Application of rigid polyurethane integral-skin foams to thermal insulating unit cases for car air conditioners

Integral-skin foams of rigid polyurethane are sandwich structures consisting of a core layer of closed cells enclosed in rigid surface layers on both sides. We examined the layer composition of integral-skin foam with the objective of maximum flexural strength, and then studied possibilities of reconciling the strength and thermal insulating properties in housings for evaporators in car air conditioners; i.e., unit cases. This examination showed that the most practical density range (250 ≦ ρ_pall ≦ 500 kg/m³) provides vibratile resistance and thermal insulating properties. In actual car-running tests, a maximum 0.1 MPa stress was generated on unit cases with overall densities of 350 kg/m³, We found this to be 0.4% of the flexural strength of an integral-skin foam and 2% of the fatigue strength. In the forcible vibratile test, a stress of 0.5 to 1.0 MPa was generated at the resonance point of a unit case with 250 to 500 kg/m³ overall density. We found that these values are 2 to 5% of integral-skin foam's flexural strength and 10 to 25% of its fatigue strength. These values are of the same level as the conventional unit case made of polypropylene blended with talc. An integral-skin foam with an overall density of 250 kg/m³, nearly equal to half the weight of polypropylene, has the same level of resistance to vibration.     

Fluctuation phenomena below the superconducting transition

The fluctuation propagator for the superconducting order parameter belowT _c is derived for a gapless superconductor. The fluctuation of the order parameter consists of two distinct modes: the fluctuations of the phase and the modulus of the order parameter. The former fluctuation obeys a phononlike dispersion, while the latter fluctuation is described by a damping diffusion type equation. The present theory gives an account of the fluctuation-induced Josephson effect belowT _c observed recently by Carlson and Goldman.     

Novel method for numerical analysis of electron trajectories in electrostatic fields of implicit functional forms

A novel method for calculating 2-dimensional electron trajectories is given, which is useful for the case when the electric fields are expressed by implicit functional forms which are not suited to a conventional electron-trajectory analysis. This method is applied to parallel-plate and parallel-cylinder deflection systems.     

Microwave response of superconducting thin films in magnetic fields

We calculate the complex conductivity of a superconducting thin film in a tilted magnetic field. Use is made of the time-dependent Ginzburg-Landau equations to deal with the dynamical behavior of the order parameter associated with the vortex motion in response to the microwave. The reactive part of the conductivity at zero frequency vanishes identically due to the vortex motion and the conductivity resembles that in the flux-flow regime of the type-II superconductor, unless the dc magnetic field is parallel to the film surface with high precision.     

Inelastic neutron scattering from the vortex lattice in type-II superconductors. I

The inelastic neutron scattering from the vortex lattice in dirty type-II superconductors is considered. In the high-field region, the correlation function for the local magnetization is given in terms of the fluctuation propagator of the superconducting order parameter. In particular it is shown that the Fourier transform of the correlation function for the local magnetization diverges as /q –G _i /^–2, when the transverse transfered momentumq approaches the reciprocal lattice vectorG _i of the Abrikosov lattice. This term gives rise to tails around each Bragg peak in the inelastic neutron-scattering cross section.     

Melt spinning and metal chloride vapor curing process on polymethylsilsesquioxane as Si?O?C fiber precursor

Melt spinning process of polymethylsilsesquioxane (PMSQ) at 403–453 K was investigated as a Si? O? C fiber precursor in terms of averages and distributions of spun fiber diameters. Because of fusible character of PMSQ at low temperature, the spun fibers were exposed to vapors of various metal chlorides (SiCl₄, Si(CH₃)Cl₃, TiCl₄, and BCl₃) to promote the fiber curing. Cured fibers were investigated by FTIR and TG analyses. In a case of the fiber synthesized with SiCl₄ curing, tensile tests on the pyrolyzed fibers were performed. Exposure of the synthesized fiber at high temperature with a flame of an oxygen‐gas burner was examined. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Testing the technologies

THE PENETRATION OF PHOTOv oltaic (PV) systems in Japan has been on the rise. Two factors have been promoting the increase: improved generation effi ciency of PV modules and governmental subsidies for the initial cost of residential PV generation systems. As a result, the cumulative installed PV capacity has increased exponentially, as shown in Figure 1; however, the cumulative installed PV capacity by 2007 was only about 40% of the target for 2010 (4,820 MW). Reaching the target and promoting larger installation capacities in the future will require further installation in the residential sector and the construction of large-scale PV systems.