共查询到20条相似文献，搜索用时 31 毫秒
1.
在水深1.0米,具有平坦海底的区域作了时域分离简正波的模拟实验,得到了1、2、3号简正波。由分离出的简正波相对幅度计算了海底反射损失因子Q。所得实验数据与理论计算结果符合甚好。计算所得Q值与由底质采样所得Q值基本一致。 相似文献
2.
A new standardization method for glass electrodes is proposed for pH measurements on the NBS scale. An expression is obtained to evaluate the apparent activity coefficient of hydrogen ions as a function of salinity and temperature, from determinations obtained by Mehrbach et al., 1973 (Limnol. Oceanogr., 18: 897–907). This expression must be used to estimate systematic errors produced by variations of residual liquid-junction potential by estimating the apparent activity coefficient of hydrogen ions. In this way, values of pH obtained in oceanographical cruises can be standardized in order to determine and compare different parameters of the CO2 system.Some experiments to study the variation of pH with temperature are carried out to compare the different series of acid constants used at present. A simple and precise polynomial equation is also obtained to determine the variation of pH with temperature. 相似文献
3.
This paper deals with obtaining the governing equations of rolling motion of a ship with a flooded compartment. The equations of motion are obtained through the variational formulation in the form of Hamilton-Ostrogradskii equation by taking the ship, the fluid in the flooded compartment and the sea as a single mechanical system. Since no specification concerning ships or flooded compartments has been made, the obtained equations are applicable to any sea-going vessel. As an application, the equation of rolling motion of a ship with a prismatic flooded compartment is obtained by choosing a suitable velocity potential for the fluid motion in the compartment. 相似文献
4.
The elliptic mild slope equation is used to simulate linear wave propagation over variable seabed topography with mild slopes.The governing equation is discretized by the finite difference method.Ba-sed on the BI-CGSTAB technique.an attractive variant of BI-Conjugate Gradients(BI-CG)method,theobtained linear algebraic system of equations is solved.Numerical experiments show that the BI-CGSTABmethod is efficient for solving the elliptic mild slope equation.The results obtained by the BI-CGSTAB-Ba-sed method are much the same as those obtained by other authors with different solution methods,but theconvergence rate is much faster than that of other methods. 相似文献
5.
An edge wave is a kind of surface gravity wave basically travelling along a shoaling beach. Based on the periodic assumption in the longshore direction, a second order ordinary differential equation is obtained for numerical simulation of the cross-shore surface elevation. Given parameters at the shoreline, a cross-shore elevation profile is obtained through integration with fourth-order Runge-Kutta technique. For a compound slope, a longshore wavenumber is obtained by following a geometrical approach and solving a transcendental equation with an asymptotic method. Numerical results on uniform and compound sloping beaches with different wave periods, slope angles, modes and turning point positions are presented. Some special scenarios, which cannot be predicted by analytical models are also discussed. 相似文献
6.
The bifurcation behavior of an articulated loading platform subjected to harmonic excitation is investigated by the incremental harmonic balance (IHB) method. The platform is modeled as a single-degree-of-freedom (SDOF) non-linear system with piecewise non-linear restoring force characteristics. The elements of the Jacobian matrix and the residue vector arising in the IHB formulations are derived in closed form. The path-following procedure using the arc length continuation method is used to trace the response curves and bifurcation diagrams. The periodic solutions and the subharmonic solutions obtained by the IHB method compare very well with the numerically integrated solutions. The bifurcation points also compare well with the numerically obtained results. The system exhibits chaotic motion through a sequence of period doubling bifurcations. Isolated period 3 solutions are also present. The Lyapunov exponents are computed and the initial condition map corresponding to coexistent attractors are obtained by the interpolated cell mapping (ICM) method. 相似文献
7.
Song Yupu Wang Jian Associate Professor Dept. of Civil Engineering Dalian University of Technology Dalian Lecturer Dept. of Civil Engineering Dalian University of Technology Dalian 《中国海洋工程》1992,(1)
A design method of reinforced concrete (R. C.) offshore platforms with nonlinear finite element analysis is proposed. According to the method, a computer program is developed. In this program nonlinear constitutive relationships and strength criteria of concrete and steel bars are included, and the progressive cracking and crushing of the concrete are taken into account. Based on the stress distribution obtained by the nonlinear finite element analysis, the amount of reinforcement in the control sections can be computed and adjusted automatically by the program to satisfy the requirement of the design. The amount of reinforcement required in the control sections, which are obtained with the nonlinear finite element analysis, is agreeable to that obtained in the experiment. This shows that the design method of R. C. offshore platform with the nonlinear finite element method proposed by the authors is reliable for practical use. 相似文献
8.
O. S. Ermakova I. A. Kapustin V. V. Papko 《Izvestiya Atmospheric and Oceanic Physics》2008,44(5):583-593
The dynamics of a layer of turbulence excited by a ribbed oscillating grate in homogeneous and stratified fluids is investigated experimentally. The time dependences of the thickness of the region encompassed by turbulence in a homogeneous fluid are obtained. On the basis of a semiempirical turbulence theory, it is shown that the time dependence of the coordinate of the turbulent-front position can be described by a power function. A satisfactory agreement between the experimental and theoretical dependences is obtained. Different regimes of turbulent-layer dynamics in a fluid with salinity stratification are investigated. The results of numerical calculations of turbulent-layer dynamics in a stratified fluid that satisfactorily agree with experimental data are presented. The data obtained can be used to estimate the efficiency of mixing within the oceanic depth. 相似文献
9.
Alim Yildiz 《Ocean Engineering》1983,10(6):387-402
This paper deals with stability investigations of forced nonlinear rolling motion of a ship with a flooded compartment. The mathematical stability analysis has been realized in the sense of Eventual Stability. Two stability regions have been constructed through two Lyapunov functions generated by using Variable Gradient Method and the method of Puri. Having obtained stability conditions for the governing equations of the motion, dissipativeness of the motion, and maximum rolling angles have been obtained by using a theorem given by Bibikov and Sanovskii (1971). 相似文献
10.
Weimin Huang Gill E. Wu S. Biyang Wen Zijie Yang Jiechang Hou 《Oceanic Engineering, IEEE Journal of》2004,29(4):1032-1037
The extraction of full wind vectors from data obtained by single-site (monostatic) high-frequency ground-wave radar (HFGWR) is an ongoing challenge because of the inherent directional ambiguities. Here, a new algorithm for resolving the ambiguity of wind direction from monostatic data is presented. The true wind direction is determined by minimizing the sum of the difference among three wind directions derived from three different radar look angles. The wind directions estimated by applying the algorithm to data obtained from the OSMAR2000 HFGWR situated at the Eastern China Sea are compared with values obtained from ship-borne instrumentation. The mean difference between the ground-truthed values and those obtained from the radar data is approximately 20/spl deg/. The distance limit for wind direction sensing using the OSMAR2000 is about 200 km, which is the range for which signal-to-noise ratios typically exceed about 23 dB in the relevant first-order portions of the backscatter spectra. 相似文献
11.
12.
The angle dependence of the roll damping moment is investigated by analysing experimentally obtained free roll decay records. Two ship models were used with and without bilge keels, also results with forward speed were obtained. The analysis indicate strong angle dependence and explains why the quadratic and cubic velocity dependent damping moments are successful in many cases. 相似文献
13.
By extending the linear frequency domain theory, a quasi-non-linear time-domain technique has been developed to investigate the large amplitude motions of catamarans in regular waves. The non-linearity of hydrodynamic forces included in this practical method comes from variations of a ship's submerged portion. These forces are obtained from a database generated by the linear frequency domain method at each time step. The coupled equations, heave and pitch, are solved in the time domain by using the Runge-Kutta method with proper initial values. In order to investigate the non-linear effects of large amplitude motions of the V-1 catamaran in the head-sea condition, numerical results obtained from the linear and non-linear strip methods have been compared with those obtained from a series of experiments carried out in the towing tank of the Hydrodynamics Laboratory at the University of Glasgow. Based on the comparative studies, the numerical results obtained from the time-domain program can provide better predictions for the large amplitude motions of catamarans than the linear frequency domain method. It is concluded that the non-linear effects are significant when the model speeds and wave amplitudes increase. The peak values of large amplitude motions around the resonance frequencies, as obtained from the non-linear time-domain predictions as well as from measurements, are smaller than those obtained from the linear theory. 相似文献
14.
从浓度定量分析探讨异丙醇作原油萃取剂的可行性 总被引：1，自引：0，他引：1
分别采用正己烷与异丙醇作为萃取剂获得不同浓度下的2组相同原油样品的萃取液,进行波长差为40nm的同步荧光光谱测量.通过插值拟合得到相应的两组相同原油样品的浓度三维荧光光谱图,并据此对相同原油样品萃取液的未知浓度进行计算,并与实际值比较,得出相应误差.文中通过对不同萃取剂中光谱谱形、峰位、荧光强度以及浓度计算的误差进行对比分析,得出采用异丙醇作为石油定量荧光分析仪的萃取剂比用正己烷更具优势,从而在定量分析的基础上论证了采用异丙醇取代正己烷作为原油萃取剂的可行性. 相似文献
15.
Jebali J Banni M Gerbej H Boussetta H López-Barea J Alhama J 《Marine environmental research》2008,65(4):358-363
Metallothionein was quantified in sea bass Dicentrarchus labrax intraperitoneally (i.p.) injected with different Cu, Cd and Hg doses (50-250 microg kg(-1) wet wt) after 48 h exposure. A distinct peak with 16.8 min retention time was obtained by reversed-phase high performance liquid chromatography coupled to fluorescence detection (RP-HPLC-FD) with the three metals. Total metallothionein levels assayed in unheated liver extracts by RP-HPLC-FD were significantly higher (1.3-1.95-fold) than those obtained by the well-established spectrophotometric method. In the RP-HPLC-FD method, metallothionein increased linearly with Cu and Hg doses, being saturated beyond 100 mug kg(-1) Cd. Maximum induction was obtained at 100 microg kg(-1) Cd (5.3-fold), and 250 microg kg(-1) Cu or Hg (8- and 5.1-fold, respectively). At low doses no metallothionein induction was shown by the less sensitive spectrophotometric assay. 相似文献
16.
A new analysis of nonlinear rolling carried out by the multiscale perturbation method is herewith presented. The behaviour of a ship in a regular beam sea is considered and approximate analytical solutions in three nonlinear resonance regions are obtained. These concern the transient and the steady state roll oscillations. The latter fits in well with a previous one obtained through the averaging method and with the results of the numerical simulation.The obtained results appear to be particularly convenient due to their major mathematical simplicity. Moreover, they allow a simple estimation of the maximum roll amplitudes predictable for a given excitation intensity. 相似文献
17.
The drag and added mass coefficients of a truss leg of an ocean platform are obtained by using the forced-oscillation technique in a still water. Higher order forces and lift forces are also measured.The drag and inertia coefficients of the truss leg model are obtained by measuring the wave forces acting on it in regular deep waves. The moment lever of the wave force is compared with theoretical results. 相似文献
18.
刀额新对虾主要过敏原蛋白的肽指纹图谱鉴定与分析 总被引：1，自引：0，他引：1
以我国常见的刀额新对虾为研究对象,旨在获得其主要过敏原的氨基酸序列等基础数据,增加对虾类过敏原的认识和理解。分离和纯化了分子量为36 kD的虾主要过敏原蛋白,利用激光辅助解析/飞行时间质谱对其进行肽质量指纹图谱鉴定,并对鉴定的结果采用Mascot搜索引擎在NCBInr数据库上进行搜索。结果表明刀额新对虾主要过敏原蛋白与斑节对虾原肌球蛋白匹配分值最高为268,吻合肽段27条,序列覆盖率为65%;与其它无脊椎动物如腐食酪螨、衣鱼等的原肌球蛋白的序列覆盖率也很高,分别达到了51%和53%。这一结果不仅表明了刀额新对虾与其它甲壳类海产品过敏原存在着高度同源性,而且为其与甲壳类及其它无脊椎动物主要过敏原之间存在严重交叉反应的现象提供了理论依据。 相似文献
19.
尝试了多种方法分离中国明对虾(Fenneropenaeus chinensis)囊胚细胞和原肠胚细胞并进行了细胞培养.结果表明,解剖法适用于囊胚细胞,自行设计的压片法适用于原肠胚细胞.在培养起始阶段,通过降低血清浓度和缩小培养体系可使中国明对虾囊胚细胞和原肠胚细胞迅速贴壁并铺展,囊胚细胞铺展后有明显的生长晕,中后期原肠胚细胞较易达到半汇聚状态.值得注意的是,中国明对虾囊胚细胞在不同培养液中培养可发生形态上的分化.本实验方法有望用于对虾细胞分化机理和对虾细胞建系的研究. 相似文献
20.
三维I型超长管线阴极保护的数值模拟 总被引：1，自引：1，他引：1
研究超长管线阴极保护设计问题的数学模型和数值模拟，并将介质电阻、金属面电阻及金属自身电阻作了系统处理。通过数值试验与实验结果的对比，肯定了所提出的数学模型及所用边界元法在处理此类问题时的合理性及有效性。 相似文献