Source Depth Research Articles

A Flexible Antibacterial Gel Electrochemiluminescence Device for Monitoring and Therapy of Chronic Diabetic Wounds

ABSTRACTThe rapid development of internal light‐driven photodynamic therapy stems from its capability to eliminate bulky physical light sources, addressing the medical requirements for comfort and portability in long‐term diabetic wound management. To overcome limitations such as tissue penetration depth and controllability of internal light sources, this study introduces an antibacterial gel electrochemiluminescence device for the treatment of diabetic wounds and the monitoring of wound bacteria. We deploy a large‐area luminescent device combining flexible screen‐printed electrodes and a dual‐network hydrogel, in which photodynamic therapy is driven by Ru@COFs' nanoconfinement‐enhanced near‐infrared electrochemiluminescence to achieve a deeper and safer antibacterial effect. The custom‐sized screen‐printed electrodes inherit the inborn electrochemical sensing function and enable intimate contact between reactive oxygen species and the wound. The device avoids physical light sources and provides a new paradigm for developing miniaturized integrated diagnostic and therapeutic wearable devices.

Chuprov invariant for vector-scalar fields of multipole sources in a shallow sea

A computational and theoretical study of the properties of the well-known waveguide invariant S.D. Chuprova (IC) was carried out in a plane-parallel Pekeris waveguide. Unlike earlier works, in which predominantly non-directional (monopole) sources were used as a source, and sound pressure fields (scalar fields) were studied, in this work not only scalar, but also vector fields formed in the waveguide by directional - combined multipole sources with directivity in both horizontal and vertical planes. A differential equation has been obtained that makes it possible to fairly accurately calculate the IC values under different conditions of signal propagation and different depths of sources and receivers. This makes it possible, in a simpler way than “full computer modeling,” to predict the invariance (stability) of the IC when varying both the hydrophysical conditions in the waveguide and the geometry of the experiment. It is shown that the directionality of sources in the horizontal plane has virtually no effect on the properties of the IC, and the directionality in the vertical plane leads to a shift in the fan structure of the signal amplitude fields, but has little effect on the IC values. The properties of the fan structure change in a similar way when using vertical projections of the oscillatory velocity vector - despite the fact that another analytical relation, different from scalar fields, is used to calculate the IC, the IC value is close to (+1) at all frequencies and distances, except those at which new modes or dislocations arise. At these frequencies and in these zones, alternating emissions with different signs and magnitudes occur. It is concluded that the stability of IC allows the application of signal processing algorithms developed for scalar fields and non-directional sources to vector-scalar fields generated, including using directional sources.

Tectonomagmatic evolution of Pune – Nasik Deccan Dykes: Insights from structure and dimension scaling

The Deccan Continental Flood Basalt of the Indian Peninsula is characterized by extensive basaltic eruptions ornamented with three spectacular distinct dyke swarms: the Pune – Nasik, Narmada – Tapi, and Western Coastal dyke swarms. Our study area is the Pune – Nasik dyke swarm, which has ~465 mappable dykes. These dykes exhibit different orientations with a predominant trend of N101° and vary in length from less than 1 km to ~64 km. These dykes are massively jointed and occasionally contain vesicles filled with secondary minerals like quartz and calcite. The host rock is weathered basalt of various older Deccan flows. In this study, we have calculated magmatic overpressures and magma chamber depths using the aspect ratios (length/thickness) of the dykes. The average estimated source depth is ~13 km, based on an average Young's modulus for the host rock basalt (Eavg, 7.5 GPa). Additionally, we compared the inferred magma source depths of the Pune – Nasik, and Narmada-Tapi dyke swarms which include the Nandurbar – Dhule, and Pachmarhi dykes of the Deccan Flood Basalt Province. Our findings indicate that the magma chamber source depth is greater in the Pune – Nasik dyke swarm compared with other dyke swarms. The variation in strike distribution of the Pune-Nasik dyke swarm may be attributed to several factors, including a larger magma chamber, local stress fields generated by shallow magma chamber, or the superimposition of tectonic stress fields (N-S and E-W extension) during the emplacement of dykes. This contrasts with the commonly held belief that the dykes are solely connected to a central edifice of the Reunion hotspot.

Geophysical and geospatial insights into surface and subsurface characteristics for groundwater potential analysis, Ras Sudr, West Sinai, Egypt

Ras Sudr has garnered significant interest owing to various initiatives aimed at expanding and developing this area. It holds considerable strategic importance, serving as a key development hub in Sinai and a focal point for tourism destination. Moreover, it has a remarkable event with flashfloods which can be utilized for groundwater or direct usage. Integrating geophysical and geospatial analyses to study the surface and subsurface characteristics as well as identify groundwater potential areas in Ras Sudr, west-central Sinai is the main objective of this study. Firstly, geophysical data including gravity and magnetic methods have a crucial importance in qualitative and quantitative interpretation of the subsurface elements. Filtering techniques were implemented to distinguish between regional and residual anomalies. Geophysical data were subjected to the radial average power spectrum technique and 3D Euler deconvolution to identify the depth of the subsurface sources. The structure pattern that characterizes the interested region was defined by employing bandpass filter and edge detection appoarches using residual anomaly maps, regional anomaly maps, tilt derivatives and total horizontal gradient maps reflecting four distinct structural trends; NW-SE parallel to the Gulf of Suez, NEE-SWW parallel to the Syrian arc system, N-S parallel to the the Nile Valley, and NNE-SSW parallel to the Gulf of Aqaba. A basement relief map was constructed using 3D magnetic modelling showing that the depth of the basement ranges from 1.6 to 6.3 km. Secondly, the remote sensing data including Sentienl-2 and SRTM datasets were employed to extract the surface analyses in the GIS environment to develop the occurrence of groundwater potentiality utilizing seven factors; LU-LC, soil, geology, slope, drainage network and lineament density and rainfall data of the study area which were ranked from 1 to 5 and weighted according to their effective contribution to the infiltration of groundwater using AHP-GIS based multi criteria method. The resulting Groundwater Potential zone (GWPZ) was categorized into five zones from poor to excellent and validated using 41 observed wells. A significant quantity of wells was identified in the areas of high potential located to the west of the region, while five wells were situated within the moderate potential zone. Thereby, the GWPZ map identifying locations with viable groundwater resources suitable for habitation, development and economic plans in Sinai for decision makers.

Lithospheric magnetic structure of cratonic regions in Central-Eastern China inferred from aeromagnetic anomalies: Insights into magnetization in the uppermost mantle

Most of the subcontinental lithospheric mantle (SCLM) beneath Proterozoic cratons consists of refertilized Archaean SCLM. Variations in SCLM composition and its physical properties significantly affect the stabilization and preservation of the ancient continents. In this paper, aeromagnetic data are analyzed to reveal the magnetic structure of the lithospheric mantle beneath two major Precambrian blocks in central-eastern China, i.e., the Upper Yangtze Block (UYB) and Ordos Block (OB). After being reduced to the pole, the Fourier power spectrum of the aeromagnetic anomalies is calculated to determine the depth to magnetic sources. Considering the lower spatial resolution of the power spectral analysis in dealing with the long-wavelength aeromagnetic anomalies, we applied the scale-normalized continuous wavelet transform (CWT) on the magnetic data to trace the magnetic sources, with special focus on deeper ones. Synthetical model of a magnetic layer and application to the profile data validate the effectiveness of this scale normalization scheme in improving the wavenumber/spatial resolution in the CWT scalogram.In order to present a detailed magnetic structure, we carried out 2.5D forward modeling work on the magnetic data of a 2280 km-long nearly N-S profile across the UYB and OB. Due to the inherent ambiguity in the modeling results, the CWT-based spectral analysis is successfully adopted to provide source depth constraints for the initial model. The constrained forward modeling results indicate strong inhomogeneities among main tectonic blocks of studied area, like humans have different fingerprints. The magnetization of OB is larger than that of UYB since its Archean to Paleoproterozoic metamorphic basement are widely exposed at the surface, while the Precambrian basement of UYB is mostly overlain by unmetamorphosed Sinian cover and weakly metamorphosed Neoproterozoic strata. The most interesting aspect is that deep-seated magnetic sources might reside in the uppermost mantle of UYB and OB, suggesting vertical layering in the SCLM in cold cratonic regions.

A Dynamic Volumetric Heat Source Model for Laser Additive Manufacturing

Melt pool scale models of laser powder bed fusion (LPBF) offer insights into the process-structure-property relationships in additive manufacturing (AM). These models often neglect physical phenomena such as vapor cavity formation and fluid mechanics to reduce computational demands. Instead, volumetric heat source models are used to represent the effects that these phenomena have on the predicted melt pool dimensions. Generally, the dimensions and effective absorption of the volumetric heat source are calibrated to reproduce melt pool dimensions observed in metallographic cross sections taken from single-track experiments on bare plate. However, the transient nature of LPBF often deviates the melt pool dimensions from the assumed steady-state conditions of single-track experiments, motivating the need for a volumetric heat source model that more generally considers the dynamic relationship between melt pool shape and laser-material interactions. Here, we introduce a two-parameter volumetric heat source model that integrates several existing models into a generalized mathematical expression, providing independent control over the radial heat distribution via the parameter k and the volumetric shape of the heat source via the parameter m. This parameterization enables the calibration of melt pool shape predictions through simultaneous adjustment of these parameters, while keeping the radial heat source dimensions consistent with the experimental spot size (D4σ) and constraining the heat source depth and absorption to physically derived expressions for cavities. Consequently, the proposed volumetric heat source model adapts to changes in the local melt pool conditions due to scanning strategy and part geometry by dynamically adjusting the heat source depth and absorption. We demonstrate the capabilities of the proposed model through comparisons with a collection of experiments from the Additive Manufacturing Benchmark (AMBench).

Identification of Continental Mantle Earthquakes Using Regional Waves Propagating Into a Thinned Continental Crust

AbstractWe evaluate three identifiers of continental mantle earthquakes (CMEs) motivated by surface‐wave normal‐mode theory: the amplitude ratio of Sn to Lg, and the frequency content of Sn and of Lg, after wave propagation through continental crustal thinning. These flexible and easily applicable methods allow for potential new discoveries of CMEs. They rely on guided waves whose propagation is dependent on the uniformity of their waveguides. For a range of Moho models, we perform 2.5D axisymmetric simulations that reach the conventional distance and frequency ranges of observational studies; we compare results from four different source depths straddling the Moho. Our synthetics, and six south‐Tibet earthquakes recorded by an array in Bangladesh, show our Sn/Lg identifier is robust in the presence of crustal thinning, but the identifying frequency contents of Sn and Lg are easily obscured. These results strengthen the utility of Sn/Lg methods for global studies of CMEs.

Theoretical investigation of the excitation of leaky modes for multilayered models

SUMMARY The dispersion analysis with array-based methods enables us to detect and analyse the multimode dispersive waves with weak amplitudes. Over the past years, there has been widespread extraction of higher normal modes from earthquake records and ambient noise, which have been extensively employed in near-surface and crustal investigations. Notably, the frequent reporting of leaky modes in recent observations has gained significant attention. This is because leaky modes can provide more constraints on subsurface structures. Particularly, a subset of leaky modes is found to be sensitive to P-wave velocities, which has the potential to compensate for the limitations of traditional surface wave inversion. Nevertheless, due to the lack of knowledge of the excitation and practical application of leaky modes, it is urgent to have an effective guide in selecting certain leaky modes for practical inversion combined with other imaging methods. To this end, the theoretical investigation into the excitation of leaky modes for multilayered models is undertaken. By computing theoretical seismograms for various source mechanisms and source depths with the discrete wavenumber and the normal-mode summation methods, respectively, the qualitative evaluation of the leaky-mode contributions to the synthesized seismograms is conducted. Additionally, the impact of the source depth for the same source mechanism is meticulously examined by the dispersion spectra. Furthermore, with the accurate computation of leaky modes, we categorize the leaky modes into PL and OP (organ-pipe) modes according to their distinctive properties, that is, their attenuation and eigen-displacements, which may be used to explain very well the occurrence of certain leaky modes on the dispersion spectrum and be indicative of the reasonable choice of PL modes to put them into practical inversion for P-velocity structures.

Performance study of GaN-based betavoltaic nuclear batteries with 3D interfaces

This study presents a design of a 3D interface simulation model featuring an inverted pyramid structure. Our objective is to forecast the performance of GaN-based betavoltaic nuclear batteries with the PN junction 3D interface structures comparing a practical machining process. Initially, we computed the electron-hole pairs (EHPs) generation rate in GaN materials irradiated by both 63Ni and 147Pm sources using Geant4. Furthermore, we employed COMSOL Multiphysics, a finite element analysis software, to simulate the EHPs transport phenomena within the battery and investigate the influence of structural parameters on the output performance. Despite maintaining thicknesses of the P- and N-regions and consistent doping concentrations (Hp-GaN, Hn-GaN, Na, and Nd) as constants, the simulation results revealed notable disparities in the short-circuit current density (Jsc), open-circuit voltage (Voc), and maximum output power density (Pmax) among batteries irradiated with various radioactive sources. Subsequently, we investigated the output performance of the nuclear battery by altering parameters such as the number of inverted pyramid structures, junction depth, and type of radioactive source. Our investigation revealed that selecting 63Ni as the radioactive source, with Na at 1017 cm−3, Nd at 1014 cm−3, a junction depth of 0.1 μm, and inverted pyramid structures of 25, resulted in the following battery performance parameters: a short-circuit current density (Jsc) of 0.648 μA/cm2, an open-circuit voltage (Voc) of 2.3481 V, and a maximum output power density (Pmax) of 1.2949 μW/cm2. Substituting the radioactive source with 147Pm, the average short-circuit current density, Jsc, increased to 56.865 μA/cm2, and the maximum output power density, Pmax, increased to 94.975 μW/cm2, It's a significant enhancement in output performance.

Study on Depth Estimation and Characteristic Analysis of Underwater Source Based on Deep-Sea Broadband Signal Modeling

Studies on estimating the underwater sound source localization using acoustic signal characteristics have mainly been conducted in shallow waters. Recently, technologies for stably and efficiently estimating the underwater sound sources localization using the underwater sound propagation characteristics of the Reliable Acoustic Path(RAP) in deep water areas are being studied. Underwater surveillance technology in deep sea areas is known to have the advantage of having low detection performance variability due to time-varying underwater environments and having a small shadow zone, making it easy to stably detect underwater sound sources and estimate location even from relatively long distance. In this study, we analyzed the sound propagation characteristics based on the actual marine environment in the deep sea of the Korean Peninsula and conducted a study to analyze the estimation performance of sound source depth using the broadband interference pattern of direct wave and sea surface reflected waves radiating from underwater sound sources.

Volcanic tremor associated with successive gas emission activity at a boiling pool: Analyses of seismic array and visible image data recorded at Iwo-Yama in Kirishima Volcanic complex, Japan

Volcanic tremors are often observed during volcanic activity and volcanic eruptions, and their generation processes provide clues for understanding volcanic fluid activity underground and eruption dynamics. However, tremors are characterized by continuous oscillations that mask P- and S-waves; hence few studies have precisely located the source, which is the most fundamental information for understanding the generation mechanism. In this study, we focus on volcanic tremors excited by continuous gas emissions occurring at a vent called Y2a in Iwo-Yama, the Kirishima Volcanic Complex, Japan, to clarify the source process of the tremor as well as gas emission activity. We simultaneously observed the volcanic tremor by deploying a small aperture array consisting of six seismometers and the gas emission activity by using a newly developed visual IoT system that can be operated without commercial electricity. MUSIC analysis locates the tremor at depths ranging from the ground surface to approximately 200 m beneath the Y2a and Y2b vents, which are approximately 30 m apart, for approximately four months from November 2021 to February 2022. The source locations of the tremors in the 2 Hz (1.2–2.6 Hz), 4 Hz (3–4 Hz), and 5 Hz (4–5.5 Hz) ranges show some differences and changes with time. The source location tends to become deeper when the 2 Hz amplitude is large. The infrasound generated by gas emission activity is dominant in the tremor signals, which are recognized in the wave propagation velocity with an acoustic velocity of 330 m/s when the 2 Hz amplitude is small. The visual IoT system succeeded in detecting long-term changes in the gas emission activity, and we found that the 2 Hz amplitude of tremor was well correlated with the amount of hot water in the boiling pool of Y2a, which was controlled by precipitation and evaporation during non-rainy days. From these observations, we infer that the volcanic tremor is generated by resonance of volcanic gas and hot water in a crack-like structure beneath Y2a. The resonance was triggered by the counterforces of the gas emissions in the boiling pool, and the infrasound was dominant during periods of hot water depletion in the boiling pool. Temporal changes in the source depths may be caused by changes in the fluid properties, configuration of the resonator and/or the strengths of the underground sources and infrasound. Our simultaneous observations of seismic array and visual IoT system clarify that even the continuous gas emission activity that looks stable is controlled by external sources such as precipitation.

LoVoCCS. II. Weak Lensing Mass Distributions, Red-sequence Galaxy Distributions, and Their Alignment with the Brightest Cluster Galaxy in 58 Nearby X-Ray-luminous Galaxy Clusters

The Local Volume Complete Cluster Survey is an ongoing program to observe nearly a hundred low-redshift X-ray-luminous galaxy clusters (redshifts 0.03 < z < 0.12 and X-ray luminosities in the 0.1–2.4 keV band L X500c > 1044 erg s−1) with the Dark Energy Camera, capturing data in the u, g, r, i, z bands with a 5σ point source depth of approximately 25th–26th AB magnitudes. Here, we map the aperture masses in 58 galaxy cluster fields using weak gravitational lensing. These clusters span a variety of dynamical states, from nearly relaxed to merging systems, and approximately half of them have not been subject to detailed weak lensing analysis before. In each cluster field, we analyze the alignment between the 2D mass distribution described by the aperture mass map, the 2D red-sequence (RS) galaxy distribution, and the brightest cluster galaxy (BCG). We find that the orientations of the BCG and the RS distribution are strongly aligned throughout the interiors of the clusters: the median misalignment angle is 19° within 2 Mpc. We also observe the alignment between the orientations of the RS distribution and the overall cluster mass distribution (by a median difference of 32° within 1 Mpc), although this is constrained by galaxy shape noise and the limitations of our cluster sample size. These types of alignment suggest long-term dynamical evolution within the clusters over cosmic timescales.

New insights into the geological evolution history of Mare Fecunditatis

The Luna 16 probe returned 101 g of lunar regolith from the northeast of the Mare Fecunditatis in 1970. Studies on these samples were primarily conducted in the 1970s and 1980s, and limited scientific achievements were obtained due to available technology at that time. China received 1.5 g Luna 16 samples in 2023 and it is expected to conduct in-depth research in the near future. We conducted a thorough investigation on several fundamental issues in this region to provide a refined geological background in the paper. Firstly, a detailed division of the basaltic units within the Mare Fecunditatis was conducted based on the TiO2 content, and impact craters in each geological unit were mapped with the high-resolution Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images. With the method of lunar surface dating from the crater size-frequency distribution, we found that the model ages of these basalt units range from 3.71 Ga to 3.31 Ga. Next, the thickness of the basalt within the Mare Fecunditatis is estimated with different types of craters, and local basalt thickness ranges from 3 m to 304 m from seven rim-completely-exposed craters in the mare. The rim-completely-exposed craters on the mare-highland boundary, the rim-partially-exposed craters in the mare, and rim-completely-buried craters in the maria also provide information on the thickness of local basalt. Finally, numerical simulations of the formation process of the largest young impact crater in this region, Langrenus crater, was conducted. The simulations show that the Langrenus crater could be formed by a 11.2-km-diameter asteroid hitting the lunar surface with a speed of ~10 km/s. The average thickness of the ejecta from the Langrenus crater is ~4.9 m near Luna 16 landing site, indicating that a significant fraction of Luna 16 samples might be the ejecta from the Langrenus crater. The simulations also reveal that the maximum shock pressure on the materials ejected to Luna 16 landing site can reach 92 GPa, and their maximum source depth is approximately 7.1 km. These interpretations can provide valuable information for further study of the Luna 16 samples and inferring the geological history of the Mare Fecunditatis.

Successive Tsunamigenic Events Near Sofu Seamount Inferred From High‐Frequency Teleseismic P and Regional T Waves

AbstractAn unexpected major tsunami from the region near Sofu Seamount was observed on 8 October 2023. Sofu Seamount is located approximately 600 km from the coast of Japan. Due to far epicentral distances and the successive occurrence of seismic events, the conventional seismic analysis to reveal the accompanying seismic sequence cannot work well. We investigated high‐frequency teleseismic P and regional T waves from the accompanying seismic sequence during the tsunamigenic events near Sofu Seamount. Envelope shapes of teleseismic P and regional T waves were similar, indicating that T‐wave envelopes also reflected source properties of seismic sequence. During seismic events near Sofu Seamount, observed regional envelopes were characterized by weak body waves and large amplitude T waves with durations of 39–68 s. According to numerical simulations of seismic wave propagation using a realistic topography model, characteristics of T waves exhibit weak slope‐angle and strong source‐depth dependencies. Strong T waves with durations less than 60 s only appeared in results with sources at depths ≤0.5 km below the seafloor. We concluded that high‐frequency radiation of the accompanying seismic sequence during the tsunamigenic events near Sofu Seamount possibly occurred at shallower depths just below the seafloor. If seismic and tsunami sources coincide, shallower source depths might cause tsunamigenic uplifts. The observed peak seafloor uplifts and T‐wave amplitudes during tsunamigenic events were scaled. This result suggests the possibility of tsunami forecasting based on T‐wave amplitudes from submarine volcanoes.

Causal sources of the significant high-amplitude magnetic anomaly zone in the northern south China Sea continental margin

The magnetic anomaly map shows an obvious NE-SW trending high-amplitude magnetic anomaly zone (NSCSMA) in the northern South China Sea (SCS) continental margin that extends from southwest Taiwan to the area at approximately 114°E and 20°N. The origin of this high-amplitude magnetic anomaly zone is important for understanding the magmatism, margin rifting, and tectonic evolution of the SCS. To gain insight into this issue, in this study, wavelet spectrum analysis, 2D magnetic modeling, and compact inversion were used to identify the causal source of the NSCSMA. Combining wavelet spectrum analysis with magnetic modeling results, we find that the depths of the major magnetic sources are not consistent along the strike of the NSCSMA (∼15 km in the east and ∼25 km in the west). The compact inversion results along five profiles across the NSCSMA also revealed two kinds of geometries (quasi-dike in the east and dome-like in the west) of the causal sources of the NSCSMA with different depths. Based on our findings and previous paleo-subduction model, we propose that the major source of the NSCSMA is serpentinized upper mantle materials associated with paleo-Pacific plate subduction.

Predicting the Number of Radio Sources seen by both VLASS and LSST

Radio surveys typically sample extragalactic sources in higher redshift regimes than is typical for optical surveys, resulting in many radio sources not having a detected optical counterpart. Over the next decade the Legacy Survey of Space and Time (LSST) will be performing the deepest (i < 26.4 mag) wide-area optical survey to date increasing the fraction of radio sources for which we have optical data. In this Research Note we use the Hyper Suprime-Cam survey to analyze how the fraction of radio sources in the Very Large Array Sky Survey (VLASS) with optical detections varies as a function of i-band magnitude and extrapolate to predict the number of optical counterparts we expect LSST to detect. Assuming a final VLASS point source depth of S 3 GHz ≲ 350 μJy, we expect LSST to identify optical counterparts to ∼106 radio sources in VLASS.

Evaluation of gold mineralisation potential using AHP systems and weighted overlay analysis

The demand for sustainable development goals and the absence of systematic development and organised exploration for gold has prompted this study to integrate magnetic and radiometric datasets with lithology to evaluate the gold mineralisation potential in the Ilesha schist belt. This study considers 3168.72 km2 of the Ilesha schist belt in southwestern Nigeria, a frontier belt for gold deposits. The high-resolution airborne magnetic and radiometric datasets were processed using enhancement techniques, including the analytical signal, lineament density, and K/Th ratio. CET grid analysis, Euler deconvolution, and analytical signal depth estimation methods were used to aid the interpretation. The spatial integration and interpolation were performed using the Analytical Hierarchy Process (AHP) and weighted overlay analytical tools within the ArcGIS environment. The dominant structural controls for potential mineralisation are ENE–WSW and ESE–WNW trends. The depth of the magnetic sources revealed by the analytical signal ranged from 63.17 to 629.47 m, while depths ranging from 47.32 to 457.22 m were obtained from Euler deconvolution. The delineated highly magnetic edge sources, dense lineaments, radiometrically highlighted alteration zones, and lithological hosts for gold mineralisation were integrated to establish the gold mineralisation potential map. The AHP deductions reveal that 10.52% of the study site is within the high mineralisation potential class, a remarkable 60.39% falls within the moderate class, a significant portion (28.86%) falls within the poor class, and 0.23% is considered unfavourable. The result was optimised by validation using known mines, with 94% (i.e., 15 out of 16 mining sites) plotting within the high mineralisation potential class. This assessment provides invaluable insight for stakeholders and policymakers to embark on gold exploration and exploitation and promote sustainable mineral development.

Effects of phosphorus fertilizer type and dripline depth on root and soil nutrient distribution, nutrient uptake, and maize yield under subsurface drip fertigation

ContextSubsurface drip irrigation can potentially increase nutrient uptake by altering the spatial distribution of nutrients and roots, but the efficiency enhancement potential of different phosphorus (P) sources combined with varying dripline depths still requires further evaluation. MethodsWe established a 2-year field experiment with spring maize in 2021 and 2022 to determine the regulatory effects of three P sources [P1, monoammonium phosphate (MAP); P2, ammonium polyphosphate (APP); and P0, no P] and three dripline depths (D0, surface drip irrigation, 0 cm; D15, subsurface at 15 cm depth; and D30, subsurface at 30 cm depth) on the soil NO3-N, NH4-N and Olsen-P distribution, root distribution, nitrogen (N) fertilizer partial factor productivity (PFPN) and P use efficiency (PUE), and grain yield. ResultsWe found a significant coupling effect between the P source and dripline depth, both of which significantly impacted soil nutrients and root distribution, grain yield, PFPN, and PUE. In P1D15 and P2D15, the highest soil NO3-N and Olsen-P contents were observed at soil depths of 0–30 and 10–20 cm and at 0–30 and 10–30 cm, respectively. Similarly, in P1D30 and P2D30, which were 20–40 and 20–40 cm, and 20–40 and 30–60 cm, respectively. Compared to the other treatments, P2D15 and P1D30 exhibited considerable increases in root length density at the 30–60 cm soil depth of 37∼52 % and 28∼58 %, respectively. Regardless of the dripline depth, P0 resulted in the lowest yield during both growing seasons. P1D30 and P2D15 were found to be the optimal combinations for achieving higher grain yield, PFPN, and PUE, as they were able to achieve a high degree of coordination between soil available N and Olsen-P, as well as root distribution. ConclusionsThe recommended approach for optimizing nutrient and root spatial distributions under subsurface drip irrigation systems involves the use of poly-P fertilizer (APP) in conjunction with shallow dripline depth and ortho-P fertilizer (MAP) paired with deep dripline depth, which provides valuable guidance for co-fertigation practices involving N and P fertilizers.

The Impact of Special Marine Environments Such as the Kuroshio on Hydroacoustic Detection Equipment

In order to study the impact of acoustic propagation characteristics in the northeastern South China Sea, GEBCO08 global terrain grid data and Argo data were used to numerically simulate the acoustic transmission characteristics of two stations in the northeast South China Sea affected by the Kuroshio. The impact of different marine environments on acoustic transmission characteristics was analyzed. The results show that increasing the deployment depth of a sound source within a certain range will reduce the transmission loss; deploying a sound source near the axis of the surface acoustic channel or the deep-sea acoustic channel will also greatly increase the propagation distance of sound signals; and the presence of topography such as undersea mountains will increase the transmission loss.

BO-GRNN: Machine Learning for Underwater Acoustic Source Localization

This article proposes a Bayesian optimization-based generalized regression neural network (BO-GRNN) framework for underwater source localization in shallow water environment. Specially, by leveraging kernel regression analysis, BO-GRNN fits a conditional probability density function using training and test samples to infer the source location of unseen test samples. Furthermore, BO-GRNN models the objective function as a Gaussian process (GP) based on observed samples, utilizing an acquisition function to sample around the best objective function values and high variance regions. By evaluating these samples and updating the GP iteratively, the optimal hyperparameters are identified, ultimately improving the training efficiency and localization performance of the GRNN. Simulation experiments and error analysis validate this framework’s effectiveness. Further validation using SWellEx-96 experimental data demonstrates the superior localization performance of this framework, even with limited data snapshots. This framework estimates the range and depth of underwater sources within a 10 km range, achieving mean absolute errors of less than 0.15 km for range and 0.2 m for depth. Compared to GRNN, this framework demonstrates a 5 times improvement in training efficiency. These advantages make BO-GRNN an efficient, accurate, and robust solution for underwater source localization.