Effect of copper addition on the β-phase formation rate in FeSi2 thermoelectric materials

The transformation kinetics of the β-phase from an as-solidified structure composed of α and ε in the Fe–Si system was investigated by using rapidly, unidirectionally or conventionally solidified FeSi₂ alloys containing a small amount of Cu (0.1–1 at%). The addition of Cu decreased the size of primary ε and slightly changed the solidified eutectic morphology. The solubility of Cu in the α-Fe₂Si₅ phase was estimated to be less than 0.2 at%. A needle-like Cu enriched phase was newly formed in the conventionally solidified alloys containing more than 0.2 at % Cu. Microdifferential thermal analysis (DTA) clearly showed that the addition of Cu drastically accelerated β-phase formation. X-ray diffraction analysis and microstructural observation of the isothermally heat-treated specimens showed that Cu addition was effective in increasing the rate of eutectoid decomposition (α → β + Si) and the initial stage of the peritectoid reaction (α + ε → β). For complete β formation, heat treatment for a long time was still required because it took a long time for the coarse ε-phase in the slowly solidified alloy to be eliminated by peritectoid reaction. The effect of Cu depended on the annealing temperature. The decomposition rate of α in the Cu-added cast specimen was about 15 times higher at 1073 K than that of the binary cast specimen and exceeded more than 30 times at 873 K. This revised version was published online in November 2006 with corrections to the Cover Date.     

A Simple Method to Determine Synchronous Machine Quantities Using Frequency Characteristics of Operational Impedances

This paper presents a simple method for determining synchronous machine quantities: d‐ and q‐axes time constants and reactances. This method determines them only by drawing additional lines in the frequency characteristics of operational impedances. A new systematic drawing strategy for determining transient/subtransient open‐circuit time constants and the d‐axis transient reactance is proposed. The frequency characteristics of operational impedances are obtained by the standstill dc test using a small dc power supply. Since the rotational test becomes unnecessary, the proposed method is suitable for tests in a factory. The validity of the proposed method was demonstrated with a numerical calculation example on a large‐capacity machine (800 MVA, 25 kV, two poles, 60 Hz) and an implementation test on a small‐capacity machine (10 kVA, 200 V, 31.9 A, four poles, 50 Hz).     

Chiral Electrodeposition by the Rotation in a Vertical Magnetic Field

The roles of the rotations in the process of chirality appearance in magnetoelectrodeposition were theoretically clarified.Electrodeposition in a vertical magnetic field induces a macroscopic fluid rotation called vertical MHD flow(VMHDF)over the electrode surface.Inside the rotation,minute numerous micro-vortexes called micro-MHD flow(MMHDF)arise from 2D and 3D nucleation,which interact with the mass flux of metallic ion,yielding chiral deposits with the characteristic features called micro-and nano-mystery circles.Generally,numerous vortexes always keep chiral symmetry,forming four types of vortexes,i.e.,with the combination of upward or downward and clockwise or counterclockwise.However,ionic vacancy acting as an atomic scale lubricant is created in electrodeposition,which gives a restriction to the vortexes;the bottom of an upward vortex covered with ionic vacancies becomes a free surface without friction,whereas the bottom of a downward vortex exposed without ionic vacancies remains rigid with friction.The rotation of VMHDF donates a precession to the upward vortexes to rotate in the same direction,which finally yield a chiral deposit.The similar effect to that of VMHDF can be expected for the system rotation(SR),where an electrolytic cell rotates in a vertical magnetic field.In this case,the SR gives the reverse rotation to the upward vortexes,so that a deposit with reverse chirality is obtained.     

Pigment Changes in Parsley Leaves during Storage in Controlled or Ethylene Containing Atmosphere

Pigments were monitored in parsley leaves stored in air, air + 10 ppm C₂H₄, or 10% O₂+ 10% CO₂ controlled atmosphere (CA). Chlorophylls a and b, as determined with HPLC, decreased sharply in leaves held in air or air + 10 ppm C₂H₄. The decrease was less in leaves held in 10% O₂ and 10% CO₂ CA. The oxidized product of chlorophyll a, 10-hydroxychlorophyll a, did not accumulate and chlo-rophyllide accumulated minimally. Xanthophylls decreased but new pigments, suspected to be esterified xanthophylls, formed with yellowing of leaves. Neither the pathway of Chl degradation or xantho-phyll products were altered by C₂H₄ or CA.     

Debittering Mechanism in Bitter Peptides of Enzymatic Hydrolysates from Milk Casein by Aminopeptidase T

The bitter peptide fraction present in casein hydrolysates obtained by using three proteases (subtilisin, papain and trypsin) was treated with aminopeptidase T from Thermus aquaticus YT-1. The bitterness of the bitter peptide fraction could be decreased, and it sometimes disappeared completely, with an increase in free amino acids. The percentages of total free amino acids released from each bitter peptide fraction (subtilisin, papain and trypsin) by aminopeptidase digestion for 20 hr were approximately 11%, 8.7%, and 6.5%, respectively. Bitter peptide (α_s1-CN f91-100) was isolated from a tryptic hydrolysate of casein by HPLC, its threshold value of bitterness being 2.9 ppm (w/v). The peptide (α_s1-CN f96-100) obtained from the amino peptidase digestion of this bitter peptide showed no bitterness.     

Optimized Logarithmic Roller Crowning Design of Cylindrical Roller Bearings and Its Experimental Demonstration

A logarithmic profile is essentially an optimal geometry for rolling machine elements such as bearing rollers and raceways. Under most conditions of loading, it yields lower stresses to give longer endurance. Lundberg first suggested the basic profile, and some researchers followed him by modifying it to satisfy engineering requirements. In this article, the authors propose a mathematical optimization method for logarithmic profiles in roller bearing applications. Moreover, rolling contact fatigue life tests are carried out to make a comparison among logarithmically crowned, standard partially crowned, and modified partially crowned rollers. Results show that the logarithmically crowned rollers are beyond the modified partially crowned rollers in fatigue life, especially in poor lubrication conditions, although the logarithmic rollers require less workload to process the crowning.     

Study on Construction of Industrial Large‐Scale Battery System

This paper proposes a construction method for battery systems that are widely used in industries. The battery system uses a building block structure combined with a battery module, whose capacity is less than 1 kWh. To manage the building block structured system, we propose a hierarchical structured management method. In each hierarchy, the voltage and temperature of the battery are monitored, and the information necessary for calculating charge states and detecting faults are sent to the upper hierarchy for the state management of the lower hierarchy. Furthermore, to ensure the safety during maintenance activities, we provide a guidance for understanding the insulation structure for the battery module, and develop a ground fault detection method that detects a decline in the insulation performance by using a rising method. For the experiment, we use a 30‐kWh trial manufacture battery system combined with the hierarchical management method. We verify that charge states and faults are detected in the battery of the system, and confirm that the system can be charged and discharged safely.     

Identification of Low Molecular Weight Peptides in Gouda-type Cheese and Evidence for the Formation of These Peptides from 23 N-terminal Residues of αsl-casein by Proteinases of Streptococcus cremoris H61

Water-soluble extracts from Gouda-type cheese in a 0.05M sodium citrate buffer at pH 4.0 were fractionated by high-pressure liquid chromatography (HPLC) before and after ripening for 1, 2, and 3 months. Three major peptides were isolated from each sample of extract, but size of the peaks increased with ripening period. The amino acid compositions of these peptides were similar to fragments of αsl-casein, i.e., αsl-CN(fl-9), αsl-CN(fl-13) and αsl-CN(fl-14). αsl-CN(fl-23) was hydrolyzed by cellular proteases of Streptococcus cremoris H61; seven main peptides including αsl-CN(fl-9), αsl-CN(fl-13) and αsl-CN(fl-14) were isolated and characterized by HPLC. This suggests that hydrolysis of αsl-CN(fl-23) by lactic acid bacterial proteinase is one of the main pathways of αsl-casein degradation during Gouda-type cheese ripening.     

A Conceptual Design Study for the Error Field Correction Coil Power Supply in JT-60SA

This paper describes a conceptual design study for the circuit configuration of the Error Field Correction Coil (EFCC) power supply (PS) to maximize the expected performance with reasonable cost in JT-60SA.The EFCC consists of eighteen sector coils installed inside the vacuum vessel,six in the toroidal direction and three in the poloidal direction,each one rated for 30kA-turn.As a result,star point connection is proposed for each group of six EFCC coils installed cyclically in the toroidal direction for decoupling with poloidal field coils.In addition,a six phase inverter which is capable of controlling each phase current was chosen as PS topology to ensure higher flexibility of operation with reasonable cost.     

Functional Properties of a Peptide of 23 Residues Purified from the Peptic Hydrolyzate of asl-CASEIN: Changes in the Emulsifying Activity During Purification of the Peptide

The pH 4.6-soluble fraction of the peptic hydrolyzate of as 1-casein contained the 23 N-terminal residues, αsl-CN(fl-23), as a major pep-tide. Reversed-phase HPLC indicated that small amounts of other peptides such as αsl-CN(f154-199) were also contained in this fraction. By removing of these peptides, the emulsifying activity (EA) of the αsl-CN(fl-23) fraction was markedly decreased. However, when the removed peptide fraction was added to the purified αsl-CN(fl-23), the EA was increased. Some synergistic effect in the emulsification seemed to exist between αsl-CN(fl-23) and the other peptides. Although the purified αsl-CN(fl-23) had low EA values at neutral pH levels, it showed high emulsifying and surface activities in the acidic pH region.