Optical microcantilever consisting of channel waveguide for scanning near-field optical microscopy controlled by atomic force

We develop a novel optical microcantilever for scanning near-field optical microscopy controlled by atomic force mode (SNOM/AFM). The optical microcantilever has the bent channel waveguide, the corner of which acts as aperture with a large tip angle. The resonance frequency of the optical microcantilever is 9 kHz, and the spring constant is estimated to be 0.59 N/m. The optical microcantilever can be operated in contact mode of SNOM/AFM and we obtain the optical resolution of about 200 nm, which is as same size as the diameter of aperture. We confirm that the throughput of optical microcantilever with an aperture of 170 nm diameter would be improved to be more than 10(-5).     

A note on application of superhomogénéisation factors to integro-differential neutron transport equations

The present article focuses on the application of the SPH factor method to the integro-differential neutron transport equation. While leakage-related parameters are arbitrarily corrected by the SPH factors, the correction procedure for these parameters affects the calculation accuracy. We treat two correction procedures named the simultaneous correction and the direct correction, and compare them with each other in one-dimensional colorset assembly problems. Through numerical testing, we find that the simultaneous SPH correction gives better accuracy than the direct SPH correction, and the higher-order SPH-corrected calculations show better accuracy than the low-order ones. Furthermore, to consider the flux discontinuity between different types of assemblies, the improved SPH method proposed by Yamamoto and the SPH method with the Selengut normalization condition are also tested. Numerical results reveal that the both methods significantly improve the calculation accuracy and that the latter method is more robust than the former method.     

Neutron transport benchmark problem proposal for fast critical assembly without homogenizations

In the present paper, we propose a neutron transport benchmark problem for fast critical assembly without homogenizations. With this problem, we can validate applicability of neutron transport codes when employed in highly heterogeneous fast critical assembly analyses. In addition, this benchmark problem can be used to validate homogenization procedures for slab lattices.     

Structures, physicochemical properties and oxygen reduction activities of carbons derived from ferrocene-poly(furfuryl alcohol) mixtures

The structure, physicochemical properties and oxygen reduction abilities of carbons prepared by the carbonization of mixtures of ferrocene and poly(furfuryl alcohol) were studied. X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM) studies revealed that the carbons thus prepared consisted of two components; amorphous and turbostratic shell-like components. The fraction, f _sharp, obtained by the analysis of the (002) peak in XRD was found to be a parameter that represented the degree of formation of the shell-like components. The formation of the shell-like components induced an increase in the mesopore volumes. Electrical conductivity increased exponentially with f _sharp, which indicated that the conduction process was governed by a percolation process of the conductive shell-like components. The amount of CO-desorption by O₂-TPD technique showed a maximum desorption at f _sharp=0.3, and the further development in the sharp component led to a decrease in the CO-desorption. Mössbauer spectroscopy technique revealed the presence of α-Fe, γ-Fe, Fe_1-x O and Fe₃C in the prepared carbons, which were soluble species to acids. The oxygen reduction activity was studied in a oxygen saturated sulfuric acid solution by rotating disk electrode voltammetry. The oxygen reduction potential varied with f _sharp; initially it increased by f _sharp=0.3 and then it decreased at higher f _sharp values. This behavior was similar to that of CO-desorption, which meant the presence of an adequate degree of the development of the shell-like structure for maximizing oxygen adsorption. Removal of the surface metal component from the carbons by acid-washing resulted in no decrease in the oxygen reduction activities of the carbons. The nature of the active sites on the carbon materials is discussed.     

Stochastic thermal stresses in an annular disc with spatially random heat transfer coefficients on upper and lower surfaces

Summary The second-order statistics (i.e., mean and variance) of the temperature and thermal stresses are analytically obtained in an annular disc with spatially random heat transfer coefficients (HTCs) on the upper and lower surfaces. This annular disc is assumed to have arbitrary variations in the HTCs solely in the radial direction and is subjected to deterministic axisymmetrical heating at the lateral surfaces. The stochastic temperature field is analyzed by considering the annular disc to be multilayered with spatially constant, but random HTCs in each layer. The Vodicka's method, which is a type of integral transform method, and a perturbation method are employed to obtain the analytical solutions for the statistics. The autocorrelation coefficients of the random HTCs and cross-correlation coefficients between the HTCs on different surfaces are expressed in exponential function forms as a homogeneous Markov random field of discrete space. Numerical calculations are performed for annular discs similar to an annular fin, which comprise two types of distributions of the means of the HTCs. The effects of the magnitude of the means of HTCs, spatial variations in the means of HTCs and correlation strengths of the HTCs on the standard deviations of the temperature and thermal stresses are discussed.     

Magnetic suspension force in an induction bearingless motor with a squirrel cage rotor

Theoretical equations of magnetic force in an induction bearingless motor have been reported. In the bearing‐less motor, both 4‐pole and 2‐pole windings are stored in stator slots for torque and suspension force generation. In the analysis, squirrel cage rotor currents are considered. These currents are induced by both torque and suspension winding currents. Inductance matrix is represented by four sets of three‐phase windings, thus a 12×12 matrix is constructed. A simplification and reasonable assumptions are introduced to obtain understandable expressions for suspension force and torque representation. The rotor flux linkages in an induction bearingless motor are derived, and a simulation model of suspension force is then constructed. It is shown that the response and the phase of suspension force are delayed in the case of cage rotors. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(3): 77–87, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20340     

Curing system involving SiH-containing organic oligomers

We describe here the preparation and properties of a novel curing system, which has been derived from an SiH-containing organic oligomer 1 and an allyloxy end-blocked organic oligomer 2 . The composition of these oligomers could be crosslinked via a platinum-catalyzed hydrosilylation reaction, that is, the addition reaction of the SiH bonds of 1 to the allyl functionality of 2 , above 100°C, yields a rubbery material in a short period of time. The compatibility of the SiH-containing oligomer 1 with the allyloxy end-blocked oligomer 2 was governed by the oligomer main chain employed. Hence the SiH-containing oligomer 1 was completely miscible with 2 , having the same main chain and, thus, the system yielded a homogeneously cured material. The poly(propylene oxide) curing system 1a / 2a was systematically investigated in detail to manifest its curing behavior and crosslink structure. © 1993 John Wiley & Sons, Inc.