Generalized Criterion for Stability of Superflow Past an Obstacle

We propose a new criterion of stability or instability of one-directional superflow of Bose condensates. In d-dimensional condensates with steady superflow, spectral function $\rho(\mathbf {r},\omega)=\sum_{l}|\langle l|\hat{n}(\mathbf{r})|\mathrm{g}\rangle|^{2}\delta (\omega-E_{l}+E_{\mathrm{g}})$ of the local density $\hat{n}(\mathbf{r})$ at the critical velocity behaves as ρ(r,ω)∝ ω ^β with β<d at low ω while ρ(r,ω)∝ ω ^d below the critical velocity. We confirm the validity of our criterion within the Gross-Pitaevskii-Bogoliubov theory. In the presence of a penetrable repulsive potential, β is given by d?2 at the critical velocity, where gray-soliton-phonon emission leads to the breakdown of superfluidity. In the case of the Landau instability in spatially uniform systems, on the other hand, β=?1/3,1/3,1 for d=1,2,3, respectively.     

Design Study of Top Lid with Clamp Structure in JT-60SA Cryostat

JT-60SA is a fully superconducting coil tokamak upgraded from the JT-60U. This paper focused on the integrity of the top lid of cryostat in JT-60SA. The design requirement for the cryostat in normal operations is to achieve vacuum insulation of 10 3 Pa, and the top flange of the top lid is lightly welded onto its body flange. The weld is tensile-loaded by bending deformation of the top lid due to vacuum pressure of external 0.1 MPa. This weld integrity is evaluated with tensile-load reduction, which results in clamp reinforcement. The structural integrity of the top lid is validated.     

Intranuclear cascade model for 50-MeV-region (p,p′x) reactions over a wide target mass range

In our previous study, the applicable range of the intranuclear cascade model was successfully extended to lower incident energy (p, p′x) reactions by introducing trajectory deflections and low-energy-loss process due to collective excitations. However, the model's validity was confirmed only for a ⁵⁶Fe target. In the present work we widen the applicable range of masses of the target nucleus. First, we derive an expression for the response function, which gives the probability of collective excitation strengths, to fit the distorted-wave Born approximation results as a function of the target mass number and the beam energy. Second, the barrier transmission coefficient was investigated. An expression with a modified Gamow penetration factor was chosen from four phenomenological forms of one-dimensional barrier transmission coefficients. Calculations with the proposed model followed by a generalized evaporation model were carried out for double-differential cross sections of (p, p′x) reactions at 30–60 MeV. Although the response function and the transmission coefficient were only parameterized approximately, the proposed model showed good agreements with experimental observations for a variety of nuclear targets from ¹²C to ²⁰⁹Bi.     

Viewpoints to characterize precision evaluation methods in binary measurements

Precision evaluation in quantitative measurements is a thoroughly discussed topic and the established methods are in use. Many methods are proposed for qualitative data including binary data, but their effectiveness and statistical properties are not so clear.     

Growth of silicon carbide thin films by hot-wire chemical vapor deposition from SiH4/CH4/H2

Silicon carbide (SiC) thin films were prepared by hot-wire chemical vapor deposition from SiH₄/CH₄/H₂ and their structural properties were investigated by X-ray diffraction, Fourier transform infrared absorption and Raman scattering spectroscopies. At 2 Torr, Si-crystallite-embedded amorphous SiC (a-Si_1 − xC_x:H) grew at filament temperatures (T_f) below 1600 °C and nanocrystalline cubic SiC (nc-3C-SiC:H) grew above T_f = 1700 °C. On the other hand, At 4 Torr, a-Si_1 − xC_x:H grew at T_f = 1400 °C and nc-3C-SiC grew above T_f = 1600 °C. When the intakes of Si and C atoms into the film per unit time are almost the same and H radicals with a high density are generated, which takes place at high T_f, nc-3C-SiC grows. On the other hand, at low T_f the intake of Si atoms is larger than that of C atoms and, consequently, Si-rich a-Si_1 − xC_x:H or Si-crystallite-embedded a-Si_1 − xC_x:H grow.     

An improved method of voltage utility factor for PWM control of a five‐leg inverter in two induction motor drives

This paper presents an improved method of voltage utility factor (VUF) from 50 to 86.6% for a five‐leg inverter when two induction motors are driven in vector control and in a condition where the frequencies of the two motors are not very different, and the improved method of voltage utility is theoretically shown. Many modulation methods for the five‐leg inverter have been proposed, but the voltage utility factor is 50% in these methods. The voltage utility factor of the five‐leg inverter is lower than that of the three‐leg inverter as maximum voltage utility factor of the three‐leg inverter is 100%. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Parametric Matter

The assimilation of digital techniques in production and manufacturing has enabled innovative explorations into nonstandard material organisation. Yusuke Obuchi, Theodore Spyropoulos and Tom Verebes of the Design Research Lab (DRL) at the Architectural Association (AA) describe how an interest in a textiles approach has developed out of a preoccupation with the interrelationship between material and computational design methods. They describe three projects that aspire to embed forms of material intelligence into architectural space. Copyright © 2006 John Wiley & Sons, Ltd.     

Activation Energy of Aggregation-Disaggregation Self-Oscillation of Polymer Chain

In this paper, we investigated the activation energies of the aggregation–disaggregation self-oscillation induced by the Belousov-Zhabotinsky (BZ) reaction by utilizing the nonthermoresponsive polymer chain in a wide temperature range. This is because the conventional type self-oscillating polymer chain, with thermoresponsive poly(Nisopropylacrylamide) (poly(NIPAAm) main-chain covalently bonded to the ruthenium catalyst (Ru(bpy)₃) of the BZ reaction, cannot evaluate the activation energy over the lower critical solution temperature (LCST). The nonthermoresponsive self-oscillating polymer chain is composed of a poly-vinylpyrrolidone (PVP) main-chain with the ruthenium catalyst (Ru(bpy)₃). As a result, we clarified that the activation energy of the aggregation–disaggregation self-oscillation of the polymer chain is hardly affected by the concentrations of the BZ substrates. In addition, the activation energy of the nonthermoresponsive self-oscillating polymer chain was found to be almost the same value as normal BZ reaction, i.e., not including the self-oscillating polymer system with Ru moiety.