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New Analytical Model for Forecasting Turbidity Current Run‐Up Heights: Implications for Risk Assessment of Seafloor Infrastructure on Submarine Slopes
Get PDFTurbidity currents are destructive flows that are hazardous to critical seafloor infrastructure on submarine slopes because run-up heights can be 10–100s of meters, as their relative density is 2–3 orders of magnitude lower than terrestrial flows. Currently, risk analysis is hindered by poor prediction of run-up heights that are mainly derived from confined 2D experiments, and/or numerical models, and are restricted to a specific configuration whereby the flow strikes topographic barriers orthogonally. Here, a new analytical model is presented, informed by and validated against physical experiments, which predicts run-up heights for flows encountering three-dimensional slopes as a function of any slope angle, and incidence angle, of the impinging turbidity current. This has important implications for reducing geohazards by informing routing and positioning of seafloor infrastructure, and for more accurately interpreting submarine landscapes and their deposits
SMEs and flood insurance: Assessing the effective resilience using contextualised evidence
Get PDFFlooding is one of the biggest challenges reported by small to medium-sized businesses (SMEs) in the UK, and flood insurance is an important tool for reducing SMEs’ future flood risks. Flood insurance helps small businesses manage increasing risks and, if priced and designed right, serves as a powerful incentive to better prepare for and reduce the impact of future floods. However, flood insurance uptake by SMEs is low and expensive. Insurance pricing depends on knowing an SME’s risks and level of resilience with confidence. However, SMEs exhibit diverse risk profiles and levels of vulnerability due to their heterogeneous business characteristics. Such complexity makes it difficult for the insurance industry to commodify SMEs’ risk and provide affordable insurance. As flood risk is on the rise, it is paramount to identify which factors influence insurers’ decisions to grant insurance to SMEs or deny it. This study uses a mixed-method approach were through online surveys, semi-structured interviews, focus group discussions, and workshops with lenders, insurers, surveyors, brokers, and SMEs, pursue threefold objectives: 1) identify factors that influence SMEs resilience and insurers decision making; 2) assess SMEs’ losses, flood risk mitigation strategies and insurance needs; and 3) collaborate with the insurance industry and SMEs to design and pilot a tool to unlock affordable insurance coverage. Results show that while critical, professional flood risk assessment and flood depth damages are not sufficient on their own. Well-kept descriptive and photographic evidence, along with the positive attitude associated with SMEs’ behaviour, makes the evidence much more compelling and convincing when they are deciding whether to insure or lend to specific businesses. The tool also encouraged SMEs to initiate or improve resilient behaviour and to facilitate communication and knowledge exchange between SMEs and insurance providers. Overall, this research offers policy and practice recommendations that have the potential to increase mutual understanding and drive a positive behavioural change among SMEs and the insurance industry
Identifying innovative models of urgent care in rural coastal areas in England:the Elevate study - a mixed-methods protocol
Get PDFINTRODUCTION: Urgent and emergency care (UEC) systems in England face unprecedented pressures, with record accident and emergency attendances, persistent breaches of ambulance response targets and poorer outcomes for time-sensitive conditions. National UEC recovery plans have introduced multiple innovations-such as same-day emergency care, virtual wards and specialty hubs-to manage these pressures and improve patient flow. Rural coastal areas are particularly vulnerable to excessive demand due to higher levels of deprivation, older populations with complex health needs, seasonal surges that generate unpredictable demand and challenges in attracting and retaining staff. Following the Chief Medical Officer's 2021 Annual Report, funding research and developing bespoke solutions to manage UEC demand and address geographical disparities has been recognised as a national priority. The Elevate study responds to this priority by identifying and evaluating innovative models of UEC in rural coastal communities in England. METHODS AND ANALYSIS: The Elevate study is a 30-month, mixed-methods evaluation that comprises three interlinked work packages: (1) National service mapping-outlining provision of innovative models of UEC in rural coastal areas of England. This will be developed through document review and interviews with regional and national service leaders. (2) Quantitative analysis-quasiexperimental and longitudinal approaches will use National Health Service (NHS) England's Emergency Care Data Set and linked routine NHS datasets to evaluate the impact of UEC models on health and process outcomes. Standard and bespoke metrics will be developed and used to assess performance. (3) Qualitative case studies-up to 12 case studies of UEC models in rural coastal communities. Interviews with patients and staff and non-participant observation will explore how and why different UEC models influence patient experience, clinical outcomes, resource use and the workforce. Findings will be integrated using the Consolidated Framework for Implementation Research to identify components of UEC models that are effective, scalable and sensitive to local context, ETHICS AND DISSEMINATION: Ethical approval for qualitative components was granted by the North of Scotland Research Ethics Committee (25/NS/0099). Dissemination will include peer-reviewed publications, policy briefs, creative media and community engagement activities to ensure findings are communicated inclusively and effectively to policymakers, health and social care practitioners and the public. TRIAL REGISTRATION NUMBER: Research Registry (researchregistry11126)
Detection of potential structural deficiencies in a global aerosol model using a perturbed parameter ensemble
Get PDFUnderstanding and reducing uncertainty in model-based estimates of aerosol radiative forcing is crucial for improving climate projections. A key challenge is that differences between model output and observations can stem from uncertainties in input parameters (parametric uncertainty) or from deficiencies in model code and configuration (structural uncertainty), and these two causes are difficult to distinguish. Structural deficiencies limit efforts to reduce parametric uncertainty through observational constraint because they prevent models from being simultaneously consistent with multiple observations. However, no framework exists to detect structural deficiencies and assess their impact on parametric uncertainty. We propose a workflow to identify structural inconsistencies between observational constraints and diagnose potential structural deficiencies. Using a perturbed parameter ensemble, we sample uncertainty in aerosols, clouds, and radiation in the UK Earth System Model (UKESM), and evaluate model bias against in-situ observations of sulfate aerosol, sulfur dioxide, aerosol optical depth, and particle number concentration across Europe. Applying observational constraints reveals inconsistencies that no combination of the perturbed parameters can resolve. For example, sulfate concentrations in different regions cannot be matched simultaneously, and enforcing a compromise between regions reduces skill across most variables. Additional examples include an inter-region inconsistency in SO2 and an inter-variable inconsistency between aerosol optical depth and sulfate. By examining the parameter sets retained by constraints, we trace inconsistencies to the parameterisations that may cause them and propose targeted changes to address the underlying deficiency. This approach offers a pathway for evidence-based model development that supports more robust uncertainty reduction and improves climate projection skill
Discontinuous transition to shear flow turbulence
Get PDFDepending on the type of flow, the transition to turbulence can take one of two forms: either turbulence arises from a sequence of instabilities or from the spatial proliferation of transiently chaotic domains, a process analogous to directed percolation. The former scenario is commonly referred to as a supercritical transition and frequently encountered in flows destabilized by body forces, whereas the latter subcritical transition is common in shear flows. Both cases are inherently continuous in a sense that the transformation from ordered laminar to fully turbulent fluid motion is only accomplished gradually with flow speed. Here we show that these established transition types do not account for the more general setting of shear flows subject to body forces. The combination of the two continuous scenarios leads to the attenuation of spatial coupling; with increasing forcing amplitude, the transition becomes increasingly sharp and eventually discontinuous. We argue that the suppression of laminar–turbulent coexistence and the approach towards a discontinuous phase transition potentially apply to a broad range of situations including flows subject to, for example, buoyancy, centrifugal or electromagnetic forces
Impact ionization properties of polypyrrole nanoparticles
Get PDFUpcoming space missions flying dust impact ionization mass spectrometers will detect and analyze dust grains that are partially organic in composition. These organic components are expected to include mixtures of polycyclic aromatic hydrocarbons, heterocyclic compounds (containing oxygen, sulfur, and nitrogen), and additional functionalized condensed species. Dust impact ionization is a strongly velocity-dependent process that produces atomic and molecular ions reflective of the composition of the impacting particle. In this work, we characterize the impact ionization response of the nitrogen-bearing heterocyclic polymer polypyrrole (PPy). Because of its electrical conductivity, PPy is commonly used as a coating material for both mineral and organic dust particles in electrostatic dust accelerator studies. PPy nanoparticles were accelerated to velocities of 2–30 km s–1, and the resulting time-of-flight mass spectra were analyzed as a function of impact velocity with additional care paid to spectral variations with particle mass. The resultant mass spectra produced by impacts under roughly 8 km s–1 are dominated by smaller PPy-derived molecular fragments at masses 27, 28, 56, and 63u, in addition to common contaminants such as Na+ (23u) and K+ (39u). Some of these molecular fragments can be understood as originating from pyrrole, i.e., the species from which PPy is derived, while others appear to be unique to PPy. At higher velocities, the impact ionization of PPy produces two homologous series of fragment ions with the general form C n H m + and C n NH m +, alongside the molecular fragments. This study refines our understanding of impact ionization processes for organic heterocyclic compounds and provides essential reference data for interpreting dust spectra from upcoming interstellar and interplanetary missions
Microbial death in the Andes: necromass declines despite growth and carbon-use-efficiency increases with decadal soil warming
Get PDFThe growth and death of soil microbes are important drivers of soil carbon formation. A warming climate is predicted to affect both the production of microbial biomass and the stability of microbial residues (necromass) held in soils. However, we have very little information on how warming in tropical soils will affect these processes, and on the effect of temperature on microbial production and turnover over different time-scales. To address this, we studied temperature effects on microbial-mediated C cycling across two different time-scales, using a 20 °C mean annual temperature gradient in the Peruvian Andes (long-term effects) and decadal experimental-warming via soil translocation (11-years of temperature effects). At long-term timescales, a legacy of warmer temperatures decreased microbial carbon use efficiency (CUE), microbial biomass C, and decreased fungal and bacterial necromass concentration in soils. At decadal timescales, experimental warming increased CUE, microbial production and microbial biomass concentration (likely the result of concomitant changes in substrate availability). However, this did not translate into increased microbial necromass concentration, which generally declined with warming across all temporal scales. Together, we show that warmer temperatures over decadal (11-year) timescales affect soil microbial processes to potentially increase their C input to soil (increased CUE, microbial production, and biomass) but we find no evidence that this C became stabilized as the necromass C pool decreased. Our results indicate that warming can alter microbial community metabolism to potentially increase necromass C inputs to soil, although we find no evidence to show that this offset overall soil C loss with warming
The Sedimentary geochemistry and paleoenvironments project phase 2 data release: An open data resource for the study of Earth's environmental history
No full textGeochemical data from sedimentary rocks are the primary source of information regarding Earth's surface evolution through time, including its air and water envelopes and interactions with life and deep Earth processes. The Sedimentary Geochemistry and Paleoenvironments Project (SGP) is a scientific consortium centered around open data and community-driven development of cyberinfrastructure tools and resources for sedimentary geochemistry and Earth history. Here we describe the SGP Phase 2 data release, which focused on incorporating Paleoproterozoic and Mesoproterozoic (2500–1000 million years ago) data and better accommodating carbonate data. This data release was built through the involvement of >200 researchers worldwide in academia, government, and industry, and provides the largest available public data resource for our user community in the academic fields of geochemistry, sedimentology, tectonics, paleontology, Earth history, and paleoclimate, as well as the petroleum and minerals industries. The dataset now encompasses 126,006 samples and 4,132,371 geochemical analyses. In addition to direct entry by SGP Team Members, we have ingested and incorporated datasets from the Geoscience Australia OZCHEM database, the Alberta Geological Survey, and the Deep-Time Marine Sedimentary Element Database (DM-SED) compilation. This paper details sampling in the Phase 2 dataset with respect to age, geography, lithology, and other geological characteristics, documents access via our search website and API, discusses possible issues and/or biases in the dataset that could impact analyses, describes plans for governance and stewardship of data from Indigenous lands, and serves as the citable reference paper for the data release
Power quality improvement of DSTATCOM using fast hybrid-PLL-based control method for wind energy applications
Get PDFIn self-excited induction generator (SEIG)-based wind energy systems, voltage and frequency fluctuate with variations in wind speed and load, reducing power quality and efficiency. A distribution static synchronous compensator (DSTATCOM) is an effective solution to mitigate these fluctuations but requires real-time and accurate control, including precise estimation of voltage and current parameters. This paper proposes a fast hybrid-phase locked loop (FH-PLL)-based DSTATCOM control algorithm, offering superior filtering capabilities and enhanced sensitivity in detecting amplitude, frequency, and phase angle variations. The proposed method significantly improves the performance of DSTATCOM-assisted SEIG energy systems. Unlike conventional alternatives, which often suffer from either low estimation accuracy or high computational complexity, the proposed approach achieves an optimal balance between computational efficiency and estimation precision, making it a superior alternative to existing control algorithms. Comprehensive comparative performance evaluations under various challenging conditions such as non-linear loads, unbalanced loads, open-circuit faults, and measurement offsets, demonstrate that the proposed method achieves the lowest total harmonic distortion (THD) and total demand distortion (TDD) compared to state-of-the-art techniques, including the enhanced phase locked loop (EPLL), second-order generalized integrator (SOGI), and conventional synchronous reference frame PLL (SRF-PLL), while remaining compliant with the relevant IEEE 519-2014 standards
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