Carrier‐envelope phase‐stabilized chirped‐pulse amplification system

We demonstrated a carrier‐envelope phase (CEP) stabilized chirped‐pulse amplifier system. This amplifier system is composed of grating based pulse‐stretcher and compressor, a regenerative amplifier and a multi‐pass amplifier. We employed a new pulse‐pick‐up method to select CEP stabilized seed pulses. This pulse selection method is different from established practice which is based on pulse train timing, but is based on CEP of seed pulse. We measured amplitude‐to‐phase noise conversion coefficient of microstructure fiber and evaluated the additional out‐of‐loop error of carrier‐envelope offset (CEO) control. We also investigated the effect of beam pointing of the measured fringe shift in self‐referencing spectral interference method. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(3): 35–42, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20334 Copyright © 2006 Wiley Periodicals, Inc.     

A study of the actual failure situation of XLPE cable and the order of priority of degradation diagnosis

We analyzed statistical data on failures due to dielectric breakdowns caused by water tree degradation in 6‐kV XLPE cables using the Hazard Analysis. The data used in this report reflect actual conditions of XLPE cables. The data are classified by the conductor size of the cables. Calculated failure rates were different for cables having different conductor sizes. In this report, the failure rates were calculated based on the information regarding conductor size, cable length, and cable age. The results obtained make it possible to quantitatively establish the order of the priority of degradation diagnosis. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(4): 50–58, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10301     

Changes in the morphology of cast nylon 6 through copolymerization

Correlations were made between several physical and mechanical properties and crystal morphology for copolyamides composed of caprolactam and either capryllactam or laurolactam as a minor comonomer. Incorporating a comonomer into the nylon 6 chain decreases the crystallinity and crystal size and, in addition, depresses the melting point of the polymer much more than predicted by the classical Flory theory on random copolymers. This fact, along with the change in the x-ray diffraction patterns, indicates that small amounts (up to 10 mole-%) of comonomer can enter the polymer crystals without any basic change in the α-form crystal structure. The variation of copolyamide densities with comonomer content also supports this theory. The initial moduli of the copolyamides, when tested above their glass transition temperatures, obey a linear relationship with the reciprocal of the amorphous content of the polymers. The impact strength increases dramatically with decreases in crystallinity and crystal size. Some of these materials have extremely large ultimate elongations and have glass transition temperatures below room temperature.     

Confidence Limits for Redundant-System Availability

s-Confidence limits are established for the Availability of a standby redundant system (1-out-of-N:G system) for both hot and cold spares consisting of several identical units and repair facilities. The failure and repair rates of the units are s-independent, constant, and estimated from test data.     

Preparation and characterization of stoichiometric CaFeO3

Stoichiometric CaFeO₃ was prepared and was characterized by crystallographic, magnetic and electrical measurements. A slight tetragonal distortion from the ideal cubic perovskite structure was found. The tetramolecular unit cell has a = 5.325 (3) A and c = 7.579 (5) A. The susceptibility showed a maximum at about 115 K and the temperature dependence of electrical resistivity changed from metallic to semiconductive in the vicinity of the magnetic transition temperature. These indicate a phase transition from the metallic-paramagnetic (the high-temperature phase) to the semiconductive-antiferromagnetic phase. The Mössbauer spectra indicated that a charge disproportionation 2Fe⁴⁺ → Fe³⁺ + Fe⁵⁺ associates with the transition.     

Effect of specimen thickness on the crack propagation and crack branching in delayed failure

The crack propagation and crack branching behaviors in delayed failure have been investigated on the specimens with various thickness ($\text{B = 1.5–10}\text{mm}$).The crack propagation velocity reveals a maximum value at a medium specimen thickness ($\text{B = 5}\text{mm}$). This fact can be understood by assuming the compound effect of two factors that the triaxiality of stress at crack tip as a driving force for hydrogen diffusion increases with increase of specimen thickness $\text{B}$, and that the invasion of hydrogen atoms from specimen surface increases with decrease of $\text{B}$.The stress intensity factor at crack branching, $\text{K}{}_{\mathrm{IB}}$, increases with decrease of specimen thickness $\text{B}$, and when B is 1.5 mm, the specimen fractures without showing the crack branching. The latter fact can be explained by connecting the necessary and sufficient conditions for crack branching with the decrease in height of plastic region at the crack tip in thin specimens.     

Electron Hall mobility calculations and alloy scattering in Ga0.47In0.53As

Electron Hall mobilities are calculated by the iterative technique in Ga0.47In0.53As. From the curve fitting to the most recent experimental data over a wide range of temperature, the alloy scattering potential close to the Phillips electronegativity difference is derived. The alloy scattering-limited mobility has a temperature dependence of T?1/2 and shows no anomalous behaviour.     

Strain-induced anodic dissolution of Cu single crystals—effects of specimen geometry and slip morphology

Specimen geometry with respect to slip deformation and slip morphology have been examined in a study of strain-induced anodic dissolution of Cu single crystals. It has been found that a sample, whose geometry leads to the largest exposure of fresh (111) slip planes onto the original surfaces, shows the largest anodic dissolution on straining. However, the amount and rate of dissolution are unaffected by slip morphology or dislocation density. It has been calculated that approximately seven layers of Cu atoms dissolve from the freshly formed active (111) planes until the planes become inactive.