53 research outputs found

    Identification and Testing of Amines for Steam Generator Corrosion and Fouling Control

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    AECL and EPRI have been evaluating candidate amines for control of corrosion and fouling in recirculating nuclear steam generators. To permit an unambiguous ranking of the suitability of the candidate amines, the characteristics of base strength, volatility, price, steam generator fouling, cost of associated condensate and blowdown polishing, toxicity and ecotoxicity have been summarized in a single numerical index. The majority of the data required for the calculation of the index is available in the literature. The effect of amine on steam generator fouling has been measured using a recirculating loop at AECL under flow boiling conditions. The loop results coupled with steam generator modelling indicate a significant reduction in steam generator fouling rates when optimized chemistry is used. The calculated reduction in the cost of steam generator fouling and corrosion control for several amines and amine mixtures is given

    Nonparametric nonlinear model predictive control

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    Model Predictive Control (MPC) has recently found wide acceptance in industrial applications, but its potential has been much impeded by linear models due to the lack of a similarly accepted nonlinear modeling or databased technique. Aimed at solving this problem, the paper addresses three issues: (i) extending second-order Volterra nonlinear MPC (NMPC) to higher-order for improved prediction and control; (ii) formulating NMPC directly with plant data without needing for parametric modeling, which has hindered the progress of NMPC; and (iii) incorporating an error estimator directly in the formulation and hence eliminating the need for a nonlinear state observer. Following analysis of NMPC objectives and existing solutions, nonparametric NMPC is derived in discrete-time using multidimensional convolution between plant data and Volterra kernel measurements. This approach is validated against the benchmark van de Vusse nonlinear process control problem and is applied to an industrial polymerization process by using Volterra kernels of up to the third order. Results show that the nonparametric approach is very efficient and effective and considerably outperforms existing methods, while retaining the original data-based spirit and characteristics of linear MPC

    Social change and the family: Comparative perspectives from the west, China, and South Asia

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    This paper examines the influence of social and economic change on family structure and relationships: How do such economic and social transformations as industrialization, urbanization, demographic change, the expansion of education, and the long-term growth of income influence the family? We take a comparative and historical approach, reviewing the experiences of three major sociocultural regions: the West, China, and South Asia. Many of the changes that have occurred in family life have been remarkably similar in the three settings—the separation of the workplace from the home, increased training of children in nonfamilial institutions, the development of living arrangements outside the family household, increased access of children to financial and other productive resources, and increased participation by children in the selection of a mate. While the similarities of family change in diverse cultural settings are striking, specific aspects of change have varied across settings because of significant pre-existing differences in family structure, residential patterns of marriage, autonomy of children, and the role of marriage within kinship systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45661/1/11206_2005_Article_BF01124383.pd
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