A highly transparent and thermally stable copolymer of 1‐adamantyl methacrylate and styrene

Thermal and optical properties of copolymers of 1‐adamantyl methacrylate (AdMA) and styrene (St) prepared by free radical polymerization in the bulk are investigated. The copolymer forms an azeotrope when the composition is AdMA/St = 55/45 mol%. The glass transition temperature and decomposition temperature of the azeotropic copolymer are 170 and ca 340 °C, respectively. The refractive index increases nonlinearly with St content from 1.522 to 1.591. The light scattering loss at 633 nm is 28.1 dB km^?1, which is less than half of that of polystyrene. The total optical loss including molecular vibrational absorption, which is evaluated using a copolymer‐based optical fiber, is 292–645 dB km^?1 at 500–700 nm. These values correspond to transmittances of 86–93% for a 1 m optical path length. © 2014 Society of Chemical Industry     

Effects of Neodymium Concentration on Optical Characteristics of Polycrystalline Nd:YAG Laser Materials

A neodymium-doped yttrium-aluminum garnet (Y₃A1₅O₁₂, YAG) (Nd:YAG) ceramic that contained 0.3–4.8 at.% neodymium additives and exhibited nearly the same optical properties as those of a single crystal was fabricated by a solid-state reaction method using high-purity powders. Although the integrated absorption intensity of the ²H_9/2+⁴F_5/2 bands simply increased as the neodymium concentration in the YAG ceramics decreased, the fluorescence intensity of the 2.4 at.% Nd:YAG ceramic was the strongest among Nd:YAG ceramics with various neodymium concentrations and a 0.9 at.% Nd:YAG single crystal. An oscillation experiment was performed on a continuous-wave (cw) laser with a diode-laser exciting system using those ceramics and the single crystal. The oscillation threshold and slope efficiency in that analysis were 309 mW and 28%, respectively, for the 1.1 at.% Nd:YAG ceramics and 356 mW and 40%, respectively, for the 2.4 at.% Nd:YAG ceramics. The lasing characteristics of the ceramics in the present work were superior to those of a 0.9 at.% Nd:YAG single crystal that was fabricated by the Czochralski (Cz) method.     

Measurement of Thermal Diffusivity at Low Temperatures Using an Optical Reflectivity Technique

An experimental arrangement has been developed for measuring the transient temperature responses and the thermal diffusivities of foil materials in the range of 10 to 300K by using the optical reflectivity technique. The cryogenic system with optical windows is designed to provide temperatures from 10 to 300 K. The front surface of a foil specimen is heated by a pulsed Nd:YAG laser. In situ measurement of the reflectivity of a continuous-wave He–Ne laser at the rear surface is conducted on the microsecond time scale. Using the temperature dependence of reflectivity, the transient temperature response is deduced. The thermal diffusivity is obtained by fitting Parker's formulae to the experimental data on temperature rise. Stainless-steel foils are chosen as samples and are studied in the region from 10 to 300 K. The accuracy is examined by comparing the present results with the theoretical temperature responses and thermal diffusivity data from the literature. Good agreement is observed.     

Stability analysis of continuous-time periodic systems via theharmonic analysis

Asymptotic stability of finite-dimensional linear continuous-time periodic (FDLCP) systems is studied by harmonic analysis. It is first shown that stability can be examined with what we call the harmonic Lyapunov equation. Another necessary and sufficient stability criterion is developed via this generalized Lyapunov equation, which reduces the stability test into that of an approximate FDLCP model whose transition matrix can be determined explicitly. By extending the Gerschgorin theorem to linear operators on the linear space l₂, yet another disc-group criterion is derived, which is only sufficient. Stability of the lossy Mathieu equation is analyzed as a numerical example to illustrate the results     

A general framework for debugging

The state of the art of debugging is examined. A debugged process model that serves as the basis of a general debugging framework is described. The relationship of the model to traditional debugging processes and support tools is discussed. A minimal set of requirements for a general debugging framework is described in terms of both the theory behind debugging methodologies and the support tools. An execution monitor, Eden, that serves as a debugging tool within this general framework is described     

Structural and electronic properties of CuInSe2

Structural investigation on monocrystalline CuInSe₂ samples has been made. From the single crystal results, the space group of CuInSe₂ was confirmed to be Iˉ42d and the crystal solidification direction was investigated. Compositional uniformity of the ingots was established by EPMA and it was found that the indium concentration was greater than that for copper. Systematic annealing experiments were carried out in vacuum at different temperatures (as low as 160° C) and for different times. Large variation in resistivity was observed after the annealing treatment. P-type samples were found to convert to n-type after the heat-treatments.     

Fast microwave detection system for coherent synchrotron radiation study at KEK: Accelerator test facility

A fast room temperature microwave detection system based on the Schottky Barrier-diode detector was created at the KEK ATF (Accelerator Test Facility). It was tested using Coherent Synchrotron Radiation (CSR) generated by the 1.28 GeV electron beam in the damping ring. The speed performance of the detection system was checked by observing the CSR from a multi-bunch (2.8 ns bunch separation time) beam. The theoretical estimations of CSR power yield from an edge of bending magnet as well as new injection tuning method are presented. A very high sensitivity of CSR power yield to the longitudinal electron distribution in a bunch is discussed.     

Stability,cure properties,and applicability as one part adhesives of systems of divalent metal salts of mono(hydroxyethyl) phthalate–anhydride–bisepoxide

Heterogeneous curable compositions of divalent metal salts of mono(hydroxyethyl) phthalate–anhydride–bisphenol A diglycidyl ether (BADG) systems were prepared by merely mixing these components at room temperature. Stability at room temperature and cure properties at high temperature of the compositions were investigated for evaluating their applicability as one part adhesive. It was found that the systems containing Mg were generally more stable than those containing Ca. Similarly, at 150°C the Ca-containing systems showed generally shorter gelation time than the Mg-containing ones, due to the fact that the Ca salt dissolves more rapidly and enters into the addition reaction with the anhydride, leading to the faster appearance of the catalytic activities of the Ca carboxylate group. Among the various combinations of components, the metal salt–succinic anhydride (SA)–BADG systems were stable at room temperature for more than 6 months and rapidly cured at high temperature, showing excellent adhesive properties. This result indicates that the SA-containing systems should be of interest in applications to one part adhesives.     

A compact full MMIC module for Ku-band phase-lockedoscillators

A compact Ku-band phase-locked oscillator module has been developed in a full MMIC (monolithic microwave integrated circuit) configuration. The module includes an MMIC voltage-controlled oscillator, an analog frequency divider, and interstage amplifiers. The constituent monolithic chips are integrated in a very small single-package module and operate at the target frequencies without any external trimming or matching network. The oscillator is tuned more than 1 GHz with a constant output amplitude. The frequency-divided output is also obtained over the whole tuning range. Spurious output is not found at any frequency up to 22 GHz. In spite of the very low-Q factor of GaAs monolithic circuitry, the oscillator phase noise exhibited is less than -80 dBc/Hz, due to the high-gain, high-speed phase lock