Search Results (25)

To analyze the wear performance induced by rotor–stator rubbing in an aero-engine sealing structure under authentic operating conditions, a transonic rotor system with double bearing is constructed. This system incorporates the disk, shaft, blades, joint bolts, and auxiliary support structure. The system was evaluated in terms of its critical speed, vibration characteristics, component strength under operational conditions, and response characteristics in abnormal extreme scenarios. A ball screw-type feeding system is employed to achieve precise rotor–stator rubbing during rotation by controlling the coating feed. Additionally, a quartz lamp heating system is used to apply thermal loads to coating specimens, and the appropriate heat insulation and cooling measures are implemented. Furthermore, a high-frequency rubbing force test platform is developed to capture the key characteristics caused by rubbing. The test rig can conduct response tests of the system with rotor–stator rubbing and abrasion tests with tip speeds reaching 425 m/s, feed rates ranging from 2 to 2000 μm/s, and heating temperatures up to 1200 °C. Test debugging has confirmed these specifications and successfully executed rubbing tests, which demonstrate stability throughout the process and provide reliable rubbing force test results. This designed test rig and analysis methodology offers valuable insights for developing high-speed rotating machinery. Full article

Pneumatic polishing tools are commonly used in traditional robot mold polishing systems, but they have problems with the stable control of mold surface roughness due to low precision and poor adaptability in polishing force adjustment. The integration of an adaptive hydraulic polishing (AHP) tool and robot system effectively solves the above problems, providing a robust solution for the high-precision polishing of various molds. This study systematically investigates the robotic polishing of NAK80 mold steel using an AHP-equipped robotic platform with 3M abrasive discs of progressively refined grit sizes (P180, P400, P800). Through single-factor experiments and response surface methodology, the effects of polishing force, rotational speed, and feeding speed on surface roughness were quantitatively analyzed. The relationship between surface roughness and the polishing parameters was derived to elucidate the roughness evolution before and after over-polishing. Orthogonal experiments combined with range analysis identified optimal parameter combinations for P180 (20 N polishing force, 5000 RPM rotational speed, and 5 mm·s⁻¹ feeding speed) and P400 abrasives (10 N polishing force, 4000 RPM rotational speed, and 5 mm·s⁻¹ feeding speed), achieving minimum surface roughness values of 0.08 µm and 0.044 µm, respectively. For P800 abrasives, a central composite design was used to develop a roughness prediction model with a ≤7.14% relative error, and the optimal parameters are a 20 N polishing force, a 5000 RPM rotational speed, and a 5 mm·s⁻¹ feeding speed. The sequential application of the optimized parameters across all the grit sizes can reduce the surface roughness from an initial 0.4 µm to a final 0.017 µm, representing a 95.75% improvement in the surface finish. Full article

To address the wear issues faced by the leg components of offshore platforms in harsh marine conditions, a Ni60-WC composite coating was fabricated on the surface of E690 high-strength steel using laser cladding. The microstructure, elemental distribution, microhardness, and tribological properties of the composite coating were characterized and tested using XRD (X-ray diffraction), SEM (scanning electron microscopy), EDS (energy-dispersive spectrometry), a microhardness tester, and a multifunctional tribometer. The study focused on the microstructure and tribological properties of the Ni60-WC composite coating. The results show that the composite coating primarily consists of γ-(Fe, Ni), WC, W2C, M23C6, and M6C phases, with cellular and dendritic structures at the top. WC and W2C, along with M23C6 and M6C, are precipitated from the W and C elements. The average hardness of the composite coating reached 569.5 HV, representing a 103% increase over the substrate hardness. The prepared composite coating exhibited a 32.6% increase in corrosion potential compared to the substrate. Additionally, the corrosion current density was reduced by 62.0%, indicating a significant enhancement in the corrosion resistance of the composite coating. The friction coefficient of the composite coating was reduced by 17.4% compared to the substrate, and wear volume was reduced by 79%, significantly enhancing the tribological performance of the coating due to reduced abrasive wear and fatigue wear. Full article

The automotive industry is currently transforming, primarily due to the rise of electric and hybrid vehicle technologies and the need to reduce vehicle mass and energy losses to decrease consumption, pollution, and raw material usage. Additionally, road surface manufacturers emphasize improving pavement durability and reducing rolling noise. This necessitates precise load condition definitions and drives the need for reliable wheel testing benches. Many current benches use abrasive-coated rollers or synthetic tapes, but devices capable of testing on actual road surfaces are rare. In this work, a novel device for testing tire-pavement interaction is proposed. The system features a cart moving along a closed-track platform, ensuring test repeatability and enabling structural durability tests on uneven surfaces with installed obstacles. The cart is equipped with a cantilever arm capable of supporting either a testing wheel with customizable dimensions and kinematic parameters or a tire integrated with a complete suspension system, moving along a customizable pavement surface. The system includes actuators and sensors for applying vertical loads and adjusting the alignment of the testing wheel (slip angle, camber angle, etc.), allowing the characterization of tire behavior such as wear, fatigue, rolling noise, and rolling resistance. Multibody simulations were performed to evaluate the bench’s feasibility in terms of kinematics, power requirements, and structural loads. Results confirmed how this novel test bench represents a promising advancement in tire testing capabilities, enabling comprehensive studies on tire performance, noise reduction, and the structural dynamics of vehicle subsystems. Full article

In the process of landscaping or afforestation in challenging terrain, in order to improve the survival rate of transplanted seedlings, it is necessary to transplant seedlings with a mother soil ball attached. During transportation, the soil ball at the root of the seedlings is very susceptible to breakage due to compression, bumps, and collisions. In order to ensure the integrity of the soil ball of the transplanted seedlings and improve the survival rate of seedlings, a method of chemically enhancing the soil surface strength was employed. Specifically, a polymer-based soil consolidating agent was used to solidify the root balls of the seedlings. To examine the abrasion resistance performance of the soil balls formed by consolidating the surface with polymer adhesive during the transportation process, we utilized a polymer-based consolidating agent to prepare test soil columns and developed a method to simulate the damage resistance performance of seedling root balls during transportation using these soil columns. The method primarily encompasses two aspects of testing: compressive strength testing of the consolidated soil columns and resistance to transportation vibration testing. The first method for testing the resistance to transportation vibration of the consolidated soil columns is a combination test that includes three sets of tests: highway truck transportation vibration testing, combined wheel vehicle transportation vibration testing, and impact testing. Although the method is cumbersome, testing is more accurate. The second method for testing the resistance to transportation vibration of the consolidated soil columns involves simultaneously testing multiple consolidated soil columns using a simulated transportation vibration test platform. The testing method is concise and efficient, and the test results are more intuitive. The combined assessment of the resistance to transportation vibration and compressive strength testing of the consolidated soil columns allows for a comprehensive evaluation of the soil columns’ resistance to damage during transportation. This study mainly provides a quick and effective method for detecting the damage resistance of consolidated soil columns/balls during transportation, providing technical support for the application of polymer-based consolidation agents in the field of seedling transplantation. Full article

In order to achieve the high-precision and high-efficiency machining of micro-channels for hard and brittle materials, the authors innovatively proposed a new technology called template-based electrophoretically assisted micro-ultrasonic machining (TBEPAMUSM). This technology transfers the micro-channel shape punch-pin to the workpiece material through micro-ultrasonic machining to form a micro-channel. At the same time, it uses the electrophoretic properties of ultra-fine abrasive particles to ensure the existence of abrasive particles in the machining area by applying a DC electric field. According to the new technology machining principle, a machine tool of TBEPAMUSM was designed and developed. The machine tool hardware adopts a C-shaped structure, including a marble platform, an ultrasonic vibration system, a micro three-dimensional motion platform, a working fluid tank, and a pressure sensor. The machine tool intelligent control system is developed based on LabVIEW, including the initialization module, fast positioning module, constant force tool setting module, constant force control machining module, and real-time coordinate display module. Micro-channels with different structures are machined on single-crystal silicon and soda-lime glass using the designed machine tool and the developed control system. The results show that: when electrophoresis assistance is applied in machining, the edge chipping phenomenon of the micro-channel is significantly reduced, the surface roughness is reduced by about 20%, and the machining efficiency is increased by about 4%. Full article

While many current and potential uses of the Israeli Mediterranean Sea have clearly defined the economic value and apparent benefits to various stakeholders (e.g., energy and raw materials extraction and maritime traffic), the benefits of these local marine ecosystems are still severely underexplored and are not manifested in economic terms. Coupled with ongoing environmental deterioration such as overfishing, climate change, and biological invasion, the need for performing monetary valuations of the benefits derived from this ecosystem is clearly evident. In this study, we evaluated three marine and coastal ecosystem services, namely, food provisioning, wastewater treatment, and coastal protection, in order to better quantify and map their importance to society. Food provisioning was inspected through the fishing sector, and its benefits were analyzed using the bioeconomic model. The results recommend a reduction in fishing efforts to increase overall biomass levels of both local and invasive fish species. However, this may lead to an economic loss in fishery profits due to reduced catch levels. The economic valuation of wastewater treatment as an ecosystem service hint at possible thresholds governed by effluent volumes and environmental conditions, whereby exceedance of Good Environmental Status (GES) standards may lead to a reduction of ~25% in the potential benefit of this ecosystem service. Finally, this study proposes an engineering restoration solution for compromised intertidal abrasion platforms, with estimated costs and potential benefits for the conservation of at-risk areas. The annual economic value of this ecosystem service is NIS 65–209 million (EUR 16.2–52.2 million). Full article

Background: To evaluate the effect of different experimental staining procedures on color stability and translucency of a nano-hybrid resin-based composite (RBC). Methods: Forty-eight cylindrical-shaped specimens (10 × 2 mm) were prepared with a nano-hybrid RBC (Clearfil Majesty ES-2) and randomly divided in four groups according to the experimental staining procedure: G1) static immersion in a staining solution (coffee) (44 ± 1 °C); G2) staining cycling between coffee (44 ± 1°C) and distilled water (37 ± 1°C) with an experimental staining machine based on Arduino, an Open Source hardware development platform; G3) staining cycles as in G2 + brushing with a low abrasive toothpaste (Relative Dentin Abrasion RDA = 30) (Elmex Sensitive Professional); G4) staining cycles as in G3, with brushing performed with a very strong abrasive toothpaste (RDA = 90) (Lacult Active). Color parameters were recorded at the baseline (T0) after staining procedures (T1) and repolishing (T2) using a spectrophotometer. Color change (∆E00) and translucency (TP, CR) were evaluated. Data were statistically analyzed (p < 0.05). Results: For ∆E00 after staining, Group 1 showed the highest color change and Group 3 the lowest. All groups were significantly different (p < 0.001) except for Group 2 vs. Group 4; after repolishing, Group 1 was significantly higher than Group 3 (p < 0.001), Group 2 (p < 0.001), and Group 4 (p = 0.003); Group 2 was higher than Group 3 (p < 0.001). For TP variable, after staining procedures, Group 2 was significantly higher than all other groups (p < 0.001), and Group 1 was significantly higher than Group 3 (p < 0.001) and Group 4 (p = 0.007). After repolishing, Group 4 was significantly lower than Group 3 (p = 0.008) and Group 2 (p = 0.027). Repolishing procedure significantly reduced color parameters. Conclusions: The investigated staining procedure induced significant differences in color stability and translucency. The use of a very strong abrasive toothpaste (RDA = 90) induced higher color change than a low abrasive one (RDA = 30). Repolishing procedures are able to partially reduce color change induced by artificial staining procedures. Full article

In the last 100 years, the population of the land of Israel has increased dramatically, accompanied by a very intense and accelerated economic and industrial growth. The objective of the present review is to reveal how these major changes have affected the Mediterranean marine and coastal environment. The present review analyzes the global, regional, and local factors and processes that cause substantial environmental changes affecting a variety of marine habitats and taxa. During the past century these include: (1) seawater warming that enhances the considerable introduction and establishment of non-indigenous tropical, i.e., Lessepsian, species; (2) overfishing of native biota that seems to contribute to this process; (3) sea-level rise, associated with climate change, which may threaten the sensitive intertidal abrasion platforms; (4) chemical, noise, and light pollution and marine debris; (5) massive sand mining from the beaches, which caused severe erosion in many coastal sections and was banned in Israel in 1964; (6) extensive dredging in the sea, mainly related to the construction and development of large ports, which can be detrimental for the benthic biota, especially in rocky substrates; and (7) marine structures (harbors, marinas, detached breakwaters) that interfere with the natural pattern of sand transport along the coast and cause morphological changes (sand erosion or accumulation) on nearby beaches and the seabed. Israel’s coast is presently characterized by intense anthropogenic activity and many stakeholders with considerable conflicts between them and with the marine ecosystem. A few environmental impacts have ceased, and others have been reduced considerably, but the extent of many additional types have increased significantly, and new impacts have appeared in recent years. Some environmental impacts are beyond our control, and others can be reduced by proper management, but it is predicted that certain major environmental impacts, such as Lessepsian migration, will continue in the future at enhanced rates. Full article

We used wind-transported particle collectors of our own inhouse design to monitor the sediment flow in a citrus orchard in Southeast Spain. These collectors, which can differentiate sediment collected by direction of origin, are very efficient, economical, and easy to manufacture from thermoplastic filaments with an industrial 3D printer. Data were acquired from six vaned masts, each with four collectors at different heights, and on one of those masts, the collectors included load cells with one end attached to the collector floor and the other end to each oriented compartment in the collectors. The load cell values were interpreted in real time by a microcontroller and amplifier. The remote monitoring system was developed with an internet of things (IoT) platform. The results showed clear predominance of winds from the Northeast after dark, and from the South during the middle of the day. After analyzing the sediment transport rates and their balance, we found that those being deposited in the citrus orchard from the Northeast had a higher carbonate content (mainly calcite), which had an aggregating and therefore stabilizing effect against wind erosion of the soil. Furthermore, significant amounts of highly adhesive phyllosilicates were captured by the upper traps, which also contributed to reducing soil wind erodibility because of their adhesiveness. However, the sediments from the South with much more total transported mass were not deposited in the study zone, but leeward of it and contained a large amount of quartz, promoting abrasion and increasing wind erodibility of the soil. Full article

The coil structure of the inductive wear debris sensor plays a significant role in the effect of wear debris detection. According to the characteristics of LC parallel resonance, the capacitor and coil are connected in parallel to make sensor coils in the LC parallel resonance state, which is beneficial to improve the ability to detect wear particles. In this paper, the mathematical model of output-induced electromotance of the detection coil is established to analyze the influence of the structure on the detection sensitivity and enhance the sensor’s current rate of change to the disturbance magnetic field, which is essential to resist noise interference. Based on the coherent demodulation principle, the AD630 lock-in amplifier is applied to the test platform to amplify and identify weak signals. In addition, experiments are designed to test the output signals of debris under the condition of different original output voltages of the sensor with a parallel structure. Meanwhile, the near-resonance state of the detection coil with LC parallel circuit is tested by output signal information. Results show that the sensor detection sensitivity will be effectively improved with the LC parallel coil structure. For the sensor structure parameters designed in this paper, the optimal raw output amplification voltage for abrasive particle detection is 4.49 V. The detection performance of ferromagnetic particles and non-ferromagnetic particles is tested under this condition, realizing the detection ability of 103.33 μm ferromagnetic abrasive particles and 320.74 μm non-ferromagnetic abrasive particles. Full article

Since the origin of the carbonate platform concept, the reconstruction of the geometry and the evolution of the margin has been an intriguing topic. The Latium-Abruzzi platform is one of the largest shallow water domains of the Central Apennines, however, the reconstruction of the geometry and evolution of its margin has been classically problematic because the latter has been erased by the out-of-sequence Olevano-Antrodoco thrust system. The investigated area is placed in the Prenestini Mountains, the southernmost portion of the Sabina Domain, where a Cretaceous to Neogene carbonate succession, ascribed the Latium-Abruzzi platform margin, crops out. Stratigraphic and facies analyses showed a Late Cretaceous extensional stage that produced two main fault-block platforms, respectively, South Eastern Prenestini and South Western Prenestini platforms, developed westward of the large Latium-Abruzzi Platform domain. In these platforms, during the Paleocene–Eocene interval, pelagite deposition coincides with the main relative sea-level rise. Instead, during the following falling stage, the seafloor, consisting of the Cretaceous carbonate, was in the wave abrasion zone and the pelagic carbonate mud was swept away or trapped in local depressions or fractures (neptunian dykes), whereas the coarse sediment produced by the erosion of indented and fractured substrate formed polygenic conglomerate accumulation on the Cretaceuos carbonate platform substrate. Successively, an isolated homoclinal ramp, the Guadagnolo Fm, Aquitanian to Serravallian in age, developed on the drowned fault-block platforms, suggesting that during Neogene the articulation of the substrate of the two fault-block platforms had to be limited to host the bioclastic sedimentation of the Guadagnolo Fm and to allow the development of a carbonate ramp depositional profile. Full article

Recent advances in technology and refinement of available computational resources paved the way for the extensive use of computers to model and simulate complex real-world problems difficult to solve analytically. The appeal of simulations lies in the ability to predict the significance of a change to the system under study. The simulated results can be of great benefit in predicting various behaviors, such as the wind pattern in a particular region, the ability of a material to withstand a dynamic load, or even the behavior of a workpiece under a particular type of machining. This paper deals with the mathematical modeling and simulation techniques used in abrasive-based machining processes such as abrasive flow machining (AFM), magnetic-based finishing processes, i.e., magnetic abrasive finishing (MAF) process, magnetorheological finishing (MRF) process, and ball-end type magnetorheological finishing process (BEMRF). The paper also aims to highlight the advances and obstacles associated with these techniques and their applications in flow machining. This study contributes the better understanding by examining the available modeling and simulation techniques such as Molecular Dynamic Simulation (MDS), Computational Fluid Dynamics (CFD), Finite Element Method (FEM), Discrete Element Method (DEM), Multivariable Regression Analysis (MVRA), Artificial Neural Network (ANN), Response Surface Analysis (RSA), Stochastic Modeling and Simulation by Data Dependent System (DDS). Among these methods, CFD and FEM can be performed with the available commercial software, while DEM and MDS performed using the computer programming-based platform, i.e., “LAMMPS Molecular Dynamics Simulator,” or C, C++, or Python programming, and these methods seem more promising techniques for modeling and simulation of loose abrasive-based machining processes. The other four methods (MVRA, ANN, RSA, and DDS) are experimental and based on statistical approaches that can be used for mathematical modeling of loose abrasive-based machining processes. Additionally, it suggests areas for further investigation and offers a priceless bibliography of earlier studies on the modeling and simulation techniques for abrasive-based machining processes. Researchers studying mathematical modeling of various micro- and nanofinishing techniques for different applications may find this review article to be of great help. Full article

Magnetic bearings have a series of excellent qualities, such as no friction and abrasions, high speed, high accuracy, and so on, which have fundamentally innovated traditional forms of support. In order to solve the problems of the large volume, low power density and high coupling coefficient of three-pole magnetic bearings, a six-pole AC active magnetic bearing is designed. Firstly, the basic structure and working principle of a two-degree-of-freedom (2-DOF) six-pole active magnetic bearing is introduced. Secondly, a suspension force modeling method of a 2-DOF AC active magnetic bearing based on the Maxwell tensor method is proposed, and the mathematical model of active magnetic bearing is established. Considering the fact that AC active magnetic bearing is essentially a nonlinear system, a fuzzy active disturbance rejection control (ADRC) method is designed based on fuzzy control and ADRC theory. Its control algorithm and control block diagram are given, and the fuzzy ADRC method is simulated and verified. Finally, the control block diagram of an experimental system based on the 2-DOF six-pole active magnetic bearing is given, and the experimental platform is constructed. The experimental results show that the mechanical and magnetic circuit structure of the 2-DOF six-pole active magnetic bearing is reasonable, and the fuzzy controllers can realize the stable suspension of the rotor. Full article

Skin-barrier restoration following abrasive trauma is facilitated by mediator release from skin-resident cells, a process that has been investigated primarily in mice or simplified human systems with previous studies focusing on a limited number of biomarkers. Here, we demonstrate how early events caused by skin-barrier disruption can be studied in a human ex vivo skin model. Ten relevant biomarkers were recovered from the interstitial fluid by skin microdialysis with subsequent sample analysis using a multiplex platform. As a control, the biomarker profiles obtained from microdialysis sampling were compared to profiles of skin biopsy homogenates. We found that nine (GM-CSF, CXCL1/GROα, CXCL8/IL-8 CXCL10/IP-10, IL-1α, IL-6, MIF, TNF-α, and VEGF) of the 10 biomarkers were significantly upregulated in response to abrasive trauma. Only dialysate levels of CCL27/CTACK were unaffected by skin abrasion. Biomarker levels in the homogenates corresponded to dialysate levels for CCL27/CTACK, CXCL1/GROα, CXCL8/IL-8, and IL-6. However, IL-1α showed an inverse trend in response to trauma, and biopsy levels of MIF were unchanged. GM-CSF, CXCL10/IP-10, TNF-α, and VEGF were not detected in the biopsy homogenates. Our results suggest that the human ex vivo skin model is a reliable approach to study early events after disruption of the skin barrier. Full article