Prediction of Non-Cavitation Propeller Noise in Time Domain     

叶金铭  熊鹰  肖昌润  毕毅 《中国海洋工程》2011,(3)

The blade frequency noise of non-cavitation propeller in a uniform flow is analyzed in time domain. The unsteady loading (dipole source) on the blade surface is calculated by a potential-based surface panel method. Then the time- dependent pressure data is used as the input for Ffowcs Williams-Hawkings formulation to predict the acoustics pressure. The integration of noise source is performed over the true blade surface rather than the nothickness blade surface, and the effect of hub can be considered. The ...  相似文献   

孟州市府大楼整体搬迁岩土工程实录     

程礼来  段宗贵  宋永锟 《河南国土资源》1997,(3)

孟州市政府办公大楼整体搬迁的场地工程地质勘察，分部进行，即划分成搬迁路径和永久性地基两个单元。既做独立分析，又进行整体评价；既提供搬迁所需岩土工程指标，又为施工提出一些切合实际的建议。准确可靠的工程地质勘察资料，促成了大楼的整体迁移和永久定位。  相似文献   

Growth of chloritoid and garnet along a nearly isothermal burial path to 70 km depth: an example from the Bughea Metamorphic Complex,Leaota Massif,South Carpathians     

Negulescu  Elena  Săbău  Gavril  Massonne  Hans-Joachim 《Mineralogy and Petrology》2018,112(4):535-553

Mineralogy and Petrology - Chloritoid-bearing micaschist occurs in the matrix of a subduction mélange (Bughea Complex) of the Leaota Massif (South Carpathians) containing blocks of...  相似文献   

Snap Tension in Mooring Lines of Deepwater Platform     

张素侠  唐友刚  刘海笑 《中国海洋工程》2009,23(3):415-428

Based on the theory of impact dynamics, the motion equations for a mooring line-floating body system before and after impact loading are established with consideration of the viscoelastic property of mooring lines. The factors that influence the taut-slack conditions of a mooring system are analyzed through classifying the taut-slack regions, which are defined by non-dimensional ratios of displacement, frequency, and damping of the system. The mooring system of Jip spar platform is analyzed, and the snap te...  相似文献   

Analysis on Buckling Performance of Submarine Pipelines During Deepwater Pipe-Laying Operation     

袁林  龚顺风  金伟良  李志刚  赵冬岩 《中国海洋工程》2009,23(2):303-316

Pipes inevitably encounter high ambient pressure and bending moment during the deepwater pipe-laying process,which can lead to elliptical buckling and even deterioration failure.For the safety of pipe-laying operation,available formalas for the pipe stability are established on the basis of the assumption of uniform deformation along the tube length and symmetrical buckling.This method can predict the nonlinear rcsponse of elliptical collapse of steel circular tubes for different ratios of diameter to thickness (D/t) under pure bending or combined bending and external pressure.In these formulas,the strain-displacement relationship is deduced from the nonlinear ring theory,and the Ramberg-Osgood constitutive model is applied to simulate the inelastic material behavior.Meanwhile,the principle of virtual work is adopted to derive the equilibrium equations.A set of equations is solved by the Newton-Raphson method,and the iterative scheme contains nested iteration for the constitutive relation.In order to check the effectiveness of this theoretical method,illustrative examples are presented in this paper.Besides,the numerical simulation is carried out by use of ANSYS.A comparison of the results shows that the theoretical method can provide reasonable prediction for engineering practice.  相似文献   

Distribution of Time-Averaged Suspended Sediment Concentration Due to Waves     

严冰  张庆河 《中国海洋工程》2009,23(1)

According to the mechanism of sediment suspension under waves,namely,the main reason of sediment suspension changes from the turbulent mixing in the bottom boundary layer to the periodic motion of the water particle near the free water surface,a three-hyer model d sediment concentration distribution due to waves is presented along the whole water depth based on the concept of the finite mixing |ength.The determination of the parameters in the model is discussed and an empirical formula is suggested.Comparisons between the calculated results and the measurements indicate that the resuits of the model agree well with the data from both the large and small scale flume experiments.  相似文献   

Non-Linear Response of Tethers Subjected to Parametric Excitation in Submerged Floating Tunnels   总被引：1，自引：0，他引：1  

孙胜男  陈健云  李静 《中国海洋工程》2009,23(1)

For the study of the non-linear response of inclined tethers subjected to parametric excitation in submerged floating tunnels,a theoretical model for coupled tube-tether vibration is developed.Upon the assumption that the static equilibrium position of the tether is a quadratic parabola,the governing differential equations of the tether motion are derived by use of the Hamilton principle.An approximate numerical solution is obtained by use of Galerkin method and Runge-kutta method.The results show that,when the static equilibrimn position of the tether is assumed to be a quadratic parabola,the tether sag effect on its vibration may be reflected;the tether sag results in the asymmetry of tether vibration amplitude;for the reduction of the tether amplitude,the buoyant unit weight of the tether should approach to zero as far as possible during the design.  相似文献   

Dynamic Modeling and Investigation of Maneuver Characteristics of A Deep-Sea Manned Submarine Vehicle     

谢俊元  须文波  张华  徐鹏飞  崔维成 《中国海洋工程》2009,23(3):505-516

A deep-sea Manned Submarine Vehicle (MSV) is usually required to move at a low forward speed and a low rotational speed when it executes investigation tasks. In this condition, the motion is in large drift angles, and the maneuverability hydrodynamic forces cannot be expressed properly in the conventional mathematical model of submersible motion. In this paper, firstly, a general equation of MSV with six-freedom motion is presented, and the numerical simulation of descent/ascent motion and helix motion is c...  相似文献   

Macro-and Micro-Properties of Two Natural Marine Clays in China   总被引：2，自引：0，他引：2  

蒋明镜  彭立才  朱合华  林奕禧  黄良机 《中国海洋工程》2009,23(2):329-344

In this paper,macro- and micro- properties of natural marine clay in two different and representative regions of China are investigated in detail.In addition to in-situ tests,soil samples are collected by use of Shelby tubes for laboratory examination in Shanghai and Zhuhai respectively,two coastal cities in China.In the laboratory tests,macro-properties such as consolidation characteristics and undrained shear strength are measured.Moreover,X-ray diffraction test,scanning electron microscope test,and mercury intrusion test are carried out for the investigation of their micro-properties including clay minerals and microstructure.The study shows that:(1) both clays are Holocene series formations,classified as either normal or underconsolidated soils.The initial gradient of the stress-strain curves shows their increase with increasing consolidation pressure;however,the Shanghai and the Zhuhai clays are both structural soils with the latter shown to be more structured than the former.As a result,the Zhuhai clay shows strain softening behavior at low confining pressures,but strain hardening at high pressures.In contrast,the Shanghai clay mainly manifests strain-hardening.(2) An activity ranges from 0.75 to 1.30 for the Shanghai marine clay and from 0.5 to 0.85 for the Zhuhai marine clay.The main clay mineral is illite in the Shanghai clay and kaolinite in the Zhuhai clay.The Zhuhai clay is mainly characterized by a flocculated structure,while the typical Shanghai clay shows a dispersed structure.The porous structure of the Shanghai clay is characterized mainly by large and medium-sized pores,while the Zhuhai clay porous structure is mainly featreed by small and medium-sized pores.The differences in their macro- and micro- properties can he attributed to different sedimentation environments.  相似文献   

黔北务正道地区铝土矿形成环境的古盐度识别     

崔滔  焦养泉  杜远生  余文超  计波  雷志远  翁申富  金中国  和秀林 《地质科技情报》2013,(1):46-51

通过对黔北务川—正安—道真铝土矿中的B、Sr、Ba、V、Zr及其生物标志化合物的分析,对务正道地区铝土矿沉积环境的古盐度进行了研究。结果表明,铝土矿的沉积受到海洋环境的影响,主要形成于半咸水-淡水环境中。沉积环境为半封闭海湾,海侵使成矿区低盐度水体变为半咸水或咸水,随后陆地淡水输入等淡化作用将半咸水或咸水淡化,淡化的程度与范围取决于淡化时间的长短,经淡化后的水体在下一轮海侵中再次被咸化,水体的古盐度随海平面升降在淡水-咸水之间循环。  相似文献