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孔堰结合梯形量水堰淹没出流水力特性及应用
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作者 李若兰 李晓庆 +1 位作者 高飞飞 戚印鑫 《农业工程学报》 北大核心 2025年第12期143-151,共9页
针对传统梯形堰上游壅水高度大、易受泥沙淤积影响以及堰板前渠道存在冻胀风险等问题,该研究提出了孔堰结合梯形量水堰。为了研究该堰在淹没出流工况下的水力特性规律,并为实际工程的应用提供理论指导,该研究构建1:1水工物理模型,设置... 针对传统梯形堰上游壅水高度大、易受泥沙淤积影响以及堰板前渠道存在冻胀风险等问题,该研究提出了孔堰结合梯形量水堰。为了研究该堰在淹没出流工况下的水力特性规律,并为实际工程的应用提供理论指导,该研究构建1:1水工物理模型,设置流量为27.14、38.14、47.36、55.47、64.22 L/s,底孔开孔高度z为50、60、70、80 mm 4个尺寸,研究不同开孔高度堰板在淹没出流状态下的临界淹没度阈值、淹没流态类型、沿程水面线、堰板开孔处上游流速分布等水力特性,并基于量纲分析和多元非线性拟合推导淹没出流工况下的量测计算式。结果表明:开孔高度z=80 mm的堰板,临界淹没度阈值为0.754,稳定淹没类型(表面波和表面射流)占比较高,上游壅水程度较改进梯形堰降低42.86%,堰板开孔处上游区域各点流速也均大于泥沙不淤流速(0.3 m/s)。当开孔高度z∈[50,80]mm时,通用预测模型(z为变量)的验证结果显示,94.48%的实测值与预测值的相对误差<±5.00%;当z=80 mm(水力特性和工程适应性最优)时,预测模型(z为定值)的验证结果显示,实测值与预测值的相对误差均<±5.00%。研究成果可为类似孔堰结合量水设施的水力特性研究提供参考,为田间渠道量水提供低扰动、高适配性、高精度的便捷解决方案。 展开更多
关键词 孔堰结合 梯形水堰 淹没出流 纲分析 量测计算式
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Fingerprint singular points extraction based on orientation tensor field and Laurent series 被引量:3
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作者 刘琴 彭可 +4 位作者 刘巍 谢琴 李仲阳 兰浩 金耀 《Journal of Central South University》 SCIE EI CAS 2014年第5期1927-1934,共8页
Singular point(SP)extraction is a key component in automatic fingerprint identification system(AFIS).A new method was proposed for fingerprint singular points extraction,based on orientation tensor field and Laurent s... Singular point(SP)extraction is a key component in automatic fingerprint identification system(AFIS).A new method was proposed for fingerprint singular points extraction,based on orientation tensor field and Laurent series.First,fingerprint orientation flow field was obtained,using the gradient of fingerprint image.With these gradients,fingerprint orientation tensor field was calculated.Then,candidate SPs were detected by the cross-correlation energy in multi-scale Gaussian space.The energy was calculated between fingerprint orientation tensor field and Laurent polynomial model.As a global descriptor,the Laurent polynomial coefficients were allowed for rotational invariance.Furthermore,a support vector machine(SVM)classifier was trained to remove spurious SPs,using cross-correlation coefficient as a feature vector.Finally,experiments were performed on Singular Point Detection Competition 2010(SPD2010)database.Compared to the winner algorithm of SPD2010 which has best accuracy of 31.90%,the accuracy of proposed algorithm is 45.34%.The results show that the proposed method outperforms the state-of-the-art detection algorithms by large margin,and the detection is invariant to rotational transformations. 展开更多
关键词 fingerprint extraction singular point fingerprint orientation tensor field Laurent series rotational invariance supportvector machine (SVM)
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