International Shipbuilding Progress - Volume 25, issue 289

Authors: Noordzij, L. | Cruijff, H.J.

Article Type: Research Article

Abstract: When investigating cavitation inception phenomena it is important to have information on the nuclei spectrum of the liquid. The so-called light-scattering technique, as developed by Keller [1] , was applied to gain this information in circumstances which are met in the DTT of the NSMB for cavitation testing of ship propellers. The number of nuclei with a diameter in the range of 7–75×10-6 m was determined. This was done for some values of (i) total gas content of the water, (ii) ambient pressure and (iii) speed of the model.

DOI: 10.3233/ISP-1978-2528901

Citation: International Shipbuilding Progress, vol. 25, no. 289, pp. 231-234, 1978

Authors: Wijnolst, N.

Article Type: Research Article

Abstract: The distribution of world ship tonnage shows little correlation with the seaborne export and import cargo flows from the individual countries. The discrepancy is particularly large in the case of developing countries. This has led to a resolution at UNCTAD-III (Santiago, 1972) in which is stated that the developing countries should own at least 10 percent of the world fleet by 1980. In the past years the developing countries have indeed expanded their fleets (in absolute terms), but their share in the world tonnage declined. Apparently, the establishment and expansion of national fleets is more easily said than done. …Most developing countries start out in shipping by establishing liner fleets. Although many books have been written on this subject, there exist few publications which provide guidelines and quantitative methods for the evaluation of shipping projects in developing countries. In fact only the Shipping Secretariat of UNCTAD has published reports on this matter. However, in none of the publications liner shipping is looked upon as a system with dynamic properties. For this reason I decided to develop a simulation model of national fleet development. With the help of this model the maritime planner in a developing country can evaluate shipping projects at the company and national level. The approach to modelbuilding which is used in this study, is called “system dynamics”, a method developed by J.W. Forrester. My early ideas on the model concepts are published in a number of articles in Norwegian Shipping News (1975). In 1976 I worked in Kenya and was able to gather information on the national fleet development plans of that country. On this basis I constructed the present models. Although most of the data is from the real world, it was inevitable that numerous assumptions had to be made. This paper is more or less a summary of my doctorate thesis, which I passed on June 20, 1977 at the Technische Hogeschool Delft, The Netherlands. It only provides a rough outline of the thesis1 1 Those interested in the detailed computer programs and sensitivity tests, may obtain a copy of the thesis (177 p.) by sending a check of U.S. $25 (including air mail postage) to Niko Wijnolst, Vijverlaan 16, 3062 HK Rotterdam, The Netherlands. . Those interested in the detailed computer programs and sensitivity tests, may obtain a copy of the thesis (177 p.) by sending a check of U.S. $25 (including air mail postage) to Niko Wijnolst, Vijverlaan 16, 3062 HK Rotterdam, The Netherlands. Show more

DOI: 10.3233/ISP-1978-2528902

Citation: International Shipbuilding Progress, vol. 25, no. 289, pp. 235-249, 1978