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Considering the sea conditions in which a large ship encountered in operation, the ship’s behavior in very short waves is important. However, the evaluation of the ship performance in very short waves was not enough validated by tank tests. Because it is difficult to generate waves with enough accuracy due to the performance of the wave generator. In this paper, it is shown that tank tests of added resistance in the regular waves including the very short waves are conducted in the Actual Sea Model Basin at National Maritime Research Institute, MPAT for DTC container ship and accurate results are obtained. The test results are compared with the benchmarks published by SHOPERA (Energy Efficient Safe SHip OPERAtion). In addition, three curves of the added resistance in the regular waves based on the results of the tank test are compared and the sensitivity analysis of energy efficiency is discussed. In the sensitivity analysis, the performance simulator for ships in actual seas (VESTA) is used, and a comparison is carried out for the fuel consumption calculated from the frequency response of each added resistance in waves. As a result, it is found that the tendency in added resistance in very short waves affects the fuel consumption and the decrease of ship speed.

The clinical impact of the coexistence of compressive cervical myelopathy (CM) and/or lumbar spinal canal stenosis (LCS) with compressive thoracic myelopathy (TM) remains unknown. The purpose of this study was to examine the incidence, clinical pictures, and surgical outcomes of patients with compressive TM and the coexistence of compressive CM and/or LCS. We retrospectively reviewed 50 patients (18 women and 32 men; mean age 68.4 years) who underwent decompression surgery for TM. Mean follow-up period was 44 months. The incidence and clinical features of the coexistence of CM and/or LCS were investigated. The surgical outcomes after single-stage multilevel decompression surgery were also examined using the Japanese Orthopedic Association (JOA) scores. Of 50 patients, 35 had concurrent CM and/or LCS (combined group), and the remaining 15 only had TM (T group). No significant differences were found with regard to sex, the etiology of TM, or the level of thoracic stenosis between the groups; however, the patients’ age and preoperative JOA scores in the combined group were significantly higher than those in the T group. In both groups, the JOA score at the final follow-up significantly improved compared to the preoperative JOA score. About 70 % of patients who underwent surgery for TM had concurrent CM and/or LCS, and they were initially diagnosed with CM or LCS. Single-stage multilevel decompression surgery for TM with concurrent CM and/or LCS is comparable to thoracic only surgery with regard to complications and surgical results, and it is well tolerated in elderly patients.