Optimal control of auxiliary heating of passive-solar-heated buildings

Previous papers have demonstrated that low-cost off-peak electricity can be used to provide auxiliary heating for a passive-solar-heated residence. This paper describes the development of optimal control strategies for the operation of this auxiliary heating system. The temperature in the residence throughout the day as determined by computer simulation is presented for several optimal and conventional control strategies. The optimal control strategies improved the temperature control in the building compared to the conventional strategies. All strategies were shown to depend heavily on weather prediction. Computer simulations showed that errors in weather prediction had a small effect on heating cost and a large effect on being able to maintain the desired indoor temperature.     

A framework for a limitation policy of the population exposure to natural radiation in Belgium

The conclusions are put forward that are adopted by a discussion group preparing the framework for a limitation policy of the radon problem in Belgium. Existing and future situations are treated in a coherent policy that is adequate for practical implementation. An action level is defined, together with a hierachy of levels for new constructions. The decision logic for the acceptance of building materials is explained.     

Multivariate statistical analysis of a high rate biofilm process treating kraft mill bleach plant effluent.

This study reports on a multivariate analysis of the moving bed biofilm reactor (MBBR) wastewater treatment system at a Canadian pulp mill. The modelling approach involved a data overview by principal component analysis (PCA) followed by partial least squares (PLS) modelling with the objective of explaining and predicting changes in the BOD output of the reactor. Over two years of data with 87 process measurements were used to build the models. Variables were collected from the MBBR control scheme as well as upstream in the bleach plant and in digestion. To account for process dynamics, a variable lagging approach was used for variables with significant temporal correlations. It was found that wood type pulped at the mill was a significant variable governing reactor performance. Other important variables included flow parameters, faults in the temperature or pH control of the reactor, and some potential indirect indicators of biomass activity (residual nitrogen and pH out). The most predictive model was found to have an RMSEP value of 606 kgBOD/d, representing a 14.5% average error. This was a good fit, given the measurement error of the BOD test. Overall, the statistical approach was effective in describing and predicting MBBR treatment performance.     

Combined directional and contradirectional coupling in athree-waveguide configuration

A three-waveguide coupler, combining directional and contradirectional coupling between the central and side waveguides, respectively, is discussed. Coupled-mode formalism is used to examine the superposed processes both in synchronism and near synchronism. The nature of the solution is shown to depend on the relative coupling strengths of the individual processes. For stronger contradirectional coupling, the power is divided among the three output ports, at ratios closely related to the ratio of the coupling coefficients, and with a nonperiodic, slowly varying length dependence. The coupler can thus be used as a power divider without the need for a precisely special case where the directional and contradirectional coupling coefficients are equal     

A new design of flocculation tank: the Turbomix applied to weighted flocculation.

As far as flocculation is concerned, the agglomeration of suspended particles into flocs is highly linked to the hydraulic behaviour of the agitation. The Turbomix is a special design of mixing tank; its design was developed to better control the flow during the flocculation stage. It enables a significant decrease in footprint of the process. The combination of the Turbomix and ballasted flocculation has been studied during pilot trials in terms of treatment efficiency. Its controlled hydraulic behaviour explains the efficiency of the process as proved by CFD investigation.     

Making decentralised systems viable: a guide to managing decentralised assets and risks.

Decentralised systems have the potential to provide a viable option for long term sustainable management of household wastewater. Yet, at present, such systems hold an uncertain status and are frequently omitted from consideration. Their potential can only be realised with improved approaches to their management, and improved methods to decision-making in planning of wastewater systems. The aim of this paper is to demonstrate the value of a novel framework to guide the planning of decentralised systems so that asset management and risk management are explicitly considered. The framework was developed through a detailed synthesis of literature and practice in the area of asset management of centralised water and wastewater systems, and risk management in the context of decentralised systems. Key aspects of the framework are attention to socio-economic risks as well as engineering, public health and ecological risks, the central place of communication with multiple stakeholders and establishing a shared asset information system. A case study is used to demonstrate how the framework can guide a different approach and lead to different, more sustainable outcomes, by explicitly considering the needs and perspectives of homeowners, water authorities, relevant government agencies and society as a whole.     

Dietary Fiber and Other Constituents of Some Tongan Foods

Components of dietary fiber (soluble nonstarch polysaccharide, pectin, hemicellulose, cellulose and lignin), water, energy, protein, lipid and starch were measured in banana, breadfruit, cassava, coconut, mango, pawpaw, plantain, sweet potato, taro and Pacific yam, all from the Pacific Island Kingdom of Tonga. The Tongan foods were generally higher in dietary fiber than New Zealand foods, consistent with the hypothesis that dietary fiber is an important factor contributing to a lower incidence of certain gastrointestinal disorders in Tonga, than in New Zealand.     

Book reviews

Ohne Zusammenfassung

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Book reviews

     

Some nitrosoamino acids in bacon adipose tissue and their contribution to the total N-nitroso compound concentration

Zusammenfassung Der Gehalt an Nitrosoaminosäuren und ihr Anteil an den Gesamt-N-Nitrosoverbindungen im Fettgewebe von rohem Schinkenspeck wurde untersucht. In 80% der Proben wurde ein Gehalt an Nitrosoaminosäuren von bis zu 0,2 mg/kg festgestellt. Scheinbare Gesamt-N-Nitrosoverbindungen waren in allen Proben in einer Konzentration von 0,4 bis 3,7 mg (N-NO)/kg vorhanden. Die eigentlichen Nitrosoaminosäuren machen nur etwa 1% der scheinbaren Gesamt-N-Nitrosoverbindungen aus. Die Mehrzahl der scheinbaren Gesamt-N-Nitrosoverbindungen im Fettgewebe findet sich im nichtlöslichen Bindegewebe, wobei der verbleibende Rest chloroformlöslich ist.Summary The levels of nitrosoamino acids and apparent total N-nitroso compounds in the adipose tissue of raw bacon have been examined. Nitrosoamino acids were detected in 80% of the samples in levels of up to 0.2 mg/kg. Apparent total N-nitroso compounds were present in all samples in concentrations of between 0.4 and 3.7 mg (N-NO)/kg. Nitrosoamino acids accounted for approximately only 1 % of the apparent total N-nitroso compounds. The majority of the apparent total N-nitroso compounds in the adipose tissue were associated with the insoluble connective tissue fraction, with the remainder present as chloroform soluble species.

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Einige Nitrosoaminosäuren im fettgewebe von Schinkenspeck und ihr anteil an der Konzentration der Gesamt-N-Nitrosoverbindungen

     

Long-time risk of groundwater/drinking water pollution with sulphuric compounds beneath burned peatlands in Indonesia.

Smoke-haze episodes caused by vegetation and peat fires affect parts of Indonesia every year with significant impacts on human health and climate. The forest fires 1997/1998 were by far the largest in Indonesian history, burning between 5 and 8 million hectares before they were stopped by the monsoon rains in December 1997. Fires sprang up again in 1998 on Kalimantan when monsoon rain paused. Peat forests and peatlands are in particular severely affected. In the 1997/1998 haze event, 2.1-2.5 million hectare of peat swamp forest burnt in Indonesia. The remaining ash contains high concentrations of sulphur and sulphuric compounds which eventually leach into the groundwater, thus polluting groundwater and drinking water. The thicker the peat layer is and the higher the number of fires in the respective area the more sulphuric compounds will leach into the groundwater. Risk areas for the sulphur loads of the ash are identified.