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81.
Lectotype optimization of offshore platforms is of particular importance in the concept design process. Lectotype optimization involves multiple objectives with uncertainty and so is a problem of multiple attribute decision making. To date, there have been few published works on this topic in the context of offshore engineering. This paper develops a framework and methodology for evaluation of offshore platform alternatives, where a fuzzy optimum model is proposed to integrate the influence of each objective in the criteria set, and a new weight-assessing method is developed to mimic the decision maker’s experience and preference based on complementary pairwise comparisons. A case study shows that the new framework and methodology is scientific, reasonable and easy to use in practice. 相似文献
82.
中国沿海常见蓝子鱼形态比较研究 总被引:6,自引:0,他引:6
对中国沿海常见蓝子鱼科鱼类的外部形态、呼吸器官、感觉器官、消化器官、骨骼系统等形态特征进行了比较研究。发现不同种蓝子鱼在体形、鳃耙、耳石、肝脏、牙齿、头骨等特征上存在一定差异,但是种间差异较小,从而推断本科鱼类分化较缓慢。 相似文献
83.
Bulk particulate organic carbon in the East China Sea: Tidal influence and bottom transport 总被引:4,自引:0,他引:4
Five oceanographic surveys were carried out in the East China Sea (ECS) and Yellow Sea from 1999 to 2003. In all, seven different sections were surveyed, but one section (the PN section) was observed on every cruise. Two time-series stations were also surveyed, one located at the Changjiang River mouth, the other over the continental shelf in the PN section.We identified biogeochemical characteristics for waters close to the Changjiang Estuary and in the Kuroshio waters (KW), respectively. Resuspension is a strong feature near bottom over the ECS continental shelf, with suspended matter values 13 times higher than that for the surface. A model of particulate organic carbon (POC) dynamics based on a rectangle equation reveals that POC concentration close to the Changjiang Estuary varies with a semidiurnal period of ∼13 h, coinciding with the tidal period. The upper limit for POC residence times in the seasons we covered over the shelf are estimated to be on the order of weeks and generally increase seaward from near the Changjiang Estuary to the KW. Short POC residence times suggest that POC in the ECS is rapidly exported from euphotic waters.A nepheloid layer, observed as elevated suspended matter in near the bottom of the water column, is important in particle transfer over the shelf, especially in winter when the residual current flows mainly eastward. Cross-shelf transport of POC via the nepheloid layer is estimated to be 0.22 × 1012 g yr−1. Comparison with other work indicates that POC transport is ∼2% of the Changjiang POC input. 相似文献
84.
本文对1987~1988年在山东省部分海岛底栖生物调查时发现的异毛虫科5个种进行了详细的描述并配有插图,其中一种为新亚种,另有3个种在我国为首次记录。 相似文献
85.
2001-2002年天目湖(沙河水库)浮游植物的生态学研究 总被引:7,自引:0,他引:7
2001年6月~2002年5月,对天目湖进行的浮游植物周年调查表明,天目湖共有浮游植物7门75属,其中年平均丰度为5026.20×104个/L,以蓝藻为主,占总丰度的54.45%;而年平均生物量为(15.364±9.103)mg/L,其中硅藻居首位,为6.634 mg/L,占浮游植物年平均生物量的43.18%;其周年变化是丰度和生物量最高值均出现在5月,丰度在5月和9月出现2个峰值,而生物量则在5、7、10月出现3个峰值。浮游植物丰度从大坝处1#点到河流入湖口的9#、10#点变化不明显但略有增加,而生物量则呈明显增加。通过对水温、透明度、营养盐与浮游植物丰度和生物量的线性回归分析发现,浮游植物丰度、生物量与水温、TP存在显著的正相关,而与N/P比、透明度存在显著性负相关,与TN相关性不是很明显。 相似文献
86.
87.
A Unified Variational Principle of Fluid Mechanics and Application on Solitary Subdomain or Point 总被引:1,自引:0,他引:1
-According to basic equations of fluid mechanics, this paper presents a unified variational principle of fluid mechanics (UVPFM) by using the optimization method of weighted residuals (OMWR). The advantages are as follows, the establishment of the functional and the variational principle is easy, it can change various problems of fluid mechanics derived by basic equations into a unified optimization problem, and the solution is the optimum one in some sense. According to the OMWR for the solitary subdomain, this paper uses UVPFM onto any solitary subdomain and gives the solution of the hydrodynamics equation which is suitable only for that solitary subdomain. According to the OMWR for solitary point, this paper uses UVPFM to any solitary point and gives the solution of the hydrodynamics equation (point solution) which is suitable only for that solitary point. As the solution for the solitary subdomain or solitary point is developed independently, the compatibility with other subdomain or other points, do 相似文献
88.
A novel method for prediction of the load carrying capacity of a corroded reinforced concrete beam (CRCB) is presented in the paper. Nine reinforced concrete beams, which had been working in an aggressive environment for more than 10 years, were tested in the laboratory. Comprehensive tests, including flexural test, strength test for corroded concrete and rusty rebar, and pullout test for bond strength between concrete and rebar, were condueted. The flexural test results of CRCBs reveal that the distribution of surface cracks on the beams shows a fractal behavior. The relationship between the fractal dimensions and mechanical properties of CRCBs is then studied. A prediction model based on artificial neural network (ANN) is established by the use of the fractal dimension as the corrosion index, together with the basic intbrmation of the beam. The validity of the prediction model is demonstrated through the experimental data, and satisfactory resuits are achieved. 相似文献
89.
90.