Accelerating Energy-Economic Simulation Models via Machine Learning-Based Emulation and Time Series Aggregation

Energy-economic simulation models with high levels of detail, high time resolutions, or large populations (e.g., distribution networks, households, electric vehicles, energy communities) are often limited due to their computational complexity. This paper introduces a novel methodology, combining cluster-based time series aggregation and sampling methods, to efficiently emulate simulation models using machine learning and significantly reduce both simulation and training time. Machine learning-based emulation models require sufficient and high-quality data to generalize the dataset. Since simulations are computationally complex, their maximum number is limited. Sampling methods come into play when selecting the best parameters for a limited number of simulations ex ante. This paper introduces and compares multiple sampling methods on three energy-economic datasets and shows their advantage over a simple random sampling for small sample-sizes. The results show that a k-means cluster sampling approach (based on unsupervised learning) and adaptive sampling (based on supervised learning) achieve the best results especially for small sample sizes. While a k-means cluster sampling is simple to implement, it is challenging to increase the sample sizes if the emulation model does not achieve sufficient accuracy. The iterative adaptive sampling is more complex during implementation, but can be re-applied until a certain accuracy threshold is met. Emulation is then applied on a case study, emulating an energy-economic simulation framework for peer-to-peer pricing models in Germany. The evaluated pricing models are the “supply and demand ratio” (SDR) and “mid-market rate pricing” (MMR). A time series aggregation can reduce time series data of municipalities by 99.4% with less than 5% error for 98.2% (load) and 95.5% (generation) of all municipalities and hence decrease the simulation time needed to create sufficient training data. This paper combines time series aggregation and emulation in a novel approach and shows significant acceleration by up to 88.9% of the model’s initial runtime for the simulation of the entire population of around 12,000 municipalities. The time for re-calculating the population (e.g., for different scenarios or sensitivity analysis) can be increased by a factor of 1100 while still retaining high accuracy. The analysis of the simulation time shows that time series aggregation and emulation, considered individually, only bring minor improvements in the runtime but can, however, be combined effectively. This can significantly speed up both the simulation itself and the training of the emulation model and allows for flexible use, depending on the capabilities of the models and the practitioners. The results of the peer-to-peer pricing for approximately 12,000 German municipalities show great potential for energy communities. The mechanisms offer good incentives for the addition of necessary flexibility

Development of high-performance strand boards: engineering design and experimental investigations

Strand-based engineered wood products such as oriented strand boards enjoy great popularity in structural engineering and are widely used for a variety of applications. To strengthen their competitiveness and to enlarge their range of utilization particularly in the load-bearing sector, the mechanical properties of these products need to be improved. This motivated the research efforts to use large-area, slender veneer strands for the production of strand boards with increased stiffness and strength. Target-oriented development of these products requires comprehending the effects of the relevant (micro-)characteristics, such as wood quality, strand geometry, and strand orientation and compaction during the production process, as well as layer assembly and density profile, on the mechanical properties of the finished strand boards. Comprehensive test series, in which these effects on tension, bending and shear properties of the boards have been studied individually, are presented in this paper. The obtained results provided insight into the microstructural load-carrying mechanisms and, thus, yielded valuable knowledge for product optimization and further improvement of custom-designed strand-based engineered wood products

Normothermic machine perfusion of kidneys: current strategies and future perspectives

PURPOSE OF REVIEW: This review aims to summarize the latest original preclinical and clinical articles in the setting of normothermic machine perfusion (NMP) of kidney grafts. RECENT FINDINGS: Kidney NMP can be safely translated into the clinical routine and there is increasing evidence that NMP may be beneficial in graft preservation especially in marginal kidney grafts. Due to the near-physiological state during NMP, this technology may be used as an ex-vivo organ assessment and treatment platform. There are reports on the application of mesenchymal stromal/stem cells, multipotent adult progenitor cells and microRNA during kidney NMP, with first data indicating that these therapies indeed lead to a decrease in inflammatory response and kidney injury. Together with the demonstrated possibility of prolonged ex-vivo perfusion without significant graft damage, NMP could not only be used as a tool to perform preimplant graft assessment. Some evidence exists that it truly has the potential to be a platform to treat and repair injured kidney grafts, thereby significantly reducing the number of declined organs. SUMMARY: Kidney NMP is feasible and can potentially increase the donor pool not only by preimplant graft assessment, but also by ex-vivo graft treatment

Normothermic machine perfusion of kidneys:current strategies and future perspectives

PURPOSE OF REVIEW: This review aims to summarize the latest original preclinical and clinical articles in the setting of normothermic machine perfusion (NMP) of kidney grafts. RECENT FINDINGS: Kidney NMP can be safely translated into the clinical routine and there is increasing evidence that NMP may be beneficial in graft preservation especially in marginal kidney grafts. Due to the near-physiological state during NMP, this technology may be used as an ex-vivo organ assessment and treatment platform. There are reports on the application of mesenchymal stromal/stem cells, multipotent adult progenitor cells and microRNA during kidney NMP, with first data indicating that these therapies indeed lead to a decrease in inflammatory response and kidney injury. Together with the demonstrated possibility of prolonged ex-vivo perfusion without significant graft damage, NMP could not only be used as a tool to perform preimplant graft assessment. Some evidence exists that it truly has the potential to be a platform to treat and repair injured kidney grafts, thereby significantly reducing the number of declined organs. SUMMARY: Kidney NMP is feasible and can potentially increase the donor pool not only by preimplant graft assessment, but also by ex-vivo graft treatment

Understanding mothers' experiences of positive changes after neonatal death

Background: The death of a neonatal baby has the potential for parents to experience many negative outcomes. Post traumatic growth describes positive personal change from the struggle with a traumatic event. This has not been explored in this context. Objective: This study sought to understand the experiences of mothers whose neonatal baby had died; in particular, whether mothers were able to experience any positive changes in their lives since the death of their baby. The study also sought to explore what factors may have facilitated or prevented these changes. Method: Ten mothers were recruited, whose baby had died in the neonatal period between two and 10 years previously. Mothers completed semi-structured, one-to-one interviews. Interview transcripts were analysed using Template Analysis. Results: Despite ongoing sadness, mothers recognized positive personal changes in their self-perception, relationships and life philosophy which were consistent with the post-traumatic growth model. Mothers also identified facilitators and barriers to these changes which were categorized into five themes: ‘Person-centred care’, ‘making sense’, ‘personal coping strategies’, ‘learning to live with it’ and ‘identity’. Conclusions: This study identified that the mothers made a conscious personal decision to cope with their experience. This is a unique finding which requires further exploration. Facilitators and barriers of growth both occurred as elements within the same five themes, indicating that all identified domains before and after the death have the potential to facilitate or to prevent personal growth. Importantly, these findings indicate that person-centred services, which are responsive to individual needs at all stages, are vital when providing maternity care in the context of loss

What aspects of post-traumatic growth are experienced by bereaved parents? A systematic review

Background: The death of a child of any age can be traumatic and can leave bereaved parents experiencing negative psychological outcomes. Recent research has shown the potential utility for understanding more about the development of post-traumatic growth following bereavement. Objective: This paper sought to identify the aspects of post-traumatic growth experienced by bereaved parents and the factors that may be involved in facilitating or preventing post-traumatic growth. Methods: A systematic search of peer-reviewed articles with a primary focus on positive personal growth in bereaved parents was conducted. Thirteen articles met the inclusion criteria, and were analysed and synthesized according to common and divergent themes. Results: Bereaved parents were able to experience elements of growth proposed by the post-traumatic growth model (changes in self-perception, relationships, new possibilities, appreciation of life and existential views). The papers also indicated that (1) mothers appeared to experience more growth than fathers, (2) cultural variation may impact on some participants’ experience of growth, and (3) participants were able to identify growth only once some time had passed. Potential facilitators of post-traumatic growth involved making meaning, keeping ongoing bonds with the child, being with bereaved families, and family and personal characteristics. Social networks were identified as having the potential to be either a facilitator or a barrier to growth. Conclusions: In addition to experiencing grief, bereaved parents may experience aspects of post-traumatic growth, and a variety of factors have been identified as potential facilitators and barriers of these changes. The findings may have implications for support services (e.g. expert-by-experience services)

Potential use of ayahuasca in grief therapy

The death of a loved one is ultimately a universal experience. However, conventional interventions employed for people suffering with uncomplicated grief have gathered little empirical support. The present study aimed to explore the potential effects of ayahuasca on grief. We compared 30 people who had taken ayahuasca with 30 people who had attended peer-support groups, measuring level of grief and experiential avoidance. We also examined themes in participant responses to an open-ended question regarding their experiences with ayahuasca. The ayahuasca group presented a lower level of grief in the Present Feelings Scale of Texas Revised Inventory of Grief, showing benefits in some psychological and interpersonal dimensions. Qualitative responses described experiences of emotional release, biographical memories, and experiences of contact with the deceased. Additionally, some benefits were identified regarding the ayahuasca experiences. These results provide preliminary data about the potential of ayahuasca as a therapeutic tool in treatments for grief.info:eu-repo/semantics/publishedVersio