Premixed metal fibre burners based on a Pd catalyst

As an alternative to previously developed catalytic FeCrAlloy fibre mat burners based on perovskite catalysts, new catalytic burners have been developed based on Pd catalyst on lantana-stabilised Al₂O₃ and different fibre structures (NIT100A, NIT100S and NIT200S by ACOTECH NV). All development steps are considered, shifting from catalyst preparation (based on combustion synthesis of γ-Al₂O₃) to the optimisation of lantana and Pd loadings, from the definitions of the best catalyst-deposition conditions (washcoating) to the catalytic burners performances, determined in an ad hoc developed combustion chamber. The results show almost half pollutants emissions and better performance compared to various non-catalytic counterparts, especially as far as CO and NO_x emissions are concerned. Some flame instability problems were though registered, especially for one of the catalytic burner mattresses employed, at low specific power inputs and excesses of air (<375 kW/m² and <12%, respectively). Further, PdO/Pd transition is shown to influence the dynamic behaviour of the catalytic burners.     

Investigation of Petroleum Refinery Effluent Treatment in an Aerobic Fixed-film Biological System

T he feasibility of treating a synthetic toxic waste and a petroleum refinery effluent was evaluated using a four-stage, fixed-film aerated bioreactor with a 50 I capacity and a surface area-to-volume ratio of 72. The process performance at various waste strengths and influent flow rates was found satisfactory.
Organic loading proved to be a better operational or design parameter. Treatment efficiency decreased as the loading was increased. An organic loading of 42 g COD/m2d or less is recommended to ensure good quality effluent. The reactor coped with organic and hydraulic overloads because of the good oxygen transfer capacity and the considerable quantity of attached biomass attained. Staging of the reactor was effective in damping excessive loadings.
Treatment of the refinery waste in the bioreactor removed up to 80 per cent of the COD and reduced the oil, sulphide and amm.N concentrations substantially, but polishing of reactor effluent using alum treatment improved effluent quality for potential reuse.     

A knowledge-based system for sensor selection

This paper presents a Knowledge-based system (KBS) developed to allow users, who may not be knowledgeable about sensors, to select sensors suitable for their specific needs. The KBS runs on a micro-computer. The selection criteria are user specified and are based on the desired measurement parameters. The system output includes all of the operational and dimensional parameters of the recommended sensor, price, and vendor information.     

Approximate feedback linearization of discrete-time non-linear systems using virtual input direct design

The design of feedback-linearization and poles-placement controllers for discrete-time non-linear plants, using Input/Output/State measurements only, is typically addressed via indirect design. In this paper we propose the use of a new technique, based on a Virtual Input Direct Design (VID²) approach. The main feature of such a technique is to reduce the control design problem into a standard non-linear mapping approximation problem, without calling for the preliminary construction of an appropriate model of the plant. As compared with the existing methods, the new one requires less computational effort, while taking full advantage of the non-linear approximation software tools already available. In this paper, the new method is described, a simple theoretical analysis is given, and some numerical examples are presented.     

Extension of the QUASAR River-Water Quality Model to Unsteady Flow Conditions

A modification of the well-known water-quality model 'quality simulation along river systems'(QUASAR) is presented in order to extend its ability, so that it may be considered applicable under unsteady-flow conditions. An aggregated dead-zone travel-time parameter, based on (a) the kinematic wave velocity (celerity) of the flow wave and (b) the behaviour of the solute within so-called 'dead zones', has been incorporated into the existing model formulation. This extends the current continuously-stirred tank reactor-based model process to account for the behaviour of solute under unsteady-flow conditions. The enhanced water-quality model has been validated by application to the Colorado River.     

Influence of electroosmotic treatment on the hydro-mechanical behaviour of clayey silts: preliminary experimental results

Preliminary results of an investigation focused on the influence of electrokinetic treatment on the mechanical and hydraulic behaviour of clayey soils are presented. The experimental programme aims at providing a contribution to the sustainability of contaminant extraction or containment via electroosmosis. Changes in the hydraulic and mechanical properties of two illitic clayey soils, subjected to a DC electric field, were investigated. Samples of the two soils were subjected to electrokinetic filtration, for different periods of time, and under different constant loads. Afterwards, they were tested under one-dimensional compression to detect changes in stiffness and hydraulic conductivity due to the electrical treatment. After the application of a DC field for a few hours, a small reversible increment in the average soil stiffness was observed, with respect to the untreated soil, while the hydraulic conductivity was not affected substantially. Dramatic changes of the mechanical and hydraulic soil properties, correlated to changes of the soil pH, were observed following non-conditioned electrokinetic treatment with duration of the order of days.     

Environmental Effects of Hydro-Electric Power Generation in Africa and the Potential for Artificial Floods

Electricity is a fundamental requirement for economic growth, and hydro-electric power is often thought to be environmentally benign. However, the construction and operation of many hydro-power dams in Africa have had significant negative impacts on the environment and rural economies. Reduced downstream flooding has destroyed fisheries and starved the floodplain soils of moisture and nutrients. Often the worst-affected areas have no electrification and therefore do not benefit from power generation. New dams which are planned in Kenya and Tanzania have been specifically designed to make flood releases. This will allow electricity to be generated whilst maintaining a dynamic flooding pattern for the short-term economic importance of fisheries and agriculture and the longer-term importance of soil fertility and biodiversity. Involvement of local community representatives in deciding when flood waters should be released on the Phongolo River in South Africa has resulted in substantial benefits to floodplain users.     

Contamination of the Chalk Aquifer by Chlorinated Solvents: A Case Study of the Luton and Dunstable Area

A detailed investigation of contamination by chlorinated solvents of the Chalk Aquifer underlying the towns of Luton and Dunstable was undertaken to assess the extent, causes and mechanisms of pollution. The research programme incorporated land-use surveys, regional groundwater surveys, monitoring of groundwater abstraction points and aquifer profiling by means of the drilling of observation boreholes, the analysis of the recovered core material and the depth sampling of these and other boreholes.
Low-level solvent contamination of the Chalk Aquifer was found to be widespread with 'hotspots'of higher concentrations. At the drilling sites, both the saturated and unsaturated zones were contaminated with solvents, although free product was not observed. The presence of an additional contaminant, oil, at some sites was noted to influence the distribution of solvents within the aquifer.
Clean-up of the aquifer is not a practical option, and treatment of the groundwater at the abstraction points has been adopted.     

Cpk index estimation using data transformation

Process capability indices (PCIs) are used in industry to assess percentages of nonconforming parts. An underlying assumption is that the output process measurements are distributed as normal random variables. When normal distributions are assumed, but different distributions are present - such as skew, heavy-tailed, and short-tailed distributions - the percentages of nonconforming parts are significantly different than the computed PCIs indicate. Data arising from nonnormal distributions can sometimes be transformed to conform to the normality assumption and the PCI's computed for the transformed data. In this paper, the effect of the transformation on the estimate of nonconforming parts is examined for three examples of nonnormal distributions - gamma, lognormal, and Weibull. The results of this experimental analysis suggest that data transformation can be useful for estimating an interval for C_pk values and the number of nonconforming parts.     

The Landscape of microRNAs in βCell: Between Phenotype Maintenance and Protection

Diabetes mellitus is a group of heterogeneous metabolic disorders characterized by chronic hyperglycaemia mainly due to pancreatic β cell death and/or dysfunction, caused by several types of stress such as glucotoxicity, lipotoxicity and inflammation. Different patho-physiological mechanisms driving β cell response to these stresses are tightly regulated by microRNAs (miRNAs), a class of negative regulators of gene expression, involved in pathogenic mechanisms occurring in diabetes and in its complications. In this review, we aim to shed light on the most important miRNAs regulating the maintenance and the robustness of β cell identity, as well as on those miRNAs involved in the pathogenesis of the two main forms of diabetes mellitus, i.e., type 1 and type 2 diabetes. Additionally, we acknowledge that the understanding of miRNAs-regulated molecular mechanisms is fundamental in order to develop specific and effective strategies based on miRNAs as therapeutic targets, employing innovative molecules.