Semi-empirical approach to modeling of soil flushing: model development, application to soil polluted by zinc and copper

This paper describes a semi-empirical approach to modeling the soil flushing technology. A new mathematical model aimed at predicting the course of the continuous soil flushing process by use of the input data obtained from simple batch laboratory experiments is described in the theoretical part. An objective of the study is to apply this new model to soil polluted by zinc and copper (11949 mg kg(-1) and 1895 mg kg(-1), respectively) by flushing the soil with an ammonia nitrogen solution. A set of batch experiments provided both equilibrium and kinetic data characterizing the leaching ability of both metals. By use of the model, the optimal ammonia concentration in the flushing solution was estimated (0.6 mol L(-1)). For this concentration, validity of the model results was verified by a column experiment. The removal efficiency obtained was 44% (zinc) and 54% (copper). The model correctly predicted the period of time needed for the removal of weakly bound metal fractions as well as the estimate of the overall removal efficiency of metals from the soil during the flushing process. It has also proven that it is possible to use the column experiment for model calibration through the modification of the input data. Agreement of the model and experimental results can be further improved this way.     

Environmentally friendly biocomposites based on waste of the dairy industry and poly(vinyl alcohol)

Environmentally friendly polymeric biocomposites based on whey powder, a waste material of the dairy industry, and fully or partially hydrolyzed poly (vinyl alcohol) were prepared and characterized with optical microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and stress–strain analysis, and their biodegradation was evaluated with the modified Zahn–Wellens method and the spectrophotometric determination of poly(vinyl alcohol). In addition, the ability of the biocomposites to absorb moisture and its consequent influence on the mechanical properties were investigated under different storage conditions. The structural differences of the two types of poly(vinyl alcohol) matrices had a significant effect on all the mentioned characteristics. Possible molecular interactions between the polymer matrix and modifier, due to hydrogen bonding, were also examined. First‐order kinetics were applied for the biodegradation data. The two‐phase character of the biodegradation was shown. The results indicated that whey powder is suitable for the modification of polymers, and this is important for the production of biodegradable polymer materials and the consequent reduction of the environmental load. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Solution of nonlinear boundary value problems—VIII. Evaluation of branching points based on shooting method and GPM technique

General straightforward method for finding branching points of nonlinear boundary value problems is presented. The technique proposed utilizes the equations used in the GPM method. The method can be applied to problems arising in a number of physical applications, the technique is tailored to diffusion and heat conduction problems.     

Proportioning with second-order information for model predictive control

We propose an algorithm for the effective solution of quadratic programming (QP) problems arising from model predictive control (MPC). MPC is a modern multivariable control method which gives the solution for a QP problem at each sample instant. Our algorithm combines the active-set strategy with the proportioning test to decide when to leave the actual active set. For the minimization in the face, we use a direct solver implemented by the Cholesky factors updates. The performance of the algorithm is illustrated by numerical experiments, and the results are compared with the state-of-the-art solvers on benchmarks from MPC.     

Calculation of multistage countercurrent separation processes—II multicomponent multistage separation by relaxation procedure

The relaxation method used for solution of problems arising in design of multicomponent separation processes is discussed and new modifications are proposed. The use of certain techniques for convergence acceleration is studied. The number of iterations is then substantially reduced and effectiveness of relaxation method is thus highly improved.This method is useful also for columns with multiple feeds, intercoolers etc., however, nonideal mixture can be conveniently handled. A modification of the relaxation procedure resulting in a pentadiagonal matrix is presented.     

Tax optimization in an agent-based model of real-time spectrum secondary market

The wireless communication industry is an essential sector boosting economic progress worldwide. The structure of the legacy wireless communication market, characterised by static licensing schemes, is moving towards real-time secondary spectrum markets. While the technological body of spectrum trading has been discussed in detail, from an economic perspectives there are still a lot of gaps in understanding how these transactions affect the economy of future communication standards. A challenging aspect of the real-time spectrum market deployment is the implementation of the appropriate tax system that impacts the market structure. With regards to this, we aim to build an agent-based model of the real-time secondary spectrum market in which various taxes including value-added tax, corporate tax, consumption tax and fixed tax, are employed. The relations between selected tax type rates and the hypothetical revenue of the national regulator is established using Laffer curves. The results of the analysis confirm the existence of a tax distortion, i.e. a system deviation from the efficient system functioning affected by the tax introduction. To measure the complexity of the tax strategies and the emergent tax distortion, an original approach based on Euclidean metrics defined over a vector space of the system performance indicators was proposed. This approach was later applied in parallel with the traditional Harberger’s triangle methodology. We found that the constrained optimisation with the tax distortion restrictions provide satisfactory results regarding the stability of the tax distortion measure. Therefore, we propose the application of the most effective corporate tax optimisation complemented by selected additional tax types.     

SU(1,1) Squeezing of SU(1,1) Generalized Coherent States

Abstract

In this paper we have introduced a new class of the SU(1,1) coherent states which are the eigenstates of the generalized annihilation operator K_. We have also studied the SU(1,1) squeezing of the SU(1,1) generalized coherent states interacting with a nonlinear medium modelled as an anharmonic oscillator.     

Intensification of 1‐phenylethanol production by periodical membrane extraction of the product from fermentation broth

BACKGROUND: Enantioselective bioreduction of acetophenone to S‐(?)‐1‐phenylethanol by Saccharomyces cerevisiae under non‐growth conditions is inhibited by the product created. This study investigated the possibility of intensification and mathematical simulation of 1‐phenylethanol production using periodic product removal carried out by membrane extraction in a hollow fiber membrane module. RESULTS: The highest reaction rate was observed at the beginning of the biotransformation. With increased product concentration in the reaction medium, the reaction rate gradually decreased by about 50% after 20 h of biotransformation. The low concentration of product maintained in the reaction medium using membrane extraction had positive influence on the 1‐phenylethanol production with a high yield (96%) and mean reaction rate of 0.226 mg h^?1g^?1, 35% higher than biotransformation without product removal. The equilibrium change and membrane fouling caused by biomass were not significant. It was possible to mathematically simulate the whole course of the extractive biotransformation with good agreement with experimental data. CONCLUSION: Bioreductive production of 1‐phenylethanol is more effective when using periodic membrane extraction of the product from the fermentation broth, which gives higher reaction rate, higher yield and simpler downstream process than biotransformation without product removal. Copyright © 2012 Society of Chemical Industry     

Corrosion behaviour of Ni-based superalloys in molten FLiNaK salts

High-temperature corrosion tests of alloys, Nimonic 80A, Inconel 718 and Inconel C-276, were investigated at 680°C in molten alkali fluoride salt (LiF–NaF–KF: 46.5–11.5–42%) environment. In this work, techniques included were weight loss measurements and potentiodynamic polarisation curves measurements. Inconel C-276 and Inconel 718 showed better corrosion resistance, while Nimonic 80A exhibited comparatively lower corrosion resistance. The high-temperature corrosion behaviour was observed using measurements of the oxide morphology and thickness. The corrosion rates were determined by recording the weight changes of the sample alloys at different time intervals. Microstructural examination showed the depletion of Cr near the surface of the alloys and hence the significant weight loss in the early stages of corrosion tests. The corrosion mechanism of the alloys is discussed in detail.     

Functionalization of polylactic acid through direct melt polycondensation in the presence of tricarboxylic acid

The goal of the article was to describe the preparation of carboxyl‐functionalized polylactic acid (PLA) through the method of direct melt copolycondensation of lactic and citric acid (CA). In addition, detailed study of copolycondensation process, its limitations and investigation of the reaction products properties are another issue this article deals with. The effect of tricarboxylic CA on the resulting properties of the functionalized lactic acid (LA) polycondesates was studied in a wide range of LA/CA molar ratios. The influence of CA on molecular weight, thermal and physicochemical properties, and chemical structure of the products was investigated, using viscometric measurements of the polymer solutions, gel permeation chromatography, ¹H nuclear magnetic resonance spectroscopy, differential scanning calorimetry, acidity number determination, and Fourier‐transform infrared and ultraviolet spectroscopy. The results show the significant effect of CA on the structure and physicochemical properties as well as high efficiency of functionalization. Furthermore, a branched structure was detected at low CA concentrations, while higher CA content leads to termination of the polycondensates chains by citryl units and a reduction in the molecular weight. Here, insights on the characterization methods of PLA‐based materials are given by various experimental techniques. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011