Search Results (216)

Aiming at the problems of complex process flow, high energy consumption, and difficult emulsification in the preparation of traditional SBS-modified emulsified asphalt, a preparation method of fast-melting SBS (referred to as SBS-T) modified emulsified asphalt based on the integration of modification and emulsification is proposed. Based on surface free energy theory, the contact angles between three rapid-melting SBS-modified emulsified asphalts with different dosages and three probe liquids (deionized water, glycerol, and formamide) were measured using the sessile drop method. The adhesion performance of the asphalt–aggregate system was studied by means of micromechanical methods. The evaluation indicators such as the cohesion work of the emulsified asphalt, the adhesion work of asphalt–aggregate, the spalling work, and the energy ratio were analyzed. The results show that the SBS-T modifier can significantly improve the thermodynamic properties of emulsified asphalt. With increasing modifier content, the SBS-T-modified emulsified asphalt demonstrated enhanced cohesive work, improved asphalt–aggregate adhesive work, and increased energy ratio, while showing reduced stripping work. At equivalent dosage levels, the SBS-T-modified emulsified asphalt demonstrates a slight improvement in adhesion performance to aggregates compared to conventional SBS-modified emulsified asphalt. The SBS-T emulsified modified asphalt provides an effective technical solution for the preventive maintenance of asphalt pavements. Full article

Pesticide residues pose risks to the environment and human health. Little is known about how tillage and straw management affect herbicide behavior in soil. This study investigated the effects of different tillage practices under varying straw incorporation scenarios on the degradation of five commonly used herbicides in a long-term experimental field located in the maize belt of Siping, Jilin Province. Post-harvest soil samples were analyzed for residual herbicide concentrations and basic soil physicochemical properties. A human health risk assessment was conducted, and a controlled incubation experiment was carried out to evaluate herbicide degradation dynamics under three management systems: straw incorporation with traditional rotary tillage (ST), straw incorporation with strip tillage (SS), and no-till without straw (CK). Residual concentrations of atrazine ranged from not detected (ND) to 21.10 μg/kg (mean: 5.28 μg/kg), while acetochlor showed the highest variability (2.29–120.61 μg/kg, mean: 25.26 μg/kg). Alachlor levels were much lower (ND–5.71 μg/kg, mean: 0.34 μg/kg), and neither nicosulfuron nor mesotrione was detected. Soil organic matter (17.6–20.89 g/kg) positively correlated with available potassium and acetochlor residues. Health risk assessments indicated negligible non-cancer risks for both adults and children via ingestion, dermal contact, and inhalation. The results demonstrate that tillage methods significantly influence herbicide degradation kinetics, thereby affecting environmental persistence and ecological risks. Integrating straw with ST or SS enhanced the dissipation of atrazine and mesotrione, suggesting their potential as effective residue mitigation strategies. This study highlights the importance of tailoring tillage and straw management practices to pesticide type for optimizing herbicide fate and promoting sustainable agroecosystem management. Full article

The no-insulation (NI) technique improves the stability and defect-tolerance of high-temperature superconducting (HTS) coils by enabling current redistribution, thereby reducing the risk of quenching. NI–HTS coils are widely applied in DC systems such as high-field magnets and superconducting field coils for electric machines. However, the presence of turn-to-turn contact resistance makes current distribution uneven, rendering traditional simulation methods unsuitable. To address this, a finite element method (FEM) based on the T–A formulation is proposed. This model solves coupled equations for the magnetic vector potential (A) and current vector potential (T), incorporating turn-to-turn contact resistance and anisotropic conductivity. The thin-strip approximation simplifies second-generation HTS materials as one-dimensional conductors, and a homogenization technique further reduces computational time by averaging the properties between turns, although it may limit the resolution of localized inter-turn effects. To verify the model’s accuracy, simulation results are compared against the H formulation, distributed circuit network (DCN) model, and experimental data. The proposed T–A model accurately reproduces key transient characteristics, including magnetic field evolution and radial current distribution, in both circular and racetrack NI coils. These results confirm the model’s potential as an efficient and reliable tool for transient electromagnetic analysis of NI–HTS coils. Full article

One of the important parameters of the sheet metal forming process is the coefficient of friction (CoF). Therefore, monitoring the friction coefficient value is essential to ensure product quality, increase productivity, reduce environmental impact, and avoid product defects. Conventional CoF monitoring techniques pose a number of problems, including the difficulty in identifying the features of force signals that are sensitive to the variation in the coefficient of friction. To overcome these difficulties, this paper proposes a new approach to apply unsupervised artificial intelligence techniques with unbalanced data to classify the CoF of DP780 (HCT780X acc. to EN 10346:2015 standard) steel sheets in strip-drawing tests. During sheet metal forming (SMF), the CoF changes owing to the evolution of the contact conditions at the tool–sheet metal interface. The surface topography, the contact loads, and the material behaviour affect the phenomena in the contact zone. Therefore, classification is required to identify possible disturbances in the friction process causing the change in the CoF, based on the analysis of the friction process parameters and the change in the sheet metal’s surface roughness. The Kohonen self-organising map (SOM) was created based on the surface topography parameters collected and used for CoF classification. The CoF determinations were performed in the strip-drawing test under different lubrication conditions, contact pressures, and sliding speeds. The results showed that it is possible to classify the CoF using an SOM for unbalanced data, using only the surface roughness parameter Sq and selected friction test parameters, with a classification accuracy of up to 98%. Full article

Aiming at the problem of the insufficient sealing performance of the solenoid valve poppet under a high working load and inspired by the multilevel groove structure of the octopus sucker and the adaptive sealing mechanism, a bionics-based design scheme for an annular groove sealing structure is proposed. By extracting the microscopic groove morphology features of the octopus sucker, we designed a multilayer rectangular cross-section groove structure at the annular interface, combined the designed structure with the Abaqus cohesive model to simulate the interface stripping behavior, and verified its mechanical properties by the pull-out test. The results show that the bionic groove structure significantly improves the bearing capacity of the sealing ring by enhancing the interface contact stress distribution and delaying the crack extension. Under the same working condition, the bionic structure increases the pull-out force by 46.1% compared with the traditional planar sealing ring. This study provides bionic theoretical support and an engineering practice reference for the design of sealing structures in complex working conditions, such as the solenoid valve poppet. Full article

This article presents the results of experimental studies aimed at determining the values of residual stresses and coefficient of friction (CoF) in bending under tension friction test, which simulates friction conditions in sheet metal forming. The influence of surface modification of the countersample and CoFs between the countersample and DC01 steel sheet on the residual stress were analysed. This study also focused on the influence of surface modification of countersamples on the change of the main parameters of DC01 steel sheets. The hole-drilling method was used to determine residual stresses. Electron beam melting, lead-ion implantation and a combination of these two techniques were used to modify the surface layer of 145Cr6 steel countersamples. The maximum value of the CoF, about 0.31, was found for the electron beam melted countersample. As a result of the surface modification process, this countersample was characterised by the lowest value of average roughness, which directly influenced the increase in the real contact area. The occurrence of residual tensile stresses was observed near the surface layer of the sheet strip in contact with the countersample. With the increase of the considered depth of residual stress measurement, the residual tensile stresses were transformed into compressive residual stresses with a value between −75 and −50 MPa, depending on the type of friction pair. SEM analyses allowed us to identify two main friction mechanisms for all friction pairs: adhesion and abrasive wear. Full article

Xinjiang larch (Larix sibirica Ledeb.) is a keystone species in the Altay Mountains, playing a vital role in maintaining ecosystem stability. This study investigates how different soil preparation techniques (ring, strip, and burrow) influence seed germination and seedling establishment by mitigating apomictic allelopathy. Experimental plots were established using artificial seeding and natural seed dispersal at soil depths of 5 cm, 10 cm, and 15 cm. Seedling survival and development were monitored in June, July, and August 2023. The results demonstrated that sod removal significantly enhanced seed germination by reducing allelopathic inhibition, improving seed–soil contact, and increasing moisture retention. Among the techniques, the ring method yielded the highest rates of seedling establishment, particularly when artificial seeding was combined with natural seed dispersal. Although seedling numbers tended to increase with soil depth, the differences were not statistically significant. Temporal dynamics revealed a peak in seedling survival in July, followed by a subsequent decline. These findings highlight the critical role of optimized soil preparation techniques in promoting successful seedling development. The study offers practical guidance for ecological restoration and sustainable forest management in degraded larch ecosystems of the Altay Mountains. Full article

Li-ion battery recycling is growing with better tech and eco-awareness. Explosions are possible during battery recycling due to their residual voltage. Proper battery discharge is vital to successful recycling. The goal of this study was to investigate a new method for discharging cylindrical batteries, utilizing a saltwater solution and copper conductors and analyzing the impact of both direct and indirect contact between the copper and the battery. A key variable impacting the discharge process was inconsistent spacing between the battery and the copper conductor. In the gap, the saltwater, functioning as an electrolyte solution, created an electrical short circuit, thus causing faster discharge. Because the battery was not in contact with the copper conductor during the discharge process, corrosion of the battery cap and valve occurred, leading to the battery’s anode and cathode elements dissolving into the solution. However, a near-total voltage drop of 99% was observed in the battery, indicating that it was almost completely discharged. Upon making contact with the copper strip during its discharge cycle, the battery exhibited no signs of corrosion. This report details the battery discharge process, encompassing an analysis of the electrochemical reaction, schematic diagrams, and a chemical analysis of the discharge precipitate. Full article

Titanium alloys are widely used in medicine due to their unique properties, including inertness with respect to living tissues, light weight, high strength, and impact toughness. For successful implementation, titanium alloy implants should possess high wear resistance and hydrophilicity. This article investigates the surface modification process of VT-1 and VT-6 titanium alloys by electron-beam processing (EBP). The EBP effect on the modified surface′s wear resistance, roughness, and hydrophilicity was analyzed. The specimens were made by machining them at a CNC turning center. The specimen surfaces were modified at the SOLO facility by a submillisecond modulated electron beam with a controlled power density of thermal impact, allowing it to reach and stabilize 1400 °C in 400 µs and then maintain it on the surface for 600 µs. A friction machine with a counterbody was used to study the wear resistance of the specimen surface. The study revealed that EBP reduces the roughness parameters of the surface. EBP also decreases the contact angle of wetting, indicating an increase in hydrophilicity compared to the original surface. Experimentally, it was shown that the formation of a nanostructure consisting of needle-like α-strips induced by EBP improves the wear resistance of the surface layer. Full article

The surface of a whole-roll flatness roll is in long-term contact with the steel strip, leading to slipping and wear and placing higher demands on the performance of the roll surface. This study establishes a finite element model for moving induction quenching and a phase transformation hardness numerical model by generating multi-field simulations and hardness predictions for the flatness roll during induction quenching. First, the thermal–physical properties of the roll material, MC3, are calculated using JMatPro V13.0. The dynamic domain and moving mesh techniques are applied in COMSOL Multiphysics to simulate time-varying boundary conditions, and the JMAK and K-M phase transformation models are used for electromagnetic–thermal–microstructure field simulations. Subsequently, the Taguchi method is used to optimize the induction quenching process of the flatness roll. After optimization, the martensitic hardened layer depth along the axial direction of the roll becomes uniformly distributed near the target value of 3 mm. Finally, through the modified Maynier hardness model, the corrected formula for the Vickers hardness of MC3 is obtained. The calculated hardness value of the roll surface in the simulation model reaches 950 HV, which agrees well with the experimental hardness results, validating the ability of the numerical model to guide specific processes. Full article

The interaction law between soil and tillage components is the basis for designing and selecting soil tillage components. This paper uses the discrete element method to explore the soil penetration performance of the comb teeth of a pneumatic film-stripping tillage residual film recycler under different structural and working state parameters. The soil particle contact model is set up, the virtual prototype of the comb roller is established, and EDEM (Version 2018, DEM Solutions Company, Edinburgh, UK) discrete element software is applied to simulate the interaction between the comb roller and the soil particles during the residual film recycler’s operation. Simulation and test results show that using a spiral arrangement of tooth comb knives (Alar, 843300, China, Zhongyuan Stainless Steel Bending Manufacturing Co.) can reduce the impact load on the machine, improving the soil disturbance and facilitating the penetration of soil mulch. The composite force on the combing roller increases with comb depth in the soil for a combing roller depth of 6–18 cm. Moreover, the rotational speed varies within the range of 60–120 r/min. The forward speed of the recycling machine significantly affects the soil penetration performance of the comb roller; the power it consumes increases with forward speed. This study can provide a reference for the structural design and optimization of working parameters of future deep tillage machines. Full article

In construction, closely spaced footings cause stress interactions that impact bearing capacity, settlement, and stability. This study experimentally evaluates the role of sheet pile walls (SPWs) in improving the performance of two adjacent strip footings—an existing footing and a newly placed footing—on sandy soil. The influence of SPW penetration depth (L_s) and center-to-center spacing between footings (X) on settlement and bearing resistance under vertical loads was investigated. Experiments were conducted in a large-scale soil tank (330 × 30 cm, depth 210 cm), with X ranging from 300 mm to 1000 mm and SPW lengths varying from 0 mm to 1500 mm. The results show that SPWs significantly enhance foundation performance by reducing settlement and increasing bearing capacity. When L_s/B = 6, the settlement of the new footing (F₁) decreases by 48%, while the existing footing (F₂) sees reductions of 47%, 67%, and 77% at L_s/B = 3, 4, and 5, respectively, under 500 kN/m² stress. The bearing capacity of F1 increases by 53% when X = 300 mm, demonstrating strong interference effects. Conversely, the F₂ settlement increases as X decreases, with a 96% rise at X = 300 mm, but it stabilizes at L_s/B = 5. SPWs also shift failure from general shear to punching shear, modifying soil–structure interaction. These findings highlight the effectiveness of SPWs in mitigating settlement, enhancing load-bearing capacity, and optimizing foundation design in closely spaced footing systems. The results suggest that an SPW length-to-footing width ratio (L_s/B) between 4 and 5 is optimal for minimizing settlement and improving stability, with only a slight difference in effectiveness between these two ratios. Full article

In this study, seven wet joint specimens of contact U-bars are designed in order to evaluate the flexural behavior of the wet joints in precast concrete slabs through four-point bending tests. This study investigates the effects of lap length, wet joint width, and water stop strips on the flexural behavior. The test results show that the ultimate bending capacity of the specimen with a lap length of 240 mm is 13.4% and 17.7% higher than that of the specimens with 160 mm and 80 mm. Water stop strips weaken the ductility of the specimen. The numerical model is established in ABAQUS finite element software and verified by the experimental results. Based on both test outcomes and finite element analysis, this study analyzes the deterioration effect of U-bars on the concrete within wet joints and proposes a calculation formula for flexural bending capacity that accounts for this deterioration. The proposed formula is shown to effectively predict the flexural capacity, since the theoretical predictions and the test results differ by less than 10%. Full article

Varroa destructor is an ectoparasitic mite that causes a true syndrome with complex symptoms in honeybees. For mite control, several synthetic active principles are commercially available. However, these formulations are proving less effective due to the acquisition of resistance mechanisms by the parasite. Naturally derived compounds, such as essential oils, are less prone to generating resistance mechanisms in mite populations and have been proven effective in numerous independent laboratory investigations. In this study, semi-field and field tests were conducted to evaluate the acaricidal efficacy of two essential oils (Citrus bergamia and Citrus limon), which, in our previous residual contact toxicity tests, showed efficacy against Varroa mites. For semi-field cage tests, two-level cages were set up. Filter paper soaked with different concentrations of essential oils was placed in the lower compartment of the cage; 20 honeybees and 10 Varroa mites were allocated in the upper level. Mite detachment from the honeybees was evaluated after 24 and 48 h. For field tests, cardboard strips soaked with solutions of essential oils at different concentrations were inserted in the experimental hives. Weekly, the strips were replaced, and the fall of parasites on the diagnostic bottom board was assessed. Semi-field tests showed that the essential oils, at the concentrations used, were not toxic to bees. In the semi-field tests, an average acaricidal efficacy of 33% and 60% was obtained, at the highest concentration used, for bergamot and lemon essential oils, respectively. During the 4 weeks of exposure to 600 mL of BEO, the average mite mortality was 28.5%. In the experimental group treated with the intermediate concentration of 1200 mL, the average mite mortality at the end of four weeks was 30.2%, while with the highest concentration of 1800 mL, it was 40.3%. During the four weeks of exposure to 600 mL of LEO, the average mite mortality was 34.1%. In the experimental group treated with the 1200 mL concentration, the average mite mortality at the end of the four weeks was 46.6%, while with the highest concentration, it was 50.7%. This study shows that the acaricidal efficacy observed in field tests differs from that in laboratory tests. Innovative formulations are needed that allow the time-controlled and gradual release of essential oil in the field. Full article

Humulones are a family of homolog natural products obtained from the strobiles of humulus lupulus, or hops plants. Structurally, they consist of substituted phloroglucinols with two isoprenyl side chains, a carbonyl group and a quaternary ring carbon substituted with a hydroxyl group. The three most prominent homologs are n-, co- and ad-humulone, containing isobutyl, isopropyl and secbutyl ketone groups, respectively. When solutions of humulones are exposed to UV light, they undergo stereoselective isomerization to the five-membered ring trans-isohumulones. A photoreactor was assembled from strip LEDs in close contact with UV-transparent tubing. This reactor allowed continuous-flow chemical synthesis of the isohumulones. The yield, conversion and product throughput are compared for the humulones, using LEDs emitting white, blue and ultraviolet light (visible, 400 nm, and 365 nm, respectively). Using an optimized continuous-flow reactor, a throughput of 0.43 g/h was obtained for trans-n-isohumulone. Full article