Search Results (319)

This prospective case series evaluated the short-term outcomes following percutaneous cementoplasty as the sole palliative treatment for appendicular osteosarcoma in 10 dogs. Synthetic self-hardening calcium phosphate bone substitute was injected into the osseous defect under fluoroscopic guidance after curettage of the bone tumor. Clinician assessment included a numerical rating score for lameness, offloading, and ease of lifting the contralateral limb as well as the 4A-VET postoperative pain scale. Owner assessment was obtained using three descriptive questionnaires, the Helsinki Chronic Pain Index (HCPI), the Canine Brief Pain Inventory (CBPI) and the Canine Symptom Assessment Scale (CSAS). Measures were recorded preoperatively and at 2, 4, 8, and 12 weeks following surgery. Early improvement in the 4A-Vet score was noted at the 2-, 4-, 8-, and 12-week time points for all major pain and function metrics. Similarly, the CBPI pain severity and interference scores demonstrated early postoperative improvement during the 2- and 4-week time points with partial attenuation by 8 and 12 weeks. Panting, difficulty sleeping, whining/moaning, and lack of appetite were significantly reduced when assessed via the CSAS. Cementoplasty as a monotherapy, affording early pain relief and improved structural integrity, supports its role as a palliative limb-preserving option for dogs unable to undergo amputation. Full article

In precision mold manufacturing, the machining of HRC52 hardened steel causes severe tool wear and high noise in multi-source sensor signals, making accurate remaining useful life (RUL) prognostics challenging. To address this, we propose a hybrid model based on a two-stage VB-to-RUL estimation strategy. The network first performs high-fidelity flank wear (VB) trajectory tracking; the RUL is then deduced via threshold mapping. The model integrates three components: a one-dimensional deep convolutional neural network (DCNN), a low-resolution self-attention (LRSA) module with 1D-to-2D spatiotemporal reconstruction, and a multi-channel bidirectional long short-term memory network (McBiLSTM). A Gaussian smoothing filter is first applied to denoise the 50 kHz signals, followed by physical-period sliding windows for feature extraction. A multi-strategy fusion pooling layer (mean, max, and last-quarter features) further improves prediction accuracy. Using the PHM 2010 milling cutter dataset under leave-one-out cross-validation, the proposed model achieves a mean absolute percentage error (MAPE) of 1.45% and a root mean square error (RMSE) of 2.76 μm, reducing prediction error by up to 75.6% compared to Transformer, LSTM, and GRU baselines. These results demonstrate that the model effectively extracts degradation features even during the accelerated wear stage, providing a potential solution for tool health monitoring and predictive maintenance under complex cutting conditions. Full article

Healing agent encapsulated in polymeric microcapsules has proven its ability to seal surface and internal cracks. Focused on mitigating the negative impact of capsules on the properties of fresh cement paste and hardened cementitious matrix, uncertainties in self-healing triggering, and poor control of the released quantity, researchers report technological improvements in predominantly experimental studies. However, practical applications will necessitate lightweight models that capture all the characteristics of practical importance. Analysis of the scientific literature reveals the lack of such models adapted for cementitious composites. In this paper, a model rooted in continuum damage mechanics, tuned based on empirical data, is used in the finite element analysis of concrete specimens containing polymer self-healing microcapsules to quantify self-healing efficiency and local damage-healing behavior. The predicted increase in the self-healing rate is more pronounced for specimens subjected to compression compared to that for elements subjected to four-point bending. Thus, for a 20% increase in healing efficiency, strength recovery in compression increases from 18.5% to 32% for C25 and C30, respectively, whereas the corresponding values for tension in the tension-be-flexure setup are 3.5% and 5.3%. Full article

This study conducts a comparative legal analysis of South Korea’s Framework Act on Artificial Intelligence (enacted January 2025, effective January 2026) and the EU AI Act (effective August 2024), focusing on the structural implications of their divergent regulatory philosophies for sustainable digital governance. Employing legal interpretive analysis (textual, systematic, and teleological) and comparative legal methodology, supplemented by risk-based regulation theory and the theory of hardening of soft norms, this paper examines three interconnected dimensions: the conceptual distinction between “high-impact” and “high-risk” AI, the legal nature of self-regulatory structures, and the potential distortion of civil liability attribution. The analysis reveals that Korea’s adoption of the “high-impact” concept, while strategically reducing compliance costs and avoiding stigma effects, generates significant legal gaps, including potential violations of the constitutional principle of clarity, a “liability lightning rod” phenomenon transferring responsibility from AI operators to frontline practitioners, and insufficient institutional prerequisites for effective self-regulation. In contrast, the EU’s ex-ante preventive framework provides greater legal certainty through direct enumeration of high-risk sectors and mandatory conformity assessments. Drawing on the growing body of EU AI Act scholarship, this paper proposes a five-step legislative model for dynamic regulatory adjustment tailored to Korea’s constitutional structure, encompassing statutory core criteria, periodic re-evaluation with parliamentary oversight, phased mandatory enforcement, and a presumption of conformity system, thereby offering a co-regulatory framework that balances innovation promotion with fundamental rights protection. Full article

L605 cobalt-based superalloy is a typical difficult-to-machine material because of its high strength, pronounced work hardening, and low thermal conductivity. To improve the microgroove machining performance of this alloy, a self-developed water-jet-guided laser (WJGL) system equipped with a multi-focus lens was employed, and single-factor experiments together with a Box–Behnken response surface design were conducted to investigate the effects of laser power, pulse frequency, water pressure, and feed speed on microgroove depth. The results showed that microgroove depth increased with laser power, decreased with pulse frequency and feed speed, and first increased and then decreased with water pressure. Analysis of variance demonstrated that the developed quadratic regression model was significant and fit the data well. A recommended parameter combination of 274.9 W laser power, 3334.9 Hz pulse frequency, 1.636 MPa water pressure, and 0.107 mm/s feed speed corresponded to a predicted microgroove depth of 621.2 μm. Validation experiments yielded an average microgroove depth of 600.2 μm, with a relative error of 3.4%, indicating that the model can be used for microgroove depth prediction and parameter selection in WJGL machining of L605 alloy and may provide guidance for future multi-objective optimization considering both machining quality and efficiency. Full article

This study introduces advanced epoxy formulations incorporating carbon-based nanofillers, carbon nanotubes, nanofibers, and functionalized graphene. The epoxy matrix was optimized to lower moisture absorption and enhance multifunctional properties. A non-stoichiometric epoxy/hardener ratio reduced equilibrium water concentration (C_eq) by up to 30% compared to unmodified epoxy, achieved by minimizing polar groups responsible for water bonding. These improvements benefit the aerospace, marine, and wind energy sectors. All nanofillers form a secondary phase with reduced glass transition temperature (T_g), but functionalized graphene performs best. Its self-assembled sheet architectures trap resin, limit water interaction, and create conductive pathways, improving strength, reducing moisture uptake, and achieving a low electrical percolation threshold (EPT). Full article

To address the critical challenges of lithology acquisition and low blasting refinement under extreme low temperatures and varying thermal conditions in high-altitude environments, this study develops a real-time dynamic identification method for rock-like interfaces using Measurement While Drilling (MWD) technology. The scope of this research involves the use of a self-developed indoor digital drilling experimental platform to simulate both ambient and freezing (−20 °C) conditions. Procedures included conducting comprehensive comparative drilling experiments on various rock-like materials with distinct strength levels to evaluate their mechanical responses during penetration. The major findings reveal a significant influence of low-temperature hardening effects on MWD parameters; specifically, the frozen state notably increases drilling torque and feed pressure while simultaneously decreasing the stable rotational speed of the drill bit. To resolve the feature parameter drift induced by temperature variations, a novel interface recognition algorithm is proposed that integrates Z-score normalization, change-point detection, and multi-dimensional spatial clustering. Through a dual-detection mechanism involving both single-point and cumulative features, the algorithm effectively captures precise mutation information during rock layer transitions. It further incorporates multi-dimensional indicators, such as consistency, change intensity, and point density, to perform comprehensive weighted scoring. Experimental results demonstrate that the proposed algorithm effectively eliminates the systematic offset of parameters caused by temperature fluctuations. The prediction error at both “strong-weak” and “weak-strong” transition interfaces is maintained within 1.5 mm, which significantly improves the accuracy and robustness of interface recognition under complex and varying working conditions. These key conclusions provide essential technical support for the implementation of differentiated charging and green refined mining operations, ensuring greater energy efficiency and environmental protection in cold-region engineering. Full article

Epoxy materials are an important class of thermosets whose properties strongly depend on the used formula, the curing parameters, and many available hardeners. Achieving desired properties such as enhanced thermal stability, extended lifetime, or self-regeneration requires selecting suitable precursors and carefully tuning curing conditions. In this work, a selected biphenyl epoxy precursor was used as a model compound to assess whether using different hardeners could be an effective factor in tailoring the elasticity of cured epoxy networks. We employed two chemically distinct hardeners—4,4′ diaminodiphenylmethane (DDM) and suberic acid—to generate materials with markedly different final properties. For instance, the glass transition temperature T_g varied within a range of over 35 °C. Two complementary experimental techniques were used in this paper to establish the optimal curing parameters: differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). Both techniques supported tracking of changes in the mixture while curing and enabled determination of T_g in the obtained products. Dielectric relaxation spectroscopy revealed various molecular motions (α, β, and γ-processes) occurring in different phases, especially in glass-forming solids. BDS is therefore a good tool for testing new organic materials. The analytic route used in this work, based on a combination of calorimetric and electrical approaches, enables precise adjustment of the curing parameters to a specific hardener and helps verify the effects of using different hardeners on the elastic properties of the product. This allows the creation and modification of epoxy matrices towards modern materials, such as composites with self-healing properties or enhanced thermal stability. Full article

In this study, hardfacing and a flux-cored/self-shielded powder wire of the FCAW-S-90G13N4 type was employed to produce and investigate the deposits of high-manganese steel. The effects of high-frequency mechanical impact (HFMI) treatment on the microstructure, hardening, and scratch resistance of the deposits were studied to evaluate and predict the impact wear resistance of the hardfacing deposits under controlled impact load conditions. As observed by XRD, SEM, and nanoindentation, the microstructure of deposited metal comprised a soft austenite matrix, dispersed hard carbides, and an ε phase (~26 vol.%). The wear resistance is thus not controlled by carbides alone but arises from the synergistic action of a hard carbide network within a ductile matrix. HFMI resulted in twinning, an increase in dislocation density, a grown volume fraction of ε (>60%) and α′-martensite. The interaction between twins, martensites, and dislocations provides a double/triple increase in microhardness (from HV_0.2 = 2.78 GPa to HV_0.2 = 6–7.69 GPa). After HFMI, scratch tests showed lower restored depths of scratch tracks and a 36–68% deceleration in the wear rate regarding those of the initial deposit. The underlying wear mechanisms were assessed accounting for the SEM observations of the scratch track morphologies and a ‘counterbody penetration vs. shear stresses ratio’ map. The initial plastic deformation-related mechanism (wedge/pile-up formation) changed by HFMI to ploughing. The obtained results allow one to evaluate and predict the impact wear resistance of the hardfacing deposits under controlled impact load conditions. Full article

The formability of AA7021-T4 sheets under changing strain paths was investigated via a novel crystal plasticity model and associated experimentation. The motivation was to advance simulation tools for process design of limited-ductility 7xxx alloys, with important applications in the automotive industry. Pre-strains were applied in biaxial and plane-strain tension using Marciniak tooling, followed by uniaxial tensile testing to failure. Strain measurements were obtained by digital image correlation, while dislocation structures were characterized using high-resolution EBSD. A strain-gradient elasto-plastic self-consistent (SG-EPSC) model incorporating dislocation density-based hardening and backstress from geometrically necessary dislocations (GNDs) was employed to predict the stress–strain response and dislocation evolution. Results showed that pre-strains normalized by forming limit diagram (FLD) criteria produced comparable residual uniaxial tensile ductility, regardless of whether biaxial or plane-strain tension was applied, despite differences in absolute pre-strain levels. Both experiments and simulations revealed that GND density correlated with remaining ductility better than simple strain magnitude values. These findings indicate that AA7021-T4 retains greater formability under multiaxial strain path changes than expected from FLD-based considerations. The combined experimental–modeling approach demonstrates the value of incorporating microstructure-based variables, such as GNDs, into forming assessments of high-strength aluminum alloys, with implications for their potential use in automotive lightweighting development. Full article

Fatigue properties remain a key challenge for aluminum–steel self-piercing riveted (SPR) joints in lightweight structures. This study evaluates shot peening as a pretreatment for the AA5052 sheet to improve the fatigue behavior of AA5052/SPFC440 dissimilar joints and to clarify the underlying mechanisms. Shot-peened and conventional SPR joints were prepared for comparison. Quasi-static tensile tests were conducted, and tension–tension fatigue tests were performed at high and low load levels. After shot peening, multiple factors with residual compressive stress, subsurface hardening, and surface roughness influenced the fatigue performance of the SPR joints. This led to a load-level-dependent fatigue behavior, with improved fatigue performance at low load levels and reduced performance at high load levels. At high load conditions, the increased surface roughness played a more significant role, with more crack initiation sites observed, resulting in fatigue lives comparable to or slightly lower than those of conventional joints. In contrast, at low load levels in the long-life regime, surface tensile stress was effectively reduced, crack initiation at surface defects was suppressed, and crack initiation shifted from the surface to subsurface regions, resulting in an 11.3% improvement in fatigue strength. These findings provide practical guidance for improving the fatigue performance of dissimilar-material SPR joints through material surface pretreatment. Full article

This paper proposes a high-speed static random access memory (SRAM) architecture that integrates a self-refresh mechanism with a novel single error and adjacent-bit errors correction (SEABEC) scheme to enhance resilience against single-event upsets (SEUs) in radiation-prone environments. By leveraging extended Hamming coding and dynamic circuits, the design achieves a 29.1% RW speed improvement, reduces SEU cross-section by one order of magnitude, and incurs a 29.8% area overhead and a 95.2% dynamic power increase of the ECC module, leading to an overall chip area increase of ~14.2% compared to static logic-based RH SEC-DED SRAM. Radiation experiments validate superior tolerance across a LET range of 1.63–21.8 MeV·cm²/mg, demonstrating nearly doubled SEU resilience compared to conventional SEC-DED-based designs. This work balances error correction capabilities with system efficiency, making it suitable for high-reliability applications in space electronics and advanced processors. Full article

Phosphogypsum is one of the most widely produced gypsum-containing wastes. Therefore, researchers worldwide are exploring ways to recycle them. It is most often considered as an alternative to natural gypsum in the production of calcium sulfate hemihydrate. There are also isolated studies aimed at producing insoluble anhydrite (CaSO₄ II) from phosphogypsum. Compared to hemihydrate, anhydrite is characterized by greater strength and water resistance, and compared to Portland cement, it demonstrates lower energy consumption and CO₂ emissions during production. This study examined the possibility of phosphoanhydrite binder (CaSO₄ II) synthesis by calcination at 600, 800, and 1000 °C of phosphogypsum from four different industrial plants. Phosphoanhydrite binders capable of self-hardening, without the use of special additives, were synthesized. Their maximum strength at 28 days reached 57 MPa, and 69 MPa at 90 days. New data have been obtained regarding the influence of initial phosphogypsum characteristics and calcination temperature on the properties of CaSO₄ II and the hardened phosphoanhydrite paste. Full article

The rising environmental burden of Portland cement production has intensified the demand for eco-friendly binders that support sustainable construction. This study investigates the development and performance of eco-friendly self-compacting geopolymer concrete (SCGC) produced from industrial by-products, including fly ash (FA), ground granulated blast furnace slag (GGBFS), silica fume (SF), metakaolin (MK), and glass waste powder (GWP). Twenty-one binder formulations were evaluated for fresh-state workability, mechanical performance, durability, and microstructural characteristics under different curing regimes. Fresh properties were assessed using slump flow, V-funnel, L-box, and J-ring tests, while hardened-state evaluations included compressive and flexural strength, Young’s modulus, and water absorption. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were performed on selected mixes to examine microstructural features and crystalline phase development. Results highlight a strong dependency of SCGC performance on binder composition and curing conditions. Mixes rich in GGBFS and SF demonstrated superior mechanical and durability performance, achieving compressive strengths of up to 102.4 MPa under water curing and 107.6 MPa under heat curing, along with negligible water absorption, reflecting a dense and well-developed gel matrix. SEM micrographs confirmed homogeneous, compact microstructures in high-performing mixes, while XRD analysis revealed broad amorphous humps indicative of well-formed N-A-S-H and C-A-S-H gel phases with minimal crystalline residues. In contrast, FA-dominant mixes displayed delayed strength development, and MK-GWP-rich systems exhibited higher porosity and reduced strength. This study underscores the significance of precursor synergy, optimized curing strategies, and microstructural refinement in tailoring SCGC for high-performance, durable, and low-carbon applications in sustainable construction with values ranged from 38.64 GPa (Mix 21) to 25.04 GPa (Mix 19) at 28 days. Stiffer mixes corresponded to denser matrices containing GGBFS and silica fume, whereas lower values were linked to weaker bonding and higher porosity. Full article

This study investigates the effects of artificial plate powders with different compositions on the durability, physical, mechanical, and microstructural properties of self-compacting mortar (SCM). Waste quartz-based composite plate fragments and waste cultured marble pieces were ground into fine powders, and the resulting quartz-based plate powder (WQP) and cultured marble powder (WMP) were used as filler materials to partially replace cement at replacement levels of 0%, 5%, 10%, 15%, 20%, and 25% by mass. The workability of fresh mortars was evaluated using the mini slump flow test in accordance with EFNARC guidelines, while hardened specimens were tested for porosity, capillary water absorption, abrasion resistance, flexural strength, and compressive strength. In addition, specimens with a 25% replacement ratio that were exposed to temperatures of 300 °C, 600 °C, and 900 °C underwent mechanical testing, and their microstructures were analyzed using SEM and XRD. The results indicated that increasing replacement ratios generally reduced workability and mechanical strength, while increasing porosity and water absorption. However, low replacement levels slightly enhanced flexural strength due to the filler effect. SEM and XRD analyses revealed that the quartz in WQP maintained high thermal stability, and mortars containing WQP exhibited a denser, more coherent, and more homogeneous microstructure. Overall, the findings demonstrate that waste-based plate powders can serve as sustainable fillers in SCM, offering environmental benefits while maintaining acceptable mechanical and microstructural performance. Full article