Occurrence of Listonella anguillarum in seed production environments of Japanese flounder Paralichthys olivaceus (Temminck et Schlegel)

The present study was undertaken to investigate the distribution of Listonella anguillarum in the rearing water, fish and diets (rotifers) of Japanese flounder (Paralichthys olivaceus). A total of 793 isolates were obtained from the seed production environment of Japanese flounder and 175 out of them were identified as L. anguillarum by biochemical characterization, polymerase chain reaction (PCR) detection for VAH1 haemolysin gene and phylogenetic analysis of 16S ribosomal deoxyribonucleic acids (rDNA) sequences. These results strongly suggested that L. anguillarum is rapidly and accurately identified by the combination of incubation on thiosulphate–citrate–bile salt–sucrose agar at 35°C overnight and PCR detection for the VAH1 haemolysin gene. All flounder specimens and all rotifer samples harboured L. anguillarum at high densities of 6.9 × 10³–6.3 × 10⁵ colony forming units (CFU) g^?1 and 1.5 × 10⁴–2.3 × 10⁶ CFU g^?1, respectively, while as low as 5.0 × 10⁰–2.0 × 10¹ CFU mL^?1 of L. aguillarum were detected in only two of 11 seawater samples, even though no vibriosis occurred in larval and juvenile flounder of tanks. This fact strongly suggests that L. anguillarum is an inhabitant in the seed production environments of Japanese flounder.     

Locating and identifying splits and holes on sugi by the laser displacement sensor

The split and the hole are two common defects on sugi (Cryptomeria japonica D.Don). They have a common feature in that they are associated with surface irregularities. We have developed a laser scanning system to detect the splits and the holes based on their thickness, which correlates spatially with the profile information. The displacements measured by the laser sensor were converted to pixel values to generate the displacement profile image. Both the splits and the holes manifested well in the image. A dedicated image-processing program written in Visual Basic has been developed. The defects regions were accurately located by the image processing. To identify the defects, eight recognition rules based on four features have been utilized. Furthermore, a method based on the pixel model was proposed to compute the area of the defect. The results indicated that the defects could be identified correctly, and the areas could be computed accurately using the pixels model.     

木材表面缺陷的激光在线检测技术

本文介绍了采用激光位移传感器对刨削加工后的木材表面的裂纹及节子缺陷进行在线检测的方法。测试原理是利用激光位移传感器扫描木材表面，提供特征信号，由傅里叶分析仪FFT记录时间信号的波形，计算机进行数据处理和分析判断，这不仅可以快速识别裂纹及节子等缺陷，并从记录波形上即可计算出裂纹的宽度和深度。     

Food habits of sika deer as assessed by fecal analysis in Mt. Ohdaigahara,central Japan

Food habits of sika deer,Cervus nippon centralis temminck, in Mt. Ohdaigahara, central Japan, were investigated by the fecal analysis method from September, 1990, to June, 1991. The fecal analysis showed that the percentage ofSasa nipponica Makino et Shibata in the fecal composition was approximately 50% throughout the year, indicating that it was the main food plant. Bark and twigs were also found in the feces in all seasons, suggesting that the deer ate bark throughout the year. Even though the amount of the bark eaten per capita was small, the high density of deer may possibly cause serious bark damage. Barking can be one of the main causes of the mortality ofPicea jezoensis Sieb. et Zucc. var.hondoensis (Mayr) Rehder andAbies homolepis Sieb. et Zucc. in Mt. Ohdaigahara. A part of this study was presented at the 105th Annual Meeting of the Japanese Forestry Society (1994).     

Effects of helical angle of router bit on acoustic emission

The purpose of this study was to investigate the effects of changes in the helical angle of the router bit on the acoustic emission (AE) signal for various workpiece grain angles. The helical angle varied from 0° to 50° at 10° increments. The workpiece grains were oriented from 0 degrees (cutting parallel to the grain), through 90° (cutting end of the grain), to 165° at 15° increments. The AE signals and machined surface roughness were measured in an attempt to clarify the relations between them. The results were summarized as follows: (1) The AE signals were lowest in the with the grain cutting zones and slightly increased in the against the grain cutting zones; they rapidly reached the highest values at the 135°–165° grain angles. The greater the helical angle of the router bit, the smaller were the AE count rates for each grain angle investigated. There was no significant change in AE generation for helical angles of 0° and 10°. Moreover, the greater the feed rate, the greater was the AE count rate for every cutting condition investigated. (2) The surface roughness, similar to the AE count rate, had the lowest values in the with the grain cutting zones, slightly increased until the 120° grain angle, and then rapidly become extremely rough, reaching a maximum at the grain angles of 135°–150°. There was no remarkable change in the machined surface roughness while routing with the grain using the router bit of greater helical angle. However, when routing against the grain, the greater the helical angle the smoother was the machined surface. (3) There were correlations between the AE count rate and the machined surface roughness for each helical angle investigated. Therefore, acoustic emission has shown promise for monitoring and controlling the routing operation, including various grain angles and helical angles of the router bit.     

On-line determination of the grain angle using ellipse analysis of the laser light scattering pattern image

Under fixed cutting conditions, the surface finish roughness is correlated to the grain angle. However, the means of determining the grain angle automatically and accurately is still a challenge for on-line control of the router. It is therefore necessary to develop a new technology to determine the grain angle accurately and automatically. In this research, a laser light scattering pattern was used to accurately determine the grain angle. The light scattering pattern image was a quasi-ellipse caused by the grain direction and tracheid effect. A new modified Hough transform ellipse analysis technology was adopted to determine the ellipse parameters that could be used to determine the grain angle. The results indicated that the measured grain angle using the method proposed here was accurate and effective. The measured grain angle coincided with the real grain angle. There was an insignificant difference between the measured grain angle of Japanese beech (Fagus crenata blume) and that of sugi (Cryptomeria japonica D.Don) under two machining conditions that gave planed or sawn finishes. However, the accuracy of the measured grain angle of sugi was better than that of Japanese beech for the planed finish, the accuracy of the measured grain angle of Japanese beech was better than that of sugi for the sawn finish, and the accuracy of the measured grain angle for planed samples was better than that for sawn samples of both sugi and Japanese beech.     

Evaluation of the section modulus for tree-stem cross sections of irregular shape

The effect of section modulus, as estimated for tree stems of irregular cross section with hollow trunks, on windthrow resistance is discussed. The sample trees were 12 aged poplar trees growing along the roadside in Sapporo. Binarized bitmap images of photographs of the crosscut surface of the sample tree stems were used to calculate numerical solutions for section moduli. The error for image resolution was simulated to less than 1% under the condition in which the image was divided into more than 400 pixels. The coefficient of variation in section modulus concerning six neutral axis directions in a horizontal plane was 11%–14%. The reduction in section modulus caused by decay or hollow trunk was 36%–56% of the full cross section. The effect of section modulus on critical wind velocity was found to be considerable. The critical wind velocity calculated for some of the sample trees was less than 40m/s, and these trees were considered to be in danger of bending failure of the stems.     

Evaluation of surface smoothness by a laser displacement sensor II: comparison of lateral effect photodiode and multielement array

Development of accurate surface assessment technology is of vital interest to modern wood industries. In this experiment we investigated new and fast noncontacting sensors to determine their usefulness for wood surface evaluation and to verify their accuracy. Two types of laser displacement sensors [equipped with a position sensitive detector (PSD) and a charge coupled device (CCD) detector] are compared with a conventional stylus and with theoretical profiles. Hornbeam workpieces with triangular profiles of differing slope and height were used for the evaluation. The results show that resolution of both sensors decreases as the height of the profile decreases. The error ratio of the laser-scanned profiles changes as a function of profile height, in the range 5%–33%. The CCD method is superior for accurate surface roughness evaluation, although the PSD approach can still be used for monitoring the error of form in most applications.Parts of this work were presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000 and at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001