Narrowband acoustic identification of monospecific fish shoals     

Scalabrin  Carla; Diner  Noel; Weill  Alain; Hillion  Alain; Mouchot  Marie-Catherine 《ICES Journal of Marine Science》1996,53(2):181-188

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渤海、黄海沿岸主要港湾假潮的基本特征   总被引：3，自引：0，他引：3  

李坤平  陈则实 《海洋与湖沼》2002,33(2):128-138

基于港湾假潮振动的基本原理，从渤海、黄海沿岸20个验潮站多年水位自记曲线资料获取假潮参数，并对其做了统计分析，给出了假潮的统计特征，还讨论了假潮形成的初步原因。结果表明，该海域主要港湾假潮出现具有明显的局地性、季节性和年际变化；夏季是大振幅假潮（振幅^1)≥80cm）的多发期，冬季基本上不出现；龙口港湾的大振幅假潮最为突出，最大振幅可达293cm；气压和风速、风向突变的良好配合，是发生大振幅假潮的主要原因。  相似文献   

Wave Runup-Rundown Ampu''''tude on Slopes     

Xue Hongchao  Guo Da  Pan Shaohua Zhong Hushui Professors  Hohai University  Nanjing Associate Professors  Hohai University  Nanjing 《中国海洋工程》1991,(1)

This paper gives an overall discussion about water level change on slopes under wave action, including wave runup, wave rundown and wave up-down amplitude, and a suggested formula for their calculation.  相似文献   

A comparative study of the photosynthetic activity among three temperate seagrass species in Northern Japan   总被引：1，自引：0，他引：1  

Maria Luisa Sasil-Orbita  & Hiroshi Mukai 《Marine Ecology》2006,27(4):388-396

The photosynthetic activity of Zostera marina, Zostera asiatica and Phyllospadix iwatensis shoots from populations of Hokkaido (Northern Japan) was determined using the pulse amplitude modulated (PAM) fluorometer. Several fluorescence parameters were measured as a function of irradiance and leaf age: electron transport rate (ETR), quantum yield, photochemical quenching (qP) and non‐photochemical quenching (NPQ). The leaf age determined by the leaf position in the shoot bundle strongly influenced the photosynthetic activity of Z. marina, Z. asiatica and P. iwatensis. Young leaves had the maximum electron transport rate (Zm: Leaf 1 = 15.7, Leaf 2 = 16.3; Za: Leaf 1 = 13.0, Leaf 2 = 12.2; and Pi: Leaf 1 = 12.5, Leaf 2 = 11.7) and showed higher photoprotection (NPQ) than old leaves. Among the studied seagrass species, Z. marina had the highest photosynthetic activity (ETR_max = 15.3), in accordance with the highest production in the field in comparison with the other two seagrass species. The PAM fluorometry technique showed to be effective in determining intraspecific (among‐leaves) and interspecific (among‐species) variation in seagrass photosynthetic activity.  相似文献   

Dynamics of estuarine residual circulation in a narrow channel including tidal-nonlinear effects     

Yoshiaki Shiraki  Tetsuo Yanagi 《Journal of Oceanography》2007,63(3):413-425

Numerical modeling of a semienclosed narrow channel demonstrates the dynamical dependency of an estuarine residual circulation (ERC) on tidal amplitudes. The ERC is defined by tidally-averaged current field. The tidally-averaged fields show that the ERC-strength variation is classified into highly stratified, partially stratified and weakly stratified ranges, respectively. The ERC becomes weaker as the tidal amplitude (and hence vertical mixing) increases in the highly and weakly stratified ranges. However, the ERC becomes stronger oppositely in the partially stratified range. The nonlinear forces induced by tides significantly affect the ERC as well as the pressure gradient force due to the freshwater flux and the vertical stress divergence (vertical eddy viscous force). In particular, the tidal stress and tidally-oscillating component of vertical stress divergence are quite important in ERC dynamics. The latter causes the enhancement of ERC in proportion to the vertical mixing in the partially stratified range.  相似文献   

光电辨认机电子线路的设计     

邹兴长 《中国海洋大学学报(自然科学版)》1988,(3)

放大器,脉冲幅度鉴别器和由移位寄存器组成的延时器,是光电辨认机电子线路的主要组成部分。在简要地介绍了该机整体电子线路的基础上,本文分析了前置放大器的输入耦合方式,高增益,低漂移问题,鉴别器自稳零电路和延时器电路。研究了电路参数与整机性能之间的关系。提出了这些参数的选择原则。  相似文献   

Regional moments,energy levels,and a new discriminant     

Lian-She Zhao  Donald V. Helmberger 《Pure and Applied Geophysics》1996,146(2):281-304

Teleseismic observations of explosions tend to be richer in short-period energy than are earthquakes, thus the effectiveness of them _b M _s discriminant. At regional distances the same basic separation occurs for smaller events in terms ofM _L M ₀ (Woods et al., 1993) andm _b M ₀ (Patton andWalter, 1993). While these studies demonstrate the basic differences in excitation, they suffer in practical application because of the detailed information required in the retrieval ofM ₀ . In this paper, we introduce a new method of discrimination, based on the energy strength (M _E ) from broadband regional records that appears to be effective and efficient. In this method all events are processed as earthquakes, and explosions are distinguished by their stronger energy levels relative to their long-period amplitudes. Results from 29 events recorded by TERRAscope, sampling 15 explosions from NTS and 14 earthquakes from the southwestern United States, are represented, indicating complete separation (45 data points).M _L =3.6 is the smallest event examined to date but the method can probably be extended to even smaller levels in calibrated regions.  相似文献   

三轴应力下花岗岩声发射P波Q值的变化   总被引：2，自引：0，他引：2       下载免费PDF全文

缪君  许昭永 《地震地质》1990,12(4):311-315

50×50×100mm3盈江花岗岩样品在σ3=30MPa、σ2=60MPa时增加σ1直至破裂,用波传播和谱振幅比法测定破裂孕育过程中σ3方向和σ2方向声发射P波Q值。结果表明:1.在σ1<0.07σ1P(最大破裂压强)时,σ3、σ2方向都保持高值,在0.2σ1P≤σ1≤0.551P期间,两个方向的Q值呈现出比较平稳的状态,其平均值Q3大约10至20,σ2方向Q2大约20至30。在σ1>0.55σ1P后,σ3方向Q3值起伏增长较大,而σ2方向Q2值仅在σ1>0.7σ1P后,才起伏增长,幅度不如σ3方向大。2.随压力的增加,在σ3、σ2两方向,低频成分明显加大。3.当σ1>0.951P后,出现一种记录畸变现象,对同一源点声发射,从沿同一方向两道记录上看出,早到波形振幅小,而晚到波形其振幅反而大  相似文献   

Lg magnitude scale in the mainland of China     

Huancheng Ge  Yuewei Ni  Jinghua Li  Caizhong Huang  Yongqin Li  Fenxia Lu  Fuxi Xu  Yaoming Jiang 《地震学报(英文版)》1992,5(3):549-562

The data of short-period seismograms had been collected widely in the mainland area of China not including Xinjiang and Tibet. The physical quantities of Lg wave are determined respectively in the five subregions. The group velocities of priminary arrival and maximum amplitude of Lg wave are equal to 3.54±0.02 km/s and 3.30±0.05 km/s, respectively. The periods of Lg waves are between 0.2s to 1.2s, averaging 0.7s. The γ-values of Lg waves in the five subregions are equal to 0.0034±0.0001 km⁻¹ for East, 0.0031±0.0004 km⁻¹ for Southwest, 0.0027±0.0004 km⁻¹ for Northeast, 0.0022±0.0001 km⁻¹ for South, and 0.0021±0.0002 km⁻¹ for Northwest subreqion, respectively. The average γ-value for the five subregions, γ=0.0027±0.0006 km⁻¹. The relations among the amplitude ratioH/Z, the station correctionD _z andD _h of amplitudes, and among them and station site condition are discussed. The subregional magnitude calibration functions ofm _Lg had been established according to each regional γ-value. From these, the unified magnitude calibration function of Chinese mainland not including Xinjiang and Tibet was given by

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