共查询到10条相似文献，搜索用时 46 毫秒
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Particle size of suspended matter in estuaries 总被引：1，自引：0，他引：1
D. Eisma 《Geo-Marine Letters》1991,11(3-4):147-153
Suspended matter usually flocculates into fragile flocs that break up during sampling and analysis. Coulter counter and pipette
size analysis are therefore an indication of floc strength. Grain-size distributions (after removal of organic matter) give
an indication of the relative amount of grains transported as flocs (as opposed to being transported as single particles).In situ size distributions of suspended matter (flocs) in the Scheldt and Rhine estuaries and the Gironde, as well as results from
the Zaire River estuary, indicated that salt flocculation does not appear to be of importance for the formation ofin situ flocs. Also there is no clear relation with particle concentration. In estuaries probably no equilibrium between floc size
and concentration is reached because of the rapid variations in turbulence and bottom shear. In the Zaire estuary a decrease
in turbulence in the surface water results in flocs of the same size as differential settling over a depth of more than 100
meters. 相似文献
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Ishak Haji Omar 《Marine Policy》1983,7(3):220-222
This article focuses on the economics of trawling in a location-specific fishery that is affected by seasonal monsoons. Both field evaluation and econometric models were used to determine the economic performances of trawlers of different tonnages. The findings indicate that in a multispecies monsoon-affected fishery medium-sized vessels in the category of 20–30 tons were most efficient. 相似文献
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The observed trend of peak storm surge ηmax increasing with storm size Rmax, roughly as ηmax ∞ Rmax0.22, particularly on gently sloping coasts, is discussed in relation to the simple 1D analytical solutions for forced long waves due to respectively surface pressure ps and wind stress τw. At constant depth h, the τw-driven surge is proportional to storm size while the ps-driven part is not. This could perhaps be seen to explain why the size-dependence is stronger on flatter slopes where the τw-driven surge dominates. However, this direct size dependence disappears in the sloping beach scenario if the typical depth is assumed proportional to storm size. The observed size dependence is then more likely due to a combination of two 2D effects: Firstly, the sideways radiation from a travelling surge which exceeds the “stationary height” Δp/ρg is relatively weaker for a wider system. Secondly, the wind stress field is a dipole, and the mutual cancellation of the two poles is weaker for larger systems. 相似文献
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河口海岸沉积动力环境复杂，沉积物粗细组分皆有。对于粗细混杂（同时含有砂砾质和泥质成分）的沉积物样品，单一的粒度分析方法不能覆盖整个粒度分布范围，常采用激光-筛分联合法进行粒度分析。由于两种方法的分析原理不同，经常出现细部的激光法结果与粗部的筛分结果部分重合现象，这会影响整个样品的粒度分布计算。石油天然气行业标准《碎屑岩粒度分析方法》（SY/T 5434-2018）对此问题给出了新的解决方案，但是只有文字描述，没有可操作的计算方法。本研究根据该行业标准提出的方案，推算出激光-筛分联合法粒度分析结果的修正计算公式。以浙江舟山群岛潮间带197个粗细混杂样品为例，采用激光-筛分联合法进行了粒度分析，分别采用直接拼接算法及SY/T 5434-2018算法计算了粒度分布，在此基础上对两套算法所得组分含量和粒度参数进行了比较。结果表明，SY/T 5434-2018算法相较于直接拼接算法，扩大了粗颗粒的体积百分比，减少了细颗粒的体积百分比。两种算法得到的组分含量具有显著的线性相关关系，且砾、砂、粉砂、黏土等组分含量的差异从粗到细依次减少。用两种算法的结果分别计算粒度参数，同样具有显著的线性相关关系，且... 相似文献
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Ole A. Mikkelsen Kristian J. Curran Paul S. Hill Timothy G. Milligan 《Estuarine, Coastal and Shelf Science》2007,72(4):615-625
Entropy analysis has been used to classify in situ particle (floc) size spectra of suspended particles into groups based on similar distribution characteristics. Results revealed that the in situ spectra sorted into groups that reflected different forcing conditions (e.g. variations in turbulence). The different forcing conditions were not necessarily reflected in other commonly used distribution measures such as median floc diameter. This suggests that entropy analysis may be an effective approach for investigating the effect of changes in forcing conditions on floc size. It is hypothesized that it may be possible to derive the average shape of floc size spectra from measurement of the forcing conditions alone and subsequently derive parameters such as floc fraction, floc density, floc settling velocity and the optical properties of the water column from the average spectra. 相似文献
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Using multi-angle scattered sound to size fish swimbladders 总被引：1，自引：0，他引：1