Abstract: In unmanned aerial vehicle (UAV) applications, the performance of simultaneous localization and mapping (SLAM) systems often degrades under high-frequency vibrations induced by airflow and wind disturbances, which can corrupt LiDAR measurements and lead to pose estimation drift or even complete system failure. To address this challenge, this paper proposes a graph optimizationbased multi-keyframe SLAM method designed to enhance robustness and accuracy under strong vibration conditions. Unlike conventional approaches that align the current frame only with the most recent keyframe, the proposed method aligns each LiDAR frame with multiple historical keyframes to construct a factor graph. Each alignment is modeled as a relative pose constraint between nodes, while an adaptive weighting strategy based on spatial distance and temporal interval dynamically balances the contributions of different keyframes. Global pose optimization is then performed within a non-linear least squares framework using the Gauss–Newton method. Experimental results on the NTU VIRAL dataset demonstrate that the proposed method significantly reduces both trajectory and rotational errors compared with LeGO-LOAM, achieving improvements of up to 71% and 84% in position and orientation accuracy, respectively. Furthermore, real-world UAV experiments validate the effectiveness and reliability of the proposed approach, showing stable and accurate mapping performance even under rapid aerial motion and external disturbances.

Abstract: Unmanned aircraft system traffic management (UTM) frameworks from multiple international initiatives define essential services but remain deliberately non-prescriptive about how architectures should be implemented, how multiple providers should be federated, and how performance should be validated under high-density operations. This research investigated the operational performance of single-provider versus federated multi-provider UTM configurations through controlled simulation experiments. We designed and implemented a modular five-layer UTM experimental framework that includes strategic planning, tactical deconfliction, safety monitoring, identity and security, and federation interfaces, aligned with current UTM concepts and service definitions. A discrete-event simulation instantiated this framework to evaluate system performance across different traffic demand levels (20, 60, and 100 flights per hour) and communication delay conditions (0.2, 1.0, and 5.0 seconds) under both federated and non-federated configurations. Experimental results showed that federation performance depends on the operating regime. At high demand with moderate delay (100 flights per hour and 1.0 second delay), federation reduced mean conflicts by 34% (from 44.0±2.9 to 29.0±11.0) and improved safety scores from 0.637 to 0.818 through coordinated intent planning. In contrast, at low demand with minimal delay (20 flights per hour and 0.2 second delay), federation overhead increased conflicts by roughly a factor of four (from 0.33±0.47 to 1.33±1.89), while safety scores remained high (above 0.96). These findings quantify the operational envelope in which multi-provider coordination provides a net benefit and establish empirical baselines for deployment and policy decisions in federated UTM ecosystems.

Abstract: Experimental and simulation studies on fluid transport system are seldom discussed in the open literature. Nevertheless, the insights and data derived from such research can significantly mitigate the scarcity of health data from real-world systems, thereby facilitating the development of advanced physics-based and data-driven algorithms. This study employs a test rig located at the IVHM Centre, Cranfield University, for experimental investigations. Based on the experimental results, an almost entirely data-driven simulation model was developed. Additionally, a case study was conducted to validate the capability of the developed simulation model and its benchmark data in supporting the creation of machine learning based fault diagnosis algorithms. The findings from this work have potential applications for a broad audience, including researchers and scholars in the fields of fluid transport system analysis, fault diagnosis, and data-driven classification algorithms.

Abstract: The development of prospective inner and outer space economies focuses on the use of bunch of small space vehicles operated as a quasi-single artificial organism. Such economies include the need for using swarms of small satellites providing communication and surveillance services, being a distributed materials production plant in space, or performing research expedition to study the resources and environments of the new worlds. The use of multiple space vehicles performing tasks as a quasi-single system makes the execution of such missions resilient by reducing the failure risks that is higher for the single-vehicled mission, especially performed in deep space. The core technology for operating distributed space systems is propulsion. From a variety of propulsion technologies ranging from the use of the pressurized cold gas to the implementation of laser beams destroying the surface of solid propellants to generate thrust, some stands out for small spacecraft applications. In this work, the summary on the space-operated propulsion is provided by highlighting the impetus of more frequent use of one technology over other. The discussion on the trends in propulsion is supported by the discussion on the physical, engineering, production, operational, and societal rationales overview. This review serves as the mean for reevaluating of the global propulsion trends and guiding the future inner and outer space propulsion assisting economies effective development.

Abstract: Traveling wave ultrasonic motors (TWUMs) are critical components in precision systems, their performance is susceptible to degradation under dynamic disturbances in harsh operating environments. This paper presents a monolithic U-shaped rotor designed to intrinsically achieve quasi-zero stiffness (QZS). Unlike conventional QZS systems that rely on assembling discrete positive and negative stiffness elements, the proposed design generates the target mechanical characteristic through the tailored nonlinear response of a unified U-shaped structure, thereby improving preload stability. Through exploring the critical parameters of the rotor cross-section, the finite element method (FEM) is employed to optimize the geometry configuration and characterize the mechanical performances. Simulation results show that the QZS behavior, demonstrating a stable force plateau of 320 ± 10 N across a 0.7 mm displacement range. A maximum von Mises stress of 788 MPa is obtained, well within the material's safety margin, thereby ensuring the structural integrity. Experimental tests validate the effectiveness of the proposed design. This compact, monolithic U-shaped rotor provides a robust and reliable QZS solution, demonstrating significant potential for enhancing the stability of TWUMs in applications prone to harsh environments such as extreme high and low temperatures, thermal cycling conditions, shock environments.

Abstract: In this paper, we explore the feasibility of deriving a simple, physically meaningful, andcompact formulation for the pressure distribution and lift of an asymmetric delta wing athigh angles of attack with an attached shock wave. Such a model would be valuable forrapid engineering analysis. Our approach begins with a compact pressure approximationin the linear regime, which is then extended to the nonlinear case through a geometrictransformation and the assumption of functional similarity between linear and nonlinearsolutions. This method bridges the solution in the central nonuniform flow region tothe exact solutions in the uniform flow regions near the leading-edge shock waves , in amanner analogous to methods used for supersonic starting flow. The model is shown to reproduce existing results for both symmetric and yawed delta wings within an acceptable error margin, providing a compact explicit expression for the normal force coefficient as a weighted average of pressure coefficients from the two uniform flow regions. Additionally, weoutline how the approach may be extended to the upper surface, where the uniform flowis described by swept Prandtl-Meyer relations.

Abstract: Propulsion systems aboard small satellites assisting dynamic space missions at the proximity of deep space natural objects may face challenges in long-term non-serviceable operations, achieving thrust vector direction control, and adapting to severe environmental conditions. The proposed solution involves using pulsed plasma thrusters with multiple spark plugs for uniform ignition and thrust vector control, enhancing reliability and efficiency of propulsion system. Key advantages of the use of such an approach include minimal power consumption, efficient volume utilization, and enhanced reliability through redundant ignition points. Experimental validation confirms the effectiveness of the proposed architecture, demonstrating uniform ignition patterns and capability of thrust vector adjustment. It can be supposed that this approach supports the viability of small satellites in future deep space missions, promising dynamic, resilient, and reusable proliferated space systems.

Abstract:

In recent years, the trend toward spacecraft miniaturization has led to the widespread adoption of micro- and nanosatellites, driven by their reduced development costs and simplified launch logistics. Operating these platforms in coordinated fleets, or swarms, represents a promising approach to overcoming the inherent limitations of individual spacecraft by distributing sensing and processing capabilities across multiple units. For systems of this scale, decentralized guidance and control architectures based on so-called behavioral strategies offer an attractive solution. These approaches are inspired by biological swarms, which exhibit remarkable robustness and adaptability through simple local interactions, minimal information exchange, and the absence of centralized supervision. This work investigates the feasibility of autonomous swarm maintenance under the stringent sensing and computational constraints typical of nanosatellite platforms. Each spacecraft is assumed to carry a single monocular camera aligned with the along-track direction. The proposed behavioral control framework enables decentralized formation keeping without ground intervention or centralized coordination. Since control actions rely on the relative motion of neighboring satellites, a lightweight relative navigation capability is required. The results indicate that complex vision pipelines can be replaced by simple blob-based image processing, although accurate reconstruction of relative parameters remains essential to avoid unnecessary control effort arising from suboptimal guidance decisions.

Abstract: Composite wing structures are widely used in unmanned aerial vehicles (UAVs) because of their high specific strength and stiffness, but they are vulnerable to localized impact events such as tool drops, runway debris and small bird or drone strikes. In many aerospace applications, carbon fiber–reinforced polymers (CFRP) are preferred for their high stiffness and weight efficiency, although they tend to fail in a brittle manner and are expensive. E-glass fiber composites, on the other hand, are tougher and cheaper, but usually considered less competitive in stiffness and impact resistance. This study numerically investigates the impact resistance of optimized E-glass fiber composite UAV wing skins compared with aerospace-grade carbon fiber skins, both supported by balsa-wood cores. A 3D finite element (FE) model of a 600 mm semi-span UAV wing segment was developed in Abaqus/Explicit, with a user-defined VUMAT implementing an orthotropic elastic law and a Hashin-type progressive damage model. A rigid spherical impactor (radius 8 mm) with various mass velocity combinations (0.5 kg at 5000 and 10 000 mm/s, and 1.0 kg at 20 000 mm/s) was used to represent low, medium and high energy impacts. E-glass material sets were defined and gradually improved, within realistic mechanical limits derived from published E-glass/epoxy systems, until a “maximum experimental limit” E-glass configuration was obtained. This optimized E-glass wing skin was then compared with carbon-fiber configurations taken as benchmark aerospace. The comparison is based on peak contact force, penetration or non-penetration, absorbed energy, and damage extent in the skin and sub-structure. The study also proposes a coupon- and sub-component-level experimental programme to validate the numerical predictions using drop-weight impact tests on E-glass and carbon-fiber laminates and on a scaled UAV wing segment. These findings indicate that suitably engineered E-glass composites can be a viable, cost-effective alternative to carbon fiber for impact-resistant UAV wing structures.

Abstract: Drag reduction forms a key area of focus in aerodynamics with a significant emphasis on delaying the laminar to turbulent transition of boundary layers over the wing of aircraft. There is enough evidence to suggest that achieving such transition delays is particularly challenging for backward swept wings with large leading edge sweep angles, which give rise to crossflow and attachment line instabilities, in addition to the Tollmien-Schlichting waves. The sustenance of extended laminar flow regions at high sweep angles has been demonstrated in recent studies, by designing airfoils with specially curated leading edge profiles, which generate pressure distributions that can suppress crossflow. Such airfoils are called Crossflow Attenuating Natural Laminar Flow (CATNLF) airfoils. However, the design of such airfoils is presently restricted to inverse methodologies due to the inability of the conventional geometry parameterization techniques in representing the specialized leading edge profiles of CATNLF airfoils. The aim of this study is to illustrate that a parametric representation of CATNLF airfoils can be realized using Bezier curves, thereby enabling their forward multi-point design using gradient-free Bayesian optimization. The developed design framework in terms of geometry parameterization and optimization formulation is able to deliver airfoils that can sustain natural laminar flow up to around 50% chord length on the upper surface, with a leading edge sweep angle greater than 27 degrees at a Mach number of 0.78 and a Reynolds number of 20 million within a range of lift coefficients Cl = 0.5 ± 0.1, making them a suitable design choice for a medium-range transport aircraft.

Abstract: In this paper a folding wing based on gear meshing deformation mechanism is developed, focusing on structural analysis and further optimization of the folding wing. Compared with existing folding wing concepts, the deformation mode of this wing is easier to manufacture and implement in engineering. A dynamic contact finite element model of gear meshing is established in ABAQUS, achieving the transmission of motion. The meshing simulation on the gear pair and dynamic strength analysis on the gear mechanism is conducted to obtain stress analysis. The results shows that the mechanism meets the strength requirements. Further dynamic numerical simulations are conducted on the outboard wing to determine the hazardous area of the load, indicating that the folding wing meets the strength requirements. At the same time, the analysis is conducted on the displacement at the tip of the outboard wing, indicating that the folding motion is relatively gentle. Finally, based on the stress analysis results, a weight reduction topology design is carried out for the spoke area of the gear and the rib structure of the folding wing using the variable density method. While ensuring strength, the optimal distribution of materials is sought by using as little material as possible, and the model is reconstructed according to the optimization results. The optimization results show that the weight reduction effect is significant.

Abstract: The engine system requirements for different engine cycles significantly influence the design of the mixing head. A literature review of fuel-injection technology for hydro-gen and methane is presented. The literature review aimed to answer proposed questions specific to the liquid rocket engine fuel injector design. The current review methodology accounts for the engine system effect. Thus, a comprehensive literature review of the working principles of startup-staged combustion cycle engines based on original patents is provided. At the end of the review, the research gaps and suggestions for further work are summarised. At high mass flow rate and injection pressure in the supercritical regime (> 50 MPa), experience is limited to the staged combustion cycle developed in Russia and the US. It is necessary to consider a fluid-dynamic heat transfer coupling study for the multi-injection element design in the supercritical state. Cryogenic spray atomisation experiments need to be designed with research significance. It is still needed to study how the similarity of the spray flow field to the combustion performance affects a liquid rocket engine problem. Moreover, scaling stoichiometric mixing theory needs to be expanded to different injector types, such as tri-coaxial and pintle injectors, to validate the correlation between the nonreactive mixing length and flame length.

Abstract: In low-Earth-orbit (LEO) satellite networks, the requirement for intelligent parameter-adjustment strategies has become increasingly critical due to the presence of highly dynamic channel conditions, limited spectrum resources, and complex interference environments. In this paper, a method for optimizing LEO satellite communication links based on deep reinforcement learning (DRL) is proposed. Through the optimization of the transmit power, the modulation and coding scheme (MCS), the beamforming parameters, and the retransmission mechanisms, adaptive link control is achieved in dynamic operational scenarios. A multidimensional state space is constructed, within which the channel state information, the interference environment, and the historical performance metrics are integrated. The spatio-temporal characteristics of the channel are extracted by means of a hybrid neural architecture that incorporates a convolutional neural network (CNN) and a long short-term memory (LSTM) net-work. To effectively accommodate both continuous and discrete action spaces, a hybrid DRL framework that combines proximal policy optimization (PPO) with a deep Q-network (DQN) is employed, thereby enabling cross-layer optimization of the physical-layer and link-layer parameters. The results demonstrate that substantial improvements in throughput, bit error rate (BER), and transmit-power efficiency are achieved under severely time-varying channel conditions, which provides a new idea for resource management and dynamic-environment adaptation in satellite communication systems.

Abstract: Ice accretion along aircraft leading edges, particularly at stagnation line parting strips, remains difficult to remove using conventional electrothermal anti-icing systems. These systems require continuous high-power heating to maintain the stagnation region above the melting point, often exceeding 10–12 kW/m². This study introduces an Ice Cavitation Deicer (ICD) that removes ice through rapid, localized cavitation generated within a thin melt layer formed at the ice–surface interface. In the proposed approach, a short pulse of electric current melts a 1–10 µm interfacial layer and causes a cavitation impulse of approximately 1–10 MPa. This impulse ejects the stagnation line ice in a direction normal to the surface, often against the external airflow, enabling the immediate aerodynamic removal of the remaining ice. Analytical modeling based on the energy conservation principle was used to determine the optimal foil geometry, thermal pulse parameters, thermal stress, and material selection. Experiments with various metallic foils and substrate materials validated the predicted ejection behavior. Compared with conventional thermal anti-icing, the ICD concept reduces power consumption by approximately two orders of magnitude while offering rapid and reliable leading-edge deicing.

Abstract: This work presents the development, modelling, integration, and validation of a flight control system (FCS) designed to convert a piloted ultra-light aircraft (ULM) into a fully autonomous vertical take-off and landing (VTOL) unmanned aerial vehicle (UAV), while maintaining Optionally Piloted Vehicle (OPV) capability. Unlike conventional ULM autopilots focused mainly on stabilization or pilot assistance, the proposed architecture enables full mission-phase autonomy, including take-off, hover, transition, cruise, approach, and landing, and ensures safe coexistence between autonomous and manual control pathways. A high-fidelity simulation framework was developed in MATLAB/Simulink and Simscape, integrating aerodynamic models derived from XFLR5 and VSPAERO, structural and inertia modelling, propulsion and energy-storage dynamics, and the complete cascaded control structure. Hardware-in-the-Loop (HIL) experiments were conducted using a modular test bench featuring a six-degree-of-freedom force–moment balance and an internal-combustion propulsion unit, allowing the injection of realistic vibration signatures into the control loop. Results demonstrate robust tracking of attitude and angular-rate commands under significant perturbations and AHRS measurement noise, indicating the system’s readiness for initial VTOL flight tests and subsequent transition-mode refinement. Overall, the paper details the control architecture, modelling methodology, simulation environment, and preliminary ground-testing efforts supporting advancement toward Technology Readiness Level 6.

Abstract: Commercial supersonic passenger transport has been absent from global aviation for more than two decades, largely due to regulatory, geographic, and economic constraints. While renewed interest in supersonic travel has emerged with advances in aircraft design, there remains a lack of scalable methods for assessing where such operations could be viable. This study evaluates supersonic feasibility at the route level using a data-driven framework that integrates engineering, regulation, and economics. A global dataset comprising 435 city-pair routes was constructed using aircraft performance estimates, great-circle routing, over-water routing fractions, and demand indicators derived from population and gross domestic product data. Routes were labeled as feasible or unfeasible based on domain-informed criteria, and supervised machine-learning models were trained to learn a continuous feasibility score between 0 and 1. A Decision Tree classifier was used to extract interpretable feasibility rules, while an Extreme Gradient Boosting (XGBoost) classifier provided predictive performance. Model behavior was analyzed using SHapley Additive exPlanations (SHAP). The results show that over-water routing fraction is the dominant determinant of feasibility, followed by time savings and great-circle distance, with demand contributing in marginal cases. The framework produces a ranked set of candidate routes as well as a predictive engine for future routes.

Abstract: Traditional reliability engineering paradigms, originally designed to prevent physical component failures, are facing a fundamental crisis when applied to today's soft-ware-intensive and autonomous systems. In critical domains like aerospace, the dom-inant risks no longer stem from the aleatory uncertainty of hardware breakdowns, but from the deep epistemic uncertainty inherent in complex systematic interactions and non-deterministic algorithms. This paper reviews the historical evolution of reliability engineering, tracing the progression through the Statistical, Physics-of-Failure, and Prognostics eras. It argues that while these failure-centric frameworks perfected the management of predictable risks, they are structurally inadequate for the "unknown unknowns" of modern complexity. To address this methodological vacuum, this study advocates for an imperative shift towards a fourth paradigm: the Resilience Era. Grounded in the principles of Safety-II, this approach redefines the engineering objec-tive from simply minimizing failure rates to ensuring mission success and functional endurance under uncertainty. The paper introduces Uncertainty Control (UC) as the strategic successor to Uncertainty Quantification (UQ), proposing that safety must be architected through behavioral constraints rather than prediction alone. Finally, the paper proposes a new professional identity for the practitioner: the system resilience architect, tasked with designing adaptive architectures that ensure safety in an era of incomplete knowledge.

Abstract: Drones have long been explored for supply. While several systems offering small pay-loads in drone delivery have seen operational use, large-scale supply drones have yet to be adopted. A range of setbacks cause this, including technological and operational challenges that hinder their adoption. Here, these challenges are evaluated from a conceptual modelling perspective to forecast their applicability once these barriers are overcome. The study uses technology trend modelling and bibliometric activity map-ping methodologies to predict the applicability of specific technologies that are cur-rently identified as operational challenges. Specifically for supply drones, trends in technological improvements of battery technology and aircraft control are modelled to project effects and focus on landing zone autonomy and powertrain. The prediction also focuses on the current state of hybrid power and higher levels of automation required for landing zone operations. These models are validated through several published case studies of small delivery drones and then applied to assess the feasibility and con-straints of larger supply drones. A case study, conceptual design of a supply drone large enough to move a shipping container, is presented to illustrate the critical technologies required to transition large supply drones from concept to operational reality. Key technologies required for large-scale supply drones have yet to build up a critical mass of research activity, particularly on landing zone autonomy and powertrain. Moreover, additional constraints beyond technological and operational challenges could include limitations in autonomy, certification hurdles, regulatory complexity, and the need for greater social trust and acceptance.

Abstract: Very Low Earth Orbit (VLEO) satellites, operating at altitudes below 450km, provide tremendous potential in the domain of remote sensing. Their proximity to Earth of-fers high resolution, low latency, and rapid revisit rates, allowing continuous moni-toring of dynamic systems and real-time delivery of vertically integrated earth ob-servation products. Nonetheless, the application of VLEO is not yet fully realized due to numerous complexities associated with VLEO satellite development, considering atmospheric drag, short satellite lifetimes, and social, political and legal regulatory fragmentation. This paper reviews the recent technological developments supporting sustainable VLEO operations with regards to aerodynamic satellite design, atomic oxygen barriers, and atmospheric-breathing electric propulsion (ABEP). Furthermore, the paper pro-vides an overview of the identification of regulatory and economic barriers that extort additional costs for VLEO ranging from frequency band allocation and space traffic management to life-cycle cost and uncertain commercial demand opportunities. Nevertheless, the commercial potential of VLEO operations is widely acknowledged, and estimated to lead to an economic turnover in the order of 1.5 B$ by 2030. Learning from the literature and prominent past experiences such as the DISCOVERER and the CORONA program, the study identifies key gaps and proposes a roadmap to sustainable VLEO development. The proposed framework emphasizes modular and serviceable satellite platforms, hy-brid propulsion systems, and globally harmonized governance in space. Ultimately, public-private partnerships and synergies across sectors will determine whether VLEO systems become part of the broader space infrastructure unlocking new capabilities for near-Earth services, environmental monitoring, and commercial innovation at the edge of space.

Abstract: This study introduces an all-fiber optic sensing network based on fiber Bragg grating (FBG) technology for structural health monitoring (SHM) of launch vehicle payload fairings un-der extreme thermo-mechanical conditions. A wavelength–space dual-multiplexing ar-chitecture enables full-field strain and temperature monitoring with minimal sensor de-ployment. Structural deformations are reconstructed from local measurements using the inverse finite element method (iFEM), achieving sub-millimeter accuracy. High-temperature experiments verified that FBG sensors maintain a strain accuracy of 0.8 με at 500 °C, significantly outperforming conventional sensors. Under 15 MPa mechanical loading and 420 °C thermal shock, the fairing structure exhibited no damage propagation. The sensing system captured real-time strain distributions and deformation profiles, con-firming its suitability for aerospace SHM. The combined use of iFEM and FBG enables high-fidelity, large-scale deformation reconstruction, offering a reliable solution for reusa-ble aerospace structures operating in harsh environments.