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Transient simulation of a pump-turbine with misaligned guide vanes during turbine model start-up

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Acta Mechanica sinica 2014年第5期30卷 646-655页

作者： Ye-Xiang Xiao ruo-Fu Xiao state Key Laboratory of Hydroscience and Engineering & Department of Thermal Engineering Tsinghua University College of Water Resources and Civil Engineering China Agricultural University

Experimental studies of a model pump-turbine s-curve characteristics and its improvement by misaligned guide vanes （MGV） were extended to prototype pump turbine through 3-D transient flow simulations. The unsteady Reynolds-averaged Navier-stokes equations with the ssT turbulence model were used to model the transient flow within the entire flow passage of a reversible pump-turbine with and without misaligned guide vanes during turbine model start-up. The unstable s-curve and its improvement by using misaligned guide vane were verified by model test and simulation. The transient flow calculations were used to clarify the variations of pressure pulse and internal flow behavior in the entire flow passage. The use of misaligned guide vanes can eliminate the s-curve characteristics of a pump-turbine, and can significantly increase the pressure pulse amplitude in the entire flow passage and the runner radial forces during start-up. The MGV only decreased the pulse amplitude on the guide vane suction side when the rotating speed was less than 50% rated speed. The hydraulic reason is that the MGV dramatically changed the flow patterns inside the entire flow passage, and destroyed the symmetry of the flow distribution inside the guide vane and runner.

关键词： Transient flow. Pump turbine. Misaligned guide vane Model test Pressure pulse

常规增强联合DWI在不可切除肝内胆管癌靶免联合治疗无进展生存预测中的价值

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放射学实践 2024年第2期39卷 227-232页

作者：盛若凡吴东郑碚璇黄晓勇曾蒙苏复旦大学附属中山医院放射科/上海市影像医学研究所上海200032 复旦大学附属中山医院肝外科上海200032

目的:探讨MRI在不可切除肝内胆管癌(iCCA)靶免联合治疗无进展生存预测中的价值。方法:纳入23例经穿刺病理证实的iCCA患者,所有患者均接受Gemox化疗联合伦伐替尼和PD-1单抗治疗。采用log-rank检验和Cox回归模型分析治疗后疾病进展的临床... 详细信息

目的:探讨MRI在不可切除肝内胆管癌(iCCA)靶免联合治疗无进展生存预测中的价值。方法:纳入23例经穿刺病理证实的iCCA患者,所有患者均接受Gemox化疗联合伦伐替尼和PD-1单抗治疗。采用log-rank检验和Cox回归模型分析治疗后疾病进展的临床-影像独立危险因素,并构建无进展生存预测诺莫图。结果:23例患者中15例在随访期间出现疾病进展,总体1年无进展生存率仅为33.5%。多因素分析结果显示,动脉期瘤周异常强化(风险比=5.747,P=0.029)、出血(风险比=5.460,P=0.033),表观扩散系数(ADC)值≤1.273×10^(-3)mm^(2)/s(风险比=6.261,P=0.004)是疾病进展的独立危险因素。伴有动脉期瘤周异常强化、出血和低ADC值的iCCA患者1年无进展生存率显著低于无动脉期瘤周异常强化(P=0.0045)、无出血(P=0.013)和高ADC值(P=0.002)。联合上述3项独立影像特征构建的诺莫图具有最高的无进展生存预测效能,C指数值为0.856(95%CI:0.785~0.927),优于任一单一影像特征(P=0.0015~0.022)。结论:基于常规增强联合DWI、诺莫图对靶免治疗不可切除iCCA无进展生存预测具有更优的预测效能。

关键词：肝内胆管癌磁共振成像扩散加权成像无进展生存联合治疗

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中国天然林碳汇贡献及碳汇潜力研究

西北林学院学报 2024年第3期39卷 266-274,280页

作者：胡忠宇苏建兰张若萱李茂梅西南林业大学经济管理学院云南昆明650224 四川农业大学经济学院四川成都611130 辽宁师范大学辽宁大连116029

采用生物量转换因子法核算全国天然林碳储量和碳密度,利用Logistic生长方程预测2023-2063年全国天然林碳汇潜力。结果表明:1)40 a间全国天然林碳储量增长明显,净增236950.27万t,增长率达65.27%,碳密度整体呈“升-降-升”趋势;2)9次清查... 详细信息

采用生物量转换因子法核算全国天然林碳储量和碳密度,利用Logistic生长方程预测2023-2063年全国天然林碳汇潜力。结果表明:1)40 a间全国天然林碳储量增长明显,净增236950.27万t,增长率达65.27%,碳密度整体呈“升-降-升”趋势;2)9次清查结果中,除第2次清查碳汇值为负值外,其他期间均表现为正的碳汇,9期清查平均碳汇为5800.06万t·a^(-1);3)第七次至第九次清查中,碳储量贡献前6的省均为西藏(91877.33万~93646.56万t)>云南(69712.67万~81015.10万t)>黑龙江(63810.25万~74683.36万t)>四川(55134.20万~62347.95万t)>内蒙古(49795.04万~61786.99万t)>吉林(32997.31万~38833.95万t),不同区域碳储量贡献关系均为西南地区(42.54%~45.67%)>东北地区(20.29%~20.54%)>华北地区(10.93%~11.56%)>中南地区(8.92%~9.86%)>华东地区(7.13%~8.56%)>西北地区(6.81%~7.20%),碳密度关系均为西南地区(66.68~68.09 t·hm^(-2))>东北地区(41.69~47.42 t·hm^(-2))>西北地区(41.29~45.82 t·hm^(-2))>华北地区(32.38~39.18 t·hm^(-2))>华东地区(27.35~38.69 t·hm^(-2))>中南地区(24.11~31.57 t·hm^(-2));4)Logistic生长方程下2030年全国天然林碳储量潜力达715320.29万t,2060年达到867620.71万t,全国天然林资源将为碳中和目标达成发挥巨大作用。

关键词：碳储量森林碳汇潜力碳中和 Logistic生长方程天然林

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Multi-layer Contribution Propagation Analysis for Fault Diagnosis

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International Journal of Automation and computing 2019年第1期16卷 40-51页

作者： ruo-Mu Tan Yi Cao school of Water Energy and Environment Cranfield University College of Chemical and Biological Engineering Zhejiang University

The recent development of feature extraction algorithms with multiple layers in machine learning and pattern recognition has inspired many applications in multivariate statistical process monitoring. In this work, two existing multi-layer linear approaches in fault detection are reviewed and a new one with extra layer is proposed in analogy. To provide a general framework for fault diagnosis in succession, this work also proposes the contribution propagation analysis which extends the original definition of contribution of variables in multivariate statistical process monitoring. In fault diagnosis stage, the proposed contribution propagation analysis for multilayer linear feature extraction algorithms is compared with the fault diagnosis results of original contribution plots associated with single layer feature extraction approach. Plots of variable contributions obtained by the aforementioned approaches on the data sets collected from a simulated benchmark case study(Tennessee Eastman process) as well as an industrial scale multiphase flow facility are presented as a demonstration of the usage and performance of the contribution propagation analysis on multi-layer linear algorithms.

关键词： Process monitoring fault detection and diagnosis contribution plots feature extraction multivariate statistics

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语义增强的多视立体视觉方法

计算机技术与发展 2024年第3期34卷 41-48页

作者：韩燮王若蓝赵融中北大学大数据学院山西太原030051 山西省视觉信息处理及智能机器人工程研究中心山西太原030051 机器视觉与虚拟现实山西省重点实验室山西太原030051

针对在基于深度学习技术的特征提取网络中,深层次的卷积神经网络提取的特征缺乏低级语义信息的问题,该文提出了语义增强的多视立体视觉方法。首先,提出了一种ConvLsTM(Convolutional Long short-Term Memory)语义聚合网络,通过使用ConvL... 详细信息

针对在基于深度学习技术的特征提取网络中,深层次的卷积神经网络提取的特征缺乏低级语义信息的问题,该文提出了语义增强的多视立体视觉方法。首先,提出了一种ConvLsTM(Convolutional Long short-Term Memory)语义聚合网络,通过使用ConvLsTM网络结构,对多个卷积层提取的特征图进行预测,得到融合每层语义信息的特征图,有助于在空间上层层抽取图像的高级特征时,利用长短期记忆神经网络结构的记忆功能来增强高层特征图中的低级语义信息,提高了弱纹理区域的重建效果,提高了3D重建的鲁棒性和完整性;其次,提出了一种可见性网络,在灰度图的基础上,通过突出特征图上可见区域的特征,加深了可见区域在特征图中的影响,有助于提高三维重建效果;最后,提取图像的纹理信息,并进入ConvLsTM语义聚合网络提取深层次特征,提高了弱纹理区域的重建效果。与主流的多视立体视觉重建方法相比,重建效果较好。

关键词：三维重建深度学习多视立体视觉特征提取语义聚合网络

Characterization of Ordovician carbonate reservoirs, southeastern saskatchewan, Canada

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成都理工大学学报（自然科学版） 2004年第6期31卷 616-622页

作者： QINGHai-ruo DepartmentofGeology UniversityofReginaReginaSKS4SOA2Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills （-5.9‰ ～ -7.8‰, PDB） and matrix dolomites （-6.6‰ ～ -8.1‰, avg. -7.4‰ PDB） compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87sr/86sr ratios （0.7084～0.7088） that are higher than suggested for the late Ordovician seawaters （0.7078～0.7080）. The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.

关键词：表征奥陶纪碳酸盐萨斯喀彻温省加拿大白云石

基于特征图金字塔的冠脉造影图像血管分割方法

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中国光学（中英文） 2024年第4期17卷 971-981页

作者：郭昊虎高若谦葛明锋董文飞刘炎赵旭峰长春理工大学机电工程学院吉林长春130022 中国科学院苏州生物医学工程技术研究所江苏苏州215163

针对冠脉造影图像照明不均、血管结构与背景区域对比度低、冠脉血管拓扑结构复杂等分割难点,建立了一个冠脉造影血管分割标注数据集,并在此基础上提出了一种基于特征图金字塔的冠脉造影图像血管分割模型。本文模型以U-Net网络为基础进... 详细信息

针对冠脉造影图像照明不均、血管结构与背景区域对比度低、冠脉血管拓扑结构复杂等分割难点,建立了一个冠脉造影血管分割标注数据集,并在此基础上提出了一种基于特征图金字塔的冠脉造影图像血管分割模型。本文模型以U-Net网络为基础进行改进和优化,首先,将U-Net编码部分的第一个卷积层修改为一个7×7的卷积层,并提高每一层的感受野,在编解码层中引入修改后的ConvNeXt block,使得网络提取更深层次特征的能力有所提升;其次,设计分组注意力机制模块GA,并将其引入到U-Net跨连接处,对编码部分提取的特征进行增强,弥补编解码器间存在的语义差距;最后,在U-Net解码器处设计了一个特征图金字塔级联模块PFC,融合各尺度的特征图,并在PFC中每一层中加入sE注意力机制模块,用于筛选特征图中的有效信息,网络损失函数为PFC模块各层输出的加权,以监督网络各层的特征提取。本文模型在测试集上的测试结果如下:Dice系数为0.8843,Jaccard系数为0.7926。实验结果表明,相比其他常用方法,本文模型在冠脉血管分割上具有较强的鲁棒性,在低对比度下能够有效抑制噪声,对冠脉血管具有更好的分割效果。

关键词：冠脉造影血管分割特征金字塔网络注意力机制 U-Net

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semi-supervised identification and mapping of surface water extent using street-level monitoring videos

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Big Earth Data 2023年第4期7卷 986-1004页

作者： ruo-Qian Wang Yangmin Ding Department of Civil and Environmental Engineering RutgersThe State University of New JerseyPiscatawayNJUSA NEC Laboratories America Inc 4 Independence WayPrincetonNJUSA

Urban flooding is becoming a common and devastating hazard,which causes life loss and economic *** and understanding urban flooding in a highly localized scale is a challenging task due to the complicated urban landscape,intri-cate hydraulic process,and the lack of high-quality and resolution *** emerging smart city technology such as monitoring cameras provides an unprecedented opportunity to address the data ***,estimating water ponding extents on land surfaces based on monitoring footage is unreliable using the tradi-tional segmentation technique because the boundary of the water ponding,under the influence of varying weather,background,and ilumination,is usually too fuzzy to identify,and the oblique angle and image distortion in the video monitoring data prevents geor-eferencing and object-based *** paper presents a novel semi-supervised segmentation scheme for surface water extent recognition from the footage of an oblique monitoring *** semi-supervised segmentation algorithm was found suitable to determine the water boundary and the monoplotting method was successfully applied to georeference the pixels of the monitoring video for the virtual quantification of the local drainage *** correlation and mechanism-based analysis demon-strate the value of the proposed method in advancing the under-standing of local drainage *** workflow and created methods in this study have a great potential to study other street-level and earth surface processes.

关键词： segmentation deep learning monoplotting smart city monocular visual data

New hydrous phases in the Al_(2)O_(3)-siO_(2)-H_(2)O system under the mantle transition zone conditions

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science China Earth sciences 2023年第4期66卷 730-737页

作者： Baoyun WANG Jin LIU suyu FU Pu XIAO Li LI Xing DING Wansheng XIAO College of Material and Chemical Engineering Tongren UniversityTongren 554300China Center for High Pressure science and Technology Advanced Research(HPsTAR) Beijing 100193China Department of Earth and Planetary science the University of TokyoTokyo 1130033Japan state Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China Key Laboratory of Mineralogy and Metallogeny Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China

Hydrous minerals in the subducting slabs are potential water carriers into the deep mantle,and thus the synthesis of new hydrous phases is significant in our understanding of water circulation throughout the Earth’s *** this study,we report the two new hydrous phases,Al_(2)siO_(6)H_(2)and Al_(5.5)si_(4)O_(18)H_(3.5)(hereafter referred to simply as phases Psi and Phi,respectively),which are synthesized in the Al_(2)O_(3)-siO_(2)-H_(2)O system at 15.5 GPa,1400℃and 17.5 GPa,1600℃ by using sakura2500-ton multi-anvil *** luminescence spectra of Cr3+show the phase Psi has characteristic peaks at 687,693 and705 nm,while phase Phi has characteristic peaks at 691,696 and 708 ***-crystal X-ray diffraction (sCXRD) refinements yield a monoclinic structure of both phases (space group P2_(1)) with ideal chemical formulae of Al_(2)siO6H2and *** determined lattice parameters for phase Psi are a=9.4168±0.0016Å,b=4.3441±0.0007Å,c=9.4360±0.002Åand β=119.726±0.005°at ambient pressure and 300 K,while the phase Phi has a=7.2549±0.0018Å,b=4.3144±0.001Å,c=8.0520±0.002Å,and β=101.740±0.009°at ambient pressure and 250 *** microprobe analyses (EPMA) show the chemical compositions of phases Psi and Phi to be Al_(1.99)si_(0.85)O_(6)H_(2.62)and Al_(5.58)si_(2.81)O_(18)H_(8.03),respectively,which slightly deviate from the ideal formulae inferred from sCXRD *** may result from the disorder or substitution of Al and si by H in the crystal structures under our synthesis *** study suggests that phases Psi and Phi are the two potential water carriers at the upper part of the mantle transitions zone,providing new insights into how deep water is stored in this region.

关键词： New hydrous phases Mantle transition zone Al_(2)O_(3)-siO_(2)-H_(2)O system Al_(2)siO_(6)H_(2) Al_(5.5)si_(4)O_(18)H_(3.5)