Sand Research Articles

Realtime estimation of average sand grain diameter and sand bed height and mass for a trailing suction hopper dredger.

A Trailing Suction Hopper Dredger (TSHD) in the sailing process, excavating seabed sediment with the drag head and pumping it through the pipeline to the spoil hopper sedimentation. The spoil hopper sedimentation process, as a critical factor affecting the loading yield and efficiency of a dredger, is susceptible to the influence of different average sand grain diameter . However, the soil type tends to change continuously during the loading process, making it difficult to obtain the by measurement or calculation. In this paper, combined with the existing simplified one-dimensional sedimentation model and simulated loading data, the Bootstrap Particle Filter (BPF), Gaussian Particle Swarm Optimized Particle Filter (GPSO-PF), Assisted Particle Filter (APF), Continuous-Discrete Feedback Particle Filter based on the constant feedback gain approximation (CD-FPF-CG) and the Galerkin method feedback gain approximation (CD-FPF-GL) are applied in the numerical simulations for online estimation of important variables such as the average sand grain diameter , the sand bed height and mass , respectively. The simulations results show that the CD-FPF-CG has a higher numerical accuracy and efficiency than the BPF, GPSO-PF, APF and CD-FPF-GL. Therefore, the CD-FPF-CG is used to estimate the above important variables for the actual vessel and the initial value of the average sand grain diameter for the CD-FPF-CG is determined via Simulated Annealing Multiple Population Genetic Algorithm (SAMPGA).

Morphodynamics drive the transport and accumulation of anthropogenic microparticles in tropical coastal depositional systems in southeastern Brazil.

A significant limitation in current coastal pollution research is that microplastics (<5 mm) comprise only a fraction of all anthropogenic microparticles (AMP, <5 mm) scale residues. Comprehensive AMP assessments, including those comprising semisynthetic, and modified natural compositions, are lacking. For instance, the accumulation of AMP in different coastal morphological features within a depositional system remains poorly known, fueling long-lasting debates about the distribution process of microparticles. Using a multi-proxy approach, we address mutual interactions between distinct surface morphologies (tidal flats, beaches, and foredunes) and transport and deposition dynamics of AMP. This issue was addressed by analyzing sediment and water samples collected at a marine protected area in the south coastal of São Paulo (Brazil). Here, we showed that AMP abundance in the tidal mudflat (18,500-20,500 particles/kg) was four times higher than in beach sands (4700-5900 particles/kg), while the lowest abundance was observed in foredune sands (4350 particles/kg). This can be attributed to the low-energy hydrodynamics of tidal flats associated with the cohesive behavior of muddy sediments, which consequently favor trapping and act as the main sink for AMP. Further, coastal processes (waves and currents) drive AMP onshore through sediment transport from the surfzone to the beach, from where the AMP becomes available for onshore eolian transport. Higher AMP abundance (85 particles/L) was observed in the marine water samples compared to the estuarine water samples (35 particles/L). Fibers <1 mm appeared as the predominant AMP in the sediment (99-100 %) and water (80-95 %) samples, primarily consisting of modified cellulose (73 %), dye signature only (16 %), and microplastics (11 %). Consequently, we argue that to fully comprehend the spatial distribution of AMP in coastal sediments and waters, it is crucial to analyze these microparticles from an integrated perspective, primarily considering the hydro-wind dynamics of different coastal morpho-sedimentary compartments combined with sediment grain size.

Development of sustainable high-performance desert sand concrete: Engineering and environmental impacts of compression casting

Development of sustainable high-performance desert sand concrete: Engineering and environmental impacts of compression casting

Performance Analysis of FFF-Printed Carbon Fiber Composites Subjected to Different Annealing Methods

Annealing is a popular post-process used to enhance the performance of parts made by fused filament fabrication. In this work, four different carbon-fiber-based composites were subjected to two different annealing methods to compare their effectiveness in terms of dimensional stability, surface roughness, tensile strength, hardness, and flexural strength. The four materials include PLA-CF, PAHT-CF, PETG-CF, and ABS-CF. The annealing methods involved heating the printed composites inside an oven in two different ways: placed on a tray and fluidized bed annealing with sharp sand. Annealing was conducted for a one-hour time interval at different annealing temperatures selected as per the glass transition temperatures of the four materials. The results showed that oven annealing provides better results under all scenarios except dimensional stability. PETG-CF and ABS-CF composites were significantly affected by oven annealing with expansion along the z-axis as high 8.42% and 18% being observed for PETG-CF and ABS-CF, respectively. Oven annealing showed better surface finish due to controlled and uniform heating, whereas the abrasive nature of sand and contact with sand grains caused inconsistencies on the surface of the composites. Sand annealing showed comparable hardness values to oven annealing. For tensile and flexural testing, sand annealing showed consistent values for all cases but lower than those obtained by oven annealing. However, oven annealing values started to decrease at elevated temperatures for PETG-CF and ABS-CF. This work offers a valuable comparison by highlighting the limitations of conventional oven annealing in achieving dimensional stability. It provides insights that can be leveraged to fine-tune designs for optimal results when working with different FFF-printed carbon-fiber-based composites, ensuring better accuracy and performance across various applications.

Transient Sand Scour Dynamics Induced by Pulsed Submerged Water Jets: Simulation Analysis

Water jet scouring technology is extensively applied in marine engineering, harbor maintenance, river training, and various other fields, showcasing a broad spectrum of potential applications. However, achieving a comprehensive understanding of the transient sand scouring characteristics of water jets remains challenging due to the inherent complexity of the coupled flow structure involving submerged jets and environmental fluids, along with the intricate dynamics of two-phase flow. This study, rooted in numerical simulation and experimental validation, introduces pulse characteristics into a submerged jet. A thorough investigation is conducted to explore the transient sand scouring characteristics and sand transport laws of the submerged jet under diverse working conditions. The results of this study revealed that the main reason for the asymmetry of the sand pit morphology is not the non-uniform distribution of sand grains, but more likely caused by turbulence effects. Simultaneously, within the initial 0.25 s of the pulse cycle, suspended sediment resulting from the pulsed jet in the preceding cycle gradually transports to the dune and its surrounding areas. Subsequently, from 0.25 s to 0.5 s, sediment on both sides of the pit’s bottom undergoes movement and amalgamation with the sediment that remained unsettled during the previous cycle. The findings reveal that higher jet velocities significantly enhance sediment suspension, migration, and redeposition, leading to deeper erosion and the rapid formation of the sand pit’s outline within 2 s. Additionally, the jet velocity and the impact distance are identified as critical factors influencing erosion depth and sediment dynamics. These insights advance the understanding of erosion mechanisms driven by pulsed jets, highlighting their impact on sediment transport processes. The research findings provide important guidance for dredging and ocean engineering fields and offer a theoretical basis for improving the understanding of submerged jet scouring mechanisms.

Influence of particle density on turbulence characteristics over a rough surface

The objective of the study is to use a 3D Acoustic Doppler Velocimeter (ADV) to gauge the typical flow and turbulence characteristics within a non-uniform open channel. The findings of experimental examinations of the subcritical flow along the channel are presented in this work. The behavior of sand grains in turbulent open channel flow across porous and rough bed surfaces was examined in laboratory research, and the results were obtained. The properties of turbulent flow, i.e., turbulence intensity, turbulent kinetic energy, and Reynolds shear stresses, are determined from ADV data. The continuity equation and the Reynolds equation of open-channel flow have been used to build theoretical formulations for the velocity distribution and Reynolds stress distribution in the vertical direction. Measured profiles of vertical velocity and Reynolds stress are compared to the derived expressions. The impact of the size of particles on the distribution of mean flow characteristics is discussed. This work provides a novel origin for the profile and analyzes the behavior of the vertical velocity distribution in the region where fully formed turbulence is dominating in open channels using the Navier–Stokes equations. In comparison to other sand roughness, Chopan sand bed (with greater density) exhibits the strongest turbulence intensities in both vertical and streamwise direction just next to the bed when away from the channel boundary. In contrast to flow across a rough surface, the variance ranges between 150 and 250% concerning the channel bed’s roughness type, impacting the velocity triple products that signifies transfer of turbulent kinetic energy.

Predicting the unseen: A shoreline shift analysis and prediction along Mayo Bay, Davao Oriental

45%-60% of the world’s population resides in shoreline areas. Shoreline regions are one of the most vulnerable areas to the effects of global warming. Positions of shorelines are challenging to predict, but the trend of accretion and erosion can be determined using statistical and geospatial techniques. Mati City is a major tourist destination for white sand beaches and pristine waters. Shorelines along Mayo Bay are a source of income for the local community. However, Mayo Bay has been subjected to shifts due to erosion. This study aims to determine the trend of the shoreline shift in Mayo Bay from 2013 to 2023. Landsat 8 OLI satellite images are used in this study. Results reveal that most shorelines experienced erosion, with 97.26% erosion transects. The shoreline length has slightly increased by 0.08% from 2013 to 2023 and is predicted to increase by 3.57% in 2063 and 11.51% by 2100. Barangay Lucatan shows the highest shoreline expansion, while Barangays Bobon and Dahican exhibit the most erosion, with mean rates of -27.15 m/year and -23.60 m/year, respectively. With a classification accuracy of 89% and Root Mean Square Error (RMSE) of 0.05, the study provides a reliable basis for Mayo Bay’s shoreline management. The findings will inform erosion mitigation efforts and guide sustainable coastal management plans for at-risk areas.

Sensibility in the impact of aeolian sand cover on permafrost degradation in Qinghai-Xizang Plateau

Abstract Environmental transformations and intensifying desertification across the Qinghai-Xizang Plateau significantly influence permafrost degradation, heightening risks associated with carbon emissions, thermal hazards, and infrastructural damage. However, the specific response of permafrost to desertification remains insufficiently understood. Here, we employed numerical modelling to examine the sensitivity of the impact of aeolian sand cover (ASC) on permafrost degradation. Our findings reveal that the thickness and moisture content of ASC profoundly affects permafrost degradation. Moreover, permafrost thermal stability and the rate of climatic warming modulate this degradation process. The simulation results identify two critical thickness thresholds for ASC: 20 cm and 80-120 cm. Specifically, dry ASC thinner than 20 cm accelerates permafrost degradation driven by desertification, whereas ASC thicker than 20 cm mitigates this effect. Furthermore, increased moisture in ASC extends the thickness thresholds to 80-120 cm. These results suggest that climatic variations in the Qinghai-Xizang Plateau, particularly transitions towards either warming-drying or warming-wetting, will markedly influence the response of permafrost to desertification. Notably, a warming-drying climate may reduce the potential degradation of permafrost caused by desertification. This study provides a critical reference for understanding the impact of aeolian desertification on permafrost in regions beyond the Qinghai-Xizang Plateau. It holds significant policy implications for environmental conservation and infrastructure development within the plateau.

Study of phase transformation of calcium silicate using desert sand as raw materials

Study of phase transformation of calcium silicate using desert sand as raw materials

Properties of Steel Fiber Reinforced Desert Sand Concrete

To study the effect of steel fibers on the mechanical properties of desert sand concrete (DSC), three lengths (12 mm, 16 mm, and 20 mm) of steel fibers and five volumetric admixtures (0.4%, 0.8%, 1.2%, and 1.6%) of steel fibers were selected to make 13 groups of concrete specimens (78 cubic specimens and 39 prismatic specimens). Compressive test, splitting test and flexural test were carried out on the specimens of DSC after curing for 28 days. According to the test results, the influence law of each parameter on the mechanical properties of DSC was analyzed, and the working principle of steel fibers to improve the mechanical properties of DSC was described by combining macroscopic and microscopic methods. The results showed that the addition of steel fibers can effectively improve the damage pattern of DSC, and all the mechanical properties of DSC are improved; 12 mm steel fibers were relatively effective in enhancing the compressive strength of DSC and 20 mm steel fibers were relatively effective in enhancing the splitting and flexural strength of DSC; Both macroscopic and microscopic results showed that the addition of appropriate amount of steel fibers can effectively fill the internal pores of DSC. The results can provide theoretical basis and technical support for the engineering application of steel fiber reinforced DSC.

Soft matter mechanics of baseball’s Rubbing Mud

Researchers looking for sustainable materials with optimal mechanical properties may draw inspiration from a baseball tradition. For nearly 100 y, a mysterious mud harvested from an undisclosed river site in New Jersey (USA) has been the agent of choice in the USA's Major League Baseball for "de-glossing" new baseballs. It is unclear, however, what makes this "Rubbing Mud" work. Here, we perform a multiscale investigation of the rheology and tribology of this mud material under baseball-relevant conditions and identify three mechanisms by which the mud alters the surface properties of the baseball. First, the mud creates a more uniform baseball surface by filling in pores in the leather; this is possible because of its relatively high cohesion (clays and organics) making the material remarkably shear thinning. Second, the residue of cohesive particles coating the baseball effectively doubles contact adhesion. Third, a sparse population of angular sand grains are bonded to the baseball by clay-sized particles, leaving a studded surface that enhances friction. The proportions of cohesive, frictional, and viscous elements in Rubbing Mud conspire to create a soft material with an unusual mix of properties, that could find other applications in the development of sustainable geomaterials. Our improved understanding of the flow and friction of natural muds may also find use in modeling natural hazards such as mudslides and for locomotion in muddy environments.

Biogeography of Australian Camphorosmeae and Diversification in Climatic Space and Across Arid Habitat Types.

This study investigates the biogeography of the Australian Camphorosmeae (Amaranthaceae s.l.) lineage and how it relates to shifts in climatic niche and habitat types. Building on previous research and data resources, we integrate molecular phylogenetics, bioclimatic data and biogeographical models to deepen our understanding of the diversification and adaptation of this group across Australia's diverse landscapes in relation to palaeoclimatic changes. For 159 species representing 12 genera, georeferenced distribution points were used to define the most informative bioclimatic variables using principal component analysis. Evolutionary shifts in climatic niches and habitat types were analysed, revealing clade-specific shifts and adaptations to different habitats and climatic conditions. Biogeographical analyses allowed us to infer ancestral areas of Camphorosmeae in Australia and relate their expansion over evolutionary time to habitat shifts. Preadaptation of this group to warm and dry habitats coupled with key periods of aridification in Australia, particularly during the Late Miocene to Pliocene, were critical in driving its diversification through migration and local adaptation to varied habitats of arid Australia. Our analyses suggest that the 'Riverine Desert' habitat offered suitable conditions for ancestral Australian Camphorosmeae and facilitated their early widespread dispersal in the Western and Eastern Desert. We hypothesise that early diverging lineages such as Roycea adapted to the later emerging 'Desert Lake' habitat when it spread in Western Australia during the Early Pliocene. Further, habitat type shifts occurred from 'Riverine Desert' to 'Shield Plain', 'Karst Plain' and to 'Sand Desert' also during the Pliocene and Pleistocene once these habitat types emerged. This study illustrates the complex interplay between ecological flexibility and niche conservatism in shaping the biodiversity of Australian Camphorosmeae.

Potential ecological risk assessment of microplastics in environmental compartments in Mexico: A meta-analysis.

Microplastic (MP) environmental contamination has been widely studied in Mexico; however, the evaluation of the associated risk to MP in environmental compartments is scarce. Therefore, this study addresses this issue using diverse indicators such as the Pollution Load Index (PLI), the Polymer Risk Index (PRI), and the Potential Ecological Risk Index (PERI). The results of a meta-analysis revealed high MP contamination levels in most of the studied compartments, which included marine and estuarine waters, beach sand, freshwater, sediments, and biota. Regarding the risk assessment indicators, PLIs indicated low (56%), dangerous (22%), moderate (12%), and high (10%) levels across compartments. Meanwhile, PRIs displayed concerning values, with 36%, 35%, 20%, and 9% exhibiting dangerous, high, moderate, and low levels, respectively. Thus, high PRI values emphasized the significant rise in MP pollution, largely attributed to high-hazard polymer compositions. Otherwise, PERIs showed low (56%), very dangerous (29%), moderate (6%), high (5%), and dangerous (4%) levels. Thus, the ecological risk in Mexico is widespread and mainly linked to MP abundance, polymer type, environmental matrix, and organisms' characteristics. This study represents the first attempt at MP ecological risk assessment in Mexico, providing crucial insights for developing mitigation strategies to address concerns about MP contamination.

Direct numerical simulation of turbulent heat transfer over surfaces with hemisphere protrusions

Direct numerical simulations (DNSs) of turbulent heat transfer over walls with regularly distributed hemispheric protrusions were conducted to explore how the arrangement and number density of hemispheres affect the turbulent heat transfer. For the rough walls, we considered eight rough surfaces, in which the number density, i.e., the number of hemispheres per unit area, and the distances between two neighboring hemispheres in the streamwise and spanwise directions were systematically varied. The friction Reynolds number was fixed at 660, and we considered an incompressible airflow with a Prandtl number of 0.71, neglecting the buoyancy effects. The results showed that the velocity roughness function strongly depends on the hemisphere arrangement and number density. The spanwise-aligned hemisphere array yields the larger velocity roughness function than its streamwise-aligned hemisphere counterpart, whereas the temperature roughness function depends only on number density. The Reynolds analogy factor decreases with increasing inner-scaled equivalent sand grain roughness, and the decreasing trend is weakly affected by the number density. We analyzed the momentum and heat transfer budgets and found that the pressure drag, which dominates the momentum transfer near the wall, is strongly affected by the hemisphere arrangement and number density. In contrast, the roughness-induced wall heat transfer term, which is the dominant contributor to near-wall heat transfer, depends only on the number density. This difference is the driving mechanism that causes dissimilar trends in momentum and heat transfer over walls with hemispheric protrusions.

Evaluation of climate conditions and ecological traits that limit the distribution expansion of alien Lolium rigidum in Japan

Invasive alien plants cause severe global problems; therefore, determining the factors that lead to the success or failure of invasion is a critical question in the field of invasion ecology. In this study, we aimed to determine the factors underlying differences in the distribution range of alien plants in Japan by investigating why Lolium multiflorum thrives in a wide range of habitats while L. rigidum is mainly distributed on sandy beaches. We initially evaluated environmental niche suitability through species distribution modelling and subsequently examined whether species traits influence the differences in range expansion between the two species. We used MaxEnt modelling to identify potential environmental niches for both species. The analysis revealed that L. rigidum was considerably less suited to the Japanese climate compared to L. multiflorum, with high summer precipitation in Japan identified as one of the climatic factors limiting the distribution of L. rigidum. Given that these winter annual plants remain dormant as seeds during summer, in subsequent experiments, we buried seeds in paddy field soil and sandy beach sand during summer and evaluated their survival rate in autumn. The survival rate of L. rigidum seeds was significantly lower than that of L. multiflorum, particularly in paddy soil. Factors contributing to seed mortality may include the decay or early germination of L. rigidum seeds under Japan’s high rainfall conditions. This study emphasises the importance of considering local environmental factors alongside climate niche modelling in the risk assessment of invasive species. Moreover, the integration of species distribution modelling for large-scale evaluations and manipulation experiments for fine-scale assessments proved effective in identifying climatic conditions and species traits influencing the success or failure of alien species invasion.

Optimization Study of the Structural Parameters of an Artificial Percolation Intake Riverbed Based on a Numerical Orthogonal Test

Research on water abstraction techniques in sandy rivers is crucial for addressing water scarcity issues in northern China. This study introduces an artificial percolation water intake riverbed structural model designed to prevent sand intake and facilitate the extraction of clear water from sandy rivers, the main function of which is to artificially construct a helical flow field to realize the separation of water and sand and, at the same time, percolate the water. In this paper, we use a numerical orthogonal test method to study the influence of structural parameters and their combinations on water extraction by percolation, and the preferred combination of structural parameters. The main conclusions of this paper are as follows: Under the condition of certain structural parameters of the artificial riverbed, the single-width flow rate has an important effect on the mean circumferential flow rate of the vortex tube and the vortex tube seepage volume. The effect of different structural parameters on the mean circumferential flow rate of the vortex tube and the vortex tube seepage varies in magnitude. The longitudinal slope of artificial riverbed i had the greatest and most significant effect on the mean circumferential flow rate of the vortex tube, and each structural parameter had some effect on the vortex tube seepage Q but not to a significant level. When the sand content of the water flow is 15 kg/m3 and the maximum sand grain size of the suspended mass is 2 mm, the optimal structural parameter combinations of the artificial riverbed under different working conditions are as follows: Combination 20 is the optimal structural parameter combination for q = 0.3 m2/s; Combination 24 is the optimal structural parameter combination for q = 0.6 m2/s; and Combination 24 is the optimal structural parameter combination for q = 0.9 m2/s. The present study is of great significance for understanding the influence of each structural parameter and its combination on the effect of the water intake and sand discharge of an artificial percolation intake riverbed, and for optimizing the combination of the structural parameters of an artificial percolation intake riverbed.

Temporal variability of plastic litter in two sand beaches of San Andres Island, Colombian Caribbean

Temporal variability of plastic litter in two sand beaches of San Andres Island, Colombian Caribbean

Mechanical Properties and Microstructure of Alkali-Activated Cements with Granulated Blast Furnace Slag, Fly Ash and Desert Sand

In this study, desert sand was used as supplementary materials in alkali-activated cements (AAC) with granulated blast furnace slag (GBFS) and fly ash (FA). For the first time, a systematic investigation was conducted on the effects of various treatment methods and contents of desert sand on the strength and microstructure of AAC. This study also analyzed the X-ray diffractometer (XRD), Scanning Electron Microscopy-Energy Dispersive X-ray Microanalysis (SEM-EDX), Mercury Intrusion Porosimetry (MIP), pH values, and Fourier-transform infrared spectroscopy (FT-IR) properties of AAC pastes containing differently treated desert sand to uncover the mechanisms by which these treatments and dosages influence mechanical properties of AAC. Untreated desert sand (DS), temperature-treated desert sand (DS-T), and ground desert sand for two different durations (20 mins and 30 mins) all exhibited some pozzolanic activity but primarily acted as fillers in the AAC pastes. Among the samples, DS-T demonstrated the highest pozzolanic activity, though it was still less than that of fly ash (FA). The optimal dosage for the modified desert sands was determined to be 10%. However, The optimal dosage of different modified desert sands is 10%. The flexural strength of DS-G30-10 reaches 6.62 MPa and the compressive strength reaches 72.3 MPa, showing the best comprehensive mechanical properties.

Taxonomic, Physiological, and Biochemical Characterization of Asterarcys quadricellularis AQYS21 as a Promising Sustainable Feedstock for Biofuels and ω-3 Fatty Acids.

Asterarcys quadricellularis strain AQYS21, a green microalga isolated from the brackish waters near Manseong-ri Black Sand Beach in Korea, shows considerable potential as a source of bioactive compounds and biofuels. Therefore, this study analyzed the morphological, molecular, and biochemical characteristics of this strain; optimized its cultivation conditions; and evaluated its suitability for biodiesel production. Morphological analysis revealed characteristics typical of the Asterarcys genus: spherical to ellipsoidal cells with pyrenoid starch plates and mucilage-embedded coenobia. Additionally, features not previously reported in other A. quadricellularis strains were observed. These included young cells with meridional ribs and an asymmetric spindle-shaped form with one or two pointed ends. Molecular analysis using small-subunit rDNA and tufA sequences confirmed the identification of the strain AQYS21. This strain showed robust growth across a wide temperature range, with optimal conditions at 24 °C and 88 µmol m-2s-1 photon flux density. It was particularly rich in ω-3 α-linolenic acid and palmitic acid. Furthermore, its biodiesel properties indicated its suitability for biodiesel formulations. The biomass of this microalga may serve as a viable feedstock for biodiesel production and a valuable source of ω-3 fatty acids. These findings reveal new morphological characteristics of A. quadricellularis, enhancing our understanding of the species.

Aeolian Biodispersal of Terrestrial Microorganisms on Mars Through Saltation Bombardment of Spacecraft.

A major unknown in the field of planetary protection is the degree to which natural atmospheric processes remove terrestrial microorganisms from robotic and crewed spacecraft that could potentially contaminate Mars (i.e., forward contamination). We present experiments in which we measured the removal rate of Bacillus subtilis HA101 spores from aluminum surfaces under the bombardment of naturally rounded sand grains. To simulate grain impacts, we constructed a pneumatic sand-feed system and gun to accelerate grains to a desired speed, with independent control of impacting grain mass, flux, and angle. Spore counts of the resulting bombarded surfaces when using scanning electron microscopy indicate that although spores directly impacted by sand grains would likely be killed, those immediately adjacent to grain impacts might be released into the environment intact. The experiments demonstrate a linear relationship between the fractional dislodgement rate of spores and grain impact speed, which can be used to estimate input to microbial transport models (e.g., using numerical models of saltation). Even the slowest grain impacts (∼2.7 m/s) dislodged spores. Such slow events may be common and widespread on Mars, which suggests that microbial dislodgement by slow saltation near the surface is largely unavoidable.