A STATISTICAL METHODOLOGY FOR PREDICTING THE POLLUTANTS IN A RIVER1

Urban and industrial areas continue to expand and consequently, to create serious water pollution problems to natural streams. The need for the development of accurate, reliable, and sensitive water quality prediction models is most desirable. The first objective of this research is to set guidelines for dividing a natural stream into more or less independent reaches based on some criteria. The second objective is to obtain the predicting equations of the water pollutants in a selected stream. The preliminary phase of this research evaluated water quality data sampled from the Pearl River which flows southwest and then turns south through the states of Mississippi and Louisiana. This evaluation served as guidelines to divide the total river basin into reaches (subsystems) appropriate to the objective of this research. Subsequent to this subsystem assignment, a stepwise multiple regression FORTRAN program was used to regress the pollutants (dependent variables) for both time and space on their water characteristics (independent variables). Based on the results obtained, the proposed statistical approach provides a practical tool for developing regression equations for the purpose of water pollutants' prediction.     

REGION OF INFLUENCE REGRESSION FOR ESTIMATING THE 50-YEAR FLOOD AT UNGAGED SITES1

ABSTRACT: Five methods of developing regional regression models to estimate flood characteristics at ungaged sites in Arkansas are examined. The methods differ in the manner in which the State is divided into subregions. Each successive method (A to E) is computationally more complex than the previous method. Method A makes no subdivision. Methods B and C define two and four geographic subregions, respectively. Method D uses cluster/discriminant analysis to define subregions on the basis of similarities in watershed characteristics. Method E, the new region of influence method, defines a unique subregion for each ungaged site. Split-sample results indicate that, in terms of root-mean-square error, method E (38 percent error) is best. Methods C and D (42 and 41 percent error) were in a virtual tie for second, and methods B (44 percent error) and A (49 percent error) were fourth and fifth best.     

基于时间的进场航班效率评估方法研究

终端区作为空中交通的起讫点,是拥堵、延误的多发区,其运行效率对航班整体的运行效率至关重要。欧洲航行安全组织(EUROCONTROL)采用畅通进场时间(Unimpeded AMSA Time)作为量化进场效率的标杆。我国目前还没有明确的进场效率量化指标,因此可以借鉴畅通进场时间这个指标来评估进场效率。以首都机场为研究对象,首先对进港航班ADS-B数据进行预处理来计算进场时间,然后利用K-means聚类算法对航班进行分组,运用回归分析法找寻与终端区拥挤程度关联性最强的解释变量,提出关于畅通航班拥挤阈值的方法来计算畅通进场时间,最后用时间效率指标对进场效率进行评估,得出5月首都机场的进场效率为83. 39%,可为进场效能评估提供参考。     

The role of risk avoidance and locus of control in workers’ near miss experiences: Implications for improving safety management systems

The process industry has made major advancements and is a leader in near-miss safety management, with several validated models and databases to track close call reports. However, organizational efforts to develop safe work procedures and rules do not guarantee that employees will behaviorally comply with them. Assuming that at some point, every safety management system will need to be examined and realigned to help prevent incidents on the job, it is important to understand how personality traits can impact workers' risk-based decisions. Such work has been done in the mining industry due to its characteristically high risks and the results can be gleaned to help the process industry realign goals and values with their workforce. In the current study, researchers cross-sectionally surveyed 1,334 miners from 20 mine sites across the United States, varying in size and commodity. The survey sought to understand how mineworkers' risk avoidance could impact their near miss incidents on the job – a common precursor to lost-time incidents. Multiple regressions showed that as a miner's level of risk avoidance increased by 1 unit in the 6-point response scale, the probability of experiencing a near miss significantly decreased by 30% when adjusting for relevant control variables. Additionally, a significant interaction between risk avoidance and locus of control suggested that the effect of risk avoidance on near misses is enhanced as a miner's locus of control increases. A one-unit increase in locus of control appends the base effect of risk avoidance on near misses with an additional 8% decrease in the probability. Findings are discussed from a near-miss safety management system perspective in terms of methods to foster both risk avoidance and locus of control in an effort to reduce the probability of near misses and lost time at the organizational level within the process industry and other high-hazard industries.     

Analyzing injury severity of bus passengers with different movements

Objective: Though public transport vehicles are rarely involved in mass casualty accidents, when they are, the number of injuries and fatalities is usually high due to the high passenger capacity. Of the few studies that have been conducted on bus safety, the majority focused on vehicle safety features, road environmental factors, as well as driver characteristics. Nevertheless, few studies have attempted to investigate the underlying risk factors related to bus occupants. This article presents an investigation aimed at identifying the risk factors affecting injury severity of bus passengers with different movements.

Method: Three different passenger movement types including standing, seated, and boarding/alighting were analyzed individually using classification and regression tree (CART) method based on publicly available accident database of Great Britain.

Results: According to the results of exploratory analyses, passenger age and vehicle maneuver are associated with passenger injury severity in all 3 types of accidents. Moreover, the variable “skidding and overturning” is associated with injury severity of seated passengers and driver age is correlated with injury severity of standing and boarding/alighting passengers.

Conclusions: The CART method shows its ability to identify and easily explain the complicated patterns affecting passenger injury severity. Several countermeasures to reduce bus passenger injury severity are recommended.     

Are two cynics better than one? Toward understanding effects of leader–follower (in‐)congruence in social cynicism

Prior research suggests that leaders' social cynicism can undermine important follower outcomes such as followers' motivation and performance. However, these studies have exclusively focused on leaders' social cynicism and neglected that followers' views on the social world might also influence the leadership process. On the basis of theories of social beliefs and person–supervisor fit, we offer an integrative perspective and predict that it is the congruence between leaders' and followers' social cynicism that shapes leadership dynamics. Data from 116 leader–follower dyads from a broad range of organizations and industries support our model: Polynomial regression and response surface analyses show significant congruence effects of leaders' and followers' social cynicism on followers' extra‐role behaviors and followers' proactive work behaviors. These positive effects of congruence on follower outcomes are transmitted by leader–member exchange quality. Finally, congruence effects are stronger when leaders' and followers' social cynicism is low rather than high. Overall, our study suggests that it is the correspondence between leaders' and followers' social cynicism that influences followers' leader–member exchange, extra‐role, and proactive behavior. We discuss the theoretical and practical implications of these findings for designing functional leader–follower dyads in organizations.     

基于MODIS气溶胶光学厚度与气象要素的苏锡常地区PM2.5地面浓度分布研究

基于GIS技术和岭回归分析方法,采用苏锡常地区的MODIS高分辨率气溶胶光学厚度资料、PM_(2.5)浓度观测资料和苏锡常及周边地区的气象观测资料,构建了基于气溶胶光学厚度和气象要素的PM_(2.5)地面浓度分布估算模型,模拟了2013年春季苏锡常地区PM_(2.5)的空间分布状况,并将此模型与气象要素多元回归模型、气溶胶光学厚度直接回归模型进行比较.结果表明:该模型将遥感观测资料与地面气象观测资料相结合,能够有效地模拟PM_(2.5)的空间分布状况;2013年春季苏锡常地区PM_(2.5)的空间分布具有整体上西北高、东南低,中心城区高、城郊区低的趋势,局部高浓度区域可能与工业生产、交通等人为因素有关;该模型能够在保持较高精度的前提下,有效地突出局部地区的变化特征,体现出更强的空间分异性,对于研究PM_(2.5)的空间分布规律具有一定的实际应用价值.     

Panel heterogeneous distribution analysis of trade and modernized agriculture on CO2 emissions: The role of renewable and fossil fuel energy consumption

In line with the global target of reducing climate change and its impact, this study explored the causal relationship between CO₂ emissions, modernized agriculture, trade openness, aggregate and disaggregate energy consumption in 14 African countries from 1990–2013 using a panel quantile estimation procedure. The empirical results showed that value addition to agricultural commodities declines CO₂ emissions in countries with high pollution levels. The study revealed a positive nexus between CO₂ emissions and energy consumption homogeneously distributed across quantiles. Trade openness was found to lower CO₂ emissions in countries with lower and higher levels of environmental pollution. While fossil fuel energy consumption was found to exacerbate CO₂ emissions, renewable energy consumption confirmed its mitigating effect on environmental pollution. The institution of climate‐smart agricultural options will sustainably increase productivity and income while adapting to climate change by reducing greenhouse gas emissions. Diversification of energy technologies with clean and modern energy sources like renewables avoid the over‐dependence on fossil fuels for agricultural purposes. Trade policies can stimulate flows of technology and investment opportunities for specialization in production and economies of scale. Hence, the consideration of policies that boost agricultural sector productivity and create an efficient market for international trade in Africa will help in improving livelihoods.     

Evaluating 24/7 Sobriety Program participant reoffense risk

Objective: Our study investigated risk factors in survival among a subpopulation of drivers in North Dakota’s 24/7 Sobriety Program. Participants mandated for a second driving-under-the-influence of alcohol (DUI) arrest were studied for a three-year interval that commenced with the start date for a 360-day enrollment. Method: A Stratified Cox regression model was developed to compute the hazard ratios for survival. A subsequent DUI-related offense as event of interest. Relation to the explanatory variable array that could be construed from administrative records were investigated. Results: Older drivers were 6.31 times more likely to reoffend than the younger driver cohort of 18–35-years. The survival curve slope showed the fastest decline in the 361-day to 730-day interval. Neither gender nor residence region was a significant predictor in DUI reoffense over the three-year monitoring interval. Preliminary work suggests reoffense was more likely if an individual had program history prior to this court mandated 360-day term in the 24/7 Sobriety Program for a second DUI. The program experience finding was unexpected but could not be studied in greater detail due to data and resource limitations. Conclusions: Administrative records access created a novel opportunity to explore an evolving impaired driving prevention strategy that has shown early promise. Individual driver survival in and after the 24/7 Sobriety Program was studied for three-years. Findings show age, post-program time interval, and possibly program history as areas to explore to improve survival rates. Driver DUI offense were most common shortly after program completion. Although limited to a single state, findings increase knowledge for refining strategies designed to impact driver subpopulations at higher risk for reoffense.