Search Results (3,520)

Integral abutment bridges (IABs) are increasingly adopted in transportation infrastructure due to their durability, reduced maintenance needs, and cost-effectiveness compared to conventional bridges. However, their reliable performance under live loads is strongly influenced by the nonlinear soil–structure interaction (SSI) at the pile–abutment joint, which remains challenging to quantify using conventional analysis methods. This study develops simplified spring-based models to capture the SSI behavior of pile–abutment joints in short-span IABs. Predictive equations for joint rotation, deflection, moment, and shear are formulated using Linear Regression (LR) and Response Surface Methodology (RSM). Unlike prior studies relying solely on FEM or traditional p–y curves, the novelty of this work lies in deriving regression-based spring constants calibrated against FEM analyses, which can be directly implemented in standard structural software. This approach significantly reduces computational demands while maintaining predictive accuracy, enabling efficient assessment of pile contributions and global bridge response. Validation against finite element method (FEM) results confirms the reliability of the simplified models, with RSM outperforming LR in representing nonlinear parameter interactions. Full article

In response to the growing demand for automation in aerospace harness manufacturing, this study proposes a digital twin-based intelligent monitoring system for robotic wiring operations. The system integrates a seven-degree-of-freedom robotic platform with an adaptive servo gripper and employs a five-dimensional digital twin framework to synchronize physical and virtual entities. Key innovations include a coordinated motion model for minimizing joint displacement, a particle-swarm-optimized backpropagation neural network (PSO-BPNN) for adaptive gripping based on wire characteristics, and a virtual–physical closed-loop interaction strategy covering the entire wiring process. Methodologically, the system enables motion planning, quality prediction, and remote monitoring through Unity3D visualization, SQL-driven data processing, and real-time mapping. The experimental results demonstrate that the system can stably and efficiently complete complex wiring tasks with 1:1 trajectory reproduction. Moreover, the PSO-BPNN model significantly reduces prediction error compared to standard BPNN methods. The results confirm the system’s capability to ensure precise wire placement, enhance operational efficiency, and reduce error risks. This work offers a practical and intelligent solution for aerospace harness production and shows strong potential for extension to multi-robot collaboration and full production line scheduling. Full article

Underwater wireless communication (UWC) is an emerging technology crucial for automating marine industries, such as offshore aquaculture and energy production, and military applications. It is a key part of the 6G vision of creating a hyperconnected world for extending connectivity to the underwater environment. Of the three main practicable UWC technologies (acoustic, optical, and radiofrequency), acoustic methods are best for far-reaching links, while optical is best for high-bandwidth communication. Recently, utilizing reconfigurable intelligent surfaces (RISs) has become a hot topic in terrestrial applications, underscoring significant benefits for extending coverage, providing connectivity to blind spots, wireless power transmission, and more. However, the potential for further research works in underwater RIS is vast. Here, for the first time, we conduct an extensive survey of state-of-the-art of RIS and metasurfaces with a focus on underwater applications. Within a holistic perspective, this survey systematically evaluates acoustic, optical, and hybrid RIS, showing that environment-aware channel switching and joint communication architectures could deliver holistic gains over single-domain RIS in the distance–bandwidth trade-off, congestion mitigation, security, and energy efficiency. Additional focus is placed on the current challenges from research and realization perspectives. We discuss recent advances and suggest design considerations for coupling hybrid RIS with optical energy and piezoelectric acoustic energy harvesting, which along with distributed relaying, could realize self-sustainable underwater networks that are highly reliable, long-range, and high throughput. The most impactful future directions seem to be in applying RIS for enhancing underwater links in inhomogeneous environments and overcoming time-varying effects, realizing RIS hardware suitable for the underwater conditions, and achieving simultaneous transmission and reflection (STAR-RIS), and, particularly, in optical links—integrating the latest developments in metasurfaces. Full article

This study looks at the role of foreign finance in promoting the shift to renewable energy in the Developing-8 (D8) countries—Bangladesh, Egypt, Indonesia, Iran, Malaysia, Nigeria, Pakistan, and Turkey—between 2000 and 2023, with particular focus given to the moderating role of globalization. Utilizing an unbalanced panel dataset covering eight D8 countries over 2000–2023 and applying advanced econometric techniques, including System-GMM, Common Correlated Effects, nd Driscoll–Kraay estimators, the analysis accounts for slope heterogeneity, cross-sectional dependence, and possible endogeneity. The results indicate that foreign finance, and particularly foreign direct investment (FDI), is highly significant in enhancing the supply and demand of renewable energy. Globalization also has an amplification effect as it spurs technology transfer, policy convergence, and market access. The combined impact of foreign finance and globalization is significant and positive in all specifications, indicating that the optimal benefits of foreign capital inflows are realized in highly integrated economies. Alternative globalization measures and tests of renewable energy robustness confirm the stability of the findings. It argues that institutionally reinforcing the foundations, strengthening global integration, and channeling foreign finance into green sectors are central policies for fostering renewable energy transitions in developing economies. This paper provides three contributions to the existing literature. First, it is the pioneering paper that examines systematically the moderating function of globalization on the foreign finance–renewable energy transition nexus in the D8 economies. Second, it applies the latest econometric techniques—System-GMM, CCE, and Driscoll–Kraay—that control for slope heterogeneity, cross-sectional dependence, and endogeneity. Third, it offers policy recommendations for emerging economies on how best to mobilize foreign finance in a globalization context. Unlike prior works that examine these dimensions separately, this study highlights their joint influence, thereby contributing a dual perspective that has been largely absent from the literature. Full article

Employing commercial off-the-shelf coherent optical transmission components and methods to design a continuous variable quantum key distribution (CVQKD) system is a promising trend of achieving QKD with high security key rate (SKR) and cost-effectiveness. In this paper, we explore a CVQKD system based on the widely used polarization division multiplexed (PDM) coherent optical transmission structure and pilot-aided digital signal processing methods. A simplified pilot-aided phase noise compensation scheme based on frequency division multiplexing (FDM) is proposed, which introduces less total excess noise than classical pilot-aided schemes based on time division multiplexing (TDM). In addition, the two schemes of training symbol (TS)-aided equalization are compared to find the optimal strategy for TS insertion, where the scheme based on block insertion strategy can provide the SKR gain of around 29%, 22%, and 15% compared with the scheme based on fine-grained insertion strategy at the transmission distance of 5 km, 25 km, and 50 km, respectively. The joint optimization of pilot-aided and TS-aided methods in this work can provide a reference for achieving a CVQKD system with a high SKR and low complexity in metropolitan-scale applications. Full article

Osteoarthritis (OA) is one of the most common forms of arthritis and is commonly characterized by the breakdown of the hyaline cartilage and synovial fluid in joints. The body naturally responds by releasing proteins with specific functions to combat the degradation of the joint. The objective of the research undertaken in this study was to simulate a selection of these proteins from previous work in the literature to gather data on their energies. This was accomplished using the molecular dynamics software NAMD and VMD, in which each protein was simulated for 5 ps in water at three different temperatures. The simulations showed that at body temperature, orosomucoid-1 and complement component 4B had energies that stabilized significantly faster than the other proteins simulated, and alpha-2-macroglobulin had energies that stabilized significantly slower than the others. These outliers were further investigated by simulating them for 1 ns to reveal their molecular dynamics. Based on the data collected, it was proposed that the proteins that had faster stabilization times would be more stable biomarkers overall. Despite any limitations of the research performed, the novel work performed here provides a foundation for future work that could give clinical insight into the diagnosis and prognosis of individuals experiencing symptoms associated with osteoarthritis. Full article

Scaffolds are temporary structures that workers usually use during building or repair work. These structures can be built in different shapes and types depending on the type of joints to which the beams and columns of the scaffolds are connected. Due to their temporary nature, they are very sensitive to vibration under dynamic or static actions, and this causes many accidents and unstable behaviours in them. This unstable behaviour has different reasons, including bracing conditions and slenderness of the columns, stiffness of joints and anchors, imperfections in the construction, damage and corrosion due to climate change, etc. This article aims to reanalyse the mechanical properties of scaffold joints and anchors and obtain some critical factors in the overall stability of the mentioned structures, including load-bearing capacity, initial stiffness, energy absorption, and ductility. To this aim, some recent research on scaffolds has been summarised and discussed, and then the failure mode and mechanical behaviour of the scaffolds in different types of scaffold joints and anchors have been estimated and considered from previous studies. Moreover, some mechanical properties, including ductility, initial stiffness, and energy absorption, have been estimated and developed based on the force-displacement curves of previous studies. The results highlight the crucial importance of the mechanical properties and behaviour of anchors and joints in estimating the behaviour and stability of scaffolds. The results also revealed that determining the mechanical characteristics of the mentioned elements can have a significant influence on the optimisation and design of scaffolds more accurately and predictably. Moreover, determining the mechanical properties of the anchors and joints can enhance our insights and understanding of how the mentioned parameters can improve the behaviour, stability, and safety of the scaffold structures. Full article

Objectives: The objective of this study was to compare occlusal and articular characteristics between young adults with and without a confirmed diagnosis of sleep bruxism, through a case-control study based on polysomnography. Methods: We conducted a case–control study with probabilistic sampling, including 20 participants with a polysomnography-confirmed diagnosis of sleep bruxism and 20 age- and sex-matched controls. A clinical oral examination was conducted to identify wear facets, joint sounds, and soft tissue indentations. Occlusal relationships were analyzed using mounted models on a semi-adjustable articulator, evaluating interferences during working, balancing, and protrusive movements, premature contacts, attrition, and dental inclinations. Results: Sleep bruxism showed a higher frequency of temporomandibular joint sounds (35% vs. 5%; p = 0.017; w = 0.375) and left-side balancing interferences (p = 0.04; d = 0.723). Multivariate analysis revealed a moderate correlation between bruxism and the combination of joint sound and occlusal inclination (COR = 0.39; 95% CI: 0.19–0.57; I² = 0.0%). Joint sound showed a weak association with REM-related bruxism (COR = 0.29; 95% CI: 0.05–0.51; I² = 21.7%) and a moderate association with non-REM bruxism (COR = 0.41). The correlation with occlusal inclination was stronger during REM sleep (COR = 0.41) than during non-REM sleep (COR = 0.35; I² = 0.0%), indicating consistent and clinically relevant associations. Conclusions: Occlusal and functional characteristics associated with sleep bruxism were identified, particularly joint sounds and dental inclinations, although no direct causal relationship was established. These findings suggest the presence of specific morphofunctional patterns that may play a role in the clinical expression of sleep bruxism. Full article

Focusing on the practical application requirements of adhesive-bonded structures in aerospace engineering, this study aims to investigate the mechanical performance and failure mechanisms of adhesive interfaces. Adhesive bonding, valued for its uniform load distribution, low stress concentration, superior sealing, and lightweight properties, serves as a critical joining technology in aerospace engineering. However, its reliable application is constrained by complex multimode failure issues, such as cohesive failure, interfacial debonding, and matrix damage. To address these challenges, a comprehensive evaluation of the novel high-strength epoxy adhesive Dq622JD-136 (Adhesive III) was conducted through systematic tests, including bulk tension, butt joint tension, single lap shear, compressive shear, and fracture toughness (TDCB/ENF) tests. These tests characterized its mechanical properties and fracture behavior under mode-I and mode-II loading, with comparative analyses against conventional adhesives HYJ-16 (Adhesive I) and HYJ-29 (Adhesive II). Key findings reveal that Adhesive III exhibits outstanding elastic modulus, significantly outperforming the comparative adhesives. While its normal and shear strengths are slightly lower than Adhesive I, they surpass Adhesive II. A common characteristic across all adhesives is that normal strength exceeds shear strength. In terms of fracture toughness, Adhesive III demonstrates superior mode-II toughness but relatively lower mode-I toughness. These results elucidate the brittle characteristics of such adhesives, mixed failure modes under normal loading, and cohesive failure behavior under shear loading. The innovation of this work lies in systematically correlating the macroscopic performance of adhesives with failure mechanisms through multi-dimensional testing. Its findings provide critical technical support for multiscale performance evaluation and adhesive selection in aerospace joints subjected to extreme thermomechanical loads. Full article

The huge growth in the utilisation of six-axis robots in various technological applications in production calls for a detailed focus on the process of preparing Numerical Control (NC) programmes for effective robot control. Considerable attention is currently being paid to optimisation by increasing stiffness, but there is also a need to focus on reducing energy consumption in robot control. Focusing on reducing energy consumption is highly justified given the widespread adoption of robotic systems across diverse manufacturing technologies and the significant potential for application. This is particularly relevant today, when minimising production costs is a critical industrial objective. A redundant degree of freedom—which is the possibility to rotate around the end-effector axis and thus influence the adjustment of the rotation of the individual robot joints—can be used for this purpose. Therefore, this paper exploits this redundant degree of freedom to set up a proper robot configuration that reduces energy consumption. The user-friendly solution, including the algorithm design and processing through a function, could be effectively implemented within an industry-standard post-processor solution for generating NC programmes for robots. This solution is unique as it is used for the optimisation of the working section of the toolpaths, where continuous control of the end-effector movement during manufacturing operations occurs. The solution was verified on a KUKA KR60 HA robot; however, it is applicable to any industrial six-axis robot. Substantial energy savings were obtained in multi-axis toolpath operations, with a 7.5% reduction in total energy consumption when using the optimised NC programme. Full article

Inclusion is a process of social transformation that is profoundly shaping the field of early childhood education. According to a narrow understanding of inclusion, the focus is on the joint participation of children with and without disabilities in general educational settings. How preschool teachers perceive and facilitate the inclusion of children with disabilities in this context depends significantly on their understanding of disability. This study therefore explores preschool teachers’ perspectives on the construct of disability. The data are based on interviews with n = 21 preschool teachers working in German preschools. The results show that teachers partially view disabilities as individual deficits of the child, partially as consequences of inadequate environmental conditions, and partially as something to be avoided and deconstructed. Most teachers combine multiple understandings of disability. Overall, the results indicate that a significant number of teachers hold a mindset shaped by the assumption of two distinct groups: those with and those without disabilities (dual-group theory). The results are discussed in the context of current debates on educational inclusion and the dual-group theory. Full article

Ultrasonic welding is an efficient and precise joining technology widely applied in aerospace, electronics, and medical industries. To overcome the limitations of conventional oscillators in high-frequency applications, this study proposes an innovative cylindrical oscillator design incorporating a 3.71 mm acoustic matching layer, operating at 1.76 MHz based on acoustic propagation theory. Through finite element analysis, a miniaturized oscillator with dimensions of 28 mm in diameter and 18 mm in height was developed, achieving optimized dynamic performance. Experimental validation via laser Doppler vibrometry confirmed a working surface amplitude exceeding 50 nm, while vibrations on non-functional walls were suppressed below 5 nm, with less than 5% deviation from simulation results. Prototype welding tests identified optimal process parameters—85 N welding pressure, 4 s welding time, and 3 s holding time—resulting in PVC joint tensile strengths exceeding 45 N. This work provides both an optimized hardware design and validated process guidelines, advancing the application of high-frequency micro-ultrasonic welding in precision, space-constrained environments. Full article

This research proposes a non-penetration lap welding process for joining T2 copper power module terminals in high-frequency and high-power electronic applications, using a hybrid laser system combining a 445 nm blue diode laser and a 1080 nm fiber laser. The composite laser beam, formed by coupling a circular blue laser beam with a spot-shaped fiber laser beam, was oscillated along circular, sinusoidal, and 8-shaped trajectories to control weld geometry and joint quality. Results indicate that all trajectories produced U-shaped weld cross-sections with smooth toe transitions and good surface quality. Specifically, the circular trajectory provided uniform energy distribution and stable weld formation; the 8-shaped trajectory achieved a balanced width-to-depth ratio; and the sinusoidal trajectory exhibited sensitivity to welding speed, often resulting in uneven fusion width. Increased welding speed promoted grain refinement, but excessive speed led to porosity and poor surface quality in both 8-shaped and sinusoidal trajectories. Oscillating laser welding facilitated equiaxed grain formation, with the circular and 8-shaped trajectories yielding more uniform microstructures. The circular trajectory maintained consistent weld dimensions and hardness distribution, while the 8-shaped trajectory exhibited superior tensile strength. This work highlights the potential of circular and 8-shaped trajectories in hybrid laser welding for regulating weld microstructure, enhancing mechanical performance and ensuring weld stability. Full article

With aging, harsh working conditions or sports injuries, the meniscus can degrade, causing pains to the patient. Nowadays, the treatment consists of the surgical replacement of this cartilage. Since this procedure can lead to complications due to open wounds and potential infections, synthesizing a polyurethane-based injectable joint filler represents an interesting alternative. In this study, poly(δ-decalactone)triol oligomers and Lysine diisocyanate were chosen as starting monomers to create an isocyanate-based prepolymer, because of their biocompatibility and liquid state at room temperature. Nevertheless, to fully replace the meniscus, the joint filler must crosslink in vivo, and this should occur in a short time window. Accordingly, in this work, we studied the catalytic activity of a range of relatively safe compounds for the alcohol/isocyanate addition reaction. A preliminary ¹H NMR kinetic study of the catalyzed addition of 1-butanol or 3-pentanol on lysine diisocyanate ethyl ester at body temperature has been performed to reach this objective. Among catalysts, stannous octoate was the most effective with either primary or secondary alcohol, allowing them to reach 92 and 80% alcohol conversion, respectively. In addition, the conversion of the primary and secondary isocyanates of lysine diisocyanate ethyl ester was monitored for all the catalysts and revealed different behaviors depending on the catalyst employed. Stannous octoate, unlike the others, showed a similar reactivity for primary and secondary isocyanates with conversions of 49 and 47%, respectively. Finally, when employing the most effective catalyst, curing of the poly(δ-decalactone) triisocyanate with glycerol at 35 °C provided a polyurethane elastomer that exhibits an elastic modulus of 519 kPa and a swelling index lower than 3% in PBS, making it suitable for injectable polyurethane joint filler application. Full article

Characterizingthe spatial variability of agricultural data is a fundamental step in precision agriculture, especially in soil management and the creation of differentiated management units for increasing productivity. Modeling the spatial dependence structure using geostatistical methods is of great importance for efficiency, estimating the parameters that define this structure, and performing kriging-based interpolation. This work presents diagnostic techniques for global and local influence and generalized leverage using the displacement of the conditional expectation of the logarithm of the joint-likelihood, called the Q-function. This method is used to identify the presence of influential observations that can interfere with parameter estimations, geostatistics model selection, map construction, and spatial variability. To study spatially correlated data, we used reparameterized t-Student distribution linear spatial modeling. This distribution has been used as an alternative to the normal distribution when data have outliers, and it has the same form of covariance matrix as the normal distribution, which enables a direct comparison between them. The methodology is illustrated using one real data set, and the results showed that the modeling was more robust in the presence of influential observations. The study of these observations is indispensable for decision-making in precision agriculture. Full article