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Henry Ker–Chang Chang Chung–Yu Liou 《International journal of geographical information science》2013,27(2):205-218
ABSTRACT Although the linear quadtree is popular in both image processing and GIS, most linear quadtree coding methods need in representation a bit length that is proportional to the resolution of images; the proportionality factor is replaced with a constant bit length that induces a more compact linear quadtree. We propose a linear quadtree coding scheme named constant key length quadtree coding (CKQC) that has advantages of easy implementation and decreased memory requirements. The proposed CKQC scheme is developed on the bases of node classification, order of traversal with breadth first and the Morton sequence. The major characteristic is to apply a constant bit length to construct quaternary codes. The bit length of each quaternary code is constant, either four or eight bits, no matter what the resolution of a raster image. In terms of memory space required and duration complexities, the overall performance is analyzed and compared with other methods to demonstrate the superiority of the proposed CKQC scheme. Several experimental results validate the applicability of the proposed scheme. 相似文献
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T. Marsset B. Marsset S. Ker Y. Thomas Y. Le Gall 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(4):628-637
We present the technological development and initial results from the deep-towed seismic acquisition device SYstème SIsmique Fond de mer (SYSIF) recently built by Ifremer. The two configurations of the SYSIF are presented (high resolution (HR): 250–1000 Hz and very high resolution (VHR): 650–2000 Hz), and results are compared to conventional seismic acquisition systems such as multi-channel HR or single-channel VHR (hull-mounted sub-bottom profiler). The ability of SYSIF to achieve higher resolution imagery is due to both the technology employed (low-frequency Janus–Helmoltz piezoelectric transducer) and the deep-towed operating mode (reduction in the Fresnel zone). Sea trials have been conducted in various geological environments and in water depths as deep as 2500 m. The new technique improved imaging of deep seafloor and sub-surface features such as pockmarks, carbonate mounds, sub-marine slides and sub-surface faulting. SYSIF, therefore, is a well-suited tool to investigate deep water geological features, especially those related to geohazard for scientific and industrial purposes. 相似文献
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An analytical solution has been developed in this paper to quantify the flow field and the surge motion of a porous tension leg platform with an impermeable top layer induced by linear waves. The porous layer of the TLP is considered to be anisotropic but homogeneous. The nonlinear form drag in the porous layer is replaced by a linear drag according to Lorentz’s hypothesis of equivalent work. The convergence of the series solution is verified. The dependence of the flow field, the surge motion of the platform, and its resonant frequency on wave and structure properties has been studied. 相似文献
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Chien-Yuan Tseng Huai-Jen Yang Houng-Yi Yang Dunyi Liu Cailai Wu Chiu-Kuang Cheng Cheng-Hong Chen Choon-Muar Ker 《Gondwana Research》2009,16(2):285
Adakitic intrusive rocks of 430–450 Ma were discovered in the North Qilian orogenic belt, the western section of the Central Orogenic System (COS) in China. These adakitic rocks were lower crust melts rather than slab melts as indicated by their crustal Ce/Pb, Nb/U, Ti/Eu, and Nd/Sm ratios and radiogenically enriched (87Sr/86Sr)i of 0.7053–0.7066 and εNd(t) of − 0.9 to − 1.7. While they are all characterized by low Yb (< 1.1 ppm) and Y (< 11.5 ppm) abundances with high Sr/Y (> 65) and (La/Yb)N (> 13.7) ratios, these adakitic rocks are classified into the low-MgO–Ni–Cr and high-MgO–Ni–Cr groups. The low-MgO samples were derived from partial melting of thickened lower crust, whereas the high-MgO samples were melts from delaminated lower crust, which subsequently interacted with mantle peridotite upon ascent. Adakitic rocks from the adjacent North Qinling orogenic belt also originated from thickened lower crust at 430 Ma. In addition, the North Qilian and North Qinling orogenic belts both consist of lithological assemblages varying from subduction-accretionary complexes at south to central arc assemblages, which include adakitic rocks, then to backarc phases at north. Such a sequence reflects northward subduction of the Qilian and Qinling oceans. In these two orogenic belts, the occurrence of adakitic rocks of common origin and ages together with the similarities in tectonic configurations and lithological assemblages are considered to be the evidence for the continuity between eastern Qilian and western Qinling, forming a > 1000 km Early Paleozoic orogenic belt. In such a tectonic configuration, the Qilian and Qinling oceans that subducted from south possibly represent parts of the large “Proto-Tethyan Ocean”. This inference is supported by the coexistence of Early Paleozoic coral and trilobite specimens from Asia, America and Australia in the North Qilian orogenic belt. Post-400 Ma volcanic rocks occur in the North Qinling orogenic belt but are absent in the North Qilian orogenic belt, indicating that these two orogenic belts underwent distinct evolution history after the closure of the Proto-Tethyan Ocean ( 420 Ma). 相似文献
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Keh‐Chyuan Tsai Po‐Chien Hsiao Kung‐Juin Wang Yuan‐Tao Weng Min‐Lang Lin Ker‐Chun Lin Chui‐Hsin Chen Jiun‐Wei Lai Sheng‐Lin Lin 《地震工程与结构动力学》2008,37(7):1081-1098
A series of pseudo‐dynamic tests (PDTs) of a full‐scale 3‐story 3‐bay buckling‐restrained braced frame (BRBF) using concrete‐filled tube columns was tested in the Taiwan National Center for Research on Earthquake Engineering using networked PDT techniques in October 2003. During the tests, real‐time experimental responses and video were webcasted to Internet viewers. The input ground motions adopted for the PDTs were chosen from the 1999 Chi‐Chi and the 1989 Loma Prieta earthquakes and scaled to represent three seismic hazard levels. This paper is in two parts, focusing on the investigations of the overall structure and the local members. This paper constitutes Part I and discusses the design, analytical investigations, and key experimental results of the specimen frame, such as the buckling of the brace‐to‐gusset joints. Part II of the paper, the companion paper, describes the gusset stiffening schemes and detailed experimental behavior of the BRBs and their connections. Experimental peak inter‐story drifts of 0.019 and 0.023 radians, prescribed for the design basis and the maximum credible earthquakes, respectively, are within the target design limits of 0.020 and 0.025 radians. These tests confirmed that the PISA3D and OpenSees nonlinear structural analysis computer programs can simulate the experimental peak shears and floor displacements well. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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