Use of spatial phase difference method to detect microwaves associated with stator coil partial discharge in a generator

This paper presents a new system for detecting electromagnetic waves emitted from partial discharges (PD) due to material defects in high-voltage electric machinery and apparatus. PD is a symptom and/or a direct cause of the deterioration of insulation systems used in high-voltage stator coils. This system can detect PD by using the spatial phase information of the microwaves emitted from PD, which are voltage pulses of very short duration. We describe the properties of this system which is composed of two double-ridge-guide-horn antennas, two preamplifiers, a gigahertz interference receiver (GHz-2ch-down-converter) of original design, two A/D (analog to digital) converters, and a personal computer. We experimentally show that this system can be used for detection of the microwaves emitted by PD occurring in the stator coil. The result of this work is the development of a new noncontact PD detection system for generators, which can be operated by station personnel. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 121(2): 16–26, 1997     

New method of off-line adjustment of feed-forward control for fossil-fired plant main control system

In fossil-fired power plants, it is important to improve the control accuracy of, for example, main steam pressure and temperature during load increase/decrease. This paper focuses on temperature control, which is the most difficult control due to the nonlinearity and large dead time of power plants. First, we construct a simplified model of a power plant that has first-order lag and dead time. Second, a calculation method of feed-forward signal is proposed from the temperature measured during load increase/decrease. Optimal feed-forward signals were decided from various lead increase/decrease rates and load change widths, followed by generalization of feed-forward control at any rate and load change width. Neural network was applied for this generalization. The proposed method was evaluated by a detailed simulator that represents accurately the dynamics of power plants. © 1997 Scripta Technica, Inc. Electr Eng Jpn 119(1): 55–61, 1997     

自确认传感器技术研究

利用自确认传感器的功能框图,介绍了自确认传感器的工作原理,并且对自确认传感器和传统传感器进行了比较,给出了自确认传感器的优势,最后从传感器故障诊断和数据恢复,自确认传感器硬件开发和自确认传感器开发、研制三个方面介绍了自确认传感器的研究进展。     

Structural Change of Potato Starch Granules by Ball-mill Treatment

Molecular change of potato starch granule by ball-mill treatment was investigated. Starch granule still retained its whole figure after 320h, treatment, but its surface changed extremely rough. Water absorption activity extremely increased by 10h treatment. Amylase susceptivity of starch increased according to treatment time. X-ray diffraction pattern lost its peak and enthalpy on DSC decreased 70% after 20h treatment. Iodine color reaction value decreased 30% and λ max shifted hypso-chromic 15nm in the both cases of debranched and non-debranched samples after 20h treatment, and this indicates amylose was also degraded by the treatment. However, the peak of amylose decreased 10% and the peak of amylopectin decreased 10% on each GPC of branched and non-debranched samples after 20h treatment. GPC (Toyopearl HW-65) of 320h treated sample shows only one peak, but its debranched sample shows similar pattern to that of non-treated sample on HPAEC. ¹³C-solid state NMR spectra suggest that total disruption frequency is fairly low after long this treatment.     

Bifidobacterial GH146 β-l-Arabinofuranosidase (Bll4HypBA1) as the Last Enzyme for the Complete Removal of Oligoarabinofuranosides from Hydroxyproline-Rich Glycoproteins

In plant cell walls, the hydroxyproline-rich glycoproteins (HRGPs) such as extensin contain oligoarabinofuranoside linked to a hydroxyproline (Hyp) residue. The mature arabinooligosaccharide was revealed to be a tetrasaccharide (α-l -Araf-(1→3)-β-l -Araf-(1→2)-β-l -Araf-(1→2)-β-l -Araf, l -Araf₄), whose linkages are targets of the bifidobacterial and Xanthomonas arabinooligosaccharide-degrading enzymes. The l -Araf₄ motif was cleaved by GH43 α-l -arabinofuranosidase (Arafase) and converted to an l -Araf₃-linked structure. The latter is then cleaved by GH121 β-l -arabinobiosidase (HypBA2), producing β-l -Araf-(1→2)-l -Ara (β-l -arabinobiose) and mono-β-l -Araf linked to the HRGP backbone. In bifidobacteria, the β-l -arabinobiose is then hydrolyzed by GH127 β-l -Arafase (Bll1HypBA1), a mechanistically unique cysteine glycosidase. We recently identified the distantly related homologue from Xanthomonas euvesicatoria as GH146 β-l -Arafase along with paralogues from Bifidobacterium longum, one of which, Bll4HypBA1 (BLLJ_0089), can degrade l -Araf₁-Hyp in a similar way to that of GH146. As the chemical synthesis of the extensin hydrophilic motif 1 a , which possesses three distinct linkages that connect four oligoAraf residues [Hyp(l -Araf_n) (n=4, 3, 1)], was achieved previously, we precisely monitored the step-wise enzymatic cleavage of 1 a in addition to that of potato lectin. The results unequivocally revealed that this enzyme specifically degrades the Hyp(l -Araf₁) motif.