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91.
A fundamental challenge in river analysis and modelling is the lack of readily available and reliable information on river bank geometry. Traditional survey methods are expensive and time consuming and often difficult to execute in many river systems because of hazardous terrain or lack of access. However, as high quality aerial and satellite imagery becomes available for more of the globe, it is increasingly possible to extract these bank locations directly from imagery. The most direct method of doing this involves manually designating edges based on visual criterion. This, however, is often prohibitively time consuming and labour intensive, and the quality is dependent on the individual doing the task. This paper describes a quick and fully automated method for locating water surface and river banks in high resolution aerial imagery without recourse to any multispectral information, by segmenting based on the local entropy of the image. This method is demonstrated on imagery of several rivers and its advantages and limitations are discussed. Published 2013. This article is a U.S. Government work and is in the public domain in the USA. 相似文献
92.
We study challenges raised by the order of Arabic verbs and their subjects in statistical machine translation (SMT). We show that the boundaries of post-verbal subjects (VS) are hard to detect accurately, even with a state-of-the-art Arabic dependency parser. In addition, VS constructions have highly ambiguous reordering patterns when translated to English, and these patterns are very different for matrix (main clause) VS and non-matrix (subordinate clause) VS. Based on this analysis, we propose a novel method for leveraging VS information in SMT: we reorder VS constructions into pre-verbal (SV) order for word alignment. Unlike previous approaches to source-side reordering, phrase extraction and decoding are performed using the original Arabic word order. This strategy significantly improves BLEU and TER scores, even on a strong large-scale baseline. Limiting reordering to matrix VS yields further improvements. 相似文献
93.
94.
炼制Fe杂质含量不同的6种Al-Zn-In阳极,采用恒电流方去评价了其电化学性能,并通过扫描电镜观察其溶解的微观形貌,探讨了Fe杂质含量对阳极电化学性能的影响规律与机制.结果表明,随着Fe杂质含量的升高,Al-Zn-In阳极的电流效率呈先增加后降低趋势,原因足少量的Fe可增加阳极的活化点,而过量的Fe则作为阴极相引发电偶腐蚀使得阳极呈局部腐蚀溶解. 相似文献
95.
96.
ZHENG Pei-nan Physical Oceanography Laboratory Ocean University of China Qingdao China Marine Environmental Ensuring of the Headquarters of General Staff Beijing China WU De-xing LIN Xiao-pei Physical Oceanography Laboratory 《水动力学研究与进展(B辑)》2009,21(2):212-218
The Taiwan Warm Current (TWC) and the Tsushima Warm Current (TSWC) flow northward over the shelf in the East China Sea (ECS), which some previous studies regard as a Taiwan-Tsushima Warm Current (TTWC) System. But the roles of the TWC and TSWC in the formation of the TTWC system have not been clarified. This article will show that the TSWC is more important in the TTWC system. Using a three-dimensional baroclinic model, we conducted several numerical experiments to reveal the dynamic relationship between the TWC and TSWC. The results show that the TWC has little effect on the TSWC, while the TSWC has a significant effect on the TWC. A source-sink driven mechanism along isobaths may be used to explain this phenomenon. The perennial northward flow through the Tsushima Strait pumps the response over the northern shelf in the ECS that gives rise to the TWC. Although the TSWC is located at the "downstream" region, it could induce about 0.5 Sv to TWC in annual mean values. 相似文献
97.
上海七○四研究所衡拓实业发展有限公司伺服阀部 《液压与气动》2010,(1)
第四章伺服比例阀的发展
1 伺服阀与比例阀简介
电液伺服阀是在二战期间由于飞行器等军事装备对控制系统快速性动态精度的更高要求而发展起来的,并在战后逐渐用于民用和工业设备.它是一种接受模拟量电控制信号,输出随电控信号大小和极性变化、且快速响应的模拟量流量和(或)压力的液压控制阀.根据其液压放大器的不同,主要分为喷嘴挡板式伺服阀和射流管式伺服阀[1].电液伺服阀具有体积小、功率放大率高、直线性好、响应速度快、运动平稳可靠、能适应模拟量和数字量调节等优点,在各种电液伺服系统中得到特别的重视. 相似文献
98.
DA Poncelet EJ Bellefroid PV Bastiaens MA Demoitié JC Marine H Pendeville Y Alami N Devos P Lecocq T Ogawa M Muller JA Martial 《Canadian Metallurgical Quarterly》1998,17(11):931-943
We previously identified the ZNF85 (HPF4) KRAB zinc finger gene, a member of the human ZNF91 family. Here, we show that the ZNF85 gene is highly expressed in normal adult testis, in seminomas, and in the NT2/D1 teratocarcinoma cell line. Immunocytochemical localization of a panel of beta-Gal/ZNF85 fusion proteins revealed that ZNF85 contains at least one nuclear localization signal located in the spacer region connecting the KRAB domain with the zinc finger repeats. Bacterially expressed ZNF85 zinc finger domain bound strongly and exclusively to DNA in vitro in a zinc-dependent manner. The KRAB(A) domain of the ZNF85 protein and of several other members of the ZNF91 family exhibited repressing activity when tested in Gal4 fusion protein assays. The repression was significantly enhanced by the addition of the KRAB (B) domain, whereas further addition of other conserved regions had no effect. The ZNF85 KRAB(A) and (B) domains in vitro bound several nuclear proteins that might constitute critical cofactors for repression. 相似文献
99.
WANGXiu-hong YUWei-dong LUOTi-qian 《水动力学研究与进展(B辑)》2004,16(5):533-536
The Arctic Oscillation (AO), though basically is a zonal symmetric phenomenon, also shows zonal asymmetric variation. The dynamics of this zonal variation is considered here from the point of view of the planetary propagation on the earth sphere. Based on the linear barotropic vorticity equation, the planetary wave ray path is calculated in the winter January. It shows that NAO(North Atlantic Oscillation),AO and North Pacific could be linked through the planetary wave propagation, which acts as the atmospheric bridge. The zonal symmetric and asymmetric structures both have association with these Rossby wave activities. 相似文献
100.
文中给出了模拟电路多故障诊断的回路法和网孔法,使K故障诊断理论内容完整,在某些情况下,回路诊断法具有一定的优越性。 相似文献