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1.
Vertical drains are usually installed in subsoil consisting of several layers. Due to the complex nature of the problem, over the past decades, the consolidation properties of multi‐layered ground with vertical drains have been analysed mainly by numerical methods. An analytical solution for consolidation of double‐layered ground with vertical drains under quasi‐equal strain condition is presented in this paper. The main steps for the computation procedure are listed. The convergence of the series solution is discussed. The comparisons between the results obtained by the present analytical method and the existing numerical solutions are described by figures. The orthogonal relation for the system of double‐layered ground with vertical drains is proven. Finally, some consolidation properties of double‐layered ground with vertical drains are analysed. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
2.
The emergence of artificial neural network (ANN) technology has provided many promising results in the field of hydrology and water resources simulation. However, one of the major criticisms of ANN hydrologic models is that they do not consider/explain the underlying physical processes in a watershed, resulting in them being labelled as black‐box models. This paper discusses a research study conducted in order to examine whether or not the physical processes in a watershed are inherent in a trained ANN rainfall‐runoff model. The investigation is based on analysing definite statistical measures of strength of relationship between the disintegrated hidden neuron responses of an ANN model and its input variables, as well as various deterministic components of a conceptual rainfall‐runoff model. The approach is illustrated by presenting a case study for the Kentucky River watershed. The results suggest that the distributed structure of the ANN is able to capture certain physical behaviour of the rainfall‐runoff process. The results demonstrate that the hidden neurons in the ANN rainfall‐runoff model approximate various components of the hydrologic system, such as infiltration, base flow, and delayed and quick surface flow, etc., and represent the rising limb and different portions of the falling limb of a flow hydrograph. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
3.
Silicon limitation on primary production and its destiny in Jiaozhou Bay, China——Ⅳ:Study on cross-bay transect from estuary to ocean 总被引:1,自引:0,他引:1
The authors analyzed the data collected in the Ecological Station Jiaozhou Bay from May 1991 to November 1994, including 12
seasonal investigations, to determine the characteristics, dynamic cycles and variation trends of the silicate in the bay.
The results indicated that the rivers around Jiaozhou Bay provided abundant supply of silicate to the bay. The silicate concentration
there depended on river flow variation. The horizontal variation of silicate concentration on the transect showed that the
silicate concentration decreased with distance from shorelines. The vertical variation of it showed that silicate sank and
deposited on the sea bottom by phytoplankton uptake and death, and zooplankton excretion. In this way, silicon would endlessly
be transferred from terrestrial sources to the sea bottom. The silicon took up by phytoplankton and by other biogeochemical
processes led to insufficient silicon supply for phytoplankton growth. In this paper, a 2D dynamic model of river flow versus
silicate concentration was established by which silicate concentrations of 0.028–0.062 μmol/L in seawater was yielded by inputting
certain seasonal unit river flows (m3/s), or in other words, the silicate supply rate; and when the unit river flow was set to zero, meaning no river input, the
silicate concentrations were between 0.05–0.69 μmol/L in the bay. In terms of the silicate supply rate, Jiaozhou Bay was divided
into three parts. The division shows a given river flow could generate several different silicon levels in corresponding regions,
so as to the silicon-limitation levels to the phytoplankton in these regions. Another dynamic model of river flow versus primary
production was set up by which the phytoplankton primary production of 5.21–15.55 (mgC/m2·d)/(m3/s) were obtained in our case at unit river flow values via silicate concentration or primary production conversion rate.
Similarly, the values of primary production of 121.98–195.33 (mgC/m2·d) were achieved at zero unit river flow condition. A primary production conversion rate reflects the sensitivity to silicon
depletion so as to different phytoplankton primary production and silicon requirements by different phytoplankton assemblages
in different marine areas. In addition, the authors differentiated two equations (Eqs. 1 and 2) in the models to obtain the
river flow variation that determines the silicate concentration variation, and in turn, the variation of primary production.
These results proved further that nutrient silicon is a limiting factor for phytoplankton growth.
This study was funded by NSFC (No. 40036010), and the Director's Fund of the Beihai Sea Monitoring Center, the State Oceanic
Administration. 相似文献
4.
Effect of Inter-Column Spacing on Soil Stresses due to Vibro-Installed Stone Columns: Interesting Findings 总被引:1,自引:0,他引:1
Hesham Elshazly Mohamed Elkasabgy Azza Elleboudy 《Geotechnical and Geological Engineering》2008,26(2):225-236
This paper reveals the interesting relation between the inter-column spacing and the corresponding alteration of soil state
of stresses due to the vibro-installation technique. This relation is inferred from analyses for load settlement records of
various field load tests, performed for stone columns arrangements with different inter-column spacing values. In order to
have adequate confidence in the findings, a well-documented case history, involving three columns patterns along with their
relevant field and laboratory test results, is utilized for this study. Moreover, a well-tested finite element model, capable
of simulating both elasto-plastic and time dependent soil deformations as well as pore water pressure building and dissipation,
is employed in the analysis. Instead of determining the soil response to the test load, based on known initial soil stresses
and material properties, the analysis is inversely posed to determine the soil initial stresses, based on the recorded settlements
and the post-installation material properties. The alteration in the soil state of stress is represented by the increase in
the post-installation horizontal to vertical stress ratio, K*, as a function of the inter-column spacing. It is found that this alteration experiences a systematic decrease in its magnitude
as the inter-column spacing increases. 相似文献
5.
This article follows the transformation process in the fishing industry with specific reference to the emergence of a limited commercial sector. In the policy domain, this sector was accommodated through a “one size fits all approach” to access rights, requiring it to compete with the large-scale commercial sector for the same resources. The strategies and actions of successful and unsuccessful applicants in four fishing communities in South Africa are examined. The paper identifies the key challenges facing the limited commercial sector as being the lack of skills to complete the application process, start up capital or credit, organisation and financial and business acumen. It highlights the disjuncture between the Marine Living Resources Act's stated aims of sustainability, equity and stability and the realities of implementation at a grassroots level. 相似文献
6.
本文介绍了南极中山锚地的选择条件,勘测实施过程及水文、气象特点,并对测量区域作了分析研究与评价,科学地确定了适合科考船抛锚的锚地,致使“雪龙”船首次在中山锚地抛锚试抛成功,结束了中山站附近海域无锚地的历史。 相似文献
7.
黄河河口演变(Ⅰ) --(一)河口水文特征 总被引:6,自引:0,他引:6
本文利用20世纪后半个世纪的完整实测资料,研究了河口径流量与输沙量的变化,自50年代至90年代呈明显递减。对黄河口的水文特征:水情、沙情、断流、离子流量、滨海潮汐、潮流、余流、温、盐度分布、风暴潮、拦门沙与盐水楔等作出定性和定量的论述。对断流的危害、成因及缓解对策作出分析。河口淤积、延伸、改道对黄河下游的影响也作出时空上的定量分析。对1855年以来近代黄河三角洲海岸线变化,作出了定量研究。 相似文献
8.
Tang Rongqing Wang Daoyan Zhang Xixian Egnineer Shanghai Jiao Tong University Shanghai Associate Professor Shanghai Jiao University Shanghai 《中国海洋工程》1993,(3)
- The authors have used a low-cost ROV of observation type for underice surveying of the Nen-Jiang Cross-river oil pipe line in the Da Qing oil field. The operation method, process and the safety measures for severe cold areas are presented. The fruitful tries and experience may be useful to ROV operators in severe cold areas. 相似文献
9.
依据水面红外发射和红外遥感测温原理,采用HDG-高灵敏度红外测温仪和常规测量仪器相结合的方法,在实验室空气稳定条件下,模拟测得了水面皮层破坏-复原(重建)的热力过程和气-水温差对水面皮层复原过程的影响,获得了大量的测量数据。数据分析表明,当气-水温差从3.0℃变为11.5℃时,水面皮层破坏可导致皮温增量从气-水温差3.0℃时的0.15℃变到11.5℃时的0.45℃,并发现恢复时间与气-水温差呈负线性关系。 相似文献
10.
Song Jinming 《海洋学报(英文版)》1997,16(4):557-562
Binogeochemical process of major elements in sining particulate of Nansha coral reef lagoons,South TXBinogeochemicalprocessofm... 相似文献