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基于S-XGBoost融合模型的中国进境快件风险水平评价研究 被引量:2
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作者 刘昌伟 谢晶 +2 位作者 邹廉青 梅云鹏 kashif abbass 《海关与经贸研究》 2024年第1期48-61,共14页
党的二十大报告指出要增强维护国家安全能力,推进国家安全体系和能力现代化,坚决维护国家安全和社会稳定。随着互联网产业的发展壮大,以进境快件为代表的跨境个人消费进入发展的快车道,随之而来的安全准入风险也越来越高。为深入推进智... 党的二十大报告指出要增强维护国家安全能力,推进国家安全体系和能力现代化,坚决维护国家安全和社会稳定。随着互联网产业的发展壮大,以进境快件为代表的跨境个人消费进入发展的快车道,随之而来的安全准入风险也越来越高。为深入推进智慧海关建设,进一步提升进境快件风险防控能力,文章分析了现行监管模式下进境快件存在的问题,运用XGBoost算法和SMOTE技术构建了S-XGBoost进境快件风险评估模型,并对历史通关数据进行了仿真布控和评估。研究结果表明本文提出的S-XGBoost算法模型具有较好的预测效果,风险预测准确率达到了99.06%,能够为海关工作人员提升进境快件布控有效率提出切实参考建议。 展开更多
关键词 数据挖掘 中国进境快件 S-XGBoost 风险水平
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Do US states’responses to COVID-19 restore investor sentiment?Evidence from S&P 500 financial institutions
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作者 Kaouther Chebbi Aymen Ammari +1 位作者 Seyed Alireza Athari kashif abbass 《Financial Innovation》 2024年第1期1996-2016,共21页
This paper specifically investigates the effects of US government emergency actions on the investor sentiment–financial institution stock returns relationship.Despite attempts by many studies,the literature still pro... This paper specifically investigates the effects of US government emergency actions on the investor sentiment–financial institution stock returns relationship.Despite attempts by many studies,the literature still provides no answers concerning this nexus.Using a new firm-specific Twitter investor sentiment(TS)metric and performing a panel smooth transition regression for daily data on 66 S&P 500 financial institutions from January 1 to December 31,2020,we find that TS acts asymmetrically,nonlinearly,and time varyingly according to the pandemic situation and US states’responses to COVID-19.In other words,we uncover the nexus between TS and financial institution stock returns and determine that it changes with US states’reactions to COVID-19.With a permissive government response(the first regime),TS does not impact financial institution stock returns;however,when moving to a strict government response(the overall government response index exceeds the 63.59 threshold),this positive effect becomes significant in the second regime.Moreover,the results show that the slope of the transition function is high,indicating an abrupt rather than a smooth transition between the first and second regimes.The results are robust and have important policy implications for policymakers,investment analysts,and portfolio managers. 展开更多
关键词 COVID-19 Financial institution stock returns Investor sentiment US states responses
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