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1.
Shogo Nakasumi Katsuyuki Suzuki Daiji Fujii Hideomi Ohtsubo 《Journal of Marine Science and Technology》2003,7(4):180-188
This article presents a mixed method of analyzing shell elements and solid elements using the overlaying mesh method. In
the structural design of a ship's hull, the shell elements are used for the global model. However, the solid elements are
necessary to analyze the stress concentration zones or the vicinity of a crack. In such cases, the models are analyzed using
zooming analysis, in which the results of a global model analysis are transferred to a local model analysis by imposing boundary
conditions. This method is more advantageous than zooming analysis in terms of the accuracy of the solution and the modeling
flexibility. Some examples of a plate model with a cracked surface or with a projection are shown in order to demonstrate
the effectiveness of the method.
Received: August 6, 2002 / Accepted: November 25, 2002
Address correspondence to: S. Nakasumi (sumi@nasl.t.u-tokyo.ac.jp)
Updated from the Japanese original, which won the 2002 SNAJ prize (J Soc Nav Archit Jpn 2001;189:219–224; and 190:655–662) 相似文献
2.
Certification criteria in type I ecolabelling related to metals for sustainable materials management
A sustainable materials management for metals should be achieved to conserve resources of metal minerals. For the sustainable materials management, material flows through the whole life cycle of materials have been recognized by material flow analysis (MFA) studies. Former MFA studies pointed out that cyclic use of metals could be enhanced not only by increasing quantity of recovered scrap but also by upgrading quality of the scrap. In general, the quality is degraded by contaminants which commingle at disassembling processes. The mixture of contaminants depends on usage of materials in products. Here, Type I ecolabelling has a potential to convey messages for avoiding mixture of contaminants to the producers of finished products. In this study, on the basis of a survey on existing certification criteria related to metals in the world, a general concept of certification criteria on sustainable materials management for metals in Type I ecolabelling system is proposed. Finally, we propose six criteria in the form of certification criteria in Type I ecolabelling system. 相似文献
3.
4.
Naoya Umeda Akihiko Matsuda Masami Hamamoto Shiro Suzuki 《Journal of Marine Science and Technology》1999,4(2):45-57
A systematic method for assessing intact ship stability with a free-running model in a seakeeping and maneuvering basin is
proposed in this paper. Model experiments were carried out in extremely steep regular waves for a model drifting, running
in head seas, and quartering seas. This method was applied to two purse seiners, and efficiently identified thresholds in
metacentric heights for capsizing of these ships. These capsizing thresholds are compared with requirements of the IMO Code
on Intact Stability. This series of model experiments also confirms that capsizing at the threshold occurs only in quartering
seas, and shows that capsizing is caused by broaching, loss of stability on a wave crest, or bow diving.
Received for publication on Jan. 20, 1999; accepted on July 6, 1999 相似文献
5.
Takashi Tsubogo 《Journal of Marine Science and Technology》1999,4(2):76-83
This paper deals with the dispersion relation of hydroelastic waves in pontoon-type very large floating structures (VLFS)
using a simple beam modeling, where the term hydroelastic waves means propagation of deflection vibrations in VLFS. The purpose of this paper is to show the properties of the hydroelastic
waves. The dispersion relation of hydroelastic waves propagating in an infinite plate floating on the water is derived based
on the linear water wave theory. The effects of the water depth and of the bending rigidity of the floating plate on the wavelength,
phase velocity, and group velocity of the hydroelastic waves are shown theoretically or numerically. Then, the dispersion
relation of hydroelastic waves in a finite plate floating on shallow water is investigated. It is shown that the wavelength
or the phase velocity of the hydroelastic waves varies with the location in the plate.
Received for publication on April 7, 1999; accepted on Aug. 20, 1999 相似文献
6.
Keisuke Watanabe Hideyuki Suzuki Koichiro Yoshida 《Journal of Marine Science and Technology》1998,3(3):151-160
The trend towards deepwater development requires a new approach to underwater installation of offshore structures. The present
method using crane vessels has some drawbacks in operations at more than 2000 m depth. The natural period of the coupled system
of the rigged structure and the crane vessel becomes longer, so that it is no longer possible to manipulate the cranes to
achieve the desired positioning accuracy. This paper examines the application of an active control technique for underwater
installations as one of the solutions to the present problems. An active control technique also has the advantage that it
can deal with the structural flexibility which allows the structure to be large and light-weight. This structural flexibility
imposes problems of suppressing the elastic responses and securing the stability of the control system. In this paper, anH
∞ controller combined with a low authority control/high authority control (LAC/HAC) feedback controller is designed for cases
where structural flexibility cannot be ignored. A robust model-following controller is examined for cases where the structure
can be treated as rigid. In order to confirm the control algorithm and verify the possibility of the active control installation
method, basin tests are executed using two types of neutrally buoyant flexible models with ultrasound ranging systems and
thrusters. 相似文献
7.
Hideyuki Suzuki Koichiro Yoshida Kazuhiro Iijima 《Journal of Marine Science and Technology》1996,1(5):255-267
The land area of Japan, especially flat land, is very small compared with its economic size. Large-scale floating structures
are one solution to satisfy the demand for space by utilizing the ocean. This paper presents a general view of the dynamic
response characteristics of large-scale floating structures, pontoons and semi-submersibles. For example, it is shown that
the natural frequencies of eigenmodes are higher than the natural frequency of heaving motion. The response of the outer framework
of a structure is shown to be generally larger than the response of the central part. Within the limits of our present understanding
of the general dynamic response characteristics of such structures, the design and analysis of semi-submersible, large-scale
floating structures is discussed. For a pontoon-type large-scale floating structure, a type whose perimeter structure has
been modified to become lighter and more rigid is proposed. With this modification, the dynamic response of the whole structure
is imporved. 相似文献
8.
Kazuhiro Fukuda Junichiro Tokunaga Takashi Nobunaga Tatsuo Nakatani Toru Iwasaki Yoshikuni Kunitake 《Journal of Marine Science and Technology》2000,5(3):123-130
This paper presents a new technique for reducing frictional drag using a super-water-repellent surface and air-injection
(called an SWR & A technique). Its effectiveness was examined by carrying out pressure-loss measurements with a tube of rectangular
cross section, along with resistance tests on a horizontal flat plate, a 7.2-m-long tanker model, and a 12-m-long high length-to-beam-ratio
model ship. These test results showed that the new technique can significantly reduce the models' frictional drag; for example,
the frictional resistance on the SWR surface was reduced by 80% at a speed of 4 m/s and 55% at 8 m/s.
Received: October 16, 2000 / Accepted: December 4, 2000 相似文献
9.
Levent Kirkayak Vinicius Aguiar de Souza Katsuyuki Suzuki Hideyuki Ando Hidetoshi Sueoka 《Journal of Marine Science and Technology》2011,16(3):354-365
It is estimated that around 10,000 containers are lost during maritime transportation every year, representing an economic
loss to the liner industry. Regulations and norms used to calculate values to secure them to the ship’s deck account for static
loads only, neglecting more realistic conditions. This paper describes an approach to simulate a two-tier scaled model of
a 20-ft ISO freight container and its linking connectors, denominated twist locks, subject to a dynamical load induced by
its base. To analyze this problem two methods were employed: a shaking table test and finite-element analysis. Results of
this study indicate that the numerical model built to simulate two-tier container stack dynamics is a promising tool for further
studies. Moreover, the model is able to predict conditions close to real situations faced by container stacks while stored
on deck. 相似文献
10.
Toshihiro Maki Tamaki Ura Takashi Sakamaki 《Journal of Marine Science and Technology》2012,17(4):523-531
This paper proposes a path-planning and guidance strategy for an autonomous underwater vehicle (AUV) to perform detailed inspections of jacket structures such as the support legs of offshore platforms. Inspections of such structures are important for maintenance, security, and environmental assessment. These tasks can be carried out at a less cost by using AUVs than through conventional methods. The path-planning method generates a set of waypoints to facilitate the complete coverage of the surface of the target from a constant distance based on the given information about the configurations of both the target and the vehicle. The guidance method actually controls the vehicle such that it follows the waypoints, under the assumption that the position and attitude of the vehicle are being estimated in real time with adequate accuracy. By combining these methods with the localization method we had previously proposed (Maki et al., J Mar Sci Technol [1]) an AUV can perform a fully autonomous observation of jacket structures with prior knowledge of only their configuration. The performance of the method was verified though tank experiments using the AUV Tri-Dog 1. A simple model of a jacket was installed in a test tank, and the vehicle succeeded in inspecting the target. 相似文献