Jebelli H.,University of Nebraska - Lincoln |
Ahn C.R.,University of Nebraska - Lincoln |
Journal of Computing in Civil Engineering | Year: 2016
In construction worksites, slips, trips, and falls are major causes of fatal injuries. This fact demonstrates the need for a safety assessment method that provides a comprehensive fall-risk analysis inclusive of the effects of physiological characteristics of construction workers. In this context, this research tests the usefulness of the maximum Lyapunov exponents (Max LE) as a metric to assess construction workers' comprehensive fall risk. Max LE, one of the gait-stability metrics established in clinical settings, estimates how the stability of a construction worker reacts to very small disruptions. In order to validate the use of Max LE, a laboratory experiment that asked a group of subjects to simulate iron workers' walking tasks on an I-beam was designed and conducted. These tasks were designed to showcase various fall-risk profiles: walking with a comfortable walking speed presented a low fall-risk profile; carrying a one-sided load and walking at a faster speed on the I-beam both presented high fall-risk profiles. Inertial measurement unit (IMU) sensors were attached to the right ankle of participants' bodies to collect kinematic data for the calculation of Max LE. The results showed that Max LE offers adequate distinguishing power for characterizing the fall risk of various construction workers' tasks, and the introduced approach to compute the gait stability from IMU sensor data captured from human bodies could provide a valuable analysis of the safety-related risks present in construction workers' motions. © 2015 American Society of Civil Engineers.
Ignaccolo M.,Duke University |
De Michele C.,Environmental
Geophysical Research Letters | Year: 2010
The probability density function of the drop diameter at the ground is investigated during stratiform and convective precipitation intervals at Darwin, Australia. We show how, after a renormalization procedure of the drop diameter, the empirical probability density functions of both types of precipitation collapse in a single curve, indicating the possible existence of an invariant distribution of the drop diameter at the ground. © 2010 by the American Geophysical Union.
Moe S.J.,Norwegian Institute for Water Research |
De Schamphelaere K.,Ghent University |
Clements W.H.,Colorado State University |
Sorensen M.T.,Environmental |
And 2 more authors.
Environmental Toxicology and Chemistry | Year: 2013
Increased temperature and other environmental effects of global climate change (GCC) have documented impacts on many species (e.g., polar bears, amphibians, coral reefs) as well as on ecosystem processes and species interactions (e.g., the timing of predator-prey interactions). A challenge for ecotoxicologists is to predict how joint effects of climatic stress and toxicants measured at the individual level (e.g., reduced survival and reproduction) will be manifested at the population level (e.g., population growth rate, extinction risk) and community level (e.g., species richness, food-web structure). The authors discuss how population- and community-level responses to toxicants under GCC are likely to be influenced by various ecological mechanisms. Stress due to GCC may reduce the potential for resistance to and recovery from toxicant exposure. Long-term toxicant exposure can result in acquired tolerance to this stressor at the population or community level, but an associated cost of tolerance may be the reduced potential for tolerance to subsequent climatic stress (or vice versa). Moreover, GCC can induce large-scale shifts in community composition, which may affect the vulnerability of communities to other stressors. Ecological modeling based on species traits (representing life-history traits, population vulnerability, sensitivity to toxicants, and sensitivity to climate change) can be a promising approach for predicting combined impacts of GCC and toxicants on populations and communities. © 2012 SETAC.
Guenther A.B.,U.S. National Center for Atmospheric Research |
Jiang X.,U.S. National Center for Atmospheric Research |
Heald C.L.,Massachusetts Institute of Technology |
Sakulyanontvittaya T.,Environmental |
And 3 more authors.
Geoscientific Model Development | Year: 2012
The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1) is a modeling framework for estimating fluxes of biogenic compounds between terrestrial ecosystems and the atmosphere using simple mechanistic algorithms to account for the major known processes controlling biogenic emissions. It is available as an offline code and has also been coupled into land surface and atmospheric chemistry models. MEGAN2.1 is an update from the previous versions including MEGAN2.0, which was described for isoprene emissions by Guenther et al. (2006) and MEGAN2.02, which was described for monoterpene and sesquiterpene emissions by Sakulyanontvittaya et al. (2008). Isoprene comprises about half of the total global biogenic volatile organic compound (BVOC) emission of 1 Pg (1000 Tg or 1015 g) estimated using MEGAN2.1. Methanol, ethanol, acetaldehyde, acetone, α-pinene, β-pinene, t-β-ocimene, limonene, ethene, and propene together contribute another 30% of the MEGAN2.1 estimated emission. An additional 20 compounds (mostly terpenoids) are associated with the MEGAN2.1 estimates of another 17% of the total emission with the remaining 3% distributed among >100 compounds. Emissions of 41 monoterpenes and 32 sesquiterpenes together comprise about 15% and 3%, respectively, of the estimated total global BVOC emission. Tropical trees cover about 18% of the global land surface and are estimated to be responsible for ∼80% of terpenoid emissions and ∼50% of other VOC emissions. Other trees cover about the same area but are estimated to contribute only about 10% of total emissions. The magnitude of the emissions estimated with MEGAN2.1 are within the range of estimates reported using other approaches and much of the differences between reported values can be attributed to land cover and meteorological driving variables. The offline version of MEGAN2.1 source code and driving variables is available from http://bai.acd.ucar.edu/ MEGAN/ and the version integrated into the Community Land Model version 4 (CLM4) can be downloaded from http://www.cesm.ucar.edu/. © Author(s) 2012.
Society of Petroleum Engineers - SPE International Conference on Health, Safety and Environment 2014: The Journey Continues | Year: 2014
Being frightened of the unknown is a natural and essential human response. Most people in the US have never seen a hydraulic fracturing facility and know relatively little about their operations, and yet many have already developed opinions about their safety and environmental impact based on reports in the media. Energy companies must recognize and prepare for this reality when approaching communities where the development of hydraulic fracturing facilities is now being proposed. Dr. Kinslow presents several examples of community engagement strategies as they relate to the energy industry, specifically hydraulic fracturing, in Texas and other states. Through these examples, she illustrates how applying the three tools of commitment, transparency and dedicating the right people for this type of engagement are critical to addressing community concerns and to the economic success of hydraulic fracturing. Commitment to the community involves a proactive response to questions and concerns of the community. Interestingly, many concerns from fracking communities do not coincide with those concerns illustrated in the media. Proactively recognizing and addressing these issues learned from past experiences places the industry in a solid position to build a trusting relationship. Transparency is essential in this relationship. The Texas Commission on Environmental Quality (TCEQ) has developed an outstanding and transparent system of engagement, data-sharing and strong community outreach. This Agency-wide attitude has gained the TCEQ standing as a science-based, strategic, and trust worthy group to turn to when human health impacts are an issue in state and federal regulatory decision making. Having the right people to bring these tools forward is essential for successful engagement. This team must involve a set of communicators that are ready to apply their scientific, business, and regulatory knowledge in order to help people in the communities understand the safety and environmental issues. Communities know when someone is not genuine. Having the right people at the front lines to build and maintain that genuine relationship through knowledge sharing will gain respect and trust on all sides. Copyright 2014, Society of Petroleum Engineers.