Learning soft computing control strategies in a modular neural network architecture

Modelling and control of nonlinear dynamical systems is a challenging problem since the dynamics of such systems change over their parameter space. Conventional methodologies for designing nonlinear control laws, such as gain scheduling, are effective because the designer partitions the overall complex control into a number of simpler sub-tasks. This paper describes a new genetic algorithm based method for the design of a modular neural network (MNN) control architecture that learns such partitions of an overall complex control task. Here a chromosome represents both the structure and parameters of an individual neural network in the MNN controller and a hierarchical fuzzy approach is used to select the chromosomes required to accomplish a given control task. This new strategy is applied to the end-point tracking of a single-link flexible manipulator modelled from experimental data. Results show that the MNN controller is simple to design and produces superior performance compared to a single neural network (SNN) controller which is theoretically capable of achieving the desired trajectory. (C) 2003 Elsevier Ltd. All rights reserved.

Phenotypic diversity amongst strains of Pleurotus sajor-caju: implications for cultivation in and environments

In arid regions, biodiversity and biomass are limited by water availability, and this problem has been compounded by desertification associated with global climate change. The saprotrophic macrofungi that are indigenous to hot subtropical and tropical regions, such as Pleurotus spp., can play key roles in water sequestration, nutrient cycling, human nutrition, and bioremediation of waste materials. We studied 15 strains of Pleurotus sajor-caju, a widespread and phenotypically-diverse species, to establish variability in growth response and primordium development over a range of stress parameters: osmotic potential (-0.5 to -5 MPa), temperature (5-40 degrees C) and pH (2-12). The initiation of primordia precedes basidiome production and therefore represents a key stage in bioremediation strategies and fungi-driven nutrient cycles. Primordia were produced at low pH (4-6), at suboptimal growth temperatures (<or =25 degrees C), and under moderate water stress (-0.5 to -3.5 MPa). Although the growth windows for different strains were similar, their maximum growth rates and the optimum conditions for growth varied. We discuss the phenotypic diversity of Pleurotus strains and discuss their potential for cultivation, bioremediation and ecological regeneration.

The importance of reproductive strategies in population genetic approaches to conservation: an example from the marine angiosperm genus Zostera

Knowledge of the levels of genetic diversity maintained in natural populations can play a central role in conservation programmes, particularly in threatened habitats or species. Fluctuations in population size can lead to loss of variation and, consequently, increase the risk of extinction. We have examined whether such a genetic bottleneck has occurred in populations of two species in the seagrass genus Zostera, which are believed to have been affected by an outbreak of wasting disease at the start of the last century. A test for heterozygote excess at five nuclear microsatellite loci did not suggest the occurrence of a genetic bottleneck, but analysis of seven chloroplast microsatellite loci and sequence data from two regions did suggest a bottleneck in the chloroplast genome. Extremely low levels of between-population diversity suggest that all subpopulations can be treated as a single management unit for each species. Comparable levels of nuclear genetic diversity were found in the three populations of the primarily sexual Zostera marina var. angustifolia studied but a wider range of within-population diversity was found in Zostera noltii, which displays both. sexual and vegetative reproductive strategies. This may be due to an increase in sexual recruitment due to localised fresh water inflow into the study site near to the most diverse population. Such populations should be prioritised as source material for any replanting or remediation due to natural or anthropogenic loss of Zostera beds in the area.

Insight into the key aspects of the regeneration process in the NOx storage reduction (NSR) reaction probed using fast transient kinetics coupled with isotopically labelled (NO)-N-15 over Pt and Rh-containing Ba/Al2O3 catalysts

For the first time, the coupling of fast transient kinetic switching and the use of an isotopically labelled reactant (15NO) has allowed detailed analysis of the evolution of all the products and reactants involved in the regeneration of a NOx storage reduction (NSR) material. Using realistic regeneration times (ca. 1 s) for Pt, Rh and Pt/Rh-containing Ba/Al2O3 catalysts we have revealed an unexpected double peak in the evolution of nitrogen. The first peak occurred immediately on switching from lean to rich conditions, while the second peak started at the point at which the gases switched from rich to lean. The first evolution of nitrogen occurs as a result of the fast reaction between H2 and/or CO and NO on reduced Rh and/or Pt sites. The second N2 peak which occurs upon removal of the rich phase can be explained by reaction of stored ammonia with stored NOx, gas phase NOx or O2. The ammonia can be formed either by hydrolysis of isocyanates or by direct reaction of NO and H2.

The study highlights the importance of the relative rates of regeneration and storage in determining the overall performance of the catalysts. The performance of the monometallic 1.1%Rh/Ba/Al2O3 catalyst at 250 and 350 °C was found to be dependent on the rate of NOx storage, since the rate of regeneration was sufficient to remove the NOx stored in the lean phase. In contrast, for the monometallic 1.6%Pt/Ba/Al2O3 catalyst at 250 °C, the rate of regeneration was the determining factor with the result that the amount of NOx stored on the catalyst deteriorated from cycle to cycle until the amount of NOx stored in the lean phase matched the NOx reduced in the rich phase. On the basis of the ratio of exposed metal surface atoms to total Ba content, the monometallic 1.6%Pt/Ba/Al2O3 catalyst outperformed the Rh-containing catalysts at 250 and 350 °C even when CO was used as a reductant.

One-pot multistep synthetic strategies for the production of fenpropimorph using an ionic liquid solvent

The one-pot synthesis of the fungicide fenpropimorph has been achieved using two different synthetic strategies in an ionic liquid. The first pathway consists of a Heck coupling followed by reductive amination; the second pathway consists of an aldol condensation followed by hydrogenation/reductive amination. Homogeneous and heterogeneous palladium catalysts have been utilised in the ionic liquid to provide a catalyst/solvent system that is suitable for recycling and process optimisation.

Vision and reality: community involvement in Irish urban regeneration

This article examines the processes and outcomes of community involvement in six Irish urban regeneration case studies, three in Dublin and three in Belfast. The findings are part of a wider study using a Complex Adaptive Systems perspective to analyse public sector decision making. Key points included: (1) the community ‘vision’ of the regeneration as an emergent property, which converged towards the vision held by the implementing agencies in the four most successful programmes; and (2) the identification of three features that contribute to non-linear (unpredictable) behaviour: a history of community involvement; the availability of resources; and the intervention of key individuals at crisis points.

Authenticity and stakeholder planning in the segregated city

This paper is concerned with the production and reproduction of segregation in Northern Ireland and how territoriality has impacted on the Protestant community in Derry/Londonderry. The city was pivotal in the development of the most recent conflict, has a majority Catholic population, sits on a contested border and has attempted to respond to expressions of alienation that have emerged from the Protestant community. The research used multiple methods to understand the nature of alienation and exclusion using secondary data, a quantitative household survey, in-depth interviews and focus
groups. This empirical commitment was important in identifying and unpacking the claims of various stakeholders with an interest in the use and development of the area. It is argued here that a version of Collaborative Planning provides a loosely articulated conceptual and methodological framework for drawing Protestant communities into the wider planning framework for the city. The data, however, suggest that the nature of stakeholders is complex and contradictory, and discursive practice that seeks consensus has limits, especially in validating or legitimating the assertions of self-acclaimed stakeholders. The research shows that the Protestant community had declined and residualised but had little experience of direct conflict with the majority community. Moreover, the Protestant community is now more likely to use the city centre (a predominantly Catholic space) for consumption and work, and its demographic decline has stopped. These findings are important as policy responses and community relations programmes have failed to distinguish between measurable socioeconomic needs and claims concerning ethnic alienation based on emotion and manipulation. Such alienation has tended to bolster single identity communities who have little or no prospect and/or knowledge of the collaborative efforts required to deliver meaningful regeneration. More realistic strategies based on agonism focus attention on power relations and the authenticity of positions adopted by competing interests in land use management and change. The paper concludes by highlighting the need to acknowledge and value contestation but to challenge sectarian discourses represented as legitimate claims about community needs and priorities.

Integrating Ballymun? Flawed progress in Ireland's largest estate regeneration scheme

Urban regeneration in the Republic of Ireland takes place in the context of the rapid, ‘Celtic Tiger’ economic growth of the 1990s. The boom transformed Irish society and led to greater affluence for many people, along with continuing and arguably worsening inequality for those excluded from its opportunities. In particular, Ireland’s small social rented sector has become the focus of the country’s most concentrated poverty and social exclusion. The Ballymun regeneration programme in North Dublin aims to facilitate physical, social and economic change in order to integrate the area more closely with the
more affluent surrounding suburbs. This article reviews the issues involved in restructuring such a large area of social exclusion within a rapidly changing European capital city, using a framework that disaggregates the concept of integration into three elements: market, citizenship and reciprocity. With just over half the physical refurbishment complete, progress has been made but some fundamental issues remain. The article concludes that although substantial advancement has been made with physical regeneration, progress with wider economic and social integration has been uneven and in some cases flawed.

Identifying strategies to maximise recruitment and retention of practices and patients in a multicentre randomised controlled trial of an intervention to optimise secondary prevention for coronary heart disease in primary care.

Background Recruitment and retention of patients and healthcare providers in randomised controlled trials (RCTs) is important in order to determine the effectiveness of interventions. However, failure to achieve recruitment targets is common and reasons why a particular recruitment strategy works for one study and not another remain unclear. We sought to describe a strategy used in a multicentre RCT in primary care, to report researchers’ and participants’ experiences of its implementation and to inform future strategies to maximise recruitment and retention. Methods In total 48 general practices and 903 patients were recruited from three different areas of Ireland to a RCT of an intervention designed to optimise secondary prevention of coronary heart disease. The recruitment process involved telephoning practices, posting information, visiting practices, identifying potential participants, posting invitations and obtaining consent. Retention involved patients attending reviews and responding to questionnaires and practices facilitating data collection. Results We achieved high retention rates for practices (100%) and for patients (85%) over an 18-month intervention period. Pilot work, knowledge of the setting, awareness of change in staff and organisation amongst participant sites, rapid responses to queries and acknowledgement of practitioners’ contributions were identified as being important. Minor variations in protocol and research support helped to meet varied, complex and changing individual needs of practitioners and patients and encouraged retention in the trial. A collaborative relationship between researcher and practice staff which required time to develop was perceived as vital for both recruitment and retention. Conclusions Recruiting and retaining the numbers of practices and patients estimated as required to provide findings with adequate power contributes to increased confidence in the validity and generalisability of RCT results. A continuous dynamic process of monitoring progress within trials and tailoring strategies to particular circumstances, whilst not compromising trial protocols, should allow maximal recruitment and retention.

Presence of arsenic in agricultural products from arsenic-endemic areas and strategies to reduce arsenic intake in rural villages

About 100 million rural people in Asia are exposed to arsenic (As)-polluted drinking water and agricultural products. Total and inorganic arsenic (t-As and i-As) intake mainly depend on the quality of drinking and cooking waters, and amounts of seafood and rice consumed. The main problems occur in countries with poor water quality where the population depends on rice for their diet, and their t-As and i-As intake is high as a result of growing and cooking rice in contaminated water. Workable solutions to remove As from water and breeding rice cultivars with low As accumulation are being sought. In the meantime, simple recommendations for processing and cooking foods will help to reduce As intake. For instance, cooking using high volumes of As-free water may be a cheap way of reducing As exposure in rural populations. It is necessary to consider the effects of cooking and processing on t-As and i-As to obtain a realistic view of the risks associated with intake of As in Asendemic areas.