Search Results (450)

The ubiquity of resource-constrained Internet-of Things (IoT) nodes creates an urgent demand for network intrusion detection systems (NIDSs) optimized for edge devices with limited computing power. In this paper, we propose a new NIDS system based on Mamba. NIDS-Mamba uses a dynamic sparse attention and a lightweight state space to jointly learn from short-term anomaly and long-term attack patterns. We use standardized NF-UNSW-NB15 and NF-CSE-CIC-IDS2018 datasets to verify the effectiveness of this NIDS-Mamba model. We find that this NIDS-Mamba model is very effective in dealing with extreme class imbalance problems. In the NF-CSE-CIC-IDS2018 dataset, the model achieves 98.32% accuracy, 96.98% F1-score, and an AUC of 0.9996. Most notably, the model is very robust in handling extreme class imbalance problems in the NF-UNSW-NB15 dataset. It achieves 97.03% G-Mean, 0.7915 MCC, and 0.9983 AUC, far exceeding other baseline models. Compared to Transformer-based baselines, NIDS-Mamba achieves nearly an order-of-magnitude improvement in throughput while maintaining a parameter footprint compatible with edge deployment constraints. The proposed architecture effectively mitigates the quadratic complexity and memory wall inherent in standard Transformers, ensuring compatibility with Limited RAM and strict energy constraints. The proposed model achieves a compact design with 1.12 million parameters and a peak inference memory of 5.4 MB, ensuring its feasibility for edge-based IoT nodes. These properties make NIDS-Mamba a strong candidate for deployment on IoT gateways and edge sensor nodes in smart home, industrial IoT, and critical infrastructure scenarios. Full article

Glass curtain walls are widely used in the enclosure structure of airport terminals due to their advantages of lightweight and beautiful appearance, good lighting, and easy installation. However, coastal areas are constantly affected by typhoons, and under the influence of strong winds, complex pressure distributions are generated on the surface of curtain walls. Therefore, studying the wind pressure distribution characteristics of glass curtain walls is crucial for the structural safety and durability of coastal airport terminals. Based on this, accurately predicting wind pressure distribution not only helps to improve the design safety of airport terminals but also effectively prevents potential damage under strong wind conditions. To achieve effective prediction of wind pressure on glass curtain walls, this paper adopts a combination of wind tunnel tests and neural network prediction models. Real wind pressure coefficient data is obtained through wind tunnel tests, and a CNN–Transformer combination model is proposed to predict wind pressure coefficients. The results show that the prediction accuracy of the combined model is higher than that of the CNN and Transformer single models. MAE is optimized by 0.04~0.10 compared with the former and 0.16~0.34 compared with the latter; RMSE has been optimized by 0.02–0.10 and 0.30–0.34, respectively. This article can provide reference for the prediction research of wind pressure on the surface of glass curtain walls in airport terminals. Full article

Aiming at the problems of cumbersome parameter tuning and low computational efficiency in traditional methods for the bandgap optimization of periodic thin-walled stiffened coupled structures, this paper integrates the null-space method with the Kirchhoff thin-plate theory to establish an efficient model for bandgap analysis. The proposed method realizes matrix-based construction of coupled and periodic boundary conditions, decouples boundary constraints from displacement shape functions, avoids the limitations of virtual spring stiffness, and requires no remeshing during parameter variation. Comparisons with the finite element method verify its convergence and accuracy: the average deviation of bandgap widths in the 0–250 Hz range is 0.37 Hz, and the computational efficiency is about 2.5 times that of FEM(Finite Element Method). This paper also systematically analyzes the effects of four key parameters, including thin-wall thickness, stiffener thickness, stiffener height and stiffener spacing, on the number and width of bandgaps and proposes targeted optimization strategies for different engineering scenarios. The results provide a new method for vibration and noise reduction design of such structures and lay a foundation for future bandgap modeling and optimization of advanced lightweight periodic structures. Full article

Planar honeycomb structures, especially biomimetic hexagonal honeycombs, are widely used in energy-absorbing equipment because of their excellent out-of-plane deformation resistance. However, their significant mechanical anisotropy, manifested by the large discrepancy between out-of-plane and in-plane responses, greatly restricts their broader applications. Inspired by spiral-reinforced thin-walled biological tubular systems, such as animal tracheae and plant vessels, this study proposes a biomimetic reinforcement strategy by embedding spiral structures along the thin walls of planar honeycombs. To validate the feasibility of the proposed design, biomimetic honeycomb specimens were fabricated using 3D-printing technology and tested under compression along different loading directions. Furthermore, a numerical model validated against the experiments was developed to reveal the underlying enhancement mechanism. The results demonstrate that the proposed biomimetic honeycomb preserves the favorable out-of-plane performance of the conventional hexagonal honeycomb, while improving the in-plane energy absorption capacity by up to 70%. The biomimetic spiral reinforcements enable more effective load transfer under multidirectional loading, resulting in a more uniform plastic stress distribution over the entire structure and activating a larger deformation region for energy dissipation. The present work provides a bioinspired strategy for developing lightweight energy-absorbing structures for potential applications in aerospace, rail vehicles, marine engineering, and civil structures. Full article

Rectangular waveguides, serving as a standardized versatile platform for manipulating terahertz radiation within controlled environments, have been extensively employed across a broad range of terahertz systems. However, conventional fabrication methods encounter significant challenges in realizing such submillimeter-scale structures within a monolithic integration, particularly when subwavelength features or intricate geometries are incorporated for advanced functionalities. In this work, we propose a fabrication route integrating stereolithography 3D printing and electroless plating, and demonstrate its broad applicability, intrinsic benefits and limitations through the realization of various high-performance D-band terahertz rectangular waveguides and antennas. The resulting rectangular waveguides achieve an insertion loss below 0.3 dB and a return loss above 15 dB across the D-band, while remaining stable across extreme temperatures (−50 °C to 150 °C) and offering a weight reduction of over 60%. A monolithically fabricated smooth-walled conical horn antenna exhibits beam-shaping characteristics that closely align with theoretical expectations. Attempts on corrugated horn antennas in conventional design reveal degraded performance, primarily arising from the inherent staircase effect associated with 3D printing. A novel design featuring obliquely oriented corrugations is developed, effectively mitigating uncontrolled deformation in periodic subwavelength features. Compared with the classical corrugated design (θ = 90°), the proposed obliquely oriented corrugations (θ = 30°) improve the agreement between experimental and theoretical radiation patterns, reducing the gain deviation from 1.45 dB to less than 0.5 Db—a quantitative improvement of over 60% in pattern fidelity. We believe that this fabrication route together with the process-adaptive design paradigm establishes a robust technical foundation for realizing high-performance, lightweight, and design-flexible terahertz waveguide components and holds significant promise for advancing the development of next-generation integrated terahertz systems. Full article

This study proposes a novel parameterized hollow spiral lattice (HSL) structure designed for additive manufacturing (AM). The structure is composed of two right-handed and two left-handed spiral members. Its unit cell is formed by sweeping a circular ring cross-section along a cylindrical helical path, creating a porous topology that integrates continuous flow channels with structural load-bearing capability. An analytical model correlating key design parameters, including spiral radius, helix angle, and tube inner/outer diameters, with the structural relative density is established. Considering the manufacturability constraints of Laser Powder Bed Fusion (LPBF), an adaptive parametric design framework is developed to simultaneously optimize the geometry, relative density, and process feasibility. Ti6Al4V HSL samples were fabricated using LPBF. Their thermo–mechanical performance was systematically characterized through Computational Fluid Dynamics (CFD) simulations, Finite Element Analysis (FEA), and quasi-static compression experiments. Thermal analysis under internal and internal–external flow conditions reveals that the centrifugal force induced by the spiral geometry generates Dean vortices. This enhances momentum exchange between the central mainstream and near-wall fluid, significantly improving radial mixing, promoting temperature uniformity, and effectively suppressing local hot spots. Mechanically, the HSL exhibits significantly superior specific strength and stiffness compared to traditional body-centered cubic (BCC) and diamond lattices, approaching the performance of cubic topology, thus demonstrating outstanding lightweight load-bearing potential. The developed HSL structure presents a promising innovative design strategy for next-generation applications requiring integrated thermal management and structural load-bearing functions. Full article

Background/Objectives: Hernia and pelvic organ prolapse often involve defects necessitating reinforcement with synthetic materials. Polypropylene meshes of varying weights are commonly used in abdominal wall repair; however, their impact on tissue response, potentially linked to adverse events during wound healing, remains incompletely understood. This study aimed to evaluate and compare the tissue response to lightweight polypropylene (LWPP) and heavyweight polypropylene (HWPP) grafts used for abdominal wall defect closure in Wistar rats. Methods: Abdominal wall defects were surgically created in male Wistar rats and repaired using either LWPP (43 g/m²) or HWPP (76 g/m²) mesh. Three weeks post-implantation, tissue response and wound closure were evaluated across different phases by assessing expression of CD68, CD56, GATA-3, CD138, vimentin, α-smooth muscle actin, and collagen deposition. Results: HWPP promoted a more pronounced foreign body response, as evidenced by increased CD68, CD56, and CD138 expression, while LWPP improved tissue compliance, enhanced fibroblast migration, and increased vimentin-associated cellular activity. Conclusions: Three weeks post-implantation, HWPP was found to induce a stronger inflammatory response, whereas LWPP implantation was associated with increased vimentin expression, indicating differences in the balance between inflammation and extracellular matrix remodelling during early wound healing. Full article

Utilizing excavated waste soil to level gullies offers significant advantages in terms of engineering economy and construction efficiency. However, the stability and deformation risks of high-fill embankments in mountainous gullies under rainfall conditions have attracted significant attention, particularly when such structures are located adjacent to residential areas. This study compares two design schemes for highway high-fill embankments, Scheme 1: high-fill slope supported by stabilizing piles and prestressed anchors, and Scheme 2: ordinary waste soil as the core, foamed lightweight soil (EPS) as the edge band, and reinforcement by a micro-pile retaining wall system. Finite element analysis was used to evaluate the Factor of Safety (FOS), displacements of retaining structures, and characteristic slope points under three conditions (no rainfall, heavy rainfall, and heavy rainfall with soil strength deterioration). The results show that Scheme 2 reduces total costs by 3.5%, shortens the construction period by 14%, and cuts maintenance costs by 65%, with a minimum FOS of 1.56 under extreme rainfall. Further parametric analysis of Scheme 2 optimized key design parameters, and field monitoring data over 6 months verified the reliability of the numerical simulation. This study provides a transferable design-verification pathway for combining lightweight and conventional fills in high embankments, offering technical support for similar projects in complex mountainous areas. Full article

This study presents a comprehensive numerical investigation into the combined bending–shear behaviour of hollow-flanged cold-formed steel (HFCFS) beams filled with lightweight concrete (LWC). Although previous research has independently examined the pure bending and pure shear responses of these composite members, their structural performance under simultaneous bending and shear remains unexplored. In this work, advanced three-dimensional finite element (FE) models were developed in ABAQUS to simulate the nonlinear behaviour of LWC-filled HFCFS beams subjected to various shear-span ratios. The modelling approach was validated using published experimental data and extended through a systematic parametric study that considered three beam geometries, two steel yield strengths (350 MPa and 450 MPa), two lightweight-concrete strengths (30 MPa and 50 MPa), and aspect ratios ranging from 1.5 to 3.5. The results demonstrated a clear progression of governing failure modes, from web shear buckling at low aspect ratios to combined shear–flexure interaction at intermediate spans and flexural-dominated failure at larger spans. Normalised shear and bending demand–capacity ratios (V/Vu and M/Mu) were used to identify the dominant limit state, revealing a predictable transition from shear-controlled to flexure-controlled behaviour. The findings enhance the understanding of composite thin-walled steel–concrete systems under combined actions and highlight the need for dedicated design rules for CF-HFCFS beams operating within the bending–shear interaction domain. Full article

At the end of its last experimental campaign, in December 2023, the Joint European Torus (JET) became available for testing a compact and lightweight Laser-Induced Breakdown Spectroscopy (LIBS) system to be mounted on its robotic arm. The purpose of the test was the in situ chemical characterization of its internal walls and plasma-facing components (PFCs). Among the areas measured, special attention was devoted to the PFCs of the divertor, as this area is most affected by the re-deposition of material eroded from the first wall and unburned nuclear fuel (deuterium and tritium). In this article, we present the results of the LIBS characterization of a PFC of the High Field Gap Closure (HFGC), highly subjected to these phenomena. The in-depth distribution of several ITER-relevant chemical species is discussed through in-depth and correlation analyses, and the interpretation of the results is explained in terms of erosion and re-deposition of materials from the first wall. The study allowed us to estimate the thickness of the ablated layers by each laser shot, which is on the order of a few tens of nanometers, and to outline a mapping of the thickness of the re-deposited material. Full article

Despite the widespread adoption of BIM, information exchange across disciplines remains hindered by heterogeneous structures at the tabular data level, particularly when integrating data across multiple discipline-specific models. Manual mapping, rigid templates, or one-off programming scripts are labor-intensive and difficult to scale, limiting automated querying, cross-model aggregation, and schedule-level analytics. This study proposes a lightweight, workflow-driven approach for semantic normalization and cross-model integration of BIM schedule data, with optional script-supported workflow configuration used only to assist the configuration of deterministic, rule-guided mapping logic, rather than serving as a core analytical method. By introducing a customizable subcategory layer, the workflow enables fine-grained semantic alignment and efficient normalization across diverse schedule datasets, implemented through lightweight Python scripting and rule-guided semantic matching used solely as a supporting mechanism for deterministic field mapping. Using structural, architectural, and HVAC models, we demonstrate a stepwise process including data cleaning, hierarchical classification, consistency checking, batch analytics, and automated computation of cross-model metrics such as opening-to-wall ratios. Sample-based validation confirms the workflow’s reliability, achieving semantic mapping agreement rates above 95% and reducing manual processing time by more than 85%. The workflow is readily extensible to other disciplines and modeling conventions, supporting high-throughput data integration for tasks such as design coordination, semantic alignment, RFI reduction, accelerated design reviews, and data-driven decision making. Overall, rather than introducing a new algorithm, the contribution of this work lies in formalizing a reusable, schedule-level workflow abstraction that enables consistent semantic alignment and automated cross-model aggregation without relying on rigid ontologies or training-intensive learning-based models. Any optional tooling used during workflow configuration is auxiliary and does not constitute a standalone learning-based method requiring model training or performance benchmarking. This provides a reusable methodological foundation for scalable, schedule-level BIM data integration and cross-model analytics. Full article

This study investigates how an internal PCM–gypsum plaster lining modifies orientation-dependent heat transfer through lightweight model house envelopes over a full spring season. Two identical container houses (reference and PCM plastered) were monitored for 105 days under free-floating conditions, and surface temperatures of all opaque elements were processed into characteristic temperature differences and corresponding heat flux densities at daily extrema. The analysis showed that wall and roof orientation strongly governed both the magnitude and variability of these characteristic heat fluxes. West-facing façades and the roof exhibited the highest values due to solar gains and radiative exchanges, while the floor and north wall remained comparatively stable. Under conditions of nearly constant mean wall temperature, the characteristic flux framework revealed that the PCM lining systematically reshaped the temporal distribution of heat transfer and reduced the effective net energy exchange between indoor space and outdoor environment, most notably on solar-exposed west and south walls and on the roof. These orientation-resolved heat flux indicators provided a physically transparent basis for deciding on which envelope surfaces PCM integration could be most advantageous and where its application could be omitted without significantly compromising thermal performance under similar climatic conditions. Full article

Driven by the requirements of lightweight design and efficient impact protection, biomimetic hexagonal honeycomb structures have been widely used for energy absorption. However, their dynamic response and energy absorption behavior in underwater environments remain insufficiently understood. To address this gap, this study investigates the impact response and deformation mechanisms of aluminum honeycomb structures under fully submerged conditions relevant to marine engineering. We fabricated honeycomb cores from 5052-H18 aluminum alloy and developed a custom fixture for fluid–structure interaction tests under underwater drop hammer impact conditions. Using force sensors and high-speed photography, we characterized the dynamic impact behavior through load–time and velocity–time responses. Results demonstrate that drainage holes in the support plate serve a dual function: they enable the structure to maintain stable deformation and absorb energy underwater while also significantly enhancing energy absorption capacity. Specifically, the mean crushing force increases by 156.5%, and the energy absorption capacity increases by 333% compared to performance in air. This enhancement arises from the plastic deformation of cell walls and the additional energy dissipation induced by fluid–structure interaction. Overall, this study clarifies the dynamic compression behavior of aluminum honeycombs in underwater environments and demonstrates their potential for marine energy-absorption applications. Full article

Rapid urbanization and global growth have made sustainable infrastructure a dire necessity. In hot arid regions, rising heat index levels intensify cooling demand and accelerate construction activity. Reducing emissions from concrete is critical to mitigate climate change. This study integrates BIM in Revit with EC3 to quantify GWP and total use of renewable/non-renewable primary resources at the product stage. A residential building is used to evaluate variations in environmental performance across multiple material scenarios (carbon intensive, energy transition, and green scenarios). Results reveal substantial differences in embodied carbon across scenarios. The carbon intensive scenario accounts for a total GWP of 649 tCO₂e, while the green scenario reduces emissions to 381 tCO₂e, which represents a reduction of 42%. Walls and floors are identified as the dominant contributors to embodied carbon due to high concrete volumes, with raw material extraction accounting for the largest share of emissions. Substituting conventional concrete walls with lightweight concrete walls reduces the total GWP by 28%. In addition, planed timber exhibits near zero emissions due to biogenic carbon storage and shows the highest renewable primary energy use among assessed materials. The proposed framework provides a practical approach for evaluating embodied carbon emissions and supports informed material selection for more sustainable building design. Full article

Thin wall composite fan blades in aircraft engines demand designs that ensure structural integrity under operational loads while resisting foreign object damage and bird strikes. This study presents a finite element investigation of thin wall composite blades with metal leading edge caps, modeled through parametric coupon analyses under static flexure loading using ANSYS APDL. Three metallic leading edge caps, Ti-6Al-4V, Inconel 718, and 15-5 PH stainless steel, were combined with IM7/8551-7 carbon fiber composites. Parametric variations included changes in metal cap material, geometric designs of the joint, and other things. Performance was evaluated in terms of failure stress, interlaminar shear strains, interface integrity, and failure margins. Results reveal that cap design and cap material critically govern structural response, with distinct interchanges between strength-to-weight efficiency, interface stresses, and interlaminar shear strain. Optimal designs reduced interlaminar shear strain levels in thin wall composite blades, while retaining adequate stiffness and strength. The results underscore the importance of interface design for effective load transfer and provide design guidelines for lightweight, damage-tolerant thin wall composite fan blade structures. Full article