北太平洋海温与福建后汛期降水量的关系

本文应用奇异值分解方法给出同期和前期北太平洋海温与福建后汛期降水量相互匹配的空间典型分布型．分析结果表明，无论同期还是前期北太平洋海温与福建后汛期降水量之间均存在着清晰的遥相关．同期的赤道中东太平洋海温异常增高、日本以东洋面海温偏低，福建后汛期降水量偏少；另外，闽南地区后汛期降水量与同期NINO西海区和黑潮海区的海温成正相关关系．冬、春季出现厄尔尼诺现象时，次年福建尤其是闽南沿海后汛期降水量将偏少．     

基于经验模式分解的希尔伯特变换包络提取在机械故障诊断中的应用

本文采用经验模式分解 (EMD)提取信号的内在模函数 (IMF) ,并利用希尔伯特变换对所得IMF进行包络分析 ,提取机械故障特征。与直接对原信号进行包络分析相比较 ,该方法提取的机械故障特征更明显。数值模拟和对故障轴承振动信号分析表明了该方法的有效性。     

基于小波分解和ANFIS模型的赤道东太平洋海温集成预测

用小波分解和自适应神经模糊推理系统（ANFIS）相结合的方法，建立了赤道东太平洋海温的集成预报模型。该方法将复杂海温系统分解为相对简单的带能分量信号，然后建立分量信号的独立预报模型，最后对预报结果进行集成。试验结果表明，模型的保留预报对象主要特征的前提下，有效地降低了预报难度，集成预报准确率和预报时效传统方法有明显的改进和提高。     

An identification of wave propagation based on a single-point measurement

This study presents the identification of wave propagation using the information measured at a fixed point. The mathematical model used to carry out this research is an integral equation. The equation turned out to be a Fredholm integral equation of the first kind. The discretized matrix equation yielded an ill-conditioned system. To secure the stability of the system, Tikhonov regularization was applied to the ill-conditioned system. The analysis of the numerical computation proved that the regularization was able to retain the target spectrum.     

平均场分解初探

本文探讨了经验正交分解的基本原理,对两种平均场分解方法进行了比较,结果表明,利用距平场分解得到的特征向量作为基底分解平均场是可行的,文中给出的实例清楚地显示出几个主要影响因子的分布特征。 文中还讨论了几个与经验正交分解法的有效性有关的理论问题,并定义了两种关系矩阵,通过分析它们之间的关系,间接地导出了时空转换公式。     

海洋无脊椎动物消化酶的研究 Ⅰ、紫贻贝、日本蟳、滨螺消化酶的初步分析及其应用

本文用11种酶底物,测定了紫贻贝、日本蟳和滨螺消化系统的酶活性,并初步研究了这些消化酶的应用。实验表明:1.0％的紫贻贝消化酶在25℃、20分钟内可水解去除鲬鱼受精卵膜。1.0％的该消化酶加入等体0.5％的半纤维素酶和果胶酶,在30℃、60分钟内可制备出大量啤酒酵母原生质体。在同样条件下,1.5—2小时内,可去除大部分三角褐指藻的细胞壁。     

Reconstruction of incomplete oceanographic data sets using empirical orthogonal functions: application to the Adriatic Sea surface temperature

A method for the reconstruction of missing data based on an EOF decomposition has been applied to a large data set, a test case of Sea Surface Temperature satellite images of the Adriatic Sea. The EOF decomposition is realised with a Lanczos method, which allows optimising computational time for large matrices. The results show that the reconstruction method leads to accurate reconstructions as well as a low cpu time when dealing with realistic cases. The method has been tested with different amounts of missing data, artificially adding clouds ranging from 40% to 80% of data loss, and then compared to the same data set with no missing data. A comparison with in situ data has also been made. These validation studies show that results are robust, even when the amount of missing data is very high. The reconstruction of the data from the Adriatic Sea shows realistic features and a reliable temperature distribution. In addition, the method is compared to an Optimal Interpolation reconstruction. The results obtained with both methods are very similar. The main difference is the computational time, which is reduced nearly 30 times with the method presented here. Once the reconstruction has been performed, the EOF decomposition is analysed to show the method’s reliability, and a cold event on the Albanian coast is studied. The reconstructed data reflect the effect of wind on the Albanian coast, that led to a cold-water episode in this zone for a 6-day period.     

Reactions of alkoxy radicals under atmospheric conditions: The relative importance of decomposition versus reaction with O2

The reactions of alkoxy radicals determine to a large extent the products formed during the atmospheric degradations of emitted organic compounds. Experimental data concerning the decompositions, 1,5-H shift isomerizations and reactions with O₂ of several classes of alkoxy radicals are inconsistent with literature estimations of their absolute or relative rate constants. An alternative, although empirical, method for assessing the relative importance under atmospheric conditions of the reactions of alkoxy radicals with O₂ versus decomposition was derived. This estimation method utilizes the differences in the heats of reaction, (H)=(H_{decomposition}–H_{O 2 reaction}), between these two reactions pathways. For (H)[22–0.5(H_{O 2 reaction})], alkoxy radical decomposition dominates over the reaction with O₂ at room temperature and atmospheric pressure of air, while for (H)[25-0.5(H_{O 2 reaction})], the O₂ reaction dominates over decomposition (where the units of H are in kcal mol^–1). The utility and shortcomings of this approach are discussed. It is concluded that further studies concerning the reactions of alkoxy radicals are needed.     

Single point mooring system modal parameter identification based on empirical mode decomposition and time-varying autoregressive model

A method based on empirical mode decomposition (EMD) and time-varying autoregressive (TVAR) model is proposed here to identify the modal parameters of time-varying systems, such as the Floating Production Storage and Offloading (FPSO) single point mooring system. For the EMD–TVAR method, the original signal is decomposed into a finite number of ‘intrinsic mode functions’ (IMFs) by the EMD. Each IMF can be represented as a TVAR model. Then, the time-varying modal parameters i.e., instantaneous frequency (IF) and modal dumping, can be obtained by the basis functions expansion method. The proposed EMD–TVAR method has good results in two experiments compared with the Huang–Hilbert transformation and Short Time Fourier Transform method, and it has been used to analysis the modal parameters of FPSO single point mooring system successfully. The system's time-varying characteristic and its frequency distribution can be known from the modal analysis results.     

Application of a 2D harmonic polynomial cell (HPC) method to singular flows and lifting problems

Further developments and applications of the 2D harmonic polynomial cell (HPC) method proposed by Shao and Faltinsen [22] are presented. First, a local potential flow solution coupled with the HPC method and based on the domain decomposition strategy is proposed to cope with singular potential flow characteristics at sharp corners fully submerged in a fluid. The results are verified by comparing them with the analytical added mass of a double-wedge in infinite fluid. The effect of the singular potential flow is not dominant for added mass and damping, but the error is non-negligible when calculating mean wave loads using direct pressure integration. Then, the double-layer nodes technique is used to simulate a thin free shear layer shed from lifting bodies, across which the velocity potential is discontinuous. The results are verified by comparing them with analytical results for steady and unsteady lifting problems of a flat plate in infinite fluid. The latter includes the Wagner problem and the Theodorsen functions. Satisfactory agreement with other numerical results is documented for steady linear flow past a foil and beneath the free surface.