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Cavitation research with computational fluid dynamics:From Euler-Euler to Euler-Lagrange approach

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Journal of Hydrodynamics 2024年第1期36卷 1-23页

作者： bin ji Zi-yang Wang Huai-yu Cheng Rickard E.Bensow State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan430072China Department of Mechanics and Maritime Sciences Chalmers University of TechnologyGothenburgSweden

Unsteady cavitating flow often contains vapor structures with a wide range of different length scales,from micro-bubbles to large cavities,which issues a big challenge to precisely investigate its evolution mechanism by computational fluid dynamics(CFD)*** present work reviews the development of simulation methods for cavitation,especially the emerging Euler-Lagrange ***,the progress of the numerical investigation of hot and vital issues is discussed,including cavitation inception,cloud cavitation inner structure and its formation mechanism,cavitation erosion,and cavitation *** is indicated that the Euler-Lagrange method can determine cavitation inception point *** cloud cavitation,the Euler-Lagrange method can reveal the source of microbubbles and their distribution law inside the shedding *** method also has advantages and great potential in assessing cloud cavitation-induced erosion and *** the ever-growing demands of cavitation simulation accuracy in basic research and engineering applications,how to improve the Euler-Lagrange method’s stability and applicability is still an open *** further promote the application of this advanced CFD simulation technology in cavitation research,some key issues are to be solved and feasible suggestions are put forward for further work.

关键词： numerical simulation Euler-Euler method Euler-Lagrange method bubble dynamicsgy,Gothenburg,Sweden

SciCN:A Scientific Dataset for Chinese Named Entity Recognition

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Computers, Materials & Continua 2024年第3期78卷 4303-4315页

作者： jing Yang bin ji Shasha Li Jun Ma jie Yu College of Computer National University of Defense TechnologyChangsha410073China

Named entity recognition(NER)is a fundamental task of information extraction(IE),and it has attracted considerable research attention in recent *** abundant annotated English NER datasets have significantly promoted the NER research in the English *** contrast,much fewer efforts are made to the Chinese NER research,especially in the scientific domain,due to the scarcity of Chinese NER *** alleviate this problem,we present aChinese scientificNER dataset–SciCN,which contains entity annotations of titles and abstracts derived from 3,500 scientific *** manually annotate a total of 62,059 entities,and these entities are classified into six *** to English scientific NER datasets,SciCN has a larger scale and is more diverse,for it not only contains more paper abstracts but these abstracts are derived from more research *** investigate the properties of SciCN and provide baselines for future research,we adapt a number of previous state-of-theart Chinese NER models to evaluate *** results show that SciCN is more challenging than other Chinese NER *** addition,previous studies have proven the effectiveness of using lexicons to enhance Chinese NER *** by this fact,we provide a scientific domain-specific *** results demonstrate that our lexicon delivers better performance gains than lexicons of other *** hope that the SciCN dataset and the lexicon will enable us to benchmark the NER task regarding the Chinese scientific domain and make progress for future *** dataset and lexicon are available at:https://***/yangjingla/***.

关键词： Named entity recognition dataset scientific information extraction lexicon

Span-based joint entity and relation extraction augmented with sequence tagging mechanism

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Science China(Information Sciences) 2024年第5期67卷 84-98页

作者： bin ji Shasha LI Hao XU jie YU Jun MA Huijun LIU jing YANG College of Computer National University of Defense Technology

Span-based joint extraction simultaneously conducts named entity recognition(NER) and relation extraction(RE) in a text span form. However, since previous span-based models rely on span-level classifications, they cannot benefit from token-level label information, which has been proven advantageous for the task. In this paper, we propose a sequence tagging augmented span-based network(STSN), a spanbased joint model that can make use of token-level label information. In STSN, we construct a core neural architecture by deep stacking multiple attention layers, each of which consists of three basic attention *** the one hand, the core architecture enables our model to learn token-level label information via the sequence tagging mechanism and then uses the information in the span-based joint extraction; on the other hand, it establishes a bi-directional information interaction between NER and RE. Experimental results on three benchmark datasets show that STSN consistently outperforms the strongest baselines in terms of F1,creating new state-of-the-art results.

关键词： joint extraction named entity recognition relation extraction span sequence tagging mechanism

Evaluation of the injection and plugging ability of a novel epoxy resin in cement cracks

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Petroleum Science 2024年第2期21卷 1211-1220页

作者： Guang-Yao Leng Wei Yan Hai-Mu Ye Er-Dong Yao ji-bin Duan Zheng-Xian Xu Ke-Pei Li jing-Ru Zhang Zhong Li State Key Laboratory of Petroleum Resource&Prospecting China University of Petroleum(Beijing)Beijing102249China CNPC Liaohe Oilfield Gas Storage Co.LTD Panjin124000LiaoningChina CNOOC Research Institute Co. Ltd.Beijing100028China

Sustained casing pressure(SCP)is a crucial issue in the oil and gas production *** resins,exhibiting exceptional compressive strength,ductility,and shear bonding strength,have the potential to form reliable *** injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation *** study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid *** investigation evaluated the viscosity,compressive strength,and brittleness index of the epoxy resin sealant,as well as its tangential and normal shear strengths in conjunction with casing *** flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in *** results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin,ranging from 1.5 to 6 h,and reduced the initial viscosity from 865.53 to 118.71 m Pa,*** mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor *** epoxy resin containing 30%curing agent exhibited optimal mechanical *** a 14-day curing period,the epoxy resin's compressive strength reached81.37 MPa,2.12 times higher than that of cement,whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy *** brittleness index of epoxy resin is only 3.42,demonstrating high flexibility and *** tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times,*** a 0.5 mm-wide crack,the injection pressure of the epoxy resin remained below 0.075 MPa,indicating superior injection and flow ***,the injection pressure of cement surged dramatically to 2.61 MPa within 5 *** breakthrough pressure of0.5 PV epoxy resin reached 7.53 MPa,decreasing the crack's perme

关键词： Sustained casing pressure Epoxy resin sealant Curing agent Viscosity reducer Mechanical properties Crack sealing

融合分解和自适应邻域的多目标离散组合优化算法

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计算机科学与探索 2024年第7期18卷 1762-1775页

作者：韦倩季彬中南大学交通运输工程学院长沙410075

为了高效获取现实中大规模多目标优化问题解决方案,实现收敛性、多样性和均匀性的平衡逐渐发展为多目标优化的重要目标之一。针对复杂多目标离散组合优化问题,提出了融合分解和自适应邻域的多目标离散组合优化算法(MOALNS)。该算法在问... 详细信息

为了高效获取现实中大规模多目标优化问题解决方案,实现收敛性、多样性和均匀性的平衡逐渐发展为多目标优化的重要目标之一。针对复杂多目标离散组合优化问题,提出了融合分解和自适应邻域的多目标离散组合优化算法(MOALNS)。该算法在问题分解的基础上为各子问题的寻优进程引入大邻域搜索策略与自适应调整机制,形成一套新型的收敛指导准则突破寻优阻力,进而使各子问题在搜索多维解空间的过程中达到全局搜索与局部搜索的平衡。同时,提出为各子问题配置独立算子积分库可有效地调整各子问题的寻优方向,解决由于目标权重不同而造成的求解方向偏差问题,以此实现更为高效、稳定的多目标优化进程。数值实验表明,提出的新型多目标离散组合优化算法在多组标准测试算例与真实案例中均展现出了在收敛性、多样性、均匀性和延展性等方面的良好性能,相较于其他经典多目标优化算法而言更具优势。

关键词：多目标离散组合优化问题分解大邻域搜索自适应机制

Infrared small target detection based on density peaks searching and weighted multi-feature local difference

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Optoelectronics Letters 2024年

作者： ji bin FAN Pengxiang WANG Mengli LIU Yang XU jiafeng School of Computer Science and Technology， Anhui University of Technology

In order to solve the problems of unknown target size， fuzzy edges， background interference and low contrast in infrared small target detection， this paper proposes an infrared small target detection method based on density peaks searching and weighted multi-feature local difference. Firstly， for the interference problem of high brightness clutter on the density peaks searching to obtain candidate targets， this paper adopts the improved high-boost filter for preprocessing， which effectively eliminates the background clutter and high brightness background interference in the infrared image， and improves the probability of the true target being captured in the density peaks searching process. Secondly， triple-layer windows are used to extract features from the area around the candidate target， which solves the problem of uncertain size of small targets. Additionally， by calculating the multiple feature local differences between triple-layer windows， the problem of blurred edges and low contrast for the targets are also resolved. In order to balance the contribution degree of different feature local differences to target detection， this paper introduces the intra-class distance to calculate the weight of each feature local differences， realizes the weighted fusion of multi-feature local differences， obtains the weighted multi-feature local difference of each candidate target， and extracts the real target from the candidate target through the interquartile range. Experiments on many different types of infrared image sequences consisting of publicly available datasets such as SIRST and IRSTD-1K show that the method proposed in this paper is applicable to a wide range of complex types with good robustness and detection performance.

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藻-菌颗粒污泥粒径与除污效能的研究

南京大学学报（自然科学版） 2024年第1期60卷 151-157页

作者：胡国胜季斌武汉科技大学城市建设学院武汉430065

作为一种光驱动的新兴污水处理工艺,藻-菌颗粒污泥(Microalgae-Bacterial Granular Sludge,MBGS)因其高除污效能、低能耗、零温室气体排放等优点而被广泛研究.MBGS粒径可以影响MBGS的藻-菌质量比与生态位,从而影响其传质及光利用效率,... 详细信息

作为一种光驱动的新兴污水处理工艺,藻-菌颗粒污泥(Microalgae-Bacterial Granular Sludge,MBGS)因其高除污效能、低能耗、零温室气体排放等优点而被广泛研究.MBGS粒径可以影响MBGS的藻-菌质量比与生态位,从而影响其传质及光利用效率,进而影响其污染物去除效能.鉴于此,考察了不同粒径MBGS(1.08,2.20,3.17和4.08 mm)的除污效能,发现1.08 mm的MBGS系统对有机物、氨氮及磷酸盐的去除效能最高,同时其出水溶解氧浓度最高.进一步结合文献调研和分析表明:当光强为100~500μmol·m^(-2)·s^(-1)时,MBGS最优粒径范围为0.80~1.60 mm;MBGS粒径对于有机物及氨氮的去除影响较磷酸盐更大;通过提供剪切力(如水力或机械搅拌)能够维持MBGS的最优粒径.研究结果可为MBGS工艺应用于实际污水处理提供理论基础.

关键词：藻-菌颗粒污泥污水生物处理颗粒粒径搅拌碳中和

压水反应堆蒸汽发生器传热管焊接堵管工艺实践

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发电设备 2024年第2期38卷 109-114页

作者：冀斌国核电站运行服务技术有限公司上海200233

基于某核电厂压水反应堆蒸汽发生器传热管的焊接堵管案例,根据2021年版ASME BPVC规范,主要从堵头材料、焊接材料、焊接工艺评定、堵管工艺操作技术等方面进行分析,以确保压水反应堆蒸汽发生器传热管焊接堵管工艺的有效性。采用经评定合... 详细信息

基于某核电厂压水反应堆蒸汽发生器传热管的焊接堵管案例,根据2021年版ASME BPVC规范,主要从堵头材料、焊接材料、焊接工艺评定、堵管工艺操作技术等方面进行分析,以确保压水反应堆蒸汽发生器传热管焊接堵管工艺的有效性。采用经评定合格的堵管工艺,对该核电厂蒸汽发生器的破损传热管进行堵管,蒸汽发生器投用后未再发生泄漏,堵管效果良好。研究结果为国内核电厂蒸汽发生器传热管破损后焊接堵管工艺提供了技术参考。

关键词：压水反应堆蒸汽发生器传热管堵头焊接

无锡市Omicron毒株引起的新型冠状病毒感染者相关持续症状的特征及其影响因素

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中华疾病控制杂志 2024年第2期28卷 221-227页

作者：詹星雅刘娟冀斌沈元南京医科大学公共卫生学院流行病学系南京211166 南京医科大学附属无锡疾病预防控制中心急性传染病防制科无锡214023

目的探究Omicron毒株引起的新型冠状病毒感染(新冠感染)者康复后3~4个月存在相关持续症状的特征及其影响因素,为制定随访计划、减少感染后相关持续症状提供依据。方法采用自编的躯体与精神神经症状量表、患者健康问卷(patient health qu... 详细信息

目的探究Omicron毒株引起的新型冠状病毒感染(新冠感染)者康复后3~4个月存在相关持续症状的特征及其影响因素,为制定随访计划、减少感染后相关持续症状提供依据。方法采用自编的躯体与精神神经症状量表、患者健康问卷(patient health questionnaire,PHQ-9)、压力知觉量表(Chinese perceived stress scale,CPSS)、焦虑量表(generalised anxiety disorder scale,GAD-7)和自编的疾病污名化量表进行调查。采用Mann-Whitney U检验、Kruskal-Wallis H检验、χ^(2)检验和二元logistic回归分析模型分析。结果有50.7%的受访者在康复后3~4个月存在相关持续症状,共报告躯体与精神神经症状47种,疲劳乏力是最常见的躯体症状(50.5%),失眠是最常见的精神神经症状(24.3%),抑郁和焦虑均与躯体或精神神经症状伴随出现。女性(β=0.70,OR=2.01,95%CI:1.04~3.86,P=0.037)、隔离期间存在临床症状(β=0.78,OR=2.17,95%CI:1.13~4.20,P=0.021)、中高压力(β=1.68,OR=5.35,95%CI:2.14~13.38,P<0.001)、严重污名化(β=1.03,OR=2.79,95%CI:1.33~5.83,P=0.006)是新冠感染者出院3~4个月后存在持续症状的危险因素。结论部分新冠感染者康复后3~4个月时仍存在相关持续症状。重点关注可能出现相关持续症状的高风险人群,并同时在医疗保健和精神心理卫生方面给予支持。

关键词：新型冠状病毒感染 Omicron毒株持续症状影响因素