Mode shape identification using residues of measured offshore structure data

Compared to traditional mode shape identification methods such as eigensystem realization algorithm (ERA), this article proposes a mode shape identification method based on estimated residues of measured data and the theoretical relationship between the estimated residues and the mode shapes from the state space model is obtained by defining a coefficient matrix. A mass-spring model with five degrees of freedom (DOFs) is utilized to demonstrate the approach. The numerical results indicate that the estimated residues are the mode shapes of structures, but with a coefficient matrix to maintain consistency with the mode shapes from the ERA. Using MATLAB a complicated numerical jacket platform is built to further study the proposed method. The results show that mode shapes consistent with those from the ERA could be obtained by taking the defined coefficient matrix into account, which is also demonstrated by a physical beam model that was built at Ocean University of China.     

ENHANCING GROUND RESOLUTION OF TM6 BASED ON MULTI-VARIATE REGRESSION MODEL AND SEMI-VARIOGRAM FUNCTION

1　ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔＬａｎｄｓａｔＴＭｉｍａｇｅｓａｒｅｐｒｏｂａ ｂｌｙｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｒｅｍｏｔｅｓｅｎｓｉｎｇｉｍａｇｅｓｆｏｒｇｅｏ ｌｏｇｉｃａｌｐｕｒｐｏｓｅｓ(Ｃｈｅｎｅｔａｌ.,1 994) .Ｕｓｕａｌｌｙ ,ｔｈｅｒｅａｒｅ7ｄｉｆｆｅｒｅｎｔｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｓｐｅｃｔｒｕｍｂａｎｄｓｉｎＴＭｉｍ ａｇｅｓ,ａｍｏｎｇｗｈｉｃｈｔｈｒｅｅｂａｎｄｓｃｏｖｅｒｔｈｅｖｉｓｉｂｌｅｒａｎｇｅｏｆｔｈｅｅｌｅｃｔｒｏｍａｇｎｅｔ…     

CK—60型非开挖地下管线铺设机施工工艺

阐述了ＣＫ－６０非开挖地下管线铺设钻机先导孔钻进以及扩孔钻进工艺方法，论证钻进压力，给进速度及地层间的相互关系，确定正确的技术参数值。     

à trous小波分解在边缘检测中的应用

讨论了劋ｔｒｏｕｓ小波分解的原理及进行边缘检测的方法靡环樱校希砸8型枷窠辛耸匝?,并与经典的Sobel算子和Robert算子处理的结果进行了比较。结果表明 ,其性能在某些方面具有明显的优越性 ,并具有一定的抗噪声能力。同时 ,讨论了本文所述方法需要进一步改进的地方。     

非开挖地下管线成孔机的研制

非开挖地下管线成孔机由水平钻机、扩孔机及动力站３部分组成，采用机液混合传动方式，对样机进行了试验，效果较好。该机可用于塑性地层的小口径圆形及非圆形地下单管及管线集束的非开挖铺设施工。     

蒙药矿物药硫黄在酸性碱性及中性介质中溶出率的测定

采用燃烧碘量法测定了矿物药硫黄及其炮制品在酸性（人工胃液）、碱性和中性介质中的溶出率，结果表明炮制后的硫黄溶出率均高于天然硫黄的溶出率。文章提出的燃烧碘量法测定溶液中微量硫方法，最小检出限为６．５μｇ，方法的回收率为９７％～９９％，ＲＳＤ＜０．６％。     

顾及地形断裂线的LiDAR点云滤波方法研究

针对山区LiDAR点云的特点,对TIN滤波算法的三个重要环节进行了改进:1利用一种简单、快速的随机化格网搜索算法来获取更多的精确初始地面点;2提出一种地形预测角的判断准则来提高地形断裂线附近区域的滤波精度;3对每个激光脚点设置加密优先级,并在滤波过程中动态调整优先级大小,优先级高的激光脚点先进行判断,加密优先级的引入提高了TIN滤波算法对地形的适应性。最后,采用两块分布有大量地形断裂线的山区数据进行实验验证,并与传统的TIN滤波算法进行比较分析,结果表明,改进后的TIN滤波算法可以有效地保留山区的地形断裂线特征,提高了算法在山区的滤波精度。     

Effect of salt types on salt precipitation and water transport in saline sandy soil

Salt precipitation on the surface of porous media significantly affects water transport processes. Most studies on salt precipitation mainly focused on single salts, but in nature, salt precipitation usually occurs as mixtures. Consequently, information on the crystallization of salt mixtures and its effect on water transport remains scarce. This study investigated the precipitation of mixtures (the mass ratios of NaCl:Na₂SO₄ were 3:7, 5:5, and 7:3, respectively) of NaCl (typical efflorescence) and Na₂SO₄ (typical subflorescence) in the initially saturated sandy soil columns and its effect on evaporation and compared it with the cases of the two salts individually. The results showed that salt mixtures exhibited a mixed pattern of crystals including both efflorescence and subflorescence, and the efflorescence showed granular aggregation, unlike the mono-salts. The crystallization coverage of the salt mixtures was smaller than that of NaCl mono-salt; high (7:3) and low (5:5 and 3:7) proportions of NaCl led to larger and smaller crystallization coverage than that of Na₂SO₄ mono-salt, respectively. While the salt mixtures had less crystallization coverage than the mono-salts, they showed lower evaporation because the salt mixtures formed a denser crystallization structure of efflorescence-subflorescence-soil layer, this crystallization structure exhibited greater inhibition of water vapour diffusion, thus reducing evaporation. In addition, the crystallization of the salt mixtures with higher NaCl proportion afforded greater resistance of evaporation. The mixed crystallization pattern formed by the salt mixtures significantly enhances the crystallization resistance to evaporation.     

青藏高原多年冻土区活动层水热特性研究进展

青藏高原多年冻土作为我国冰冻圈的重要组成部分, 其水热状况是影响寒区生态环境、 陆气间水热交换、 气候变化以及地面路基建设等的重要因素。为增进对青藏高原多年冻土区活动层水热特性的认识, 对影响活动层水热特性的主要因素以及主要研究方法做进一步梳理, 并指出了当前研究中的不足。研究认为, 气象条件、 植被覆盖度、 土壤性质、 积雪等是影响多年冻土区活动层水热过程的主要因素, 目前针对活动层水热特性的研究主要通过对站点实测资料分析和模型模拟等方式展开。未来工作的重点应放在改进适合于高寒山区的陆面模式以及增强水热动态过程与气候系统的相互作用上。