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1.
壳聚糖特性粘度的快速测定   总被引:4,自引:0,他引:4  
对比不同生产厂家、不同分子量 (或粘度 )、不同脱乙酰度的壳聚糖产品在 2种不同测定条件 (30℃ ,0 .1mol· L-1CH3 COONa- 0 .2 mol· L-1CH3 COOH为溶剂 ;2 5℃ ,0 .2 mol· L-1Na Cl-0 .1mol· L-1CH3 COOH为溶剂 )下利用常规外推法和常用一点法经验公式所得的壳聚糖的特性粘度值表明 :一点法经验公式计算所得的壳聚糖的特性粘度值与用常规外推法所得的特性粘度值间的偏差最小 ,适合于快速测定壳聚糖特性粘度 ,进而可求得其粘均分子量  相似文献   
2.
天然气水合物的测井识别和评价   总被引:8,自引:0,他引:8  
地球物理测井作为传统的资源评价方法,在天然气水合物勘探中是有效评价手段。从国内外对天然气水合物的研究现状出发,简要地总结了天然气水合物的地球物理特征,介绍了利用电阻率测井和声波速度测井识别含天然气水合物储集层的方法和对天然气水合物进行评价,对现有的测井评价模型进行了讨论,指出了对天然气水合物储集层的地球物理测井评价模型还有待于进一步探讨。  相似文献   
3.
合成孔径雷达影像几何处理方法对比实验研究   总被引:1,自引:0,他引:1  
合成孔径雷达(SAR)由于其全天候、全天时的工作能力,成为近几年来摄影测量与遥感领域的研究热点。概述了合成孔径雷达影像的三种几何处理方法:多项式法、多项式正射纠正法及距离-多普勒方法,对以上三种方法的算法进行了描述;并基于C 程序进行了计算机实现。利用ERS-2数据和RADARSAT数据进行了实验,并对实验结果进行了比较,结果表明:多项式正射纠正方法和距离-多普勒方法纠图精度较高,且纠图精度相差不大;而多项式法在山区纠图精度相对较差。  相似文献   
4.
水下拖曳系统运动姿态仿真研究   总被引:5,自引:2,他引:3  
冯甦  朱克强 《海洋工程》2005,23(4):56-63
采用凝集参数法建立了水下拖曳系统的三维离散模型,该模型由一系列的质量点和不计重量的弹簧组成.采用数学模型编程对NCEL浮球实验和四个典型拖曳系统进行了仿真计算.计算结果表明此数学模型具有一定的理论意义和工程实用价值.  相似文献   
5.
胶州湾现代沉积速率和沉积通量研究   总被引:16,自引:0,他引:16  
对胶州湾沉积岩心J39、J37和J94进行了210Pb的测定,绘制了岩心中210Pb的垂直分布图,岩心J37和J94的210Pb呈两段分布模式,岩心J39的210Pb呈三段分布模式。胶州湾西北部大沽河口外海域近百年来沉积速率为0 768cm/a,沉积通量为0 7716g/(cm2·a)。胶州湾中部沉积速率为0 64cm/a,沉积通量为0 65g/(cm2·a)。胶州湾口外J94站沉积速率为0 54cm/a,沉积通量为0 81g/(cm2·a)。结果表明,胶州湾海域210Pb活度与悬浮体含量密切相关,悬浮体含量高的区域,210Pb活度高;反之,悬浮体含量低的区域,210Pb活度低。根据210Pb的垂直分布、活度和沉积速率及悬浮体含量,结合历史资料,对胶州湾近百年来的沉积环境和物质扩散进行了探讨。  相似文献   
6.
The finite volume method (FVM) has many advantages in 2-D shallow water numerical simulation. In this study, the finite volume method is used with unstructured triangular grids to simulate the tidal currents. The Roe scheme is applied in the calculation of the intercell numerical flux, and the MUSCL method is introduced to improve its accuracy. The time integral is a two-step scheme of forecast and revision. For the verification of the present method, the Stoker's problem is calculated and the result is compared with the mathematically analytic solutions. The comparison indicates that the method is feasible. A sea area of a port is used as an example to test the method established here. The result shows that the present computational method is satisfactory, and it could be applied to the engineering fields.  相似文献   
7.
Development of A Fully Nonlinear Numerical Wave Tank   总被引:1,自引:1,他引:0  
A fully nonlinear numerical wave tank (NWT) based on the solution of the σ-transformed Navier-Stokes equation is developed in this study. The numerical wave is generated from the inflow boundary, where the surface elevation and/or velocity are specified by use of the analytical solution or the laboratory data. The Sommerfeld/Orlanski radiation condition in eonjunetion with an artificial damping zone is applied to reduce wave reflection from the outflow boundary. The whole numerical solution procedures are split into three steps, i.e., advection, diffusion and propagation, and a new method, the Lagrange-Euler Method, instead of the MAC or VOF method, is introduced to solve the free surface elevation at the new time step. Several typical wave cases, including solitary waves, regular waves and irregular waves, are simulated in the wave tank. The robustness and accuracy of the NWF are verified by the good agreement between the numerical results and the linear or nonlinear analytical solutions. This research will be further developed by study of wave-wave, wave-current, wave-structure or wave-jet interaction in the future.  相似文献   
8.
This paper presents a numerical analysis of lateral responses of a long slender marine structure under combined parametric and forcing excitations. In the development of the 3-D numerical program, a finite element method is implemented in the time domain using the Newmark constant acceleration method. Some example studies are performed for various water depths, environmental conditions and vessel motions. The relative amplitudes of combined excitations to a conventional forcing excitation are examined. The response amplitude of a combined excitation is much greater than that of a forcing excitation in the even number of instability regions of the Mathieu stability chart. The results demonstrate that a combined excitation needs to be considered for the accurate dynamic analysis of long slender marine structures subjected to a surface vessel motion.  相似文献   
9.
QI  Peng 《中国海洋工程》2002,16(2):201-210
A hybrid numerical method for the hydraulic modeling of a curtain-walled dissipater of reflected waves from breakwa-ters is presented. In this method, a zonal approach that combines a nonlinear weakly dispersive wave (Boussinesq-type equation) method and a Reynolds-Averaged Navier-Stokes (RANS) method is used. The Boussinesq-type equation is solved in the far field to describe wave transformation in shallow water. The RANS method is used in the near field to re-solve the turbulent boundary layer and vortex flows around the structure. Suitable matching conditions are enforced at the interface between the viscous and the Boussinesq region. The Coupled RANS and Boussinesq method successfully resolves the vortex characteristics of flow in the vicinity of the structure, while unexpected phenomena like wave re-reflection are effectively controlled by lengthening the Boussinesq region. Extensive results on hydraulic performance of a curtain-walled dissipater and the mechanism of dissipation of reflected waves  相似文献   
10.
Analysis of Wave Loads on A Semi-Submersible Platform   总被引:10,自引:0,他引:10  
QIAN  Kun 《中国海洋工程》2002,16(3):395-406
For the global and structural fatigue strength analysis of a semi-submersible platform, wave loads under design conditions are calculated by use of the three-dimensional boundary element method. Methods for calculating the forward-speed free-surface Green function are discussed and a computer program with this Green function is developed. According to the special rules, the wave loads under several typical design conditions of the platform are calculated. The maximum vertical bending moment, torsion moment and horizontal split force are determined from a series of contour maps of wave loads for the wave period of 5 to 18 seconds at a certain interval and the wave phase of 0°to 360°at a certain interval. The wave height is determined by the function of wave period with a given exceedance probability. The maximum wave loads under the combination of wave parameters are used as the input of hydrodynamic pressure in the three-dimensional finite element analysis process. The transfer functions of wave loads  相似文献   
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