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A combination of δ~(18)O and salinity data was employed to explore the freshwater balance in the Canada Basin in summer 2008.The Arctic river water and Pacific river water were quantitatively distinguished by using different saline end-members.The fractions of total river water,including the Arctic and Pacific river water,were high in the upper 50 m and decreased with depth as well as increasing latitude.In contrast,the fraction of Pacific river water increased gradually with depth but decreased toward north.The inventory of total river water in the Canada Basin was higher than other arctic seas,indicating that Canada Basin was a main storage region for river water in the Arctic Ocean.The fraction of Arctic river water was higher than Pacific river water in the upper 50 m while the opposite was true below 50 m.As a result,the inventories of Pacific river water were higher than those of Arctic river water,demonstrating that the Pacific inflow through the Bering Strait is the main source of freshwater in the Canada Basin.Both the river water and sea-ice melted water in the permanent ice zone were more abundant than those in the region with sea-ice just melted.The fractions of total river water,Arctic river water,Pacific river water increased northward to the north of 82°N,indicating an additional source of river water in the permanent ice zone of the northern Canada Basin.A possible reason for the extra river water in the permanent ice zone is the lateral advection of shelf waters by the Trans-Polar Drift.The penetration depth of sea-ice melted waters was less than 30 m in the southern Canada Basin,while it extended to 125 m in the northern Canada Basin.The inventory of seaice melted water suggested that sea-ice melted waters were also accumulated in the permanent ice zone,attributing to the trap of earlier melted waters in the permanent ice zone via the Beaufort Gyre. 相似文献
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利用1次中强以上地震(M0≥4.7)发生后前6天地震序列的资料,对未来半年内是否可能发生相当(M=M0±0.3)或更大的地震进行模糊聚类分析.根据36个初选问题的Wallen评分,精选出13项能突出表现地震序列的特征参数作为指标.应用模糊聚类的FCM算法对地震序列进行分类,Ⅰ类为M0级中强震后6个月内还有震级为M≥M0-0.3级的地震发生;Ⅱ类为M0级中强震后6个月内无相当或更大的地震。以中国大陆地区1966年以来的48次M0≥4.7级中强震序列资料建立震后判别模型,然后对近期发生的8次强震序列进行了外推检验。 相似文献
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利用15 N示踪法实测南海水体反硝化速率的研究发现,培养水样在长时间密闭放置过程中也会受到外界空气的污染,且其29N2/28N2比值恒定为0.007 35。根据空气背景中29N2/28N2比值恒定的特征,提出基于质量平衡关系校正空气N2污染的方法,通过将样品实测29N2浓度扣除由外界空气贡献的29N2浓度,可获得由生物反硝化作用所产生的29N2准确浓度,进而可计算出准确的反硝化速率。经空气29N2背景校正后,29N2浓度的偏差明显小于未经校正的结果,且29N2浓度与培养时间之间的线性相关性显著加强,凸显出空气29N2背景校正是获取准确反硝化速率的关键。鉴于15 N示踪法已被广泛应用于海洋水体与沉积物反硝化速率的测定中,所提出的空气29N2背景校正方法具有重要的意义。 相似文献
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基于单次散射模型的尾波功率谱分析法,利用四川省地震局与日本东北大学共同建立的成都遥测台网地震波实时处理系统记录的50个地震的数字化地震波形资料,计算了成都遥测台网区域地球介质对应于几个不同频率的Qc值.发现在1.0~20.0 Hz频率范围内,Qc值随频率的变化近似服从幂函数关系Qc=Q0f n.其中Q0值在60.83~178.05之间,平均值为117;n值在0.713~1.159之间,平均值为0.978.结果表明,成都遥测台网区域Qc值对频率有强的依赖关系.与世界上其它地区所得到的结果比较,成都遥测台网区域Qc-1值及其随频率的变化与构造活动强烈地区的值类似,具有强的频率依赖性. 相似文献
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根据36个初选问题的Wallen评分,精选出10项能突出表现地震序列的特征参数作为指标,采用FCM模糊聚类方法对地震序列进行分类,在分类过程中,将地震序列分为两类:I类为M≥6.0强震后六个月内还有震级为M≥5.0的强震发生;Ⅱ类为M≥6.0强震后六个月内无M≥5.0地震。以中国大陆地区1996年以来的26次M≥6.0强震序列建立震后判别模型,然后以近期发生的8次强震序列进行了外推检验。 相似文献
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在日本东北大学NEC PC 98系列微机地震波实时处理软件的基础上,成功开发了IBM PC机型上的地震波实时处理系统,并实际应用于成都遥测地震台网。该系统的技术优势主要在于用AR模型对信号进行预处理以压制干扰,提高信噪比,增加系统的稳定性和可靠性,采用赤池情报量规准则对P波,S波进行自动判读,大大降低了误判率,其人机交互处理采用了鼠标器对波形进行截取,放大及P波,S波进行人工读取,提高了系统效率。 相似文献
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A real time processing system of seismic waves using personal computers-Function and characteristics
Arealtimeprocesingsystemofseismicwavesusingpersonalcomputers—FunctionandcharacteristicsJUNFAN1)(范军)TIANCHANGCHEN1)(陈天长)WEI?.. 相似文献
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