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Article type: Cover
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Published: October 20, 1959
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Article type: Cover
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Published: October 20, 1959
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Sadakazu TERAO, Issei SUETSUGU, Katsuya FUJII
Article type: Article
Pages
1-12
Published: October 20, 1959
Released on J-STAGE: February 24, 2018
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Calculation of natural frequency of vessel's hull is a matter of vital importance from the viewpoint of eliminating hull vibration. Although numbers of calculation formulae have been made public in the past, it seems that they have not sufficient accuracy for use in ship designing, it thus still remains as essential as ever to conduct vibration measurement on actual vessels. In view of this, we, the writers and their colleagues, designed and manufactured a hull vibration exciter and a marine vibrograph of cross hinge type associated with wire strain gauge with which we have been conducting forced vibration tests on vessel's hull with the intention of making experimental researches. In this treatise are given an outline of the vibration tests with the results thereof as well as the study of several formulae for calculating naturalf requency. The outcome may be summarized as below. 1. Comparison was made between our actually measured values with those obtained from the natural frequency calculation formula formulated by Messrs. Tomita, Kumai and Hirowatari, and as a result it was found that, although with regard to the fundamental vibrations the above values turned out to be comparatively similar, they showed considerable difference with regard to vibrations of higher order. 2. For large type supertankers, ranging from 40,000 to 50,000dwt., the capacity of the vibration exciter used by ourselves has proved to be sufficient. However, in order to know exactly the mode of vibrations, higher order vibrations and coupled vibrations, it is essential to make simultaneous measurement at least at more than ten points. 3. A specific phenomenon was observed in the forced vibration test conducted on actual vessels by means of vibration exciter, namely, coupled vibration appeared to the area comprising the vibration exciter and the structural portion of where the exciter was fitted, whereby the result of measurement was affected, and therefore, particular attention should be given to the structure of the fitting portion of the vibration exciter.
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Yoshio FUKUMOTO, Yoichiro OKAMURA
Article type: Article
Pages
13-15
Published: October 20, 1959
Released on J-STAGE: February 24, 2018
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For the strip with circular holes of same size perforated on the longitudinal axis, the effect of Bo/d and p/d (Bo is breadth of the strip, d diameter of the circular holes, p pitch of the holes) on the tensile rigidity was experimentally investigated. An approximate calculation method of the tensile rigidity was developed for the strip with the square holes in stead of the circular ones for the convenience of calculation. In the range of p/d > 3, irrespective of the difference in the shape of hole, the calculated values were proved to be in good agreement with the experimental ones.
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Jyumei KIWAKI, Yasuo YAMASAKI, Nobuo KANEKO
Article type: Article
Pages
16-20
Published: October 20, 1959
Released on J-STAGE: February 24, 2018
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Recently Volatile corrosion inhibitor (V.C.I.) is applied in all circles to the prevention of corrosion of the iron and steel materials on vapour and liquid phases. Experiments have been made on the anticorrosive effect of the V.C.I. for boilers which are at rest or cleaned with acid. The results of the experiments come to the next conclusions. (1) The suitable concentration of V.C.I. in the liquid phase is 100 mg/l and V.C.I. of more than 100 mg/l is not more efficacious. (2) V,C.I. of 100 mg/l concentration have nearly the same effect as NaOH of 300 mg/l. (3) After the acid cleaning, the boilers must be washed well with NaOH solution and water, and V.C.I. should be used in vapour or liquid phase.
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Tatsuji KUKITA
Article type: Article
Pages
21-24
Published: October 20, 1959
Released on J-STAGE: February 24, 2018
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Generally speaking, it is profitable for weight, volume and manufacturing expenses to adopt extended heating surface for the heat exchanger in which the temperature difference between heating and heated fluid is small. It is very important to use the studs of the most suitable size when studded tubes are used for extended heating surface. In our factory, studded tubes have been adopted for heating tubes of exhaust gas boiler in the last several years, and it was found that they were better in all respects than the bare tubes. By the recent inspection of the studded tubes taken from the exhaust gas boiler after long running, it was found that there was no necessity to take special considerations on the design and operation of the boiler, compared with the boiler with the bare tubes.
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Fukuo SHIBATA, Takao ITOI
Article type: Article
Pages
25-31
Published: October 20, 1959
Released on J-STAGE: February 24, 2018
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Special features of self-excited A.C. generator which put spurs to use A.C. system in almost all vessls of the world are as follows: 1. It is not necessary for this generator to use a rotary exciter. 2. It has a constant voltage characteristic without big automatic voltage regulator. 3. When the load is applied to it suddenly, the quantity of the instantaneous voltage drop is very little. In spite of the importance of parallel running in the operation of the ship generator, it has been neglected. There are important problems in the parallel running of selfexcited A.C. generator. One of the authors has paid attention to this problem and applied for patents (S-32-17773 and S-34-1489). These inventions are those which have special features of closed type and open type at the same time, and by which the balance method has been changed to the unbalanced method. "SK" generator seems to be a final excellent ship genrator which in future will be used widely, and we believe that "SK" generator will remain as one of the most popular forms of electric controlling method, same as famous Ward-Leonard, Ilgner, Kramer method and so forth.
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[in Japanese]
Article type: Article
Pages
32-33
Published: October 20, 1959
Released on J-STAGE: February 24, 2018
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[in Japanese]
Article type: Article
Pages
34-36
Published: October 20, 1959
Released on J-STAGE: February 24, 2018
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
Pages
37-40
Published: October 20, 1959
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Article type: Appendix
Pages
40-
Published: October 20, 1959
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Article type: Appendix
Pages
41-
Published: October 20, 1959
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Article type: Appendix
Pages
App1-
Published: October 20, 1959
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Article type: Appendix
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Published: October 20, 1959
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Article type: Appendix
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Published: October 20, 1959
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Article type: Appendix
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Published: October 20, 1959
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Article type: Appendix
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Published: October 20, 1959
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Article type: Appendix
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Published: October 20, 1959
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Article type: Appendix
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Published: October 20, 1959
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Article type: Appendix
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Published: October 20, 1959
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Article type: Cover
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Published: October 20, 1959
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