The major difficulty associated with the use of conceptual rainfall–runoff (CRR) models in hydrology is their calibration since most of these models involve a large number of parameters. CRR model calibration is a global optimisation problem since its main objective is to find a set of optimal model parameter values that provides a best fit between observed and estimated flow hydrographs. However, even when using the superior search capabilities of modern global optimisation methods (GOM), the search for a set of optimal parameter values within an inflated multi-dimensional search space can result in an inefficient search and may lead to inaccurate parameter estimates. In addition, in most CRR model calibration studies to-date, no explicit constraint in the search procedure was used that could ensure the physical consistency of the estimated parameters. Improvements in parameter estimates could be achieved if the search space could be reduced through the incorporation of constraints that describe the logical interactions between the rainfall and runoff processes. A methodology is proposed herein for formulating constraints to improve the probability of success of calibration methods. More specifically, inequalities relating CRR model parameters with the available hydrologic data were developed and incorporated into a GOM to reduce the search space. The shuffled complex evolution (SCE) GOM showed that this approach resulted in significant improvements in the estimation of CRR model parameters for the case of synthetic streamflow data without errors as well as for data with heteroscesdastic errors. Furthermore, the suggested constrained SCE-based calibration procedure could provide CRR model parameter estimates that are consistent with the physically plausible interactions between the rainfall and runoff processes under consideration.

The long-term weathering behavior of two UV cure clearcoat systems, one a monocure, the other a dual cure system, was studied by infrared spectroscopy, UV spectroscopy, Raman spectroscopy, dynamic mechanical thermal analysis (DMTA), and fracture energy measurements. The photooxidation rate and consumption of residual acrylate double bonds during weathering was highly dependant on the presence of hindered amine light stabilizers (HALS) for both systems. Ultraviolet light absorbers (UVA) had little effect on the photooxidation rate or rate of consumption of acrylate double bonds during weathering. Changes in fracture energy (brittleness) of the clearcoats mirrored the changes found in the consumption of residual acrylate double bonds. DMTA analysis of both clearcoats indicated no increase in crosslink density as weathering progressed, suggesting the acrylate double bonds were not reacting to form additional crosslinks.

A variety of spectroscopy and sample preparation techniques are described that allow chemical composition changes to be followed for isolated clearcoat samples, clearcoats in complete paint systems, and all coating layers in complete paint systems as a function of exposure. The analysis techniques provide photooxidation rate, ultraviolet light absorber effectiveness and longevity, and hindered amine light stabilizer effectiveness and longevity information that can be used to dramatically reduce the possibility of introducing inferior clearcoat/basecoat paint systems in service.

A Fourier transform infrared spectroscopy spectrum analysis technique has been developed to compare the photooxidation resistance of clearcoats from different chemical families. Fourier transform infrared spectroscopy measurements of clearcoat photooxidation resistance are combined with ultraviolet spectroscopy measurements of ultraviolet light absorber additive longevity to produce a clear picture of clearcoat weathering performance. Benchmark results are presented for 23 coatings from a wide range of chemical families. All measurements were carried out under 0.45W/m2 borosilicate inner and outer filtered xenon arc SAE J1960 JUN89 accelerated exposure.

The calibration of conceptual rainfall runoff (CRR) models is an optimization problem whose objective is to determine the values of the model parameters which provide the best fit between observed and estimated flows. This study investigated the performance of three probabilistic optimization techniques for calibrating the Tank model, a hydrologic model typical of CRR models. These methods were the Shuffled Complex Evolution (SCE), genetic algorithms (GA) and simulated annealing (SA) methods. It was found that performances depended on the choice of the objective function considered and also on the position of the start of the optimization search relative to the global optimum. Of the three global optimization methods (GOM) in the study, the SCE method provided better estimates of the optimal solution than the GA and SA methods. Regarding the efficiency of the GOMs, as expressed by the number of iterations for convergence, the ranking in order of decreasing performance was the SCE, the GA and the SA methods.

Horseradish peroxidase (HRP) catalyses the oxidation of phenols by hydrogen peroxide resulting in the formation of water-insoluble polymers which can be separated by coagulation and sedimentation. The feasibility of the enzyme process to treat a foundry wastewater containing 3.5 mM of total phenols (330 mg/l as phenol) was examined. Two enzyme stocks of different purities were used but total phenols removal was independent of enzyme purity. For both stocks, 97 to 99% of the phenolic contaminants were removed, despite the presence of other contaminants such as organic compounds and iron in the waste matrix. The quantity of HRP required for this degree of treatment was in the same range as for the treatment of a synthetic wastewater containing an equal amount of pure phenol. Polyethylene glycol, a chemical additive, reduced enzyme inactivation, allowing a 22-fold reduction in the amount of HRP required for 99% removal of phenols from the foundry waste. Residual chemical oxygen demands (COD) varied depending on the enzyme source. The high purity HRP achieved more than 65% removal of COD, but due to a high concentration of other organic matter present in the low purity HRP, no reduction in COD was achieved with this enzyme source. A comparison was made between enzyme treatment and oxidation using Fenton's reagent. Enzyme cost must be significantly reduced in order to make the enzyme treatment process economically competitive.

Hydroperoxide concentration behavior measurements and transmission Fourier transform infrared spectroscopy measurements were used to compare the photooxidation resistance of three acrylic-melamine clearcoats. Ultraviolet spectroscopy was used to compare the longevity of additives that absorb ultraviolet light for the same clearcoats. Samples were subjected to SAE J1960 JUN89 xenon-are accelerated exposure. No dramatic difference in clearcoat photooxidative degradation rate was found, but dramatic differences in ultraviolet light absorber longevity were found. Paint systems based on the clearcoat that exhibits poor ultraviolet light absorber longevity exhibited poor Florida weathering performance.