无机盐对两性离子聚合物在粘土表面吸附的影响

通过测定无机盐对具有不同分子结构两性离子聚合物在粘土表面吸附特点,确定出了两性离子聚合物分子结构特征对其在粘土表面吸附规律及其受无机盐影响的变化规律。     

农田灌溉设施的全要素生产率增长效应

基于中国15个小麦主产省2000—2017年面板数据,采用SFA-Malmquist指数法和面板工具变量法探讨了农田灌溉设施的小麦全要素生产率增长效应及作用机制,结果表明:2000—2017年间,小麦全要素生产率年均提升1.66%,技术进步率和效率提升率年均增长1.21%和0.38%,总体表现为技术诱导型的增长模式;农田灌溉规模的扩张可以在保障小麦生产效率提升的同时推动技术进步,实现小麦全要素生产率增长的双重驱动;农田灌溉质量的提升表现出正向的技术进步效应,但对技术效率却产生了微弱负向影响,且全要素生产率增长效应不显著。因此,在保持灌溉规模扩张对小麦全要素生产率驱动作用的同时,挖掘灌溉质量提升带来的全要素生产率增长潜能,将会是实现小麦稳产增产的关键。     

资金约束下损失规避零售商的订购和广告协同策略

在损失规避下,探讨了零售商的订购和广告协同决策问题。零售商的初始资金状态存在三种情形：资金充足、资金相对短缺（不需融资）、资金短缺（对外融资）,分别在三种情形下刻画了零售商的最优运营策略,结果表明：零售商用于商品采购和广告的资金产生的边际效用与边际负效用之比相等,且介于1与单位融资资金的使用成本之间;用于两项活动的最后一单位资金产生的边际效用相等。探讨了损失规避、初始资金、融资利率、商品价格及广告促销的敏感性对运营策略的影响：在资金充足或资金短缺下,商品订购量和广告强度随影响因素的变动方向通常相同;在资金相对短缺下,商品订购量和广告强度随影响因素的变动方向则相反。讨论中揭示了一些管理启示。     

地方政府水环境治理的协同机制及实现条件——基于SX县水环境治理分析

水环境治理是对环境外部性偏差进行干预的一种方式,也是国家治理体系与治理能力现代化建设的重要内容。地方政府承担着区域水环境治理的基本职责,在应对复杂性环境问题与自我创新导向的协同变迁过程中,形成了常规协同与动员协同、专项协同与整体协同、纵横协同与内外协同、结构协同与程序协同等不同类型的协同治理机制。本文结合SX县水环境治理实践,具体研究水环境协同治理机制的生成条件、运行逻辑和基本特点。在此基础上,将水环境治理协同机制有效运转的基本条件归纳为价值引导、公众参与、制度统协和技术支持等方面。     

基于网络搜索信息的农村水环境质量灰色预测模型

针对农村水环境直接监测数据相对缺乏、间接数据难以有效引入的问题,综合灰色关联分析和预测模型,提出一种基于网络搜索信息的农村水环境质量灰色预测模型。首先,综合考虑数据重要性和可获得性,确定农村水环境相关的搜索关键词清单;然后,采用主成分分析法提取搜索关键词的主要特征,构建初始网络搜索变量,并利用灰色绝对关联度衡量各初始网络搜索变量与水环境质量之间的关联程度。在此基础上,构建不同频率数据的多变量离散灰色模型,将强关联变量的降频数据作为多变量离散灰色模型的驱动因素,从而构建基于网络搜索信息的农村水环境质灰色预测模型。实例分析结果表明,相对于传统灰色模型,引入网络搜索信息可以提高农村水环境预测精度,为农村水环境治理提供决策支持。     

股价暴涨的风险:基于中国股市的实证

股价暴涨直观上带来高收益，激发市场正面情绪，那么为什么暴涨被视为风险?本文利用2006年至2016年中国A股上市公司数据，通过计量建模对暴涨股票的特征和日后的市场表现进行刻画。实证发现：（1）股价暴涨频度高的股票，呈现低资产收益率、高市值账面比、多散户持股、少沪深300成份股等特点；（2）易发生暴涨的股票其长期超额收益率更低，未来有更大的暴跌风险和更高的收益率波动率；（3）对于运营基本面较差、市场过于乐观、信息披露质量较低的股票，暴涨后的暴跌风险更加明显。研究结论在不同代理变量选择、多种计量模型设定下均稳健成立。本文揭示了暴涨不仅仅是极端价格波动，而且更容易发生在高风险股票中，未来蕴含着更大的潜在损失。暴涨是实实在在的风险。     

An Insurance Model for Risk Management of Process Facilities

Most existing risk management models for process industries do not consider the effect of insurance coverage, which results in an overestimation of overall risk. A model is presented in this article to study the effect of insurance coverage of health, safety, environmental, and business risks. The effect of insurance recovery is modeled through the application of adjustment factors by considering the stochastic factors affecting insurance recovery. The insurance contract's conditions, deductibles, and policy limits are considered in developing the insurance recovery adjustment factors. Copula functions and Monte Carlo simulations are used to develop the distribution of the aggregate loss by considering the dependence among loss classes. A case study is used to demonstrate both the practical application of the proposed insurance model to improve management decisions, and the mitigating effect of insurance to minimize the residual risk.     

Risk Perceptions Toward Drinking Water Quality Among Private Well Owners in Ireland: The Illusion of Control

In rural areas where no public or group water schemes exist, groundwater is often the only source of drinking water and is extracted by drilling private wells. Typically, private well owners are responsible for the quality and testing of their own drinking water. Previous studies indicate that well owners tend to underestimate the risks of their well water being contaminated, yet little is known about why this is the case. We conducted a qualitative study by interviewing private well owners in Ireland to investigate their beliefs surrounding their water quality, which, in turn, inform their risk perceptions and their willingness to regularly test their water. Based on our findings we designed a theoretical model arguing that perceived control is central in the perceived contamination risks of well water. More specifically, we argue that well owners have the illusion of being in control over their water quality, which implies that people often perceive themselves to be more in control of a situation than they actually are. As a result, they tend to underestimate contamination risks, which subsequently impact negatively on water testing behaviors. Theoretical and practical implications are highlighted.     

Optimal Abort Rules for Multiattempt Missions

Many real‐world systems use mission aborts to enhance their survivability. Specifically, a mission can be aborted when a certain malfunction condition is met and a risk of a system loss in the case of a mission continuation becomes too high. Usually, the rescue or recovery procedure is initiated upon the mission abort. Previous works have discussed a setting when only one attempt to complete a mission is allowed and this attempt can be aborted. However, missions with a possibility of multiple attempts can occur in different real‐world settings when accomplishing a mission is really important and the cost‐related and the time‐wise restrictions for this are not very severe. The probabilistic model for the multiattempt case is suggested and the tradeoff between the overall mission success probability (MSP) and a system loss probability is discussed. The corresponding optimization problems are formulated. For the considered illustrative example, a detailed sensitivity analysis is performed that shows specifically that even when the system's survival is not so important, mission aborting can be used to maximize the multiattempt MSP.     

水环境安全评价方法及其在京津冀地区的应用

为了克服模糊综合评价方法中的权重选取以及最大最小算法导致的信息缺失问题,本文提出一种改进的模糊综合评价方法。首先以熵权法、灰色关联分析法以及主成分分析法为基础,建立组合权重模型;其次,在加权平均原则下引入综合评分方法进行评价得到最终评价结果。从经济社会、水质状况和资源条件三个方面出发,初步建立了包含17个指标的水环境安全评价体系。利用主成分分析法对初步建立的指标体系进行了筛选,最终确定了13个指标作为评价指标。在筛选之后的指标体系下,用改进的模糊综合评价法对北京、天津、河北以及京津冀地区总体的水环境安全进行了评价,给出了2006-2014年间各地区水环境安全变化情况,结果显示京津冀地区水环境安全基本呈现北京优于河北优于天津的趋势;京津冀地区总体的水环境安全呈现先变好再变差的趋势。森林覆盖率是水环境安全最主要的影响因素,其次是第三产业占GDP的比重、人均水资源量以及Ⅰ-Ⅲ类水质占比。弹性系数分析表明,这四个指标的改善也是对京津冀地区水环境安全提高最有效的措施。最后,根据对评价结果的分析,提出了提高京津冀水环境安全的一些建议。