Search Results (61)

A remote analysis of coastal sedimentation in northern KwaZulu-Natal (KZN), South Africa, describes how summer runoff and winter wave-action operate within a highly variable climate. Despite rising sea levels, the sediment flux can sustain beaches under certain conditions. Daily satellite red-band reflectivity and ocean–atmosphere reanalysis datasets were studied over the period of 2018–2025. Statistical results indicate that streamflow discharges are spread northward by oblique wave-driven currents. Sediment concentrations peak during late winter (>1 mg/L, May–October) when deep turbulent mixing (>40 m) mobilizes sand from the seabed. A case study from September 2021 revealed that ridging high-pressure/cut-off low weather patterns can simultaneously increase streamflow, wave energy, and wind power, creating a surf-zone sediment conveyor along the coast of northern KZN. Long-term climate diagnostics from 1981 to 2025 reveal upward trends in coastal runoff, vegetation, and turbidity (0.29 σ/yr) that point to an increasingly vigorous water cycle. The warming of the southeast Atlantic intensifies the sub-tropical upper-level westerlies and late winter storms over southeast Africa. These processes occur in 5–8 year cycles and drive shoreline advance and retreat, from accretion ~1 T/m and storm surge inundations up to 5.5 m. Using Digital Earth, it was noted that ~1/4 of beaches around Africa are gaining sediment while ~1/3 are eroding. Although remote information could not close the sediment budget, realistic estimates of long-shore transport in the surf-zone (>10⁴ kg/yr/m) and on the beach (>10³ kg/yr/m) were calculated. These provide an emerging explanation for the resilience of northern KZN beaches, as sea levels rise at a rate of 0.6 cm/yr. Full article

Ti(C,N)-based cermet turning inserts with two distinct chip breaker groove structures were employed to investigate the influence of chip breaker geometry on cutting performance. Chip removal performance and wear resistance of the inserts were evaluated according to chip morphology. The results reveal that, compared with inserts with the V-type groove, those with the SF-type groove exhibit superior chip removal capability and enhanced flank wear resistance. Based on two key parameters of the equivalent groove width and initial chip curl radius, an oblique cutting model was proposed for turning inserts with three-dimensionally complex grooves. The model incorporates the coupled effects of chip breaker geometry, workpiece material properties, inserts material properties and cutting process parameters. By controlling chip morphology, the proposed model effectively realizes the improvement and rational optimization of cutting performance, providing a theoretical basis for the design and optimization of complex groove turning inserts. Full article

Background: Reverse-oblique femoral fractures are regarded as highly unstable and are still associated with high complication and failure rates. A new classification system is said to facilitate risk assessment and decision-making. Methods: Over ten years, 7804 patients with per/subtrochanteric fractures were screened in this retrospective analysis. A total of 552 patients with a reverse-oblique fracture pattern were included. The fractures were classified according to the new classification system. The choice of implants, complication rates, revision surgery, and time of surgery were recorded. Radiological outcome parameters and dislocation were measured. Results: For the classification, a good intra-rater reliability (r = 0.77) and inter-rater reliability (k = 0.64) were calculated. The complication rate was overall 19% (n = 105). More than 60% of complications needed revision surgery. The most common complications were cut-out and implant failure (3%); only Parker’s ratio, as a radiological parameter, had prognostic value. Malreduction had a negative impact on mal- or non-unions (p < 0.01), and a trend towards higher overall complications (p = 0.52). Prolonged time of surgery increased the overall complication rate (r = 0.2, p < 0.001). The same was found after open reduction (p = 0.005, OR 2.00). The use of cerclage wires had no positive or negative effects. The use of short or long implants did not influence the outcome. Conclusions: Reverse-oblique femoral fractures are associated with a high complication rate. Short implants can be safely used in cases without severe dislocation if a sufficient working length is considered. Anatomical reduction benefits the outcome as long as it can be performed closed. The classification system presents good inter- and intra-rater reliability. Full article

This study examined muscle coordination during cutting movements in athletes with a history of groin pain. A total of 15 athletes who had experienced groin pain in the past two years (GP) and 14 healthy controls (CON) participated. Electromyography (EMG) and ground reaction force (GRF) data were collected, and EMG was analyzed using non-negative matrix factorization to extract muscle synergies. Three synergies were identified in both groups: Synergy 1 (landing), Synergy 2 (deceleration), and Synergy 3 (acceleration). No group differences were observed in GRF. However, compared with the CON, the GP demonstrated a 58.1% greater contribution of the latissimus dorsi and a 31.5% greater contribution of the erector spinae (SES) in Synergy 1, suggesting excessive trunk involvement during landing. In Synergy 2, SES contribution was 97.0% lower in the GP. In Synergy 3, the external oblique contribution decreased by 118.4%, while rectus abdominis contribution increased by 54.3%. These muscles are critical for pelvic stability, and their altered contributions indicate disrupted neuromuscular coordination in athletes with GP. Full article

With the deepening implementation of the coordinated development strategy for energy exploitation and ecological conservation, green coal mining technology has become a critical pathway to achieve balanced resource development and environmental protection. This study investigates the stress field evolution and dynamic fracture propagation mechanisms in overlying strata during shallow coal seam mining in the Shenfu mining area. By employing a multidisciplinary approach combining triaxial compression tests (0–15 MPa confining pressure), scanning electron microscopy (SEM) microstructural characterization, elastoplastic theoretical modeling, and FLAC3D numerical simulations, the synergistic failure mechanisms of overlying strata were systematically revealed. Gradient-controlled triaxial tests demonstrated significant variations in stress-strain responses across lithological types. Notably, Class IV sandstone exhibited exceptional uniaxial compressive strength of 106.7 MPa under zero confining pressure, surpassing the average strength of Class I–III sandstones (86.2 MPa) by 23.6%, attributable to its highly compacted grain structure. A nonlinear regression-derived linear strengthening model quantified that each 1 MPa increase in confining pressure enhanced axial peak stress by 4.2%. SEM microstructural analysis established critical linkages between microcrack networks/grain-boundary slippage at the mesoscale and macroscopic brittle failure patterns. Numerical simulations demonstrated that strata failure manifests as tensile-shear composite fractures, with lateral crack propagation inducing bed separation spaces. The stress field exhibited spatiotemporal heterogeneity, with maximum principal stress concentrating near the initial mining cut during early excavation. Fractures propagated obliquely at angles of 55–65° to the horizontal plane in an ‘inverted V’ pattern from the goaf boundaries, extending vertically 12–18 m before transitioning to the bent zone, ultimately forming a characteristic three-zone structure. Experimental and simulated vertical stress distributions showed minimal deviation (≤2.8%), confirming constitutive model reliability. This research quantitatively characterizes the spatiotemporal synergy of strata failure mechanisms in ecologically vulnerable northwestern China, proposing a confining pressure-effect quantification model for support parameter optimization. The revealed fracture dynamics provide critical insights for determining ecological restoration timelines, while establishing a novel theoretical framework for optimizing green mining systems and mitigating ecological damage in the Shenfu mining area. Full article

Manufacturing in modern industrial sectors involves the machining of components where the undeformed chip thickness inevitably decreases to values comparable to the tool edge radius. Under such conditions, the ploughing effect between the workpiece and the tool becomes dominant, followed by the noticeable formation of a stagnation zone. This paper presents research focused on the analysis of the cutting process for small cross-sections of the removed layers, based on cutting force components. This study investigated the machining of two titanium alloy grades—Ti Grade 5 (Ti-6Al-4V) and Ti Grade 2—with the main focus on process stability. A material separation model was analyzed to demonstrate the mechanism of material flow within the cross-section of the machined layer. It was found that the material has a limited ability to flow sideways at the boundary of the chip thickness, thus determining the probable size of the stagnation zone in front of the cutting edge. Orthogonal cutting experiments enabled the determination of the minimum chip thickness coefficient for constant temperature conditions, independent of the tool edge radius, as $h_{min0}=$0.313. In oblique cutting tests, the sensitivity of thin-layer machining was demonstrated for the determined values of minimum undeformed chip thickness. By applying the 0–1 test for chaos, the measurement time (parameter $T·dt$) was determined for both titanium alloys to determine the range of observable chaotic behavior. The analyses confirmed that Ti Grade 2 enters chaotic dynamics much more rapidly than Ti Grade 5 and displays local cutting instabilities independent of the uncut chip thickness. Full article

Double-suction centrifugal pumps are extensively employed in industrial applications owing to their high efficiency, low vibration, superior cavitation resistance, and operational durability. This study analyzes how impeller oblique cutting angles (0°, 6°, 9°, 12°) affect a double-suction pump at a fixed 4% trimming ratio and constant average post-trim diameter. Numerical simulations and tests reveal that under low-flow (0.7Q_d) and design-flow conditions, the flat-cut (0°) minimizes reflux ratio and maximizes efficiency by aligning blade outlet flow with the mainstream. Increasing oblique cutting angles disrupts this alignment, elevating reflux and reducing efficiency. Conversely, at high flow (1.3Q_d), the 12° bevel optimizes outlet flow, achieving peak efficiency. Pressure pulsation at the volute tongue (P11) peaks at the blade-passing frequency, with amplitudes significantly higher for 9°/12° bevels than for 0°/6°. The flat-cut suppresses wake vortices and static–rotor interaction, but oblique cutting angle choice critically influences shaft-frequency pulsation. Entropy analysis identifies the volute as the primary loss source. Larger oblique cutting angles intensify wall effects, increasing total entropy; pump chamber losses rise most sharply due to worsened outlet velocity non-uniformity and turbulent dissipation. The flat-cut yields minimal entropy at Q_d. These findings provide a basis for tailoring impeller trimming to specific operational requirements. Furthermore, the systematic analysis provides critical guidance for impeller trimming strategies in other double-suction pumps and pumps as turbines in micro hydropower plants. Full article

As vital material carriers of human civilization, earthen sites are experiencing continuous surface deterioration under the combined effects of weathering and anthropogenic damage. Traditional surface conservation techniques, due to their poor compatibility and limited reversibility, struggle to address the compound challenges of micro-scale degradation and macro-scale deformation. With the deep integration of digital twin technology, spatial information technologies, intelligent systems, and sustainable concepts, earthen site surface conservation technologies are transitioning from single-point applications to multidimensional integration. However, challenges remain in terms of the insufficient systematization of technology integration and the absence of a comprehensive interdisciplinary theoretical framework. Based on the dual-core databases of Web of Science and Scopus, this study systematically reviews the technological evolution of surface conservation for earthen sites between 2000 and 2025. CiteSpace 6.2 R4 and VOSviewer 1.6 were used for bibliometric visualization analysis, which was innovatively combined with manual close reading of the key literature and GPT-assisted semantic mining (error rate < 5%) to efficiently identify core research themes and infer deeper trends. The results reveal the following: (1) technological evolution follows a three-stage trajectory—from early point-based monitoring technologies, such as remote sensing (RS) and the Global Positioning System (GPS), to spatial modeling technologies, such as light detection and ranging (LiDAR) and geographic information systems (GIS), and, finally, to today’s integrated intelligent monitoring systems based on multi-source fusion; (2) the key surface technology system comprises GIS-based spatial data management, high-precision modeling via LiDAR, 3D reconstruction using oblique photogrammetry, and building information modeling (BIM) for structural protection, while cutting-edge areas focus on digital twin (DT) and the Internet of Things (IoT) for intelligent monitoring, augmented reality (AR) for immersive visualization, and blockchain technologies for digital authentication; (3) future research is expected to integrate big data and cloud computing to enable multidimensional prediction of surface deterioration, while virtual reality (VR) will overcome spatial–temporal limitations and push conservation paradigms toward automation, intelligence, and sustainability. This study, grounded in the technological evolution of surface protection for earthen sites, constructs a triadic framework of “intelligent monitoring–technological integration–collaborative application,” revealing the integration needs between DT and VR for surface technologies. It provides methodological support for addressing current technical bottlenecks and lays the foundation for dynamic surface protection, solution optimization, and interdisciplinary collaboration. Full article

This paper reports an investigation of the thermomechanical behavior at the interface of GFRP/Al composite stacks when the stacking arrangement varies. A temperature-coupled damage approach was developed to simulate thermal energy transfer and damage propagation at metallic-to-composite interface. The proposed model was then implemented into ABAQUS/Explicit finite element code using user-defined subroutine VUMAT finely imbricated with VDFLUX. Unlike to previous models, oblique cutting configuration (OCC) involving double-inclination of the tool was proposed to simulate finely the material removal process owing to drill action. Drilling trials involving the cutting speed and the stacking arrangement were conducted to support the proposed approach. The predictions revealed that increasing the spindle speed significantly impacts the temperature distribution and subsurface thermal damage. An exponential temperature law was derived for predicting temperature variation with the cutting speed and identifying thermal saturation at the interface. The sensitivity of the composite behavior to the stacking arrangement (GFRP → Al vs. Al → GFRP) was well highlighted. The results indicated that attacking the structure from the GFRP side results in higher interfacial temperatures due to GFRP’s lower thermal conductivity. These findings contribute to understanding the heat-affected zone in GFRP, and, hence, provide guidance to minimize thermal damage in industrial drilling of the hybrid stacks. Full article

Wrist kinematics can provide insight into the development of repetitive strain injuries, which is important particularly in workplace environments. The emergence of markerless motion capture is beginning to revolutionize kinematic assessment such that it can be conducted outside of the laboratory. The purpose of this work was to apply open-source software (OSS) and machine learning (ML) by using DeepLabCut (OSS) to determine anatomical landmark locations and a variety of regression algorithms and neural networks to predict wrist angles. Sixteen participants completed a series of flexion–extension (FE) and radial–ulnar (RUD) range-of-motion (ROM) trials that were captured using a 13-camera VICON optical motion capture system (i.e., the gold standard), as well as 4 GoPro video cameras. DeepLabCut (version 2.3.3) was used to generate a 2D dataset of anatomical landmark coordinates from video obtained from one obliquely oriented GoPro video camera. Anipose (version 1.0.1) was used to generate a 3D dataset from video obtained from four GoPro cameras. Anipose and various ML algorithms were used to determine RUD and FE wrist angles. The algorithms were trained and tested using a 75%:25% data split with four folds for the 2D and 3D datasets. Of the seven ML techniques applied, deep neural networks resulted in the highest prediction accuracy (5.5) for both the 2D and 3D datasets. This was substantially higher than the wrist angle prediction accuracy provided by Anipose ($FE-99$; $RUD-25.2$). We found that, excluding cubic regression, all other studied algorithms exhibited reasonable performance that was similar to that reported by previous authors, showing that it is indeed possible to predict wrist kinematics using a low-cost motion capture system. In agreement with past research, the increased MAE for FE is thought to be due to a larger ROM. Full article

To address the mismatch between materials and operational speed in mine scraper conveyors under time-varying load conditions, this paper proposes a methodology for the regulation of speed based on the quantity of coal transported by the scraper conveyor. Furthermore, a vector control strategy for permanent magnet synchronous motors (PMSMs) is presented, underpinned by a global fast terminal sliding mode controller. Firstly, a calculation model for the real-time coal volume of the scraper conveyor was developed based on the double-end oblique cutting coal mining technology in fully mechanized mining operations. This model takes into account the operational condition of the shearer and the scraper conveyor. In addition, a graded speed regulation control method was introduced. Secondly, a global fast terminal controller was developed by integrating the features of linear and terminal sliding mode surfaces. An enhanced sliding mode vector control strategy for the permanent magnet drive motor of the scraper conveyor was subsequently proposed. Finally, a simulation and ground test were subsequently performed on the PMSM experimental bench and SGZ2×1200 scraper conveyor to validate the proposed control strategy. The results indicated that the proposed control strategy not only diminished the overshoot of the rotational speed and decreased the dynamic response time but also improved the anti-interference capabilities of the PMSM relative to the original PI control. Moreover, the ground test validated the feasibility of the suggested speed regulation method. Full article

Since one of the effective methods for producing the form-cutting tools used in the form-turning process involves utilizing a wire cut machine, the effect of the geometric characteristics of the form contour on reducing the negative effects of the recast layer was investigated in this research. The basic assumption of the components for each type of profile form is based on a combination of four modes, i.e., concave arc, convex arc, flat surface, and oblique surface. Based on this, samples were fabricated as cutting tools with three different radii: a convex arc, a concave arc, and a flat surface. During the wire electrical discharge machining (WEDM) operation, one-pass mode was used to create a rough surface, two passes resulted in a semi-finished surface, and three passes resulted in a finished surface. Furthermore, the difference between the surface quality of the recast layer in the two areas above the workpiece or the wire entry point and the bottom area of the workpiece or the wire exit point was studied. Finally, the effect of the direction, size of the curvature and the number of passes in the electric discharge process of the wire on the recast layer was shown, and it was observed that with the increase in the number of passes in WEDM, the thickness of the recast layer was reduced, along with the uniformity of the cutting contour section in the areas close to the cutting region. The entry of the wire was greater than that in the areas near the exit of the wire. Full article

During deicing operations on transmission lines, the cutting forces generated by the milling cutter of a deicing robot exert significant reaction forces on the robot body. Excessive cutting forces can compromise the robot’s locomotion stability and deicing performance. This study introduces an optimization of the traditional straight-plate milling cutter by designing two new types of deicing milling cutters: oblique-cut and straight-cut milling cutters. The effects of cutter geometry, milling speed, and feed rate on cutting forces were systematically investigated using finite element simulations. A deicing test platform was constructed to validate the simulation results. The findings indicate that the cutting force hierarchy among the three designs is as follows: straight-plate > oblique-cut > straight-cut. Notably, the straight-cut milling cutter reduces cutting forces by 16–33% compared with the traditional straight-plate cutter. Furthermore, higher milling speeds and faster feed rates along the transmission line increase cutting forces. These studies provide valuable guidance for optimizing milling cutter designs in deicing robots. Full article

Aiming at the problem of the wheat straw and stubble of the previous crop blocking the opener during the operation of the summer peanut no-tillage seeder under straw incorporation modes, an oblique stubble-cutting and side-throwing anti-blocking device that can simultaneously cut the stubble and throw the straw was designed. The structure and working principle of the device were clarified, and the key structure of the anti-blocking device was designed through theoretical analysis. According to the kinematics analysis of the rotary blade cutting and throwing of the root–soil composite, the key factors affecting the operation quality of the device and the range of values were determined. The quadratic orthogonal rotation combination design test was carried out with the motion inclination angle, bending angle, and advancing velocity as the test factors, and the straw clearance rate, stubble-cutting rate, and operation power consumption as the indexes. The discrete element simulation test was carried out in EDEM. The significance test of the test results was carried out in Design-Expert, and the influence of each factor on the test index and the interaction between the factors were determined. Then the regression model was optimized by multi-objective function, and the optimal parameter combination was obtained as follows: The motion inclination angle was 22°, the bending angle was 58°, and the advance velocity was 7.7 km/h. At this time, the straw clearance rate of the seedling belt was 92.55%, the root stubble-cutting rate was 95%, and the operation power consumption was 1.80 kW. The field test shows that the machine had good passing capacity, the straw clearance rate of the seedling belt was 91.04%, the root stubble-cutting rate was 92.98%, and the operation power consumption of the single group of stubble cutting device was 1.92 kW. The difference between the field test results and the simulation test was less than 6%, which met the local agronomic requirements and proved that the anti-blocking device had good operation quality. Full article

Ice is a common natural phenomenon in cold areas, which plays an important role in the construction of cold areas and the design of artificial ice rinks. To supplement our knowledge of ice mechanics, this paper investigates the mechanical properties of granular snow ice. The factors influencing the flexural strength of granular snow ice are analyzed through a three-point bending test. It is found that flexural strength is affected by strain rate. At low strain rates, flexural strength increases with increasing strain rate, whereas at high strain rates, flexural strength decreases with increasing strain rate. As temperature decreases, the flexural strength value of ice increases, but its brittleness becomes more pronounced, indicating that the strain rate corresponding to the maximum flexural strength is lower. Within the test temperature range, the tough-brittle transition range is from 6.67 × 10⁻⁵ s⁻¹ to 3.11 × 10⁻⁴ s⁻¹. At −5 °C, the strain rate corresponding to the maximum bending strength is 3.11 × 10⁻⁴ s⁻¹, while at −10 °C, it is only 6.67 × 10⁻⁵ s⁻¹. Flexural strength is influenced by crystal structure. At −20 °C, the average flexural strength of granular snow ice is 2.85 MPa, compared to 1.93 MPa for columnar ice at the same temperature. Through observation, we found that there are straight cracks and oblique cracks. The fracture toughness of granular snow ice was investigated by cutting prefabricated cracks at the bottom of the ice beam and employing a three-point bending device. It is found that fracture toughness decreases with increasing strain rate. Temperature also affects granular snow ice. At −15 °C, fracture toughness is 181.60 kPa·m^1/2, but at −6 °C, it decreases to 147.28 kPa·m^1/2. However, at varying temperatures and strain rates, there is no significant difference in the fracture patterns of ice samples, which predominantly develop upward along the prefabricated cracks. Full article