偏光显微镜法在空气粉尘中石棉纤维鉴别中的应用

本文采用偏光显微镜法鉴别空气粉尘中的微量石棉纤维。经滤膜收集的粉尘样品通过高温灰化及酸洗过程去除大部分干扰物质,经乙醇分散后均匀沉积在玻璃片上,滴加具有固定折射率的浸油制成试片。在正交偏光系统下观察到粉体中存在纤维状颗粒,且纤维呈现四次平行消光特性,比对6种常见石棉的偏光显微镜图,综合分析试样粉尘的光学性质,推断样品中含有温石棉。     

基于激光点云的高墩垂直度偏差分析方法

现代桥梁工程中高墩桥梁屡见不鲜,桥墩垂直度已成为评定桥墩施工质量的重要指标之一.以新疆某特大桥项目为依托,针对高墩垂直度检测结果实用性低的问题,提出一种采用三维激光扫描技术对高墩垂直度进行非接触测量分析的方法.利用三维激光扫描仪快速获取高墩结构全局点云信息,对桥墩点云进行拼接、降噪等预处理,采用编程算法实现了桥墩节段中心点和垂直度偏差的计算,并得到了垂直度偏差变化规律图.最后将该方法与传统方法进行对比.结果表明:利用三维激光扫描技术对高墩进行快速测量,能够获取桥墩中心轴线的三维空间线型,精确分析并定位最大偏差位置,显著提高垂直度测量结果的实用性,具有良好的工程应用前景,并为后续研究桥墩垂直度问题提供了新思路.     

Relationship Quality as Predictor of B2B Customer Loyalty in the Pharmaceutical Sector: Evidence from Jordan

This article aims to investigate the impactful effect of relationship quality dimensions (i.e., trust, satisfaction, and commitment) on aspects of loyalty represented by attitudinal loyalty and behavioral loyalty. A quantitative survey method was employed to achieve the objectives of the study. Furthermore, a convenience sampling technique was adopted to select a representative sample from physicians working in the public healthcare sector in Jordan. A total of 500 questionnaires were distributed, and 408 questionnaires were used in the statistical analyses. The data were analyzed by applying structural equation modeling to test the study model, and hypotheses were constructed and tested quantitatively and discussed qualitatively. The results revealed that both aspects of customer loyalty (i.e., behavioral and attitudinal) were affected positively by the overall dimensions of relationship quality (i.e., trust, satisfaction, and commitment), providing a recommendation for pharmaceutical companies in Jordan to focus on improving the relationship quality between their medical representatives and physicians due to the importance of such a factor in improving customer loyalty, which will reflect positively in managing their customers effectively and enhancing future business opportunities.     

基于SEM模型的农地规模经营意愿影响因素研究*——以江汉平原潜江市为例

［目的］乡村振兴战略背景下，受规模经营效益的驱动，农地流转和适度规模经营将不断推进，研究农地规模经营意愿的影响因素及贡献率，对进一步扩大农地适度经营规模、发展现代农业和助力乡村振兴具有重要的现实意义。［方法］文章以江汉平原潜江市为研究区，基于176份调查问卷数据，借助结构方程模型，定量诊断影响集约化农区农地规模经营意的愿影响因素及贡献。［结果］影响潜江市农地规模经营意愿的因素主要为生产经营、资源禀赋、流转束缚、环境特征、行为认知5个方面，假设的5个潜在变量路径系数分别为0331、0238、0218、0238、0240，均对农地规模经营意愿影响因素表现出显著的正向影响； 引入模型的19个影响因素中，新技术新用具运用、生产经营面积、地块数量和社会地位认知影响最为显著，而生产经济组织程度、流转租金、农业基础设施等因素的影响相对较小，最后从健全农地流转政策等方面提出了较合理的建议。［结论］研究对系统剖析集约化农区农地规模经营的主要影响因素及贡献、推动新时代下农业供给侧结构性改革对农地规模经营的决策需求具有重要的参考价值。     

基于计划行为理论的农户耕地转入和转出意愿对比研究

［目的］农民耕地原子化程度不断加深，现行的家庭联产承包责任制已不能适应农村商品化和市场化的进程，严重制约了农村地区的经济发展。对山东部分农村地区农户进行耕地转入和转出意愿对比分析，以促进农村地区耕地流转提出可行性的建议，以期加速农村地区市场化进程，实现经济快速发展。［方法］以计划行为理论为基础，文章以行为态度、主观规范、感知行为控制3个潜在变量， 11个可测变量构建农户耕地转出和转入意愿模型，以山东省6个地区549户农户的实地调查数据为样本，利用结构方程模型对农户耕地流转意愿进行实证分析。［结果］行为态度和知觉行为控制对农户耕地转入和转出意愿都具有显著影响，且标准化路径系数都为正； 主观态度对耕地转入意愿具有显著性影响，其标准化路径系数为负，对转出意愿的标准化系数为正； 11个可测变量分别对相应的潜在变量都有显著性影响。［结论］行为态度对农户耕地转入和转出的影响效果不同，转入耕地的农户主要从耕地固有价值出发，而转出耕地的农户主要从经济理性考虑； 主观规范中4个可观测变量对农户耕地转出和转入的影响具有一致性； 知觉行为控制中农户的契约意识对耕地转出重要性大于耕地转入。     

Exogenous shocks and managerial preparedness: A study of U.S. airlines’ environmental scanning before the onset of the COVID-19 pandemic

Managerial preparedness is a constant concern for firm stakeholders. This concern is exacerbated during times of immense stress brought about by exogenous shocks. In this paper, we analyze the preparedness of U.S. commercial airline management teams to the largest systematic exogenous shock to date, namely the COVID-19 pandemic in 2019 and 2020. We do this by underpinning the paper with theory on environmental scanning and managerial dysfunction and then documenting the signals and actions of management around multiple public health scares. These include the SARS outbreak, the Swine Flu outbreak and the COVID-19 outbreak. Our results, based off of corporate filings with the SEC, is that airline management had multiple “dry runs” before the COVID-19 outbreak that should have lead them to prepare for financially catastrophic scenarios such as the one observed in 2020. Instead, management teams failed to learn from these, and other, prior shocks. Instead, they focused on other, less serious threats while diffusing their financial buffers through dividends and share buybacks.     

基于三维激光扫描的钢板组合梁结构检测方法

针对钢结构桥梁的传统尺寸检测工作存在数据获取效率低、实地操作困难和检测精度不高等问题,结合三维激光扫描技术,给出一种基于三维激光点云数据的钢板组合梁构件多部位尺寸无损检测方法.主要步骤包括扫描设计、点云获取、点云预处理及配准、截面获取与尺寸检测.以某高速公路桥梁工程钢板组合梁结构检测为例,分别对比了传统尺寸检测方法和本文方法.实验表明该方法具有无接触测量、高可靠性和检测范围全面的优势.     

新型Ka频段宽角扫描圆极化相控阵天线

提出了一种新型的Ka频段圆极化相控阵天线。天线单元以单馈电开槽贴片天线为基础实现圆极化，通过微带贴片表面加载介质和辅助辐射器，展宽了天线波束宽度并优化了单元轴比。以该天线为阵列单元，采用顺序旋转布阵技术优化得到的2×2子阵，其辐射方向图具有良好的旋转对称性，由该子阵扩展形成的相控阵天线，有效地实现了圆极化宽角扫描特性。以8×8矩形阵列为例，仿真分析了此类二维相控阵天线波束扫描过程中的方向图和极化特性。研究结果表明，天线在工作频段内可实现方位360°、俯仰±60°扫描，扫描范围内天线增益波动和轴比均小于3 dB，同时该天线具有低剖面（高度尺寸为0.08λ0，λ0为空气介质波长）、结构简单、易于加工和集成等特点，非常适合小型化或一体化相控阵天线系统应用。