Search Results (201)

Atmospheric and oceanic turbulence can severely degrade the orbital angular momentum (OAM) mode purity of vortex beams in cross-media optical links. Here, we propose a hybrid correction framework that fuses multiscale phase-screen modeling with a lightweight U-Net predictor for phase-distortion—driven solely by measured optical intensity—and augments it with a feed-forward, Gaussian-reference subtraction scheme for iterative compensation. In our experiments, this approach boosts the l = 3 mode purity from 38.4% to 98.1%. Compared to the Gerchberg–Saxton algorithm, the Gaussian-reference feed-forward method achieves far lower computational complexity and greater robustness, making real-time phase recovery feasible for OAM-based communications over heterogeneous channels. Full article

As a novel prefabricated structural element, the pre-tensioned, prestressed concrete T-beam with polygonal tendons layout demonstrates advantages including reduced prestress loss, streamlined construction procedures, and stable manufacturing quality, showing promising applications in medium-span bridge engineering. This paper conducted a full-scale experiment and numerical simulation research on a 30 m pre-tensioned, prestressed concrete T-beam with polygonal tendons practically used in engineering. The full-scale experiment applied symmetrical four-point bending to create a pure bending region and used embedded strain gauges, surface sensors, and optical 3D motion capture systems to monitor the beam’s internal strain, surface strain distribution, and three-dimensional displacement patterns during loading. The experiment observed that the test beam underwent elastic, crack development, and failure phases. The design’s service-load bending moment induced a deflection of 18.67 mm (below the 47.13 mm limit). Visible cracking initiated under a bending moment of 7916.85 kN·m, which exceeded the theoretical cracking moment of 5928.81 kN·m calculated from the design parameters. Upon yielding of the bottom steel reinforcement, the maximum of the crack width reached 1.00 mm, the deflection in mid-span measured 148.61 mm, and the residual deflection after unloading was 10.68 mm. These results confirmed that the beam satisfied design code requirements for serviceability stiffness and crack control, exhibiting favorable elastic recovery characteristics. Numerical simulations using ABAQUS further verified the structural performance of the T-beam. The finite element model accurately captured the beam’s mechanical response and verified its satisfactory ductility, highlighting the applicability of this beam type in bridge engineering. Full article

This research evaluates the rheological and mechanical properties of polymer- and nanomaterials-modified bitumen by incorporating nanosilica (NSA), nanoclay (NCY), and Acrylonitrile Styrene Acrylate (ASA) at 5% by weight of the bitumen. The samples were prepared at 165 °C for one hour to obtain homogeneous blends. All samples were subjected to short- and long-term aging to simulate the effects of different operating conditions. The research conducted a series of tests, including consistency, frequency sweep, and multiple creep stress and recovery (MSCR) using the dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The results showed that all modified bitumen outperformed the neat bitumen. The frequency sweep showed a higher complex modulus (G*) and lower phase angle (δ), indicating enhanced viscoelastic properties and, thus, higher resistance to permanent deformation. The BBR test revealed that the bitumen modified with NCY5% has a creep stiffness of 47.13 MPa, a 51.5% improvement compared to the neat bitumen, while the NSA5% has the highest m-value, a 28.5% enhancement compared with the neat bitumen. The MSCR showed that the modified blends have better recovery properties and, therefore, better resistance to permanent deformation under repeated loadings. The aging index demonstrated that the modified bitumen is less vulnerable to aging and maintains their good flexibility and resistance to permanent deformations. Finally, these results showed that adding 5% polymer and nanomaterials improved the bitumen’s’ performance before and after aging by reducing permanent deformation and enhancing crack resistance at low temperatures, thus extending the pavement service life and making them an effective alternative for improving pavement performance in various climatic conditions and under high traffic loads. Full article

Background/Objectives: Partial maxillectomy frequently results in severe impairments of oral functions, such as difficulties in chewing, speech, swallowing, and facial appearance. Immediate prosthetic rehabilitation is challenging because soft tissue healing is typically required before impression taking. This study aimed to (1) develop a comprehensive digital workflow for fabricating immediate obturator prostheses using preoperative data and (2) assess their early clinical effectiveness in restoring oral functions after surgery. Methods: In this prospective clinical study, 20 patients undergoing partial maxillectomy from January 2023 to January 2025 were enrolled. A digital workflow combining cone-beam computed tomography (CBCT), intraoral scanning, CAD/CAM design, and 3D metal printing was implemented. Obturator prostheses were digitally designed preoperatively and inserted immediately post-resection. Functional outcomes were postoperatively evaluated after one month using the Obturator Functioning Scale (OFS), which measures functional, speech, esthetic, and psychosocial aspects. Results: The digitally fabricated immediate obturator prostheses were successfully placed intraoperatively in all patients. Most participants reported mild to moderate difficulties, with speech-related issues being the most common, while esthetic concerns were minimal. Masticatory function was satisfactorily restored in 75% of cases, and 60% of patients experienced minimal fluid leakage during swallowing. No significant differences were found between genders. Patients with larger defects tended to report greater functional challenges. Conclusions: The digitally planned immediate obturator prosthesis provides a practical and effective solution for early rehabilitation following partial maxillectomy. This digital workflow reduces patient discomfort, restores key oral functions, and facilitates psychosocial recovery. Full article

Reinforced concrete structures are prone to the development of microcracks during service. In this study, a composite-modified epoxy potting adhesive was formulated using nano-TiO₂, carboxyl-terminated butadiene nitrile liquid rubber (CTBN), and the reactive diluent D-669. The mechanical properties and effectiveness of this composite adhesive in repairing oblique cracks were systematically evaluated and compared with those of single-component-modified epoxy adhesives. Key material parameters influencing the performance of oblique crack repair were identified, and the underlying repair mechanisms were analyzed. Based on these findings, a theoretical formula for calculating the shear-bearing capacity of beams with repaired web reinforcement was proposed. Experimental results demonstrated that compared to single-component-modified epoxy resin, the optimally formulated composite adhesive improved the tensile strength, elongation at break, and bond strength by 4.07–21.16 MPa, 13.28–20.4%, and 1.05–3.79 MPa, respectively, while reducing the viscosity by 48–872 mPa·s. The viscosity of the adhesive was found to play a critical role in determining the repair effectiveness, with toughness enhancing the crack resistance and bond strength contributing to the structural stiffness recovery. The adhesive effectively penetrated the steel–concrete interface, forming a continuous bonding layer that improved energy dissipation and significantly enhanced the load-bearing capacity of the repaired beams. Full article

USP (usual temperature pitch)-modified asphalt optimizes its rheological properties through reactions between the modifier and the asphalt. This significantly enhances the high- and low-temperature adaptability and environmental friendliness of asphalt. It has now become an important research direction in the field of highway engineering. This article systematically investigates the impact of different dosages of USP warm mix modifier on asphalt binders through rheological and microstructural analysis. Base asphalt and SBS-modified asphalt were blended with USP at varying ratios. Conventional tests (penetration, softening point, ductility) were combined with dynamic shear rheometry (DSR, AASHTO T315) and bending beam rheometry (BBR, AASHTO T313) to characterize temperature/frequency-dependent viscoelasticity. High-temperature performance was quantified via multiple stress creep recovery (MSCR, ASTM D7405), while fluorescence microscopy and FTIR spectroscopy elucidated modification mechanisms. Key findings reveal that (1) optimal USP thresholds exist at 4.0% for base asphalt and 4.5% for SBS modified asphalt, beyond which the rutting resistance factor (G*/sin δ) decreases by 20–31% due to plasticization effects; (2) USP significantly improves low-temperature flexibility, reducing creep stiffness at −12 °C by 38% (USP-modified) and 35% (USP/SBS composite) versus controls; (3) infrared spectroscopy displays that no new characteristic peaks appeared in the functional group region of 4000–1300 cm⁻¹ for the two types of modified asphalt after the incorporation of USP, indicating that no chemical changes occurred in the asphalt; and (4) fluorescence imaging confirmed that the incorporation of USP led to disintegration of the spatial network structure of the control asphalt, explaining the reason for the deterioration of high-temperature performance. Full article

In order to study the mechanical properties of seven-wire steel strands after wire breakage failure, this study is based on the established finite-element beam-element model of seven-wire steel strands and analyzes two failure forms of symmetric wire breakage and asymmetric wire breakage. The stress redistribution pattern, recovery length, and parameter influences (temperature: 0–40 °C; friction coefficient: 0.15–0.30; torsion angle: 4–7°) are analyzed. The results show that broken wire damage will cause the stress of the intact steel wire to increase rapidly, increasing the risk of fracture of the intact steel wire. The recovery length will shorten with the increase in the friction coefficient, torsion angle, and the number of broken wires but will extend with the increase in temperature. The stress changes in the steel strand are as follows: when the number of broken wires increases, the maximum stress increases significantly and the average stress decreases slightly; when the temperature rises, the maximum stress and average stress in both cases of wire breakage show a significant linear decrease. These research results provide important references for the safety assessment and life prediction of cables in bridge engineering. Full article

The goal of this study is to evaluate how the inclusion of synthetic wax, added in 0.5% increments from 1.5% to 3.5%, affects the characteristics of PMB 45/80-65 (polymer-modified bitumen) during both short-term (RTFOT) and long-term (PAV) aging processes. Tests were carried out to assess the fundamental properties of the binder, leading to the determination of the penetration index (PI) and the plasticity range (PR). The binder’s properties were examined at below-freezing operating temperatures, with creep stiffness measured using a bent beam rheometer (BBR) at −10 °C, −16° C, −22 °C, and −28 °C. The rheological properties of the asphaltenes were evaluated based on both linear and nonlinear viscoelasticity. The experimental study explored temperature effects on the rheological properties of composite materials using a DSR dynamic shear rheometer at 40 °C, 60 °C, and 80 °C over a frequency range of 0.005 to 10 Hz. The main parameters of interest were composite viscosity (η*) and zero shear viscosity (η₀). Viscoelastic parameters, including the dynamic modulus (G*) and phase shift angle (δ), were determined, and Black’s curves were used to illustrate the relationship between these parameters, where G*/sinδ was determined. The MSCR test was employed to investigate the impact of bitumen on the asphalt mixture’s resistance to permanent deformation and to assess the degree and efficacy of asphalt modification. The test measured two parameters, irreversible creep compliance (J_nr) and recovery (R), under stress levels of 0.1 kPa (LVE) and 3.2 kPa (N-LVE). The Christensen–Anderson–Marasteanu model was used to describe the bitumen behavior during binder aging, as reflected in the rheological study results. Ultimately, this study revealed that synthetic wax influences the rheological properties of PMB 45/80-65 polymer bitumen. Specifically, it mitigated the stiffness reduction in modified bitumen caused by polymer degradation during aging at an amount less than 2.5% of synthetic wax. Full article

Multi-Beam frequency scanning leaky-wave antennas (FBS-LWAs) offer a viable solution for hardware miniaturization in direction-of-arrival (DOA) estimation systems. However, the presence of multiple spatial harmonics results in responses in multiple directions for a given incident source, introducing estimation ambiguity and significantly challenging accurate DOA estimation. Moreover, due to the nonlinear frequency response of the FBS-LWA, its response matrix does not satisfy the Vandermonde structure, which renders common rank-recovery techniques ineffective for processing coherent signals. As a result, the DOA estimation of coherent sources using multi-beam FBS-LWAs remains an open and challenging problem. To address this issue, this paper proposes a novel DOA estimation method for coherent signals based on multi-beam frequency scanning leaky-wave antennas. First, the received signals are transformed into the frequency domain via fast Fourier transform (FFT) to construct the signal data matrix from which the covariance matrix is computed.Then, conventional beamforming (CBF) is employed to obtain an initial estimate of the angle set, which will be further refined by a smaller grid to form a candidate angle set. Finally, a maximum likelihood algorithm based on the stochastic principle (Sto-ML) is used to suppress the interference of the parasitic directions and select the final DOA estimates from the candidate angle set. Simulation results show that the proposed method effectively mitigates the impact of parasitic directions and achieves an accurate DOA estimation of multiple coherent sources, even under both low and medium-to-high signal-to-noise ratio (SNR) conditions. Full article

Background: Pericoronitis is defined as inflammation of the soft tissues around the crown of an erupting tooth or a tooth with incomplete eruption, most commonly during eruption of the third molars. Pediatric dentists frequently encounter pericoronitis of the first molar, most of which resolve spontaneously. We describe the case of a 7-year-old girl who was referred to our hospital with intractable swelling in the right buccal region. Case Presentation: Intraoral examination showed an erupting right mandibular first molar and facial examination revealed swelling and an accumulation of pus in the cheek region. Radiographic examination revealed no pathological findings; therefore, it was diagnosed as a cheek abscess, and the region was incised that day. However, the symptoms recurred 3 weeks later, and cone-beam computed tomography detected a bone defect in the right mandibular first molar region, confirming a diagnosis of dentoalveolar abscess caused by pericoronitis of the first molar. The swelling resolved after incision of the abscess, and bone recovery was confirmed by X-ray in the follow-up period. Conclusions: Erupting first molars is at risk of pericoronitis, which may sometimes progress to a dentoalveolar abscess. Dental professionals should be alert to this possibility and should advise pediatric patients and their guardians to maintain good oral hygiene around erupting molars. Full article

Reinforced concrete (RC) beams with openings in shear spans exhibited a significantly reduced structural performance due to disruptions in load transfer mechanisms. This numerical study investigated the influence of pre-stressed iron-based Shape Memory Alloy (Fe-SMA) rebars on the behavior of RC beams with web openings, focusing on the effect of shear-oriented design parameters, including the stirrup spacing, stirrup diameter, and horizontal reinforcement around the opening. A nonlinear finite element analysis (NLFEA) was conducted using ABAQUS/CAE software 2020 to simulate the response of RC beams under these conditions. The results showed that the presence of web openings in RC beams reduced the ultimate load capacity and stiffness. However, the pre-stressed Fe-SMA reinforcement effectively mitigated these adverse effects, restoring much of the solid beam’s performance. Among the studied parameters, reducing the stirrup spacing significantly improved the load-bearing capacity, with the smallest spacing (100 mm) restoring 86% of the solid beam’s ultimate load. Increasing the Fe-SMA stirrup diameter further enhanced performance, with T16 stirrups recovering 92% of the solid beam’s ultimate load capacity. The most substantial improvement occurred when horizontal reinforcement was introduced, particularly with T16 stirrups, achieving a 95% load recovery, nearly matching the solid RC beam structural performance. These findings demonstrated the promising potential of pre-stressed Fe-SMA reinforcement as a viable solution for restoring the structural strength of RC beams with web openings. Full article

This study evaluated the combined effect of a cationic coagulant (Magnafloc 1727^®) and a high molecular weight anionic flocculant (SNF 604^®) on the settling properties, aggregate structure, and rheological behavior of synthetic tailings suspensions composed of kaolinite and quartz in industrial water at pH 11. Settling tests, focused beam reflectance measurement (FBRM), zeta potential measurement, and rheological characterization were used to analyze the system’s performance under different coagulant dosages (0–150 g/t), while keeping the flocculant dosage constant (20 g/t). The results indicated that the coagulant favored surface charge neutralization, shifting the zeta potential from −13.2 mV to +4.0 mV. This resulted in larger, more efficient flocs capturing fines, with a 46% turbidity reduction. FBRM analysis revealed a significant increase in aggregate size and a slight decrease in fractal dimension (from 2.35 to 2.20), consistent with larger volume structures and lower bulk density. Rheologically, a substantial increase in yield stress was observed, especially in 50 wt% suspensions, suggesting the development of a continuous flocculated network with greater mechanical strength. These findings highlight the importance of sequential chemical conditioning in clayey tailings and its impact on clarification efficiency and water recovery under alkaline conditions representative of industrial mining processes. Full article

This study investigates the stiffening phenomena caused by aging and low-dosage Kraft lignin addition on a soft bitumen (PG58S–28)- used in cold climate regions. Through a combination of physico-chemical and rheological analyses, including Fourier-transform infrared spectroscopy (FTIR), Brookfield rheometer viscosity (BRV), dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and complex shear modulus (G*) tests, the impacts of lignin modification and thermo-oxidative aging are evaluated. In particular, the anti-aging potential of lignin is scrutinized. The results indicate that while the carbonyl index effectively tracks bitumen aging, the sulphoxide index is less reliable due to high initial S=O bond content in Kraft lignin and greater repeatability variability. Standard rheological tests (BRV, DSR, MSCR, and BBR) show that long-term aging significantly increases bitumen stiffness, while lignin modification leads to a moderate stiffening effect but does not exhibit any noticeable anti-aging properties. The G* analysis confirms that aging strongly influences bitumen rigidity, particularly at low and intermediate equivalent frequencies, while lignin acts similarly to an inert filler, with minimal effects on linear viscoelastic (LVE) behaviour. Overall, the study concludes that the addition of Kraft lignin at low dosage does not alter the fundamental aging mechanisms of bitumen, nor does it provide significant antioxidant benefits. These findings contribute to the ongoing discussion on bio-based bitumen modifiers and their role in sustainable pavement materials. Full article

Seismic resilience is a critical concern in the development of prefabricated concrete structures. This study investigates the seismic performance of prestressed prefabricated concrete frames with mechanically connected steel bars through both experiment and finite element simulations using ABAQUS. The research aimed to evaluate the influence of prestressed and mechanical connections on structural stiffness, energy dissipation and failure mechanisms, and a restoring force model was developed based on the experimental and numerical results to provide a theoretical basis for seismic design. The parametric analysis based on the verified numerical model shows that the pretension can significantly enhance the bearing capacity, stiffness and deformation recovery ability of the prefabricated concrete frames. The peak load increased by 30.8%, the initial stiffness improved by 17.4%, the ductility coefficient reached 2.82, the residual deformation rate reduced by 40.7%, the emergence and development of cracks delayed, and the crack width reduced. Improving the effective prestress in a certain range can improve the bearing capacity and initial stiffness of the frame. Increasing the strength of concrete and the ratio of the longitudinal reinforcement of beam and column can effectively enhance the bearing capacity of the frame. With the increase of axial compression ratio in a certain range, the bearing capacity and initial stiffness of the frame increase significantly, but the ductility decreases. Based on the hysteresis curve and skeleton curve tested, the skeleton curve model and stiffness degradation law of the prestressed prefabricated concrete frames reinforced with mechanical connection steel bars were fitted, and the restoring force model was established. The predicted value was in good agreement with the experimental value, illustrating the validity of the model developed. These results offer valuable insights for optimizing the seismic design of prefabricated concrete frames, ensuring a balance between strength, stiffness, and ductility in earthquake-resistant structures. Full article

Functional polymeric materials play a critical role in optimizing flocculation and sedimentation processes in mining tailings, where complex interactions with mineral surfaces govern polymer performance. This study examines the structure–performance relationship, which describes how the internal structure of aggregates (e.g., compactness, porosity and fractal dimension) influences sedimentation behavior, specifically for anionic polyacrylamide (SNF 704) in kaolin-quartz-pyrite suspensions at a pH of 10.5. Using focused beam reflectance measurement (FBRM) and static sedimentation tests, we demonstrate that pyrite exhibits the highest flocculant adsorption capacity, inducing a train-like polymer conformation on its surface. This reduces the formation of effective polymeric bridges, resulting in less compact and more porous aggregates that negatively impact sedimentation rates. Increasing the flocculant dosage improves the capture of fine particles; however, at high pyrite concentrations, rapid saturation of adsorption sites limits flocculation efficiency. Additionally, the fractal dimension of the aggregates decreases with increasing pyrite content, revealing more open structures that hinder consolidation. These findings underscore the importance of optimizing polymer dosage and tailoring flocculant design to the mineralogical composition, thereby enhancing water recovery and sustainability in mining operations. This study highlights the role of structure–property relationships in polymeric flocculants and their potential for next-generation tailings management solutions. Full article