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81.
Historically, Crescent City is one of the most vulnerable communities impacted by tsunamis along the west coast of the United States, largely attributed to its offshore geography. Trans-ocean tsunamis usually produce large wave runup at Crescent Harbor resulting in catastrophic damages, property loss and human death. How to determine the return values of tsunami height using relatively short-term observation data is of great significance to assess the tsunami hazards and improve engineering design along the coast of Crescent City. In the present study, the extreme tsunami heights observed along the coast of Crescent City from 1938 to 2015 are fitted using six different probabilistic distributions, namely, the Gumbel distribution, the Weibull distribution, the maximum entropy distribution, the lognormal distribution, the generalized extreme value distribution and the generalized Pareto distribution. The maximum likelihood method is applied to estimate the parameters of all above distributions. Both Kolmogorov-Smirnov test and root mean square error method are utilized for goodness-of-fit test and the better fitting distribution is selected. Assuming that the occurrence frequency of tsunami in each year follows the Poisson distribution, the Poisson compound extreme value distribution can be used to fit the annual maximum tsunami amplitude, and then the point and interval estimations of return tsunami heights are calculated for structural design. The results show that the Poisson compound extreme value distribution fits tsunami heights very well and is suitable to determine the return tsunami heights for coastal disaster prevention. 相似文献
82.
Non-specific immune response of bullfrog Rana catesbeiana to pathogenic Aeromonas hydrophila was studied to 60 individuals in two groups. Each bullfrog in bacterium-injected group was injected intraperitoneally (i.p.) with 0.2 ml bacterial suspension at a density of 5.2 × 10^6 CFU/ml, while each one in control group injected i.p. with 0.2 ml sterile saline solution (0.85%, w/v). Three bullfrogs in both groups were sampled at 0, 1, 3, 7, 11, 15 and 20 days post-injection (dpi) for the evaluation of non-specific immune parameters. It was observed that intraperitoneal injection of A. hydrophila significantly increased the number of leucocytes and that of NBT-positive cells in peripheral blood. Significant increases in serum bactericidal activity and serum acid phosphatase activity were also observed in the bacterium-injected frogs when compared with those in the control group. However, a significant reduction was detected in vitro in phagocytosis activity of peripheral blood phagocytes. No significant difference in changes in the number of peripheral erythrocytes, serum superoxide dismutase (SOD) activity, and lysozyme activity was detected between the two groups. It is suggested that bullfrogs may produce a series of non-specific immune reactions in response to the A. hydrophila infection. 相似文献
83.
84.
Assessment of point and nonpoint sources pollution in Songhua River Basin,Northeast China by using revised water quality model 总被引:3,自引:1,他引:3
Individual participation of pollutants in the pollution load should be estimated even if roughly for the appropriate environmental management of a river basin. It is difficult to identify the sources and to quantify the load, especially in modeling nonpoint source. In this study a revised model was established by integrating point and nonpoint sources into one-dimensional Streeter-Phelps (S-P) model on the basis of real-time hydrologic data and surface water quality monitoring data in the Jilin Reach of the Songhua River Basin. Chemical oxygen demand (COD) and ammonia nitrogen (NH_3-N) loads were estimated. Results showed that COD loads of point source and nonpoint source were 134 958 t/yr and 86 209 t/yr, accounting for 61.02% and 38.98% of total loads, respectively. NH_3-N loads of point source and nonpoint source were 16 739 t/yr and 14 272 t/yr, accounting for 53.98% and 46.02%, respectively. Point source pollution was stronger than nonpoint source pollution in the study area at present. The water quality of upstream was better than that of downstream of the rivers and cities. It is indispensable to treat industrial wastewater and municipal sewage out of point sources, to adopt the best management practices to control diffuse pollutants from agricultural land and urban surface runoff in improving water quality of the Songhua River Basin. The revised S-P model can be successfully used to identify pollution source and quantify point source and nonpoint source loads by calibrating and validating. 相似文献
85.
The wave crest is an important factor for the design of both fixed and floating marine structures. Wave crest height is a
dominant parameter in assessing the likelihood of wave-in-deck impact and resultant severe damage. Many empirical and theoretical
distribution functions for wave crest heights have been proposed, but there is a lack of agreement between them. It is of
significance to develop a better new nonlinear wave crest height distribution model. The progress in the research of wave
crest heights is reviewed in this paper. Based on Stokes’ wave theory, an approximate nonlinear wave crest-height distribution
formula with simple parameters is derived. Two sets of measured data are presented and compared with various theoretical distributions
of wave crests obtained from nonlinear wave models and analysis of the comparison is given in detail. The new crest-height
distribution model agrees well with observations. Also, the new theoretical distribution is more accurate than the other methods
cited in this paper and has a greater range of applications. 相似文献
86.
A complete set of one-month Acoustic Doppler Profiler (ADP) current data at a station in the southern Yellow Sea (SYS) is analyzed using the rotary spectrum method. The results revealed different rotary properties between barotropic and baroclinic tidal currents. The barotropic and baroclinic tidal currents rotate elliptically counter-clockwise and clockwise, respectively. Meanwhile, baroclinic bottom tidal currents are almost along-isobath. The baroclinic cross-isobath velocities attenuate quickly at the bottom, implying important effects of bottom topography on the cross-isobath motions. 相似文献
87.
The effects of degraded porphyran (P1) and natural porphyran (P) on the lifespan and vitality of Drosophila melanogaster are studied. The porphyrans, added daily to the food medium at 0.2% and 1% concentrations, can significantly increase the lifespan in average of 55.79 and 58.23 d in 0.2% P1 diet females and 1% P1 diet males, extending by 12.29% and 8.60% over the corresponding controls, respectively. The effects of porphyrans on D. melanogaster in heat-stress condition were also examined, and found a remarkable increase in survival time. The results which are consistently associated with the use of porphyrans are related to their free radical scavenger action. Considerable increase in vitality demonstrated that vitalities of middle-aged fly (assessed by measuring their mating capacity) was observed after porphyrans addition. Therefore, porphyrans are effective in reducing the rate of aging, and P1 in low molecular weight is better than natural P. 相似文献
88.
DONG Weihua YIN Xiuqin 《中国地理科学(英文版)》2007,17(2):166-172
Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total nitrogen (N) in the broad-leaved litters ingested by earthworms was researched by means of a laboratory experiment. Experimental samples were collected from broad-leaved Korea Pine mixed forest in Liangshui National Natural Reserve (47°10′50″N, 128°53′20″E) in the northeastern Xiao Hinggan Mountains of Northeast China. The contents of organic C and total N in earthworms, leaf litters and earthworm faeces were analyzed. Results show that the organic C content was in the fol- lowing order: leaf litters>faeces>earthworms, while total N content was contrary to that of the organic C. The organic C contents in the different leaf litters were in the following order: Tilia amurensis>Betula costata>Acer mono, whereas the total N contents in the different leaf litters were: Betula costata>Tilia amurensis>Acer mono. The contents of organic C and total N in the faeces from the different leaf litters were almost consistent with the contents of the leaf litters. After the leaf litters were ingested by earthworms, the organic C, which was transformed to increase earthworms' weights, ac- counted for 3.90%-13.31% of the total ingestion by earthworms, while that in the earthworm faeces accounted for 6.14%-13.70%. The transformed organic C through the other metabolism (e.g., respiration) of earthworms accounted for 75.04%-89.92%. The ingested organic C by earthworms was mostly used for metabolic activities. The N ingested by earthworms was less than organic C. It is estimated that 37.08% of total N was transformed to increase the earthworm's weight, 19.97% into earthworm faeces and 47.86% for the consumption of the earthworm's activities. The earthworms not only increased the content of organic C and total N in the soil, but also decreased the values of C/N in the soil and leaf litters. Earthworms play a major role in the leaf litters' decomposition and transformation. 相似文献
89.
ZHANG Huiyuan LIU Guihuan WANG Jinnan WAN Jun 《中国地理科学(英文版)》2007,17(2):179-185
The ecological protection of the watersheds in China is being confronted with a lot of problems such as soil and water erosion, water pollution at present. Therefore watershed eco-compensation is becoming a question of common interest. Based on the analyses of the major problems and their origins in the watershed protection in China, the paper discusses the concerned policies including relative rules and laws, financial policies and water right transaction policies. Simultaneously the paper reviews the practices carried out in China, including the ecological construction project in the western China, the trans-provincial eco-compensation practice and the small watershed eco-compensation practice. According to the present situation of eco-compensation practices and the future policy requirement, this paper finally puts forward four key problems to be solved in the watershed eco-compensation of China in the future. 相似文献
90.
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