Spatiotemporal modeling of irregularly spaced aerosol optical depth data

Many advancements have been introduced to tackle spatial and temporal structures in data. When the spatial and/or temporal domains are relatively large, assumptions must be made to account for the sheer size of the data. The large data size, coupled with realities that come with observational data, make it difficult for all of these assumptions to be met. In particular, air quality data are very sparse across geographic space and time, due to a limited air pollution monitoring network. These “missing” values make it difficult to incorporate most dimension reduction techniques developed for high-dimensional spatiotemporal data. This article examines aerosol optical depth (AOD), an indirect measure of radiative forcing, and air quality. The spatiotemporal distribution of AOD can be influenced by both natural (e.g., meteorological conditions) and anthropogenic factors (e.g., emission from industries and transport). After accounting for natural factors influencing AOD, we examine the spatiotemporal relationship in the remaining human influenced portion of AOD. The presented data cover a portion of India surrounding New Delhi from 2000–2006. The proposed method is demonstrated showing how it can handle the large spatiotemporal structure containing so much missing data for both meteorologic conditions and AOD over time and space.     

The Yellow River in transition

Like many parts of the world, the Yellow River basin has problems associated with water scarcity, pollution, and flood risk. Analyses that focus only on the physical characteristics of these problems miss some of their most important social drivers. In this paper we identify some interlocking changes that have occurred as a consequence of economic reforms begun in China in 1978, and the implications of these changes for the Yellow River. The reforms have caused changes in the organisation of household production, increasing urbanisation and urban affluence, rapid industrialisation, and large scale spatial shifts in agricultural production. Rather than specific decisions it is these gradual changes that have affected the current status of the Yellow River and its basin. Our analysis suggests that at least some solutions to water problems in the Yellow River lie outside the basin, and beyond the realm of science or technology.     

Thermal instability and runaway criteria: The dangers of disregarding dynamics

Two exemplary exothermic processes, synthesis of nitroglycerine in a continuous stirred tank reactor (CSTR) and synthesis of the explosive RDX in a CSTR, are used to demonstrate the dangers of ignoring the system dynamics when defining criteria for thermal criticality or runaway. Stability analyses are necessary to prescribe such criteria, and for these systems prove the presence of dangerous oscillatory thermal instability which cannot be detected using the steady state thermal balances.     

Estimating the Lower Heating Values of Hazardous and Solid Wastes

ABSTRACT

A new equation is proposed to predict the lower heating value of hazardous and non-hazardous materials. The equation was developed by a statistical correlation of heating value and composition data for a variety of materials as reported in a number of sources. The model takes into account the carbon, hydrogen, oxygen, chlorine, and sulfur content of the material being combusted.     

Macroergonomic Analysis and Design for Improved Safety and Quality Performance

Abstract

Macroergonomics, which emerged historically after sociotechnical systems theory, quality management, and ergonomics, is presented as the basis for a needed integrative methodology. A macroergonomics methodology was presented in some detail to demonstrate how aspects of microergonomics, total quality management (TQM), and sociotechnical systems (STS) can be triangulated in a common approach, in the context of this methodology, quality and safety were presented as 2 of several important performance criteria. To demonstrate aspects of the methodology, 2 case studies were summarized with safety and quality performance results where available. The first case manipulated both personnel and technical factors to achieve a “safety culture” at a nuclear site. The concept of safety culture is defined in INSAG-4 (International Atomic Energy Agency, 1991). as “that assembly of characteristics and attitudes in organizations and individuals which establishes that, as an overriding priority, nuclear plant safety issues receive the attention warranted by their significance.” The second case described a tire manufacturing intervention to improve quality (as defined by Sink and Tuttle, 1989) through joint consideration of technical and social factors. It was suggested that macroergonomics can yield greater performance than can be achieved through ergonomic intervention alone. Whereas case studies help to make the case, more rigorous formative and summative research is needed to refine and validate the proposed methodology respectively.     

Braided River Flow and Invasive Vegetation Dynamics in the Southern Alps, New Zealand

In mountain braided rivers, extreme flow variability, floods and high flow pulses are fundamental elements of natural flow regimes and drivers of floodplain processes, understanding of which is essential for management and restoration. This study evaluated flow dynamics and invasive vegetation characteristics and changes in the Ahuriri River, a free-flowing braided, gravel-bed river in the Southern Alps of New Zealand’s South Island. Sixty-seven flow metrics based on indicators of hydrologic alteration and environmental flow components (extreme low flows, low flows, high flow pulses, small floods and large floods) were analyzed using a 48-year flow record. Changes in the areal cover of floodplain and invasive vegetation classes and patch characteristics over 20 years (1991–2011) were quantified using five sets of aerial photographs, and the correlation between flow metrics and cover changes were evaluated. The river exhibits considerable hydrologic variability characteristic of mountain braided rivers, with large variation in floods and other flow regime metrics. The flow regime, including flood and high flow pulses, has variable effects on floodplain invasive vegetation, and creates dynamic patch mosaics that demonstrate the concepts of a shifting mosaic steady state and biogeomorphic succession. As much as 25 % of the vegetation cover was removed by the largest flood on record (570 m³/s, ~50-year return period), with preferential removal of lupin and less removal of willow. However, most of the vegetation regenerated and spread relatively quickly after floods. Some flow metrics analyzed were highly correlated with vegetation cover, and key metrics included the peak magnitude of the largest flood, flood frequency, and time since the last flood in the interval between photos. These metrics provided a simple multiple regression model of invasive vegetation cover in the aerial photos evaluated. Our analysis of relationships among flow regimes and invasive vegetation cover has implications for braided rivers impacted by hydroelectric power production, where increases in invasive vegetation cover are typically greater than in unimpacted rivers.     

Effects of leadership consideration and structure on employee perceptions of justice and counterproductive work behavior

In this paper, we examine the effects of leadership consideration and structure on two important organizational behavior outcomes: employee perceptions of organizational justice and counterproductive work behavior (CWB). We examine these effects across two studies using multisource data (employees and supervisors in Study 1; employees and coworkers in Study 2). Results reveal that consideration and structure have distinct effects across distributive, procedural, informational, and interpersonal dimensions of justice. Moreover, results suggest that consideration and structure have multiplicative effects on employee CWB. We find the highest levels of CWB among employees of supervisors who exhibit high structure and low consideration. Interestingly, results also suggest that the effects of structure on CWB may be curvilinear (u‐shaped) such that moderate levels of structure are associated with the lowest levels of CWB. We discuss implications for future consideration and structure research as well as managerial practice. Copyright © 2012 John Wiley & Sons, Ltd.     

Water Stress Projections for the Northeastern and Midwestern United States in 2060: Anthropogenic and Ecological Consequences

Future climate and land‐use changes and growing human populations may reduce the abundance of water resources relative to anthropogenic and ecological needs in the Northeast and Midwest (U.S.). We used output from WaSSI, a water accounting model, to assess potential changes between 2010 and 2060 in (1) anthropogenic water stress for watersheds throughout the Northeast and Midwest and (2) native fish species richness (i.e., number of species) for the Upper Mississippi water resource region (UMWRR). Six alternative scenarios of climate change, land‐use change, and human population growth indicated future water supplies will, on average across the region, be adequate to meet anthropogenic demands. Nevertheless, the number of individual watersheds experiencing severe stress (demand > supplies) was projected to increase for most scenarios, and some watersheds were projected to experience severe stress under multiple scenarios. Similarly, we projected declines in fish species richness for UMWRR watersheds and found the number of watersheds with projected declines and the average magnitude of declines varied across scenarios. All watersheds in the UMWRR were projected to experience declines in richness for at least two future scenarios. Many watersheds projected to experience declines in fish species richness were not projected to experience severe anthropogenic water stress, emphasizing the need for multidimensional impact assessments of changing water resources.     

Characterization of Drought in the South Atlantic,United States

Drought has been less extensively characterized in the humid South Atlantic compared to the arid western United States. Our objective was to characterize drought in the South Atlantic and to understand whether drought has become more severe in this region over time. Here we used monthly streamflow to characterize hydrological drought. Hydrological drought occurred when streamflow fell below the 20th percentile over three consecutive months and terminated once streamflow remained above the 20th percentile for three consecutive months. We characterized the frequency, duration, magnitude, and severity of events using the above definition. Significant changes in drought characteristics were tested with Mann‐Kendall over three periods: 1930‐2010, 1930‐1969, and 1970‐2010. We show that 71% of drought events were shorter than six months, while 7% were multiyear events. There was little evidence of trends in drought characteristics to support the claim of drought becoming more severe in the South Atlantic over the 20th Century. The one exception was a significant increase in the joint probability of nearby basins being simultaneously in drought conditions in the southern portion of the study area from 1970 to 2010. While drought characteristics have changed little through time, decreasing average streamflow in non drought periods coupled with increasing water demand provide the context within which recent multiyear drought events have produced significant stress on existing water infrastructure.