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1. chinaXiv:202109.00061 [pdf]

生物质废弃电厂稻壳灰混凝土力学及耐久性能量演化研究

姜平伟
Subjects: Civil Engineering and Building Construction >> Building Materials

将生物质发电厂所产废弃稻壳灰代替部分水泥加入到混凝土中,制备出一种新型的电厂稻壳灰(Electric Power Plant-Rice Husk Ash,简称E-RHA)混凝土(E-RHA-C),进行了E-RHA-C力学性能及经历210d Na2SO4侵蚀及105次干湿Na2SO4溶液循环耐久性能试验,结合其宏观力学和物理参数、微观形态对E-RHA增强混凝土力学强度、抗硫酸盐侵蚀能力进行机理分析,并利用能量转化方法对E-RHA-C耐久性进行损伤评价,得到相应的本构模型。结果表明:普通混凝土中掺入适量稻壳灰矿物掺合料,能够有效提高力学性能,但混凝土力学性能增加过程的稳定性逐渐降低。随着硫酸盐龄期增加,E-RHA-C试件逐渐局部剥落、体积膨胀;力学性能、相对动弹性模量先提高后急剧下降,有效孔隙率先降低后提高,E-RHA-C中骨料周围的界面区破坏程度远小于普通混凝土,体现出较好的耐侵蚀性。硫酸盐侵蚀E-RHA-C前期对试件力学性能的增强主要表现在总应变能、耗散能的提升,E-RHA-C塑性及延性变形提高。而在第二阶段,E-RHA-C逐渐体现出峰值应力和延性降低、脆性破坏明显现象。基于统计损伤理论和耗散能,建立了E-RHA-C的耐久性损伤本构模型。

submitted time 2021-09-25 Hits14Downloads3 Comment 0

2. chinaXiv:202109.00060 [pdf]

环境无序性对消费者多样化寻求的影响及作用机制

王艳; 蒋晶
Subjects: Psychology >> Cognitive Psychology

在日常生活和购物环境中,混乱无序无处不在。然而,关于环境无序性对消费者产品选择行为的影响研究却十分有限,本文试图填补这一不足。具体而言,本文创新性地提出环境无序性与多样化寻求行为之间存在着因果关系,且自我效能威胁和未来偏好不确定感在其中发挥链式中介作用。通过1个预实验和4个实验,本文发现无论在真实环境、线下购物环境、工作环境,还是线上产品陈列情境下,环境无序性均可提升多样化寻求行为;无序的环境会对消费者的自我效能产生威胁,进而增强其对未来产品偏好的不确定性感知,最终促使其通过增加多样化寻求行为来应对未来可能变化的产品偏好。

submitted time 2021-09-24 Hits27Downloads8 Comment 0

3. chinaXiv:202109.00059 [pdf]

国内公共图书馆未成年人服务研究的系统评述

卫垌圻; 刘颖
Subjects: Library Science,Information Science >> Readers Work

为了准确把握对我国公共图书馆未成年人服务的研究现状与发展态势,梳理与分析现有研究中存在的不足与缺陷,以便更好地为未来的研究工作提供借鉴参考。通过对公共图书馆领域未成年人服务的中英文研究进行文献检索,将本领域的3224篇论文按照研究方法分为5类,并分别对每一类研究及其子分类进行了系统评述。研究发现,针对未成年人公共图书馆服务的研究主题多样,内容广泛,并契合国家要求与社会需求,关注特殊群体的利益,有自己的研究特色。同时,非实证研究比例较大,有深度和有持续性的研究较少,国际影响力也非常小。未来应该积极借鉴其他社会科学的实证范式,研究本学科的核心问题,将图书馆未成年人服务研究做得更细致、更深入。

submitted time 2021-09-22 Hits116Downloads39 Comment 0

4. chinaXiv:202109.00058 [pdf]

Dating the First Case of COVID-19 Epidemic from a Probabilistic Perspective

Zhouwang Yang; Yunhe Hu; Zhiwei Ding; Tiande Guo
Subjects: Mathematics >> Applied Mathematics

In the early days of the epidemic of coronavirus disease 2019 (COVID-19), due to insufficient knowledge of the pandemic, inadequate nucleic acid tests, lack of timely data reporting, etc., the origin time of the onset of COVID-19 is difficult to determine. Therefore, source tracing is crucial for infectious disease prevention and control. The purpose of this paper is to infer the origin time of pandemic of COVID-19 based on a data and model hybrid driven method. We model the testing positive rate to fit its actual trend, and use the least squares estimation to obtain the optimal model parameters. Further, the kernel density estimation is applied to infer the origin time of pandemic given the specific confidence probability. By selecting 12 representative regions in the United States for analysis, the dates of the first infected case with 50% confidence probability are mostly between August and October 2019, which are earlier than the officially announced date of the first confirmed case in the United States on January 20, 2020. The experimental results indicate that the COVID-19 pandemic in the United States starts to spread around September 2019 with a high confidence probability. In addition, the existing confirmed cases are also used in Wuhan City and Zhejiang Province in China to infer the origin time of COVID-19 and provide the confidence probability. The results show that the spread of COVID-19 pandemic in China is likely to begin in late December 2019.

submitted time 2021-09-22 Hits15979Downloads3842 Comment 0

5. chinaXiv:202109.00057 [pdf]

作业中断对任务绩效的影响及心理疲劳的调节作用

陈悦源; 方卫宁; 郭北苑; 鲍海峰
Subjects: Psychology >> Physiological Psychology

作业中断会对中断后行为绩效产生影响,探讨不同疲劳状态下中断对作业绩效影响的认知机制将有助于完善和发展中断的认知理论。本研究采用事件相关电位(ERP),通过在不同心理疲劳状态下执行数学题任务中断、暂停中断和不中断的空间2-back任务,结合行为数据和ERPs结果,分析作业中断对任务绩效的影响以及心理疲劳在其中的调节作用。实验结果发现,中断后诱发的P200和P300振幅显著提高,作业中断使得主任务的注意力资源下降,任务中断的无关信息干扰了主任务工作记忆,而疲劳状态则进一步加剧了中断对注意资源、工作记忆及行为绩效的负面效应。本研究在揭示作业中断认知过程及疲劳对其影响机理的同时,也支持了中断的目标记忆模型。

submitted time 2021-09-21 Hits367Downloads191 Comment 0

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