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91.
This study presents the results of the decoupling of a free-roll decay test by wavelet transforms. A free-roll decay test was performed to determine the coefficients of damping terms in equations of motion. No motion of the model was restricted during the experiment. A slight yaw motion was found while the model was in the free-roll decay motion. It was necessary to extract a pure roll motion from the experimental data. Wavelet transforms were applied to the signals to extract the pure roll motion. The results were compared to those found through the Fourier transform. Discrete wavelet transforms were able to efficiently decouple the test signals, while the continuous wavelet transform and the Fourier transform could not. 相似文献
92.
93.
Todorov JR Elskus AA Schlenk D Ferguson PL Brownawell BJ McElroy AE 《Marine environmental research》2002,54(3-5):691-695
To determine the estrogenicity of effluents from sewage treatment plants (STPs) to larval fish, 2-day-old sunshine bass were exposed to effluents from three STPs serving New York City (NYC), varying in size and treatment level. Estrogenic response was evaluated by measuring vitellogenin (VTG) and estrogen receptor (ER) expression in cytosolic fractions of whole body homogenates. Concentrations of the presumptive endocrine disruptors in the effluents were also measured. VTG and ER levels in sewage-exposed fish were 3-5 times that observed in controls. Combined concentrations of estradiol and estrone ranged from 5 to 13 ng/l and nonylphenol-ethoxylate metabolites (NPEOs: 4-nonylphenol, and 1-, 2-, and 3-nonylphenol-ethoxylates) ranged from 180 to 470 microg/l in chlorinated effluent. Results indicate that both ER and VTG can be used as biomarkers for endocrine disruption in larval fish, and that 4-day exposure to sewage effluent is sufficient to elicit significant expression of these markers in sunshine bass larvae. The extremely higher concentrations of NPEOs found in effluent relative to hormones (approximately 40,000-fold) indicates that surfactant metabolites may be contributing significantly to the estrogenic effects observed. 相似文献
94.
95.
A numerical procedure is described for predicting the motion and structural responses of tension leg platforms (TLPs) in waves. The developed numerical approach, in a TLP is assumed to be flexible instead of rigid, is based on a combination of the three dimensional source distribution method and the finite-element method. The hydrodynamic interactions among TLP members, such as columns and pontoons, are included in the motion and structural response analysis. Numerical results are compared with the experimental and numerical ones. The results of comparison confirmed the validity of the proposed approach. 相似文献
96.
A higher order panel method based on B-spline representation for both the geometry and the solution is developed for the analysis of steady flow around marine propellers. The self-influence functions due to the normal dipole and the source are desingularized through the quadratic transformation, and then shown to be evaluated using conventional numerical quadrature. By selecting a proper order for numerical quadrature, the accuracy of the present method can be increased to the machine limit. The far- and near-field influences are shown to be evaluated based on the same far-field approximation, but the near-field solution requires subdividing the panels into smaller subpanels continuously, which can be effectively implemented due to the B-spline representation of the geometry. A null pressure jump Kutta condition at the trailing edge is found to be effective in stabilizing the solution process and in predicting the correct solution. Numerical experiments indicate that the present method is robust and predicts the pressure distribution on the blade surface, including very close to the tip and trailing edge regions, with far fewer panels than existing low-order panel methods. 相似文献
97.
沉积物对磷酸盐的吸附与释放 总被引:3,自引:0,他引:3
本实验研究黄河口水文站沉积物对黄河水磷的吸附释放过程和东海111号站位沉积物对海水磷的吸附释放过程。并摸拟黄河沉积物在海水中磷的吸附释放过程。结果表明:底沉积物对磷的吸附相当迅速,无论是河泥还是海泥在24h内均能达到吸附平衡。吸附量与沉积物的量和水中原有磷的浓度有关,在不同的pH条件下,沉积物对磷的吸附是有显著差别的 相似文献
98.
用气相色谱仪和气—质联机等方法对黄条鱼师的腐败挥发性化合物进行了定性和定量分析。这将有利于对黄条做一步的生化性质分析和制定其鲜品的国家标准。样品在25℃贮藏5d期间,测定了某些化学指标。结果表明在贮藏1d后,鱼肉变腐臭,挥发性碱基化合物三甲胺和二甲基在贮藏中增加。在5d的贮藏期间发现的挥发性有机酸包括乙酸、丙酸、丁酸、异丁酸、戊酸、异成酸,并且它们的含量不断增加,检测出脂肪氧化产物和含硫化合物,正己醛、3—辛酮、3,5—丰二烯—2—酮,2—壬酮辛烯—3—醇,二甲基三硫化物、1H—吲哚等都是黄条腐败时产生的重要挥发性化合物。应指出的是,2—甲基丁醇、庚醇、苯酚、辛烯—3—醇己醛是黄条中所特有的化合物,其余化合物与其它鱼类的挥发性化合物几乎相近。 相似文献
99.
近几年,全国重点渔业县——荣成市从拓展渔业的生存发展空间、加速渔业的现代化国际化进程的战略高度出发,把大洋渔业作为渔业产业结构调整、渔民转产转业和可持续发展的工作重点,坚持“三个注重”,即注重搞好产业发展规划、注重搞好项目考察论证、注重依靠科技进步,从而使大洋渔业呈现出强劲的发展势头。荣成市决心抓住机遇,从思路调整、配套服务、倾斜支持等方面加大力度,争取使大洋渔业在短时期内有新的起色、新的突破,在国内外大洋渔业开发竞争中占据一席之地。 相似文献
100.