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51.
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
52.
Nonlinear Effect of Wave Propagation in Shallow Water 总被引:5,自引:2,他引:5
LI Ruijie WANG Houjie
Associate Professor Ocean University of Qingdao Qingdao P. R. China.
Graduate Student Ocean University of Qingdao Qingdao P. R. China. 《中国海洋工程》1999,(1)
—In this paper,a nonlinear model is presented to describe wave transformation in shallow wat-er with the zero-vorticity equation of wave-number vector and energy conservation equation.Thenonlinear effect due to an empirical dispersion relation(by Hedges)is compared with that of Dalrymple'sdispersion relation.The model is tested against the laboratory measurements for the case of a submergedelliptical shoal on a slope beach,where both refraction and diffraction are significant.The computation re-sults,compared with those obtained through linear dispersion relation.show that the nonlinear effect ofwave transformation in shallow water is important.And the empirical dispersion relation is suitable for re-searching the nonlinearity of wave in shallow water. 相似文献
53.
In this paper, a new definition of structure system redundancy is proposed in view of the various measures for structure redundancy. By introducing the terms of structure system failure at the mechanism level and equivalent reliability index, the safety for existing offshore platforms can be evaluated by the semi-probabilistic method presented in this paper. Some numerical examples are given and satisfactory results have been obtained. 相似文献
54.
Zusammenfassung Nach einer kurzen Diskussion der theoretischen Grundlagen für die Berechnung der Ausbreitung von schädlichen Beimengungen der Luft auf Grund der Gesetzmäßigkeiten der turbulenten Diffusion wird mit Hilfe der vonPasquill angegebenen empirischen Beziehungen zwischen Streuungsmaßen und Quelldistanz die Formel für die Immissionskonzentration am Boden abgeleitet. An Hand einer Reihe von Beispielen wird das Bodenkonzentrationsfeld relativ zu dem Punkt maximaler Immissionskonzentration berechnet, wobei eine feste Schornsteinhöhe von 40 m und eine für mittlere Emittenten zutreffende Auswurfmenge an schädlichen Gasen vorausgesetzt wird. Die Abbildungen zeigen die starke Modifikation des Konzentrationsfeldes durch die meteorologischen Verhältnisse, je nachdem, ob ein stabiler, indifferenter oder labiler Ausbreitungstyp vorliegt.
Mit 5 Textabbildungen 相似文献
Summary After a short discussion of the theoretical background for the calculation of the spreading of the noxious pollutants of the air based on the laws of turbulent diffusion a formula is derived for the concentration of the immisison on the ground with help of the empirical relations between the dispersion measures and the distance from the source given byPasquill. In some examples the concentration field at the ground relative to the point of maximum immission is calculated, considering a fixed height of the funnel of 40 m and a quantity of noxious gases as usually found with average emittents. The figures show a strong modification of the concentration field by the meteorological situation according to whether the spreading type is stable, indifferent or unstable.
Résumé On discute tout d'abord brièvement les fondements théoriques permettant de calculer la propagation des pollutions atmosphériques; pour ce faire, on se base sur les lois de la diffusion turbulente. On en tire ensuite une formule de calcul de la concentration des immissions à l'aide des relations empiriques dePasquill, relations existant entre les quantités répandues et la distance de la source. On calcule au moyen d'une série d'exemples le champ des concentrations au sol par rapport au point de concentration maximum; pour ce faire, on admet und chemineé fixe de 40 mètres de hauteur et une quantité de gaz nocifs correspondant à une moyenne de polluants. Les figures montrent la forte modification que subit la répartition des concentrations selon les conditions météorologiques, en d'autres termes si l'on a affaire à un type de propagation stable, indifférent ou instable.
Mit 5 Textabbildungen 相似文献
55.
XU Jiongxin Professor Institute of Geography Chinese Academy of Sciences Beijing China 《国际泥沙研究》1997,(3)
LINTRODUCTIONThetributariesofmiddleYellowRiverarefamousintheworldforthehighestsuspendedsedimentconcentrationandsedimentyield.Forexample,atWenjiachuanstationofKuyeheRiverthemeasuredhighestsuspendedconcentrationis1700kg/m',andthemeanannualsedimentyieldis25000t/(kln'.a).Theformationofhyperconcentratedflowsandtheirinfluenceonerosionprocessesareofgreatimportancenotonlyfromatheoreticalpointofviewbutalsoforpracticalpurposes.Therefore,scientistsfromChinaandallovertheworldhavedrawntheirintensio… 相似文献
56.
简述了火山空降碎屑灾害的危害性 ,指出研制火山空降碎屑灾害预测软件包的实际意义。介绍了软件的主要结构框图、软件设计的基本思路和结构设计时的几点考虑。介绍了在VisualBasic6 .0平台下 ,碎屑粒径参数、岩浆黏度、结晶压力、喷出压力、给定时间段和特定区域的各高度层风参数、岩浆动力学参数、喷出物总量、抛射体分布、坍塌阶段碎屑分布和扩散阶段碎屑分布计算等各程序的主要结构及主要功能。介绍了在Mapinfor 6 .0平台下软件的主要功能。给出了实现该软件包各项功能的理论基础和科学依据 ,并展示了 1980年 5月 18日美国圣海伦斯火山喷发的空降碎屑分布计算的实例 ,同时把计算结果与实际观测数据进行了对比 ,从而使模型的改进工作和软件的正确性得到了验证。最后 ,对软件存在的缺陷和需要进一步改进之处进行了细致的分析 相似文献
57.
Qiu Dahong Zang Jun Jia Ying
Academician of the Chinese Academy of Sciences Professor the State Key Laboratory of Coastal Offshore Engineering 《中国海洋工程》1996,(2)
Based on the 2nd order cnoidal wave theory, the characters of shallow water standing waves and their action on vertical walls are studied in this paper. The theoretical expressions of the wave surface elevation in front of and the wave pressure on the vertical wall are obtained. In order to verify the theoretical results, model tests were made in the State Key Laboratory of Coastal and Offshore Engineering at DUT. For the wave surface elevation in front of the wall and the wave forces on the wall at the moment when the wave surface at the wall surface goes down to the bottom of the wave trough, the calculated results coincide quite well with the experimental results. For the wave forces on the wall at the moment when the wave surface at the wall surface goes up to the top of the wave crest, the theoretical expressions are modified by the experimental results. For the convenience of practical use, calculations are made for the wave conditions which usually occur in enginering practice by use of the inves 相似文献
58.
Dr. K. -H. Nitsch Professor Dr. H. G. F. Winkler 《Contributions to Mineralogy and Petrology》1965,11(5):470-486
The equilibrium curves for the reactions:
- (a)4 orthozoisite + 1 quartz ? 5 anorthite + 1 grossularite + 2 H2O. 相似文献
59.
Nicholas Dodd 《中国海洋工程》1995,(2)
A nonlinear short-wave-averaged (surf beat) model is presented. The model is based on that of Roelvink (1993), but the numerical techniques used in the solution are based on the so-called weighted-averaged flux (WAF) method (eg Watson et al., 1992), with time-operator splitting used for the treatment of some of the source terms. This method allows a small number of computational points to be used, and is particularly efficient in modelling breaking long waves. The short-wave (or primary-wave) energy equation is solved using a more traditional Lax-Wendroff technique. Results of validation indicate that the model performs satisfactorily in most respects. 相似文献
60.
Li Yucheng He Ming Professor Dalian University of Technology Dalian Former master student Dalian University of Technology Dalian 《中国海洋工程》1994,(3)
-Based on the extended Morison Equation and model tests, the in-line forces on small square cylinders caused by waves (regular and irregular) and currents are analyzed in detail in this paper. The hydrodynamic coefficient CD and Cu related to KC number and the effect of direction of wave incidence are also given, which can be used in engineering practice. 相似文献