A pre/post evaluation of fatigue,stress and vigilance amongst commercially licensed truck drivers performing a prolonged driving task

Purpose. The main purpose of this research study was to evaluate changes in fatigue, stress and vigilance amongst commercially licensed truck drivers involved in a prolonged driving task. The secondary purpose was to determine whether a new ergonomic seat could help reduce both physical and cognitive fatigue during a prolonged driving task. Two different truck seats were evaluated: an industrial standard seat and a new truck seat prototype. Methods. Twenty male truck drivers were recruited to attend two testing sessions, on two separate days, with each session randomized for seat design. During each session, participants performed two 10-min simulated driving tasks. Between simulated sessions, participants drove a long-haul truck for 90 min. Fatigue and stress were quantified using a series of questionnaires whereas vigilance was measured using a standardized computer test. Results. Seat interactions had a significant effect on fatigue patterns. Conclusion. The new ergonomic seat design holds potential in improving road safety and vehicle accidents due to fatigue-related accidents.     

Impact of urban water supply on energy use in China: a provincial and national comparison

To reduce greenhouse gas (GHG) emissions and help mitigate climate change, urban water systems need to be adapted so that electrical energy use is minimised. In this study, energy data from 2011 was used to quantify energy use in China’s urban water supply sector. The objective was to calculate the energy co-benefits of urban water conservation policies and compare energy use between China and other countries. The study investigated influencing factors with the aim of informing the development of energy efficient urban water infrastructure. The average energy use per cubic metre and per capita for urban water supply in China in 2011 was 0.29 kWh/m³ and 33.2 kWh/cap year, respectively. Total GHG emissions associated with energy use in the urban water supply sector were 7.63 MtCO₂e, or carbon dioxide equivalent. Calculations using these indicators showed significant energy savings could result from water conservation measures. A comparison between provinces of China showed a direct correlation between energy intensity of urban water supply and the population served per unit length of pipe. This may imply energy and emission intensity can be reduced if more densely populated areas are supplied by a corresponding pipe density, rather than by a low-density network operating at higher flow rates. This study also found that while the percentage of electrical energy used for urban water supply tended to increase with the percentage of population served, this increase was slower where water supply was more energy efficient and where a larger percentage of population was already supplied.     

Different Shades of Green: A Case Study of Support for Wind Farms in the Rural Midwest

Benton County, in north-central Indiana, USA has successfully sited more than 500 turbines. To understand Benton County’s acceptance of wind farms, a holistic case study was conducted that included a document review, a survey of local residents and interviews with key stakeholders. Survey questionnaires were sent to 750 residents asking questions about attitudes toward the wind farms, perceived benefits and impacts from the wind farms, environmental attitudes, and demographic information. Key stakeholders were also interviewed for a deeper understanding of the historical timeline and community acceptance of the wind farm development. While there is limited opposition to the turbines, on the whole the community presents a front of acceptance. Financial, rather than environmental, benefits are the main reason for the acceptance. Although significant in other case studies, transparency and participation do not play a large role in Benton County’s acceptance. Most residents are not concerned with either visual impacts or noise from the wind turbines. More concrete benefits to the community, such as reduced energy bills for county residents, could help to extend acceptance even further within the community. Although there are concerns about the acceptance of wind farms and the impacts of those farms on local residents in both peer-reviewed literature and popular media, we found little evidence of those concerns in Benton County. Instead, we found Benton County to be a community largely accepting of wind farms.     

Cost analysis of composite sampling for classification

When an environmental sampling objective is to classify all the sample units as contaminated or not, composite sampling with selective retesting can substantially reduce costs by reducing the number of units that require direct analysis. The tradeoff, however, is increased complexity that has its own hidden costs. For this reason, we propose a model for assessing the relative cost, expressed as the ratio of total expected cost with compositing to total expected cost without compositing (initial exhaustive testing). Expressions are derived for the following retesting protocols: (i) exhaustive, (ii) sequential and (iii) binary split. The effects of both false positive and false negative rates are also derived and incorporated. The derived expressions of relative cost are illustrated for a range of values for various cost components that reflect typical costs incurred with hazardous waste site monitoring. Results allow those who are designing sampling plans to evaluate if any of these compositing/retesting protocols will be cost effective for particular applications.