Surface Processes Research Articles

Estimation of 100 m root zone soil moisture by downscaling 1 km soil water index with machine learning and multiple geodata

Root zone soil moisture (RZSM) is crucial for agricultural water management and land surface processes. The 1 km soil water index (SWI) dataset from Copernicus Global Land services, with eight fixed characteristic time lengths (T), requires root zone depth optimization (Topt) and is limited in use due to its low spatial resolution. To estimate RZSM at 100-m resolution, we integrate the depth specificity of SWI and employed random forest (RF) downscaling. Topographic synthetic aperture radar (SAR) and optical datasets were utilized to develop three RF models (RF1: SAR, RF2: optical, RF3: SAR + optical). At the DEMMIN experimental site in northeastern Germany, Topt (in days) varies from 20 to 60 for depths of 10 to 30 cm, increasing to 100 for 40–60 cm. RF3 outperformed other models with 1 km test data. Following residual correction, all high-resolution predictions exhibited strong spatial accuracy (R ≥ 0.94). Both products (1 km and 100 m) agreed well with observed RZSM during summer but overestimated in winter. Mean R between observed RZSM and 1 km (100 m; RF1, RF2, and RF3) SWI ranges from 0.74 (0.67, 0.76, and 0.68) to 0.90 (0.88, 0.81, and 0.82), with the lowest and highest R achieved at 10 cm and 30 cm depths, respectively. The average RMSE using 1 km (100 m; RF1, RF2, and RF3) SWI increased from 2.20 Vol.% (2.28, 2.28, and 2.35) at 30 cm to 3.40 Vol.% (3.50, 3.70, and 3.60) at 60 cm. These negligible accuracy differences underpin the potential of the proposed method to estimate RZSM for precise local applications, e.g., irrigation management.

Research on Surface Processing Method of Pulse Transmission Signal of Amplitude-Modulated Drilling Fluid in 10,000-m Deep Wells

Conventional Measurement-While-Drilling (MWD) technology is unable to function statically at the predicted temperatures of deep formations exceeding 200 °C in wells reaching depths of 10,000 m. It is limited to measuring downhole engineering parameters through purely mechanical means, such as inclination. However, the accurate long-distance transmission of drilling fluid pulse signals poses a significant bottleneck, restricting the application of these mechanical measurement methods. To address these issues, this paper develops and designs an algorithm to identify and analyze the amplitude characteristics of deep well mud signals. By employing a signal coding algorithm, a signal processing analysis method, and a signal feature recognition algorithm based on grey correlation degree, we construct a signal recognition method capable of decoding mud amplitude encoded signals. Key techniques such as filtering, smoothing, and feature extraction are utilized in the signal processing, and the proposed method’s effectiveness is verified through the analysis of collected signals. Furthermore, long-distance simulation analysis software is developed to evaluate waveform distortion during extended transmission, confirming the feasibility of the recognition algorithm. Laboratory experiments demonstrate that this algorithm can accurately recognize and demodulate signals generated by mechanical inclinometer structures, providing a novel decoding method for signal transmission in deep and ultra-deep wells.

Numerical investigation on drying characteristics between hot wind and wet coating of battery electrode

In this paper, a three-dimensional dynamic drying model is established between hot wind and wet coating based on dynamic mesh method and multi-field coupling theory of porous media. This model considers the combined influences of hot wind and aluminum plate on drying characteristics of wet coating comprehensively based on meshless parallel method. It is proved to be reliable because its simulation data within the error range of plus/minus 15 %. Through this model, the influences and distribution of different operating parameters on drying characteristics are analyzed for surface and interior of wet coating, and the velocity, temperature and relative humidity of hot wind are selected as 8 m/s-10 m s-1, 353.15K-373.15 K and 35 %-55 %, respectively. The results show that the drying processes of surface and interior can be accelerated effectively for wet coating by increasing velocity and temperature of hot wind, while the relative humidity has little effect on its drying characteristics. Meanwhile, the variation trends of wet coating with the drying time as 0–20 s, 20s-30 s and 30s-50 s are consistent with the acceleration, uniform and deceleration drying processes of porous media, respectively. Finally, the drying uniformity is compared for different partitions of wet coating. The results show that the growth gradient of drying non-uniformity with the increase of velocity is smaller than that with the increase of temperature. The change gradient of drying non-uniformity for wet coating with the change of temperature is larger than that with the change of velocity. For drying model in this paper, the optimal operating strategy when the velocity of hot wind is 8 m/s-10 m s-1, temperature is 363.15 K and relative humidity is 45 % can be adopted to improve the drying uniformity of wet coating while reducing its total drying time in engineering. The research results provide an important theoretical basis for control parameters regulation of lithium-ion battery coating oven.

Earth surface exchanges (ESEX) discussion of ‘Swelling and flow of expanding clays as a cause for nontectonic deformations in a glacial–interglacial environment: Holy Cross Mountains, Poland’ by E.Jurewicz, P.Karnkowski, A.Czarnecka‐Skwarek, E.Wójcik, I.Gawriuczenkow. Earth Surface Processes and Landforms2023: 1–16. https://doi.org/10.1002/esp.5609

AbstractIn a recently published report focused on the role of swelling of Triassic clays as the dominant process that led to the local steepening of competent Jurassic strata, its authors presented an opinion on the lack of evidence for the existence of the Gnieździska–Brzeziny strike‐slip fault along the contact between the Triassic and Jurassic rocks. This discussion presents the structural, geophysical, cartographic and geomechanical data indicating that the contact of Triassic and Jurassic rocks is defined by the vertical dextral strike‐slip Gnieździska–Brzeziny fault, which was formed after tilting of the beds in the Late Cretaceous. The presented evidence validates the tectonic deformation of Mesozoic rocks related to strike‐slip faulting. The dominant horizontal contraction across the fault planes within the restraining stepovers resulted in tilting of the beds, which is a well‐recognized phenomenon within the strike‐slip fault networks worldwide.

Surface Enhanced Nonlinear Raman Processes for Advanced Vibrational Probing.

Surface enhanced Raman scattering (SERS) is not restricted to the well-known one-photon excited spontaneous Raman process that gives information on molecular composition, structure, and interaction through vibrational probing with high sensitivity. The enhancement mainly originates in high local fields, specifically those provided by localized surface plasmon resonances of metal nanostructures. High local fields can particularly support nonlinear Raman scattering, as it depends on the fields to higher powers. By revealing plasmon-molecule interactions, nonlinear Raman processes provide a very sensitive access to the properties of metal nanomaterials and their interfaces with molecules and other materials. This Perspective discusses plasmon-enhanced spontaneous and coherent nonlinear Raman scattering with the aim of identifying advantages that lead to an advanced vibrational characterization of such systems. The discussion will highlight the aspects of vibrational information that can be gained based on specific advantages of different incoherent and coherent Raman scattering and their surface enhancement. While the incoherent process of surface enhanced hyper Raman scattering (SEHRS) gives highly selective and spectral information complementary to SERS, the incoherent process of surface enhanced pumped anti-Stokes Raman scattering (SEPARS) can help to infer effective nonresonant SERS cross sections and allows to see "hot" vibrational transitions. Surface enhanced coherent anti-Stokes Raman scattering (SECARS) and surface enhanced stimulated Raman scattering (SESRS) combine the advantages of high local fields and coherence, which gives rise to high detection sensitivity and offers possibilities to explore molecule-plasmon interactions for a comprehensive characterization of composite and hybrid structures in materials research, catalysis, and nanobiophotonics.

Miocene climate cooling and aridification of Antarctica may have enhanced syn-extensional magmatism in the western Ross Sea

Continental rift systems are commonly characterized by volcanism with parental basaltic magmas sourced from the mantle. Erosion of the rift shoulders and sedimentation in the adjacent basins can affect the stress and thermal fields at depth, thereby affecting partial mantle melting. However, the sensitivity of magmatic activity to such surface forcing is elusive. Geological observations from the western Ross Sea, Antarctica, suggest rift onset in the Cretaceous with a transition from wide-rifting to narrow-rifting at the boundary between the Antarctic craton and the Transantarctic Mountains. Miocene climate cooling during rifting in the western Ross Sea, in addition, leads to an abrupt decrease in sedimentation rate, synchronous to the emplacement of the McMurdo Volcanic Group. This represents the largest alkali province worldwide, extending both inland and offshore of Transantarctic Mountains and western Ross Sea, respectively. Here, we use coupled thermo-mechanical and landscape evolution numerical modeling to quantify melt production in slowly stretching rift basins due to changes in erosion/deposition rates. The model combines visco-elasto-plastic deformation of the lithosphere and underlying mantle during extension, partial rock melting, and linear hillslope diffusion of the surface topography. The parametric study covers a range of slow extension rates, crustal thicknesses, mantle potential temperatures and diffusion coefficients. Numerical simulations successfully reproduce the ∼150–200-km-wide extension of western Ross Sea and Miocene-to-present asthenospheric melt production (McMurdo Volcanic Group). Results further show that slow rifts magmatism is highly sensitive to sediment deposition within the basin, which inhibits mantle decompression melting and delays the crustal breakup. Regional climate-driven sedimentation rate changes are thus likely to have affected the syn-rift magmatic history of the western Ross Sea, Antarctica, supporting the relevance of interactions between surface and deep-seated processes across extensional settings.

A low-cost UAV survey can unravel Baird's Tapir (Tapirus bairdii) trail network dynamics in a neotropical highland forest

UAV technology has transformed spatial data collection and high-spatial resolution analysis of diverse environments around the world. Its role within geosciences, ecology, engineering, and other sciences has been increasing withing the last decade. In ecological and geomorphological aspects, it offers a powerful tool for studying landforms, surface processes, vegetation, and animal behavior globally. Our study employs high-resolution UAV surveys to analyze Tapirus bairdii trail networks and their connection to the landscape in a Costa Rican highland paramo-forest national park. Using a DJI Phantom 4 V.2 UAV, we conducted a photogrammetric flight over 3.19 ha, producing datasets with a spatial resolution of 2.99 cm/pixel. These datasets facilitated geostatistical analysis of Tapirus bairdii trails, revealing their complexity and hotspots near lagoons. We investigated lagoon characteristics, finding that finer sediments spatially correspond with higher trail activity. This suggests that sediment types in lagoons influence Tapirus bairdii navigation, impacting trail network composition. Our findings highlight UAV technology's role in advancing ecological and geomorphological research in protected areas, providing insights into Tapirus bairdii behavior within highland ecosystems. Overall, to the date this is the first high-resolution UAV survey of Tapirus bairdii within these types of highland tropical environments.

Quartz luminescence sensitivity enhanced by residence time in the critical zone

The emerging use of quartz luminescence properties to characterize Earth-surface processes shows promise, with optically stimulated luminescence (OSL) sensitivity proposed as a valuable tool for provenance or sediment history tracing. However, the geologic processes that lead to quartz sensitization remain unclear. Here we study the impact of source rock and surface processes on the luminescence properties of quartz sand from bedrock and modern and Late Pleistocene alluvium generated from a mountainous catchment in northern Utah, USA. Continuous wave and linear modulated OSL are used to characterize the luminescence sensitivity and intensity of the fast-decay component. We compare the OSL sensitivity with sand-grain provenance and with proxies for surface processes such as topographic metrics, cosmogenic 10Be-derived erosion rates, chemical weathering indices, and magnetic susceptibility. Late Pleistocene sediment has low OSL sensitivity and a weak fast-decay component, similar to bedrock samples from the source area. In contrast, modern alluvium is dominated by the fast-decay component and has higher and more variable OSL sensitivity, with no clear relationship to upstream bedrock source. There is, however, an inverse relationship between OSL sensitivity and catchment-averaged erosion rates and a positive relationship with chemical weathering indices and magnetic susceptibility. These metrics suggest that the modern alluvium has experienced increased residence time in the shallow critical zone compared to the Late Pleistocene sediments. We suggest that changes in hillslope processes between the effectively wetter, cooler Pleistocene and the dryer, warmer conditions of the Holocene enhanced the luminescence properties. The results suggest that climatic controls on rates and processes of chemical and mechanical weathering and sediment transport and residence within the critical zone are encoded in the luminescence properties of quartz sand.

Direct Microenvironment Modulation of CO2 Electroreduction: Negatively Charged Ag Sites Going beyond Catalytic Surface Reactions.

Electrochemical reduction of CO2 is an important way to achieve carbon neutrality, and much effort has been devoted to the design of active sites. Apart from elevating the intrinsic activity, expanding the functionality of active sites may also boost catalytic performance. Here we designed "negatively charged Ag (nc-Ag)" active sites featuring both the intrinsic activity and the capability of regulating microenvironment, through modifying Ag nanoparticles with atomically dispersed Sn species. Different from conventional active sites (which only mediate the surface processes by bonding with the intermediates), the nc-Ag sites could also manipulate environmental species. Therefore, the sites could not only activate CO2, but also regulate interfacial H2O and CO2, as confirmed by operando spectroscopies. The catalyst delivers a high current density with a CO faradaic efficiency of 97 %. Our work here opens up new opportunities for the design of multifunctional electrocatalytic active sites.

Direct Microenvironment Modulation of CO2 Electroreduction: Negatively Charged Ag Sites Going beyond Catalytic Surface Reactions

AbstractElectrochemical reduction of CO2 is an important way to achieve carbon neutrality, and much effort has been devoted to the design of active sites. Apart from elevating the intrinsic activity, expanding the functionality of active sites may also boost catalytic performance. Here we designed “negatively charged Ag (nc‐Ag)” active sites featuring both the intrinsic activity and the capability of regulating microenvironment, through modifying Ag nanoparticles with atomically dispersed Sn species. Different from conventional active sites (which only mediate the surface processes by bonding with the intermediates), the nc‐Ag sites could also manipulate environmental species. Therefore, the sites could not only activate CO2, but also regulate interfacial H2O and CO2, as confirmed by operando spectroscopies. The catalyst delivers a high current density with a CO faradaic efficiency of 97 %. Our work here opens up new opportunities for the design of multifunctional electrocatalytic active sites.

Sea level and East Asian winter monsoon-controlled periodic transition of sinks in fine-grained sediments in the East China sea over the past 200 kyr

The study of critical geological processes of sediments from source to sink in the East China Sea (ECS) is of great significance for further understanding the surface processes, material cycling, and sedimentary evolution in the East Asian continental margin. Based on the high-resolution clay mineralogy and REEs in fine-grained sediments of Core CSHC-15, this study has analyzed the periodic transition mechanism of sinks in fine-grained sediments in the ECS from a source-to-sink perspective. The clay mineral provenances of Core CSHC-15 exhibited distinct periodic abrupt shifts between the Changjiang and Taiwan island over the past 200 kyr, indicating the periodic transitions of sinks in fine-grained sediments between the inner shelf of the ECS and the Okinawa Trough. When the sea level rose or fell to a critical depth (around −25 m or −50 m), the changes in the accommodation space of the continental shelf and the shelf fronts were the direct factors leading to the periodic transitions of sinks in fine-grained sediments in the ECS. The intense eccentricity cycles (100-kyr) of the clay mineral parameters of Core CSHC-15 reflected the impacts of the East Asian Winter Monsoon (EAWM). This study confirms that long-term (eccentricity and longer cycles) climate signals of the source areas can be extracted from the clastic sedimentary records of the ECS. The new finding highlights the periodic transition mechanism of sedimentary sinks in the ECS that will promote the progress of sedimentary geology since the Late Quaternary.

Induced surface process of graphene variants’ dispersion with biocompatible riboflavin

Graphene oxide (GO) and its reduced variant (rGO) are highly esteemed for their remarkable optical and electrical properties, along with their versatile surface chemistry. Ensuring uniform distribution and effectively utilizing their inherent properties is crucial for enhancing their application in biomedical devices. In our study, we strategically utilized riboflavin as a biocompatible dispersion agent to enhance the stability of rGO, which was notably better than GO. We rigorously assessed stability through UV–vis, fluorescence spectroscopy, and molecular dynamics simulation. These materials were comprehensively characterized for material and electrochemical properties, providing detailed insights into key attributes such as interlayer spacing, dispersibility, flake size, and superior electrical conductivity of rGO. Our multifaceted approach elucidated the performance characteristics and enhanced stability introduced by the dispersion efficiency of riboflavin. The practical applications of GO and rGO dispersed samples were examined through antimicrobial susceptibility using a zone inhibition test, revealing that the dispersion process mitigated the antimicrobial efficacy of GO and rGO. Overall, this study emphasizes the versatility and potential of rGO in various applications and highlights the importance of effective dispersion to maximize material performance.

Unloading Uplift Caused by Surface Processes in New Zealand's Southern Alps

AbstractThe Southern Alps experiences rapid bedrock uplift and intense surface processes like erosion and deglaciation. We quantify how the erosion and deglaciation contribute to the ongoing vertical motions using geophysical models. The erosional unloading uplift is found to be 0.5–1.5 mm/yr throughout the central Southern Alps, whereas the recent deglaciation may locally produce uplift up to 1–3 mm/yr. The estimated unloading uplift accounts for 10%–40% of the GNSS‐observed uplift. After correcting the unloading uplift, the GNSS‐observed uplift can be explained by about 4–6 mm/yr dip‐slip motion on the Alpine fault, which is 10%–50% below previous geodetic estimates. Hence, unloading uplift must be evaluated when interpreting geodetic observations in tectonically active mountain ranges subjected to intense surface processes.

Native and TMT Chestnut Extractives as Hydrophobic and Photostabylizing Additives for Wood Surfaces

Wood extractives have proven strong anti-oxidative properties which may be used to mitigate surface deterioration caused by photolytic effects and free radical formations. An interesting challenge regarding wood extractives is understanding how they behave in terms of treating natural wood surfaces to reduce anti-oxidative processes that arise from exposure to the main environmental factors. In this study, the possible efficacy of chestnut (Castanea sativa Mill.) extractives derived from native (CH) and thermally modified wood (TMT CH), as a means of protecting against UV exposure in poplar (Populus spp.) and spruce (Picea abies Karst.) wood, was evaluated. Chestnut wood was first thermally modified at 180 °C for 3 h, and the extractives were obtained by the accelerated solvent extraction technique (ASE) and subsequently used to treat wood surfaces. Samples were immersed in extractive solutions and exposed to artificial UV-weathering exposure, then contact angle and colour stability were monitored during the process. An FTIR analysis of the photo-degradation process of poplar and spruce surfaces was also executed. Extractives of TMT chestnut changed the total colour variation in both poplar and spruce wood. A much darker colour compared to the extractives of native wood was observed and an increase in ∆E* from 9.75 to 30.76 and 6.24 to 22.97 in poplar and spruce was calculated. The stability of the colour depended both on the surface wood and the type of extractive. The initial contact angle remained almost unchanged in the poplar wood surface and only slightly increased in spruce regardless of whether they were treated with extractives from native or TMT chestnut wood. A strong reduction in contact angle after the accelerated UV exposure test was observed, especially in spruce treated with CH extractives. FTIR analysis confirmed the lower levels of chemical degradation of surfaces observed by colorimetry, where TMT CH extractives formed more stable chemical bonds than native extractives. The comparative analysis in this study clarified the complex relationships between the effects of high-temperature modification of wood and the potential protective role of TMT extractives on some wood surfaces.

Quantitative Analysis of Aeolian Sand Provenance: A Comprehensive Analysis in the Otindag Dune Field, Central Inner Mongolia, China

The identification and quantification of aeolian sand contributions are essential for understanding the formation of dune fields and mechanisms of modern surface processes. In the present study, we take aeolian sand in the Otindag dune field (hereafter, often referred to as, simply, Otindag) as the research object. The dune field’s immediate source is quantitatively identified based on heavy minerals and the Conservativeness Index (CI), Consensus Ranking (CR), and the Consistent Tracer Selection (CTS) method. The primary source area of the aeolian sand was found to be from the northwestern, upwind area of the Otindag (59 ± 14%), followed by the Yinshan Mountain (17 ± 10%) and the lake basin (23 ± 12%). The proposed sediment transport model elucidates that sediments from the upwind of the Otindag are directly transported from the northwest to the Otindag, where they are deposited. Materials from the southern Yinshan Mountains are carried by rivers to the southern edge of the Otindag, where they are subsequently transported by wind and ultimately deposited. The lake deposits within the Otindag also contribute to the aeolian sand supply under the influence of wind. This study demonstrates that the fingerprinting techniques of CI, CR, and CTS serve as successful strategies for conducting quantitative provenance research in dune fields.

Prediction model of grinding roughness for worm with complicated space tooth surface

Optimum grinding parameters are crucial for achieving high-quality grinding of helical tooth surfaces for worm drives. The complex coupling motion relationship and formation mechanism between the worm blank and the grinding head make it difficult to predict the effect of grinding parameters on tooth surface roughness. Therefore, we developed a prediction model for the worm tooth surface roughness under conjugate grinding and applied it to the Roller Enveloping Worm Reducer (REWR). The forming process of the theoretical worm tooth surface during the grinding process was modeled by using the conjugate meshing principle. Considering the plowing and cutting effects of grinding particles on the tooth surface at different design parameters, feed speeds, and rotational speeds of the grinding head, the roughness prediction equation was established based on the theory of the maximum depth of valley bottom. Through the coupling analysis of the theoretical tooth surface model and the roughness prediction model, the prediction of the worm tooth surface roughness is realized. Based on the validated model, the influences of grinding parameters on the worm tooth surface roughness of REWR were quantitatively discussed. This study is of great significance for optimizing process parameters in the grinding of complex spatial surface transmissions.

Investigation of the surface charge behaviour of ettringite: Influence of pH, calcium, and sulphate ions

Ettringite is an important mineral that contributes to the overall performance of cementitious materials. Knowledge of the surface charge behaviour of a solid is necessary for a mechanistic description of surface processes such as adsorption or particle-particle interactions. The objective of this study was to develop a model capable of reproducing ettringite surface charge as a function of calcium, sulphate, and pH.Ettringite was synthesised and characterised using different analytical, microscopic, and spectroscopic techniques with the help of density functional theory. Electrophoretic mobility was measured using laser Doppler electrophoresis in alkaline waters representative of the cementitious environment.The behaviour of the ettringite surface charge was shown to be quite complex as sulphate and calcium acted in a competitive manner on the overall charge. The ζ-potential increases when the calcium content increases, whereas it decreases when sulphate increases. This is due to the possible adsorption of these ions at the surface, and the extent of the effect depends on the relative concentrations of Ca and SO42−.An electrostatic double layer model (DLM) was used to calculate the surface potential, considering the adsorption of both calcium and sulphate, as possible ions determining the potential (IDP), and formation of different complexes with ettringite surface functional groups (SOH). The variations of the ζ-potential could be satisfactorily predicted under the different chemical conditions of interest in a cementitious environment.

Impacts of Topography‐Based Subgrid Scheme and Downscaling of Atmospheric Forcing on Modeling Land Surface Processes in the Conterminous US

AbstractThe effects of small‐scale topography‐induced land surface heterogeneity are not well represented in current Earth System Models (ESMs). In this study, a new topography‐based subgrid structure referred to as topographic units (TGU) designed to better capture subgrid topographic effects, and methods to downscale atmospheric forcing to the land TGUs have been implemented in the Energy Exascale Earth System Model (E3SM) Land Model (ELM). Effects of the subgrid scheme and downscaling methods on ELM simulated land surface processes are evaluated over the conterminous United States (CONUS). For this purpose, ELM simulations are performed using two configurations without (NoD ELM) and with (D ELM) downscaling, both using TGUs derived for the 0.5‐degree grids and the same land surface parameters. Simulations using the two ELM configurations are compared over the CONUS domain, regional levels, and at observational sites (e.g., SNOTEL). The CONUS‐level results suggest that D ELM simulates more snowfall and snow water equivalent (SWE), higher runoff, and less ET during spring and summer. Regional‐level results suggest more pronounced impacts of downscaling over regions dominated by higher elevation TGUs and regions with maximum precipitation occurring during cool seasons. Results at the SNOTEL sites suggest that D ELM has superior capability of reproducing the observed SWE at 83% of the sites, with more pronounced performance over topographically heterogeneous TGUs with their maximum precipitation occurring during cool seasons. The results highlight the importance of improving representation of small‐scale surface heterogeneity in ESMs and motivate future research to understand their effects on land‐atmosphere interactions, streamflow, and water resources management over mountainous regions.

Examination of Surface Hardness and Roughness of AISI 1050 Steel Material in Milling Based on Surface Processing Conditions

It is known that material hardness and surface conditions have a significant impact on the operating life of machine elements working with each other. In this study, Surface roughness values obtained depending on processing conditions and hardness changes on the machined surfaces during milling of AISI 1050 steel were examined. In experimental studies, ideal machining conditions were determined by taking into account surface roughness values and hardness changes using the Taguchi L18 experimental design method. In all experiments, it was observed that the lowest surface hardness was achieved under dry conditions when 6500 1/min speed, 4000 mm/min feed rate, and 0.4 mm cutting depth values were applied. When the speed increased from 5500 1/min to 6000 1/min and the feed rate increased from 4500 mm/min to 5000 mm/min, improvements in surface quality were observed in both machining conditions. In conclusion; In experiments where coolant was applied at high cutting speeds, it was determined that surface hardness and surface roughness values were higher than in dry machining conditions.

Spatially Variable Ripple and Groove Formation on Gallium Arsenide Using Linear, Radial, and Azimuthal Polarizations of Laser Beam

We demonstrated the linear, radial, and annular ripple formation on the surface of GaAs. The formation of linear ripples was optimized by the number of shots and the fluence of 30 ps, 532 nm pulses. The radial and annular nanoripples were produced under the ablation using doughnut-like beams possessing azimuthal and radial polarizations, respectively. We compare the ripples and grooves formed by a linearly polarized Gaussian beam relative to an annular vector beam. The joint overlap of sub-wavelength grooves with ripples formed by azimuthally and radially polarized beams was reported. The conditions under which the shape of radial and ring-like nano- or micro-relief on the GaAs surface can be modified by modulating the polarization of laser pulse were determined. The resultant surface processing of GaAs using a laser beam with different polarization modes is useful for exploring valuable insights and benefits in different applications.