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61.
Observations of the Fawn Trough Current over the Kerguelen Plateau from instrumented elephant seals 总被引:2,自引:1,他引:1
Fabien Roquet Young-Hyang Park Christophe Guinet Frdric Bailleul Jean-Benoît Charrassin 《Journal of Marine Systems》2009,78(3):377
Due to its great meridional extent and relatively shallow depths, the Kerguelen Plateau constitutes a major barrier to the eastward flowing Antarctic Circumpolar Current in the Indian sector of the Southern Ocean. While most of the Antarctic Circumpolar Current transport is deflected north of the Kerguelen Islands, the remainder ( 50 Sv, 1 Sv = 106 m3 s− 1) must pass south of the islands, most probably through the Fawn and Princess Elizabeth Troughs. However, the paucity of finely resolved quasi-synoptic hydrographic data in this remote and infrequently sampled area has limited the progress in our knowledge of the regional circulation. Since 2004, a new approach using elephant seals from the Kerguelen Islands as autonomous oceanographic profilers has provided new information on the hydrography over the Kerguelen Plateau, covering the entire Antarctic Zone between the Polar Front and Antarctica, with a mean along-track resolution of about 25 km. These finely resolved bio-logged data revealed details of a strong northeastward current found across the Fawn Trough (sill depth: 2600 m; 56°S, 78°E). This so-called Fawn Trough Current transports cold Antarctic waters found mostly south of the Elan Bank, between the Ice Limit (58°S) and the Antarctic Divergence (64°S) in the eastern Enderby Basin, toward the Australian–Antarctic Basin. Our analysis also demonstrates that the Deep Western Boundary Current, which carries cold Antarctic water along the eastern flank of the southern Kerguelen Plateau collides with Fawn Trough Current at the outlet of the Fawn Trough sill. In other words, the Fawn Trough constitutes a veritable bottleneck, channelling the quasi-totality of the Antarctic Circumpolar flow found south of the Polar Front. Thanks to the unprecedented fine resolution of seal-borne data, a branch of flow centered at the Winter Water isotherm of 1 °C is also revealed along the northern escarpment of the Elan Bank, and then along the southern edge of Heard Island. Further analysis of different supplementary data reveals a complex circulation pattern in the entire Enderby Basin, with several distinctive branches of flow being strongly controlled by prominent topographic features such as the Southwest Indian Ridge, Conrad Rise, Elan Bank, and Kerguelen Plateau. This newly emerged frontal structure refines considerably previous large-scale circulation schematics of the area. 相似文献
62.
根据橡胶密封式管接头的作用原理和使用要求,对HXD1型机车制动空气管路冲脱故障产生的原因进行分析。从结构上对橡胶密封式管接头进行改进,并提出采用卡套式管接头代替橡胶密封式管接头的建议。 相似文献
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喷丸处理可以使铁素体不锈钢1Cr17实现表面自身纳米化.对不同工艺的试样进行在高温空气介质中的耐氧化试验,结果表明1Cr17不锈钢经纳米化喷丸后,在氧化20 h后材料的表面可以形成一层富Cr的致密的内氧化物层,有效的防止了材料的进一步氧化.喷丸后又经过退火的试样,在氧化12 h时表面就形成了一层致密的内氧化物层,因为退火可以有效地释放因为喷丸而产生的压应力,可以更好地促进Cr向表面的扩散,更快的在合金表面形成富Cr的氧化物,从而显著提高了合金的抗高温氧化性. 相似文献
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介绍一种利用新型智能电机过载继电器E3 PLUS、现场通信总线DeviceNet及PLC等技术相结合的船舶智能马达控制系统,阐述智能马达控制中心(Smart MCC)的工作原理、功能及应用实例,该系统可以提供电机多种故障检测和诊断功能以及计算机集中控制,使马达控制系统逐步向自动化集成型发展,系统的性能和可靠性高,能最大限度地降低船舶整体运行成本,提高运行效率. 相似文献
67.
李维毅 《铁路通信信号工程技术》2014,(2):79-80
针对目前ZK4型电空转辙机存在的锁闭问题进行分析,并对主要问题的应对措施进行介绍,为实际应用提供理论指导。 相似文献
68.
An adjoint 1-D model was used to determine vertical diffusivity coefficients from temperature profiles collected within a filament escaping from the Galician coast following an upwelling event. The optimisation scheme ended with relatively high diffusivity values within the thermocline (9×10−5 m2 s−1). Such high values are relevant for biogeochemical exchanges between surface and deep waters in stratified areas.The optimised values were several orders of magnitude higher than the bulk of diffusivity measurements recorded with a free-falling device; however, the optimisation solution was consistent with the arithmetic mean of the measurements in the thermocline (7.7×10−5 m2 s−1), giving more weight to the few largest values. Below the thermocline, the data assimilation method failed because of the three-dimensional nature of the advective field of the upwelling system. Ignoring this advective forcing in the model led to estimates that were two orders of magnitude too high.The results suggest that turbulent mixing is a random process where a few intense events determine the average mixing that drives the long-term evolution of the water column structure. This statistical property is very important when one wants to use instantaneous diffusivity measurements for modelling purposes. 相似文献
69.
在借鉴和总结国内外汽车产业在生态设计、减量化制造、废旧汽车回收再利用等方面的先进经验基础上,提出了汽车产业实施循环经济的"4R"原则,按产品生命周期的不同阶段分别探讨了实施循环经济的有效途径,并结合我国的实际特点,提出了相关的政策建议。 相似文献
70.