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Sample records for choogata futai kozobutsu

  1. Numerical response analysis of a large mat-type floating structure in regular waves; Matogata choogata futai kozobutsu no haro oto kaiseki

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    Yasuzawa, Y.; Kagawa, K.; Kitabayashi, K. [Kyushu University, Fukuoka (Japan); Kawano, D. [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)

    1997-08-01

    The theory and formulation for the numerical response analysis of a large floating structure in regular waves were given. This paper also reports the comparison between the experiment in the Shipping Research Institute in the Minitry of Transport and the result calculated using numerical analytic codes in this study. The effect of the bending rigidity of a floating structure and the wave direction on the dynamic response of a structure was examined by numerical calculation. When the ratio of structure length and incident wavelength (L/{lambda}) is lower, the response amplitude on the transmission side becomes higher in a wave-based response. The hydrodynamic elasticity exerts a dominant influence when L/{lambda} becomes higher. For incident oblique waves, the maximum response does not necessarily appear on the incidence side. Moreover, the response distribution is also complicated. For example, the portion where any flexible amplitude hardly appears exists. A long structure response can be predicted from a short structure response to some degree. They differ in response properties when the ridigity based on the similarity rule largely differs, irrespective of the same L/{lambda}. For higher L/{lambda}, the wave response can be easily predicted when the diffrection force is replaced by the concentrated exciting force on the incidence side. 13 refs., 14 figs., 3 tabs.

  2. Wave attenuation around a large pontoon-type floating structure; Pontoon gata choogata futai shui no haro gensui ni tsuite

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    Kagemoto, H.; Fujino, M.; Ishii, H.; Yamashita, T. [The University of Tokyo, Tokyo (Japan)

    1996-10-01

    With an objective to identify actual conditions of wave attenuation at the bottom of an ultra-large floating structure, a model of a large pontoon-type floating structure was used to measure and discuss wave varying pressure distribution at the bottom of the floating structure subjected to regular waves. The experiment used a pontoon-type model having a length of 6.00 m and a depth of 1.20 m. A pressure sensor was embedded at the bottom of the floating body to measure the wave varying pressure. The experiment was performed in regular waves with wave amplitude kept constant nearly at 1.0 cm, and the wave cycle was changed between 0.475 and 1.000 sec. Angle of encounter with wave was set to four values of 0 degrees, 10 degrees, 45 degrees and 90 degrees. As a result of the experiment, it was verified that the wave varying pressure underneath the floating body agrees well with the linearity potential theoretical value, and the wave varying pressure attenuates to nearly zero inside the floating body from its end above waves to about one wave length. In addition, the pressure distribution in a direction perpendicular to waves was found nearly constant excepting the edges of the floating body. 3 refs., 7 figs.

  3. Structural analyses of very large semi-submersibles in waves; Choogata hansensuishiki futai no harochu kozo oto kaiseki

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    Iijima, K.; Yoshida, K.; Suzuki, H. [The University of Tokyo, Tokyo (Japan)

    1997-08-01

    An analysis method in which the technique of a vehicle obtained when a three-dimensional singular point distribution method and Kagemoto`s mutual interaction theory are combined was expanded for the fluid area was proposed as the structural analysis of very large semi-submersibles in waves. A partial structure method is used for the structure. In a fluid area, the number of unknown quantities appearing in a final expression could be largely reduced by introducing the new concept of a group body. In this process, both hydro-elasticity and hydrodynamic mutual interaction are considered. As a result, floating bodies that could not be previously calculated can be modeled as a three-dimensional frame structure and the response analysis in waves can be carried out without damaging the accuracy. The calculation result is used as the input data required for analyzing the structural fatigue locally during structural design of very large semi-submersibles in the 3,000 (m) class. This study can present a series of procedures between the response analysis of very large floating bodies in waves and the structural design. 11 refs., 14 figs., 1 tab.

  4. Experimental study on the response of very large floating structures (VLFS) in wave; Choogata futaishiki kaiyo kozobutsu no harochu oto ni kansuru jikkenteki kenkyu

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    Ota, M.; Ikegami, H.; Yamaguchi, Y. [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)

    1997-10-01

    The elastic response of VLFS of 1200m long in wave was studied experimentally using a water tank and integral elastic model of 1/80 scale. As offshore airport, a ultra- thin box type floating structure of 5km long, 1km wide and several meter thick is used, and the effect of elasticity is not negligible for such a structure. The experiment used a water tank of 160m long, 30m wide and 3.1m deep. Supposing a water depth of 20m for real VLFSs, the experiment was carried out mainly in a local shallow water area prepared with a temporary bottom together with that in a deep water area. A simple mooring equipment with a linear spring equivalent to real VLFSs was used. The integral floating model was prepared by not mechanical but welded junction to obtain uniform elasticity. The response in wave showed a complicated 3-D behavior, offering useful data for verification of a behavior estimation method. The response was nearly equal between shallow and deep water areas at the same wave length, and the response amplitude in regular waves was equivalent to the significant amplitude in long and short crested irregular waves. 7 refs., 8 figs., 3 tabs.

  5. On the estimation method of hydrodynamic forces acting on a huge floating structure; Choogata futai ni hataraku haryoku ryutairyoku no suiteiho ni kansuru kenkyu

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    Kagemoto, H.; Fujino, M.; Zhu, T. [The University of Tokyo, Tokyo (Japan)

    1996-12-31

    A floating structure such as an international airport is anticipated to have a length of about 5,000 m and a width of about 1,000 m. A singular point method may be used as a method to estimate force that such a floating body is subjected to from waves. In order to derive a solution with practically sufficient accuracy, 1250 elements are required in the length direction and 250 elements in the width direction, or a total of 312,500 elements. Calculating this number of elements should use finally a linear equation system handling complex coefficients comprising 312,500 elements, which would require a huge amount of calculation time. This paper proposes a method to derive solution on wave forces acting on a super-large floating structure or fluid force coefficients such as added mass coefficients and decay coefficients at a practically workable calculation amount and still without degrading the accuracy. The structure was assumed to be a box-shaped structure. Strengths of the singular points to be distributed on each element were assumed to be almost constant except for edges in lateral, oblique and longitudinal waves. Under this assumption, the interior of the floating structure excepting its edges was represented by several large elements to have reduced the number of elements. A calculation method proposed based on this conception was verified of its effectiveness. 2 refs., 25 figs., 3 tabs.

  6. Basic investigation on deflection wave propagation and strength of very large floating structures; Choogata futai kozo no tawami hado denpa kyodo to kyodo ni kansuru kisoteki kosatsu

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    Tsubogo, T.; Okada, H. [University of Osaka Prefecture, Osaka (Japan). Faculty of Engineering

    1997-08-01

    The response strength in which deflection waves propagating in the elastic body of a large floating structure with an order of km in length and width was investigated. Attention was paid to the waves propagating the place fully away from the boundary of a very large floating body so as to obtain the dispersion relation of waves and the relation between incident waves and deflection waves. Next, the frequency response was checked from the aspect of the displacement amplitude and strength for beams and plates. The dispersion relation of waves propagating the place fully away from the boundary of a very large floating body and the relation between the waves and infinite-point incident waves were represented by an expression. Similarly, the waves propagates more than the infinite-point incident waves in frequency, wavelength, and speed. A lower-limit value exists in the propagation speed. The displacement and stress amplitudes are represented by a relational expression. For plates, the displacement amplitude increases when the wave direction coincides with the small-rigidity direction. The stress amplitude is maximized when the waves corresponding to the ``wave below a floating body = size of a characteristic wave number`` reach the large-rigidity direction. 10 refs., 10 figs., 2 tabs.

  7. On the sea-covering effect of a huge floating structure on the surrounding water; Choogata futai shuhen no kaisui ni taisuru kaimen shahei no eikyo ni tsuite

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    Fujino, M.; Kagemoto, H.; Hamada, T. [The University of Tokyo, Tokyo (Japan)

    1996-12-31

    The numerical analysis program based on the difference method for dynamics of sea water with sea-surface displacement, flow rate, salt content and temperature as the parameters is modified to more accurately assess the effects of a huge marine structure on surrounding environment by adding the effects of insolation and boundary conditions of the sea-covering effects of the floating structure. The numerical simulation was done for summer and winter seasons, not in a sea area but using a rectangular bay with the floating structure at the center. A new flow evolves around the floating structure, due to the sea-covering effect. The flow patterns in summer and winter are clearly different, due to difference in insolation. The predicted flow is also sensitive whether stratification is considered or not, by which is meant that it is important what stratification effect is taken into account. Daily insolation changes are accompanied by vertical distribution of water temperature and its temporal change. These effects are also observed under the floating structure which shields insolation. 10 refs., 17 figs., 4 tabs.

  8. Tidal simulation of a bay with a very large floating structure using multi level model; Taso moderu ni yoru choogata futai mawari no ryukyo keisan

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    Hu, Changhong; Kyozuka, Y. [Kyushu Univ., Fukuoka (Japan). Graduate School

    1996-03-29

    Tidal currents and drift currents in a bay with a pontoon type very large floating structure are calculated using a multi-level model. A method of solving two dimensional Poisson equation is proposed to obtain the hydrodynamic pressure under the floating structure. Vertical displacement of the floating structure due to the calculated surrounding water levels can also be calculated. Computation is performed also for tidal flows of a bay to study the effect of the vertical displacement of the pontoon. Lastly, building an airport in the Ariake Sea is assumed as an example, and the effect of the structure on tidal currents is calculated using this method. A floating airport has less effect on tidal currents and residual currents in comparison with a reclaimed island. The horizontal flow velocity under a floating structure increases more than in the case of no platoon, and the effect on the flow rate becomes smaller relatively. There is a little difference in the vertical flow rate between the case of allowing vertical displacement of the platoon and the case of restricting the displacement, but the change in the horizontal flow rate is very little. 5 refs., 11 figs.

  9. On the sea-covering effect of a huge floating structure on the surrounding water; Choogata futai shuhen no kaisui ni taisuru kaimen shahei no eikyo ni tsuite

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    Fujino, M.; Kagemoto, H.; Hamada, T. [The University of Tokyo, Tokyo (Japan)

    1996-12-31

    The numerical analysis program based on the difference method for dynamics of sea water with sea-surface displacement, flow rate, salt content and temperature as the parameters is modified to more accurately assess the effects of a huge marine structure on surrounding environment by adding the effects of insolation and boundary conditions of the sea-covering effects of the floating structure. The numerical simulation was done for summer and winter seasons, not in a sea area but using a rectangular bay with the floating structure at the center. A new flow evolves around the floating structure, due to the sea-covering effect. The flow patterns in summer and winter are clearly different, due to difference in insolation. The predicted flow is also sensitive whether stratification is considered or not, by which is meant that it is important what stratification effect is taken into account. Daily insolation changes are accompanied by vertical distribution of water temperature and its temporal change. These effects are also observed under the floating structure which shields insolation. 10 refs., 17 figs., 4 tabs.

  10. On the prediction of hydroelastic behaviors of a huge floating structure in waves. 2nd Report; Choogata futai no harochu dansei kyodo no suiteiho ni tsuite

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    Murai, M.; Kagemoto, H.; Fujino, M. [The University of Tokyo, Tokyo (Japan)

    1997-08-01

    On the hydroelastic behaviors of a huge floating structure, a mutual interaction theory based on the area division method is used for the analysis of a fluid problem and a mode analysis method is used for the analysis of deformation. On the continuous deformation of a floating structure, the structure is considered as a set of partial structures obtained when the plane shape was divided into squares and discretely handled as a series of rigid motions in the small partial structures obtained by dividing the partial structures more finely. The experimental result in a water tank and the distribution method at a singular point were compared on the deformation of the elastic floating structure estimated by calculation based on this formulation. The result showed that the estimation method on the hydroelastic problem proposed in this paper is valid. On the prediction of hydroelastic behaviors of a huge floating structure, various calculation examples indicate that the hydroelastic behavior is not only the relation between the structure length and wavelength, but also that the bending rigidity of a structure is a very important factor. For a huge floating structure in the 5,000 m class, up to shorter wavelength of about {lambda}/L = 1/100 must be investigated. 6 refs., 14 figs., 5 tabs.

  11. Hydroelastic responses of pontoon type very large floating offshore structures. 2nd Report. Effect of the water depth and the drift forces; Pontoon gata choogata futaishiki kaiyo kozobutsu no harochu chosei oto ni kansuru kenkyu. 2. Senkai eikyo to hyoryuryoku

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    Maeda, H.; Miyajima, S. [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science; Masuda, K.; Ikoma, T. [Nihon University, Tokyo (Japan). College of Science and Technology

    1996-12-31

    Steady-state drift force in regular waves is theoretically analyzed. It is also studied under combined external force experimentally using a two-dimensional water tank. The fluid forces are analyzed by the pressure distribution method based on the potential theory, in which the effects of water depth are taken into account to discuss the effects of elastic deformation of the floating structure on the drift characteristics of steady-state waves. The tests were carried out using a wave-making circulating water tank equipped with a wind duct to create wind, waves and tidal flow. Drift force under a combined external force by wind, wave and/or tidal flow cannot be accurately predicted by arithmetically adding these components. For predicting drift force by tidal flow, it is necessary to take into account drag force in current at the floating structure bottom as well as that in wind at the front face. Drift force by tidal flow is affected by shallowness of water, which should be taken into account for drag forces. The floating structure will be deformed along the wave face as its stiffness decreases, basically decreasing steady-state drift force. 9 refs., 14 figs.

  12. Hydroelastic responses of pontoon type very large floating offshore structures. 2nd Report. Effect of the water depth and the drift forces; Pontoon gata choogata futaishiki kaiyo kozobutsu no harochu chosei oto ni kansuru kenkyu. 2. Senkai eikyo to hyoryuryoku

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    Maeda, H.; Miyajima, S. [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science; Masuda, K.; Ikoma, T. [Nihon University, Tokyo (Japan). College of Science and Technology

    1996-12-31

    Steady-state drift force in regular waves is theoretically analyzed. It is also studied under combined external force experimentally using a two-dimensional water tank. The fluid forces are analyzed by the pressure distribution method based on the potential theory, in which the effects of water depth are taken into account to discuss the effects of elastic deformation of the floating structure on the drift characteristics of steady-state waves. The tests were carried out using a wave-making circulating water tank equipped with a wind duct to create wind, waves and tidal flow. Drift force under a combined external force by wind, wave and/or tidal flow cannot be accurately predicted by arithmetically adding these components. For predicting drift force by tidal flow, it is necessary to take into account drag force in current at the floating structure bottom as well as that in wind at the front face. Drift force by tidal flow is affected by shallowness of water, which should be taken into account for drag forces. The floating structure will be deformed along the wave face as its stiffness decreases, basically decreasing steady-state drift force. 9 refs., 14 figs.

  13. Assessment of a Mega-Float on water quality and ecosystem in Tokyo bay; Choogata futaishiki kaiyo kozobutsu ga Tokyowan no suishitsu to seitaikei ni oyobosu eikyo ni tsuite

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    Kyozuka, Y.; Hu, C.; Hasemi, H. [Kyushu University, Fukuoka (Japan). Faculty of Engineering; Hikai, A.

    1997-08-01

    The effect on the marine environment in the bay when a Mega-Float is installed in a bay was investigated. The physical process such as a residual flow (including tidal currents, water temperature, salt, density, and density currents), and the ecosystem model for which floating organic matter and plankton are handled were incorporated to develop a program for water quality calculation in a bay. The program was used for Tokyo Bay and compared with the conventional calculation result and the oceanograhpic observation result. Simultaneously, the effect on the Mega-Float was considered. On the flow in Tokyo Bay in summer, the calculation result that comparatively coincided with the observation value in a residual flow level was obtained. The horizontal distribution of COD comparatively coincides with the existing observation result. The influence that the Mega-Float exerts on the flow, water temperature, water quality, and ecosystem in the ambient sea area was little and local in the calculation scale (L {times} B {times} d = 6 km {times} 3 km {times} 2 m) of this time. However, the difference occurring due to the design position must also be investigated in future. 12 refs., 8 figs., 5 tabs.

  14. Comparative study of hydroelastic responses of semisubmersible type and pontoon type very large floating structure in waves; Tachushiki semisabugata to pontoon gata choogata futai no harochu dansei oto no hikaku

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    Ma, N.; Hirayama, T.; Sato, N. [Yokohama National University, Yokohama (Japan). Faculty of Engineering

    1996-12-31

    A semisubmersible very large floating structure is compared with an equivalent pontoon type in vertical displacement and longitudinal bending moment in waves. The theoretical calculation is based on the mode synthesis method, and fluid force is analyzed by the three-dimensional singularity method for the symmetric structure, in which the effects of elastic deformation are taken into account. The semisubmersible and pontoon types are not much different from each other in eigenfrequency and mode shape in the dry mode. In the wet mode, on the other hand, the pontoon type is characterized by the synthetic mode in which torsional and bending modes overlap each other, each mode having a similar eigenfrequency. These types are different in elastic response, the pontoon type having several tens times higher coefficient of attenuation than the semisubmersible type. The pontoon type is generally lower in response, but its torsional mode is excited in transverse waves, making it higher than the semisubmersible type at near eigenfrequency of this mode. 15 refs., 17 figs., 2 tabs.

  15. Comparative study of hydroelastic responses of semisubmersible type and pontoon type very large floating structure in waves; Tachushiki semisabugata to pontoon gata choogata futai no harochu dansei oto no hikaku

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    Ma, N.; Hirayama, T.; Sato, N. [Yokohama National University, Yokohama (Japan). Faculty of Engineering

    1996-12-31

    A semisubmersible very large floating structure is compared with an equivalent pontoon type in vertical displacement and longitudinal bending moment in waves. The theoretical calculation is based on the mode synthesis method, and fluid force is analyzed by the three-dimensional singularity method for the symmetric structure, in which the effects of elastic deformation are taken into account. The semisubmersible and pontoon types are not much different from each other in eigenfrequency and mode shape in the dry mode. In the wet mode, on the other hand, the pontoon type is characterized by the synthetic mode in which torsional and bending modes overlap each other, each mode having a similar eigenfrequency. These types are different in elastic response, the pontoon type having several tens times higher coefficient of attenuation than the semisubmersible type. The pontoon type is generally lower in response, but its torsional mode is excited in transverse waves, making it higher than the semisubmersible type at near eigenfrequency of this mode. 15 refs., 17 figs., 2 tabs.

  16. Computation accuracy of flow conditions around a very large floating structure using a multi-layer model. Comparison with experimental results; Taso model ni yoru choogata futai mawari no ryukyo keisan seido ni tsuite. Jikken tono hikaku

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    Kyotsuka, Y. [Kyushu University, Fukuoka (Japan); Omori, H.; Nakagawa, H.; Kobayashi, M. [Mitsui Engineering and Shipbuilding Co. Ltd., Tokyo (Japan)

    1996-04-10

    As one of the environmental problems in sea areas surrounding a very large floating structure (VLFS), change in flow condition is important, and it is one of the factors dominating the prediction of succeeding diffusion and ecosystems. Although a multi-layer model is in wide use for computation of flow condition and diffusion in one inner bay, its applicability should be reexamined because of no consideration of VLFSs. In this study, flow velocity profiles around a barge were then measured through the towing test of a barge in shallow water, and compared with computation results using a multi-layer model. The multi-layer model computed the flow velocity profiles by dividing the flow region to be computed into normal one and that under VLFS, and determined pressures under VLFS by 2-D Poisson`s equation. Slip condition was used as boundary condition at the bottom considering the number of layers under VLFS. Further numerical computation was conducted by 2-D MAC method, in particular, to compare flow around the wake of VLFS with experimental one. Both computation results well agreed with experimental one. 3 refs., 9 figs., 1 tab.

  17. Structural response characteristics of semi-submersible V.L.F.S. in waves and fundamental guideline to the structural design; Choogata hansensuishiki futai no kozo oto tokusei to shoki kozo sekkeiho no kangaekata

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    Iijima, K.; Yoshida, K.; Suzuki, H. [The University of Tokyo, Tokyo (Japan)

    1998-10-01

    Study was made on response characteristics of column- supported and column/lower hull-supported models as typical model of semi-submersible V.L.F.S., using a length of floating structure as main parameter. The improvement method of structural responses was also studied by considering some phenomena derived from responses. In the column-supported model, the peak of quasi-static structural response in lower frequency zone is most important for structure design. In the column/lower hull-supported model, the peak is not important for structure design because only the small peak appears at extremely low frequency. Structural resonance response and matching response due to horizontal bending and torsional oscillation in lower frequency zone are important for design. This phenomenon is more notable for the column/lower hull-supported model subjected to large horizontal wave force. In the simple column-supported model, the response can be analyzed quantitatively using a beam model on an elastic bearing floor. 9 refs., 14 figs., 3 tabs.

  18. Structural response analysis of very large floating structures in waves using one-dimensional finite element model; Ichijigen yugen yoso model ni yoru choogata futai no harochu kozo oto kaiseki

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    Fujikubo, M.; Yao, T.; Oida, H. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering

    1996-12-31

    Formulation was made on a one-dimensional beam finite element which is effective in analyzing structural response of very large floating structures by modeling them on beams on an elastic foundation. This element allows strict solution of vibration response in the beams on the elastic foundation to be calculated efficiently for a case where mass and rigidity change in the longitudinal direction. This analysis method was used to analyze structural response of a large pontoon-type floating structure to investigate mass in the end part for the structural response and the effect of decay while passing the structure. With a pontoon-type floating structure, reduction in bends and bending stress in the end part of the floating structure is important in designing the structure. Reducing the mass in the end part is effective as a means to avoid resonance in these responses and reduce the responses. Increase in rigidity of a floating structure shifts the peak in quasi-static response to lower frequency side, and reduces response in resonance, hence it is advantageous for improving the response. Since incident waves decay while passing through the floating structure, response in the lower wave side decreases. The peak frequency in the quasi-static response also decreases at the end part of the structure in the upper wave side due to decay in wave force. 7 refs., 11 figs., 1 tab.

  19. Consideration on the dynamic behavior and the structural design of large scale floating structure. 2nd Report. Stability of elastic structure and design of elastic response; Choogata futai no kozo kyodo oyobi kozo sekkei ni kansuru kosatsu. 2. Dansei henkei wo koryoshita fukugensei oyobi kozo oto no sekkei

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    Suzuki, H.; Yoshida, K. [The University of Tokyo, Tokyo (Japan)

    1996-12-31

    A policy of improving a very large floating body was planned based on its dynamic characteristics, and a proposal was made thereon. Furthermore, discussions were given on stability that considers effect of elastic deformation required when a structure is mounted on a floating body. With respect to a structural design of a very large floating body in which elastic response is governing, and upon modeling the very large floating body into an aeolotropic plate on an elastic supporting floor, it was shown that the existing range of natural vibration speed in the elastic response is in higher range than the natural vibration speed of heave. It was also indicated that the peak height of response to waves in resonance is inversely proportional to wave frequency, and furthermore, degree of flowing in of vibration energy during the resonance is determined by an inner product of spatial vibration patterns of wave force and the excited mode shape. A proposal was made on a floating body improved of excessive response in the floating body edges by changing the characteristics of the floating body edges. In addition, discussions were given on stability that considers elastic deformation of a floating body that becomes necessary when a structure, such as a building, is built on a very large floating body. 9 refs., 9 figs., 3 tabs.

  20. Wave response analyses of floating crane structure; Crane sen no jobu kozobutsu no haro oto

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    Nobukawa, H.; Takaki, M.; Kitamura, M.; Ahou, G. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering; Higashimura, M. [Fukada Salvage and Marine Works Co. Ltd., Osaka (Japan)

    1996-12-31

    Identifying a dynamic load acting on a lifted load in a floating crane moving in waves is important for preparing an operation manual for the floating crane. Analyses were made on motions in waves of a floating crane with a lifting load of 3,600 tons, with considerations given to deformation of the crane structure. Discussions were given on a dynamic load acting on a lifted load. If a case that considers elastic deformation in the crane structure is compared with a case that does not consider same in calculating hull motions of the floating crane, the difference between them is small if wave length {lambda} to the ship length L is about 0.5. However, if {lambda}/L is 1.0 and 1.5, the difference grows very large. Therefore, the effect of deformation in the crane structure on hull motions of the floating crane cannot be ignored in these cases. A dynamic load acting on a lifted load that considers deformation in the crane structure is about 5% of lifted weight in a headsea condition in which the wave height is 2 m and {lambda}/L is 1.5. As opposed, an estimated value of a dynamic load when the crane structure is regarded as a rigid body is 13%, which is 2.6 times as great as the case that considers deformation of the crane structure. 3 refs., 17 figs., 1 tab.

  1. Systematic analysis on mooring systems of floating structures; Futai keiryuho ni kansuru keitoteki kenkyu

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    Yoshida, K.; Suzuki, H.; Ide, T. [The University of Tokyo, Tokyo (Japan)

    1996-12-31

    Discussed herein are mooring performance requirements of the new types of marine structures now proposed, and characteristic ranges and future expansion potential of the existing mooring systems. The mooring systems studied for floating structures are catenary, single point (multi-leg and single-leg types), fixed structure with fender and tension leg mooring systems. The studied items include extraction of the elements that constitute rigidity of the spring for horizontal mooring, survey on and data collection for each element, determination of element ranges, programs for mooring analysis, assessment of mooring characteristic ranges, and potential development of the characteristic ranges. It is concluded that the existing systems with their current characteristic ranges and future possibility are insufficient for the future marine structures. It is therefore necessary to develop new mooring concepts, instead of expanding the current concepts, in order to meet the mooring performance requirements for the new marine structures. 14 refs., 9 figs., 11 tabs.

  2. Systematic analysis on mooring systems of floating structures; Futai keiryuho ni kansuru keitoteki kenkyu

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    Yoshida, K.; Suzuki, H.; Ide, T. [The University of Tokyo, Tokyo (Japan)

    1996-12-31

    Discussed herein are mooring performance requirements of the new types of marine structures now proposed, and characteristic ranges and future expansion potential of the existing mooring systems. The mooring systems studied for floating structures are catenary, single point (multi-leg and single-leg types), fixed structure with fender and tension leg mooring systems. The studied items include extraction of the elements that constitute rigidity of the spring for horizontal mooring, survey on and data collection for each element, determination of element ranges, programs for mooring analysis, assessment of mooring characteristic ranges, and potential development of the characteristic ranges. It is concluded that the existing systems with their current characteristic ranges and future possibility are insufficient for the future marine structures. It is therefore necessary to develop new mooring concepts, instead of expanding the current concepts, in order to meet the mooring performance requirements for the new marine structures. 14 refs., 9 figs., 11 tabs.

  3. Simple method for analizing multi-leg-structures. 3. ; Study on the lateral vibration of the off-shore structure. Takyaku kozobutsu no kan prime i kaisekiho ni kansuru ichikosatsu. 3. ; Kaiyo kozobutsu no yokoshindo ni kansuru kenkyu

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    Kan, K.; Aso, K.; Doki, H. (Akita Univ., Akita, (Japan). Mining College)

    1990-04-25

    The lateral vibration of the off-shore structure constructed with 8-12 legs was analized. Furthermore, the validity of this method was experimentally examined. The results are as follows: The values of natural frequency and displacement for each structure vibrating in water are independent of the direction of vibration within the ranges of the leg-intervals and the dimentions of legs. The natural frequency obtained by the proposed mehtod, which utilizes two theories, coincides very well with the experimental frequency within the error range that is about 0.00-1.36%. Furthermore, the method in this study gives the fairly well estimation with respect to the amplitude of the lateral vibration, since the error involved in the estimation is only about 9.80-13.7% until the fifth period of vibration. The values of the frequency or displacement estimaated by two theories give the almost same degree of the error range. 4 refs., 13 figs., 3 tabs.

  4. Study on identification of inertial properties for mechanical system; Kikai kozobutsu no kansei tokusei doteiho ni kansuru kenkyu

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    Nakamura, M.; Sawanobori, T.; Kogure, M.; Nishio, S. [Yamanashi University, Yamanashi (Japan); Nagamatsu, A. [Tokyo Institute of Technology, Tokyo (Japan)

    1995-04-20

    It is necessary to recognize inertial properties accurately for modeling during machine development and design. A pendulum method is generally available as the conventional technique that recognizes the inertial properties. This method is difficult to be applied to an intricately shaped matter or heavy matter. Therefore, a characteristic matrix identification method that is very excellent in principle has been proposed, and many studies have been made for practical use. However, the influence that the measurement error of a transfer function used for identification exerts is open to investigation. This paper examined the technique that obtains the inertial characteristics of an elastic-supported mechanical structure using the characteristic matrix identification method. The influence that the measurement point position of the transfer function exerts on an identification error was also investigated. The result showed that the measurement point should be away from the node of the rotation mode as far as possible. This technique was applied to the engine system of a motorcar, and the identification result in a practical level was obtained using a transfer function gotten from the excitation experiment by a hammer. 6 refs., 8 figs., 1 tab.

  5. Design and model experiments on thruster assisted mooring system; Futaishiki kaiyo kozobutsu no thruster ni yoru choshuki doyo seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, M.; Koterayama, W. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Kajiwara, H. [Kyushu Institute of Technology, Kitakyushu (Japan). Faculty of Computer Science and System Engineering; Hyakudome, T. [Kyushu University, Fukuoka (Japan)

    1996-12-31

    Described herein are dynamics and model experiments of the system in which positioning of a floating marine structure by mooring is combined with thruster-controlled positioning. Coefficients of dynamic forces acting on a floating structure model are determined experimentally and by the three-dimensional singularity distribution method, and the controller is designed by the PID, LQI and H{infinity} control theories. A model having a scale ratio of 1/100 was used for the experiments, where 2 thrusters were arranged in a diagonal line, one on the X-axis. It is found that the LQI and H{infinity} controllers of the thruster can control long-cycle rolling of the floating structure. They allow thruster control which is insensitive to wave cycle motion, and efficiently reduce positioning energy. The H{infinity} control regulates frequency characteristics of a closed loop more finely than the LQI control, and exhibits better controllability. 25 refs., 25 figs.

  6. Some considerations about improvement for fatigue strength of structures; Shatai kozobutsu no hiro kyodo kojo ni kansuru ichikosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kimoto, H.; Toyama, K.; Maruyama, H.; Magara, S. [Press Kogyo Co. Ltd., Kanagawa (Japan)

    1997-10-01

    To reduce weight, higher tensile strength and/or thinner plate are used or considered in vehicle structures. In general, welded or notch sections, fatigue strength decreases because of increasing concentrated stress or effect of notch sensitivity and so on. In this paper, some methods are studied to improve fatigue strength and obtain a long life. 2 refs., 11 figs., 5 tabs.

  7. Non-linear mechanical simulations in space structures engineering; Uchu kozobutsu kogaku ni okeru hisenkei kikai rikigaku simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, K. [Kinki Univ Osaka (Japan)

    1997-08-05

    Space structure engineering comes under the combination of different engineering fields. Role of numerical analysis and simulation is large in space structure engineering. Considering space structure engineering as an application of non-linear mechanical simulation, constrains with simulation technology and analysis examples are explained in this paper. Following important points are confirmed by simulating the motion of membrane under external force acting on inner and outer surfaces at a particular point of square satellite model which rotates in tension membrane. When the external force is removed, each material point and membrane centre move with vibration, however centre of gravity of satellite moves very rapidly along the vertical direction of membrane centre. Further external disturbance (which develops on material points) propagates at all material points and membrane centre as a twisted wave. Maximum relative displacement between inner surface and outer surface decreases with the increment of initial angular velocity but not on the points of upper membrane. Fluctuation of position motion of satellite resulted from external disturbance is become small as initial rotation angular velocity increases. 10 refs., 6 figs., 2 tabs.

  8. Design and model experiments on thruster assisted mooring system; Futaishiki kaiyo kozobutsu no thruster ni yoru choshuki doyo seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, M.; Koterayama, W. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Kajiwara, H. [Kyushu Institute of Technology, Kitakyushu (Japan). Faculty of Computer Science and System Engineering; Hyakudome, T. [Kyushu University, Fukuoka (Japan)

    1996-12-31

    Described herein are dynamics and model experiments of the system in which positioning of a floating marine structure by mooring is combined with thruster-controlled positioning. Coefficients of dynamic forces acting on a floating structure model are determined experimentally and by the three-dimensional singularity distribution method, and the controller is designed by the PID, LQI and H{infinity} control theories. A model having a scale ratio of 1/100 was used for the experiments, where 2 thrusters were arranged in a diagonal line, one on the X-axis. It is found that the LQI and H{infinity} controllers of the thruster can control long-cycle rolling of the floating structure. They allow thruster control which is insensitive to wave cycle motion, and efficiently reduce positioning energy. The H{infinity} control regulates frequency characteristics of a closed loop more finely than the LQI control, and exhibits better controllability. 25 refs., 25 figs.

  9. Wave-free floating body forms for a shallow sea area; Senkaiiki no naminashi futai keijo ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Kyozuka, Y.; Nariai, Y. [Kyushu University, Fukuoka (Japan)

    1997-10-01

    In column footing or semi-submergible type marine structures, a vertical wave force vanishes at a specific period of waves. This phenomenon is called wave-free characteristics. This wave-free characteristics make it possible to design marine structures superior in oscillation performance in waves. Since Bessho`s wave-free theory is useful only for an infinite water depth, this paper studied the wave-free theory for a shallow sea area. On a wave-free singularity and required floating body form, 2-D and 3-D axisymmetric floating body forms were determined, and vertical wave force characteristics of the obtained body forms were calculated and verified experimentally. Since the source term of the wave-free singularity was weaker in a shallow sea area than an infinite deep water area, resulting in the narrow width of the obtained wave-free body forms in a shallow sea area. The wave-free theory for a shallow sea area was verified by both numerical calculation based on a singularity distribution method and model experiment for these floating body forms. 3 refs., 10 figs.

  10. Evaluation on the effect of tsunami and seaquake on the floating structure; Tsunami kaishin no futai ni taisuru eikyo hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, K.; Suzuki, H.; Hosomi, I. [The University of Tokyo, Tokyo (Japan); Nahata, H. [The Long-Term Credit Bank of Japan, Ltd., Tokyo (Japan)

    1996-12-31

    The effects of tsunami and seaquake on large floating structures are theoretically studied, where these effects are followed in terms of local strength using the equation proposed by Sells to predict surface shapes changed by seaquake-caused uplift of the seabottom. The equation is combined with the one for tsunami propagation, to better predict the tsunami motion. The simulation results indicate the necessity of considering the effects of tsunami for the design of a large floating structure. The authors discuss that the effect of tsunami is minimized when a floating structure is set at a depth of at least 40 to 50m, chain length should be determined by equalizing the breaking weight with the load at which the structure starts to move, and a structure should be set at a position where it is not attacked by transverse waves. They also discuss that seaquake intensity should be predicted by the equation of motion of compressible fluid, and, noting local strength of a floating structure, it will not be damaged when it is at least 16mm thick under the conditions of 2m as seabottom uplift and 0.5m as draft depth. 15 refs., 9 figs., 2 tabs.

  11. Evaluation on the effect of tsunami and seaquake on the floating structure; Tsunami kaishin no futai ni taisuru eikyo hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, K.; Suzuki, H.; Hosomi, I. [The University of Tokyo, Tokyo (Japan); Nahata, H. [The Long-Term Credit Bank of Japan, Ltd., Tokyo (Japan)

    1996-12-31

    The effects of tsunami and seaquake on large floating structures are theoretically studied, where these effects are followed in terms of local strength using the equation proposed by Sells to predict surface shapes changed by seaquake-caused uplift of the seabottom. The equation is combined with the one for tsunami propagation, to better predict the tsunami motion. The simulation results indicate the necessity of considering the effects of tsunami for the design of a large floating structure. The authors discuss that the effect of tsunami is minimized when a floating structure is set at a depth of at least 40 to 50m, chain length should be determined by equalizing the breaking weight with the load at which the structure starts to move, and a structure should be set at a position where it is not attacked by transverse waves. They also discuss that seaquake intensity should be predicted by the equation of motion of compressible fluid, and, noting local strength of a floating structure, it will not be damaged when it is at least 16mm thick under the conditions of 2m as seabottom uplift and 0.5m as draft depth. 15 refs., 9 figs., 2 tabs.

  12. Outline in 1997 Japan compound material academic meeting technological prize winning technology; Kenchiku, doboku kozobutsu no hoshu{center_dot}hokyo yo forukatousito no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Iba, Yoshitomo.; Uemura, Masahiko.; Murakami, Shinkichi.; Saito, Makoto.; Kobayashi, Akira. [Nittetsu Composite Corp., Tokyo (Japan)

    1999-03-15

    That function declines in the sutra time target, and it is finally destroyed, or a construction structure thing bears putting off that life by managing efficient maintenance it is possible. The factor of the function decline of the structure thing, the degree of the decline, and so on are grasped quantitatively, and efficient repair reinforcement time and a method of construction are chosen, and you must carry it out for that. It is paying attention to the development of the method of construction to reinforce the maintenance repair of the construction structure thing by using the tip compound factor from such a viewpoint. In the beginning, a material cost was very expensive, and the recognition not to use it was very general in such a construction field. In such recognition, in Tonen Corp. incorporated company, it has paid attention to the use possibility in the construction field of the tip compound factor since early, research and development have been done continuously from 1980, that It succeeds in, and it is the method of construction that a repair reinforces a concrete structure thing by the tip material that the method of construction which got the technological prize of the Japan compound material academic meeting in 1997 moved carbon fiber to the center. (NEDO)

  13. Outline in 1997 Japan compound material academic meeting technological prize winning technology. Kenchiku, doboku kozobutsu no hoshu[center dot]hokyo yo forukatousito no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Iba, Yoshitomo.; Uemura, Masahiko.; Murakami, Shinkichi.; Saito, Makoto.; Kobayashi, Akira. (Nittetsu Composite Corp., Tokyo (Japan))

    1999-03-15

    That function declines in the sutra time target, and it is finally destroyed, or a construction structure thing bears putting off that life by managing efficient maintenance it is possible. The factor of the function decline of the structure thing, the degree of the decline, and so on are grasped quantitatively, and efficient repair reinforcement time and a method of construction are chosen, and you must carry it out for that. It is paying attention to the development of the method of construction to reinforce the maintenance repair of the construction structure thing by using the tip compound factor from such a viewpoint. In the beginning, a material cost was very expensive, and the recognition not to use it was very general in such a construction field. In such recognition, in Tonen Corp. incorporated company, it has paid attention to the use possibility in the construction field of the tip compound factor since early, research and development have been done continuously from 1980, that It succeeds in, and it is the method of construction that a repair reinforces a concrete structure thing by the tip material that the method of construction which got the technological prize of the Japan compound material academic meeting in 1997 moved carbon fiber to the center. (NEDO)

  14. Evaluation of deteriorating concrete structures using neural network; Nyuraru nettowaku ni motozuita concrete kozobutsu tenken gijutsusha no shiko katei no hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, N.; Tsutsumi, T. [The Tokyo Electric Power Co. Inc., Tokyo (Japan). Technical Lab.; Shiraki, W. [Tottori Univ., Tottori (Japan). Faculty of Engineering; Matsushima, M. [Tokyo Electric Power Services Co. Ltd., Tokyo (Japan)

    1994-08-20

    In Japan, the phenomena of early deterioration of concrete structures have begun to be pointed out and the importance of maintenance and management services of structures is recognized once again. In this study, since a part of the data of inspecting concrete structures of the existing thermal power plants is available as a data base, a neural network system to evaluate deterioration due to sea salt has been constructed using this data base. The thinking processes so far judged by inspection engineers have been clarified by testing the suitability of the evaluation of the degree of soundness of concrete structures by the above system, and conducting the sensitivity analysis concerning the factors determining the degree of soundness. It has been revealed that the neural network system has shown the accuracy in terms of the number of right answers of as high as 85% in the evaluation of the degree of soundness and it has been found that the system has shown no difference whatsoever from inspection engineers. According to the sensitivity analysis of this system, its sensitivity has become higher in the order of crack width, peeling-off, falling-off and crack alongside a member at the deterioration level II, and at the deterioration level III, the sensitivity of the crack width has become predominant. 22 refs., 5 figs., 4 tabs.

  15. System identification of superstructures with rocking motion and deformation of bases; Kiso ga henkeishi rocking suru kozobutsu no shindo tokusei suiteiho

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Naito, Y.; Uchiyama, S.; Maeda, T.; Matsuda, K. [Kajima Corp., Tokyo (Japan)

    1995-12-20

    Transfer functions of individual parts against bases are generally used as a method for estimating dynamic characteristics of superstructures from observation records of earthquakes or microtremors. However, since soil-structure-interaction (SSI) is included in the observation records, it is difficult to clarify the dynamic characteristics of superstructures, independently. A method has been previously proposed, by which the dynamic characteristics of superstructures without the effect of SSI can be estimated by restricting the vibration mode using equivalent height even in the case of the ground motion condition for multi-particle systems as same as in the case of that for one-particle systems. In this study, this method has been applied to models of SSI systems with rocking and deformation of bases, to estimate the dynamic characteristics of superstructures for ground motion and top excitation conditions. Rigidity of bases was varied as a parameter. Consequently, it was confirmed that the present method can provide accurate estimates of dynamic characteristics of superstructures for both ground motion and top excitation conditions if deformation of bases is not so large. 2 refs., 11 figs., 3 tabs.

  16. Quality assurance in welded structures. Part 3. ; NDT technology enhanced by computer. Yosetsu kozobutsu no hinshitsu hosho. 3. ; Computer riyo ni yoru hihakai shiken no kodoka

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, H.; Ogata, T. (Kawasaki Heavy Industries Ltd., Kobe (Japan))

    1993-09-05

    The basic theory of nondestructive testing (NDT) technology enhanced by computer and its practical example are outlined. Higher reliability of the products, reduction in production cost by automation, countermeasures for dirty, hard and dangerous works, technical communication by skilled workers, and higher efficiency of the products are the principles of enhancement of nondestructive testing. The fields of application of computer to the NDT specially handy, light and cheap micro-computer are numerical analysis, drawings, image processing, automation, artificial intelligence, measurement/control, data reserve and so forth. As for the trend of NTD advancement, radiation penetrating test, automation of probe in ultrasonic flow detection or real time measurement of inspection, three dimensional graphic expression of defect results and so forth are advanced. Future topics are the normalization of appropriate thinking of quality level and improvement and clarification of reliability of NDT. 13 refs., 5 figs., 2 tabs.

  17. Topographical effects on wave exciting forces on huge floating structure. 2; Ogata futaishiki kaiyo kozobutsu ni sayosuru haryoku ni kansuru kenkyu. 2

    Energy Technology Data Exchange (ETDEWEB)

    Imai, Y. [Hiroshima University, Hiroshima (Japan); Okusu, M. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1996-12-31

    A method to predict drift force acting on a floating structure has been developed for a marine structure consisting of a number of floating elements, positioned in a region having a slope at the sea bottom. When a huge marine structure, such as floating air port, is located in a coastal area, scale of the overall structure is very large, of the order of scale of water depth change. The new method assumes that a marine structure consisting of an infinite number of cylindrical floating elements is installed in parallel to the seashore, where symmetrical nature of the configuration allows to predict behavior of the whole system by analyzing one element. Integration of pressures acting on structure surfaces determines the horizontal component of the drift force acting on the structure. Being influenced by topography, drift force predicted peaks at a frequency different from that for the level predicted on the assumption of constant water depth. This indicates the necessity for consideration of seabottom slope and effects of broken waves at the seashore. 6 refs., 12 figs.

  18. Detective examples of steel structures and its countermeasure. Ship and marine structure; Kokozobutsu no hakai jirei to sono taisaku. Senpaku kaiyo kozobutsu

    Energy Technology Data Exchange (ETDEWEB)

    Kawasaki, T.; Tada, M. [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)

    1995-10-01

    Examples of breaking are introduced concerning the welding in vessels and marine structures, and its measures are discussed. Some examples in vessels are a brittle fracture of butt welding zone caused by a defective penetration in a 5,000 ton lumber carrier; a fatigue failure caused by the unevenness of joint of a transverse partition in a bulk freighter; a lamellar tear caused by a restraint imparting in the thickness direction of a panel point; and falling of a leg which was due to a fatigue fracture starting from the crack of a part influenced by welding heat and which caused overturn of a semisubmerged rig. The following are the preventive measures. A welding method and steels mutually matching need to be selected for securing tenacity in a heat-influenced part of a welded joint. Prevention of a lamellar tear requires a design of a proper welding bevel, employment of a low hydrogen type welding electrode and a composition, use of pre-heating and a block welding method. Prevention of a cold crack in welding importantly calls for a setting of a bead length so that the hardness of a heat-influenced part may be 400 Hr or less and also for preheating. 15 refs., 12 figs., 3 tabs.

  19. Topographical effects on wave exciting forces on huge floating structure. 2; Ogata futaishiki kaiyo kozobutsu ni sayosuru haryoku ni kansuru kenkyu. 2

    Energy Technology Data Exchange (ETDEWEB)

    Imai, Y. [Hiroshima University, Hiroshima (Japan); Okusu, M. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1996-12-31

    A method to predict drift force acting on a floating structure has been developed for a marine structure consisting of a number of floating elements, positioned in a region having a slope at the sea bottom. When a huge marine structure, such as floating air port, is located in a coastal area, scale of the overall structure is very large, of the order of scale of water depth change. The new method assumes that a marine structure consisting of an infinite number of cylindrical floating elements is installed in parallel to the seashore, where symmetrical nature of the configuration allows to predict behavior of the whole system by analyzing one element. Integration of pressures acting on structure surfaces determines the horizontal component of the drift force acting on the structure. Being influenced by topography, drift force predicted peaks at a frequency different from that for the level predicted on the assumption of constant water depth. This indicates the necessity for consideration of seabottom slope and effects of broken waves at the seashore. 6 refs., 12 figs.

  20. Experimental study on the estimation method of hydrodynamic force acting on floating offshore structures; Futaishiki kaiyo kozobutsu ni kuwawaru ryutairyoku no suiteiho ni kansuru jikkenteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, K.; Kato, S. [Ship Research Inst., Tokyo (Japan); Koterayama, W. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1996-04-10

    In the design of various floating offshore structures (FOS), the functionality, safety and amenity of FOSs were examined by estimating responses of FOSs to environmental external forces such as wave, wind and flow. In this paper, the estimation method of drag acting on the whole FOS was established by combining previous study results on hydrodynamic force acting on various bodies such as Reynolds number effect (RNE), 3-D effect (TDE) and interference effect (IE). This hydrodynamic force was also compared with that obtained from the experiment result on a FOS model for TLP to confirm the applicability of this estimation method. The estimation result on the drag coefficient in steady flow by considering RNE, TDE and IE well agreed with experimental one. The drag coefficient acting on FOSs in heaving could be estimated in practically sufficient accuracy by considering drag acting on not columns but only square columns. The estimation result on the drag coefficient acting on FOSs in surging by considering RNE, TDE and IE well agreed with experimental one. 12 refs., 10 figs., 1 tab.

  1. Theoretical study on seaquake loads acting on a two-dimensional floating body; Nijigen futai ni hataraku kaishin kaju ni kansuru rironteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Higo, Y.; Ueno, H. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering; Koda, M. [Asahi Glass Co. Ltd., Tokyo (Japan); Nakamori, K. [Nippon Denro MFG. Co. Ltd., Osaka (Japan)

    1996-10-01

    Analyses and discussions were given on characteristics of loads as a result of seaquake acting on a floating body. In the present study, propagation of pressure waves due to vibration in sea bottom ground as propagation of underwater sound waves, and pressures in wave motion fields and loads due to seaquake acting on the floating body were derived by using the Green function which satisfies free surface conditions and sea bottom conditions. In addition, the boundary element method was used to conduct similar calculations to verify the methodological reasonability. As a result of discussions, the following results were obtained: a seaquake load has a resonant point which corresponds to an intrinsic value of the boundary value problem in a closed region; the resonant point moves according to width of the floating body, and the frequency moves to higher frequency side when water depth is shallower; compressibility of fluid cannot be ignored in the vicinity of the frequency for the resonant point; the seaquake load is proportional to width of a vibrating ground on the sea bottom, and the load in the vertical direction decreases when the center of the floating body is separated from the vibrating ground; a load in the horizontal direction presents no problems in a floating body with a shallow draft; and a moment in the lateral direction may present a larger problem than in the load in the vertical direction. 8 refs., 8 figs.

  2. Studies on surface tension effect for free surface flow around floating models; Futai mokei mawari no jiyu hyomenryu ni oyobosu hyomen choryoku no eikyo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, K. [Yokohama National Univ., Yokohama (Japan). Faculty of Engineering; Akiba, H. [Toyo Construction Co. Ltd., Tokyo (Japan)

    1996-12-31

    The effect of surface tension on free surface flow around floating models is discussed experimentally and numerically. Three-dimensional free surface flow around vertical circular cylinders floating in a circulating water channel was visually observed, where a surface-active agent was added to water. The results are analyzed using Weber number. The numerical analysis was done for vertical cylinder and CY100 models using the Rankine source method. Weber number of at least around 120 is necessary to eliminate the effect of surface tension from free surface flow around the CY100 model. The numerical analysis for the cylinder model needs simulation with wavelength shorter than that of free surface wave used by the Rankine source method. The model for the resistance test should be at least around 7m long to eliminate the effect of surface tension at Froude number of 0.1 or higher. 15 refs., 12 figs., 2 tabs.

  3. Studies on surface tension effect for free surface flow around floating models; Futai mokei mawari no jiyu hyomenryu ni oyobosu hyomen choryoku no eikyo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, K. [Yokohama National Univ., Yokohama (Japan). Faculty of Engineering; Akiba, H. [Toyo Construction Co. Ltd., Tokyo (Japan)

    1996-12-31

    The effect of surface tension on free surface flow around floating models is discussed experimentally and numerically. Three-dimensional free surface flow around vertical circular cylinders floating in a circulating water channel was visually observed, where a surface-active agent was added to water. The results are analyzed using Weber number. The numerical analysis was done for vertical cylinder and CY100 models using the Rankine source method. Weber number of at least around 120 is necessary to eliminate the effect of surface tension from free surface flow around the CY100 model. The numerical analysis for the cylinder model needs simulation with wavelength shorter than that of free surface wave used by the Rankine source method. The model for the resistance test should be at least around 7m long to eliminate the effect of surface tension at Froude number of 0.1 or higher. 15 refs., 12 figs., 2 tabs.

  4. Basic studies on design supporting system of offshore structure. Part 2. Implementation of structural design supporting system of offshore structures; Kaiyo kozobutsu wo taisho to shita sekkei shien system ni kansuru kisoteki kenkyu. 2. Kaiyo kozobutsu no kozo sekkei shien system no kochiku

    Energy Technology Data Exchange (ETDEWEB)

    Nomoto, T.; Hamada, K.; Aoyama, K. [The University of Tokyo, Tokyo (Japan)

    1996-12-31

    In order to improve the existing design-supporting system for offshore structures, new functions are added to evaluate information of the products, especially those for structural designs. The structural analysis system should be provided with a function of design modification, to efficiently support the structural analysis of these structures. The new system adds hierarchy of various offshore structure models and three-dimensional dimensions to clarify structural and geometrical constraints and design-modification function. The design-modification function is included by use of the hierarchy. The other new functions are finite element analysis systems for the main structure and components, and rigidity calculation for the main structure. The main structure and functional element models are confirmed to be useful also for utilization of information, and provide necessary information of the product models. 11 refs., 11 figs.

  5. Influence of soil-structure interaction on system identification of building. Part 2. Iterative identification method using regression curves; Jiban kozobutsu sogo sayo ga kozobutsu no shindo tokusei suitei ni oyobosu eikyo. 2. Kaikishiki to hanpuku keisan ni yoru tokusei suiteiho no teian

    Energy Technology Data Exchange (ETDEWEB)

    Yamaya, H.; Naito, Y.; Ishibashi, T. [Kajima Corp., Tokyo (Japan)

    1995-12-20

    When the dynamic characteristics of structures are identified using data obtained from microtremors or earthquakes as well as from vibration tests with an exciter, the effect of soil-structure interaction on the data together with the effects of disturbances, such as wind force, makes it difficult to identify the characteristics of the structure and soil. A method was previously provided for identifying the characteristics of structure and soil-structure interaction respectively using two-particle systems composed of one particle for the super-structure and another for the base. In this paper, a method is proposed for determining two regression curves with two unknown parameters, i.e., a resonance frequency and a damping ratio, through numeric iteration. At first, parameters were extracted, for which regression curves seem relatively easy to obtain according to the previous discussion, and then, regression curves were calculated by numeric iteration to improve accuracy. Consequently, it was found that regression curves can be used to identify unknown parameters when two among four parameters, i.e., resonance frequencies and damping ratios of super-structure and interaction components, are obtained through experiments. 1 ref., 12 figs., 1 tab.

  6. Ultimate strength analysis of thin plated structures using eigen-functions. 3rd Report. Application to reliability analysis; Koyu kansu wo mochiita usuita kozobutsu no dansosei kaisekiho. 3. Shinraisei kaiseki eno oyo

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Y. [Osaka University, Osaka (Japan). Welding Research Institute; Masaoka, K.; Okada, H. [University of Osaka Prefecture, Osaka (Japan). Faculty of Engineering

    1996-12-31

    A reliability analysis was performed on ultimate strength of a hull by introducing reliability engineerings into the idealized structural unit method. Elements developed under the present study were applied to a model of an actual structure to indicate that even an analysis requiring much time under the finite element method can be performed in a short time and at high accuracy when this method is used. Analysis acted with bending moment and shear force simultaneously was performed on a model used as a structure in experiments carried out by Nishihara, assuming pure bending moment and longitudinal strength during slamming. Then, a reliability analysis was conducted on the same model based on this analysis method to investigate the ultimate strength. In an analysis of an ultimate strength when bending and shearing that assume slamming act upon simultaneously, axial force in the hull side decreases as loading increases, wherein how the shearing force increases can be identified clearly. Although existence of initial bends reduces the strength, the effect of variance in the vicinity of the average value on the reliability is rather small, while the effect due to variance in yield stress is greater. 27 refs., 14 figs., 4 tabs.

  7. Investigation on the dynamic response and strength of very long floating structures by beam modeling on an elastic foundation; Dansei shishojo no hari model ni yoru chodai futai kozo no doteki tawami kyodo tokusei ni kansuru kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Tsubogo, T.; Okada, H. [University of Osaka Prefecture, Osaka (Japan). Faculty of Engineering

    1997-08-01

    A very large floating structure was replaced with the beam on an elastic foundation to examine the response characteristics in waves. Another evidence was regularly and numerically given for the basic characteristics of a very large floating body Suzuki found. New information was also obtained. The frequency response is mainly classified into a wave number control area and proper frequency control area when buoyancy elasticity exists. When the buoyancy structure is long and flexible, the proper frequency becomes continuous and the frequency control area becomes a resonance area. In the wave number control area, the Suzuki`s characteristic wave number becomes a control parameter, and various characteristic values are indicated by characteristic wave numbers. The response in the wave number control area becomes quasi-static when the distribution mass of buoyancy is fully small. The design in which the distribution mass of buoyancy is fully large must be avoided. In the displacement amplitude, the mass on the free end is severest. The proper frequency of vertical vibration relatively moves to the high-frequency side when buoyancy is considered as an elastic foundation. Attention must be thus paid to the proper frequency of vibration on the horizontal surface. 9 refs., 12 figs., 3 tabs.

  8. On the hydroelastic response of box-shaped floating structure with shallow draft. Tank test with large scale model; Senkitsusui hakogata futai no harochu dansei oto ni tsuite. Ogata mokei ni yoru suiso shiken

    Energy Technology Data Exchange (ETDEWEB)

    Yago, K.; Endo, H. [Ship Research Inst., Tokyo (Japan)

    1996-12-31

    The hydroelastic response test was carried out in waves using an approximately 10m long large model, and the numerical analysis was done by the direct method, for a commercial-size (300m long) box-shaped floating structure with shallow draft. The scale ratio of the model is 1/30.8, and the minimum wave cycle is around 0.7s from wave-making capacity of the tank, which corresponds to 4 to 14s with the commercial-size structure. Elastic displacement and bending strain were measured. The calculated results by the direct method are in good agreement with the observed results. The fluid dynamic mutual interference effects between elements are weak in added mass but strong in damping force, indicating that the range of mutual interference is strongly related to rolling cycle in the range of mutual interference. Wave pressure on the floating structure bottom is high at the upper side of the wave, greatly damping towards the downside of the wave. However, response amplitude of elastic displacement tends to increase at the ends, both in upside and downside of the wave. For the floating structure studied, the 0 to 4th mode components are predominant in longitudinal waves, and the 6th or higher mode components are negligibly low. 21 refs., 15 figs., 2 tabs.

  9. On the hydroelastic response of box-shaped floating structure with shallow draft. Tank test with large scale model; Senkitsusui hakogata futai no harochu dansei oto ni tsuite. Ogata mokei ni yoru suiso shiken

    Energy Technology Data Exchange (ETDEWEB)

    Yago, K.; Endo, H. [Ship Research Inst., Tokyo (Japan)

    1996-12-31

    The hydroelastic response test was carried out in waves using an approximately 10m long large model, and the numerical analysis was done by the direct method, for a commercial-size (300m long) box-shaped floating structure with shallow draft. The scale ratio of the model is 1/30.8, and the minimum wave cycle is around 0.7s from wave-making capacity of the tank, which corresponds to 4 to 14s with the commercial-size structure. Elastic displacement and bending strain were measured. The calculated results by the direct method are in good agreement with the observed results. The fluid dynamic mutual interference effects between elements are weak in added mass but strong in damping force, indicating that the range of mutual interference is strongly related to rolling cycle in the range of mutual interference. Wave pressure on the floating structure bottom is high at the upper side of the wave, greatly damping towards the downside of the wave. However, response amplitude of elastic displacement tends to increase at the ends, both in upside and downside of the wave. For the floating structure studied, the 0 to 4th mode components are predominant in longitudinal waves, and the 6th or higher mode components are negligibly low. 21 refs., 15 figs., 2 tabs.

  10. Influence of wind force on system identification of buildings during microtremors. Part 3. Mechanism of deformation of transfer function; Joji bido ni yoru kozobutsu no shindo tokusei suitei ni oyobosu kaze no eikyo . 3. Dentatsu kansu ga mikakejo henkasuru mechanism no kento

    Energy Technology Data Exchange (ETDEWEB)

    Ishibashi, T.; Naito, Y.; Yamaya, H.; Sato, K. [Kajima Corp., Tokyo (Japan)

    1995-12-20

    To evaluate the system identification of buildings by measurement of the microtremors, influence of wind force on the result has been investigated taking into account the mechanism of deformation of transfer function. Wind mainly affects the primary vibration of buildings. The primary frequency is almost constant even with changing the wind velocity. The damping ratios of vibration are hardly affected by the wind velocity, when they are determined from the power spectrum at the top of buildings. While, the apparent damping ratios are overestimated for higher wind velocities, when they are determined from the transfer function to the base. The mechanism causing an increase of such damping ratios has been investigated. Assuming that the system of particles with soil-structure interaction or the wave model structure receives the force (wind force) at the upper part, that two types of input force exist at the upper and lower part (wind force and ground motion), and that the two input forces are independent, the mechanism has been examined by using a simple theoretical model. It was found that all these factors remarkably contribute to the increase in the damping ratios. 5 refs., 16 figs., 1 tab.

  11. Development of Aquaphalt, ordinary-temperature and underwater-hardening new material, and its characteristics. ; New material for the water and earthquake proofing of underground structures. Joon shichu kokagata shinzairyo Aquafalt no kaihatsu to tokusei. ; Chichu kozobutsu no bosuiyo, genshin prime yo shin zairyo

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, M.; Idota, Y.; Kouchi, K. (Okumura Corp., Tokyo (Japan))

    1990-10-09

    Shield technique is widely applied to the works of underground structures these days. Materials of cement system used for back-filling injection parts in the shield technique has the tendency to cause cracks; however, there has been a request for the development of a material which plays a role of cushion against ground subsidence. Now, a composite material (called Aquaphalt) which satisfies earthquake and water proofing features was developed, and this report introduces the results of the material {prime} s characteristic tests. Cement and highly water absorptive polymer are mixed in asphalt emulsion, the main component, in this new composite material. The material gelatinizes in 5 - 10 seconds after mixture, and hardens gradually in about 10 hours. As a result of indoor experiments, it was confirmed that the material has favorable water resistance and flexibility. It was also confirmed that the material attains initial strength, which is demanded in shield tunnel works, with the help of a hardening accelerator. Moreover, simulations of tunnel back-filling injection were carried out, and it was testified that this material is applicable with conventional installations. 3 refs., 8 figs., 3 tabs.

  12. Recent trends of deep offshore exploration. From `Survey of Trends and Problems in Floating Structure Operating Technology for Deep Offshore Drilling Systems`; Daisuishin kaiiki ni okeru saikin no tanko kaihatsu doko ni tsuite. `Daisuishin kussaku system no futai un`yo gijutsu i kansuru doko to mondaiten no chosa` yori

    Energy Technology Data Exchange (ETDEWEB)

    Hosomi, A. [The Institute of Energy Economics, Tokyo (Japan)

    1998-06-01

    Japan National Oil Corporation`s survey for fiscal 1997 of deepsea mine exploration and exploitation in the world is described. The survey discloses that future potentials are high in the Mediterranean, Asia, and Oceania although the generally known main deepsea oil-producing zones of the world belong in the Atlantic, as exemplified by the western part of the North Sea. The level of oil exploitation in the ocean that has been 200m or shallower in the past is now advancing deeper toward levels lower than 1000m. As for pilot drilling, although a 2000m-deep level is regarded as the limit beyond which progress deeper would be difficult, yet drilling into a 3000m-deep level is now being planned. Among drilling contractors, reorganization is under way through merger and acquisition. Although the total number of rigs has reduced, demand for rigs turned strong in 1996, and the number of rigs is increasing rapidly through new construction or refurbishment. As for ocean development systems, various practical applications have added to the list of available systems. 3 figs., 6 tabs.

  13. 地震资料在车古201块储层建模中的应用%Application of Seismic Data to Reservoir Modeling of the Chegu 201 Block

    Institute of Scientific and Technical Information of China (English)

    蔡毅; 张祥忠; 张新赏

    2005-01-01

    Great uncertainty exists in reservoir models built for blocks where well spacing is uneven or large. The uncertainty in reservoir models can be significantly reduced by using Coordinate Cokriging Sequential Gaussian Simulation technology, in combination with the restriction of seismic characteristic data. Satisfactory reservoir parameter interpolation results, which are more accurate than those derived only from borehole data, are obtained, giving rise to a reasonable combination of widespread and dense-sampled seismic (soft data) data with borehole data (hard data). A significant effect has been made in reservoir parameter modeling in the Chegu 201 block of the Futai Oilfield by using this technology.

  14. Application of Seismic Data to Reservoir Modeling of the Chegu 201 Block

    Institute of Scientific and Technical Information of China (English)

    CaiYi; ZhangXiangzhong; ZhangXinshang

    2005-01-01

    Great uncertainty exists in reservoir models built for blocks where well spacing is uneven or large. The uncertainty in reservoir models can be significantly reduced by using Coordinate Cokriging Sequential Gaussian Simulation technology, in combination with the restriction of seismic characteristic data. Satisfactory reservoir parameter interpolation results, which are more accurate than those derived only from borehole data, are obtained, giving rise to a reasonable combination of widespread and dense-sampled seismic (soft data) data with borehole data (hard data). A significant effect has been made in reservoir parameter modeling in the Chegu 201 block of the Futai Oilfield by using this technology.

  15. Phylogenetic Status and Morphological Characters of Rhabditolaimus anoplophorae (Rhabditida: Diplogastridae).

    Science.gov (United States)

    Kanzaki, Natsumi; Giblin-Davis, Robin M

    2014-03-01

    Rhabditolaimus anoplophorae Kanzaki and Futai was re-isolated from its type host (carrier), the cerambycid beetle Anoplophora malasiaca, collected in an experimental field of the Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan. The nematode was cultured on nematode growth medium plates seeded with Escherichia coli OP50, and its morphological characters and molecular profile were examined to modernize the description. Scanning electron microscopic and light microscopy revealed the presence of four stomatal flaps, a very long gymnostom, a single ventral papilla in males, and a horizontal slit-like vulval opening in females. The positions of the deirids, hemizonids, phasmids, and rectal glands are additionally described, and the absence of a male bursa was confirmed. Phylogenetically, the genus forms a well-supported clade in the family Diplogastridae. Rhabditolaimus anoplophorae is a member of the monophyletic Rhabditolaimus clade and is closely related to R. leuckarti and several undescribed species.

  16. Lipopolysaccharide-induced multinuclear cells: Increased internalization of polystyrene beads and possible signals for cell fusion

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi-Matsui, Mayumi, E-mail: nakanim@iwate-med.ac.jp; Yano, Shio; Futai, Masamitsu

    2013-11-01

    Highlights: •LPS induces multinuclear cells from murine macrophage-derived RAW264.7 cells. •Large beads are internalized by cells actively fusing to become multinuclear. •The multinuclear cell formation is inhibited by anti-inflammatory cytokine, IL10. •Signal transduction for cell fusion is different from that for inflammation. -- Abstract: A murine macrophage-derived line, RAW264.7, becomes multinuclear on stimulation with lipopolysaccharide (LPS), an outer membrane component of Gram-negative bacteria. These multinuclear cells internalized more polystyrene beads than mononuclear cells or osteoclasts (Nakanishi-Matsui, M., Yano, S., Matsumoto, N., and Futai, M., 2012). In this study, we analyzed the time courses of cell fusion in the presence of large beads. They were internalized into cells actively fusing to become multinuclear. However, the multinuclear cells once formed showed only low phagocytosis activity. These results suggest that formation of the multinuclear cells and bead internalization took place simultaneously. The formation of multinuclear cells was blocked by inhibitors for phosphoinositide 3-kinase, phospholipase C, calcineurin, and c-Jun N-terminal kinase. In addition, interleukin 6 and 10 also exhibited inhibitory effects. These signaling molecules and cytokines may play a crucial role in the LPS-induced multinuclear cell formation.

  17. Lipopolysaccharide induces multinuclear cell from RAW264.7 line with increased phagocytosis activity

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi-Matsui, Mayumi, E-mail: nakanim@iwate-med.ac.jp [Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Futai Special Laboratory, Yahaba, Iwate 028-3694 (Japan); Yano, Shio; Matsumoto, Naomi; Futai, Masamitsu [Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Futai Special Laboratory, Yahaba, Iwate 028-3694 (Japan)

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer LPS induces multinuclear cells from murine macrophage-derived RAW264.7 cells. Black-Right-Pointing-Pointer The multinuclear cells are formed through cell-cell fusion in the presence of Ca{sup 2+}. Black-Right-Pointing-Pointer The multinuclear cells do not express osteoclast-specific enzymes. Black-Right-Pointing-Pointer They internalized more and larger beads than mononuclear cells and osteoclasts. -- Abstract: Lipopolysaccharide (LPS), an outer membrane component of Gram-negative bacteria, induces strong proinflammatory responses, including the release of cytokines and nitric oxide from macrophage. In this study, we found that a murine macrophage-derived line, RAW264.7, became multinuclear through cell-cell fusion after incubation with highly purified LPS or synthetic lipid A in the presence of Ca{sup 2+}. The same cell line is known to differentiate into multinuclear osteoclast, which expresses a specific proton pumping ATPase together with osteoclast markers on stimulation by the extracellular domain of receptor activator of nuclear factor {kappa}B ligand (Toyomura, T., Murata, Y., Yamamoto, A., Oka, T., Sun-Wada, G.-H., Wada, Y. and Futai, M., 2003). The LPS-induced multinuclear cells did not express osteoclast-specific enzymes including tartrate-resistant acid phosphatase and cathepsin K. During multinuclear cell formation, the cells internalized more and larger polystyrene beads (diameter 6-15 {mu}m) than mononuclear cells and osteoclasts. The internalized beads were located in lysosome-marker positive organelles, which were probably phagolysosomes. The LPS-induced multinuclear cell could be a good model system to study phagocytosis of large foreign bodies.