Dynamic participation in local energy communities with peer-to-peer trading

Background: Energy communities and local electricity markets (e.g., as peer-to-peer trading) are on the rise due to increasingly decentralized electricity generation and favorable adjustment of the legal framework in many European countries. Methods: This work applies a bi-level optimization model for dynamic participation in peer-to-peer electricity trading to determine the optimal parameters of new participants who want to join an energy community, based on the preferences of the members of the original community (e.g., environmental, economic, or mixed preference). The upper-level problem chooses optimal parameters by minimizing an objective function that includes the prosumers' cost-saving and emission-saving preferences, while the lower level problem maximizes community welfare by optimally allocating locally generated photovoltaic (PV) electricity between members according to their willingness-to-pay. The bi-level problem is solved by transforming the lower level problem by its corresponding Karush-Kuhn-Tucker (KKT) conditions. Results: The results demonstrate that environment-oriented prosumers opt for a new prosumer with high PV capacities installed and low electricity demand, whereas profit-oriented prosumers prefer a new member with high demand but no PV system capacity, presenting a new source of income. Sensitivity analyses indicate that new prosumers' willingness-to-pay has an important influence when the community must decide between two new members. Conclusions: The added value of this work is that the proposed method can be seen as a basis for a selection process between a large number of potential new community members. Most important future work will include optimization of energy communities over the horizon several years.

Hamiltonian formulation of higher rank symmetric gauge theories

Recent discussions of fractons have evolved around higher rank symmetric gauge theories with emphasis on the role of Gauss constraints. This has prompted the present study where a detailed hamiltonian analysis of such theories is presented. Besides a general treatment, the traceless scalar charge theory is considered in details. A new form for the action is given which, in $$2+1$$ 2 + 1 dimensions, yields area preserving diffeomorphisms. Investigation of global symmetries reveals that this diffeomorphism invariance induces a noncommuting charge algebra that gets exactly mapped to the algebra of coordinates in the lowest Landau level problem. Connections of this charge algebra to noncommutative fluid dynamics and magnetohydrodynamics are shown.

Cross Entropy Covariance Matrix Adaptation Evolution Strategy Solving the Bi-Level Bidding Optimization Problem in Local Energy Markets with Renewables

The increased penetration of renewables in distribution power systems has motivated researchers to take significant interest in local energy transactions. The major goal of Local Energy Markets (LEM) is to promote the participation of small consumers in energy transactions and providing an opportunity for transactive energy systems. Such energy transactions in LEM are considered as a bi-level optimization problem in which all agents at upper and lower levels try to maximize their profits. But typical bi-level problem is very complex as it is inherently nonlinear, discontinued and strongly NP-hard. So, this article proposes the application of hybridized Cross Entropy Covariance Matrix Adaptation Evolution Strategy (CE-CMAES) to tackle such a complex bi-level problem of LEM. The proposed CE-CMAES secured the 1st rank in Testbed-2 entitled, “Bi-level optimization of end-users’ bidding strategies in local energy markets (LM)” at international competitions on Smart Grid Problems, held at GECCO 2020 and WCCI 2020. CE method is used for global exploration of search space and CMAES is used for local exploitation as its adaptive step-size mechanism prevents its premature convergence. A practical distribution system with renewable energy penetration is considered for simulation. The comparative analysis shows that the overall cost, mean fitness and Ranking Index (R.I) obtained from CE-CMAES are superior to those obtained from the state-of-the-art participated algorithms. Wilcoxon Signed Rank Statistical test also proves that CE-CMAES is statistically different from the tested algorithms.

Modeling interaction between distribution company and networked microgrids in optimal operation of active distribution network

In this paper, the interaction between energy sellers and buyers in utilizing active distribution networks is modeled with considering two networked and non-networked modes of microgrids (MGs). A retail electricity market is modeled as a bi-level problem. Accordingly, the Distribution Company (DISCO) in the upper level in order to maximize the profit offers an optimal price to MGs. While in the lower level, the MGs to compare the offered prices by DISCO with the prices of MGs generation sources for minimizing the total costs decided to whether to buy from the DISCO or not. As the first contribution of the paper is to consider the networked operation of the MGs under a unique beneficiary of MGs (BMG). As the second contribution, two very important indices reserve and self-adequacy are considered, which are necessary in the problems related to MGs. In this paper, the impact of considering and disregarding two important reserve and self-adequacy indices of MGs on the profit of the DISCO in two different scenarios is investigated. In each scenario, the impact of considering two modes networked and non-networked of MGs on the profit of DISCO is investigated. Simulation results show the efficiency the presented model.

Social-Ecological Barriers to Student-parents’ Academic Success: A Systematic Review

Students who are parents in higher education (HE) in the United States encounter competing demands and challenges while navigating multiple roles as parents, students, and employees. These challenges are multifaceted and can hinder their degree attainment. Using the socio-ecological model, we systematically summarized existing literature published between 2009 - 2020 to understand the experiences and predictors of student-parents academic outcomes in HE. The reviewed articles included students from two-year and four-year institutions (community college, undergraduates, and graduate students). The analysis revealed that the constraints to student-parents academic success are a system-level problem. Most of the barriers and facilitators identified were related to structural policies adopted by HE. This study concludes with recommendations for future research, policymakers, and the school ecosystem.

DESIGNING THE DESIGN PROCESS FOR EARLY PROBLEM DISCOVERY FOR A COMPLEX AERONAUTICS SYSTEMS CHALLENGE

The earliest stage in the innovation lifecycle, problem formulation, is crucial for setting direction in an innovation effort. When faced with an interesting problem, engineers commonly assume the approximate solution area and focus on ideating innovative solutions. However, in this project, NASA and their contracted partner, Accenture, collaboratively conducted problem discovery to ensure that solutioning efforts were focused on the right problems, for the right users, and addressing the most critical needs—in this case, exploring weather tolerant operations (WTO) to further urban air mobility (UAM) – known as UAM WTO. The project team leveraged generative, qualitative methods to understand the ecosystem, players, and where challenges in the industry are inhibiting development. The complexity of the problem area required that the team constantly observe and iterate on problem discovery, effectively “designing the design process.” This paper discusses the approach, methodologies, and selected results, including significant insights on the application of early-stage design methodologies to a complex, system-level problem.

Optimizing udder health in dairy cattle

In this chapter several aspects of udder health are discussed. Mastitis, inflammation of the mammary gland, which is generally caused by bacterial infections, is one of the most important and most studied diseases in dairy cattle. Diagnostic approaches are discussed with specific attention for the bacteriological causes of the disease. Subsequently immunological aspects of intramammary infections will be reviewed. Because treatment of mastitis in unavoidable at some point in time in most dairy herds, attention is given to treatment of mastitis with an emphasis on different types of antibiotics and antibiotic resistance. The most important part of udder health management, however, is the preventive management. From that perspective, breeding, housing and nutrition are shortly discussed, as are the milking machine and milking procedures. Finally attention is given to problem solving once mastitis has led to a herd level problem and some future trends are discussed.