排序方式: 共有46条查询结果,搜索用时 429 毫秒
11.
F. G. ONeill 《Ocean Engineering》2003,30(16):2053-2063
A theoretical investigation is carried out of the mesh size measurement of an idealized fishing netting mesh. It is assumed that the bending moment of the netting twine is proportional to curvature and that there is no twine extension and no cross-sectional deformation of the twine. The corresponding momentum and force balance equations are analyzed. The measurement method our analysis most approximates is that of the ICES gauge. The effect on mesh measurement of twine bending stiffness, frictional resistance, boundary slope, gauge force and gauge thickness are all examined. 相似文献
12.
13.
14.
P. Rai F. L. Imperial President 《Fragblast: International Journal for Blasting and Fragmentation》2005,9(4):219-232
The present research paper is a case study in a limestone quarry in the Philippines where major problems in terms of improper fragmentation (large boulder count and poor pay-loader performance), poor wall control, and poor heave characteristics of the muck pile were witnessed. The paper highlights the role of modifying the firing pattern and, also, the application of stemming plug without incorporating any change in the stemming column length due to which incremental expansion in the mesh area could be implemented to determine the optimum mesh area. The optimum mesh area, due to the said changes in the blast design, was considerably larger in comparison to the pre-existing mesh area. The study has also highlighted the importance of indirect methods for characterizing and precisely adjudging the blast performance. 相似文献
15.
文中利用动态数据链表的技术 ,为等高线数据重新设计了一种数据结构和检索方法 ,从而实现了内存中有效地操作等高线数据 ,使基于矢量等高线数据的 DEM建模速度得到了显著的提高 相似文献
16.
不同结构网囊特性的初步研究 总被引:1,自引:0,他引:1
杨吝 《广东海洋大学学报》1998,(2)
为了测定不同拖网网囊结构对网囊的几何形状、同目张开、网目形状和拖网阻力的影响,设计和制作了4种网囊,一种是传统的菱形同目(DM)网囊,另三种是新型网囊:方形同目(SM)网囊,菱、方形网目混合二片式(DSM2)网囊和菱、方形同目混合四片式(DSM4)网囊。于1996年9月11~12日在中山大学试验水槽进行了同模试验,结果表明:1)各网囊阻力相差不大,且随拖速和渔获的增加而增大。2)新型网囊的几何形状和同目的张开及其形状均优于传统菱形网目网囊。3)空网时,各种网囊均呈圆筒状。当网囊中有了渔获后,传统菱形同目网囊的端部变为球状,除了球状部分的网目有较大张开外,其余同目张开很小,网囊使用直径也小,而新型网囊始终保持筒状,且网目充分张开,网囊使用直径也大。4)新型例翼的几何形状及使用直径和网目的张开及形状几乎不受拖速大小、有无渔获和渔获多少的影响。 相似文献
17.
A finite element model of the Irish and Celtic Sea regions with a range of grid resolutions is used to examine the influence of resolution upon the higher harmonics of the tide in the region. Comparisons are also made with published results from finite difference models of the area, and observations. Calculations using fine near-shore elements with non-zero water depths in coastal regions were found to be more accurate and less time consuming than those using a zero coastal water depth. A detailed examination of the spatial variability of the higher harmonics in near-shore regions of the eastern Irish Sea particularly the Solway and Morecambe Bay showed significant small-scale variability. This together with the variation in higher harmonics in the eastern Irish Sea and adjacent estuaries, clearly shows the need for an unstructured grid model of the region that can include the estuaries. To match the high resolution of the model in near-shore regions accurate high-resolution topography is required. 相似文献
18.
四面体模型由于其灵活性,在地学及GIS领域有着广泛的应用.本文讨论了空间离散点四面体剖分中采用的逐点插入算法,介绍了此算法数据结构的定义,算法实现中所需要的3D向量类的构造,阐述了点位的快速搜索的方法.应用Visual C++6.0这一集成开发环境(IDE),结合微软的DireetX 9.0 for C/C++SDK,... 相似文献
19.
本文阐发了波浪状镶嵌构造学说的要义。在对学说的创立和发展做了简要的回顾之后,着重阐述了学说发展的现状,并对其今后发展的广阔前景及有待解决的问题也进行了概略的讨论。 相似文献
20.
为了科学地确定南海区拖网网囊的结构和适宜网目尺寸 ,于 2 0 0 0年 1 1月 2 5日~ 1 2月 2 0日在南海北部珠江口以外海域水深 36~ 70m拖网渔场 ,对 4种不同网目尺寸的方目网囊进行了网囊套网式捕鱼选择性试验 ,获得了蓝圆鱼参(Decapterusmaruadsi)、多齿蛇鲻 (Sauridatumbil)、条尾绯鲤 (Upeneusbensa si)等 3种主要鱼种的选择性曲线。试验结果表明 :4种方目网囊的数量平均逃逸率均高于重量平均逃逸率 ;网囊渔获的优势体长总是大于套网渔获的优势体长 ;蓝 鱼参、多齿蛇鲻、条尾绯鲤之类的圆体鱼类比扁体鱼类更易于逃出方目网囊。 相似文献