Search Results (7,250)

This paper presents a comprehensive study aimed at improving the efficiency of unmanned aerial vehicles (UAVs) through the enhancement of their aerodynamic and mechanical structures. The research is based on coupled computational fluid dynamics (CFD) and finite element analysis (FEA). The airflow around the UAV was modeled using the Navier–Stokes equations, while the structural behavior was described by the equations of linear elasticity. A UAV configuration with a wingspan of 1.8 m and a mass-optimized structure was investigated for flight speeds in the range of 10–35 m/s and angles of attack from −5° to +15°. The results of the aerodynamic optimization, including airfoil thickness variation and smoothing of the wing–fuselage junction, showed a reduction in the drag coefficient by 9–12% and an increase in the lift-to-drag ratio by up to 11% in the cruise regime. The structural optimization based on replacing aluminum with a carbon-fiber composite material led to a reduction in the structural mass by 13–16%, a reduction in the structural strength criterion value by 18–22%, as confirmed by the Tsai–Wu failure analysis, and a reduction in wing-tip deflection by 20–25% under 3 g and 5 g load cases, while satisfying strength and stiffness requirements. The obtained results demonstrate that the proposed integrated aerodynamic and structural optimization approach significantly improves the overall performance, efficiency, and operational reliability of UAV systems. Full article

The use of carbon fiber-reinforced plastic (CFRP) components has increased significantly in civilian aviation, necessitating effective maintenance and repair strategies to ensure durability and performance. While prior studies have focused on composite repair methods, such as stepped scarf patch and bolted joint repairs, these were limited to specimen and panel levels without addressing full-scale wing models. This study bridges that gap by evaluating stepped-lap repairs on a full-scale composite wing model under realistic loading conditions and exploring various repair scenarios. To reduce computational cost, two-dimensional shell elements were employed to simulate repairs, with results validated using experimental tensile test data from stepped-lap repaired specimens. Numerical models were developed for single regions and two closely located repair regions. For single-region repairs, adding up to two extra layers enhanced mechanical strength, but three extra layers increased strain, diminishing performance. For two closely located repairs, additional layers improved strength, though less effectively than single-region repairs. Square-shaped repairs exhibited higher strain due to stress concentrations at the corners, while circular repairs showed more uniform stress and strain distribution. These findings emphasize the importance of optimizing repair geometry and layer configurations using numerical simulations to ensure optimal structural performance of CFRP components. Full article

This paper reviews research on energy management strategies (EMSs) for fuel-cell hybrid ships and introduces a “topology–strategy coupling” analytical framework, dividing system topology into two layers: energy-unit composition and DC-bus interface topology. It also introduces key concepts, such as EMS-independent dispatchability and the dominant DC-bus voltage-regulation unit. Based on this framework, the paper explains why certain strategies are easier to implement, tune, and validate under specific interface structures by considering the impact of interface topology on hybrid system efficiency and typical EMS constraints. It presents a unified four category EMS taxonomy, treating hybrid EMSs as a distinct class, and provides cross-category comparisons of different strategies. Additionally, it discusses the consistency and validation challenges when learning-based strategies transition from simulation to onboard deployment and further synthesizes mainstream approaches for integrating lifetime/health considerations into EMSs and their corresponding degradation modeling. Furthermore, the paper conducts a quantitative synthesis of relevant studies from 2016 to 2025, statistically summarizing and presenting the distributional characteristics of energy-unit composition, strategy categories, commonly used methods, validation approaches, and the inclusion of lifetime/health factors. In doing so, it uses data to describe the current state of research and identifies the key challenges and future research directions. Full article

Background: The peptidyl–prolyl cis–trans isomerase PIN1 regulates multiple oncogenic and tumor-suppressive pathways and is frequently overexpressed in human cancers. Although pharmacological inhibition of PIN1 has shown antitumor potential, existing PIN1-targeting degraders lack systematic structure–activity relationship (SAR) analyses and display inconsistent cellular efficacy, leaving the therapeutic relevance of PIN1 degradation unclear. Methods: Two series of PIN1-targeting PROTACs were designed using the covalent inhibitor sulfopin as the PIN1 binder and ligands for either cereblon (CRBN) or von Hippel–Lindau (VHL). Systematic SAR studies focused on linker structure and jointing atom composition. PIN1 degradation was assessed by Western blotting in multiple cancer cell lines, and further investigated through a series of computational and mechanistic experiments. Antitumor efficacy and safety were evaluated in an MCF-7 xenograft mouse model with preliminary pharmacokinetic analysis. Results: SAR analysis revealed that short, linear linkers and reduced hydrogen bond donor content markedly enhanced PIN1 degradation, whereas VHL-recruiting PROTACs showed inferior cellular activity. These studies identified PC2, a CRBN-recruiting PROTAC, as a lead compound. PC2 selectively induced ubiquitin–proteasome-dependent PIN1 degradation with minimal global proteomic or transcriptomic perturbation. Despite modest antiproliferative effects in vitro, PC2 significantly suppressed tumor growth in vivo without observable toxicity and achieved effective intratumoral PIN1 degradation. Conclusions: This study defines SAR-guided design principles for PIN1-targeting PROTACs and demonstrates that selective PIN1 degradation can produce robust antitumor activity in vivo. PC2 represents the first PIN1 degrader validated in animal models and supports targeted PIN1 degradation as a viable anticancer strategy. Full article

Brake-by-wire systems eliminate the mechanical linkage between the brake pedal and wheel actuators, resulting in the loss of the natural and familiar braking feel perceived by the driver. To address this issue, this study proposes an active brake pedal simulator based on a linear motor and springs, aiming to simulate the adaptive pedal feel and ensure safety performance. Firstly, this paper established a structural model of the pedal simulator and designed a force compensation strategy to reproduce the target pedal characteristic curve of the traditional hydraulic braking system. Subsequently, the system was verified through Adams simulation and real vehicle experiments under slow, normal, and emergency braking conditions. The experimental results show that the initial design exhibited a relatively “soft” pedal feel, with a brake feel index score of 62.31. By optimizing the spring stiffness and feedback force composition, the brake feel index score was significantly improved to 92.21. The optimized pedal simulator is capable of achieving precise pedal force tracking and adaptive adjustment of pedal feel, and still providing basic and reliable pedal force feedback, even in the event of motor failure. Therefore, the designed pedal simulator provides a practical and effective solution for improving the pedal feel of the brake-by-wire system, demonstrating strong application potential. Full article

Background/Objectives: Predicting diseases based on the gut microbiome pattern is still difficult because of compositional shortcomings, batch heterogeneity, and scanty modeling of inter-taxon interactions. This study introduces a Dysbiosis-Aware Multiset Transformer Framework called DysbioFormer, which predicts state diseases by recognizing patterns of microbes. Methods: The current methods are mainly based on flat abundance representations or fixed-order models which limit the capability of describing intricate interactions of communities and evolutionary structure. Results: DysbioFormer is a solution to these shortcomings, in which each sample of the microbiome is modeled as a permutation-invariant multiset of taxonomic tokens with compositional, phylogenetic, and harmonized cohort data. Stacked Set Attention Blocks are used to learn relational dependencies between taxa, whereas Pooling-by-Multihead-Attention is used to aggregate global disease-level embeddings and this is not based on sequence assumptions. The model has been tested on MicrobiomeHD, which consists of a wide variety of human gut microbiome samples at a variety of disease conditions and healthy controls. Experimental results demonstrate strong diagnostic performance, achieving an accuracy of 97%, an AUC of 0.97, and an F1-score of 96%, consistently outperforming classical machine learning models under identical evaluation protocols. Attention-derived signatures also can give interpretable connections among predictive results and disease-linked microbial taxa, enhancing biological plausibility. Conclusions: The suggested architecture enables scalable, cohort-agnostic microbial diagnostics, and provides a principled route to transforming the complex information of the microbiome into reliable clinical information. DysbioFormer creates a universal basis of future microbiome-based disease screening and precision health uses. Its design allows extending towards multi-omics integration, longitudinal studies, and decision-support infrastructure, supporting microbiome-informed translational medicine in a variety of clinical research settings. Full article

Thin-walled structures are widely used in long-span bridges such as truss composite arch bridges due to their excellent mechanical properties and cost-effectiveness. However, long-term service can lead to defects including interface delamination and concrete carbonation. This study aims to clarify the regulatory mechanism of bonded rebar diameter on the static direct shear performance at the interface of existing normal concrete (NC) thin-walled structures strengthened with ultra-high performance concrete (UHPC). Using mechanical cutting combined with high-pressure water jetting as the interface treatment method, three sets of shear specimens with rebar diameters of 6 mm, 8 mm, and 12 mm were designed. Through static shear tests and nonlinear finite element analysis, the influence of rebar diameter on the shear performance at the interface was systematically examined. Research findings indicated that as the diameter of embedded rebars increases, the primary failure mode at the interface transitions from interface bond failure to NC matrix failure. Furthermore, as the diameter increased from 6 mm to 12 mm, the ultimate shear strength rose from 5.75 MPa to 9.19 MPa, representing a 59.8% increase. The residual strength increased from 1.5 MPa to 3.45 MPa, representing a significant 130% improvement. The failure slip distance increased from 0.35 mm to 0.44 mm, indicating enhanced ductility. Additionally, the established finite element model can accurately predict the mechanical behavior at the interface under different planting rebar diameters, with an error margin of less than 10% compared to experimental results. The research findings provided a theoretical basis for the design of planting rebar parameters in UHPC-strengthened thin-walled concrete structures. Full article

Reconciling carbon (C) sequestration with biodiversity conservation remains a key challenge for sustainable forest management, as C–biodiversity relationships vary across taxa and contexts. We evaluated how botanical composition, forest structure, C pools, and land use predict species richness of insects, birds, and bats across mature temperate forests in southern Québec, Canada. Generalized linear models were fitted for insects and birds, while bat data were analyzed descriptively due to low and uneven richness. Botanical composition and forest structure were the most consistent predictors across groups. Insects responded strongly to vegetation structure and C allocation, with richness decreasing with shrub density and mineral soil C but increasing with the soil:above-ground C ratio and distance from infrastructure. Bird richness increased with herbaceous cover and wetland area, emphasizing the value of open and moist habitats. Across taxa, C pools acted as secondary but complementary predictors. Based on observational analyses, our results show that C–biodiversity relationships are compartment-specific and taxon-sensitive, and suggest that maintaining structural complexity, diverse vegetation strata, wetland habitats, and soil C pools may help align biodiversity conservation with C sequestration objectives in temperate forests. Full article

This work introduces Hybrid Membrane–Neural P systems (HMN P systems), a computational model that integrates principles from membrane computing and spiking neural P systems. The resulting framework offers a versatile foundation for the development of bio-inspired arithmetic architectures. Within this setting, we propose a compact family of arithmetic kernels capable of executing signed addition, subtraction, multiplication, and division in both modular and non-modular arithmetic domains. By leveraging intrinsic spike aggregation, spike–anti-spike annihilation, and exhaustive rule application, the proposed designs achieve efficient and reliable arithmetic computation in a constant number of simulation steps under exhaustive semantics and assuming synchronized input, independent of operand values. Addition and subtraction are executed intrinsically upon spike arrival, requiring no internal computation steps, while multiplication and division are completed in a single simulation step by one neuron. Furthermore, we introduce a modular-reduction kernel that operates in two simulation steps with a single neuron, and leverage its modular structure to construct modular multiplication and division through composition with non-modular arithmetic modules. Comparative evaluations against representative SNP and SNQ arithmetic designs demonstrate that HMN kernels achieve operand-independent execution time while requiring fewer neurons. Distinct from most existing approaches, the HMN framework natively supports signed operands through a dual-spike representation, thereby eliminating the need for auxiliary sign-handling mechanisms. Asynchronous spike arrivals can be managed by an optional synchronization membrane; since this mechanism is decoupled from the arithmetic kernels, its overhead is excluded from kernel performance and reported separately. Collectively, these results establish HMN systems as an efficient and modular platform for constant-time arithmetic computation, offering reusable arithmetic kernels that serve as a foundation for higher-level constructions, including those arising in elliptic-curve and modular arithmetic. Full article

The incorporation of slag and calcium carbonate (CaCO₃) as clinker-reducing constituents offers significant potential for lowering CO₂ emissions in cement production; however, their combined influence on age-dependent compressive strength remains complex and highly coupled. In this study, a structured literature-based dataset ($N=75$ mix conditions) was compiled from two independent experimental sources to investigate compressive strength development in slag–CaCO₃ blended cementitious systems. Compressive strength at 3 and 28 days was formulated as a multi-output regression problem to explicitly capture the correlated nature of strength evolution between early-age and later-age curing stages. Dataset-level analysis revealed that CaCO₃ replacement exerts a stronger influence on early-age strength (reductions of approximately 15–25%) than on later-age strength (typically within 5–15%), indicating a transition from clinker-dominated hydration to slag-controlled later-age strength development. Compared with independent single-output models, the proposed multi-output framework improved prediction performance by increasing $R^2$ values by approximately 4–6% and reducing RMSE by up to 15–18%. Feature importance analysis identified slag replacement ratio and CaCO₃ dosage as the dominant predictors, while chemical composition descriptors modulated age-dependent sensitivity. The results demonstrate that compressive strength at different curing ages is governed by coupled yet temporally evolving physicochemical mechanisms. From an engineering perspective, CaCO₃ replacement should be evaluated within an integrated compositional design framework that considers curing-age requirements and slag reactivity. Overall, this study provides a transparent and statistically robust approach for analyzing strength evolution in blended cement systems and highlights the value of multi-output learning for age-dependent performance prediction in sustainable cementitious materials. Full article

This study provides a comprehensive analysis of peanut shell (PnS) combustion behavior using combined physicochemical characterization and non-isothermal thermogravimetric kinetics. To evaluate its potential as a sustainable solid biofuel, PnS was characterized for its proximate and ultimate composition, with its fiber structure analyzed via Van Soest methods and functional groups identified via FTIR spectroscopy. Thermogravimetric analysis (TGA) was performed at high heating rates ($20,40,60$, and $80 \mathrm{K}{ \mathrm{m}\mathrm{i}\mathrm{n}}^{-1}$) to investigate combustion stages under oxidative conditions. The results established PnS as a high-potential energy source, revealing a significant volatile matter content ($65.30 \mathrm{w}\mathrm{t}\%$) and an exceptionally high heating value ($20.87 \mathrm{M}\mathrm{J} {\mathrm{k}\mathrm{g}}^{-1}$), which surpasses many standard agricultural residues. The proximate analysis also indicated a moisture content of $9.61\%$ and an ash content of $6.59\%$. TGA profiles displayed distinct decomposition stages, with the primary devolatilization occurring between 500 and 700 K. Kinetic analysis was conducted using six model-free methods: Friedman (FR), Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Starink (STK), Kissinger (K), and Vyazovkin (VY) and the Coats-Redfern model-fitting method. The apparent activation energy $\left({\mathrm{E}}_{\mathrm{a}}\right)$ was found to vary with conversion $\left(\mathsf{\alpha }\right)$, reflecting the complex degradation of the lignocellulosic matrix (47.86% cellulose, $28.4\%$ lignin). The activation energy values ranged from approximately $23 \mathrm{k}\mathrm{J}{ \mathrm{m}\mathrm{o}\mathrm{l}}^{-1}$ (VY method at low conversion) to $187 \mathrm{k}\mathrm{J}{ \mathrm{m}\mathrm{o}\mathrm{l}}^{-1}$ (FR method at $\mathsf{\alpha }=0.5$). Model-fitting analysis identified the three-dimensional diffusion (D3) model as the governing reaction mechanism. Thermodynamic analysis indicated positive enthalpy ($\Delta \mathrm{H}:70.7-181.8 \mathrm{k}\mathrm{J}{ \mathrm{m}\mathrm{o}\mathrm{l}}^{-1}$) and Gibbs free energy ($\Delta \mathrm{G}$: $116.2-216.7 \mathrm{k}\mathrm{J}{ \mathrm{m}\mathrm{o}\mathrm{l}}^{-1}$), with predominately negative entropy ($\Delta \mathrm{S}$), confirming the endothermic and non-spontaneous nature of the reaction activation. Full article

Biodiversity promotes ecosystem multifunctionality (EMF), yet it remains unclear how wetland types mediate the biodiversity–EMF relationship. This study investigated the differences in maintaining ecosystem functionality between lacustrine (lake) and riverine (river) wetlands in a semi-arid region. We examined how multiple soil environmental variables individually influence plant communities, soil enzyme activities, and microbial community composition and diversity, and we further explored how these factors drive EMF via interactions with microbial communities. Results showed that both individual ecosystem functions and EMF were significantly lower in lacustrine wetlands compared to riverine wetlands. Plant community attributes were the primary drivers of spatial heterogeneity in bacterial, fungal, and archaeal communities; conversely, soil enzyme activities were more strongly correlated with soil structure. Structural Equation Modeling (SEM) revealed distinct regulatory mechanisms: riverine wetlands were primarily subject to direct linkage between ecosystem multifunctionality and microbial diversity, whereas lacustrine wetlands exhibited a regulatory paradigm dominated by environmental filtering, where abiotic stressors (e.g., salinity and soil moisture) indirectly drove EMF by reshaping plant communities. These findings provide critical theoretical and technical insights for the conservation and restoration of wetland ecosystems. Full article

This paper investigates deflection deformation and premature bearing failure in deep-hole machining spindles with high length-to-diameter ratios under eccentric loading. A contact stiffness model for angular contact ball bearings was developed based on Hertz contact theory. Combined with the finite element method (FEM), a comprehensive mechanical analysis model of the spindle was established. The results show that spindles with high length-to-diameter ratios exhibit significant cantilever behavior, leading to considerable front-end deflection under eccentric loading. This deflection causes the inner and outer rings to incline, resulting in localized stress concentrations, which are the primary contributors to spindle fatigue failure. To improve the spindle’s stress distribution and dynamic performance, an optimized design replacing the metal housing with carbon fiber composite material is proposed. Static and modal analyses were performed using Abaqus and Romax. The analysis results demonstrate that the carbon fiber shell reduces self-weight deformation by 35.8%, decreases coupled deformation under self-weight and grinding loads by 28.6%, and increases modal fundamental frequencies by 20.88% to 47.41%. These improvements significantly enhance structural stiffness and dynamic stability. Experimental vibration monitoring during machine testing validated the accuracy of the modeling and simulation. Full article

The demand for biodegradable, recyclable, natural composites with lightweight structures is driven by the fact that advanced structures can withstand quasi-static and dynamic loadings. This study examined the energy-absorbing characteristics of interlocking periodic honeycomb sandwich structures made from short sugar palm, kenaf, and pineapple leaf fibres (PALFs) reinforced with a polylactic acid (PLA) composite. The biodegradable sugar palm, kenaf, and PALF/PLA composite sheets were subjected to hot compression and cut into single- and double-slot square plates. The interlocking technique was used to assemble periodic two-dimensional square-honeycomb sandwich structures. Moreover, new and recyclable PLA-based composites with three fibres were tested for tensile properties. The biodegradable PLA-based composite honeycomb sandwich structure underwent a quasi-static compression test. Finite element modelling was used to simulate the load–displacement curve, energy-absorption characteristics, and failure behaviour, incorporating tensile properties and geometric imperfections. The results revealed that the double-slot design of the pineapple/PLA sandwich structure significantly increased by 1.33 times compared to the sugar palm/PLA sandwich structure. Notably, it reduced the compressive strength of recyclable pineapple/PLA (66.4%) and recyclable sugar palm/PLA (31.5%) composite sandwich structures compared to the new pineapple/sugar palm PLA-based composite. In addition, finite element analysis (FEA) showed reasonable agreement with experimental data, with a 7.11% error in energy absorption (EA). It was highlighted that biodegradable, recyclable, interlocking sandwich-structured composites have potential for advanced, sustainable energy-absorbing structures. Full article

To clarify the shear lag effect and flexural performance of glass fiber-reinforced polymer (GFRP) composite truss web girder bridges and verify the feasibility of substituting steel truss webs with GFRP members, a refined finite element (FE) model was established via ABAQUS. Transverse and longitudinal stress distributions in concrete slabs were systematically analyzed under mid-span concentrated, full-span distributed, and two-point symmetric loads, with a parallel performance comparison against steel truss web girder bridges. The transverse shear lag effect exhibited distinct interlayer differences, with the top slab effective width ratio 15–20% lower than that of the bottom slab; stress peaks at truss-slab joints stemmed from concentrated shear transfer, while bottom slab stress troughs were induced by boundary constraints. Longitudinally, the effective width ratio averaged 0.65 at beam ends, dropped to the minimum at loading points, and recovered to over 0.98 in non-loaded zones. Performance comparisons showed that under the applied load patterns, the GFRP system exhibited a flexural performance similar to that of the steel system, with mid-span deflection differences of 0.29–0.30 mm and normal stress deviations below 0.1 MPa. This study quantifies the multi-case shear-lag response characteristics, verifies that GFRP truss webs can achieve flexural behavior comparable to steel webs under the investigated conditions, and provides theoretical support for the refined design and engineering applications of this novel bridge structure. Full article