Search Results (295)

Dense and complex underground structures impose stringent requirements on shield tunneling. In the close-proximity construction of super-large-diameter shield tunnels, challenges may arise, including adverse impacts on the normal operation of existing structures, as well as difficulties in ensuring the bearing capacity and deformation control of these structures during excavation. This study, based on the stratigraphic conditions of the Chengdu area, employs FLAC3D 7.0 version software to simulate the section where the Shuanghua Road Tunnel underpasses both Metro Line 10 and the Chengdu-Guiyang High-Speed Railway. The main conclusions are as follows: (1) Tunnel underpassing induces uneven settlement in the metro tunnel, with a maximum settlement reaching 47.7 mm. The settlement trough exhibits a twin-peak morphology during dual-line construction. When a single super-large-diameter tunnel line crosses the existing structural cluster, the maximum settlement is located directly above the crossing point. During dual-line crossing, the maximum settlement shifts towards the midpoint between the two new tunnel lines. (2) As the left line of the new tunnel approaches the existing structure, the cross-sectional deformation of the existing structure is “pulled” towards the direction of the excavated new tunnel. After the new left line moves away, the cross-sectional deformation gradually recovers to a bilaterally symmetrical state. (3) The tunnel cross-section undergoes dynamic “compression-tension” convergence changes during the construction process, with a maximum longitudinal tensile convergence of −1.28 mm. (4) During the underpassing of the existing structural cluster by the super-large-diameter tunnel, the maximum torsion angle is approximately −0.016°, occurring at the moment when the shield machine head first passes directly beneath, located directly above the new tunnel. The torsion angle of the existing structure is greatest during the first underpassing event, and the maximum torsion angle during the second underpassing is lower than that during the first. This study reveals the composite deformation mode of “settlement-convergence-torsion” during the underpassing of existing structural clusters by super-large-diameter shield tunnels, providing a theoretical basis for risk control in similar adjacent engineering projects. Full article

This paper investigates the cold rolling (CR) deformation behavior of electrolytic nickel at room temperature. While the microstructural evolution across deformation levels ranging from 5% to 98% is systematically characterized. The deposited electrolytic nickel exhibits numerous growth twins of various lengths and thicknesses, accounting for over 70% of the microstructure. The average grain size is 0.56 μm, and the grain size distribution is relatively broad. The plastic deformation of electrolytic nickel in the early stage is governed by the interaction between high-density dislocations and abundant twins. The primary mechanism accommodating deformation is detwinning. At 70% deformation, under high strain, complete detwinning occurs. When the CR reaches 90%, the average short-axis grain size is refined to 113 nm, indicating the deformation-induced refinement limit of electrolytic nickel. The microstructure at this stage exhibits a typical lamellar morphology. At 98% deformation, the average microhardness peaks at 240.3 HV, representing a cumulative increase of 46.88%. Dynamic recovery and recrystallization are observed at both 70% and 98% deformation levels, accompanied by the formation of Σ3 {120} type incoherent twins within recrystallized grains. Under large strain, the dominant cold plastic deformation mechanism transitions to a synergistic effect of dislocation slip and stratification. Full article

This study develops an immersive marine Information and Communication Technology (ICT) convergence framework designed to enhance coastal climate resilience by improving accessibility, visualization, and communication of scientific research on Dokdo (Dok Island) in the East Sea. High-resolution spatial datasets, multi-source marine observations, underwater imagery, and validated research outputs were integrated into an interactive virtual-reality (VR) and web-based three-dimensional (3D) platform that translates complex geophysical and ecological information into intuitive experiential formats. A geospatially accurate 3D virtual model of Dokdo was constructed from maritime and underwater spatial data and coupled with immersive VR scenarios depicting sea-level variability, coastal morphology, wave exposure, and ecological characteristics. To evaluate practical usability and pro environmental public engagement, a three-phase field survey (n = 174) and a System Usability Scale (SUS) assessment (n = 42) were conducted. The results indicate high satisfaction (88.5%), strong willingness to re-engage (97.1%), and excellent usability (mean SUS score = 80.18), demonstrating the effectiveness of immersive content for environmental education and science communication crucial for achieving Sustainable Development Goal 14 targets. The proposed platform supports stakeholder engagement, affective learning, early climate risk perception, conservation planning, and multidisciplinary science–policy dialogue. In addition, it establishes a foundation for a digital twin system capable of integrating real-time ecological sensor data for environmental monitoring and scenario-based simulation. Overall, this integrated ICT-driven framework provides a transferable model for visualizing marine research outputs, enhancing public understanding of coastal change, and supporting sustainable and adaptive decision-making in small island and coastal regions. Full article

Current traditional tea processing production lines suffer from issues such as fragmented data and low levels of intelligence. This paper proposes a three-dimensional visualization system for tea processing production lines based on digital twins. Firstly, the system’s overall framework and functional architecture were established. Secondly, multi-source heterogeneous data from the production line was collected and managed through a driver architecture, enabling the construction and mapping of the digital twin information model. Thirdly, referencing the actual environment of a green tea processing line, scene-specific lighting models and rendering techniques were employed to recreate a virtual green tea processing environment. During this process, lighting optimization enhanced the realism of the system’s scenes. Finally, employing data-driven methodologies, the system dynamically simulates the operational states of various production line equipment and the morphological changes in tea leaves. This achieves comprehensive three-dimensional visualization and all-round monitoring of the tea processing production line. Experimental validation confirms the feasibility of this visualized 3D system, injecting fresh impetus into advancing intelligent tea production. Full article

With the rapid expansion in the use of nanomaterials, ensuring their reprocessability has become a critical consideration for the sustainable development of polymer-based nanocomposites. In this study, the effects of repetitive thermo-mechanical processing cycles on the properties of polycarbonate (PC)/organoclay nanocomposites, as well as the impact of reactive extrusion of reprocessed PC/organoclay nanocomposites using a chain extender, were investigated for the first time. The nanocomposites were processed three times using a twin-screw extruder, and a multi-anhydride functional chain extender was incorporated to counteract the thermo-mechanical degradation observed after the third extrusion cycle. Morphological analysis indicated that the delamination of clay nanolayers within the polymer matrix was slightly enhanced with increasing extrusion cycles, while the addition of the chain extender further promoted nanoclay exfoliation. Despite the improved clay dispersion in PC, both rheological and tensile measurements revealed the detrimental effects of repeated reprocessing on the nanocomposites. The chain extender effectively mitigated this degradation by relinking cleaved polymer chains; consequently, the complex viscosity and storage modulus at 0.1 Hz of the three-times-extruded nanocomposite increased by 248% and 426%, respectively, following chain extender incorporation. The effectiveness of the chain extender was further evidenced by a 27% enhancement in tensile strength. The glass transition temperatures of the samples were not significantly affected by either the extrusion cycles or the addition of the chain extender. The thermal stability of the nanocomposites decreased with increasing numbers of extrusion cycles; however, the incorporation of the chain extender imparted enhanced resistance to thermal degradation, as confirmed by thermogravimetric analysis. Full article

Pharyngeal airway morphology is closely linked to craniofacial development, and children with Class II malocclusion—often characterized by mandibular retrusion—may present reduced airway dimensions and a higher risk of obstructive sleep apnea. This retrospective single-center study evaluated whether functional orthodontic appliances can improve pharyngeal airway space by promoting mandibular advancement during growth. Fifty patients aged 6–12 years with skeletal Class II malocclusion (ANB > 4°) were treated with a Twin Block appliance (n = 18), Rapid Palatal Expander (RPE; n = 16), or AMCOP^® elastodontic device (n = 16). Pre- and post-treatment lateral cephalograms were analyzed to assess skeletal (SNA, SNB, ANB, Co–Gn), dentoalveolar (overjet, overbite, IMPA), and pharyngeal airway variables (SPAS, MAS, PAS). Intra-group changes were tested with paired t-tests and inter-group differences with one-way ANOVA and Tukey post hoc tests (α = 0.05). All appliances produced statistically significant increases in pharyngeal airway dimensions. The Twin Block group showed the greatest improvements, with mean increases of 2.1 mm in SPAS (p < 0.001), 1.8 mm in MAS (p < 0.001), and 1.5 mm in PAS (p < 0.001), together with a significant mandibular advancement (ΔSNB = +1.7°; ΔANB = −1.5°) and elongation of mandibular length (ΔCo–Gn = +3.3 mm). RPE and AMCOP^® induced more moderate, yet significant, skeletal and airway changes (RPE: SPAS +1.4 mm, p = 0.006; MAS +0.9 mm, p = 0.009; PAS +0.8 mm, p = 0.022; AMCOP^®: SPAS +0.9 mm, p = 0.034; MAS +0.9 mm, p = 0.041; PAS +0.6 mm, p = 0.037). Within the limitations of this small, retrospective single-center sample, the findings indicate that functional orthodontic treatment during growth may be associated with increases in pharyngeal airway dimensions in Class II patients. Among the appliances evaluated, the Twin Block showed the most pronounced skeletal and morphological airway changes. Full article

Ice accretion on arctic vessels and offshore platforms poses serious threats to navigation and operational safety. Existing research has primarily focused on isolated structures. This study employs a combined approach of numerical simulation and experimental validation. It systematically investigates the icing characteristics of tandem twin-cylinders in wake flow fields. This configuration is common yet rarely studied in real marine environments. The model employs two identical cylinders arranged in tandem. It examines the effects of wind speed, distance, diameter, and wind direction angle on ice accretion morphology and distribution. Validation was conducted through wind tunnel tests at 5 m/s wind speed and 2.0 g/m³ liquid water content. Results demonstrate a significant shielding effect from the upstream cylinder wake. As wind speed increases, the ice mass difference between upstream and downstream cylinders widens. Ice mass shows a nonlinear relationship with distance. Minimum ice accretion on the downstream cylinder occurs at 350–450 mm distance. This results from wake pattern transition. The shielding effect exhibits strong nonlinear dependence on wind direction angle. A deviation of 8.2° increases total ice mass by 242.5%. Multivariable analysis confirms these nonlinear mechanisms persist under coupled distance–wind speed variations. This study provides the first systematic revelation of twin-cylinder icing mechanisms in wake flow fields. It offers a validated predictive tool for anti-icing design of arctic marine structures. Full article

Background: Realistic simulation of ECG signals is essential for validating signal-processing algorithms and training artificial intelligence models in cardiology. Many existing approaches model either waveform morphology or heart rate variability (HRV), but few achieve both with high accuracy. This study proposes a hybrid method that combines morphological accuracy with physiological variability. Methods: We developed a mathematical model that integrates Gaussian mesa functions (GMF) for waveform generation and a chaotic Rössler attractor to simulate RR-interval variability. The GMF approach allows fine control over the amplitude, width, and slope of each ECG component (P, Q, R, S, T), while the Rössler system introduces dynamic modulation through the use of seven parameters. Spectral and statistical analyses were applied, including power spectral density (PSD) computed via the Lomb–Scargle, STFT, CWT, and histogram analyses. Results: The synthesized signals demonstrated physiological realism in both the time and frequency domains. The LF/HF ratio was 1.5–2.0 when simulating a normal rhythm and outside these limits in a simulated stress rhythm, consistent with typical HRV patterns. PSD analysis captured clear VLF (0.003–0.04 Hz), LF (0.04–0.15 Hz), and HF (0.15–0.4 Hz) bands. Histogram distributions showed amplitude ranges consistent with real ECGs. Conclusions: The hybrid GMF–Rössler approach enables large-scale ECG synthesis with controllable morphology and realistic HRV. It is computationally efficient and suitable for artificial intelligence training, diagnostic testing, and digital twin modeling in cardiovascular applications. Full article

A 3D printing filament was fabricated from poly(lactic acid) (PLA), cassava pulp (CP), and epoxy using a twin-screw extruder. Several bio-composites were synthesized by varying the amount of epoxy (0.5, 1.0, 3.0, 5.0, and 10.0 wt.%). The size of the CP fibers significantly affected the surface quality, filament diameter, and mechanical properties of the final product. The smallest fiber size (45 µm) provided a smooth surface and consistent diameter. Incorporating 1 wt.% of epoxy into PLA/CP enhanced the tensile strength (56.6 MPa), elongation at break (6.2%), and hydrophobicity of the composite. The composite mechanical properties deteriorated at epoxy contents above 1 wt.% due to the amplified plasticizer effect of excessive epoxy. The optimized PLA/CP/epoxy formulation was used to generate the 3D filament. The resultant filament displayed a tensile strength of 64.6 MPa and elongation at break of 9.8%, attributed to the fine morphology achieved via thorough mixing provided by the twin-screw extruder. Epoxide-mediated crosslinking between PLA and CP enabled the development of a novel 3D printing filament with excellent mechanical properties. This research illustrates how agricultural residues can be upcycled into high-performance biomaterials with innovation in sustainable manufacturing, inclusive economic growth, reducing reliance on petroleum-based plastics and thus providing benefits regarding human health, climate change mitigation, plastic in the ocean, and environmental impacts. Full article

Understanding suspended sediment transport in macrotidal embayments is crucial for assessing water quality, ecosystem function, and long-term morphological stability. This study provides a high-resolution, localized estimate of suspended sediment flux and examines the empirical relationship between turbidity (NTU, nephelometric turbidity unit) and total suspended matter (TSM, mg·L⁻¹) in the main tidal channel of Gomso Bay, a UNESCO-designated tidal flat on the west coast of Korea. A 13 h high-resolution fixed-point observation was conducted during a semi-diurnal tidal cycle using a multi-instrument platform, including an RCM, CTD profiler, tide gauge, and water sampling for gravimetric TSM analysis. Vertical measurements at the surface, mid, and bottom layers, taken every 15–30 min, revealed a strong linear correlation (R² = 0.94) between turbidity and TSM, empirically validating the use of optical sensors for real-time sediment monitoring under the highly dynamic conditions of Korean west-coast tidal channels. The net suspended sediment transport load was estimated at approximately 5503 kg·m⁻¹, with ebb-dominant residual currents indicating a net seaward sediment flux at the observation site. Residual flows over macrotidal channels are known to vary laterally, with landward fluxes often occurring over shoals. Importantly, the results from this single-station, short-duration observation indicate a predominantly seaward suspended sediment transport during the study period, which should be interpreted as a localized and time-specific estimate rather than a bay-wide characteristic. Nevertheless, these findings provide a baseline for assessing sediment flux and contribute to future applications in digital twin modeling and coastal management. Gomso Bay is part of the UNESCO-designated ‘Getbol, Korean Tidal Flats’, underscoring the global significance of preserving and monitoring this dynamic coastal system. Full article

Environmental concerns about plastic waste have increased interest in biobased and biodegradable polymers such as polylactic acid (PLA) and polybutylene succinate (PBS). Blending PLA and PBS can provide a balanced performance, offsetting the PLA’s brittleness. PLA/PBS can be processed either via single-screw extrusion (SSE) or twin-screw extrusion compounding followed by SSE (TSSE). This study aims at a comprehensive investigation of these two processing routes and assesses their impact on the physical, morphological, and mechanical properties of PLA/PBS blends. The results indicate that while both routes produce blends with comparable overall performance, subtle differences exist in the degradation behavior of PLA and the morphology of the blends. The PLA molecular weight drop was more pronounced in TSSE (~18.7%) compared to SSE (~1.5%). In both processing routes, PBS exhibited sub-micrometer domains below 15 wt.% loading, beyond which a distinct sea–island morphology with larger PBA domains was observed. TSSE exhibited slightly finer PBS domains. However, these differences did not lead to significant mechanical performance or miscibility differences. For instance, with 15 wt.% PBS loading, the elongation at break was improved from 4.6% to 193% in SSE15 and 192% in TSSE15, with a 29% and 30% decrease in yield strength, respectively. This work suggests that the single-step SSE process can be used as a cost-effective and energy-saving approach in PLA/PBS blending without the need for pre-compounding. Full article

This study proposes an enhanced deep learning framework for accurate detection of P-peaks in noisy photoplethysmographic (PPG) signals, utilizing a hybrid architecture that integrates wavelet-based analysis with neural network components. The P-peak detection task is formulated as a binary classification problem, where the model learns to identify the presence of a peak at each time step within fixed-length input windows. A temporal attention mechanism is incorporated to dynamically focus on the most informative regions of the signal, improving both localization and robustness. The proposed architecture combines Discrete Wavelet Transform (DWT) for multiscale signal decomposition, Convolutional Neural Networks (CNNs) for morphological feature extraction, and Long Short-Term Memory (LSTM) networks for capturing temporal dependencies. A temporal attention layer is introduced after the recurrent layers to enhance focus on time steps with the highest predictive value. An evaluation was conducted on 30 model variants, exploring different combinations of input types, decomposition levels, and activation functions. The best-performing model—Type30, which includes DWT (3 levels), CNN, LSTM, and attention—achieves an accuracy of 0.918, precision of 0.932, recall of 0.957, and F1-score of 0.923. The findings demonstrate that attention-enhanced hybrid architectures are particularly effective in handling signal variability and noise, making them highly suitable for real-world applications in wearable PPG monitoring, digital twins for Heart Rate Variability (HRV), and intelligent health systems. Full article

This manuscript investigates the effect of MWCNT addition on the morphological and water absorption properties of bio-based polyester nanocomposites made from PLA and PBS. The nanocomposites were produced by the melt-mixing method using a twin-screw extruder. An analysis of the percentage by mass of water absorbed was used to determine the absorption properties of polyesters. The addition of MWCNTs to the polyester matrix is a big challenge because agglomerated MWCNTs can introduce micro-voids and defects that act as a channel for water permeation. The SEM images show that the polyester fracture surface becomes rough with several voids after the addition of MWCNTs. The water absorption properties of bio-based polyesters such as PBS show significant changes (an increase of 185%) compared to pure PBS. These findings reveal that the addition of MWCNTs in a small amount (1 wt%) affects the morphology and water absorption capacity of bio-based polyesters. Full article

Lyophilization (freeze-drying) has become a cornerstone pharmaceutical technology for stabilizing biopharmaceuticals, overcoming the inherent instability of biologics, vaccines, and complex drug formulations in aqueous environments. The appropriate literature for this review was identified through a structured search of several databases (such as PubMed, Scopus) covering publications from late 1990s till date, with inclusion limited to peer-reviewed studies on lyophilization processes, formulation development, and process analytical technologies. This succinct review examines both fundamental principles and cutting-edge advancements in lyophilization technology, with particular emphasis on Quality by Design (QbD) frameworks for optimizing formulation development and manufacturing processes. The work systematically analyzes the critical three-stage lyophilization cycle—freezing, primary drying, and secondary drying—while detailing how key parameters (shelf temperature, chamber pressure, annealing) influence critical quality attributes (CQAs) including cake morphology, residual moisture content, and reconstitution behavior. Special attention is given to formulation strategies employing synthetic surfactants, cryoprotectants, and stabilizers for complex delivery systems such as liposomes, nanoparticles, and biologics. The review highlights transformative technological innovations, including artificial intelligence (AI)-driven cycle optimization, digital twin simulations, and automated visual inspection systems, which are revolutionizing process control and quality assurance. Practical case studies demonstrate successful applications across diverse therapeutic categories, from small molecules to monoclonal antibodies and vaccines, showcasing improved stability profiles and manufacturing efficiency. Finally, the discussion addresses current regulatory expectations (FDA/ICH) and compliance considerations, particularly regarding cGMP implementation and the evolving landscape of AI/ML (machine learning) validation in pharmaceutical manufacturing. By integrating QbD-driven process design with AI-enabled modeling, process analytical technology (PAT) implementation, and regulatory alignment, this review provides both a strategic roadmap and practical insights for advancing lyophilized drug product development to meet contemporary challenges in biopharmaceutical stabilization and global distribution. Despite several publications addressing individual aspects of lyophilization, there is currently no comprehensive synthesis that integrates formulation science, QbD principles, and emerging digital technologies such as AI/ML and digital twins within a unified framework for process optimization. Future work should integrate advanced technologies, AI/ML standardization, and global access initiatives within a QbD framework to enable next-generation lyophilized products with improved stability and patient focus. Full article

The production of polymer nanocomposites from supertough blends reinforced with carbon-based nanofillers has garnered attention in recent years due to improvements in their mechanical, thermal, and electrical properties. Currently, the main challenge is to develop materials with balanced performance for diverse industrial demands. In this context, this work aimed to produce nanocomposites of poly(butylene terephthalate) (PBT) and poly(ethylene-octene) grafted with glycidyl methacrylate (POE-g-GMA), reinforced with carbon nanotubes (MWCNTs). The PBT, the PBT/POE-g-GMA blend, and the respective MWCNT nanocomposites were initially premixed in an internal mixer and then processed in a co-rotational twin-screw extruder. After processing, they were injection-molded to obtain tensile, impact, and HDT test specimens. Mechanical (tensile, impact, and Shore D hardness), thermal (differential scanning calorimetry—DSC), thermomechanical (heat deflection temperature—HDT), electrical resistivity/conductivity, morphology, and Fourier transform infrared spectroscopy (FTIR) properties were evaluated. The results demonstrated a good balance among the investigated properties, with improvements in mechanical, thermal, and thermomechanical properties when compared to PBT. The impact strength of the nanocomposites reached 186 J/m, approximately 158% higher than that of neat PBT. The HDT reached approximately 55 °C in the PBT/POE-g-GMA/MWCNT5 nanocomposites, while the crystallization temperature increased by 11 °C, as evidenced by DSC, an aspect of great relevance for industrial applications. Furthermore, the PBT/POE-g-GMA/MWCNT5 nanocomposites exhibited an electrical conductivity of 1.06 × 10⁻⁷ S/cm, indicating potential for electrical applications. Full article