关键词： Hydro-economic model   Uncertainty quantification   Decision making   Surface-water/groundwater model   Computable general equilibrium model   Optimization under uncertainty  

摘要： This paper presents a framework to systematically compare the contributions to uncertainty in hydro-economic simulated outputs from the uncertainty surrounding input parameters employed by the hydrologic and economic models independently. We consider an illustrative case study example. An integrated modeling framework is adopted, involving a surface-water/groundwater nitrate-transport model, and a multi-regional Computable General Equilibrium model. Environmental uncertainty contributions are determined by optimizing nitrate-loading under ecologically-relevant constraint uncertainty at varying risk stancesthe results of which are mapped to economic outputs. Economic uncertainty contributions are quantified through Monte-Carlo sampling of variables associated with social-accounting matrices and substitution and transformation elasticities. Results indicate that, at the study-area scale, the environmental contribution to Gross-Regional Product uncertainty is generally larger compared to that of economic uncertainty. Nevertheless, the reliability of hydro-economic outputs is shown to be highly dependent on environmental and economic sources of uncertainty. On the basis of our case study findings, we recommend that commensurate effort be focused toward enhanced assimilation of observation data in both types of models to reduce their respective uncertainties.

关键词： Circular economy (CE)   Zero waste   Waste management   Wastewater   European Union (EU)  

摘要： One of the key elements in the transformation towards a circular economy (CE) is providing more sustainable practices for resources and waste management. Improvement actions focused on transformation towards a CE should be targeted at all groups of materials and waste. As water is essential for human survival and well-being and plays a significant role in sustainable development (SD), the actions related to the reuse of water and the recovery of raw materials from wastewater and other water-based waste should be taken. The paper presents a proposition for a new CE model framework in the water and wastewater sector, which includes the six following actions: reduction-prevent wastewater generation in the first place by the reduction of water usage and pollution reduction at source;reclamation (removal)-an application of effective technologies for the removal of pollutants from water and wastewater;reuse-reuse of wastewater as an alternative source of water supply (non-potable usage), recycling-recovery of water from wastewater for potable usage;recovery-recovery of resources such as nutrients and energy from water-based waste, and rethink-rethinking how to use resources to create a sustainable economy, which is `free` of waste and emissions. The novelty of the proposed CE model framework is that it presents possible ways of implementing CE principles in the water and wastewater sector, with a strong emphasis not only technological but also organisational and societal changes. Application of the proposed model may help to further transform the European economy to the CE model. Moreover, the indicated model can be significant tool supporting an assessment of local or regional progress towards CE in the water and wastewater sector and further environmental management and planning.

摘要： Background Non-alcoholic steatohepatitis (NASH) is a severe, typically progressive form of non-alcoholic fatty liver disease (NAFLD). The global prevalence of NASH is increasing, driven partly by the global increase in obesity and type 2 diabetes mellitus (T2DM), such that NASH is now a leading cause of cirrhosis. There is currently an unmet clinical need for efficacious and cost-effective treatments for NASH;no pharmacologic agents have an approved indication for NASH. Objective Our objective was to summarise and critically appraise published health economic models of NASH, to evaluate their quality and suitability for use in the assessment of novel treatments for NASH, and to identify knowledge gaps, challenges and opportunities for future modelling. Methods A systematic literature review was performed using the MEDLINE, Embase, Cochrane Library and EconLit databases to identify published health economic analyses in patients with NAFLD or NASH. Supplementary hand searches of grey literature were also performed. Articles published up to November 2019 were included in the review. Quality assessment of identified studies was also performed. Results A total of 19 articles comprising 16 unique models including either NAFLD as a whole or NASH alone were included in the review. Structurally, most models had a state-transition component;in terms of health states, two different approaches to early disease states were used, modelling either progression through fibrosis stages or NAFLD/NASH-specific health states. Conditions that frequently co-exist with NASH, such as obesity, T2DM and cardiovascular disease were not captured in models identified here. Late-stage complications such as cirrhosis, decompensated cirrhosis and hepatocellular carcinoma were consistently included, but input data (e.g. costs, utilities and transition probabilities) for late-stage complications were frequently sourced from other liver disease areas. The quality of included studies was heterogenous,

关键词： 清洁生产   循环经济   生态农业   资源化   模型  

摘要： 清洁生产与循环经济是众多高校环境类专业的专业必修课,也是化工、制药等专业的专业选修课.建立清洁生产与循环经济模型,是实现循环经济的重要途径.文中结合安徽的具体地域特点,分别构建了皖南空间垂直复合循环经济模型和合肥市柿树岗乡生态农业循环经济模型作为教学案例.通过垂直空间和水平空间搭建农作物生产与家禽业生产的资源循环利用结构,通过沼气池实现了有机固废与沼气能的转换,通过特色农业和特色文化,有效的拓展了农业生态系统的循环链.这些教学模型案例的构建,可以让学生深入领会和掌握清洁生产与循环经济体系.

关键词： Distributed Lyapunov-based economic model predictive control (DLEMPC)   Input delay   Optimization   Feasibility   Stability  

摘要： In industrial processes, time-delay often occurs in many operations and increases difficulty to control these dynamical systems. In this paper, we propose a distributed Lyapunov economic model predictive control (DLEMPC) method for continuous-time nonlinear systems with input time-delay. Next, we establish sufficient conditions to make the system feasible and stable under our proposed DLEMPC strategy, and bound system state in a region which contains the provided original value. Finally, a chemical process simulation is given to illustrate our theoretical results. (C) 2019 ISA. Published by Elsevier Ltd. All rights reserved.

关键词： Direct Contact Membrane   Distillation (DCMD)   Observer-based Economic Model   Predictive Control (OEMPC)   Observer design   Differential Algebraic Equations (DAEs)  

摘要： In this work, we present an Observer-based Economic Model Predictive Control (OEMPC) scheme for Direct Contact Membrane Distillation (DCMD). To compute control actions via MPC strategy, full knowledge of the system states is necessary to predict the future evolution of the system. However, the full state measurement for DMCD is either difficult or costly. In this work, an integrated framework of an observer design and EMPC paradigm is proposed for the DMCD process. Numerical simulations are presented to illustrate the performance of the proposed observer design. Closed-loop simulations show that the proposed OEMPC scheme was able to operate the process economically while satisfying process and input constraints. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

关键词： Economics   Batteries   Optimization   Power system stability   Photovoltaic systems   Mathematical model   Wind-photovoltaic-battery microgrid power system   distributed economic model predictive control   nonlinear system   economic cost function   dual-mode   stability  

摘要： This paper proposed a dual-mode distributed economic model predictive control (EMPC) for a nonlinear wind-photovoltaic-battery microgrid power system (WPB-MPS). The communications between each subsystem are taken into consideration and the economic objectives that are established based on the aspects that: satisfy the total demand;make full use of the power generated by the WPB-MPS;optimize the battery's state of charge;and reduce the fluctuation of power exchange with the grid. The subsystem-based EMPCs work iteratively and cooperatively to solve the economic objective functions, which reflect economies of the system and not necessary to drive the system to a certain steady state as hierarchical control. A dual-mode Lyapunov-based EMPC has been formulated to guarantee the stability of the system with disturbance, and under certain conditions, the closed-loop system state can be driven and hold in a safe region. Simulations demonstrate the advantages and efficiency of the proposed method.

关键词： Growth models   group actions   invariance and symmetry properties   mathematical modelling in economics   production functions  

摘要： In this paper, we extend the work by Sato devoted to the development of economic growth models within the framework of the Lie group theory. We propose a new growth model based on the assumption of logistic growth in factors and derive the corresponding production functions, as well as a compatible notion of wage share. In the process, it is shown that the new functions compare reasonably well against relevant economic data. The corresponding problem of maximisation of profit under conditions of perfect competition is solved with the aid of one of these functions. In addition, it is explained in reasonably rigorous mathematical terms why Bowley's law no longer holds true in the post-1960 data.

关键词： Numerical optimal control   NLP sensitivity   Economic MPC   Path-following  

摘要： We present a sensitivity-based nonlinear model predictive control (NMPC) algorithm and demonstrate it on a case study with an economic cost function. In contrast to existing sensitivity-based approaches that make strong assumptions on the underlying optimization problem (e.g. the linear independence constraint qualification implying unique multiplier), our method is designed to handle problems satisfying a weaker constraint qualification, namely the Mangasarian-Fromovitz constraint qualification (MFCQ). Our nonlinear programming (NLP) sensitivity update consists of three steps. The first step is a corrector step in which a system of linear equations is solved. Then a predictor step is computed by a quadratic program (QP). Finally, a linear program (LP) is solved to select the multipliers that give the correct sensitivity information. A path-following scheme containing these steps is embedded in the advanced-step NMPC (asNMPC) framework. We demonstrate our method on a large-scale case example consisting of a reactor and distillation process. We show that LICQ does not hold and the path-following method is able to accurately approximate the ideal solutions generated by an NLP solver. (C) 2020 The Authors. Published by Elsevier Ltd.

关键词： Beef production systems   Bio-economic modelling   Finishing stage   Economic viability  

摘要： Global population growth together with rising incomes is increasing the demand for meat-based products. This increases the need to optimize livestock production structures, whilst ensuring viable returns for the farmers. On a global scale, beef producers need tools to assist them to produce more high-quality products whilst maintaining economic efficiency. The Grange Scottish Beef Model (GSBM) was customized to simulate beef finishing enterprises using data from Scottish beef finishing studies, as well as agricultural input and output price datasets. Here we describe the model and its use to determine the cost-effectiveness of alternative current management practices (e.g. forage- and cereal-based finishing) and slaughter ages (i.e. short, medium or long finishing duration). To better understand drivers of profitability in beef finishing systems, several scenarios comparing finishing duration, gender, genetic selection of stock for growth rate or feed efficiency, as well as financial support were tested. There are opportunities for profitable and sustainable beef production in Scotland, for both cereal and forage based systems, particularly when aiming for a younger age profile at slaughtering. By careful choice of finishing systems matched to animal potential, as well as future selection of high performing and feed efficient cattle, beef finishers will be able to enhance performance and increase financial returns.