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Method with reliable accuracy and fast speed for measuring operational current of HTS NI closed-loop coils in steady persistent-current-mode

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Superconductivity 2024年第1期9卷 65-73页

作者： li Lu Wei Wu Xin Yu Zhuoyan Zhong Kai li Chengyun Pan Mengzhu li Zhijian Jin School of Electrical Engineering and Electronic Information Shanghai Jiao Tong UniversityMinghang District200240 ShanghaiPR China Shanghai Superconductor Technology Co. Ltd.Pudong New District201203 ShanghaiPR China CRRC Changchun Railway Vehicles Co. Ltd.Changchun 130062JilinPR China

This study proposes a method for measuring the operational current of high temperature superconducting(HTS)non‐insulation(NI)closed‐loop coils,which operate in the steady persistent‐current‐mode(PCM).HTS NI closed‐loop coils are promising for many easily‐quenching direct‐current(DC)applications,where their performance is determined by magnetomotive forces,total number of turns,and *** the primary interface parameter in an application system,the operational current must be accurately and rapidly ***,this is achieved by dividing the measured magnetic field by the coil ***,even if the influence of the screening current induced field(SCIF)is not considered,existing methods for the coil constant may be disturbed by the performance and location of Hall sensors,or experience a long measuring ***,a relatively accurate and fast method is proposed in this study,which is based on adjusting the output current of the adjustable power supply and monitoring the coil voltage as an *** proposed method was validated through experiments and simulations using an equivalent circuit model coupled with a finite element method(FEM)model,and its current accuracy can be equivalent to the resolution of the employed power *** was demonstrated that this method reduced the requirements for Hall sensor’s performance and location,and has a more reliable accuracy in contrast to the simulation *** to the experimentally conventional method,the proposed method presents a significantly faster *** impact of the SCIF was considered and proven to be negligible for the tested pancake *** for coils whose coil constant vibrates owing to the SCIF,this method can be adapted to directly measure various operational ***,it was demonstrated that the measurement error can be influenced by the current discrepancy among turns when the coil is not in the steady PCM,and a procedure for reducing this error was pr

关键词： Operational current HTS NI closed‐loop coils Measurement method Adjustable power supply Coil voltage

Autogenous healing mechanism of cement-based materials

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结构与土木工程前沿:英文版 2023年第6期17卷 948-963页

作者： Desheng li Hao ZHENG kang GU Lei LANG Shang shi Bing CHEN Department of Civil Engineering School of ScienceNanjing University of Science and TechnologyNanjing210094China School of Transportation Science and Engineering Harbin Institute of TechnologyHarbin150090China State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai200240China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsWuhan430071China

Autogenous self-healing is the innate and fundamental repair capability of cement-based materials for healing *** researchers have investigated factors that influence autogenous ***,systematic research on the autogenous healing mechanism of cement-based materials is *** healing process mainly involves a chemical process,including further hydration of unhydrated cement and carbonation of calcium oxide and calcium ***,the autogenous healing process is influenced by the material constituents of the cement composite and the ambient *** this study,different factors influencing the healing process of cement-based materials were *** electron microscopy and optical microscopy were used to examine the autogenous healing mechanism,and the maximum healing capacity was ***,detailed theoretical analysis and quantitative detection of autogenous healing were *** study provides a valuable reference for developing an improved healing technique for cement-based composites.

关键词： autogenous healing cement-based materials healing mechanism aggregation effect

激光功率和扫描策略对TiC增强高碳钢硬质合金层开裂行为影响规律

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焊接学报 2024年第7期45卷 109-115页

作者：周群赵轩李永健何石何鹏彭中亚李曙光成都航利(集团)实业有限公司成都611936 哈尔滨工业大学材料结构精密焊接与连接全国重点实验室哈尔滨150001 江苏大学机械工程学院镇江212013

TiC增强高碳钢硬质合金是一种在工业领域得到广泛应用的耐磨材料,但在激光熔覆制备过程中容易产生裂纹.文中采用仿真分析和熔覆试验确定了激光功率和扫描策略对硬质合金裂纹行为的影响规律.借助ANSYS软件采用有限元法确定激光熔覆后熔... 详细信息

TiC增强高碳钢硬质合金是一种在工业领域得到广泛应用的耐磨材料,但在激光熔覆制备过程中容易产生裂纹.文中采用仿真分析和熔覆试验确定了激光功率和扫描策略对硬质合金裂纹行为的影响规律.借助ANSYS软件采用有限元法确定激光熔覆后熔覆层中的温度梯度和残余应力分布,采用扫描电子显微镜(SEM)对显微组织进行分析,结果表明,激光功率和扫描策略不同会导致在熔覆层内产生不同的热梯度分布、残余应力分布以及物相组织演变,这是造成熔覆层具有不同开裂倾向性的主要原因.高激光功率结合往复扫描策略带来了高热输入和低温度梯度,可有效减少开裂倾向.随着激光功率的增加,TiC陶瓷相会熔化溶解,合金明显呈现回火组织特征,逐渐形成贝氏体组织和回火马氏体组织,进一步有利于降低裂纹产生的倾向.

关键词：激光熔覆开裂行为钢结硬质合金显微组织残余应力

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基于改进DINO的铁路接触网异物检测方法

中国铁道科学 2024年第4期45卷 158-167页

作者：史天运侯博李国华代明睿中国铁道科学研究院集团有限公司北京100081 中国铁道科学研究院集团有限公司电子计算技术研究所北京100081

针对铁路接触网异物类别多样、场景多变的开放目标检测问题,提出基于改进DINO目标检测算法的铁路接触网异物检测方法。首先,基于铁路接触网异物图像特征,利用EfficientNet网络替换原始模型中的Resnet主干网络,并结合卷积注意力模块(Conv... 详细信息

针对铁路接触网异物类别多样、场景多变的开放目标检测问题,提出基于改进DINO目标检测算法的铁路接触网异物检测方法。首先,基于铁路接触网异物图像特征,利用EfficientNet网络替换原始模型中的Resnet主干网络,并结合卷积注意力模块(Convolutional Block Attention Module,CBAM)对EfficientNet网络进行改进,在颈部结构采用改进后的加权双向特征金字塔网络(Bidirectional Feature Pyramid Network,BiFPN),以增强模型对重要特征的关注度,提升检测性能;其次,通过马赛克数据增强和环境干扰等多种数据增强技术对输入图片数据进行处理,丰富样本数据的特征;最后,利用铁路人工智能平台实现铁路接触网异物检测的应用。结果表明:所提方法在性能方面表现优异,其平均精度均值可达89.87%,与YOLOv5,DETR和原始DINO这3种典型的目标检测算法相比,分别提高了6.40%,7.31%和5.75%。该方法能够满足行车线路上接触网异物的准确、快速及智能化识别要求,为接触网异物检测提供重要的技术支撑。

关键词：铁路接触网异物识别目标检测人工智能平台卷积注意力模块

基于GRACE与GLDAS数据的黄河流域甘肃段地下水可持续性研究

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中国沙漠 2024年第2期44卷 196-206页

作者：康小虎李琳孙超刘鹄甘肃省农村饮水安全管理办公室甘肃兰州730000 中国科学院西北生态环境资源研究院甘肃兰州730000 甘肃省水利科学研究院甘肃兰州730000

黄河流域甘肃段水资源供需矛盾突出,地下水环境承载负荷较高,针对该区域开展地下水可持续性评估可为全省乃至整个黄河流域的高质量发展提供重要参考。在地下水监测数据验证的基础上,利用GRACE、GLDAS数据对黄河流域甘肃段2002—2022年... 详细信息

黄河流域甘肃段水资源供需矛盾突出,地下水环境承载负荷较高,针对该区域开展地下水可持续性评估可为全省乃至整个黄河流域的高质量发展提供重要参考。在地下水监测数据验证的基础上,利用GRACE、GLDAS数据对黄河流域甘肃段2002—2022年的地下水储量变化量与地下水可持续性进行了分析。结果表明:期间区域地下水储量季节性波动显著、年际变化较大,地下水储量呈下降趋势;地下水系统整体可靠性和脆弱性较高,可恢复性与可持续性较低。空间上,区域内地下水系统的可持续性指数(Sustainability Index,SI)呈现整体降低、区域增加和较高持续性区域范围缩减、中心转移的特点(SI为0~0.5);时间上,研究期间可持续性指数呈波动下降趋势,但下降速率持续放缓,部分年份可持续性指数有所升高。影响地下水可持续性下降的主要因素为人类活动开采消耗地下水(如农田灌溉和工业用水);政策因素(如水资源管理举措)在一定程度上减缓了地下水下降速率与持续恶化趋势。未来应考虑采用节流保护、开源控制的举措,促进黄河流域甘肃段地下水资源可持续性的逐步提升。

关键词：黄河流域甘肃省地下水可持续性 GRACE GLDAS

Robust Correlation Clustering Problem with Locally Bounded Disagreements

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Tsinghua Science and Technology 2024年第1期29卷 66-75页

作者： Sai Ji Min li Mei liang Zhenning Zhang Institute of Mathematics Hebei University of TechnologyTianjin 300401China School of Mathematics and Statistics Shandong Normal UniversityJinan 250358China College of Statistics and Data Science Beijing University of TechnologyBeijing 100124China Department of Operations Research and Information Engineering Beijing University of TechnologyBeijing 100124China

Min-max disagreements are an important generalization of the correlation clustering problem(CorCP).It can be defined as *** a marked complete graph G=(V,E),each edge in the graph is marked by a positive label"+"or a negative label"_"based on the similarity of the connected *** goal is to find a clustering C of vertices V,so as to minimize the number of disagreements at the vertex with the most ***,the disagreements are the positive cut edges and the negative non-cut edges produced by clustering *** paper considers two robust min-max disagreements:min-max disagreements with outliers and min-max disagreements with *** parameter δ∈(0,1/14),we first provide a threshold-based iterative clustering algorithm based on LP-rounding technique,which is a(1/δ,7/(1-14δ))-bi-criteria approximation algorithm for both the min-max disagreements with outliers and the min-max disagreements with outliers on one-sided complete bipartite ***,we verify that the above algorithm can achieve an approximation ratio of 21 for min-max disagreements with penalties when we set parameter δ=1/21.

关键词： min-max disagreements outliers penalties approximation algorithm LP-rounding

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阿尔金断裂东段的河流阶地累积位错

地震地质 2024年第3期46卷 547-569页

作者：李路瑶丁锐姜大伟张世民应急管理部国家自然灾害防治研究院北京100085

阿尔金断裂带是青藏高原北缘的大型左旋走滑断裂,其东段与NW走向的祁连山逆冲断裂带斜接。文中基于无人机摄影测量技术(SfM)获得的高分辨率影像数据,对阿尔金断裂带东段长约127km的段落开展了详细解译,并对其中9个典型河流阶地位错点进... 详细信息

阿尔金断裂带是青藏高原北缘的大型左旋走滑断裂,其东段与NW走向的祁连山逆冲断裂带斜接。文中基于无人机摄影测量技术(SfM)获得的高分辨率影像数据,对阿尔金断裂带东段长约127km的段落开展了详细解译,并对其中9个典型河流阶地位错点进行测量与统计。沿阿尔金断裂带向E,晚第四纪左旋累积位移总体呈衰减趋势,且以断裂带东侧NW走向斜接逆冲断裂或逆冲走滑断裂为界,其累积位错量在同一断裂段内大致相当,但相邻断裂段之间表现为阶梯状递减,指示了斜接断裂的构造转换关系及可能的地震破裂分段作用,为阿尔金断裂带活动性分段研究与潜在发震能力评价提供了依据。

关键词：阿尔金断裂带高分辨率地形数据累积位移断错地貌构造转换

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Regulating the crystal phase of bismuth-based semiconductors for promoted photocatalytic performance

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Science China Chemistry 2024年第6期67卷 1839-1864页

作者： Zhaohui Wu Mei-Chi Chong shiying Zhang Junshan li Yongfa Zhu Hunan Key Laboratory of Applied Environmental Photocatalysis Changsha UniversityChangsha410022China Department of Chemistry Tsinghua UniversityBeijing100084China Institute for Advanced Study Chengdu UniversityChengdu610106China

Numerous bismuth-based semiconductors(BBSs)with sophisticated and desirable structures used as photocatalysts for efficient photocatalytic degradation of water organic contaminants have attracted considerable ***,regulating the crystal phases and phase transition of BBSs for promoted photocatalytic performance is ***,the unique crystal structure and band structure features of each typical BBSs,and the vital roles on phase controlling of each phase were systematically presented based on the classification of ***,the critical factors for the phase transition of BBSs and intrinsic driving forces endowed by phases of BBSs for enhanced photocatalytic performance of organic contaminants removal were also *** review will provide systematical guidelines and horizons for regulating the crystal phase and phase transition of BBSs,promoting photocatalytic degradation and mineralization of organic contaminants.

关键词： bismuth-based semiconductors phase regulation photocatalytic performances organic contaminants

Influence of secondary lining thickness on mechanical behaviours of double-layer lining in large-diameter shield tunnels

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Underground Space 2024年第5期18卷 130-150页

作者： shimin Wang Xuhu He Xiaoyu Peng Ya Wang Zhengxin li Zihan Song Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China

In large-diameter shield tunnels,applying the double-layer lining structure can improve the load-bearing properties and maintain the stability of segmental *** secondary lining thickness is a key parameter in the design of a double lining structure,which is worth being *** on an actual large-diameter shield tunnel,loading model tests are carried out to investigate the effect of the secondary lining thickness on the mechanical behaviours of the double lining *** test results show that within the range of secondary lining thicknesses discussed,the load-bearing limit of the double-layer lining increases with growing secondary lining *** a passive support,the secondary lining acts as an auxiliary load-bearing structure by contacting the *** changes in secondary lining thickness have a significant effect on the contact state between the segment and secondary lining,with both the contact pressure level and the contact area between the two *** double-layer lining structures in large-diameter shield tunnels,it is proposed that the stiffness of the secondary lining needs to be matched to the stiffness of the segment,as this allows them to have a coordinated deformation and a good joint load-bearing effect.

关键词： Large-diameter shield tunnels Double-layer lining structure Secondary lining thickness Stiffness matching Similar model test