MRI Application for Clarifying Fuel Cell Performance with Variation of Polymer Electrolyte Membranes: Comparison of Water Content of a Hydrocarbon Membrane and a Perfluorinated Membrane

Magnetic resonance imaging (MRI) is applied to clarify a dominating factor on variation of fuel cell performance with two types of polymer electrolyte membranes, a hydrocarbon membrane and a perfluorinated membrane. MRI results revealed that the hydrocarbon membrane showed a water content higher than that of the perfluorinated membrane, responsible for a better fuel cell performance due to decrease of resistance loss of the fuel cell. Authors' address: Shohji Tsushima, Research Center for Carbon Recycling and Energy, Tokyo Institute of Technology, 2-12-1, Ohokayama, Meguro-ku, Tokyo 152-8552, Japan     

Optimization of carbon incorporation in GaAs during molecular beam epitaxial growth

Carbon-doped GaAs with dopant concentrations up to about 10²⁰ cm^–3 has been grown by molecular beam epitaxy. Above a critical carbon concentration, which depends on the deposition parameters, the surface deteriorates and loses its mirror-like appearance. From X-ray diffractometry and scanning electron microscopy, a diagram is established separating two areas with rough and mirror-like surface morphologies. The electrical properties as well as the morphology of GaAs : C can be simultaneously improved by a careful adjustment of the deposition parameters according to this diagram. On leave at: Tokyo Institute of Technology, Research Center for Quantum Effect Electronics, 2-12-1 O-okayama, Meguro-ku, Tokyo 152, Japan     

Purification and uniqueness of quantum Gibbs states

We give a new condition for uniqueness of Gibbs states of quantum spin models on lattices.Research fellow of Canon Foundation in Europe, on leave from Tokyo Metropolitan University, Hachioji, 192-03 Japan     

On the convergence of exponential operators—the Zassenhaus formula,BCH formula and systematic approximants

The convergence of the Zassenhaus formula is proven under an appropriate condition as well as for other exponential operators such as the Baker-Campbell-Hausdorff formula.On leave of absence from Department of Physics, Faculty of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan     

Review of Recent Zoom Lens Developments for 35 mm Cinematography at Panavision

A series of high performance zoom lens objectives developed by Panavision over fifteen years, which are very popular in the motion picture (cine) industry, are described. Various aspects of four cine zoom lenses, including; definitions, development, specification, construction, aberrations and tolerances, are discussed.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15-17, 2000 at the International Conference Center, Tokyo, Waseda University, Japan.     

Characterization of nonlinear optical parameters of polymethine dyes

We investigated nonlinear refraction, nonlinear absorption, and saturable absorption of polymethine dyes by the Z-scan technique (λ=1064 nm). The analysis of simultaneous appearance of several nonlinear optical processes in dye solutions excited by picosecond pulses was carried out. The saturable absorption was analyzed taking into account various models. Nonlinear refractive indices, nonlinear absorption coefficients, and saturation intensities of various polymethine dyes were measured. Received: 27 December 2002 / Revised version: 6 March 2003 / Published online: 5 May 2003 RID="*" ID="*"Corresponding author. Fax: +81-471/363-366, E-mail: r_ganeev@issp.u-tokyo.ac.jp RID="**" ID="**"Present address: The Institute for Solid State Physics, The Tokyo University, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan     

Reconstruction of Optical Surfaces from Ray Data

We present a reconstruction algorithm to compute the topography of one or two optical surfaces of an arbitrary shape. The surfaces are constructed from a set of first order partial differential equations. The data consists of information on ray deflection by the surfaces. The algorithm can be used for lens design, to analyze an unknown lens, or for quality control purposes.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15-17, 2000 at the International Conference Center, Tokyo, Waseda University, Japan.     

Screening of impurities in strong magnetic fields

Charged impurities inserted in an electron gas in strong magnetic fields and at low temperatures are considered. Using the random phase and the generalized Born approximations, a self-consistent calculation of the screening of the impurities and the broadening of the electronic energy levels due to the scattering by these impurities is presented. Concrete results obtained in numerical form show that for typical semiconductors the anisotropy of te screening induced by the magnetic field is strongly reduced by collisional damping. The screening length, however, depends rather strongly on the field.On leave of absence from the Department of Physics, University of Tokyo, Tokyo, Japan.     

Transverse asymmetry of $^3\!\stackrel{\rightarrow}{\rm He}$ and the magnetic form factor of the neutron

Multi-nucleon transfer reactions in ⁴⁰Ca + ²⁰⁸Pb have been studied at several bombarding energies close to the Coulomb barrier. Light reaction products have been identified in mass and charge with a time-of-flight spectrometer. The energy spectra of the inclusive two-neutron pick-up channel show a population in a narrow region of excitation energies which corresponds to the predicted energy of pairing-vibration states in ⁴²Ca.Received: 30 September 2003, Revised: 9 December 2003, Published online: 13 July 2004PACS: 25.70.Hi Transfer reactions - 24.10.-i Nuclear reaction models and methods - 21.60.Cs Shell model - 21.10.Pc Single-particle levels and strength functionsA.M. Vinodkumar: Present address: Tokyo Institute of Technology, Japan.     

Parameter Dependence of the Iterative Stepwise Quantization Method in Hologram Binarization for Real and Complex Amplitude Signals

In this paper we present the results of parameter dependence analysis of the iterative stepwise quantization method in amplitude hologram binarization. Although the original method considers only a real amplitude signal, we also analyze the parameter dependence for the complex amplitude signal. The results of the analysis help in selecting the parameters in a way that binary holograms with improved quality of reconstructions can be obtained.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15-17, 2000 at the International Conference Center, Tokyo, Waseda University, Japan.     

Concluding remarks to ICAME2011

An overview of the main aspects of ICAME2011 – tutorial lectures, oral and poster presentations, evening sessions - is presented along with a brief outline of several of the scientific highlights. Among other topics considered are the involvements of young scientists and female scientists, and operation of the oral and poster sessions. Despite the most challenging combinations of circumstances in the lead up to ICAME2011 that resulted in the change of venue at an advanced stage from Tokyo to Kobe, the Committee organised a high quality conference with many positive outcomes for the future. The Mössbauer community acknowledges and appreciates these efforts greatly.     

New limits on coupling of fundamental constants to gravity using 87Sr optical lattice clocks

The 1S0-3P0 clock transition frequency nuSr in neutral 87Sr has been measured relative to the Cs standard by three independent laboratories in Boulder, Paris, and Tokyo over the last three years. The agreement on the 1 x 10(-15) level makes nuSr the best agreed-upon optical atomic frequency. We combine periodic variations in the 87Sr clock frequency with 199Hg+ and H-maser data to test local position invariance by obtaining the strongest limits to date on gravitational-coupling coefficients for the fine-structure constant alpha, electron-proton mass ratio mu, and light quark mass. Furthermore, after 199Hg+, 171Yb+, and H, we add 87Sr as the fourth optical atomic clock species to enhance constraints on yearly drifts of alpha and mu.     

Design of the Optimum Holographic Optical Element Lens Using the Hologram Computer-Aided Design Tool

A hologram CAD (computer-aided design) tool capable of designing holographic optical element (HOE) is described. We have been developing this tool which is specialized for holograms. An optimum HOE lens with high diffraction efficiency and diffraction limited imaging characteristics is designed with the tool by applying a computer generated hologram (CGH) which generates an aspherical wave. The imaging characteristics of the HOE lens are experimentally verified and desirable results are obtained.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15-17, 2000 at the International Conference Center, Tokyo, Waseda University, Japan.     

Optical Pick-up for Blue Optical Recording at NA = 0.85

Sony and Philips have recently developed the basic technology for a 22.5 GB optical recording system, based on a blue laser (#x03BB; = 405 nm) and high numerical aperture (NA = 0.85) objective lens. This system is referred to by the acronym DVR (for Digital Video Recording). In this paper we describe the relization of a compact optical pickup unit capable of writing and reading data on disc according to the DVR format.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15-17, 2000 at the International Conference Center Tokyo Waseda University, Japan.     

Nanosecond Bias-Free Mach–Zehnder Electro-Optic Switch Based on Dye-Doped Polymer DR1/SU-8 and Microstrip Line Electrode

Abstract

A bias-free Mach–Zehnder interferometer electro-optic switch is demonstrated with a dye-doped polymer Disperse Red 1 (Tokyo Chemical Industry, Co., LTD, Tokyo, Japan)/SU-8 (MicroChem Corp., Newton, Massachusetts, USA) and microstrip line electrode. The device is carefully designed and optimized for bias-free function and high-speed switching using the three-dimensional beam-propagation method and extended point-matching method, and the switch is seriously fabricated by a wet-etching technique and inductively coupled plasma etching technique for good control of dimension parameters. The measured rise time and fall time at 1,550 nm are both at the level of ~10 ns. Owing to the bias-free function and nanosecond response speed, this switch exhibits potential applications of high-speed optical routing and exchanging.     

Relaxation mode analysis of nonlinear birth and death processes

Nonlinear birth and death processes with one variable are considered. The general master equations describing these processes are analyzed in terms of their eigenmodes and eigenvalues using the method of a WKB approximation. Formulas for the density of eigenstates are obtained. The lower lying eigenmodes are calculated to investigate long-time relaxation, such as relaxations of metastable and unstable states. Anomalous accumulation of the lower lying eigenvalues is shown to exist when the system is infinitesimally close to a critical or marginal state. The general results obtained are applied to some instructive examples, such as the kinetic Weiss-Ising model and a stochastic model of nonlinear chemical reactions.The work at UCSD was supported in part by the National Science Foundation under Grants MPS72-04363A03 and CHE75-20624.Adapted from the author's Ph.D. dissertation at University of Tokyo, December 1974.     

Simulation Study of High Intensity S-Band Photoinjector

In this paper, we report the results of simulation study of KEK/U.Tokyo S-Band photoinjector under the present new experimental condition. The aim of the simulation study is to transport high bunch charge with low emittance evolution.     

Measurement of Root Mean Square Granularity of X-ray Films Using a Commercial Film Scanner

Root mean square granularity of films are generally measured using a microdensito-meter, although it is costly and not easily available. To solve the cost problem, we tried to use an inexpensive commercial film scanner. Films with different densities were prepared and the relationship between densities by a diffuse densitometer and pixel values by a film scanner was obtained. We found that a linear relationship exists between rms granularity and a corrected standard deviation of pixel value that is available as an index granularity.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15-17, 2000 at the International Coference Center, Tokyo, Waseda University, Japan.     

Elements of Cost-Based Tolerancing

One goal for optical design is to assign tolerances so that the as-built systems satisfy all required specifications and have the lowest fabrication and assembly expense. Tolerances affect not only the image quality, but also the production cost. Thus tolerance assignment is a critical step in the optical design process. In this paper we discuss the essential elements of a cost-based tolerancing method. The paper concludes with an example comparing results from a cost-based tolerancing procedure with results from a conventional approach.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15-17, 2000 at the International Conference Center, Tokyo, Waseda University, Japan.     

A 40 GHz band SIS receiver using Nb/Al?AlOx/Nb array junctions

A 40 GHz band SIS mixer receiver has been built using Nb/Al–AlOx/Nb array junctions and a 4.3 K closed cycle helium refrigerator. The minimum conversion loss of the mixer is 2±1 dB and the single sideband receiver noise temperature (T_RX (SSB)) is as low as 110±10 K at 36 GHz. T_RX (SSB) is almost constant in the IF bandwidth of 600 MHz. The mixer saturation level is as high as 15 nW, which is comparable to the injected LO power.Nobeyama Radio Observatory (NRO), a branch of the Tokyo Astronomical Observatory, University of Tokyo, is a cosmic radio observing facility open for outside users.