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1.
Due to the geological time scales required for observation of catchment evolution, surrogates or analogues of field data are necessary to understand long‐term processes. To investigate long‐term catchment behaviour, two experimental model catchments that developed without rigid boundaries under controlled conditions are examined and a qualitative and quantitative analysis of their evolution is presented. Qualitatively, the experimental catchments have the visual appearance of field scale data. Observation demonstrates that changes in catchment shape and network form are conservative. Quantitative analysis suggests that the catchments reach an equilibrium form while a reduction in the channel network occurs. While the catchments are laboratory scale models, the results provide insights into field scale behaviour. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
2.
岩石破坏前后曲线分类及脆-延转换围压研究——蚀变岩常规三轴压缩试验Ⅰ 总被引:2,自引:0,他引:2
蚀变岩是工程中少见的软弱岩类,在西南某重大水电工程中,蚀变岩处于工程的重要部位,为保证工程的长期稳定性,对蚀变岩力学特性进行了深入全面的试验研究.通过对孔隙度不同的饱水蚀变岩进行系统的常规三轴压缩试验和总结分析,提出了蚀变岩三轴压缩下破坏前应力.应变曲线可分为3大类,破坏后应力-应变曲线亦可分为3大类的形态模式.并得出结论:蚀变岩的破坏类型受围压与孔隙度的共同影响,在给定的12 MPa围压下蚀变岩以脆性破坏为主,只有孔隙度大于16%且围压大于4 MPa时才有可能进入脆-延转换状态,且脆-延转换围压随孔隙度增加而降低,临界状态应力比随孔隙度增大而增加. 相似文献
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在实验室内, 22. 5±0. 5℃条件下以去头去骨去鳞片去皮的金色小沙丁鱼的纯肉糜为饵料饲养斜带髭鲷幼鱼,测定体重范围在 4. 6~6. 5g的斜带髭鲷的体重、体长的生长曲线及其生态转换效率和特定生长率.实验结果表明,斜带髭鲷的体重、体长在实验期间直线增长,体重、体长的生长曲线分别为Wt(w.w.湿重,下同 ) =0. 391 7t 5. 766 2(R=0. 999 6)和Lt=0. 105t 6. 265(R=0. 989 9).用胃含物法测定斜带髭鲷的胃排空率、日摄食量、日生长量、生态转换效率和特定生长率.实验得到斜带髭鲷消化道的瞬时排空率Rt= 1. 23 4×10-3 (m/m) /h,日摄食量Cd= 1. 342 9g(w.w. ),生态转换效率Eg=29. 50% ±2. 77% [m/m(w.w. ) ],特定生长率SGR=4. 71%±0. 69% [m/m(w.w. ) ]. 相似文献
5.
Chen Guoping Yu Kuang-ming Zhang Jiachang Assistant Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing
Prof. Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing
Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1991,(4)
This paper discusses the effect of berm width and elevation of composite slope on irregular wave run-up. Based on the data obtained from model tests, the formula and distribution of irregular wave run-up on composite slope are derived. The changing of wind speed, width and elevation of the berm are considered comprehensively. The wave run-up with various exceedance probability can be es-timated utilizing the distribution curves of irregular wave run-up. 相似文献
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The food consumption and ecological conversion efficiency of a species marine pelagic andsmall size fish, Hyporhamphus sajori, were determined by using in situ stomach content method presented by Eggers. The results showed that: (1) the fish was taken in food all day, so empty-stomach rate was very low, taking up about 4.5% of the total determined fish number. However, the fish still has significant daily feeding rhythm. A feeding peak was found 0:00 o'clock at night, but feeding level was always high in the daytime; (2) relationship between instantaneous food content in stomach and corresponding time could be described as S_t = a ·e ~(-b ·t). There was not significant difference of instantaneous gastric evacuation rate between two determinations, with average value being 0.13 × 10~(-2)g/ (g·d) (wet weight); (3) the daily food consumption tended to change in irregular waving form, with average value being (10.16×l0~(-2)±1.19×l0~(-2) g/ (g·d) (wet weight) or (55.56 × 10~(-2) ±6.51 × 10~(-2) kJ/ 相似文献
8.
An extensive experimental and computational investigation of the combined and separate effects of free surface and body on the lift characteristics of a pair of fins attached to a strut and fin alone is conducted. The results reveal that the free-surface effect becomes significant when the depth of submergence to chord ratio (H/c) is less than three. The effect of the strut is also realized for shallower depth of submergence of the fins through free-surface deformation leading to a significant change in the incidence angle of the flow to the fins. The numerical results based on the Higher Order Boundary Element Method with the linearized free-surface condition show good agreement with the experimental results for fin (foil) alone even at shallow submergence, but some discrepancies appear for the fin attached to the strut at higher speeds mostly due to the neglect of the nonlinear free-surface effect. 相似文献
9.
D. C. Mason I. J. Davenport R. A. Flather C. Gurney G. J. Robinson J. A. Smith 《Estuarine, Coastal and Shelf Science》2001,53(6):759
A sensitivity analysis of the waterline method of constructing a Digital Elevation Model (DEM) of an intertidal zone using remote sensing and hydrodynamic modelling is described. Variation in vertical height accuracy as a function of beach slope is investigated using a set of nine ERS Synthetic Aperture Radar (SAR) images of the Humber/Wash area on the English east coast acquired between 1992 and 1994. Waterlines from these images are heighted using a hydrodynamic tide-surge model and interpolated using block kriging. On 1:500 slope beaches, an average block height estimation standard deviation of 18–22 cm is achieved. This rises to 27 cm on 1:100 slope beaches, and 32 cm on 1:30 slope beaches. The average heighting error at different slopes is decomposed into components due to waterline heighting error, inadequate sensor resolution and interpolation inaccuracy. It is shown that, at 1:500 slope, waterline heighting error and interpolation inaccuracy are the main error sources, whilst at 1:30 slope, errors due to inadequate sensor resolution become dominant. The ability of the technique to generate intertidal DEMs for almost the entire coastal zone in a complete ERS SAR scene covering 100×100 km is demonstrated. 相似文献
10.
浙江省海塘塘顶高程的确定 总被引:10,自引:1,他引:10
介绍了浙江省海塘塘顶高程确定时所涉及的波浪爬高,越浪量等的计量,同时分析了1997年后浙江省海塘塘顶高程确定的方法,由已建海塘的塘顶高程分析可见,在背水坡和塘顶有保护措施的情况下,采用允许最大越波流量来控制海塘塘顶高程,可适当降低塘身高度。 相似文献