Maximum Depth Research Articles

Analysis of microscopic deformation mechanism of SiCp/Al composites induced by ultrasonic vibration nanoindentation

Ultrasonic vibration machining technology affords environmentally friendly dry cutting without employing a cutting fluid and has been applied to the macro-scale dry cutting precision machining of SiCp/Al composites. However, the high-frequency vibration on the atomic-scale deformation mechanism of such materials remains unclear. Hence, this paper combines the molecular dynamics simulations (MD) with ultrasonic vibration indentation tests to investigate the effect of ultrasonic vibration on the multiscale deformation of SiCp/Al composites. The results demonstrate that the vibration amplitude exceeding the lattice constant (4.05 Å) of Al induces the plastic flow of Al atoms after breaking through the interatomic force. On the one hand, the ultrasonic high-frequency vibration energy accelerates the interfacial failure and the SiC particle fragmentation and promotes the dislocation movement to form the dislocation loop. On the other hand, compared with conventional indentation, ultrasonic vibration energy reduces the FCC phase transition rate by up to 40.8% and improves the toughness of the composites. Meanwhile, the high-frequency impact energy promotes the material to produce lattice distortion and subgranular grains, where grain slippage and lamination faults occur at the grain boundaries. Besides, the maximum depth of the material impact layer is about 1.45 times that of a conventional indentation, which contributes to the material being removed efficiently. The results of this research provide potential insights into ultrasonic vibration-assisted micro and nano removal processing of SiCp/Al composites, which could help to expand the efficient and precise clean processing of this type of material.

Anoxia begets anoxia: A positive feedback to the deoxygenation of temperate lakes.

Declining oxygen concentrations in the deep waters of lakes worldwide pose a pressing environmental and societal challenge. Existing theory suggests that low deep-water dissolved oxygen (DO) concentrations could trigger a positive feedback through which anoxia (i.e., very low DO) during a given summer begets increasingly severe occurrences of anoxia in following summers. Specifically, anoxic conditions can promote nutrient release from sediments, thereby stimulating phytoplankton growth, and subsequent phytoplankton decomposition can fuel heterotrophic respiration, resulting in increased spatial extent and duration of anoxia. However, while the individual relationships in this feedback are well established, to our knowledge, there has not been a systematic analysis within or across lakes that simultaneously demonstrates all of the mechanisms necessary to produce a positive feedback that reinforces anoxia. Here, we compiled data from 656 widespread temperate lakes and reservoirs to analyze the proposed anoxia begets anoxia feedback. Lakes in the dataset span a broad range of surface area (1-126,909 ha), maximum depth (6-370 m), and morphometry, with a median time-series duration of 30 years at each lake. Using linear mixed models, we found support for each of the positive feedback relationships between anoxia, phosphorus concentrations, chlorophyll a concentrations, and oxygen demand across the 656-lake dataset. Likewise, we found further support for these relationships by analyzing time-series data from individual lakes. Our results indicate that the strength of these feedback relationships may vary with lake-specific characteristics: For example, we found that surface phosphorus concentrations were more positively associated with chlorophyll a in high-phosphorus lakes, and oxygen demand had a stronger influence on the extent of anoxia in deep lakes. Taken together, these results support the existence of a positive feedback that could magnify the effects of climate change and other anthropogenic pressures driving the development of anoxia in lakes around the world.

Investigation of the possibility of shaping an electron dose field of a clinical accelerator with 3D printed polymer products

The improvement of existing dose delivery techniques is a constant goal in cancer radiation therapy, since it increases the treatment efficiency. For example, the use of so-called boluses and compensators offers ways to correct for surface irregularities or tissue inhomogeneities in some irradiated areas. While compensators are usually inserted along the radiation beam at a certain distance from the patient, boluses are located directly on the surface of the patient's body and follow its contours. Depending on their thickness and shape, these beam modifiers enable a shift of the depth of the dose maximum and control the depth-dose distribution. However, an accurate production of beam modifiers often requires complex procedures, thus limiting their use in the clinic. This study suggests the fused filament fabrication technique to produce polymer-based beam modifiers for shaping the dose of clinical electron beams. The feasibility of this approach was studied through a series of experiments and simulations using the Monte Carlo method. The results show that therapeutic electron beams with energies of 6–12 MeV can be effectively modified using such polymer samples. The numerical model can also be used to evaluate the dose distribution of electron beams shaped by plastic absorbers prior to production, thereby making it possible to select the compensator geometry for specific purposes.

Evaluation of the Depth and Width of Cuts after Controlled-Depth Abrasive Water Jet Machining Using Low Pressure.

The presented paper is focused on the evaluation of material removal during machining via an abrasive water jet with a controlled depth of cut. In the introductory parts of the work, a theoretical analysis of water jet technology and an analysis of the current state of the problem are presented. The experimental part of the work is devoted to testing the effects of technological parameters on material removal from the point of view of the maximum erosion depth and volume loss of material during machining with a low water pressure of 50 MPa. The tested material was a Ti 6Al 4V titanium alloy. The experiments were carried out by changing the traverse speed of the cutting head, the mass flow of the abrasive and the angle of inclination of the cutting head, according to the DoE 33 experiment plan. The obtained values were evaluated using the method of variance (ANOVA) and regression analysis. Furthermore, the values of the width of the erosion track and the maximum and minimum erosion effects for both tested materials were evaluated.

Effect of organic amendments on soil structure, microbial community and water transport in the Qinghai Lake watershed, North-Eastern Qinghai–Tibet Plateau

ABSTRACT The effect of organic amendments on soil structure, microbial community and water transport in alpine ecosystems remains uncertain. Six fertilization regimes from a 2-year field experiment were selected to study this mechanism, i.e. plant litter (PL), organic fertilizer (OF), low concentration of glucose (LCG), medium concentration of glucose (MCG), high concentration of glucose (HCG) and the control (CT). Our results indicated that the soil macroporosity, branch density, length density and node density of soil macropores treated with OF, PL, HCG, MCG and LCG were larger than those of soils treated with CT. The phospholipid fatty acids (PLFAs), bacteria, fungi, actinomycetes, gram-positive bacteria (G+) and gram-negative bacteria (G−) of soils treated with OF, PL, HCG and MCG were larger than those of soils treated with LCG and CT. In contrast, the dyed area ratio and the maximum wetting depth of soils treated with OF, PL, LCG, HCG and MCG were smaller than those treated with CT. There were significant positive correlations between soil organic matter (SOM) and connectivity of soil macropores. Therefore, SOM accumulation significantly improved the soil pore structure, induced the development of the soil microbial community, increased the soil water retention ability and decreased the generation of preferential flow.

Experimental study on solar heating system based on heat pipe technology for mitigating subgrade frost heave

Subgrade frost heave is the main reason that affects the safe operation and comfort of trains during the cold season. Solar heating system based on heat pipe technology is a promising method to mitigate the frost heave by raising the subgrade temperature. In this paper, a field experiment was conducted to evaluate the heating performance of the solar heating system based on heat pipe technology in the cold season. In addition, the heat collection performance and stability of the system are compared with other solar heating systems. Finally, its applicability is discussed. Experimental results revealed that the solar heating system based on heat pipe technology can effectively raising the soil temperature and mitigate the frost heave of subgrade. During the experiment period, the soil temperature at the depth of −0.5 m in the experiment site was 5 °C higher than that of the comparison site, and the maximum freezing depth was 0.4 m, which was 56 % lower than that of the comparison site. The mean daily temperature of heat collection units (HCUs)fluctuated around 30 °C, and the mean daily temperature of the two-phase closed thermosyphons (TPCTs) fluctuated between 15 °C and 30 °C. The heat transfer efficiency of System 1 and System 2 is greater than 0.5, and the total effective heat transfer during the experiment period is 512 MJ and 283 MJ, respectively, and the heat transfer difference is about 2 times. Compared with other solar heating systems, the system proposed in this paper has good heat collection performance and more superior system stability. The mean daily heat transfer of System 1 and System 2 is 6.4 MJ and 3.71 MJ, respectively, which is 62.9 % higher and 5.6 % lower than the mean daily heat loss of subgrade of 3.93 MJ, respectively. The system has the application prospect of low maintenance cost and good long-term anti-frost heave effect.

Rainfall-Runoff Response of A Suburban Area

Batu Pahat experiences flash floods whenever intense rainfall coincides with high tide. Among the factors which cause flash floods are due to Batu Pahat river catchment's flat and low-lying geographical features as well as high-intensity rainfall. The goals of the study are to analyse the frequency of rainfall events for SMK Munshi Sulaiman station and to investigate runoff due to severe rainfall events within the study area. The observed daily rainfall depth record between 2010 and 2021 was obtained from the Department of Irrigation and Drainage (DID) Malaysia. The frequency of rainfall events within the 11-year period is examined using empirical rainfall intensity formulation. Rainfall-runoff of the five most heavy rainfall events in 2021 within the study area are simulated using HEC-HMS. It has been found that most daily rainfall events have a frequency of a 1-year return period. Only three events were found to have a return period of up to 2-year ARI, with a maximum rainfall depth of 110.67 mm. Five heaviest rainfall events in 2021 were obtained from DID's real-time online platform for rainfall-runoff simulations. One of the events, which occurred in June 2021 has a frequency larger than a 100-year return period while other events have return periods ranging from 1-year to 5-year. Simulations produced by HEC-HMS for these events in January, April, May, June, and September 2021 have resulted in peak flow of 6.7 m3/s, 26.8 m3/s, 24.7 m3/s, 39.9 m3/s, and 39.9 m3/s, respectively. Based on frequency analysis, rainfall-runoff simulations, and field observations, it can be concluded that flash floods are highly possible due to high-intensity rainfall as well as lowland topographical features of the study area. Therefore, flood mitigation measures need to be carried out to improve the drainage system for the suburban area.

Flood Estimation and Control in a Micro-Watershed Using GIS-Based Integrated Approach

Flood analyses when using a GIS-based integrated approach have been successfully applied around the world in large-sized watersheds. This study employed hydrological-hydraulic modeling to analyze flash floods by integrating HEC-HMS, HEC-RAS, and ArcGIS software for flood evaluation and control in a micro-watershed in the Samaru River, Nigeria. The watershed boundaries, its characteristics (soil and land use), the topographical survey, and the intensity duration frequency curve (IDF) of the study area were produced using data-driven techniques. The HEC-HMS model was used to derive the peak discharges for 2-, 5-, 10-, 25-, 50-, 100-, and 200-year return periods with the frequency storm method. Afterward, the water surface profiles for the respective return periods were estimated using the HEC-RAS hydrodynamic model. The simulated design flood for the 2-, 5-, 10-, 25-, 50-, 100-, and 200-year return periods at the reference location (the NUGA gate culvert) were 3.5, 6.8, 9.1, 12.1, 14.3, 16.6, and 19.0 m3/s, respectively, while those at the watershed outlet for the respective return periods were 7.5, 14.9, 20.3, 27.3, 32.6, 38.0, and 43.5 m3/s, respectively (with a water height of 0.9 m, 1.1 m, 1.3 m, 1.33 m, 1.38 m, 1.5 3m, and 1.8 m, respectively), at the NUGA gate culvert cross-section. The maximum water depths of about 0.9 m and 1.0 m were recorded in the right and left overbanks, which were similar to the simulated water depth for the 2- and 5-year return periods. Hence, for the smart control of floods passing through the river and major hydraulic structures, a minimum design height of 1.50 m is recommended. For the most economic trapezoidal channel section, a normal depth of 1.50 m, a bottom width of 1.73 m, a top width of 3.50 m, and a free board of 0.30 m is proposed to curb the overtopping of floods along the channel sub-sections. The findings of this study could help hydraulic engineers minimize flooding in streams and rivers overbanks in a micro-watershed.

Design of a submarine main ballast blowing systems

A submarine ballast system represents a combination of dedicated equipment and piping in which the main circulating fluid is either sea water straight from the submarine exterior or air which is compressed at high pressures and then it is stored in pressure vessels onboard. These fluids are, then, introduced in or extracted from various tanks located strategically onboard the submerged vehicle. Because water cannot be compressed and because of it’s density, it will require large amounts of energy and pumps to be able to move all the water within the system in a short period of time that is required for surfacing a submerged vehicle. Therefore, compressed air is favoured for the main deballasting because of the air’s capability of being stored at high pressures and displacing water in a fast manner once it is fed into the ballast tanks, thanks to it’s ability to expand as the submarine emerges and the surrounding water pressure drops. In addition, the compressed air systems must operate for at least a normal surfacing from periscopie depth, but also for surfacing from the maximum depth in the case of an emergency. From an engineering standpoint, ballast tank blowing systems are complex, but nevertheless are vital, for allowing the maneuvering of the submarine and it’s bouyancy within the water it navigates, regardless if it’s in a surfaced or submerged condition and must be done in the smoothest and with as little noise as possible. The requirements of designing and calculation of such systems are covered by the Class and Administration rules and regulations.

Use of visual and echo sounding surveys: case study of submerged aquatic vegetation of lake Kenon (Eastern Transbaikalia)

The paper presents the results of studying of the aquatic vegetation of Lake Kenon based on the integrated use of traditional methods of visual survey with an echo sounding. The use of echo sounding surveys makes it possible to study better the features of the distribution of submerged aquatic plants. It allows you to speed up the process of sampling in the field, and also facilitates office processing of the received data. Based on the measurement results, a bathymetric map was built, and the boundaries and areas of dominant phytocenoses were determined. It was revealed that at present the total area of thickets is 489 hectares, which is 33 % of the lake area. The maximum depth of plant growth was 5.1 m. The data obtained is higher than the percentage of overgrowth in 1993, but lower than the values for the 70s and 80s. At present, as in previous years, Chara algae are leading in terms of overgrowing area. The decrease in the distribution area of Nitella flexilis and Potamogeton crispus was revealed.

The endpoint of partial deconfinement

We study the matrix quantum mechanics of two free hermitian N × N matrices subject to a singlet constraint in the microcanonical ensemble. This is the simplest example of a theory that at large N has a confinement/deconfinement transition. In the microcanonical ensemble, it also exhibits partial deconfinement with a Hagedorn density of states. We argue that the entropy of these configurations, based on a combinatorial counting of Young diagrams, are dominated by Young diagrams that have the VKLS shape. When the shape gets to the maximal depth allowed for a Young diagram of SU(N), namely N, we argue that the system stops exhibiting the Hagedorn behavior. The number of boxes (energy) at the transition is N2/4, independent of the charge of the state.

Efficient Automatic Subdifferentiation for Programs with Linear Branches

Computing an element of the Clarke subdifferential of a function represented by a program is an important problem in modern non-smooth optimization. Existing algorithms either are computationally inefficient in the sense that the computational cost depends on the input dimension or can only cover simple programs such as polynomial functions with branches. In this work, we show that a generalization of the latter algorithm can efficiently compute an element of the Clarke subdifferential for programs consisting of analytic functions and linear branches, which can represent various non-smooth functions such as max, absolute values, and piecewise analytic functions with linear boundaries, as well as any program consisting of these functions such as neural networks with non-smooth activation functions. Our algorithm first finds a sequence of branches used for computing the function value at a random perturbation of the input; then, it returns an element of the Clarke subdifferential by running the backward pass of the reverse-mode automatic differentiation following those branches. The computational cost of our algorithm is at most that of the function evaluation multiplied by some constant independent of the input dimension n, if a program consists of piecewise analytic functions defined by linear branches, whose arities and maximum depths of branches are independent of n.

Three-dimensional inter-basin groundwater flow toward a groundwater-fed stream: Identification, partition, and quantification

Inter-basin groundwater flow (IGF), defined as groundwater flows across the topographic divides, occurs in nature as a common phenomenon, and seriously affect water balance and solute transport in a basin. Although the existence of IGF has been checked in drainage basins with indirect methods, such as using information of hydrogeochemistry, few studies are conducted to directly identify and quantify the IGF in the three-dimensional (3D) space using numerical modeling of groundwater flow. In this study, we identify, partition and quantify IGF based on a regional-scale 3D groundwater flow model covering several traditional surface water basins. The investigation is focused on the Hailiutu River, a groundwater-fed stream in the Ordos Plateau, China. It is the first time that the source zones and 3D paths of IGF as well as its contribution to the streamflow are fully captured for a groundwater-fed stream. Results indicate that the IGF contributes 36%∼59% to the baseflow and 32%∼52% to the streamflow of the Hailiutu River, through different groups of circulation paths with the maximum depth up to ∼ 1000 m. Uncertainty analyses of the model show that the contribution of IGF to the streamflow is positively correlated to the infiltration recharge and hydraulic conductivities of the aquifer media. Several indirect methods are also checked for comparison, but they could only be used to assess the potential contribution of IGF, not the IGF paths. This study will facilitate in deeply understanding the evolution mechanism of the inter-basin groundwater circulation and the interaction between surface water and groundwater.

Unraveling the formation dynamics of metallic femtosecond laser induced periodic surface structures

Femtosecond laser surface processing (FLSP) is an emerging fabrication technique to efficiently control the surface morphology of many types of materials including metals. However, the theoretical understanding of the FLSP formation dynamics is not a trivial task, since it involves the interaction of various physical processes (electromagnetic, thermal, fluid dynamics) and remains relatively unexplored. In this work, we tackle this problem and present rigorous theoretical results relevant to low-fluence FLSP that accurately match the outcomes of an experimental campaign focused on the formation dynamics of laser induced periodic surface structures (LIPSS) on stainless steel. More specifically, the topography and maximum depth of LIPSS trenches are theoretically and experimentally investigated as a function of the number of laser pulses. Moreover, precise LIPSS morphology measurements are performed using atomic force microscopy (AFM). The proposed comprehensive simulation study is based on two-temperature model (TTM) non-equilibrium thermal simulations coupled with fluid dynamic computations to capture the melting metal phase occurring during FLSP. Our rigorous simulation results are found to be in excellent agreement with the AFM measurements. The presented theoretical framework to model FLSP under low-fluence femtosecond laser pulses will be beneficial to various emerging applications of LIPSS on metallic surfaces, such as cooling high-powered laser diodes and controlling the thermal emission or absorption of metals.

Satellite and High-Spatio-Temporal Resolution Data Collected by Southern Elephant Seals Allow an Unprecedented 3D View of the Argentine Continental Shelf

High spatial and temporal resolution hydrographic data collected by Southern Elephant Seals (Mirounga leonina, SESs) and satellite remote sensing data allow a detailed oceanographic description of the Argentine Continental Shelf (ACS). In-situ data were obtained from the CTD (Conductivity, Temperature, and Depth), accelerometer, and hydrophone sensors attached to five SESs that crossed the ACS between the 17th and 31st of October 2019. The analysis of the temperature (T) and salinity (S) along the trajectories allowed us to identify two different regions: north and south of 42°S. Satellite Sea Surface Temperature (SST) data suggests that north of 42°S, warm waters are coming from the San Matias Gulf (SMG). The high spatio-temporal resolution of the in-situ data shows regions with intense gradients along the T and S sections that were associated with a seasonal front that develops north of Península Valdés in winter due to the entrance of cold and fresh water to the SMG. The speed of the SESs is correlated with tidal currents in the coastal portion of the northern region, which is in good agreement with the macrotidal regime observed. A large number of Prey Catch Attempts (PCA), a measure obtained from the accelerometer sensor, indicates that SESs also feed in this region, contradicting suggestions from previous works. The analysis of wind intensity estimated from acoustic sensors allowed us to rule out the local wind as the cause of fast thermocline breakups observed along the SESs trajectories. Finally, we show that the maximum depth reached by the elephant seals can be used to detect errors in the bathymetry charts.

Analysis of lateral dynamic response characteristics of drilling riser during installation of deep-water Christmas tree

In this research, in order to investigate the safety risk of drilling riser during deep-water Christmas tree lowering process and determine the basic parameters for the safety calculation of the upper part of the Christmas tree, wave-current force calculation method is explained based on modified Morison equation. According to differential element method, the dynamic equations of vertical and horizontal bending of riser under wave and current conditions are derived and equation solution method and calculation stability conditions are analyzed. By combining the upper and lower boundaries of riser during Christmas tree connection and environmental load factors, dynamic responses of riser under different wave, top tension, platform drift, operating water depth and other parameters are investigated. The obtained results show that maximum lateral displacement, corresponding water depth and bending moment of riser as well as the amplitude and period of displacement fluctuation at riser bottom are increased with the increase of wave velocity and water depth. It is also found that increase of top tension reduced the maximum lateral displacement of riser and increased corresponding water depth, but excessive tension increased the fluctuations of displacement and bending moment at riser bottom. Increase of platform drift increased maximum lateral displacement fluctuation range, bottom string displacement and bending moment of the riser and decreased corresponding maximum displacement water depth. Drift is found to increase the fluctuations of dynamic parameters at riser bottom. Increase of operating water depth increased riser maximum lateral displacement and decreased the period and amplitude of bottom bending moment fluctuations; also, maximum water depth position approached to "1/3" position on sea surface.

Marine Geophysical Survey of a Medieval Shipwreck in Shallow Waters Using an Autonomous Surface Vehicle: A Case Study from Avaldsnes, Norway

This study demonstrates the successful use of a single-channel chirp system mounted on an Autonomous Surface Vehicle (ASV) for detecting and mapping a partly buried medieval ship found in water approximately one meter (m) deep in a dynamic, intertidal environment at Avaldsnes, south-western Norway. The ASV's fast mobilization and access to areas otherwise difficult to reach, makes it an efficient, low-cost, and non-invasive platform for examining the seafloor and subsurface with high-resolution seismic data, acquired in a dense grid. Line spacing of 0.25 m allowed for the generation of a detailed 3D data cube, enabling effective interpretation of both acoustic vertical sections and horizontal amplitude maps. This approach empowered accurate identification of the outline of the wooden hull and provided information about ship dimensions and maximum burial depth. Structural elements observed in the geophysical datasets, including the keelson, raiders, and maststep, corroborates with findings from previous diving investigations and photogrammetry documentation. Moreover, the geophysical survey offers valuable additional knowledge of the buried ship remains, revealing a slight tilt of the keel and a substantial object buried in close proximity to the stern, probably the rudder or another wreck-related artefact.

Decision rules for personalized statin treatment prescriptions over multi-objectives.

In our previous study, we demonstrated the feasibility of producing a proactive statin prescription strategy - a personalized statin treatment plan (PSTP) - using neural networks with big data. However, its non-transparency limited result interpretations and clinical usability. To improve the transparency of our previous approach with minimal compromise to the maximal statin treatment benefit-to-risk ratio, this study proposed a five-step pipeline approach called the decision rules for statin treatment (DRST). Steps 1-3 of our proposed pipeline improved our previous PSTP model in optimizing individual benefit-to-risk ratio; Step 4 used a decision tree model (DRST) to provide straightforward rules in the initial statin treatment plan; Step 5 aimed to evaluate the efficacy of these decision rules by conducting a clinical trial simulation. We included 107,739 de-identified patient data from Optum Labs Database Warehouse in this study. The final decision rules were compact and efficient, resulting from a decision tree with only a maximum depth of 3 and 11 nodes. The DRST identified three factors that are easily obtainable at the point of care: age, low-density lipoprotein cholesterol (LDL-C) level, and age-adjusted Charlson score. Moreover, it also identified six subpopulations that can benefit most from these decision rules. In our clinical trial simulations, DRST was found to improve statin benefit in LDL-C reduction by 4.15 percentage points (pp) and reduce risks of statin-associated symptoms (SAS) and statin discontinuation by 11.71 and 3.96 pp, respectively, when compared to the standard of care. Moreover, these DRST results were only less than 0.6 pp suboptimal to PSTP, demonstrating that building DRST that provide transparency with minimal compromise to the maximal benefit-to-risk ratio of statin treatments is feasible.

Variations and Depth of Formation of Submesoscale Eddy Structures in Satellite Ocean Color Data in the Southwestern Region of the Peter the Great Bay

The aim of this study was to develop methods for determining the most significant contrasts in satellite ocean color data arising in the presence of a submesoscale eddy structure, as well as to determine the corresponding depths of the upper layer of the sea where these contrasts are formed. The research was carried out on the example of the chain of submesoscale eddies identified in the Tumen River water transport area in the Japan/East Sea. MODIS Aqua/Terra satellite data of the remotely sensed reflectance (Rrs) and Rrs band ratio at various wavelengths, chlorophyll-a concentration, and, for comparison, sea surface temperature (sst) were analyzed. Additionally, the results of ship surveys in September 2009 were used to study the influence of eddy vertical structure on the obtained remote characteristics. The best characteristic for detecting the studied eddies in satellite ocean color data was the MODIS chlor_a standard product, which is an estimate of chlorophyll-a concentration obtained by a combination of the three-band reflectance difference algorithm (CI) for low concentrations and the band-ratio algorithm (OCx) for high concentrations. At the same time, the weakest contrasts were in sst data due to similar water heating inside and outside the eddies. The best eddy contrast-to-noise ratio according to Rrs spectra is achieved at 547 nm in the spectral region of seawater with maximum transparency and low relative errors of measurements. The Rrs at 678 nm and associated products may be a significant characteristic for eddy detection if there are many phytoplankton in the eddy waters. The maximum depth of the remotely sensed contrast formation of the considered eddy vertical structure was ~6 m, which was significantly less than the maximum spectral penetration depth of solar radiation for remote sensing, which was in the 14–17 m range. The results obtained can be used to determine the characteristics that provide the best contrast for detecting eddy structures in remotely sensed reflectance data and to improve the interpretation of remote spectral ocean color data in the areas of eddies activity.

Analytical modelling of desiccation crack depth estimation for granitic soils

Desiccation cracking has been aggravated by the frequent extreme weather events and climate change in recent years. The presence of these cracks compromises the integrity of soil structures and significantly contributes to rainfall infiltration, slope stability, as well as soil deformation. According to tensile failure theory and Hookean elastic equation, an analytical model was established to predict crack depth under continuous desiccating conditions. The essential input parameters for the modelling are the modulus ratio and tensile strength, which can be determined through uniaxial tensile and shear tests. The maximum crack depth is estimated based on the suction change profile of the soil under investigation. Herein, the suction change profiles were developed from volumetric water content monitoring at various depths and utilizing the soil water characteristic curve (SWCC) of the investigated soil. Validation of the proposed method was conducted through laboratory simulations, specifically in the context of crack formation in granitic soils under continuous drying conditions. The predicted crack depth, in a range of 0.22 ∼ 0.30 m, closely aligned with the observed values. Collectively, for a specific soil with given elastic parameters and strength, crack depth can be estimated through suction change. This approach, compared with existing crack modeling methods, offers a simple and efficient way for crack depth estimation, holding promise for practical applications.