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A Numerical Study on the Effect of the Backflow Hole Position on the Performances of a Self-Priming Pump

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Fluid Dynamics & Materials Processing 2024年第5期20卷 1103-1122页

作者： Dongwei wang lijian Cao Weidong wang Jiajun Hu School of Energy and Power Engineering Lanzhou University of TechnologyLanzhou730050China Sanlian Pump Industry Co. Ltd.Ma’anshan243000China

A self-priming pump is a centrifugal pump that has the ability to prime itself. Typically, its performance dependson the configuration of its reflux hole. In this study, the ANSYS FLUENT software is used to investigate the effectsof three different radial positions of the reflux hole on gas-liquid two-phase distribution, pressure pulsation, andimp during self-priming. The research results indicate that: (1) The effective channel size for the reflux liquid toenter the volute varies depending on the location of the reflux hole. The effect of the impeller rotation on thereflux liquid becomes more obvious as the setting distance of the reflux aperture decreases. (2) The position ofthe reflux hole significantly affects the gas phase mass fraction inside the impeller, resulting in a significant reductionin the time it takes for the mass fraction to exceed 80%. (3) The position of the reflux hole significantly affectsthe average pressure on each monitoring surface. (4) Placing the reflux hole at a excessively distant radial distancecan result in an excessive vertical component. (5) The self-priming performance of the pump can be improved tosome extent by placing the return hole at a small radial distance.

关键词： Self-priming pump self-priming time numerical calculation gas-liquid two-phase flow

Unveiling the time-temperature dependence of metastability of supercooled liquid using nano-calorimetry

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Science China(Physics,Mechanics & Astronomy) 2024年第3期67卷 119-127页

作者： Yijun Ding lijian Song Zheng wang Ruiqi Yu Junqiang wang Lina Hu Yuanzheng Yue Edgar D.Zanotto Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong University Jinan 250061China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingbo 315201China Key Laboratory of Experimental Teratology Shandong University Jinan 250061 China Department of Chemistry and Bioscience Aalborg UniversityAalborg 9220Denmark Department of Materials Engineering Federal University of Sao CarlosSao Carlos SP 13.565-905Brazil

There is a lack of understanding of both the conversion of an unstable glass into a metastable supercooled liquid(MSL) upon heating and the metastability of MSLs. In this study, we investigated the time-and temperature-dependent metastability of an MSL using an advanced nano-calorimetric technique. The chosen Au-based metallic glass(Au MG) allowed adequate probing of its MSL in a temperature range between 10 and 70 K above the standard glass transition temperature. We found that the survival time of the MSL state is a quadratic function of temperature. Beyond this duration threshold, the sample undergoes fast crystallization even if it is below the crystallization temperature that is measured using differential scanning calorimetry.Employing transmission electron microscopy, we observed the formation of clusters with a partially ordered lattice structure during relaxation in the Au MG sample fabricated using a nano-calorimeter. The atomic ordering within the clusters was enhanced by increasing time and temperature in the MSL region. Once the as-produced glass entered the MSL stage upon heating followed by a quenching stage at a given rate, the mechanical properties of the quenched glass remained the same regardless of its holding temperature and duration within the MSL region. This work provides insights into the glass-MSL-crystal transformation and offers guidance for designing standard metallic glasses for property characterizations.

关键词： metallic glass supercooled liquid relaxation nucleation nano calorimetric technology

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光量子精密测量研究进展(特邀)

中国激光 2024年第1期51卷 354-368页

作者：王犇张利剑南京大学现代工程与应用科学学院江苏南京210023 智能光传感与调控技术教育部重点实验室江苏南京210023 人工微结构科学与技术协同创新中心江苏南京210023 南京大学固体微结构物理国家重点实验室江苏南京210023

量子精密测量作为当代量子力学的主要应用方面之一,近些年来一直是量子科技的重要研究和发展方向。量子精密测量的主要研究目标是针对物理系统中的未知参数,利用量子资源进行量子增强测量,以提升参数测量精度。与其他物理系统相比,光子... 详细信息

量子精密测量作为当代量子力学的主要应用方面之一,近些年来一直是量子科技的重要研究和发展方向。量子精密测量的主要研究目标是针对物理系统中的未知参数,利用量子资源进行量子增强测量,以提升参数测量精度。与其他物理系统相比,光子系统具有相干时间长、不易受到环境干扰等优越性,因而常被用作量子信息处理的载体。以光子为基础的传感器提升传感精度是光量子精密测量的主要任务。介绍了量子精密测量的一般性原理,给出参数估计的量子极限精度下界。同时,介绍了目前光量子精密测量的理论与实验研究进展以及相应的挑战。

关键词：量子光学量子精密测量参数估计海森堡极限传感

Arabidopsis phytochromes A and B synergistically repress SPA1 under blue light

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Journal of Integrative Plant Biology 2023年第4期65卷 888-894页

作者： Xiaolin Jia Meifang Song Shaoci wang Tong Liu lijian wang Lin Guo Liang Su Yong Shi Xu Zheng Jianping Yang State Key Laboratory of Wheat and Maize Crop Science and Center for Crop Genome EngineeringLongzi Lake CampusCollege of AgronomyHenan Agricultural UniversityZhengzhou 450046China Institute of Radiation Technology Beijing Academy of Science and TechnologyBeijing 100875China Institute of Crop Sciences Chinese Academy of Agricultural SciencesBeijing 100081China Henan Police College Zhengzhou 450046China Beijing Genseed Technology Co. Ltd.Beijing 100080China

In Arabidopsis,although studies have demonstrated that phytochrome A(phyA)and phyB are involved in blue light signaling,how blue light-activated phytochromes modulate the activity of the CONSTITUTIVELY PHOTOMORPHOGENIC1(COP1)-SUPPRESSOR OF PHYA-105(SPA1)E3 complex remains largely unknown.Here,we show that phyA responds to early and weak blue light,whereas phyB responds to sustainable and strong blue light.Activation of both phyA and phyB by blue light inhibits SPA1 activity.Specifically,blue light irradiation promoted the nuclear import of both phytochromes to stimulate their binding to SPA1,abolishing SPA1’s interaction with LONG HYPOCOTYL 5(HY5)to release HY5,which promoted seedling photomorphogenesis.

关键词： Arabidopsis blue light phytochrome SPA1

δ-铁素体对钠冷快堆用316KD奥氏体不锈钢热变形行为和动态再结晶的影响

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金属学报 2024年第3期60卷 367-376页

作者：陈胜虎王琪玉姜海昌戎利建中国科学院金属研究所中国科学院核用结构材料与安全评价重点实验室沈阳110016 中国科学技术大学材料科学与工程学院沈阳110016

奥氏体不锈钢中δ-铁素体的存在显著影响热加工过程中奥氏体晶粒度的控制,造成晶粒不均匀现象,关于δ-铁素体对奥氏体动态再结晶行为的影响机制尚不清楚。本工作利用Gleeble-3800热力模拟试验机在1423 K、0.1 s^(-1)条件下进行了铸态样... 详细信息

奥氏体不锈钢中δ-铁素体的存在显著影响热加工过程中奥氏体晶粒度的控制,造成晶粒不均匀现象,关于δ-铁素体对奥氏体动态再结晶行为的影响机制尚不清楚。本工作利用Gleeble-3800热力模拟试验机在1423 K、0.1 s^(-1)条件下进行了铸态样品和均质化处理态样品的热压缩实验,结合SEM、EBSD和TEM等研究了δ-铁素体对热变形行为和动态再结晶的影响。结果表明:1473 K均质化处理14 h可基本消除δ-铁素体,同时伴随着奥氏体晶粒的显著长大,计算表明δ-铁素体向奥氏体的转变速率主要受控于Cr在奥氏体中的扩散。铸态样品变形过程中,δ-铁素体内部、δ-铁素体/奥氏体界面处的塑性变形先于奥氏体相,高温下较软δ-铁素体的存在,造成铸态样品的流变应力明显低于均质化处理态无δ-铁素体样品。随着变形的进行,δ-铁素体易发生动态回复,动态回复引起的软化导致流变应力显著下降。均质化处理态样品的动态再结晶机制是原始奥氏体晶界弓出形核的不连续动态再结晶。而δ-铁素体的存在促进了δ-铁素体/奥氏体界面附近奥氏体的动态再结晶,其机制为连续动态再结晶。铸态样品中的原始奥氏体晶界为不连续动态再结晶的形核位置,2种动态再结晶机制的耦合作用使得铸态样品的动态再结晶程度显著高于均质化处理态样品。

关键词：奥氏体不锈钢 δ-铁素体均质化处理热变形动态再结晶

Maize cryptochromes 1a1 and 1a2 promote seedling photomorphogenesis and shade resistance in Zea mays and Arabidopsis

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The Crop Journal 2023年第4期11卷 1192-1203页

作者： Xiaocong Fan Shizhan Chen Wenjing Wu Meifang Song Guanghua Sun Shuaitao Yao Weimin Zhan Lei Yan Hongdan Li Yanpei Zhang lijian wang Kang Zhang Liangliang Jiang Jianping Yang Qinghua Yang College of Agronomy State Key Laboratory of Wheat and Maize Crop Scienceand Center for Crop Genome EngineeringLongzi Lake CampusHenan Agricultural UniversityZhengzhou 450046HenanChina Institute of Radiation Technology Beijing Academy of Science and TechnologyBeijing 100875China Institute of Crops Jiangxi Academy of Agricultural SciencesNanchang 330200JiangxiChina Institute of Crop Sciences Chinese Academy of Agricultural SciencesBeijing 100081China Genovo Biotechnology Co. Ltd.Tianjin 301700China Henan Institute of Science and Technology Xinxiang 453003HenanChina

Maize growth and development are regulated by light quality,intensity and photoperiod.Cryptochromes are blue/ultraviolet-A light receptors involved in stem elongation,shade avoidance,and photoperiodic flowering.To investigate the function of cryptochrome 1(CRY1) in maize,where it is encoded by Zm CRY1,we obtained two Zm CRY1a genes(Zm CRY1a1 and Zm CRY1a2),both of which share the highest similarity with other gramineous plants,in particular rice CRY1a by phylogenetic analysis.In Arabidopsis,overexpression of Zm CRY1a genes promoted seedling de-etiolation under blue and white light,resulting in dwarfing of mature plants.In seedlings of the maize inbred line Zong 31(Zm CRY1aOE),overexpression of Zm CRY1a genes caused a reduction in the mesocotyl and first leaf sheath lengths due to down-regulation of genes influencing cell elongation.In mature transgenic maize plants,plant height,ear height,and internode length decreased in response to overexpression of Zm CRY1a genes.Expression of Zm CRY1a were insensitive to low blue light(LBL)-induced shade avoidance syndrome(SAS) in Arabidopsis and maize.This prompted us to investigate the regulatory role of the gibberellin and auxin metabolic pathways in the response of Zm CRY1a genes to LBL treatment.We confirmed a link between Zm CRY1a expression and hormonal influence on the growth and development of maize under LBL-induced SAS.These results reveal that Zm CRY1a has a relatively conservative function in regulating maize photomorphogenesis and may guide new strategies for breeding high density-tolerant maize cultivars.

关键词： Zea mays L.Cryptochrome Photomorphogenesis Shade avoidance syndrome Hormone

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分配特殊群桩空间作用效应的双向m法

岩土工程学报 2024年第6期46卷 1197-1205页

作者：廖立坚苏伟杨新安王雨权中国铁路设计集团有限公司天津300308 同济大学交通运输工程学院上海201804

群桩到单桩的作用分配是桩基计算的关键问题,针对规范中的单向m法只适用于平面作用的局限性,从单桩刚度、群桩刚度、受力平衡方程3个层面进行公式推导,建立了变形协调的群桩刚度矩阵和空间受力平衡方程,形成了适用于空间作用的双向m法,... 详细信息

群桩到单桩的作用分配是桩基计算的关键问题,针对规范中的单向m法只适用于平面作用的局限性,从单桩刚度、群桩刚度、受力平衡方程3个层面进行公式推导,建立了变形协调的群桩刚度矩阵和空间受力平衡方程,形成了适用于空间作用的双向m法,并以对称等长直桩、双向斜桩、不对称桩为计算实例,对比分析了单向m法和双向m法的计算结果。结果表明:单向m法计算对称等长直桩时,结果准确,计算双向斜桩时,单桩的弯矩和剪力波动较大,最大值偏小20%左右,计算不对称桩时,单桩外力之和与总外力不闭合,可信度低;而双向m法的理论解可覆盖这些桩基类型,结果更接近有限元数值解。研究成果为特殊桩基提供了一种快速且简便的计算方法,扩展了公路和铁路桥梁桩基设计规范的适用范围。

关键词：群桩作用分配空间作用 m法双向斜桩不对称桩

一次复杂地形下边界层抬升型暖区暴雨对流触发条件和可预报性的数值研究

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大气科学 2024年第3期48卷 1095-1112页

作者：徐渊闵锦忠庄潇然王霄朱利剑江西省气象台南昌330096 南京信息工程大学气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心南京210044 江苏省气象台南京210008 凉山州气象局四川省凉山州615000 中国气象局上海台风研究所上海200030

长江中下游地区的暖区暴雨过程易受复杂下垫面强迫的影响,具有较大的预报不确定性,尤其是其中的对流触发过程。为探讨此类过程的触发条件及揭示其可预报性受限制程度,本文针对2020年6月23日一次复杂地形包裹下的长江中下游暖区暴雨展开... 详细信息

长江中下游地区的暖区暴雨过程易受复杂下垫面强迫的影响,具有较大的预报不确定性,尤其是其中的对流触发过程。为探讨此类过程的触发条件及揭示其可预报性受限制程度,本文针对2020年6月23日一次复杂地形包裹下的长江中下游暖区暴雨展开高分辨率的数值模拟和对流尺度集合模拟,通过Lagrange气块后向轨迹分析、去除地形和关闭热效应的敏感性试验以及集合敏感性分析等方法对此次过程的对流触发阶段展开分析。结果表明,此次过程被抬升气块的主要源地为1.5 km以下的边界层,仙霞岭和杉岭在正午时分因热力作用而驱动的出谷风是引发局地辐合抬升的动力源,高低层散度、湿位涡的垂直配置以及偶极型位涡异常对此次对流触发过程具有较好的指示意义。此外,该过程对前期近地面2 m高度处温度和模式底层视热源具有较高的敏感性,该结果证实下垫面强迫的精确刻画对于提升暖区暴雨的预报效果至关重要。逐步减小初始场误差的初值敏感性试验进一步表明,此次暖区对流过程的可预报性显著低于北边的锋面过程,表现为锋面对流的偏差总能量能随初始误差的缩小持续性降低,而暖区对流的偏差总能量曲线则仍能增长至与原水平相近,呈现出非线性辐合收缩特征。因此,对于天气尺度强迫显著的锋面对流,或可优先考虑通过加强资料同化能力等手段降低初始场误差来减小预报误差;但对于复杂地形下的暖区暴雨对流触发过程,则需要更加强调通过集合预报来捕捉其不确定性。

关键词：暖区暴雨对流触发复杂地形对流尺度集合模拟可预报性

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复杂地质条件下铁路桥梁桩基通用计算方法

中国铁道科学 2024年第2期45卷 72-80页

作者：廖立坚苏伟杨新安王雨权李黎中国铁路设计集团有限公司天津300308 同济大学交通运输工程学院上海201804 中铁第六勘察设计院集团有限公司天津300308

为保障复杂地质环境中铁路桥梁桩基础的结构安全,进一步提升设计质量,提出一种通用的复杂特殊地质条件下桩基计算方法。选择静水、负摩阻力、膨胀土和地震液化土作为4种基本特殊地质,以桥梁桩基设计规范中的m法和单桩承载力计算式为基础... 详细信息

为保障复杂地质环境中铁路桥梁桩基础的结构安全,进一步提升设计质量,提出一种通用的复杂特殊地质条件下桩基计算方法。选择静水、负摩阻力、膨胀土和地震液化土作为4种基本特殊地质,以桥梁桩基设计规范中的m法和单桩承载力计算式为基础,提出它们各自分别作用时的计算方法和综合作用时的耦合效应算法。结果表明:季节冻结深度线、多年冻土上限深度线、中性点深度线和急剧层深度线可作为冰、液态水、冻土、负摩阻力、膨胀土的分界线;该方法在规范基础上增加的计算步骤、计算参数和外载增量可以移植到桩基通用设计程序中,并适用于任意复杂特殊地质条件计算,可为实现该条件下铁路桥梁桩基安全、高效、精细化的计算提供支持。研究成果应用于铁路桥梁设计中,节省桩长约5%、桩身配筋约4%。

关键词：铁路桥梁复杂地质桩基计算冻土上限耦合效应