interaction of the ICE and the LOVA and to validate the analytical model of thermofluid events in the VV of the fusion reactor. This paper introduces a conceptual design of the integrated test facility and a testing plan.     

A new type of fatigue striation on PMMA immersed in organic agents

Fatigue crack growth tests of PMMA were undertaken at 295 K in organic agents with relatively high viscosity. Regular wavy striations, the wave length and amplitude of which were dependent on the characteristics of the agent, appeared on the fracture surfaces at low values of the stress intensity factor ranges. This type of striation has not been reported elsewhere. The formation mechanism of these was analysed based on the two dimensional viscous-fluid flow through a narrow gap between the crack planes. The theoretical suggestion that the wave length of the striation tends to increase with increase in the surface tension of the liquid and a decrease in its viscosity was in good agreement with the experimental trend.     

Mullite–Boron Nitride Composite with High Strength and Low Elasticity

Mullite–boron nitride (BN) composite with high strength, low Young's modulus, and highly improved strain tolerance was prepared by reactive hot pressing (RHP) using aluminum borates (9Al₂O₃·2B₂O₃ and 2Al₂O₃·B₂O₃) and silicon nitride as starting materials. Compared with the monolithic mullite, the composite RHPed at 1800°C showed 1.64 times (540 MPa) the strength, 70% (153 GPa) the Young's modulus, and 2.34 times (3.53 × 10⁻³) the strain tolerance. Transmission electron microscopy observation revealed that the composite had an isotropic microstructure with a fine mullite matrix grain size of less than 1 μm and nanosized hexagonal BN (h-BN) platelets of about 200 nm in length and 60–80 nm in thickness. The high strength was suggested to be from the reduced matrix grain size and the small toughening effect by the h-BN platelets.