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The discontinuous PWM method is widely used because the switching loss can be drastically reduced. However, acoustic noise generated from a motor and a reactor with the discontinuous PWM method increases more than with the conventional sinusoidal PWM method. In applications where noise must be considered, the carrier frequency is set near the upper limit of the audible range. However, the acoustic noise may be a problem when the discontinuous PWM method is used. The authors have previously proposed "Rampwise DPWM" which can reduce both acoustic noise and switching loss. This paper shows that the proposed technique is effective even under the condition that the output voltage amplitude of the inverter or the ratio of the switching pause period is changed.

SnS is a promising photovoltaic semiconductor owing to its suitable band gap energy and high optical absorption coefficient for highly efficient thin film solar cells. The most significant carnage is demonstration of n-type SnS. In this study, Cl-doped n-type single crystals were grown using SnCl2 self-flux method. The obtained crystal was lamellar, with length and width of a few millimeters and thickness ranging between 28 and 39 μm. X-ray diffraction measurements revealed the single crystals had an orthorhombic unit cell. Since the ionic radii of S2– and Cl– are similar, Cl doping did not result in substantial change in lattice parameter. All the elements were homogeneously distributed on a cleaved surface; the Sn/(S + Cl) ratio was 1.00. The crystal was an n-type degenerate semiconductor with a carrier concentration of ∼3 × 1017 cm–3. Hall mobility at 300 K was 252 cm2 V–1 s–1 and reached 363 cm2 V–1 s–1 at 142 K.

The electronic structures of delafossite α-CuGaO2 and wurtzite β-CuGaO2 were calculated based on density functional theory using the local density approximation functional including the Hubbard correction (LDA+U). The differences in the electronic structure and physical properties between the two polymorphs were investigated in terms of their crystal structures. Three major structural features were found to influence the electronic structure. The first feature is the atomic arrangements of cations. In the conduction band of α-CuGaO2 with a layered structure of Cu2O and Ga2O3, Cu and Ga states do not mix well; the lower part of the conduction band mainly consists of Cu 4s and 4p states, and the upper part consists of Ga 4s and 4p states. By contrast, in β-CuGaO2, which is composed of CuO4 and GaO4 tetrahedra, Cu and Ga states are well-mixed. The second feature is the coordination environment of Cu atoms; the breaking of degeneracy of Cu 3d orbitals is determined by the crystal field. Dispersion of the Cu 3d valence band of β-CuGaO2, in which Cu atoms are tetrahedrally coordinated to oxygen atoms, is smaller than those in α-CuGaO2, in which Cu atoms are linearly coordinated to oxygen atoms; this results in a larger absorption coefficient and larger hole effective mass in β-CuGaO2 than in α-CuGaO2. The interatomic distance between Cu atoms-the third feature-also influences the dispersion of the Cu 3d valence band (i.e., the effective hole mass); the effective hole mass decreases with decreasing interatomic distance between Cu atoms in each structure. The results obtained are valuable for understanding the physical properties of oxide semiconductors containing monovalent copper and silver.

SnS is a promising photovoltaic semiconductor owing to its suitable band gap energy and high optical absorption coefficient for highly efficient thin film solar cells. The most significant carnage is demonstration of n-type SnS. In this study, Cl-doped n-type single crystals were grown using SnCl

Let ν + \nu ^+ and ν − \nu ^- be two measured laminations which fill up a hyperbolic surface. Kerckhoff [Duke Math. J. 65 (1992), 187–213] defines a line of minima as a family of surfaces where convex combinations of the hyperbolic length functions of ν + \nu ^+ and ν − \nu ^- are minimum. This is a proper curve in the Teichmüller space. We show that there exists a line of minima which does not converge in the Thurston compactification of the Teichmüller space of a compact Riemann surface. We also show that the limit set of the line of minima is contained in a simplex on the Thurston boundary.

Relatively nontoxic, earth-abundant Cl was incorporated into n-type SnS as a dopant. The existence of impurity phases was carefully identified in Sn(S1− x − y Cl x )-dense ceramics. The highest electron mobility (8.3 cm2 V−1 s−1) in n-type conduction was achieved in samples with x ≥ 0.005. Cl concentration is critical for conduction-type conversion, whereas carrier density and electron mobility are determined by sulfur-site deficiency. Carrier transport is explained by grain boundary potential barrier scattering in undoped p-type samples and by ionized impurity scattering in Cl-doped n-type samples.

Silver nanoink sinterable at low temperature, as low as 120degC, was developed from silver nanoparticle synthesized by thermal decomposition of silver complex. This ink has features of both low sintering temperature and excellent solution stability. Printed samples and some applications are described.

Traffic information feedback strategies have the potential to improve the efficiency of traffic flow. There is a processing delay in providing the information, and the delay sometimes makes the traffic flow unstable. In this study, a relationship between the stability of traffic flow of the Symmetrical Two-Route with providing traffic information and the information delay is analyzed. The type of provided traffic information is vehicle number on each route. It is assumed that drivers choose one route by reference to the information. The dynamics of the traffic flow is described by the delay differential equation. By analyzing the equation, a sufficient condition for stability of the traffic flow is presented. Moreover, the validity of the condition is confirmed by numerical simulations using the Stochastic Optimal Velocity model, which is one of the realistic traffic models.

Rhodium(I)-catalyzed 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds was carried out in the presence of a chiral phosphoramidite ligand based on (R)-binol and dialkylamines. The reaction was significantly accelerated in the presence of a base such as KOH and Et 3 N, allowing the reaction to be completed within 6 hours at 50 °C. The addition to 2-cyclohexenone achieved enantioselectivities up to 99%, though they were less effective for 2-cyclopentenone (79% ee), 2-cycloheptenone (77% ee) and acyclic enones (31-43% ee).

The rhodium-catalyzed conjugate addition of tolylboronic acid to α,β-unsaturated ketones, esters or amides was carried out in water. [RhCl(cod)]2 and 2β-cyclodextrin-[Rh(OH)(cod)]2 complexes were found to catalyze the reaction efficiently in a single aqueous medium.

A series of Adamantanephenol derivatives was synthesized from adamantinetriphenol / adamantinetrimethylhydroquinone and vinylether compound. Solubility for resist solvent or alkali developer of those materials and thermal properties were examined. Adamantanetrimethylhydroquinone cross-linked with divinylether (AmHQ-CL) had excellent properties as positive tone resist material. We evaluated lithographic properties of AmHQ-CL with photo acid generator and base. Line and space pattern was formed with EB exposure followed with post exposure bake and alkali development. Pattern of smooth wall surface was obtained by removing high molecular weight component from AmHQ-CL. Line width roughness (LWR) of the pattern AnHQ-CL nMWD was less than 30 nm. It was very small value compared with that of traditional polymer resist.

The rhodium-catalyzed conjugate addition of tolylboronic acid to α,β-unsaturated ketones, esters or amides was carried out in water. [RhCl(cod)]2 and 2β-cyclodextrin-[Rh(OH)(cod)]2 complexes were found to catalyze the reaction efficiently in a single aqueous medium.