排序方式： 共有32条查询结果，搜索用时 312 毫秒
11.
We analyze multiwavelength observations of an M2.9/1N flare that occurred in AR NOAA 11112 on 16 October 2010. AIA 211 Å EUV images reveal the presence of a faster coronal wave (decelerating from ≈?1390 to ≈?830 km?s?1) propagating ahead of a slower wave (decelerating from ≈?416 to ≈?166 km?s?1) towards the western limb. The dynamic radio spectrum from Sagamore Hill radio telescope shows the presence of a metric type II radio burst, which reveals the presence of a coronal shock wave (speed ≈?800 km?s?1). The speed of the faster coronal wave, derived from AIA 211 Å images, is found to be comparable to the coronal shock speed. AIA 171 Å high-cadence observations showed that a coronal loop, which was located at a distance of ≈?0.32R ⊙ to the west of the flaring region, started to oscillate by the end of the impulsive phase of the flare. The results indicate that the faster coronal wave may be the first driver of the transversal oscillations of coronal loop. As the slower wave passed through the coronal loop, the oscillations became even stronger. There was a plasmoid eruption observed in EUV and a white-light CME was recorded, having velocity of ≈?340?–?350 km?s?1. STEREO 195 Å images show an EIT wave, propagating in the same direction as the lower-speed coronal wave observed in AIA, but decelerating from ≈?320 to ≈?254 km?s?1. These observations reveal the co-existence of both waves (i.e. coronal Moreton and EIT waves), and the type II radio burst seems to be associated with the coronal Moreton wave. 相似文献
12.
The present paper is Part I of a series of three papers prepared by the authors on the methods useful for ultimate limit state assessment of marine structures, that have been developed in the literature during the last few decades. It is considered that such methods are now mature enough to enter day-by-day design and strength assessment practice. The aims of the three papers are to conduct some benchmark studies of such methods on ultimate limit state assessment of (unstiffened) plates, stiffened panels, and hull girders of ships and ship-shaped offshore structures, using some candidate methods such as ANSYS nonlinear finite element analysis (FEA), DNV PULS, ALPS/ULSAP, ALPS/HULL, and IACS common structural rules (CSR) methods. As an illustrative example, an AFRAMAX-class hypothetical double hull oil tanker structure designed by CSR method is studied. In the present paper (Part I), the ultimate limit state assessment of unstiffened plates under combined biaxial compression and lateral pressure loads is emphasized using ANSYS, DNV PULS, and ALPS/ULSAP methods, and their resulting computations are compared. Part II will deal with methods for the ultimate limit state assessment of stiffened panels under combined biaxial compression and lateral pressure using ANSYS, DNV PULS, and ALPS/ULSAP methods, and Part III will treat methods for the progressive collapse analysis of the hull structure using ANSYS, ALPS/HULL, and IACS CSR methods. 相似文献
13.
Bok Kyoung Choi Bong -Chae Kim Byoung -Nam Kim Suk Wang Yoon 《Ocean Science Journal》2006,41(4):195-199
Comparative study was carried out for an acoustic iterative inverse method to estimate bubble size distributions in water.
Conventional bubble sizing methods consider only sound attenuation for sizing. Choi and Yoon [IEEE, 26(1), 125–130 (2001)]
reported an acoustic iterative inverse method, which extracts the sound speed component from the measured sound attenuation.
It can more accurately estimate the bubble size distributions in water than do the conventional methods. The estimation results
of acoustic iterative inverse method were compared with other experimental data. The experimental data show good agreement
with the estimation from the acoustic iterative inverse method. This iterative technique can be utilized for bubble sizing
in the ocean. 相似文献
14.
In tropical waters where temperatures are relatively stable,we investigated whether the relationship between phytoplankton growth and grazing loss rate acros s different habitats around Peninsular Malaysia can be attributed to its eutrophication states.We measured phytoplankton growth(μ) and grazing loss(g) rates in waters off Bachok Marine Research Station(BMRS),located northeast of Peninsular Malaysia.Chlorophyll-a(chl-a) concentration ranged from 2.90 to 15.78 μg/L and was dominated by nanoand micro-phytoplankton(2 μm in size).Using the Landry and Hassett dilution method,μ at BMRS ranged from 1.02 to 1.58/d whereas g varied from 0.07 to 0.88/d.Grazing accounted for 35% of the primary production at BMRS.A systematic review of available data in waters around Peninsular Malaysia,revealed how μ fluctuated over a wide range(0.01-1.80/d) and correlated with chl a distribution(R2=0.181,P0.001).However,the relationship was only significant at 9 μg/L chl a for mesotrophic waters and 16 μg/L chl a for eutrophic waters.In contrast,g ranged from 0.00 to 1.01/d,and correlated with μ at all locations.The g/μslope ranged from 19% to 84%,and was generally similar for waters around Peninsular Malaysia.However,all the g/μ slopes had a positive y-intercept except for BMRS,and this seemed to suggest the availability of alternative prey supporting grazing at the other stations. 相似文献
15.
Tidal variability in benthic silicic acid fluxes and microphytobenthos uptake in intertidal sediment
Aude Leynaert Sorcha Ní Longphuirt Soonmo An Jae-Hyun Lim Pascal Claquin Jacques Grall Bong Oh Kwon Chul Hwan Koh 《Estuarine, Coastal and Shelf Science》2011
Silicic acid (DSi) benthic fluxes play a major role in the benthic–pelagic coupling of coastal ecosystems. They can sustain microphytobenthos (MPB) development at the water–sediment interface and support pelagic diatoms when river DSi inputs decrease. DSi benthic fluxes have been studied at the seasonal scale but little is known about their dial variations. This study measured the amplitude of such variations in an intertidal area over an entire tidal cycle by following the alteration of DSi pore water concentrations at regular intervals over the flood/ebb period. Furthermore we independently estimated the potential DSi uptake by benthic diatoms and compared it to the variations of DSi pore water concentrations and fluxes. The microphytobenthos DSi demand was estimated from primary production measurements on cells extracted from the sediment. There were large changes in DSi pore water concentration and a prominent effect of tidal pumping: the DSi flushed out from the sediment at rising tide, occurs in a very short period of time, but plays a far more important role in fueling the ecosystem (800 μmol-Si m−2 d−1), than diffusive fluxes occurring throughout the rest of the tidal cycle (2 μmol-Si m−2 d−1). This process is not, to our knowledge, currently considered when describing the DSi cycling of intertidal sediments. Moreover, there was a large potential MPB requirement for DSi (812 μmol-Si m−2 d−1), similar to the advective flow periodically pumped by the incoming tide, and largely exceeded benthic diffusive fluxes. However, this DSi uptake by benthic diatoms is almost undetectable given the variation of DSi concentration profiles within the sediment. 相似文献
16.
Bong Ju Kim 《Ocean Engineering》2010,37(13):1159-1168
The aim of this study was to evaluate the load characteristics of steel and concrete tubular members under jet fire, with the motivation to investigate the jet fire load characteristics in FPSO topsides. This paper is part of Phase II of the joint industry project on explosion and fire engineering of FPSOs (EFEF JIP) (
[Paik and Czujko, 2009] and [Paik, 2010]). To obtain reliable load values, jet fire tests were carried out in parallel with a numerical study. Computational fluid dynamics (CFD) simulation was used to set up an adiabatic wall boundary condition for the jet fire to model the heat transfer mechanism. A concrete tubular member was tested under the assumption that there is no conduction effect from jet fire. A steel tubular member was tested and considered to transfer heat through conduction, convection, and radiation. The temperature distribution, or heat load, was analyzed at specific locations on each type of member. ANSYS CFX, (2008) and KFX, 2007 codes were used to obtain similar fire action in the numerical and experimental methods. The results of this study will provide a useful database to determine design values related to jet fire. 相似文献
17.
Sang Hoon Lee Jang J. Bahk Han J. Kim Kyung E. Lee Hyeong T. Jou Bong C. Suk 《Geo-Marine Letters》2010,30(2):133-142
The depositional characters of densely dated turbidite successions originating from the southwestern margin of the Ulleung
Basin reveal changes in high-resolution frequency, failing areas, and relative volumes of slope failures over the past 29.4
cal. ka. Between 29.4 and 19.1 cal. ka B.P., various thin- to very thick-bedded turbidites accumulated at an average recurrence
interval of ca. 605 years. After 19.1 cal. ka B.P., turbidites were deposited with an average recurrence interval of 3,183
years, and their thickness abruptly decreased upward. These features suggest that various-scale slope failures occurred frequently
during the eustatic lowering of sea level, and the frequency and relative volumes of slope failures suddenly decreased after
sea level began to rise. When sea level was lowest (20.0–19.1 cal. ka B.P.), successive stacks of very thick turbidites can
most likely be ascribed to larger-volume mass failures. An upward change from muddy to sandy turbidites around 21.4 cal. ka
B.P. suggests that the failing areas retrograded from the muddy upper-middle slope to the sandy uppermost slope when sea level
was nearly at its lowest. Based on these findings together with published evidence, frequent mass failures between 29.4 and
19.1 cal. ka B.P. were plausibly triggered by earthquakes, in combination with reduced hydrostatic pressure that promoted
gas-hydrate dissolution during the eustatic lowering of sea level. These data on the frequency, scale, failing areas, and
triggering causes of slope failures along the southwestern margin over the past 29.4 cal. ka, not documented in earlier studies,
provide invaluable information to better understand the basin-scale characters and occurrences of latest Quaternary slope
failures in the Ulleung Basin. 相似文献
18.
The present paper is Part III of a series of three papers on the methods useful for ultimate limit state assessment of ships and ship-shaped offshore structures. It is focused on the methods for the progressive collapse analysis of hull girders under bending moments, in contrast to the previous two papers (Parts I and II), respectively, dealing with methods for the ultimate limit state assessment of unstiffened plates and stiffened panels. An AFRAMAX-class hypothetical double hull oil tanker structure designed by IACS common structural rules (CSR) method is studied as an illustrative example. The ultimate vertical bending moment capacity of the hull structure is then analyzed by ANSYS FEA, ALPS/HULL, and IACS CSR methods, and their resulting computations are compared. 相似文献
19.
Suam Kim Chang-Ik Zhang Jin-Yeong Kim Jae-Ho Oh Sukyung Kang Jae Bong Lee 《Ocean Science Journal》2007,42(3):179-192
Understanding in climate effects on marine ecosystem is essential to utilize, predict, and conserve marine living resources
in the 21s t century. In this review paper, we summariz ed t h e past history and current status of Korean fisheries as well
as the changes in climate and oceanographic phenomena since the 1960s. Ocean ecosystems in Korean waters can be divided into
three, based on the marine commercial fish catches; the demersal ecosystem in the Yellow Sea and the East China Sea, the pelagic
ecosystem in the Tsushima Warm Current from the East China Sea to the East/Japan Sea, and the demersal ecosystem in the northern
part of the East/Japan Sea. Through the interdisciplinary retrospective analysis using available fisheries, oceanographic,
and meteorological information in three important fish communities, the trend patterns in major commercial catches and the
relationship between climate/ environmental variability and responses of fish populations were identified. Much evidence revealed
that marine ecosystems, including the fish community in Korean waters, has been seriously affected by oceanographic changes,
and each species has responded differently. In general, species diversity is lessening, and mean trophic level of each ecosystem
has decreased during the last 3~4 decades. Future changes in fisheries due to global warming are also considered for major
fisheries and aquaculture in Korean waters. 相似文献
20.
Jeong Joo Bong Jung Hoi-Soo Lee Jun-Ho Park Kyung Kyu Kim Seok Yun Woo Han Jun 《Ocean Science Journal》2022,57(3):451-466
Ocean Science Journal - Dadae Beach located in the Nakdong River estuary has been continuously evolving as the result of natural and anthropogenetic activities. Due to the geographic... 相似文献