Decomposition of Mullite by Silica Volatilization

Thermal decomposition of mullite into corundum was investigated using a high-temperature X-ray single-crystal camera equipped with a gas-flame furnace and by scanning electron microscopy and electron probe microanalysis (EPMA). When heated to ∼1750°C, mullite decomposed to corundum by the liberation of the SiO₂ component with topotaxial relations of:

• (1) 

  (310)_mull∥(001)_cor; [001]_mull∥[110]_cor
• (2) 

  (130)_mull∥(001)_cor; [001]_mull∥[110]_cor
• (3) 

  (110)_mull∥(001)_cor; [001]_mull∥[110]_cor

Thus, it was considered that, when mullite decomposed into corundum, their oxygen close-packed planes were almost preserved. The SEM photographs showed that the crystals of the developed corundum are prismatic and ∼5 μm wide. The EPMA showed that the phase boundary between mullite and developed corundum is discontinuous.     

The Influence Analysis that a Phase Characteristic of the High‐Level Earthquake Gives to Vibration Response Characteristic of the 550‐kV Disconnectors

We developed the 550‐kV disconnectors that strengthened earthquake proofing by the addition of the damper unit and weight reduction of conductive part based on the damage of the 550‐kV disconnectors by the Great East Japan earthquake (March 11, 2011) and inspected the earthquake proofing performance by shake table test. In shake table test, we performed the test by the artificial seismic wave that varied in phase characteristic in addition to the test by resonance method. And, in a high‐level earthquake area, we analyzed it about the influence that a phase characteristic of the artificial seismic wave gave to stress to occur in disconnectors. As a result, it is thought that the stress to occur in disconnectors is decided by a primary natural frequency basically because a bending strain to occur to the disconnectors in the time when the resonance frequency ingredient becomes the big acceleration response value grows big. But, on a particular phase condition, it was confirmed that the bending strain to occur in disconnectors might grow big conspicuously. As for this, the possibility is thought about by influence of higher natural frequency doing superposition.     

Parameter identification of distributed parameter systems in the presence of measurement noise

A new approach to recursive parameter identification of second-order distributed parameter systems in the presence of measurement noise under unknown initial and boundary conditions is proposed. A two-dimensional low-pass filter is introduced to pre-filter the observed data corrupted by measurement noise. The low-pass filter is designed in the continuous time-space domain and discretized by bilinear transformation. Thus a discrete estimation model of the system under study is easily constructed with filtered input-output data for recursive identification algorithms. The recursive least squares method is still efficient in the presence of low measurement noise if the filter parameters are designed so that the noise effects are reduced sufficiently. Using filtered input data as instrumental variables, a recursive instrumental variable method is also presented to obtain consistent estimates when the digital low-pass filters are not designed successfully or when the output data is corrupted by high measurement noise. Illustrative examples are given to demonstrate the applicability of the proposed methods.     

Investigation of Water Tree Degradation in Dry‐Cured and Extruded Three‐Layer (E‐E Type) 6.6‐kV Removed XLPE Cables

Dry‐cured and extruded three‐layer (E‐E type) 6.6‐kV cross‐linked polyethylene (XLPE) cables were introduced into electric power systems more than 30 years ago, but they do not experience failures because of water tree degradation. Also, the degradation index of water treeing for these cables has not been established. Therefore, investigating results of residual breakdown voltage and water tree degradation of these cables will help us plan for cable replacement and determine water tree degradation diagnosis scheduling, and will be fundamental data for cable lifetime evaluation. In this study, the authors measured the ac breakdown voltages of dry‐cured and E‐E type 6.6‐kV XLPE cables removed after 18 to 25 years of operation and observed the water trees in their XLPE insulation. As a result, it was observed that breakdown voltages were larger than the maximum operating voltage (6.9 kV) and the ac voltage for the dielectric withstanding test (10.3 kV). Water trees were mainly bow‐tie water trees and their maximum length was approximately 1 mm. Although the number of measured cables was limited, the lifetime of this type of cable was estimated to be approximately 40 years, even experiencing water immersion.     

Effects of Microwave Heating on Lipoxygenase and Trypsin Inhibitor Activities, and Water Absorption of Winged Bean Seeds

Lipoxygenase and trypsin inhibitors in dry whole winged bean seeds were completely inactivated after microwave heating for 3.0 and 5.0 min, respectively. The soaking of the seeds, prior to microwave heating, considerably decreased the heating times needed to inactivate lipoxygenase and trypsin inhibitor. Furthermore, microwave heating was effective in increasing the rate of water absorption of the seeds.     

ADDUCT FORMATION OF β-DIKETONATO LANTHANOIDS(III) WITH CARBOXYLIC ACIDS HAVING HYDROXYL AND METHOXYL GROUPS

Adduct formation of 2-thenoyltrifluoroacetonato(tta) lantha-num(III), europium(III), and ytterbium(I II) with α-pheny 1 1 actic, α-methoxy phenyl acetic, salicylic, and o-methoxy benzoic acids in chloroform has been studied by solvent extraction technique. It has been found that 1anthanoid(111) chelates form more stable adducts with these carboxylic acids in the sequence: Yb(tta)₃ < Eu(tta) ₃ < La(tta) ₃. The adduct formation constants as well as the separation factors obtained as the ratio of the constants between a pair of metals are the largest for α-phenyl lactic acid among these acids. The characteristics with α-phenyl 1actic acid would be caused by the action as bidentate unlike benzoic acid derivatives which work as monodentates owing to the internal complexa-tion through hydrogen bonding.     

α-HYDROXYCARBOXYLIC ACID AS ADDUCT FORMING LIGAND FOR EXTRACTION OF LANTHANIDE(III)

Lanthanide(lII) chelates with 1,1,1 -trif luoro-5,5-dimethyl-2,4-hexanedione form adducts with benzilic acid, an a-hydroxycar-boxylic acid, in chloroform. The order of. the adduct formation constants in magnitude is: La^m> Eu^m> Yb^m although it is known that the stability constant of lanthanide(III) complexes with α-hydroxycarboxylic acids in aqueous solutions increases with increasing atomic number.     

Limonoids in Pummelos [Citrus grandis (L.) Osbeck]

Juice and seeds from 16 cultivars of mature pummelo fruits were analyzed for limonoid content. Pummelo juice contained an average of 18 ppm limonin and 29 ppm total limonoid glucosides. Compared to other juices, ptmnnelo contained very high concentrations of limonin and very low concentrations of limonoid glucosides. Limonin, nomilin, obacunone and trace amounts of deacetyhromilin were found in pummelo seeds. The 17–β-D-glucopyranoside derivatives (glucosides) of nomilin, nomilinic acid and obacunone were also present. Total limonoid aglycone concentration in the seeds ranged from 773 ppm to 9,900 ppm and total limonoid glucosides ranged from 130 ppm to 1,912 ppm.     

Crystal Structure and Defects of Ordered (Pb1-xCax)TiO3

Crystal structure and defects of ordered ((Pb_{1- x} Ca _x )TiO₃ ceramics have been investigated by transmission electron microscopy. The structure is determined to be tetragonal, belonging to point group 4 mm . Pb and Ca are in an ordered fcc arrangement on the A sites. In addition to the chemical ordering, there is ordering due to atomic shuffling or what has been referred to as electrical ordering. Two distinct sets of planar defects are observed in the same region. One set of planar defects are identified as antiphase boundaries that are the results of chemical ordering and the other set are displacement boundaries that are the results of electrical ordering.