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Impact resistance analysis and multi-objective optimization of polyurea-coated auxetic honeycomb sandwich panels

MATERIALS TODAY COMMUNICATIONS 2023年 35卷

作者： He, Qiang li, lizheng Jing, xuwen Jiang, Yonggang Yan, Dejun Jiangsu Univ Sci & Technol Sch Mech Engn Zhenjiang 212000 Peoples R China Cssc Huangpu Wenchong Shipbuilding Co Ltd Guangzhou 510715 Peoples R China

To investigate the protective capacity and mechanism of polyurea-coated auxetic honeycomb sandwich structures under impact loading. The mechanical properties of a sandwich panel under the action of a cylindrical punch is numerically simulated by LS-DYNA. Firstly, the impact of different coating positions on the protective properties of sandwich panels is analyzed and concluded which coating method is most effective. Then, the mechanism of the impact resistance of sandwich panels strengthened by the thickness, grading and orientation of the auxetic honeycomb cores is discussed by outline volume analysis. Finally, a multi-objective optimization of the sandwich panel's internal concave hexagonal structural parameters with the best impact resistance is carried out. It is shown that the coating of polyurea elastomers can effectively increase the impact protection performance of sandwich panels. The best impact resistance is achieved by the back side coated sandwich panel (type B). Increasing the wall thickness of auxetic honeycomb and the thickness of the upper graded honeycomb core can effectively increase the impact resistance of the type B sandwich panel. Optimized type B sandwich panel has a 6.2% reduction in maximum deflection (D) compared to the unoptimized version. The findings of this research provide a reference for the study and design of polyurea-coated sandwich panels.

关键词： Polyurea elastomer Auxetic honeycomb Impact resistance Numerical simulation

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GPT在文本分析中的应用:一个基于Stata的集成命令用法介绍

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数量经济技术经济研究 2024年第5期41卷 197-216页

作者：李春涛闫续文张学人河南大学国际商学院中南财经政法大学金融学院河南豫能控股股份有限公司武汉大学经济与管理学院

数字智能时代,深度挖掘文本数据的价值日益重要,大语言模型的出现为此提供了新的契机。本文在人工智能技术赋能实证研究发展的框架下,首先分析了文献中词典法、文本相似度、监督式机器学习等传统文本分析方法的局限性;其次论述了大语言... 详细信息

数字智能时代,深度挖掘文本数据的价值日益重要,大语言模型的出现为此提供了新的契机。本文在人工智能技术赋能实证研究发展的框架下,首先分析了文献中词典法、文本相似度、监督式机器学习等传统文本分析方法的局限性;其次论述了大语言模型的优势及其对实证研究、特别是文本分析的赋能作用;在此基础上,借助由本文作者编制的Stata命令chatgpt,通过一系列案例展示了GPT在提高文本数据处理效率、优化文本指标刻画能力、增强文本指标衡量精度以及丰富文本指标信息含量上的核心优势。本文认为,大语言模型将极大地释放文本数据价值,在基于文本分析方法的相关实证研究中具有巨大的应用潜力。

关键词：文本分析 GPT 大语言模型自然语言处理文本语调

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Seed biostimulant Bacillus sp. MGW9 improves the salt tolerance of maize during seed germination

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AMB EXPRESS 2021年第1期11卷 74页

作者： li, Heqin Yue, Haiwang li, li liu, Yu Zhang, Haiyan Wang, Jianhua Jiang, xuwen Qingdao Agr Univ Dryland Technol Key Lab Shandong Prov Qingdao 266109 Peoples R China Hebei Acad Agr & Forestry Sci Dryland Farming Inst Hengshui 053000 Peoples R China China Agr Univ Seed Sci & Technol Res Ctr Beijing 100193 Peoples R China

Crop performance is seriously affected by high salt concentrations in soils. To develop improved seed pre-sowing treatment technologies, it is crucial to improve the salt tolerance of seed germination. Here, we isolated and identified the strain Bacillus sp. MGW9 and developed the seed biostimulant MGW9. The effects of seed biopriming with the seed biostimulant MGW9 in maize (Zea mays L.) under saline conditions were studied. The results show that the strain Bacillus sp. MGW9 has characteristics such as salt tolerance, nitrogen fixation, phosphorus dissolution, and indole-3-acetic acid production. Seed biopriming with the seed biostimulant MGW9 enhanced the performance of maize during seed germination under salinity stress, improving the germination energy, germination percentage, shoot/seedling length, primary root length, shoot/seedling fresh weight, shoot/seedling dry weight, root fresh weight and root dry weight. Seed biostimulant MGW9 biopriming also alleviated the salinity damage to maize by improving the relative water content, chlorophyll content, proline content, soluble sugar content, root activity, and activities of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase, while decreasing the malondialdehyde content. In particular, the field seedling emergence of maize seeds in saline-alkali soil can be improved by biopriming with the seed biostimulant MGW9. Therefore, maize seed biopriming with the seed biostimulant MGW9 could be an effective approach to overcoming the inhibitory effects of salinity stress and promoting seed germination and seedling growth.

关键词： Salt stress Seed biostimulant Seed germination Zea mays Bacillus sp

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岩浆-热液成矿系统中铁同位素地球化学研究现状

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矿床地质 2023年第6期42卷 1214-1228页

作者：王续文李宇轩安芳大陆动力学国家重点实验室西北大学地质学系陕西西安710069

铁元素是岩浆-热液成矿系统中参与成矿的重要金属元素之一,岩浆-热液矿床中富铁矿物(黄铁矿、磁铁矿、黄铜矿、磁黄铁矿、斑铜矿、毒砂、菱铁矿)的δ^(56)Fe值变化较大(-2.07‰~+1.58‰),指示铁同位素在岩浆演化、流体出溶和热液演化过... 详细信息

铁元素是岩浆-热液成矿系统中参与成矿的重要金属元素之一,岩浆-热液矿床中富铁矿物(黄铁矿、磁铁矿、黄铜矿、磁黄铁矿、斑铜矿、毒砂、菱铁矿)的δ^(56)Fe值变化较大(-2.07‰~+1.58‰),指示铁同位素在岩浆演化、流体出溶和热液演化过程中均存在明显的分馏,因此,在约束岩浆-热液成矿系统中成矿金属的迁移-富集-沉淀过程和示踪成矿物质来源方面具有巨大的应用潜力。通过整理和分析前人研究资料,文章总结了岩浆-热液成矿系统岩浆演化、流体出溶和热液演化过程中铁同位素地球化学行为的研究现状。岩浆演化过程中铁同位素会发生显著分馏,如部分熔融过程中,熔体相比残余固相富集重铁同位素;矿物分离结晶会引起残余熔体铁同位素组成的变化,主要受含Fe2+或Fe3+矿物结晶的影响,如磁铁矿分离结晶会导致残余熔体铁同位素组成变轻,总体反映岩浆氧化还原状态对铁同位素分馏的主要控制作用,因此,含矿岩体铁同位素组成及其变化可用于确定岩浆的氧化还原状态。流体出溶是含矿岩浆演化成为岩浆热液矿床的关键过程,出溶流体相对于母岩富集轻铁同位素,但实验研究表明出溶流体铁同位素组成可能受其中铁的迁移形式、与流体平衡的含Fe2+或Fe3+矿物的比例、相分离和流体混合等多种因素影响。热液演化过程中,含铁热液矿物沉淀会引起流体铁同位素组成的变化,磁铁矿沉淀会导致流体富集轻铁同位素,而含铁硫化物(如磁黄铁矿)沉淀则会使得流体逐渐富集重铁同位素,显示热液流体氧化还原状态对铁同位素分馏的控制作用。由于黄铜矿被认为可以有效记录流体的铁同位素组成,其铁同位素值被用于区分热液流体氧化还原状态。铁元素作为岩浆-热液成矿系统中直接参与成矿的元素,为直接示踪成矿物质来源提供了可能性,然而,岩浆演化、流体出溶和热液演化过程中铁同位素的明显分馏,导致利用铁同位素示踪成矿物质来源的特殊性。进一步明确流体出溶、热液演化等地质过程中的分馏规律,是利用铁同位素示踪成矿物质来源的关键。

关键词： Fe同位素岩浆-热液成矿系统地球化学行为应用研究现状

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A general method for instantaneous undeformed chip thickness calculation in five-axis milling based on Boolean operations

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2021年第7-8期116卷 2325-2334页

作者： li, Guochao liu, Yunlong Zhao, Donghao Dai, Lei Zhou, Honggen Jing, xuwen Jiangsu Univ Sci & Technol Sch Mech Engn Zhenjiang 212003 Jiangsu Peoples R China Jiangsu Univ Sci & Technol Jiangsu Prov Key Lab Adv Mfg Marine Mech Equipmen Zhenjiang 212003 Jiangsu Peoples R China

Instantaneous undeformed chip thickness (IUCT) plays a critical role in optimizing and monitoring of five-axis milling processes, as it determines machining precision and tool life by affecting cutting forces. Analytical and numerical methods have been widely used for IUCT calculation. However, these methods have some deficiencies, such as solving the unsolvable transcendental equations, modeling the complex cutting edge trajectory, and poor adaptability for five-axis milling. Therefore, a Boolean method which consists of subtraction and intersection operations is developed. First, the blank for the current cutting edge is obtained by the Boolean subtraction operation between the workpiece and the swept volume that produced by the front cutting edges. Second, the Boolean intersection operation is executed between the blank and the auxiliary edge entity (AEE) that corresponding to the tool edge. Then, the IUCT of each cutting edge or each cutting point can be deduced based on the Boolean result with the known blank geometry, tool geometry, tool path, and machining parameters. The method is verified by milling force experiments. It is an efficient, accurate, and general method because it does not need to establish complex mathematical or numerical models. The calculated IUCT will promote the optimizing and monitoring of five-axis milling processes.

关键词： Chip thickness Boolean operation Five-axis milling Milling force

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Combined Separated Oscillatory Fields Technique

Combined Separated Oscillatory Fields Technique

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European Frequency and Time Forum (EFTF)

作者： Fuyu Sun Chao li xuwen Hu Shougang Zhang National Time Service Center Chinese Academy of Sciences Xi'an China Key Laboratory of Time Reference and Applications Chinese Academy of Sciences Xi'an China

ISBN: (数字)9798350354270

ISBN: (纸本)9798350354287

Ramsey's method of separated oscillatory fields (SOFs) has been originally used in beam magnetic resonance apparatuses, which leads to the establishment of atomic definition of time interval and frequency. Since then, various versions of the SOFs technique have been widely used for precise measurement of different physical quantities. Here, we present an alternative method to generate atomic beam magnetic resonance signals by combining two Ramsey cavities with phase differences of 0 and 1t. It is found that the strength of the resonance signals generated using this combined SOFs technique is approximately twice that of the resonance signals produced by the conventional SOFs techniques. In addition to generating stronger resonance, the combined Ramsey method eliminates the Rabi background superimposed on the Ramsey interference pattern without increasing the Ramsey signal linewidth. Thus, this technique serves a promising tool for high-precision measurements.

关键词： Atomic measurements Time-frequency analysis Magnetic field measurement Atomic beams Magnetic resonance Europe Interference

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Pilot-scale catalytic ozonation pretreatment for improving the biodegradability of fixed-bed coal gasification wastewater

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PROCESS SAFETY AND ENVIRONMENTAL PROTECTION 2021年 148卷 13-19页

作者： Chen, Xiaoya Wang, Chunrong Jiang, Longxin li, Haiyan Wang, Jianbing He, xuwen China Univ Min & Technol Beijing Sch Chem & Environm Engn Beijing 100083 Peoples R China

Achieving zero liquid dischargeis a requirement for the development of the coal chemical industry;high pollutant concentration, strong biotoxicity, and poor biodegradability (BOD5/COD=0.1-0.2) make fixed-bed coal gasification wastewater difficult to treat. This study synthesized a Fe-Mn/lava catalyst (FMLC) and performed a pilot-scale test on catalytic ozonation for the pretreatment of fixed-bed coal gasification wastewater. The effects of ozone and catalyst dosages were investigated, and the changes in the organics, biotoxicity, and biodegradability of wastewater were analyzed using three-dimensional fluorescence spectroscopy, BOD5/COD, and specific oxygen uptake rate (SOUR). Energy consumption was also calculated. The removal efficiencies (at a flow rate of 1.0 m(3)/h, ozone dosage of 179 g/h, and catalyst dosage of 40 kg/m(3)) of COD and BOD5 were 61.77% and 16.98%, respectively, after 30 days of continuous operation. Toxic refractory macromolecular organic pollutants were transformed into small, biodegradable substances. BOD5/COD increased from 0.16 to 0.35, and SOUR decreased from 2.8460 to 2.3180 mgO(2)/(gMLSS.h). The operating cost was 1.24 kWh/kg COD. Catalytic ozonation as a pretreatment technology markedly improved biodegradability, reduced biotoxicity, and looks to be promising for treating fixed-bed coal gasification wastewater. (C) 2020 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.

关键词： Fixed-bed coal gasification wastewater Pilot-scale Catalytic ozonation Fe-Mn/lava catalyst Pretreatment Biodegradability

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诉讼威慑与公司治理优化——基于康美药业集体诉讼的事件研究证据

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北京工商大学学报（社会科学版） 2024年第4期39卷 129-142页

作者：李春涛闫续文宋敏河南大学国际商学院河南开封475001 中南财经政法大学金融学院湖北武汉430073 武汉大学经济与管理学院湖北武汉430072

股东的权利,从享有公司收益、参与重大决策,到提起诉讼要求损害赔偿,被广泛认为是一个经济体中有效配置资本的重要影响因素。康美药业案作为中国第一起实质性集体诉讼,其判决结果深刻影响了资本市场主体的行为。采用事件研究法,以2018—... 详细信息

股东的权利,从享有公司收益、参与重大决策,到提起诉讼要求损害赔偿,被广泛认为是一个经济体中有效配置资本的重要影响因素。康美药业案作为中国第一起实质性集体诉讼,其判决结果深刻影响了资本市场主体的行为。采用事件研究法,以2018—2022年中国A股上市公司为样本,检验了2021年11月12日康美药业证券虚假陈述集体诉讼案一审判决所带来的强化股东保护的公司治理效应。结果发现,盈余管理程度高、被交易所问询多以及存在关联交易的企业,在康美药业案一审判决前后的市场反应更差。此外,相较于其他重要事件日,一审判决对潜在违规企业的威慑更为明显,且威慑效应具有持续性,公司更倾向于守法经营,带来公司治理的优化。为保障中小股东的合法权益,建议政府进一步降低集体诉讼门槛和维权成本,为投资者提供便捷有效的诉讼维权渠道;上市公司增强财务信息质量和透明度,守法经营,依法披露,提升内部治理水平。

关键词：康美药业盈余管理问询函关联交易事件研究集体诉讼

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广州从化南平村风水林植物群落学特征及规划建议

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南方林业科学 2019年第1期47卷 49-54页

作者：李磊李许文倪建中代色平乳源瑶族自治县林业局广东乳源512700 广州市林业和园林科学研究院广东广州510405 广州市景观建筑重点实验室广东广州510405

采用现场全面踏查和样地调查相结合的方法,研究了广东省广州市从化区南平村风水林植物群落特征。在3个面积为400 m2的调查样方中,共记录植物134种(包括种下单位),隶属于77科114属。植物种类丰富,以大戟科、桑科、壳斗科和紫金牛科植物... 详细信息

采用现场全面踏查和样地调查相结合的方法,研究了广东省广州市从化区南平村风水林植物群落特征。在3个面积为400 m2的调查样方中,共记录植物134种(包括种下单位),隶属于77科114属。植物种类丰富,以大戟科、桑科、壳斗科和紫金牛科植物占优势。该群落具有南亚热带常绿阔叶林的典型群落结构,垂直结构分层明显,层次清晰。400 m2样地面积内,乔灌木群落的Shannon-Winner指数都在2.7以上,Simpson多样性指数在0.8以上,群落均匀度在2.0以上。该样地生物多样性的各项指标远远大于本地的一些风水林。研究成果对广州从化乡村绿化美化建设、风水林的保护、生态公益林造林、园林开发应用具有参考价值。

关键词：风水林树种组成群落结构物种丰富度规划建议广州

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Analysis and Design of Adversarial Virtual Simulation Training System 21

Analysis and Design of Adversarial Virtual Simulation Traini...

引用

13th International Conference on Computer Modeling and Simulation, ICCMS 2021

作者： Sun, xuwen li, Shixiong Xing, Yu Dalian Naval Academy China China Coast Guard Academy China

ISBN: (纸本)9781450389792

In order to improve the high degree of close to training reality for college teaching and training, an antagonistic virtual simulation training system is constructed by analyzing and designing. First, the basic process of antagonistic training is analyzed for preparation, training implantation, and training evaluation, then the process is modeled, and modeled. And then, functional requirements of adversarial virtual simulation training is analyzed and studied, after which, the technical architecture is designed, and core technique is discussed. The study lays a foundation for the design and implementation of the antagonistic virtual simulation training system in future. © 2021 ACM.

关键词： E-learning

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