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Bayesian filtering based prognostic framework incorporating varying loads
Get PDFUnexpected system failures are costly and preventing them is crucial to guarantee availability and reliability of complex assets. Prognostics help to increase the availability and reliability. However, existing methods have their limitations: physics-based methods have limited adaptivity to specific applications, while data-driven methods heavily rely on (scarcely available) historical data, which reduces their prognostic performance. Especially when operational conditions change over time, existing methods do not always perform well. As a solution, this paper proposes a new framework in which loads are explicitly incorporated in a prognostic method based on Bayesian filtering. This is accomplished by zooming in on the failure mechanism on the material level, thus establishing a quantitative relation between usage and degradation rates. This relation is updated using a Bayesian filter and measured loads, but also allows accurate degradation predictions by considering future (changing) loads. This enables decision support on either operational use or maintenance activities. The performance of the proposed load-controlled prognostic method is demonstrated in an atmospheric corrosion use case, based on a public real data set constructed from annual corrosion measurements on carbon steel specimens. The developed load-controlled particle filter (LCPF) is demonstrated to outperform a method based on a regular particle filter, a regression model and an ARIMA model for this specific scenario with changing operating conditions. The generalization of the framework is demonstrated by two additional conceptual case studies on crack propagation and seal wear
Synergistic effect of Hypoxic Conditioning and Cell-Tethering Colloidal Gels enhanced Productivity of MSC Paracrine Factors and Accelerated Vessel Regeneration
Get PDFMicroporous hydrogels have been widely used for delivering therapeutic cells. However, several critical issues, such as the lack of control over the harsh environment they are subjected to under pathological conditions and rapid egression of cells from the hydrogels, have produced limited therapeutic outcomes. To address these critical challenges, cell-tethering and hypoxic conditioning colloidal hydrogels containing mesenchymal stem cells (MSCs) are introduced to increase the productivity of paracrine factors locally and in a long-term manner. Cell-tethering colloidal hydrogels that are composed of tyramine-conjugated gelatin prevent cells from egressing through on-cell oxidative phenolic crosslinks while providing mechanical stimulation and interconnected microporous networks to allow for host-implant interactions. Oxygenating microparticles encapsulated in tyramine-conjugated colloidal microgels continuously generated oxygen for 2 weeks with rapid diffusion, resulting in maintaining a mild hypoxic condition while MSCs consumed oxygen under severe hypoxia. Synergistically, local retention of MSCs within the mild hypoxic-conditioned and mechanically robust colloidal hydrogels significantly increased the secretion of various angiogenic cytokines and chemokines. The oxygenating colloidal hydrogels induced anti-inflammatory responses, reduced cellular apoptosis, and promoted numerous large blood vessels in vivo. Finally, mice injected with the MSC-tethered oxygenating colloidal hydrogels significantly improved blood flow restoration and muscle regeneration in a hindlimb ischemia (HLI) model.</p
Nutrient production, water consumption, and stresses of large-scale versus small-scale agriculture:A global comparative analysis based on a gridded crop model
Get PDFAgricultural water consumption is the main contributor to water scarcity worldwide, while small-scale and large-scale agriculture have distinguishing characteristics. Significant gaps remain in the process-based agricultural production and water consumption estimates distinguishing small-scale and large-scale agriculture, which inhibits our deep understanding of where, how, and by whom crops are produced and against what water outcomes. We close this gap by leveraging a gridded crop model, covering 61% of the global harvested area using a 2010 baseline. Results show small-scale agriculture accounts for 43% of the total harvested area, however, contributes to relatively less nutrient production despite cultivating more food crops (relative to their total harvested area) than large-scale agriculture. This result challenges the assumption made by existing global scale studies when allocating national agricultural production to small-scale and large-scale agriculture, which (partly) ignores the differences in climate conditions, soil characteristics, input level, and type of irrigation that small-scale versus large-scale agriculture may have. The lower contribution is due to both water and soil fertility stress. Small-scale agriculture overrepresents in water-scarce regions but consumes much less blue water (38%) compared to its harvested area (54%). In water-scarce regions, soil fertility stress causes small-scale agriculture the unproductive green water utilization and a 70–90% unmet crop production potential. Our findings demonstrate the unequal exposure and contribution to water scarcity between small-scale and large-scale agriculture and between food and non-food crops. Understanding such disparities is one of the first and necessary steps toward enhancing the resilience and sustainability of agricultural systems
Web Crawl Refusals:Insights From Common Crawl
No full textWeb crawlers are an indispensable tool for collecting research data. However, they may be blocked by servers for various reasons. This can reduce their coverage. In this early-stage work, we investigate server-side blocks encountered by Common Crawl (CC). We analyze page contents to cover a broader range of refusals than previous work. We construct fine-grained regular expressions to identify refusal pages with precision, finding that at least 1.68% of sites in a CC snapshot exhibit a form of explicit refusal. Significant contributors include large hosters. Our analysis categorizes the forms of refusal messages, from straight blocks to challenges and rate-limiting responses. We are able to extract the reasons for nearly half of the refusals we identify. We find an inconsistent and even incorrect use of HTTP status codes to indicate refusals. Examining the temporal dynamics of refusals, we find that most blocks resolve within one hour, but also that 80% of refusing domains block every request by CC. Our results show that website blocks deserve more attention as they have a relevant impact on crawling projects. We also conclude that standardization to signal refusals would be beneficial for both site operators and web crawlers
Responses of surface runoff and soil water-erosion to changes in seasonal land cover and rainfall intensity; the case of Shilansha watershed, Rift Valley Basin of Ethiopia
Get PDFStudy Region:Shilansha is a watershed located in the Upper Bilate River of the Rift Valley Lake Basin in southern Ethiopia. The region experiences extreme soil water-erosion among the greatest rates globally at 498 tons ha−1 yr−1 leading to large quantities of sediment accumulation in Lake Abaya.Study Focus:Surface runoff, soil water-erosion, and sediment loads in the region vary with agricultural seasons and rainfall intensities but are often poorly quantified in modeling studies. This study assessed these effects using the event-based physically based distributed open-source Limburg Soil Water Erosion Model (OpenLISEM), incorporating local field data and multi-sensor satellite data processed with machine learning techniques.New Hydrological Insights:During the fallow season, simulated surface runoff and total soil loss were 9.7 % and 47 % larger than the growing season and 0.9 % and 42 % larger than the harvest season, respectively. Compared to moderate intensity, an 87 % increase in high rainfall intensity increased surface runoff by 159 % and soil loss by 295 %, while a 45 % decrease in low rainfall intensity reduced surface runoff by 49 % and soil loss by 85 %. High rainfall intensity had a greater impact when combined with fallow season land cover, while effects were smallest when low rainfall intensity combined with growing season land cover. A calibrated model parameter set for a particular season resulted in deteriorated model performance when applied to other seasons. These findings offer insights on the importance of considering seasonal changes in land cover and rainfall intensity when developing soil and water conservation strategies
Habitability and adaptation to a changing climate:Impacts of climate change on agriculture and human mobility in the Kayes and Sikasso Regions, Mali
Get PDFFinite element hybridization of port-Hamiltonian systems
Get PDFIn this contribution, we extend the hybridization framework for the Hodge Laplacian [Awanou et al. (2023) [16]] to port-Hamiltonian systems describing linear wave propagation phenomena. To this aim, a dual field mixed Galerkin discretization is introduced, in which one variable is approximated via conforming finite element spaces, whereas the second is completely local. The mixed formulation is then hybridized to obtain an equivalent formulation that can be more efficiently solved using a static condensation procedure in discrete time. The size reduction achieved thanks to the hybridization is greater than the one obtained for the Hodge Laplacian as the final system only contains the globally coupled traces of one variable. Numerical experiments on the 3D wave and Maxwell equations illustrate the convergence of the method and the size reduction achieved by the hybridization.</p
In-house patient-specific preoperative three-dimensional visualisation for anatomical lung resections
No full textIntroductionFor patients with local non-small cell lung cancer <2cm with poor pulmonary function, a segmentectomy might be considered as a treatment option. However, a segmentectomy is a complex and low-volume procedure. Using three-dimensional (3D) models is proven to be of added value for these procedures and can potentially decrease intraoperative blood loss, operative time and patient complications. Commercial services are costly and require transfer of sensitive patient data to external entities.This study aims to facilitate pre-operative planning of segmentectomies using 3D models produced with an in-house segmentation protocol compared to standard 2D contrast-enhanced CT scans.Methods and results14 patients with stage 1A1-2 NSCLC who underwent a segmentectomy from 2023 to August 2024 were included in the study. An in-house CT-scan segmentation protocol was developed using Mimics software and compared to 3D Slicer segmentation. Informed consent was obtained after local ethics approval. Additionally, surgeons retrospectively filled in questionnaires to estimate changes in the surgical plan. Moreover, each 3D model was given an quality score. Questionnaires revealed that surgeons felt comfortable creating a preoperative plan using 3D models (96%). Quality was perceived as good or excellent in all but one case. The use of 3D models changed 32% of all surgical plans compared to 2D CT. For patients prospectively planned with our 3D models, all relevant structures were correctly identified, and confirmed during surgery.ConclusionsIn all cases, preoperative 3D models showed to have added value in increasing the understanding of patientspecific anatomy, and should be validated externally
Tests and Proofs - 18th International Conference, TAP 2024, Milan, Italy, September 9-10, 2024, Proceedings
No full textTracing metal sources in orogenic gold deposits of the Timburu Goldfield, Meratus, Indonesia:A geochemical and statistical approach
No full textOrogenic gold deposits at the Timburu Goldfield, Indonesia, are primarily hosted by metamorphosed ultramafic and volcanic rocks, as well as quartz lodes formed along shear zones. Gold mineralisation developed along the lithological contacts between serpentinites, porphyritic intrusions, and granitoids. The mineralization is represented by electrum and hessite, with trace amounts of chalcopyrite, galena, tetrahedrite, and Co-Ni-As-S phases. The alteration mineralogy of mafic rocks in Timburu includes magnesite, dolomite, sericite, albite, calcite, and chlorite. This study integrates a multi-statistical evaluation of in-situ trace-element data, geological relationships, and detailed mineralogical characterisation to better understand the evolution of geochemical reservoirs responsible for metal accumulation during orogenic events. Principal component analysis (PCA) produced three significant components that explained 80% of the cumulative variance. We divide the pyrite data into three groups based on trace element correlations, which are likely linked to pyrite texture and paragetic sequences. The results show that the Ni-Co and other metals were leached from metamorphosed ultramafic rocks and mobilised during alteration. Metals, including Au have been released during greenschist- to amphibolite-facies metamorphism in the context of a continent–continent collision. The rare earth element (REE) patterns of metavolcanic and serpentinised ultramafic rocks may be similar to other accretionary complexes formed during continent–continent collision. The transformation of serpentinite to listvenite is controlled by the addition of carbon dioxide and the mobilisation of SiO2, MgO, and CaO. Chemical changes during alteration are primarily dominated by the incorporation of trace elements into pyrite