共查询到20条相似文献,搜索用时 31 毫秒
1.
Keith R. McAllister 《Journal of Marine Science and Technology》1997,2(3):173-181
The Mobile Offshore Base (MOB) is a multipurpose, floating logistics base which can be stationed in coastal or international
waters. The offshore base is comprised of self-propelled modules that are connected together at sea to form a runway and support
base for fixed-wing aircraft and helicopters. The MOB is used as a prepositioned cargo stowage and transshipment point, enabling
the movement of cargo to and from ships in an open seaway. Described here is an approach to developing a mobile, offshore
basing capability. The work is discussed in context of two significant MOB projects including a discussion of criteria and
major technical issues.
Presented at the International Workshop on Very Large Floating Structures (VLFS'96), 25–28 November 1996, Hayama, Japan 相似文献
2.
Yusuke Yano Shinichi Takagawa Kazuyasu Wada 《Journal of Marine Science and Technology》2003,7(3):101-108
The Japan Marine Science and Technology Center (JAMSTEC) has been, and is now promoting the “OD21” program (i.e., “Ocean
drilling in the 21st century”). This is the first plan in the world to utilize deep-water riser-drilling technologies for
scientific drilling. One of the important factors for the success of this program is the development of a high-performance
drilling vessel. Since 1990, JAMSTEC has been continuing a technological study of a riser-drilling vessel for scientific studies
with an operational capability in waters up to 4000 m deep. It was decided to start the construction with a two-phase plan:
a vessel with a riser operation for waters up to 2500 m deep will be constructed in the initial stage, and then the vessel
will be modified to a 4000-m depth capability. In the development process of the vessel, named Chikyu, many new technical developments have taken place, such as drilling/coring equipment, a dynamic positioning system, etc.
Thus, the Chikyu is expected to contribute to ocean engineering and other work, in addition to scientific advances.
Received: June 15, 2002 / Accepted: November 11, 2002
Address correspondence to: Y. Yano (e-mail: yanoy@jamstec.go.jp) 相似文献
3.
4.
On November 30, 2006, USS Boone (FFG 28) lost all steering control in the Mediterranean Sea due to a lost rudder. Within hours of the casualty, numerous US Navy and contractor activities sprung into action to coordinate and complete an emergent voyage repair to return USS Boone to service to support the Global War on Terrorism. The Navy faced a large hurdle to identify and transport a replacement rudder to Rota, Spain, and prepare and carry out an extremely complex repair procedure. Pearl Harbor Naval Shipyard personnel removed the replacement rudder from USS Crommelin (FFG 37) in Pearl Harbor Naval Shipyard and transported the rudder to Rota, Spain. The Navy's Supervisor of Salvage and Diving developed the repair procedure and coordinated the repair operation, which involved over 30 US Navy and contractor divers. The repair team completed the rudder replacement on December 28, 2006 and returned USS Boone to underway operations. 相似文献
5.
Hiroshi Kagemoto 《Journal of Marine Science and Technology》2003,7(3):128-136
Explicit expressions are derived for the drift force that will act on a bottom-mounted, slightly porous vertical cylinder
fixed in regular waves. The drift-force expressions derived both from the near-field and the far-field are shown. It is indicated,
and numerically demonstrated, that the conventional far-field formula does not hold for a porous body, but needs the additional
term of a near-field body-surface integration.
Received: July 4, 2002 / Accepted: November 6, 2002
Acknowledgment. The author would like to acknowledge Prof. Kashiwagi, of Kyushu University, for indicating the work of Havelock relating
to Eq. 20.
Address correspondence to: H. Kagemoto (e-mail: kagemoto@k.u-tokyo.ac.jp) 相似文献
6.
Masahiko Fujikubo Taoyun Xiao Kazuhiro Yamamura 《Journal of Marine Science and Technology》2003,7(3):119-127
A structural safety assessment of a pontoon-type very large floating structure (VLFS) surrounded by a gravity-type breakwater
was carried out for extreme wave conditions by considering the damage to the breakwater. Bending and shear collapses are considered
to be a failure mode of the floating structure, while overturning damages the breakwater. The probability of the breakwater
overturning, and the transmitted wave height before and after damage to the breakwater, are evaluated using design formulae
for port and harbor facilities in Japan. The ultimate bending and shear strengths of the floating structure are calculated
by the idealized structural unit method (ISUM) and FEM, respectively. The calculated failure probability for the floating
structure is compared with the specified target safety level. It was found that the floating structure under consideration
is most likely to fail by bending in transverse waves, and that the corresponding failure probability satisfies the target
level.
Received: September 12, 2002 / Accepted: October 4, 2002
Acknowledgment. The authors are grateful to Dr. Shigeo Ohmatsu, National Maritime Research Institute, Japan, for allowing us to use the program
of hydroelastic response analysis.
Address correspondence to: M. Fujikubo (e-mail: fujikubo@naoe.hiroshima-u.ac.jp)
Updated from the Japanese original, which won the 2002 SNAJ prize (J Soc Arthit Jpn 2002;190:337–345) 相似文献
7.
Satoru Shiraishi Kazuhiro Iijima Keitaro Harasaki 《Journal of Marine Science and Technology》2003,8(1):1-10
This article describes the results of hydraulic model tests of the elastic response of a very large floating structure (VLFS)
moored inside a reef in an isolated island. The distributions of strains and vertical displacements due to the elastic response
of the VLFS were measured. The response characteristics were strongly affected by deformed nonlinear waves inside the reef.
A two-step analytical method to compute the elastic response of a VLFS is proposed, and its validity is verified using the
results of the hydraulic model tests.
Received: May 2, 2002 / Accepted: March 17, 2003
RID="*"
ID="*" Address correspondence to: S. Shiraishi (shiraishi@pari.go.jp)
Acknowledgment. This study was supported by the Program for Promotions of Fundamental Transport Technology Research from the Corporation
for Advanced Transport and Technology (CATT). 相似文献
8.
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
9.
Time-varying coefficient vector autoregressive (T-VVAR) modeling with instantaneous responses is applied to spectrum analysis
based on the nonstationary motion data of ships. Because of the ship's maneuvers, changes such as course and speed, the ship
motions in waves are regarded as a nonstationary random process, although the seaway can be considered as a stationary stochastic
process. The T-VVAR model is transformed into a state space model, and the time-varying coefficients can be evaluated by using
the Kalman filter algorithm. Using the estimated time-varying coefficients, the instantaneous cross spectra of the ship motions
can be calculated at every moment. In order to examine the reliability of the proposed procedure, on-board tests were carried
out. Under stationary conditions, at a constant speed and course, the proposed method shows good agreement with stationary
vector autoregressive (SVAR) modeling analysis. Moreover, it is confirmed that the proposed method can estimate the instantaneous
cross spectra of the ship motions even under nonstationary conditions, showing that this is a powerful tool for on-line analysis
of the nonstationary motion data of ships.
Received: August 2, 2002 / Accepted: November 28, 2002
Acknowledgments. The authors thank the captain and crew of the training ship Shioji Maru, Tokyo University of Mercantile Marine.
Address correspondence to: T. Iseki (iseki@ipc.tosho-u.ac.jp)
Updated from the Japanese original, which won the 2002 SNAJ prize (J Soc Nav Archit Jpn 2001;190:161–168) 相似文献
10.
Weicheng Cui 《Journal of Marine Science and Technology》2002,7(1):43-56
Metals are the most widely used materials in engineering structures, and one of the most common failure modes of metal structures
is fatigue failure. Although metal fatigue has been studied for more than 160 years, many problems still remain unsolved.
In this article, a state-of-the-art review of metal fatigue is carried out, with particular emphasis on the latest developments
in fatigue life prediction methods. All factors which affect the fatigue life of metal structures are grouped into four categories:
material, structure, loading, and environment. The effects of these factors on fatigue behavior are also addressed. Finally,
potential problems to be resolved in the near future are pointed out.
Received: January 7, 2002 / Accepted: March 25, 2002 相似文献
11.
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
12.
Naoya Umeda Hirotada Hashimoto Akihiko Matsuda 《Journal of Marine Science and Technology》2003,7(3):145-155
We have attempted to develop a more consistent mathematical model for capsizing associated with surf-riding in following
and quartering waves by taking most of the second-order terms of the waves into account. The wave effects on the hull maneuvring
coefficients were estimated, together with the hydrodynamic lift due to wave fluid velocity, and the change in added mass
due to relative wave elevations. The wave effects on the hydrodynamic derivatives with respect to rudder angles were estimated
by using the Mathematical Modelling Group (MMG) model. Then captive ship model experiments were conducted, and these showed
reasonably good agreements between the experiments and the calculations for the wave effects on the hull and the rudder maneuvring
forces. It was also found that the wave effects on restoring moments are much smaller than the Froude–Krylov prediction, and
the minimum restoring arm appears on a wave downslope but not on a wave crest amidship. Thus, an experimental formula of the
lift force due to the heel angle of the ship is provided for numerical modelling. Numerical simulations were then carried
out with these second-order terms of waves, and the results were compared with the results of free-running model experiments.
An improved prediction accuracy for ship motions in following and quartering seas was demonstrated. Although the boundaries
of the ship motion modes were also obtained with both the original model and the present one, the second-order terms for waves
are not so crucial for predicting the capsizing boundaries themselves.
Received: June 20, 2002 / Accepted: October 10, 2002
Acknowledgments. This research was supported by a Grant-in-Aid for Scientific Research of the Ministry of Education, Culture, Sports, Science
and Technology of Japan (No. 13555270). The authors thank Prof. N. Rakhmanin of the Krylov Ship Research Institute for providing
the Russian literature, as well as Mr. H. Murata of NHK (Japan Broadcasting Corporation) for translating it into Japanese.
Address correspondence to: N. Umeda (e-mail: umeda@naoe.eng.osaka-u.ac.jp) 相似文献
13.
Yoshitaka Ogawa 《Journal of Marine Science and Technology》2003,7(3):137-144
To develop a practical prediction method for the green water load and volume on the bow deck in irregular waves, model tests
were conducted using a tanker and a cargo ship on a domestic Japanese voyage. The relation between green water load and relative
water height at the stem was considered. Based on the finding that the maximum value of the green water load is proportional
to the square of the maximum value of the water elevation over the bow top, the probability density functions of the green
water load and volume in short-term predictions were proposed. It was verified that the proposed functions show good agreement
with the measured distributions, especially in the tails, and were better than conventional functions. Using these functions,
long-term predictions of the green water load were carried out. It was confirmed that the present method is more rational
than the conventional one for estimating the long-term probability of the green water load. An assessment of the bow height
of a domestic Japanese ship from the viewpoint of deck wetness was carried out using these prediction methods. This research
was used as the technical background for the revision of domestic rules on load lines, which was enforced in October 2001.
Received: July 19, 2002 / Accepted: October 30, 2002
Acknowledgment. Some of the present study was carried out as part of a cooperation project (RR45) with the Shipbuilding Research Association
of Japan, supported by the Nippon Foundation.
Address correspondence to: Y. Ogawa (e-mail: ogawa@nmri.go.jp) 相似文献
14.
Régis Duvigneau Michel Visonneau Gan Bo Deng 《Journal of Marine Science and Technology》2003,8(1):11-25
The practical use of automated computational fluid dynamics (CFD)-based design tools in the ship-building industry requires
powerful flow solvers which are able to take into account realistic geometries as well as complex physical phenomena, such
as turbulence. A shape optimization tool is developed in this framework. A derivative-free optimizer, yielding both flexibility
and robustness, is preferred to the classical gradient-based method, which is more difficult to implement and is still limited
to only moderately complex problems. The flow solver included in the design procedure solves the incompressible Reynolds-averaged
Navier–Stokes equations on unstructured grids using a finite-volume formulation involving several near-wall low-Reynolds-number
turbulence models. The design tool is used to optimize the stern of a modern hull shape at model and full scale, with different
purposes being considered. More precisely, the drag reduction and the homogenization of the flow in the wake are expected
by controlling the longitudinal vortex generated. Our interest is particularly focused on the influence of turbulence modeling
in the design process. The effects of a two-equation model based on the eddy-viscosity assumption and a second-order closure
relying on the Reynolds stress transport equations are compared.
Received: September 24, 2002 / Accepted: April 14, 2003
RID="*"
Acknowledgment. The authors thank the scientific committee of CINES (project dmn2050) for the attribution of CPU time. 相似文献
15.
Naoki Osawa Yasumitsu Tomita Kiyoshi Hashimoto 《Journal of Marine Science and Technology》2003,7(4):189-204
In order to accumulate knowledge about how material compositions and manufacturing methods affect fatigue strength, this
paper investigates the relationship between the swiftness of the changes in the macroscopic indices of the crack initiation
process and the hardening properties of a material. This is done by calculating the cyclic deformation behavior of a f.c.c.
single crystal. The relationship between the swiftness of the changes and the crystal geometries is also examined by calculating
the deformation behavior of a f.c.c. crystal with a high Schmid factor buried in a large crystal with a low Schmid factor.
In addition, a multiscale hardening rule based on forest theory is developed in order to examine the microscopic mechanisms
of fatigue slip band (persistent slip bands, PSBs) formation. The validity of the theories presented is examined by comparing
the changing nature of the measured and calculated hysteresis loop shapes of f.c.c. single crystals. Inhomogenous slip deformation
through the crystal is also investigated, and inferences are then drawn about the microscopic mechanisms of cyclic hardening
and PSB formation.
Received: August 5, 2002 / Accepted: December 18, 2002
Address correspondence to: N. Osawa (osawa@naoe.eng.osaka-u.ac.jp)
Updated from the Japanese original, which won the 2002 SNAJ prize (J Soc Nav Archit Jpn 1998;184:351–363, 1999;185:283–292
and 186:535–544, 2001;190:539–551) 相似文献
16.
A nonlinear time-domain procedure is presented which is used to calculate the vertical responses of a container ship advancing
in head waves. The method assumes linear radiation forces represented by time convolution of memory functions, infinite frequency
added masses, and radiation restoring coefficients. The nonlinear hydrostatic restoring and Froude–Krilov forces are computed
exactly over the instantaneous wetted surface of the ship's hull. Forces due to green water on deck are calculated using the
momentum method. Nonlinear effects are identified on different vertical ship responses, namely on the heave and pitch motions,
the vertical accelerations, and the vertical bending moment. These non-linear effects are expressed by the variation of the
transfer function with the wave amplitude, the higher-order harmonics of the time signals, the offset of the time series,
and the asymmetry of the peaks. The numerical results and the quantified nonlinear effects are compared with experimental
results showing an ability to reproduce the main nonlinear effects.
Received: December 17, 2001 / Accepted: January 31, 2002 相似文献
17.
Hiroaki Takamura Koichi Masuda Hisaaki Maeda Masatoshi Bessho 《Journal of Marine Science and Technology》2003,7(4):164-174
Seaquakes, which are characterized by the propagation of vertical earthquake motion at the sea bottom as a compression (longitudinal)
wave, are reported to cause damage to ships, and their effect on floating structures is a matter of great concern. To comprehend
the basic properties of seaquakes, we first discuss a method to calculate the displacement of the seabed when it is subjected
to hydrodynamic pressure. To investigate the interrelationship between the vibration of a floating structure and the deformation
of the seabed, a new boundary integral equation is derived which assumes that the seabed is a semiinfinite homogeneous elastic
solid in order to analyze the seaquake-induced hydrodynamic pressure acting on the floating structure. By considering the
propagation of the seismic wave in the ground and in the water, the incident wave potential in seaquake problems is also deduced
and its characteristics are discussed. Finally, the response of a very large floating structure in a seaquake is investigated
using a fluid force analysis method, and considering the interrelationship between the vibration of the floating structure
and the deformation of the seabed.
Received: August 19, 2002 / Accepted: November 11, 2002
Address correspondence to: H. Takamura (hiroaki_takamura@nishimatsu.co.jp)
Updated from the Japanese original, which won the 2002 SNAJ prize (J Soc Nav Archit Jpn 2001;189:87–92,93–100 and 190:381–386) 相似文献
18.
Process planning for a hull structure defines the assembly sequence of the hull block. Although this activity is very important
because the working strategy defines the production costs, to date it has been done manually. To raise the efficiency of this
process, we developed a practical computer-aided process planning system. It has been developed using deliverables obtained
from advanced computer integrated manufacturing system (CIM; ACIM) for shipbuilding projects sponsored by the Ship and Ocean
Foundation (SOF). The system has a knowledge base which contains the know-how of skilled designers as well as design practices,
and allows the assembly sequence of hull parts and intermediate products to be defined automatically. The system has been
integrated with the shipyard CAD system MATES, and put to practical use.
Received: August 19, 2002 / Accepted: November 25, 2002
Address correspondence to: Y. Sasaki (yuuichi_sasaki@mhi.co.jp)
Updated from the Japanese original, which won the 2002 SNAJ prize (J Soc Nav Archit Jpn 2001;189:309–315) 相似文献
19.
J.F. Shriver H.E. Hurlburt O.M. Smedstad A.J. Wallcraft R.C. Rhodes 《Journal of Marine Systems》2007,65(1-4):3
A 1/32° global ocean nowcast/forecast system has been developed by the Naval Research Laboratory at the Stennis Space Center. It started running at the Naval Oceanographic Office in near real-time on 1 Nov. 2003 and has been running daily in real-time since 1 Mar. 2005. It became an operational system on 6 March 2006, replacing the existing 1/16° system which ceased operation on 12 March 2006. Both systems use the NRL Layered Ocean Model (NLOM) with assimilation of sea surface height from satellite altimeters and sea surface temperature from multi-channel satellite infrared radiometers. Real-time and archived results are available online at http://www.ocean.nrlssc.navy.mil/global_nlom. The 1/32° system has improvements over the earlier system that can be grouped into two categories: (1) better resolution and representation of dynamical processes and (2) design modifications. The design modifications are the result of accrued knowledge since the development of the earlier 1/16° system. The improved horizontal resolution of the 1/32° system has significant dynamical benefits which increase the ability of the model to accurately nowcast and skillfully forecast. At the finer resolution, current pathways and their transports become more accurate, the sea surface height (SSH) variability increases and becomes more realistic and even the global ocean circulation experiences some changes (including inter-basin exchange). These improvements make the 1/32° system a better dynamical interpolator of assimilated satellite altimeter track data, using a one-day model forecast as the first guess. The result is quantitatively more accurate nowcasts, as is illustrated by several model-data comparisons. Based on comparisons with ocean color imagery in the northwestern Arabian Sea and the Gulf of Oman, the 1/32° system has even demonstrated the ability to map small eddies, 25–75 km in diameter, with 70% reliability and a median eddy center location error of 22.5 km, a surprising and unanticipated result from assimilation of altimeter track data. For all of the eddies (50% small eddies), the reliability was 80% and the median eddy center location error was 29 km. The 1/32° system also exhibits improved forecast skill in relation to the 1/16° system. This is due to (a) a more accurate initial condition for the forecast and (b) better resolution and representation of critical dynamical processes (such as upper ocean – topographic coupling via mesoscale flow instabilities) which allow the model to more accurately evolve these features in time while running in forecast mode (forecast atmospheric forcing for the first 5 days, then gradually reverting toward climatology for the remainder of the 30-day forecast period). At 1/32° resolution, forecast SSH generally compares better with unassimilated observations and the anomaly correlation of the forecast SSH exceeds that from persistence by a larger amount than found in the 1/16° system. 相似文献
20.
JAMES S. WEBSTER HOWARD FIREMAN DILLON A. ALLEN ADRIAN J. MACKENNA JOHN C. HOOTMAN 《Naval Engineers Journal》2007,119(2):35-48
The US Navy has been studying the technical and cost impacts associated with the availability and cost of fossil fuel contrasted with nuclear energy alternatives for surface combatants and amphibious warfare ships. Over the past 2 years these efforts have grown in maturity to examine the tactical and strategic implications of our Navy's dependence on fossil fuels from technical, economic, and military perspectives. This paper will present three major topics:
Given the US Navy's dependence on fossil fuels and the expected increase in cost and reduced availability of fossil fuel, propulsion system investment decisions made today will have a profound impact on the future tactical and strategic roles of the US Navy surface fleet. This paper lays the foundation for providing robust and flexible technology decision opportunities for the Navy's future. 相似文献
- ▪
Background research on alternative energy sources.
- ▪
A survey discussion of current and future power and propulsion system technologies.
- ▪
An overview of principal Naval Sea Systems Command studies on the integration of alternative power and propulsion system technologies into notional surface combatants, submarines, and amphibious warfare ships.
Given the US Navy's dependence on fossil fuels and the expected increase in cost and reduced availability of fossil fuel, propulsion system investment decisions made today will have a profound impact on the future tactical and strategic roles of the US Navy surface fleet. This paper lays the foundation for providing robust and flexible technology decision opportunities for the Navy's future. 相似文献