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Optical surface inspection of steel mill products such as pipes, plates and slabs usually has the problem of overdetection, which is caused by signals from harmless parts such as scale and surface texture. The authors propose a new inspection technique based on the experience that most harmful defects on these products have a concave or convex shape, whereas most harmless parts that might be overdetected have flat shapes. The proposed technique is called the ‘twin-illumination and subtraction technique’. In this technique, firstly, two images of the target area on a steel surface illuminated from the two sides are captured, respectively. A subtraction image is then calculated from these images. Comparing the images illuminated from the different sides, the images from concave or convex defects look different due to their different shadows, while images from harmless flat parts look the same because illumination does not cause any shadow. As a result, two images with the same appearances from a harmless part are canceled by subtraction, and two images with different appearances from a concave or convex defect remain even after subtraction. Finally, it is possible to detect only concave or convex defects without overdetecting flat patterns. In this manuscript, first, we explain the proposed technique and confirmation experiments in the laboratory. We also explain a new optical inspection system based on the concept described above and its application to moving hot pipes in a steel manufacturing plant to prove the effectiveness of the technique. We concluded that the inspection system has sufficient performance for use as a practical system.

A total of 355 Murrah cross buffaloes, consisting of 23 subclinical and 332 clinical mastitis cases brought to the Veterinary Teaching Hospital, Chitwan, Nepal from 2002 to 2005, were analyzed to determine the organisms involved, the seasonal occurrence of mastitis, and antibiotic susceptibility of mastitis pathogens. Coagulase negative Staphylococci (CNS) such as Staphylococcus albus and S. epidermidis were the predominant organisms associated with subclinical cases, and CNS and Coliforms in clinical cases. The maximum number (16%) of clinical cases of mastitis were observed in the month of July, when temperature and humidity are highest. The incidence of clinical mastitis was higher in animals during 1st calving and during the 1st month of parturition. Resistance to antibiotics was determined for 55, 23 and 149 isolates of Staphylococcus spp., Streptococcus spp. and Coliforms, respectively. In vitro drug sensitivity testing revealed that enrofloxacin had the highest average sensitivity (91%) for all types of bacteria. The effectiveness of other drugs detected were gentamicin (87%), tetracycline (83%) and chloramphenicol (82%). The antibiogram showed that both gentamicin and enrofloxacin are slowly becoming resistant. Mastitis pathogens have developed resistance to ampicillin and penicillin.

Recently, steel can manufacturing requires higher quality because otherwise minute non-metallic inclusions in thin sheets cause cracks and result in a burst during pressurization after the pressing process. Quality testing systems have already been installed in the final process in steel plants, but if there were another inspection in an earlier step, for example, at the hot strip mill, the mass manufacture of nonconforming products could be avoided and maintaining quality control would be more efficient. In order to detect inclusion defects in hot-rolled steel plates, the authors developed a new technique for MFLT (Magnetic Flux Leakage Testing) using different magnetizing forces. According to an analysis of the noise factors in MFLT, it was found that the signals generated from the scale layer on a steel surface are dominant. A different magnetizing force method is the used to decrease this overpowering noise level in MFLT. In this paper, it was confirmed that inclusions larger than 160μm in diameter and less than 0.45mm in depth can be detected utilizing this method.