An exploration of the potential for re-distributed manufacturing to contribute to a sustainable,resilient city*

Abstract

Re-distributed manufacturing (RDM), broadly described as manufacturing done at a smaller-scale and locally, could be beneficial to business and urban society through creating jobs, reducing the environmental impacts of production, and improving resilience to future disturbances. Consideration of RDM within a city-region requires the consideration of a wide range of issues – societal, technical, economic and environmental. This paper presents the results of a study into the potential for RDM to contribute to a sustainable, resilient city in the face of a range of expected future disturbances on the city and on manufacturing sectors. The study took an integrated assessment approach which incorporated the development of a conceptual framework; a ‘strawman’ causal loop diagram which was reviewed by participants in a workshop; and a stock and flow system dynamics model that represents our understanding about the structure and behaviour of urban manufacturing. Several key themes emerged: similarities between RDM and traditional manufacturing, availability of physical space for RDM to be done, achieving urban resilience through RDM by enabling responsiveness to disturbances, changes in environmental impacts from production, additions or losses in jobs, the competitiveness of local manufacturing, and skills and innovation for RDM technologies. Further work is recommended.     

长江靖江段刀鲚捕捞量的时间变化及相关环境因子分析

江苏靖江段位于长江近口段,是长江刀鲚渔汛最集中的水域。调查了靖江段2008、2009、2012~2015年6个渔汛期的捕捞数据,采用广义可加模型(GAM模型)分析了刀鲚捕捞量与靖江段表层水温、潮差、气压、降水量、浑浊度、CODMn等环境因子之间的相关性。调查显示,靖江段每年发放刀鲚专项渔业捕捞证84~95本,平均年作业天数28~43 d,2012~2015年的作业天数比2008~2009年明显下降。6个渔汛期刀鲚的年捕捞量变幅为3.71~17.38万尾和3.61~18.26 t,除2013年外,年捕捞量总体上仍呈下降趋势。采用GAM模型对10艘持证渔船的刀鲚日捕捞量与环境因子之间的相关性分析显示,日捕捞量随水温的升高而递增,汛期78.8%的产量在15~23.2℃水温范围获得。而当水温低于10℃时,空网率上升,仅获得5.7%的汛期产量。表明当水温不足10℃时,刀鲚可暂时停止其生殖洄游过程。分析还显示,69.1%的汛期产量在2.0 m以上的大潮差期获得,表明潮汐亦是影响刀鲚日捕捞量的重要因子。低浊度及气压、降水量、CODMn等对刀鲚的日捕捞量无显著性影响,但当浊度大于100 NTU时,日捕捞量迅速降低。可见,水温、潮差和高浑浊度是影响长江靖江段汛期刀鲚捕捞量的关键环境因子。     

Drying of salted silver jewfish in a hybrid solar drying system and under open sun: Modeling and performance analyses

This study investigated the thin-layer drying kinetics of salted silver jewfish in a hybrid solar drying system and under open sun. Ten drying models were compared with experimental data of salted silver jewfish drying. A new model was introduced, which is an offset linear logarithmic (offset modified Page model). The fit quality of the models was evaluated using the coefficient of determination (R²), root mean square error (RMSE), and sum of squared absolute error (SSAE). The result showed that Midilli et al. model and new model were comparable with two or three-term exponential drying models. This study also analyzed energy and exergy during solar drying of salted silver jewfish. Energy analysis throughout the solar drying process was estimated on the basis of the first law of thermodynamics, whereas exergy analysis during solar drying was determined on the basis of the second law of thermodynamics. At an average solar radiation of 540 W/m² and a mass flow rate of 0.0778 kg/sec, the collector efficiency and drying system efficiency were about 41% and 23%, respectively. Specific energy consumption was 2.92 kWh/kg. Moreover, the exergy efficiency during solar drying process ranged from 17% to 44%, with an average value of 31%. The values of improvement potential varied between 106 and 436 W, with an average of 236 W.     

A probabilistic model for the carry-over of PCDD/Fs from feed to growing pigs

When food producing animals are contaminated with PCDD/F congeners, information on the contaminant’s concentration in the bodies of the animals at time of slaughter is needed for risk management purposes. We have developed a mathematical model for the kinetics of PCDD/Fs in growing pigs in case of contaminated feed fed for a limited duration of time. This model allows the prediction of concentrations in body fat. It considers absorption fractions of PCDD/Fs, clearance by metabolism, dilution by growth and excretion through fecal fat. The model parameters were calibrated by fitting the model to experimental data. On the basis of this toxicokinetic model a probabilistic model has been constructed. The probabilistic model handles the parameters with appropriate probability distributions and Monte-Carlo simulation technique, providing for realistic situations with many animals and a range of contaminations and feeding intervals. We applied the new model to describe the German dioxin incident of winter 2010/2011 and discuss its viability as decision tool. The approach demonstrated here is a showcase how a risk assessment in the case of contaminated feeding can be performed.     

我国西北地区退耕地植被恢复基本途径与模式探讨

本文在试验研究，实地考察的基础上，基于中国西部退奈还林还草工程的实背景，现状及研究基础，通过对国外相关实中践进行分析，提出了西北地区退耕地植被恢复的思路和“以封山育林为主，辅之以人工措施”的基本建设，并提出了不同景观立地条件下的56种植被恢复模式。     

Deterministic and Stochastic Simulations for Solid Waste Collection Systems – A SWIM Approach

The SWIM model is the first systems model in Australia that deals with integrated waste management systems. The main modelling approach adopted is simulation, which is based on both deterministic and stochastic models for collection systems.These models are described in this paper, after a number of modelling approaches are reviewed. An example of the application of the SWIM model is given, and planned extensions to the SWIM model are briefly outlined.     

Modeling Waste Incineration for Life-Cycle Inventory Analysis in Switzerland

This paper proposes a mathematical model for life-cycle inventory analysis (LCI) of waste incineration in Switzerland. In order to model conventional and new incineration technologies adequately, fundamental aspects of the different technologies relevant for the LCI are discussed. The environmental impact of these technologies strongly depends on the assessment of the long-term emissions of the solid incineration residues and is therefore related to value based decisions about the time horizon considered. The article illustrates that the choice of the landfill model has a significant influence on the results of life-cycle assessment of waste incineration.     

Regression Analysis Model Applied to Biomonitoring Studies

A regression model is proposed for studying the relationship between trace metals concentrations and weights of individuals of Monodonta turbinata (Born), a gastropod mollusc used as a trace metal biomonitor of marine coastal areas. The model herein presented was developed including sites as reference factors and showed very good correlations. The prevision model of contamination gave good results for this kind of pollutants, and it can be used as a tool for monitoring programmes.     

The Development of a Prediction Model for the Kinetic Constant of Chlorinated Aliphatic Hydrocarbons

Kinetic constants are important design parameters to determine the degradation of a substrate in biological treatment systems. The objective of this study was to develop a regression model using a quantitative structure–activity relationship technique for the prediction of the first-order rate constants (k) of chlorinated aliphatic hydrocarbons (CAHs). The prediction model showed very good correlations between the measured and calculated rate constants of CAHs. It was likely that the higher-order connectivity indices were important factors for the prediction of the kinetic constants, implying more complicated connectivity indices contributed to the prediction of a biological property. This technique would provide a useful tool to establish the kinetics of other CAHs without costly or time-consuming tests.     

对纳米医学材料安全性问题的思考

笔者在综合国内外研究的基础上,从风险辨识、剂量反应阈值、接触阈值、风险评价、风险管理等5个步骤进行了危害分析和控制,提出了"人体、社会环境以及纳米医学材料"三者所构成系统的安全评价模型,认为其过程可分3步来进行;针对该模型提出建立健全相关法律、法规、质量和安全标准等8项安全对策措施,以降低纳米医学材料带来的风险。