Seismic Crack Investigation in an Earth Dam by Centrifugal Loading Test

There are many Earth-fill dams in Japan, which are mostly used for irrigation use. Most of these dams in Japan were constructed by experience over 100 years ago. There are so many irrigation dams, which suffered earthquake damage in the past. Due to the damages, the cracks at the crest in the dam-axis direction have been reported in many cases. For the rock-fill dam recently constructed, the crack on the crest in the dam-axis direction has also been found in the case of a large earthquake. The mechanism of such a crack has not been discussed well. In this study, to clarify the mechanism of a crack in the dam-axis direction, a centrifugal loading test was applied to the dam with a 50 G gravity field. As a result, the critical level of strain was observed at the crest of the model, and it was found that the horizontal displacement at the upper part of the dam was excessive. It can be concluded from the study that the seismic cracks in the dam-axis direction occurred due to the excessive tensile stress, which was not considered in the design process

Field Telemetry of Blade-rotor Coupled Torsional Vibration at Matuura Power Station Number 1 Unit

The quasi-modal reduction technique and finite element model (FEM) were used to construct an analytical model for the blade-rotor coupled torsional vibration of a steam turbine generator of the Matuura Power Station. A single rotor test was executed in order to evaluate umbrella vibration characteristics. Based on the single rotor test results and the quasi-modal procedure, the total rotor system was analyzed to predict coupled torsional frequencies. Finally, field measurement of the vibration of the last stage buckets was made, which confirmed that the double synchronous resonance was 124.2 Hz, meaning that the machine can be safely operated. The measured eigen values are very close to the predicted value. The single rotor test and this analytical procedure thus proved to be a valid technique to estimate coupled torsional vibration

Longitudinal L2 development of the English article in individual learners

We investigate the accuracy development of the English article by learners of English as a second language. The study focuses on individual learners, tracking their learning trajectories through their writings in the EF-Cambridge Open Language Database (EFCAMDAT), an open access learner corpus. We draw from 17,859 writings by 1,280 learners and ask whether article accuracy in individual learners fluctuates randomly or whether learners can be clustered according to their developmental trajectories. In particular, we apply k-means clustering to automatically cluster in a bottom up fashion learners with similar learning curves. We follow learners for a period covering one CEFR level. Given the relatively short learning window, the majority of learners follow a horizontal line. Nevertheless, we also identify groups of learners showing a power-function and U-shaped curve. Crucially, these groups are ‘hidden’ when the aggregate of learners is considered, a finding highlighting the importance of individual level analysis

Metastatic carcinoma of the colon similar to Crohn's disease: a case report.

A 68-year-old Japanese man with a history of linitis plastica carcinoma of the stomach and subsequent gastrectomy 8 years previously presented with lower abdominal pain. Radiological and endoscopic examinations showed multiple submucosal nodular lesions similar to Crohn's disease in the ileocecal area. A firm diagnosis could not be made after initial multiple biopsies. Finally, a submucosal biopsy revealed adenocarcinoma. The ileocecal lesion was diagnosed as a recurrence because of the histological findings, which included mucosal preservation, a similarity with the histologic type of stomach carcinoma, and atypical immunoreactivity for primary colon carcinoma; the lesion was negative for both cytokeratin 7 and cytokeratin 20. In cases where metastatic carcinoma of the colon is suspected, we recommend early consideration of a submucosal biopsy.</p

Space-Time Finite Element Method for Seismic Analysis of Concrete Dam

Finite element method (FEM) is the most extended approach for analyzing the design of the dams against earthquake motion. In such simulations, time integration schemes are employed to obtain the response of the dam at time tn+1 from the known response at time tn. To this end, it is desirable that such schemes are high-order accurate in time and remain unconditionally stable large time-step size can be employed to decrease the computation cost. Moreover, such schemes should attenuate the high-frequency components from the response of structure being studied. Keeping this in view, this chapter presents the theory of time-discontinuous space-time finite element method (ST/FEM) and its application to obtain the response of dam-reservoir system to seismic loading

Individual variation and the role of L1 in the L2 development of English grammatical morphemes: insights from learner corpora

The overarching goal of the dissertation is to illustrate the relevance of learner corpus research to the field of second language acquisition (SLA). The possibility that learner corpora can be useful in mainstream SLA research has a significant implication given that they have not been systematically explored in relation to SLA theories. The thesis contributes to building a methodological framework to utilize learner corpora beneficially to SLA and argues that learner corpus research contributes to other disciplines. This is achieved by a series of case studies that quantitatively analyze individual variation and the role of native language (L1) in second language (L2) development of English grammatical morphemes and explain the findings with existing SLA theories. The dissertation investigates the L2 development of morphemes based on two largescale learner corpora. It first reviews the literature and points out that the L2 acquisition order of English grammatical morphemes that has been believed universal in SLA research may, in fact, vary across the learners with different L1 backgrounds and that individual differences in morpheme studies have been relatively neglected in previous literature. The present research, thus, provides empirical evidence testing the universality of the order and the extent of individual differences. In the first study, the thesis investigates L1 influence on the L2 acquisition order of six English grammatical morphemes across seven L1 groups and five proficiency levels. Data drawn from approximately 12,000 essays from the Cambridge Learner Corpus establish clear L1 influence on this issue. The study also reveals that learners without the equivalent morpheme in L1 tend to achieve an accuracy level of below 90% with respect to the morpheme even at the highest proficiency level, and that morphemes requiring learners to learn to pay attention to the relevant distinctions in their acquisition show a stronger effect of L1 than those which only require new form-meaning mappings. The findings are interpreted under the framework of thinking-for-speaking proposed by Dan Slobin. Following the first study, the dissertation exploits EF-Cambridge Open Language Database (EFCamDat) and analyzes the developmental patterns of morphemes, L1 influence on the patterns, and the extent to which individual variation is observed in the development. Based on approximately 140,000 essays written by 46,700 learners of 10 L1 groups across a wide range of proficiency levels, the study found that (i) certain developmental patterns of accuracy are observed irrespective of target morphemes, (ii) inverted U-shaped development is rare irrespective of morphemes, (iii) proficiency influences the within-learner developmental patterns of morphemes, (iv) the developmental patterns at least slightly vary depending on morphemes, and (v) significant individual variation is observed in absolute accuracy, the accuracy difference between morphemes, and the rate of development. The findings are interpreted with dynamic systems theory (DST), a theory of development that has recently been applied to SLA research. The thesis further examines whether any systematic relationship is observed between the developmental patterns of morphemes. Although DST expects that their development is interlinked, the study did not find any strong relationships between the developmental patterns. However, it revealed a weak supportive relationship in the developmental pattern between articles and plural -s. That is, within individual learners, when the accuracy of articles increases, the accuracy of plural -s tends to increase as well, and vice versa