An ensemble wavelet bootstrap machine learning approach to water demand forecasting: a case study in the city of Calgary,Canada

This paper explores a hybrid wavelet, bootstrap and neural network (WBNN) modeling approach for daily (1, 3 and 5 day) urban water demand forecasting in situations with limited data availability. This method was tested using 3 years of daily water demand and meteorological data for the city of Calgary, Alberta, Canada. The performance of the WBNN method was compared to that of three other methods: traditional neural networks (NN), wavelet NNs (WNN), and bootstrap-based NN (BNN) models. While the hybrid WBNN and WNN models equally provided 1-day lead-time forecasts of greater accuracy than those obtained with other methods, for longer lead-time (3- or 5-day) forecasts the WBNN model alone outperformed the other models. The confidence bands generated using the WBNN model displayed the uncertainty associated with the forecasts.     

Influence of chemical and physical characteristics of cement kiln dusts (CKDs) on their hydration behavior and potential suitability for soil stabilization

The interaction of CKDs with a given soil depends on the chemical and physical characteristics of the CKDs. Hence, the characterization of CKDs and their hydration products may lead to better understanding of their suitability as soil stabilizers. In the present article, four different CKD powders are characterized and their hydration products are evaluated. A detailed chemical (X-ray diffraction), thermogravimetric and morphological (scanning electron microscope) analyses of both the CKD powders and the hydrated CKD pastes are presented. In general, high free-lime content (~ 14–29%) CKDs, when reacted with water produced significant amounts of calcium hydroxide, ettringite and syngenite. These CKDs also developed higher unconfined compressive strength and higher temperature of hydration compared to CKDs with lower amounts of free-lime. An attempt was made to qualitatively correlate the performance of CKD pastes with the chemical and physical characteristics of the original CKD powders and to determine their potential suitability as soil stabilizers. To that effect a limited unconfined compressive strength testing of CKD-treated kaolinite clays was performed. The results of this study suggest that both the compressive strength and the temperature of hydration of the CKD paste can give early indications of the suitability of particular CKD for soil stabilization.     

Application of autocorrelation analysis for interpreting acoustic emission in rock

The statistical properties of acoustic emission from rock samples were studied as a function of applied uniaxial load. It was found that the parameters of the autocorrelation function of the acoustic emission event series change significantly near failure. An increase in the values of the autocorrelation coefficients and a tendency to a linear decrease with time were observed. We propose that the increasing autocorrelation of the acoustic emission series is an evidence of the increased affect that the individual acoustic emission sources have on one another. This mutual effect of acoustic events arises as a result of the redistribution of stress in the sample during the fracturing process at higher loads (more than 95% of ultimate strength). The results support the possibility of using autocorrelation analysis as a failure warning sign or even to predict the sample's total failure. Different rock materials and various loading patterns were used to generalise the results obtained.     

Vergleich von hydraulischen und chemischen Sedimenteigenschaften aus Spül- und Kernbohrungen im Raum Peine (Norddeutschland)

Comparison of hydraulic and chemical properties of sediments from flush- and core drillings in the area of Peine (Germany). Because of financial constraints, investigations of nitrate metabolism are often based on disturbed borehole samples. It is arguable, however, whether disturbed samples are suitable for these types of investigations. Disadvantages of disturbed samples in comparison to undisturbed core samples are well known and include possible contamination of the sample by mud additives, destruction of the sediment formation and the insecurity concerning the correct depth allocation. In this study, boreholes were drilled at three locations to a maximum depth of 50?m. The extracted samples, as intact sediment cores and drill cuttings, were studied with regard to chemical and hydraulic parameters of the aquifer sediments. The results show: 1. hydraulic parameters are not affected by clay-based mud; 2. disturbed samples contain less fine grain material relative to the core samples, and the hydraulic conductivity can only be estimated from catch samples; 3. catch samples contain fewer reducing agents (sulphides, organic carbon) than core samples in hydraulically passive zones (defined as K < 10^–6?m?·?s^–1); 4. the results of analyses of disturbed and undisturbed core samples are in good agreement for hydraulically active zones (K ≥ 10^–6?m?·?s^–1).     

Identifikation NSO-heterocyclischer Prioritärsubstanzen zur Erkundung und Überwachung Teeröl-kontaminierter Standorte

The German Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV) requires the monitoring of NSO-heterocyclic hydrocarbons without specifying the extent of such analysis. An assessment procedure for the identification of NSO-heterocyclic priority substances was thus created within the “KORA” project (“Natural Attenuation: Retention and Degradation Processes Reducing Contaminations in Groundwater and Soil”) funded by the German Federal Ministry of Education and Research (BMBF). This assessment includes physicochemical properties, biodegradability, toxicity, and groundwater propagation of these substances at creosote-contaminated sites. In addition to unsubstituted compounds, the derived list of 20 priority NSO-heterocycles also contains substituted derivatives as well as relevant transformation products.     

Characterising urban concentration and land-use diversity in simulations of future land use

This paper presents two sets of functional indicators that were implemented and tested for the assessment of spatial aspects of future land-use configurations as simulated by a land-use model. This is potentially useful for the ex-ante evaluation of spatial planning policies. The indicators were applied in a Dutch case study and relate to two important themes in Dutch spatial planning: compact urbanisation and mixing of land uses. After a short introduction of these themes, the sets of indicators are presented which are used for their evaluation. These indicators are applied to simulations based on two scenarios for land-use development in the Netherlands up to 2030. After a discussion of the results we conclude that the combined application of land-use models and indicators produces new and potentially useful information for policy makers, although both the model and the associated indicators are still in a state of development.     

Control of polyaniline conductivity and contact angles by partial protonation

Many studies require a specific value of conductivity when investigating conducting polymers. The conductivity of polyaniline can efficiently be controlled by partial protonation of the polyaniline base. Although this is a simple task in principle, practical guidelines are missing. In the present study, the changes in the conductivity of polyaniline base after immersion in aqueous solutions of various acids are reported. Polyaniline base has been reprotonated in aqueous solutions of picric, camphorsulfonic and phosphoric acids. The conductivity of partially reprotonated polyaniline varied between 10⁻⁹ and 10⁰ S cm⁻¹. The relation between the pH of a phosphoric acid solution, which was in equilibrium with polyaniline, and the conductivity σ is pH = 0.77 − 0.64 log(σ [S cm⁻¹]). The wettability, i.e. water contact angles, can similarly be set by partial protonation to between 78° for polyaniline base and 44° for polyaniline reprotonated in 1 mol L⁻¹ phosphoric acid. In solutions of picric acid, the transition from the non‐conducting to the conducting state occurs over a narrow range of acid concentrations, and the tuning of conductivity is consequently difficult. Phosphoric acid is well suited for the control of conductivity of polyaniline because of the moderate dependence of the conductivity on the acid concentration or pH. Copyright © 2007 Society of Chemical Industry