危化品储运的数字孪生系统设计

数字孪生技术近年来取得了长足的发展，其凭借对真实场景的细粒度与动态性模拟，已经广泛应用于智能建造、智慧交通、航空航天等领域。危化品的储运一直是事故的重点多发环节，然而数字孪生技术在这一领域的应用仍然较少。基于数字孪生的技术特点，首先分析数字孪生当前的技术核心与实现方式，然后阐述危化品储运数字孪生系统的基本功能，设计系统的基本架构，最后以天然气接收站为例，展示数字孪生技术在LPG槽车装卸与运输过程中的应用前景。分析表明，以数字孪生技术为底座，依托传感器获取的多源数据流，在应用层衍生满足用户需要功能的设计，能够为实现危化品储运“主动安全”提供一定技术保障。     

Valuation with share repurchases and personal taxes

We derive a consistent valuation approach that integrates the interdependent effects of cash dividends, share repurchases and active debt management while considering personal taxes. The valuation approach is based on the assumption that a predetermined proportion of the flow to equity is used for share repurchases instead of cash dividends. Additionally, we examine the effects of share repurchases on the cost of equity by deriving appropriate adjustment formulae. Furthermore, we run simulations to investigate the valuation differences caused by the distribution of excess cash via cash dividends or share repurchases. The results show that share repurchases have a significant positive effect on equity market value.     

反隐身预警雷达的发展动态与新技术

预警雷达一直是战场防空和国土防御的基本装备之一，而隐身飞行器的出现迫使现代预警雷达必须提高其反隐身能力。首先从雷达的工作频率、目标的极化信息和非后向散射特性剖析了现代预警雷达的反隐身关键技术，然后根据不同的雷达体制对典型反隐身预警雷达进行分类综述，最后总结了多输入多输出、低截获概率、太赫兹超宽带、微波光子相控阵、第三代半导体和基于数学模型的网络优化等新技术的特点和难点，并展望了反隐身预警雷达需进一步研究的方向，以期为反隐身预警雷达相关设计人员提供一定的帮助和参考。     

Human Factors Programs within Contra Costa County

Starting in 1999, regulated industrial facilities in Contra Costa County, California were required to develop Human Factors Programs as part of the Industrial Safety Ordinance (ISO). Human Factors Programs within the County are designed to be a thorough assessment of the interactions between equipment, work processes, procedures, practices, work environment, people, and management systems as they relate to health and safety. Committees were established at each facility to oversee the development, training, and execution of the site-specific programs. Primary areas of focus in the ongoing implementation of an effective Human Factors Program are periodic assessments and resolution of Latent Conditions, and performance of Management of Organizational Change Assessments before staffing changes. This article describes the steps that facilities in Contra Costa County have taken to develop comprehensive site specific Human Factors Programs. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2009     

社会保障支出、地区差异与积极老龄化

积极老龄化作为应对老龄化挑战的一种有效手段,能提高老年人的晚年生活质量,充分发挥老年人的“余热”,然而现有研究在一定程度上缺乏对积极老龄化前因变量的深入探索。文章构建了老年群体的社会保障支出影响社会参与意识形成及其转化为社会参与行为的理论框架,并用泰尔指数解析社会保障支出对积极老龄化的省际影响和区域影响,以捕捉积极老龄化的客观和主观条件。运用中国动态劳动力调查(CLDS)和2017年《中国统计年鉴》数据进行的实证研究表明:人均社会保障支出对积极老龄化的发展具有显著负向影响;社会保障支出水平对积极老龄化的发展产生显著正向影响;老年人的人力资本、工作经历和健康持久性在人均社会保障支出与积极老龄化之间存在显著调节效应;东中西三大经济带的社会保障支出差异对积极老龄化的影响不显著,但相邻省份的社会保障支出差异对积极老龄化具有显著负向影响。