This paper focuses on multimissile cooperative guidance for intercepting multiple maneuvering targets and proposes a guidance law based on an iterative time-to-go estimation method. Firstly, an evaluation model for target assignment is established, with special emphasis on the multimissile time coordination matching index. The target assignment problem is then formulated as an optimization task and solved using an improved coati optimization algorithm (ICOA), which incorporates chaotic mapping, dynamic weights, and Cauchy mutation to enhance optimization performance. Secondly, by combining biased proportional navigation (BPN) with the iterative time-to-go estimation method, a time-coordinated guidance law applicable to maneuvering targets is developed. By continuously updating the predicted interception time according to real-time target motion, this guidance law extends the applicability of previous approaches, which were originally designed for stationary targets, to scenarios involving highly maneuvering targets without relying on a predefined attack time. Simulation results demonstrate that the ICOA achieves better convergence speed and optimization accuracy than PSO, GWO, and COA. The proposed method also exhibits strong interception performance and coordination precision across various maneuvering target scenarios, validating its effectiveness.
The conservation properties of high-order finite difference schemes have consistently been questioned, limiting their application in complex engineering problems. Based on the symmetric conservative metric method (SCMM), high-order weighted compact nonlinear schemes (WCNS) exhibit geometric conservation properties comparable to those of the finite volume method. However, their global conservation properties have not been fully addressed. This paper introduces a uniformly high-order WCNS scheme on equidistant grids, where the integral weights at all solution points are treated as unknowns and directly solved numerically to ensure exact satisfaction of global conservation. Theoretical analysis provides four constraint conditions that the integral weights should satisfy, which are then validated through targeted numerical experiments. Additionally, we examine the impact of the global conservation property on the simulation results of high-order finite difference schemes. The findings of this study can inform the design of high-order boundary difference schemes and numerical integration methods for engineering applications.
Kenichiroh Koshika, Hideki Tsuruga, Tomokazu Morita
et al.
A nondestructive safety diagnosis for lithium-ion battery modules was demonstrated with experimental data. The charging curve analysis (CCA) was selected for estimating the internal state of a lithium-ion battery cell and the cell operating conditions in a module. The safety threshold set by using CCA data was validated by thermal runaway tests for battery cells using an external heating method. The diagnosis for the module revealed not only its safety but also its discharge capacity (state of health (SOH)). An output image with comprehensive information including indicators to accumulate remaining battery performance values was successfully displayed.
In this paper, two stochastic resonance systems for reconstructing noise-containing pulse signals are designed based on Fabry-Perot cavity with 3D DSM. The effects of different parameters in two stochastic resonance systems on bistability are analysed, the cross-correlation coefficient and cross-correlation gain between the original input signal, the input signal, and the output signal are calculated as a means of evaluating their signal reconstruction performance. The results show that their maximum cross-correlation gains reach 3.2 and 3, respectively, both stochastic resonance systems can effectively reconstruct noisy pulse signals. By comparing the simulation data of the two systems, it is known that the stochastic resonance system using photonic crystals can effectively reduce the need for pulse signal strength and noise intensity. This study provides an effective means of detecting weak pulse signals.
Aiming at the problem of whirl-flutter dynamics of distributed propulsion rotorcraft in high-speed forward flight state， this paper proposes a highly versatile， fast and efficient distributed multi-rotor/tilt-wing coupled aeroelastic dynamics analysis method. Based on the theory of moderately deformed beams， this method takes into account the elastic and inertial coupling between the rotors and the wings. By using the strip theory corrected by CFD， a distributed multi-rotor/tilt-wing aeroelastic dynamics analysis model is established to study its whirl-flutter characteristics in the forward flight state. After proving the accuracy of the analysis method， this paper also studies the influence of the dynamic parameters of the coupled system （such as the wings， nacelles and rotors， etc.） on the critical whirl-flutter speed of the aircraft. The results show that the system first experiences torsional instability and then in-plane bending instability. The torsional stiffness of the wings has the greatest influence on the critical flutter speed of the system， followed by the out-of-plane and in-plane bending stiffness. The three-dimensional effect of the flutter motion is obvious， presenting as the coupling of the torsional and in-plane and out-of-plane bending modes of the wings. Opening the lift rotors and increasing the number of rotors at low speeds can effectively increase the aeroelastic stability of the system. The flapping stiffness of the hinge-less blades has little influence on the critical flutter of the system. Increasing the rotor thrust and reducing the rotor speed are beneficial to increasing the critical flutter speed of the system， while increasing the height of the rotors and nacelles will reduce the critical flutter speed of the system.
Lorenzo Beltrame, Jules Salzinger, Lukas J. Koppensteiner
et al.
In this study, we propose a scalable deep learning approach to automated phenotyping using UAV multispectral imagery, exemplified by yellow rust detection in winter wheat. We adopt a high-granularity scoring method (1 to 9 scale) to align with international standards and plant breeders’ needs. Using a lower spatial resolution (60 m flight height at 2.5 cm GSD), we reduce the data volume by a factor of 3.4, making large-scale phenotyping faster and more cost-effective while obtaining results comparable to those of the state-of-the-art. Our model incorporates explainability components to optimise spectral bands and flight schedules, achieving top-three accuracies of 0.87 for validation and 0.67 and 0.70 on two separate test sets. We demonstrate that a minimal set of bands (EVI, Red, and GNDVI) can achieve results comparable to more complex setups, highlighting the potential for cost-effective solutions. Additionally, we show that high performance can be maintained with fewer time steps, reducing operational complexity. Our interpretable model components improve performance through regularisation and provide actionable insights for agronomists and plant breeders. This scalable and explainable approach offers an efficient solution for yellow rust phenotyping and can be adapted for other phenotypes and species, with future work focusing on optimising the balance between spatial, spectral, and temporal resolutions.
Wind tunnel testing is a crucial method for studying aircraft flutter. Using heavy gas as the wind tunnel medium can mitigate the escalating issue of test models being overweight as advanced aircraft develop. This paper employs an analytical method for numerical calculations of three-dimensional (3D) wing flutter based on fluid–structure interaction (FSI). Flutter calculations for the Goland wing are conducted, and the results in the air medium are consistent with the literature. In contrast, significant differences in flutter behavior are observed in the heavy gas R134a medium. Compared to air, when the model reaches a critical state in R134a, the incoming flow velocity is lower, the incoming flow density is approximately 3 to 5 times air, and the incoming flow dynamic pressure is about 1.1 to 1.2 times that of air. The correction of heavy gas flutter data is crucial for wind tunnel testing. This paper proposes a correction method based on the unsteady transonic flow similarity law proposed by Bendiksen under quasi-steady conditions. Attempts are made to revise relevant published wind tunnel tests and heavy gas flutter calculation results. The transonic flutter similarity law effectively explains the flutter similarity of rigid models in both heavy gas and air media. Still, it fails in cases with highly reduced frequencies and low mass ratios, such as those encountered with flexible wings.
Jonathan Arturo Sánchez Muñoz, Christian Lagarza-Cortés, Jorge Ramírez-Cruz
Spike blunt bodies are a method to reduce drag when a body moves at speeds above sound. Several numerical works based on computational fluid dynamics (CFD) have deeply studied fluid performance and highlighted its advantages. However, most documentation focuses on modifying spike physical properties while keeping constant supersonic or hypersonic flow conditions. In recent years, machine learning models have emerged as viable tools to predict values in almost any field, including aerodynamics. In the case of CFD, many models have been explored, such as support vector regression, ensemble methods, and artificial neural networks. However, a simple and easy-to-implement method such as k-Nearest Neighbors has not been extensively explored. This work extrapoled k-Nearest Neighbors to predict the drag coefficient of a spike blunt body for a range of supersonic and hypersonic speeds based on drag data obtained from CFD analysis. The parametric study of the spike blunt body was performed considering body diameter, spike length, and freestream Mach number as input variables. The algorithm presents proper predictions, with errors less than 5% for the drag coefficient and considering a minimum of three neighbor nodes. The k-NN was compared again Kriging model and k-NN presents a better accuracy. The above validates the flexibility of the method and shows a new area of opportunity for the calculation of aerodynamic properties.
Developing wind tunnel models is time consuming, labor intensive, and expensive. Rapid prototyping for wind tunnel tests is an effective, faster, and cheaper method to obtain aerodynamic performance results while considerably reducing acquisition time and cost for the models. Generally, the rapid prototyping models suffer from insufficient stiffness or strength to withstand the loads generated during a wind tunnel test. In the present study, a rapid prototype model reinforced with metallic inserts was produced to experimentally investigate the aerodynamic characteristics of an uncrewed aerial vehicle with various wingtip deflections. The fused deposition modeling process was used to make the outer mold, whereas the metallic parts were produced using laser cutting and the computer numerical control machining process. Then, the model was evaluated both experimentally and numerically. The test campaign presented in this work was conducted in the de Havilland low-speed wind tunnel facility at the University of Glasgow. For better characterization of flow patterns dominated by leading edge vortices, numerical simulations were run using OpenFOAM 8.0 and validated with experimental data. The experimental data obtained from the hybrid rapid-prototyped model agreed well with the numerical results. This demonstrates the efficacy of hybrid rapid-prototyped models in providing reliable results for initial baseline aerodynamic database development within a short period and at a reduced cost for wind tunnel tests.
A high-performance servo control system is the basis for realizing high-precision photoelectric tracking. With high position resolution and power-off self-locking, ultrasonic motors have a wide range of applications for high-precision positioning control. An optoelectronic tracking platform driven by two ultrasonic motors is proposed in this study. The shaft structure of the tracking platform is designed and modeled. The shaft structure is simplified, and a dynamic model is established to analyze the motion characteristics. The parameters of the limit mechanism are optimized based on the analysis. The shaft structure is built to verify the response characteristics of the tracking platform at different velocities. The results show that the proposed design can fully utilize the self-locking of ultrasonic motors for rapid automatic alignment of the axis system. The maximum response time is less than 55 ms. When the operating velocity is less than 70°/s, the positioning error is less than 0.055°, and the lower the speed, the smaller the positioning error.
The conceptual design of a hybrid aerial vehicle for the exploration of the upper Venus atmosphere is presented. The vehicle will float like a balloon and harvest solar energy which is stored in batteries. The neutral buoyancy reduces the energy consumption and makes the vehicle robust and durable. Energy stored in the batteries can be used for powered flight with good horizontal and vertical mobility to explore aspects of the atmosphere. The vehicle is intended to operate near 55.3 km altitude and to explore the cloud layer of the planet. The vehicle takes its inspiration from the Stingray inflatable wing by Prospective Concepts. Based on a trade study, the wing span was set to 25 m. Equations are developed for the altitude, gas and skin temperature, and skin stress during neutrally buoyant flight. To keep the equations in a simplified analytical form, the complex compartmentalized gas pockets of the vehicle are lumped into a single gas sphere. The equations take into account the volumetric expansion of the structure and the requirement that the differential pressure needs to be large enough to allow for brief periods of powered flight without significant structural deformation. An aerodynamic analysis provides the lift and drag coefficient curves and indicates that the vehicle is pitch-stable. A powered flight analysis shows that an airspeed of 30 m/s can be maintained for 31 min at 55 km and 69 min at 69 km altitude.
In this paper, an optically transparent ultra-wideband electromagnetic absorber (EMA) is designed using indium tin oxide (ITO) film. To achieve a transparent property, the traditional dielectric substrate and copper are replaced by polyethylene terephthalate (PET) and ITO film. The ultra-wideband absorbing is achieved through the combination of multilayer periodic ITO structures etched on flexible PET layers. The simulation results show that the design can absorb EM waves in the frequency range of 3.72-42.42 GHz (relative bandwidth 165.75%), while its overall thickness is only 0.669λ0 (λ0 is the wavelength at the center frequency of EMA). The design also has the property of polarization insensitive and angular stability. Finally, the absorber is fabricated and measured to prove the effectiveness.
Victor Emmanuel Pierre Lopez, Lawrence Dale Thomas
A complexity metric is proposed for the quantification of system complexity using information about the composition of a system and its interactions depicted in a System Modelling Language (SysML) model. The proposed metric is adapted from the complexity metric developed for design structure matrix (DSM) applications and was modified to allow the metric to be applied at different decomposition levels and to accommodate the inclusion of external interactions. The metric was applied to three case studies: a Mars lander, a CubeSat and a spacecraft thermal control system. The proposed metric attributed a higher amount of complexity due to the interactions compared to the DSM metric. This variance resulted in instances where the results differed for the two metrics. Despite these differences, both metrics behaved similarly to changes in component or interaction complexity.
Problem. The global automotive industry has already had an experience of recovery from
the global financial crisis of 2008, but the pandemic crisis of 2020 is quite different in nature and pattern
of progress: in recent history it has had no analogues and it will be premature to state its completion.
Therefore, it is important to determine the impact of the pandemic on the production and sale of cars in
order to overcome the negative consequences. To address this issue, the article identifies the sensitivity
of this subsector of mechanical engineering to destructive changes in the environment; an analysis of
changes in the volume of production and sales of cars by countries of the world over the past period has
been made. Goal. The aim of the work is to determine the destructive consequences and trends of the
COVID-19 pandemic impact on the global automotive industry, namely the production and sale of cars.
Methodology. To determine the impact of the COVID-19 pandemic, a vertical and horizontal analysis
of car production and sales in the world has been conducted. Results. The results of the analysis allowed
the authors to group the countries of the world by the destructive effects of the pandemic crisis of 2020
for the automotive industry. Originality. The carried out classification of countries by the destructive
effects of the COVID-19 pandemic provided an opportunity to gain insight into its impact on the
automotive industry, in particular on the production and sale of cars. Practical value. The obtained
results can be recommended to identify further ways to overcome the negative effects of the COVID-19
pandemic in the automotive industry.
Aleksandrs Urbahs, Sergey Kravchenko, Margarita Urbaha
et al.
The paper presents the air-launch system enabling the delivery of small satellites into low Earth orbit. One of the most important advantages of the concept is its cost. Generally, the paper proves that launching a carrier from an aerial platform (a movable launch pad) provides the whole range of competitive advantages. In particular, the total losses during the launch from an aerial platform will reduce by 20–35%, and the characteristic velocity of the maneuver will reduce by 4–7%.
Aiming at the low matching accuracy of local stereo matching algorithm in weak texture or discontinuous disparity areas, a stereo matching algorithm combining multi-scale fusion of convolutional neural network (CNN) and feature pyramid structure (FPN) is proposed. The feature pyramid is applied on the basis of the convolutional neural network to realize the multi-scale feature extraction and fusion of the image, which improves the matching similarity of the image blocks. The guide graph filter is used to quickly and effectively complete the cost aggregation. The disparity selection stage adapts the improvement dynamic programming algorithm to obtain the initial disparity map. The initial disparity map is refined so as to obtain the final disparity map. The algorithm is trained and tested on the image provided by Middlebury data set, and the result shows that the disparity map obtained by the algorithm has good effect.
After many hardships,it has become the consensus of the domestic aviation industry that we must strive to promote the construction of the operation support capacity of civil aircraft manufacturers.Based on the longterm follow-up and limited participation in the operation practice of several domestic civil aircraft,the views on several problems in the operation support capacity building of domestic civil aircraft manufacturing enterprises are expoun ded in this paper.The importance of“operation support technology”in the construction of“operation support capability”is analyzed,it is proposed to cultivate spare parts market through“minimum replaceable parts”decomposition to reduce cost,provide value-added service for user product operation by adding“new skills”training demand,promote manual compilation technology update and add new highlights for domestic civil aircraft operation support.It is hoped that based on the discussion of operation support capacity building of civil aircraft manufacturers,it can promote their technical development and promote the application of relevant ideas in the field of civil aircraft,so as to meet the major national needs and engineering practice.