Study on Lightning Protection Measures for Distribution Lines and Customer Equipment against Back Flow Lightning Current from Radio Communication Station

Recently, with the expansion of communication network areas, the number of radio communication stations built in the neighborhood of customer houses has increased. If lightning strikes a communication radio tower, part of the lightning current flows into the distribution line and into customer houses. This may cause the failure of distribution lines or customer equipment. To protect distribution lines and customer equipment from lightning faults, it is necessary to analyze the surge phenomena in distribution lines and customer equipment and take appropriate protection measures. In this study, we examined the effect of lightning protection measures for distribution lines and customer equipment against lightning strikes to a communication tower. First, using an actual‐scale test distribution line, we measured the lightning current flowing into distribution lines and customer equipment. Second, we quantitatively examined the effect of lightning protection measures by lighting surge analysis while changing each parameter. From the experimental and analytical results, we show that the proposed protection measures can reduce the lightning current flowing into distribution lines and customer equipment.     

基于应变设计的大应变X100管线钢的成分设计与开发

介绍了日本新日铁公司开发的适用于基于应变设计的大应变低Mo含量高强度X100管线钢的成分设计,在实验室研究了Mo和Cr对强化能力的影响,并进行了低Mo含量16 mm厚度X100管线钢管的试生产。研究了试生产的低Mo含量X100大应变管线钢管热力时效前后的力学性能,如落锤撕裂试验性能以及母材和焊缝区的V形缺口夏比冲击性能等。试验结果表明,试生产的低Mo含量X100大应变管线钢管具有优异的低温韧性和焊缝韧性。     

A self-organizing time-optimal controller†

A kind of self-organizing controller is proposed, which can accomplish time-optimal control of the unknown plant through adaptation. The self-organizing controller consists of the controller which has a variable switching surface and the adaptation logic net which observes the state of the controlled plant and the control signal yielded by the controller. It can improve the parameters of the controller according to the adaptation algorithm. The proposed method required neither information on the plant dynamics nor its identification. Adaptation is carried out on line. Computer simulation shows the effectiveness of the method.     

MILK BASIC PROTEIN ENHANCES THE BONE STRENGTH IN OVARIECTOMIZED RATS

We studied the effects of milk basic protein (MBP) on bone metabolism in ovariectomized (OVX) rats. Five‐week‐old female Sprague‐Dawley rats were ovariectomized and fed a low‐calcium diet (0.009% Ca) for 5 weeks. The OVX rats were divided into three experimental groups: Control group (20% casein), MBP‐L group (19.9% casein, 0.1% MBP), and MBP‐H (19% casein, 1% MBP) of six animals. The rats were fed each experimental diet for 3 weeks. The bone breaking strength and energy of femur in the MBP‐H group were significantly higher than those in the control group. The bone breaking energy of femur in the MBP‐L group was also significantly higher than those in the control group. There were no differences in the amount of femoral calcium and phosphorus among the three groups, however, the amounts of femoral proline, hydroxyproline and hydroxylysine (typical amino acids of collagen) in the MBP groups were significantly higher than those in the control group. These data indicate that MBP in the whey protein increases the amount of the bone collagen and enhances the bone strength.     

RAPID DETECTION OF A SMALL NUMBER OF VIABLE CELLS BY THE FLUORESCENT GLUCOSE METHOD

A fluorescent glucose, 2NBDG, was rapidly consumed by 4 different species of microorganisms: Escherichia coli, Lactobacillus acidophilus, Saccharomyces cerevisiae, and Candida tropicalis. E. coli and L. acidophilus became fluorescent enough for microscopic observation within 1 min, while S. cerevisiae and C. tropicalis became fluorescent in a longer time span. All of the 14 coliforms that were isolated from various foods consumed 2NBDG and became fluorescent within 1 min. Therefore, 2NBDG is expected to be a useful indicator of viable cells irrespective of species as long as they could assimilate glucose. This 2NBDG method is valid in counting small amount of cells, such as 10–100 cells, accurately and carefully. Also, the 2NBDG method was successfully applied to the rapid detection of a small number of E. coli in milk. The feasibility of the 2NBDG method is discussed from the viewpoint of food safety control.     

Properties of Space Charge Distributions and Conduction Current in XLPE and LDPE under DC High Electric Field

Space charge behavior and conduction current in polyethylene under dc stress were investigated. One of the reasons for the different breakdown property in cross‐linked polyethylene (XLPE) from that in low‐density polyethylene (LDPE) may be based on the existence of cross‐linking by‐products in XLPE. Furthermore, a thermal history in cross‐linking process for XLPE may also cause of the difference. It is generally accepted that the existence of the cross‐linking by‐products increase the conduction current in XLPE under dc stress. It is also said that an anneal treatment in air atmosphere may affect to the electrical properties under dc stress. Therefore, we investigated the effect of the cross‐linking by‐products and the anneal treatment on space charge behavior and conduction current in polyethylene under dc stress. In our research, it is thought that the increasing dissipation power in XLPE is the cause of the breakdown in it under dc stress. Therefore, to calculate the dissipation power in the bulk of test sample, we measured the space charge distribution and the external circuit current simultaneously. Based on the results, we discussed the reason of the difference of the space charge properties in XLPE and LDPE focusing on the cross‐linking by‐products and the oxidation of the test samples.     

THE ENHANCEMENT OF PRODUCTION OF PHENYLALANINE BY EXTRACTIVE FERMENTATION WITH POLYMERIC BEADS

Extractive fermentation using uncharged polymeric beads (Amberlite XAD-16) was used for phenylalanine production. By compensating the adsorption of the hydrophobic nutrients by the polymeric beads, production of phenylalanine was increased due to the removal of phenylalanine inhibition on the growth of the bacteria. When the fed batch culture was performed at low bead concentration, the production of the phenylalanine increased about 30% compared to the control fermentation. An increase of production can be also achieved by using the pre-saturated beads with the hydrophobic nutrients. In addition, the adsorption isotherm in the fermentation medium was investigated. It was found that the adsorption of phenylalanine onto the beads decreased because the adsorption sites can be occupied by nutrients, but this competitive adsorption is not so drastic as to affect the adsorption of phenylalanine during fermentation. This knowledge will be useful when this technology is applied to actual commercial operation.     

PRELIMINARY STUDIES ON EXTRACTIVE PHENYLALANINE FERMENTATION WITH UNCHARGED POLYMERIC BEADS

Extractive fermentation was used for phenylalanine production to prevent the crystallization of phenylalanine during the fermentation. Instead of the conventionally used ion exchange resin, uncharged polystyrene beads (Amberlite XAD-16) were used to extract phenylalanine from the fermentation broth. The experimental results obtained using a baffled shake flask showed that phenylalanine was not produced when the beads were added at the same time as the inoculum. From the detailed studies, it was found that hydrophobic nutrients such as tyrosine and colored materials from the soybean hydrolysate adsorbed onto the beads as well as phenylalanine. In order to overcome this problem, the beads were gradually added during the course of the fermentation to minimize the adsorption of the hydrophobic medium components. Using the gradual addition of the polymeric beads during fermentation, an equivalent amount of phenylalanine was produced as compared to the control, and 40% of the phenylalanine produced was extracted during the fermentation. It was concluded that extractive fermentation using polymeric beads could be an effective way of preventing the crystallization of phenylalanine during fermentation.     

An Advanced Effective Capacitance Model for Calculating Gate Delay Considering Input Waveform Effect

In deep submicron designs, predicting gate delay time is a noteworthy work for Static Timing Analysis. The effective capacitance Ceff concept is usually used to calculate the gate delay with interconnect loads. Conventionally, the input-signal to the gate is always assumed as a ramp waveform. However, the input signal is also the output of CMOS gates with interconnect loads and not the ramp waveform. Thus the simple assumption as a ramp signal results in significant influence on the delay calculation. In this paper, an advanced effective capacitance model is proposed to consider both the input waveform effect and the interconnect loads, where the nonlinear influence of input waveform is modeled as one part of the effective capacitance for calculating the gate delay. Experimental results show a significant improvement in accuracy when the input waveform effect is considered.