双层局部开孔板沉箱对波浪反射的理论研究

提出了一种用于研究由双层开孔板和一个不透水后板的开孔结构对斜向波反射率的理论分析方法。整个流域被分成三个子域，在每个子域内应用特征函数展开法以得到该域内包含未知展开系数的势函数的表达式，在速度势的展开中，考虑了非传播模态波浪的影响。通过匹配开孔板处的边界条件可以求解待定的展开系数，继而求解双层开孔板防波堤结构对斜向波的反射率。数值计算结果与试验结果进行了比较，符合较好。并进一步讨论了几个重要因素对反射系数的影响。     

协方差阵二次型容许估计的一个必要条件

研究协方差阵Σ的二次型容许估计问题。设 y1,y2 ,… ,yniid,n≥ 2 ,y1与 p维正态分布N (β,Σ )有相同的前四阶矩。其中β =(β1,β2 ,… ,βp)′∈ Rp与Σ =(σij) p× p >0均未知。记 y =△ (y1,y2 ,… ,yn)′。在二次损失 L (d ,Σ ) =tr(d -Σ) 2下给出Σ的二次型估计 a S2 + nby-y-′是容许估计的必要条件为 :(n - 1) a + b + 2 max(a,b)≤ 1。此必要条件比张立振等协方差阵的二次型容许估计中的必要条件有了明显的加强     

Change of multifractal thermal characteristics in the western Philippine sea upper layer during internal wave-soliton propagation

The upper layer (above 140 m depth) temperature in the western Philippine Sea near Taiwan was sampled using a coastal monitoring buoy (CMB) with 15 attached thermistors during July 28–August 7, 2005. The data were collected every 10 min at 1, 3, 5, 10, 15, and 20 m using the CMB sensors, and every 15 sec at 15 different depths between 25 m and 140 m. Internal waves and solitons were identified from the time-depth plot of the temperature field. Without the internal waves and solitons, the power spectra, structure functions, and singular measures (representing the intermittency) of temperature field satisfy the power law with multi-scale characteristics at all depths. The internal waves do not change the basic characteristics of the multifractal structure. However, the internal solitons change the power exponent of the power spectra drastically, especially in the low wave number domain; they also break down the power law of the structure function and increase the intermittency parameter. The physical mechanisms causing these different effects need to be explored further.     

浅水波长计算问题

浅水波周期保持常值,而波长缩减时其计算需进行迭代。提出了两个精度较高的经验公式供计算应用。水深波长比差值ΔLD0的变化规律反映出浅水波长缩减为一复杂过程,并与波能密度加大相关。LD0≤0.14时,特别是LD0=0.056前后,其特征会更加显著,由此可探讨波长变化的内在机理。     

A proposed directional function and wind-wave directional spectrum

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关于“包装产品的计量标准型一次抽检方案”的确定

本文给出了“包装产品的计量标准型一次抽检方案”,并通过一个实例说明本方案比一般《计量标准型一次抽检方案》更为优越。     

Fully nonlinear numerical wave tank (NWT) simulations and wave run-up prediction around 3-D structures

A finite-difference scheme and a modified marker-and-cell (MAC) algorithm have been developed to investigate the interactions of fully nonlinear waves with two- or three-dimensional structures of arbitrary shape. The Navier–Stokes (NS) and continuity equations are solved in the computational domain and the boundary values are updated at each time step by the finite-difference time-marching scheme in the framework of a rectangular coordinate system. The fully nonlinear kinematic free-surface condition is implemented by the marker-density function (MDF) technique developed for two fluid layers.To demonstrate the capability and accuracy of the present method, the numerical simulation of backstep flows with free-surface, and the numerical tests of the MDF technique with limit functions are conducted. The 3D program was then applied to nonlinear wave interactions with conical gravity platforms of circular and octagonal cross-sections. The numerical prediction of maximum wave run-up on arctic structures is compared with the prediction of the Shore Protection Manual (SPM) method and those of linear and second-order diffraction analyses based on potential theory and boundary element method (BEM). Through this comparison, the effects of non-linearity and viscosity on wave loading and run-up are discussed.     

Algorithm for HF radar vector current measurements

A new algorithm is proposed, called the stream function method (SFM) for producing vector current maps from radial data measured by dual-site high frequency surface wave radar (HFSWR). In SFM, a scalar stream function is constructed under some oceanographic assumptions. The function describes the two-dimensional (2-D) ocean surface water motion and is used to obtain the distribution of vector currents. The performance of SFM is evaluated using simulated radial data, which demonstrates that SFM has advantages over typical vectorial combination methods (VCM) both in error acceptance and robustness, and excels another method based on least-squares fitting (LSF) in recovering the complicated current models. Furthermore, SFM is capable of providing the total currents based on radials from single-site radar. We also test the assumptions of horizontal non-divergence in the simulation. The new algorithm is applied to the field experiment data of Wuhan University’s ocean state measuring and analyzing radar (OSMAR), collected in the coastal East China Sea during April 11–17, 2004. Quantitative comparisons are given between radar results by three current algorithms and in-situ current meter measurements. Preliminary analysis of the vertical current shear is given based on the current meter measurements.     

用样条函数计算结果研究冲绳海槽热源机制

对冲绳海槽１９８４－１９９０年的实测热流值，利用数字滤波方法计算，得到反映该区深部地壳热状态的区域热流值为８０－１６０ｍＷ／ｍ＾２，用Ｂ样条函数法对其作数值模拟，计算出海槽地温场模式，并以此研究冲绳海槽海底高热流的形成机制，得出冲绳海槽热流值的区域性变化与綦中地质构造格局呈正相关，高热流是该区现代构造活动所致，其明显特征是地壳减薄，地幔上拱等结论。