Stable identification scheme for linear discrete-time systems

This paper is concerned with the problem of identifying parameters in stochastic systems described by single-input single-output linear discrete-time equations. A stable estimation error system is developed by using the extended Kalman filter technique and the concept of strictly positive real transfer function. The identifier corresponding to the estimation error system is constructed, and the convergence of parameter estimates to the exact values is proved under some bounded conditions. It is shown that the recursive maximum likelihood identifier and the recursive extended least squares identifier are obtained by neglecting the correction terms in the proposed identifier. Numerical examples for a fourth-order system are presented to illustrate the effectiveness of the proposed method.     

INFORMATION FILTERING FOR EMERGENCY MANAGEMENT

Information filtering is an intelligent function that selects the relevant messages and items of use or interest to the user from a large amount of incoming information. This function has become very important for the rapid development of network technology. This article focuses on information filtering for the management of emergency situations. We believe that special purpose-built "information filtering systems" should be developed to cope with the problem of information overload in emergency management. In this article, we first investigated features of information in emergent situations and then proposed an information filtering system for emergency management. The proposed system is composed of two parts: causal analysis and information classification. A prototype system has been developed and its effectiveness was evaluated by experiments.     

Propagation Characteristics of kHz Band PLC Signal on MV–LV Distribution System

The kHz band power line communication (PLC) is one of the convincing mediums of the communication system for smart meter reading. Data transmission between medium‐voltage (MV) and low‐voltage (LV) points to pass the transformer by PLC is interested. In this paper, the PLC signal propagation characteristics between points of MV at substation and LV at customer are calculated and analyzed. The results show that direct communication between points on MV distribution line and most LV customers is impossible due to large propagation losses at MV–LV transformer and on LV distribution line.     

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.     

EFFECT OF HIGH PRESSURE ON THE ACCUMULATION OF IMP AND ON THE STABILITY OF AMP DEAMINASE IN RABBIT SKELETAL MUSCLE

This study evaluated the effect of high pressure on rabbit skeletal muscle, specifically on the production of inosinic acid (IMP), one of “umami” components, and on the activity of adenosine triphosphate (AMP) deaminase, which plays a role in the conversion of AMP to IMP. By increasing the pressure (0.1 to 300 MPa), nucleotide analysis showed that IMP content in muscle increased instantly with a concomitant decrease in ATP content. The IMP content of muscle at 300 MPa was approximately 15% higher than with lower pressures (0.1–200 MPa) when stored for 1 week at 4C after pressurization. These results suggested that the metabolism of nucleotides in muscle was not significantly impaired by pressure treatment. At 300 MPa, AMP deaminase maintained approximately 70% of the activity at 0.1 MPa. In contrast, the activity of purified AMP deaminase was completely lost at 200 MPa, and irreversible conformational changes were observed by in situ fluorescence spectroscopy. These results indicated that purified AMP deaminase was irreversibly denatured under pressure as high as 300–400 MPa.     

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.     

Gelation Mechanism of Soybean 11S Globulin: Formation of Soluble Aggregates as Transient Intermediates

Thermal association-dissociation behavior of soybean 11S globulin was investigated by sucrose density gradient centrifugation and polyacrylamide gel electrophoresis. Soluble aggregates with a molecular weight of 8 × 10⁶ were formed when 0.5% and 5% protein solutions were heated for 1 min at 100°C. At the lower protein concentration, subsequent heating caused disappearance of the soluble aggregate followed by complete dissociation into acidic and basic subunits. At the higher concentration, however, subsequent heating caused formation of highly polymerized aggregates, and gel was formed after 5 min of heating. The soluble aggregates appear to be transient intermediates in the course of gel formation of 11S globulin.