Effect prediction of time-gaps for adaptive cruise control (ACC) and in-vehicle tasks on bus driver performance

Researchers have devoted a great deal of attention to the effects of driver assist systems on driver performance. This article describes a modeling approach to simulate the effects of time-gaps for adaptive cruise control (ACC) and manual in-vehicle tasks on bus-driver performance. A concept model was built with the knowledge of modularization, parameterization, and parallel processing. By running the model, the predictions for the effects of five levels of time-gaps and two types of in-vehicle tasks were collected in three measures: (1) mean gap, (2) minimum gap, and (3) collision rate. The model performed well in prediction, especially when driving with in-vehicle tasks. Predictions from the model were validated by the experiment with a verified fixed-base bus-driving simulator, used in the authors’ previous studies. Throughout the modeling approach, this research provides a theoretical and accurate way to assess effects of time-gaps and vehicle-equipped interfaces. In follow-up research, the authors will apply this approach to evaluate other driving assist systems (e.g. collision warning systems and navigation systems) to create a customized software kit.     

The fate of hydrogen peroxide as an oxygen source for bioremediation activities within saturated aquifer systems

In situ bioremediation is an innovative technique for the remediation of contaminated aquifers that involves the use of microorganisms to remediate soils and groundwaters polluted by hazardous substances. During its application, this process may require the addition of nutrients and/or electron acceptors to stimulate appropriate biological activity. Hydrogen peroxide has been commonly used as an oxygen source because of the limited concentrations of oxygen that can be transferred into the groundwater using above-ground aeration followed by reinjection of the oxygenated groundwater into the aquifer or subsurface air sparging of the aquifer. Because of several potential interactions of H2O2 with various aquifer material constituents, its decomposition may be too rapid, making effective introduction of the H2O2 into targeted treatment zones extremely difficult and costly. Therefore, a bench-scale study was conducted to determine the fate of H2O2 within subsurface aquifer environments. The purpose of this investigation was to identify those aquifer constituents, both biotic and abiotic, that are most active in controlling the fate of H2O2. The decomposition rates of H2O2 were determined using both equilibrated water samples and soil slurries. Results showed H2O2 decomposition to be effected by several commonly found inorganic soil components; however, biologically mediated catalytic reactions were determined to be the most substantial.     

DYNAMIC MODELING OF STREAM QUALITY BY INVARIANT IMBEDDING1

ABSTRACT. The estimator equations obtained using invariant imbedding is used to estimate the parameters in river or stream pollution. By using these equations, the parameters can be estimated directly from differential equations representing the pollution model and from measured noisy data such as BOD and DO. Another advantage of this approach is that a sequential estimation scheme is obtained. By using this sequential scheme, only current data are needed to estimate current or future values of the unknown parameters. Consequently, a large amount of computer time and computer memory can be saved. Furthermore, not only the parameters but also the concentrations of pollutants can be estimated. Thus, it also forms an effective forecasting technique. The classical least squares criterion is used in the estimation. Several examples are solved to illustrate the technique. (KEY WORDS: dynamic modeling; water pollution; invariant imbedding; forecasting; least squares criterion; estimation)     

Methanogenic diversity changes in full-scale anaerobic digesters by co-digestion of food waste and sewage sludge

Journal of Material Cycles and Waste Management - This study aims to investigate the methanogenic community of anaerobic mono-digestion of sewage sludge (SL-digester) and co-digestion of sewage...