scholarly journals Modern Modeling Paradigms Using Generalized Disjunctive Programming

Processes ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 839 ◽  
Author(s):  
Qi Chen ◽  
Ignacio Grossmann
Keyword(s):  
Model Development ◽  
Logical Structure ◽  
Disjunctive Programming ◽  
Mixed Integer ◽  
Illustrative Case ◽  
Modeling Framework ◽  
Decomposition Scheme ◽  
Solution Strategies ◽  
Generalized Disjunctive Programming ◽  
Illustrative Case Study

Models involving decision variables in both discrete and continuous domain spaces are prevalent in process design. Generalized Disjunctive Programming (GDP) has emerged as a modeling framework to explicitly represent the relationship between algebraic descriptions and the logical structure of a design problem. However, fewer formulation examples exist for GDP compared to the traditional Mixed-Integer Nonlinear Programming (MINLP) modeling approach. In this paper, we propose the use of GDP as a modeling tool to organize model variants that arise due to characterization of different sections of an end-to-end process at different detail levels. We present an illustrative case study to demonstrate GDP usage for the generation of model variants catered to process synthesis integrated with purchasing and sales decisions in a techno-economic analysis. We also show how this GDP model can be used as part of a hierarchical decomposition scheme. These examples demonstrate how GDP can serve as a useful model abstraction layer for simplifying model development and upkeep, in addition to its traditional usage as a platform for advanced solution strategies.

Generalized Disjunctive Programming: Solution Strategies

2011 ◽  
pp. 57-75 ◽  
Author(s):  
Juan P. Ruiz ◽  
Jan-H. Jagla ◽  
Ignacio E. Grossmann ◽  
Alex Meeraus ◽  
Aldo Vecchietti
Keyword(s):  
Disjunctive Programming ◽  
Solution Strategies ◽  
Generalized Disjunctive Programming ◽  
Programming Solution

scholarly journals Optimization of biogas supply networks considering multiple objectives and auction trading prices of electricity

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Jafaru Musa Egieya ◽  
Lidija Čuček ◽  
Klavdija Zirngast ◽  
Adeniyi Jide Isafiade ◽  
Zdravko Kravanja
Keyword(s):  
Organic Fertilizer ◽  
Ghg Emissions ◽  
Multiple Objectives ◽  
Electricity Production ◽  
Mixed Integer ◽  
Illustrative Case ◽  
Supply Networks ◽  
Economic Profit ◽  
Biogas Plants ◽  
Illustrative Case Study

AbstractThis contribution presents an hourly-based optimization of a biogas supply network to generate electricity, heat and organic fertilizer while considering multiple objectives and auction trading prices of electricity. The optimization model is formulated as a mixed-integer linear programming (MILP) utilizing a four-layer biogas supply chain. The model accounts for biogas plants based on two capacity levels of methane to produce on average 1 ± 0.1 MW and 5 ± 0.2 MW electricity. Three objectives are put forward: i) maximization of economic profit, ii) maximization of economic profit while considering cost/benefits from greenhouse gas (GHG) emissions (economic+GHG profit) and iii) maximization of sustainability profit. The results show that the economic profit accrued on hourly-based auction trading prices is negative (loss), hence, four additional scenarios are put forward: i) a scenario whereby carbon prices are steadily increased to the prevalent eco-costs/eco-benefits of global warming; ii) a scenario whereby all the electricity auction trading prices are multiplied by certain factors to find the profitability breakeven factor, iii) a scenario whereby shorter time periods are applied, and investment cost of biogas storage is reduced showing a relationship between cost, volume of biogas stored and the variations in electricity production and (iv) a scenario whereby the capacity of the biogas plant is varied from 1 MW and 5 MW as it affects economics of the process. The models are applied to an illustrative case study of agricultural biogas plants in Slovenia where a maximum of three biogas plants could be selected. The results hence present the effects of the simultaneous relationship of economic profit, economic+GHG profit and sustainability profit on the supply and its benefit to decision-making.

Systemic Unsustainability as a Threat to Democracy

2020 ◽  
Author(s):  
Andrea Felicetti
Keyword(s):  
Research Agenda ◽  
Ecological Crisis ◽  
Illustrative Case ◽  
Sustainability Transition ◽  
Ways Of Thinking ◽  
Illustrative Case Study ◽  
New Research

Resilient socioeconomic unsustainability poses a threat to democracy whose importance has yet to be fully acknowledged. As the prospect of sustainability transition wanes, so does perceived legitimacy of institutions. This further limits representative institutions’ ability to take action, making democratic deepening all the more urgent. I investigate this argument through an illustrative case study, the 2017 People’s Climate March. In a context of resilient unsustainability, protesters have little expectation that institutions might address the ecological crisis and this view is likely to spread. New ways of thinking about this problem and a new research agenda are needed.

The Effects of Teaching Reflection Diaries on In-Service High School Teachers in Japan

Relay Journal ◽  
2020 ◽  
pp. 80-99
Author(s):  
Naoya Shibata
Keyword(s):  
High School ◽  
High School Teachers ◽  
Illustrative Case ◽  
Teaching Beliefs ◽  
Experienced Teacher ◽  
Female Teachers ◽  
Self Confidence ◽  
Research Findings ◽  
Illustrative Case Study

Although teaching reflection diaries (TRDs) are prevalent tools for teacher training, TRDs are rarely used in Japanese secondary educational settings. In order to delve into the effects of TRDs on teaching development, this illustrative case study was conducted with two female teachers (one novice, and one experienced) at a Japanese private senior high school. The research findings demonstrated that both in-service teachers perceived TRDs as beneficial tools for understanding their strengths and weaknesses. TRDs and class observations illustrated that the novice teacher raised their self-confidence in teaching and gradually changed their teaching activities. On the other hand, the experienced teacher held firm teaching beliefs based on their successful teaching experiences and were sometimes less willing to experiment with different approaches. However, they changed their teaching approaches when they lost balance between their class preparation and other duties. Accordingly, although teachers’ firm beliefs and successful experiences may sometimes become possible hindrances from using TRDs effectively, TRDs can be useful tools to train and help teachers realise their strengths and weaknesses.

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