Energy Flow Research Articles

Quantifying the Effects of Solar Wind Fluctuations on the Solar Wind‐Magnetosphere Interaction

AbstractAla‐Lahti et al. (2024, https://doi.org/10.1029/2024GL112922) present results from a global magnetohydrodynamic simulation of a single geomagnetic substorm for four scenarios: the original solar wind conditions, smoothed low‐frequency solar wind conditions, constant solar wind conditions with a boxcar averaged north/south component of the interplanetary magnetic field (IMF), and the boxcar‐averaged scenario with ultra‐low‐frequency (ULF) fluctuations. Smoothed (<1 mHz) solar wind parameters capture the bulk of the interaction, boxcar averaging reduces the energy flow through the system by 15%–40%, and ULF fluctuations (2–8 mHz) only enhance interactions by 5%–15%. From this, we conclude that low‐frequency plasma and magnetic field variations dominate the interaction. Further global simulations and observational studies of different events will be needed to determine the significance of intrinsic magnetopause and magnetotail instabilities (rather than directly driven interplanetary magnetic field fluctuations). They will also be needed to generalize these results for the full range of solar wind and geomagnetic conditions.

Dynamics of elastic wires: preserving area without nonlocality

We derive an H-1-gradient flow of the elastic energy which preserves the enclosed area of evolving planar curves. For this new sixth-order evolution equation, we prove a global existence result. Additionally, by penalizing the length, we show convergence to an area constrained critical point of the elastic energy.

Assessing temporal shifts in trophic diversity in fish assemblages after the Fundão dam collapse.

The rupture of the Fundão dam stands as one of the most significant environmental disasters of its kind on a global scale, profoundly affecting the aquatic ecosystem of Doce River Basin. By employing stable isotopes of carbon and nitrogen, we were able to trace matter and energy flow within ecosystems. In this study, we assessed the spatial and temporal variation, between 2020 and 2022, in species richness and trophic diversity in areas exposed (along a gradient in the main channel of the river) or unexposed (control sites in tributaries systems) to the mine ore tailings in the Doce River Basin. We tested the hypothesis that tailings reduce species richness, and that trophic stability is negatively affected by mining tailings. To estimate trophic stability for each sampling site, we calculated the standard ellipse area (SEA) and six community-wide metrics based on stable isotopes. The three regions studied presented distinct patterns on trophic diversity. Control sites exhibited stability in trophic metrics over time. Affected regions close to the rupture of the dam exhibited significant fluctuations on all six community-wide metrics analyzed than the affected regions farther from the rupture. Sites close to the rupture exhibited lower species richness, affecting mainly herbivores and piscivores. Our findings show the potential of using the isotopic approach in monitoring the ecological recovery of impacted ecosystems.

Harnessing Machine Learning to Analyze Energy Generation and Capacity Trends in the USA: A Comprehensive Study

The constraints in conventional energy forecasting models in the USA are increasingly being appreciated as the energy landscape evolves. Such models are generally constructed on linear assumptions that do not capture energy generation and consumption patterns as dynamic and multi-dimensional. This research project aimed to develop effective machine-learning models to interpret historical trends in energy generation and capacity in the United States. With access to massive datasets for various energy sources—fuel-based to renewable and nuclear energy—this research endeavors to discover actionable information that can optimize energy output and improve grid stability. The dataset used is a comprehensive overview of energy production in America, integrating information from a variety of sources, ranging from fossil fuels to renewables and nuclear energy. This extensive dataset is sourced from reliable sources such as the U.S. Energy Information Administration (EIA) which supplies vast historical and current data on energy consumption and production patterns; the Federal Energy Regulatory Commission (FERC) which supplies information on regulatory frameworks and market forces that affect energy production; and smart grid management systems that deliver real-time data on energy flows and grid performance. Selecting appropriate machine learning models is crucial to process engineered features and derive actionable insights effectively. For this purpose, we use Logistic Regression, Random Forest Classifier, and the Support Vector Machines. The model performance table indicates how well three machine learning algorithms—Logistic Regression, Random Forest, and SVM—classify between renewable and non-renewable energy sources. All three models are highly accurate, with SVM having a slight edge, followed by Random Forest and lastly Logistic Regression. AI-powered energy forecasting is revolutionizing energy infrastructure planning in America through the provision of sophisticated information to guide investment in grid upgrades and expansion. As America transitions to dependence on renewable energy, AI-based forecasting is essential to optimize the integration of solar and wind energy production onto the grid. The variability of these renewable resources poses special challenges for grid managers, who need to balance demand and supply in real time. Moreover, AI can be used to identify gaps in renewable energy capacity and storage. The infusion of AI-based insights into the energy sector has far-reaching implications for U.S. policymakers, equipping them with fact-based tools to efficiently apply energy reforms. With evolving energy patterns, legislators need to adjust regulations to facilitate a seamless transition to a more sustainable energy system.

Seismic Hazard Evaluation and Strain Dynamics in the Simav Fault Zone: A Comprehensive Analysis of Earthquake Recurrence and Energy Release Patterns

This study aims to determine the earthquake hazard of the Simav Fault Zone (SFZ), one of the key tectonic features of Western Anatolia—a region that serves as a natural laboratory for geoscientists due to its complex tectonic structure and swarm-type seismic activity generated by multiple active graben systems. For this purpose, the a (6.33) and b (0.92) seismic parameters based on the Gutenberg–Richter magnitude–frequency relationship were first calculated using M ≥ 3 earthquakes that occurred between 1900 and 2024 along the SFZ. Moreover, the recurrence periods of events with magnitudes between M = 5 and M = 7.1 were determined (ranging 32 and 982 years), and the seismic hazard levels in the region were identified. The spatial density of the earthquakes and the regional distribution of the energy they released were analyzed, and the variations in seismic activity along the fault and energy flow in the region were investigated. For the evaluation of past earthquakes with the current strain field of the region, using geodetic velocity data, the strain rates of each segment of SFZ were calculated (reaching 90 ns/year) and findings related to stress accumulation processes were obtained. The findings, along with previous events, indicate that the region is susceptible to seismic hazards and that even moderate earthquakes pose a significant threat to both infrastructure and the population. This study, which seeks to enhance the understanding of seismic hazards and regional strain accumulation in the SFZ, is expected to serve as a valuable tool in seismic hazard assessments and local disaster management strategies, and to provide a critical reference for decision-makers in effective earthquake risk management.

Sustainability building materials and circularity score of residential buildings

Building materials used, approaches and technologies related to the operation of residential buildings influence the environment and climate change. For this purpose, an assessment of environmental impacts and circularity of 11 residential buildings (marked as A) was carried out using the life cycle assessment (LCA) methodology. LCA analysis consisted of four parts. First, the goal and scope were defined. Then, inventory analysis (LCI) entered the assessment using input data. They were needed to quantify inputs and outputs, resource and energy flows, emissions, and other leakages. Life cycle impact assessment (LCIA) quantified the pollutants into impact categories. The last part was the interpretation of the results. Investigated buildings were assessed within a moderate climate zone and "Cradle to Cradle" system boundaries over a lifetime of 60 years. The product and energy consumption phases generally contributed to the highest GHG emissions. In terms of materials, aerated concrete (up to 89.4%), concrete (20-51%) and clay brick (38-47%) caused the highest values for the GWP indicator. The end-of-life phase, including incineration, landfilling and reuse of materials, was quantified in the 0.1-74% range. Quantified global indicators are Global warming potential (GWP), Depletion potential of the stratospheric ozone layer (ODP), and Abiotic depletion potential for non-fossil resources (ADP-E). In this study, regional indicators are Acidification potential (AP), Eutrophication potential (EP) and Formation potential of tropospheric ozone (POCP). A building that achieves higher circularity is the building that makes the most use of renewable or reused resources, so it uses less raw materials. The circularity score representing materials recovery was 23% to 48%. The best circularity score of building E (48%) was due to downcycling (45.8%) and use as energy (32.1%) of applied materials. The lowest circularity score was found for building I, with a value of 23%. The most suitable building in terms of environmental impact and circularity was identified using multicriteria analysis.

The feeding mode effect: influence on particle ingestion by four invertebrates from Sub-Antarctic and Antarctic waters.

Microplastic (MP) pollution is a significant threat to marine environments not only due to its widespread presence but also because of the alarming emergence of ingestion records among benthic organisms. In this study, MP prevalence was assessed in the stomach of the crustaceans Lithodes santolla and Grimothea gregaria and the gastropods Nacella deaurata and N. concinna. Particles were analyzed with Fourier-transform infrared (FTIR) spectroscopy. Overall, the analysis revealed that the particles were mainly microfibers composed of cellulose/rayon (60%), followed by MPs (30%), and undetermined not registered in the library (10%). Higher prevalence was found in marine benthic grazers compared to scavengers, with the latter showing low particle prevalence in their stomach contents. Grazers presented a significantly higher abundance per individual but a lower size of ingested particles compared to scavengers. When grouped by trophic levels, tertiary consumers presented significantly lower abundances per individual but larger sizes of the ingested particles. Pearson's correlations showed no significant associations between particle abundance/size and species body size. The results of this study may suggest that continued MP pollution in marine environments and the associated accidental ingestion by marine organisms will alter the energy flow and organic matter availability in benthic food webs, with species that perform certain functional traits more susceptible to being affected.

A general spectral collocation method for computing the dispersion relations of guided acoustic waves in multilayer dissipative structures

A spectral collocation method is proposed to compute the complex wavenumber–real frequency dispersion relations of guided acoustic waves in multilayer structures involving dissipative materials. The nature of these dissipative materials is initially considered to be arbitrary, i.e., poroelastic, viscoelastic, or viscoacoustic. For a given frequency, the complex wavenumbers as well as the physical fields, which are further used to evaluate the Poynting vectors and analyze the energy flux, are obtained by solving a generalized eigenvalue problem. The latter arises from a set of discretized equations of motion and appropriate boundary (coupling) conditions. These equations of motion and boundary (coupling) conditions are imposed by the nature of the material composing each layer of the structure. A focus is made on poroelastic layers. The dispersion relation of a two-layer elastic–poroelastic structure is analyzed, as well as the energy flows in the structure. The results as calculated with the present spectral collocation method are validated against those obtained with a classical complex root-finding (Müller) method and experiments.

MASS-ENERGY MODELS OF THE ECONOMY – CONCEPTS AND REALITIES I. MATERIAL FLOW ANALYSIS

basis (production and trade) and of the ecosphere (from soil and subsoil, biosphere and atmosphere) are presented. Therefore, mass-energy models allow a unified treatment of the “social metabolism” and of its interaction with the environment. We present the most important models, both those that study separately material or energy flows, as well as the synthetic ones, more complex, but more realistic. We deal with both descriptive and prescriptive models, which serve to develop analyses and policies at various levels: enterprise, branch, country, region, or global ensemble. In addition, we analyze the main assumptions and methods of these models, together with the goals and the feasibility of policies built-up on their basis. In this first part, we describe the factual situation of materials and energies in the world economy for the last twenty years and the Material Flow Analysis (MFA) method, while in the second part – the methods of Energy Flow Analysis (EFA) and Life Cycle Assessment (LCA) of products, with the interaction between economy, nature, and society.

Changes in the soil detrital food chain associated with Gunnera tinctoria plant invasions

Abstract Whilst invasive plants can modify community and ecosystem attributes, there is little information on their impact across different trophic levels. Here, we examined the effects of Gunnera tinctoria Molina (Mirb.; Gunneraceae; “Chilean-rhubarb”) on the soil detrital food chain, the major pathway for energy flow in terrestrial ecosystems and the recycling of nutrients. Measurements of soil physio-chemistry properties and the natural abundances of C and N isotopes, along with assessments of microbial and earthworm populations were used to verify if G. tinctoria drives the soil food web and how C is transferred from decomposing litter to worm populations. Based on the C isotope compositions of plant material and detritivorous worms (i.e., earthworms and enchytraeid worms), all worms contribute to G. tinctoria litter decomposition, irrespective of their feeding preference. The increased role of larger earthworm populations in litter decomposition was also associated with changes in the soil microbial community, with some bacterial genera being absent from invaded areas. Of particular interest was a three-fold increase in Nitrospira spp. in invaded areas, likely due to an increase in earthworm-related ammonia production, with this being rapidly converted to nitrate. Given the poor representation of other ammonia and nitrite oxidizing soil bacteria, many of the Nitrospira spp. present in invaded soils may perform complete ammonia oxidation (i.e., COMAMMOX). Our results indicate a greater role for native earthworms in decomposition processes in areas invaded by G. tinctoria, resulting in modifications in the other soil biota and an increase in soil nitrate.

Sustainable Energy Management: Energy Flow and Economic Analysis of Grape Production

The efficiency of energy flow and the economic viability of agricultural systems are foundational pillars of sustainable energy management and development. This study applies the energy pyramid framework to evaluate energy flow efficiency and conduct an economic analysis to explore the viability of grape production systems in Takestan County, Qazvin, Iran. Data were collected from 220 grape-growers during the 2020–2021 period. Results indicated that fertilizers and electricity were the major energy inputs, comprising 36.51% and 20.12% of total energy use, respectively. The energy ratio and energy productivity were estimated at 5.81 and 0.49 kg MJ−1. Non-renewable and indirect energy sources constituted 58.16% and 63.29% of the total energy, respectively. Sensitivity analysis revealed that human labor had the highest marginal physical productivity due to the labor-intensive practices of grape production systems. To enhance economic viability, it is recommended to match energy usage to specific operational requirements and maximize system efficiency. These strategies increase labor productivity by streamlining processes and reducing inefficiencies, while optimizing energy inputs to ensure their effective utilization in production activities.

Do functional feeding groups exhibit significant differences in the movement patterns of Mediterranean lotic insects under induced thermal stress?

ABSTRACT Global warming disrupts freshwater ecosystems, affecting the movement of vagile aquatic insects and their Functional Feeding Groups (FFGs), key to nutrient cycling and energy flow. This study hypothesized that predators would be less sensitive to thermal stress than collectors, scrapers, and shredders, leading to minimal movement changes. Using a cost-effective video-tracking system, we analyzed four movement variables under three levels of thermal stress. Results showed varied FFG responses, particularly under transitional heated-water conditions. Collector-filterers and shredders exhibited significant changes in total path length and movement tortuosity, while speed-related variables remained largely unaffected. Strong correlations were observed, except among gatherers under the highest temperature. The experiment suggests that warming may constrain point-to-point movement, with distance-related variables proving the most reliable indicators of sensitivity. Collectors, scrapers, and shredders showed greater distance reductions than speed changes, highlighting critical functional and trophic shifts in microhabitat dynamics under global warming.

Diversity, phylogeny and distribution of the subtribe Cristariina (Bivalvia: Unionidae: Unioninae) from China, with description of a new genus and species.

The family Unionidae is a diverse and ecologically significant group of freshwater invertebrates, playing a keystone role in the energy flow and nutrient cycling in aquatic ecosystems. A recent taxonomic revision of the East Asian endemic subtribe Cristariina within Unionidae has revealed its division into seven genera. As an important part of East Asia, China harbours an exceptionally diverse and highly unique fauna of freshwater mussels. However, a comprehensive understanding of species diversity and phylogenetic relationships of Cristariina remains elusive due to inadequate sampling in previous studies, particularly in China. Here, we conducted comprehensive taxonomic and mitogenomic phylogenetic analyses of Cristariina based on extensive sampling across 17 provinces in China. The COI sequences of Cristariina in GenBank were thoroughly examined, and combined with the sequences obtained from this study, a total of 33 monophyletic groups were identified. By integrating molecular data and morphological characteristics, we describe a new genus and species: Acudonta baitiaoensis gen. nov., sp. nov. , as well as a newly recorded species for China (Cristaria truncata ). Additionally, we confirm that the nominal species Anemina euscaphys syn. nov. , Anemina fluminea syn. nov. and Anemina globosula syn. nov. are junior synonyms of Anemina arcaeformis through integrative taxonomy. Mitogenomic phylogeny establishes the following robust phylogenetic framework at the generic level within Cristariina: ((((Sinanodonta + Acudonta gen. nov. ) + (Beringiana + Pletholophus )) + ((Anemina + Buldowskia ) + Amuranodonta )) + Cristaria ). Besides Sinanodonta and Cristaria , the distribution of other genera of Cristariina in China exhibits distinct faunal regions of endemism. ZooBank: urn:lsid:zoobank.org:pub:30E44DEB-3CCD-47F7-A2B2-3FA851BE434E.

A hunting ground for predatory bacteria at the Zhenbei seamount in the South China Sea

Abstract Seamounts are critical marine biodiversity hot spots, while the metabolic activity of their microbial community remains largely unknown. In this study, we investigated the diversity and activity of free-living and particle-attached microorganisms in the surface, middle, and bottom layers of seawater at the Zhenbei seamount in the South China Sea using omics approaches including 16S rRNA/16S rDNA ratio analysis. Over 20 phyla were detected with Proteobacteria, Actinobacteriota, Cyanobacteria, Bacteroidota, Thaumarchaeota, and Planctomycetota being predominant. Surprisingly, Bdellovibrionota and Myxococcota, the two well-known predatory bacteria, exhibited exceptionally higher rRNA/rDNA ratios than the other phyla, with rRNA abundances being 10- or even 200-fold higher than their rDNA abundances. These metabolically active predatory bacteria are mainly uncultured species. A total of 23 Myxococcota MAGs and 12 Bdellovibrionota MAGs were assembled. The most highly overexpressed genes frequently detected in these MAGs were those that encode flagellum and pilus proteins as well as T4-like virus tail tube protein, indicating that these predator bacteria were likely active in hunting. Our results suggest that seamounts may serve as hunting grounds for predatory bacteria, which may be involved in controlling the flows of elements and energy in the seamount microbial communities and thus in shaping the seamount ecosystems.

Hybrid method for energy flow in mid-high frequency acoustics: Applications in robust shape optimization for complex cavities

We present an efficient method for computing acoustic energy within complex-shaped geometries and cavities with obstacles in the mid-high frequency range. This method is based on the Simplified Energy Method (MES), known for its accuracy in such frequency ranges but traditionally limited to simple cavity shapes. The proposed hybrid method integrates the techniques of ray and triangle intersection with the MES formulation to address these limitations. By calculating the intersection points of the rays, we identify the obstructing elements before computing the energy transfer between the boundary elements. A primary intersection state matrix, containing direct view information between elements, is integrated into a modified MES equation to eliminate unnecessary computations and ensure precise calculations of energy transfer for obstructed elements. This hybrid approach is applied to both direct and reverberant fields to determine the total energy density. Numerical simulations conducted within a complex domain enclosure demonstrate the precision of the proposed algorithms when compared to traditional MES calculations. In addition, we propose applying this method to robust shape optimization, effectively balancing competing criteria to achieve optimized acoustic performance. This refined and computationally feasible tool significantly advances computational acoustics, providing accurate and efficient design solutions for complex environments.

Mixed-layer lipidomes suggest offshore transport of energy-rich and essential lipids by cyclonic eddies

Mixed-layer lipidomes suggest offshore transport of energy-rich and essential lipids by cyclonic eddies

Sustainable supply chain in green hydrogen industry in India using SAP-LAP and paradox framework

Purpose This study aims to delve into how predictive maintenance (PM) strategies and supply chain optimization (SCO) can effectively integrate within the green hydrogen sector, enhancing operational efficiency and sustainability. Design/methodology/approach This study uses the situation, actor, process-learning, action, performance model of inquiry, enriched by insights from the paradox framework using expert opinions. The study is grounded in an empirical methodology, using in-depth interviews and discussions with industry experts to elucidate the complex dynamics. Findings Key findings from the expert interviews reveal a rich tapestry of challenges and opportunities. This study emphasizes the criticality of PM in reducing downtime and increasing the lifespan of key equipment in hydrogen production. Simultaneously, it underscores the pivotal role of SCO in ensuring the seamless flow of materials and energy, which is vital for the industry’s scalability and economic viability. Originality/value It is noted that this study contributes a detailed perspective to the existing body of literature, particularly focusing on the nuanced roles of PM and SCO in the green hydrogen value chain. This approach is distinct from prior studies that primarily concentrated on the hydrogen value chain, which have traditionally delved into the drivers, challenges and enablers of these areas.

From the right to the city to the right to the village? French perspectives on the urban-rural divide

Within urban studies, the planetary extent of energy and material flows is increasingly questioned as a major cause of current ecological crises. Within degrowth movements and thinking, pleas for the relocalisation of humanity’s attachments are becoming common and, in France at least, they are often associated with anti-urban stances and calls to leave big cities and metropolises, considered to be the epicentres of planetary urbanisation and globalisation. This review essay presents this ecological critique that developed in France over the past decade. It starts with a fresh look at the right to the city. To what extent can big cities still embody an ideal at odds with urbanisation, as Henri Lefebvre posited? Does radicalism not lie more in the back-to-the-land calls that are re-flourishing? The essay then discusses the opposition between planetary urbanisation and relocalisation, and explores the recent French conversation on the ‘right to the village’. Beyond such a right, a crucial issue for degrowth, however radical its vision, is to ruralise the urban, particularly in large metropolitan regions.

Characterization of the autumn microphytobenthos and phytoepiphyton of the littoral of Lake Verbne (Kyiv, Ukraine)

For the first time, the taxonomic diversity, quantitative development, structural organization, dominant complexes, trophic status of microphytobenthos and phytoepiphytos were determined for the littoral of the Lake Verbne ecosystem in the autumn period (2023). The taxonomic richness of the microphytobenthos and phytoepiphyton was formed by 117 species (135 intraspecific taxa, ist) from 7 divisions, and 79 species (87 ist) from 6 divisions. Among the divisions, the leading role in the floristic spectrum belonged to Bacillariophyta (52; 64%), followed by Chlorophyta (27; 20%) and Cyanobacteria (6; 8%), respectively. The Sørensen coefficient between microphytobenthos and phytoepiphyton was 0.48, at the level of divisions: Bacillariophyta > 0.57 > Cyanobacteria > 0.53 > Chlorophyta > 0.42, which confirms a certain specificity of the taxonomic composition of the components of the studied contour communities. The quantitative diversity of these algal communities was formed by the oligodominant complexes Cyanobacteria—Bacillariophyta (by number) and Bacillariophyta—Cyanobacteria (by biomass). The trophic status of the lake ecosystem littoral according to microphytobenthos corresponds to the eutrophic type, and according to phytoepiphyton — to the oligotrophic type. Shannon's indices of information diversity, calculated taking into account the biomass (the energy basis of primary energy flows), were higher for microphytobenthos than for phytoepiphyton. The dominant complex of contour algal communities was oligo- or polydominant: Cyanobacteria—Bacillariophyta (by number) and BacillariophytaCyanobacteria (by biomass), represented by both small-celled and large-celled forms. The original data on the structural organization of microphytobenthos and phytoepiphyton indicate an important role of contour algal communities in the autumn in the formation of biodiversity in the littoral of Lake Verbne, which is a hydroecosystem of the metropolis and belongs to the nature reserve fund of Ukraine.

Uncovering the Role of Direct Electron Transfer in Plasmon-Mediated Electrochemical Reactions.

The mechanism of the charge and energy flow at the metal-molecule interface has attracted much attention, especially with the recent rise of plasmonic nanomaterials for light-to-chemical conversion. Although numerous studies have demonstrated the irreplaceable effects of energetic electrons on accelerating chemical reactions, detangling the direct electron transfer (DET) from indirect electron transfer (IET) and understanding their roles are still challenging. Here, by combining electrochemical dark field scattering spectroscopy, the photoelectrochemical method, and density functional theory calculation, we provided the evidence of DET during chemical reactions, alongside decoupling the contributions of DET and IET, and then established the relationship between chemical reactivity and DET efficiency. Moreover, we discovered that DET is selective for different reactions, e.g., enhancing the oxygen reduction reaction much more than the hydrogen evolution reaction. This work offers the possibility to optimize reaction selectivity via DET and advances mechanistic insights into plasmonic charge transfer.