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© 2016 Elsevier Ltd. The concept of eco-industrial park (EIP) has recently become the subject of a great deal of attention from industry and academic research groups. This paper proposes a series of systematic approaches for multi-level modelling and optimisation in EIPs. The novelties of this work include, (1) building a four-level modelling framework (from unit level to process level, plant level and industrial network level) for EIP research, (2) applying advanced mathematical modelling methods to describe each level operation, (3) developing efficient methodologies for solving optimisation problems at different EIP levels, (4) considering symbiotic relations amongst the three networks (material, water and energy networks) at the top EIP level with the boundary conditions of economic, social and legal requirements. For methodology demonstration, two cases at process level and industrial network level respectively are tested and solved with the developed modelling and optimisation strategies. Finally, the challenges and applications in future EIP research are also discussed, including data collection, the extension of the current networks to EIPs, and the feasibility of the proposed methodologies for complex EIP problems. The extended EIPs include the combination of material exchanges, energy systems and waste-water treatment networks. The aspects considered for future industrial ecology are carbon emission, by-product reuse, water consumption, and energy consumption. The main object of this paper is to explain the detailed model construction process and the development of optimisation approaches for a complex EIP system. In future work, this system is expected to share services, utility, and product resources amongst industrial plants to add value, reduce costs, improve environment, and consequently achieve sustainable development in a symbiosis community.

BACKGROUND: Successive quinquennial National Infant Feeding Surveys have provided a valuable picture of national and regional variations in infant feeding practices within the United Kingdom. Social variation in breastfeeding has been recognised to be an important source of health inequalities in childhood by the Independent Inquiry into Inequalities in Health Report. AIM: To determine the prevalence of breastfeeding at birth and at four months in a sample of women from urban general practices, its variation between practices, and relation to practice population deprivation scores. To report the timing of introduction of solid feeds. DESIGN OF STUDY: Cross-sectional questionnaire survey based on a random cluster sample. SETTING: Women with infants aged four months in general practices in South London. METHOD: Mode of infant feeding at birth and four months, and time of introduction of solids. Jarman score as a measure of practice population deprivation. Housing tenure, maternal ethnic group, and maternal age at leaving full-time education. RESULTS: Twenty-five general practices were sampled. Median practice Jarman score was 15.0 (interquartile range [IQR] = 12.6-21.9). Responses were received from 1053 out of 1532 mothers approached (69%). Of these, 87% (897) had breastfed at birth, while 59% (609) were still breastfeeding their babies at four months. Mothers in rented accommodation were less likely to breastfeed than owner-occupiers (odds ratio [95% CI] = 0.52 [0.37-0.74]), as were women of white, compared with those of black, ethnic origin (odds ratio [95% CI] = 0.55 [0.36-0.82]). Those who completed up to two years and more than two years education after the age of 16 were 2.94 (95% CI = 1.85-4.66) and 9.25 (95% CI = 6.02-14.21) more likely to breastfeed at four months, respectively, than mothers whose formal education was completed at or before 16 years. Practice-specific rates of breastfeeding ranged from 71% to 100% at birth (median 87%; IQR = 79-93%) and 22% to 83% at four months (median 61%; interquartile range = 47-66%). The intra-practice correlation coefficient for breastfeeding at four months was 0.052 (within-cluster variance = 0.23, between-cluster variance = 0.013). There was no association between breastfeeding at four months and practice-specific Jarman score. Median age of starting solids was 16 weeks (IQR = 15-17 weeks). CONCLUSIONS: Housing tenure, maternal education, and ethnic group are significantly associated with breastfeeding prevalence at four months. Between-practice variation in breastfeeding prevalence is not associated with measures of practice population deprivation, as assessed by Jarman scores. Consideration should be given to including information on maternal ethnic group and housing tenure in future National Infant Feeding Surveys. Current weaning practices fall short of the recommendation of the World Health Assembly.