Adaptive optics instrumentation in submillimeter/terahertz spectroscopy with a flexible polyvinylidene fluoride cladding hollow waveguide

A simple instrument has been developed to carry out temperature dependent submillimeter/terahertz-wave spectroscopy using a polyvinylidene fluoride flexible hollow waveguide and an eggplant-shape launching lens.     

Spectroscopic and Photoluminescent Properties of Indium Zinc Oxide (IZO) and IZO/Ag/IZO Sandwiched Film

We report the ellipsometric and photoluminescence (PL) properties of Indium zinc oxide (IZO) films, which were grown by radio frequency sputtering under Ar and O₂ atmospheres. IZO films grown under an O₂ atmosphere (IZO (O₂)) showed enhanced PL properties when compared to the films grown under an Ar atmosphere (IZO (Ar)), particularly with respect to the band-edge emission. The enhancement of band-edge emission can be attributed to the reduction in the non-emissive defect states related to oxygen vacancies, which were repaired by sputtering under O₂ atmosphere, whereas the PL enhancement in green region is probably due to the formation of the different types of defects under the excess oxygen environment. This was also supported by the results of time-resolved PL measurements, where the band-edge emission of IZO (Ar) showed rapid decay with a 50 ps lifetime, which indicates the dominance of the relaxation pathway to underlying defect states. In contrast, the PL decay profiles of IZO (O₂) for band-edge and emissive defect states showed moderate decay with time-constants of 2.3 ns and 5.7 ns, respectively. The exciton relaxation dynamics were sensitive to the presence and its kinds of defect states, which were controlled by the growth conditions.     

Revising the logical foundations of inductive logic programming systems with ground reduced programs

In this paper we revise Muggleton’s theory of inverse entailment, which is the logical foundation of Progol, one of the most famous ILP systems. We first point out that the theory is incomplete in general. Secondly we prove that the theory is complete if the background knowledge given to the system is a ground reduced program, every training example is a ground unit clause, and the hypothesis space is the set of all definite clauses. The proof is obtained by showing that every ground reduced logic program is logically equivalent to the conjunction of all atoms in its least Herbrand model. As a corollary to this equivalence, we are finally able to improve the logical foundation of the GOLEM system.     

Low-Temperature Sintering of Mullite/Yttria-Doped Zirconia Composites in the Mullite-Rich Region

Mullite/Y-TZP composites in the mullite-rich region, using powders of mullite prepared via the hydrazine method and a commercially available zirconia compound (ZrO₂(2Y)), have been fabricated by sintering for 3 h at 1450°C in air. The grain sizes of mullite and ZrO₂(2Y) are changed with increased ZrO₂(2Y) content; the former decreases from 0.25 µm to 0.13 µm, and the latter increases from 0.21 µm to 0.35 µm. High strength (780 MPa) and fracture toughness (5.4 MPam^1/2) are obtained in the 50/50 (vol%) mullite/ZrO₂(2Y) composite with 99.6% of theoretical density.     

High Atom Efficiency in Sc(OTf)3‐Catalyzed Allylation of Aldehydes with Tetraallyltin

The high atom efficiency was achieved through addition of Ac₂O in the Sc(OTf)₃‐catalyzed allylation of aldehyde with tetraallytin in a 4 : 1 molar ratio.     

Theoretical analysis of transient recovery voltages when clearing a transformer secondary fault

An analytical formula for the transient recovery voltage and its derivative dv/dt across a circuit breaker has been derived for the case of a transformer secondary fault. A comparison of the calculated results with field test and EMTP simulation results has demonstrated it to have satisfactory accuracy. By applying the formula, the effects of various circuit parameters on the transient recovery voltage and its derivative dv/dt are elucidated. The derivative dv/dt, defined conventionally as the ratio of the crest value and the time to the crest, is found to be about two‐thirds of the maximum value of dv/dt given as a function of time. In addition, a formula for the critical circuit parameters at which dv/dt across a vacuum circuit breaker reaches the critical condition, that is, the circuit breaker fails to interrupt a fault current, is derived. © 2000 Scripta Technica, Electr Eng Jpn, 134(3): 44–52, 2001     

Pollution control of actual flue gas using pulsed power at a thermal power plant

There are several important environmental problems in the world. One of them is acid rain caused by combustion flue gases from thermal power plants, factories, and automobiles. Different kinds of gas discharges, such as surface discharge, dc and ac corona discharge, silent discharge, and electron beam controlled discharge, have been studied for the removal of NO_x and SO₂ from flue gases. The recent development of repetitive pulsed power generators gives the pulsed steamer corona discharges a chance of success in the removal of NO_x and SO₂. In this paper, the experimental results of NO_x and SO₂ removal by a repetitive pulse power generator are described. The actual flue gas at a thermal power plant was used. It is shown that about 90% of the NO was removed at a flow rate of 0.8 liters/min and a repetition rate of 7 pps. © 2001 Scripta Technica, Electr Eng Jpn, 134(4): 28–35, 2001     

Experimental study on laboratory scale Totalized Hydrogen Energy Utilization System using wind power data

The renewable energy source like wind energy generates electric power with intermittent nature. Hydrogen energy system can help to solve the fluctuation problem of the wind power. Totalized Hydrogen Energy Utilization System (THEUS) consists of a Unitized Reversible Fuel Cell (URFC), a hydrogen storage tank, and other auxiliary components. Wind power is inherently variable; the URFC will be subjected to a dynamic input power profile in water electrolyzer mode operation. This paper describes the THEUS operation and performance at different variations in intermittent wind power. The performance of the THEUS was evaluated in water electrolyzer and fuel cell mode operation. The stack efficiency, system efficiency, and system efficiency including heat output from the URFC were presented at each operation. The total efficiency of the URFC and THEUS were also investigated. The maximum total efficiency of the URFC and THEUS were 53% and 66%, respectively.     

Improvement in mechanical properties of poly(p‐phenylene sulfide) fibers by high‐tension multiannealing method

High‐tension multiannealing (HTMA) was applied to improve the tensile properties of poly(p‐phenylene sulfide) fibers, which was furthermore applied to the fibers produced and improved with the zone‐drawing and zone‐annealing treatments. The HTMA treatment was repeatedly applied to the fibers under the conditions of a 250°C temperature and an applied tension of between 201.0 and 188.0 MPa. As a result, at the 13th treatment the degree of crystallinity increased to 40%. On the other hand, the orientation factor of crystallites increased dramatically to 0.982 during the zone‐drawing treatment, but increased only slightly during the subsequent treatments of zone annealing and HTMA. The finally obtained fiber had a tensile modulus of 10.4 GPa and a tensile strength of 0.73 GPa. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1569–1576, 2000     

Field test and EMTP simulation of transient voltages when clearing a transformer secondary fault

A field test was carried out to investigate a fault clearing transient due to current interruption of a three‐phase to ground fault at the secondary side of a 3‐MVA, 22/6.6‐kV transformer by a vacuum circuit breaker. EMTP simulations in comparison with the measured results have made it clear that the capacitance C_p of a CR divider to measure voltages reduces dv/dt of transient recovery voltage across the circuit breaker by the ratio of (C_t/(C_t + C_p) where C_t is the transformer stray capacitance. The leakage inductance evaluated from the transformer rating has been found to be noticeably greater than that determined from the measured fault current possibly due to the transformer saturation. Considering the transformer magnetizing conductance and selecting an appropriate interrupted current, EMTP simulation gives a satisfactory result compared with a field test. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 40–48, 2000