Computation of wave-making resistance of a catamaran in deep water using a potential-based panel method   总被引：1，自引：0，他引：1  

Md Shahjada Tarafder  Kazuo Suzuki 《Ocean Engineering》2007,34(13):1892-1900

This paper presents a potential-based boundary element method for solving a nonlinear free-surface flow problem for a Wigley catamaran moving with a uniform speed in deep water. Since the interior flow of each monohull of the catamaran is different from the exterior flow, both monohulls must be considered as lifting bodies. The pressure Kutta condition is imposed at the trailing-edge of the lifting body by determining the dipole distribution, which generates required circulation on the lifting part. The effects of wave interference and hull separation on the hydrodynamic characteristics of the catamaran hull are analyzed and the validity of the computer scheme is examined by comparing the wave resistance with the numerical results of others. The present method could be a useful design tool for screening the suitable combinations of hull parameters and hull spacing at the preliminary design stage of catamaran hull.  相似文献   

The estimation of annual production by phytoplankton in Akkeshi Bay,Japan     

Satoru Taguchi  Kazuo Iseki  Teruyoshi Kawamura 《Journal of Oceanography》1977,33(2):97-102

The annual net and gross primary production by phytoplankton in Akkeshi Bay Hokkaido, are estimated to be 146±25 g C m^–2y^–1 and 416±53 g C m^–2y^–1, respectively. The annual means of the net and gross efficiency between primary production and solar radiation are estimated to be 0.26 % and 0.79 %, respectively.  相似文献   

A report on failures of current meter moorings set east of Tsushima Island from 1983 to 1987     

Kazuo Kawatate  Tsunehiro Miita  Yasunori Ouchi  Shinjiro Mizuno 《Progress in Oceanography》1988,21(3-4)

On the basis of field records, we describe failures of current meter moorings deployed in the Tsushima Strait from 1983 to 1987. In order to avoid future failures of current meter moorings, we should communicate frequently with the fishermen's union and deploy the moorings with reserve flotation and acoustic release.  相似文献   

Trajectories of drift bottles released in the Tsushima Strait     

Tsunehiro Miita  Kazuo Kawatate 《Progress in Oceanography》1986,17(3-4)

Kyungsang-Namdo Fisheries Experimental Station released 620 drift bottles in the west strait of the Tsushima Strait from 1932 to 1939. Among them 183 were recovered. Fukuoka Prefectural Fisheries Experimental Station also released 1930 bottles in the east strait between 1954 and 1969. Recovered bottles were 442.The bottles drifted to the south in winter owing to a northwesterly wind, and drifted to the northeast in spring and summer with the Tsushima warm current. Bottles released at the west strait drifted to the north along the east shore of Korea, went around the Ullung Island, and then to the northeast. Drift bottles released at the east strait drifted to the north along the shore of Japan and washed ashore on the coast.  相似文献   

Estimation of seasonal changes in the flow of Shirase Glacier using JERS-1/SAR image correlation     

Kazuki Nakamura  Koichiro Doi  Kazuo Shibuya 《Polar Science》2007,1(2-4):73-83

This paper presents estimates of detailed seasonal variations in ice-flow velocity for Shirase Glacier calculated using data obtained by Japanese Earth Resources Satellite-1 (JERS-1) synthetic aperture radar (SAR). We used 12 pairs of images (44-day repeat cycle) over the interval from 30 April 1996 to 1 July 1998 to estimate ice-flow fields using an image correlation method. Geometric registration was performed with reference to the RADARSAT Antarctic Mapping Project (RAMP) image dataset. Error analysis based on feature mismatch indicated an absolute error of ±0.30 km/a and relative error of ±0.04 km/a in the estimated flow velocity. The obtained ice-flow velocity increases rapidly from the upstream region (1.18 km/a) to the grounding line, where it becomes stagnant (2.32 km/a), before accelerating gradually to 2.62–2.82 km/a in the downstream region and then increasing to 3.05–3.50 km/a at the terminus of the floating ice tongue. The ice-flow velocities in the downstream region are highly variable, depending on both the distance from the grounding line and the observed epoch (season). Most of the obtained seasonal variations in ice-flow velocity at the floating ice tongue are within the range of the associated error estimate, but the annual difference between 1997 (3.11 km/a) and 1998 (3.50 km/a) is significant, reflecting a possible acceleration in the ice-flow velocity in association with the disappearance of the floating ice tongue between April and May of 1998. In terms of the summer–winter difference in averaged air temperature, the large difference recorded in 1997 (17.0 °C) relative to 1996 (13.9 °C) corresponds to a reduced ice-flow velocity in 1997 (approximately 0.20 km/a) relative to that in 1996 (approximately 0.30 km/a), indicating interactions between air, sea ice, and glacier flow in Lützow-Holm Bay.  相似文献   

The response of the subglacial Lake Vostok, Antarctica, to tidal and atmospheric pressure forcing   总被引：1，自引：0，他引：1  

Anja Wendt  Reinhard Dietrich  Jens Wendt  Mathias Fritsche  Valery Lukin  Alexander Yuskevich  rey Kokhanov  Anton Senatorov  Kazuo Shibuya  Koichiro Doi 《Geophysical Journal International》2005,161(1):41-49

  相似文献   

Estimation or simulation? That is the question   总被引：1，自引：0，他引：1  

Jorge Kazuo Yamamoto 《Computational Geosciences》2008,12(4):573-591

The issue of smoothing in kriging has been addressed either by estimation or simulation. The solution via estimation calls for postprocessing kriging estimates in order to correct the smoothing effect. Stochastic simulation provides equiprobable images presenting no smoothing and reproducing the covariance model. Consequently, these images reproduce both the sample histogram and the sample semivariogram. However, there is still a problem, which is the lack of local accuracy of simulated images. In this paper, a postprocessing algorithm for correcting the smoothing effect of ordinary kriging estimates is compared with sequential Gaussian simulation realizations. Based on samples drawn from exhaustive data sets, the postprocessing algorithm is shown to be superior to any individual simulation realization yet, at the expense of providing one deterministic estimate of the random function.  相似文献   

Stick–slip behavior of Indian gabbro as studied using a NIED large-scale biaxial friction apparatus     

Tetsuhiro Togo  Toshihiko Shimamoto  Futoshi Yamashita  Eiichi Fukuyama  Kazuo Mizoguchi  Yumi Urata 《地震学报(英文版)》2015,(2):97-118

This paper reports stick–slip behaviors of Indian gabbro as studied using a new large-scale biaxial friction apparatus, built in the National Research Institute for Earth Science and Disaster Prevention(NIED), Tsukuba, Japan. The apparatus consists of the existing shaking table as the shear-loading device up to 3,600 k N, the main frame for holding two large rectangular prismatic specimens with a sliding area of 0.75 m2 and for applying normal stresses rnup to 1.33 MPa, and a reaction force unit holding the stationary specimen to the ground. The shaking table can produce loading rates v up to 1.0 m/s,accelerations up to 9.4 m/s2, and displacements d up to0.44 m, using four servocontrolled actuators. We report results from eight preliminary experiments conducted with room humidity on the same gabbro specimens at v = 0.1–100 mm/s and rn= 0.66–1.33 MPa, and with d of about 0.39 m. The peak and steady-state friction coefficients were about 0.8 and 0.6, respectively, consistent with the Byerlee friction. The axial force drop or shearstress drop during an abrupt slip is linearly proportional to the amount of displacement, and the slope of this relationship determines the stiffness of the apparatus as1.15 9 108N/m or 153 MPa/m for the specimens we used.This low stiffness makes fault motion very unstable and the overshooting of shear stress to a negative value was recognized in some violent stick–slip events. An abrupt slip occurred in a constant rise time of 16–18 ms despite wide variation of the stress drop, and an average velocity during an abrupt slip is linearly proportional to the stress drop.The use of a large-scale shaking table has a great potential in increasing the slip rate and total displacement in biaxial friction experiments with large specimens.  相似文献