Search Results (89)

In recent years, interest in edible insects has increased in Western countries, leading to an expansion of the market for insect-based products. In this context, it is essential to assess their susceptibility to infestation by stored-product pests, to ensure food safety and to develop appropriate storage management strategies. This study examined the ability of three common stored-product moth species (Plodia interpunctella, Corcyra cephalonica and Ephestia kuehniella) to infest Acheta domesticus powder and biscuits enriched with cricket powder. Larval development, adult emergence, wingspan and female fertility were evaluated. The results showed that P. interpunctella and C. cephalonica were able to complete their development on cricket powder, albeit with lower survival rates, longer developmental times and fewer offspring than on the standard diet. E. kuehniella was unable to develop on cricket powder and only minimal adult emergence was recorded in the biscuit trials, although signs of infestation were detected. These findings demonstrate that stored-product moths represent a potential infestation risk for this novel food, the market for which is expected to grow. Full article

To achieve miniaturization and lightweight design of a flapping-wing aircraft, a high-performance biomimetic butterfly flyer was designed based on an analysis of the butterfly’s body structure and flight principles. The aircraft has a mass of 20.6 g and a wingspan of 0.295 m. To validate the rationality of the design, sensitivity analysis of the flapping-wing drive mechanism was first conducted using MATLAB 2022B software, and the length of the driving rod was optimized. Subsequently, a dynamic model was established to calculate the aerodynamic performance of the flapping wing. Then, the aerodynamic performance of the aircraft was verified using simulation software (XFLOW 2022). Finally, the flight stability of the aircraft was validated using the SIMULINK toolbox. Flight test results show that the biomimetic butterfly flyer achieves a maximum flight speed of 0.9 m/s, a climb rate of 0.12 m/s, and a flight endurance of up to 3 min, with good flight stability. This design provides a new approach for the development of small and lightweight flapping-wing aircraft. Full article

This work presents a novel Graph Neural Network (GNN) based framework for structural damage detection and localization in composite aerospace structures. The sensor network is modeled as a graph whose nodes correspond to the strain measurement points placed on the system, while the edges capture spatial and structural relationships among sensors. Strain mode shapes, extracted via Automated Operational Modal Analysis (AOMA), are used as input features for the GNN. Two architectures are developed: one for binary damage detection and another for damage localization, the latter outputting a spatial probability distribution of damage over the structure. Both networks are trained and validated on synthetic datasets generated from high-fidelity finite element transient simulations performed on a composite wing equipped with 40 strain sensors. The obtained results show strong effectiveness in both detection and localization tasks, thus highlighting the potential of leveraging GNNs for topology-aware Structural Health Monitoring applications. In particular, the proposed framework achieves an AUC of 0.97 for damage detection and a mean localization error of approximately 3% of the wingspan on the synthetic dataset. The performance of the GNN is also compared with a fully connected and a convolutional neural network, demonstrating significant improvements in the localization accuracy. Full article

Habitat and climate changes driven by human activities are altering the distribution of organisms globally. In South Korea, recent temperature increases have exceeded twice the global average, and habitats have markedly changed and shrunk due to urban development driven by population growth and economic expansion. Despite its high biodiversity and over 500 years of preservation, Gwangneung Forest in South Korea has experienced habitat alterations due to the urbanization of surrounding rural areas since the 1990s. In this study, we aimed to evaluate how butterfly communities respond to urbanization and climate change using long-term monitoring data (1998–2015) from the conserved Gwangneung Forest. We considered the thermal adaptation types (cold-, warm-, and moderately adapted species), habitat types (forest edge, forest inside, and grassland), diet breadth (monophagous, oligophagous, and polyphagous), and wingspan of butterflies. Linear regression analysis of the abundance trends for each species revealed that cold-adapted species experienced population declines, while warm-adapted species showed increases. Changes in butterfly abundance were associated with both thermal adaptation type and wingspan, with larger, more mobile species showing greater resistance to habitat loss in surrounding areas. To preserve butterfly diversity in Gwangneung Forest and across South Korea, it is crucial to conserve open green habitats—such as gardens, small arable lands, and grasslands—within urban areas, especially considering the impacts of climate change and habitat loss, which disproportionately affect smaller species with limited mobility. Full article

Flexible inflatable film wings have many functional advantages that traditional fixed rigid wings do not possess, such as foldability, small size, light weight, convenient storage, transportation, and so on. More and more scholars and engineers are paying attention to flexible inflatable wings, which have gradually become a new hot research topic. However, flexible wings rely on inflation pressure to maintain the shape and rigidity of the skin film, and the inflation pressure has a significant influence on the strain deformation and wing bearing characteristics of flexible wing skin film. Here, based on the flexible mechanics theory and balance principle of flexible inflatable film, a theoretical model of structural deformation and internal inflation pressure was constructed, and finite element simulation analysis under different internal inflation pressure conditions was carried out as well. The results demonstrate that the biaxial deformation of flexible wing skin film is closely related to internal inflation pressure, local size, configuration, and film material properties. However, strain deformation along the wingspan direction is quite distinguishing, skin films work under the condition of biaxial plane deformation, and the strain deformation of the spanning direction is obviously higher than that of the chord direction, which all increases with internal inflation pressure. Therefore, it is necessary to pay more attention to bearing strain deformation characteristics to meet the bearing stiffness requirements, which could effectively provide a theoretical reference for the structural optimization design and inflation scheme setting of flexible inflatable wings. Full article

This study addresses the gap in the experimental validation of the tilt-rotor vertical take-off and landing (VTOL) UAVs by developing a novel prototype that integrates fixed-wing and multi-rotor advantages. A dynamic model based on the “X” quadrotor configuration was established, and Euler parameters were employed to derive the attitude transformation matrix. Structural optimization using hybrid meshing and inertia release methods revealed a maximum deformation of 57.1 mm (2.82% of half-wingspan) and stress concentrations below material limits (379.21 MPa on fasteners). The landing gear was optimized using the unified objective method, and the stress was reduced by 32.63 MPa compared to the pre-optimization stress. Vibration analysis identified hazardous frequencies (11–12 Hz) to avoid resonance. Stable motor speed tracking (±5 RPM) and rolling attitude control (less than 10% error) are achieved using a dual-serial PID control system based on the DSP28377D master. Experimental validation in low-altitude flights confirmed the prototype’s feasibility, though ground effects impacted pitch/yaw performance. This work provides critical experimental data for future tilt-rotor UAV development. Full article

Using generally available geometric data, calculations of wetted and projected areas of major components, that is, wings, fuselages, empennage, and engine nacelles, for 55 airplanes were compiled into a database comprising four groups: commercial, supersonic, all-wing, and military airplanes. Attention is primarily focused on subsonic and supersonic commercial airliners, and the wetted areas of the components of each are discussed and shown to be reasonably estimated by simple functions of airplane geometry, like gross wing planform area, fuselage length and diameter. Comparisons of total wetted areas of 13 commercial airplanes and 5 military airplanes with results reported by 14 independent studies showed good agreement. Total wetted areas for all the airplanes were shown to be well-represented by simple functions of wing planform area S alone. Relationships between the projected and wetted areas of the commercial airplanes were explored to illustrate the implications for airplane design, including accommodation of fuselage stretch, trends in component wetted area fractions, correspondence of wetted areas to planform envelope—that is, the product of wingspan and fuselage length, relation of frontal areas to wetted areas, and application of a planform configuration parameter, B = (bAR)^3/16(1 + 3.5/AR^9/4)^−1/2, to estimation of (L/D)_max—and prediction of wetted area as a function of gross weight based on the square–cube relation between area and volume. Full article

The aerodynamic performance of an aircraft can be enhanced by incorporating wingtip devices, or winglets, which primarily reduce lift-induced drag created by wingtip vortices. This study outlines an optimization procedure for implementing winglets on a Class I fixed-wing mini-UAV to maximize aerodynamic efficiency and performance. After the Conceptual and Preliminary design phases, a baseline UAV was developed without winglets, adhering to specific layout constraints (e.g., wingspan, length). Various winglet designs—plate and blended types with differing heights, cant angles, and sweep angles—were then created and assessed. A Computational Fluid Dynamics (CFD) analysis was conducted to evaluate the flow around both the winglet-free UAV and configurations with each winglet design. The simulations employed Reynolds-Averaged Navier-Stokes (RANS) equations coupled with the Spalart-Allmaras turbulence model, targeting the optimal winglet configuration for enhanced aerodynamic characteristics during cruise. Charts of lift, drag, pitching moment coefficients, and lift-to-drag ratios are presented, alongside flow contours illustrating vortex characteristics for both baseline and optimized configurations. Additionally, dynamic stability analyses examined how winglets impact the UAV’s stability and control. The results demonstrated a significant improvement in aerodynamic coefficients ($C_{Lmax}$, $L/D_{max}$, $C_{La}$, $C_{ma}$), leading to an increase in both range and endurance. Full article

Morphing aircraft can actively or passively change their shape in different flight environments and missions to ensure optimal flight performance at all flight stages, thereby enhancing environmental adaptability and meeting extensive multi-mission requirements. This paper proposes a stable flight control strategy for a variable-span aircraft based on Model Predictive Control (MPC). The Linear Parameter Varying (LPV) modeling approach is adopted to establish a longitudinal dynamic model that varies with the wingspan deformation rate. Without considering disturbances, a model predictive control strategy is designed to achieve dynamic stability control during flight. Considering the existence of composite disturbances during the morphing process, a robust model predictive control (RMPC) strategy is proposed, using set containment as the performance index. To verify the robustness of the control strategy, numerical tests are conducted under different wingspan deformation rates and disturbance intensities. The test results demonstrate that the RMPC strategy can effectively suppress external disturbances under various deformation rates, maintain stable flight speed and altitude, and ensure smooth transitions of critical flight state parameters such as angle of attack and pitch angle. These results validate the effectiveness of the proposed method. Full article

Distributed propulsion systems are strategically placed along the aircraft wingspan to ingest the fuselage boundary layer, thereby enhancing propulsion efficiency. However, the aerodynamic effects of S-shaped duct geometry on a distributed propulsion system are not fully understood. The impact of the S-shaped duct inlet aspect ratio and centerline offset on the inlet distortion of ducted fans was numerically investigated using a method based on the circumferential body force model. The results show that the most severe inlet distortion occurs when a large centerline offset is combined with a small aspect ratio. For an S-shaped duct with a substantial centerline offset, increasing the aspect ratio mitigates the distortion level in the edge fans. Specifically, increasing the aspect ratio from 6 to 10 reduces the total pressure and swirl distortion index in the edge fan by up to 80.1% and 84.2%, respectively. In an S-shaped duct with a small aspect ratio, decreasing the centerline offset from 1.75 times to 0.75 times the ducted fan diameter lowers the total pressure and swirl distortion index in the edge fan by up to 75.2% and 87.5%, respectively. These insights provide valuable information for the integrated design and optimization of the S-shaped duct in distributed propulsion systems. Full article

Mechanical metamaterials, especially the cells with a negative Poisson’s ratio (NPR), have received much attention since they offer more deformability potential in morphing wings. This paper proposes a strategy for regulating the deformation of metamaterial cells based on the deformation form of the wing planform. The deformation of the wing shape was achieved through this strategy, with the main control factor of NPR. In light of the strategy, taking bi-directional re-entrant anti-tetrachiral (BRATC) metamaterial cells with NPR as an example, a scheme for BRATC metamaterial cells to regulate NPR is proposed. Driven by the same increase in wingspan (Δspan = 5%), the wing models, which are constructed based on the BRATC metamaterial cells with NPR characteristics at the different chord length increment at wing root (Δchord = 20%, 25%, and 30%), achieved an acceptable object-contour shape error (K = 1.29%, 1.40%, and 2.10%) with corresponding relative area increases (Ar = 15.5%, 18.13%, and 20.75%). Finally, the feasibility of the method is verified by experimentally measuring the deformation of the wing model. Full article

Due to the small size of the micro aircraft, it has high permeability and concealability, holding promise in application in the military and civil fields, and it has become a domestic and international research frontier and hotspot in the past decade. However, caused by the heavy onboard power supply and the decline in the actuator’s operating power at micro sizes, untethered flight is still a development difficulty at present. In this paper, we introduce a new micro vehicle configuration which is driven by onboard capacitive energy and can realise off-line free flight under the drive of electrostatic actuators. In the overall design, this paper proposes structural capacitors as the energy supply unit and buoyancy unit of the vehicle, which can overcome part of the vehicle body’s weight by being filled with helium gas, while the capacitor can provide electrical energy for the propulsion unit. The micro vehicle has a wingspan of 5 cm, a total mass of 165 mg, a stable operating voltage between 1300 V and 2400 V, and a flight time of more than 60 s under the condition of an onboard capacitor power supply. The micro vehicle designed in this thesis has a small wingspan, light weight, and better concealment, and it has broad application prospects in the future in environmental reconnaissance, surveying, and other scenarios. Full article

Background/Objectives: Physical performance is becoming increasingly critical in basketball, as it directly influences players’ agility, power, and endurance. This study aimed to assess the progression of body composition and physical performance metrics across different ages and genders, establishing age- and gender-specific reference values for Tunisian basketball athletes. Methods: A total of 469 Tunisian basketball players (239 boys and 230 girls) were assessed and grouped by age. Anthropometric measures—including standing and sitting height, body mass, leg length, body mass index, fat mass, fat-free mass, body fat percentage, wingspan, and leg muscle volume—were collected alongside physical performance metrics. Performance tests included countermovement and squat jumps, change-of-direction speed, maximal oxygen uptake, flexibility, the five-jump test, and 5 m, 10 m, and 20 m sprints with and without the ball. Normative data were generated based on age and gender categories. Results: The findings revealed significant age-related improvements in both anthropometric and performance parameters. Boys consistently outperformed girls in physical and fitness-related measures, with gender differences becoming more pronounced with age. Stepwise regression analyses indicated that, for boys, body fat percentage, leg muscle volume, standing height, and wingspan were the best predictors of physical performance. For girls, body fat percentage, standing height, and sitting height were identified as key predictors. Conclusions: The newly established Tunisian reference values for physical performance in youth basketball provide valuable benchmarks that can support the development of explosive power and strength in players, aiding in talent identification and potentially enhancing individual and team performance outcomes. Full article

Over twenty Solar-Powered Unmanned Aerial Vehicle (SPUAV) designs exist worldwide, yet few have successfully achieved uninterrupted high-altitude flight. This shortfall is attributed to several factors that cause the actual performance of SPUAV to fall short of expectations. Existing studies identify the propeller slipstream as one of these adverse factors, which leads to a decrease in the lift–drag ratio and an increase in energy consumption. However, traditional design methods for SPUAVs tend to ignore the potential adverse effects of slipstream at the top-level design phase. We find that this oversight results in a reduction in the feasible mission region of SPUAVs from 109 days to only 46 days. To address this issue, this paper presents a high-fidelity multidisciplinary design framework for the energy/propulsion systems of SPUAVs that integrates the effects of a propeller slipstream. Specifically, deep neural networks are employed to predict the lift–drag characteristics of SPUAVs under various slipstream conditions, and the energy performance is further analyzed by evaluating the time-varying state parameters throughout a day. Subsequently, the optimal solutions for the energy/propulsion systems specific to certain latitudes and dates are obtained through optimization design. The effectiveness of the proposed design framework was demonstrated on a 30-m wingspan SPUAV. The results indicated that, compared to the traditional design method, the proposed approach led to designs that more effectively accomplished closed-loop flight in designated regions and prevented the reduction of the feasible mission region. Additionally, through the targeted retrofit of the energy/propulsion systems, SPUAVs exhibited enhanced adaptability to the solar radiation characteristics of different mission points, resulting in a further expansion of the feasible mission region. Furthermore, this research also explored the variation trends in optimal solutions across different latitudes and dates and investigated the reasons and physical mechanisms behind these variations. Full article

Inspired by hummingbirds and certain insects, flapping wing micro aerial vehicles (FWMAVs) exhibit potential energy efficiency and maneuverability advantages. Among them, the bi-directional motor-driven tailless FWMAV with simple structure prevails in research, but it requires active pose control for hovering. In this paper, we employ deep reinforcement learning to train a low-level hovering strategy that directly maps the drone’s state to motor voltage outputs. To our knowledge, other FWMAVs in both reality and simulations still rely on classical proportional-derivative controllers for pose control. Our learning-based approach enhances strategy robustness through domain randomization, eliminating the need for manually fine-tuning gain parameters. The effectiveness of the strategy is validated in a high-fidelity simulation environment, showing that for an FWMAV with a wingspan of approximately 200 mm, the center of mass is maintained within a 20 mm radius during hovering. Furthermore, the strategy is utilized to demonstrate point-to-point flight, trajectory tracking, and controlled flight of multiple drones. Full article