Estimation of chloride permeability of concretes by empirical modeling: Considering effects of cement type,curing condition and age

In this study, effects of cement type, curing condition, and testing age on the chloride permeability of concrete were investigated experimentally. Chloride permeability of concrete was determined through rapid chloride permeability test (RCPT). The research variables included cement type (i.e. plain and four different blended cements), water–cement ratio (0.65 and 0.45), curing condition (uncontrolled, controlled, and wet curing), and testing age (28, 90, and 180 days). Furthermore, based on the experimental results, a neural network (NN) model-based explicit formulation was proposed to predict the chloride permeability of concrete in terms of the water–cement ratio, aggregate–cement ratio, superplasticizer–cement ratio, cement type, curing condition, and testing age. Finally, proposed NN based explicit formulation was verified by using the data gathered from the literature. The test results indicated that the selected experimental parameters had pronounced effects on the chloride permeability of concretes. Besides, it was found that the empirical model developed by using NN seemed to have a high prediction capability of the chloride permeability of concretes.     

Template‐free microsphere and hollow sphere formation of polymethylanilines

BACKGROUND: Microsphere and/or hollow sphere formation of methyl‐substituted polyaniline derivatives was investigated via chemical polymerization where different sets of conditions were examined. It was found that a variety of parameters (e.g. types and concentrations of monomer and oxidant, polymerization time, solvent with and without acid) have a crucial influence on the morphology of the resulting polyaniline derivatives. RESULTS: Structures with desired morphologies (with or without microspheres and hollow spheres) may be obtained in a controlled manner by changing the parameters. Moreover, the electrochemical and optical properties of the polymers in the presence of acid and/or base were investigated via cyclic voltammetry and UV‐visible and electron spin resonance spectroscopic techniques. It is noteworthy that the morphologies of microspheres and/or hollow spheres remained unchanged after repeated acid and base treatments. CONCLUSION: Micro/hollow spherical structures were successfully prepared via chemical polymerization of various substituted anilines by using ammonium persulfate as oxidant. It was found that the type of oxidant and monomers along with the polymerization time are quite important factors for the formation of micro/hollow spheres. Furthermore, hydrogen bond formation does not play any crucial role for the formation of these spheres. Chemically and electrochemically doped/dedoped states of microspheres and/or hollow spheres are very sensitive, and give rapid response towards vapours of HCl and NH₃, which makes them amenable for use in sensors. Copyright © 2009 Society of Chemical Industry     

Cost Savings in the Ozone Treatment of Paper Mill Effluents Achieved By a Closed-Loop Ozone Control System

Control strategies were created to reduce the operating costs of ozone stages of effluent treatment plants in paper mills as well as to improve the quality of the effluent. Biologically treated effluents from five mills were subjected to laboratory and pilot tests. All COD target values could be reached and maintained with SAC-based control strategies. Disturbing events were compensated with a deviation of only 2% within maximum 3.1 volume exchanges, depending on the kind of event. The SAC (spectral absorption coefficient) was found to be highly suitable for controlling the ozone dosage. In a SME paper mill, 20% of the operating costs of an ozone plant can be saved. The return on investment for such a system is thus about 8 months.     

Single-chip image sensors with a digital processor array

The architectures, implementation and applications of two smart sensors, LAPP and PASIC, are described. The basic idea of these two designs is to integrate an image sensor array with a digital processor array in a single chip. The integrated camera-and-processor eliminates the bottleneck of sequential image read-out that characterizes conventional systems. They provide fast, compact and economic solutions for tasks such as industrial inspection, optical character recognition and robot vision.     

Effects of canning processes on the elements content of cultivated mushrooms (Agaricus bisporus)

Mushroom (Agaricus bisporus) was studied for chemical characteristics after blanching and different chemical preservations (acidification and control process). Losses of Mn, Cu, Zn and Fe during blanching treatment were 45, 3.9, 23.48 and 35.3%, respectively. On the other hand, losses of drained weight values were only 37.5%. During storage for four months, and using different chemical preservation treatments, the differences of the means of the elements and drained weights were not significant (P < 0.05).     

Modelling of Stress State,Centre Consolidation and Roll Force in Billet Rolling

Roll pressure models have been derived from theoretical studies, FEM simulations and experimental investigations. A model developed from slip line field theory has been shown to fit well to the experimental results. The Finite Element simulations overestimated the pressure function. This is a common problem in hot rolling experiments, since the problem of measuring the correct rolling temperature makes the estimation of the yield strength very difficult. The difference between the FE calculations and the experimental measurements is a measure for the error in the experimental temperature measurements rather than for the accuracy of the Finite Element Method. Traditional modelling has not been an appropriate tool to evaluate the material flow in the centre of the billet. In spite of the fact that the entire stress state can be modelled by slip line field theory, the slip lines which determine the stress state in the centre coincide for actual geometries only in one single point. Thus the strain increments are known only in that single point. Since a material element passes that point instantaneously, it is not possible to find any finite strains in the centre by integrating any incremental function. By FEM, strain modelling is simple and the possibility to consolidate a porous bloom or ingot core can be determined. FE modelling requires an entirely new approach to the modelling problem. It is not reasonable to use FEM to evaluate only the temperature distribution for the use in roll force models from the previous century. Instead, a fully thermomechanically coupled FE model is suggested. However, the calculation time is still far too long to be used for on‐line control purposes. For this application hybrid modelling can be a solution, where off‐line FE models are combined with empirical modelling, and simplified models can be used for the process control.     

Behaviour ofYersinia enterocolitica andAeromonas hydrophila in skim milk during fermentation by various lactobacilli

In this study, behaviour ofYersinia enterocolitica andAeromonas hydrophila in skim milk during fermentation by various_{lactobacillus} sp. were determined. pH values of the skim milk samples were also examined during fermentation. The amount of produced lactic acid and diacetyl/acetoin productions of theLactobacillus sp. were estimated. Antimicrobial effects of the lactobacilli onY. enterocolitica andA. hydrophila were also determined by an agar diffusion method. WhileY. enterocolitica was not inhibited and grew during fermentation,A. hydrophila was inhibited, in part, and the growth was retarded. Results were supported by the agar diffusion method forY. enterocolitica, whereas inhibition activity was not found forA. hydrophila. The highest lactic acid productions were estimated inL. bulgaricus (7.50 mg/ml) andL. acidophilus (5.63 mg/ml) and four out of sixLactobacillus sp. were found to be diacetyl/acetoin producers.