检索结果-南通市图书馆

Predictability of the 7·20 extreme rainstorm in Zhengzhou in stochastic kinetic-energy backscatter ensembles

Science China Earth Sciences 2024年第7期67卷 2226-2241页

作者： Min YANG peilong YU Lifeng ZHANG Xiaobing PAN Quanjia ZHONG Yunying LI College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China Key Laboratory of High Impact Weather(Special) China Meteorological AdministrationChangsha 410073China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment ChangeNanjing University of Information Science and TechnologyNanjing 210044China Department of Ocean Science Hong Kong University of Science and TechnologyHong Kong 999077China

The scale-dependent predictability of the devastating 7·20 extreme rainstorm in Zhengzhou,China in 2021 was investigated via ensemble experiments,which were perturbed on different scales using the stochastic kinetic-energy backscatter(SKEB)scheme in the WRF model,with the innermost domain having a 3-km grid spacing.The daily rainfall(RAIN24h)and the cloudburst during 1600-1700 LST(RAIN1h)were considered.Results demonstrated that with larger perturbation scales,the ensemble spread for the rainfall maximum widens and rainfall forecasts become closer to the observations.In ensembles with mesoscale or convective-scale perturbations,RAIN1h loses predictability at scales smaller than 20 km and RAIN24h is predictable for all scales.Whereas in ensembles with synoptic-scale perturbations,the largest scale of predictability loss extends to 60 km for both RAIN1h and RAIN24h.Moreover,the average positional error in forecasting the heaviest rainfall for RAIN24h(RAIN1h)was 400 km(50-60)km.The southerly low-level jet near Zhengzhou was assumed to be directly responsible for the forecast uncertainty of RAIN1h.The rapid intensification in low-level cyclonic vorticity,mid-level divergence,and upward motion concomitant with the jet dynamically facilitated the cloudburst.Further analysis of the divergent,rotational and vertical kinetic spectra and the corresponding error spectra showed that the error kinetic energy at smaller scales grows faster than that at larger scales and saturates more quickly in all experiments.Larger-scale perturbations not only boost larger-scale error growth but are also conducive to error growth at all scales through a downscale cascade,which indicates that improving the accuracy of larger-scale flow forecast may discernibly contributes to the forecast of cloudburst intensity and position.

关键词： Stochastic kinetic-energy backscatter(SKEB) Extreme rainfall Ensemble forecast Predictability

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Lactiplantibacillus plantarum FRT4 attenuates high-energy low-protein dietinduced fatty liver hemorrhage syndrome in laying hens through regulating gut-liver axis

引用

Journal of Animal Science and Biotechnology 2024年第3期15卷 1292-1311页

作者： Daojie Li Hongying Cai Guohua Liu Yunsheng Han Kai Qiu Weiwei Liu Kun Meng peilong Yang Key Laboratory of Feed Biotechnology of Ministry of Agriculture and Rural Affairs Institute of Feed ResearchChinese Academy of Agricultural SciencesBeijing 100081China National Engineering Research Center of Biological Feed Beijing 100081China

Background Fatty liver hemorrhage syndrome(FLHS)becomes one of the most major factors resulting in the laying hen death for caged egg production.This study aimed to investigate the therapeutic effects of Lactiplantibacillus plan-tarum(Lp.plantarum)FRT4 on FLHS model in laying hen with a focus on liver lipid metabolism,and gut microbiota.Results The FLHS model of laying hens was established by feeding a high-energy low-protein(HELP)diet,and the treatment groups were fed a HELP diet supplemented with differential proportions of Lp.plantarum FRT4.The results indicated that Lp.plantarum FRT4 increased laying rate,and reduced the liver lipid accumulation by regulating lipid metabolism(lipid synthesis and transport)and improving the gut microbiota composition.Moreover,Lp.plan-tarum FRT4 regulated the liver glycerophospholipid metabolism.Meanwhile,“gut-liver”axis analysis showed that there was a correlation between gut microbiota and lipid metabolites.Conclusions The results indicated that Lp.plantarum FRT4 improved the laying performance and alleviated FLHS in HELP diet-induced laying hens through regulating“gut-liver”axis.Our findings reveal that glycerophospholipid metabolism could be the underlying mechanism for the anti-FLHS effect of Lp.plantarum FRT4 and for future use of Lp.plantarum FRT4 as an excellent additive for the prevention and mitigation of FLHS in laying hens.

关键词： Fatty liver hemorrhage syndrome Gut microbiota Lactiplantibacillus plantarum FRT4 Laying hens Lipid metabolism

来源：

维普期刊数据库博看期刊

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Oxygenic iron clusters in ZSM-5 zeolite promote quantum sieving of gaseous hydrogen isotopes

引用

Science China Chemistry 2024年第4期67卷 1242-1249页

作者： Jingjing Zhang Yongyan Deng Dongxu Gai Yang Shi Xingwen Feng peilong Li Yongtao An Xiaoqin Zou Institute of Materials China Academy of Engineering PhysicsMianyang 621907China Faculty of Chemistry Northeast Normal UniversityChangchun 130024China

Isotopic separation is of paramount importance for producing high-purity heavy hydrogen,yet the process remains hugely challenging.Here,we report on an Fe/ZSM-5 zeolite that was able to efficiently separate deuterium from protium via chemical quantum sieving.Structural data showed that four types of Fe species were present in Fe/ZSM-5 and oligomeric Fe-O clusters in the zeolite pores were correlated directly with gas selectivity.Gas adsorption revealed that Fe-O species served as the main adsorption sites and interacted with D_(2) more strongly than with H_(2).D_(2)/H_(2)separation was exemplified using thermal desorption spectroscopy.D_(2)/H_(2) selectivity increased with Fe loading in Fe/ZSM-5 and a selectivity of 32.1 was obtained with an optimal loading of 7 wt%.The shift of desorption temperature supports the chemical affinity-based quantum sieving of D_(2)over H_(2).This study demonstrates an effective strategy for enhancing D_(2)/H_(2) separation and the high selectivity means that Fe/ZSM-5 has strong potential in hydrogen isotope separation.

关键词： iron zeolite hydrogen isotope gas separation quantum sieving thermal desorption

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Enhancing XRF sensor-based sorting of porphyritic copper ore using particle swarm optimization-support vector machine(PSO-SVM)algorithm

引用

International Journal of Mining Science and Technology 2024年第4期34卷 545-556页

作者： Zhengyu Liu Jue Kou Zengxin Yan peilong Wang Chang Liu Chunbao Sun Anlin Shao Bern Klein School of Civil and Resources Engineering University of Science and TechnologyBeijing 100083China Institute of Minerals Research University of Science and TechnologyBeijing 100083China State Key Laboratory of Mineral Processing Beijing 102628China Ansteel Group Mining Co.Ltd. Anshan 114000China Norman B.Keevil Institute of Mining Engineering University of British ColumbiaVancouverBC V6T 1Z4Canada

X-ray fluorescence(XRF)sensor-based ore sorting enables efficient beneficiation of heterogeneous ores,while intraparticle heterogeneity can cause significant grade detection errors,leading to misclassifications and hindering widespread technology adoption.Accurate classification models are crucial to determine if actual grade exceeds the sorting threshold using localized XRF signals.Previous studies mainly used linear regression(LR)algorithms including simple linear regression(SLR),multivariable linear regression(MLR),and multivariable linear regression with interaction(MLRI)but often fell short attaining satisfactory results.This study employed the particle swarm optimization support vector machine(PSO-SVM)algorithm for sorting porphyritic copper ore pebble.Lab-scale results showed PSO-SVM out-performed LR and raw data(RD)models and the significant interaction effects among input features was observed.Despite poor input data quality,PSO-SVM demonstrated exceptional capabilities.Lab-scale sorting achieved 93.0%accuracy,0.24%grade increase,84.94%recovery rate,57.02%discard rate,and a remarkable 39.62 yuan/t net smelter return(NSR)increase compared to no sorting.These improvements were achieved by the PSO-SVM model with optimized input combinations and highest data quality(T=10,T is XRF testing times).The unsuitability of LR methods for XRF sensor-based sorting of investigated sample is illustrated.Input element selection and mineral association analysis elucidate element importance and influence mechanisms.

关键词： XRF sensor-based sorting PSO-SVM algorithm Copper ore pebble Receiver operating curve(ROC) Net smelter return(NSR)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Microstructure and Mechanical Properties of Cu Matrix Composites Reinforced by TiB_(2)/TiN Ceramic Reinforcements

引用

Acta Metallurgica Sinica(English Letters) 2020年第12期33卷 1609-1617页

作者： Jinwei Yin peilong zhou Hanqin Liang Dongxu Yao Yongfeng Xia Kaihui Zuo YuPing Zeng State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Cu matrix composites reinforced by TiB_(2)/TiN ceramic reinforcements(Cu/TBN composites)were prepared by hot pressing method.Prior to the hot pressing,Cu/TiB_(2)/TiN composite powders(CTBN powders),which were used as the starting materials of Cu/TBN composites,were fabricated by self-propagating high-temperature synthesis method.The CTBN particles were found to be in a special core–shell structure with a Cu–Ti alloy core and a TiB_(2)/TiN ceramic shell.The test results presented obvious improvements in mechanical properties.The highest ultimate tensile strength reached up to 297 MPa,77 MPa higher than that of Cu.And the highest hardness reached up to 70.7 HRF,15.7 HRF higher than that of Cu.A comparative study indicated that the core–shell structured particles could bring about more obvious strengthening eff ect than the traditional irregularly shaped particles,which was due to the improved Cu/ceramics interfacial bonding,the linkage strengthening effect of both TiB_(2) and TiN,and higher load bearing ability of the core–shell structured reinforcements.

关键词： Cu matrix composite Microstructure Mechanical property Self-propagating high-temperature synthesis(SHS)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A cohort study of HIV infection in club drug abusers among men who have sex with men in Qingdao

引用

China Medical Abstracts(Internal Medicine) 2024年第1期41卷 23-24页

作者：李培龙 Div Epidemiol Natl AIDS/STD Contr&Prev CenterChin Dis Contr&Prev CenterBeijing 102206

Objective To understand and analyze the incidence of HIV infection in club drug abusers among men who have sex with men (MSM) in Qingdao and provide a reference for the prevention and intervention of this population.Methods From March 2017 to July 2022,club drug abusers among MSM who were HIV-negative were recruited by snowball sampling of MSM social organizations in Qingdao.

关键词： prevention drug among HIV

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

圆燕尾光束在大气湍流中的传输调控

引用

光学学报 2024年第10期44卷 436-442页

作者：刘娜娜洪佩龙任煜轩梁毅广西大学物理科学与工程技术学院广西南宁530004 安庆师范大学数理学院安徽安庆246133 复旦大学脑科学转化研究院上海200032

光吸收和光散射给大气光通信以及生物活体光操控等应用带来极大的挑战。探索受光散射影响小的光束一直是光场调控研究的难点。本文设计了具有自会聚特性的圆燕尾光束,并研究其在大气湍流中的传输特性。通过分析光束在复杂环境中的畸变... 详细信息

光吸收和光散射给大气光通信以及生物活体光操控等应用带来极大的挑战。探索受光散射影响小的光束一直是光场调控研究的难点。本文设计了具有自会聚特性的圆燕尾光束,并研究其在大气湍流中的传输特性。通过分析光束在复杂环境中的畸变和强度波动发现,在湍流增强时,燕尾光束的传输质量下降,并伴随漂移和闪烁。通过对光束的尺寸因子和初始横向位置进行优化,可以提高其自会聚稳定性。模拟发现,自会聚能力强的圆燕尾光束,在湍流中表现更优越。这些研究显示圆燕尾光束在抗湍流散射方面具有优势,为复杂环境中的光通信、光捕获和光操纵技术提供了重要的选择。

关键词：物理光学圆燕尾光束自会聚大气湍流传输

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

中国金融稳定保障基金最优规模度量和配置研究--基于宏观经济部门非预期损失的分析

引用

金融经济学研究 2024年第1期39卷 126-143页

作者：王晓婷赵铖沈沛龙山西财经大学金融学院

金融稳定保障基金是建设金融强国战略背景下维护和实现金融稳定的重要工具。通过编制2008—2020年中国31个省(区、市)金融部门、政府部门、非金融企业部门和家庭部门宏观或有权益资产负债表,运用宏观在险价值方法度量各地区、各部门资... 详细信息

金融稳定保障基金是建设金融强国战略背景下维护和实现金融稳定的重要工具。通过编制2008—2020年中国31个省(区、市)金融部门、政府部门、非金融企业部门和家庭部门宏观或有权益资产负债表,运用宏观在险价值方法度量各地区、各部门资产和负债市场价值的非预期损失,估算能充分覆盖重大风险敞口的金融稳定保障基金最优规模和配置比例。研究发现,中国金融稳定保障基金的最优相对规模从大到小依次是:政府部门、非金融企业部门、家庭部门和金融部门。其中,非金融企业部门和家庭部门地区间规模差异显著,东部地区相对规模水平较低,西部地区较高。政府部门作为公共部门具有对其他经济主体的隐性担保责任,最终承担其他部门产生但未抵补的金融风险,是金融稳定的“最后一道防线”。为了更好地防范和化解金融风险,维护金融稳定,金融稳定保障基金应当确定风险适配的目标规模,并实现多层级分部门的有效配置,最终形成全方位、多层次的金融稳定保障基金配置体系。

关键词：金融稳定保障基金建设金融强国宏观资产负债表宏观在险价值

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

生物基树脂改性沥青流变特性评价及体系融合行为

引用

材料导报 2024年第2期38卷 269-275页

作者：蒋修明丁湛孙超岳磊栗慧峰栗培龙长安大学公路学院西安710064 长安大学水利与环境学院西安710054 长安大学旱区地下水文与生态效应教育部重点实验室西安710054 长安大学道路结构与材料交通运输行业重点实验室西安710064

受石油资源储量和供应的限制,将生物质材料引入石油沥青已经成为一个热门话题。本研究以麦草秸秆液化产物为原材料合成三种生物基树脂(BPF、BPU和BPF-PU),并将其用于生物沥青的制备,旨在探究生物基树脂对沥青流变特性的影响及二者之间... 详细信息

受石油资源储量和供应的限制,将生物质材料引入石油沥青已经成为一个热门话题。本研究以麦草秸秆液化产物为原材料合成三种生物基树脂(BPF、BPU和BPF-PU),并将其用于生物沥青的制备,旨在探究生物基树脂对沥青流变特性的影响及二者之间的交互作用。首先,通过频率扫描和多重应力蠕变恢复试验分析了树脂对沥青胶结料黏弹特性和高温抗车辙性能的影响;其次,借助流变学理论对树脂-沥青体系的相态结构进行了分析;最后,从荧光显微结构和官能团分布特征的角度探究了二者之间的融合行为。结果表明,BPF和BPF-PU能够增加沥青中的弹性成分,提升其高温抗车辙性能,而BPU则会强化沥青的黏性响应;三种树脂能够较为均匀地分散到基质沥青中,并与其形成稳定的相态结构,这可能是因为树脂与基质沥青之间形成了醚键(C-O-C)。本研究有助于为农作物秸秆的增值转化和生物沥青的开发提供新的思路,但在生物沥青性能的全面评价方面需要进一步研究。

关键词：农作物秸秆生物基树脂生物沥青流变特性融合行为相态结构

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

芳纶纱的结构形貌对芳纶/PTFE织物复合材料摩擦学性能的影响

引用

润滑与密封 2024年第3期49卷 41-48页

作者：蔡明张招柱姜葳李佩隆中国科学院兰州化学物理研究所固体润滑国家重点实验室甘肃兰州730000 中国科学院材料磨损与防护重点实验室甘肃兰州730000

为了研究纱线结构形貌对织物复合材料摩擦学性能的影响,选用对位芳纶纤维,制备成3种具有不同结构形貌的芳纶纱,分别为长丝平行纱、长丝加捻纱和短纤维加捻纱。以相同的制备工艺得到3种芳纶/PTFE织物复合材料,采用多试件摩擦磨损试验机... 详细信息

为了研究纱线结构形貌对织物复合材料摩擦学性能的影响,选用对位芳纶纤维,制备成3种具有不同结构形貌的芳纶纱,分别为长丝平行纱、长丝加捻纱和短纤维加捻纱。以相同的制备工艺得到3种芳纶/PTFE织物复合材料,采用多试件摩擦磨损试验机测试复合材料的摩擦学性能,并对芳纶/PTFE混编织物及相应复合材料的结构形貌、力学性能和磨损表面进行分析与探讨。实验结果表明:芳纶纱的结构形貌可直接影响纱线的断裂强度、纱线拔出强力、纱线与树脂的界面结合力,进而影响织物复合材料的摩擦学性能;在不同的磨损条件下3种混编织物的耐磨性表现有所不同,当载荷相对较低时,芳纶短纤维加捻纱/PTFE织物复合材料磨损率更低,而当载荷较高时,芳纶长丝加捻纱/PTFE织物复合材料耐磨性更好。

关键词： PTFE长丝纱芳纶纱结构形貌摩擦学性能

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：