Reproduction of Array Observation Records by Means of Centrifuge Shaking Table Model

This paper shows the effects of the degree of consolidation of the soft clay layer on the strong motion response. Seismic behavior of the Kobe artificial islands during the 1995 Hyogo-ken Nambu earthquake is studied by using centrifuge shaking table test. At the earthquake, it is known that the liquefaction damage of artificial island was different from each other. Authors consider the reason why is due to the degree of consolidation of clay layer underlying the reclaimed ground. The model grounds used for the centrifuge test are made by the clay and fill material sampled from Kobe artificial island, and each clay layer of models is consolidated as the same degree as the sites. First, from the viewpoint of the reproducibility of in-situ behavior, the seismic response and the ground settlement are compared with observation data. Next, we compare the seismic response of the test results of the different degree of consolidation. It is found that the degree of consolidation and the shear strength of the clay layer significantly affect the ground behavior. The large damage is not always come to being on the ground with soft clay layer

Automatic Determination of the Imaging plane in Lumbar MRI

ABSTRACT In this paper we describe a method for assisting radiological technologists in their routine work to automatically determine the imaging plane in lumbar MRI. The method is first to recognize the spinal cord and the intervertebral disk (ID) from the lumbar vertebra 3-plane localizer image, and then the imaging plane is automatically determined according to the recognition results. To determine the imaging plane, the spinal cord and the ID are automatically recognized from the lumbar vertebra 3-plane localizer image with a series of image processing techniques. The proposed method consists of three major steps. First, after removing the air and fat regions from the 3-plane localizer image by use of histogram analysis, the rachis region is specified with Sobel edge detection filter. Second, the spinal cord and the ID were respectively extracted from the specified rachis region making use of global thresholding and the line detection filter. Finally, the imaging plane is determined by finding the straight line between the spinal cord and the ID with the Hough transform. Image data of 10 healthy volunteers were used for investigation. To validate the usefulness of our proposed method, manual determination of the imaging plane was also conducted by five experienced radiological technologists. Our experimental results showed that the concordance rate between the manual setting and automatic determination reached to 90%. Moreover, a remarkable reduction in execution time for imaging-plane determination was also achieved