Control methods and compensation characteristics of a series active filter for neutral conductor

With an increase in the number of electronic devices, such as personal computers, connected to power distribution lines in commercial buildings, problems associated with their use, such as voltage distortion on utility outlets and excessive neutral current on the distribution lines, become more and more serious. This paper shows control methods and compensation characteristics of series active filters connected to the neutral conductor. The distinctive functions of the proposed active filter are the mitigation of third harmonic voltage and the reduction of neutral current in three‐phase four‐wire distribution systems. The required kVA rating of the proposed active filter is less than 10% of that of the harmonic producing leads. A control method of the DC capacitor voltage on the active filter circuit is also described. It was experimentally demonstrated that one of these two functions of the active filter (to mitigate harmonics or to reduce the neutral current) can be realized selectively and that the DC capacitor voltage of the active filter can be regulated to a desired value. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(4): 53–63, 2006; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20227     

Continuous fatigue level estimation for the classification of fatigued bills based on an acoustic signal feature by a supervised SOM

Fatigued bills have a harmful influence on the daily operation of automated teller machines (ATMs). To make the classification of fatigued bills more efficient, the development of an automatic fatigued bill classification method with a continu ous fatigue level is desirable. We propose a new method to estimate the bending rigidity of bills using the acoustic signal feature of banking machines. The estimated bending rigidities are used as the continuous fatigue level for the classification of fatigued bills. By using a supervised self-organizing map (SOM), we effectively estimate the bending rigidity using only the acoustic energy pattern. The experimental results with real bill samples show the effectiveness of the proposed method. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

A reliable method for classification of bank notes using artificial neural networks

We present a method based on principal component analysis (PCA) for increasing the reliability of bank note recognition machines. The system is intended for classifying any kind of currency, but in this paper we examine only US dollars (six different bill types). The data was acquired through an advanced line sensor, and after preprocessing, the PCA algorithm was used to extract the main features of data and to reduce the data size. A linear vector quantization (LVQ) network was applied as the main classifier of the system. By defining a new method for validating the reliability, we evaluated the reliability of the system for 1200 test samples. The results show that the reliability is increased up to 95% when the number of PCA components as well as the number of LVQ codebook vectors are taken properly. In order to compare the results of classification, we also applied hidden Markov models (HMMs) as an alternative classifier. This work was presented, in part, at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24#x2013;26, 2003     

Fluid flow and heat transfer in the transition process of natural convection over an inclined plate

The present study deals with fluid flow and heat transfer in the transition process of natural convection over an inclined plate. In order to examine the mechanism of the transition process, experiments on the flow and heat transfer were performed for various plate inclination angles in the range of 20 to 75°. The wall temperature and fluid flow fields were visualized using a liquid crystal sheet and fluorescent paint, respectively. The visualization confirmed that separation of a boundary layer flow took place, and the onset point of streaks appeared over the plate wall when the modified Rayleigh number exceeded a characteristic value for each inclination angle. The local Nusselt number in the transition range was proportional to the one‐third power of the local modified Rayleigh number. By introducing a nondimensional parameter, a new correlation between visualizations of the flow and temperature fields and heat transfer was proposed. © 2001 Scripta Technica, Heat Trans Asian Res, 30(8): 648–659, 2001     

Load‐following control for dispersed generators using a PI controller

Recently, there has been growing interest in utilizing dispersed generation systems, which are grouped into micro turbine systems, co‐generation systems, and so on, as a substitute for fuel oil energy and a technology to prevent global warming. Since start‐up time of dispersed generation systems is short, it is possible to operate systems to supply load power corresponding to a demand. Moreover, PPSs (Power Producers and Suppliers) can participate in a power retail sales company, since deregulation of electric utilities was instituted in March 2000. However, PPSs have to keep instantaneous generating power commissioning rule, to maintain supply‐and‐demand balance between customer and supplier. Therefore, in this paper, we examine instantaneous generating power commissioning for dispersed generators where start‐up time is short and it is possible to operate systems to supply a power load corresponding to a demand. We adopt a PI controller as a controller. The system is composed of double control loop in inner loop and in outer loop. In inner loop electric power is controlled and in outer loop electric energy is controlled. The controller parameters are designed using the pole‐placement technique. The effectiveness of the proposed control system is confirmed by simulations. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(2): 58–66, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10200     

Position control for ultrasonic motors using backstepping control and dead‐zone compensation with fuzzy inference

The ultrasonic motor has comparatively high nonlinearity which varies with driving conditions, and possesses a variable dead zone in control input associated with the applied load torque. The dead zone is a problem for industrial applications and it is important to eliminate the dead zone in order to improve control performance. This paper proposes a new position control scheme for ultrasonic motors to overcome the dead zone. The dead zone is compensated by fuzzy inference, and backstepping control performs accurate position control. Compared with model reference adaptive control, which uses an augmented error, backstepping control can analyze a transient response. Mathematical models are formulated and experimental results show the effectiveness of the proposed position control scheme. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(1): 69–77, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20016     

Toxicity in rats fed diet containing iron lactate for 26 weeks

In order to characterize the toxicity of iron lactate, a 26-week feeding study was performed in male and female F344 rats. Animals were divided into 2 groups, and given diet containing iron lactate at concentration of 0 or 2%. No animals died during the administration period. Body weight gain was suppressed in both sexes of the 2% group compared with the 0% group. Hematologically, anemia was observed in male of the 2% group. Serum alkaline phosphatase decreased in both sexes of the 2% group. The spleen weight of both sexes and kidney weight of females were higher in the 2% group than in the 0% group. Lipid peroxide increased not only in the liver and the kidney homogenates of treated males and females, but also in the serum of treated females. Histopathologically, iron deposition was observed in the liver, the kidney and the spleen of treated males and females, and in the intestine of treated females. The present results indicate that the iron lactate administration caused iron deposition in the liver and the other several organs, resulting in lipid peroxidation in these organs.