Variable Depths Research Articles

Stable hydrogen and oxygen isotope geochemistry of Fe3+-rich, interstratified clay minerals from seafloor hydrothermal sites

Chemical and structural complexities in interstratified clay minerals arising from mineral transformations and evolving formation conditions should be recorded in their stable isotope signatures. This paper examines the controls on the stable hydrogen and oxygen isotope compositions of Fe3+-rich, glauconite-nontronite, talc-nontronite and talc-saponite from submarine hydrothermal sites, with a focus on the Red Sea Atlantis II Deep. Values of δ18O became less positive in the order nontronite > glauconite-nontronite > talc-nontronite > talc-saponite, yielding oxygen isotope temperatures ranging from ∼40 °C for nontronite to ∼135–300 °C for talc-saponite. These clay minerals have low δ2H, ranging from −145 to −127‰ for talc-nontronite, −135‰ for nontronite, −129 to −85‰ for glauconite-nontronite, and −95 to −59‰ for talc-saponite. The clay mineral-water hydrogen isotope fractionation is strongly affected by Fe3+ content, with increasing structural Fe3+ causing progressive weakening of O-H bonds. The large ionic radius and high charge of Fe3+ cause it to be more poorly shielded by surrounding oxygen from hydroxyl hydrogen relative to other octahedral or tetrahedral cations. The resulting lengthening of O-H bonds favours 1H over 2H. Our results confirm that Fe-rich phases, such as nontronite-glauconite, are produced at the lowest temperatures and Mg-rich phases, such as talc-saponite, are formed at the highest temperatures in seafloor hydrothermal environments. Evolving fluid chemistry and fluid pathways during clay mineral formation are also important. Glauconite layer formation from precursor nontronite likely occurred during diagenesis; redox changes causing Fe-reduction and an increase in layer charge facilitated interlayer K-fixation. Talc-saponite compositions vary with temperature and fluid chemistry, forming at variable sediment depths depending on access to the hottest hydrothermal fluids.

Thermal photogrammetry on a permafrost rock wall for the active layer monitoring

Permafrost and active layer models often cannot explain the high spatial variability, especially in heterogeneous environments like the mountainous regions due to their scarce resolution, paucity of climatic data and topographic details. In this study, we want to introduce a new application of the unmanned aerial vehicle (UAV) in thermal photogrammetry to model the active layer thickness (ALT) of an alpine rock wall through the computation of the thermal inertia and compare the results with a widespread ALT model. On the Gran Zebrù South rock wall, 8 thermal UAV surveys has been conducted in 4 different summer days during 2021-2022 in order to have two 3D thermal models per day at different solar radiation inputs. By analyzing topographic data, visible imagery and the thermal models, the apparent thermal inertias (ATIs) have been converted into heat transfer coefficients (HTCs) and then into ALT of 2021 and 2022. These maps have been validated through the placement of thermistors at different elevations and with variable depths (2, 15 and 40 cm from the rock surface).The resulting ALT has been compared with the Stefan's solution and the alpine permafrost index map (APIM), which showed large underestimations and a noncorrespondence with permafrost occurrence. The average ALT increase of 29.3 cm from 2021 to 2022 has been discussed regarding permafrost formation/degradation future trend under the climatic change and potential risks of alpine areas.

Oxygen Fugacity of Global Ocean Island Basalts

AbstractMantle plumes contain heterogenous chemical components and sample variable depths of the mantle, enabling glimpses into the compositional structure of Earth's interior. In this study, we evaluated ocean island basalts (OIB) from nine plume locations to provide a global and systematic assessment of the relationship between fO2 and He‐Sr‐Nd‐Pb‐W‐Os isotopic compositions. Ocean island basalts from the Pacific (Austral Islands, Hawaii, Mangaia, Samoa, Pitcairn), Atlantic (Azores, Canary Islands, St. Helena), and Indian Oceans (La Réunion) reveal that fO2 in OIB is heterogeneous both within and among hotspots. Taken together with previous studies, global OIB have elevated and heterogenous fO2 (average = +0.5 ∆FMQ; 2SD = 1.5) relative to prior estimates of global mid‐ocean ridge basalts (MORB; average = −0.1 ∆FMQ; 2SD = 0.6), though many individual OIB overlap MORB. Specific mantle components, such as HIMU and enriched mantle 2 (EM2), defined by radiogenic Pb and Sr isotopic compositions compared to other OIB, respectively, have distinctly high fO2 based on statistical analysis. Elevated fO2 in OIB samples of these components is associated with higher whole‐rock CaO/Al2O3 and olivine CaO content, which may be linked to recycled carbonated oceanic crust. EM1‐type and geochemically depleted OIB are generally not as oxidized, possibly due to limited oxidizing potential of the recycled material in the enriched mantle 1 (EM1) component (e.g., sediment) or lack of recycled materials in geochemically depleted OIB. Despite systematic offset of the fO2 among EM1‐, EM2‐, and HIMU‐type OIB, geochemical indices of lithospheric recycling, such as Sr‐Nd‐Pb‐Os isotopic systems, generally do not correlate with fO2.

Intelligent monitoring of milling tool wear based on milling force coefficients by prediction of instantaneous milling forces

The spindle current of a machine tool contains a wealth of machining information and by analyzing its signal characteristics wear monitoring of milling tools can be achieved. Most current research in tool wear monitoring has been achieved by intelligent classification methods, but such methods are unable to identify wear states when cutting parameters change. To address this challenge, the paper proposes a new tool wear monitoring framework that identifies the wear state of milling cutters under different cutting parameters. The first step is to establish the mapping relationship between the spindle current signal and the milling force signal through neural networks under a variety of cutting parameters. Based on the mapping property between two signals, a TCN-LSTM based neural network prediction model is proposed to achieve accurate prediction of milling forces by spindle current signal. Various cutting information is then calculated based on the predicted milling forces and PLC communication, and a method is proposed to identify the machining status of the tool: the milling force coefficient monitoring method. The method reflect the wear status of the milling cutter by monitoring the range of threshold values, making the identification of the tool wear state without interference from variable spindle speeds, feeds and depths of cut. The proposed method provides a new solution for tool wear monitoring, breaking the inherent thinking of intelligent tool wear classification, and the experimental results prove the effectiveness and generality of the proposed method.

Multi-property digital soil mapping at 30-m spatial resolution down to 1 m using extreme gradient boosting tree model and environmental covariates

Information on the variability of soil properties including clay, calcium carbonate equivalent (CCE) and acidity (pH) in space and depth play major role in sustainable agricultural development but scarce in many regions in the world, specifically in developing countries. Digital soil mapping technique has shown strong success in the prediction of soil properties both in space and depth from their relationship with environmental covariates. The aim of the study was to digitally map soil properties including clay, CCE and pH at multiple depths and identify the dominant factors controlling their variability using Minadoab region of Iran as a case study area due to its significance for agricultural production and economic development in the country. A total of 104 soil profiles were randomly selected and described in field during 15–30 July 2017, and 386 samples were collected from each genetic horizon with variable depths. A continuous spline function was fitted to the horizon data and properties were estimated at five standardized depths following GlobalSoilMap project. The soil layers were then grouped into three classes: i) H1: top (0–5 cm); ii) H2–H4: middle (5–15, 15–30 and 30–60 cm); and iii) H5: bottom (60–100 cm) for easy interpretation. A total of 17 static environmental covariates were derived from terrain-related attributes. Additionally, matching with the soil sampling date, a total of eight band ratios in addition to six individual bands were derived from Landsat-8 OLI (Product ID: LC08_L1TP_168034_20170721_20170728_01_T1) for the study area. Finally, all covariates were categorized in nine groups representing various factors controlling soil variations. The digital maps associated with uncertainties were prepared using extreme gradient boosting (XGBoost) Tree model and bootstrapping method, respectively. Overall, the highest accuracy using XGBoost Tree model was found for CCE (R2 = 0.73, on average), followed by pH (R2 = 0.72, on average) and clay (R2 = 0.70, on average). The highest amount of clay was observed for the bottom layer, followed by middle and top layers across the study area. H1 to H3 layers were subjected to tillage operations over the time and may have contributed to the redistribution of clays. A similar trend was also observed for CCE and pH as the location of the study area is underlain by massive limestone. The uncertainties helped quantify over- and under-estimation of the predictions and the factors with the highest variable importance was identified as the dominant factor. The information generated for the study area provides soil variability information that is critical for developing management strategies for sustainable production in the area.

Prediction of dissolved organic nitrogen via spectroscopic fingerprint in the shallow riverbed sediments of effluent-dominated rivers: A case study in Xi’an, northwest China

An evaluation on the impacts of effluent discharge to receiving rivers is in demand. Discharged dissolved organic nitrogen (DON) with high eutrophication potentials tends to accumulate in the shallow riverbed sediments especially for effluent-dominated rivers. Since DON characterization requires for advanced analytical tools, there is thereby a need but it is still a challenge to evaluate their distribution and transformation in the riverbed sediments. Considering the fact that DON is an important part of dissolved organic matter (DOM), which has plentiful spectral information, the authors hypothesize if it is feasible to predict DON variations in riverbed sediments via the DOM properties in surface water or sediment porewater? Here, the spatiotemporal spectral characteristics of DOM in river water and sediment porewater of two effluent-dominated rivers were investigated. Compared to surface water, more abundant relationships among fluorephores and spectra-derived parameters in porewater were observed. The relatively high DON contents in both surface water (0.16–0.47 mg-N/L) and sediment porewater (0.35–5.02 mg-N/L) compared to those reported in other natural waters highlighted the importance in predicting DON in effluent-dominated rivers. The DON in the oxic zone from winter samples carried more humus-like signals, while the fractions in summer samples recognized protein-like and humus-like signals. Two machine learning methods, i.e., random forest (RF) and extreme gradient boosting (XGBoost) were employed to provide evidence-based information on how DON contents and properties differed at variable depths. RF (R2: 0.920, 0.475) outperformed XGBoost (R2: 0.488, 0.316) in predicting DON in winter-oxic zone and winter-suboxic zone. While XGboot (R2: 0.515, 0.787) is superior than RF (R2: 0.317, 0.567) in summer-oxic zone and summer-suboxic zone. Fluorophore of C1 served as the most important variable for predicting DON in winter samples in both models. SUVA260 and SUVA280 were verified most impressive predictor for samples from suboxic zone in summer in both models. HIX represented the most important variable predicting DON in summer samples in XGBoost model. These findings are critical for understanding the transformation processes of DON in the shallow riverbed sediments in receiving rivers, and could provide important implications to improve wastewater discharge management and river health.

Crustal structure of onshore-offshore Atlantic Canada and environs from constrained 3-D gravity inversion using variable mesh depths

SUMMARYAtlantic Canada encompasses geological evidence of the orogenic and rifting episodes that inspired the development of the theory of plate tectonics and the fundamental concept of the Wilson cycle. To provide a regional crustal-scale view that can complement surface mapping studies and sparse seismological investigations, an onshore–offshore 3-D constrained gravity inversion methodology is proposed involving incorporation of topography and an inversion mesh that is laterally variable in terms of its maximum depth extent. A 3-D density anomaly model for the entirety of Atlantic Canada and its environs is generated, with the inverted density distribution structure and extracted isodensity surfaces showing excellent correspondence with independent and co-located controlled source and passive seismic constraints. The full density model and crustal thicknesses from this work are made freely available so that they may be used for further study, for instance as inputs for deformable plate reconstruction modelling.

Health Diagnosis for Lithium-Ion Battery by Combining Partial Incremental Capacity and Deep Belief Network During Insufficient Discharge Profile

Accurate state of health (SOH) estimation of lithium-ion batteries provides scientific basis for secure operation and stepwise utilization in on-board powertrain. However, the variable discharge depths inevitably reduce the elasticity and precision of the estimation method in prevalent partial discharge situations. In this work, multiple candidate health indicators are extracted from the peaks and valleys of the partial incremental capacity curves and screened firstly. Specifically, the fine-tuning process of deep belief network (DBN) based on particle swarm optimization are elaborated and synthetic comparison in terms of error and time consumption with three classical deep networks is performed. To better accommodate practical scenarios, three datasets of the LiFePO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{4}$</tex-math></inline-formula> cells under different discharge depth are applied to verify the proposed framework. The experimental results indicated that the presented framework is feasible and the prediction error can be minimized to less 2%.

Mesozoic crustal reworking at different depths in the North China Craton: Insight from the coexisting Early Cretaceous high and low Sr/Y granitoids

Crustal reworking, an important part of continental evolution, can occur in cratons even though they are generally rigid and stable. However, the reworking mechanisms are still debated. Here, we present detailed zircon UPb ages, mineral compositions, major and trace elements, and Sr–Nd–Pb–Hf isotopic data for the coexisting high and low Sr/Y granitoids in the Liaodong Peninsula to decipher the reworking mechanism in the eastern North China Craton (NCC). Mafic microgranular enclaves (MMEs) are common in the studied granitoids, and both the granitoids and their MMEs have consistent emplacement ages of 128–126 Ma. The low and high Sr/Y granitoids are characterized by high-K calc-alkaline I-type granites. They are enriched in light rare earth elements (REEs) and large ion lithophile elements (e.g., Rb, K, and Pb), with depletions in high field strength elements (e.g., Nb, Ta, P, and Ti). The low Sr/Y granitoids have homogeneous Sr–Nd–Pb-Hf isotopic compositions, indistinguishable from those of their MMEs, indicating that they are of cognate origin. Their high (87Sr/86Sr)i (0.713759–0.715341), low εNd(t) and εHf(t) values (−19.2 to −18.1 and − 20.9 to −15.0, respectively), and old two-stage Nd and Hf model ages (ca. 2.50 Ga) suggest that they are derived from partial melting of the ancient lower crust at a normal crustal depth. In contrast, the high Sr/Y granitoids show more depleted heavy REEs and higher Sr/Y (21.1–80.2) and (La/Yb)N (19.2–50.2) ratios, with very low Y (≤ 12.5 ppm) and Yb (≤ 1.11 ppm) contents and negligible Eu anomalies. Their enriched and variable Sr–Nd–Pb-Hf isotopes (e.g., εNd(t) = −20.8 to −14.9, εHf(t) = −24.3 to −9.2) are distinctly different from those of their MMEs (e.g., εNd(t) = −17.6 to −13.2, εHf(t) = −20.8 to −0.3), implying a magma mixing process. These features suggest that the high Sr/Y granitoids and their MMEs are formed by mixing of the thickened ancient lower crustal and lithospheric mantle-derived magmas, with minor contributions of the asthenospheric mantle. Combined with the coeval (129–114 Ma) high-Mg adakitic and A-type granitoids, the coexisting high and low Sr/Y granitoids may indicate intensive crustal reworking at variable depths in the NCC. The reworking is attributed to the asthenosphere upwelling and lithospheric delamination induced by the rollback of the subducting Paleo-Pacific plate.

Experimental investigation into the effects of voids on the response of buried flexible pipes subjected to incrementally increasing cyclic loading

In this study, large-scale fully instrumented laboratory tests were conducted to investigate the behaviour of buried flexible high-density polyethylene (HDPE) pipes, in sand beds with and without voids subjected to incrementally increasing cyclic loading. Voids with a predetermined size were created at one side of the spring-lines of the pipes, which were buried at variable depths, H, of 1.5, 2.0 and 2.5 times the diameter of the pipe, D. Results showed that increasing the pipe burial depth, H/D, contributed to decreasing the settlement of the footing, deformation of the pipe crown and invert, lateral displacement of the spring-line, and the stress and strain generated along the pipe crown and invert. Void presence led to a significant increase in the footing settlement, which ranged from 3 % up to 18 %, according to H/D. Furthermore, void presence led to a sharp increase in the crown, invert, and spring-line settlements, which ranged from 34 % to 52 %, 10 %–12.5 %, and 13 %–38 %, respectively. Increasing pipe burial depth was found to be highly effective in protecting buried pipes, minimising inevitable consequences of the presence of voids. However, this was combined with an increase in the pressure at the pipe spring-line that led to a positive horizontal support at the pipe's spring-lines resulting in reducing pipe deformation.

Seasonal spatial ecology of Lake Trout in Lake Erie

AbstractObjectiveLake Trout Salvelinus namaycush are native coldwater apex predators that play an important role in maintaining ecosystem functionality and diversity in the Laurentian Great Lakes. Following population collapses, rehabilitation efforts were widely initiated in the Great Lakes to reestablish self‐sustaining Lake Trout populations. Lake Erie may pose a challenge to these rehabilitation efforts due to limited availability of appropriate oxythermal habitat. Our goal was to investigate seasonal habitat use of adult Lake Trout in Lake Erie to inform management and rehabilitation efforts.MethodsWe used acoustic telemetry in Lake Erie, which was equiped with a lake‐wide acoustic receiver grid, to quantify Lake Trout seasonal region occupancy, dispersal distances, bottom depth occupancy, space use extent, and space use overlap.ResultWe found that 32% of fish tagged in the eastern basin and all fish from the western basin dispersed more than 100 km from their tagging location, which represents a greater proportion of the population moving long distances than what has been previously documented in the Great Lakes. During stratification, Lake Trout were detected almost exclusively in the offshore eastern basin in areas where water depth exceeded 25 m. During nonstratified seasons, fish used other regions of the lake, occupying areas of highly variable depths. During fall, most fish tagged in the eastern basin occupied habitat along the southern shore of the eastern basin. Fish tagged in the western basin returned to this region in the fall of subsequent years despite occupying the offshore eastern basin during stratification and having depth occupancy, home range size, and overlap similar to that of eastern basin‐tagged fish. Fish size was positively correlated with receiver depth during winter and spring, and with home range overlap during spring and summer.ConclusionThe results of this study can begin to inform management decisions regarding stocking locations, harvest regulations, and habitat restoration to facilitate the continued rehabilitation of this important native species.

The early Late Triassic Yumen mafic rocks in the eastern Tethyan Himalaya: A record of the progressive opening of the Yarlung Zangbo Neo-Tethyan Ocean

The timing of the opening of the Yarlung Zangbo Neo–Tethyan Ocean (YZNTO) is debated. In this contribution, geochemical and geochronological analyses of diabase, pillow basalt and layered basalt from the Upper Triassic Yumen tectonic mélange (T3Y) of the eastern Tethyan Himalaya in South Tibet are used to elucidate the timing and the magmatic evolution preceding the development of the YZNTO. Zircon U-Pb geochronology indicates that the Yumen mafic rocks crystallized in the Late Triassic (diabase, c. 225 Ma). These rocks display alkaline basalt affinities and have variable enrichment in Ba, U, Pb, Sr and Ti and depletion in Rb, Th and Nb. The diabase and pillow basalt samples have compositions transitional between enriched mid–ocean ridge basalt and ocean island basalt (OIB); layered basalt is more compatible with an OIB affinity. Whole–rock εNd (t) ratios of the mafic rocks range from +5.5 to +11.5 and zircons from a diabase have εHf(t) values varying from – 1.1 to +10.0. Whole–rock trace element concentrations indicate that the parental magmas of the Yumen mafic rocks were derived from the mantle at variable depths extending from the garnet to spinel stability fields. The Yumen mafic rocks originated from partial melting of a heterogeneous magma source composed of dominant depleted asthenospheric magmas and the addition of some components of an ancient and enriched lithospheric mantle; negligible crustal contamination occurred. Combined with previous studies, we conclude that the Yumen mafic rocks were probably produced in an intercontinental rift setting with extremely thin continental lithosphere in the early Late Triassic prior to the opening of the eastern YZNTO. The YZNTO progressively opened along the northern edge of the Indian plate from west to east in the Phanerozoic.

A new way to visualize prostate brachytherapy needles using ultrasound color Doppler and needle surface modifications

Suboptimal ultrasound conspicuity of the brachytherapy applicator can lead to inaccurate image reconstructions of the applicator resulting in decreased tumor control or increased normal tissue dose. This feasibility study aims to improve ultrasound conspicuity of high-dose rate (HDR) brachytherapy needles by modifying the surface of the needles to produce a color Doppler twinkling signature. Surface modifications of standard 17-gauge titanium HDR brachytherapy needles included laser-scribing, application of polymethyl methacrylate (PMMA), and coating with a commercially available echogenic coating. Laser-scribing was performed with variable widths (0.1-1 mm) and depths (10-100 μm). The echogenic coating was applied with 3 different thicknesses (27, 40, and 64 μm). Unmodified and modified needles were imaged under B-mode and color Doppler ultrasound in phantom and cadaver, and the signal strength was recorded. Laser-scribed, PMMA-coated, and echogenic-coated brachytherapy needles produced a twinkling signature along the needle shaft on color Doppler ultrasound. Twinkling was observed with laser-scribe depths >20 μm and widths >0.1 mm and from echogenic coatings 40 μm and 64 μm thick. Twinkling was not observed with unmodified needles. The twinkling signature had a spectral composition with a uniform magnitude between the velocities of 2 to 16 cm/s. Color Doppler ultrasound of surface-modified brachytherapy applicators may improve applicator conspicuity aiding applicator placement and digitization. HDR brachytherapy needles may be modified to produce the twinkling signature via laser-scribing, PMMA rings, or applying an echogenic coating.

Carbon and Nitrogen Mineralization Kinetics in Soil Under Differential Nutrient Management Regimes in Inceptisols of Coastal India

ABSTRACT In intensive cropping systems, nutrient, and residue management techniques have a tendency to change the soil’s carbon (C) and nitrogen (N) cycle and, consequently, its potential for sequestration and loss. To understand the carbon and nitrogen mineralization kinetics, laboratory incubation studies were conducted with soils at variable depths from a long-term nutrient management experiment on cereal-vegetable-pulse cropping system. The experiment was laid out completely randomized design with 10 treatments replicated thrice. Long-term integrated application of inorganics with organics, biofertilizers, and amendment along with crop residues showed higher carbon and nitrogen mineralization potential and lower potential was observed in soils where crops were raised without application of any nutrient inputs (control) and uncultivated fallow. It was calculated that the potential for higher levels of carbon and nitrogen mineralization existed in the surface (0–15 cm) and subsurface (15–30 cm) layers, respectively, and was negligible in the deeper layer (30–45 cm). The mineralization rate was initially faster up to 42 days of incubation, indicating proper utilization of readily decomposable soil organic matter in the labile pools and thereafter found to slow down. Addition of lime along with the integrated use of organics and inorganics has found to raise the pH to a level that provides a suitable soil environment which affects the carbon and nitrogen mineralization kinetics resulting in buildup of total organic carbon and total nitrogen in the soils. The first-order kinetic model was the best fit in explaining the kinetic parameters of C and N mineralization. Soils under integrated nutrient management (INM) with farmyard manure (FYM) along with biofertilizers, amendment, and inorganic nutrients exhibited better carbon dynamics higher C mineralization (Cmin), potentially mineralizable C (C0), rate of C mineralization (dCmin/dt), and C mineralization quotient (qM), whereas soils applied with similar combinations with vermicompost was found effective for better nitrogen dynamics in terms of enhanced N mineralization (Nmin), potentially mineralizable N (N0), rate of N mineralization (dNmin/dt) and active N fraction over control and fallow soils. Integrated application of inorganic and organic inputs with crop residues over the years has shown beneficial impacts on soil carbon and nitrogen mineralization processes and their kinetics.

Field and laboratory validation of new sampling gear to quantify coregonine egg deposition and larval emergence across spawning habitat gradients

The influence of habitat and environmental conditions on Great Lakes coregonine reproduction is not well described, in part, because we lack sampling gears for early life stages that are effective across habitats. We designed new egg and larval emergence traps to quantify coregonine reproductive success across variable depths and substrates and tested them in laboratory and field settings. In the laboratory, our new metal ring egg traps had greater egg retention (94–100%) and faster post-catch processing (5–7 min) relative to a commonly employed fiber mat trap (30–67% and 30–60 min). In Lake Ontario’s Chaumont Bay, egg densities for lake whitefish Coregonus clupeaformis (0–5,832 eggs m−2) and cisco Coregonus artedi (0–426,501 eggs m−2) measured with metal ring traps (n = 112) varied across habitats but were greatest between 2–5 m on rock and dreissenid mussel substrates. Emergence traps used an inverted cone, fine mesh, and a clear collection chamber to capture positively phototactic emerging larvae. In the laboratory, traps captured 69–80% of emerged larvae. In Chaumont Bay, emergence traps deployed for 21 days after ice out caught only cisco larvae. Emergence rates varied across habitats (0–118 larvae m−2 day−1, n = 85) but were highest on dreissenid mussel reef substrate. Our samplers improved processing efficiency and facilitated large sample sizes to quantify variability in egg deposition densities and emergence rates across habitats. These methods can advance coregonine conservation by determining how anthropogenic changes to habitat and environmental conditions influence incubation success.

Volatiles and Intraplate Magmatism: a Variable Role for Carbonated and Altered Oceanic Lithosphere in Ocean Island Basalt Formation

Abstract Recycling of material at subduction zones has fundamental implications for melt composition and mantle rheology. Ocean island basalts (OIBs) sample parts of the mantle from variable depths that have been diversely affected by subduction zone processes and materials, including the subducted slab, metasomatising melts and fluids. Resultant geochemical differences are preserved at a variety of scales from melt inclusions to whole rocks, from individual islands to chains of islands. Here we examine a global dataset of ocean island basalt compositions with a view to understanding the connection between silica-saturation, olivine compositions, and halogens in glass and olivine-hosted melt inclusions to reveal information regarding the mantle sources of intraplate magmatism. We find that minor elements incorporated into olivine, although informative, cannot unambiguously discriminate between different source contributions, but indicate that none of the OIB analysed here are derived solely from dry peridotite melting. Nor can differences in lithospheric thickness explain trace element variability in olivine between different ocean islands. We present new halogen (F, Cl, Br/Cl, I/Cl) data along with incompatible trace element data for the global array and encourage measurement of fluorine along with heavier halogens to obtain better insight into halogen cycling. We suggest that Ti-rich silica-undersaturated melts require a contribution from carbonated lithosphere, either peridotite or eclogite and are an important component sampled by ocean island basalts, together with altered oceanic crust. These results provide new insights into our understanding of mantle-scale geochemical cycles, and also lead to the potential for the mantle transition zone as an underestimated source for observed volatile and trace-element enrichment in ocean island basalts.

Deep Learning Stranded Neural Network Model for the Detection of Sensory Triggered Events

Maintenance processes are of high importance for industrial plants. They have to be performed regularly and uninterruptedly. To assist maintenance personnel, industrial sensors monitored by distributed control systems observe and collect several machinery parameters in the cloud. Then, machine learning algorithms try to match patterns and classify abnormal behaviors. This paper presents a new deep learning model called stranded-NN. This model uses a set of NN models of variable layer depths depending on the input. This way, the proposed model can classify different types of emergencies occurring in different time intervals; real-time, close-to-real-time, or periodic. The proposed stranded-NN model has been compared against existing fixed-depth MLPs and LSTM networks used by the industry. Experimentation has shown that the stranded-NN model can outperform fixed depth MLPs 15–21% more in terms of accuracy for real-time events and at least 10–14% more for close-to-real-time events. Regarding LSTMs of the same memory depth as the NN strand input, the stranded NN presents similar results in terms of accuracy for a specific number of strands. Nevertheless, the stranded-NN model’s ability to maintain multiple trained strands makes it a superior and more flexible classification and prediction solution than its LSTM counterpart, as well as being faster at training and classification.

Effect of low-permeability layers on vadose well recharge rates

Recharge in unconfined aquifers during Managed Aquifer Recharge (MAR) is influenced by the lithologic characteristics of the vadose zone. The capacity of vadose wells to achieve recharge rates above those possible with recharge basins is studied in heterogeneous unsaturated porous media. Although near-surface low permeability layers can be bypassed with vadose wells, subsequent low permeability layers below or adjacent to the well screen influence recharge rates by forming perched conditions. The numerical model VS2DTI was used to evaluate the effect of heterogeneous lithology on vadose well recharge. A sand aquifer was modeled using hydrogeologic characteristics from the Hueco-Bolson aquifer in Texas. Modeled recharge was studied for a 33 m deep vadose well with a 10 m high water column evaluated under conditions of both a homogenous aquifer and an aquifer with heterogeneity formed by a thin, low permeability clay layer. These low permeability layers were modeled at various depths alongside and below the well to study the impact of heterogeneity on MAR processes. Results contrast vadose wells a) without clay layers to recharge 200.6 m3/d, considered the well's maximum (100%) efficiency, and b) inclusion of clay layers creating perched conditions which are shown to reduce recharge. Specifically, recharge rates greater than 180 m3/d (90% efficiency) occur if the clay layer was aligned at or above the upper half of the well screen. Simulating the low permeability clay layer along the bottom half of the well caused recharge rates reduction to a minimum of 30 m3/d (15% efficiency). Rates above 100 m3/d (50% efficiency) occurred when the clay layer was 10 m below the base of the well. These results characterize the impact of low permeability layer distance adjacent to and below a vadose well. A low permeability horizon at a fixed depth relative to vadose wells at variable depths was also studied to demonstrate that recharge rate increases corresponding to deeper vadose wells due to additional screen length and greater pressure head. Results quantify the impact of vadose well placement relative to low permeability layer depth, and promote understanding to achieve design recharge rates using the fewest and shallowest wells possible.

Assessing the Impact of Rutting Depth of Bituminous Airport Runway Pavements on Aircraft Landing Braking Distance during Intense Precipitation

A runway pavement during its useful life is subject to a series of deteriorations because of repeated load cycles and environmental conditions. One of the most common deteriorations is the formation of rutting (surface depression in the wheel path) on the runway surface. Rutting negatively affects aircraft performance during landings and will behave even worse during precipitation or with the existence of fluid contaminations on the surface. This paper aims to develop a model for calculating aircraft braking distance during landing on wet-pavement runways affected by rutting based on dynamic skid resistances generated by tire–fluid–pavement interactions. Intense precipitation, variable rutting depths for a 100 m length step, water film depths (e.g., 1 to 26 mm), and aircraft wheel loads (e.g., 10 to 140 kN) are considered as the boundary conditions of the developed model. The output is a model that can estimate aircraft braking distance as a function of rutting depth and can perform further assessment of the probability of the occurrence of landing overrun. After validating the model with existing methodologies and calibrating it according to the actual landing distance required for each type of aircraft, an Italian airport is simulated using a model with real data regarding the level of service of its pavement surface characteristics.

Optimization of patient positioning for improved healing after corneal transplantation

Corneal transplantation is the only solution which avoids loss of vision, when endothelial cells are dramatically lost. The surgery involves injecting gas into the anterior chamber of the eye, to create a bubble that pushes onto the donor cornea (graft), achieving sutureless adherence to the host cornea. During the postoperative period, patient positioning affects the bubble. To improve healing, we study the shape of the gas-bubble interface throughout the postoperative period, by numerically solving the equations of fluid motion. Patient-specific anterior chambers (ACs) of variable anterior chamber depths (ACD) are considered, for either phakic (with natural lens) and pseudophakic (with artificial lens) eyes. For each AC, gas-graft coverage is computed for different gas fill and patient positioning. The results show that the influence of positioning is negligible, regardless of gas filling, as long as the ACD is small. However, when the ACD value increases, patient positioning becomes important, especially for pseudophakic ACs. The difference between best and worst patient positioning over time, for each AC, is negligible for small ACD but significant for larger ACD, especially for pseudophakic eyes, where guidelines for optimal positioning become essential. Finally, mapping of the bubble position highlights the importance of patient positioning for an even gas-graft coverage.