利用无人机标定雷达精度的新方法

针对现有雷达标定系统存在的使用成本高、组织实施不方便、真值获取手段不可靠等一系列问题,提出了利用搭载“北斗”卫星定位系统的旋翼无人机作为探测目标的三坐标雷达精度标定新方法。设计了基于该方法的三坐标雷达标定系统方案,研究了系统实现所需的关键技术,最后给出了系统样机的试验结果。结果表明,该方法能够真实反映三坐标雷达的系统误差,与传统雷达标定方法相比,更加经济、简便、灵活。     

Sustainable hub location under mixed uncertainty

This paper addresses a novel sustainable hub location problem (SHLP) in which two new environmental-based cost functions accounting for air and noise pollution of vehicles are incorporated. To cope with uncertain data incorporated in the model, a mixed possibilistic–stochastic programming approach is proposed to construct the crisp counterpart. A simulated annealing (SA) and an imperialist competitive algorithm (ICA) with a new solution representation are developed to solve real-sized instances whose performances are compared with a proposed lower bound. Finally, some computational experiments are provided to demonstrate the effectiveness of the proposed model and solution approaches.     

Theoretical,empirical, and operational models in hotel location research

This paper aims to review past literature on hotel location models and evaluate the state of the art, as well as set out future directions. This study divides hotel location models into three major categories: theoretical models, empirical models, and operational models. Four theoretical hotel location models are reviewed and discussed, including the tourist-historic city model, the mono-centric model, the agglomeration model, and the multi-dimensional model. Based on previous literature, six empirical models and three operational models of hotel location are elaborated. Furthermore, some challenges related to hotel location studies are discussed, and future research directions are provided. In particular, we advocate the development of more sophisticated hotel location models and the use of Geographic Information System (GIS) in hotel location analysis.     

What is driving increases in dietary quality in the United States?

Over 1994–2010, adult dietary quality in the United States increased by 10 percent. We find a shift in consumption between at-home and away-from-home food played a relatively minor role as compared to changes in demographics and educational attainment. The two largest contributors we identify include an increased usage of nutritional information and a shift away from relying heavily on price, taste, storability and ease of preparation when shopping for food. Our findings suggest nutrition policy discussions could focus on further shifting attitudes/preferences towards healthier diets while allowing consumers to better extract nutrition information when making food choices.     

福鼎市桐江溪卤乙酸分布特征及潮汐影响分析

为了掌握福鼎市桐江溪卤乙酸(HAAs)的含量、时空分布规律及其来源,对水体中HAAs化合物进行取样调查。根据桐江溪水文情势及沿岸特点设置10个取样点,于2017年12月及2018年7月按照涨潮、退潮情况分别对水样进行采集,检测HAAs分布情况,同时将卤乙酸(HAAs)与水质特性、涨退潮进行了相关性分析。研究发现,HAAs是普遍存在于桐江溪中的污染物质。其中,一氯乙酸(MCAA)、二氯乙酸(DCAA)、三氯乙酸(TCAA)、一溴乙酸(MBAA)、二溴乙酸(DBAA)等5种卤乙酸(HAA_5)质量浓度为0.44～3.39μg/L;一氯乙酸(MCAA)、二氯乙酸(DCAA)、三氯乙酸(TCAA)、一溴乙酸(MBAA)、二溴乙酸(DBAA)、三溴乙酸(TBAA)、一溴一氯乙酸(BCAA)、一溴二氯乙酸(BDCAA)、二溴一氯乙酸(CBDAA)等9种卤乙酸(HAA_9)质量浓度为0.83～56.15μg/L。桐江溪中HAAs主要为DCAA,TCAA,TBAA 3种,其中DCAA为制药厂及医院排水导致,主要分布在下游;TCAA主要来源于河段上游的农业生产活动;TBAA为上游沸石矿尾矿库受雨水冲刷而流入的Br~-所生成,主要分布于河流中下段。相关性分析结果表明,温度与HAA_5,HAA_9质量浓度呈现正相关,pH值与HAA_5,HAA_9质量浓度呈现负相关;TCAA质量浓度于相同季节不同潮汐及不同季节相同潮汐时均呈现上游高于下游的现象,其他HAAs均不因涨潮、退潮的差异造成质量浓度分布的变化。掌握桐江溪HAAs的含量、时空分布规律及来源,探讨其与水质的相关性,对于净水工艺选择、水厂出水HAAs含量的溯源分析、水体环境风险评估以及研究水生生物体内HAAs的累积效应等有重要意义。     

Assessment of Current Training Program and Its Effectiveness in Hotels of Bhutan

The increasing number of tourist in Bhutan demands for more high-quality hotels to provide better services to guests. The objectives of the study are, (1) to assess the current training provided to the hotel employees; (2) to evaluate the training gap concerning training design and; (3) to examine relationship between the training factors affecting the training effectiveness in Bhutanese hotel industry. Findings showed mismatch of training provided to employees resulting in poor quality of service. Negative score was found between the importance and satisfaction level of hotel employees on contents of training design. However the results showed positive relationship between the training factors and training effectiveness, work environment has strong influence.     

大数据背景下区域木材物流配送中心选址

指出了我国木材物流存在的主要问题以及解决方案,结合大数据技术,利用遗传算法进行木材物流配送中心的选址,建立了数学模型并进行了案例分析,以达到对木材物流成本和服务的优化。     

济南市古生物化石赋存特征及保护区划研究

为贯彻《古生物化石保护条例》,提高济南市古生物化石保护水平,在对区内古生物化石资源进行野外勘查和综合整理的基础上,依据古生物化石鉴定结果及其赋存地层分布特征,得出济南市古生物化石的分布特征,划分了古生物化石产地,选择化石完整程度、富集程度、剖面出露程度、周边地质环境、工程活动影响五个评价因子,运用综合指数法,建立了符合济南实际的古生物化石保护区划分体系,将区内古生物化石产地进行了保护区分级,并按照“保护优先,结合实际”的原则,制定了符合济南市实际的古生物化石保护措施。     

制度距离、投资动机与企业OFDI区位选择——中国对外直接投资“制度风险偏好”的一种解释

由于企业的对外直接投资（OFDI）存在制度适应成本，东道国与母国之间的制度距离会对企业OFDI产生负向影响。基于2003—2015年中国对140个国家和地区OFDI的分析表明：中国企业的OFDI具有明显的市场寻求动机和战略资源寻求动机，其中，市场寻求型OFDI表现出显著的互补效应，战略资源寻求型OFDI表现出一定程度的挤出效应；东道国与中国的制度距离会通过投资动机影响中国企业OFDI的区位选择，即倾向于向制度距离较小的国家和地区进行OFDI，且制度距离会弱化市场寻求型OFDI的互补效应和战略资源寻求型OFDI的挤出效应。站在企业角度来看，中国企业在进行OFDI时并不具有“制度风险偏好”，而是表现出“制度风险规避”特征：选择对其自身发展来讲制度风险较小（制度距离较小）的目标市场进行OFDI。因此，中国应深化市场经济体制改革，提升国内制度质量，加强国际经济合作，并增强企业的制度适应能力，以有效减小制度距离对企业OFDI区位选择的约束，进而优化OFDI区位分布，提高OFDI效益和质量。     

股权集中度视角下高管团队特征对现金股利政策的影响

现金股利政策是上市公司对盈利进行分配或留存用于再投资的决策问题,在公司经营中起着至关重要的作用。探究了高管团队特征(规模、年龄、性别、学历背景)对企业现金股利政策的影响,研究发现管理团队的规模越大、平均年龄越大,企业现金股利支付率越高,表明企业管理团队人数越多,年龄越大,越容易采用较高的股利支付率,而管理团队的平均学历越高,越倾向于选择较低的现金股利分配率。说明更高学历的管理层认为,较低的现金股利支付水平才是有利于企业发展的股利支付水平。男性管理层和女性管理者对企业支付现金股利的高低并没有明显的差异。进一步研究发现,企业的股权越集中,管理者的特征对现金股利政策的影响会被弱化。也就是说,股权集中度会显著削弱管理者特征对公司现金股利政策的影响,该实证结果也印证了上市公司中代理问题的普遍存在。研究结果可为企业管理团队的合理配置提出可以借鉴的依据以及实证结果的支持。